FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Volz, MP Mazuruk, K AF Volz, MP Mazuruk, K TI An experimental study of the influence of a rotating magnetic field on Rayleigh-Bernard convection SO JOURNAL OF FLUID MECHANICS LA English DT Article ID VERTICAL BRIDGMAN CONFIGURATIONS; SINGLE-CRYSTAL GROWTH; LIQUID-METAL; THERMOCONVECTIVE INSTABILITY; NUMERICAL-SIMULATION; NATURAL-CONVECTION; FLUID-FLOW; MELT; STABILITY; CYLINDERS AB A destabilizing vertical temperature gradient and a rotating magnetic field have been applied to a cylindrical column of liquid gallium. The convective flows which arise as a function of these parameters are identified. For small magnetic field strengths, a regime of stationary flow is observed. This regime is bounded by critical values of the Rayleigh and magnetic Taylor numbers. As the rotating magnetic field is increased, the critical Rayleigh number can increase by more than a factor of 10. The rotating magnetic field itself induces an instability at a critical value of the magnetic Taylor number independent of the Rayleigh number. The nature of the bifurcations (whether subcritical or supercritical) and the convective flows occurring at the critical Rayleigh numbers are dependent upon the magnetic Taylor number. For small magnetic Taylor numbers, the experimental observations are consistent with the occurrence of a single asymmetric meridional roll which is driven around the cylinder by the rotating magnetic field. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Volz, MP (reprint author), NASA, George C Marshall Space Flight Ctr, SD47, Huntsville, AL 35812 USA. NR 42 TC 24 Z9 24 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI PORT CHESTER PA 110 MIDLAND AVE, PORT CHESTER, NY 10573-9863 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD OCT 10 PY 2001 VL 444 BP 79 EP 98 PG 20 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 479RC UT WOS:000171416500004 ER PT J AU Miller, CE Cohen, EA AF Miller, CE Cohen, EA TI Rotational spectroscopy of 10 (XIIi)-I-2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID ELECTRON RESONANCE SPECTRA; DIATOMIC-MOLECULES; MICROWAVE-SPECTRUM; IODINE OXIDE; PHOTOELECTRON-SPECTROSCOPY; GROUND-STATE; SPIN-ORBIT; IO; BRO; PARAMETERS AB Pure rotational spectra of the IO radical have been observed for vibrational levels up to v =13 in the X-1 (2)Pi (3/2) state and up to v =9 in the X-2 (2)Pi (1/2) state. Isotopically enriched (IO)-O-18 rotational spectra have been observed for vibrational levels up to v = 5 in both the X-1 and X-2 states. These are the first high-resolution spectra of any kind reported for the X-2 state and greatly extend the available data for the X-1 state. The data for both isotopomers have been fitted simultaneously to a single set of (2)Pi parameters with fixed isotopic ratios. The isotope relations among the parameters have provided a means of decorrelating the electron spin-rotation constant gamma from the fine-structure centrifugal distortion constant, A(D), and have allowed the first determination of an effective value for gamma. The rotation-vibration constants correspond to the equilibrium molecular properties r(e)(X-1) =186.762 pm, r(e)(X-2)=188.468 pm, omega (e)(X-1)=681.69 cm(-1), and omega (e)(X-2)=645.29 cm(-1). These constants have been used to calculate X-1 and X-2 Rydberg-Klein-Rees potentials encompassing energies up to 40% of the dissociation limit. A complete set of hyperfine coupling constants has been determined for the first time and interpreted using appropriate relativistic atomic radial integrals. (C) 2001 American Institute of Physics. C1 Haverford Coll, Dept Chem, Haverford, PA 19041 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Miller, CE (reprint author), Haverford Coll, Dept Chem, Haverford, PA 19041 USA. NR 46 TC 25 Z9 25 U1 1 U2 4 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 8 PY 2001 VL 115 IS 14 BP 6459 EP 6470 DI 10.1063/1.1398308 PG 12 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 480RK UT WOS:000171475800025 ER PT J AU Partridge, H Stallcop, JR Levin, E AF Partridge, H Stallcop, JR Levin, E TI Potential energy curves and transport properties for the interaction of He with other ground-state atoms SO JOURNAL OF CHEMICAL PHYSICS LA English DT Review ID CORRELATED MOLECULAR CALCULATIONS; AB-INITIO CALCULATIONS; GAUSSIAN-BASIS SETS; COUPLED-CLUSTER THEORY; LOWEST EXCITED-STATES; DER-WAALS INTERACTION; BINARY GAS MIXTURES; OPEN-SHELL SYSTEMS; RARE-GAS; CROSS-SECTIONS AB The interactions of a He atom with a heavier atom are examined for 26 different elements, which are consecutive members selected from three rows (Li-Ne, Na-Ar, and K,Ca, Ga-Kr) and column 12 (Zn, Cd) of the Periodic Table. Interaction energies are determined using high-quality ab initio calculations for the states of the molecule that would be formed from each pair of atoms in their ground states. Potential energies are tabulated for a broad range of interatomic separation distances. The results show, for example, that the energy of an alkali interaction at small separations is nearly the same as that of a rare-gas interaction with the same electron configuration for the closed shells. Furthermore, the repulsive-range parameter for this region is very short compared to its length for the repulsion dominated by the alkali-valence electron at large separations (beyond about 3-4 a(0)). The potential energies in the region of the van der Waals minimum agree well with the most accurate results available. The ab initio energies are applied to calculate scattering cross sections and obtain the collision integrals that are needed to determine transport properties to second order. The theoretical values of Li-He total scattering cross sections and the rare-gas atom-He transport properties agree well (to within about 1%) with the corresponding measured data. Effective potential energies are constructed from the ab initio energies; the results have been shown to reproduce known transport data and can be readily applied to predict unknown transport properties for like-atom interactions. (C) 2001 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Eloret Corp, Moffett Field, CA 94035 USA. RP Partridge, H (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 104 TC 78 Z9 81 U1 2 U2 14 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 8 PY 2001 VL 115 IS 14 BP 6471 EP 6488 DI 10.1063/1.1385372 PG 18 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 480RK UT WOS:000171475800026 ER PT J AU Farhat, S de La Chapelle, ML Loiseau, A Scott, CD Lefrant, S Journet, C Bernier, P AF Farhat, S de La Chapelle, ML Loiseau, A Scott, CD Lefrant, S Journet, C Bernier, P TI Diameter control of single-walled carbon nanotubes using argon-helium mixture gases SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID ELECTRIC-ARC TECHNIQUE; HYDROGEN ADSORPTION; LARGE-SCALE; CATALYTIC GROWTH; GRAPHENE TUBULES; PARTICLES; HYDROCARBONS; MICROTUBULES; TEMPERATURE; ENERGETICS AB A method is reported for controlling the diameter of single-walled carbon nanotubes (SWCNTs) during the electric-arc-discharge process. Using argon as inert atmosphere provides smaller diameters as compared with those when pure helium is used. Varying the gas mixture from argon to helium changes the diameter distribution to higher values. A linear fit of the average diameter shows a 0.2 Angstrom diam decrease per 10% increase in the argon-helium ratio. (C) 2001 American Institute of Physics. C1 Univ Paris 13, LIMHP, F-93430 Villetaneuse, France. Off Natl Etud & Rech Aerosp, LEM, F-92322 Chatillon, France. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Nantes, IMN, F-44322 Nantes 3, France. Univ Lyon 1, DPM, F-69622 Villeurbanne, France. Univ Montpellier 2, GDPC, F-34095 Montpellier 5, France. RP Univ Paris 13, LIMHP, Ave JB Clement, F-93430 Villetaneuse, France. EM farhat@limhp.univ-paris13.fr NR 43 TC 54 Z9 55 U1 0 U2 7 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-9606 EI 1089-7690 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 8 PY 2001 VL 115 IS 14 BP 6752 EP 6759 DI 10.1063/1.1390526 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 480RK UT WOS:000171475800055 ER PT J AU Folkner, WM AF Folkner, WM TI LISA orbit selection and stability SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 3rd International LISA Symposium CY JUL 11-14, 2000 CL MAX PLANCK INST GRAVITAT PHYS, GLOM, GERMANY SP European Space Agcy, NASA HO MAX PLANCK INST GRAVITAT PHYS AB The LISA mission involves three spacecraft separated by 5 X 10(6) km. Each spacecraft needs to be able to point at the other spacecraft in order to transmit and receive laser signals to each other. The initial beam acquisition process is dependent on the pointing accuracy of the spacecraft, the laser beam width and the knowledge of the directions to the other spacecraft. The directions from one spacecraft to another will be determined by tracking radio signals from each spacecraft independently by Earth tracking stations. An analysis of the position determination estimation is described here. Using conventional Doppler and range information, the relative angular positions of each spacecraft can be determined to better than 1 mu rad (0.2 aresec), which is less than the laser beamwidth. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Folkner, WM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 3 Z9 3 U1 1 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD OCT 7 PY 2001 VL 18 IS 19 BP 4053 EP 4057 DI 10.1088/0264-9381/18/19/312 PG 5 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 485JX UT WOS:000171752200013 ER PT J AU Armstrong, JW Estabrook, FB Tinto, M AF Armstrong, JW Estabrook, FB Tinto, M TI Sensitivities of alternate LISA configurations SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 3rd International LISA Symposium CY JUL 11-14, 2000 CL MAX PLANCK INST GRAVITAT PHYS, GLOM, GERMANY SP European Space Agcy, NASA HO MAX PLANCK INST GRAVITAT PHYS ID GRAVITATIONAL-RADIATION; SPACECRAFT MOTION AB LISA can be considered as six proof masses, pairwise Doppler tracked with one-way optical links. An appropriate combination of these one-way Doppler links can cancel the principal noise sources (laser phase noise and optical bench motion noise). Here we compute the gravitational wave sensitivities for the baseline Michelson combination and for several other LISA data combinations which also cancel the leading noise. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Armstrong, JW (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 9 Z9 9 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD OCT 7 PY 2001 VL 18 IS 19 BP 4059 EP 4065 DI 10.1088/0264-9381/18/19/313 PG 7 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 485JX UT WOS:000171752200014 ER PT J AU Hellings, RW AF Hellings, RW TI Data processing for LISA's laser interferometer tracking system (LITS) SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 3rd International LISA Symposium CY JUL 11-14, 2000 CL MAX PLANCK INST GRAVITAT PHYS, GLOM, GERMANY SP European Space Agcy, NASA HO MAX PLANCK INST GRAVITAT PHYS AB In this paper, we present results on the subject of data processing for LISA. We present, for the first time, time-domain algorithms for the elimination of clock jitter noise algorithms that avoid the singularities of the previous frequency-domain method. We also discuss how to generate the data averages that each spacecraft will eventually need to telemeter to the ground, thereby inferring what a realistic scientific data rate will be for LISA. Finally, we argue, based partly on these results, that a laser interferometer tracking system (LITS) that employs independent lasers in each spacecraft is preferable, for reasons of simplicity, to one in which the lasers in two of the spacecraft are locked to the incoming beam from the third. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hellings, RW (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 1 Z9 1 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD OCT 7 PY 2001 VL 18 IS 19 BP 4075 EP 4080 DI 10.1088/0264-9381/18/19/315 PG 6 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 485JX UT WOS:000171752200016 ER PT J AU Tinto, M Armstrong, JW Estabrook, FB AF Tinto, M Armstrong, JW Estabrook, FB TI Discriminating a gravitational-wave background from instrumental noise using time-delay interferometry SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article; Proceedings Paper CT 3rd International LISA Symposium CY JUL 11-14, 2000 CL MAX PLANCK INST GRAVITAT PHYS, GLOM, GERMANY SP European Space Agcy, NASA HO MAX PLANCK INST GRAVITAT PHYS ID RADIATION AB The first in-flight Doppler tracking measurements performed by LISA will be used to assess its detector performance. The existence of a strong stochastic background of gravitational radiation from many close binary systems in our Galaxy will prevent us from identifying the interferometer noise level in the frequency band 0.1-8 m-Hz. This in turn will prevent us from making an unambiguous detection of the background itself. By implementing the proposed multiple Doppler readouts, it is possible to generate several observables that are independent of laser phase fluctuations, and at the same time have different couplings to gravitational waves and to the various LISA instrumental noises. Comparison, for example, of the Michelson interferometer observable with the fully symmetric Sagnac data-type allows discrimination between a confusion-limited gravitational-wave background and instrumental noise. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tinto, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 5 Z9 5 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD OCT 7 PY 2001 VL 18 IS 19 BP 4081 EP 4086 DI 10.1088/0264-9381/18/19/316 PG 6 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 485JX UT WOS:000171752200017 ER PT J AU Walch, SP Bakes, ELO AF Walch, SP Bakes, ELO TI On the reaction CH2NH2++HCN/HNC -> NH2CH2CNH+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID INTERSTELLAR; ICES; MOLECULES; HYAKUTAKE; CHEMISTRY; EMISSION; SPECTRA; HCN; HNC; B2 AB We have studied the reaction of protonated methyleneimine with HCN/HNC at the B3LYP level of theory. The only low energy pathway in this system arises from HNC + CH2NH2+. This limit is 15.5 kcal/mol above HCN + CH2NH2+. Both HCN and HNC exist in the interstellar medium (ISM) and by implication in the icy grain mantles. The features of this pathway are formation of an electrostatic minimum, followed by a slight barrier leading to an NH2CH2CNH+ minimum. This pathway has no barriers above the reactants energy. Acid hydrolysis of NH2CH2CNH+ leads to glycine (NH2CH2,COOH). This work demonstrates a plausible pathway converting methyleneimine to NH2CH2CN. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, ELORET, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, SETI Inst, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Walch, SP (reprint author), NASA, ELORET, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 26 TC 10 Z9 10 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 OCT 5 PY 2001 VL 346 IS 3-4 BP 267 EP 273 DI 10.1016/S0009-2614(01)00933-2 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 481EQ UT WOS:000171507300012 ER PT J AU Bushnell, DM AF Bushnell, DM TI On (civil) aviation future(s) SO AERONAUTICAL JOURNAL LA English DT Editorial Material C1 NASA Langley Res Ctr, Hampton, VA 23601 USA. RP Bushnell, DM (reprint author), NASA Langley Res Ctr, Hampton, VA 23601 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU ROYAL AERONAUTICAL SOC PI LONDON PA 4 HAMILTON PL, LONDON W1V OBQ, ENGLAND SN 0001-9240 J9 AERONAUT J JI Aeronaut. J. PD OCT PY 2001 VL 105 IS 1052 BP 603 EP 606 PG 4 WC Engineering, Aerospace SC Engineering GA 481LQ UT WOS:000171521100006 ER PT J AU Leib, SJ Goldstein, ME AF Leib, SJ Goldstein, ME TI Sound from turbulence convected by a parallel flow within a rectangular duct SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA 39th Aerospace Sciences Meeting CY JAN 08-11, 2001 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut AB A previously derived high-frequency solution to Lilley's equation is used to study the far-field characteristics of the sound generated by a turbulent flow within a semi-infinite duct of nonaxisymmetric cross section. The source term is simplified by assuming the turbulence to be axisymmetric about the mean flow direction, and a relatively simple formula for the far-field azimuthal and polar sound field variation is obtained. The numerical computations involve the calculation of ray trajectories, and a parallel computer code has been developed for this purpose. It is expected that the code will be able to produce azimuthal directivity patterns in a few minutes on a large parallel computer system. The method has been applied to a rectangular duct, and numerical results for the azimuthal and polar variation of the sound field were computed on a cluster of workstations for a number of duct aspect ratios, wall impedances values, and source locations. C1 Ohio Aerosp Inst, Inst Computat Mech Prop, Brookpark, OH 44142 USA. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Leib, SJ (reprint author), Ohio Aerosp Inst, Inst Computat Mech Prop, Brookpark, OH 44142 USA. NR 16 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 2001 VL 39 IS 10 BP 1875 EP 1883 DI 10.2514/2.1202 PG 9 WC Engineering, Aerospace SC Engineering GA 480CV UT WOS:000171445200006 ER PT J AU Rogers, SE Roth, K Nash, SM AF Rogers, SE Roth, K Nash, SM TI Validation of computed high-lift flows with significant wind-tunnel effects SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA 18th Applied Aerodynamics Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut AB The modeling requirements for validating Navier-Stokes computations of a high-lift trapezoidal wing are investigated. This wing has a full-span slat and a full-span flap and has been tested extensively in the NASA Langley 14 x 22-ft Wind Tunnel and the NASA Ames 12-ft Pressure Wind Tunnel. Because of the size of the wing, there are significant facility effects in the data from the 12-ft wind tunnel. Computational models of the test facility of differing fidelity are developed and tested. Results are compared with experimental lift, drag, and surface pressures. In the computations a simplified, inviscid model of the test section performs as well as a high-fidelity, viscous test-section model. Computed results generally compare very well with experimental data at all but the highest angles of attack. A comparison of computational results from both free-air and wind-tunnel simulations at the same lift condition indicates that it is necessary to simulate the wind tunnel to perform validation using the 12-ft wind-tunnel experimental data. A subsequent grid-refinement study found that enhanced spanwise resolution increased the accuracy of the computed surface pressures at high angle of attack and resulted in a computed maximum lift that was 5% above the experimental value. C1 NASA, Ames Res Ctr, NAS Syst Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Aerosp Operat Modeling Off, Moffett Field, CA 94035 USA. MCAT Inc, Moffett Field, CA 94035 USA. RP Rogers, SE (reprint author), NASA, Ames Res Ctr, NAS Syst Div, Mail Stop T27B-1, Moffett Field, CA 94035 USA. NR 30 TC 9 Z9 13 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 OCT PY 2001 VL 39 IS 10 BP 1884 EP 1892 DI 10.2514/2.1203 PG 9 WC Engineering, Aerospace SC Engineering GA 480CV UT WOS:000171445200007 ER PT J AU Chandrasekhara, MS Wilder, MC Carr, LW AF Chandrasekhara, MS Wilder, MC Carr, LW TI Compressible dynamic stall control using dynamic shape adaptation SO AIAA JOURNAL LA English DT Article C1 NASA, Ames Res Ctr, React Flow Environm Branch, Moffett Field, CA 94035 USA. USN, Postgrad Sch, NASA, Joint Inst Aeronaut,Dept Aeronaut & Astronaut, Monterey, CA 93943 USA. RP Chandrasekhara, MS (reprint author), NASA, Ames Res Ctr, React Flow Environm Branch, MS 260-1, Moffett Field, CA 94035 USA. NR 4 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 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 2001 VL 39 IS 10 BP 2021 EP 2024 DI 10.2514/2.1196 PG 4 WC Engineering, Aerospace SC Engineering GA 480CV UT WOS:000171445200025 ER PT J AU Hampton, RD Quraishi, N Rupert, JK AF Hampton, RD Quraishi, N Rupert, JK TI Flexibility equations for active rack isolation system umbilicals with planar end loading SO AIAA JOURNAL LA English DT Article C1 US Mil Acad, Dept Civil & Mech Engn, W Point, NY 10996 USA. NASA, Lyndon B Johnson Space Ctr, Payloads Off, Houston, TX 77058 USA. Dynet Inc, Missile Syst Dept, Simulat & Anal Sect, Huntsville, AL 35806 USA. RP Hampton, RD (reprint author), US Mil Acad, Dept Civil & Mech Engn, W Point, NY 10996 USA. NR 19 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 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 2001 VL 39 IS 10 BP 2024 EP 2027 PG 4 WC Engineering, Aerospace SC Engineering GA 480CV UT WOS:000171445200026 ER PT J AU Yang, HX Konzett, J Prewitt, CT AF Yang, HX Konzett, J Prewitt, CT TI Crystal structure of a new (21)-clinopyribole synthesized at high temperature and pressure SO AMERICAN MINERALOGIST LA English DT Article ID STRUCTURE REFINEMENT; TRIPLE-CHAIN; BIOPYRIBOLES; PYRIBOLES; CHEMISTRY; DIOPSIDE; RICHTERITES; AMPHIBOLES; MINERALOGY; DISORDER AB A (21)-clinopyribole with the composition K1.10Na2.32Ca1.52Mg5.85Al1.23Si12.04O34(OH)(2) has been synthesized at 10 GPa and 1250 degreesC in a multi-anvil apparatus. The unit-cell parameters are a = 9.8390(9), b = 26.6471(6), c = 5.2665(5) Angstrom, beta = 106.25(5)degrees, and V = 1325.6(4) Angstrom (3). The structure (space group A2/m) consists of an alternating arrangement of single- and double-chain silicate slabs along the b axis, with a + + + + configuration. This phase possesses all the features predicted by Veblen and Burnham (1978b) for a mixed-chain silicate intermediate between pyroxenes and amphiboles. The single-chain portion of the structure corresponds to a clinopyroxene with the omphacite composition Di(55)Jd(45), whereas the double chain portion is essentially a potassic richterite. The MS2 cation in the single-chain portion occupies a coordination environment that is similar to the M4 site in richterite, whereas the MD4 cation coordination in the double-chain portion is comparable to the M2 site in C2/c omphacite. The observed unit-cell volume is 1.5% smaller than the equivalent mixture of Di(55)Jd(45) + richterite, accounting, in part, for its hi-h-pressure stability relative to its pyroxene and amphibole components. C1 Carnegie Inst Washington, Geophys Lab, Washington, DC 20015 USA. RP Yang, HX (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-301, Pasadena, CA 91109 USA. NR 35 TC 5 Z9 5 U1 0 U2 0 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 OCT PY 2001 VL 86 IS 10 BP 1261 EP 1266 PG 6 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 480CW UT WOS:000171445300013 ER PT J AU Escoubet, CP Fehringer, M Goldstein, M AF Escoubet, CP Fehringer, M Goldstein, M TI The Cluster mission - Introduction SO ANNALES GEOPHYSICAE LA English DT Editorial Material AB The Cluster mission, ESA's first cornerstone project, together with the SOHO mission, dating back to the first proposals in 1982, was finally launched in the summer of 2000. On 16 July and 9 August, respectively, two Russian Soyuz rockets blasted off from the Russian cosmodrome in Baikonour to deliver two Cluster spacecraft, each into their proper orbit. By the end of August 2000, the four Cluster satellites had reached their final tetrahedral constellation. The commissioning of 44 instruments, both individually and as an ensemble of complementary tools, was completed five months later to ensure the optimal use of their combined observational potential. On I February 2001, the mission was declared operational. The main goal of the Cluster mission is to study the small-scale plasma structures in three dimensions in key plasma regions, such as the solar wind, bow shock, magnetopause, polar cusps, magnetotail and the auroral zones. With its unique capabilities of three-dimensional spatial resolution, Cluster plays a major role in the International Solar Terrestrial Program (ISTP), where Cluster and the Solar and Heliospheric Observatory (SOHO) are the European contributions. Cluster's payload consists of state-of-the-art plasma instrumentation to measure electric and magnetic fields from the quasi-static up to high frequencies, and electron and ion distribution functions from energies of nearly 0eV to a few MeV. The science operations are coordinated by the Joint Science Operations Centre (JSOC), at the Rutherford Appleton Laboratory (UK), and implemented by the European Space Operations Centre (ESOC), in Darmstadt, Germany. A network of eight national data centres has been set up for raw data processing, for the production of physical parameters, and their distribution to end users all over the world. The latest information on the Cluster mission can be found at http://sci.esa.int/cluster/. C1 ESA, Estec, Sci So, NL-2200 AG Noordwijk, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Escoubet, CP (reprint author), ESA, Estec, Sci So, Keplerlaan 1, NL-2200 AG Noordwijk, Netherlands. NR 8 TC 368 Z9 378 U1 3 U2 22 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS-GERMANY JI Ann. Geophys. PD OCT-DEC PY 2001 VL 19 IS 10-12 SI SI BP 1197 EP 1200 PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 522AH UT WOS:000173873200002 ER PT J AU Balogh, A Carr, CM Acuna, MH Dunlop, MW Beek, TJ Brown, P Fornacon, KH Georgescu, E Glassmeier, KH Harris, J Musmann, G Oddy, T Schwingenschuh, K AF Balogh, A Carr, CM Acuna, MH Dunlop, MW Beek, TJ Brown, P Fornacon, KH Georgescu, E Glassmeier, KH Harris, J Musmann, G Oddy, T Schwingenschuh, K TI The Cluster Magnetic Field Investigation: overview of in-flight performance and initial results SO ANNALES GEOPHYSICAE LA English DT Article DE interplanetary physics; instruments and techniques; magnetospheric physics; magnetospheric configuration and dynamics; space plasma physics; shock waves ID ACCURATE DETERMINATION; NATURAL CONSTRAINTS; SPINNING SPACECRAFT; VECTOR MEASUREMENTS; GRADIENTS; SHOCK AB The accurate measurement of the magnetic field along the orbits of the four Cluster spacecraft is a primary objective of the mission. The magnetic field is a key constituent of the plasma in and around the magnetosphere, and it plays an active role in all physical processes that define the structure and dynamics of magnetospheric phenomena on all scales. With the four-point measurements on Cluster, it has become possible to study the three-dimensional aspects of space plasma phenomena on scales commeasurable with the size of the spacecraft constellation, and to distinguish temporal and spatial dependences of small-scale processes. We present an overview of the instrumentation used to measure the magnetic field on the four Cluster spacecraft and an overview the performance of the operational modes used in flight. We also report on the results of the preliminary in-orbit calibration of the magnetometers; these results show that all components of the magnetic field are measured with an accuracy approaching 0.1 nT. Further data analysis is expected to bring an even more accurate determination of the calibration parameters. Several examples of the capabilities of the investigation are presented from the commissioning phase of the mission, and from the different regions visited by the spacecraft to date: the tail current sheet, the dusk side magnetopause and magnetosheath, the bow shock and the cusp. We also describe the data processing flow and the implementation of data distribution to other Cluster investigations and to the scientific community in general. C1 Univ London Imperial Coll Sci & Technol, London, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. TU Braunschweig, IGM, Braunschweig, Germany. MPE, Garching, Germany. IfW, Graz, Austria. RP Balogh, A (reprint author), Univ London Imperial Coll Sci & Technol, London, England. RI dunlop, malcolm/F-1347-2010 NR 20 TC 889 Z9 903 U1 5 U2 34 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS-GERMANY JI Ann. Geophys. PD OCT-DEC PY 2001 VL 19 IS 10-12 SI SI BP 1207 EP 1217 PG 11 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 522AH UT WOS:000173873200004 ER PT J AU Gurnett, DA Huff, RL Pickett, JS Persoon, AM Mutel, RL Christopher, IW Kletzing, CA Inan, US Martin, WL Bougeret, JL Alleyne, HSC Yearby, KH AF Gurnett, DA Huff, RL Pickett, JS Persoon, AM Mutel, RL Christopher, IW Kletzing, CA Inan, US Martin, WL Bougeret, JL Alleyne, HSC Yearby, KH TI First results from the Cluster wideband plasma wave investigation SO ANNALES GEOPHYSICAE LA English DT Article DE ionosphere; wave-particle interactions; wave propagation; magnetospheric physics; plasma waves and instabilities; instruments and techniques ID AURORAL KILOMETRIC RADIATION; MAGNETOSPHERICALLY REFLECTED WHISTLERS; DYNAMICS EXPLORER-1; CHORUS EMISSIONS; VLF CHORUS; POLAR; PRECIPITATION; SPACECRAFT; ELECTRONS; FREQUENCY AB In this report we present the first results from the Cluster wideband plasma wave investigation. The four Cluster spacecraft were successfully placed in closely spaced, high-inclination eccentric orbits around the Earth during two separate launches in July - August 2000. Each spacecraft includes a wideband plasma wave instrument designed to provide high-resolution electric and magnetic field waveforms via both stored data and direct downlinks to the NASA Deep Space Network. Results are presented for three commonly occurring magnetospheric plasma wave phenomena: (1) whistlers, (2) chorus, and (3) auroral kilometric radiation. Lightning-generated whistlers are frequently observed when the spacecraft is inside the plasmasphere. Usually the same whistler can be detected by all spacecraft, indicating that the whistler wave packet extends over a spatial dimension at least as large as the separation distances transverse to the magnetic field, which during these observations were a few hundred km. This is what would be expected for nonducted whistler propagation. No case has been found in which a strong whistler was detected at one spacecraft, with no signal at the other spacecraft, which would indicate ducted propagation. Whistler-mode chorus emissions are also observed in the inner region of the magnetosphere. In contrast to lightning-generated whistlers, the individual chorus elements seldom show a one-to-one correspondence between the spacecraft, indicating that a typical chorus wave packet has dimensions transverse to the magnetic field of only a few hundred km or less. In one case where a good one-to-one correspondence existed, significant frequency variations were observed between the spacecraft, indicating that the frequency of the wave packet may be evolving as the wave propagates. Auroral kilometric radiation, which is an intense radio emission generated along the auroral field lines, is frequently observed over the polar regions. The frequency-time structure of this radiation usually shows a very good one-to-one correspondence between the various spacecraft. By using the microsecond timing available at the NASA Deep Space Network, very-long-baseline radio astronomy techniques have been used to determine the source of the auroral kilometric radiation. One event analyzed using this technique shows a very good correspondence between the infer-red source location, which is assumed to be at the electron cyclotron frequency, and a bright spot in the aurora along the magnetic field line through the source. C1 Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Stanford Univ, Star Lab, Stanford, CA 94305 USA. Jet Prop Lab, Pasadena, CA 91109 USA. Observ Paris, F-92195 Meudon, France. Univ Sheffield, Sheffield, S Yorkshire, England. RP Gurnett, DA (reprint author), Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. OI Kletzing, Craig/0000-0002-4136-3348 NR 56 TC 51 Z9 51 U1 0 U2 2 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS-GERMANY JI Ann. Geophys. PD OCT-DEC PY 2001 VL 19 IS 10-12 SI SI BP 1259 EP 1272 PG 14 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 522AH UT WOS:000173873200007 ER PT J AU Horbury, TS Cargill, PJ Lucek, EA Balogh, A Dunlop, MW Oddy, TM Carr, C Brown, P Szabo, A Fornacon, KH AF Horbury, TS Cargill, PJ Lucek, EA Balogh, A Dunlop, MW Oddy, TM Carr, C Brown, P Szabo, A Fornacon, KH TI Cluster magnetic field observations of the bowshock: Orientation, motion and structure SO ANNALES GEOPHYSICAE LA English DT Article DE interplanetary physics; planetary bow shocks; space plasma physics; shock waves; waves and instabilities ID QUASI-PERPENDICULAR SHOCK; EARTHS BOW SHOCK; COLLISIONLESS SHOCKS; ISEE-2 OBSERVATIONS; WAVES; IONS; SIMULATIONS; DOWNSTREAM; EVOLUTION; MIRROR AB Four spacecraft Cluster magnetic field observations of the low 6 quasi-perpendicular terrestrial bowshock are presented for the first time. Multiple quasi-perpendicular crossings on 25 December 2000 are analysed. By combining data from the four spacecraft, bowshock orientations and velocities can be calculated. It is shown that, even while in rapid motion, the bowshock normal direction remains remarkably constant, and that coplanarity estimates are accurate to, typically, around 20degrees. Magnetic field magnitude profiles are shown to be very well correlated between spacecraft although downstream waves with fluctuations perpendicular to the local field, while statistically similar at all four spacecraft, are poorly correlated on separation scales of several hundred km Examples are shown of a number of bowshock phenomena, including non-standing fluctuations in the shock foot and the shock interacting with changing solar wind conditions. C1 Univ London Imperial Coll Sci & Technol, Blackett Lab, London, England. Goddard Space Flight Ctr, Greenbelt, MD USA. Tech Univ Carolo Wilhelmina Braunschweig, D-3300 Braunschweig, Germany. RP Horbury, TS (reprint author), Univ London Imperial Coll Sci & Technol, Blackett Lab, London, England. RI dunlop, malcolm/F-1347-2010 NR 22 TC 32 Z9 32 U1 0 U2 3 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS-GERMANY JI Ann. Geophys. PD OCT-DEC PY 2001 VL 19 IS 10-12 SI SI BP 1399 EP 1409 PG 11 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 522AH UT WOS:000173873200013 ER PT J AU Glassmeier, KH Motschmann, U Dunlop, M Balogh, A Acuna, MH Carr, C Musmann, G Fornacon, KH Schweda, K Vogt, J Georgescu, E Buchert, S AF Glassmeier, KH Motschmann, U Dunlop, M Balogh, A Acuna, MH Carr, C Musmann, G Fornacon, KH Schweda, K Vogt, J Georgescu, E Buchert, S TI Cluster as a wave telescope - first results from the fluxgate magnetometer SO ANNALES GEOPHYSICAE LA English DT Article DE electromagnetics; wave propagation; magnetospheric physics; MHD waves and instabilities; plasma waves and instabilities ID SPACE PLASMA; COMPONENTS; STATES; FIELD AB The four Cluster spacecraft provide an excellent opportunity to study spatial structures in the magnetosphere and adjacent regions. Propagating waves are amongst the interesting structures and for the first time, Cluster will allow one to measure the wave vector of low-frequency fluctuations in a space plasma. Based on a generalized minimum variance analysis wave vector estimates will be determined in the terrestrial magnetosheath and the near-Earth solar wind. The virtue and weakness of the wave telescope technique used is discussed in detail. C1 Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Meteorol, D-3300 Braunschweig, Germany. Tech Univ Carolo Wilhelmina Braunschweig, Inst Theoret Phys, D-3300 Braunschweig, Germany. Univ London Imperial Coll Sci & Technol, Space & Atmospher Phys Grp, London, England. Goddard Space Flight Ctr, Greenbelt, MD USA. Max Planck Inst Extraterr Phys, Munich, Germany. Swedisch Space Res Inst, Uppsala, Sweden. RP Glassmeier, KH (reprint author), Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Meteorol, D-3300 Braunschweig, Germany. RI dunlop, malcolm/F-1347-2010 NR 27 TC 66 Z9 66 U1 0 U2 2 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS-GERMANY JI Ann. Geophys. PD OCT-DEC PY 2001 VL 19 IS 10-12 SI SI BP 1439 EP 1447 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 522AH UT WOS:000173873200017 ER PT J AU Turner, AD Bock, JJ Beeman, JW Glenn, J Hargrave, PC Hristov, VV Nguyen, HT Rahman, F Sethuraman, S Woodcraft, AL AF Turner, AD Bock, JJ Beeman, JW Glenn, J Hargrave, PC Hristov, VV Nguyen, HT Rahman, F Sethuraman, S Woodcraft, AL TI Silicon nitride micromesh bolometer array for submillimeter astrophysics SO APPLIED OPTICS LA English DT Article ID STRONG ELECTROTHERMAL FEEDBACK; TEMPERATURES; PERFORMANCE; MULTIPLEXER; SENSORS; MK AB We present the design and performance of a feedhorn-coupled bolometer array intended for a sensitive 350-mum photometer camera. Silicon nitride micromesh absorbers minimize the suspended mass and heat capacity of the bolometers. The temperature transducers, neutron-transmutation-doped Ge thermistors, are attached to the absorber with In bump bonds. Vapor-deposited electrical leads address the thermistors and determine the thermal conductance of the bolometers. The bolometer array demonstrates a dark noise-equivalent power of 2.9 x 10(-17) W/root Hz and a mean heat capacity of 1.3 pJ/K at 390 mK. We measure the optical efficiency of the bolometer and feedhorn to be 0.45-0.65 by comparing the response to blackbody calibration sources. The bolometer array demonstrates theoretical noise performance arising from the photon and the phonon and Johnson noise, with photon noise dominant under the design background conditions. We measure the ratio of total noise to photon noise to be 1.21 under an absorbed optical power of 2.4 pW. Excess noise is negligible for audio frequencies as low as 30 mHz. We summarize the trade-offs between bare and feedhorn-coupled detectors and discuss the estimated performance limits of micromesh bolometers. The bolometer array demonstrates the sensitivity required for photon noise-limited performance from a spaceborne, passively cooled telescope. (C) 2001 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Colorado, Boulder, CO 80309 USA. Cardiff Univ, Cardiff CF1 1XL, S Glam, Wales. RP CALTECH, Jet Prop Lab, Mail Stop 59-33, Pasadena, CA 91109 USA. EM a.turner@siwaveinc.com; James.Bock@jpl.nasa.gov; jwbeeman@lbl.gov; jglenn@casa.colorado.edu; P.Hargrave@astro.cf.ac.uk; vvh@astro.caltech.edu; hien@irastro.jpl.nasa.gov; fr@astro.caltech.edu; cheenu@jpl.nasa.gov; A.Woodcraft@astro.cf.ac.uk NR 31 TC 96 Z9 96 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD OCT 1 PY 2001 VL 40 IS 28 BP 4921 EP 4932 DI 10.1364/AO.40.004921 PG 12 WC Optics SC Optics GA 475ND UT WOS:000171169800001 PM 18364768 ER PT J AU Tingay, SJ Preston, RA Jauncey, DL AF Tingay, SJ Preston, RA Jauncey, DL TI The subparsec-scale structure and evolution of Centaurus A. II. Continued very long baseline array monitoring SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 5128, Centaurus A, PKS 1322-427); radio continuum; techniques : interferometric ID RADIO GALAXY; RELATIVISTIC JETS AB We present the results of continued 8.4 GHz Very Long Baseline Array monitoring of the subparsecscale structure and evolution of Centaurus A, following on from the initial results presented in 1998 by Tingay et al. We include, for the first time, multiepoch VLBI images at 22.2 GHz that show that the jet is linear and well collimated on scales as small as 0.02 pc (similar to 1000r(s)). Two components in the subparsec-scale jet continue to evolve slowly with a speed of 0.12c. We confirm that an additional component, close to the core, has no significant motion. Some evidence is seen for rapid variations within individual components, as noted dramatically in 1991-1992 by Tingay et al., albeit at a lower level of activity. Both the stationary behavior of the component close to the core and the internal variability of components in the subparsec-scale jet of Centaurus A may be explained as being due to the existence of shocks created in the wake of major component ejections from the nucleus, as simulated by Agudo et al. (published in 2001). Tentative evidence is found to suggest that two subparsec-scale counterjet components are in motion away from the nucleus. The estimated apparent speeds of the jet and counterjet components are consistent with the previously suggested likely jet viewing angle range, 50 degrees -80 degrees. We also compare our Centaurus A images with high-resolution VLBI images of M87 to show that the region of the Centaurus A jet in which collimation likely first occurs lies a factor of 10 below our current resolution limit. Future space VLBI missions at high frequency will be required to resolve this region. C1 CSIRO, Australia Telescope Natl Facil, Paul Wild Observ, Narrabri, NSW 2390, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CSIRO, Australia Telescope Natl Facil, Epping, NSW 2121, Australia. RP Tingay, SJ (reprint author), CSIRO, Australia Telescope Natl Facil, Paul Wild Observ, Locked Bag 194, Narrabri, NSW 2390, Australia. RI Tingay, Steven/B-5271-2013 NR 18 TC 27 Z9 27 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 2001 VL 122 IS 4 BP 1697 EP 1706 DI 10.1086/323097 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 479TY UT WOS:000171420700004 ER PT J AU Mora, A Merin, B Solano, E Montesinos, B de Winter, D Eiroa, C Ferlet, R Grady, CA Davies, JK Miranda, LF Oudmaijer, RD Palacios, J Quirrenbach, A Harris, AW Rauer, H Cameron, A Deeg, HJ Garzon, F Penny, A Schneider, J Tsapras, Y Wesselius, PR AF Mora, A Merin, B Solano, E Montesinos, B de Winter, D Eiroa, C Ferlet, R Grady, CA Davies, JK Miranda, LF Oudmaijer, RD Palacios, J Quirrenbach, A Harris, AW Rauer, H Cameron, A Deeg, HJ Garzon, F Penny, A Schneider, J Tsapras, Y Wesselius, PR TI EXPORT: Spectral classification and projected rotational velocities of Vega-type and pre-main sequence stars SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : fundamental parameters; stars : pre-main sequence; stars : rotation ID HERBIG AE/BE STARS; T-TAURI STARS; HIGH-RESOLUTION SPECTROSCOPY; BETA-PICTORIS; EFFECTIVE TEMPERATURES; LITHIUM ABUNDANCES; CIRCUMSTELLAR DISK; GIANTS; VARIABILITY; SEARCH AB In this paper we present the first comprehensive results extracted from the spectroscopic campaigns carried out by the EXPORT (EXoPlanetary Observational Research Team) consortium. During 1998-1999, EXPORT carried out an intensive observational effort in the framework of the origin and evolution of protoplanetary systems in order to obtain clues on the evolutionary path from the early stages of the pre-main sequence to stars with planets already formed. The spectral types of 70 stars, and the projected rotational velocities, v sin i, of 45 stars, mainly Vega-type and pre-main sequence, have been determined from intermediate- and high-resolution spectroscopy, respectively. The first part of the work is of fundamental importance in order to accurately place the stars in the HR diagram and determine the evolutionary sequences; the second part provides information on the kinematics and dynamics of the stars and the evolution of their angular momentum. The advantage of using the same observational configuration and methodology for all the stars is the homogeneity of the set of parameters obtained. Results from previous work are revised, leading in some cases to completely new determinations of spectral types and projected rotational velocities; for some stars no previous studies were available. C1 Univ Autonoma Madrid, Fac Ciencias, Dept Fis Teor, E-28049 Madrid, Spain. Lab Astrofis Espacial & Fis Fundamental, Madrid 28080, Spain. CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain. TNO, TPD Space Instrumentat, NL-2600 AD Delft, Netherlands. CNRS, Inst Astrophys Paris, F-75014 Paris, France. NASA, NOAO, STIS, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Joint Astron Ctr, Hilo, HI 96720 USA. Univ Leeds, Dept Phys & Astron, Leeds LS2 9JT, W Yorkshire, England. Univ Calif San Diego, Dept Phys, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. DLR, Dept Planetary Explorat, D-12489 Berlin, Germany. Univ St Andrews, Dept Phys & Astron, St Andrews KY16 9SS, Fife, Scotland. Inst Astrofis Canarias, Tenerife 38200, Spain. Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England. Observ Paris, F-92195 Meudon, France. Univ Groningen, SRON, NL-9700 AV Groningen, Netherlands. RP Mora, A (reprint author), Univ Autonoma Madrid, Fac Ciencias, Dept Fis Teor, Modulo C-XI, E-28049 Madrid, Spain. EM alcione.mora@uam.es RI Solano, Enrique/C-2895-2017; Montesinos, Benjamin/C-3493-2017; OI Montesinos, Benjamin/0000-0002-7982-2095; Cameron, Andrew/0000-0002-8863-7828; Deeg, Hans-Jorg/0000-0003-0047-4241; Merin, Bruno/0000-0002-8555-3012 NR 65 TC 127 Z9 127 U1 1 U2 2 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 2001 VL 378 IS 1 BP 116 EP 131 DI 10.1051/0004-6361:20011098 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480WM UT WOS:000171486600020 ER PT J AU Lopez, B Tuthill, PG Danchi, WC Monnier, JD Niccolini, G AF Lopez, B Tuthill, PG Danchi, WC Monnier, JD Niccolini, G TI The icy side of Frosty Leo SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE radiative transfer; methods : numerical; methods : observational; techniques : interferometric; stars : mass loss; stars : AGB and post-AGB ID BIPOLAR PREPLANETARY NEBULAE; BINARY-SYSTEMS; DUSTY WINDS; IRAS 09371; MASS-LOSS; STARS; HYDRODYNAMICS; MECHANISMS; ENVELOPE AB An imaging study of the bipolar nebula Frosty Leo is presented. In particular, we have studied the effects of spatial distribution of H(2)O ice on the circumstellar environment. Using the Keck telescope with the NIRC infrared camera, we have recovered images at a wavelength of 3.08 mu within the prominent (attenuation of about 5 mag) water-ice absorption band, and in the adjacent quasi-continuum at 1.6 mum, 2.2 mum, and 3.3 mum. While the well-known bipolar structure appears quite symmetrical in all quasi-continuum images, the Northern lobe seems to be almost totally extinguished (by a factor of greater than or similar to 10) compared to the Southern one in images at 3.08 mum. This suggests a much greater concentration of ice between the observer and the Northern lobe. The question of the physical structure of the nebula has been addressed with the use of numerical radiative transfer simulations which have been able to reproduce the general behavior of the images and of earlier spectral data. From this, we deduce and/or confirm several parameters of interest: the typical dust grain size, the dust density distribution in the envelope, and the abundance of water ice. Models were produced with physically symmetrical lobes in which some one-sided extinction was produced by an effect related to the observer's viewing angle. However, in order to reproduce the extreme extinction observed, more complicated scenarios, involving asymmetry with respect to the plane of the disk, were needed. Additional imaging observations were conducted at 2.26 mum (where the system is bright) with the intent to recover high-angular-resolution information. Data sets consisted of one hundred of rapid-exposure data frames from which images were recovered using a shift-and-add algorithm. Although these images did contain structures at the diffraction limit of the telescope ( similar to 50 milliarcsec), no evidence for binarity as reported by Roddier et al. (1995) from adaptive optical studies was found within the dynamical range obtained. C1 Observ Cote Azur, Dept Fresnel, UMR 6528, F-06034 Nice 4, France. Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. RP Lopez, B (reprint author), Observ Cote Azur, Dept Fresnel, UMR 6528, BP 4229, F-06034 Nice 4, France. EM lopez@obs-nice.fr OI Monnier, John D/0000-0002-3380-3307 NR 36 TC 6 Z9 6 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 2001 VL 377 IS 1 BP 90 EP 103 DI 10.1051/0004-6361:20010858 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 474DB UT WOS:000171088200011 ER PT J AU Vrsnak, B Aurass, H Magdalenic, J Gopalswamy, N AF Vrsnak, B Aurass, H Magdalenic, J Gopalswamy, N TI Band-splitting of coronal and interplanetary type II bursts - I. Basic properties SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : radio radiation; MHD; shock waves; Sun : corona; interplanetary medium ID INTER-PLANETARY MEDIUM; MHD SHOCK-WAVES; RADIO-BURSTS; WIND SPACECRAFT; MASS EJECTIONS; SOLAR CORONA; ACCELERATION; EMISSION; RADIATION; MECHANISM AB Patterns analogous to the band-splitting of metric type II bursts are found in a number of type II bursts observed in the dekameter-kilometer wavelength range. A similarity of morphological and frequency-time characteristics of two emission components are indicative of a common source. Relative frequency splits span in the range Deltaf/f = 0.05-0.6. At radial distances between 2 and 4 R(circle dot) only small splits around 0.1 can be found. In the interplanetary space the relative split on average increases with the radial distance, whereas the inferred shock velocity decreases. In three events extrapolations of the split components point to the base and the peak of the jump in the local plasma frequency caused by the associated shock passage at 1 AU. This is suggestive of the plasma radiation from the regions upstream and downstream of the shock. Adopting this interpretation, one finds that the drop of Deltaf/f at 2-4 R(circle dot) is congruent with the Alfven velocity maximum expected there. The split increase and the velocity decrease at larger distances can be explained as a consequence of declining Alfven speed in the interplanetary space. C1 Univ Zagreb, Hvar Observ, HR-10000 Zagreb, Croatia. Astrophys Inst Potsdam, D-14482 Potsdam, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Vrsnak, B (reprint author), Univ Zagreb, Hvar Observ, Kaciceva 26, HR-10000 Zagreb, Croatia. EM bvrsnak@geodet.geof.hr RI Gopalswamy, Nat/D-3659-2012 NR 44 TC 72 Z9 73 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 OCT PY 2001 VL 377 IS 1 BP 321 EP 329 DI 10.1051/0004-6361:20011067 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 474DB UT WOS:000171088200029 ER PT J AU de Martino, D Matt, G Mukai, K Belloni, T Bonnet-Bidaud, JM Chiappetti, L Gansicke, BT Haberl, F Mouchet, M AF de Martino, D Matt, G Mukai, K Belloni, T Bonnet-Bidaud, JM Chiappetti, L Gansicke, BT Haberl, F Mouchet, M TI The X-ray emission of the intermediate polar V 709 Cas SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE accretion; binaries : close; stars, individual : RX J0028+59=V 709 Cas; X-rays : stars ID V709 CASSIOPEIAE; POWER SPECTRA; AM-HERCULIS; POLAR; ACCRETION; SPECTROSCOPY; MISSION; MODELS; BAND AB We present RXTE and BeppoSAX observations of the Intermediate Polar V 709 Cas acquired in 1997 and 1998 respectively. The X-ray emission from 0.1 to 30 keV is dominated by the strong pulsation at the rotational period of the white dwarf (312.8 s) with no sign of orbital or sideband periodicity, thus confirming previous ROSAT results. However, we detect changes in the power spectra between the two epochs. While the second harmonic of the spin period is present during both observations, the first harmonic is absent in 1997. An increase in the amplitude of the spin pulsation is found between 1997 and 1998 together with a decrease in the X-ray flux. The average X-ray spectrum from 0.1 to 100 keV is well described by an isothermal plasma at similar to 27 keV plus complex absorption and an iron K-alpha fluorescent line, due to reflection from the white dwarf surface. The rotational pulsation is compatible with complex absorption dominating the low energy range, while the high energy spin modulation can be attributed to tall shocks above the accreting poles. The RXTE spectrum in 1997 also shows the presence of an absorption edge from ionized iron likely located in the pre{shock accretion flow. The variations along the spin period of the partial covering absorber and of reflection are compatible with the classical accretion curtain scenario. The variations in the spin pulse characteristics and X-ray flux indicate that V709 Cas experiences changes in the mass accretion rate on timescales from months to years. C1 Osserv Astron Capodimonte, I-80131 Naples, Italy. Univ Roma Tre, Dipartimento Fis, Rome, Italy. NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. Osserv Astron Brera, I-23807 Merate, Italy. Serv Astrophys Saclay, Gif Sur Yvette, France. CNR, Ist Fis Cosm, I-20133 Milan, Italy. Univ Sternwarte Gottingen, D-37083 Gottingen, Germany. Max Planck Inst Extraterr Phys, D-37075 Garching, Germany. Observ Paris, Sect Meudon, DAEC, F-92195 Meudon, France. Observ Paris, Meudon Sect, CNRS, UMR 8631, F-92195 Meudon, France. Univ Paris 07, F-75005 Paris, France. RP Osserv Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy. EM demartino@na.astro.it; matt@fis.uniroma3.it; mukai@milkyway.gsfc.nasa.gov; belloni@merate.mi.astro.it; bobi@discovery.saclay.cea.fr; lucio@ifctr.mi.cnr.it; boris@uni-sw.gwdg.de; fwh@xray.mpe.mpg.de; martine.mouchet@obspm.fr RI Gaensicke, Boris/A-9421-2012; OI Gaensicke, Boris/0000-0002-2761-3005; Chiappetti, Lucio/0000-0001-7857-7908; de Martino, Domitilla/0000-0002-5069-4202 NR 36 TC 29 Z9 29 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 OCT PY 2001 VL 377 IS 2 BP 499 EP 511 DI 10.1051/0004-6361:20011059 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 476KP UT WOS:000171226500018 ER PT J AU Bujarrabal, V Castro-Carrizo, A Alcolea, J Contreras, CS AF Bujarrabal, V Castro-Carrizo, A Alcolea, J Contreras, CS TI Mass, linear momentum and kinetic energy of bipolar flows in protoplanetary nebulae SO ASTRONOMY & ASTROPHYSICS LA English DT Review DE stars : AGB and post-AGB; stars : circumstellar matter; radio-lines : stars; planetary nebulae ID PROTO-PLANETARY NEBULAE; POST-AGB STARS; RICH CIRCUMSTELLAR ENVELOPES; ASYMPTOTIC GIANT BRANCH; 21 MU-M; COLD IRAS OBJECTS; EVOLVED STARS; MOLECULAR ENVELOPE; RADIATIVE-TRANSFER; DUST SHELLS AB We have studied the CO emission from protoplanetary nebulae (PPNe). Our sample is composed of 37 objects and includes, we think, all well identified PPNe detected in CO, together with the two yellow hypergiants emitting in CO and one young PN. We present a summary of the existing CO data, including accurate new observations of the (12)CO and (13)CO J = 1-0 and J = 2-1 lines in 16 objects. We identify in the nebulae a slowly expanding shell (represented in the spectra by a central core) and a fast out ow (corresponding to the line wings), that in the well studied PPNe is known to be bipolar. Excluding poor data, we end up with a sample of 32 sources (including the 16 observed by us); fast flows are detected in 28 of these nebulae, being absent in only 4. We present a method to estimate from these data the mass, "scalar" momentum and kinetic energy of the different components of the molecular outflows. We argue that the uncertainties of our method can hardly lead to significant overestimates of these parameters, although underestimates may be present in not well studied objects. The total nebular mass is often as high as similar to 1 M(.), and the mass-loss rate, that (presumably during the last stages of the AGB phase) originated the nebula, had typical values similar to 10(-4) M(.) yr(-1). The momentum corresponding to this mass ejection process in most studied nebulae is accurately coincident with the maximum momentum that radiation pressure, acting through absorption by dust grains, is able to supply (under expected conditions). We estimate that this high-efficiency process lasts about 1000-10 000 yr, after which the star has ejected a good fraction of its mass and the AGB phase ends. On the other hand, the fast molecular outflows, that have probably been accelerated by shock interaction with axial post-AGB jets, carry a significant fraction of the nebular mass, with a very high momentum (in most cases between 10(37) and 10(40) g cm s(-1)) and very high kinetic energy (usually between 10(44) and 10(47) erg). In general, yellow hypergiants and post-AGB objects with low initial mass show nebular masses and momenta that are, respectively, higher and lower than these values. We compare the momenta of the fast outflows with those that can be supplied by radiation pressure, taking into account the expected short acceleration times and some effects that can increase the momentum transfer. We find that in about 80% of PPNe, the fast molecular flows have too high momenta to be powered by radiation pressure. In some cases the momentum of the outflow is similar to 1000 larger than that carried by radiation pressure; such high factors are difficult to explain even under exceptional conditions. Wind interaction is the basic phenomenon in the PN shaping from the former AGB envelopes; we conclude that this interaction systematically takes place along a dominant direction and that this process is not powered by radiation pressure. Due to the lack of theoretical studies, the possible momentum source remains a matter of speculation. C1 Observ Astron Nacl, Alcala De Henares 28800, Spain. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bujarrabal, V (reprint author), Observ Astron Nacl, Apartado 1143, Alcala De Henares 28800, Spain. EM bujarrabal@oan.es; carrizo@oan.es; j.alcolea@oan.es; sanchez@eclipse.jpl.nasa.gov RI Sanchez-Contreras, Carmen/N-3718-2015 OI Sanchez-Contreras, Carmen/0000-0002-6341-592X NR 118 TC 169 Z9 169 U1 0 U2 2 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 2001 VL 377 IS 3 BP 868 EP 897 DI 10.1051/0004-6361:20011090 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480JH UT WOS:000171457900014 ER PT J AU Grun, E Hanner, MS Peschke, SB Muller, T Boehnhardt, H Brooke, TY Campins, H Crovisier, J Delahodde, C Heinrichsen, I Keller, HU Knacke, RF Kruger, H Lamy, P Leinert, C Lemke, D Lisse, CM Muller, M Osip, DJ Solc, M Stickel, M Sykes, M Vanysek, V Zarnecki, J AF Grun, E Hanner, MS Peschke, SB Muller, T Boehnhardt, H Brooke, TY Campins, H Crovisier, J Delahodde, C Heinrichsen, I Keller, HU Knacke, RF Kruger, H Lamy, P Leinert, C Lemke, D Lisse, CM Muller, M Osip, DJ Solc, M Stickel, M Sykes, M Vanysek, V Zarnecki, J TI Broadband infrared photometry of comet Hale-Bopp with ISOPHOT SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE comets : individual : C/1995 O1 (Hale-Bopp); infrared : solar system ID HALLEY MONITORING PROGRAM; INTERACTIVE ANALYSIS PIA; C/1995 O1; WATER ICE; DUST; GRAINS; SUN; PARTICLES; EMISSION; SPECTRUM AB Comet Hale-Bopp was observed five times with ISOPHOT, the photometer on board ESA's Infrared Space Observatory (ISO) between 4.6 and 2.8 AU. Each time, broadband photometry was performed using 4 different detectors, 5 apertures and 10 filters covering the range between 3.6 and 170 mum. Background observations were performed with identical instrument settings at the same positions on the sky several days after the comet observations. The observation strategy and the data reduction steps are described in some detail, including the techniques to correct for variable detector responsivity. The resulting inband power values of the Hale-Bopp observations and their uncertainties are given. The mean uncertainty is 25%. The final fluxes were computed, taking into account the zodiacal background, possible offset of the comet's position from the center of the aperture, the brightness distribution within the coma, and the spectral energy distribution of the comet's emission. Strong thermal emission from a broad size distribution of dust particles was detected in all of the data sets, even at r = 4.6-4.9 AU pre-perihelion and 3.9 AU post-perihelion; the total thermal energy varied as r(-3). The 7.3-12.8 mum color temperature was similar to1.5 times the blackbody temperature, higher than that observed in any other comet. Silicate features at 10 and 25 mum were prominent in all 5 data sets, the largest heliocentric distances that silicate emission has been detected in a comet. The presence of crystalline water ice grains is suggested from the 60 mum excess emission at 4.6-4.9 AU, consistent with the observed Q(OH) if the icy grains were slightly warmer than an equilibrium blackbody. The average albedo of the dust is higher than that of comet P/Halley, but lower than other albedo measurements for Hale-Bopp nearer perihelion. There is no evidence for a component of cold, bright icy grains enhancing the scattered light at 4.6 AU. Simple models for a mixture of silicate and absorbing grains were fit to the ISO spectra and photometry at 2.8 AU. The observed flux at lambda >100 mum requires a size distribution in which most of the mass is concentrated in large particles. Dust production rates of order 1.5 x 10(5) kg s(-1) at 2.8 AU and 3 x 10(4) kg s(-1) at 4.6 AU have been found. They correspond to dust to gas mass ratios of 6 to 10. C1 Max Planck Inst Kernphys, D-69117 Heidelberg, Germany. CALTECH, Jet Prop Lab, Pasadena, CA USA. ESA, ISO Data Ctr, Villafranca, Spain. European So Observ, Santiago 19, Chile. Univ Arizona, Tucson, AZ USA. Observ Paris, Meudon, France. Max Planck Inst Aeron, Katlenburg Duhm, Germany. Penn State Univ, Erie, PA 16563 USA. Lab Astrophys Spatiale, Marseille, France. Max Planck Inst Astron, D-69117 Heidelberg, Germany. Space Telescope Sci Inst, Baltimore, MD 21218 USA. MIT, Cambridge, MA 02139 USA. Charles Univ Prague, Prague, Czech Republic. Univ Kent, Canterbury, Kent, England. RP Grun, E (reprint author), Max Planck Inst Kernphys, D-69117 Heidelberg, Germany. EM eberhard.gruen@mpi-hd.mpg.de RI Lisse, Carey/B-7772-2016 OI Lisse, Carey/0000-0002-9548-1526 NR 69 TC 42 Z9 43 U1 1 U2 2 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 2001 VL 377 IS 3 BP 1098 EP 1118 DI 10.1051/0004-6361:20011139 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480JH UT WOS:000171457900034 ER PT J AU Stecker, FW Glashow, SL AF Stecker, FW Glashow, SL TI New tests of Lorentz invariance following from observations of the highest energy cosmic gamma-rays SO ASTROPARTICLE PHYSICS LA English DT Article DE Lorentz invariance; gamma-rays ID ABSORPTION; SPECTRUM AB We use the recent reanalysis of multi-TeV gamma -ray observations of Mrk 501 to constrain the Lorentz invariance breaking parameter involving the maximum electron velocity. Our limit is two orders of magnitude better than that obtained from the maximum observed cosmic-ray electron energy. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Boston Univ, Boston, MA 02215 USA. RP Stecker, FW (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. RI Stecker, Floyd/D-3169-2012 NR 24 TC 149 Z9 150 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 J9 ASTROPART PHYS JI Astropart Phys. PD OCT PY 2001 VL 16 IS 1 BP 97 EP 99 DI 10.1016/S0927-6505(01)00137-2 PG 3 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 473TE UT WOS:000171063500006 ER PT J AU Hubeny, I Blaes, O Krolik, JH Agol, E AF Hubeny, I Blaes, O Krolik, JH Agol, E TI Non-LTE models and theoretical spectra of accretion disks in active galactic nuclei. IV. Effects of Compton scattering and metal opacities SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies : active; galaxies : nuclei; radiative transfer ID X-RAY-SPECTRA; LINE SEYFERT-1 GALAXIES; VERTICAL STRUCTURE; DIELECTRONIC RECOMBINATION; BLACK-HOLES; ATMOSPHERES; EQUILIBRIUM; IONIZATION; EMISSION; CORONA AB We extend our models of the vertical structure and emergent radiation field of accretion disks around supermassive black holes described in previous papers of this series. Our models now include both a self-consistent treatment of Compton scattering and the effects of continuum opacities of the most important metal species (C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, Ni). With these new effects incorporated, we compute the predicted spectrum from black holes accreting at nearly the Eddington luminosity (L/L-Edd approximate to 0.3) and central masses of 10(6), 10(7), and 10(8) M-circle dot. We also consider two values of the Shakura-Sunyaev alpha parameter, 0.1 and 0.01, but in contrast to our previous papers, we consider a kinematic viscosity that is independent of depth. Although it has little effect when M >10(8) M-circle dot, Comptonization grows in importance as the central mass decreases and the central temperature rises. It generally produces an increase in temperature with height in the uppermost layers of hot atmospheres. Compared to models with coherent electron scattering, Comptonized models have enhanced extreme ultraviolet/soft X-ray emission, but they also have a more sharply declining spectrum at very high frequencies. Comptonization also smears the hydrogen and the He II Lyman edges. The effects of metals on the overall spectral energy distribution are smaller than the effects of Comptonization for these parameters. Compared to pure hydrogen-helium models, models with metal-continuum opacities have reduced flux in the high-frequency tail, except at the highest frequencies, where the flux is very low. Metal photoionization edges are not present in the overall disk-integrated model spectra. The viscosity parameter alpha has a more dramatic effect on the emergent spectrum than do metal-continuum opacities. As alpha increases (and therefore the disk column density decreases), the flux at both the high- and low-frequency extremes of the spectrum increases, while the flux near the peak decreases. Multitemperature blackbodies are a very poor approximation to accretion disk spectra in the soft X-ray region, and such crude modeling may greatly overestimate the accretion luminosity required to explain observed soft X-ray excesses in active galactic nuclei. In addition to our new grid of models, we also present a simple analytic prescription for the vertical temperature structure of the disk in the presence of Comptonization, and show under what conditions a hot outer layer (a corona) is formed. C1 NASA, Goddard Space Flight Ctr, NOAO, AURA, Greenbelt, MD 20771 USA. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RP Hubeny, I (reprint author), NASA, Goddard Space Flight Ctr, NOAO, AURA, Code 681, Greenbelt, MD 20771 USA. RI Agol, Eric/B-8775-2013 OI Agol, Eric/0000-0002-0802-9145 NR 43 TC 107 Z9 108 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2001 VL 559 IS 2 BP 680 EP 702 DI 10.1086/322344 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480BD UT WOS:000171439800014 ER PT J AU Gaensler, BM Slane, PO Gotthelf, EV Vasisht, G AF Gaensler, BM Slane, PO Gotthelf, EV Vasisht, G TI Anomalous X-ray pulsars and soft gamma-ray repeaters in supernova remnants SO ASTROPHYSICAL JOURNAL LA English DT Review DE pulsars : general; radio continuum : ISM; stars : neutron; supernova remnants; X-rays : stars ID LARGE-MAGELLANIC-CLOUD; MAGNETIZED NEUTRON-STARS; GALACTIC-PLANE-SURVEY; VARIABLE SPIN-DOWN; YOUNG PULSARS; CARINA NEBULA; RADIO-SOURCES; SGR 1900+14; EMISSION; COINCIDENT AB Important constraints on the properties of the anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) can be provided by their associations with supernova remnants (SNRs). We have made a radio search for SNRs toward the AXPs RX J170849-400910 and 4U 0142+61. We find that the former lies near a possible new SNR with which it is unlikely to be physically associated, but we see no SNR in the vicinity of the latter. We review all claimed pairings between AXPs and SNRs; the three convincing associations imply that AXPs are young (<10 000 yr) neutron stars with low projected space velocities (<500 km s(-1)). Contrary to previous claims, we find no evidence that the density of the ambient medium around AXPs is higher than that in the vicinity of radio pulsars. Furthermore, the nondetection of radio emission from AXPs does not imply that these sources are radio-silent. We also review claimed associations between SGRs and SNRs. We find none of these associations to be convincing, consistent with a scenario in which SGRs and AXPs are both populations of high-field neutron stars ("magnetars") but the SGRs are an older or longer-lived group of objects than are the AXPs. If the SGR-SNR associations are shown to be valid, then SGRs must be high-velocity objects and most likely represent a different class of source to the AXPs. C1 MIT, Ctr Space Res, Cambridge, MA 02139 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gaensler, BM (reprint author), MIT, Ctr Space Res, 70 Vassar St, Cambridge, MA 02139 USA. RI Gaensler, Bryan/F-8655-2010; OI Gaensler, Bryan/0000-0002-3382-9558 NR 133 TC 142 Z9 144 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2001 VL 559 IS 2 BP 963 EP 972 DI 10.1086/322358 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480BD UT WOS:000171439800034 ER PT J AU Ciardi, DR van Belle, GT Akeson, RL Thompson, RR Lada, EA Howell, SB AF Ciardi, DR van Belle, GT Akeson, RL Thompson, RR Lada, EA Howell, SB TI On the near-infrared size of Vega SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; infrared : stars; stars : fundamental parameters; stars : individual (Vega); techniques : interferometric ID MODEL ATMOSPHERES; ABSOLUTE FLUX; EFFECTIVE TEMPERATURES; STANDARD STARS; DUST; CALIBRATIONS; DIAMETERS; SYSTEMS AB Near-infrared (2.2 mum) long baseline interferometric observations of Vega are presented. The stellar disk of the star has been resolved, and the data have been fitted with a limb-darkened stellar disk of diameter Theta (LD) = 3.28 +/-0.01 mas. The derived effective temperature is T-eff = 9553 +/- 111 K. However, the residuals resulting from the stellar disk model appear to be significant and display organized structure. Instrumental artifacts, stellar surface structure, stellar atmosphere structure, and extended emission/scattering from the debris disk are discussed as possible sources of the residuals. While the current data set cannot uniquely determine the origin of the residuals, the debris disk is found to be the most likely source. A simple debris disk model, with 3%-6% of Vega's flux emanating from the disk at r less than or similar to4 AU, can explain the residuals. C1 Univ Florida, Dept Astron, Gainesville, FL 32611 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Planetary Sci Inst, Astrophys Grp, Tucson, AZ 85705 USA. RP Ciardi, DR (reprint author), Univ Florida, Dept Astron, 211 Space Sci Bldg, Gainesville, FL 32611 USA. OI Akeson, Rachel/0000-0001-9674-1564 NR 34 TC 54 Z9 54 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2001 VL 559 IS 2 BP 1147 EP 1154 DI 10.1086/322345 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480BD UT WOS:000171439800049 ER PT J AU van Belle, GT Ciardi, DR Thompson, RR Akeson, RL Lada, EA AF van Belle, GT Ciardi, DR Thompson, RR Akeson, RL Lada, EA TI Altair's oblateness and rotation velocity from long-baseline interferometry SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : fundamental parameters; stars : individual (Altair); infrared : stars; techniques : interferometric ID PALOMAR TESTBED INTERFEROMETER; ANGULAR SIZE MEASUREMENTS; A-TYPE STARS; EFFECTIVE TEMPERATURES; DIAMETER MEASUREMENTS; CHROMOSPHERIC MODELS; MIRA VARIABLES; CARBON STAR; V-HYDRAE; CATALOG AB We present infrared interferometric angular size measurements for the A7IV-V star Altair that indicate a noncircular projected disk brightness distribution. Given the known rapid rotation of this star, we model the data as arising from an elongated rigid atmosphere. To first order, an ellipse may be fitted to our interferometric diameter measurements, with major and minor axes of 2a=3.461 +/-0.038 mas and 2b=3.037 +/-0.069 mas, respectively, for a difference of 424 +/- 79 mu as between 2a and 2b, and with an axial ratio of a/b=1.140 +/-0.029. Assuming that the apparent oblateness of the photosphere is due to the star's rapid rotation, a more rigorous evaluation of the observation data in the context of a rigidly rotating Roche model shows that an estimate of nu sin i=210 +/- 13 km s(-1) can be derived that is independent of spectroscopic techniques. Also derived are values for the mean effective temperature and the mean linear radius, and an observational constraint upon the relationship between rotation velocity and stellar inclination is established. Altair is the first main-sequence star for which direct observations of an oblate photosphere have been reported and the first star for which nu sin i has been established from observations of the star's photospheric geometry. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. Univ Wyoming, Dept Phys & Astron, Laramie, WY 82071 USA. CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. RP van Belle, GT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. OI Akeson, Rachel/0000-0001-9674-1564 NR 59 TC 102 Z9 102 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2001 VL 559 IS 2 BP 1155 EP 1164 DI 10.1086/322340 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480BD UT WOS:000171439800050 ER PT J AU Manoharan, PK Tokumaru, M Pick, M Subramanian, P Ipavich, FM Schenk, K Kaiser, ML Lepping, RP Vourlidas, A AF Manoharan, PK Tokumaru, M Pick, M Subramanian, P Ipavich, FM Schenk, K Kaiser, ML Lepping, RP Vourlidas, A TI Coronal mass ejection of 2000 July 14 flare event: Imaging from near-Sun to Earth environment SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar-terrestrial relations; Sun : corona; Sun : coronal mass ejections (CMEs); Sun : flares; Sun : magnetic fields; Sun : radio radiation ID SOLAR-WIND SPEED; RADIO; INTERPLANETARY; DENSITY; CYCLE AB We report the results of our investigation of interplanetary effects caused by the large solar flare (X5.7/3B) that occurred on 2000 July 14. In association with this event a bright, fast, halo coronal mass ejection (CME) was observed. The analysis of multiwavelength, high-cadence images obtained from the Radioheliograph shows the on-disk signatures of the initiation of the CME at low-coronal Nancay heights, less than or equal to2 R-circle dot. The formation of the CME inferred from the radio data indicates a nearly developed halo at the low corona. The white-light images and CME follow-up measurements in the interplanetary medium also show, in agreement with the radio data, the propagation of the fully developed halo CME. The inference on the consequences of the CME in the inner heliosphere is from the interplanetary scintillation (IPS) observations obtained with the Ooty Radio Telescope and multiantenna system at the Solar-Terrestrial Environment Laboratory. Scintillation measurements at Ooty on a grid of a large number of radio sources provided an opportunity to image the disturbance associated with the CME at different distances from the Sun before its arrival at the near-Earth space. The scintillation data in particular also played a crucial role in understanding the radial evolution of the speed of the CME in the inner heliosphere. The "speed-distance" plot indicates a two-level deceleration : (1) a low decline in speed at distances within or about 100 solar radii and (2) a rapid decrease at larger distances from the Sun. The linear increase in the size of the CME with radial distance is also briefly discussed. The expansion of the CME, formation of the halo in the low corona, and its speed history in the interplanetary medium suggest a driving energy, which is likely supplied by the twisted magnetic flux rope system associated with the CME. C1 Tata Inst Fundamental Res, Radio Astron Ctr, Udhagamandalam 643001, Ooty, India. Nagoya Univ, Solar Terr Environm Lab, Toyokawa, Japan. Observ Paris, DASOP, F-92195 Meudon, France. Tata Inst Fundamental Res, Natl Ctr Radio Astrophys, Pune, Maharashtra, India. Univ Maryland, Dept Phys & Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, Res Lab, Washington, DC 20375 USA. RP Manoharan, PK (reprint author), Tata Inst Fundamental Res, Radio Astron Ctr, POB 8, Udhagamandalam 643001, Ooty, India. RI Vourlidas, Angelos/C-8231-2009 OI Vourlidas, Angelos/0000-0002-8164-5948 NR 24 TC 70 Z9 73 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2001 VL 559 IS 2 BP 1180 EP 1189 DI 10.1086/322332 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480BD UT WOS:000171439800053 ER PT J AU Ghosh, P White, NE AF Ghosh, P White, NE TI X-ray probes of cosmic star formation history SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; galaxies : evolution; stars : evolution; stars : formation; X-rays : galaxies; X-rays : stars ID HUBBLE DEEP FIELD; HIGH-REDSHIFT; GALAXIES; PULSARS AB We discuss the imprints left by a cosmological evolution of the star formation rate (SFR) on the evolution of X-ray luminosities L-x of normal galaxies, using the scheme earlier proposed by us, wherein the evolution of L-x of a galaxy is driven by the evolution of its X-ray binary population. As indicated in our earlier work, the L-x profile of with redshift can both serve as a diagnostic probe of the SFR profile and constrain evolutionary models for X-ray binaries. We report here the first calculation of the expected evolution of X-ray luminosities of galaxies, updating our work by using a suite of more recently developed SFR profiles that span the currently plausible range. The first Chandra deep imaging results on L-x evolution are beginning to probe the SFR profile of bright spiral galaxies; the early results are consistent with predictions based on current SFR models. Using these new SFR profiles, the resolution of the "birthrate problem" of low-mass X-ray binaries and recycled, millisecond pulsars in terms of an evolving global SFR is more complete. We discuss the possible impact of the variations in the SFR profile of individual galaxies and galaxy types. C1 Tata Inst Fundamental Res, Dept Astron & Astrophys, Bombay 400005, Maharashtra, India. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ghosh, P (reprint author), Tata Inst Fundamental Res, Dept Astron & Astrophys, Homi Bhabha Rd, Bombay 400005, Maharashtra, India. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 20 TC 35 Z9 35 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2001 VL 559 IS 2 BP L97 EP L100 DI 10.1086/323641 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480BG UT WOS:000171440100007 ER PT J AU Ptak, A Griffiths, R White, N Ghosh, P AF Ptak, A Griffiths, R White, N Ghosh, P TI The consequences of the cosmic star formation rate: X-ray number counts SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : evolution; X-rays : galaxies ID GALAXIES; CATALOG AB We discuss the observable consequences for the detection of galaxies in the X-ray bandpass resulting from a peak in the cosmic star formation rate at a redshift greater than 1. Following N. White and P. Ghosh, we assume a large evolution in the X-ray/B luminosity ratio at z similar to 0.5-1.5 resulting from the X-ray binaries that have evolved from stars formed at z > 1-2. Using the Hubble Deep Field-North (HDF-N) redshift survey data and the locally observed X-ray/B luminosity ratio as a guide, we estimate a median X-ray flux (2-10 keV) on the order of 8 x 10(-18) ergs cm(-2) s(-1) for galaxies in the HDF-N, which is consistent with a signal derived from a recent stacking analysis of the HDF-N Chandra data by N. Brandt and coworkers. We also predict the number counts in deep X-ray surveys expected from normal galaxies at high redshift. C1 Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. Tata Inst Fundamental Res, Dept Astron & Astrophys, Bombay 400005, Maharashtra, India. RP Ptak, A (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI White, Nicholas/B-6428-2012; Ptak, Andrew/D-3574-2012 OI White, Nicholas/0000-0003-3853-3462; NR 16 TC 40 Z9 40 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2001 VL 559 IS 2 BP L91 EP L95 DI 10.1086/323893 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480BG UT WOS:000171440100006 ER PT J AU Feibelman, WA Kondo, Y AF Feibelman, WA Kondo, Y TI Planetary nebula He 2-36: Still enigmatic, but getting less SO SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE binaries : close; line : identifications; line : profiles; planetary nebulae : individual (He 2-36, NGC 2346) ID BINARY AB IUE spectra of He 2-36 indicate that the stellar C IV lambda 1549 doublet varies in intensity by a factor of 2.5 during a one-year interval. Detection of [Ne IV] lambda 2424, plus previously known He II and C IV, argue for a hot companion to the cool A2 III nucleus. The C IV emission shows a split profile that strongly resembles the profile (reprocessed in the NEWSIPS format) of the stellar C IV emission of NGC 2346 near phase 0.0 of its well-established 16-day period close binary nucleus. The physical cause for the bifurcation is examined. Numerous other emission lines have been identified in the IUE spectrum of He 2-36. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Feibelman, WA (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 23 TC 3 Z9 3 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD OCT PY 2001 VL 136 IS 2 BP 735 EP 745 DI 10.1086/322533 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 486CA UT WOS:000171799800011 ER PT J AU Kinne, S Pueschel, R AF Kinne, S Pueschel, R TI Aerosol radiative forcing for Asian continental outflow SO ATMOSPHERIC ENVIRONMENT LA English DT Article DE aerosol; radiative forcing; dust; Asia; aircraft samples ID SMALL LATEX SPHERES; PARTICLES AB Asian aerosols in elevated layers over the Pacific Ocean were sampled with NASA wire-impactors and a FSSP optical particle spectrometer-probe aboard the NASA DC-8 aircraft in early March 1994. Strong variations in aerosol properties, primarily aerosol concentration, lead to derived mid-visible extinctions between 0.003 and 0.5/km. FSSP data usually identified two size-modes. The larger 'coarse mode' (radii of 1-3 mum) was assumed to be dust. The composition of the smaller 'accumulation mode' (radii of 0.1-0.3 mum) was based on the analysis of the wire-impactor samples, as significant amounts of soot reduce mid-visible single scattering albedos to the 0.87-0.92 range. Radiative forcing simulations investigated the impact of Asian outflow aerosol on atmospheric radiative fluxes and heating rates. Only events with larger optical depths were important. In those events the solar attenuation of the smaller size mode dominated the net-flux losses at the surface, with values similar those of urban-polluted and/or biomass burning aerosol types (as observed during the TARFOX and INDOEX field experiments). In contrast, changes to net-fluxes at the top of the atmosphere (ToA) for outflow cases are less negative-primarily due to the added greenhouse effect of the dust component. For the climate of the Earth-Atmosphere-System, ToA net-flux losses are considered a cooling, ToA net-flux gains are associated with warming. Weak cooling is determined for the Asian outflow cases under cloud-free conditions. The addition of a reported 50% cloud cover below the aerosol layer causes a switch to slight warming. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 UMBC, JCET, Baltimore, MD 21250 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kinne, S (reprint author), UMBC, JCET, Baltimore, MD 21250 USA. NR 15 TC 28 Z9 34 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1352-2310 J9 ATMOS ENVIRON JI Atmos. Environ. PD OCT PY 2001 VL 35 IS 30 BP 5019 EP 5028 DI 10.1016/S1352-2310(01)00329-6 PG 10 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 485VL UT WOS:000171776400001 ER PT J AU Campbell, MR Dawson, DL Melton, S Hooker, D Cantu, H AF Campbell, MR Dawson, DL Melton, S Hooker, D Cantu, H TI Surgical instrument restraint in weightlessness SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE spaceflight; microgravity; space medicine; trauma; human factors ID TEXAS MEDICINE; FEBRUARY 1998; MICROGRAVITY; SPACE; SURGERY; TRAUMA; CARE AB Background: Performing a surgical procedure during spaceflight will become more likely in the future as the duration of missions becomes longer. Only minimal surgical capability was available on previous missions since the definitive medical care time was short and the likelihood of a surgical event too low to justify carrying surgical hardware onboard. Early demonstrations of surgical procedures in the microgravity environment of parabolic flight indicated the need for careful logistical planning and restraint of surgical hardware. Human ergonomics also has more effect in microgravity than in the conventional 1-G environment. Methods: Three methods of surgical instrument restraint-a Minor Surgical Kit (MSK), a Surgical Restraint Scrub Suit (SRSS), and a Surgical Tray (ST)-were evaluated in parabolic flight surgical procedures. Results. The MSK was easily stored, easily deployed, and demonstrated the best ability to facilitate a surgical procedure in microgravity. Conclusion: Important factors in a surgical restraint system for microgravity include excellent organization of supplies, ability to maintain sterility, accessibility while providing secure restraint, ability to dispose of sharp items and biological trash, and ergonomic efficiency. C1 NASA Med Operat, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Wyle Labs, Houston, TX USA. RP Campbell, MR (reprint author), McCuiston Reg Hosp, 575 DeShong, Paris, TX 75460 USA. NR 12 TC 10 Z9 10 U1 0 U2 1 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD OCT PY 2001 VL 72 IS 10 BP 871 EP 876 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 479PK UT WOS:000171412600001 PM 11601549 ER PT J AU Stowe, RP Mehta, SK Ferrando, AA Feeback, DL Pierson, DL AF Stowe, RP Mehta, SK Ferrando, AA Feeback, DL Pierson, DL TI Immune responses and latent herpesvirus reactivation in spaceflight SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE stress; spaceflight; aging; herpesvirus; microgravity; immunity ID EPSTEIN-BARR-VIRUS; CELL-MEDIATED-IMMUNITY; PROLONGED PHYSICAL STRESS; SHORT-TERM SPACEFLIGHT; PSYCHOLOGICAL STRESS; BOVINE NEUTROPHILS; RISK-FACTORS; CYTOMEGALOVIRUS; ASTRONAUTS; CORTISOL AB Background: Increased frequency and severity of herpesvirus infections are common in individuals with impaired cellular immunity, a phenomenon observed in both the elderly and astronauts alike. This study investigated immune responses and latent herpesvirus reactivation during a 9-d spaceflight. In addition, adrenocortical and immune responses of an elderly astronaut (payload specialist-2, PS2; age 77) who flew on this mission were compared with that of younger crewmembers. Hypothesis: Spaceflight and associated stresses will decrease cellular immunity and reactivate latent herpesviruses. Methods: Blood and urine samples, collected from the seven crewmembers who flew on the Space Shuttle Discovery (STS-95), were analyzed for levels of neuroendocrine hormones, leukocyte and lymphocyte subsets, and evidence of herpesvirus reactivation. Results: Prior to flight, increased antibody titers to latent Epstein-Barr virus were found. During flight, acute changes in dehydroepiandrosterone sulfate (DHEAS) and cortisol resulted in a pronounced decrease in the DHEAS/cortisol ratio by the end of the mission for PS2 and a younger crewmember. Shedding of cytomegalovirus (CMV) in urine and increased CMV antibody titers also occurred inflight. At landing, the percent increases in adrenocorticotropic hormone and cortisol were greatest for PS2 as compared with the other six crewmembers. A significant neutrophilia also was observed in all crewmembers. Notably, PS2 had large increases in monocytes and natural killer cells at landing while other crewmembers showed little change or a decrease. Conclusions: These findings indicate that spaceflight and associated stresses reactivate latent herpesviruses and suggest that acute changes in neuroendocrine hormones mediate these changes in part by downregulating cellular immunity. Moreover, the similarities between aging and spaceflight suggest that the study of the immune system in elderly subjects may be useful as a predictive model for astronauts enduring long-term spaceflights. C1 Univ Texas, Med Branch, Dept Pathol, Galveston, TX 77555 USA. Univ Texas, Med Branch, Dept Surg, Galveston, TX 77555 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. RP Stowe, RP (reprint author), Univ Texas, Med Branch, Dept Pathol, Galveston, TX 77555 USA. NR 50 TC 67 Z9 70 U1 0 U2 6 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD OCT PY 2001 VL 72 IS 10 BP 884 EP 891 PG 8 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 479PK UT WOS:000171412600003 PM 11601551 ER PT J AU Ludwig, DA Vernikos, J Wade, CE Convertino, VA AF Ludwig, DA Vernikos, J Wade, CE Convertino, VA TI Blood pressure changes during orthostatic stress: Evidence of gender differences in neuroeffector distribution SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE gender; blood pressure; vasoconstriction; orthostatic intolerance; stand test ID BODY NEGATIVE-PRESSURE; CARDIOVASCULAR-RESPONSES; SPACEFLIGHT; TOLERANCE; INTOLERANCE; WOMEN; MEN AB Background: Research has demonstrated that exogenous adrenergic agonists produce dose-related vasoconstriction in men but not women. This suggests that the distribution of adrenergic receptor sites differ with gender. Women may have a higher density of receptor sites in the arterioles (fast acting with low gain) while men may have higher density in the larger vessels (slow acting with high gain). Methods. To partially test this hypothesis, the time course in beat-to-beat responses in systolic and diastolic BP, and heart rate was compared between six men and six women during the transition from a supine to an upright posture and during prolonged standing. Results: The transient change in systolic and diastolic BP was very rapid in women, but completed within 15 to 30 s after assuming an upright position. Men increased BP at a much slower rate, but continued to produce higher BPs over the complete testing session (up to 15 min). The rate of change for men (15 mm Hg systolic and 10 mm Hg diastolic) was approximately half that for women (30 mm Hg systolic and 15 mm Hg diastolic) during the first 30 s of upright posture. However, after 60 s of standing, absolute change in systolic BP for the men exceeded that of the women by approximately 5 mm Hg for both systolic and diastolic BP. While men's heart rate remained relatively constant during standing, women compensated for the lower change in BP by a continual increase in heart rate throughout the duration of the test. Although both men and women demonstrated increases in norepinephrine at 5 and 15 min during standing, no difference between genders was observed. Similarly, there were no differences in dominant periodicity of heart rate during standing, although women demonstrated slightly higher beat-to-beat variation (RMS) than men. Conclusion: The results support the hypothesis of distributional differences in neuroeffector responses between men and women and have implications for how men and women respond to orthostatic stress across a variety of environmental conditions. C1 Univ N Carolina, Dept Math Sci, Div Stat, Greensboro, NC 27402 USA. NASA Headquarters, Washington, DC USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. USA, Inst Surg Res, Ft Sam Houston, TX 78234 USA. RP Ludwig, DA (reprint author), Univ N Carolina, Dept Math Sci, Div Stat, 383 Bryan Bldg, Greensboro, NC 27402 USA. NR 28 TC 16 Z9 17 U1 0 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD OCT PY 2001 VL 72 IS 10 BP 892 EP 898 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 479PK UT WOS:000171412600004 PM 11601552 ER PT J AU Diedrichsen, J Hazeltine, E AF Diedrichsen, J Hazeltine, E TI Unifying by binding: Will binding really bind? SO BEHAVIORAL AND BRAIN SCIENCES LA English DT Editorial Material ID RESPONSE-COMPATIBLE STIMULI; BLINDNESS AB The theory of event coding by Hommel et al. proposes that feature binding is a central component of action planning. To evaluate the binding hypothesis, we consider findings from studies of action-perception interference and bimanual movements. We argue that although binding of action features may be a valuable concept, interference from partial feature overlap does not provide a parsimonious account for the observed phenomena. C1 Univ Calif Berkeley, Dept Psychol, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Diedrichsen, J (reprint author), Univ Calif Berkeley, Dept Psychol, Tolman Hall, Berkeley, CA 94720 USA. RI Diedrichsen, Jorn/A-7789-2010 OI Diedrichsen, Jorn/0000-0003-0264-8532 NR 9 TC 0 Z9 0 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH ST, NEW YORK, NY 10011-4221 USA SN 0140-525X J9 BEHAV BRAIN SCI JI Behav. Brain Sci. PD OCT PY 2001 VL 24 IS 5 BP 884 EP + PG 14 WC Psychology, Biological; Behavioral Sciences; Neurosciences SC Psychology; Behavioral Sciences; Neurosciences & Neurology GA 606FD UT WOS:000178722800028 ER PT J AU Garreaud, RD Rutllant, J Quintana, J Carrasco, J Minnis, P AF Garreaud, RD Rutllant, J Quintana, J Carrasco, J Minnis, P TI CIMAR-5: A snapshot of the lower troposphere over the subtropical southeast Pacific SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID TROPICAL PACIFIC; CLOUD; CIRCULATION; VARIABILITY; SATELLITE; CLIMATE AB The extensive and persistent deck of stratocumulus (SCu) off the west coast of subtropical South America plays an important role in the regional and global climate, as well as in coastal weather. As in other subtropical regions, the SCu form at the top of a marine boundary layer (MBL) bounded by a relatively cold ocean and a large-scale subsidence inversion. Nevertheless, details of the structure and variability of the lower troposphere over this region are largely unknown. Ship-based meteorological observations taken along a transect at 27 degreesS from the Chilean coast (71 degreesW)A to Easter Island (110 degreesW) during the second half of October 1999 provide a preliminary description of the low-level circulation, thermodynamic structure, and cloudiness over the subtropical southeast Pacific. Three types of observations were made: (a) 15-min average of air temperature, relative humidity, solar radiation, pressure, and wind by an automatic weather station on the ship deck; (b) 15-min average of vertical reflectivity and cloud base by a laser ceilometer on the ship deck; and (c) twice-daily rawinsondes. Several cloud and radiation properties were derived from GOES-8 imagery and validated against the ship-based observations. A preliminary assessment of the ability of NCEP-NCAR reanalysis and scatterometer winds in representing the atmosphere over a largely in situ data-void area is also presented. Sea surface temperature and near-surface air temperature increase gradually westward, while near-surface relative humidity remains nearly constant at similar to 80%. A significant increase in the free-tropospheric moisture indicates an offshore decrease in the large-scale subsidence. Consistently, the MBL evolves from a shallow, well-mixed MBL topped by compact SCu. near the coast; to a deeper, decoupled MBL with a cumuli rising into a patchy SCu deck near Easter Island, in a similar fashion to the transition from subtropical-stratus regime to trade-cumulus regime described elsewhere. In addition to these "climatological" features, the ship data also reveal the large sensitivity of the MBL-trade inversion structure to synoptic-scale disturbances over the subtropical Pacific. Cloud droplet effective sizes increase from the coast to open ocean. Furthermore, cloud fraction, cloud-top height, liquid water path, and optical depth all peaked during the morning and reached a minimum by midafternoon. C1 Univ Chile, Dept Geophys, Santiago, Chile. Direcc Meteorol Chile, Santiago, Chile. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Garreaud, RD (reprint author), Univ Chile, Dept Geophys, Blanco Encalada 2085, Santiago, Chile. EM rgarreau@dgf.uchile.cl RI Garreaud, Rene/I-6298-2016; Carrasco, Jorge/K-2949-2014; Minnis, Patrick/G-1902-2010; OI Carrasco, Jorge/0000-0003-2154-5483; Minnis, Patrick/0000-0002-4733-6148; Garreaud, Rene/0000-0002-7875-2443 NR 21 TC 50 Z9 52 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD OCT PY 2001 VL 82 IS 10 BP 2193 EP 2207 DI 10.1175/1520-0477(2001)082<2193:CASOTL>2.3.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 478PA UT WOS:000171353500003 ER PT J AU Huang, NE Chern, CC Huang, K Salvino, LW Long, SR Fan, KL AF Huang, NE Chern, CC Huang, K Salvino, LW Long, SR Fan, KL TI A new spectral representation of earthquake data: Hilbert spectral analysis of station TCU129, Chi-Chi, Taiwan, 21 September 1999 SO BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA LA English DT Article AB A new method of spectral analysis, using an approach we call the empirical mode decomposition (EMD) and the Hilbert spectrum analysis (HSA), is presented. The EMD method decomposes any data into a finite number of intrinsic mode function (IMF) components with time-variable amplitudes and frequencies. This decomposition is nearly orthogonal and totally adaptive. With the decomposition, a Hilbert, rather than Fourier, transform is applied to each IMF component, which gives each component instantaneous frequency and energy density. This approach is totally new, and it is different from any of the existing methods: it uses differentiation to define the frequency rather than the traditional convolution computation; thus, it gives the instantaneous frequency and energy density. The greatest advantage of the new approach is that it is the only spectral analysis method applicable to nonstationary and nonlinear data. To illustrate the capability of his new method, we have applied it to the earthquake record from station TCU129, at Chi-Chi, Taiwan, collected during the 21 September 1999 earthquake. The same record is also analyzed with Fourier analysis, wavelet transform, and response spectrum analysis. Comparisons among the different analysis methods indicate that the Hilbert spectral analysis gives the most detailed information in a time-frequency-energy presentation. It also emphasizes the potentially damage-causing low-frequency energy in the earthquake signal missed by all the other methods. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. Natl Taiwan Univ, Dept Civil Engn, Taipei, Taiwan. Infometr Int Inc, Big Sky Engn Consultants, Taipei, Taiwan. USN, Ctr Surface Warfare, Carderock Div, Bethesda, MD 20817 USA. NASA, Wallops Flight Facil, Lab Hydrospher Proc, Wallops Isl, VA 23337 USA. Natl Taiwan Univ, Inst Oceanog, Taipei 10764, Taiwan. RP Huang, NE (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Code 971, Greenbelt, MD 20771 USA. RI Long, Steven/D-7248-2012 NR 19 TC 77 Z9 96 U1 0 U2 9 PU SEISMOLOGICAL SOC AMER PI EL CERRITO PA PLAZA PROFESSIONAL BLDG, SUITE 201, EL CERRITO, CA 94530 USA SN 0037-1106 J9 B SEISMOL SOC AM JI Bull. Seismol. Soc. Amer. PD OCT PY 2001 VL 91 IS 5 BP 1310 EP 1338 PG 29 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 497ME UT WOS:000172458800035 ER PT J AU Loh, CH Wu, TC Huang, NE AF Loh, CH Wu, TC Huang, NE TI Application of the empirical mode decomposition-Hilbert spectrum method to identify near-fault ground-motion characteristics and structural responses SO BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA LA English DT Article AB In this article, the empirical mode decomposition method combined with the Hilbert spectrum method (EMD + HHT) is used to analyze the free-field ground motion and to estimate the global structural property of building and bridge structure through the measurement of seismic response data. The EMD + HHT method provides a powerful tool for signal processing to identify nonlinear and nonstationary data. Based on the decomposed ground-motion signal, the absolute input energy of each decomposed wave was studied (the fling step [pulselike wave] can be separated from the recorded near-fault ground motion). Through application of the EMD + HHT method to building and bridge seismic response data, the time-varying system natural frequency and damping ratio can also be estimated. Damage identification from seismic response data of buildings and bridges, particularly from the Chi-Chi earthquake data, is also described. C1 Natl Taiwan Univ, Dept Civil Engn, Taipei 10764, Taiwan. Natl Ctr Res Earthquake Engn, Taipei, Taiwan. Natl Taiwan Univ, Natl Sci & Technol Program Hazard Mitigat Off, Taipei 10764, Taiwan. NASA, Goddard Space Flight Ctr, Ocean & Ice Branch, Greenbelt, MD 20711 USA. RP Loh, CH (reprint author), Natl Taiwan Univ, Dept Civil Engn, Taipei 10764, Taiwan. NR 10 TC 67 Z9 118 U1 5 U2 27 PU SEISMOLOGICAL SOC AMER PI EL CERRITO PA PLAZA PROFESSIONAL BLDG, SUITE 201, EL CERRITO, CA 94530 USA SN 0037-1106 J9 B SEISMOL SOC AM JI Bull. Seismol. Soc. Amer. PD OCT PY 2001 VL 91 IS 5 BP 1339 EP 1357 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 497ME UT WOS:000172458800036 ER PT J AU Nghiem, SV Bertoia, C AF Nghiem, SV Bertoia, C TI Study of multi-polarization C-band backscatter signatures for Arctic sea ice mapping with future satellite SAR SO CANADIAN JOURNAL OF REMOTE SENSING LA English DT Article ID SYNTHETIC-APERTURE-RADAR; COMPLEX-DIELECTRIC-CONSTANT; POLARIMETRIC SIGNATURES; MICROWAVE-FREQUENCIES; LAYERED MEDIA; MELT PONDS; IMAGERY; MODEL; SCATTERING; SNOW AB The Advanced Synthetic Aperture Radar (ASAR) is scheduled for launch on the ENVISAT satellite in 2001. ASAR will be operated at C band with multiple polarizations and multiple incidence angles. To evaluate the use of future ASAR data for Arctic sea ice mapping, we carry out a study of multiple polarization C-band SAR signatures of various sea ice types. We present polarimetric SAR data acquired over sea ice acquired by the Jet Propulsion Laboratory (JPL) polarimetric AIRSAR system on the NASA DC-8 aircraft over sea ice regions in the Beaufort Sea and the Bering Sea. We use a physical sea ice model to obtain and study polarimetric scattering signatures of sea ice under various conditions. We also compare sea ice signatures with backscatter of ocean surface at different wind speeds using an empirical C-band ocean wind geophysical model function. We present backscatter signatures for ENVISAT ASAR single polarization modes and alternating polarization modes over all swaths. Me find that different polarization combinations in various ENVISAT ASAR image modes at different incidence angle ranges need to be selected to obtain more accurate or more robust results for sea ice mapping. In the wide swath mode, ENVISAT ASAR polarization can be chosen to measure either horizontal or vertical backscatter exclusively. For light wind conditions near a sea ice edge, horizontal backscatter is better to distinguish between first year ice (excluding young ice) and open ocean surface at large incidence angles. For high winds, vertical back-scatter is better in identifying most sea ice types (except multi-year ice at large incidence angles) from open water over a large range of incidence angles. We also investigate diurnal effects to determine the impact on sea ice backscatter acquired at different times of the day. Results show that diurnal effects on first year ice are significant so that SAR data collected over sun-synchronous ascending orbits and descending orbits in daytimes and nighttimes need to be analyzed separately to obtain consistent sea ice mapping results. This study also provides useful information for the application of the future RADARSAT-2 multi polarization SAR to sea ice mapping. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. US Natl Ice Ctr, Washington, DC 20395 USA. RP Nghiem, SV (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-235, Pasadena, CA 91109 USA. NR 59 TC 35 Z9 38 U1 1 U2 10 PU CANADIAN AERONAUTICS SPACE INST PI OTTAWA PA 1685 RUSSELL RD, UNIT 1-R, OTTAWA, ON K1G 0N1, CANADA SN 0703-8992 J9 CAN J REMOTE SENS JI Can. J. Remote Sens. PD OCT PY 2001 VL 27 IS 5 BP 387 EP 402 PG 16 WC Remote Sensing SC Remote Sensing GA 503QP UT WOS:000172811700002 ER PT J AU Dedrick, KR Partington, K Van Woert, M Bertoia, CA Benner, D AF Dedrick, KR Partington, K Van Woert, M Bertoia, CA Benner, D TI US National/Naval Ice Center digital sea ice data and climatology SO CANADIAN JOURNAL OF REMOTE SENSING LA English DT Article AB Weekly sea ice charts produced by the National Ice Center (NIC) from 1972 through 1994 have recently been released to the public in support of environmental research. These charts were originally intended as navigation aids for vessels operating Northern Hemisphere sea ice-infested waters. However, it was recognized early on that these data represent a unique resource for Arctic researchers, adding significantly to sea ice data sets compiled by Walsh (1978) and others. Ice concentration records commonly derived from satellite passive microwave data are similar to the NIC data set in terms of resolution, extent and period of record, but these microwave data may suffer from systematic biases related to the imaging process and algorithms used to infer ice concentration from raw data. Although the NIC digital sea ice data set has its own limitations, its starting point precedes that of the passive microwave record and avoids some of its inherent biases. This paper describes the spatial and thematic characteristics of the NIC historical data set, as well as the digital and analog data and analysis methods used to create the data set. This study, also briefly investigates long-term change in Arctic ice cover. The NIC data set reveals that sea ice concentration patterns in the Atlantic and Pacific sectors of the Arctic vary in response to changes in the North Atlantic Oscillation. This result is consistent with the findings of other researchers, who used other data sets. C1 Natl Naval Ice Ctr, Washington, DC 20395 USA. NASA Headquarters, Polar Res Program, Earth Sci Enterprise, Washington, DC USA. NOAA, NESDIS, Off Res & Applicat, Camp Springs, MD USA. Natl Naval Ice Ctr, Washington, DC USA. RP Dedrick, KR (reprint author), Natl Naval Ice Ctr, FB4,Room 2301,4251 Suitland Rd, Washington, DC 20395 USA. NR 26 TC 26 Z9 27 U1 0 U2 2 PU CANADIAN AERONAUTICS SPACE INST PI OTTAWA PA 1685 RUSSELL RD, UNIT 1-R, OTTAWA, ON K1G 0N1, CANADA SN 0703-8992 J9 CAN J REMOTE SENS JI Can. J. Remote Sens. PD OCT PY 2001 VL 27 IS 5 BP 457 EP 475 PG 19 WC Remote Sensing SC Remote Sensing GA 503QP UT WOS:000172811700007 ER PT J AU Roller, CA Cohen, HS Kimball, KT Bloomberg, JJ AF Roller, CA Cohen, HS Kimball, KT Bloomberg, JJ TI Variable practice with lenses improves visuo-motor plasticity SO COGNITIVE BRAIN RESEARCH LA English DT Article DE visuo-motor plasticity; lens; practice variability; neural plasticity; motor learning ID CONTEXTUAL INTERFERENCE; PRISM ADAPTATION; SKILL ACQUISITION; MEMORY; EXPOSURE; CONSOLIDATION; COORDINATION; DISPLACEMENT; RETENTION; MOVEMENT AB Novel sensorimotor situations present a unique challenge to an individual's adaptive ability. Using the simple and easily measured paradigm of visual-motor rearrangement created by the use of visual displacement lenses, we sought to determine whether an individual's ability to adapt to visuo-motor discordance could be improved through training. Subjects threw small balls at a stationary target during a 3-week practice regimen involving repeated exposure to one set of lenses in block practice X2.0 magnifying lenses), multiple sets of lenses in variable practice (X2.0 magnifying, X0.5 minifying and up-down reversing lenses) or sham lenses. At the end of training, adaptation to a novel visuo-motor situation (20-degree right shift lenses) was tested. We found that (1) training with variable practice can increase adaptability to a novel visuo-motor situation, (2) increased adaptability is retained for at least I month and is transferable to further novel visuo-motor permutations and (3) variable practice improves performance of a simple motor task even in the undisturbed state. These results have implications for the design of clinical rehabilitation programs and countermeasures to enhance astronaut adaptability, facilitating adaptive transitions between gravitational environments. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Baylor Coll Med, Bobby R Alford Dept Otorhinolaryngol & Communicat, Houston, TX 77030 USA. Baylor Coll Med, Dept Med, Design & Anal Unit, Houston, TX 77030 USA. NASA, Lyndon B Johnson Space Ctr, Neurosci Labs, Houston, TX 77058 USA. RP Roller, CA (reprint author), Dept Otolaryngol, NA 102,1 Baylor Plaza, Houston, TX 77030 USA. NR 55 TC 32 Z9 32 U1 4 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0926-6410 J9 COGNITIVE BRAIN RES JI Cognit. Brain Res. PD OCT PY 2001 VL 12 IS 2 BP 341 EP 352 DI 10.1016/S0926-6410(01)00077-5 PG 12 WC Computer Science, Artificial Intelligence; Neurosciences; Neuroimaging SC Computer Science; Neurosciences & Neurology GA 486NG UT WOS:000171823400017 ER PT J AU Harstad, K Bellan, J AF Harstad, K Bellan, J TI Evaluation of commonly used assumptions for isolated and cluster heptane drops in nitrogen at all pressures SO COMBUSTION AND FLAME LA English DT Article ID ROCKET CHAMBER PRESSURES; SUPERCRITICAL CONDITIONS; FLUID HYDROGEN; VAPORIZATION; ENVIRONMENTS; DROPLETS; EQUILIBRIUM; EVAPORATION; COMBUSTION; BEHAVIOR AB A study is performed to assess commonly used assumptions in the modeling of drop behavior in moderate to high temperature surroundings and at all pressures. The model employed for this evaluation has been previously validated for isolated drops by using microgravity data, and is very general: it contains Soret and Dufour effects, does not assume mass transfer quasi-steadiness at the drop boundary, or necessarily the existence of a drop surface (i.e., phase discontinuity). Moreover, the numerical simulations are performed with accurate equations of state and transport properties over a wide range of thermodynamic variables. Consistent with low pressure conditions, the drop boundary is identified a posteriori of the calculations with the location of the largest density change. Simulations are here performed for isolated drops, and for monodisperse as well as binary size drop clusters. The results show that at locations arbitrarily near the boundary, the drop does not reach the mixture critical point within the wide range of conditions investigated (far-field temperatures of 470-1000 K and pressures ranging from 0.1 to 5 MPa). However, the state arbitrarily near the boundary is closer to the critical condition for smaller drops in a cluster than for the larger drops. Evaluations of the effect of the relaxation time at the drop boundary show that quasi-steadiness of the mass transfer prevails for drops of radius as small as 2 x 10(-3) cm. Finally, the diameter squared, exhibits a linear time variation only at atmospheric pressure. At all other pressures investigated (1-5 MPa), the diameter squared displays a negative curvature with time which never becomes linear. In agreement with existing experimental data, the drop lifetime increases monotonically with pressure at low far field temperatures (470 K), but exhibits a maximum as a function of pressure at high temperatures (1000 K). On an appropriate scale, the slope of the diameter squared versus time is shown to be independent of the drop size at all pressures. (C) 2001 by The Combustion Institute. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bellan, J (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NR 36 TC 15 Z9 15 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD OCT PY 2001 VL 127 IS 1-2 BP 1861 EP 1879 DI 10.1016/S0010-2180(01)00292-9 PG 19 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 489ZJ UT WOS:000172022900001 ER PT J AU Elrad, T Filman, RE Bader, A AF Elrad, T Filman, RE Bader, A TI Aspect-oriented programming - Introduction SO COMMUNICATIONS OF THE ACM LA English DT Editorial Material C1 IIT, Dept Comp Sci, Concurrent Programming Res Grp, Chicago, IL 60616 USA. NASA, Ames Res Ctr, Adv Comp Sci Res Inst, Moffett Field, CA 94035 USA. RP Elrad, T (reprint author), IIT, Dept Comp Sci, Concurrent Programming Res Grp, Chicago, IL 60616 USA. NR 3 TC 74 Z9 74 U1 0 U2 4 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 USA SN 0001-0782 J9 COMMUN ACM JI Commun. ACM PD OCT PY 2001 VL 44 IS 10 BP 28 EP 32 PG 5 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA 476ET UT WOS:000171213800011 ER PT J AU Walsh, WA Kleiber, P AF Walsh, WA Kleiber, P TI Generalized additive model and regression tree analyses of blue shark (Prionace glauca) catch rates by the Hawaii-based commercial longline fishery SO FISHERIES RESEARCH LA English DT Article DE blue shark; catch rates; generalized additive model; regression tree AB Generalized additive model (GAM) and regression tree analyses were conducted with blue shark, Prionace glauca, catch rates (catch per set) as reported by National Marine Fisheries Service observers serving aboard Hawaii-based commercial longline vessels from March 1994 through December 1997 (N=2010 longline sets). The objective was to use GAM and regression tree methodology to relate catch rates to a tractable suite of readily measured or computed variables. Because the predictor variables are also either provided in or easily computed from the logbooks that commercial vessels submit upon landing fish for sale, it is likely that a model or models fitted to accurate observer data could then be applied on a fleet-wide basis to serve as a standard of comparison for the logbooks. The GAM included nine spatio-temporal, environmental, and operational variables and explained 72.1% of the deviance of blue shark catch rates. Latitude exerted the strongest effects of any individual variable; longitude was the most influential variable when adjusted for the effects of all other factors. Relatively cold sea surface temperatures were associated with high catch rates. The initial regression tree included 68 terminal nodes and I I predictors. It was refined to a final tree with 42 terminal nodes, which reduced the root mean deviance by 65.3%. The tree was partitioned first on latitude 26.6 degreesN, and then branched out to reach terminal nodes after 2-8 additional partitionings. Sets south of this latitude were characterized by lower catch rates and partitionings on a greater number and variety of predictors. Northerly sets were characterized by higher and more variable blue shark catch rates. Predictions from the two analyses were highly correlated (r=0.903. P much less than0.001). Moreover, use of these methods in combination aided greatly in the interpretation of results. We conclude that GAM and regression tree analyses can be usefully employed in the assessment of blue shark catch rates in this fishery. We suggest that either or both of these models could serve as comparison standards for commercial logbooks. Published by Elsevier Science B.V. C1 Univ Hawaii, Joint Inst Marine & Atmospher Res, Honolulu, HI 96822 USA. RP Walsh, WA (reprint author), Univ Hawaii, Honolulu Lab, Natl Marine Fisheries Serv, 2570 Dole St, Honolulu, HI 96822 USA. NR 12 TC 51 Z9 55 U1 1 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0165-7836 J9 FISH RES JI Fish Res. PD OCT PY 2001 VL 53 IS 2 BP 115 EP 131 DI 10.1016/S0165-7836(00)00306-4 PG 17 WC Fisheries SC Fisheries GA 469GR UT WOS:000170806600002 ER PT J AU Yamaguchi, A Taylor, GJ Keil, K Floss, C Crozaz, G Nyquist, LE Bogard, DD Garrison, DH Reese, YD Wiesmann, H Shih, CY AF Yamaguchi, A Taylor, GJ Keil, K Floss, C Crozaz, G Nyquist, LE Bogard, DD Garrison, DH Reese, YD Wiesmann, H Shih, CY TI Post-crystallization reheating and partial melting of eucrite EET90020 by impact into the hot crust of asteroid 4Vesta similar to 4.50 Ga ago SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID ANGRA-DOS-REIS; PARENT BODY; BHOLGHATI HOWARDITE; MINERAL CHEMISTRY; PLAGIOCLASE FELDSPAR; SHOCK METAMORPHISM; AR-39-AR-40 AGE; IBITIRA EUCRITE; ION MICROPROBE; SOLAR-SYSTEM AB We performed petrologic, radiometric (Ar-Ar, Sm-Nd, and Mn-Cr ages), and ion microprobe studies of the basaltic eucrite, EET90020. This is one of the few rare basaltic eucrites whose Ar-39-(40) Ar age has not been reset during impact bombardment on the HED parent body less than or equal to4 Ga ago and, thus. should provide a unique opportunity to study the nature of the early thermal events on its parent body (presumably asteroid 4Vesta). Hand specimen inspection shows that the rock consists of a fine-grained and a coarse-grained lithology. Microscopy indicates that the fine-grained lithology has a granulitic texture, with a coarser-grained area and a large opaque assemblage embedded in the granulitic matrix. The coarse-grained lithology has an igneous, subophitic texture. The rock has pyroxenes similar to those in type 5 eucrites (type 5 pyroxene) and experienced prolonged thermal metamorphism after rapid crystallization from a near-surface melt. However, minor mineral assemblages are unusual and suggest a complex thermal history. Tridymite occurs as large laths, irregular crystals (< 1.5 mm), and in a large assemblage of tridymite-plagioclase-pyroxene about 4 mm in size. One large opaque assemblage (similar to1.4 mm in size) is a decomposition product of Cr-ulvospinel and consists of zoned Ti-chromite. ilmenite and minor Fe-metal. The opaques are often rimmed by Fe-rich olivine and pigeonite with some chemical variations, indicating disequilibrium with the surrounding type 5 pyroxenes. Ca-phosphate: with low REE abundances, and the LREE signatures observed in plagioclase suggest that melt was present during metamorphism. This indicates that EET90020 was reheated above the subsolidus temperature of eucrites of similar to 1060 degreesC. causing partial melting. Tridymite, Cr-ulvospinel, and some pyroxene and plagioclase crystallized from the melt. The presence of unequilibrated phases related to opaques suggests cooling rates greater than several degreesC/day. The reheating event was too short to destroy the exsolution textures of the type 5 pyroxenes. The temperature of the rock just before the reheating could have been similar to 870 degreesC, based on the two-pyroxene temperature of the type 5 pyroxenes. The absence of shock effects in plagioclases suggests that EET90020 did not experience shock events > 1-5 GPa after the reheating event. EET90020 seems to have experienced the following thermal history; (1) crystallization during rapid cooling near the surface, (2) some brecciation by impact; (3) thermal metamorphism that produced type 5 pyroxene; and (4) short reheating that caused partial melting and rapid cooling. Ar-39-Ar-40 measurements show a relatively flat pattern and an age of 4.49 +/- 0.01 Ga, which is consistent with rapid cooling from high temperature (event 4). Resetting of the Sm-Nd ages at 4.51 +/- 0.04 Ga appears to be closely related to the remelting of Ca-phosphates. Rb-Sr data suggest Rb-loss from tridymite during partial melting. The resetting of the Mn-Cr age may have been related to the formation of Cr-ulvospinels (event 4). We suggest that all these ages were reset by partial melting (event 4). We further suggest that the partial melting event (event 4) that reset the ages similar to4.50 Ga ago was caused by an impact into EET90020 which was part of the hot crust of 4Vesta and resulted in an increase in the temperature from the ambient temperature of similar to 870 degreesC to above the subsolidus temperature of eucrites of similar to 1060 degreesC. Copyright (C) 2001 Elsevier Science Ltd. C1 Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Natl Inst Polar Res, Antartic Meteorite Res Ctr, Tokyo 1738515, Japan. Washington Univ, Space Sci Lab, St Louis, MO 63130 USA. Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Space Mission Syst & Serv Co, Houston, TX 77058 USA. RP Yamaguchi, A (reprint author), Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. EM yamaguch@nipr.ac.jp NR 81 TC 52 Z9 53 U1 1 U2 16 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD OCT PY 2001 VL 65 IS 20 BP 3577 EP 3599 DI 10.1016/S0016-7037(01)00681-0 PG 23 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 491RP UT WOS:000172122900011 ER PT J AU Douglas, S Douglas, DD AF Douglas, S Douglas, DD TI Structural and geomicrobiological characteristics of a microbial community from a cold sulfide spring SO GEOMICROBIOLOGY JOURNAL LA English DT Article DE sulfur spring; microbial community; microscopy; geomicrobiology AB The Ancaster sulfur spring is a cold (9 degreesC) sulfur spring located near Ancaster, Ontario, Canada, which hosts an abundant and diverse microbial mat community. We conducted an extensive microscopical study of the microbial community of this spring using a number of techniques: phase light, confocal scanning laser microscopy, conventional scanning electron microscopy using both chemical/critical point drying and cryofixation preparative techniques, environmental scanning electron microscopy, and transmission electron microscopy. The latter two techniques were coupled with energy dispersive X-ray spectrometry for elemental analysis to complement wet geochemical data collected on bulk spring water and mat pore water. In the anoxic source of the spring, green and purple sulfur bacteria were found together with a sulfide-utilizing type of cyanobacteria that had the unusual characteristic of storing colloidal sulfur intracellularly. Deeper within the source, the mats were dominated by green sulfur bacteria and thick biofilms of cells that precipitated Fe and Zn sulfide minerals on their surfaces. Downstream from the source, thick, filamentous white mats lined the stream channel, formed by a diverse mass of nonphotosynthetic sulfur oxidizers, which were responsible for forming thick masses of spherical colloidal sulfur. These were distinguished by ESEM-EDS from cells by their simple elemental composition (only S was detected). Aqueous geochemistry analysis by ICP-MS showed that some elements (Fe, C, P, Zn, Mg, Ba) were present at higher levels in mat pore water than in bulk spring water. Our approach allowed us to gain an appreciation of the characteristics of this microbial community and allowed us to develop a good understanding of the types of microorganisms present and infer some of the relationships among the members of the community. In addition, we wish to convey the utility of a thorough microscopical approach in geomicrobiological and microbial ecology studies. C1 NASA, Ctr Life Detect, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Guelph, Dept Microbiol, Guelph, ON N1G 2W1, Canada. RP Douglas, S (reprint author), NASA, Ctr Life Detect, Jet Prop Lab, MS183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 19 Z9 19 U1 2 U2 5 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA SN 0149-0451 J9 GEOMICROBIOL J JI Geomicrobiol. J. PD OCT-DEC PY 2001 VL 18 IS 4 BP 401 EP 422 DI 10.1080/014904501753210567 PG 22 WC Environmental Sciences; Geosciences, Multidisciplinary SC Environmental Sciences & Ecology; Geology GA 489AC UT WOS:000171968700003 ER PT J AU Chen, G Davis, D Crawford, J Nowak, JB Eisele, F Mauldin, RL Tanner, D Buhr, M Shetter, R Lefer, B Arimoto, R Hogan, A Blake, D AF Chen, G Davis, D Crawford, J Nowak, JB Eisele, F Mauldin, RL Tanner, D Buhr, M Shetter, R Lefer, B Arimoto, R Hogan, A Blake, D TI An investigation of South Pole HOx chemistry: Comparison of model results with ISCAT observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TROPOSPHERE; SULFUR; SNOW AB Unexpected high levels of OH and NO were recorded at the South Pole (SP) Atmospheric Research Observatory during the 1998-99 ISCAT field study. Model simulations suggest a major photochemical linkage between observed OH and NO, A detailed comparison of the observations with model predictions revealed good agreement for OH at NO levels between 120 and 380 pptv. However, the model tended to overestimate OH for NO levels < 120 pptv, while it underestimated OH at levels > 380 pptv. The reasons for these deviations appear not to involve NO directly but rather HOx radical scavenging for the low NO conditions and additional HOx sources for the high NO conditions. Because of the elevated levels of NO and highly activated HOx photochemistry the SP was found to be a strong net source of surface ozone. It is quite likely that the strong oxidizing environment found at the South Pole extends over the entire polar plateau. C1 Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. New Mexico State Univ, Carlsbad, NM USA. Geochem Sci Div, Hanover, NH USA. Univ Calif Irvine, Irvine, CA USA. Sonoma Technol Inc, Golden, CO USA. RP Chen, G (reprint author), Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. RI Nowak, John/B-1085-2008; Crawford, James/L-6632-2013; Lefer, Barry/B-5417-2012 OI Nowak, John/0000-0002-5697-9807; Crawford, James/0000-0002-6982-0934; Lefer, Barry/0000-0001-9520-5495 NR 18 TC 47 Z9 47 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 1 PY 2001 VL 28 IS 19 BP 3633 EP 3636 DI 10.1029/2001GL013158 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 476GF UT WOS:000171217300003 ER PT J AU Crawford, JH Davis, DD Chen, G Buhr, M Oltmans, S Weller, R Mauldin, L Eisele, F Shetter, R Lefer, B Arimoto, R Hogan, A AF Crawford, JH Davis, DD Chen, G Buhr, M Oltmans, S Weller, R Mauldin, L Eisele, F Shetter, R Lefer, B Arimoto, R Hogan, A TI Evidence for photochemical production of ozone at the South Pole surface SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TROPOSPHERIC OZONE; ANTARCTICA; SNOW AB Observations of OH, NO, and actinic flux at the South Pole surface during December 1998 suggest a surprisingly active photochemical environment which should result in photochemical production of ozone. Long-term South Pole in situ ozone data as well as sonde data also appear to support this conclusion. Other possible factors contributing to ozone variability such as stratospheric influence and the origin of air transported to the South Pole are also explored. Based on box model calculations it is estimated that photochemistry could add 2.2 to 3.6 ppbv/day of ozone to surface air parcels residing on the Antarctic polar plateau. Although the oxidizing potential of the polar plateau appears to be exceptionally high for a remote site, it is unlikely that it has a significant impact on surrounding regions such as the Southern Ocean and the Antarctic free troposphere. These new findings do suggest, however, that the enhanced oxidizing power of the polar plateau may need to be considered in interpreting the chemical history of climate proxy species in ice cores. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Alfred Wegener Inst Polar & Marine Res, D-27570 Bremerhaven, Germany. Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80305 USA. New Mexico State Univ, Carlsbad Environm Monitoring & Res Ctr, Carlsbad, NM 88220 USA. USA, Cold Reg Res & Engn Lab, Hanover, NH 03755 USA. Sonoma Technol Inc, Golden, CO USA. RP Crawford, JH (reprint author), NASA, Langley Res Ctr, 21 Langley Blvd, Hampton, VA 23681 USA. RI Crawford, James/L-6632-2013; Lefer, Barry/B-5417-2012 OI Crawford, James/0000-0002-6982-0934; Lefer, Barry/0000-0001-9520-5495 NR 14 TC 62 Z9 63 U1 0 U2 13 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 OCT 1 PY 2001 VL 28 IS 19 BP 3641 EP 3644 DI 10.1029/2001GL013055 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 476GF UT WOS:000171217300005 ER PT J AU Uritsky, VM Klimas, AJ Vassiliadis, D AF Uritsky, VM Klimas, AJ Vassiliadis, D TI Comparative study of dynamical critical scaling in the auroral electrojet index versus solar wind fluctuations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SELF-ORGANIZED CRITICALITY; AE; MAGNETOSPHERE; AVALANCHE; BEHAVIOR; SYSTEMS; MODEL AB Based on an analysis of auroral electrojet (AE) index data, we demonstrate that the temporal evolution of magnetospheric perturbations exhibits non-trivial power-law relations consistent with the behavior of a general class of statistical physical models in the vicinity of a stationary critical point. We show that the ensemble average dynamics of the activity bursts in the AE index is essentially scale-free and can be characterized in terms of spreading critical exponents eta and delta. The lifetime T and the size S of the bursts show strong algebraic correlation that is approximated by the dependence S similar to T(1+eta+delta). For times shorter than 3.5 hours, we find scaling features in the AE index that are independent of the solar wind input, thus indicating the internal magnetospheric origin of the revealed effects. C1 NASA, Goddard Space Flight Ctr, NRC, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. RP Uritsky, VM (reprint author), NASA, Goddard Space Flight Ctr, NRC, Code 692, Greenbelt, MD 20771 USA. EM vuritsky@pop600.gsfc.nasa.gov NR 16 TC 42 Z9 42 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 OCT 1 PY 2001 VL 28 IS 19 BP 3809 EP 3812 DI 10.1029/2001GL013026 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 476GF UT WOS:000171217300047 ER PT J AU Parry, M Arnell, N McMichael, T Nicholls, R Martens, P Kovats, S Livermore, M Rosenzweig, C Iglesias, A Fischer, G AF Parry, M Arnell, N McMichael, T Nicholls, R Martens, P Kovats, S Livermore, M Rosenzweig, C Iglesias, A Fischer, G TI Millions at risk: defining critical climate change threats and targets SO GLOBAL ENVIRONMENTAL CHANGE-HUMAN AND POLICY DIMENSIONS LA English DT Editorial Material C1 Univ E Anglia, Sch Environm Sci, Jackson Environm Inst, Norwich NR4 7TJ, Norfolk, England. Univ Southampton, Dept Geog, Southampton, Hants, England. London Sch Hyg & Trop Med, London, England. Middlesex Univ, Flood Hazard Res Ctr, Enfield, Middx, England. Univ Maastricht, Maastricht, Netherlands. Goddard Inst Space Studies, New York, NY USA. Univ Politecn Madrid, Madrid, Spain. Int Inst Appl Syst Anal, Laxenburg, Austria. RP Parry, M (reprint author), Univ E Anglia, Sch Environm Sci, Jackson Environm Inst, Norwich NR4 7TJ, Norfolk, England. RI Martens, Pim/A-9297-2011; Nicholls, Robert/G-3898-2010 OI Nicholls, Robert/0000-0002-9715-1109 NR 6 TC 88 Z9 91 U1 0 U2 15 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0959-3780 J9 GLOBAL ENVIRON CHANG JI Glob. Environ. Change-Human Policy Dimens. PD OCT PY 2001 VL 11 IS 3 BP 181 EP 183 DI 10.1016/S0959-3780(01)00011-5 PG 3 WC Environmental Sciences; Environmental Studies; Geography SC Environmental Sciences & Ecology; Geography GA 488HX UT WOS:000171922800001 ER PT J AU Petit, JM Morbidelli, A Chambers, J AF Petit, JM Morbidelli, A Chambers, J TI The primordial excitation and clearing of the asteroid belt SO ICARUS LA English DT Article DE asteroids; origin; Solar System; planetary embryos ID PLANETARY EMBRYOS; SOLAR NEBULA; EVOLUTION AB In this paper, we use N-body integrations to study the effect that planetary embryos spread between similar to0.5 and 4 AU would have on primordial asteroids. The most promising model for the formation of the terrestrial planets assumes the presence of such embryos at the time of formation of Jupiter. At the end of their runaway growth phase, the embryos are on quasi-circular orbits, with masses comparable to that of the Moon or Mars. Due to gravitational interactions among them, and with the growing Jupiter, their orbits begin to cross each other, and they collide, forming bigger bodies. A general outcome of this model is that a few planets form in a stable configuration in the terrestrial planet region, while the asteroid belt is cleared of embryos. Due to combined gravitational perturbations from Jupiter and the embryos, the primordial asteroids are dynamically excited. Most of the asteroids are ejected from the system in a very short time, the dynamical lifetime being on the order of 1 My. A few asteroids (less than 1 %) survive, mostly in the region 2.8-3.3 AU, and their eccentricity and inclination distribution qualitatively resembles the observed one. The surviving asteroids have undergone changes in semimajor axis of several tenths of an AU, which could explain the observed radial mixing of asteroid taxonomic types. When the distribution of massive embryos is truncated at 3 AU, we obtain too many asteroids in the outer part of the belt, especially too many Hildas. This suggests that the formation of Jupiter did not prohibit the formation of large embryos in the outer belt and Jupiter did not accrete them while it was still growing. (C) 2001 Academic Press. C1 Observ Nice, CNRS, F-06304 Nice 4, France. Armagh Observ, Armagh BT61 9DG, North Ireland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Petit, JM (reprint author), Observ Nice, CNRS, BP 4229, F-06304 Nice 4, France. NR 21 TC 105 Z9 107 U1 0 U2 5 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 OCT PY 2001 VL 153 IS 2 BP 338 EP 347 DI 10.1006/icar.2001.6702 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 494BH UT WOS:000172258100010 ER PT J AU Cruikshank, DP Ore, CMD Roush, TL Geballe, TR Owen, TC de Bergh, C Cash, MD Hartmann, WK AF Cruikshank, DP Ore, CMD Roush, TL Geballe, TR Owen, TC de Bergh, C Cash, MD Hartmann, WK TI Constraints on the composition of Trojan asteroid 624 Hektor SO ICARUS LA English DT Article DE asteroids, composition; surfaces, asteroids; spectroscopy; ices; mineralogy ID NEAR-INFRARED SPECTROSCOPY; CHARGED-PARTICLE IRRADIATION; LOW-ALBEDO ASTEROIDS; REFLECTANCE SPECTRA; SOLAR-SYSTEM; OPTICAL-CONSTANTS; OUTER-BELT; WATER ICE; MU-M; CARBONACEOUS CHONDRITES AB We present a composite spectrum of Trojan asteroid 624 Hektor, 0.3-3.6 mum, and models computed for the full wavelength range with the Hapke scattering theory. The data show that there is no discernible 3-mum absorption band. Such a band would indicate the presence of OH(-) or H(2)O-bearing silicate minerals, or macromolecular carbon-rich organic material of the kind seen on the low-albedo hemisphere of Saturn's satellite Iapetus. The absence of spectral structure is itself indicative of the absence of the nitrogen-rich tholins (which show a distinctive absorption band attributed to N-H). The successful models in this study all incorporate magnesium-rich pyroxene (Mg, Fe SiO(3)), which satisfactorily matches the red color of Hektor. Pyroxene is a mafic mineral common in terrestrial and lunar lavas, and is also identified in Main Belt asteroid spectra. An upper limit to the amount of crystalline H(2)O ice (30-mum grains) in the surface layer of Hektor accessible to near-infrared remote sensing observations is 3 wt%. The upper limit for serpentine, as a representative of hydrous silicates, is much less stringent, at 40%, based on the shape of the spectral region around 3 mum. Thus, the spectrum at 3 mum does not preclude the presence of a few weight percent of volatile material in the uppermost surface layer of Hektor. Below this "optical" surface that our observations probe, any amount of H(2)O ice and other volatile-rich materials might exist. All of the models we calculated require a very low-albedo, neutral color material to achieve the low geometric albedo that matches Hektor; we use elemental carbon. If elemental carbon is present on Hektor, it could be of organic or inorganic origin. By analogy, other D-type asteroids could achieve their red color, low albedo, and apparent absence of phyllosilicates from compositions similar to the models presented here. Our models appear to demonstrate that organic solids are not required to match the red color and low albedos of D-type asteroids. (C) 2001 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Moffett Field, CA 94035 USA. Gemini OBserv, Hilo, HI 96720 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Observ Paris, F-92195 Meudon, France. Stanford Univ, Stanford, CA 94309 USA. Planetary Sci Inst, Tucson, AZ 85715 USA. RP Cruikshank, DP (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. EM dcruikshank@mail.arc.nasa.gov NR 83 TC 56 Z9 57 U1 0 U2 1 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 2001 VL 153 IS 2 BP 348 EP 360 DI 10.1006/icar.2001.6703 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 494BH UT WOS:000172258100011 ER PT J AU DiSanti, MA Mumma, MJ Dello Russo, N Magee-Sauer, K AF DiSanti, MA Mumma, MJ Dello Russo, N Magee-Sauer, K TI Carbon monoxide production and excitation in Comet C/1995 O1 (Hale-Bopp): Isolation of native and distributed CO sources SO ICARUS LA English DT Article DE comets; ices; infrared spectroscopy; carbon monoxide; extended emission ID GIOTTO SPACECRAFT ENCOUNTER; MONTE-CARLO-SIMULATION; KECK-II-TELESCOPE; B2 HYAKUTAKE; ATMOSPHERES APPLICATION; PLANETARY-ATMOSPHERES; INTERSTELLAR ICES; EXTENDED SOURCE; P-HALLEY; SOLID CO AB The release of carbon monoxide from Comet C/1995 O1 Hale-Bopp was studied between June 1996 and September 1997 using high resolution infrared spectroscopy near 4.7 mum. The excitation of CO molecules in the coma was assessed through measurement of the rotational temperature on several dates at an angular resolution of similar to 1 arcsecond. An increase in Trot with distance from the nucleus was revealed, most likely because of photolytic heating by fast H-atoms. Observed temperature profiles varied from date to date, but overall the degree of heating was most pronounced near perihelion. The similar rotational temperatures observed for CO and HCN may indicate control of rotational populations by collisions with electrons. The spatial distribution of CO molecules in the coma revealed two distinct sources for CO, one being CO ice native to the nucleus, and another being CO released from a progenitor distributed in the coma. Only the native source was seen when the comet was beyond 2 AU from the Sun. Based on pre- and post-perihelion observations on five dates with heliocentric distance Rh between 4.10 and 2.02 AU, a heliocentric dependence Q(CO.native) = (1.06 +/- 0.44) x 10(30) R(h) (-1.76 +/-0.26) molecules s(-1) was obtained. Within R(h) similar to 1.5 AU, however, both native and distributed sources were consistently present on all dates of observation. The total CO produced was the sum of the two sources and, based on seven dates, obeyed Q(CO.total) = (2.07 +/- 0.20) x 10(30) R(h) (-1.66 +/-0.22) molecules s(-1). This he. liocentric dependence was consistent with that found for water (QH(2)O alpha R(h) (-1.88 +/-0.18) between 0.93 and 1.49 AU) and for mm-sized dust (R(h)(-1.7 +/-0.2) between 0.9 and 2.5 AU). Our derived total mixing ratio for CO was Q(CO,total)/QH(2)O = 0.241 +/- 0.009, with native and distributed sources each contributing an abundance of approximately 12 percent that of water. This was the case even after correcting measured CO and H(2)O column densities, and hence production rates, for opacity in the solar pump. The distributed source exhibited behavior consistent with thermal destruction of a precursor material. The observed variations in its production rate and spatial distribution along the slit suggested contributions from both a diffuse source in the coma and possibly from one or more jets enriched in CO or CO-containing material, such as CHON grains. (C) 2001 Academic Press. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Rowan Univ, Dept Chem & Phys, Glassboro, NJ 08028 USA. RP DiSanti, MA (reprint author), Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. EM disanti@kuiper.gsfc.nasa.gov RI mumma, michael/I-2764-2013; Magee-Sauer, Karen/K-6061-2015; Dello Russo, Neil/G-2727-2015 OI Magee-Sauer, Karen/0000-0002-4979-9875; Dello Russo, Neil/0000-0002-8379-7304 NR 99 TC 106 Z9 106 U1 0 U2 2 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 2001 VL 153 IS 2 BP 361 EP 390 DI 10.1006/icar.2001.6695 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 494BH UT WOS:000172258100012 ER PT J AU Ma, ZQ Bhattacharya, P Rieh, JS Ponchak, GE Alterovitz, SA Croke, ET AF Ma, ZQ Bhattacharya, P Rieh, JS Ponchak, GE Alterovitz, SA Croke, ET TI Reliability of microwave SiGe/Si heterojunction bipolar transistors SO IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS LA English DT Article DE accelerated lifetime testing; HBT reliability; REID; SiGeHBT ID MOLECULAR-BEAM EPITAXY; HBTS AB The degradation behavior of NPN Si/SiGe/Si heterojunction bipolar transistors, grown by solid-source molecular beam epitaxy (MBE), has been studied by accelerated lifetime testing at different ambient temperatures. The degradations of the de current gain and the microwave performance of the devices are explained in terms of recombination enhanced impurity diffusion (REED) of boron atoms from the base region and the subsequent formation of parasitic energy barriers at the base-emitter and base-collector junctions. C1 Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. HRL Labs, LLC, Malibu, CA 90265 USA. RP Ma, ZQ (reprint author), Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. NR 14 TC 2 Z9 4 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1531-1309 J9 IEEE MICROW WIREL CO JI IEEE Microw. Wirel. Compon. Lett. PD OCT PY 2001 VL 11 IS 10 BP 401 EP 403 DI 10.1109/7260.959308 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA 483XW UT WOS:000171662000001 ER PT J AU Bacon, BJ Ostroff, AJ Joshi, SM AF Bacon, BJ Ostroff, AJ Joshi, SM TI Reconfigurable NDI controller using inertial sensor failure detection & isolation SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article AB A modified derivation of nonlinear dynamic inversion provides the theoretical underpinnings for a reconfigurable control law for aircraft that have suffered combinations of actuator failures, missing effector surfaces, and aerodynamic changes. The approach makes use of acceleration feedback to extract information pertaining to any aerodynamic change and thus does not require a complete aerodynamic model of the aircraft. The control law does require feedback of effector positions to accommodate actuator dynamics. Both accelerometer and rate gyro failure detection and isolation (FDI) systems are implemented, allowing up to three independent failures for each FDI system as long as they are in different axes. Nonlinear simulation results show that the FDI systems improve the robustness to accelerometer/rate gyro uncertainties. An advanced tailless aircraft model is used to demonstrate the concepts. The simulation includes accelerometer and rate gyro noise and bias, failures due to accelerometers, rate gyros, and actuators, and modeled missing surfaces that cause airplane aerodynamic changes. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Bacon, BJ (reprint author), NASA, Langley Res Ctr, MS 132, Hampton, VA 23681 USA. NR 19 TC 18 Z9 19 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 OCT PY 2001 VL 37 IS 4 BP 1373 EP 1383 DI 10.1109/7.976972 PG 11 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 509MA UT WOS:000173150500019 ER PT J AU Vandooren, A Cristoloveanu, S Mojarradi, M Kolawa, E AF Vandooren, A Cristoloveanu, S Mojarradi, M Kolawa, E TI Back-gate and series resistance effects in LDMOSFETs on SOI SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article DE device physics; high-voltage devices; LDMOSFET; power devices; series resistance; SOI ID FILM AB Detailed experimental results are used to develop a new model for the linear region of operation of lateral DMOSFETs (LDMOSFETs) on silicon-on-insulator (SOI) that includes the influence of the buried oxide and back-gate. Back-gate biasing results in double-channel conduction and bias-dependent series resistance. Pertinent techniques for parameter extraction are presented and contrasted to those currently used in low-voltage SOI MOSFETs. The typical feature of LDMOSFETs is the significant change in series resistance as the back-gate is driven from accumulation to inversion. The model allows a clear identification of the architectural and technological parameters of the device. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA. ENSERG, UMR CNRS, Lab Phys Composants Semicond, F-38016 Grenoble, France. ENSERG, INPG, F-38016 Grenoble 1, France. RP Vandooren, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 8 Z9 8 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 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD OCT PY 2001 VL 48 IS 10 BP 2410 EP 2416 DI 10.1109/16.954485 PG 7 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 478MH UT WOS:000171349600034 ER PT J AU Legarsky, JL Gogineni, SP Akins, TL AF Legarsky, JL Gogineni, SP Akins, TL TI Focused synthetic aperture radar processing of ice-sounder data collected over the Greenland ice sheet SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE airborne radar; Greenland; ice; ice thickness; remote sensing; sounding; synthetic aperture radar (SAR) ID GROUND-PENETRATING RADAR; WEST ANTARCTICA; MIGRATION; NORTH AB We developed a synthetic aperture radar (SAR) processing algorithm for airborne/spaceborne ice-sounding radar systems and applied it to data collected in Greenland. By using focused SAR (phase-corrected coherent averaging), we improved along-track resolution by a factor of four and provided a 6-dB processing gain over unfocused SAR (coherent averaging without phase correction) based on a point-target analysis for a Greenland ice-sounding data set. Also, we demonstrated that the focused-SAR processing reduced clutter and enabled us to identify bedrock-interface returns buried in clutter. Using focused-SAR technique, we processed data collected over a key 360-km-long portion of the 2000-m contour line of southwest Greenland. To the best of our knowledge, these are the first high-quality radar ice thickness measurements over this key location. Moreover, these ice-thickness measurements have been used for improving mass-balance estimates of the Greenland ice sheet. C1 Univ Missouri, Dept Elect Engn, Columbia, MO 65211 USA. Univ Kansas, Dept Elect Engn & Comp Sci, Lawrence, KS 66044 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Legarsky, JL (reprint author), Univ Missouri, Dept Elect Engn, Columbia, MO 65211 USA. NR 25 TC 27 Z9 28 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 OCT PY 2001 VL 39 IS 10 BP 2109 EP 2117 DI 10.1109/36.957274 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 484FW UT WOS:000171680400003 ER PT J AU Ngheim, SV Tsai, WY AF Ngheim, SV Tsai, WY TI Global snow cover monitoring with spaceborne K-U-band scatterometer SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE flood; Ku-band scatterometer; NSCAT; snow; snowmelt ID PASSIVE MICROWAVE RESPONSE; NORTHERN-HEMISPHERE; NASA SCATTEROMETER; XYLEM EMBOLISM; LAYERED MEDIA; SCATTERERS; MODEL; CLASSIFICATION; CALIBRATION; PARAMETERS AB This paper presents a study to demonstrate the potential of a spaceborne K-u-band scatterometer to monitor global snow cover. Global K-u-band data were acquired by the National Aeronautics and Space Administration (NASA) Scatterometer (NSCAT) operated on the Advanced Earth Observing Satellite (ADEOS) from September 1996 to June 1997. NSCAT backscatter patterns over the northern hemisphere reveals boundaries between different snow classes, defined by the Cold Regions Research and Engineering Laboratory (CRREL), Hanover, NH, snow classification system at different times of the snow season. We show the evolution of the backscatter signature throughout the entire seasonal snow cycle. Within the snow extent determined by the National Oceanic and Atmospheric Administration (NOAA), Washington, DC, and Climate Prediction Center (CPC), operational snow product, K-u-band backscatter data expose detailed features and rapid changes as observed in in-situ snow depth data from surface weather stations in U.S., Canada, and Russia. Sensitivity of K-u-band backscatter to snow conditions is illustrated with the dramatic change over the U.S. northern plains and the Canadian prairie region corresponding to the snow event leading to the 1997 Flood of the Century. We discuss snow field experiments and data analysis plan to understand snow scattering mechanisms, to interpret snow backscatter, and to derive its relationship with snow physical parameters. In view of current and future satellite K-u-band scatterometers, the development of algorithms for quantitative snow cover monitoring is pertinent. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ngheim, SV (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 52 TC 48 Z9 49 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 OCT PY 2001 VL 39 IS 10 BP 2118 EP 2134 DI 10.1109/36.957275 PG 17 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 484FW UT WOS:000171680400004 ER PT J AU Meneghini, R Liao, L Bidwell, SW Heymsfield, GM AF Meneghini, R Liao, L Bidwell, SW Heymsfield, GM TI On the feasibility of a Doppler weather radar for estimates of drop size distribution using two closely spaced frequencies SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE airborne radar; Doppler; drop-size distribution; dual wavelength; spaceborne radar ID VERTICAL AIR MOTION; EDOP RADAR; 94 GHZ; RAIN; REFLECTIVITY AB Dual-frequency weather radar data can be gathered using a single broadband power amplifier and antenna for the purpose of estimating parameters of the hydrometeor size distribution. This is an attractive feature for observation platforms that are limited with respect to mass or available power. Whether useful properties of the scattering medium can be obtained from data of this type is the focus of the paper. Generally, as the center frequency or the bandwidth is decreased, the reflectivity factor difference falls below the level of the inherent signal fluctuations. Even if large numbers of independent samples can be gathered to permit estimates of the differential signals, the question remains as to whether the signal can be related unambiguously to properties of the rain or snow. Center frequencies at or near 35 GHz with bandwidths in excess of 5% give relatively strong differential signals. The signal, moreover, is directly related to the median mass diameter of the size distribution. The differential mean Doppler at frequencies where non-Rayleigh scattering effects are significant is also of use because the quantity depends only on the terminal velocity of the drops and is insensitive to the mean air and platform motion. In principle, the mean and differential mean Doppler velocities from a nadir-viewing radar can be used to estimate the mean vertical air motion and the median drop diameter of the size distribution. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Caelum Res Corp, Rockville, MD 20847 USA. RP NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM bob@priam.gsfc.nasa.gov NR 26 TC 7 Z9 8 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 EI 1558-0644 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD OCT PY 2001 VL 39 IS 10 BP 2203 EP 2216 DI 10.1109/36.957283 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 484FW UT WOS:000171680400012 ER PT J AU Edmonds, LD AF Edmonds, LD TI A time-dependent charge-collection efficiency for diffusion SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article DE charge collection; charge-collection efficiency; diffusion ID SILICON DEVICES; ION TRACKS AB The diffusion equation has some applications relevant to charge collection from ion tracks in silicon devices. Textbook solutions for the diffusion equation are available only for a few simple boundary geometries and special types of boundary conditions. A broader class of geometries was previously treated via a charge-collection efficiency function, but this applies only to total (integrated in time from zero to infinity) collected charge. The earlier work took advantage of the fact that Laplace's equation can be solved for a broad class of geometries. This paper extends the earlier work so that it applies to charge collected up to an arbitrary time. A time-dependent charge-collection efficiency function can be estimated for any geometry such that Laplace's equation has been solved. In particular, the analysis permits a comparison between diffusion calculations and a computer simulation of charge collection from an ion track. This comparison supports an earlier model in which charge collection, including a so-called "prompt" component, is driven by diffusion. The analysis applies to arbitrary track locations and directions. It also provides the option of treating a device geometry as two-dimensional in rectangular coordinates (if desired) while simultaneously treating the track as a line instead of a plane. Simulation codes having such flexibility regarding geometry are difficult to use, so the analysis makes the study of geometry effects accessible to a larger number of investigators. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Edmonds, LD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 17 Z9 18 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 OCT PY 2001 VL 48 IS 5 BP 1609 EP 1622 DI 10.1109/23.960349 PG 14 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 486QJ UT WOS:000171828200001 ER PT J AU Vandooren, A Yuan, J Flandre, D Colinge, JP AF Vandooren, A Yuan, J Flandre, D Colinge, JP TI Total-dose effects in double-gate-controlled NPN bipolar transistors SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT European Conference on Radiation and its Effects on Components and Systems (RADECS) CY SEP 11-13, 2000 CL LOUVAIN LA NEUVE, BELGIUM DE bipolar transistor; double-gate MOSFETs; radiation effects; silicon-on-insulator AB The sensitivity to radiation-induced degradation of new double-gate-controlled lateral NPN bipolar transistors has been investigated. The radiation hardness is improved when the device is working in the accumulation mode. The effect of positive charge and increased surface recombination velocity is analyzed by means of device simulations and experimental results. C1 Motorola Inc, Digital DNA Labs, Austin, TX 78721 USA. Univ Calif Davis, Dept Elect Engn, Davis, CA 95616 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Catholic Univ Louvain, Microelect Lab, B-1348 Louvain, Belgium. RP Motorola Inc, Digital DNA Labs, Austin, TX 78721 USA. EM jing.yuan@idt.com; flandre@dice.ucl.ac.be; colinge@ece.ucdavis.edu NR 11 TC 0 Z9 0 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 EI 1558-1578 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD OCT PY 2001 VL 48 IS 5 BP 1694 EP 1699 DI 10.1109/23.960359 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 486QJ UT WOS:000171828200011 ER PT J AU Johnston, AH AF Johnston, AH TI Proton displacement damage in light-emitting and laser diodes SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT European Conference on Radiation and its Effects on Components and Systems (RADECS) CY SEP 11-13, 2000 CL LOUVAIN LA NEUVE, BELGIUM DE laser diodes; light-emitting diodes (LEDs); optoelectronic devices; radiation effects ID QUANTUM-WELL LASERS; LIFETIME AB The effects of proton displacement damage on light-emitting diodes (LEDs) and laser diodes are discussed, comparing the radiation sensitivity of current technology devices with older devices for which data exist in the literature. Injection-enhanced annealing is discussed, along with the issue of energy dependence of proton displacement damage. New characterization methods are proposed for light-emitting diodes that complement measurement of light output and provide a better indication of nonradiative recombination centers. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnston, AH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 25 TC 17 Z9 24 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD OCT PY 2001 VL 48 IS 5 BP 1713 EP 1720 DI 10.1109/23.960362 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 486QJ UT WOS:000171828200014 ER PT J AU Misra, A Gibala, R Noebe, RD AF Misra, A Gibala, R Noebe, RD TI Optimization of toughness and strength in multiphase intermetallics SO INTERMETALLICS LA English DT Article; Proceedings Paper CT Symposium on Deformation and Microstruture in Intermatallics CY FEB 12-15, 2001 CL NEW ORLEANS, LOUISIANA DE NiAl; directionally solidified eutectics; ductile-phase toughening; slip transfers; precipitate strengthening ID FE-AL ALLOYS; CLEAVAGE FRACTURE; MECHANICAL-PROPERTIES; NIAL-CR; DEFORMATION; BEHAVIOR; MICROSTRUCTURES; ALUMINIDES; TRANSITION; TENSILE AB We have examined the effects of a fine dispersion of precipitates in the matrix phase of two multiphase NiAl-based alloys on strength and toughness. The first system is a directionally solidified Ni-30Fe-23Al alloy composed of a B2 matrix reinforced with a ductile fcc-based second phase. Spinodal decomposition leads to fine-scale bcc precipitates within the B2 phase, resulting in a 50% increase in room-temperature strength, but with reduced ductility and toughness compared to similar alloys without the strengthening precipitates. The increase in strength limits matrix plasticity prior to cleavage crack initiation, but some slip transfer still occurs from the fcc-based phase to the (B2 + bcc) matrix. A mixed dendritic and lamellar microstructure also contributes to lower toughness. The second system is a directionally solidified NiAl-31Cr-3Mo eutectic composed of a B2-NiAl matrix reinforced with a Cr(Mo) phase. Small additions of Hf and Si to this material result in the precipitation of a fine cuboidal G-phase in the NiAl matrix. Reduced toughness in this modified alloy relative to unalloyed NiAl-Cr(Mo) is attributed to the lack of plasticity in the precipitate-strengthened matrix and partial loss of the aligned lamellar microstructure by Hf and Si alloying. Observations of the deformation and fracture mechanisms in these alloys are used as a basis to discuss microstructural design of multiphase intermetallics with optimized strength and toughness. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Michigan, Dept Mat Sci & Engn, Ann Arbor, MI 48109 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Misra, A (reprint author), Los Alamos Natl Lab, POB 1663, Los Alamos, NM 87545 USA. RI Misra, Amit/H-1087-2012 NR 21 TC 36 Z9 39 U1 0 U2 13 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0966-9795 J9 INTERMETALLICS JI Intermetallics PD OCT-NOV PY 2001 VL 9 IS 10-11 BP 971 EP 978 DI 10.1016/S0966-9795(01)00098-X PG 8 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA 499QZ UT WOS:000172583000019 ER PT J AU Allen, JS Hallinan, KP AF Allen, JS Hallinan, KP TI Liquid blockage of vapor transport lines in low Bond number systems due to capillary-driven flows in condensed annular films SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article ID INSTABILITY; MECHANISMS; FLUID; DISPLACEMENT; STABILITY; BREAKUP; PIPE AB An experimental capillary-pumped loop (CPL) was designed to investigate the behavior of phase-change heat transfer devices and ascertain the mechanisms which have caused anomalous behavior of previous CPL demonstrations in low gravity. Low-gravity experiments were conducted during the Microgravity Science Laboratory (MSL-1) mission on-board the Space Shuttle Columbia in July of 1997. An interesting phenomenon resulting from liquid flow in an annular film was observed while investigating operation of the experimental CPL in low gravity. To the authors' knowledge, observation of this phenomenon has not been previously reported. In every test run performed, liquid would accumulate in the curved portion of the vapor leg. The accumulation of liquid would continue until the liquid lobe would suddenly transition into a slug of liquid. The liquid slug would prevent the flow of vapor to the condenser; eventually resulting in dryout of the condenser. Since liquid was no longer fed to the evaporator from the condenser, the CPL would ultimately fail. Analysis reveals that the formation of the slug is a consequence of both capillary pressure differences in the liquid film present in the curved section of the vapor leg and a long wavelength instability of the liquid film. This analysis also reveals the conditions under which the formation of such liquid slugs are inevitable. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. Univ Dayton, Dept Mech & Aerosp Engn, Dayton, OH 44169 USA. RP Allen, JS (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Mail Stop 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 25 TC 6 Z9 7 U1 2 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0017-9310 J9 INT J HEAT MASS TRAN JI Int. J. Heat Mass Transf. PD OCT PY 2001 VL 44 IS 20 BP 3931 EP 3940 DI 10.1016/S0017-9310(01)00036-9 PG 10 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA 462KK UT WOS:000170419100014 ER PT J AU Mikata, Y AF Mikata, Y TI Explicit determination of piezoelectric Eshelby tensors for a spheroidal inclusion SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article DE spheroidal inclusion; piezoelectric; Eshelby tensors ID COMPOSITE-MATERIALS; INHOMOGENEITIES; MEDIA AB In this paper, by systematically treating the integrals involved in the piezoelectric inclusion problem, we have obtained explicit results for the piezoelectric Eshelby tensors for a spheroidal inclusion aligned along the axis of the anisotropy in a transversely isotropic piezoelectric material. This problem was first treated by Dunn and Wienecke (Int. J. Solids Struct. 34 (27), 3571-3582) using a Green's function approach, which closely follows Withers' approach (Phil. Mag. A 59 (4), 759-781) for an ellipsoidal inclusion problem in a transversely isotropic elastic medium. The same problem was recently treated by Michelitsch and Levin (Eur. Phys. J. B 14, 527-533), who also used a Green's function approach. In this paper, we also obtain the piezoelectric Eshelby tensors for a spheroidal inclusion explicitly, but using a different approach. The method is a direct extension of a more unified approach, which has been recently developed by Mikata (Int. J. Engng. Sci. 38, 608-641), which is based on Deeg's results (Ph.D. dissertation, Stanford University) on a piezoelectric inclusion problem. The main advantage of this method is that it is more straightforward and simpler than Dunn and Wienecke (1996), or Michelitsch and Levin (2000), and the results are a little bit more explicit than their solutions. The key step of this paper is an analytical evaluation of several integrals, which was made possible after a careful treatment of a certain bi-cubic equation. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Inst Computat & Appl Mech, Hampton, VA 23681 USA. RP Mikata, Y (reprint author), Lockheed Martin Co, POB 1072, Moscow 123098, Russia. NR 17 TC 38 Z9 38 U1 2 U2 11 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7683 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD OCT PY 2001 VL 38 IS 40-41 BP 7045 EP 7063 DI 10.1016/S0020-7683(00)00419-4 PG 19 WC Mechanics SC Mechanics GA 471LZ UT WOS:000170932000001 ER PT J AU Chuang, KC Bowles, KJ Papadopoulos, DS Hardy-Green, D McCorkle, LS AF Chuang, KC Bowles, KJ Papadopoulos, DS Hardy-Green, D McCorkle, LS TI A high T-g PMR polyimide composites (DMBZ-15) SO JOURNAL OF ADVANCED MATERIALS LA English DT Article ID TEMPERATURE AB A high T-g thermosetting PMR-type polyimide, designated as DMBZ-15, was developed by replacing methylene dianline (MDA) in PMR-15 with 2,2'-dimethylbenzidine. Polyimide/carbon fiber (T650-35) composites were fabricated from a formulation of 3,3' 4,4'-benzophenonetetracarboxylic acid dimethyl ester (BTDE) and 2,2'-dimethylbenzidine (DMBZ), along with nadic ester (NE) as the endcap. DMBZ-15 displays a higher glass transition temperature (T-g = 414 degreesC than PMR-15 (T-g = 345degreesC), and thus retains better mechanical properties,for brief exposure above 400degreesC The physical properties and long-term thermo-oxidative stability of the DMBZ-15 polyimide/carbon fiber composites are also compared to that of PMR-15 composites. C1 NASA, Glenn Res Ctr, Cleveland, OH USA. Univ Akron, Akron, OH 44325 USA. Gilcrest Corp, Cleveland, OH USA. RP Chuang, KC (reprint author), NASA, Glenn Res Ctr, Cleveland, OH USA. NR 13 TC 5 Z9 12 U1 1 U2 10 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 1070-9789 J9 J ADV MATER-COVINA JI J. Adv. Mater. PD OCT PY 2001 VL 33 IS 4 BP 33 EP 38 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA 509KF UT WOS:000173146400006 ER PT J AU Li, L Frunzio, L Wilson, C Prober, DE Szymkowiak, AE Moseley, SH AF Li, L Frunzio, L Wilson, C Prober, DE Szymkowiak, AE Moseley, SH TI Improved energy resolution of x-ray single photon imaging spectrometers using superconducting tunnel junctions SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID DETECTORS; NOISE; DYNAMICS AB We present measurements of the energy resolution of improved single-photon imaging x-ray spectrometers based on superconducting tunnel junctions. The devices have a Ta film absorber with an Al/AlOx/Al tunnel junction on each end. Recent device designs optimized for better quasiparticle cooling in the Al trap obtain an energy resolution of 13 eV full width at half maximum for a photon energy E=5.9 keV, an improvement of a factor of two over earlier devices. We also determined that the niobium contact used in previous devices degraded the energy resolution in the center section of the absorber. With a different contact configuration, we have eliminated this spatial broadening. (C) 2001 American Institute of Physics. C1 Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. Yale Univ, Dept Phys, New Haven, CT 06520 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Li, L (reprint author), Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RI Wilson, Christopher/A-9676-2008; Moseley, Harvey/D-5069-2012; OI Frunzio, Luigi/0000-0002-0272-5481 NR 19 TC 27 Z9 27 U1 1 U2 1 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD OCT 1 PY 2001 VL 90 IS 7 BP 3645 EP 3647 DI 10.1063/1.1391422 PG 3 WC Physics, Applied SC Physics GA 474YY UT WOS:000171135900080 ER PT J AU Mehta, SK Kaur, I Grimm, EA Smid, C Feeback, DL Pierson, DL AF Mehta, SK Kaur, I Grimm, EA Smid, C Feeback, DL Pierson, DL TI Decreased non-MHC-restricted (CD56(+)) killer cell cytotoxicity after spaceflight SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE space immunology; microgravity; non-major histocompatibility complex-restricted killer cell ID IMMUNE CHANGES; DURATION MISSIONS; SPACE-FLIGHT; RADIOIMMUNOASSAY; REACTIVATION; ASTRONAUTS; PLASMA; SERUM AB Cytotoxic activity of non-major histocompatibility complex-restricted (CD56(+)) (NMHC) killer cells and cell surface marker expression of peripheral blood mononuclear cells were determined before and after spaceflight. Ten astronauts (9 men, 1 woman) from two space shuttle missions (9- and 10-day duration) participated in the study. Blood samples were collected 10 days before launch, within 3 h after landing, and 3 days after landing. All peripheral blood mononuclear cell preparations were cryopreserved and analyzed simultaneously in a 4-h cytotoxicity Cr-51 release assay using K562 target cells. NMHC killer cell lytic activity was normalized per 1,000 CD56(+) cells. When all 10 subjects were considered as one study group, NMHC killer cell numbers did not change significantly during the three sampling periods, but at landing lytic activity had decreased by similar to 40% (P < 0.05) from preflight values. Nine of ten astronauts had decreased lytic activity immediately after flight. NMHC killer cell cytotoxicity of only three astronauts returned toward preflight values by 3 days after landing. Consistent with decreased NMHC killer cell cytotoxicity, urinary cortisol significantly increased after landing compared with preflight levels. Plasma cortisol and ACTH levels at landing were not significantly different from preflight values. No correlation of changes in NMHC killer cell function or hormone levels with factors such as age, gender, mission, or spaceflight experience was found. After landing, expression of the major lymphocyte surface markers (CD3, CD4, CD8, CD14, CD16, CD56), as determined by flow cytometric analysis, did not show any consistent changes from measurements made before flight. C1 NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Enterprise Advisory Serv Inc, Houston, TX 77058 USA. Univ Texas, MD Anderson Canc Ctr, Dept Tumor Biol, Houston, TX 77030 USA. RP Pierson, DL (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SF24, Houston, TX 77058 USA. NR 27 TC 21 Z9 26 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 OCT PY 2001 VL 91 IS 4 BP 1814 EP 1818 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 474VV UT WOS:000171128300040 PM 11568167 ER PT J AU Petrukovich, AA Klimov, SI Lazarus, A Lepping, RP AF Petrukovich, AA Klimov, SI Lazarus, A Lepping, RP TI Comparison of the solar wind energy input to the magnetosphere measured by Wind and Interball-1 SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE solar wind; interplanetary magnetic field; magnetospheric storms; magnetospheric substorms ID MAGNETIC-FIELD STRUCTURES; SPACECRAFT; CONVECTION AB Timely solar wind measurements are indispensable for space weather forecasts and magnetospheric studies, but solar wind variations detected by a distant spacecraft might be different from those actually hitting Earth's magnetosphere. To determine how important these differences can be for geophysical applications, we compared energy input to the magnetosphere which was simultaneously measured by the Wind and Interball-1 spacecraft at various distances from the Earth. The percentage of equal (with differences less than 15%) measurements was found to increase from 30% at energies associated with small substorms to 100% for storm-level energies. The degree of tho spacecraft separation along the X GSE coordinate and in the YZ GSE plane appeared to be of minor importance within the limits of Wind and Interball-1 orbits. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Space Res Inst, Moscow 117810, Russia. MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Lab Extraterr Phys, Greenbelt, MD 20771 USA. RP Petrukovich, AA (reprint author), Space Res Inst, 84-32 Profsoyuznaya St, Moscow 117810, Russia. RI Petrukovich, Anatoly/G-8764-2011 OI Petrukovich, Anatoly/0000-0002-5344-2967 NR 15 TC 5 Z9 5 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 OCT PY 2001 VL 63 IS 15 BP 1643 EP 1647 DI 10.1016/S1364-6826(01)00039-6 PG 5 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 476TZ UT WOS:000171246000007 ER PT J AU Mauget, BR Minnetyan, L Chamis, CC AF Mauget, BR Minnetyan, L Chamis, CC TI Computational tracking of composite manufacturing with fiber preforms SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE braided fiber preforms; composites; composite manufacturing; computational simulation; damage progression; fiber angle changes; preform molding; progressive fracture; shape fitting; structural durability AB The use of braided fiber preforms is a cost-effective process for the manufacturing of composite aircraft structures. For a rational design, it is necessary to predict the fiber orientations in the composite structure after molding. Whenever the manufacturing process requires the manipulation of fiber weaves, large strains and, therefore, significant changes in the fiber orientations occur due to the application of small traction. This drastically changes the mechanical properties of the final structure. To quantify this effect, a new method to simulate the large deformation behavior of fiber preforms has been developed and is presented. The method uses a laminate analogy model with very low stiffness matrix to compute the finite element properties. The assumptions are made that fibers do not elongate, the laminate is made of symmetrically woven fibers, and that, during a finite element step, the properties can be assumed constant. Based on these assumptions, a simple way to compute the fiber changes is proposed, as it is remarked that a box with fibers as its diagonal will deform into a box of different aspect ratio. The large displacement approach is valid since the properties depend on the global Poisson ratio computation that is proved accurate. The method is then demonstrated by an example, where a fiber weave preform is shaped over a mold. The resulting fiber orientations are analyzed to evaluate the effect of the manufacturing process on structure properties and durability. The advantage of the present method is further demonstrated by evaluating the damage tolerance of the composite structure via progressive fracture. C1 Clarkson Univ, Potsdam, NY 13699 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Mauget, BR (reprint author), Clarkson Univ, Potsdam, NY 13699 USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 USA SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD OCT PY 2001 VL 23 IS 4 BP 254 EP 258 PG 5 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA 491AK UT WOS:000172085700003 ER PT J AU Gross, FB Grek, SB Calle, CI Lee, RU AF Gross, FB Grek, SB Calle, CI Lee, RU TI JSC Mars-1 Martian Regolith simulant particle charging experiments in a low pressure environment SO JOURNAL OF ELECTROSTATICS LA English DT Article DE triboelectricity; charging of soil; Martian soil simulant; Faraday cup; low-pressure solids charging ID ELECTRIFICATION AB NASA has a keen interest in Martian dust particle charging as it impacts future Mars missions. The particle charging can be used in experiments to help gather information about atmospheric electrostatics, saltation, and tribo-electric charging. Additionally, the charging could also be a nuisance for equipment because of the potential hazard of electrostatic adhesion and discharge. In order to gather more information about the nature of particle charging at Martian atmospheric pressures, experiments were performed in a 7Torr environment testing the contact and frictional charging of the JSC Mars-1 Martian Regolith simulant. An apparatus was devised that dropped the simulant down a deflection board whose surfaces were coated with various materials of interest. The particles were illuminated by a UV source as they fell. The UV illumination was added to consider whether the surface states of the particles would be augmented to permit greater tribo-charging. The charged particles would then exit the board into a Faraday cup to measure the amount of charge accumulated using an electrometer. The materials used on the deflection board surfaces included copper, glass and acetate. The UV source did not significantly alter the experimental outcomes. (C) 2001 Elsevier Science B.V. All rights reserved. C1 FSU, FAMU, Coll Engn, Dept Elect & Comp Engn, Tallahassee, FL 32310 USA. NASA, Kennedy Space Ctr, Kennedy Space Ctr, FL 32899 USA. RP Gross, FB (reprint author), FSU, FAMU, Coll Engn, Dept Elect & Comp Engn, Tallahassee, FL 32310 USA. NR 13 TC 26 Z9 27 U1 5 U2 11 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-3886 J9 J ELECTROSTAT JI J. Electrost. PD OCT PY 2001 VL 53 IS 4 BP 257 EP 266 DI 10.1016/S0304-3886(01)00152-8 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA 489XD UT WOS:000172017100001 ER PT J AU Darden, JM Earhart, EM Flowers, GT AF Darden, JM Earhart, EM Flowers, GT TI Comparison of the dynamic characteristics of smooth annular seals and damping seals SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-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 ID COEFFICIENTS AB Annular seals are known to enhance rotordynamic stability margins and minimize vibration response levels in high-speed rotating machinery. Theoretical predictions for the rotordynamic characteristics of annular seals exist but additional experimental data is needed to properly anchor these results. NASA Marshall Space Flight Center (MSFC) has developed an annular seal test rig and facility to experimentally characterize axially fed annular seals. Annular seals with deliberately roughened stators (i.e., damping seals) have been shown analytically to increase stability margins of rocket engine turbomachinery, by reducing the seal's whirl frequency ratio. The capabilities of MSFC annular seal test rig have been enhanced to allow high fluid inlet preswirl testing that is more representative of actual turbopump seal boundary conditions. The purpose of this paper is to describe the effect of this realistic preswirl on the stabilizing capability of both damping and smooth seals. Centered seal results are presented for both a smooth annular seal and a clamping seal. These results were obtained for a range of seal pressure differentials, shaft rotational speeds, and two levels of inlet fluid preswirl. C1 NASA, George C Marshall Space Flight Ctr, MSFC, Huntsville, AL 35812 USA. Auburn Univ, Dept Mech Engn, Auburn, AL 36849 USA. RP Darden, JM (reprint author), NASA, George C Marshall Space Flight Ctr, MSFC, TD55,Bldg 4203, Huntsville, AL 35812 USA. NR 7 TC 1 Z9 2 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD OCT PY 2001 VL 123 IS 4 BP 857 EP 863 DI 10.1115/1.1383256 PG 7 WC Engineering, Mechanical SC Engineering GA 488KP UT WOS:000171934600019 ER PT J AU Judge, J Pierre, C Mehmed, O AF Judge, J Pierre, C Mehmed, O TI Experimental investigation of mode localization and forced response amplitude magnification for a mistuned bladed disk SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY AB The results of an experimental investigation on the effects of random blade mistuning on the forced dynamic response of bladed disks are reported. The primary aim of the experiment is to gain understanding of the phenomena of mode localization and forced response blade amplitude magnification in bladed disks. A stationary nominally periodic, 12-bladed disk with simple geometry is subjected to a traveling-wave out-of-plane "engine order" excitation delivered via phase-shifted control signals sent to piezoelectric actuators mounted on the blades. The bladed disk is then mistuned by the addition of small, unequal weights to the blade tips. and it is again subjected to a traveling wave excitation. The experimental data is used to verify analytical predictions about the occurrence of localized mode shapes, increases in forced response amplitude, and changes in resonant frequency due to the presence of mistuning. Very good agreement between experimental measurements and finite element analysis is obtained. The out-of-plane response is compared and contrasted with the previously reported in-plane mode localization behavior of the same test specimen. This work also represents an important extension of previous experimental study by investigating a frequency regime in which modal density is lower but disk-blade interaction is significantly greater. C1 Univ Michigan, Dept Mech Engn, Ann Arbor, MI 48109 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Judge, J (reprint author), Univ Michigan, Dept Mech Engn, Ann Arbor, MI 48109 USA. RI Judge, John/D-1429-2015 NR 27 TC 26 Z9 33 U1 1 U2 4 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD OCT PY 2001 VL 123 IS 4 BP 940 EP 950 DI 10.1115/1.1377872 PG 11 WC Engineering, Mechanical SC Engineering GA 488KP UT WOS:000171934600029 ER PT J AU Estlin, TA Chien, SA Wang, XM AF Estlin, TA Chien, SA Wang, XM TI Hierarchical task network and operator-based planning: two complementary approaches to real-world planning SO JOURNAL OF EXPERIMENTAL & THEORETICAL ARTIFICIAL INTELLIGENCE LA English DT Article DE planning; hierarchical task network planning; operator-based planning AB Work on generative planning systems has focused on two diverse approaches to plan construction. Hierarchical task network (HTN) planners build plans by successively refining high-level goals into lower-level activities. Operator-based planners employ means-end analysis to directly formulate plans consisting of low-level activities. While many have argued the universal dominance of a single approach, this paper presents an alternative view: that in different situations either may be most appropriate. To support this view, a number of advantages and disadvantages of these approaches are described in light of experiences in developing two real-world, fielded planning systems. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NR 15 TC 2 Z9 2 U1 1 U2 3 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK,, ABINGDON OX14 4RN, OXON, ENGLAND SN 0952-813X J9 J EXP THEOR ARTIF IN JI J. Exp. Theor. Artif. Intell. PD OCT PY 2001 VL 13 IS 4 BP 379 EP 395 DI 10.1080/09528130110101288 PG 17 WC Computer Science, Artificial Intelligence SC Computer Science GA 517NB UT WOS:000173615800004 ER PT J AU Byun, SH Schutz, BE AF Byun, SH Schutz, BE TI Improving satellite orbit solution using double-differenced GPS carrier phase in kinematic mode SO JOURNAL OF GEODESY LA English DT Article DE kinematic; orbit determination; double difference; ambiguity search; GPS AB The limit of orbit accuracy associated with processing the ionospheric-free double-differenced (DD) GPS carrier phase observable in pure kinematic mode is investigated. The kinematic orbit determination problem becomes unobservable when the satellite positions at all epochs and all of the DD ambiguities are estimated simultaneously without any constraints. Although searching for some of the DD ambiguities can make the problem observable, this is not practical when the DD ambiguities are not integers. However, if a reasonably accurate a priori satellite orbit solution is available, epoch-by-epoch satellite positions and the DD ambiguities can be estimated by constraining a geometrically strong DD pass. The technique was demonstrated with TOPEX GPS data, which gave a final radial RMS orbit accuracy of 4 cm with respect to a fully dynamic solution. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Texas, Ctr Space Res, Austin, TX 78759 USA. RP Byun, SH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 238-600, Pasadena, CA 91109 USA. NR 6 TC 4 Z9 5 U1 0 U2 3 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0949-7714 J9 J GEODESY JI J. Geodesy PD OCT PY 2001 VL 75 IS 9-10 BP 533 EP 543 DI 10.1007/s001900100205 PG 11 WC Geochemistry & Geophysics; Remote Sensing SC Geochemistry & Geophysics; Remote Sensing GA 498BH UT WOS:000172489600007 ER PT J AU Burlaga, LF Skoug, RM Smith, CW Webb, DF Zurbuchen, TH Reinard, A AF Burlaga, LF Skoug, RM Smith, CW Webb, DF Zurbuchen, TH Reinard, A TI Fast ejecta during the ascending phase of solar cycle 23: ACE observations, 1998-1999 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; INTER-PLANETARY SHOCK; COSMIC-RAY DECREASES; MAGNETIC CLOUDS; ELECTRON-TEMPERATURE; INTERPLANETARY SHOCK; GEOMAGNETIC STORMS; COMPOUND STREAMS; FIELD STRUCTURE; WIND AB We discuss fast ejecta observed at 1 AU during a period of increasing solar activity from February 5, 1998, to November 29, 1999. "Fast ejecta" are transient, noncorotating flows that move past the Earth during a day or more, with a maximum speed > 600 km s(-1). We identify two classes of fast ejecta at 1 AU: (1) magnetic clouds, whose local magnetic structure is that of a flux rope; and (2) "complex ejecta," which are not flux ropes and have disordered magnetic fields. Nearly equal numbers of magnetic clouds and complex ejecta were found: four and five, respectively. The complex ejecta had weaker magnetic fields and higher proton temperatures than the magnetic clouds on average. The average beta for the complex ejecta (0.25 +/- 0.09) was larger than that for the magnetic clouds (0.06 +/- 0.04). The complex ejecta and magnetic clouds had comparable speeds on average, namely, 558 +/- 80 and 500 +/- 63 km s(-1), respectively. Using the duration of the stream and that of the counterstreaming electrons to measure the ejecta, the average time for the complex ejecta to move past ACE was 3 days, which is more than twice that for the magnetic clouds. All of the magnetic clouds contain some material with a high alpha /proton density ratio (>8%) and a density ratio of O7+/O6+ > 1. However, three of the five complex ejecta did not contain material with O7+/O6+ > 1, although four of the complex ejecta contained material with O7+/O6+ > 1. All of the magnetic clouds caused geomagnetic storms. Three complex ejecta produced no geomagnetic storms. The other two complex ejecta produced geomagnetic storms indirectly: one by driving a shock into the rear of a magnetic cloud and the other by amplifying southward fields in its leading edge and interaction region. Most of the magnetic clouds were associated with a single solar source, but nearly all of the complex ejecta could have had multiple sources. We find evidence in the solar observations that some of the complex ejecta could have been produced by the interaction of two or more coronal mass ejections (CMEs). At least three CMEs might have interacted to produce a large complex ejection that arrived at 1 AU on May 4, 1998. This complex ejection was overtaking and interacting with a magnetic cloud. We discuss several hypotheses concerning the structures and origins of complex ejecta, including the likely possibility that some complex ejecta are formed by a series of interacting CMEs of various sizes. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19711 USA. Boston Coll, Inst Sci Res, Chestnut Hill, MA 02167 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. RP Burlaga, LF (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RI Reinard, Alysha/H-7808-2013 OI Reinard, Alysha/0000-0003-0304-2989 NR 72 TC 109 Z9 113 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD OCT 1 PY 2001 VL 106 IS A10 BP 20957 EP 20977 DI 10.1029/2000JA000214 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475XG UT WOS:000171194600003 ER PT J AU Cohen, CMS Mewaldt, RA Cummings, AC Leske, RA Stone, EC Slocum, PL Wiedenbeck, ME Christian, ER von Rosenvinge, TT AF Cohen, CMS Mewaldt, RA Cummings, AC Leske, RA Stone, EC Slocum, PL Wiedenbeck, ME Christian, ER von Rosenvinge, TT TI Forecasting the arrival of shock-accelerated solar energetic particles at Earth SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ADVANCED-COMPOSITION-EXPLORER AB Energetic particles accelerated at interplanetary shocks can result in an increased radiation dose for astronauts as well as an increased risk to satellite hardware. These shocks are known to occasionally accelerate protons to energies greater than 100 MeV and can result in very high fluxes. Advanced warning of the arrival of strong interplanetary shocks can enable steps to be taken to minimize the potential risks. In an effort to monitor and assess the radiation risk to astronauts, two real-time count rate monitors were implemented in the Solar Isotope Spectrometer (SIS) on the ACE spacecraft. These rates measure protons with energies > 10 and > 30 MeV. Since ACE is located at the L1 Lagrangian point, these rates provide information and warning up to 1 hour before an interplanetary shock reaches Earth. Using ACE and GOES, data we have examined examples of shocks and associated energetic particles that have been detected at ACE and were later observed near Earth in an effort to develop more fully the forecasting capability of ACE. Because of the limited amount of solar activity during 1997-1999, this current work is primarily a proof of concept. C1 CALTECH, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Cohen, CMS (reprint author), CALTECH, MC 220-47, Pasadena, CA 91125 USA. RI Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 12 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD OCT 1 PY 2001 VL 106 IS A10 BP 20979 EP 20983 DI 10.1029/2000JA000216 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475XG UT WOS:000171194600004 ER PT J AU Le, G Raeder, J Russell, CT Lu, G Petrinec, SM Mozer, FS AF Le, G Raeder, J Russell, CT Lu, G Petrinec, SM Mozer, FS TI Polar cusp and vicinity under strongly northward interplanetary magnetic field on April 11, 1997: Observations and MHD simulations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID HIGH-LATITUDE MAGNETOPAUSE; BOUNDARY-LAYER; IONOSPHERIC CONVECTION; MAGNETOSHEATH PLASMA; MAGNETOSPHERIC CUSPS; DAYSIDE MAGNETOPAUSE; EARTHS MAGNETOPAUSE; RECONNECTION; INSTRUMENT; SPACECRAFT AB We present a correlative case study of the solar wind interaction with the magnetosphere using in situ observations of the polar cusp and surrounding regions, ground-based and low-altitude spacecraft polar cap observations, and global MHD simulations during an extended period of strongly northward interplanetary magnetic field (IMF) on April 11, 1997. Within this extended period of strongly northward IMF, the Polar spacecraft entered a region with magnetosheath-like plasma and field lines above the polar cusp. Data from multiple instruments on Polar showed that the observed signatures can be interpreted as Polar entering the reconnection layer and crossing the current layer associated with it. The magnetosheath-like field lines encountered by Polar have just reconnected poleward of the polar cusp in the north. The reversed ionospheric convection patterns derived from the assimilative mapping of ionospheric electrodynamics (AMIE) technique show the reversed convection over the polar cap due to high-latitude reconnection throughout the whole interval. MHD simulations were performed using solar wind parameters observed by Wind, supporting the cusp reconnection interpretation. C1 Natl Ctr Atmospher Res, High Altitude Observ, Boulder, CO 80307 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Lockheed Martin Adv Technol Ctr, Space Phys Lab, Palo Alto, CA 94304 USA. RP Le, G (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 696, Greenbelt, MD 20771 USA. RI Lu, Gang/A-6669-2011; Le, Guan/C-9524-2012 OI Le, Guan/0000-0002-9504-5214 NR 47 TC 14 Z9 14 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 OCT 1 PY 2001 VL 106 IS A10 BP 21083 EP 21093 DI 10.1029/2000JA900091 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475XG UT WOS:000171194600014 ER PT J AU Kruschwitz, CA Kelley, MC Gardner, CS Swenson, G Liu, AZ Chu, X Drummond, JD Grime, BW Armstrong, WT Plane, JMC Jenniskens, P AF Kruschwitz, CA Kelley, MC Gardner, CS Swenson, G Liu, AZ Chu, X Drummond, JD Grime, BW Armstrong, WT Plane, JMC Jenniskens, P TI Observations of persistent Leonid meteor trails 2. Photometry and numerical modeling SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SPECTRA; SHOWER; SODIUM; LIDAR AB During the 1998 Leonid meteor shower, multi-instrument observations of persistent meteor trains were made from the Starfire Optical Range on Kirtland Air Force Base, New Mexico, and from a secondary site in nearby Placitas, New Mexico. The University of Illinois Na resonance lidar measured the Na density and temperature in the trains, while various cameras captured images and videos of the trains, some of which were observed to persist for more than 30 min. The Na density measurements allow the contribution of Na airglow to the observed train luminescence to be quantified for the first time. To do this, persistent train luminescence is numerically modeled. Cylindrical symmetry is assumed, and observed values of the Na density, temperature, and diffusivity are used. It is found that the expected Na luminosity is consistent with narrowband CCD all-sky camera observations, but that these emissions can contribute only a small fraction of the total light observed in a 0.5-1 mu bandwidth. Other potential luminosity sources are examined, in particular, light resulting from the possible excitation of monoxides of meteoric metals (particularly FeO) and O-2(b(1)Sigma (+)(g)) during reactions between atmospheric oxygen species and meteoric metals. It is found that the total luminosity of these combined processes falls somewhat short of explaining the observed brightness, and thus additional luminosity sources still are needed. In addition, the brightness distribution, the so-called hollow cylinder effect, remains unexplained. C1 Cornell Univ, Sch Elect & Comp Engn, Ithaca, NY 14853 USA. Cornell Univ, Sch Elect & Comp Engn, Ithaca, NY 14853 USA. Univ Illinois, Dept Elect & Comp Engn, Urbana, IL 61801 USA. USAF, Res Lab, Starfire Opt Range, Kirtland AFB, NM 87117 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ E Anglia, Sch Environm Sci, Norwich NR4 7TJ, Norfolk, England. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Kruschwitz, CA (reprint author), Cornell Univ, Sch Elect & Comp Engn, 304 Rhodes Hall, Ithaca, NY 14853 USA. RI Plane, John/C-7444-2015; Chu, Xinzhao/I-5670-2015; Liu, Alan/C-3738-2008 OI Plane, John/0000-0003-3648-6893; Chu, Xinzhao/0000-0001-6147-1963; Liu, Alan/0000-0002-1834-7120 NR 28 TC 20 Z9 20 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD OCT 1 PY 2001 VL 106 IS A10 BP 21525 EP 21541 DI 10.1029/2000JA000174 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475XG UT WOS:000171194600049 ER PT J AU Sibeck, DG Decker, RB Mitchell, DG Lazarus, AJ Lepping, RP Szabo, A AF Sibeck, DG Decker, RB Mitchell, DG Lazarus, AJ Lepping, RP Szabo, A TI Solar wind preconditioning in the flank foreshock: IMP 8 observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EARTHS BOW SHOCK; DIAMAGNETIC CAVITIES UPSTREAM; 3-DIMENSIONAL PLASMA; PRESSURE VARIATIONS; CURRENT SHEET; MAGNETOPAUSE; HOT; EVENTS AB We use IMP 8 plasma, magnetic field, and energetic ion observations within the Earth's foreshock from January through August 1995 to determine the effects of energetic ion bursts on the ambient solar wind for comparison with model predictions. Owing to the spiral interplanetary magnetic field orientation, the events are far more common upstream from the prenoon than postnoon bow shock. Pressures associated with the energetic ions depress foreshock magnetic field strengths and plasma densities. The magnitude of the depression is proportional to the intensity of energetic ions. The excavated plasma and magnetic field sometimes pile up in narrow regions of enhanced plasma densities and magnetic field strengths, but depressed flow velocities, just outside the foreshock cavities. Typical amplitudes of the depressions and enhancements at IMP 8 far upstream from the bow shock are far less (20% and 10%, respectively) than those seen in past case studies of events observed just outside the bow shock. The cavities occur preferentially during high-speed solar wind streams but show no clear dependence upon other solar wind parameters. The distribution of burst durations resembles those for interarrival times for interplanetary magnetic field discontinuities, magnetopause motion, and flux transfer events, suggesting causal relationships between these phenomena. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. MIT, Space Res Ctr, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sibeck, DG (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. RI Sibeck, David/D-4424-2012 NR 44 TC 28 Z9 28 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 OCT 1 PY 2001 VL 106 IS A10 BP 21675 EP 21688 DI 10.1029/2000JA000417 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475XG UT WOS:000171194600061 ER PT J AU Simpson, JE Garimella, SV de Groh, HC Abbaschian, R AF Simpson, JE Garimella, SV de Groh, HC Abbaschian, R TI Bridgman crystal growth of an alloy with thermosolutal convection under microgravity conditions SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Article ID SOLIDIFICATION; SEGREGATION AB The solidification of a dilute alloy (bismuthtin) tender Bridgman crystal growth conditions is investigated. Computations are pe formed in two dimensions with a uniform grid. The simulation includes the species concentration, temperature and flow fields, as well as conduction in the ampoule. Fully transient simulations have been performed, with no simplifying steady state approximations. Results tire obtained under microgravity conditions for pure bismuth, and for Bi-0.1 at. % Sn and Bi- 1.0 at. % Sn alloys, and compared with experimental results obtained from crystals grown in the microgravity, environment of space. For the Bi-1.0 at. % Sn case the results indicate that a secondary convective cell, driven by solutal gradients, forms near the interface. The magnitude of the velocities in this cell increases with time, causing increasing solute segregation tit the solid/liquid interface. Finally, a comparison between model predictions and results obtained from a space experiment is reported. The concentration-dependence of the alloy melting temperature is incorporated in the model for this case. Satisfactory correspondence is obtained between the predicted and experimental results in terms of solute concentrations in the solidified crystal. C1 Purdue Univ, Sch Mech Engn, W Lafayette, IN 47907 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Florida, Dept Mat Sci & Engn, Gainesville, FL 32611 USA. RP Simpson, JE (reprint author), Purdue Univ, Sch Mech Engn, W Lafayette, IN 47907 USA. RI Garimella, Suresh/A-1286-2013 OI Garimella, Suresh/0000-0003-1421-2912 NR 24 TC 3 Z9 3 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0022-1481 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD OCT PY 2001 VL 123 IS 5 BP 990 EP 998 DI 10.1115/1.1389058 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 480UB UT WOS:000171480200020 ER PT J AU Dougherty, DJ Muller, RE Maker, PD Forouhar, S AF Dougherty, DJ Muller, RE Maker, PD Forouhar, S TI Stitching-error reduction in gratings by shot-shifted electron-beam lithography SO JOURNAL OF LIGHTWAVE TECHNOLOGY LA English DT Article DE diffraction; electron-beam lithography; gratings; integrated optics; semiconductor lasers ID LASER-DIODES; DFB LASERS; LINEWIDTH AB Calculations of the grating spatial-frequency spectrum and the filtering properties of multiple-pass electron-beam writing demonstrate a tradeoff between stitching-error suppression and minimum pitch separation. High-resolution measurements of optical-diffraction patterns show a 25-dB reduction in stitching-error side modes. C1 Scion Photon, Milpitas, CA 95035 USA. CALTECH, Jet Prop Lab, Microdevices Lab, Pasadena, CA 91109 USA. RP Dougherty, DJ (reprint author), Scion Photon, Milpitas, CA 95035 USA. NR 7 TC 13 Z9 13 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 0733-8724 J9 J LIGHTWAVE TECHNOL JI J. Lightwave Technol. PD OCT PY 2001 VL 19 IS 10 BP 1527 EP 1531 DI 10.1109/50.956140 PG 5 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA 481UF UT WOS:000171538300014 ER PT J AU Wang, Y Grant, J Sharma, A Myers, G AF Wang, Y Grant, J Sharma, A Myers, G TI Modified Talbot interferometer for fabrication of fiber-optic grating filter over a wide range of Bragg wavelength and bandwidth using a single phase mask SO JOURNAL OF LIGHTWAVE TECHNOLOGY LA English DT Article DE Bragg gratings; broadband; chirped gratings; optical fiber filters; optical fibers; tilted fiber Bragg gratings (FBGs) ID LASER; EXPOSURE AB A technique involving a compact apparatus that combines the phase mask and two-beam interferometric techniques is presented. It involves the use of a phase mask to diffract the ultraviolet (UV) beam and a cylindrical lens combined with a pair of mirrors to produce two symmetric virtual line sources of UV light. Bragg wavelength and bandwidth of the fiber gratings can be controlled with a simple translation of the fiber and/or the phase mask. Using a 40-mw continuous-wave frequency-doubled argon-ion laser at 244 nm and a single phase mask, a series of chirped fiber gratings with the Bragg wavelength in a wide range around 600 nm and 1300 nm are fabricated in hydrogen-loaded ordinary fibers. C1 Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Wang, Y (reprint author), Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. NR 19 TC 16 Z9 16 U1 1 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0733-8724 J9 J LIGHTWAVE TECHNOL JI J. Lightwave Technol. PD OCT PY 2001 VL 19 IS 10 BP 1569 EP 1573 DI 10.1109/50.956144 PG 5 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA 481UF UT WOS:000171538300018 ER PT J AU Li, YF Froggatt, M Erdogan, T AF Li, YF Froggatt, M Erdogan, T TI Volume current method for analysis of tilted fiber gratings SO JOURNAL OF LIGHTWAVE TECHNOLOGY LA English DT Article DE gratings; optical fiber devices; optical propagation; optical waveguide theory; phase matching; polarization ID RADIATION LOSS AB An analytic approach to calculate the radiation pattern (including the wavelength dependence, azimuthal distribution, and polarization dependence) of tilted fiber phase gratings using the volume current method (VCM) is introduced in this paper. Results for both uniform and apodized fiber gratings are derived and discussed, and a brief comparison to experimental measurements from practical devices is also made. C1 Univ Rochester, Dept Elect & Comp Engn, Rochester, NY 14627 USA. Univ Rochester, Inst Opt, Rochester, NY 14627 USA. Luna Technol, Blacksburg, VA 24062 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Li, YF (reprint author), Semrock Inc, Rochester, NY 14624 USA. NR 12 TC 42 Z9 46 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 0733-8724 J9 J LIGHTWAVE TECHNOL JI J. Lightwave Technol. PD OCT PY 2001 VL 19 IS 10 BP 1580 EP 1591 DI 10.1109/50.956146 PG 12 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA 481UF UT WOS:000171538300020 ER PT J AU Ponomarev, AL Sachs, RK AF Ponomarev, AL Sachs, RK TI Radiation breakage of DNA: a model based on random-walk chromatin structure SO JOURNAL OF MATHEMATICAL BIOLOGY LA English DT Article DE DNA fragment; double strand break; chromatin; ionizing radiation; Monte Carlo computer model; biopolymer; random walk ID DOUBLE-STRAND BREAKS; LINEAR-ENERGY-TRANSFER; FIELD GEL-ELECTROPHORESIS; INTERPHASE CHROMOSOMES; TRACK STRUCTURE; IONIZING-RADIATION; MAMMALIAN-CELLS; SIMULATION; FRAGMENTS; POLYMER AB Monte Carlo computer software, called DNAbreak, has recently been developed to analyze observed non-random clustering of DNA double strand breaks in chromatin after exposure to densely ionizing radiation. The software models coarse-grained configurations of chromatin and radiation tracks, small-scale details being suppressed in order to obtain statistical results for larger scales, up to the size of a whole chromosome. We here give an analytic counterpart of the numerical model, useful for benchmarks, for elucidating the numerical results, for analyzing the assumptions of a more general but less mechanistic "randomly-located-clusters" formalism, and, potentially, for speeding up the calculations. The equations characterize multi-track DNA fragment-size distributions in terms of one-track action; an important step in extrapolating high-dose laboratory results to the much lower doses of main interest in environmental or occupational risk estimation. The approach can utilize the experimental information on DNA fragment-size distributions to draw inferences about large-scale chromatin geometry during cell-cycle interphase. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Calif Berkeley, Dept Math, Berkeley, CA 94072 USA. RP Ponomarev, AL (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SN-3, Houston, TX 77058 USA. FU NIGMS NIH HHS [GM57245] NR 37 TC 7 Z9 7 U1 0 U2 0 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0303-6812 J9 J MATH BIOL JI J. Math. Biol. PD OCT PY 2001 VL 43 IS 4 BP 356 EP 376 DI 10.1007/s002850100098 PG 21 WC Biology; Mathematical & Computational Biology SC Life Sciences & Biomedicine - Other Topics; Mathematical & Computational Biology GA 492HR UT WOS:000172162800004 PM 12120873 ER PT J AU Boyle, R Mensinger, AF Yoshida, K Usui, S Intravaia, A Tricas, T Highstein, SM AF Boyle, R Mensinger, AF Yoshida, K Usui, S Intravaia, A Tricas, T Highstein, SM TI Neural readaptation to earth's gravity following return from space SO JOURNAL OF NEUROPHYSIOLOGY LA English DT Article ID SEMICIRCULAR CANAL AFFERENTS; INNERVATING OTOLITH ORGANS; VERTEBRATE HAIR-CELLS; RESPONSE DYNAMICS; SQUIRREL-MONKEY; OPSANUS-TAU; WEIGHTLESSNESS; SENSITIVITY; PHYSIOLOGY; DISCHARGE AB The consequence of exposure to microgravity on the otolith organs was studied by recording the responses of vestibular nerve afferents supplying the utricular otolith organ to inertial accelerations in four toadfish, Opsanus tau, sequentially for 5 days following two National Aeronautics and Space Administration shuttle orbital flights. Within the first day postflight, the magnitude of response to an applied translation was on average three times greater than for controls. The reduced gravitational acceleration in orbit apparently resulted in an upregulation of the sensitivity of utricular afferents. By 30 h postflight, responses were statistically similar to control. The time course of return to normal afferent sensitivity parallels the reported decrease in vestibular disorientation in astronauts following return from space. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Washington Univ, Sch Med, Dept Otolaryngol, St Louis, MO 63110 USA. Univ Tsukuba, Dept Physiol, Tsukuba, Ibaraki 3058575, Japan. Toyohashi Univ Technol, Toyohashi, Aichi 4418580, Japan. Oregon Hlth Sci Univ, Dept Otolaryngol Head & Neck Surg, Portland, OR 97201 USA. Florida Inst Technol, Dept Biol Sci, Melbourne, FL 32901 USA. RP Boyle, R (reprint author), NASA, Ames Res Ctr, M-S 239-11, Moffett Field, CA 94035 USA. FU NIDCD NIH HHS [P0-1 DC-01837] NR 26 TC 34 Z9 39 U1 0 U2 6 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0022-3077 J9 J NEUROPHYSIOL JI J. Neurophysiol. PD OCT PY 2001 VL 86 IS 4 BP 2118 EP 2122 PG 5 WC Neurosciences; Physiology SC Neurosciences & Neurology; Physiology GA 482EN UT WOS:000171562000052 PM 11600668 ER PT J AU Jones, SM AF Jones, SM TI Amine catalyzed condensation of tetraethylorthosilicate SO JOURNAL OF NON-CRYSTALLINE SOLIDS LA English DT Article ID HYDROLYSIS; SILICATES; GELS AB The catalysis of the condensation of hydrolyzed metal alkoxides by amines has been mentioned in the literature, but there has been no systematic study of their influence on the rate of the condensation reaction of the alkoxide and the microstructure of the resultant gel. The hydrolysis of tetraethylorthosilicate (TEOS) was catalyzed by a mineral acid and the condensation was catalyzed by various organic amines. The gelation times were found to vary widely with the different amines used as the catalyst and the microstructure of the resultant xerogels also differed significantly depending on the amine added. Gelation occurred in the shortest amount of time when 1.4-diazabicyclo{2 2 2} octane (DABCO) was used, whereas, systems catalyzed with imidazole (Im) and pyridine (Pyr) and their derivatives exhibited longer gel times and were composed of less coarse microstructures. (C) 2001 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jones, SM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MailStop 125-109, Pasadena, CA 91109 USA. NR 18 TC 16 Z9 17 U1 2 U2 8 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-3093 J9 J NON-CRYST SOLIDS JI J. Non-Cryst. Solids PD OCT PY 2001 VL 291 IS 3 BP 206 EP 210 DI 10.1016/S0022-3093(01)00858-4 PG 5 WC Materials Science, Ceramics; Materials Science, Multidisciplinary SC Materials Science GA 481JX UT WOS:000171517100009 ER PT J AU Blass, WE Hillman, JJ Fayt, A Daunt, SJ Senesac, LR Ewing, AC Jennings, LW Hager, JS Mahan, SL Reuter, DC Sirota, M AF Blass, WE Hillman, JJ Fayt, A Daunt, SJ Senesac, LR Ewing, AC Jennings, LW Hager, JS Mahan, SL Reuter, DC Sirota, M TI 10 mu m ethylene: spectroscopy, intensities and a planetary modeler's atlas SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID RAMAN INTENSITIES; FOURIER-TRANSFORM; ABINITIO AB FTS and TDL spectra of ethylene in the 10 mum region have been observed, measured, calibrated, assigned and intensities have been measured. The ultimate goal of this work is the production of a planetary modeler's atlas. A spectrum taken in double-pass configuration at the McMath-Pierce FTS instrument at Kitt Peak National Observatory has been frequency calibrated using CO2 laser bands. Results of a previous analysis (Cauuet et al., J Mol Spectrosc 1990;139:191) have enabled the assignment of the FTS spectrum wherein we have measured over 500 line intensities in the 900-1000 cm(-1) region. These FTS intensities have been calibrated against 13 isolated transitions, taken as secondary intensity standards. These standard lines have been measured independently using TDL (tunable-diode-laser) spectrometers at University of Tennessee and Goddard Space Flight Center. A calculated spectrum, including mixing coefficients for v(4), v(7), v(10) and v(12), and calculated relative intensities, and the TDL-calibrated FTS line intensities were used as data in a non-linear regression analysis to determine the 296 K vibrational band intensities of S-0-7(v) = 321.69 +/- 0.36 cm(-1)/cm atm, S-0-10(v) = 1.16 +/- 0.47 cm(-1)/cm atm, and S-0-12(v) = 31.60 +/- 9.80 cm(-1)/cm atm. These vibrational band intensities combined with the theoretical spectral-line atlas make possible the generation of an ethylene spectrum at an arbitrary temperature. Such spectra prove useful to the planetary-atmosphere modeling-community. A web site is available where an individual can interact with the model and download a custom atlas. The URL is http://aurora.phys.utk.edu/(similar to)blass/ethyatl/. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Tennessee, Dept Phys & Astron, Complex Syst Lab, Knoxville, TN 37996 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Catholique Louvain, Dept Phys, B-1348 Louvain, Belgium. Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA. NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. RP Blass, WE (reprint author), Univ Tennessee, Dept Phys & Astron, Complex Syst Lab, Knoxville, TN 37996 USA. RI Blass, William/A-2792-2008 NR 29 TC 26 Z9 26 U1 0 U2 2 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 OCT 1 PY 2001 VL 71 IS 1 BP 47 EP 60 DI 10.1016/S0022-4073(01)00011-5 PG 14 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 467RA UT WOS:000170716500005 ER PT J AU Howard, A Seraji, H AF Howard, A Seraji, H TI Vision-based terrain characterization and traversability assessment SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article AB This article presents novel techniques for real-time terrain characterization and assessment of terrain traversability for a field mobile robot using a vision system and artificial neural networks. The key terrain traversability characteristics are identified as roughness, slope, discontinuity, and hardness. These characteristics are extracted from imagery data obtained from cameras mounted on the robot and are represented in a fuzzy logic framework using perceptual, linguistic fuzzy sets. The approach adopted is highly robust and tolerant to imprecision and uncertainty inherent in sensing and perception of natural environments. The four traversability characteristics are combined to form a single Fuzzy Traversability Index, which quantifies the ease-of-traversal of the terrain by the mobile robot. Experimental results are presented to demonstrate the capability of the proposed approach for classification of different terrain segments based on their traversability. (C) 2001 John Wiley & Sons, Inc. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 57 Z9 59 U1 0 U2 11 PU JOHN WILEY & SONS INC PI HOBOKEN PA 111 RIVER ST, HOBOKEN, NJ 07030 USA SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD OCT PY 2001 VL 18 IS 10 BP 577 EP 587 DI 10.1002/rob.1046 PG 11 WC Robotics SC Robotics GA 471CQ UT WOS:000170910300002 ER PT J AU Bousman, WG AF Bousman, WG TI Evaluation of airfoil dynamic stall characteristics for maneuverability SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 26th European Rotorcraft Forum CY SEP 26-29, 2000 CL THE HAGUE, NETHERLANDS AB The loading on an airfoil during dynamic stall is examined in terms of the augmented lift that occurs and the associated penalties in pitching moment and drag. It is shown that once stall occurs, and a leading-edge vortex is shed from the airfoil, there is a unique relationship between the augmented lift, the negative pitching moment, and the increase in drag. This relationship shows limited sensitivity to a number of parameters that govern dynamic stall, such as steady and alternating pitch angles and reduced frequency. Second-order polynomials are used to characterize this dynamic stall behavior. It is shown that the dynamic stall performance of most single-element airfoils is similar, and it appears that little can be done to significantly improve rotorcraft maneuverability except to provide good static C-lmax characteristics and the chord or blade number that is required to provide the necessary rotor thrust. The loading on a helicopter blade during a severe maneuver is examined and it is shown that the blade's dynamic stall behavior is similar to that observed in two-dimensional wind tunnel testing. The interaction of the dynamic stall vortex and three-dimensional flow near the blade tip is studied for both a rotor blade in flight and an oscillating wing in a wind tunnel. This comparison shows that there are significant differences in the interaction of the dynamic stall vortex and the tip flow for the two cases. The polynomials used to characterize dynamic stall behavior may be employed as a metric and this is demonstrated by evaluating sample theoretical predictions of semi-empirical stall models and CFD computations. This approach is also shown to be useful in evaluating test data obtained from dynamic stall tests of multi-element airfoils. C1 NASA, Ames Res Ctr, Aviat & Missile Command, AMRDEC,Aeroflightdynam Directorate,Rotocraft Div, Moffett Field, CA 94035 USA. RP Bousman, WG (reprint author), NASA, Ames Res Ctr, Aviat & Missile Command, AMRDEC,Aeroflightdynam Directorate,Rotocraft Div, Moffett Field, CA 94035 USA. NR 29 TC 5 Z9 5 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 2001 VL 46 IS 4 BP 239 EP 250 PG 12 WC Engineering, Aerospace SC Engineering GA 488VA UT WOS:000171955600001 ER PT J AU Stern, DP AF Stern, DP TI Systematic identification of preferred orbits for magnetospheric missions: 1. Single satellites SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article ID MAGNETOPAUSE AB This is a systematic attempt to identify and assess near-equatorial, high-eccentricity Orbits best suited for studying the Earth's magnetosphere, in particular its most dynamic part, the plasma sheet of the magnetotail. The study was motivated by the design needs of a multi-spacecraft "constellation" mission, stressing low cost, minimal active control and economic launch strategies, and both quantitative and qualitative aspects were investigated. On one hand, by collecting hourly samples throughout the year, accurate estimates were obtained of the coverage of different regions, and of the frequency and duration of long eclipses. On the other hand, an intuitive understanding was developed of the factors which determine the merits of the mission, including long-range factors due to perturbations by the Moon, Sun and the Earth's equatorial bulge. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Stern, DP (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. NR 16 TC 3 Z9 3 U1 0 U2 1 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 USA SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 2001 VL 49 IS 4 BP 559 EP 583 PG 25 WC Engineering, Aerospace SC Engineering GA 601LV UT WOS:000178448400003 ER PT J AU Begault, DR Wenzel, EM AF Begault, DR Wenzel, EM TI Direct comparison of the impact of head tracking, reverberation, and individualized head-related transfer functions on the spatial perception of a virtual speech source SO JOURNAL OF THE AUDIO ENGINEERING SOCIETY LA English DT Article; Proceedings Paper CT 108th Convention of the Audio-Engineering-Society CY FEB 19-22, 2000 CL PARIS, FRANCE SP Audio Engn Soc ID LOCALIZATION; SIMULATION AB A study of sound localization performance was conducted using headphone-delivered virtual speech stimuli, rendered via HRTF-based acoustic auralization software and hardware, and blocked-meatus HRTF measurements. The independent variables were chosen to evaluate commonly held assumptions in the literature regarding improved localization: inclusion of head tracking, individualized HRTFs, and early and diffuse reflections. Significant effects were found-for azimuth and elevation error, reversal rates, and externalization. C1 NASA, Ames Res Ctr, Human Factors Res & Technol Div, Moffett Field, CA 94035 USA. Raytheon Tech Serv Co, Moffett Field, CA 94035 USA. RP Begault, DR (reprint author), NASA, Ames Res Ctr, Human Factors Res & Technol Div, Moffett Field, CA 94035 USA. NR 41 TC 74 Z9 80 U1 0 U2 8 PU AUDIO ENGINEERING SOC PI NEW YORK PA 60 E 42ND ST, NEW YORK, NY 10165-2520 USA SN 0004-7554 J9 J AUDIO ENG SOC JI J. Audio Eng. Soc. PD OCT PY 2001 VL 49 IS 10 BP 904 EP 916 PG 13 WC Acoustics; Engineering, Multidisciplinary SC Acoustics; Engineering GA 502NE UT WOS:000172749000002 PM 11885605 ER PT J AU Whitacre, JF West, WC Brandon, E Ratnakumar, BV AF Whitacre, JF West, WC Brandon, E Ratnakumar, BV TI Crystallographically oriented thin-film nanocrystalline cathode layers prepared without exceeding 300 degrees C SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID LITHIUM COBALT OXIDE; BATTERIES; LICOO2 AB The highest capacity rf sputtered cathode layers created for use in thin-film solid-state batteries have been found to require an annealing step with temperatures in excess of 700 degreesC. Since this high-temperature process step is incompatible with silicon device technology and flexible polymer substrates, the development of a low-process temperature (less than or equal to 300 degreesC) cathode laver has been undertaken. Thin-film cathode layers consisting of LiCoO2 were deposited using planar magnetron rf sputtering and subsequently incorporated into thin-film solid-state cells comprised of a LiPON electrolyte and lithium metal anode. Film composition was examined using Rutherford backscattering spectrometry and inductively coupled plasma mass spectroscopy, while phase content and crystal structure were studied through X-ray diffraction experiments conducted at the Stanford Synchrotron Radiation Laboratory. Microstructure and morphology were examined using transmission and scanning electron microscopy. It was found that LiCoO2 could be deposited at room temperature in a nanocrystalline state with a defined (104) out of plane texture and a high degree of lattice distortion. By heating these layers to 300 degreesC, the average grain size was increased while lattice distortion was minimized. Electrochemical cycling data revealed that the low temperature annealing step increases cell capacity to near theoretical values while significantly improving both the rate capability and discharge voltage. Impedance analysis on test cells showed that the electronic resistance of the cells is decreased after heating to 300 degreesC. (C) 2001 The Electrochemical Society. C1 CALTECH, Jet Prop Lab, Ctr Integrated Space Microsyst, Electrochem Technol Grp, Pasadena, CA 91109 USA. RP Whitacre, JF (reprint author), CALTECH, Jet Prop Lab, Ctr Integrated Space Microsyst, Electrochem Technol Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 20 TC 33 Z9 36 U1 4 U2 31 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 OCT PY 2001 VL 148 IS 10 BP A1078 EP A1084 DI 10.1149/1.1400119 PG 7 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA 481CD UT WOS:000171501600005 ER PT J AU Sohn, BJ Chung, HS Kim, DH Perkey, D Robertson, FR Smith, EA AF Sohn, BJ Chung, HS Kim, DH Perkey, D Robertson, FR Smith, EA TI Use of satellite-derived water vapor data to investigate northwestward expansion of North Pacific subtropical high during 1995 summer SO JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN LA English DT Article ID OUTGOING LONGWAVE RADIATION; 40-50 DAY OSCILLATION; WESTERN PACIFIC; INTRASEASONAL OSCILLATION; HEMISPHERE SUMMER; CONVECTIVE ACTIVITY; GLOBAL OCEANS; CLOUD AMOUNT; EAST-ASIA; MONSOON AB The spatial and temporal evolution of the moisture field over the subtropical northwest Pacific during the summer of 1995 is investigated using daily total precipitable water from combined SSM/I-TOVS data, and pentad upper tropospheric humidity (UTH) data, in conjunction with NCEP reanalysis data. From analysis of the combined water vapor field, the westward movement of a dry airmass is observed along the 20-30 degreesN latitude zone from near the dateline to the south of Japan throughout the summer of 1995. Extended EOF analysis of total precipitable, water reveals that the westward moving pattern takes place in association with an expanding North Pacific subtropical high, maintaining an oscillatory component exhibiting a period of some 15-25 days. A concomitant dipole-like oscillating anomalous circulation with approximately a 20-day period between the South China Sea and south of Japan appears to influence the westward expansion of the subtropical high or vice versa. The analysis also suggests that the fluctuations of the North Pacific high are in response to a local Hadley-type circulation. which is induced by westward-moving anomalous convection episodes along 10-20 degreesN. C1 Seoul Natl Univ, Sch Earth & Environm Sci, Seoul 151747, South Korea. Korean Meteorol Adm, Meteorol Res Inst, Seoul, South Korea. Seoul Natl Univ, Sch Earth & Environm Sci, Seoul, South Korea. NASA UAH Global Hydrol & Climate Ctr, Huntsville, AL USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sohn, BJ (reprint author), Seoul Natl Univ, Sch Earth & Environm Sci, Seoul 151747, South Korea. EM sohn@snu.ac.kr NR 44 TC 4 Z9 4 U1 1 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 OCT PY 2001 VL 79 IS 5 BP 1059 EP 1075 DI 10.2151/jmsj.79.1059 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 500KA UT WOS:000172625200006 ER PT J AU Chao, DF Zhang, NL AF Chao, DF Zhang, NL TI Effects of evaporation and thermocapillary convection on volatile liquid droplets SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID SOLID-SURFACES; CONTACT ANGLES; MINUTE DROPS; INSTABILITY AB Results of an experimental investigation of evaporating sessille drops on a glass-slide surface for three volatile liquids show that both evaporation and thermocapillary convection in the sessile drop strongly affect the drop spreading and contact angle. The evolution of contact diameter or the drops can be divided into four stages: 1) initial spreading, 2) spreading-evaporation balance, 3) evaporation-dominating contraction, and 4) final rapid contraction. Molecular-kinetic spreading always occurs in the early first stage and is rapidly restrained and then taken over by the effects of evaporation. Thermocapillary convection, induced by the evaporation, promotes the competition of evaporation over the spreading and shortens the spreading-evaporation balance stage to become undetectable. Evaporation may increase or decrease the contact angle of the evaporating sessile drops, depending on the evaporation rate. C1 NASA, John H Glenn Res Ctr, Micrograv Sci Div, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Dept Workforce Enhancement, Cleveland, OH 44142 USA. RP Chao, DF (reprint author), NASA, John H Glenn Res Ctr, Micrograv Sci Div, Mail Stop 500-102, Cleveland, OH 44135 USA. NR 22 TC 7 Z9 7 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 OCT-DEC PY 2001 VL 15 IS 4 BP 416 EP 420 DI 10.2514/2.6644 PG 5 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 487GG UT WOS:000171864900006 ER PT J AU Krantz, TL Alanou, MP Evans, HP Snidle, RW AF Krantz, TL Alanou, MP Evans, HP Snidle, RW TI Surface fatigue lives of case-carburized gears with an improved surface finish SO JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME LA English DT Article ID CARBON STEEL GEARS; DURABILITY AB Previous research provides qualitative evidence that an improved surface finish can increase the surface fatigue lives of gears. To quantify the influence of surface roughness on life, a set of AISI 9310 steel gears was provided with a near-mirror finish by superfinishing. The effects of the superfinishing on the quality of the gear tooth surfaces were determined using data from metrology profilometry, and interferometric microscope inspections. The superfinishing reduced;he roughness average by about a factor of 5. The superfinished gears were subjected to surface fatigue testing at 1.71 GPa (248-ksi) Hertz contact stress, and the data were compared with the NASA Glenn gear fatigue data base, The lives of gears with superfinished teeth were about four times greater compared with the lives of gears with ground teeth but with otherwise similar quality. C1 USA, Res Lab, Glenn Res Ctr, Cleveland, OH 44135 USA. Cardiff Univ, Cardiff CF24 3TA, S Glam, Wales. RP Krantz, TL (reprint author), USA, Res Lab, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 25 TC 12 Z9 12 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0742-4787 J9 J TRIBOL-T ASME JI J. Tribol.-Trans. ASME PD OCT PY 2001 VL 123 IS 4 BP 709 EP 716 DI 10.1115/1.1387036 PG 8 WC Engineering, Mechanical SC Engineering GA 482KW UT WOS:000171576200007 ER PT J AU Navarra, KR Rabe, DC Fonov, SD Goss, LP Hah, C AF Navarra, KR Rabe, DC Fonov, SD Goss, LP Hah, C TI The application of pressure- and temperature-sensitive paints to an advanced compressor SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 46th International Congress and Exhibition on Gas Turbines and Aeroengines CY JUN 04-07, 2001 CL NEW ORLEANS, LOUISIANA AB An innovative pressure-measurement technique that employs the tools of molecular spectroscopy has been widely investigated by the aerospace community. Measurements are made via oxygen-sensitive molecules attached to the surface of interest as a coating, or paint. The pressure-sensitive-paint (PSP) technique is now commonly used in stationary wind-tunnel tests; this paper presents the use of this technique in advanced turbomachinery applications. New pressure- and temperature-sensitive paints (P/TSPs) have been developed for application to a state-of-the-art transonic compressor where pressures up to 1.4 atm and surface temperatures to 90 degreesC are expected for the suction surface of the first-stage rotor PSP and TSP data images have been acquired from the suction surface of the first-stage rotor at 85 percent of the corrected design speed for the compressor near-stall condition. A comparison of experimental results with CFD calculations is discussed. C1 USAF, Res Lab, Wright Patterson AFB, OH 45433 USA. Innovat Sci Solut Inc, Dayton, OH 45440 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Navarra, KR (reprint author), USAF, Res Lab, Wright Patterson AFB, OH 45433 USA. NR 21 TC 5 Z9 5 U1 1 U2 6 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 OCT PY 2001 VL 123 IS 4 BP 823 EP 829 DI 10.1115/1.1400116 PG 7 WC Engineering, Mechanical SC Engineering GA 492MD UT WOS:000172171400018 ER PT J AU Stelzner, AD Kammer, DC Milenkovic, P AF Stelzner, AD Kammer, DC Milenkovic, P TI A time domain method for estimating forces applied to an unrestrained structure SO JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME LA English DT Article AB A new method for the estimation of forces applied to a structure is presented. This time domain technique uses the structures response time history and returns tin estimate of the applied force time history. This technique allows near-real-time estimation of input forces for non-collocated sensor/actuator pairs for multi-input/multi-output systems. Two examples are presented. The first is a single-input/single-output one-dimensional spring/ mass chain in which a remote accelerometer is used to estimate an input force at one end. In the second example, the technique is used to estimate six docking fim-es and moments between the Space Shuttle and the Russian MIR Space Station during el numerical simulation of a docking event. C1 CALTECH, Jet Prop Lab, Mech Engn Sect, Pasadena, CA 91109 USA. RP Stelzner, AD (reprint author), CALTECH, Jet Prop Lab, Mech Engn Sect, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 10 Z9 11 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 1048-9002 J9 J VIB ACOUST JI J. Vib. Acoust.-Trans. ASME PD OCT PY 2001 VL 123 IS 4 BP 524 EP 532 DI 10.1115/1.1401055 PG 9 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 489YB UT WOS:000172019600014 ER PT J AU Kaminskii, AA Ueda, K Eichler, HJ Kuwano, Y Kouta, H Bagayev, SN Chyba, TH Barnes, JC Murai, T Lu, J AF Kaminskii, AA Ueda, K Eichler, HJ Kuwano, Y Kouta, H Bagayev, SN Chyba, TH Barnes, JC Murai, T Lu, J TI Tetragonal vanadates YVO4 and GdVO4 - New efficient chi((3))-active crystals for Raman laser converters SO LASER PHYSICS LA English DT Article; Proceedings Paper CT 3rd International Symposium on Modern Problems of Laser Physics (MPLP-2000) CY JUL 02-07, 2000 CL NOVOSIBIRSK, RUSSIA SP Russian Federat, Minist Sci & Technol, Russian Fdn Basic Res, Sci Council Opt & Laser Phys RAS AB High-order Stokes and anti-Stokes picosecond generation in tetragonal YVO4 and GdVO4 host crystals for lasing trivalent lanthanides (Ln(3+)) has been observed for the first time. All measured stimulated Raman scattering (SRS) wavelengths in the visible and near infrared (NIR) are identified and attributed to the SRS-active vibration modes of these vanadates. C1 Russian Acad Sci, Inst Crystallog, Moscow 117333, Russia. Univ Electrocommun, Inst Laser Sci, Tokyo 1828585, Japan. Tech Univ Berlin, Inst Opt, D-10623 Berlin, Germany. NEC Corp Ltd, Mat Dept Ctr, Kawasaki, Kanagawa 213, Japan. Russian Acad Sci, Inst Laser Phys, Novosibirsk 630090, Russia. Hampton Univ, Res Ctr Opt Phy, Hampton, VA 23688 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Kaminskii, AA (reprint author), Russian Acad Sci, Inst Crystallog, Leninsky Pr 59, Moscow 117333, Russia. RI Bagayev, Sergei/R-7942-2016 OI Bagayev, Sergei/0000-0003-4470-2779 NR 16 TC 27 Z9 27 U1 1 U2 2 PU INTERPERIODICA PI BIRMINGHAM PA PO BOX 1831, BIRMINGHAM, AL 35201-1831 USA SN 1054-660X J9 LASER PHYS JI Laser Phys. PD OCT PY 2001 VL 11 IS 10 BP 1124 EP 1133 PG 10 WC Optics; Physics, Applied SC Optics; Physics GA 488VN UT WOS:000171957100015 ER PT J AU Jansen, MJ Jones, WR Wheeler, DR Keller, DJ AF Jansen, MJ Jones, WR Wheeler, DR Keller, DJ TI Evaluation of non-ozone-depleting-chemical cleaning methods for space mechanisms using a vacuum spiral orbit rolling contact tribometer SO LUBRICATION ENGINEERING LA English DT Article DE space vehicles; vacuum bearings; chemical cleaners ID PERFLUOROPOLYALKYLETHER; PERFLUOROPOLYETHERS; TEMPERATURE; SURFACES AB Because CFC 113, an ozone depleting chemical (ODC), can no longer be produced, alternative bearing cleaning methods must be studied. The objective of this work was to study the effect of the new cleaning methods on lubricant lifetime using a vacuum bearing simulator, the Spiral Orbit Tribometer (SOT). In addition to baselines tests using CFC 113, four alternative cleaning methods were studied. They were ultra-violet (UV) ozone, aqueous levigated alumina slurry (ALAS), super critical fluid (SCF) CO2, and aqueous Brulin (TM) 815GD. Test conditions were the following: a vacuum of at least 1.3 x 10(-6) Pa, 440C steel components, a rotational speed of 10 RPM, a lubricant charge of between 60-75 micrograms, a perfluoropolyalkylether (PFPAE) lubricant (Z-25), and a load of 200N (a mean Hertzian stress of 1.5 GPa). Normalized lubricant lifetime was determined by dividing the total number of ball orbits by the amount of lubricant. The failure condition was a friction coefficient of 0.38. Post-test XPS analysis showed a greater amount of carbon on the surfaces cleaned with Brulin (TM) 815GD and SCF CO2 than with the other techniques, which may represent residual hydrocarbons. Statistical analysis of the resultant data was conducted and it was determined that the data sets were most directly comparable when subjected to a natural log transformation. The natural log life (NL-Life) data for each cleaning method were reasonably normally (statistically) distributed and yielded standard deviations that were not significantly different among the five cleaning methods investigated. This made comparison of their NL-Life means very straightforward using a Bonferroni multiple comparison of means procedure. This procedure showed that the ALAS. UV-ozone and CFC 113 methods were not statistically significantly different from one another with respect to mean NL-Life. It also found that the SCF CO2 method yielded a significantly higher mean NL-Life than the mean NL-lives of the three previously mentioned methods. It also determined that the aqueous Brulin (TM) 815GD method yielded a mean NL-Life that was statistically significantly higher than the mean NL-lives of each of the other four methods. Baseline tests using CFC 113 cleaned parts yielded a mean NL-Life 3.6 orbits/mug. ALAS and UV-ozone yielded similar mean NL-Life of 3.3 orbits/mug and 3.3 orbits/mug respectively. Finally, SCF CO2 gave a mean NL-Life of 4.1 orbits/mug, while aqueous Brulin (TM) 815GD data yielded the longest mean NL-Life (4.7 orbits/mug). C1 AYT Corp, Brookpark, OH USA. NASA, John H Glenn Res Ctr, Cleveland, OH USA. RealWorld Qual Syst, Cleveland, OH USA. RP Jansen, MJ (reprint author), AYT Corp, Brookpark, OH USA. NR 23 TC 2 Z9 2 U1 1 U2 3 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD OCT PY 2001 VL 57 IS 10 BP 22 EP 26 PG 5 WC Engineering, Mechanical SC Engineering GA 478PX UT WOS:000171355500003 ER PT J AU Waring, GT Hamazaki, T Sheehan, D Wood, G Baker, S AF Waring, GT Hamazaki, T Sheehan, D Wood, G Baker, S TI Characterization of beaked whale (Ziphiidae) and sperm whale (Physeter macrocephalus) summer habitat in shelf-edge and deeper waters off the northeast US SO MARINE MAMMAL SCIENCE LA English DT Article DE sperm whale; Physeter macrocephalus; beaked whales (Mesoplodon spp. and Ziphius cavirostris); habitat use; satellite imagery; GIS; northeast US shelf ID GULF-OF-MEXICO; WARM-CORE RING; SCOTIAN-SHELF; MESOPLODON-BIDENS; SUBMARINE-CANYON; CETACEANS; FRONTS; DISTRIBUTIONS; SLOPE; VARIABILITY AB Sperm whales (Physeter macrocephalus) and beaked whales (Mesoplodon spp. and Ziphius cavirostris) are deep-diving cetaceans that frequent shelf-edge and Gulf Stream waters off the northeast U.S. coast. Sighting data collected during seven summer (1990, 1991, 1993, and 1995-1998) shipboard surveys were analyzed using a geographic information system to determine habitat use based on bathymetric and oceanographic features. Although sighting rates were lower for beaked whales, both taxa occupied similar habitats. Beaked whales were concentrated at the colder shelf edge, whereas sperm whales were associated with warmer off-shelf water. Mean sighting rates for both taxa were higher in canyon features, but only beaked whale sighting rates were significantly different between canyon and non-canyon habitat (Wilcoxon signed rank test P = 0.007). Within the shared habitat, the two taxa were separated at fine-scale based on oceanographic features. C1 NOAA, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, Woods Hole, MA 02543 USA. NOAA, Natl Marine Fisheries Serv, NE Reg Off, Gloucester, MA 01930 USA. NOAA, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, Narragansett, RI 02882 USA. Univ Rhode Isl, Grad Sch Oceanog, Narragansett, RI 02882 USA. RP Waring, GT (reprint author), New Mexico State Univ, Dept Fisheries & Wildlife Sci, Las Cruces, NM 88003 USA. NR 53 TC 42 Z9 52 U1 4 U2 14 PU SOC MARINE MAMMALOGY PI LAWRENCE PA 1041 NEW HAMPSHIRE ST, LAWRENCE, KS 66044 USA SN 0824-0469 J9 MAR MAMMAL SCI JI Mar. Mamm. Sci. PD OCT PY 2001 VL 17 IS 4 BP 703 EP 717 DI 10.1111/j.1748-7692.2001.tb01294.x PG 15 WC Marine & Freshwater Biology; Zoology SC Marine & Freshwater Biology; Zoology GA 486GC UT WOS:000171809200003 ER PT J AU Hepp, AF AF Hepp, AF TI Materials and technologies for space exploration - Editorial SO MATERIALS & DESIGN LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0261-3069 J9 MATER DESIGN JI Mater. Des. PD OCT PY 2001 VL 22 IS 7 BP 527 EP 527 DI 10.1016/S0261-3069(01)00013-9 PG 1 WC Materials Science, Multidisciplinary SC Materials Science GA 461CP UT WOS:000170347600001 ER PT J AU Cheng, Z Chaikin, PM Russel, WB Meyer, WV Zhu, J Rogers, RB Ottewill, RH AF Cheng, Z Chaikin, PM Russel, WB Meyer, WV Zhu, J Rogers, RB Ottewill, RH TI Phase diagram of hard spheres SO MATERIALS & DESIGN LA English DT Article DE hard sphere; colloids; crystallization; glass transition; dendrites; gravity; microgravity ID CRYSTALS; GROWTH AB We report results from the Space Shuttle experiments Colloidal Disorder-Order Transition (CDOT) 1 and 2. The phase diagram of colloidal hard spheres is measured in microgravity avoiding the effects of sedimentation and convection that arise with normal gravity. For samples in the crystal-liquid coexistence region we observed a dendritic growth. For high concentration samples near random close packing we observed crystallization and no evidence for a glassy phase. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Princeton Univ, Dept Phys, Princeton, NJ 08544 USA. Princeton Univ, Dept Chem Engn, Princeton, NJ 08544 USA. NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. Univ Bristol, Sch Chem, Bristol BS8 1TS, Avon, England. NR 19 TC 25 Z9 25 U1 2 U2 19 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0261-3069 J9 MATER DESIGN JI Mater. Des. PD OCT PY 2001 VL 22 IS 7 BP 529 EP 534 DI 10.1016/S0261-3069(01)00015-2 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA 461CP UT WOS:000170347600002 ER PT J AU Wilson, JW Cucinotta, FA Miller, J Shinn, JL Thibeault, SA Singleterry, RC Simonsen, LC Kim, MH AF Wilson, JW Cucinotta, FA Miller, J Shinn, JL Thibeault, SA Singleterry, RC Simonsen, LC Kim, MH TI Approach and issues relating to shield material design to protect astronauts from space radiation SO MATERIALS & DESIGN LA English DT Article DE galactic cosmic rays; shielding; astronauts ID HEAVY-ION FRAGMENTATION; GALACTIC COSMIC-RAYS; CROSS-SECTIONS; MODEL; FE-56; PAST AB One major obstacle to human space exploration is the possible limitations imposed by the adverse effects of long-term exposure to the space environment. Even before human spaceflight began, the potentially brief exposure of astronauts to the very intense random solar energetic particle (SEP) events was of great concern. A new challenge appears in deep space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays (GCR) since the missions are of long duration and the accumulated exposures can be high. Since aluminum (traditionally used in spacecraft to avoid potential radiation risks) leads to prohibitively expensive mission launch costs, alternative materials need to be explored, An overview of the materials related issues and their impact on human space exploration will be given. Published by Elsevier Science Ltd. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. DOE, Lawrence Berkeley Natl Lab, Berkeley, CA 94720 USA. NR 42 TC 16 Z9 21 U1 2 U2 14 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0261-3069 J9 MATER DESIGN JI Mater. Des. PD OCT PY 2001 VL 22 IS 7 BP 541 EP 554 DI 10.1016/S0261-3069(01)00014-0 PG 14 WC Materials Science, Multidisciplinary SC Materials Science GA 461CP UT WOS:000170347600004 PM 12194183 ER PT J AU Ferguson, DC Wilt, DM Hepp, AF Kolecki, JC Siebert, MW Jenkins, PP Scheiman, DA Fatemi, NS Hoffman, RW AF Ferguson, DC Wilt, DM Hepp, AF Kolecki, JC Siebert, MW Jenkins, PP Scheiman, DA Fatemi, NS Hoffman, RW TI The Mars Pathfinder wheel abrasion experiment SO MATERIALS & DESIGN LA English DT Article DE coupon testing; selection for material properties; abrasion ID SOJOURNER; ROVER AB On board the Mars Pathfinder spacecraft, launched in December of 1996. was a small roving vehicle named Sojourner. On Sojourner was an experiment to determine the abrasive characteristics of the Martian surface, called the Wheel Abrasion Experiment (WAE). The experiment worked as follows: one of the wheels of the rover had a strip of black anodized aluminum bonded to the tread upon which was deposited five patches or samples of three different metals ranging in thickness from 200 Angstrom to 1000 Angstrom. A series of candidate metals (Ag, Al, Au, Cu, Ni, Pt and W) were tested for suitability for the WAE. Optical, corrosion, abrasion and adhesion criteria were used to select aluminum, platinum and nickel. The photovoltaic sensor or photodetector developed for the WAE is described. As the wheel was spun in the Martian soil, thin patches of metal were abraded away, exposing the black surface. Abrasion of those samples was detected by the change in specular reflectance of sunlight as measured by a photodetector mounted above the wheel. The degree of abrasion occurring on the samples is discussed, along with comparisons to the abrasion seen in Earth-based laboratory experiments using Martian soil. Conclusions are reached about the hardness, grain size and angularity of the Martian simulant soil particles and about precautions to be undertaken to avoid abrasion on moving parts exposed to Martian dust. Published by Elsevier Science Ltd. C1 NASA, John H Glenn Res Ctr, Photovolta & Space Environm Branch, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Brookpark, OH 44142 USA. Essential Res Inc, Cleveland, OH 44135 USA. NR 10 TC 1 Z9 1 U1 0 U2 5 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0261-3069 J9 MATER DESIGN JI Mater. Des. PD OCT PY 2001 VL 22 IS 7 BP 555 EP 564 DI 10.1016/S0261-3069(01)00016-4 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA 461CP UT WOS:000170347600005 ER PT J AU Southward, RE Thompson, DW AF Southward, RE Thompson, DW TI Reflective and conductive silvered polyimide films for space applications prepared via a novel single-stage self-metallization technique SO MATERIALS & DESIGN LA English DT Article ID REDUCTION; ADHESION; OPTICS AB Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione into a dimethylacetamide solution of poly(amic acid), formed from 3,3 ' ,4,4 ' -benzophenone tetracarboxylic acid dianhydride and 4,4 ' -oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction yielding a reflective and conductive silvered surface with properties approaching those of the native metal. Ligand/anion effects on the metallization process resulted when using additional silver(I) compounds including: silver(I) nitrate; silver(I) tetrafluoroborate; (trifluoroacetato)silver(I); (hexafluoroacetylacetonato)silver(I); (trifluoroacetylacetonato)silver(I); and 1-(2-thienyl)-3,3,3(trifluoroacetonato)silver(I). Comparisons among these six silver(I) compounds as precursors for the surface metallization of BTDA/4,4 ' -ODA are discussed with regard to reflectivity, conductivity and surface morphology. The metallized films usually retain the essential mechanical properties and thermal properties of a parent film. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, tapping mode atomic force microscopy and X-ray photoelectron spectroscopy. Also, electrical conductivity, reflectivity, differential scanning calorimetric, thermal gravimetric and mechanical measurements were made on the metallized films. Published by Elsevier Science Ltd. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Coll William & Mary, Williamsburg, VA 23187 USA. NR 24 TC 26 Z9 29 U1 0 U2 10 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0261-3069 J9 MATER DESIGN JI Mater. Des. PD OCT PY 2001 VL 22 IS 7 BP 565 EP 576 DI 10.1016/S0261-3069(01)00017-6 PG 12 WC Materials Science, Multidisciplinary SC Materials Science GA 461CP UT WOS:000170347600006 ER PT J AU Henderson, DO Mu, R Ueda, A Wu, MH Gordon, EM Tung, YS Huang, M Keay, J Feldman, LC Hollingsworth, JA Buhro, WE Harris, JD Hepp, AF Raffaelle, RP AF Henderson, DO Mu, R Ueda, A Wu, MH Gordon, EM Tung, YS Huang, M Keay, J Feldman, LC Hollingsworth, JA Buhro, WE Harris, JD Hepp, AF Raffaelle, RP TI Optical and structural characterization of copper indium disulfide thin films SO MATERIALS & DESIGN LA English DT Article DE semi-conductors; vapour deposition; optical ID CUINSE2 AB Thin films of copper indium disulfide (CuInS2) were synthesized by spray chemical vapor deposition. Rutherford backscattering measurements were used to determine the composition and thickness of the films. The elemental ratios were found to be within 2% of stoichiometrically correct CuInS2 The thickness of the films was found to be approximately 1.0 mum. An optical band-gap of approximately 1.44 eV for this material was determined by optical transmission spectroscopy. Reflectance spectroscopy identified phonon bands centered at 225, 291 and 317 cm(-1). (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Fisk Univ, Dept Phys, Chem Phys Lab, Nashville, TN 37208 USA. Charles Evans & Associates, Redwood City, CA 94063 USA. Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37208 USA. Washington Univ, Dept Chem, St Louis, MO 63130 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RI Buhro, William/A-7682-2009 NR 12 TC 19 Z9 20 U1 1 U2 10 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0261-3069 J9 MATER DESIGN JI Mater. Des. PD OCT PY 2001 VL 22 IS 7 BP 585 EP 589 DI 10.1016/S0261-3069(01)00019-X PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA 461CP UT WOS:000170347600008 ER PT J AU Chubb, DL Pal, AMT Patton, MO Jenkins, PP AF Chubb, DL Pal, AMT Patton, MO Jenkins, PP TI Rare earth doped yttrium aluminum garnet (YAG) selective emitters SO MATERIALS & DESIGN LA English DT Article DE yttrium aluminum garnet; spectral emittance model; temperature differences AB As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For the holminum aluminum garnet film the efficiency is 0.35 at 1446 K, but only 0.27 at 1270 K. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Essential Res Inc, Cleveland, OH 44122 USA. NR 19 TC 3 Z9 3 U1 1 U2 7 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0261-3069 J9 MATER DESIGN JI Mater. Des. PD OCT PY 2001 VL 22 IS 7 BP 591 EP 599 DI 10.1016/S0261-3069(01)00021-8 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA 461CP UT WOS:000170347600009 ER PT J AU Harris, JD Eckles, WE Hepp, AF Duraj, SA Fanwick, PE Richardson, J Gordon, EM AF Harris, JD Eckles, WE Hepp, AF Duraj, SA Fanwick, PE Richardson, J Gordon, EM TI Room temperature dissolution of metal powders by thiourea: a novel route to transition metal isothiocyanate complexes SO MATERIALS & DESIGN LA English DT Article DE oxidation; atomic structure; chemical reactions ID CRYSTAL-STRUCTURES; 4-METHYLPYRIDINE; HOST; THIOCYANATE; BATTERIES; DEVICES; CUINSE2; FILMS; GUEST; GAAS AB A new synthetic route to isothiocyanate containing materials is presented. Five isothiocyanate 4-methylpyridine (gamma -picoline) compounds were prepared by refluxing metal powders (Fe, Co, Ni and Cu) with thiourea in y-picoline. The isothiocyanate ligand is generated in situ by the isomerization of thiourea to NH4+SCN- at reflux temperatures. The complexes [Fe(NCS)(2)(pic)(4)] (.) pic (1), [Co(NCS)(2)(pic)(4)] (.) pic (2), [Ni(NCS)(2)(pic)(4)] (3), [Cu(NCS)(2)(pic)(4)] (.) 2/3pic (.) 1/3H(2)O (4), [Cu(NCS)(pic)(2)](x) (5) (where pic = gamma -picoline) were characterized by X-ray crystallography; the structural data for compounds 1-3 and 5 are presented. Published by Elsevier Science Ltd. C1 Cleveland State Univ, Dept Chem, Cleveland, OH 44115 USA. NASA, Glenn Res Ctr, Thin Film Technol Grp, Cleveland, OH 44135 USA. Purdue Univ, Dept Chem, W Lafayette, IN 47907 USA. Univ Louisville, Dept Chem, Louisville, KY 40292 USA. Wilberforce Univ, Div Nat Sci, Wilberforce, OH 45384 USA. NR 36 TC 7 Z9 7 U1 1 U2 3 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0261-3069 J9 MATER DESIGN JI Mater. Des. PD OCT PY 2001 VL 22 IS 7 BP 625 EP 634 DI 10.1016/S0261-3069(01)00025-5 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA 461CP UT WOS:000170347600013 ER PT J AU Snyder, GJ Caillat, T Fleurial, JP AF Snyder, GJ Caillat, T Fleurial, JP TI Thermoelectric properties of chalcogenides with the spinel structure SO MATERIALS RESEARCH INNOVATIONS LA English DT Article DE thermoelectric; thermopower; metal-insulator transition; polaron semiconductor; Ferromagnet ID ELECTRICAL-PROPERTIES; MAGNETIC-PROPERTIES; CD1-XCUXCR2SE4 AB Many compounds with the spinel structure type have been analyzed for their thermoelectric properties. Published data was used to augment experimental results presented here and to select promising thermoelectric spinels. Compounds studied here include Cu0.5Al0.5Cr2Se4, Co0.5Co0.5Cr2Se4 Cu0.5In0.5Cr2Se4, and CuIr2Se4. Many exhibit low lattice thermal conductivity of about 20 mW/cmK, independent of temperature. Two representative series of compounds GaxCu1-xCr2Se4 0 less than or equal tox less than or equal to0.6 and CuxZn1-x Cr2Se4 0 less than or equal tox less than or equal to 0.3 have been studied to examine the doping region of interest for both high and low temperature thermoelectric applications. Ferromagnetic, small polaron semiconductors are found in both series of compounds. G(a)xCu(1-x)Cr(2)Se(4) shows a metal insulator transition, from a p-type metal at x=0 to a p-type and then n-type semiconductor as x crosses 1/2. The maximum figure of merit ZT is of order 0.1. CuxZn1-xCr2Se4 transitions from a p-type semiconductor to a p-type metal as x increases. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Snyder, GJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 277-207, Pasadena, CA 91109 USA. RI Snyder, G. Jeffrey/E-4453-2011; Snyder, G/I-2263-2015 OI Snyder, G. Jeffrey/0000-0003-1414-8682; NR 25 TC 19 Z9 19 U1 1 U2 20 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1432-8917 J9 MATER RES INNOV JI Mater. Res. Innov. PD OCT PY 2001 VL 5 IS 2 BP 67 EP 73 DI 10.1007/s100190100133 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA 487EB UT WOS:000171859700004 ER PT J AU Gounelle, M Zolensky, ME AF Gounelle, M Zolensky, ME TI A terrestrial origin for sulfate veins in CI1 chondrites SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID CARBONACEOUS CHONDRITES; AQUEOUS ACTIVITY; ISOTOPIC COMPOSITION; PARENT BODY; METEORITES; CARBONATES; COMPONENTS; MINERALOGY; POROSITY; MATRIX AB White sulfate veins are a very well-known petrological feature of the chemically primitive CI1 carbonaceous chondrites. Sulfate veins were first described in the Orgueil meteorite in 1961, almost one century after its fall. However, we have observed such veins to form easily during typical sample storage. We suggest that all CI1 sulfate veins formed during the terrestrial residence of these heavily brecciated, porous stones. Reacting with atmospheric water, sulfates originally present in the meteorites dissolved and remobilized, and/or sulfides oxidised, filling the many open spaces offered to them by the very porous rock. Sulfate veins in CI1 chondrites can no longer be used as evidence of a late-stage oxidation event in the CI1 parent body, or of centimeter-scale fluid transport on the parent asteroid. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Ctr Spectrometrie Nucl & Spectrometrie Masse, F-91405 Orsay, France. RP Gounelle, M (reprint author), Nat Hist Museum, Dept Mineral, London SW7 5BD, England. NR 59 TC 76 Z9 76 U1 0 U2 5 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD OCT PY 2001 VL 36 IS 10 BP 1321 EP 1329 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 492NC UT WOS:000172173600007 ER PT J AU Cayon, L Sanz, JL Martinez-Gonzalez, E Banday, AJ Argueso, F Gallegos, JE Gorski, KM Hinshaw, G AF Cayon, L Sanz, JL Martinez-Gonzalez, E Banday, AJ Argueso, F Gallegos, JE Gorski, KM Hinshaw, G TI Spherical Mexican hat wavelet: an application to detect non-Gaussianity in the COBE-DMR maps SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE methods : data analysis; cosmic microwave background ID COSMOLOGICAL DENSITY PERTURBATIONS; MICROWAVE BACKGROUND-RADIATION; SKY MAPS; FLUCTUATIONS; STATISTICS; SPOTS AB The spherical Mexican hat wavelet is introduced in this paper, with the aim of testing the Gaussianity of the cosmic microwave background temperature fluctuations. Using the information given by the wavelet coefficients at several scales, we have performed several statistical tests on the COBE-DMR maps to search for evidence of non-Gaussianity. Skewness, kurtosis, scale-scale correlations (for two and three scales) and Kolmogorov-Smirnov tests indicate that the COBE-DMR data are consistent with a Gaussian distribution. We have extended the analysis to compare temperature values provided by COBE-DMR data with distributions (obtained from Gaussian simulations) at each pixel and at each scale. The number of pixels with temperature values outside the 95 and 99 per cent limits is consistent with that obtained from Gaussian simulations, at all scales. Moreover, the extrema values for COBE-DMR data (maximum and minimum temperatures in the map) are also consistent with those obtained from Gaussian simulations. C1 Fac Ciencias, Inst Fis Cantabria, Santander, Spain. Max Planck Inst Astrophys, D-85740 Garching, Germany. Univ Oviedo, Dept Matemat, Oviedo 33007, Spain. European So Observ, D-85740 Garching, Germany. Univ Warsaw Observ, Warsaw, Poland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Cayon, L (reprint author), Fac Ciencias, Inst Fis Cantabria, Av Castros S-N, Santander, Spain. RI Martinez-Gonzalez, Enrique/E-9534-2015 OI Martinez-Gonzalez, Enrique/0000-0002-0179-8590 NR 38 TC 56 Z9 56 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 OCT 1 PY 2001 VL 326 IS 4 BP 1243 EP 1248 DI 10.1111/j.1365-2966.2001.04641.x PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480DH UT WOS:000171446400005 ER PT J AU Farrah, D Rowan-Robinson, M Oliver, S Serjeant, S Borne, K Lawrence, A Lucas, RA Bushouse, H Colina, L AF Farrah, D Rowan-Robinson, M Oliver, S Serjeant, S Borne, K Lawrence, A Lucas, RA Bushouse, H Colina, L TI HST/WFPC2 imaging of the QDOT ultraluminous infrared galaxy sample SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : active; quasars : general; galaxies : Seyfert; galaxies : starburst; infrared : galaxies ID ACTIVE GALACTIC NUCLEI; HUBBLE DEEP FIELD; IRAS GALAXIES; INTERACTING GALAXIES; STAR-FORMATION; OPTICAL POLARIZATION; LUMINOSITY FUNCTION; STARBURST GALAXIES; ELLIPTIC GALAXIES; REDSHIFT SURVEY AB We present HST WFPC2 V-band imaging for 23 ultraluminous infrared galaxies (ULIRGs) taken from the QDOT redshift survey. The fraction of sources observed to be interacting is 87 per cent. Most of the merging systems show a number of compact 'knots', whose colour and brightness differ substantially from their immediate surroundings. Colour maps for nine of the objects show a non-uniform colour structure. Features include blue regions located towards the centres of merging systems which are Likely to be areas of enhanced star formation, and compact red regions which are likely to be dust shrouded starbursts or active Galactic nuclei. The host galaxies of the quasi-stellar objects (QSOs) in the sample were found to be either interacting systems or ellipticals. Our data show no evidence that ULIRGs are a simple transition stage between galaxy mergers and QSOs. We propose an alternative model for ULIRGs based on the morphologies in our sample and previous N-body simulations. Under this model ULIRGs as a class are much more diverse than a simple transition between galaxy merger and QSO. The evolution of IR power source and mer er morphology in ULIRGs is driven solely by the local environment and the morphologies of the merger progenitors. C1 Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Astrophys Grp, London SW7 2BW, England. Univ Sussex, Ctr Astron, Brighton BN1 9QJ, E Sussex, England. Univ Kent, Sch Phys Sci, Unit Space Sci & Astrophys, Canterbury CT2 7NZ, Kent, England. NASA, Raytheon ITSS, GSFC, Greenbelt, MD USA. Univ Edinburgh, Royal Observ, Inst Astron, Edinburgh EH9 3HJ, Midlothian, Scotland. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Inst Fis Cantabria, Santander, Spain. RP Farrah, D (reprint author), Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Astrophys Grp, Prince Consort Rd, London SW7 2BW, England. NR 87 TC 79 Z9 79 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 OCT 1 PY 2001 VL 326 IS 4 BP 1333 EP 1352 DI 10.1111/j.1365-2966.2001.04721.x PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480DH UT WOS:000171446400014 ER PT J AU Jarvis, MJ Rawlings, S Lacy, M Blundell, KM Bunker, AJ Eales, S Saunders, R Spinrad, H Stern, D Willott, CJ AF Jarvis, MJ Rawlings, S Lacy, M Blundell, KM Bunker, AJ Eales, S Saunders, R Spinrad, H Stern, D Willott, CJ TI A sample of 6C radio sources designed to find objects at redshift z > 4 - II. Spectrophotometry and emission-line properties SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : active; radio continuum : galaxies ID COMPACT STEEP-SPECTRUM; OPTICAL IDENTIFICATIONS; GALAXIES; EVOLUTION; NUCLEI; GAS AB This is the second in a series of three papers that present and interpret basic observational data on the 6C* 151-MHz radio sample: a low-frequency selected sample that exploits filtering criteria based on radio properties (steep spectral index and small angular size) to find radio sources at redshift z > 4 within a 0.133-sr patch of sky. We present results of a programme of optical spectroscopy that has yielded redshifts in the range 0.5 less than or similar to z less than or similar to 4.4 for the 29 sources in the sample, all but six of which are secure. We find that the filtering criteria used for 6C* are very effective in excluding the low-redshift, low-luminosity radio sources: the median redshift of 6C* is z approximate to 1.9 compared with z approximate to 1.1 for a complete sample matched in 151-MHz flux density. By combining the emission-line data set for the 6C* radio sources with those for the 3CRR, 6CE and 7CRS samples we establish that z greater than or equal to 1.75 radio galaxies follow a rough proportionality between Ly alpha and 151-MHz luminosity, which, like similar correlations seen in samples of lower redshift radio sources, is indicative of a primary link between the power in the source of the photoionizing photons (most likely a hidden quasar nucleus) and the power carried by the radio jets. We argue that radio sources modify their environments and that the range of emission-line properties seen is determined more by the range of source age than by the range in ambient environment. The smallest z > 1.75 radio galaxies have all the properties expected if the size distribution of luminous high-redshift steep-spectrum radio sources reflects a broad range (similar to2 dex) of source ages with a narrower range (less than or similar to1.5 dex) of environmental densities, namely: (1) high-ionization lines, e.g. Ly alpha of relatively low luminosity; (2) boosted low-ionization lines, e.g. C II]; (3) spatially compact emission-line regions; and (4) HI-absorbed Ly alpha profiles. This is in accord with the idea that all high-redshift, high-luminosity radio sources are triggered in similar environments, presumably recently collapsed massive structures. C1 Univ Oxford, Dept Phys, Oxford OX1 3RH, England. Sterrewacht Leiden, NL-2300 RA Leiden, Netherlands. Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Cardiff Univ, Dept Phys & Astron, Cardiff CF2 3YB, S Glam, Wales. Univ Cambridge, Cavendish Lab, Astrophys Grp, Cambridge CB3 0HE, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Univ Oxford, Dept Phys, Keble Rd, Oxford OX1 3RH, England. EM jarvis@strw.leidenuniv.nl NR 61 TC 49 Z9 49 U1 0 U2 1 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 1 PY 2001 VL 326 IS 4 BP 1563 EP 1584 DI 10.1111/j.1365-2966.2001.04726.x PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 480DH UT WOS:000171446400035 ER PT J AU Cockell, CS Scherer, K Horneck, G Rettberg, P Facius, R Gugg-Helminger, A Driscoll, C Lee, P AF Cockell, CS Scherer, K Horneck, G Rettberg, P Facius, R Gugg-Helminger, A Driscoll, C Lee, P TI Exposure of arctic field scientists to ultraviolet radiation evaluated using personal dosimeters SO PHOTOCHEMISTRY AND PHOTOBIOLOGY LA English DT Article ID SOLAR UV-RADIATION; HAUGHTON IMPACT STRUCTURE; BACILLUS-SUBTILIS; BIOFILM TECHNIQUE; B RADIATION; ANTARCTICA; AMPLIFICATION; IRRADIANCE; QUEENSLAND; SITES AB During, July 2000 we used an electronic personal dosimeter (X-2000) and a biological dosimeter (Deutsches Zentrum, fur Luft- und Raumfahrt: Biofilm) to characterize the UV radiation exposure of arctic field scientists involved in biological and geological fieldwork. These personnel were working at the Haughton impact structure on Devon Island (75 degreesN) in the Canadian High Arctic under a 24 h photoperiod. During a typical day of field activities under a clear sky, the total daily erythermally weighted exposure,. as, measured by electronic dosimetry, was up to 5.8 standard erythemal dose (SED). Overcast skies. (typically 7-8 okta of stratus); reduced exposures by a mean of 54%. We estimate that during a month of field activity in July a typical field scientist at this latitude could potentially receive similar to 80 SED to the face. Because of body movements the upper body was exposed to a UV regimen that often changed on second-to-second timescales as assessed by electronic dosimetry. Over a typical 10 min period on vehicle traverse, we found that erythemal exposure could vary to up to 87% of the mean exposure. Time-integrated exposures showed that the type of outdoor field activities in the treeless expanse of the polar desert had little effect on the exposure received. Although absolute exposure changed in accordance with the time of day, the exposure ratio (dose received over horizontal dose) did not vary much over the day. Under clear skies the mean exposure ratio was 0.35 +/- 0.12 for individual activities at different times of the day assessed using electronic dosimetry. Biological dosimetry showed that the occupation was important in determining daily exposures. In our study, scientists in the field received an approximately two-fold higher dose than individuals, such as, medics, and computer scientists, who spent the majority of their time in tents. C1 British Antarctic Survey, Cambridge CB3 0ET, England. Inst Aerosp Med, German Aerosp Ctr, Cologne, Germany. Gigahertz Opt, Puchheim, Germany. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Cockell, CS (reprint author), British Antarctic Survey, High Cross,Madingley Rd, Cambridge CB3 0ET, England. EM csco@bas.ac.uk RI Rettberg, Petra/K-2378-2015 OI Rettberg, Petra/0000-0003-4439-2395 NR 39 TC 22 Z9 24 U1 1 U2 3 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0031-8655 J9 PHOTOCHEM PHOTOBIOL JI Photochem. Photobiol. PD OCT PY 2001 VL 74 IS 4 BP 570 EP 578 DI 10.1562/0031-8655(2001)074<0570:EOAFST>2.0.CO;2 PG 9 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA 485WP UT WOS:000171786700009 PM 11683037 ER PT J AU Anantram, M Delzeit, L Cassell, A Han, J Meyyappan, M AF Anantram, M Delzeit, L Cassell, A Han, J Meyyappan, M TI Nanotubes in nanoelectronics: transport, growth and modeling SO PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES LA English DT Article; Proceedings Paper CT Rutherford Memorial Workshop on Semiconductor Nanostructures CY FEB 05-09, 2001 CL QUEENSTOWN, NEW ZEALAND SP USAF Off Sci Res, Asian Off Aerosp Res & Dev, USN, Off Naval Res Int Field Off, USA Res Off Far E, Japan Soc Promot Sci, 151st Comm Nanometre Struct & Electr, Royal Soc New Zealand, Elsevier Sci, Keithley Instruments, Air New Zealand DE nanotubes; ballistic transport; chemical vapour deposition ID WALLED CARBON NANOTUBES; SINGLE; DEVICES AB Carbon nanotube based nanotechnology appears to be Promising for future nanoelectronics. Theoretical analysis and results for the ballistic current carrying capacity of nanotube wires are presented. Aspects of metal-nanotube coupling are examined. Results are also presented for chemical vapor deposition of CNT from hydrocarbon feedstock. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Meyyappan, M (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. EM meyya@orbit.arc.nasa.gov NR 21 TC 11 Z9 11 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 1386-9477 J9 PHYSICA E JI Physica E PD OCT PY 2001 VL 11 IS 2-3 BP 118 EP 125 DI 10.1016/S1386-9477(01)00187-4 PG 8 WC Nanoscience & Nanotechnology; Physics, Condensed Matter SC Science & Technology - Other Topics; Physics GA 485HC UT WOS:000171746600014 ER PT J AU Korona, KP Babinski, A Kuhl, J Baranowski, JM Leon, R AF Korona, KP Babinski, A Kuhl, J Baranowski, JM Leon, R TI Step-like photoluminescence dynamics in field-effect structures containing quantum dots SO PHYSICA STATUS SOLIDI B-BASIC RESEARCH LA English DT Article ID CARRIER RELAXATION AB We present time-resolved photoluminescence investigations of field-effect structures containing quantum dots (QDs). The high electrical field in those devices significantly influences carrier dynamics, Photoluminescence (PL) from the ground state occurs at an energy of 1.35 eV, but after strong excitation the PL band can reach up to 1.5 eV due to state filling. After strong excitation, a few hundred picoseconds of slow PL decay are observed. Then the emission from the QDs performs a step-like quenching. The remaining luminescence has a long lifetime (about 1 ns) and its maximum occurs at about 1.35 eV. Numerical calculations suggest that the step-like PL quenching is caused by a decay of screening of the electrical field in the region with QDs. C1 Univ Warsaw, Inst Expt Phys, PL-00681 Warsaw, Poland. Max Planck Inst Festkorperforsch, D-70569 Stuttgart, Germany. Australian Natl Univ, Dept Elect Mat Engn, Canberra, ACT 02000, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Korona, KP (reprint author), Univ Warsaw, Inst Expt Phys, Hoza 69, PL-00681 Warsaw, Poland. OI Babinski, Adam/0000-0002-5591-4825 NR 16 TC 1 Z9 1 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA PO BOX 10 11 61, D-69451 BERLIN, GERMANY SN 0370-1972 J9 PHYS STATUS SOLIDI B JI Phys. Status Solidi B-Basic Res. PD OCT PY 2001 VL 227 IS 2 BP 605 EP 612 DI 10.1002/1521-3951(200110)227:2<605::AID-PSSB605>3.0.CO;2-S PG 8 WC Physics, Condensed Matter SC Physics GA 489HU UT WOS:000171986600035 ER PT J AU Daftuar, S Klimesh, M AF Daftuar, S Klimesh, M TI Mathematical structure of entanglement catalysis SO PHYSICAL REVIEW A LA English DT Article ID STATES AB The majorization relation has been shown to be useful in classifying which transformations of jointly held quantum states are possible using local operations and classical communication. In some cases, a direct transformation between two states is not possible, but it becomes possible in the presence of another state (known as a catalyst) this situation is described mathematically by the trumping relation, an extension of majorization. The structure of the trumping relation is not nearly as well understood as that of majorization. We give an introduction to this subject and derive some results. Most notably. we show that the dimension of the required catalyst is, in general, unbounded; there is no integer k such that it suffices to consider catalysts of dimension k or less in determining which states can be catalyzed into a given state. We also show that almost all bipartite entangled states are potentially useful as catalysts. C1 CALTECH, Inst Quantum Informat, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Daftuar, S (reprint author), CALTECH, Inst Quantum Informat, Pasadena, CA 91125 USA. EM daftuar@its.caltech.edu; klimesh@shannon.jpl.nasa.gov NR 15 TC 19 Z9 19 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD OCT PY 2001 VL 64 IS 4 AR 042314 DI 10.1103/PhysRevA.64.042314 PG 6 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 482ZU UT WOS:000171609900036 ER PT J AU Howe, PT Kortyna, A Darrach, M Chutjian, A AF Howe, PT Kortyna, A Darrach, M Chutjian, A TI Low-energy electron attachment to SF6 at sub-meV resolution using a tunable laser photoelectron method SO PHYSICAL REVIEW A LA English DT Article ID VIBRATIONAL FESHBACH RESONANCES; RATE CONSTANTS; CROSS-SECTIONS; HIGH-N; MOLECULES; COLLISIONS; THRESHOLD; ULTRAVIOLET; CCL4; BEAM AB Electron attachment to sulfur hexafluoride is studied using a photoelectron source of ultralow-energy electrons with sub-meV resolution. Vacuum-ultraviolet laser radiation produced through nonlinear-optical techniques is used to photoionize xenon at and above its P-2(1/2)o ionization limit. The resulting photoelectrons interact with sulfur hexafluoride admixed to the xenon. The electron energy is continuously scanned from 0 to 127 meV, with a resolution of 0.1 meV at threshold. Computational modeling indicates that the attachment cross section is well described by the Wigner threshold law at electron energies less than about 5 meV. Data at higher energies are best described by the Wigner s-wave form, or by a Klots form with beta =0.228. Cusps are observed at the omega (6), omega (1), and omega (3) vibrational modes of SF6. While the omega (1) and omega (3) cusps have their maxima at the spectroscopic energies of 97.1 and 117.6 meV, respectively, the omega (6) cusp has its maximum at 46 meV, nearly 3 meV higher than its spectroscopic value of 43.2+/-0.4 meV. Possible explanations are considered, such as a low-l angular-momentum barrier, an overtone mode of SF6 excited by the collision, or clustering. The definitive cause of this shift is not understood. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lafayette Coll, Dept Phys, Easton, PA 18042 USA. RP Howe, PT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 46 TC 12 Z9 12 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD OCT PY 2001 VL 64 IS 4 AR 042706 DI 10.1103/PhysRevA.64.042706 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 482ZU UT WOS:000171609900060 ER PT J AU Huo, WM AF Huo, WM TI Convergent series representation for the generalized oscillator strength of electron-impact ionization and an improved binary-encounter-dipole model SO PHYSICAL REVIEW A LA English DT Article ID PARTIAL CROSS-SECTIONS; CHARGED-PARTICLES; ATOM SCATTERING; WAVE-FUNCTIONS; BASIS-SETS; R-MATRIX; THRESHOLD; MOLECULES; CH4; HYDROGEN AB The use of the Bethe cross section in the binary-encounter-dipole (BED) model for electron-impact ionization is studied. While the dipole contribution in the Born approximation accounts for the longest-range interaction in electron-neutral atom/molecule inelastic collisions at any incident energy. the Bethe formula is applicable only at high energies. To derive a suitable representation of the Born cross section for dipole-allowed transitions. a convergent series representation for the generalized oscillator strength (GOS) of electron-impact ionization is studied. It is shown that by transforming to a new variable determined by the location of the singularities of the GOS on the complex plane of momentum transfer K, a series representation for the GOS is obtained that is convergent at all physically attainable values of K. An approximate representation of the GOS that truncates the series representation to the first three terms is also given. The approximate GOS describes the interaction of the electron with a shielded dipole potential and satisfies both Lassettre's limit theorem at K = 0 and the asymptotic behavior at large K derived by Rau and Fano [A. R P. Rau and U. Fano, Phys. Rev. 162, 68 (1967)]. The dipole-Born cross section so obtained is applicable at all incident energies and goes to the Bethe cross section at the high-energy limit. It provides a more suitable representation of the dipole contribution in the BED model than the Bethe cross section and is valid over the entire energy range. A similar analysis of the optical-oscillator strength (OOS) as a function of the complex momentum for the ejected electron k(p), plus the requirement that the OOS satisfies both the low- and high-k(p) limits produces an analogous series representation for the OOS. An approximate one-term representation of the OOS is also developed that can be used in modeling calculations. Numerical examples of total ionization cross sections of N-2, H2O, CO2, CH4, and CF4 using the new analytical representation are presented to illustrate the applicability of the improved BED model. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Huo, WM (reprint author), NASA, Ames Res Ctr, Mail Stop T27B-1, Moffett Field, CA 94035 USA. NR 54 TC 30 Z9 30 U1 1 U2 4 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD OCT PY 2001 VL 64 IS 4 AR 042719 DI 10.1103/PhysRevA.64.042719 PG 16 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 482ZU UT WOS:000171609900073 ER PT J AU Stallcop, JR Partridge, H Levin, E AF Stallcop, JR Partridge, H Levin, E TI Effective potential energies and transport cross sections for atom-molecule interactions of nitrogen and oxygen SO PHYSICAL REVIEW A LA English DT Article ID DER-WAALS COEFFICIENTS; COUPLED-CLUSTER THEORY; GAUSSIAN-BASIS SETS; COLLISION INTEGRALS; DISPERSION COEFFICIENTS; HARTREE-FOCK; ELECTRON CORRELATION; WAVE-FUNCTIONS; HYDROGEN; HE AB The potential energy surfaces for H-2-N and N-2-N interactions are calculated by accurate ab initio methods and applied to determine transport data. The results confirm that an effective potential energy for accurately deter-mining transport properties can be calculated using a single predetermined orientation. A simple method is developed to determine the dispersion coefficients of effective potential energies. Effective potential energies required for O-2-O collisions are determined. The H-2-N, N-2-N, O-2-H. and O-2-O collision integrals are calculated and tabulated for a broad range of temperatures. The theoretical values of the N-2-N and O-2-O diffusion coefficients compare well with measured data available at room temperature. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Eloret Corp, Moffett Field, CA 94035 USA. RP NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 68 TC 33 Z9 33 U1 0 U2 6 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9926 EI 2469-9934 J9 PHYS REV A JI Phys. Rev. A PD OCT PY 2001 VL 64 IS 4 AR 042722 DI 10.1103/PhysRevA.64.042722 PG 12 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 482ZU UT WOS:000171609900076 ER PT J AU Cho, H Williams, GA AF Cho, H Williams, GA TI One-dimensional excitations in superfluid He-4 and He-3-He-4 mixture films adsorbed in porous materials SO PHYSICAL REVIEW B LA English DT Article ID VORTEX CORE SIZE; PHASE-TRANSITION; HELIUM FILMS; THERMODYNAMICS; HEAT AB normal-fluid component varying as T-2 is observed at very low temperatures in superfluid He-4 and He-3-He-4 mixture films adsorbed in alumina powder. The normal fluid appears to arise from thermally excited third sound that has one-dimensional propagation characteristics. A Landau model of third sound excitations in an infinite cylindrical pore by Saam and Cole provides good agreement with the experimental measurements over a wide range of He-4 and He-3 coverages. However, it is unclear why the powder substrate can be modeled as having cylindrical pores. C1 Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. RP Cho, H (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 28 TC 0 Z9 0 U1 1 U2 3 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 OCT 1 PY 2001 VL 64 IS 14 AR 144503 PG 5 WC Physics, Condensed Matter SC Physics GA 481QC UT WOS:000171530000076 ER PT J AU Hu, ZW Lai, B Chu, YS Cai, Z Mancini, DC Thomas, BR Chernov, AA AF Hu, ZW Lai, B Chu, YS Cai, Z Mancini, DC Thomas, BR Chernov, AA TI Phase sensitive X-ray diffraction imaging of defects in biological macromolecular crystals SO PHYSICAL REVIEW LETTERS LA English DT Article ID SYNCHROTRON-RADIATION; TOPOGRAPHY; CRYSTALLIZATION; PROTEIN; RESOLUTION; LYSOZYME; SPECKLE; GROWTH AB Conventional x-ray diffraction topography is currently used to map defects in the bulk of protein crystals, but the lack of sufficient contrast is frequently a limiting factor. We experimentally demonstrate that this barrier can be circumvented using a method that combines phase sensitive and diffraction imaging principles. Details of defects revealed in tetragonal lysozyme and cubic ferritin crystals are presented and discussed. The approach enabling the detection of the phase changes of diffracted x rays should prove to be useful in the study of defect structures in a broad range of biological macromolecular crystals. C1 NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. Argonne Natl Lab, Adv Photon Source, Argonne, IL 60439 USA. Univ Alabama, Ctr Micrograv Mat Res, Huntsville, AL 35899 USA. RP Hu, ZW (reprint author), NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. EM zhengwei.hu@msfc.nasa.gov NR 29 TC 15 Z9 15 U1 2 U2 6 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 OCT 1 PY 2001 VL 87 IS 14 AR 148101 DI 10.1103/PhysRevLett.87.148101 PG 4 WC Physics, Multidisciplinary SC Physics GA 479WV UT WOS:000171427500044 PM 11580675 ER PT J AU Hogan, RC Cuzzi, JN AF Hogan, RC Cuzzi, JN TI Stokes and Reynolds number dependence of preferential particle concentration in simulated three-dimensional turbulence SO PHYSICS OF FLUIDS LA English DT Article ID ISOTROPIC TURBULENCE; HEAVY-PARTICLES; FLOWS AB An analysis of particle concentrations formed in direct numerical simulations of forced three-dimensional (3-D) turbulence is described, Up to 48 million particles responding passively to the flow with response times ranging from 0.2 to 6 times the dissipation time of the fluid were evolved together until the concentration field reached a statistical stationary state. The Stokes number (St), defined at the dissipation time scale, was the sole parameter used to characterize the particle-fluid coupling in the regime where particles preferentially concentrate. Concentrations resulting from three simulations equilibrating at the Taylor microscale Reynolds numbers (Re-lambda) 40, 80, and 140 were studied. We present several new results for concentration measures utilized in previous studies as well as measures introduced in this paper. The measures are compared and contrasted on a finer St grid than presented in previous work and are analyzed as functions of Re-lambda and spatial binning scale. The measures are based on (a) deviations of the concentration PDF (probability density function) from the PDF of a uniform particle field, (b) the correlation dimension (D-2) for both 3-D and two-dimensional concentrations, and (c) the relative St-dependent concentrations contained in a localized region of space. Measure (c) is motivated by the observation that the total and St-dependent concentrations are linearly correlated. The concentration measures reveal St dependencies that are insensitive to the Reynolds number of the flow with each measure having its own characteristic shape. The widths and maxima of St functions for measures explicitly constructed on a single spatial binning scale showed a very weak dependence on bin sizes ranging from 2 to 6 times the Kolmogorov length scale. We conclude that the measures studied in this paper reveal a universality that may persist to much higher Reynolds numbers. (C) 2001 American Institute of Physics. C1 Symtech Inc, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Hogan, RC (reprint author), Symtech Inc, MS 245-3, Moffett Field, CA 94035 USA. NR 17 TC 57 Z9 58 U1 2 U2 8 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD OCT PY 2001 VL 13 IS 10 BP 2938 EP 2945 DI 10.1063/1.1399292 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 476LG UT WOS:000171228100019 ER PT J AU Dee, DP Rukhovets, L Todling, R Da Silva, AM Larson, JW AF Dee, DP Rukhovets, L Todling, R Da Silva, AM Larson, JW TI An adaptive buddy check for observational quality control SO QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY LA English DT Article DE adaptive tolerances; data assimilation; quality control ID DATA ASSIMILATION AB An adaptive buddy-check algorithm is presented that adjusts tolerances for suspect observations, based on the variability of surrounding data. The algorithm derives from a statistical hypothesis test combined with maximum-likelihood covariance estimation. Its stability is shown to depend on the initial-identification of outliers by a simple background check. The adaptive feature ensures that the final quality-control decisions are not very sensitive to prescribed statistics of first-guess and observation errors, nor on other approximations introduced into the algorithm. The implementation of the algorithm in a global atmospheric data assimilation is described. Its performance is contrasted with that of a non-adaptive buddy check, for the surface analysis of an extreme storm that took place over Europe on 27 December 1999. The adaptive algorithm allowed the inclusion of many important observations that differed greatly from the first guess and that would have been excluded on the basis of prescribed statistics. The analysis of the storm development was much improved as a result of these additional observations. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Argonne Natl Lab, Argonne, IL 60439 USA. RP Dee, DP (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Mail Code 910-3, Greenbelt, MD 20771 USA. RI da Silva, Arlindo/D-6301-2012 OI da Silva, Arlindo/0000-0002-3381-4030 NR 26 TC 29 Z9 30 U1 0 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 OCT PY 2001 VL 127 IS 577 BP 2451 EP 2471 DI 10.1002/qj.49712757714 PN A PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 487TC UT WOS:000171890500013 ER PT J AU Goward, SN Masek, JG AF Goward, SN Masek, JG TI Landsat - 30 years and counting SO REMOTE SENSING OF ENVIRONMENT LA English DT Editorial Material C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. RP Goward, SN (reprint author), Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RI Masek, Jeffrey/D-7673-2012 NR 5 TC 20 Z9 22 U1 1 U2 3 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 OCT PY 2001 VL 78 IS 1-2 SI SI BP 1 EP 2 DI 10.1016/S0034-4257(01)00306-6 PG 2 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 481NE UT WOS:000171525000001 ER PT J AU Goward, SN Masek, JG Williams, DL Irons, JR Thompson, RJ AF Goward, SN Masek, JG Williams, DL Irons, JR Thompson, RJ TI The Landsat 7 mission - Terrestrial research and applications for the 21st century SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SATELLITE DATA; FUTURE; CARBON AB The Landsat Earth observation approach introduced in 1972 created a new way of monitoring land cover and land use globally. The Landsat 7 mission, successfully launched on April 15, 1999, continues those observations and demonstrates significant progress in precise numerical radiometry, spectral differentiation, and seasonally repetitive monitoring. Substantial improvements in calibration procedures, both prior to launch and during normal operations, have also been made to ensure long-term stability in the acquired spectral radiometry. Landsat 7 data acquisitions are being driven by a long-term data acquisition plan that was designed to ensure that substantially cloud-free, seasonal coverage would be recorded and archived in the US for all land areas of the globe. NASA competitively selected a Landsat Science Team, consisting of representatives from US universities and government agencies, to exploit the Landsat 7 record for global change research. This team is addressing the technical and analytical means to process and analyze the core of this observation record, and for the first time in the history of the Landsat mission, the technical and operational aspects of the mission are being driven by the goals of the US science community. The expected outcome of these efforts is a rapid improvement in understanding the Earth system, as well as conceptual knowledge that will underpin significant advancements in the application of this technology for commercial, operational, educational, and research purposes. Pathways to achieve effective Landsat continuity in the early decades of the 21st century are also being given careful attention, and there is no question that the lessons teamed from the Landsat 7 mission will strongly influence these next-generation sensor systems. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Univ Maryland, Dept Geog, Lab Global Remote Sensing, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Landsat Project Sci Off, Greenbelt, MD 20771 USA. US Geol Survey, EROS Data Ctr, Sioux Falls, SD USA. RP Goward, SN (reprint author), Univ Maryland, Dept Geog, Lab Global Remote Sensing, Lefrak Hall,Room 1113, College Pk, MD 20742 USA. EM sg21@umail.umd.edu RI Masek, Jeffrey/D-7673-2012; Irons, James/D-8535-2012 NR 32 TC 59 Z9 60 U1 0 U2 9 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 EI 1879-0704 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 2001 VL 78 IS 1-2 SI SI BP 3 EP 12 DI 10.1016/S0034-4257(01)00262-0 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 481NE UT WOS:000171525000002 ER PT J AU Arvidson, T Gasch, J Goward, SN AF Arvidson, T Gasch, J Goward, SN TI Landsat 7's long-term acquisition plan - an innovative approach to building a global imagery archive SO REMOTE SENSING OF ENVIRONMENT LA English DT Article DE Landsat 7; Long-term Acquisition Plan; LTAP; planning; scheduling; seasonality; cloud avoidance AB The Landsat-7 Long-Term Acquisition Plan (LTAP) automates the selection of Landsat scenes to periodically refresh a global archive of sunlit, substantially cloud-free land images. Its automatic nature reduces the workload on both operations and science office management, and makes the best use of limited resources both on board the satellite and in the ground-processing systems. The core of the LTAP is the definition of seasonality for each scene of interest, where seasonality is defined as the occurrence of change over time. When significant change is occurring, acquisition frequencies are high. Conversely, if little change is occurring, acquisition frequencies are low. This definition of seasonality was augmented with suggested acquisition frequencies from the various science community niches that have historically relied on Landsat data to support their research goals. Cloud climatology for each scene was determined, as monthly historical averages, so it could be compared during scheduling with the daily cloud-cover predictions to discriminate between scenes cloudier than usual (less worthy of acquisition) and scenes clearer than normal (more worthy of acquisition). A scheduler system executes the LTAP and builds the daily schedule by evaluating many factors for each scene, including seasonality, acquisition history, cloud cover, and availability of resources. The result of this evaluation is a list of the "best" 250 scenes to be acquired that day. An important tool in the development of the scheduling system and in the evaluation of the LTAP performance is a modeling capability that allows "what if" analyses to be made and proposed changes to the LTAP or the scheduling software to be evaluated. This modeling capability has proven key to understanding the impacts of potential changes in strategy or software. By considering cloud climatology and current cloud-cover predictions, Landsat 7 has acquired imagery with less cloud contamination than previous Landsat data. After 16 months of operations, a relatively cloud-free global archive exists that captures land-cover change where and when it occurs. Additional user requests have been low, suggesting users are finding suitable data already in the archive. Short-term science campaigns and special requests can be accommodated in the LTAP without perturbing the seasonality of the archive or exceeding the available resources. (C) 2001 Elsevier Science Inc. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Landsat 7 Sci Off, Lockheed Martin, Greenbelt, MD 20771 USA. Comp Sci Corp, Landsat 7 Mission Operat Ctr, Lanham, MD USA. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Univ Maryland, Landsat 7 Sci Team, College Pk, MD 20742 USA. RP Arvidson, T (reprint author), NASA, Goddard Space Flight Ctr, Landsat 7 Sci Off, Lockheed Martin, Code 923, Greenbelt, MD 20771 USA. NR 13 TC 77 Z9 85 U1 1 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 OCT PY 2001 VL 78 IS 1-2 SI SI BP 13 EP 26 DI 10.1016/S0034-4257(01)00263-2 PG 14 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 481NE UT WOS:000171525000003 ER PT J AU Teillet, PM Barker, JL Markham, BL Irish, RR Fedosejevs, G Storey, JC AF Teillet, PM Barker, JL Markham, BL Irish, RR Fedosejevs, G Storey, JC TI Radiometric cross-calibration of the Landsat-7 ETM+ and Landsat-5 TM sensors based on tandem data sets SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID THEMATIC MAPPER AB Early in its mission, the Landsat-7 spacecraft was temporarily placed in a "tandem" orbit very close to that of the Landsat-5 spacecraft in order to facilitate the establishment of sensor calibration continuity between the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) and Landsat-5 Thematic Mapper (TM) sensors. The key period for the tandem configuration was June 1-4, 1999, during which hundreds of nearly coincident matching scenes were recorded by both the Landsat-7 ETM+ and, in cooperation with Space Imaging/EOSAT and international ground stations, the Landsat-5 TM as well. The paper presents a methodology for radiometric cross-calibration of the solar reflective spectral bands of the Landsat-7 ETM+ and Landsat-5 TM sensors and results based on analysis of two different tandem image pairs for which ground reference data are available. With the well-calibrated ETM+ as a reference, the tandem-based cross-calibrations for the two image pairs yield TM responsivities that are consistent to each other to within 2% or better depending on the spectral band. Comparisons with independent methods and results obtained by other groups indicate that the tandem-based cross-calibration is within 3% of the independent results on average in spectral bands 1-4 but compares less favorably in bands 5 and 7. The present study indicates that the tandem cross-calibration approach can provide a valuable "contemporary" calibration update for Landsat-5 TM in the visible and near-infrared spectral bands based on the excellent radiometric performance of Landsat-7 ETM+. The methodology also incorporates adjustments for spectral band differences between the two Landsat sensors. Spectral band difference effects are shown to be more dependent on the surface reflectance spectrum than on atmospheric and illumination conditions. A variety of terrestrial surfaces are assessed regarding their suitability for Landsat radiometric cross-calibration in the absence of surface reflectance spectra. Crown Copyright (C) 2001 Elsevier Inc. All rights reserved. C1 Canada Ctr Remote Sensing, Ottawa, ON K1A 0Y7, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. Raytheon Informat Technol & Syst Serv, Lanham, MD 20706 USA. RP Teillet, PM (reprint author), Canada Ctr Remote Sensing, 488 Booth St, Ottawa, ON K1A 0Y7, Canada. RI Markham, Brian/M-4842-2013 OI Markham, Brian/0000-0002-9612-8169 NR 9 TC 185 Z9 210 U1 5 U2 30 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 OCT PY 2001 VL 78 IS 1-2 SI SI BP 39 EP 54 DI 10.1016/S0034-4257(01)00248-6 PG 16 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 481NE UT WOS:000171525000005 ER PT J AU Cahalan, RF Oreopoulos, L Wen, G Marshak, A Tsay, SC DeFelice, T AF Cahalan, RF Oreopoulos, L Wen, G Marshak, A Tsay, SC DeFelice, T TI Cloud characterization and clear-sky correction from Landsat-7 SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RADIATIVE-TRANSFER; ATMOSPHERIC CORRECTION; INDEPENDENT PIXEL; OPTICAL-THICKNESS; STRATOCUMULUS; AEROSOL; ALBEDO; SCATTERING; ALGORITHM; FLUXES AB Landsat, with its wide swath and high resolution, fills an important mesoscale gap between atmospheric variations seen on a few kilometer scale by local surface instrumentation and the global view of coarser resolution satellites such as MODIS. In this important scale range, Landsat reveals radiative effects on the few hundred-meter scale of common photon mean-free-paths, typical of scattering in clouds at conservative (visible) wavelengths, and even shorter mean-free-paths of absorptive (near-infrared) wavelengths. Landsat also reveals shadowing effects caused by both cloud and vegetation that impact both cloudy and clear-sky radiances. As a result, Landsat has been useful in development of new cloud retrieval methods and new aerosol and surface retrievals that account for photon diffusion and shadowing effects. This paper discusses two new cloud retrieval methods: the nonlocal independent pixel approximation (NIPA) and the normalized difference nadir radiance method (NDNR). We illustrate the improvements in cloud property retrieval enabled by the new low gain settings of Landsat-7 and difficulties found at high gains. Then, we review the recently developed "path radiance" method of aerosol retrieval and clear-sky correction using data from the Department of Energy Atmospheric Radiation Measurement (ARM) site in Oklahoma. Nearby clouds change the solar radiation incident on the surface and atmosphere due to indirect illumination from cloud sides. As a result, if clouds are nearby, this extra side-illumination causes clear pixels to appear brighter, which can be mistaken for extra aerosol or higher surface albedo. Thus, cloud properties must be known in order to derive accurate aerosol and surface properties. A three-dimensional (3D) Monte Carlo (MC) radiative transfer simulation illustrates this point and suggests a method to subtract the cloud effect from aerosol and surface retrievals. The main conclusion is that cloud, aerosol, and surface retrievals are linked and must be treated as a combined system. Landsat provides the range of scales necessary to observe the 3D cloud radiative effects that influence joint surface-atmospheric retrievals. (C) 2001 Elsevier Science Inc. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21250 USA. EROS Data Ctr, SAB, Raythean Sci Dept, Boulder, CO 80307 USA. RAP, NCAR, Boulder, CO 80307 USA. RP Cahalan, RF (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RI Oreopoulos, Lazaros/E-5868-2012; Cahalan, Robert/E-3462-2012; Marshak, Alexander/D-5671-2012; Tsay, Si-Chee/J-1147-2014 OI Oreopoulos, Lazaros/0000-0001-6061-6905; Cahalan, Robert/0000-0001-9724-1270; NR 29 TC 31 Z9 32 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 OCT PY 2001 VL 78 IS 1-2 SI SI BP 83 EP 98 DI 10.1016/S0034-4257(01)00251-6 PG 16 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 481NE UT WOS:000171525000008 ER PT J AU Bindschadler, R Dowdeswell, J Hall, D Winther, JG AF Bindschadler, R Dowdeswell, J Hall, D Winther, JG TI Glaciological applications with Landsat-7 imagery: early assessments SO REMOTE SENSING OF ENVIRONMENT LA English DT Article DE glaciology; remote sensing; Landsat; ice sheets; glaciers; sea ice ID GREENLAND ICE-SHEET; MELTING GLACIER ICE; SATELLITE IMAGERY; SEA-ICE; MASS-BALANCE; TM BAND-2; SVALBARD; INTERFEROMETRY; REFLECTANCE; TOPOGRAPHY AB Enhanced Thematic Mapper Plus (ETM+) data from Landsat-7 are providing glaciologists with an ever-expanding data set that makes a comprehensive monitoring of the global cryosphere feasible for the first time in history. Examples of ETM+ data illustrate its ability to satisfy major scientific needs in the glaciological subdisciplines of sea-ice, glacier, ice-cap, and ice-sheet research with high-resolution optical satellite imagery. Examples shown include use as proxy ground-truth, positioning glacier termini and snowlines, and determining snow facies boundaries. The additional ETM+ panchromatic band, at a higher spatial resolution of 15 m, improves the spatial accuracy of these applications. The glaciological aspects of the Landsat-7 Long-Term Acquisition Plan are discussed to show how the timing and location of the image acquisitions will generate a cryospheric data set of unprecedented utility for future research. (C) 2001 Published by Elsevier Science Inc. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Oceans & Ice Branch, Greenbelt, MD 20771 USA. Univ Bristol, Sch Geog Sci, Bristol Glaciol Ctr, Bristol BS8 1SS, Avon, England. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Hydrospher Sci Branch, Greenbelt, MD 20771 USA. Norsk Polar Inst, N-9296 Tromso, Norway. RP Bindschadler, R (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Oceans & Ice Branch, Greenbelt, MD 20771 USA. RI Hall, Dorothy/D-5562-2012 NR 50 TC 27 Z9 37 U1 8 U2 21 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 OCT PY 2001 VL 78 IS 1-2 SI SI BP 163 EP 179 DI 10.1016/S0034-4257(01)00257-7 PG 17 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 481NE UT WOS:000171525000014 ER PT J AU Merry, CJ Stockman, S AF Merry, CJ Stockman, S TI Educational outreach activities for Landsat-7 SO REMOTE SENSING OF ENVIRONMENT LA English DT Article DE education; Landsat; remote sensing AB The goal of the Landsat-7 educational program is to bring applications of Landsat data into K-16 classrooms. The educational strategy of the Landsat Science Team Office relies on collaborating with preexisting education programs in NASA's Earth Science Enterprise (ESE), as well as initiating new projects. Several current Landsat-based education products and programs are described that address science and geography education content for various grade levels. Current and future program developments using Landsat data are also identified for the K-16 classroom. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Ohio State Univ, Dept Civil & Environm Engn & Geodet Sci, Columbus, OH 43210 USA. NASA, Goddard Space Flight Ctr, Landsat 7 Project Sci Off, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. RP Merry, CJ (reprint author), Ohio State Univ, Dept Civil & Environm Engn & Geodet Sci, 2070 Neil Ave,470 Hitchcock Hall, Columbus, OH 43210 USA. NR 7 TC 2 Z9 2 U1 1 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 2001 VL 78 IS 1-2 SI SI BP 217 EP 220 DI 10.1016/S0034-4257(01)00261-9 PG 4 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 481NE UT WOS:000171525000018 ER PT J AU Wiedenbeck, ME Yanasak, NE Cummings, AC Davis, AJ George, JS Leske, RA Mewaldt, RA Stone, EC Hink, PL Israel, MH Lijowski, M Christian, ER von Rosenvinge, TT AF Wiedenbeck, ME Yanasak, NE Cummings, AC Davis, AJ George, JS Leske, RA Mewaldt, RA Stone, EC Hink, PL Israel, MH Lijowski, M Christian, ER von Rosenvinge, TT TI The origin of primary cosmic rays: Constraints from ACE elemental and isotopic composition observations SO SPACE SCIENCE REVIEWS LA English DT Review ID ACCELERATION; ABUNDANCES; GALAXY; SOLAR AB Cosmic-ray isotope observations from NASA's Advanced Composition Explorer (ACE) mission have been used to investigate the composition of cosmic-ray source material. Source abundances relative to Fe-56 are reported for eleven isotopes of Ca, Fe, Co, and Ni, including the very rare isotopes Ca-48 and Ni-64. Although the source abundances range over a factor similar to10(4), most of the ratios to Fe-56 are consistent with solar-system values to within similar to20%. However, there are some notable differences, the most significant being an excess of similar to(70+/-30)% relative to the solar system for the cosmic-ray source ratio Fe-58/Fe-56. The possible association of such an excess with a contribution to the cosmic-ray source from Wolf-Rayet star ejecta is discussed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. Washington Univ, St Louis, MO 63130 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wiedenbeck, ME (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 26 TC 23 Z9 23 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 2001 VL 99 IS 1-4 BP 15 EP 26 DI 10.1023/A:1013816209004 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 514YP UT WOS:000173468900002 ER PT J AU Mewaldt, RA Yanasak, NE Wiedenbeck, ME Davis, AJ Binns, WR Christian, ER Cummings, AC Hink, PL Leske, RA Niebur, SM Stone, EC Von Rosenvinge, TT AF Mewaldt, RA Yanasak, NE Wiedenbeck, ME Davis, AJ Binns, WR Christian, ER Cummings, AC Hink, PL Leske, RA Niebur, SM Stone, EC Von Rosenvinge, TT TI Radioactive clocks and cosmic-ray transport in the Galaxy SO SPACE SCIENCE REVIEWS LA English DT Review ID ADVANCED-COMPOSITION-EXPLORER; ISOTOPIC COMPOSITION; PROPAGATION; NUCLEI; BE-10; DECAY; ACCELERATION; CONSTRAINTS; VOYAGER; CL-36 AB There are a number of radioactive 'clocks' in the cosmic radiation that can be used to measure the time scales for cosmic ray processes in the Galaxy. With high-resolution isotope measurements available from ACE it is now possible to read these clocks with greatly improved accuracy and address key questions about the origin and lifetime of cosmic rays. This paper discusses the status of three such investigations. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. Washington Univ, St Louis, MO 63105 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Mewaldt, RA (reprint author), CALTECH, Pasadena, CA 91125 USA. RI Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 44 TC 12 Z9 12 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 2001 VL 99 IS 1-4 BP 27 EP 39 DI 10.1023/A:1013868225842 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 514YP UT WOS:000173468900003 ER PT J AU Ramaty, R Lingenfelter, RE Kozlovsky, B AF Ramaty, R Lingenfelter, RE Kozlovsky, B TI Spallogenic light elements and cosmic-ray origin SO SPACE SCIENCE REVIEWS LA English DT Review ID METAL-POOR STARS; SUPERNOVA-REMNANTS; OXYGEN ABUNDANCES; ORION COMPLEX; EARLY GALAXY; SUPERBUBBLES; EVOLUTION; NUCLEOSYNTHESIS; ACCELERATION; BERYLLIUM AB We discuss the new information that the light elements, particularly Be, have brought to cosmic-ray studies, specifically to the issue of the origin of the seed material of the cosmic rays. The primary nature of the Be evolution strongly suggests that supernova ejecta are the sources of this material. We discuss the superbubble models that emerged as the most likely site for the acceleration of supernova ejecta, and we review the arguments that support the model in which the present epoch cosmic rays have the same origin as those that produce the light elements throughout the evolutionary history of the Galaxy. These arguments include the facts that the bulk of the Galactic supernovae are confined within the interiors of superbubbles, where their ejecta could dominate the metallicity, and that high velocity grains, which condense out of the cooling and expanding ejecta, serve as the injection source for shock acceleration, via sputtering of grain material and scattering of volatile gas atoms. We also review the evolutionary calculations that show that a secondary origin for the evolution of Be as a function of the O abundance is energetically untenable, and unnecessary if cosmic-ray transport is properly taken into account. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif San Diego, La Jolla, CA 92903 USA. Tel Aviv Univ, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. RP Ramaty, R (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 56 TC 5 Z9 5 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 2001 VL 99 IS 1-4 BP 51 EP 60 DI 10.1023/A:1013872426751 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 514YP UT WOS:000173468900005 ER PT J AU Muller, D Connel, JJ Decourchelle, A Mewaldt, R Reynolds, S Strong, A Volk, H Wiedenbeck, M AF Muller, D Connel, JJ Decourchelle, A Mewaldt, R Reynolds, S Strong, A Volk, H Wiedenbeck, M TI Key measurements in the future - Working group report SO SPACE SCIENCE REVIEWS LA English DT Review ID GALACTIC COSMIC-RAYS; PRODUCTION CROSS-SECTIONS; LIQUID-HYDROGEN TARGET; SUPERNOVA-REMNANTS; INTERSTELLAR-MEDIUM; ENERGY-SPECTRA; SHOCK ACCELERATION; CHEMICAL EVOLUTION; ABUNDANCE RATIOS; NUCLEON BE-9 AB The experimental basis of cosmic-ray astrophysics consists of detailed measurements of the cosmic-ray intensity arriving near earth, of observations of photons in all wavelength bands generated by cosmic ray interactions in the interstellar medium or in the cosmic-ray sources, and of laboratory studies of high energy particle interactions. In addition, a large body of astronomical information on the composition of stellar atmospheres and of the interstellar medium, including interstellar dust grains, is required to bring cosmic-ray data into context with subjects such as nucleosynthesis and evolution of the galaxy. This report will summarize some of these observational questions, will discuss specific experimental needs in current research, and will review some of the key measurements that can be expected for the near future. This review will neither be complete nor attempt to establish observational priorities. However, it will illustrate the variety of observational activities that are required to achieve progress. C1 Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Phys, Chicago, IL 60637 USA. CEA Saclay, Serv Astrophys, F-91191 Gif Sur Yvette, France. CALTECH, Pasadena, CA 91125 USA. N Carolina State Univ, Dept Phys, Raleigh, NC 27695 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. RP Muller, D (reprint author), Univ Chicago, Enrico Fermi Inst, 5640 S Ellis Ave, Chicago, IL 60637 USA. NR 64 TC 1 Z9 1 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 2001 VL 99 IS 1-4 BP 353 EP 373 DI 10.1023/A:1013877922633 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 514YP UT WOS:000173468900029 ER PT J AU Howard, S Dellacorte, C Valco, MJ Prahl, JM Heshmat, H AF Howard, S Dellacorte, C Valco, MJ Prahl, JM Heshmat, H TI Dynamic stiffness and damping characteristics of a high-temperature air foil journal bearing SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT STLE/ASME Tribology Conference CY OCT 21-24, 2001 CL SAN FRANCISCO, CALIFORNIA SP STLE, ASME DE fluid film compliant bearings; foil bearings; gas bearings; turbomachinery AB Using a high-temperature optically based displacement measurement system, a foil air bearing's stiffness and damping characteristics were experimentally determined. Results were obtained over a range of modified Sommerfeld Number from 1.5E6 to 1.5E7, and at temperatures front 25 degrees to 538 degreesC. An Experimental procedure was developed comparing the error in two curve fitting functions to reveal different modes of physical behavior throughout the operating domain. The maxi mum change in dimensionless stiffness was 3.0E-2 to 6.5E-2 over the Sommerfeld Number range tested. Stiffness decreased with temperature by as much as a factor of two front 25 degrees to 538 degreesC. Dimensionless damping was a stronger function of Sommerfeld Number ranging from 20 to 300. As the temperature is increased, the damping shifts from a viscous type to a frictional type. C1 USA, NASA, Glenn Res Ctr, Res Lab, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Mech & Aerosp Engn, Cleveland, OH 44106 USA. Mohawk Innovat Technol Inc, Albany, NY USA. RP Howard, S (reprint author), USA, NASA, Glenn Res Ctr, Res Lab, Cleveland, OH 44135 USA. NR 9 TC 43 Z9 44 U1 1 U2 7 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 OCT PY 2001 VL 44 IS 4 BP 657 EP 663 DI 10.1080/10402000108982507 PG 7 WC Engineering, Mechanical SC Engineering GA 483VM UT WOS:000171656600018 ER PT J AU Nguyen, QN Jones, WR AF Nguyen, QN Jones, WR TI Volatility and wear characteristics of a variety of liquid lubricants for space applications SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT 55th Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 07-11, 2000 CL NASHVILLE, TENNESSEE SP Soc Tribologists & Lubricat Engineers DE fluorocarbons; hydrocarbons; space vehicles; synthetic lubricants; vapor pressure; wear testing device ID POLYSILAHYDROCARBON SYNTHETIC FLUIDS; VACUUM 4-BALL TRIBOMETER; PERFLUOROPOLYETHERS AB The vapor pressures and wear characteristics are critical properties for liquid lubricants to assure long-term reliability and performance in space applications. Vapor pressures, obtained using a Knudsen cell technique, and wear properties, obtained using a vacuum four-ball apparatus, were measured for a series of unformulated liquid lubricants. These included: two multiply alkylated cyclopentanes (MACs) (X-1000 and X-2000). two linear perfluoropolyalkylethers (PFPAEs) (Z-25 and 815Z), and four silahydrocarbons (a tri, a tetra- and two pentas). Vapor pressures were measured at three elevated temperatures (423, 448 and 498K) and extrapolated to room temperature 298K. The lowest 298K vapor pressure of 5.7 x 10(-14) Pa, was obtained with the PFPAE fluid (815Z) and the highest value with the low, molecular weight MAC (X-1000) at 3.6 x 10(-7) Pa. In addition, vacuum wear rates were determined for some of the lubricants. The lowest wear rates (approximately 3 x 10(-11) mm 3 / mm) were observed for three of the silahydrocarbons while the highest wear rates (approximately 2 x 10(-9) mm(3) / mm) were observed with the two PFPAE flu ids (Z-25 and 815Z). The MAC (X-2000) yielded a wear rate of about 10(-10) mm(3) / mm. The results indicated that the silahydrocarbon class of liquid lubricants offers the better potential for space applications. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Nguyen, QN (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 21 TC 5 Z9 5 U1 0 U2 1 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 OCT PY 2001 VL 44 IS 4 BP 671 EP 677 DI 10.1080/10402000108982509 PG 7 WC Engineering, Mechanical SC Engineering GA 483VM UT WOS:000171656600020 ER PT J AU Rai, AK Massey, ML Gschwender, LJ Snyder, CE Zabinski, JS Sharma, SK Jones, WR AF Rai, AK Massey, ML Gschwender, LJ Snyder, CE Zabinski, JS Sharma, SK Jones, WR TI Enhanced performance of Pennzane (R) greases for space applications by both additive formulations and smooth hard coatings SO TRIBOLOGY TRANSACTIONS LA English DT Article DE Pennzane (R); grease; additives; low volatility; bearing steel; wear; coating; surface roughness; steel hardness ID LUBRICANTS AB Tribological requirements of the moving mechanical assemblies (MMAs) of spacecraft are usually satisfied by a variety of lubricants and materials. When the lubricant elastohydrodynamic film is broken, metal-to-metal contact occurs in the MMAs. This may lead to lubricant overheating, and breakdown, and then to increased wear and,failure. Wear related failure can also occur due to evaporation and/or creep of the lubricant over the lifetime of space assembly. As requirements for spacecraft performance and lif?,time increase, improved lubrication systems for MMAs are needed. A considerable amount of progress has been made in developing improved lubricants with advanced additives; however their performance has not been evaluated and ranked. In the present work, four-ball and reciprocating tribometer tests were conducted to evaluate and rank the performance of various Pennzane (R) based greases. Employing the reciprocating tribometer technique, Pennzane (R) based greases were also evaluated with hard coatings such as titanium nitride (TiN) and titanium carbonitride (TiCN) in a metal-on-coating configuration. Viability of a filtered cathodic arc technique for obtaining very smooth, hard coatings is demonstrated, The importance of coating deposition temperature for certain bearing steel materials is also discussed. It is demonstrated that wear is substantially reduced with an optimized Pennzane (R) grease formulation on a smooth, hard TiCN surface coating. C1 Universal Energy Syst Inc, Dayton, OH 45432 USA. AFRL, MLBT, Mat & Mfg Directorate, Wright Patterson AFB, OH 45433 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Rai, AK (reprint author), Universal Energy Syst Inc, Dayton, OH 45432 USA. NR 15 TC 2 Z9 2 U1 0 U2 1 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 OCT PY 2001 VL 44 IS 4 BP 678 EP 684 DI 10.1080/10402000108982510 PG 7 WC Engineering, Mechanical SC Engineering GA 483VM UT WOS:000171656600021 ER PT J AU Kuhlman, KR Martens, RL Kelly, TF Evans, ND Miller, MK AF Kuhlman, KR Martens, RL Kelly, TF Evans, ND Miller, MK TI Fabrication of specimens of metamorphic magnetite crystals for field ion microscopy and atom probe microanalysis SO ULTRAMICROSCOPY LA English DT Article; Proceedings Paper CT 46th International Field Emission Symposium CY JUL 23-28, 2000 CL PITTSBURGH, PENNSYLVANIA DE oxide; magnetite; field ion microscopy; atom probe microanalysis; focused ion beam; sample preparation AB Field ion specimens have been successfully fabricated from samples of metamorphic magnetite crystals (Fe3O4) extracted from a polymetamorphosed, granulite-facies marble with the use of a focused ion beam. These magnetite crystals contain nanometer-scale, disk-shaped inclusions making this magnetite particularly attractive for investigating the capabilities of atom probe field ion microscopy (APFIM) for geological materials. Field ion microscope images of these magnetite crystals were obtained in which the observed size and morphology of the precipitates agree with previous results. Samples were analyzed in the energy compensated optical position-sensitive atom probe. Mass spectra were obtained in which peaks for singly ionized O-16, Fe-56 and (FeO)-Fe-56 and doubly ionized Fe-54, Fe-56 and Fe-57 peaks were fully resolved. Manganese and aluminum were observed in a limited analysis of a precipitate in an energy compensated position sensitive atom probe. (C) 2001 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, In Situ Instruments Grp, Device Res & Applicat Sect, Pasadena, CA 91109 USA. Imago Sci Instruments Corp, Madison, WI 53719 USA. Univ Wisconsin, Dept Mat Sci & Engn, Madison, WI 53706 USA. Oak Ridge Natl Lab, Div Met & Ceram, Microscopy & Microanalyt Sci Grp, Oak Ridge, TN 37831 USA. RP Kuhlman, KR (reprint author), CALTECH, Jet Prop Lab, In Situ Instruments Grp, Device Res & Applicat Sect, M-S 302-231,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Evans, Neal/F-5955-2011 NR 9 TC 14 Z9 14 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-3991 J9 ULTRAMICROSCOPY JI Ultramicroscopy PD OCT PY 2001 VL 89 IS 1-3 BP 169 EP 176 DI 10.1016/S0304-3991(01)00116-4 PG 8 WC Microscopy SC Microscopy GA 500EV UT WOS:000172613800024 PM 11770743 ER PT J AU Miyoshi, K AF Miyoshi, K TI Durability evaluation of selected solid lubricating films SO WEAR LA English DT Article; Proceedings Paper CT 13th International Conference on Wear of Materials CY APR 22-26, 2001 CL VANCOUVER, CANADA DE MoS2 films; lead films; silver films; DLC films AB An investigation was conducted to examine the coefficients of friction, wear rates, and durability of bonded molybdenum disulfide (MoS2), magnetron-sputtered MoS2 (MS MoS2), ion-plated silver, ion-plated lead, magnetron-sputtered diamond-like carbon (MS DLC), and plasma-assisted chemical-vapor-deposited DLC (PACVD DLC) films in sliding contact with 6 mm-diameter AISI 440C stainless steel balls. Unidirectional ball-on-disk sliding friction experiments were conducted with a load of 5.9 N and a sliding velocity of 0.2 mls at room temperature in three environments: ultrahigh vacuum (vacuum pressure, 7 x 10(-7) Pa), humid air (relative humidity, similar to 20%), and dry nitrogen (relative humidity, <1 %). The main criteria for judging the performance of the solid lubricating films were coefficient of friction and wear rate, which had to be <0.3 and on the order of 10(-6) mm(3)/N m or less, respectively. The bonded MoS2 and MS MoS2 films met the criteria in all three environments. The ion-plated lead and silver films met the criteria only in ultrahigh vacuum but failed in humid air and in dry nitrogen. The MS DLC and PACVD DLC films met the requirements in humid air and dry nitrogen but failed in ultrahigh vacuum. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Miyoshi, K (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS106-5, Cleveland, OH 44135 USA. EM miyoshi@grc.nasa.gov NR 15 TC 17 Z9 19 U1 1 U2 10 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0043-1648 J9 WEAR JI Wear PD OCT PY 2001 VL 251 BP 1061 EP 1067 DI 10.1016/S0043-1648(01)00759-1 PN 2 PG 7 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 489VJ UT WOS:000172012900030 ER PT J AU Altis, S AF Altis, S TI Tectonic stress state in NE Japan as part of the Okhotsk plate SO TECTONOPHYSICS LA English DT Review DE NE Japan; Okhotsk plate; Japan Sea; extrusion tectonics; geodetic strain; internal deformation; SW Japan; pull-apart basin ID INTRACONTINENTAL TRANSCURRENT STRUCTURE; ANATOLIAN FAULT ZONE; NORTHEAST JAPAN; ISLAND-ARC; PALEOMAGNETIC EVIDENCE; CRUSTAL DEFORMATION; BASIN DEVELOPMENT; SUBDUCTION ZONES; SOUTHWEST JAPAN; EASTERN MARGIN AB An existing geodetic flow velocity model, obtained by using an internal free network adjustment technique, is used to derive estimates for various strain rates parameters in NE Japan. The greatest shortening rates of the principal strains, trending similar toE-W, are located in regions where much steady, internal, frame-invariant plastic flow deformation is observed to be taking place. The internal geodetic adjustment technique yielded the internal deformation in the Tohoku arc; most of the intraplate deformations, including the much folding deformations observed in the inner zone, are produced from within. An interseismic transient elastic loading at a strongly coupled/locked Japan trench would not be needed. The observed ongoing extensive ductile folding deformation in the inner zone of Tohoku may mean that the geodetic strain rates, causing shortening at similar to2-3 cm/yr, probably reflect the more correct level of the deformation, which is steady/permanent, in NE Japan as compared with seismic/faulting data, which indicate similar to0.5 cm/yr shortening. The calculated principal strain rates are used to make an interpretation for the origin of the deviatoric principal stresses within the greater regional plate tectonic framework. The tectonic stress state in NE Japan, as part of the Okhotsk plate, could mostly be influenced by the Okhotsk plate, which is extruding southward to lessen the significant accumulated contractional deformation in NE Asia in the Verkhoyansk-Cherskii mountains. The principal strain rates are similar toN-S extensional essentially everywhere in NE Japan, as a result of the southerly extrusion, except in its southernmost leading edge, in the Uetsu/Fossa Magna province, where the Japan Alps rampart rises in front of the extrusion. Here an similar toE-W compressional stress state prevails. A second similar toE-W contractional zone is found in north-central Tohoku, extending from the Sanriku province in the outer zone to the inner zone in the Japan Sea side, being more prevalent in the latter zone. The calculated rotation rates from the geodetic flow model are clockwise (CW) in both of the similar toE-W contractional regions. NF, Japan, extruding southward, faces buttresses in (1) the Oga-Ojika Line (OOL), and/or a crustal weakness zone between the northern and the southern halves of Tohoku approx. at similar to 38.5 degreesN latitude, and, especially, (2) the Japanese Alps rampart; these obstacles cause the northern and southernmost Tohoku to veer to its right and rotate CW, thereby setting up the similar toE-W-trending compressional deformation in their respective inner zones. Between the OOL (or the 38.5 degreesN boundary) and the Kanto Tectonic Line (KTL), the sense of the differential rotations is counterclockwise (CCW), towards the ocean to the SE. The northern Tohoku (north of the OOL) and the southernmost Tohoku (south of the KTL) cannot rotate CCW towards the ocean because of the Izu block's collision in the south and the relatively strong coupling along the subduction interface beneath the Japan trench in the north off-Sanriku, The relatively stronger long-term coupling between the northern Tohoku and the Pacific plate at the Sanriku coast, with respect to that in off-Fukushima, is due to a flatter subduction. of the Pacific slab there, increasing the plates' interface contact area; the flattening of the subduction dip angle was caused by CCW rotation and shifting of the northern Tohoku along the dextral Honjo-Matsushima Line, roughly corresponding to the OOL, towards the Pacific and overriding of the subduction zone during the formation of the Japan Sea. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NAVOCEANO, Bathymetry Acoust Div, Stennis Space Ctr, Bay St Louis, MS 39522 USA. RP Altis, S (reprint author), NAVOCEANO, Bathymetry Acoust Div, Stennis Space Ctr, Code N531, Bay St Louis, MS 39522 USA. NR 136 TC 6 Z9 6 U1 1 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD SEP 30 PY 2001 VL 339 IS 3-4 BP 311 EP 329 DI 10.1016/S0040-1951(01)00139-1 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 494MJ UT WOS:000172286200004 ER PT J AU Zou, Y Vahdat, N Collins, M AF Zou, Y Vahdat, N Collins, M TI Fire extinguishing ability of 1-bromo-1-propane and 1-methoxynonafluorobutane evaluated by cup burner method SO JOURNAL OF FLUORINE CHEMISTRY LA English DT Article DE halon replacement; bromoalkane; hydrofluoroether; inert gases; cup burner AB The fire extinguishing ability of 1-bromo-1-propane/nitrogen (the molecular formula of 1-bromo-1-propane: CH3-CH2CH2Br) and 1-methoxynonafluorobutane/nitrogen gas mixtures (the molecular formula of 1-methoxynonafluorobutane: CF3CF2CF2CF2OCH3) as total flooding agents were evaluated by a cup burner method. It was shown that addition of small amounts of 1-bromo-1-propane and 1-methoxynonafluorobutane to nitrogen can enhance the extinguishing ability of the inert gas by 47.1 and 31.5%, respectively, and the relative of the extinguishing concentration to the concentration of 1-bromo-1-propane or 1-metboxynonafluorobutane in the flooding agents is: Y = 5.18866 + 26.72165e(-X/11.07715) or Y = 5.96301 + 23.59368 e(-X/22.46021). Meanwhile, an arrangement for mixing organic compounds with inert gases (N-2) before applying to fire was proposed. (C) 2001 Published by Elsevier Science B.V. C1 Tuskegee Univ, Dept Chem Engn, Sch Engn, Tuskegee, AL 36088 USA. NASA, Kennedy Space Ctr, Boca Raton, FL 32899 USA. RP Vahdat, N (reprint author), Tuskegee Univ, Dept Chem Engn, Sch Engn, Tuskegee, AL 36088 USA. NR 14 TC 4 Z9 4 U1 1 U2 3 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0022-1139 J9 J FLUORINE CHEM JI J. Fluor. Chem. PD SEP 28 PY 2001 VL 111 IS 1 BP 33 EP 40 DI 10.1016/S0022-1139(01)00439-0 PG 8 WC Chemistry, Inorganic & Nuclear; Chemistry, Organic SC Chemistry GA 474KL UT WOS:000171105600006 ER PT J AU Prigent, C Aires, F Rossow, W Matthews, E AF Prigent, C Aires, F Rossow, W Matthews, E TI Joint characterization of vegetation by satellite observations from visible to microwave wavelengths: A sensitivity analysis SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HIGH-RESOLUTION RADIOMETER; WIND SCATTEROMETER DATA; TERRESTRIAL BIOPHYSICAL PARAMETERS; LAND-SURFACE EMISSIVITIES; 37 GHZ DATA; SOIL-MOISTURE; GLOBAL VEGETATION; AVHRR DATA; MONITORING VEGETATION; ERS SCATTEROMETER AB This study presents an evaluation and comparison of visible, near-infrared, passive and active microwave observations for vegetation characterization, on a global basis, for a year, with spatial resolution compatible with climatological studies. Visible and near-infrared observations along with the Normalized Difference Vegetation Index come from the Advanced Very High Resolution Radiometer. An atlas of monthly mean microwave land surface emissivities from 19 to 85 GHz has been calculated from the Special Sensor Microwave/Imager for a year, suppressing the atmospheric problems encountered with the use of simple channel combinations. The active microwave measurements are provided by the ERS-1 scatterometer at 5.25 GHz. The capacity to discriminate between vegetation types and to detect the vegetation phenology is assessed in the context of a vegetation classification obtained from in situ observations. A clustering technique derived from the Kohonen topological maps is used to merge the three data sets and interpret their relative variations. NDVI varies with vegetation density but is not very sensitive in semi-arid environments and in forested areas. Spurious seasonal cycles and large spatial variability in several areas suggest that atmospheric contamination and/or solar zenith angle drift still affect the NDVI. Passive and active microwave observations are sensitive to overall vegetation structure: they respond to absorption, emission, and scattering by vegetation elements, including woody parts. Backscattering coefficients from ERS-1 are not sensitive to atmospheric variations and exhibit good potential for vegetation discrimination with similar to 10 dB dynamic range between rain forest to and grassland. Passive microwave measurements also show some ability to characterize vegetation but are less sensitive than active measurements. However, passive observations show sensitivity to the underlying surface wetness that enables detection of wetlands even in densely vegetated areas. Merging the data sets using clustering techniques capitalizes on the complementary strengths of the instruments for vegetation discrimination and shows promising potential for land cover characterization on a global basis. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Prigent, C (reprint author), Observ Paris, Dept Radioastron Millimetr, 61 Ave Observ, F-75014 Paris, France. EM catherine.prigent@obspm.fr; faires@giss.nasa.gov; wrossow@giss.nasa.gov; ematthews@giss.nasa.gov RI Rossow, William/F-3138-2015 NR 67 TC 50 Z9 50 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 27 PY 2001 VL 106 IS D18 BP 20665 EP 20685 DI 10.1029/2000JD900801 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 476FV UT WOS:000171216300004 ER PT J AU Quinn, PK Coffman, DJ Bates, TS Miller, TL Johnson, JE Voss, K Welton, EJ Neususs, C AF Quinn, PK Coffman, DJ Bates, TS Miller, TL Johnson, JE Voss, K Welton, EJ Neususs, C TI Dominant aerosol chemical components and their contribution to extinction during the Aerosols99 cruise across the Atlantic SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MARINE BOUNDARY-LAYER; EXPERIMENT ACE 1; GLOBAL 3-DIMENSIONAL MODEL; LIGHT-SCATTERING; OPTICAL DEPTH; ATMOSPHERIC AEROSOLS; RADIATIVE PROPERTIES; STRONG ELECTROLYTES; PARTICULATE MATTER; AQUEOUS-SOLUTIONS AB The Aerosols99 cruise crossed the Atlantic Ocean from Norfolk, Virginia, to Cape Town, South Africa, during January and February of 1999. On the basis of back trajectories, aerosol number concentrations and size distributions, and trace gas concentrations, seven "air mass" regions were encountered. These included North America, Northern Hemisphere (NH) marine, African dust, a mixture of dust and biomass burning from Africa, biomass burning from Africa, Southern Hemisphere SH) marine tropics, and SH marine temperate. Simultaneous measurements of aerosol chemical composition, number size distribution, scattering and absorption coefficients, vertical profiles, and optical depth allowed for a thorough characterization of the aerosol. Presented here are the concentrations and mass fractions of the aerosol chemical components that were dominant in each region and the aerosol scattering and absorption coefficients, single scattering albedos, Angstrom ngstrom exponents, and optical depths measured in each region. Also presented is the percent of the extinction measured at the surface due to each chemical component and mass extinction efficiencies of the individual aerosol components estimated from Mie calculations and a multiple linear regression. All results are reported at the measurement relative humidity of 55 +/- 5%. Non-sea-salt (nss) SO aerosol was a significant contributor to the submicron mass concentration in all air mass regions (mean mass fractions ranged from 20 to 67%). It made the largest contribution to submicron extinction in the North America region (45 +/- 30%, mean and 1 sigma standard deviation). Sea-salt mean submicron mass fractions ranged from 9 to 49% with the lowest value in the biomass burning region and highest values in the NH marine and dust regions. Its contribution to submicron extinction ranged from a mean of 29 to 66%. Sea-salt mean supermicron mass fractions ranged from 52 to 98% with the highest values in the marine regions. Its contribution to supermicron extinction ranged from 60 to 98%. Mean submicron and supermicron mass fractions of dust in the dust region were 22 +/- 3.3% (mean and 95% uncertainty) and 26 +/- 3.9%, respectively. Corresponding submicron and supermicron extinction contributions were 24 +/- 7.5 and 18 +/- 4.0%, respectively. Submicron mass fractions of particulate organic matter (POM) ranged from below detection limits in the dust region to 18 +/- 11% in the biomass burning region. Contributions to submicron extinction ranged from below detection limits to 24% in the North America region. In the biomass burning region the black carbon mean submicron mass fraction was 6.7 +/- 1.3% with a contribution of 6.4 +/- 2.7% to the submicron extinction. Extinction fractions of each component for particles with aerodynamic diameters less than 10 mum also are reported in the paper. Sea salt dominated the extinction measured at the surface due to sub-10 mum aerosol for all air mass regions, even those influenced by continental sources. The fraction of the measured column aerosol optical depth due to aerosol within the 'boundary layer was estimated for the NH marine, dust, biomass burning, and SH marine tropics regions. Mean values ranged from 35 +/- 15% for the biomass burning region to 95 +/- 46% for the NH marine region. C1 NOAA, Pacific Marine Environm Lab, Seattle, WA 98115 USA. Univ Washington, Joint Inst Study Atmosphere & Oceans, Seattle, WA 98195 USA. Univ Miami, Dept Phys, Miami, FL 33149 USA. Univ Maryland, Goddard Earth Sci & Technol Ctr, Greenbelt, MD 20771 USA. Inst Tropospher Res, D-04318 Leipzig, Germany. RP Quinn, PK (reprint author), NOAA, Pacific Marine Environm Lab, 7600 Sand Point Way Ne, Seattle, WA 98115 USA. EM quinn@pmel.noaa.gov RI Welton, Ellsworth/A-8362-2012; Voss, Kenneth /A-5328-2013; Bates, Timothy/L-6080-2016; Quinn, Patricia/R-1493-2016 OI Voss, Kenneth /0000-0002-7860-5080; Quinn, Patricia/0000-0003-0337-4895 NR 61 TC 60 Z9 62 U1 0 U2 12 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 27 PY 2001 VL 106 IS D18 BP 20783 EP 20809 DI 10.1029/2000JD900577 PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 476FV UT WOS:000171216300013 ER PT J AU Voss, KJ Welton, EJ Quinn, PK Frouin, R Miller, M Reynolds, RM AF Voss, KJ Welton, EJ Quinn, PK Frouin, R Miller, M Reynolds, RM TI Aerosol optical depth measurements during the Aerosols99 experiment SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SHIPBOARD; TABLES; INDEX; OZONE; AIR AB The Aerosols99 cruise took place during the period from January 14 to February 8, 1999, on the R/V Ronald Brown. The cruise track was almost a straight line in the southeast direction from Norfolk, Virginia, to Cape Town, South Africa, and afforded the opportunity to sample several different aerosol regimes over the North and South Atlantic. Handheld sunphotometers, a shadowband radiometer (FRSR), and a LIDAR were used to measure the aerosol optical depth (AOD) during the cruise. The AOD and angstrom exponent a (spectral dependence of the AOD) varied strongly between regimes. Maritime regions typically had AOD (500 nm) of approximately 0.10 +/- 0.03, with a around 0.3 +/- 0.3. An African dust event was encountered in which the AOD (500 nm) averaged 0.29 +/- 0.05 with an alpha of 0.36 +/- 0.13. At the Intertropical Convergence Zone (ITCZ), no measurements were obtained because of cloudiness; however, after the ITCZ we encountered a biomass burning aerosol with high average AOD (500 nm) of 0.36 +/- 0.13, and a high alpha (0.88 +/- 0.30). Farther south the aerosol went back to the low levels of a typical marine aerosol. C1 Univ Miami, Dept Phys, Miami, FL 33146 USA. Univ Maryland, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21228 USA. NOAA, Pacific Marine Environm Lab, Seattle, WA 98115 USA. Univ Washington, Joint Inst Study Atmosphere & Oceans, Seattle, WA 98195 USA. Univ Calif San Diego, Inst Oceanog Sci, La Jolla, CA 92037 USA. Brookhaven Natl Lab, Dept Environm Sci, Upton, NY 11973 USA. RP Voss, KJ (reprint author), Univ Miami, Dept Phys, Miami, FL 33146 USA. EM voss@physics.miami.edu RI Welton, Ellsworth/A-8362-2012; Voss, Kenneth /A-5328-2013; Quinn, Patricia/R-1493-2016 OI Voss, Kenneth /0000-0002-7860-5080; Quinn, Patricia/0000-0003-0337-4895 NR 16 TC 20 Z9 21 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 27 PY 2001 VL 106 IS D18 BP 20811 EP 20819 DI 10.1029/2000JD900783 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 476FV UT WOS:000171216300014 ER PT J AU Voss, KJ Welton, EJ Quinn, PK Johnson, J Thompson, AM Gordon, HR AF Voss, KJ Welton, EJ Quinn, PK Johnson, J Thompson, AM Gordon, HR TI Lidar measurements during Aerosols99 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TO-BACKSCATTER RATIO; LIGHT-SCATTERING; OPTICAL-PROPERTIES; OCEAN COLOR AB The Aerosols99 cruise (January 14 to February 8, 1999) went between Norfolk, Virginia, and Cape Town, South Africa. A Micropulse lidar system was used almost continually during this cruise to profile the aerosol vertical structure. Inversions of this data illustrated a varying vertical structure depending on the dominant air mass. In clean maritime aerosols in the Northern and Southern Hemispheres the aerosols were capped at 1 km. When a dust event from Africa was encountered, the aerosol extinction increased its maximum height to above 2 km. During a period in which the air mass was dominated by biomass burning from southern Africa, the aerosol layer extended to 4 km. Comparisons of the aerosol optical depth (AOD) derived from lidar inversion and surface Sun photometers showed an agreement within +/-0.05 RMS. Similar comparisons between the extinction measured with a nephelometer and particle soot absorption photometer (at 19 m altitude) and the lowest lidar measurement (75 m) showed good agreement (+/-0.014 km(-1)). The lidar underestimated surface extinction during periods when an elevated aerosol layer (total AOD > 0.10) was present over a relatively clean (aerosol extinction < 0.05 km(-1)) surface layer, but otherwise gave accurate results. C1 Univ Miami, Dept Phys, Coral Gables, FL 33124 USA. Univ Maryland Baltimore Cty, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21250 USA. NOAA, Pacific Marine Environm Lab, Seattle, WA 98115 USA. Univ Washington, Joint Inst Study Atmosphere & Oceans, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Greenbelt, MD 20771 USA. RP Voss, KJ (reprint author), Univ Miami, Dept Phys, Coral Gables, FL 33124 USA. EM voss@physics.miami.edu RI Welton, Ellsworth/A-8362-2012; Voss, Kenneth /A-5328-2013; Quinn, Patricia/R-1493-2016; Thompson, Anne /C-3649-2014 OI Voss, Kenneth /0000-0002-7860-5080; Quinn, Patricia/0000-0003-0337-4895; Thompson, Anne /0000-0002-7829-0920 NR 22 TC 40 Z9 45 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 SEP 27 PY 2001 VL 106 IS D18 BP 20821 EP 20831 DI 10.1029/2001JD900217 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 476FV UT WOS:000171216300015 ER PT J AU Rinsland, CP Meier, A Griffith, DWT Chiou, LS AF Rinsland, CP Meier, A Griffith, DWT Chiou, LS TI Ground-based measurements of tropospheric CO, C2H6, and HCN from Australia at 34 degrees S latitude during 1997-1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PACIFIC EXPLORATORY MISSION; INFRARED SPECTROSCOPIC MEASUREMENTS; HYDROGEN-CYANIDE HCN; CARBON-MONOXIDE; PEM-TROPICS; SEASONAL-VARIATIONS; ATMOSPHERIC CHEMISTRY; VERTICAL-DISTRIBUTION; SOUTH ATLANTIC; METHYL HALIDES AB High spectral resolution (0.004 cm(-1)) infrared solar absorption measurements Of CO, C2H6, and HCN have been recorded with the Fourier transform spectrometer located at the Network for the Detection of Stratospheric Change complementary station at the University of Wollongong, Australia (34.45 degreesS, 150.88 degreesE, 30 m above sea level). The time series covers March 1997 to February 1998. Profile retrievals with maximum sensitivity in the upper troposphere show distinct seasonal cycles for all three molecules with maxima during October-December 1997. Best fits to the time series of daily averages yield peak 0.03-14 km columns (molecules cm(-2)) of 1.54 X 10(18) for CO, 8.56 X 10(15) for C2H6, and 6.56 X 10(15) for HCN during austral spring. Mixing ratio profiles of all three molecules during this time show maxima in the upper troposphere. Isentropic back trajectories suggest the elevated CO, C2H6, and HCN columns above Wollongong originated from southern Africa or South America with no significant contribution from the intense tropical Asian emissions during the strong El Nino event of 1997-1998. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Wollongong, Dept Chem, Wollongong, NSW 2522, Australia. Wyle Labs, Hampton, VA 23666 USA. RP Rinsland, CP (reprint author), NASA, Langley Res Ctr, Mail Stop 401A, Hampton, VA 23681 USA. EM c.p.rinsland@larc.nasa.gov; arndt@uow.edu.au; david_griffith@uow.edu.au; chioul@scatmos.larc.nasa.gov NR 61 TC 30 Z9 30 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 SEP 27 PY 2001 VL 106 IS D18 BP 20913 EP 20924 DI 10.1029/2000JD000318 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 476FV UT WOS:000171216300022 ER PT J AU Veverka, J Farquhar, B Robinson, M Thomas, P Murchie, S Harch, A Antreasian, PG Chesley, SR Miller, JK Owen, WM Williams, BG Yeomans, D Dunham, D Heyler, G Holdridge, M Nelson, RL Whittenburg, KE Ray, JC Carcich, B Cheng, A Chapmank, C Bell, JF Bell, M Bussey, B Clark, B Domingue, D Gaffey, MJ Hawkins, E Izenberg, N Joseph, J Kirk, R Lucey, P Malin, M McFadden, L Merline, WJ Peterson, C Prockter, L Warren, J Wellnitz, D AF Veverka, J Farquhar, B Robinson, M Thomas, P Murchie, S Harch, A Antreasian, PG Chesley, SR Miller, JK Owen, WM Williams, BG Yeomans, D Dunham, D Heyler, G Holdridge, M Nelson, RL Whittenburg, KE Ray, JC Carcich, B Cheng, A Chapmank, C Bell, JF Bell, M Bussey, B Clark, B Domingue, D Gaffey, MJ Hawkins, E Izenberg, N Joseph, J Kirk, R Lucey, P Malin, M McFadden, L Merline, WJ Peterson, C Prockter, L Warren, J Wellnitz, D TI The landing of the NEAR-Shoemaker spacecraft on asteroid 433 Eros SO NATURE LA English DT Article ID EJECTA BLOCKS; 243-IDA AB The NEAR-Shoemaker spacecraft was designed to provide a comprehensive characterization of the S-type asteroid 433 Eros (refs 1-3), an irregularly shaped body with approximate dimensions of 34x13x13 km. Following the completion of its yearlong investigation, the mission was terminated with a controlled descent to its surface, in order to provide extremely high resolution images. Here we report the results of the descent on 12 February 2001, during which 70 images were obtained. The landing area is marked by a paucity of small craters and an abundance of 'ejecta blocks'. The properties and distribution of ejecta blocks are discussed in a companion paper(4). The last sequence of images reveals a transition from the blocky surface to a smooth area, which we interpret as a 'pond'. Properties of the 'ponds' are discussed in a second companion paper(5). The closest image, from an altitude of 129 m, shows the interior of a 100-m-diameter crater at 1-cm resolution. C1 Cornell Univ, Ithaca, NY 14853 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Northwestern Univ, Dept Geol Sci, Evanston, IL 60208 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. SW Res Inst, Boulder, CO 80302 USA. Rensselaer Polytech Inst, Ctr Sci, Dept Earth & Environm Sci, Troy, NY 12180 USA. US Geol Survey, Flagstaff, AZ 86001 USA. Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Malin Space Sci Syst Inc, San Diego, CA 92191 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Veverka, J (reprint author), Cornell Univ, Space Sci Bldg, Ithaca, NY 14853 USA. RI Wellnitz, Dennis/B-4080-2012; McFadden, Lucy-Ann/I-4902-2013; Murchie, Scott/E-8030-2015; Izenberg, Noam/F-3952-2015 OI McFadden, Lucy-Ann/0000-0002-0537-9975; Murchie, Scott/0000-0002-1616-8751; Izenberg, Noam/0000-0003-1629-6478 NR 14 TC 76 Z9 78 U1 1 U2 6 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD SEP 27 PY 2001 VL 413 IS 6854 BP 390 EP 393 DI 10.1038/35096507 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 475UY UT WOS:000171188700045 PM 11574879 ER PT J AU Goldstein, ME AF Goldstein, ME TI An exact form of Lilley's equation with a velocity quadrupole/temperature dipole source term SO JOURNAL OF FLUID MECHANICS LA English DT Article AB There have been several attempts to introduce approximations into the exact form of Lilley's equation in order to express the source term as the sum of a quadrupole whose strength is quadratic in the fluctuating velocities and a dipole whose strength is proportional to the temperature fluctuations. The purpose of this note is to show that it is possible to choose the dependent (i.e. the pressure) variable so that this type of result can be derived directly from the Euler equations without introducing any additional approximations. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Goldstein, ME (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 12 TC 46 Z9 48 U1 0 U2 1 PU CAMBRIDGE UNIV PRESS PI PORT CHESTER PA 110 MIDLAND AVE, PORT CHESTER, NY 10573-9863 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD SEP 25 PY 2001 VL 443 BP 231 EP 236 PG 6 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 479UM UT WOS:000171422000008 ER PT J AU Killen, RM Potter, AE Reiff, P Sarantos, M Jackson, BV Hick, P Giles, B AF Killen, RM Potter, AE Reiff, P Sarantos, M Jackson, BV Hick, P Giles, B TI Evidence for space weather at Mercury SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID LUNAR SODIUM ATMOSPHERE; LEONID METEOR-SHOWER; INTERPLANETARY SCINTILLATION OBSERVATIONS; POTASSIUM ATMOSPHERES; SPATIAL-DISTRIBUTION; MAGNETOSPHERE; SURFACE; MOON; EXOSPHERE; DISCOVERY AB Mercury's sodium atmosphere is known to be highly variable both temporally and spatially. During a week-long period from November 13 to 20, 1997, the total sodium content of the Hermean atmosphere increased by a factor of 3, and the distribution varied daily. We demonstrate a mechanism whereby these rapid variations could be due to solar wind-magnetosphere interactions. We assume that photon-stimulated desorption and meteoritic vaporization are the active source processes on the first (quietest) day of our observations. Increased ion sputtering results whenever the magnetosphere opens in response to a southward interplanetary magnetic field (IMF) or unusually large solar wind dynamic pressure. The solar wind dynamic pressure at Mercury as inferred by heliospheric radial tomography increased by a factor of 20 during this week, while the solar EUV flux measured by the Solar EUV Monitor (SEM) instrument on board the Solar and Heliospheric Observatory (SOHO) increased by 20%. While impact vaporization provides roughly 25% of the source, it is uniformly distributed and varies very little during the week. The variations seen in our data are not related to Caloris basin, which remained in the field of view during the entire week of observations. We conclude that increased ion sputtering resulting from ions entering the cusp regions is the probable mechanism leading to large rapid increases in the sodium content of the exosphere. While both the magnitude and distribution of the observed sodium can be reproduced by our model, in situ measurements of the solar wind density and velocity, the magnitude and direction of the interplanetary magnetic field, and Mercury's magnetic moments are required to confirm the results. C1 SW Res Inst, San Antonio, TX 78228 USA. Natl Solar Observ, Tucson, AZ 85719 USA. Rice Univ, Dept Astron & Space Sci, Houston, TX 77005 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. NASA, Goddard Space Flight Ctr, Interplanetary Phys Branch, Greenbelt, MD 20771 USA. RP Killen, RM (reprint author), SW Res Inst, 6220 Culebra Rd,PO Drawer 28510, San Antonio, TX 78228 USA. RI Sarantos, Menelaos/H-8136-2013; Reiff, Patricia/D-2564-2014 OI Reiff, Patricia/0000-0002-8043-5682 NR 72 TC 107 Z9 107 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 2001 VL 106 IS E9 BP 20509 EP 20525 DI 10.1029/2000JE001401 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 474HH UT WOS:000171099900001 ER PT J AU Hort, M Weitz, CM AF Hort, M Weitz, CM TI Theoretical modeling of eruption plumes on Mars under current and past climates SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID EXPLOSIVE VOLCANIC-ERUPTIONS; MARTIAN VOLCANOS; VALLES-MARINERIS; HELLAS REGION; ALBA-PATERA; MAGMA; WATER; EVOLUTION; DEPOSITS; GEOLOGY AB We have used a combined conduit transport/eruption column model to explore the evolution of volcanic eruption plumes on Mars under different atmospheric conditions. In the calculations we consider a volatile phase composed of H2O, CO2, and SO2 and take into account that the magmatic water erupted at the vent may condense as the eruption column rises into the Martian atmosphere. As two end-member models, we explore the eruption of rhyolitic and basaltic melt compositions containing different amounts of volatiles as well as having different eruption temperatures. Under current Martian atmospheric conditions eruption plumes are found to rise as high as 100 km for a mass eruption rate of 5 x 10(7) kg s(-1), which is consistent with model calculations by Wilson and Head [1994]. In contrast, under a dense atmosphere (10(5) Pa on the Martian surface) which may have existed earlier in Martian history, the same eruption plume reaches only about 25 km height. All magmatic water released during the eruption is found to freeze as it rises in the eruption column, which means that fallout from the plume will contain water ice which call be subsequently deposited ill near surface layers. This ice may then suddenly melt due to higher surface heat flow or shallow intrusions leading to rapid release of water oil the flanks of volcanoes. Only if the atmosphere were hotter ill the past could the water in the eruption plume condense and produce rain rather than ice. Furthermore, the calculations show that smaller micron-size particles would be distributed globally from eruption plumes under current Martian conditions but would not have been as widely dispersed from plumes erupted into an earlier dense atmosphere. C1 GEOMAR Forchungszentrum, Abt Vulanol & Petrol, D-24148 Kiel, Germany. NASA, Off Space Sci, Washington, DC 20546 USA. RP Hort, M (reprint author), GEOMAR Forchungszentrum, Abt Vulanol & Petrol, Wischhofstr 1-3, D-24148 Kiel, Germany. NR 66 TC 12 Z9 12 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 2001 VL 106 IS E9 BP 20547 EP 20562 DI 10.1029/2000JE001293 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 474HH UT WOS:000171099900003 ER PT J AU Anderson, RC Dohm, JM Golombek, MP Haldemann, AFC Franklin, BJ Tanaka, KL Lias, J Peer, B AF Anderson, RC Dohm, JM Golombek, MP Haldemann, AFC Franklin, BJ Tanaka, KL Lias, J Peer, B TI Primary centers and secondary concentrations of tectonic activity through time in the western hemisphere of Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID THARSIS REGION; VALLES MARINERIS; ORIENTATION DATA; ORIGIN; PROVINCE; TOPOGRAPHY; THAUMASIA; EVOLUTION; TROUGHS; HISTORY AB Five main stages of radial and concentric structures formed around Tharsis from the Noachian through the Amazonian as determined by geologic mapping of 24,452 structures within the stratigraphic framework of Mars and by testing their radial and concentric orientations. Tectonic activity peaked in the Noachian (stage 1) around the largest center, Claritas, an elongate center extending more than 20 degrees in latitude and defined by about half of the total grabens which are concentrated in the Syria Planum, Thaumasia, and Tempe Terra regions. During the Late Noachian and Early Hesperian (stage 2), extensional structures formed along the length of present-day Valles Marineris and in Thaumasia (with a secondary concentration near Warrego Vallis) radial to a region just to the south of the central margin of Valles Marineris. Early Hesperian (stage 3) radial grabens in Pavonis, Syria, Ulysses, and Tempe Terra and somewhat concentric wrinkle ridges in Lunae and Solis Plana and in Thaumasia, Sirenum, Memnonia, and Amazonis are centered northwest of Syria with secondary centers at Thaumasia, Tempe Terra, Ulysses Fossae, and western Valles Marineris. Late Hesperian/Early Amazonian (stage 4) structures around Alba Patera, the northeast trending alignment of Tharsis Montes, and Olympus Mons appears centered on Alba Patera. Stage 5 structures (Middle-Late Amazonian) represent the last pulse of Tharsis-related activity and are found around the large shield volcanoes and are centered near Pavonis Mons. Tectonic activity around Tharsis began in the Noachian and generally decreased through geologic time to the Amazonian. Statistically significant radial distributions of structures formed during each stage, centered at different locations within the higher elevations of Tharsis. Secondary centers of radial structures during many of the stages appear related to previously identified local magmatic centers that formed at different times and locations throughout Tharsis. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Dept Hydrol & Water Resources, Tucson, AZ 85721 USA. US Geol Survey, Astrogeol Team, Flagstaff, AZ 86001 USA. Univ Pittsburgh, Dept Geol & Planetary Sci, Pittsburgh, PA 15260 USA. RP Anderson, RC (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM R.C.Anderson@jpl.nasa.gov; jmd@hwr.arizona.edu; M.P.Golombek@jpl.nasa.gov; A.F.C.Haldemann@jpl.nasa.gov; B.J.Franklin@jpl.nasa.gov; ktanaka@usgs.gov; juan_lias@urscorp.com RI Dohm, James/A-3831-2014 NR 51 TC 163 Z9 164 U1 3 U2 10 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 SEP 25 PY 2001 VL 106 IS E9 BP 20563 EP 20585 DI 10.1029/2000JE001278 PG 23 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 474HH UT WOS:000171099900004 ER PT J AU Ibanez, J Leon, R Vu, DT Chaparro, S Johnson, SR Navarro, C Zhang, YH AF Ibanez, J Leon, R Vu, DT Chaparro, S Johnson, SR Navarro, C Zhang, YH TI Tunneling carrier escape from InAs self-assembled quantum dots SO APPLIED PHYSICS LETTERS LA English DT Article ID LEVEL TRANSIENT SPECTROSCOPY; ELECTRONIC-STRUCTURE; TRAPS; GAAS AB Deep-level transient spectroscopy measurements in InAs quantum dots (QDs) grown in both n-GaAs and p-GaAs show that tunneling is an important mechanism of carrier escape from the dots. The doping level in the barrier strongly affects the tunneling emission rates, enabling or preventing the detection of a transient capacitance signal from a given QD level. The relative intensity of this signal acquired with different rate windows allows the estimation of tunneling emission energies. (C) 2001 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Arizona State Univ, Ctr Solid State Elect Res, Tempe, AZ 85287 USA. RP Ibanez, J (reprint author), CSIC, Inst Jaume Almera, Barcelona, Spain. RI Ibanez-Insa, Jordi/F-6995-2014 OI Ibanez-Insa, Jordi/0000-0002-8909-6541 NR 15 TC 22 Z9 22 U1 0 U2 5 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 SEP 24 PY 2001 VL 79 IS 13 BP 2013 EP 2015 PG 3 WC Physics, Applied SC Physics GA 472ZQ UT WOS:000171015200028 ER PT J AU Gershenson, ME Gong, D Sato, T Karasik, BS Sergeev, AV AF Gershenson, ME Gong, D Sato, T Karasik, BS Sergeev, AV TI Millisecond electron-phonon relaxation in ultrathin disordered metal films at millikelvin temperatures SO APPLIED PHYSICS LETTERS LA English DT Article ID DIRECT DETECTOR; RESISTIVITY; MICROBOLOMETER; BOLOMETER AB We have measured directly the thermal conductance between electrons and phonons in ultrathin Hf and Ti films at millikelvin temperatures. The experimental data indicate that electron-phonon coupling in these films is significantly suppressed by disorder. The electron cooling time tau (epsilon) follows the T-4 dependence with a record-long value tau (epsilon)=25 ms at T=0.04 K. The hot-electron detectors of far-infrared radiation, fabricated from such films, are expected to have a very high sensitivity. The noise-equivalent power of a detector with the area 1 mum(2) and the noise limited by fluctuations of the temperature are expected to be (2-3)x10(-20) W/root Hz, which is two orders of magnitude smaller than that of the state-of-the-art bolometers. (C) 2001 American Institute of Physics. C1 Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08854 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Wayne State Univ, Dept Elect & Comp Engn, Detroit, MI 48202 USA. RP Gershenson, ME (reprint author), Rutgers State Univ, Dept Phys & Astron, POB 849, Piscataway, NJ 08854 USA. OI Gong, Donglai/0000-0002-1697-1739 NR 23 TC 51 Z9 51 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD SEP 24 PY 2001 VL 79 IS 13 BP 2049 EP 2051 DI 10.1063/1.1407302 PG 3 WC Physics, Applied SC Physics GA 472ZQ UT WOS:000171015200040 ER PT J AU Bose, D Hash, D Govindan, TR Meyyappan, M AF Bose, D Hash, D Govindan, TR Meyyappan, M TI Modelling of inductively coupled plasma processing reactors SO JOURNAL OF PHYSICS D-APPLIED PHYSICS LA English DT Article; Proceedings Paper CT Conference on the Future of Technological Plasmas CY MAR 19-21, 2001 CL BRIGHTON, ENGLAND ID REFERENCE CELL; SIMULATION AB A comprehensive model has been developed to study low-pressure, high-density plasma processing reactors. The model couples plasma generation and transport self-consistently to fluid flow and gas energy equations. The model and the simulation software have been used to analyse chlorine plasmas used in metal etching. The effect of the inductive coil frequency on the plasma characteristics has been examined and found to influence plasma uniformity only moderately. Model predictions for a CF4 plasma have been found to agree well with experimental results. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bose, D (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 16 TC 16 Z9 16 U1 1 U2 5 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0022-3727 J9 J PHYS D APPL PHYS JI J. Phys. D-Appl. Phys. PD SEP 21 PY 2001 VL 34 IS 18 BP 2742 EP 2747 DI 10.1088/0022-3727/34/18/305 PG 6 WC Physics, Applied SC Physics GA 484DK UT WOS:000171674800008 ER PT J AU O'Brien, K Horne, K Boroson, B Still, M Gomer, R Oke, JB Boyd, P Vrtilek, SD AF O'Brien, K Horne, K Boroson, B Still, M Gomer, R Oke, JB Boyd, P Vrtilek, SD TI Keck II spectroscopy of mHz quasi-periodic oscillations in Hercules X-1 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; binaries : close; stars : individual : Hercules X-1 stars : oscillations; X-rays : stars ID X-RAY BINARIES; 35 DAY CYCLE; ACCRETION DISCS; HERCULIS X-1; 4U 1626-67; LOW STATE; DISCOVERY; UHURU; MASS AB We present Keck II spectroscopy of optical mHz quasi-periodic oscillations (QPOs) in the light curve of the X-ray pulsar binary Hercules X-1. In the power spectrum it appears as 'peaked noise', with a coherency similar to2, a central frequency of 35 mHz and a peak-to-peak amplitude of 5 per cent. However, the dynamic power spectrum shows it to be an intermittent QPO, with a lifetime of similar to 100 s, as expected if the lifetime of the orbiting material is equal to the thermal time-scale of the inner disc. We have decomposed the spectral time series into constant and variable components and used blackbody fits to the resulting spectra to characterize the spectrum of the QPO variability and constrain possible production sites. We find that the spectrum of the QPO is best fitted by a small hot region, possibly the inner regions of the accretion disc, where the ballistic accretion stream impacts on to the disc. The lack of any excess power around the QPO frequency in the X-ray power spectrum, created using simultaneous light curves from RXTE, implies that the QPO is not simply reprocessed X-ray variability. C1 Univ St Andrews, Sch Phys & Astron, St Andrews KY16 9SS, Fife, Scotland. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Rice Univ, Howard Hughes Med Inst, Houston, TX 77005 USA. Rice Univ, Dept Biochem & Cell Biol, Houston, TX 77005 USA. CALTECH, Pasadena, CA 91125 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP O'Brien, K (reprint author), Univ St Andrews, Sch Phys & Astron, St Andrews KY16 9SS, Fife, Scotland. EM kso@astro.uva.nl RI Boyd, Patricia/D-3274-2012 NR 26 TC 6 Z9 6 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD SEP 21 PY 2001 VL 326 IS 3 BP 1067 EP 1075 DI 10.1046/j.1365-8711.2001.04651.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 477YP UT WOS:000171314400024 ER PT J AU Worrall, DM Birkinshaw, M Hardcastle, MJ Lawrence, CR AF Worrall, DM Birkinshaw, M Hardcastle, MJ Lawrence, CR TI Chandra measurements of the X-ray core and cluster of 3C 220.1 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE radiation mechanisms : non-thermal; galaxies : active; galaxies : clusters : individual : 3C 220.1; galaxies : individual : 3C 220.1; X-rays : galaxies ID POWERFUL RADIO GALAXIES; EMISSION; QUASARS; CYGNUS AB We report results of an 18-ks exposure with the ACIS instrument on Chandra of the powerful z = 0.62 radio galaxy 3C 220.1. The X-ray emission separates into cluster gas of emission-weighted kT similar to 5 keV, 0.7-12 keV luminosity (to a radius of 45 arcsec) of 5.6 x 10(44) erg s(-1) and unresolved emission (coincident with the radio core). while the extended X-ray emission is clearly thermal in nature, a straightforward cooling-flow model, even in conjunction with a point-source component, is a poor fit to the radial profile of the X-ray emission. This is despite the fact that the measured properties of the gas suggest a massive cooling flow of similar to 130 M-. yr(-1), and the data show weak evidence for a temperature gradient. The central unresolved X-ray emission has a power-law spectral energy index alpha similar to 0.7 and 0.7-12 keV luminosity of 10(45) erg s(-1), and any intrinsic absorption is relatively small. The two-point spectrum of the core emission between radio and X-ray energies has alpha (rx) = 0.75. Since this is a flatter spectrum than seen in other sources where the X-ray emission is presumed to be radio-related, regions close to the active galactic nucleus (AGN) in this source may dominate the central X-ray output, as is believed to be the case for lobe-dominated quasars. Simple unification models would be challenged if this were found to be the case for a large fraction of high-power radio galaxies. C1 Univ Bristol, Dept Phys, Bristol BS8 1TL, Avon, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Worrall, DM (reprint author), Univ Bristol, Dept Phys, Bristol BS8 1TL, Avon, England. RI Hardcastle, Martin/E-2264-2012 OI Hardcastle, Martin/0000-0003-4223-1117 NR 22 TC 32 Z9 32 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 SEP 21 PY 2001 VL 326 IS 3 BP 1127 EP 1133 DI 10.1046/j.1365-8711.2001.04644.x PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 477YP UT WOS:000171314400031 ER PT J AU Branchini, E Freudling, W Da Costa, LN Frenk, CS Giovanelli, R Haynes, MP Salzer, JJ Wegner, G Zehavi, I AF Branchini, E Freudling, W Da Costa, LN Frenk, CS Giovanelli, R Haynes, MP Salzer, JJ Wegner, G Zehavi, I TI Comparing the SFI peculiar velocities with the PSCz gravity field: a VELMOD analysis SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : clusters : general; galaxies : distances and redshifts; cosmology : observations; cosmology : theory; large-scale structure of Universe ID TULLY-FISHER RELATION; CATALOG-REDSHIFT-SURVEY; SCALE POWER SPECTRUM; DENSITY FIELDS; LIKELIHOOD ANALYSIS; SAMPLE SELECTION; NEARBY GALAXIES; SC GALAXIES; LOCAL-GROUP; JY SURVEY AB We compare the peculiar velocities derived from the I-band Tully-Fisher (TF) relation for 989 field spiral galaxies in the SFI catalogue with the predicted velocity field derived from the IRAS PSCz galaxy redshift survey. We assume linear gravitational instability theory and apply the maximum likelihood technique, VELMOD to SFI galaxies within a redshift cz(LG) = 6000 km s(-1). The resulting calibration of the TF relation is consistent with a previous, independent calibration for a similar sample of spirals residing in clusters. Our analysis provides an accurate estimate of the quantity beta (1) = Omega (0.6)(m)/b(1), where b(1) is the linear biasing parameter for IRAS galaxies. Using the forward TF relation and smoothing the predicted velocity field with a Gaussian filter of radius 300 km s(-1), we obtain beta (1) = 0.42 +/- 0.04 (1 sigma, uncertainty). This value, as well as other parameters in the fit, are robust to varying the smoothing radius to 500 km s(-1) and splitting the sample into spherical shells in redshift space. The one exception is the small-scale velocity dispersion, sigma (v), which varies from similar to 200 km s(-1) (within cz(LG) = 4000 km s(-1)) to similar to 500 km s(-1) at larger distance. For beta (1) similar or equal to 0.42, the residuals between the TF data and the PSCz gravity field are uncorrelated, indicating that the model provides a good fit to the data. More generally, a chi (2) statistic indicates that the PSCz model velocity field provides an acceptable (3 sigma) fit to the data for 0.3 < (1) < 0.5. C1 Univ Groningen, Kapteyn Inst, NL-9700 Groningen, Netherlands. Univ Roma Tre, Dipartimento Fis, I-00146 Rome, Italy. Space Telescope European Coordinating Facil, D-85748 Garching, Germany. European So Observ, D-85748 Garching, Germany. Univ Durham, Dept Phys, Durham DH1 3LE, England. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Ithaca, NY 14853 USA. Wesleyan Univ, Dept Astron, Middletown, CT 06457 USA. Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Grp, Batavia, IL 60510 USA. RP Branchini, E (reprint author), Univ Groningen, Kapteyn Inst, Landleven 12,POB 800, NL-9700 Groningen, Netherlands. OI Branchini, Enzo/0000-0002-0808-6908 NR 51 TC 31 Z9 31 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 SEP 21 PY 2001 VL 326 IS 3 BP 1191 EP 1204 DI 10.1046/j.1365-8711.2001.04671.x PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 477YP UT WOS:000171314400037 ER PT J AU McClanahan, TP Trombka, JI Nittler, LR Boynton, WV Bruckner, J Squyres, SW Evans, LG Bhangoo, JS Clark, PE Floyd, SR McCartney, E Mikheeva, I Starr, RD AF McClanahan, TP Trombka, JI Nittler, LR Boynton, WV Bruckner, J Squyres, SW Evans, LG Bhangoo, JS Clark, PE Floyd, SR McCartney, E Mikheeva, I Starr, RD TI Spectral analysis and compositing techniques for the Near Earth Asteroid Rendezvous (NEAR Shoemaker), X-ray and Gamma-Ray Spectrometers (XGRS) SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT Imaging 2000 Conference CY JUN 27-JUL 01, 2000 CL STOCKHOLM, SWEDEN SP Nobel Inst Phys, ACREO, Detect Technol Inc, MAMEA Imaging AB, Pixel Vis Technol Inc, Sectra AB, SINTEF Electr & Cybernet AB An X-ray and Gamma-Ray Spectrometer (XGRS) is on board the Near Earth Asteroid Rendezvous (NEAR) spacecraft to determine the elemental composition of the surface of the asteroid 433 Eros. The Eros asteroid is highly oblate and irregular in shape. As a result, analysis methodologies are in many ways a divergence from comparable techniques. Complex temporal, spatial and instrument performance relationships must be accounted for during the analysis process. Field of view and asteroid surface geometry measurements must be modeled and then combined with real measurements of solar, spectral and instrument calibration information to derive scientific results. NEAR is currently orbiting 433 Eros and is in the initial phases of its primary data integration and mapping phases. Initial results have been obtained and bulk chemistry assessments have been obtained through specialized background assessment and data reduction techniques. (C) 2001 Published by Elsevier Science B.V. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Comp Sci Corp, Syst Sci Div, Laurel, MD 20707 USA. Cornell Univ, Ithaca, NY 14853 USA. Max Planck Inst Chem, D-55020 Mainz, Germany. Univ Arizona, Dept Planetary Sci, Tucson, AZ 85721 USA. RP McClanahan, TP (reprint author), NASA, Goddard Space Flight Ctr, Blg 2,Room S101,Code 691, Greenbelt, MD 20771 USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD SEP 21 PY 2001 VL 471 IS 1-2 BP 179 EP 183 DI 10.1016/S0168-9002(01)00995-0 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 476BN UT WOS:000171206500035 ER PT J AU Hiroi, T Zolensky, ME Pieters, CM AF Hiroi, T Zolensky, ME Pieters, CM TI The Tagish Lake meteorite: A possible sample from a D-type asteroid SO SCIENCE LA English DT Article ID MAIN-BELT; BODIES; VESTA AB A new type of carbonaceous chondrite, the Tagish Lake meteorite, exhibits a reflectance spectrum similar to spectra observed from the D-type asteroids, which are relatively abundant in the outer solar system beyond the main asteroid belt and have been inferred to be more primitive than any known meteorite. Until the Tagish Lake fait, these asteroids had no analog in the meteorite collections. The Tagish Lake meteorite is a carbon-rich (4 to 5 weight %), aqueously altered carbonaceous chondrite and contains high concentrations of presolar grains and carbonate minerals, which is consistent with the expectation that the D-type asteroids were originally made of primitive materials and did not experience any extensive heating. C1 Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. NASA, Earth Sci & Solar Syst Explorat Div, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Hiroi, T (reprint author), Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. NR 19 TC 91 Z9 91 U1 0 U2 9 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD SEP 21 PY 2001 VL 293 IS 5538 BP 2234 EP 2236 DI 10.1126/science.1063734 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 475AL UT WOS:000171139400037 PM 11520950 ER PT J AU Pizzarello, S Huang, YS Becker, L Poreda, RJ Nieman, RA Cooper, G Williams, M AF Pizzarello, S Huang, YS Becker, L Poreda, RJ Nieman, RA Cooper, G Williams, M TI The organic content of the Tagish Lake meteorite SO SCIENCE LA English DT Article ID MURCHISON METEORITE; CARBONACEOUS CHONDRITE; C-13 NMR; ACIDS; HYDROCARBONS; DERIVATIVES; MATTER AB The Tagish Lake meteorite felt last year on a frozen take in Canada and may provide the most pristine material of its kind. Analyses have now shown this carbonaceous chondrite to contain a suite of soluble organic compounds (similar to 100 parts per million) that includes mono- and dicarboxylic acids, dicarboximides, pyridine carboxylic acids, a sulfonic acid, and both aliphatic and aromatic hydrocarbons. The insoluble carbon exhibits exclusive aromatic character, deuterium enrichment, and fullerenes containing "planetary" helium and argon. The findings provide insight into an outcome of early solar chemical evolution that differs from any seen so far in meteorites. C1 Arizona State Univ, Dept Chem & Biochem, Tempe, AZ 85287 USA. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. Univ Calif Santa Barbara, Inst Crustal Studies, Santa Barbara, CA 93106 USA. Univ Rochester, Dept Earth & Environm Sci, Rochester, NY 14627 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Pizzarello, S (reprint author), Arizona State Univ, Dept Chem & Biochem, Tempe, AZ 85287 USA. NR 20 TC 131 Z9 134 U1 7 U2 23 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 SEP 21 PY 2001 VL 293 IS 5538 BP 2236 EP 2239 DI 10.1126/science.1062614 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 475AL UT WOS:000171139400038 PM 11520948 ER PT J AU Srivastava, V Rothermel, J Clarke, AD Spinhirne, JD Menzies, RT Cutten, DR Jarzembski, MA Bowdle, DA McCaul, EW AF Srivastava, V Rothermel, J Clarke, AD Spinhirne, JD Menzies, RT Cutten, DR Jarzembski, MA Bowdle, DA McCaul, EW TI Wavelength dependence of backscatter by use of aerosol microphysics and lidar data sets: application to 2.1-mu m wavelength for space-based and airborne lidars SO APPLIED OPTICS LA English DT Article ID MODELED BACKSCATTER; BACKGROUND MODE; CO2 LIDAR; MU M; PACIFIC; CALIBRATION; PROFILES; 9.1-MU-M AB An aerosol microphysics dataset was used to model backscatter in the 0.35-11-mum wavelength range, with the results validated by comparison with measured cw and pulsed lidar backscatter obtained during two NASA-sponsored airborne field experiments. Different atmospheric features were encountered, with aerosol backscatter ranging over 4 orders of magnitude. Modeled conversion functions were used to convert existing lidar backscatter datasets to 2.1 mum. Resulting statistical distribution shows the midtropospheric aerosol backscatter background mode of beta (2.1) to be between similar to3.0 x 10(-10) and similar to1.3 x 10(-9) m(-1) sr(-1), similar to 10-20 times higher than that for beta (9.1) and a beta (2.1) boundary layer mode of similar to1.0 x 10(-7) to similar to1.3 x 10(-6) m(-1) sr(-1), similar to3-5 times higher than beta (9.1). (C) 2001 Optical Society of America. C1 Global Hydrol & Climate Ctr, Huntsville, AL 35805 USA. Univ Alabama, Huntsville, AL 35899 USA. Univ Hawaii, Sch Oceanog, Honolulu, HI 96822 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Srivastava, V (reprint author), Global Hydrol & Climate Ctr, 320 Sparkman Dr NW, Huntsville, AL 35805 USA. EM vandana@msfc.nasa.gov NR 23 TC 12 Z9 13 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 SEP 20 PY 2001 VL 40 IS 27 BP 4759 EP 4769 DI 10.1364/AO.40.004759 PG 11 WC Optics SC Optics GA 473EY UT WOS:000171028400001 PM 18360517 ER PT J AU Wang, MH Bailey, SW AF Wang, MH Bailey, SW TI Correction of sun glint contamination on the SeaWiFS ocean and atmosphere products SO APPLIED OPTICS LA English DT Article ID WATER-LEAVING RADIANCE; SPECTRAL REFLECTANCE; COLOR SENSORS; DIFFUSE TRANSMITTANCE; WHITECAPS; ALGORITHM AB For remote sensing of the ocean and atmosphere optical properties, the measurement of radiances affected by sun glint has to be avoided and/or masked out. There are usually no meaningful retrievals in regions significantly contaminated by sun glint, The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) is capable of operationally tilting the sensor 20 degrees away from nadir to minimize sun glint contamination. The sun glint mask is computed from the Cox and Munk model [J. Opt. Soc. Am. 44, 838-850 (1954)] and applied to the SeaWiFS data. However, sun glint is still a factor near the subsolar point. We present results that demonstrate the effect of sun glint contamination on retrievals of ocean bio-optical and atmospheric products. We show that, although sun glint contamination has a minor effect on retrieved ocean color products, the effect on retrieved atmospheric products, e.g., aerosol optical thickness, is significant. We describe a sun glint correction scheme implemented in the SeaWiFS data-processing system and compare the results with and without sun glint correction. With sun glint correction the derived ocean and atmospheric products are improved. Also, the sun glint masked area can be reduced and therefore can increase significantly the coverage area near the subsolar point. (C) 2001 Optical Society of America. C1 Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Futuretech Corp, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wang, MH (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Code 970-2, Greenbelt, MD 20771 USA. EM wang@simbios.gsfc.nasa.gov RI Wang, Menghua/F-5631-2010; Bailey, Sean/D-3077-2017 OI Wang, Menghua/0000-0001-7019-3125; Bailey, Sean/0000-0001-8339-9763 NR 20 TC 79 Z9 82 U1 2 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD SEP 20 PY 2001 VL 40 IS 27 BP 4790 EP 4798 DI 10.1364/AO.40.004790 PG 9 WC Optics SC Optics GA 473EY UT WOS:000171028400003 PM 18360519 ER PT J AU Goldmeer, JS Urban, DL Yuan, ZG AF Goldmeer, JS Urban, DL Yuan, ZG TI Measurement of gas-phase temperatures in flames with a point-diffraction interferometer SO APPLIED OPTICS LA English DT Article ID FLUID AB Experiments were performed to evaluate the performance of a point-diffraction interferometry (PDI) system to measure gas-phase temperatures in flames. PDI is an interferometric technique that creates the reference beam after the laser beam passes through the test section and directly provides the index of refraction in two dimensions. PDI-based temperature measurements were compared with thermocouple measurements of two-dimensional and axisymmetric thermal boundary layers, as well as two-dimensional and axisymmetric diffusion flames. The PDI system provided excellent agreement in the measurement of thermal profiles in the boundary layers and was within the uncertainties that are due to the radiation corrections for the thermocouple-based flame temperature measurements. (C) 2001 Optical Society of America. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. RP Goldmeer, JS (reprint author), GE Co, Ctr Corp Res & Dev, POB 8,K-1,Engn Syst Bldg, Schenectady, NY 12301 USA. EM goldmeer@alum.wpi.edu NR 19 TC 13 Z9 13 U1 3 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD SEP 20 PY 2001 VL 40 IS 27 BP 4816 EP 4823 DI 10.1364/AO.40.004816 PG 8 WC Optics SC Optics GA 473EY UT WOS:000171028400006 PM 18360522 ER PT J AU George, IM Mushotzky, RF Yaqoob, T Turner, TJ Kraemer, S Ptak, AF Nandra, K Crenshaw, DM Netzer, H AF George, IM Mushotzky, RF Yaqoob, T Turner, TJ Kraemer, S Ptak, AF Nandra, K Crenshaw, DM Netzer, H TI X-ray emission from the nucleus of the dwarf elliptical galaxy NGC 3226 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : dwarf; galaxies : individual (NGC 3226); galaxies : nuclei; X-rays : binaries; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; BLACK-HOLE MASS; SEYFERT NUCLEI; RADIO-SOURCES; LUMINOSITY; SPECTROMETER; VARIABILITY; DETECTIONS; NGC-4579; COMPACT AB We present the first high-resolution X-ray image of the dwarf elliptical galaxy NGC 3226. The data were obtained during an observation of the nearby Seyfert Galaxy NGC 3227 using the Chandra X-Ray Observatory. We detect a point X-ray source spatially consistent with the optical nucleus of NGC 3226 and a recently detected, compact, flat-spectrum radio source. The X-ray spectrum can be measured up to similar to 10 keV and is consistent with a power law with a photon index 1.7 less than or similar to Gamma less than or similar to 2.2 or thermal bremsstrahlung emission with 4 keV less than or similar to kT less than or similar to 10 keV. In both cases, the luminosity in the 2-10 keV band similar or equal to 10(40) h(75)(-1) ergs s(-1). We find marginal evidence that the nucleus varies within the observation. These characteristics support evidence from other wave bands that NGC 3226 harbors a low-luminosity active nucleus. We also comment on two previously unknown, fainter X-ray sources less than or similar to 15" from the nucleus of NGC 3226. Their proximity to the nucleus (with projected distances of less than or similar to 1.3 h(75)(-1) kpc) suggests both are within NGC 3226 and thus have luminosities (approximately a few times 10(38) to a few times 10(39) ergs s(-1)) consistent with black hole binary systems. C1 NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Univ Space Res Assoc, Washington, DC USA. Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Wise Observ, IL-69978 Tel Aviv, Israel. RP George, IM (reprint author), NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. RI Ptak, Andrew/D-3574-2012 NR 31 TC 12 Z9 12 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2001 VL 559 IS 1 BP 167 EP 172 DI 10.1086/322389 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 478WP UT WOS:000171371300016 ER PT J AU Pounds, K Reeves, J O'Brien, P Page, K Turner, M Nayakshin, S AF Pounds, K Reeves, J O'Brien, P Page, K Turner, M Nayakshin, S TI An XMM-Newton observation of the luminous Seyfert 1 galaxy Markarian 509 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Markarian 509); galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; X-RAY-SPECTRA; COLD MATTER; REFLECTION; IRON; DISK; ULTRAVIOLET; EMISSION; QUASARS; ASCA AB We present the spectral analysis of an early XMM-Newton observation of the luminous Seyfert 1 galaxy Mrk 509. We find the hard (2-10 keV) continuum slope, including reflection, to be somewhat flatter (Gamma = 1.75) than that of a typical broad-line Seyfert 1 galaxy. The most obvious feature in the hard X-ray spectrum is a narrow emission line near 6.4 keV with an equivalent width of similar to 50 eV. The energy and strength of this line is consistent with fluorescence from "neutral" iron in the molecular torus, and we note the emerging ubiquity of this feature in XMM-Newton and Chandra observations of Seyfert 1 galaxies over a wide luminosity range. We also find evidence for a second emission line at 6.7-6.9 keV, which we attempt to model by reflection from a highly ionized disk. A "soft excess," evident as an upward curvature in the continuum flux below similar to 1.5 keV, cannot be explained solely by enhanced reflection from the ionized disk. The RGS spectrum shows only weak discrete emission and absorption features in the soft X-ray spectrum, supporting our conclusion that the soft excess emission in Mrk 509 represents the high-energy portion of optically thick, thermal emission from the inner accretion disk. C1 Univ Leicester, Xray Astron Grp, Leicester LE1 7RH, Leics, England. USRA, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Pounds, K (reprint author), Univ Leicester, Xray Astron Grp, Leicester LE1 7RH, Leics, England. NR 40 TC 78 Z9 78 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2001 VL 559 IS 1 BP 181 EP 186 DI 10.1086/322315 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 478WP UT WOS:000171371300018 ER PT J AU Wallyn, P Ling, JC Mahoney, WA Wheaton, WA Durouchoux, P AF Wallyn, P Ling, JC Mahoney, WA Wheaton, WA Durouchoux, P TI Batse search for the similar to 540 keV feature in the Crab spectrum observed by Granat-SIGMA SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : observations; pulsars : individual (Crab Pulsar) ID FIGARO-II; PULSAR; NEBULA; LINE AB We report the first simultaneous observations of the gamma -ray spectrum of the Crab in the energy range 25-1.7 MeV made by the BATSE and SIGMA experiments. These observations were made on 1992 March 10-11. We report specifically results of a search in the JPL BATSE Earth Occultation database for the transient high-energy feature at similar to 540 keV reported by Granat-SIGMA during this period. We obtain a null result for this feature on both March 10 and March 11. The time-averaged continuum spectrum in the 25 keV-MeV range for the 2 day average spectrum is consistent with a single power law, with photon index of 2.25 +/-0.02. The best-fit line flux for either a narrow (0 keV FWHM) feature at 541 keV or a broad (44 keV FWHM) feature at 536 keV of the same 2 day spectrum is (-1.2 +/-0.8) x 10(-3) and (-1.3 +/-0.8) x 10(-3) photons cm(-2) s(-1), compared to (4.3 +/-1.2) x 10(-3) and (5.1 +/-1.7) x 10(-3) photons cm(-2) s(-1), respectively, reported by the SIGMA investigators. The difference of the line fluxes measured simultaneously by the BATSE and SIGMA experiments is estimated to be 3.8 a significance for the narrow feature and 3.4 sigma significance for the broad feature. C1 CALTECH, Jet Prop Lab 169 327, Pasadena, CA 91109 USA. Ctr Etud Saclay, Serv Astrophys, DAPNIA, F-91191 Gif Sur Yvette, France. RP Wallyn, P (reprint author), CALTECH, Jet Prop Lab 169 327, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 21 TC 2 Z9 2 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2001 VL 559 IS 1 BP 342 EP 345 DI 10.1086/322318 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 478WP UT WOS:000171371300032 ER PT J AU Peterson, RC Dorman, B Rood, RT AF Peterson, RC Dorman, B Rood, RT TI Modeling mid-ultraviolet spectra. I. Temperatures of metal-poor stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : abundances; stars : abundances; stars : fundamental parameters; stars : Population II; ultraviolet : galaxies; ultraviolet : stars ID ALPHA-CENTAURI-A; SPECTROSCOPIC ANALYSIS; ELLIPTIC GALAXIES; FE-I; STELLAR POPULATIONS; ABUNDANCE ANALYSIS; TRANSITIONS; ATMOSPHERES; HYDROGEN; LINES AB Determining the properties of remote globular clusters and elliptical galaxies using evolutionary population synthesis requires a library of reliable model stellar fluxes. Empirical libraries are limited to spectra of stars in the solar neighborhood, with nearly solar abundances and abundance ratios. We report here a first step toward providing a flux library that includes nonsolar abundances, based on calculations from first principles that are calibrated empirically. Because the mid-ultraviolet spectrum of an old stellar system is dominated by the contribution from its main-sequence turnoff stars, we have started by modeling these. We have calculated mid-ultraviolet spectra for the Sun and nine nearby, near-main-sequence stars spanning metallicities from less than 1/100 solar to greater than solar, encompassing a range of light-element-abundance enhancements. We first determined temperatures of eight of the stars by analyzing optical echelle spectra together with the mid-ultraviolet. Both could be matched at the same time only when models with no convective overshoot were adopted and only when an approximate chromosphere was incorporated near the surface of relatively metal-rich models. Extensive modifications to mid-UV line parameters were also required, notably the manual assignment of approximate identifications for mid-U-V lines missing from laboratory line lists. Without recourse to additional missing opacity, these measures suffice to reproduce in detail almost the entire mid-UV spectrum of solar-temperature stars up to 1/10 solar metallicity and the region from 2900 to 3100 Angstrom throughout the entire metallicity range. Ramifications for abundance determinations in individual metal-poor stars and for age-metallicity determinations of old stellar systems are briefly discussed, with emphasis on the predictive power of the calculations. C1 Univ Calif Santa Cruz, Univ Calif Observ, Lick Observ, Dept Astron, Santa Cruz, CA 95064 USA. Astrophys Adv, Palo Alto, CA 94301 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Emergent IT Inc, Greenbelt, MD 20771 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. RP Peterson, RC (reprint author), Univ Calif Santa Cruz, Univ Calif Observ, Lick Observ, Dept Astron, Santa Cruz, CA 95064 USA. NR 75 TC 27 Z9 27 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2001 VL 559 IS 1 BP 372 EP 387 DI 10.1086/322294 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 478WP UT WOS:000171371300035 ER PT J AU Hollis, JM Boboltz, DA Pedelty, JA White, SM Forster, JR AF Hollis, JM Boboltz, DA Pedelty, JA White, SM Forster, JR TI R Aquarii: Evidence for differential rotation of the SiO maser shell SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; masers; stars : individual (R Aquarii); stars : rotation; stars : variables : other; techniques : interferometric ID VARIABLE-STARS; PERIOD AB We previously reported Very Large Array and Berkeley-Illinois-Maryland Association (BIMA) array observations that suggested rotation of the SiO maser shell surrounding the long-period variable (LPV) in the R Aquarii binary system. In the present Very Long Baseline Array (VLBA) work, we report high spatial and spectral resolution observations of the v = 1, J = 1-0, SiO, maser line that confirm our previous result and further suggest that the LPV maser shell is undergoing differential rotation. The 8-34 yr range of rotational periods resulting from differential rotation of the maser shell contains the similar to 18 yr period reported previously. The velocity structure of the VLBA data suggests a rotation symmetry axis oriented at a position angle of similar to 150 degrees. The differential rotation model can be envisioned as a series of nested thin spherical shells that have a common rotation axis; each thin shell is characterized by its radius, r, with the innermost shell rotating fastest and the outermost shell slowest, in accordance with an equatorial plane velocity law of the form v proportional to (1/r(q))(1/2). We find that q approximate to 1.09 is necessary to approximate the VLBA data, suggesting that the differential rotation is approximately Keplerian. C1 NASA, Earth & Space Data Comp Div, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. USN Observ, Washington, DC 20392 USA. NASA, Biospher Sci Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Hat Creek, CA 96040 USA. Hat Creek Radio Observ, Hat Creek, CA 96040 USA. RP Hollis, JM (reprint author), NASA, Earth & Space Data Comp Div, Goddard Space Flight Ctr, Code 930, Greenbelt, MD 20771 USA. NR 11 TC 27 Z9 27 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2001 VL 559 IS 1 BP L37 EP L40 DI 10.1086/323667 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 478WQ UT WOS:000171371400010 ER PT J AU Bouzidi, M d'Humieres, D Lallemand, P Luo, LS AF Bouzidi, M d'Humieres, D Lallemand, P Luo, LS TI Lattice Boltzmann equation on a two-dimensional rectangular grid SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID NAVIER-STOKES EQUATION; CIRCULAR-CYLINDER; BGK MODELS; SYSTEM; FLOW AB sWe construct a multirelaxation lattice Boltzmann model [1] on a two-dimensional rectangular grid. The model is partly inspired by a previous work of Koelman [2] to construct a lattice BGK model on a two-dimensional rectangular grid. The linearized dispersion equation is analyzed to obtain the constraints on the isotropy of the transport coefficients and Galilean invariance for various wave propagations in the model. The linear stability of the model is also studied. The model is numerically tested for three cases: (a) a vortex moving with a constant velocity on a mesh with periodic boundary conditions: (b) Poiseuille flow with an arbitrary inclined angle with respect to the lattice orientation; and (c) a cylinder asymmetrically placed in a channel. The numerical results of these tests are compared with either analytic solutions or the results obtained by other methods. Satisfactory results are obtained for the numerical simulations. (C) 2001 Academic Press. C1 Univ Paris 11, Lab CNRS, ASCI, F-91405 Orsay, France. Ecole Normale Super, Phys Stat Lab, F-75231 Paris 05, France. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Bouzidi, M (reprint author), Univ Paris 11, Lab CNRS, ASCI, Batiment 506, F-91405 Orsay, France. RI Luo, Li-Shi/A-4561-2011 OI Luo, Li-Shi/0000-0003-1215-7892 NR 15 TC 64 Z9 65 U1 0 U2 23 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 SEP 20 PY 2001 VL 172 IS 2 BP 704 EP 717 DI 10.1006/jcph.2001.6850 PG 14 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 477FY UT WOS:000171273600013 ER PT J AU Harnack, O Il'in, KS Siegel, M Karasik, BS McGrath, WR de Lange, G AF Harnack, O Il'in, KS Siegel, M Karasik, BS McGrath, WR de Lange, G TI Dynamics of the response to microwave radiation in YBa2CU3O7-x hot-electron bolometer mixers SO APPLIED PHYSICS LETTERS LA English DT Article ID SUPERCONDUCTING FILMS; HEAT-CAPACITY; THIN-FILMS; PHOTORESPONSE; NONEQUILIBRIUM AB We present a systematic study of the intermediate frequency (IF) bandwidth of hot-electron bolometer mixers made from YBa2Cu3O7-x high-temperature superconductive thin films fabricated on substrates with high thermal conductivity (MgO and sapphire). At a local oscillator frequency of 100 GHz, a strong dependence of the IF bandwidth on the bias point and temperature has been experimentally found. Moreover, an unexpected IF bandwidth variation has been detected in a broad range of operating frequencies (1-480 GHz). Besides conventional bolometric mixing mechanisms associated with thermalization of electrons and phonons, the contribution of direct interaction between radiation and magnetic vortices in the YBa2Cu3O7-x film may be responsible for the observed effects. (C) 2001 American Institute of Physics. C1 Forschungszentrum Julich, Inst Schichten & Grenzflachen, D-52425 Julich, Germany. CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. Space Res Org Netherlands, Groningen, Netherlands. RP Il'in, KS (reprint author), Sony Int Europe GmbH, Adv Technol Ctr Stuttgart, Mat Sci Labs, D-70327 Stuttgart, Germany. EM k.ilin@fz-juelich.de NR 21 TC 13 Z9 13 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD SEP 17 PY 2001 VL 79 IS 12 BP 1906 EP 1908 DI 10.1063/1.1401095 PG 3 WC Physics, Applied SC Physics GA 472ZL UT WOS:000171014800055 ER PT J AU Jozsa, R Abrams, DS Dowling, JP Williams, CP AF Jozsa, R Abrams, DS Dowling, JP Williams, CP TI Comment on "Quantum clock synchronization based on shared prior entanglement" - Reply SO PHYSICAL REVIEW LETTERS LA English DT Editorial Material C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Bristol, Dept Comp Sci, Bristol BS8 1UB, Avon, England. RP Jozsa, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI DOWLING, JONATHAN/L-2749-2013 NR 1 TC 8 Z9 8 U1 0 U2 2 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 SEP 17 PY 2001 VL 87 IS 12 AR 129802 DI 10.1103/PhysRevLett.87.129802 PG 1 WC Physics, Multidisciplinary SC Physics GA 474TJ UT WOS:000171122700083 ER PT J AU Newman, PA Nash, ER Rosenfield, JE AF Newman, PA Nash, ER Rosenfield, JE TI What controls the temperature of the Arctic stratosphere during the spring? SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; POLAR VORTEX; TOTAL OZONE; CIRCULATIONS; METEOROLOGY; BALANCE; TRENDS; FLUXES; WAVES AB The temperature of the polar lower stratosphere during spring is the key factor in changing the magnitude of ozone loss in the Arctic polar vortex. In this paper, we quantitatively demonstrate that the polar lower stratospheric temperature is primarily controlled by planetary-scale, waves. We use National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data covering the last two decades to investigate how these planetary waves are connected to polar lower stratospheric temperatures. In particular, we show that the tropospheric eddy heat flux in middle to late winter (January-February) is highly correlated with the mean polar stratospheric temperature during March. These planetary waves are forced by both thermal and orographic processes in the troposphere and propagate into the stratosphere in the middle and high latitudes. Strong midwinter planetary wave forcing leads to a warmer spring Arctic lower stratosphere in early spring, while weak midwinter forcing leads to cooler spring Arctic temperatures. In addition, this planetary wave driving also has a strong impact on the strength of the polar vortex. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Emergent Informat Technol Inc, Vienna, VA USA. Sci Applicat Int Corp, Gen Sci Corp, Beltsville, MD USA. RP Newman, PA (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 916, Greenbelt, MD 20771 USA. EM newman@code916.gsfc.nasa.gov; nash@code916.gsfc.nasa.gov; rose@code916.gsfc.nasa.gov RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 39 TC 194 Z9 196 U1 2 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 SEP 16 PY 2001 VL 106 IS D17 BP 19999 EP 20010 DI 10.1029/2000JD000061 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 473KZ UT WOS:000171044200001 ER PT J AU Zhou, LM Tucker, CJ Kaufmann, RK Slayback, D Shabanov, NV Myneni, RB AF Zhou, LM Tucker, CJ Kaufmann, RK Slayback, D Shabanov, NV Myneni, RB TI Variations in northern vegetation activity inferred from satellite data of vegetation index during 1981 to 1999 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HIGH-RESOLUTION RADIOMETER; SEA-SURFACE TEMPERATURE; NEAR-INFRARED CHANNELS; ATMOSPHERIC CO2; CLIMATE-CHANGE; TIME-SERIES; TERRESTRIAL ECOSYSTEMS; CARBON BALANCE; ORBITAL DRIFT; WHITE SPRUCE AB The northern high latitudes have warmed by about 0.8 degreesC since the early 1970s, but not all areas have warmed uniformly [Hansen et al., 1999]. There. is warming in most of Eurasia, but the warming rate in the United States is smaller than in most of the world, and a slight cooling is observed in the eastern United States over the past 50 years. These changes beg the question, can we detect the biotic response to temperature changes? Here we present results from analyses of a recently developed satellite-sensed normalized difference vegetation index (NDVI) data set for the period July 1981 to December 1999: (1) About 61% of the total vegetated area between 40 degreesN and 70 degreesN in Eurasia shows a persistent increase in growing season NDVI over a broad contiguous swath of land from central Europe through Siberia to the Aldan plateau, where almost 58% (7.3 x 10(6) km(2)) is forests and woodlands; North America, in comparison, shows a fragmented pattern of change in smaller areas notable only in the forests of the southeast and grasslands of the upper Midwest, (2) A larger increase in growing season NDVI magnitude (12% versus 8%) and a longer active growing season (18 versus 12 days) brought about by an early spring and delayed autumn are observed in Eurasia relative to North America, (3) NDVI decreases are observed in parts of Alaska, boreal Canada, and northeastern Asia, possibly due to temperature-induced drought as these regions experienced pronounced warming without a concurrent increase in rainfall [Barber et al., 2000]. We argue that these changes in NDVI reflect changes in biological activity. Statistical analyses indicate that there is a statistically meaningful relation between changes in NDVI and land surface temperature for vegetated areas between 40 degreesN and 70 degreesN. That is, the temporal changes and continental differences in NDVI are consistent with ground-based measurements of temperature, an important determinant of biological activity. Together, these results suggest a photosynthetically vigorous Eurasia. relative to North America during the past 2 decades, possibly driven by temperature and precipitation patterns. Our results are in broad agreement with a recent comparative analysis of 1980s and 1990s boreal and temperate forest inventory data [United Nations, 2000]. C1 Boston Univ, Dept Geog, Boston, MA 02215 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. RP Zhou, LM (reprint author), Boston Univ, Dept Geog, 675 Commonwealth Ave, Boston, MA 02215 USA. EM lmzhou@crsa.bu.edu; compton@kratmos.gsfc.nasa.gov; kaufmann@bu.edu; dan@manyu.gsfc.nasa.gov; shabanov@bu.edu; rmyneni@crsa.bu.edu RI Slayback, Daniel/E-7465-2011; Zhou, Liming/A-2688-2012; Myneni, Ranga/F-5129-2012 NR 60 TC 740 Z9 918 U1 16 U2 215 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 SEP 16 PY 2001 VL 106 IS D17 BP 20069 EP 20083 DI 10.1029/2000JD000115 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 473KZ UT WOS:000171044200006 ER PT J AU Rind, D Chandler, M Lerner, J Martinson, DG Yuan, X AF Rind, D Chandler, M Lerner, J Martinson, DG Yuan, X TI Climate response to basin-specific changes in latitudinal temperature gradients and implications for sea ice variability SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NORTH-ATLANTIC OSCILLATION; GENERAL-CIRCULATION MODELS; SURFACE-TEMPERATURE; SOUTHERN-OSCILLATION; GEOPOTENTIAL HEIGHT; ARCTIC OSCILLATION; TRENDS; HEMISPHERE; WINTER; PRECIPITATION AB We use experiments with the GISS general circulation model to investigate how changes in latitudinal temperature gradients affect atmospheric circulation in different ocean basins, with particular attention paid to the implications for high-latitude sea ice. The results are relevant to both estimated past climate changes, current climate gradient changes (e.g., El Nino-Southern Oscillation events), and proposed future climate responses to greenhouse gases. Sea surface temperature gradients are increased/decreased in all ocean basins, and in the Pacific and Atlantic separately, without changing sea ice or global average temperature. Additional experiments prescribe sea ice growth/reduction with global cooling/warming. As expected, increased gradients strengthen the subtropical jet stream and deepen the subpolar lows in each hemisphere, but results in the Northern and Southern Hemispheres differ in fundamental ways. In the Northern Hemisphere, increased storm intensities occur in the ocean basin with the increased gradient; in the Southern Hemisphere the deeper storms occur in the ocean basin with the decreased gradient. Alterations of the gradient in one ocean basin change longitudinal temperature gradients; an increased gradient in one basin from tropical heating results in subsidence in the tropics in the other basin, mimicking the effect of a decreased gradient in that basin. The subtropical jet is therefore strengthened over the basin with the increased gradient and decreased over the other ocean basin. Hence in many respects, regional effects, such as the strength of subpolar lows in an individual basin, are amplified when the gradient changes are of opposite sign in the two ocean basins. The Southern Hemisphere response occurs because gradient increases in one ocean basin, by strengthening the subtropical jet, shift storm tracks equatorward and away from the potential energy source associated with cold air advection from Antarctica. At the same time, with a weaker subtropical jet in the other basin, storms move poleward and strengthen. This latter effect may explain observed sea ice variations that are out of phase in the Atlantic and Pacific Ocean basins in the Southern Hemisphere (referred to as the Antarctic dipole) as well as upper ocean variability in the Weddell gyre. Gradient changes produce little effect on sea level pressure in the Arctic, unless sea ice is changed. With Arctic sea ice reductions, the sea ice response acts as a positive feedback, inducing cyclonic circulation changes that would enhance its removal, as may be occurring due to the current high phase of the North Atlantic Oscillation. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA. RP Rind, D (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM drind@giss.nasa.gov NR 44 TC 43 Z9 43 U1 0 U2 5 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 SEP 16 PY 2001 VL 106 IS D17 BP 20161 EP 20173 DI 10.1029/2000JD900643 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 473KZ UT WOS:000171044200013 ER PT J AU Rind, D Chandler, M Lonergan, P Lerner, J AF Rind, D Chandler, M Lonergan, P Lerner, J TI Climate change and the middle atmosphere 5. Paleostratosphere in cold and warm climates SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPOSPHERE-STRATOSPHERE SYSTEM; GENERALIZED ELIASSEN-PALM; LAST GLACIAL MAXIMUM; DOUBLED CO2 CLIMATE; VOSTOK ICE CORE; PLANETARY-WAVES; UV VARIABILITY; MODEL; CIRCULATION; TRANSPORT AB The GISS Global Climate Middle Atmosphere Model is used to investigate how the stratosphere would have changed during two paleotime periods: the cold Last Glacial Maximum (similar to 21,000 years ago) and the warm Paleocene (58 million years ago). Uncertainties in sea surface temperatures and mountain wave drag over the ice sheets are investigated in sensitivity experiments. In many respects the climate and dynamical forcing of the stratosphere was opposite in these time periods, with reduced CO2, increased topography, and increased latitudinal temperature gradients during the ice age, and increased CO2, reduced topography and latitudinal temperature gradients during the Paleocene, representative of much of the Tertiary. The results show that the stratospheric response was often of an opposite nature as well, with the ice ages featuring a warmer stratosphere, increased residual circulation in the lower stratosphere (and decreased above), and weakened polar vortices, while the Paleocene simulation had a colder stratosphere, decreased residual circulation in the lower stratosphere (and increased above), with strengthened polar vortices. Analysis shows that the stratospheric response is very individualistic to the particular climate regime, and the opposite effects are not necessarily produced by inversely related mechanisms. Of particular importance in both climates is the reduced latitudinal gradient at high latitudes, which weakens high-latitude zonal winds and limits wave energy vertical propagation. Increased planetary wave. forcing in the lower stratosphere accelerates the circulation during the ice ages. A strong increase in zonal winds during the Paleocene is the result of both decreased planetary wave forcing, associated with the reduced topography, and decreased mountain wave drag. The sensitivity experiments show that if tropical sea surface temperatures were warmer, the stratospheric residual circulation was enhanced, while stratospheric warmings are sensitive to the precise sea surface temperature specifications and mountain wave drag. 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, 2880 Broadway, New York, NY 10025 USA. EM drind@giss.nasa.gov NR 27 TC 15 Z9 15 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 16 PY 2001 VL 106 IS D17 BP 20195 EP 20212 DI 10.1029/2000JD900548 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 473KZ UT WOS:000171044200016 ER PT J AU Ginoux, P Chin, M Tegen, I Prospero, JM Holben, B Dubovik, O Lin, SJ AF Ginoux, P Chin, M Tegen, I Prospero, JM Holben, B Dubovik, O Lin, SJ TI Sources and distributions of dust aerosols simulated with the GOCART model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; SKY RADIANCE MEASUREMENTS; OPTICAL-THICKNESS; SAHARAN DUST; MINERAL AEROSOL; SIZE-DISTRIBUTION; DESERT DUST; ULTRAVIOLET-RADIATION; SPATIAL VARIABILITY; TRACE-ELEMENTS AB The global distribution of dust aerosol is simulated with the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model. In, this model all topographic lows with bare ground surface are assumed to have accumulated sediments which are potential dust sources. The uplifting of dust particles is expressed as a function of surface wind speed and wetness. The GOCART model is driven by the assimilated meteorological fields from the Goddard Earth Observing System Data Assimilation System (GEOS DAS) which facilitates direct comparison with observations. The model includes seven size classes of mineral dust ranging from 0.1-6 mum radius. The total annual emission is estimated to be between 1604 and 1960 Tg yr(-1) in a 5-year simulation. The model has been evaluated by comparing simulation results with ground-based measurements and satellite data. The evaluation has been performed by comparing surface concentrations, vertical distributions, deposition rates, optical thickness, and size distributions. The comparisons show that the model results generally agree with the observations without the necessity of invoking any contribution from anthropogenic disturbances to soils. However, the model overpredicts the transport of dust from the Asian sources to the North Pacific. This discrepancy is attributed to an overestimate of small particle emission from the Asian sources. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 USA. Max Planck Inst Biogeochem, D-07701 Jena, Germany. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. RP Ginoux, P (reprint author), Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. EM ginoux@rondo.gsfc.nasa.gov; chin@rondo.gsfc.nasa.gov; itegen@bgc-jena.mpg.de; jprospero@rsmas.miami.edu; brent@aeronet.gsfc.nasa.gov; dubovik@aeronet.gsfc.nasa.gov; slin@dao.gsfc.nasa.gov RI Dubovik, Oleg/A-8235-2009; Ginoux, Paul/C-2326-2008; Chin, Mian/J-8354-2012; OI Dubovik, Oleg/0000-0003-3482-6460; Ginoux, Paul/0000-0003-3642-2988; Prospero, Joseph/0000-0003-3608-6160 NR 61 TC 801 Z9 817 U1 14 U2 92 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 SEP 16 PY 2001 VL 106 IS D17 BP 20255 EP 20273 DI 10.1029/2000JD000053 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 473KZ UT WOS:000171044200020 ER PT J AU Koch, D AF Koch, D TI Transport and direct radiative forcing of carbonaceous and sulfate aerosols in the GISS GCM SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; BLACK CARBON; ATMOSPHERIC AEROSOL; PARTICULATE CARBON; ORGANIC-CARBON; ANTHROPOGENIC SULFATE; AIRBORNE MEASUREMENTS; ELEMENTAL CARBON; UNITED-STATES; CLIMATE AB We simulate the major anthropogenic aerosols, sulfate, organic carbon and black carbon, in the Goddard Institute for Space Studies General Circulation Model (GISS GCM), and examine their transport, relative abundances, and direct radiative forcing. Both present-day and projected future emissions are used, as provided by the IPCC SRES (A2) scenarios for 2030 and 2100. We consider the sensitivity of the black carbon distribution to the treatment of its solubility and allow solubility to depend upon exposure to gas phase production of sulfuric acid (case S), or time (case A), or a fixed rate (case C). We show that all three approaches can be tuned to give reasonable agreement with present-day observations. However, case S has higher black carbon in the arctic winter, owing to reduced SO2 oxidation and black carbon solubility. This improves upon the arctic deficiency in previous models, though may be somewhat excessive in this model. We also show that with a different ratio of sulfur/carbonaceous emissions, the case S mechanism can give significantly different results compared to the other mechanisms. Thus, in the 2100 simulation, with reduced sulfur and increased black carbon emissions, the black carbon burden is similar to 13% higher and the direct radiative forcing is similar to 40% higher in case S compared to the other cases. We consider the relative abundances of carbonaceous and sulfate aerosols in different regions. In the current simulations, carbonaceous aerosols exceed sulfate at the surface in Asia and much of Europe and throughout the column in biomass burning regions. We show that the model ratio of carbonaceous to sulfate aerosols increases with altitude over many oceanic regions, especially in summertime, as was observed during the Tropospheric Aerosol Radiative Forcing Observational Experiment campaign; however, over land and during other seasons the ratio generally decreases with altitude. The (present day) direct radiative forcings for externally mixed (case A) black carbon, organic carbon, and sulfate are calculated to be 0.35, -0.30, and -0.65 W/m(2), respectively. In the 2100 simulation these forcings are 0.89, -0.64, and -0.54 W/m(2), respectively. The net anthropogenic aerosol global average forcing seasonality inverts between the current and future simulations: the forcing is most negative in (Northern Hemisphere) summertime in 2000 but is least negative or even positive during (NH) summer in 2100; this inversion is more extreme in the Northern Hemisphere. C1 Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10027 USA. RP Koch, D (reprint author), Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10027 USA. EM dkoch@giss.nasa.gov NR 47 TC 155 Z9 159 U1 3 U2 21 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 SEP 16 PY 2001 VL 106 IS D17 BP 20311 EP 20332 DI 10.1029/2001JD900038 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 473KZ UT WOS:000171044200023 ER PT J AU Ferrare, RA Turner, DD Brasseur, LH Feltz, WF Dubovik, O Tooman, TP AF Ferrare, RA Turner, DD Brasseur, LH Feltz, WF Dubovik, O Tooman, TP TI Raman lidar measurements of the aerosol extinction-to-backscatter ratio over the Southern Great Plains SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SPECTRAL RESOLUTION LIDAR; SKY RADIANCE MEASUREMENTS; MID-ATLANTIC COAST; OPTICAL-PROPERTIES; WATER-VAPOR; ATMOSPHERIC AEROSOLS; TROPOSPHERIC AEROSOL; 6-WAVELENGTH LIDAR; SUN-PHOTOMETER; BOUNDARY-LAYER AB We derive profiles of the aerosol extinction-to-backscatter ratio, S-a, at 355 nm using aerosol extinction and backscatter profiles measured during 1998 and 1999 by the operational Raman lidar at the Department of Energy Atmospheric Radiation Measurement Program Southern Great Plains site in north central Oklahoma. Data from this Raman/Rayleigh-Mie lidar, which measures Raman scattering from nitrogen as well as the combined molecular (Rayleigh) and aerosol (Mie) scattering at the laser wavelength, are used to derive aerosol extinction and backscattering independently as a function of altitude. Because this lidar operates at 355 nm, where molecular backscattering is comparable to aerosol backscattering, S-a retrievals are generally limited to conditions where aerosol extinction at 355 nm is >0.03 km(-1). The mean value of S-a at 355 nm derived for this period was 68 sr with a standard deviation of 12 sr. S-a was generally about 5-10 sr higher during high aerosol optical thickness (AOT) (>0.3) conditions than during low AOT (<0.1). A similar increase in S-a was found when the relative humidity increased from 30 to 80%. Large (> 15%) variations in the vertical profile of S-a occurred about 30% of the time, which implies that significant variability in the vertical distribution of the aerosol size distribution, shape, and/or composition often occurs. The Raman lidar measurements of S-a were compared with estimates of particle size and refractive index derived from an algorithm that uses ground-based Sun photometer measurements of Sun and sky radiance. For 17 cases of coincident Raman lidar and Sun and sky radiance measurements, S-a was linearly correlated with the aerosol fine mode effective radius and the volume ratio of fine/coarse particles. C1 NASA, Langley Res Ctr, Sci Applicat Int Corp, Hampton, VA 23665 USA. Pacific NW Natl Lab, Richland, WA USA. Univ Wisconsin, Cooperat Inst Meteorol Satellite Studies, Madison, WI USA. NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. Sandia Natl Labs, Livermore, CA USA. RP Ferrare, RA (reprint author), NASA, Langley Res Ctr, Sci Applicat Int Corp, Hampton, VA 23665 USA. EM r.ferrare@larc.nasa.gov; dave.turner@pnl.gov; l.h.heilman@larc.nasa.gov; wayne.feltz@ssec.wisc.edu; dubovik@spamer.gsfc.nasa.gov; tooman@ca.sandia.gov RI Dubovik, Oleg/A-8235-2009 OI Dubovik, Oleg/0000-0003-3482-6460 NR 57 TC 65 Z9 65 U1 0 U2 12 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 16 PY 2001 VL 106 IS D17 BP 20333 EP 20347 DI 10.1029/2000JD000144 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 473KZ UT WOS:000171044200024 ER PT J AU Thomas, AC Carr, ME Strub, PT AF Thomas, AC Carr, ME Strub, PT TI Chlorophyll variability in eastern boundary currents SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PIGMENT CONCENTRATIONS; CALIFORNIA CURRENT AB The first three years of SeaWiFS data (1997-2000) provide the most complete quantification to date of chlorophyll seasonal variability along the full latitudinal extent of the four major eastern boundary currents (EBCs). Comparisons to previously published chlorophyll seasonal climatologies deduced from the relatively sparse coverage provided by the Coastal Zone Color Scanner (CZCS) show significant differences in both southern hemisphere EBCs, while northern hemisphere regions are qualitatively similar. Comparisons between chlorophyll and cross-shelf Ekman transport seasonal cycles, calculated from coincident satellite scatterometer data, show seasonal maxima have similar phases over most of the California Current, at higher (> 32 degreesS) latitudes in the Peru-Chile and Benguela Currents (> 30 degreesS) and at lowest latitudes (< 20 degreesN) in the Canary Current. Latitudinal zones within which phases diverge axe indicative of alternate and/or more distant forcing. C1 Univ Maine, Sch Marine Sci, Orono, ME 04469 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91009 USA. Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. RP Thomas, AC (reprint author), Univ Maine, Sch Marine Sci, Orono, ME 04469 USA. NR 11 TC 81 Z9 86 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 SEP 15 PY 2001 VL 28 IS 18 BP 3421 EP 3424 DI 10.1029/2001GL013368 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 473HN UT WOS:000171035000001 ER PT J AU Marcus, SL Dickey, JO de Viron, O AF Marcus, SL Dickey, JO de Viron, O TI Links between intraseasonal. (extended MJO) and ENSO timescales: Insights via geodetic and atmospheric analysis SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MADDEN-JULIAN OSCILLATION; ANGULAR-MOMENTUM FLUCTUATIONS; EL-NINO; INTERANNUAL FLUCTUATIONS; SURFACE-TEMPERATURE; CIRCULATION MODELS; TROPICAL PACIFIC; ROTATION; LENGTH; PREDICTABILITY AB The relationship of intraseasonal variability to ENSO is investigated using daily length-of-day (LOD), atmospheric angular momentum (AAM), west equatorial Pacific (WPAC) wind stress and monthly Nino3 SST data for the years 1976-1999. Strong coherence is found for LOD, AAM, and their residual (representative of oceanic angular momentum and /or unmodeled/underrepresented atmospheric variability) with the regional wind stress at periods near 75 days, a preferred time scale for WPAC Kelvin wave generation. Amplitude envelopes of LOD and AAM filtered at similar periods (60-100 days) are significantly correlated with Nino3 anomalies at an SST lag of 8 months; the LOD-AAM residual correlates at a shorter lag (5 months), with the difference representing an oceanic spin-up time. No significant correlations are found using a band (36-60 days) typifying the global Madden-Julian Oscillation, accounting for the lack of previous MJO-ENSO correlations in the literature. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Marcus, SL (reprint author), CALTECH, Jet Prop Lab, MS 238-332, Pasadena, CA 91109 USA. RI de Viron, Olivier/N-6647-2014; OI de Viron, Olivier/0000-0003-3112-9686; Marcus, Steven/0000-0002-5763-6961 NR 35 TC 7 Z9 7 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 SEP 15 PY 2001 VL 28 IS 18 BP 3465 EP 3468 DI 10.1029/2001GL013434 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 473HN UT WOS:000171035000012 ER PT J AU Studinger, M Bell, RE Blankenship, DD Finn, CA Arko, RA Morse, DL Joughin, I AF Studinger, M Bell, RE Blankenship, DD Finn, CA Arko, RA Morse, DL Joughin, I TI Subglacial sediments: A regional geological template for ice flow in West Antarctica SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STREAM; SHEET; BENEATH AB We use aerogeophysical data to estimate the distribution of marine subglacial sediments and fault-bounded sedimentary basins beneath the West Antarctic Ice Sheet (WAIS). We find that significant ice flow occurs exclusively in regions covered by subglacial sediments. The onsets and lateral margins of ice streams coincide with the limit of marine sediments. Lateral margins are also consistently linked with fault-bounded basins. We predict that the inland migration of ice streams B and C-1 towards the ice divide outside the region covered by marine or rift sediments is unlikely. The subglacial geology has the potential to modulate the dynamic evolution of the ice streams and the WAIS. C1 Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA. Univ Texas, Inst Geophys, Austin, TX 78759 USA. US Geol Survey, Denver Fed Ctr, Lakewood, CO 80225 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Studinger, M (reprint author), Columbia Univ, Lamont Doherty Earth Observ, POB 1000, Palisades, NY 10964 USA. EM mstuding@ldeo.columbia.edu RI Blankenship, Donald/G-5935-2010; Joughin, Ian/A-2998-2008 OI Joughin, Ian/0000-0001-6229-679X NR 17 TC 67 Z9 67 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 15 PY 2001 VL 28 IS 18 BP 3493 EP 3496 DI 10.1029/2000GL011788 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 473HN UT WOS:000171035000019 ER PT J AU Rignot, E Echelmeyer, K Krabill, W AF Rignot, E Echelmeyer, K Krabill, W TI Penetration depth of interferometric synthetic-aperture radar signals in snow and ice SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MASS-BALANCE; GREENLAND; SHEET; ALASKA AB Digital elevation models of glaciated terrain produced by the NASA/Jet Propulsion Laboratory (JPL) airborne interferometric synthetic-aperture radar (InSAR) instrument in Greenland and Alaska at the C- (5.6 cm wavelength) and L-band (24-cm) frequencies were compared with surface elevation measured from airborne laser altimetry to estimate the phase center of the interferometric depth, or penetration depth, delta (p). On cold polar firn at Greenland summit, delta (p) = 9 +/- 2m at C- and 14 +/- 4m at L-band. On the exposed ice surface of Jakobshavn Isbrae, west Greenland, delta (p) = 1 +/-2 m at C- and 3 +/-3 m at L-band except on smooth, marginal ice where delta (p) = 15 +/-5 m. On colder marginal ice of northeast Greenland, delta (p) reaches 60 to 120 m at L-band. On the temperate ice of Brady Glacier, Alaska, delta (p) is 4 +/-2 m at C- and 12 +/-6 m at L-band, with little dependence on snow/ice conditions. The implications of the results on the scientific use of InSAR data over snow/ice terrain is discussed. C1 CALTECH, Jet Prop Lab, Radar Sci & Engn Sect, Pasadena, CA 91109 USA. Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA. NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Lab Hydrospher Proc, Wallops Isl, VA 23337 USA. RP Rignot, E (reprint author), CALTECH, Jet Prop Lab, Radar Sci & Engn Sect, MS 300-235,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 9 TC 108 Z9 110 U1 2 U2 18 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 SEP 15 PY 2001 VL 28 IS 18 BP 3501 EP 3504 DI 10.1029/2000GL012484 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 473HN UT WOS:000171035000021 ER PT J AU Boer, EA Bell, LD Brongersma, ML Atwater, HA AF Boer, EA Bell, LD Brongersma, ML Atwater, HA TI Models for quantitative charge imaging by atomic force microscopy SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID TAPPING-MODE; INTERMITTENT-CONTACT; ELASTIC SPHERE; VIBRATING TIP; RIGID PLANE; SURFACE; CANTILEVER; AMPLITUDE; DYNAMICS; ADHESION AB Two models are presented for quantitative charge imaging with an atomic-force microscope. The first is appropriate for noncontact mode and the second for intermittent contact (tapping) mode imaging. Different forms for the contact force are used to demonstrate that quantitative charge imaging is possible without precise knowledge of the contact interaction. From the models, estimates of the best charge sensitivity of an unbiased standard atomic-force microscope cantilever are found to be on the order of a few electrons. (C) 2001 American Institute of Physics. C1 CALTECH, Thomas J Watson Lab Appl Phys, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Thomas J Watson Lab Appl Phys, Pasadena, CA 91125 USA. EM elizabeth.boer@alcatel.fr RI Brongersma, Mark/R-6099-2016 NR 63 TC 14 Z9 14 U1 0 U2 4 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-8979 EI 1089-7550 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 15 PY 2001 VL 90 IS 6 BP 2764 EP 2772 DI 10.1063/1.1394896 PG 9 WC Physics, Applied SC Physics GA 466LR UT WOS:000170647500020 ER PT J AU Urban, TJ Pekker, T Tapley, BD Kruizinga, GL Shum, CK AF Urban, TJ Pekker, T Tapley, BD Kruizinga, GL Shum, CK TI A multiyear intercomparison of wet troposphere corrections from TOPEX/Poseidon, ERS-1, and ERS-2 Microwave Radiometers and the European Centre for Medium-Range Weather Forecasts model SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA-LEVEL VARIATIONS; ALTIMETER DATA; TOPEX AB Wet troposphere corrections to altimeter measurements calculated from the TOPEX/Poseidon (T/P) Microwave Radiometer (TMR) and the ERS-1 and ERS-2 Microwave Radiometers (EMR I and EMR2) are compared to each other and to European Centre for Medium-Range Weather Forecasts (ECMWF) model data. The most recently published correction algorithm for the EMR1 data [Stum et al., 1998] is applied. The suggested drift correction for TMR data [Keihm et al., 1998, 2000] is also evaluated. The corrected EMR1 data (1991-1996) produce a global (to +/- 66 degrees the T/P latitude range) long-term mean wet troposphere correction 6 and 13 mm lower than TMR and ECMWF, respectively. The EMR2 data (1995-1999) yield a mean wet troposphere correction 2 and 9 mm lower than TMR and ECMWF, respectively. After removing mean differences all three microwave radiometers reproduce similar long-term zonal wet troposphere corrections compared to the ECMWF model (10-14 mm rms) and to each other (5-9 nim rms) with some zonally periodic differences, most < 10 mm. The ECMWF model shows variations compared to the radiometers of over 30 mm before 1995, about 20-30 mm from 1995 to 1997, and up to 20 mm from 1998 to 1999. The intersatellite differences include a latitudinally dependent annual signal, reaching 10 nun in amplitude. Before correcting for the TMR drift there exists a global relative TMR-EMR1 drift of -1.6 +/- 0.4 mm y(-1), from 1992 to 1996. After correcting for the TMR drift the TMR-EMR I trend is reduced to -0.4 +/- 0.2 mm. y(-1), supporting the TMR drift correction. The TMR-EMR2 trend changes sign (direction) after an anomaly that occurred in one of the EMR2 brightness temperatures during June 1996. Before the anomaly, with (without) the TMR correction the relative TMR-EMR2 trend is -3.0 +/- 1.9 (4.0 +/- 2.1) nun y(-1), again supporting the TMR drift correction. After the anomaly, through 1997 the TMR-EMR trend is 3.7 +/- 1.2 mm y(-1), and from 1998 to 1999 it is 0.8 +/- 0.6 mm y(-1). C1 Univ Texas, Ctr Space Res, Austin, TX 78759 USA. NASA, Jet Prop Lab, Pasadena, CA 91109 USA. Ohio State Univ, Dept Civil & Environm Engn & Geodet Sci, Columbus, OH 43210 USA. RP Urban, TJ (reprint author), Univ Texas, Ctr Space Res, 3925 W Braker Lane,Suite 200, Austin, TX 78759 USA. NR 40 TC 8 Z9 9 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 SEP 15 PY 2001 VL 106 IS C9 BP 19657 EP 19669 DI 10.1029/2000JC000486 PG 13 WC Oceanography SC Oceanography GA 471YT UT WOS:000170956800011 ER PT J AU Marcinkevicius, S Gaarder, A Leon, R AF Marcinkevicius, S Gaarder, A Leon, R TI Rapid carrier relaxation by phonon emission in In0.6Ga0.4As/GaAs quantum dots SO PHYSICAL REVIEW B LA English DT Article ID ELECTRONIC-STRUCTURE; ENERGY RELAXATION; OPTICAL PHONONS; AUGER PROCESSES; EXCITED-STATES; HOT CARRIERS; CAPTURE; GAAS; MECHANISM; ENSEMBLE AB Carrier transfer into quantum dots has been investigated by time-resolved photoluminescence spectroscopy in a set of In0.6Ga0.4As/GaAs quantum dot structures with gradually changing interband transition and intraband level energies. Quantum dot energy levels were tuned by thermal compositional disordering of the inter-face. Time-resolved photoluminescence for low photoexcited carrier densities show efficient electron relaxation by LO phonon emission for samples in which the electron energy level separation is close to the LO phonon energy. Slower carrier transfer in samples with abrupt quantum dot/barrier interfaces is also found, the latter is attributed to strain-induced or compositional potential barriers at the quantum dot inter-face. C1 Royal Inst Technol, Dept Phys Opt, S-10044 Stockholm, Sweden. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Marcinkevicius, S (reprint author), Royal Inst Technol, Dept Phys Opt, S-10044 Stockholm, Sweden. NR 29 TC 18 Z9 18 U1 0 U2 2 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 SEP 15 PY 2001 VL 64 IS 11 AR 115307 DI 10.1103/PhysRevB.64.115307 PG 5 WC Physics, Condensed Matter SC Physics GA 474ZG UT WOS:000171136700071 ER PT J AU de Oliveira, HP Joras, SE AF de Oliveira, HP Joras, SE TI Perturbations in warm inflation SO PHYSICAL REVIEW D LA English DT Article ID COSMOLOGICAL PERTURBATIONS; DENSITY PERTURBATIONS; THERMAL DISSIPATION; SCENARIO; SPECTRA; SCALAR; MODELS AB Warm inflation is an interesting possibility to describe the early universe, whose basic feature is the absence, at least in principle, of a preheating or reheating phase. Here we analyze the dynamics of warm inflation generalizing the usual slow-roll parameters that are useful for characterizing the inflationary phase. We study the evolution of entropy and adiabatic perturbations, where the main result is that for a very small amount of dissipation the entropy perturbations can be neglected and the purely adiabatic perturbations will be responsible for the primordial spectrum of inhomogeneities. Taking into account the Cosmic Background Explorer Differential Microwave Radiometer data of the cosmic microwave background anisotropy as well as the fact that the interval of inflation for which the scales of astrophysical interest cross outside the Hubble radius is about 50 e-folds before the end of inflation, we could estimate the magnitude of the dissipation term. It is also possible to show that at the end of inflation the universe is hot enough to provide a smooth transition to the radiation era. C1 Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Estado Rio de Janeiro, Inst Fis, Dept Fis Teor, BR-20550013 Rio De Janeiro, Brazil. Brown Univ, Dept Phys, Providence, RI 02912 USA. RP de Oliveira, HP (reprint author), Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, POB 500, Batavia, IL 60510 USA. EM henrique@fnal.gov; joras@het.brown.edu RI Joras, Sergio/M-9230-2014 NR 22 TC 36 Z9 36 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 SEP 15 PY 2001 VL 64 IS 6 AR 063513 DI 10.1103/PhysRevD.64.063513 PG 8 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 472HN UT WOS:000170978200019 ER PT J AU Lee, TJ Dateo, CE AF Lee, TJ Dateo, CE TI Towards the synthesis of the high energy density material TdN4: excited electronic states SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; TETRAHEDRAL N-4; CONTRACTION; N-2(-) AB Vertical electronic excitation energies for singlet states have been computed for the high energy density material TdN4 in order to assess synthetic routes that originate from excited states of N-2 molecules. Based on linear response coupled-cluster calculations, the lowest six excited states are 9.35(1 T-1(1)), 10.01(1 T-1(2)), 10.04(1 (1)A(2)), 10.07(1 E-1), 10.12(2 T-1(1)), and 10.42(2 T-1(2)) eV above the ground state. Comparison with the energies of excited states of N-2 + N-2 fragments, leads us to propose that the most likely synthetic route for TdN4 involving this mechanism arises from combination of two bound quintet states of N-2. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Eloret Corp, Moffett Field, CA 94035 USA. RP Lee, TJ (reprint author), NASA, Ames Res Ctr, MS230-3, Moffett Field, CA 94035 USA. RI Lee, Timothy/K-2838-2012 NR 25 TC 19 Z9 20 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 SEP 14 PY 2001 VL 345 IS 3-4 BP 295 EP 302 DI 10.1016/S0009-2614(01)00866-1 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 479LD UT WOS:000171405100014 ER PT J AU Mjolsness, E DeCoste, D AF Mjolsness, E DeCoste, D TI Machine learning for science: State of the art and future prospects SO SCIENCE LA English DT Editorial Material ID PREDICTION AB Recent advances in machine learning methods, along with successful applications across a wide variety of fields such as planetary science and bioinformatics, promise powerful new tools for practicing scientists. This viewpoint highlights some useful characteristics of modern machine learning methods and their relevance to scientific applications. We conclude with some speculations on near-term progress and promising directions. C1 CALTECH, Jet Prop Lab, Machine Learning Syst Grp, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, Machine Learning Syst Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM mjolsness@jpl.nasa.gov NR 15 TC 93 Z9 108 U1 6 U2 33 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 EI 1095-9203 J9 SCIENCE JI Science PD SEP 14 PY 2001 VL 293 IS 5537 BP 2051 EP + DI 10.1126/science.293.5537.2051 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 473FB UT WOS:000171028700064 PM 11557883 ER PT J AU Chaban, GM Gerber, RB Janda, KC AF Chaban, GM Gerber, RB Janda, KC TI Transition from hydrogen bonding to ionization in (HCl)(n)(NH(3))(n) and (HCl)n(H2O)(n) clusters: Consequences or anharmonic vibrational spectroscopy SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID CORRELATED MOLECULAR CALCULATIONS; CONSISTENT-FIELD APPROACH; GAUSSIAN-BASIS SETS; PROTON-TRANSFER; WATER-MOLECULES; GAS-PHASE; AB-INITIO; CRYSTALLINE ICE; HCL; AMMONIA AB Anharmonic vibrational frequencies and intensities are calculated for 1:1 and 2:2 (HCl)(n)(NH(3))(n) and (HCl)(n-)(H(2)O)(n) complexes, employing the correlation-corrected vibrational self-consistent field method with ab initio potential surfaces at the MP2/TZP computational level. In this method, the anharmonic coupling between all vibrational modes is included, which is found to be important for the systems studied. For the 4:4 (HCL)(n)- (H(2)O)(n) complex, the vibrational spectra are calculated at the harmonic level, and anharmonic effects are estimated. Just as the (HCl)(n)(NH(3))(n) Structure switches from hydrogen-bonded to ionic for n = 2, the (HCl)(n)-(H(2)O)(n) switches to ionic structure for n = 4. For (HCl)(2)(H(2)O)2, the lowest energy structure corresponds to the hydrogen-bonded form. However, configurations of the ionic form are separated from this minimum by a barrier of less than an O-H stretching quantum. This suggests the possibility of experiments on ionization dynamics using infrared excitation of the hydrogen-bonded form. The strong cooperative effects on the hydrogen bonding, and concomitant transition to ionic bonding, makes an accurate estimate of the large anharmonicity crucial for understanding the infrared spectra of these systems. The anharmonicity is typically of the order of several hundred wavenumbers for the proton stretching motions involved in hydrogen or ionic bonding, and can also be quite large for the intramolecular modes. In addition, the large cooperative effects in the 2:2 and higher order (HCl)(n)(H(2)O)(n) Complexes may have interesting implications for solvation of hydrogen halides at ice surfaces. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. Univ Calif Irvine, Inst Surface & Interface Sci, Irvine, CA 92697 USA. Hebrew Univ Jerusalem, Dept Phys Chem, IL-91904 Jerusalem, Israel. Hebrew Univ Jerusalem, Fritz Haber Res Ctr, IL-91904 Jerusalem, Israel. RP Chaban, GM (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. EM chaban@pegasus.arc.nasa.gov NR 43 TC 77 Z9 77 U1 1 U2 12 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD SEP 13 PY 2001 VL 105 IS 36 BP 8323 EP 8332 DI 10.1021/jp011567k PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 472RG UT WOS:000170998300009 ER PT J AU Sheth, RK Diaferio, A Hui, L Scoccimarro, R AF Sheth, RK Diaferio, A Hui, L Scoccimarro, R TI On the streaming motions of haloes and galaxies SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : clusters : general; cosmology : theory; dark matter ID PAIRWISE VELOCITY DISPERSION; ANALYTIC MODEL; UNIVERSE AB A simple model is described of how objects of different masses stream towards each other as they cluster gravitationally. The model shows how the mean streaming velocity of dark matter particles is related to the motions of the parent dark matter haloes. It also provides a reasonably accurate description of how the pairwise velocity dispersion of dark matter particles differs from that of the parent haloes. The analysis is then extended to describe the streaming motions of galaxies. This shows explicitly that the streaming motions measured in a given galaxy sample depend on how the sample was selected, and shows how to account for this dependence on sample selection. In addition, we show that the pairwise dispersion should also depend on sample type. Our model predicts that, on small scales, redshift-space distortions should affect red galaxies more strongly than blue. C1 NASA, Fermilab Astrophys Grp, Batavia, IL 60510 USA. Univ Turin, Dipartimento Fis Gen Amedeo Avogadro, I-10124 Turin, Italy. Columbia Univ, Dept Phys, New York, NY 10027 USA. Inst Adv Study, Sch Nat Sci, Princeton, NJ 08540 USA. RP Sheth, RK (reprint author), NASA, Fermilab Astrophys Grp, MS 209, Batavia, IL 60510 USA. NR 21 TC 49 Z9 50 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 SEP 11 PY 2001 VL 326 IS 2 BP 463 EP 472 DI 10.1046/j.1365-8711.2001.04457.x PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475UL UT WOS:000171186400010 ER PT J AU Brown, P Cooke, B AF Brown, P Cooke, B TI Model predictions for the 2001 Leonids and implications for Earth-orbiting satellites SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE comets : individual : 55P/Tempel; Tuttle; meteors, meteoroids ID STREAM AB A numerical model of the Leonid stream is developed, based on an earlier model which has been applied to the Perseid stream. The results for this model are applied to the 2001 Leonid return. By examining the full three-dimensional dispersion of individual 'streamlets' released from the Leonid parent comet, 55P/Tempel-Tuttle, we have derived an estimate for the temporal change in spatial density of each trail. Using this result along with an estimate for the location of the centres for individual streamlets and fits to previous Leonid storm profiles, we estimate that the activity from the shower will be broad and relatively strong (zenithal hourly rates perhaps in excess of 1000). In particular, streamlets from the 1766 and 1799 ejections contribute to activity peaking near 10 and 12 UT on 2001 November 18, respectively. Additional older material from 1633, 1666 and 1699, as well as more recent ejections from 1866 and 1833, contributes to a much broader secondary maximum near 17.5 UT on November 18. Comparison with other published models of predicted Leonid activity in 2001 shows general agreement in terms of timing, but the models differ significantly in terms of the relative magnitude of the activity (which other models suggest will be larger). Significant anisotropy in the impact hazard exists for satellites in the geostationary belt, with those over western longitudes most likely to be affected. Integrated fluences for the 2001 Leonid return suggest a hazard of order one magnitude greater than occurred for the 1999 Leonid storm. C1 Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada. Comp Sci Corp, Engn Directorate, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Brown, P (reprint author), Los Alamos Natl Lab, EES-8, Los Alamos, NM 87545 USA. NR 16 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 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD SEP 11 PY 2001 VL 326 IS 2 BP L19 EP L22 DI 10.1046/j.1365-8711.2001.04765.x PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 475UL UT WOS:000171186400002 ER PT J AU Lee, J Watts, J Howell, L AF Lee, J Watts, J Howell, L TI Simulations of a thin sampling calorimeter with GEANT/FLUKA SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article DE galactic cosmic ray spectrum; calorimeter; scintillating fiber; GEANT simulation ID PRIMARY COSMIC-RAYS; SPECTRA AB The Advanced Cosmic-ray Composition Experiment for the Space Station (ACCESS) will investigate the origin, composition and acceleration mechanism of cosmic rays by measuring the elemental composition of the cosmic rays up to 10(15) eV. These measurements will be made with a thin ionization calorimeter and a transition radiation detector. This paper reports studies of a thin sampling calorimeter concept for the ACCESS thin ionization calorimeter. For the past year, a Monte Carlo simulation study of a thin sampling calorimeter (TSC) design has been conducted to predict the detector performance and to design the system for achieving the ACCESS scientific objectives. Simulation results show that the detector energy resolution function resembles a Gaussian distribution and the energy resolution of TSC is about 40%. In addition, simulations of the detector's response to an assumed broken power law cosmic ray spectrum in the region where the 'knee' of the cosmic ray spectrum is believed to occur have been conducted and clearly show that a thin sampling calorimeter can provide sufficiently accurate estimates of the spectral parameters to meet the science requirements of ACCESS. (C), 2001 Elsevier Science B.V. All rights reserved. C1 NASA, MSFC, Huntsville, AL 35812 USA. RP Watts, J (reprint author), NASA, MSFC, SD50, Huntsville, AL 35812 USA. EM jeongin.lee@msfc.nasa.gov; john.watts@msfc.nasa.gov; leonard.howell@msfc.nasa.gov NR 16 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 EI 1872-9576 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD SEP 11 PY 2001 VL 470 IS 3 BP 500 EP 511 DI 10.1016/S0168-9002(01)00792-6 PG 12 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 474PH UT WOS:000171115600004 ER PT J AU Hays, CC Schroers, J Johnson, WL Rathz, TJ Hyers, RW Rogers, JR Robinson, MB AF Hays, CC Schroers, J Johnson, WL Rathz, TJ Hyers, RW Rogers, JR Robinson, MB TI Vitrification and determination of the crystallization time scales of the bulk-metallic-glass-forming liquid Zr58.5Nb2.8Cu15.6Ni12.8Al10.3 SO APPLIED PHYSICS LETTERS LA English DT Article ID PHASE-SEPARATION; NI; ZR41.2TI13.8CU12.5NI10.0BE22.5; REGION AB The crystallization kinetics of Zr58.5Nb2.8Cu15.6Ni12.8Al10.3 were studied in an electrostatic levitation (ESL) apparatus. The measured critical cooling rate is 1.75 K/s. Zr58.5Nb2.8Cu15.6Ni12.8Al10.3 is the first bulk-metallic-glass-forming liquid that does not contain beryllium to be vitrified by purely radiative cooling in the ESL. Furthermore, the sluggish crystallization kinetics enable the determination of the time-temperature-transformation (TTT) diagram between the liquidus and the glass transition temperatures. The shortest time to reach crystallization in an isothermal experiment; i.e., the nose of the TTT diagram is 32 s. The nose of the TTT diagram is at 900 K and positioned about 200 K below the liquidus temperature. (C) 2001 American Institute of Physics. C1 CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. Univ Alabama, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Hays, CC (reprint author), CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. RI Hyers, Robert/G-3755-2010 NR 16 TC 52 Z9 52 U1 1 U2 19 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 SEP 10 PY 2001 VL 79 IS 11 BP 1605 EP 1607 DI 10.1063/1.1398605 PG 3 WC Physics, Applied SC Physics GA 469EB UT WOS:000170800700007 ER PT J AU Hartman, RC Villata, M Balonek, TJ Bertsch, DL Bock, H Bottcher, M Carini, MT Collmar, W De Francesco, G Ferrara, EC Heidt, J Kanbach, G Katajainen, S Koskimies, M Kurtanidze, OM Lanteri, L Lawson, A Lin, YC Marscher, AP McFarland, JP McHardy, IM Miller, HR Nikolashvili, M Nilsson, K Noble, JC Nucciarelli, G Ostorero, L Pursimo, T Raiteri, CM Rekola, R Savolainen, T Sillanpaa, A Smale, A Sobrito, G Takalo, LO Thompson, DJ Tosti, G Wagner, SJ Wilson, JW AF Hartman, RC Villata, M Balonek, TJ Bertsch, DL Bock, H Bottcher, M Carini, MT Collmar, W De Francesco, G Ferrara, EC Heidt, J Kanbach, G Katajainen, S Koskimies, M Kurtanidze, OM Lanteri, L Lawson, A Lin, YC Marscher, AP McFarland, JP McHardy, IM Miller, HR Nikolashvili, M Nilsson, K Noble, JC Nucciarelli, G Ostorero, L Pursimo, T Raiteri, CM Rekola, R Savolainen, T Sillanpaa, A Smale, A Sobrito, G Takalo, LO Thompson, DJ Tosti, G Wagner, SJ Wilson, JW TI Day-scale variability of 3C 279 and searches for correlations in gamma-ray, x-ray, and optical bands SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : observations; quasars : individual (3C 279) ID HIGH-ENERGY EMISSION; COMPARISON STARS; BLAZAR 3C-279; RADIATION; MODELS; EXTINCTION; PHOTOMETRY; OBJECTS; QUASARS; EGRET AB Light curves of 3C 279 are presented in optical (R band), X-rays (RXTE/PCA), and gamma rays (CGRO/ EGRET) for 1999 January-February and 2000 January-March. During both of those epochs the gamma -ray levels were high and all three observed bands demonstrated substantial variation, on timescales as short as 1 day. Correlation analyses provided no consistent pattern, although a rather significant optical/gamma -ray correlation was seen in 1999, with a gamma -ray lag of similar to2.5 days, and there are other suggestions of correlations in the light curves. For comparison, correlation analysis is also presented for the gamma -ray and X-ray light curves during the large gamma ray flare in 1996 February and the two gamma -bright weeks leading up to it; the correlation at that time was strong, with a gamma -ray/X-ray offset of no more than 1 day. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Osserv Astron Torino, I-10025 Pino Torinese, Italy. Colgate Univ, Dept Phys & Astron, Hamilton, NY 13346 USA. Landessternwarte Konigstuhl, D-69117 Heidelberg, Germany. Rice Univ, Dept Space Phys & Astron, Houston, TX 77005 USA. Western Kentucky Univ, Dept Phys & Astron, Bowling Green, KY 42104 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. Georgia State Univ, Dept Phys & Astron, Atlanta, GA 30303 USA. Tuorla Observ, FIN-21500 Piikkio, Finland. Astrophys Inst Potsdam, D-14482 Potsdam, Germany. Univ Southampton, Dept Phys & Astron, Southampton SO9 5NH, Hants, England. Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA. Boston Univ, Inst Astrophys Res, Boston, MA 02215 USA. Abastumani Observ, GE-383762 Abastumani, Rep of Georgia. Osservatorio Astron Perugia, I-06123 Perugia, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hartman, RC (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. RI Thompson, David/D-2939-2012; Tosti, Gino/E-9976-2013; Kurtanidze, Omar/J-6237-2014; OI Thompson, David/0000-0001-5217-9135; Ostorero, Luisa/0000-0003-3983-5980; Villata, Massimo/0000-0003-1743-6946; Savolainen, Tuomas/0000-0001-6214-1085; Raiteri, Claudia Maria/0000-0003-1784-2784 NR 42 TC 42 Z9 43 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2001 VL 558 IS 2 BP 583 EP 589 DI 10.1086/322462 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472TW UT WOS:000171001900012 ER PT J AU Dickens, JE Langer, WD Velusamy, T AF Dickens, JE Langer, WD Velusamy, T TI Small-scale abundance variations in TMC-1: Dynamics and hydrocarbon chemistry SO ASTROPHYSICAL JOURNAL LA English DT Article DE astrochemistry; ISM : clouds; ISM : individual (TMC-1); ISM : molecules; radio lines : ISM ID MOLECULAR CLOUD-1 TMC-1; CARBON-CHAIN MOLECULES; STAR-FORMING REGIONS; DUST EMISSION; CORE L1544; DEPLETION; SEARCH; PROTOSTARS; OPHIUCHUS; PYRROLE AB We present high spectral resolution observations of eighteen molecules, including high-quality maps of CCS and HC7N in TMC-1, using NASA's Deep Space Network 70 m antenna to study the interaction between cloud dynamics and chemistry. Other molecules shown in our study are (CO)-O-18, NH3, CS, C3S, C3H2, H2C3, H2C4, H2C6, HC3N, HC5N, DC5N, HC9N, C4H, C5H, C6H, and a successful detection of the rare C8H molecule. In addition, we have searched for and set meaningful abundance limits on several carbon chain and ring molecules such as C7H, H2C5, c-H2C5, and biogenic molecules such as pyrrole and glycine. All the species observed in TMC-1 show large spectral-line variations in both intensity and shape over extremely small scales (similar to 0.03 pc). Maps of CCS and HC7N display abundance ratio variations of 3-5 along individual lines of sight. The high degree of clumpiness, transient nature of clumps, and gas-phase enrichment adequately explain the " early-time " chemistry and the molecular complexity in TMC-1. This enrichment has interesting implications for hydrocarbon chemistry in TMC-1, and presumably other clumpy, dark clouds. Specifically, the large number of clumps at various stages of early-time chemical evolution increases the chances for detection of complex hydrocarbons, since the probability of observing a clump at the time of peak abundance for a given molecular species is increased. We suggest two mechanisms for explaining the small-scale variations : (1) the passage of MHD waves in a clumpy medium and (2) grain impacts during clump-clump collisions. In the quiescent region far from any protostar, the MHD activity can be generated locally by clump collisions. The passage of MHD waves helps maintain early-time chemistry in the clumps. Both mechanisms provide enough energy to raise grain temperatures from 10 K to T-crit similar to 30 K, sufficient to cause reactive radical explosions in grain mantles and thermal desorption. In this manner, the mantle injection causes TMC-1 to exhibit some aspects of " hot-core " chemistry, as seen in more massive star-forming regions. The transient nature of the clumps and the mantle-driven chemistry make TMC-1 a good target for future searches of complex molecular species. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-506, Pasadena, CA 91109 USA. EM james.dickens@jpl.nasa.gov; william.langer@jpl.nasa.gov; velu@rams.jpl.nasa.gov NR 34 TC 40 Z9 40 U1 1 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2001 VL 558 IS 2 BP 693 EP 701 DI 10.1086/322292 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472TW UT WOS:000171001900020 ER PT J AU Gibb, EL Whittet, DCB Chiar, JE AF Gibb, EL Whittet, DCB Chiar, JE TI Searching for ammonia in grain mantles toward massive young stellar objects SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM; ISM : abundances; ISM : molecules; line : profiles ID MIDINFRARED SPECTRAL EVOLUTION; ASTROPHYSICAL ICE MIXTURES; INFRARED BAND STRENGTHS; MAIN-SEQUENCE STARS; 3 MICRON SPECTRA; NGC 2264 IRS; ABSORPTION FEATURES; SWS OBSERVATIONS; OBSERVATIONAL CONSTRAINTS; LABORATORY SIMULATIONS AB We present a study of the mid-infrared spectral regions of 17 objects observed with the Short-Wavelength Spectrometer on the Infrared Space Observatory (ISO SWS) in a search for the presence of the elusive NH3 solid-state absorption features at 2.96 and 9.0 mum. We compare the 3 mum profile with laboratory spectra of pure water and water/ammonia mixtures from the Leiden Molecular Astrophysics database. We determine that the shape of the 3 mum water feature alone does not present conclusive evidence of the presence or lack of NH3 ice on dust grain mantles because of the large number of unknown physical parameters that influence the 3 mum water profile: grain size distribution, grain shape, mantle composition, thermal history, and geometrical effects. In the 9 mum region, the presence of NH3 is characterized by a sudden change in slope at 8.5 mum and a peak at 9.0 mum within the silicate profile. Of the 16 silicate features studied, four show evidence of a 9 mum ammonia feature, including the previously reported detections in ground-based observations of NGC 7538 IRS 9, and SWS observations of W33 A. Upper limits are found for the remaining objects. Why NH3, which is an abundant gas-phase molecule in cold, dense cores, is not apparently present in significant amounts on most grain mantles, where it is expected to freeze out, is currently a mystery. C1 Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Rensselaer Polytech Inst, New York Ctr Studies Origins Life, Troy, NY 12180 USA. NR 75 TC 43 Z9 47 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2001 VL 558 IS 2 BP 702 EP 716 DI 10.1086/322291 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472TW UT WOS:000171001900021 ER PT J AU Allen, GE Petre, R Gotthelf, EV AF Allen, GE Petre, R Gotthelf, EV TI X-ray synchrotron emission from 10-100 TeV cosmic-ray electrons in the supernova remnant SN 1006 SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; cosmic rays; ISM : individual (SN 1006); radiation mechanisms : nonthermal; supernova remnants; X-rays : general ID PARTICLE-ACCELERATION; RADIO OBSERVATIONS; ABSORPTION-LINES; RX J1713.7-3946; CASSIOPEIA-A; LUPUS REGION; SN-1006; SPECTRUM; ORIGIN; SHOCKS AB We present the results of a joint spectral analysis of RXTE PCA, ASCA SIS, and ROSAT PSPC data of the supernova remnant SN 1006. This work represents the first attempt to model both the thermal and nonthermal X-ray emission over the entire X-ray energy band from 0.12 to 17 keV. The thermal flux is described by a nonequilibrium ionization model with an electron temperature kT(e) = 0.6 keV, an ionization timescale n(0)t = 9x10(9) cm(-3) s, and a relative elemental abundance of silicon that is 10-18 times larger than the solar abundance. The nonthermal X-ray spectrum is described by a broken power law model with low- and high-energy photon indices Gamma (1) = 2.1 and Gamma (2) = 3.0, respectively. Since the non- thermal X-ray spectrum steepens with increasing energy, the results of the present analysis corroborate previous claims that the nonthermal X-ray emission is produced by synchrotron radiation. We argue that the magnetic field strength is significantly larger than previous estimates of about 10 muG and arbitrarily use a value of 40 muG to estimate the parameters of the cosmic-ray electron, proton, and helium spectra of the remnant. The results for the ratio of the number densities of protons and electrons (R=160 at 1 GeV), the total energy in cosmic rays (E-cr = 1x10(50) ergs), and the spectral index of the electrons at 1 GeV (Gamma (e) = 2.14 +/-0.12) are consistent with the hypothesis that Galactic cosmic rays are accelerated predominantly in the shocks of supernova remnants. Yet, the remnant may or may not accelerate nuclei to energies as high as the energy of the "knee" depending on the reason why the maximum energy of the electrons is only 10 TeV. C1 MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. RP Allen, GE (reprint author), MIT, Ctr Space Res, 77 Massachusetts Ave,NE 80-6029, Cambridge, MA 02139 USA. NR 84 TC 62 Z9 62 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2001 VL 558 IS 2 BP 739 EP 752 DI 10.1086/322470 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472TW UT WOS:000171001900024 ER PT J AU Habbal, SR Woo, R Arnaud, J AF Habbal, SR Woo, R Arnaud, J TI On the predominance of the radial component of the magnetic field in the solar corona SO ASTROPHYSICAL JOURNAL LA English DT Article DE polarization; solar wind; Sun : corona; Sun : infrared; Sun : magnetic delds ID POLARIZATION; LINES; SUN AB Polarimetric measurements of the corona out to 2 R-circle dot in the Fe XIII 10747 Angstrom line, the strongest of the iron forbidden lines, are placed for the first time in the context of spatially resolved images of coronal density structures. These measurements, which are the only tool currently available to yield the direction of the magnetic field, date to 1980, the only year when they were available with polarized brightness images of the corona. Through this comparison, the observed predominance of the radial component of the coronal magnetic field, discovered over three decades ago from eclipse observations and established systematically by Arnaud, is shown to point to the coexistence of two magnetic field components in the corona: a nonradial field associated with the large-scale structures known as streamers and a more pervasive radial magnetic field. This finding suggests that these two components are the coronal counterparts of the strong- and weak-field components recently observed in the quiet-Sun photospheric field and supported by recent theoretical investigations of the solar dynamo. C1 Univ Wales, Aberystwyth SY23 3BZ, Dyfed, Wales. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Toulouse 3, Astrophys Lab, F-31062 Toulouse, France. RP Habbal, SR (reprint author), Univ Wales, Aberystwyth SY23 3BZ, Dyfed, Wales. NR 29 TC 24 Z9 24 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2001 VL 558 IS 2 BP 852 EP 858 DI 10.1086/322308 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472TW UT WOS:000171001900032 ER PT J AU Sato, J AF Sato, J TI Observation of the coronal hard X-ray sources of the 1998 April 23 flare SO ASTROPHYSICAL JOURNAL LA English DT Article DE plasmas; Sun : flares; Sun : X-rays, gamma rays ID SOLAR-A MISSION; TELESCOPE AB We analyzed Hard X-Ray Telescope observations of an X1.2 flare on 1998 April 23. This flare is one of the best examples for studying coronal hard X-ray sources due to the intensity of the emission and the occultation of the footpoints. In this flare, coronal hard X-ray sources composed of both thermal and nonthermal emissions showed complex structure unlike any previously observed. Dominant thermal and nonthermal sources do not come from the same loop-top region. Nonthermal sources include two sources in the low corona (similar to2.7 x 10(3) km) and an extended source in the high corona (similar to5 x 10(4) km). These observations of nonthermal coronal sources suggest that energetic phenomena occur in the low corona at first, and energized electrons are then injected into a high coronal region. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sato, J (reprint author), Montana State Univ, Dept Phys, POB 173840, Bozeman, MT 59717 USA. NR 9 TC 15 Z9 15 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2001 VL 558 IS 2 BP L137 EP L140 DI 10.1086/323616 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472UE UT WOS:000171002700015 ER PT J AU Lundgren, P Usai, S Sansosti, E Lanari, R Tesauro, M Fornaro, G Berardino, P AF Lundgren, P Usai, S Sansosti, E Lanari, R Tesauro, M Fornaro, G Berardino, P TI Modeling surface deformation observed with synthetic aperture radar interferometry at Campi Flegrei caldera SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID GROUND DEFORMATIONS; UNREST EPISODES; GRAVITY; ETNA; VOLCANISM; EVOLUTION; MOVEMENT; AREAS AB Satellite radar interferometry of Campi Flegrei caldera, Italy, reveals a pattern of subsidence during the period 1993-1998. Interferograms spanning the first half of the observation period (1993-1995) have a lower amplitude and average rate of subsidence than those spanning either the second half (1995-1998) or the entire period (1993-1998), consistent with observations of a slowing down or reversal of subsidence during the first half of the observation period. We calculate a time series of deformation images relative to a reference image on the basis of a least squares inversion. During the observation period the maximum subsidence progresses at a rate of roughly 38 +/- 2 mm/yr, with periods of no apparent subsidence in late 1996 to early 1997. To understand the characteristics of the source, we jointly invert pairs of ascending and descending differential interferograms spanning similar time intervals (first half, second half, or entire interval) of the period 1993-1998. In each case the joint inversion fits the two unwrapped interferograms with a similar subhorizontal rectangular contracting tensile dislocation striking roughly N98 degreesE with dimensions similar to 4 x 2 km and located beneath the city of Pozzuoli at a depth of 2.5-3 km. Inversion for a spheroidal or Mogi point source also produced reasonable fits but with progressively poorer overall fits to the data, respectively. Our inversion assuming a simple source in an elastic half-space does not include the possible effects of local structure on the surface deformation, a factor that may also reduce the need for an asymmetric source. The solution we find is consistent with other studies that suggest subsidence due to hydrothermal diffusion as the primary deformation mechanism during this phase of caldera deflation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Delft Univ Technol, Dept Earth & Oceanog Sci, NL-2629 JA Delft, Netherlands. CNR, Ist Ric Elettromagnetismo & Componenti Elettron, I-80124 Naples, Italy. RP Lundgren, P (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 300-233, Pasadena, CA 91109 USA. EM paul@weed.jpl.nasa.gov; Stefania.Usai@lr.tudelft.nl; sansosti@irece.na.cnr.it; lanari@irece.na.cnr.it; manlio@irece.na.cnr.it; fornaro@irece.na.cnr.it; berardp@irece.na.cnr.it RI Sansosti, Eugenio/F-7297-2011; OI Sansosti, Eugenio/0000-0002-5051-4056; Fornaro, Gianfranco/0000-0002-1679-607X NR 40 TC 86 Z9 87 U1 1 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD SEP 10 PY 2001 VL 106 IS B9 BP 19355 EP 19366 DI 10.1029/2001JB000194 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 472FV UT WOS:000170973600011 ER PT J AU Ellison, J Ahmadi, G Kehoe, M AF Ellison, J Ahmadi, G Kehoe, M TI Passive vibration control of airborne equipment using a circular steel ring SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID ISOLATION SYSTEM AB Vibration isolation is needed to protect avionics equipment from adverse aircraft vibration environments. Passive isolation is the simplest means to achieve this goal. The system used here consists of a circular steel ring with a lump mass on top and exposed to base excitation. Sinusoidal and filtered zero-mean Gaussian white noise are used to excite the structure and the acceleration response spectra at the top of the ring are computed. An experiment is performed to identify the natural frequencies and modal damping of the circular ring. Comparison is made between the analytical and experimental results and good agreement is observed. The ring response is also evaluated with a concentrated mass attached to the top of the ring. The effectiveness of the ring in isolating the equipment from base excitation is studied. The acceleration response spectra of a single-degree-of-freedom (s.d.o.f.) system attached to the top of the ring are evaluated and the results are compared with those exposed directly to the base excitation. It is shown that a property designed ring could effectively protect the avionics from possible damaging excitation levels. (C) 2001 Academic Press. C1 Clarkson Univ, Dept Mech & Aeronaut Engn, Potsdam, NY 13699 USA. NASA, Dryden Flight Res Facil, Edwards AFB, CA 93523 USA. RP Ellison, J (reprint author), Clarkson Univ, Dept Mech & Aeronaut Engn, Potsdam, NY 13699 USA. NR 35 TC 2 Z9 7 U1 0 U2 3 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 SEP 6 PY 2001 VL 246 IS 1 BP 1 EP 28 DI 10.1006/jsvi.2000.3116 PG 28 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 473MY UT WOS:000171049200001 ER PT J AU Munoz, C AF Munoz, C TI Proof-term synthesis on dependent-type systems via explicit substitutions SO THEORETICAL COMPUTER SCIENCE LA English DT Article DE proof synthesis; higher-order unification; explicit substitutions; lambda calculus ID HIGHER-ORDER UNIFICATION; CONFLUENCE PROPERTIES; CALCULUS AB Typed lambda -terms are used as a compact and linear representation of proofs in intuitionistic logic. This is possible since the Curry-Howard isomorphism relates proof-trees with typed lambda -terms. The proofs-as-terms principle can be used to verify the validity of a proof by type checking the lambda -term extracted from the complete proof-tree. In this paper we present a proof synthesis method for dependent-type systems where typed open terms are built incrementally at the same time as proofs are done. This way, every construction step, not just the last one, may be type checked. The method is based on a suitable calculus where substitutions as well as meta-variables are first-class objects. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Mail Stop 132C, Hampton, VA 23681 USA. EM munoz@icase.edu NR 39 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-3975 EI 1879-2294 J9 THEOR COMPUT SCI JI Theor. Comput. Sci. PD SEP 6 PY 2001 VL 266 IS 1-2 BP 407 EP 440 DI 10.1016/S0304-3975(00)00196-1 PG 34 WC Computer Science, Theory & Methods SC Computer Science GA 473KK UT WOS:000171042600013 ER PT J AU Vasquez, RP Jung, CU Kim, JY Park, MS Kim, HJ Lee, SI AF Vasquez, RP Jung, CU Kim, JY Park, MS Kim, HJ Lee, SI TI X-ray photoemission study of the infinite-layer cuprate superconductor Sr0.9La0.1CuO2 SO JOURNAL OF PHYSICS-CONDENSED MATTER LA English DT Article ID HIGH-TEMPERATURE SUPERCONDUCTORS; CHEMICAL-POTENTIAL SHIFT; ONE-DIMENSIONAL SRCUO2; ELECTRONIC-STRUCTURE; PHOTOELECTRON-SPECTROSCOPY; UNDERDOPED LA2-XSRXCUO4; SATELLITE STRUCTURE; EPITAXIAL-FILMS; SPECTRA; YBA2CU3O7-X AB The electron-doped infinite-layer superconductor Sr0.9La0.1CuO2 is studied with x-ray photoemission spectroscopy (XPS). A non-aqueous chemical etchant is shown to effectively remove contaminants and to yield surfaces from which signals intrinsic to the superconductor dominate. These data are compared to measurements from hole-doped La1.85Sr0.15CuO4, from undoped La2CuO4, and from electron-doped Nd1.85Ce0.15CuO4-delta. The Cu 2p core level is more consistent with a lower value of the O 2p --> Cu 3d charge transfer energy Delta than in hole-doped cuprates. A clear Fermi edge is observed in the valence band region. C1 CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. Pohang Univ Sci & Technol, Natl Creat Res Initiat Ctr Superconduct, Pohang 790784, South Korea. Pohang Univ Sci & Technol, Dept Phys, Pohang 790784, South Korea. RP CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. EM richard.p.vasquez@jpl.nasa.gov NR 36 TC 10 Z9 13 U1 0 U2 5 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0953-8984 EI 1361-648X J9 J PHYS-CONDENS MAT JI J. Phys.-Condes. Matter PD SEP 3 PY 2001 VL 13 IS 35 BP 7977 EP 7985 DI 10.1088/0953-8984/13/35/305 PG 9 WC Physics, Condensed Matter SC Physics GA 479QV UT WOS:000171415800010 ER PT J AU Wasfy, TM Noor, AK AF Wasfy, TM Noor, AK TI Visualization of CFD results in immersive virtual environments SO ADVANCES IN ENGINEERING SOFTWARE LA English DT Article DE virtual environment; virtual reality; visualization of fluid flow; object-oriented software; visual simulation; computational fluid dynamics AB An object-oriented event-driven immersive virtual environment (VE) is described for the visualization of computational fluid dynamics (CFD) results. The VE incorporates the following types of primitive software objects: interface objects, support objects, geometric entities, and finite elements. The fluid domain is discretized using either a multi-block structured grid or an unstructured finite element mesh. The VE allows natural 'fly-through' visualization of the model, the CFD grid, and the model's surroundings. In order to help visualize the flow and its effects on the model, the VE incorporates the following objects: stream objects (lines, surface-restricted lines, ribbons, and volumes); colored surfaces; elevation surfaces; surface arrows; global and local iso-surfaces; vortex cores; and separation/attachment surfaces and lines. Most of these objects can be used for dynamically probing the flow. Particles and arrow animations can be displayed on top of stream objects. Primitive response quantities as well as derived quantities can be used. A recursive tree search algorithm is used for real-time point and value search in the CFD grid. (C) 2001 Published by Elsevier Science Ltd. C1 Old Dominion Univ, Ctr Adv Engn Environm, NASA, Langley Res Ctr, Hampton, VA USA. Adv Sci & Automat Corp, Hampton, VA USA. RP Old Dominion Univ, Ctr Adv Engn Environm, NASA, Langley Res Ctr, Mail Stop 201, Hampton, VA USA. EM a.k.noor@larc.nasa.gov NR 24 TC 16 Z9 18 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0965-9978 EI 1873-5339 J9 ADV ENG SOFTW JI Adv. Eng. Softw. PD SEP PY 2001 VL 32 IS 9 BP 717 EP 730 DI 10.1016/S0965-9978(01)00020-5 PG 14 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Engineering, Multidisciplinary SC Computer Science; Engineering GA 465XY UT WOS:000170616300005 ER PT J AU Nelson, DA AF Nelson, DA TI Untitled SO AEROSPACE AMERICA LA English DT Letter C1 NASA, Washington, DC 20546 USA. RP Nelson, DA (reprint author), NASA, Washington, DC 20546 USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD SEP PY 2001 VL 39 IS 9 BP 7 EP 7 PG 1 WC Engineering, Aerospace SC Engineering GA 522HZ UT WOS:000173891600008 ER PT J AU Pecheur, C Visser, W Simmons, R AF Pecheur, C Visser, W Simmons, R TI RIACS workshop on the verification and validation of autonomous and adaptive systems SO AI MAGAZINE LA English DT Editorial Material C1 NASA, Adv Comp Sci Res Inst, Automated Software Engn Grp, Ames, IA USA. Carnegie Mellon Univ, Sch Comp Sci, Pittsburgh, PA 15213 USA. RP Pecheur, C (reprint author), NASA, Adv Comp Sci Res Inst, Automated Software Engn Grp, Ames, IA USA. OI Simmons, Reid/0000-0003-3153-0453 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 USA SN 0738-4602 J9 AI MAG JI AI Mag. PD FAL PY 2001 VL 22 IS 3 BP 107 EP 111 PG 5 WC Computer Science, Artificial Intelligence SC Computer Science GA 633MV UT WOS:000180287800015 ER PT J AU Rose, CP Freedman, R Bauer, M Rich, C Horswill, I Schultz, A Freed, M Vera, A Dautenhahn, K AF Rose, CP Freedman, R Bauer, M Rich, C Horswill, I Schultz, A Freed, M Vera, A Dautenhahn, K TI AAAI 2000 fall symposium series reports SO AI MAGAZINE LA English DT Editorial Material C1 Univ Pittsburgh, Pittsburgh, PA 15260 USA. Northwestern Univ, Evanston, IL 60208 USA. USN, Res Lab, Washington, DC USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Hong Kong, Hong Kong, Hong Kong, Peoples R China. Univ Hertfordshire, Hatfield AL10 9AB, Herts, England. RP Rose, CP (reprint author), Univ Pittsburgh, Pittsburgh, PA 15260 USA. RI Horswill, Ian/B-7175-2009 NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 USA SN 0738-4602 J9 AI MAG JI AI Mag. PD FAL PY 2001 VL 22 IS 3 BP 113 EP 116 PG 4 WC Computer Science, Artificial Intelligence SC Computer Science GA 633MV UT WOS:000180287800016 ER PT J AU Fesq, L Atkins, E Khatib, L Pecheu, C Cohen, PR Stein, LA van Lent, M Laird, J Provetti, A Cao, ST AF Fesq, L Atkins, E Khatib, L Pecheu, C Cohen, PR Stein, LA van Lent, M Laird, J Provetti, A Cao, ST TI AAAI 2001 Spring Symposium Series reports SO AI MAGAZINE LA English DT Editorial Material C1 Univ Texas, El Paso, TX 79968 USA. Univ Michigan, Ann Arbor, MI 48109 USA. Stanford Univ, Stanford, CA 94305 USA. Univ Liverpool, Liverpool L69 3BX, Merseyside, England. Univ Texas, Arlington, TX 76019 USA. Univ Massachusetts, Amherst, MA 01003 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. MIT, Cambridge, MA 02139 USA. Univ Maryland, College Pk, MD 20742 USA. RP Fesq, L (reprint author), Univ Texas, El Paso, TX 79968 USA. RI Provetti, Alessandro/D-4104-2015 OI Provetti, Alessandro/0000-0001-9542-4110 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 USA SN 0738-4602 J9 AI MAG JI AI Mag. PD FAL PY 2001 VL 22 IS 3 BP 117 EP 122 PG 6 WC Computer Science, Artificial Intelligence SC Computer Science GA 633MV UT WOS:000180287800017 ER PT J AU Stein, TP Wade, CE AF Stein, TP Wade, CE TI The catecholamine response to spaceflight: role of diet and gender SO AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM LA English DT Article ID DOWN BED REST; SPACE-FLIGHT; CARDIOVASCULAR-RESPONSE; BLOOD-PRESSURE; METABOLISM; EXERCISE; BALANCE; ENERGY; WOMEN; MEN AB Compared with men, women appear to have a decreased sympathetic nervous system (SNS) response to stress. The two manifestations where the sexual dimorphism has been the most pronounced involve the response of the SNS to fluid shifts and fuel metabolism during exercise. The objectives of this study were to investigate whether a similar sexual dimorphism was found in the response to spaceflight. To do so, we compared catecholamine excretion by male and female astronauts from two similar shuttle missions, Spacelab Life Sciences 1 (SLS1, 1991) and 2 (SLS2, 1993) for evidence of sexual dimorphism. To evaluate the variability of the catecholamine response in men, we compared catecholamine excretion from the two SLS missions against the 1996 Life and Microgravity Sciences Mission (LMS) and the 1973 Skylab missions. Results: No gender- or mission-dependent changes were found with epinephrine. Separating out the SLS1/2 data by gender shows that norepinephrine excretion was essentially unchanged with spaceflight in women (98 +/- 10%; n = 3) and substantially decreased with the men (41 +/- 9%; n = 4, P < 0.05). Data are a percentage of mean preflight value SE. Comparisons among males demonstrated significant mission effects on norepinephrine excretion. After flight, there was a transient increase in norepinephrine but no evidence of any gender-specific effects. We conclude that norepinephrine excretion during spaceflight is both mission and gender dependent. Men show the greater response, with at least three factors being involved, a response to microgravity, energy balance, and the ratio of carbohydrate to fat in the diet. C1 Univ Med & Dent New Jersey, Sch Osteopath Med, Dept Surg, Stratford, NJ 08084 USA. NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. RP Stein, TP (reprint author), Univ Med & Dent New Jersey, Sch Osteopath Med, Dept Surg, 2 Med Ctr Dr, Stratford, NJ 08084 USA. NR 47 TC 13 Z9 13 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0193-1849 J9 AM J PHYSIOL-ENDOC M JI Am. J. Physiol.-Endocrinol. Metab. PD SEP PY 2001 VL 281 IS 3 BP E500 EP E506 PG 7 WC Endocrinology & Metabolism; Physiology SC Endocrinology & Metabolism; Physiology GA 465BZ UT WOS:000170569900011 PM 11500305 ER PT J AU Whang, YC Fairfield, D Lepping, RP Mukai, T Saito, Y Slavin, I Szabo, A AF Whang, YC Fairfield, D Lepping, RP Mukai, T Saito, Y Slavin, I Szabo, A TI Double discontinuities at the magnetotail plasma sheet-lobe boundary SO ANNALES GEOPHYSICAE LA English DT Article DE magnetospheric physics; plasma sheet; space plasma physics; discontinuities; shock waves ID SLOW-MODE SHOCKS; MAGNETIC-FIELD; ROTATIONAL DISCONTINUITY; INTERPLANETARY SPACE; WIND OBSERVATIONS; GEOMAGNETIC TAIL; SOLAR-WIND AB A double discontinuity is a compound structure composed of a slow shock layer and an adjoining rotational discontinuity layer on the postshock side. We use high-resolution data from Geotail and Wind spacecraft to examine the interior structure within the finite thickness of the discontinuity at the plasma sheet-lobe boundary and found that recognizable MHD structures at the boundary can be stand-alone slow shocks or double discontinuities. The plasma density increases significantly and the magnetic field intensity decreases significantly across the interior of the slow shock layer. Through the rotational layer, the magnetic field rotates about the normal direction of the shock surface, as the plasma density and the magnetic field intensity remain nearly unchanged. The rotational angle can vary over a wide range. We notice that the observations of double discontinuities are no less frequent than the observations of stand-alone slow shocks. Identification of slow shocks and double discontinuities infers that plasma and magnetic field lines continuously move across the boundary surface from the lobe into the plasma sheet, and there is a conversion of magnetic field energy into plasma thermal energy through the slow shock layer. The double discontinuities also allows for a rapid rotation of the postshock magnetic field lines immediately behind the shock layer to accommodate the environment of the MHD flow in the plasma sheet region. C1 Catholic Univ Amer, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. RP Whang, YC (reprint author), Catholic Univ Amer, Washington, DC 20064 USA. NR 30 TC 5 Z9 5 U1 0 U2 0 PU EUROPEAN GEOPHYSICAL SOCIETY PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 0992-7689 J9 ANN GEOPHYS JI Ann. Geophys. PD SEP PY 2001 VL 19 IS 9 BP 1095 EP 1105 PG 11 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA 489LC UT WOS:000171992000004 ER PT J AU Goolish, EM AF Goolish, Edward M. TI Astrobiology: Bridging the Physical and Life Sciences SO ASTROBIOLOGY LA English DT Editorial Material C1 NASA, Ames Res Ctr, Astrobiol Inst, Moffett Field, CA 94035 USA. RP Goolish, EM (reprint author), NASA, Ames Res Ctr, Astrobiol Inst, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MARY ANN LIEBERT, INC PI NEW ROCHELLE PA 140 HUGUENOT STREET, 3RD FL, NEW ROCHELLE, NY 10801 USA SN 1531-1074 EI 1557-8070 J9 ASTROBIOLOGY JI Astrobiology PD SEP PY 2001 VL 1 IS 3 BP 292 EP 292 DI 10.1089/15311070152757500 PG 1 WC Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Life Sciences & Biomedicine - Other Topics; Geology GA V38SM UT WOS:000209363100005 ER PT J AU Soifer, BT Neugebauer, G Matthews, K Egami, E Weinberger, AJ Ressler, M Scoville, NZ Stolovy, SR Condon, JJ Becklin, EE AF Soifer, BT Neugebauer, G Matthews, K Egami, E Weinberger, AJ Ressler, M Scoville, NZ Stolovy, SR Condon, JJ Becklin, EE TI High-resolution mid-infrared imaging of infrared-luminous starburst galaxies SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : general; galaxies : starburst; infrared radiation ID STAR-FORMING GALAXIES; ARP 299; OPTICAL SPECTROSCOPY; RADIO SUPERNEBULA; VV 114; NUCLEI; SAMPLE; EMISSION; SYSTEM; ATLAS AB Observations for seven infrared-luminous starburst galaxies are reported in the mid-infrared from 8 to 18 mum using the Keck telescopes with spatial resolution approaching the diffraction limit. All of the galaxies observed show evidence of strong interactions based on optical morphologies. For these galaxies, a substantial fraction, usually more than 50%, of the infrared luminosity is generated in regions ranging in sizes from 100 pc to 1 kpc. Nuclear starbursts often dominate the infrared luminosity, but this is not always true. In some galaxies, most notably NGC 6090, substantial infrared luminosity greatly in excess of the nuclear luminosity is generated in regions associated with the physical interaction between two galaxies. The radio emission is a good tracer of the location of high-luminosity young stars. The visual/ultraviolet radiation output of the nearby star-forming galaxies is dominated by emission from regions that are generally not producing the copious infrared luminosity of the systems. As seen in comparing the mid-infrared and near-infrared images of the galaxies observed here, the regions of high-infrared luminosity in local galaxies are significantly smaller than the galaxies as a whole. The integrated spectral energy distributions (SEDs) of these galaxies are very different from the SEDs of the regions of star formation. If the SEDs of star-forming regions in these galaxies reflect the SEDs that would be found in forming galaxies at high redshift, we would expect the distant galaxies to be dominated by the mid- and far-infrared luminosity output far more than the integrated luminous output of nearby starburst galaxies would suggest. C1 CALTECH, Palomar Observ, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. CALTECH, SIRTF Sci Ctr, Pasadena, CA 91125 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. RP Soifer, BT (reprint author), CALTECH, Palomar Observ, Mail Stop 320-47, Pasadena, CA 91125 USA. EM bts@mop.caltech.edu; gxn@mop.caltech.edu; kym@caltech.edu; egami@mop.caltech.edu; alycia@astro.ucla.edu; ressler@cougar.jpl.nasa.gov; nzs@astro.caltech.edu; stolovy@ipac.caltech.edu; jcondon@nrao.edu; becklin@astro.ucla.edu OI Weinberger, Alycia/0000-0001-6654-7859 NR 54 TC 87 Z9 87 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 2001 VL 122 IS 3 BP 1213 EP 1237 DI 10.1086/322119 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472RA UT WOS:000170997700009 ER PT J AU Beck, SC Turner, JL Gorjian, V AF Beck, SC Turner, JL Gorjian, V TI Infrared emission from clusters in the star-forming disk of Henize 2-10 SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : dwarf; galaxies : individual (He 2-10); galaxies : starburst; galaxies : star clusters; galaxies : peculiar; radio continuum ID GALAXY HENIZE-2-10; NGC-5253; STARBURSTS; HE-2-10 AB We have made subarcsecond-resolution images of the central 10" of the Wolf-Rayet dwarf galaxy He 2-10 at 11.7 mum, using the Long Wavelength Spectrometer on the Keck I Telescope. The spatial distribution of the infrared emission roughly agrees with that of the rising spectrum radio sources seen by Kobulnicky & Johnson and confirms that those sources are compact H II regions, rather than supernova remnants or other objects. The infrared sources are more extended than the subarcsecond rising spectrum radio sources, although the entire complex is still less than 5" in extent. On size scales of 1" the infrared and radio emission are in excellent agreement, with each source requiring several hundred to a thousand O stars for excitation. The nebulae lie in a flattened disklike distribution about 240 by 100 pc and provide all of the flux measured by IRAS for the entire galaxy in the 12 mum band; 30% of the total IRAS flux from the galaxy emanates from one 15-30 pc source. In this galaxy, intense star formation, probably triggered by an accretion event, is confined to a central disk, which breaks up into distinct nebulae presumably marking the sites of young super-star clusters. C1 Tel Aviv Univ, Dept Phys & Astron, Ramat Aviv, Israel. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Beck, SC (reprint author), Tel Aviv Univ, Dept Phys & Astron, Ramat Aviv, Israel. NR 17 TC 23 Z9 23 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 2001 VL 122 IS 3 BP 1365 EP 1368 DI 10.1086/322099 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472RA UT WOS:000170997700019 ER PT J AU Roe, HG Gavel, D Max, C de Pater, I Gibbard, S Macintosh, B Baines, KH AF Roe, HG Gavel, D Max, C de Pater, I Gibbard, S Macintosh, B Baines, KH TI Near-infrared observations of Neptune's tropospheric cloud layer with the Lick Observatory adaptive optics system SO ASTRONOMICAL JOURNAL LA English DT Article DE infrared radiation; instrumentation : adaptive optics; planets and satellites : individual (Neptune) ID ATMOSPHERIC STRUCTURE; ABSORPTION SPECTRA; H-2-HE PAIRS; TEMPERATURES; METHANE; BAND; VARIABILITY; BRIGHTNESS; SCATTERING; OVERTONE AB We provide one of the first constraints on the combined infrared single-scattering albedo and opacity of Neptune's upper tropospheric cloud layer. For the observations, we used the adaptive optics system on the Lick Observatory's 3 m Shane Telescope (Mount Hamilton, California). The cloud layer is thought to be composed H(2)S of and extend up to 3.5-4.5 bars. Previously, the single-scattering albedo was measured in the range 0.2-0.94 mum and found to be extremely high (>0.8), but decreasing with increasing wavelength. Assuming an optically thick cloud, we find the best-Dt single-scattering albedo of a 3.5 bar layer to be at 0.23(-0.08)(+0.07) at 1.27 mum and 0.18(-0.04)(+0.03) at 1.56 mum. Uncertainties in the column density of haze above the cloud layer, and from deconvolution to remove contaminating light scattered by the point-spread function from infrared-bright features, indicate that the cloud could be even darker, but it is unlikely to be brighter than we report. The cloud particles could be brighter than we report if the total near-infrared opacity of the cloud is very low or the cloud's scattering phase function is significantly more forward-scattering at 1.2-1.6 mum than at 0.75 mum. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Roe, HG (reprint author), Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA. EM hroe@doty.berkeley.edu OI Max, Claire/0000-0003-0682-5436 NR 35 TC 8 Z9 8 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 2001 VL 122 IS 3 BP 1636 EP 1643 DI 10.1086/322125 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 472RA UT WOS:000170997700044 ER PT J AU Hanisch, RJ Farris, A Greisen, EW Pence, WD Schlesinger, BM Teuben, PJ Thompson, RW Warnock, A AF Hanisch, RJ Farris, A Greisen, EW Pence, WD Schlesinger, BM Teuben, PJ Thompson, RW Warnock, A TI Definition of the Flexible Image Transport System (FITS) SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE instrumentation : miscellaneous; methods : miscellaneous; techniques : miscellaneous; astronomical databases : miscellaneous ID EXTENSION AB The Flexible Image Transport System-FITS-has been in use in the astronomical community for over two decades. A newly updated version of the standard has recently been approved by the International Astronomical Union FITS Working Group. This new version of the standard appears here in its entirety. As a preface we briefly describe the process by which the standard evolves and revisions are approved, and note two minor changes to NOST 100-2.0 which were adopted by the IAU FWG. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Natl Radio Astron Observ, Charlottesville, VA USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS, Greenbelt, MD USA. Univ Maryland, College Pk, MD 20742 USA. Comp Sci Corp, Cincinnati, OH 45202 USA. RP Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. EM hanisch@stsci.edu NR 14 TC 108 Z9 116 U1 1 U2 8 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 SEP PY 2001 VL 376 IS 1 BP 359 EP 380 DI 10.1051/0004-6361:20010923 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 466LG UT WOS:000170646600043 ER PT J AU Le Bertre, T Matsuura, M Winters, JM Murakami, H Yamamura, I Freund, M Tanaka, M AF Le Bertre, T Matsuura, M Winters, JM Murakami, H Yamamura, I Freund, M Tanaka, M TI Galactic mass-losing AGB stars probed with the IRTS. I. SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : carbon; stars : mass-loss; stars : AGB and post-AGB; ISM : evolution; galaxy : solar neighbourhood; infrared : stars ID CIRCUMSTELLAR DUST SHELLS; GIANT BRANCH STARS; LONG-PERIOD VARIABLES; LOSS RATES; EVOLVED STARS; INFRARED OBSERVATIONS; CARBON STARS; RICH STARS; ENVELOPES; SPECTRA AB AGB mass-losing sources are easy to identify and to characterize in the near-infrared range (1-5 mum). We make use of the near-infrared data acquired by the Japanese space experiment IRTS to study a sample of sources detected in the 2 celestial strips surveyed by the IRTS. Mass-loss rates and distances are estimated for 40 carbon-rich sources and 86 oxygen-rich sources of which 8 are probably of S-type. Although the sample is small, one sees a dependence of the relative contribution of the two kinds of sources to the replenishment of the interstellar medium (ISM) on the galactocentric distance. E.g. from 6 to 8 kpc, oxygen-rich sources in our sample contribute 10-12 times as much as carbon rich sources, whereas from 10 to 12 kpc, the latters contribute 3-4 times as much as the formers. Therefore, one would expect a gradient in the composition of the ISM between 6 and 12 kpc from the Galactic Centre, especially in its dust component. Most of the replenishment (>50%) by AGB stars is due to sources with mass-loss rate larger than 10(-6) M-circle dot yr(-1). C1 Observ Paris, DEMIRM, UMR 8540, F-75014 Paris, France. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. Univ Tokyo, Dept Astron, Bunkyo Ku, Tokyo 1130033, Japan. Univ Manchester, Dept Phys, Manchester M60 1QD, Lancs, England. Max Planck Inst Radioastron, D-53121 Bonn, Germany. NASA, Goddard Space Flight Ctr, Infrared Astrophys Branch, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RP Observ Paris, DEMIRM, UMR 8540, 61 Av Observ, F-75014 Paris, France. EM Thibaut.LeBertre@obspm.fr NR 49 TC 37 Z9 37 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 SEP PY 2001 VL 376 IS 3 BP 997 EP 1010 DI 10.1051/0004-6361:20011033 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 474CR UT WOS:000171087200029 ER PT J AU Markwick, AJ Charnley, SB Millar, TJ AF Markwick, AJ Charnley, SB Millar, TJ TI Deuterium fractionation along the TMC-1 ridge SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE MHD : waves; ISM : abundances; ISM : molecules; ISM : individual : Taurus Molecular Cloud; molecular processes ID DENSE INTERSTELLAR CLOUDS; MOLECULAR CLOUDS; CHEMISTRY; WAVES AB In this paper, we present a model to predict and explain the observed gradients in deuterium fractionation and molecular abundance along the TMC-1 ridge. In TMC-1, gradients in the level of deuterium fractionation are observed for all the molecular species for which the measurement has been made; HCO+, HC3N, C3H2 and HNC. The model is based on the assumption that the chemical evolution of the TMC-1 ridge has been affected by Alfven waves. The structure of the model and its comparison with observations are discussed. We find that the model qualitatively and somewhat quantitatively reproduces the observations of the aforementioned molecular species. We present predictions of the fractionation gradients along the TMC-1 ridge for other molecules of observational interest. C1 Univ Manchester, Dept Phys, Manchester M60 1QD, Lancs, England. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Univ Manchester, Dept Phys, POB 88, Manchester M60 1QD, Lancs, England. EM ajm@jarus1.phy.unist.ac.uk; charnley@dusty.arc.nasa.gov; Tom.Millar@umist.ac.uk RI Charnley, Steven/C-9538-2012; OI Millar, Tom/0000-0001-5178-3656 NR 30 TC 16 Z9 16 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 2001 VL 376 IS 3 BP 1054 EP 1063 DI 10.1051/0004-6361:20011022 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 474CR UT WOS:000171087200034 ER PT J AU Cambresy, L Boulanger, F Lagache, G Stepnik, B AF Cambresy, L Boulanger, F Lagache, G Stepnik, B TI Far-infrared dust opacity and visible extinction in the Polaris Flare SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ISM : clouds; ISM : dust, extinction; ISM : individual object : Polaris Flare; infrared : ISM : continuum ID COLD DUST; SPECTRAL OBSERVATIONS; INTERSTELLAR DUST; EMISSION; CLOUD; STAR; COBE; COMPLEX; GALAXY AB We present an extinction map of the Polaris molecular cirrus cloud derived from star counts and compare it with the Schlegel et al. (1998) extinction map derived from the far-infrared dust opacity. We find that, within the Polaris cloud, the Schlegel et al. (1998) AV values are a factor 2 to 3 higher than the star count values. We propose that this discrepancy results from a difference in tau (FIR)=A(V) between the diffuse atomic medium and the Polaris cloud. We use the difference in spectral energy distribution, warm for the diffuse atomic medium, cold for the Polaris cloud, to separate their respective contribution to the line of sight integrated infrared emission and find that the tau (FIR)=A(V) of cold dust in Polaris is on average 4 times higher than the Schlegel et al. (1998) value for dust in atomic cirrus. This change in dust property could be interpreted by a growth of fluffy particles within low opacity molecular cirrus clouds such as Polaris. Our work suggests that variations in dust emissivity must be taken into account to estimate A(V) from dust emission wherever col d infrared emission is present (i.e. molecular clouds). C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Observ Paris, Dept Rech Spatiale, F-92195 Meudon, France. Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France. RP Cambresy, L (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Mail Code 100-22, Pasadena, CA 91125 USA. EM laurent@ipac.caltech.edu NR 34 TC 61 Z9 61 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 SEP PY 2001 VL 375 IS 3 BP 999 EP 1007 DI 10.1051/0004-6361:20010930 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 466KX UT WOS:000170645700029 ER PT J AU Mallouris, C Welty, DE York, DG Moos, HW Sembach, KR Friedman, SD Jenkins, EB Lemoine, M Oegerle, WR Savage, BD Shull, JM Sonneborn, G Vidal-Madjar, A AF Mallouris, C Welty, DE York, DG Moos, HW Sembach, KR Friedman, SD Jenkins, EB Lemoine, M Oegerle, WR Savage, BD Shull, JM Sonneborn, G Vidal-Madjar, A TI Far Ultraviolet Spectroscopic Explorer observations of interstellar gas toward the Small Magellanic Cloud star Sk 108 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : abundances; galaxies : ISM; ISM : abundances; Magellanic Clouds; stars : individual (Sk 108) ID HUBBLE-SPACE-TELESCOPE; LY-ALPHA SYSTEMS; HEAVY-ELEMENTS; ABSORPTION-LINES; IONIZED-GAS; OSCILLATOR-STRENGTHS; ZETA-PUPPIS; ABUNDANCES; SIGHT; KINEMATICS AB We discuss the interstellar absorption lines found in Far Ultraviolet Spectroscopic Explorer spectra of the Wolf-Rayet binary Sk 108, which is located in the northeastern part of the main "bar" of the Small Magellanic Cloud. The spectra cover the 988-1187 Angstrom wavelength range at a resolution of about 12,000 and a signal-to-noise ratio of 20-40. We use detailed component information from higher resolution near-UV and optical spectra to model the far-UV lines of similarly distributed species. Both the Galactic and SMC gas toward Sk 108 seem to be predominantly neutral, although a significant fraction of the SMC gas is ionized. The column densities of P II, S II, and Ar I are consistent with essentially solar ratios, relative to N(Zn II), in both the Galactic and SMC gas; the column density of N I remains somewhat uncertain. Molecular hydrogen is present in the Galactic gas, with properties similar to those found in low mean density Galactic lines of sight and in the Galactic gas toward several other LMC and SMC stars. We report a tentative detection of H-2 in the SMC gas for J = 1 and 3, with rotational level populations consistent with an excitation temperature on the order of 1000 K-similar to the H-2 found in diffuse Galactic gas toward zeta Puppis. Strong absorption from N III, S III, and Fe III has revealed a significant ionized component, particularly in the SMC; O VI is present, but relatively weak, especially in the Galactic gas. The N(C IV)/N(O VI) ratio varies somewhat within the SMC, suggesting that several processes may contribute to the observed high ion abundances. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Observ Paris, CNRS, UMR 8629, Dept Astrophys Relativiste & Cosmol, F-92195 Meudon, France. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Colorado, Dept Astrophys & Planetary Sci, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. CNRS, Inst Astrophys Paris, F-75014 Paris, France. RP Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA. RI Oegerle, William/C-9070-2012; Sonneborn, George/D-5255-2012; Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 52 TC 19 Z9 19 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2001 VL 558 IS 1 BP 133 EP 144 DI 10.1086/322461 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CB UT WOS:000170794300013 ER PT J AU Nummelin, A Whittet, DCB Gibb, EL Gerakines, PA Chiar, JE AF Nummelin, A Whittet, DCB Gibb, EL Gerakines, PA Chiar, JE TI Solid carbon dioxide in regions of low-mass star formation SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; infrared : ISM; ISM : abundances; ISM : lines and bands; ISM : molecules ID HERBIG-HARO OBJECTS; TIME-DEPENDENT CHEMISTRY; DENSE MOLECULAR CLOUDS; YOUNG STELLAR OBJECTS; TAURUS DARK CLOUD; INFRARED-SPECTROSCOPY; ABSORPTION FEATURES; SWS OBSERVATIONS; ICE MIXTURES; CO AB We present high-resolution (R similar to 1500-2000) spectra of the 4.27 mum asymmetric stretching feature of solid CO2 in eight lines of sight observed with the Short Wavelength Spectrometer of the Infrared Space Observatory. Two of the sources are field stars located behind the Taurus molecular cloud; the others are young stellar objects (YSOs) of predominantly low-to-intermediate mass. We find a significant source-to-source variation in the solid CO2/H2O abundance ratio in our sample: two lines of sight, Elias 18 and RAFGL 989, have CO2 abundances of similar to 34%-37%, considerably higher than in other lines of sight studied to date. In agreement with a previous study of Elias 16, we confirm a substantial (similar to 20%) abundance of solid CO2 relative to H2O in the quiescent intracloud medium. We compare the CO2 profiles with laboratory spectra of interstellar ice analogs from the Leiden Observatory Laboratory database. Results show that the 4.27 um profiles toward field stars and embedded low-mass objects are remarkably similar to each other and seem to originate mostly in cold H2O-rich ice. In two higher mass YSOs (RAFGL 989 and S255 IRS1), the profiles are clearly different, and at least the latter source shows signs of thermal processing. C1 Rensselaer Polytech Inst, Dept Phys Appl Phys & Astron, Troy, NY 12180 USA. Rensselaer Polytech Inst, New York Ctr Studies Origins Life, Troy, NY 12180 USA. Univ Alabama, Dept Phys, Birmingham, AL 35294 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mt View, CA 94043 USA. RP Nummelin, A (reprint author), Chalmers Lindholmen Univ Coll, Dept Elect & Comp Engn, POB 8873, SE-40272 Gothenburg, Sweden. RI Gerakines, Perry/B-9705-2009; Gerakines, Perry/D-2226-2012 OI Gerakines, Perry/0000-0002-9667-5904 NR 55 TC 68 Z9 68 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2001 VL 558 IS 1 BP 185 EP 193 DI 10.1086/322480 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CB UT WOS:000170794300018 ER PT J AU Gogus, E Kouveliotou, C Woods, PM Thompson, C Duncan, RC Briggs, MS AF Gogus, E Kouveliotou, C Woods, PM Thompson, C Duncan, RC Briggs, MS TI Temporal and spectral characteristics of short bursts from the soft gamma repeaters 1806-20 and 1900+14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; stars : individual (SGR 1806-20, SGR 1900+14); X-rays : bursts ID MAGNETIZED NEUTRON-STARS; SGR 1900+14; X-RAY; STATISTICAL PROPERTIES; SGR-1806-20; OUTBURST; EMISSION AB We study the temporal and coarse spectral properties of 268 bursts from SGR 1806-20 and 679 bursts from SGR 1900 + 14, all observed with the Rossi X-Ray Timing Explorer/Proportional Counter Array. Hardness ratios and temporal parameters, such as T-90 durations and iota (90) emission times are determined for these bursts. We find a lognormal distribution of burst durations, ranging over more than 2 orders of magnitude: T-90 similar to 10(-2) to greater than or similar to 1 s, with a peak at similar to 0.1 s. The burst light curves tend to be asymmetrical, with more than half of all events showing rise times t(r) < 0.3 T-90. We find that there exists a correlation between the duration and fluence of bursts from both sources. We also find a significant anticorrelation between hardness ratio and fluence for SGR 1806-20 bursts and a marginal anticorrelation for SGR 1900 + 14 events. Finally, we discuss possible physical implications of these results within the framework of the magnetar model. C1 Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NASA, Marshall Space Flight Ctr, Huntsville, AL 35805 USA. Univ Space Res Assoc, Washington, DC USA. Canadian Inst Theoret Astrophys, Toronto, ON M5S 3H8, Canada. Univ Texas, Dept Astron, Austin, TX 78712 USA. RP Gogus, E (reprint author), Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NR 32 TC 62 Z9 62 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2001 VL 558 IS 1 BP 228 EP 236 DI 10.1086/322463 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CB UT WOS:000170794300022 ER PT J AU Ibrahim, AI Strohmayer, TE Woods, PM Kouveliotou, C Thompson, C Duncan, RC Dieters, S Swank, JH van Paradijs, J Finger, M AF Ibrahim, AI Strohmayer, TE Woods, PM Kouveliotou, C Thompson, C Duncan, RC Dieters, S Swank, JH van Paradijs, J Finger, M TI An unusual burst from soft gamma repeater SGR 1900+14: Comparisons with giant flares and implications for the magnetar model SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; stars : individual (SGR 1900+14); stars : magnetic fields; stars : neutron; X-rays : bursts ID X-RAY PULSAR; VARIABLE SPIN-DOWN; STATISTICAL PROPERTIES; NEUTRON-STARS; SGR-1900+14; EMISSION; SGR1900+14; TRANSIENT; OUTBURST; FIELD AB The soft gamma-ray repeater SGR 1900+14 entered a remarkable phase of activity during the summer of 1998. This activity peaked on 1998 August 27, when a giant periodic gamma -ray flare resembling the famous 1979 March 5 event from SGR 0526-66 was recorded. Two days later (August 29), a strong, bright burst was detected simultaneously with the Rossi X-Ray Timing Explorer (RXTE) and the Burst and Transient Source Experiment (BATSE). This event reveals several similarities to the giant flares of August 27 and March 5 and shows a number of unique features not previously seen in SGR bursts. Unlike typically short SGR bursts (duration similar to0.1 s), this event exhibits a 3.5 s burst peak that was preceded by an extended (similar to 1 s) complex precursor, and followed by a long (similar to 10(3) s) pulsating tail modulated at the 5.16 s stellar rotation period. Spectral analysis shows a striking distinction between the spectral behavior of the precursor, main peak, and long tail. While the spectrum is uniform during the peak, a significant hard-to-soft spectral evolution is detected in both the precursor and tail emissions. Temporal behavior shows a sharp rise (similar to 10 ms) at the precursor onset, a rapid cutoff (similar to 17 ms) at the end of the burst peak, and a gradual decay (similar to 17 minutes) of the pulsating tail. The tail pulsations show a simple pulse profile that did not evolve with time. The contrasted spectral and temporal signatures of the event suggest that the precursor, main peak, and extended tail are produced by different physical mechanisms, and that the observed tail represents a new emission component from SGRs. We discuss these features and their implications in the context of the magnetar model. The bright 3.5 s component is consistent with a very hot (kT similar to 1 MeV) trapped fireball, and the precursor with magnetospheric emission in which the radiating particles are heated more continuously. Less than 1% of the fireball energy will be conducted into the exposed surface of the neutron star, thereby dissociating heavy elements and even helium, and inducing rapid transformations between neutrons and protons. The extended "afterglow" tail of the August 29 burst is consistent with a cooling hot spot of small area (similar to 13 km(2)), and indicates that the energy release in an SGR burst is strongly localized. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. George Washington Univ, Dept Phys, Washington, DC 20052 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Space Res Assoc, NSSTC, Huntsville, AL 35805 USA. Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. Univ Alabama, Dept Phys, Huntsville, AL 35812 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP Ibrahim, AI (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RI Ibrahim, Alaa/A-6250-2008; Swank, Jean/F-2693-2012 OI Ibrahim, Alaa/0000-0002-8791-7270; NR 51 TC 66 Z9 66 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2001 VL 558 IS 1 BP 237 EP 252 DI 10.1086/322248 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CB UT WOS:000170794300023 ER PT J AU Rivera, EJ Lissauer, JJ AF Rivera, EJ Lissauer, JJ TI Dynamical models of the resonant pair of planets orbiting the star GJ 876 SO ASTROPHYSICAL JOURNAL LA English DT Article DE celestial mechanics; methods : n-body simulations; planetary systems; stars : individual (GJ 876) AB We present two planet fits to the radial velocity measurements of the M dwarf star GJ 876 that account for the mutual perturbations between the planets, as well as their interactions with the star. We also give the results of long-term integrations testing the stability of some of our best-fit systems. Our Newtonian models fit the data much better than do Keplerian models, reducing the chi (2)(nu) from 1.88 to as low as 1.34 for an unstable high-inclination system and 1.43 for a stable low-inclination system. Several different local minima with comparable chi (2)(nu) are found in parameter space; thus, our results are not able to provide tight constraints on the inclinations of the orbits to the line of sight and actual planetary masses. Most sets of planetary parameters that we have derived represent systems that are stable for at least 10(8) yr. Test particles orbiting between the two planets within our best-fit planar system are lost in less than 300 yr. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. RP Rivera, EJ (reprint author), NASA, Ames Res Ctr, Div Space Sci, 245-3, Moffett Field, CA 94035 USA. NR 9 TC 85 Z9 86 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2001 VL 558 IS 1 BP 392 EP 402 DI 10.1086/322477 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CB UT WOS:000170794300036 ER PT J AU Bloemhof, EE Dekany, RG Troy, M Oppenheimer, BR AF Bloemhof, EE Dekany, RG Troy, M Oppenheimer, BR TI Behavior of remnant speckles in an adaptively corrected imaging system SO ASTROPHYSICAL JOURNAL LA English DT Article DE instrumentation : adaptive optics; turbulence ID OPTICS; PERFORMANCE; PLANETS; CORONAGRAPH; TELESCOPES; RESOLUTION; IMAGES; NOISE AB Adaptive correction on large ground-based telescopes is enabling a variety of novel studies that would be impossible at the limits of spatial and spectral resolution imposed by the Earth's turbulent atmosphere. Even relatively high-order systems, however, do not yield a perfect correction and as a result are compromised by a low-intensity halo of remnant light that is removed from the core of the point-spread function (PSF) and dispersed in the focal plane. Worse still, this halo is neither constant in time nor uniform in position but is concentrated in transient spots that move about as mutually coherent patches of phase over the telescope aperture happen to combine constructively in the image plane, These "speckles" in the PSF set limits on ground-based searches for faint companions to bright stars. We describe here simple properties of the physics of speckle formation that will affect the statistics of residual speckles in a fundamental way: at high correction, the secondary maxima of the static PSF will coherently amplify or "pin" the time-varying speckles, influencing their effective characteristic lifetimes and dramatically changing their spatial distribution. Furthermore, as a result of speckle pinning, temporal variations in the noncommon path errors that occur in practical adaptive optics systems will cause an additional gradual drift in the spatial distribution of speckles. as Airy rings shift. Speckle pinning may be exploited to suppress speckle noise by tailoring the PSF with static aberrations artificially injected via the deformable mirror so as to clear a region of the PSF of Airy rings and hence of pinned speckles, a technique that we term "speckle sweeping." C1 CALTECH, Palomar Observ, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94620 USA. RP Bloemhof, EE (reprint author), CALTECH, Palomar Observ, 105-24, Pasadena, CA 91125 USA. NR 16 TC 49 Z9 49 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2001 VL 558 IS 1 BP L71 EP L74 DI 10.1086/323494 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CC UT WOS:000170794500017 ER PT J AU Kouveliotou, C Tennant, A Woods, PM Weisskopf, MC Hurley, K Fender, RP Garrington, ST Patel, SK Gogus, E AF Kouveliotou, C Tennant, A Woods, PM Weisskopf, MC Hurley, K Fender, RP Garrington, ST Patel, SK Gogus, E TI Multiwavelength observations of the soft gamma repeater SGR 1900+14 during its 2001 April activation SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : magnetic fields; stars : neutron ID MAGNETIZED NEUTRON-STARS; X-RAY PULSAR; SGR1900+14 AB The soft gamma repeater SGR 1900+14 became active on 2001 April 18 after about 2 years of quiescence; it had remained at a very low state of activity since the fall of 1998, when it exhibited extraordinary flaring. We have observed the source in the gamma-rays and X-rays with Ulysses and Chandra and in the radio with MERLIN. We report here the confirmation of a two-component X-ray spectrum (power law + blackbody), indicating emission from the neutron star surface. We have determined that there is a dust halo, due to scattering in the interstellar medium, surrounding the source that extends up to greater than or similar to 100 " from the center of SGR 1900+14. C1 NSSTC, Univ Space Res Assoc, Huntsville, AL 35805 USA. NASA, Marshall Space Flight Ctr, NSSTC, Huntsville, AL 35805 USA. NASA, MSFC, Huntsville, AL 35812 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Univ Amsterdam, Inst High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands. Univ Manchester, Nuffield Radio Astron Labs, Jodrell Bank Observ, Macclesfield SK11 9DL, Cheshire, England. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Kouveliotou, C (reprint author), NSSTC, Univ Space Res Assoc, SD-50,320 Sparkman Dr, Huntsville, AL 35805 USA. NR 26 TC 44 Z9 44 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2001 VL 558 IS 1 BP L47 EP L50 DI 10.1086/323496 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CC UT WOS:000170794500012 ER PT J AU Tylka, AJ Cohen, CMS Dietrich, WF MacLennan, CG McGuire, RE Ng, CK Reames, DV AF Tylka, AJ Cohen, CMS Dietrich, WF MacLennan, CG McGuire, RE Ng, CK Reames, DV TI Evidence for remnant flare suprathermals in the source population of solar energetic particles in the 2000 Bastille Day event SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; shock waves; Sun : coronal mass ejections (CMEs); Sun : flares; Sun : particle emission ID ADVANCED-COMPOSITION-EXPLORER; CHARGE-STATE MEASUREMENTS; IONIC CHARGE; TEMPORAL EVOLUTION; HEAVY-IONS; ACCELERATION; WIND; SPACECRAFT; ENERGIES; NUCLEON AB The energy spectra of Fe in the Very large solar energetic particle (SEP) event of 2000 July 14 are strikingly different from those of lighter species. We show that this difference can be explained by shock acceleration from a two-component source population, comprising solar wind suprathermals and a small (similar to5%) admixture of remnant flare particles. as previously proposed to explain enhanced He-3/He-4 in some gradual SEP events. Flare remnants can also account for several previously unexplained features of high-energy solar heavy ions as well as important aspects of SEP event-to-event variability. These results offer a new perspective on the enduring controversy over the relative roles of Hares and coronal mass ejections (CMEs) in producing SEPs. Flare activity clearly makes a unique and critical contribution to the source population. But the predominate accelerator in large gradual SEP events is the CME-driven shock, and many spectral, compositional, and charge state characteristics of high-energy heavy ions can be understood without invoking other acceleration mechanisms. C1 USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. CALTECH, Pasadena, CA 91125 USA. Univ Chicago, Enrico Fermi Inst, Lab Astrophys & Space Res, Chicago, IL 60637 USA. Lucent Technol, Bell Labs, Murray Hill, NJ 07974 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Tylka, AJ (reprint author), USN, Res Lab, EO Hulburt Ctr Space Res, Code 7652, Washington, DC 20375 USA. RI Tylka, Allan/G-9592-2014 NR 32 TC 66 Z9 67 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2001 VL 558 IS 1 BP L59 EP L63 DI 10.1086/323344 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CC UT WOS:000170794500015 ER PT J AU Points, SD Chu, YH Snowden, SL Smith, RC AF Points, SD Chu, YH Snowden, SL Smith, RC TI Large-scale diffuse X-ray emission from the Large Magellanic Cloud SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies : ISM; Magellanic Clouds; X-rays : galaxies; X-rays : ISM ID ROSAT; COMPONENTS; SPECTRUM; REMNANTS; SHELLS AB X-ray mosaics of the Large Magellanic Cloud (LMC) taken with the ROSAT Position Sensitive Proportional Counter (PSPC) have revealed extensive diffuse X-ray emission, indicative of hot greater than or equal to 10(6) K gas associated with this irregular galaxy on scales from similar to 10 to greater than or equal to 1000 pc. We have selected regions of large-scale (d greater than or equal to 600 pc) diffuse X-ray emission, such as supergiant shells, the LMC Spur, and the LMC Bar, and examined the physical conditions of the hot gas associated with them. We find that for these objects the plasma temperatures range from kT similar to 0.15 to 0.60 keV and the derived electron densities range from n(e) similar to 0.005 to 0.03 cm(-3). Furthermore, we have examined the fraction of diffuse X-ray emission from the LMC and compared it to the total X-ray emission. We find that discrete sources such as X-ray binaries and supernova remnants account for similar to 41% and similar to 21% of the X-ray emission from the LMC, respectively. In contrast, diffuse X-ray emission from the field and from supergiant shells account for similar to 30% and similar to6% of the total X-ray emission, respectively. C1 Univ Illinois, Dept Astron, Urbana, IL 61801 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cerro Tololo Interamer Observ, La Serena, Chile. RP Points, SD (reprint author), Univ Illinois, Dept Astron, 1002 W Green St, Urbana, IL 61801 USA. RI Snowden, Steven/D-5292-2012 NR 34 TC 13 Z9 13 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD SEP PY 2001 VL 136 IS 1 BP 99 EP 118 DI 10.1086/321799 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 467LQ UT WOS:000170705000005 ER PT J AU Ronca, AE Baer, LA Daunton, NG Wade, CE AF Ronca, AE Baer, LA Daunton, NG Wade, CE TI Maternal reproductive experience enhances early postnatal outcome following gestation and birth of rats in hypergravity SO BIOLOGY OF REPRODUCTION LA English DT Article DE parturition; pregnancy; reproductive behavior; stress ID NORWAY RATS; PUP STIMULI; BEHAVIOR; SPACEFLIGHT; PROLACTIN; VIRGIN AB A major goal of space life sciences research is to broaden scientific knowledge of the influence of gravity on living systems. Recent spaceflight and centrifugation studies demonstrate that reproduction and ontogenesis in mammals are amenable to study under gravitational conditions that deviate considerably from those typically experienced on Earth (1 x g). In the present study, we tested the hypothesis that maternal reproductive experience determines neonatal outcome following gestation and birth under increased (hyper) gravity. Primigravid and bigravid female rats and their offspring were exposed to 1.5 x g centrifugation from Gestational Day 11 either through birth or through the first postnatal week. On the day of birth, litter sizes were identical across gravity and parity conditions, although significantly fewer live neonates were observed among hypergravity-reared litters born to primigravid dams than among those born to bigravid dams (82% and 94%, respectively; 1.0 x g controls, 99%). Within the hypergravity groups, neonatal mortality was comparable across parity conditions from Postnatal Day I through Day 7, at which time litter sizes stabilized. Maternal reproductive experience ameliorated neonatal losses during the first 24 h after birth but not on subsequent days, and neonatal mortality was associated with changes in maternal care patterns. These results indicate that repeated maternal reproductive experience affords protection against neonatal losses during exposure to increased gravity. Differential mortality of neonates born to primigravid versus bigravid dams denotes gravitational load as one environmental mechanism enabling the expression of parity-related variations in birth outcome. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Lockheed Martin Sci & Engn, Moffett Field, CA 94035 USA. RP Ronca, AE (reprint author), NASA, Ames Res Ctr, Div Life Sci, 261-3, Moffett Field, CA 94035 USA. FU NIMH NIH HHS [MH46485] NR 45 TC 16 Z9 16 U1 0 U2 0 PU SOC STUDY REPRODUCTION PI MADISON PA 1603 MONROE ST, MADISON, WI 53711-2021 USA SN 0006-3363 J9 BIOL REPROD JI Biol. Reprod. PD SEP PY 2001 VL 65 IS 3 BP 805 EP 813 DI 10.1095/biolreprod65.3.805 PG 9 WC Reproductive Biology SC Reproductive Biology GA 464YG UT WOS:000170560500025 PM 11514345 ER PT J AU Gilchrist, KH Barker, VN Fletcher, LE DeBusschere, BD Ghanouni, P Giovangrandi, L Kovacs, GTA AF Gilchrist, KH Barker, VN Fletcher, LE DeBusschere, BD Ghanouni, P Giovangrandi, L Kovacs, GTA TI General purpose, field-portable cell-based biosensor platform SO BIOSENSORS & BIOELECTRONICS LA English DT Article DE extracellular recording; portable; biosensor ID ARRAYS AB There are several groups of researchers developing cell-based biosensors for chemical and biological warfare agents based on electrophysiologic monitoring of cells. ln order to transition such sensors from the laboratory to the field, a general-purpose hardware and software Platform is required. This paper describes the design, implementation, and field-testing of such a system, consisting of cell-transport and data acquisition instruments. The cell-transport module is a self-contained, battery-powered instrument that allows various types of cell-based modules to be maintained at a preset temperature and ambient CO, level while in transit or in the field. The data acquisition module provides 32 channels of action potential amplification, filtering, and real-time data streaming to a laptop computer, At present, detailed analysis of the data acquired is carried out off-line, but sufficient computing power is available in the data acquisition module to enable the most useful algorithms to eventually be run real-time in the field. Both modules have sufficient internal power to permit realistic field-testing, such as the example presented in this paper. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Stanford Univ, Dept Elect Engn, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kovacs, GTA (reprint author), Stanford Univ, Dept Elect Engn, CIS-202X, Stanford, CA 94305 USA. OI Gilchrist, Kristin/0000-0003-3584-9832 NR 11 TC 52 Z9 54 U1 1 U2 3 PU ELSEVIER ADVANCED TECHNOLOGY PI OXFORD PA OXFORD FULFILLMENT CENTRE THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0956-5663 J9 BIOSENS BIOELECTRON JI Biosens. Bioelectron. PD SEP PY 2001 VL 16 IS 7-8 BP 557 EP 564 DI 10.1016/S0956-5663(01)00169-5 PG 8 WC Biophysics; Biotechnology & Applied Microbiology; Chemistry, Analytical; Electrochemistry; Nanoscience & Nanotechnology SC Biophysics; Biotechnology & Applied Microbiology; Chemistry; Electrochemistry; Science & Technology - Other Topics GA 476ZD UT WOS:000171257900015 PM 11544049 ER PT J AU Atwater, JE Michalek, WF Wheeler, RR Dahl, R Lunsford, TD Garmon, FC Sauer, RL AF Atwater, JE Michalek, WF Wheeler, RR Dahl, R Lunsford, TD Garmon, FC Sauer, RL TI A microwave-powered sterilizable interface for aseptic access to bioreactors that are vulnerable to microbial contamination SO BIOTECHNOLOGY PROGRESS LA English DT Article ID SPORES; DNA AB Novel methods and apparatus that employ the rapid heating characteristics of microwave irradiation to facilitate the aseptic transfer of nutrients, products, and other materials between microbially sensitive systems and the external environment are described. The microwave-sterilizable access port (MSAP) consists of a 600-W magnetron emitting at a frequency of 2.45 GHz, a sterilization chamber with inlet and outlet flow lines, and a specimen transfer interface. Energy is routed to the sterilization chamber via a coaxial transmission line where small quantities of water couple strongly with the incident radiation to produce a superheated vapor phase. The efficiency of energy transfer is enhanced through the use of microwave susceptors within the sterilization chamber. Mating surfaces are thermally sterilized through direct contact with the hot gas. Efficacy has been demonstrated using the thermophile Bacillus stearothermophilus. C1 UMPQUA Res Co, Myrtle Creek, OR 97457 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Atwater, JE (reprint author), UMPQUA Res Co, POB 609, Myrtle Creek, OR 97457 USA. NR 15 TC 1 Z9 1 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 8756-7938 J9 BIOTECHNOL PROGR JI Biotechnol. Prog. PD SEP-OCT PY 2001 VL 17 IS 5 BP 847 EP 851 DI 10.1021/bp0100732 PG 5 WC Biotechnology & Applied Microbiology; Food Science & Technology SC Biotechnology & Applied Microbiology; Food Science & Technology GA 480QK UT WOS:000171473300008 PM 11587573 ER PT J AU Conaty, AL Jusem, JC Takacs, L Keyser, D Atlas, R AF Conaty, AL Jusem, JC Takacs, L Keyser, D Atlas, R TI The structure and evolution of extratropical cyclones, fronts, jet streams, and the tropopause in the GEOS general circulation model SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID LIFE-CYCLE; PREDICTION; MAPS; GCM AB The realism of extratropical cyclones, fronts, jet streams. and the tropopause in the Goddard Earth Observing System (GEOS) general circulation model (GCM), implemented in assimilation and simulation modes, is evaluated from climatological and case-study perspectives using the GEOS-1 reanalysis climatology and applicable conceptual models as benchmarks for comparison. The latitude-longitude grid spacing of the datasets derived from the GEOS GCM ranges from 2 degrees x 2.5 degrees to 0.5 degrees x 0.5 degrees. Frontal systems in the higher-resolution datasets are characterized by horizontal potential temperature gradients that are narrower in scale and larger in magnitude than their lower-resolution counterparts, and various structural features in the Shapiro-Keyser cyclone model are replicated with reasonable fidelity at 1 degrees x 1 degrees resolution. The remainder of the evaluation focuses on a 3-month Northern Hemisphere winter simulation of the GEOS GCM at 1 degrees x 1 degrees resolution. The simulation realistically reproduces various large-scale circulation features related to the North Pacific and Atlantic jet streams when compared with the GEOS-1 reanalysis climatology, and conforms closely to a conceptualization of the zonally averaged troposphere and stratosphere proposed originally by Napier Shaw and revised by Hoskins. An extratropical cyclone that developed over the North Atlantic Ocean in the simulation features surface and tropopause evolutions corresponding to the Norwegian cyclone model and to the LC2 life cycle proposed by Thorncroft et al., respectively. These evolutions are related to the position of the developing cyclone with respect to upper-level jets identified in the time-mean and instantaneous flow fields. This article concludes with the enumeration of several research opportunities that may be addressed through the use of state-of-the-art GCMs possessing sufficient resolution to represent mesoscale phenomena and processes explicitly. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. SUNY Albany, Dept Earth & Atmospher Sci, Albany, NY 12222 USA. Sci Applicat Int Corp, Gen Sci Corp, Beltsville, MD USA. RP Atlas, R (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 29 TC 13 Z9 15 U1 1 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD SEP PY 2001 VL 82 IS 9 BP 1853 EP 1867 DI 10.1175/1520-0477(2001)082<1853:TSAEOE>2.3.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 468HL UT WOS:000170752000001 ER PT J AU Atlas, R Hoffman, RN Leidner, SM Sienkiewicz, J Yu, TW Bloom, SC Brin, E Ardizzone, J Terry, J Bungato, D Jusem, JC AF Atlas, R Hoffman, RN Leidner, SM Sienkiewicz, J Yu, TW Bloom, SC Brin, E Ardizzone, J Terry, J Bungato, D Jusem, JC TI The effects of marine winds from scatterometer data on weather analysis and forecasting SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID DATA ASSIMILATION SYSTEM; GLOBAL SURFACE WIND; QE-II STORM; SEASAT SCATTEROMETER; SATELLITE SCATTEROMETER; AMBIGUITY REMOVAL; EUROPEAN-CENTER; NSCAT WINDS; VARIATIONAL ASSIMILATION; VECTOR WINDS AB Satellite scatterometer observations of the ocean surface wind speed and direction improve the depiction of storms at sea. Over the ocean, scatterometer surface winds are deduced from multiple measurements of reflected radar power made from several directions. In the nominal situation, the scattering mechanism is Bragg scattering from centimeter-scale waves, which are in equilibrium with the local wind. These data are especially valuable where observations are otherwise sparse-mostly in the Southern Hemisphere extratropics and Tropics, but also on occasion in the North Atlantic and North Pacific. The history of scatterometer winds research and its application to weather analysis and forecasting is reviewed here. Two types of data impact studies have been conducted to evaluate the effect of satellite data, including satellite scatterometer data, for NWP. These are simulation experiments (or observing system simulation experiments or OSSEs) designed primarily to assess the potential impact of planned satellite observing systems, and real data impact experiments (or observing system experiments or OSEs) to evaluate the actual impact of available space-based data. Both types of experiments have been applied to the series of satellite scatterometers carried on the Seasat, European Remote Sensing-1 and -2, and the Advanced Earth Observing System-1 satellites, and the NASA Quick Scatterometer. Several trends are evident: The amount of scatterometer data has been increasing. The ability of data assimilation systems and marine forecasters to use the data has improved substantially. The ability of simulation experiments to predict the utility of new sensors has also improved significantly. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. Natl Ctr Environm Predict, Washington, DC USA. Gen Sci Corp, Laurel, MD USA. RP NASA, Goddard Space Flight Ctr, Data Assimilat Off, Mail Code 910-3, Greenbelt, MD 20771 USA. EM atlas@dao.gsfc.nasa.gov RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 93 TC 74 Z9 83 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 EI 1520-0477 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD SEP PY 2001 VL 82 IS 9 BP 1965 EP 1990 DI 10.1175/1520-0477(2001)082<1965:TEOMWF>2.3.CO;2 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 468HL UT WOS:000170752000009 ER PT J AU Bhatia, AK Drachman, RJ AF Bhatia, AK Drachman, RJ TI Polarizabilities and other properties of the td mu molecular ion SO CANADIAN JOURNAL OF PHYSICS LA English DT Article ID GROUND-STATE; DIPOLE POLARIZABILITIES; RYDBERG STATES; HELIUM; LITHIUM; H-2(+) AB Wave functions of the Hylleraas type were used earlier to calculate energy levels of muonic systems. Recently, we found in the case of the molecular ions H-2(+), D-2(+), and HD+ that it was necessary to include high powers of the internuclear distance in the Hylleraas functions to localize the nuclear motion when treating the ions as three-body systems without invoking the Born-Oppenheimer approximation. We tried the same approach in a muonic system, td mu (-) (triton, deuteron, and muon). Improved convergence was obtained for J = 0 and 1 states for shorter expansions when we used this type of generalized Hylleraas function, but as the expansion length increased the high powers were no longer useful. We obtained good energy values for the two lowest J = 0 and 1 states and compared them with the best earlier calculations. Expectation values were obtained for various operators, the Fermi contact parameters, and the permanent quadrupole moment. The cusp conditions were also calculated. The polarizability of the ground state was then calculated using second-order perturbation theory with intermediate J = 1 pseudostates. (It should be possible to measure the polarizability by observing Rydberg states of atoms with td mu (-) acting as the nucleus.) In addition, the initial sticking probability (an essential quantity in the analysis of muon catalyzed fusion) was calculated and compared with earlier results. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 682, Greenbelt, MD 20771 USA. EM drachman@stars.gsfc.nasa.gov NR 21 TC 7 Z9 7 U1 1 U2 3 PU CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS PI OTTAWA PA 65 AURIGA DR, SUITE 203, OTTAWA, ON K2E 7W6, CANADA SN 0008-4204 EI 1208-6045 J9 CAN J PHYS JI Can. J. Phys. PD SEP PY 2001 VL 79 IS 9 BP 1149 EP 1158 DI 10.1139/cjp-79-9-1149 PG 10 WC Physics, Multidisciplinary SC Physics GA 477VR UT WOS:000171305400004 ER PT J AU Dykman, MI Golding, B McCann, LI Smelyanskiy, VN Luchinsky, DG Mannella, R McClintock, PVE AF Dykman, MI Golding, B McCann, LI Smelyanskiy, VN Luchinsky, DG Mannella, R McClintock, PVE TI Activated escape of periodically driven systems SO CHAOS LA English DT Article ID SURMOUNTING OSCILLATING BARRIERS; DISSIPATIVE DYNAMICAL-SYSTEMS; STOCHASTIC RESONANCE; WEAK-NOISE; LARGE FLUCTUATIONS; POTENTIAL BARRIER; BROWNIAN PARTICLE; INTEGRAL APPROACH; METASTABLE STATE; OPTICAL TRAP AB We discuss activated escape from a metastable state of a system driven by a time-periodic force. We show that the escape probabilities can be changed very strongly even by a comparatively weak force. In a broad parameter range, the activation energy of escape depends linearly on the force amplitude. This dependence is described by the logarithmic susceptibility, which is analyzed theoretically and through analog and digital simulations. A closed-form explicit expression for the escape rate of an overdamped Brownian particle is presented and shown to be in quantitative agreement with the simulations. We also describe experiments on a Brownian particle optically trapped in a double-well potential. A suitable periodic modulation of the optical intensity breaks the spatio-temporal symmetry of an otherwise spatially symmetric system. This has allowed us to localize a particle in one of the symmetric wells. (C) 2001 American Institute of Physics. C1 Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA. Univ Wisconsin, Dept Phys, River Falls, WI 54022 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Lancaster, Dept Phys, Lancaster LA1 4YB, England. Univ Pisa, Dipartimento Fis, I-56100 Pisa, Italy. INFM, UdR Pisa, I-56100 Pisa, Italy. RP Dykman, MI (reprint author), Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA. RI Mannella, Riccardo/B-8798-2012; Luchinsky, Dmitry/N-4177-2014 NR 54 TC 40 Z9 40 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1054-1500 J9 CHAOS JI Chaos PD SEP PY 2001 VL 11 IS 3 BP 587 EP 594 DI 10.1063/1.1380368 PG 8 WC Mathematics, Applied; Physics, Mathematical SC Mathematics; Physics GA 469EC UT WOS:000170800800017 ER PT J AU Ostroumov, V Hoover, R Ostroumova, N Van Vliet-Lanoe, B Siegert, C Sorokovikov, V AF Ostroumov, V Hoover, R Ostroumova, N Van Vliet-Lanoe, B Siegert, C Sorokovikov, V TI Redistribution of soluble components during ice segregation in freezing ground SO COLD REGIONS SCIENCE AND TECHNOLOGY LA English DT Article; Proceedings Paper CT 2nd International Conference on Contaiminants in Freezing Ground CY JUL 02-05, 2000 CL FITZWILLIAM COLL, CAMBRIDGE, ENGLAND SP Univ Cambridge, Scott Polar Res Inst, Geotech Sci Labs, Carleton Univ HO FITZWILLIAM COLL DE redistribution; soluble components; ice segregation AB The segregation of ice develops in freezing grounds by migration of a pore solution to the crystallization front. How do the soluble components behave during the ice segregation, especially mobile forms of contaminant heavy metals? The intent of this paper is to study redistribution of the mobile metals during formation of lens-type cryogenic structure freezing water-rich silt, The experimental data show that the concentration of pore solute increases during the segregation of ice including metal pollutants. The zones of high concentration are formed at the interface of segregation ice lens and mineral layers in freezing ground. The parameters of phase transition of water (start temperature of thawing and total heat of phase transition) in such zones are decreased with the increased concentration. Part of the liquid unfrozen water in the concentration zones of frozen silt consists of microscopic drops at the surface of ice crystals. Probably part of the dissolved mobile component is present in such liquid inclusions under subzero temperature. A fixation of metal pollutants takes place in the zones of concentration during ice segregation in freezing ground. (C) 2001 Elsevier Science BN. All rights reserved. C1 Russian Acad Sci, Lab Soil Cryol, Inst Physicochem Problems Soil Sci, Moscow, Russia. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Sci & Technol, Lille, France. Alfred Wegener Inst Polar & Marine Res, Potsdam Unit, Potsdam, Germany. RP Ostroumov, V (reprint author), Russian Acad Sci, Lab Soil Cryol, Inst Physicochem Problems Soil Sci, Moscow, Russia. RI Brigitte, Van Vliet-Lanoe/A-1622-2009 NR 19 TC 9 Z9 13 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0165-232X J9 COLD REG SCI TECHNOL JI Cold Reg. Sci. Tech. PD SEP PY 2001 VL 32 IS 2-3 BP 175 EP 182 DI 10.1016/S0165-232X(01)00031-3 PG 8 WC Engineering, Environmental; Engineering, Civil; Geosciences, Multidisciplinary SC Engineering; Geology GA 475CM UT WOS:000171144200009 ER PT J AU Lee, D Beam, RM Warming, RF AF Lee, D Beam, RM Warming, RF TI Supercompact multiwavelets for flow field simulation SO COMPUTERS & FLUIDS LA English DT Article DE wavelets; multiresolution; data compression ID EQUATIONS; WAVELETS; BASES AB A supercompact multiwavelet scheme for computational fluid dynamics is presented. Beam and Warming's supercompact wavelet method is an appropriate wavelet for fluid simulation data in the sense that it can provide compact support. The compactness of the wavelets avoids unnecessary interaction with remotely located data (e.g. across a shock discontinuity or vortex) and significantly reduces computational data processing time. Thresholding for data compression with the supercompact wavelets is applied based on a covariance vector structure of multiwavelets. The extension of this scheme to three dimensions is analyzed. Numerical tests demonstrate that the analytic advantages actually result in large data compression ratios. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Hanyang Univ, Dept Mech Engn, Ansan 412791, Kyungki Do, South Korea. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lee, D (reprint author), Hanyang Univ, Dept Mech Engn, 1271 Sa L Dong, Ansan 412791, Kyungki Do, South Korea. NR 24 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD SEP-NOV PY 2001 VL 30 IS 7-8 BP 783 EP 805 DI 10.1016/S0045-7930(01)00029-9 PG 23 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 467BV UT WOS:000170681400003 ER PT J AU Briley, WR McDonald, H AF Briley, WR McDonald, H TI An overview and generalization of implicit Navier-Stokes algorithms and approximate factorization SO COMPUTERS & FLUIDS LA English DT Article DE implicit algorithms; linearization; alternating direction implicit; approximate factorization; upwind; relaxation; Newton's method; Navier-Stokes ID EULER EQUATIONS; HYPERBOLIC SYSTEMS; SCHEMES; FLOW; FORM; STEADY; GRIDS AB A theme of linearization and approximate factorization provides the context for a retrospective overview of the development and evolution of implicit numerical methods for the compressible and incompressible Euler and Navier-Stokes algorithms. This topic was chosen for this special volume commemorating the recent retirements of R.M. Beam and R.F. Warming. A generalized treatment of approximate factorization schemes is given, based on an operator notation for the spatial approximation. The generalization focuses on the implicit structure of Euler and Navier-Stokes algorithms as nonlinear systems of partial differential equations, with details of the spatial approximation left to operator definitions. This provides a unified context for discussing noniterative and iterative time-linearized schemes, and Newton iteration for unsteady nonlinear schemes. The factorizations include alternating direction implicit, LU and line relaxation schemes with either upwind or centered spatial approximations for both compressible and incompressible flows. The noniterative schemes are best suited for steady flows, while the iterative schemes are well suited for either steady or unsteady flows. This generalization serves to unify a large number of schemes developed over the past 30 years. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Mississippi State Univ, Dept Mech Engn, Computat Fluid Dynam Lab, NSF,ERC Computat Field Simulat, Mississippi State, MS 39762 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Mississippi State Univ, Dept Mech Engn, Computat Fluid Dynam Lab, NSF,ERC Computat Field Simulat, POB 6176, Mississippi State, MS 39762 USA. EM briley@erc.msstate.edu NR 87 TC 20 Z9 22 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7930 EI 1879-0747 J9 COMPUT FLUIDS JI Comput. Fluids PD SEP-NOV PY 2001 VL 30 IS 7-8 BP 807 EP 828 DI 10.1016/S0045-7930(01)00030-5 PG 22 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 467BV UT WOS:000170681400004 ER PT J AU Kiris, C Kwak, D AF Kiris, C Kwak, D TI Numerical solution of incompressible Navier-Stokes equations using a fractional-step approach SO COMPUTERS & FLUIDS LA English DT Article DE incompressible Navier-Stokes equations; fractional-step method; implicit method ID VORTEX; FLOW AB A fractional step method for the solution of steady and unsteady incompressible Navier-Stokes equations is outlined. The method is based on a finite-volume formulation and uses the pressure in the cell center and the mass fluxes across the faces of each cell as dependent variables. Implicit treatment of convective and viscous terms in the momentum equations enables the numerical stability restrictions to be relaxed. The linearization error in the implicit solution of momentum equations is reduced by using three subiterations in order to achieve second order temporal accuracy for time-accurate calculations. In spatial discretizations of the momentum equations, a high-order (third and fifth) flux-difference splitting for the convective terms and a second-order central difference for the viscous terms are used. The resulting algebraic equations are solved with a line-relaxation scheme which allows the use of large time step. A four color ZEBRA scheme is employed after the line-relaxation procedure in the solution of the Poisson equation for pressure. This procedure is applied to a Couette flow problem using a distorted computational grid to show that the method minimizes grid effects. Additional benchmark cases include the unsteady laminar flow over a circular cylinder for Reynolds numbers of 200, and a 3-D, steady, turbulent wingtip vortex wake propagation study. The solution algorithm does a very good job in resolving the vortex core when fifth-order upwind differencing and a modified production term in the Baldwin-Barth one-equation turbulence model are used with adequate grid resolution. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kiris, C (reprint author), NASA, Ames Res Ctr, Mail Stop T27B-1, Moffett Field, CA 94035 USA. NR 29 TC 15 Z9 17 U1 0 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD SEP-NOV PY 2001 VL 30 IS 7-8 BP 829 EP 851 DI 10.1016/S0045-7930(01)00031-7 PG 23 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 467BV UT WOS:000170681400005 ER PT J AU Thomas, JL Diskin, B Brandt, A AF Thomas, JL Diskin, B Brandt, A TI Textbook multigrid efficiency for the incompressible Navier-Stokes equations: high Reynolds number wakes and boundary layers SO COMPUTERS & FLUIDS LA English DT Article DE incompressible navier-stokes equations; textbook multigrid efficiency; distributive relaxation; defect-correction iteration AB Textbook multigrid efficiencies for high Reynolds number simulations based on the incompressible Navier-Stokes equations are attained for a model problem of flow past a finite flat plate. Elements of the full approximation scheme multigrid algorithm, including distributed relaxation, defect correction, and boundary treatment, are presented for the three main physical aspects encountered: entering flow, wake flow, and boundary layer flow. Textbook efficiencies, i.e., reduction of algebraic errors below discretization errors in one full multigrid cycle, are attained for second order accurate simulations at a laminar Reynolds number of 10,000. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, CMSB, Hampton, VA 23681 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. Weizmann Inst Sci, IL-76100 Rehovot, Israel. RP Thomas, JL (reprint author), NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, CMSB, Mail Stop 128, Hampton, VA 23681 USA. NR 10 TC 7 Z9 7 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD SEP-NOV PY 2001 VL 30 IS 7-8 BP 853 EP 874 DI 10.1016/S0045-7930(01)00032-9 PG 22 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 467BV UT WOS:000170681400006 ER PT J AU Seif, S Chang, JM Bhat, K Penn, B Lal, RB AF Seif, S Chang, JM Bhat, K Penn, B Lal, RB TI Investigation of temperature dependence and impurity content on the growth rate of KDP crystals SO CRYSTAL GROWTH & DESIGN LA English DT Article AB Growth rate and effects of doping sodium in potassium dihydrogen phosphate (KDP) solution have been studied in crystals grown by solution evaporation and slow cooling methods. The crystals were grown in a KDP solution doped with different concentrations of sodium ions. The rates of growth along the thickness and width of the crystals were independent of sodium incorporation into the grown crystals and dependent on temperature reduction by a factor of 10. The concentration of sodium in the crystals (C-s) measured by ICP and the concentrations of sodium in the KDP solution (C-1) showed C-s/C-1 to be constant. C1 Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. Alabama A&M Univ, Dept Chem, Normal, AL 35762 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Lal, RB (reprint author), Alabama A&M Univ, Dept Phys, POB 71, Normal, AL 35762 USA. NR 8 TC 12 Z9 12 U1 0 U2 6 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1528-7483 J9 CRYST GROWTH DES JI Cryst. Growth Des. PD SEP-OCT PY 2001 VL 1 IS 5 BP 359 EP 362 DI 10.1021/cg010002a PG 4 WC Chemistry, Multidisciplinary; Crystallography; Materials Science, Multidisciplinary SC Chemistry; Crystallography; Materials Science GA 519CM UT WOS:000173707400003 ER PT J AU Rashkovich, LN Gvozdev, NV Sil'nikova, MI Yaminskii, IV Chernov, AA AF Rashkovich, LN Gvozdev, NV Sil'nikova, MI Yaminskii, IV Chernov, AA TI Dependence of the step velocity on its length on the (010) face of the orthorhombic lysozyme crystal SO CRYSTALLOGRAPHY REPORTS LA English DT Article ID NUCLEATION AB The length of a two-dimensional critical nucleus has been measured, and the Gibbs-Thomson formula has been experimentally verified on orthorhombic lysozyme crystals. The step velocity was found to be independent of its length. The critical length initiating the step motion can be determined by a low density of kinks on a step, and not the critical-nucleus size. The invalidity of the Gibbs-Thomson formula in this case is discussed. (C) 2001 MAIK "Nauka/Interperiodica". C1 Moscow MV Lomonosov State Univ, Fac Phys, Moscow 119899, Russia. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Rashkovich, LN (reprint author), Moscow MV Lomonosov State Univ, Fac Phys, Vorobevy Gory, Moscow 119899, Russia. NR 8 TC 13 Z9 13 U1 0 U2 2 PU MAIK NAUKA/INTERPERIODICA PUBL PI MELVILLE PA C/O AMERICAN INST PHYSICS, 2 HUNTINGTON QUANDRANGLE, STE 1NO1, MELVILLE, NY 11747-4502 USA SN 1063-7745 J9 CRYSTALLOGR REP+ JI Crystallogr. Rep. PD SEP-OCT PY 2001 VL 46 IS 5 BP 860 EP 863 DI 10.1134/1.1405879 PG 4 WC Crystallography SC Crystallography GA 481WU UT WOS:000171544100027 ER PT J AU Lathouwers, D Bellan, J AF Lathouwers, D Bellan, J TI Yield optimization and scaling of fluidized beds for tar production from biomass SO ENERGY & FUELS LA English DT Article ID FLASH PYROLYSIS; FLOWS AB A numerical study is performed in order to evaluate the performance and optimal operating conditions of fluidized bed pyrolysis reactors used for condensable tar production from biomass. For this purpose, a previously validated biomass particle pyrolysis model is coupled with a detailed hydrodynamic model for the binary gas particle mixture. The kinetics scheme is based on superimposed cellulose, hemicellulose, and lignin reactions. Any biomass feedstock can be simulated through knowledge of its initial mass composition with respect to these three primary components. The separately validated hydrodynamic model is based on a three-fluid model (gas, sand, and biomass) derived from the kinetic theory of granular flows. Separate transport equations are constructed for each particle class, allowing for the description of such phenomena as particle segregation and for separate temperatures for each particle class. The model is employed to investigate the effect of various operating conditions on the efficiency of tar collection in fluidized bed reactors. Results indicate that, at fixed particle size, the operating temperature is the foremost parameter influencing tar yield, The biomass feed temperature, the feedstock, and fluidization velocity magnitude, all have minor impact on the yield. The particle diameter has a considerable influence on the short-time tar yield, but it is inferred that it may have a more moderate influence on the steady-state tar yield. For the range of fluidizing gas temperatures investigated, optimum steady-state tar collection is obtained for 750 K under the assumption that the pyrolysis rate is faster than the feed rate; the predicted optimum temperature is only slightly higher if this assumption is not satisfied. Finally, scale-up of the reactor is addressed and is found to have a small negative effect on tar collection at the optimal operating temperature. It is also found that slightly better scaling is obtained by using shallow fluidized beds with higher fluidization velocity. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bellan, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM josette.bellan@jpl.nasa.gov NR 23 TC 33 Z9 34 U1 1 U2 15 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0887-0624 EI 1520-5029 J9 ENERG FUEL JI Energy Fuels PD SEP-OCT PY 2001 VL 15 IS 5 BP 1247 EP 1262 DI 10.1021/ef010053h PG 16 WC Energy & Fuels; Engineering, Chemical SC Energy & Fuels; Engineering GA 477TH UT WOS:000171300000036 ER PT J AU Moran, MM Stein, TP Wade, CE AF Moran, MM Stein, TP Wade, CE TI Hormonal modulation of food intake in response to low leptin levels induced by hypergravity SO EXPERIMENTAL BIOLOGY AND MEDICINE LA English DT Article DE centrifugation; catecholamines; body mass regulation; epididymal fat ID AGOUTI OBESITY; PROOPIOMELANOCORTIN; MICE; HYPOTHALAMUS; EXPRESSION; NEURONS; WEIGHT; HUMANS; GENE; RATS AB A loss in fat mass is a common response to centrifugation and it results in low circulating leptin concentrations. However, rats adapted to hypergravity are euphagic. The focus of this study was to examine leptin and other peripheral signals of energy balance in the presence of a hypergravity-induced loss of fat mass and euphagia. Male Sprague-Dawley rats were centrifuged for 14 days at gravity levels of 1.25, 1.5, or 2 G, or they remained stationary at 1 G. Urinary catecholamines, urinary corticosterone, food intake, and body mass were measured on Days 11 to 14. Plasma hormones and epididymal fat pad mass were measured on Day 14. Mean body mass of the 1.26,1.5, and 2 G groups were significantly (P < 0.05) lower than controls, and no differences were found in food intake (g/day/100 g body mass) between the hypergravity groups and controls. Epididymal fat mass was 14%,14%, and 21% lower than controls in the 1.25, 1.5, and 2.0 G groups, respectively. Plasma leptin was significantly reduced from controls by 46%, 45%, and 65% in the 1.25,1.5, and 2 G groups, respectively. Plasma insulin was significantly tower in the 1.25, 1.5, and 2.0 G groups than controls by 35%,38%, and 33%. No differences were found between controls and hypergravity groups in urinary corticosterone. Mean urinary epinephrine was significantly higher in the 1.5 and 2.0 G groups than in controls. Mean urinary norepinephrine was significantly higher in the 1.25, 1.5 and 2.0 G groups than in controls. Significant correlations were found between G load and body mass, fat mass, leptin, urinary epinephrine, and norepinephrine. During hypergravity exposure, maintenance of food intake is the result of a complex relationship between multiple pathways, which abates the importance of leptin as a primary signal. C1 NASA, Ames Res Ctr, Life Sci Res Div, Moffett Field, CA 94035 USA. Univ Med & Dent New Jersey, Sch Osteopath Med, Dept Surg, Stratford, NJ 08084 USA. RP Wade, CE (reprint author), NASA, Ames Res Ctr, Life Sci Res Div, MS 239-11, Moffett Field, CA 94035 USA. NR 27 TC 23 Z9 23 U1 1 U2 1 PU SOC EXPERIMENTAL BIOLOGY MEDICINE PI MAYWOOD PA 195 WEST SPRING VALLEY AVE, MAYWOOD, NJ 07607-1727 USA SN 0037-9727 J9 EXP BIOL MED JI Exp. Biol. Med. PD SEP PY 2001 VL 226 IS 8 BP 740 EP 745 PG 6 WC Medicine, Research & Experimental SC Research & Experimental Medicine GA 466TM UT WOS:000170661900005 PM 11520939 ER PT J AU Sajdel-Sulkowska, EM Li, GH Ronca, AE Baer, LA Sulkowski, GM Koibuchi, N Wade, CE AF Sajdel-Sulkowska, EM Li, GH Ronca, AE Baer, LA Sulkowski, GM Koibuchi, N Wade, CE TI Effects of hypergravity exposure on the developing central nervous system: Possible involvement of thyroid hormone SO EXPERIMENTAL BIOLOGY AND MEDICINE LA English DT Article DE hypergravity; rat; cerebellum; development; thyroid hormone ID BRAIN-DEVELOPMENT; IODINE-DEFICIENCY; RAT; HYPOTHYROIDISM; TERM; HYPERTHYROIDISM; SPACEFLIGHT; THYROXINE; RESPONSES; PLASMA AB The present study examined the effects of hypergravity exposure on the developing brain and specifically explored the possibility that these effects are mediated by altered thyroid status. Thirty-four timed-pregnant Sprague-Dawley rats were exposed to continuous centrifugation at 1.5 G (HG) from gestational Day 11 until one of three key developmental points: postnatal Day (P) 6, P15, or P21 (10 pups/dam: 5 males/5 females). During the 32-day centrifugation, stationary controls (SC, n = 25 dams) were housed in the same room as HG animals. Neonatal body, forebrain, and cerebellum mass and neonatal and maternal thyroid status were assessed at each time point. The body mass of centrifuged neonates was comparatively lower at each time point. The mass of the forebrain and the mass of the cerebellum were maximally reduced in hypergravity-exposed neonates at P6 by 15.9% and 25.6%, respectively. Analysis of neonatal plasma suggested a transient hypothyroid status, as indicated by increased thyroid stimulating hormone (TSH) level (38.6%) at P6, while maternal plasma TSH levels were maximally elevated at P15 (38.9%). Neither neonatal nor maternal plasma TH levels were altered, suggesting a moderate hypothyroid condition. Thus, continuous exposure of the developing rats to hypergravity during the embryonic and neonatal periods has a highly significant effect on the developing forebrain and cerebellum and neonatal thyroid status (P < 0.05, Bonferroni corrected). These data are consistent with the hypothesized role of the thyroid hormone in mediating the effect of hypergravity in the developing central nervous system and begin to define the role of TH in the overall response of the developing organism to altered gravity. C1 Brigham & Womens Hosp, Dept Psychiat, Boston, MA 02115 USA. Harvard Univ, Sch Med, Dept Psychiat, Boston, MA 02115 USA. NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Lockheed Martin Engn & Sci, Moffett Field, CA 94035 USA. Harvard Univ, Program Cognit Neurosci, Cambridge, MA 02138 USA. Gunma Univ, Sch Med, Dept Physiol, Maebashi, Gumma 3718511, Japan. Gunma Univ, Sch Med, CREST, Maebashi, Gumma 3718511, Japan. RP Sajdel-Sulkowska, EM (reprint author), Brigham & Womens Hosp, Dept Psychiat, 75 Francis St, Boston, MA 02115 USA. NR 49 TC 18 Z9 18 U1 0 U2 1 PU SOC EXPERIMENTAL BIOLOGY MEDICINE PI MAYWOOD PA 195 WEST SPRING VALLEY AVE, MAYWOOD, NJ 07607-1727 USA SN 0037-9727 J9 EXP BIOL MED JI Exp. Biol. Med. PD SEP PY 2001 VL 226 IS 8 BP 790 EP 798 PG 9 WC Medicine, Research & Experimental SC Research & Experimental Medicine GA 466TM UT WOS:000170661900012 PM 11520946 ER PT J AU Bishop, JL Lougear, A Newton, J Doran, PT Froeschl, H Trautwein, AX Korner, W Koeberl, C AF Bishop, JL Lougear, A Newton, J Doran, PT Froeschl, H Trautwein, AX Korner, W Koeberl, C TI mineralogical and geochemical analyses of Antarctic lake sediments: A study of reflectance and Mossbauer spectroscopy and C, N, and S isotopes with applications for remote sensing on Mars SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Review ID DEEP-SEA SEDIMENTS; THERMAL EMISSION-SPECTRA; MCMURDO DRY VALLEYS; SULFATE REDUCTION; MASS-SPECTROMETER; OPTICAL-CONSTANTS; RESIDENCE TIMES; ICE; CARBON; SULFUR AB We analyzed lake-bottom sediments from the Dry Valleys region of Antarctica to study the influence of water chemistry on the mineralogy and geochemistry of these sediments, as well as to evaluate techniques for remote spectral identification of potential biomarker minerals on Mars. Lakes from the Dry Valleys region of Antarctica have been investigated as possible analogs for extinct lake environments on early Mars. Sediment cores were collected in the present study from perennially ice-covered Lake Hoare in the Taylor Valley. These sediments were taken from a core in an oxic region of the lake and another core in an anoxic zone. Differences between the two cores were observed in the sediment color, Fe(II)/Fe(III) ratio, the presence of pyrite, the abundance of Fe, S, and some trace elements, and the C, N, and S isotope fractionation patterns. The results of visible-infrared reflectance spectroscopy (0.3-25 mum), Mossbauer spectroscopy (77 and 4 K), and X-ray diffraction are combined to determine the mineralogy and composition of these samples. The sediments are dominated by plagioclase, K-feldspar, quartz, and pyroxene. Algal mats grow on the bottom of the lake and organic material has been found throughout the cores. Calcite is abundant in some layers of the sediment core from the shallow, oxic region, and pyrite is abundant in the upper sediment layers of the core from the deep, anoxic region of Lake Hoare. Analysis of the spectroscopic features due to organics and carbonates with respect to the abundance of organic C and carbonate contents was performed in order to select optimal spectral bands for remote identification of these components in planetary regoliths. Carbonate bands near 4 and 6.8 mum (similar to 2500 and 1500 cm(-1)) were detected for carbonate abundances as low as 0.1 Wt% CO2. Organic features at 3.38, 3.42, and 3.51 mum (2960, 2925, and 2850 cm(-1)) were detected for organic C abundances as low as 0.06 wt% C. The delta C-3 and delta N-15 trends show a more complex organic history for the anoxic region sediments than for the oxic region sediments. The biogenic pyrite found in the core from the anoxic zone is associated with depleted delta S-34 values and high organic C levels and could be used as a potential biomarker mineral for paleolakes on Mars. Copyright (C) 2001 Elsevier Science Ltd. C1 NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. Med Univ Lubeck, Inst Phys, D-23538 Lubeck, Germany. Univ Calif Santa Cruz, Santa Cruz, CA 95064 USA. Univ Illinois, Chicago, IL 60607 USA. Austrian Res Ctr Seibersdorf, A-1030 Vienna, Austria. Univ Vienna, Inst Geochem, A-1090 Vienna, Austria. RP Bishop, JL (reprint author), NASA, Ames Res Ctr, SETI Inst, MS-239-4, Moffett Field, CA 94035 USA. RI Newton, Jason/A-9536-2009 OI Newton, Jason/0000-0001-7594-3693 NR 101 TC 29 Z9 31 U1 2 U2 21 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD SEP PY 2001 VL 65 IS 17 BP 2875 EP 2897 DI 10.1016/S0016-7037(01)00651-2 PG 23 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 472HK UT WOS:000170977900006 ER PT J AU Cho, JYN Newell, RE Browell, EV Grant, WB Butler, CF Fenn, MA AF Cho, JYN Newell, RE Browell, EV Grant, WB Butler, CF Fenn, MA TI Observation of pollution plume capping by a tropopause fold SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WAVE INDUCED LAMINAE; STRATOSPHERIC INTRUSIONS; SEASONAL EVOLUTION; OZONESONDE DATA; BOUNDARY-LAYER; TROPOSPHERE; AIR; SUBTROPICS; TRANSPORT; POLINAT-2 AB Airborne lidar measurements reveal a case in which a layer of high-ozone air extruding from a tropopause fold appears to cap a pollution plume and force it to spread out in the lower troposphere. The morphology of the high-ozone layer resembles a three-dimensional model of tropopause fold evolution that produces a low-altitude potential vorticity tube. This is a mechanism that can complete the irreversible transfer of air from the stratosphere, and can also affect pollution levels at the surface if the capping layer reaches the top of the boundary layer. C1 MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Sci Applicat Int Corp, Hampton, VA 23666 USA. RP Cho, JYN (reprint author), MIT, Dept Earth Atmospher & Planetary Sci, 77 Massachusetts Ave,54-1823, Cambridge, MA 02139 USA. RI Grant, William/B-8311-2009 OI Grant, William/0000-0002-1439-3285 NR 22 TC 13 Z9 13 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 SEP 1 PY 2001 VL 28 IS 17 BP 3243 EP 3246 DI 10.1029/2001GL012898 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 467JM UT WOS:000170698700007 ER PT J AU Kaufman, YJ Smirnov, A Holben, BN Dubovik, O AF Kaufman, YJ Smirnov, A Holben, BN Dubovik, O TI Baseline maritime aerosol: methodology to derive the optical thickness and scattering properties SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SKY RADIANCE MEASUREMENTS; RETRIEVAL; AERONET; NUMBER; ALGORITHM; NETWORK; AVHRR; OCEAN; SUN AB Satellite measurements of the global distribution of aerosol and their effect on climate should be viewed in respect to a baseline aerosol. In this concept, concentration of fine mode aerosol particles is elevated above the baseline by man-made activities (smoke or urban pollution), while dust or sea-spray elevates the coarse mode. Using 1-3 years of measurements in 10 stations of the Aerosol Robotic network (AERONET) we develop a methodology and derive the optical thickness and properties of this baseline aerosol for the Pacific and Atlantic Oceans. Defined as the median for periods of stable optical thickness (standard deviation < 0.02) during 2-6 days, the median baseline aerosol optical thickness over the Pacific Ocean is 0.052 at 500 nm with Angstrom ngstrom exponent of 0.77, and 0.071 and 1.1 respectively, over the Atlantic Ocean. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. RP Kaufman, YJ (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Dubovik, Oleg/A-8235-2009; Smirnov, Alexander/C-2121-2009 OI Dubovik, Oleg/0000-0003-3482-6460; Smirnov, Alexander/0000-0002-8208-1304 NR 23 TC 69 Z9 74 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 2001 VL 28 IS 17 BP 3251 EP 3254 DI 10.1029/2001GL013312 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 467JM UT WOS:000170698700009 ER PT J AU Wickert, J Reigber, C Beyerle, G Konig, R Marquardt, C Schmidt, T Grunwaldt, L Galas, R Meehan, TK Melbourne, WG Hocke, K AF Wickert, J Reigber, C Beyerle, G Konig, R Marquardt, C Schmidt, T Grunwaldt, L Galas, R Meehan, TK Melbourne, WG Hocke, K TI Atmosphere sounding by GPS radio occultation: First results from CHAMP SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GLOBAL POSITIONING SYSTEM; IONOSPHERE; SATELLITES; VALIDATION; INVERSION; ORBIT AB The first radio occultation measurements of the CHAMP (CHAllenging Minisatellite Payload) satellite using Global Positioning System (CPS) signals have been performed on February 11, 2001. By the end of April 2001 more than 3000 occultations were recorded. Globally distributed vertical profiles of dry temperature and specific humidity are derived, of which a set of 438 vertical dry temperature profiles is compared with corresponding global weather analyses. The observed temperature bias is less than similar to1 K above the tropopause and even less than 0.5 K in the altitude interval from 12 to 20 km at latitudes > 30 degreesN. About 55% of the compared profiles reached the last kilometer above the Earth's surface. In spite of the activated anti-spoofing mode of the CPS system the state-of-the-art CPS flight receiver aboard CHAMP combined with favorable antenna characteristics allows for atmospheric sounding with high accuracy and vertical resolution. C1 Geoforschungszentrum Potsdam, Div 1, D-14473 Potsdam, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Commun Res Labs, Div Space Sci, Koganei, Tokyo 1848795, Japan. RP Wickert, J (reprint author), Geoforschungszentrum Potsdam, Div 1, Telegrafenberg, D-14473 Potsdam, Germany. RI Schmidt, Torsten/A-7142-2013; Wickert, Jens/A-7257-2013 OI Schmidt, Torsten/0000-0001-9302-1000; NR 30 TC 280 Z9 299 U1 1 U2 20 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 2001 VL 28 IS 17 BP 3263 EP 3266 DI 10.1029/2001GL013117 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 467JM UT WOS:000170698700012 ER PT J AU Hernandez-Pajares, M Juan, JM Sanz, J Colombo, OL van der Marel, H AF Hernandez-Pajares, M Juan, JM Sanz, J Colombo, OL van der Marel, H TI A new strategy for real-time integrated water vapor determination in WADGPS networks SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID METEOROLOGY; DELAY AB A major issue in many applications of CPS is the real-time estimation of the Zenith Tropospheric Delays (ZTD). Several authors have developed strategies that estimate ZTD, with a latency of one hour or more in order to compute Integrated Water Vapor (IWV), using local measurements of surface pressure, or to assimilate ZTD into Numerical Weather Predicition. (NWP) models. These strategies require that data from a regional CPS network be processed in near real-time, using precise IGS orbits and partial orbit relaxation. Recently it has been shown that in Wide Area Differential CPS (WADGPS) networks of several hundred kilometers across, double-differenced carrier phase ambiguities can be computed on-the-fly, using a real-time tomographic model of the ionosphere obtained from the same CPS data. In this work we show how ambiguity resolution can help determine in real-time the ZTD for a WADGPS network user, only 10-20% worse than those of the postprocessed solutions. C1 Univ Politecn Catalunya, Grp Astron & Geomat, E-08034 Barcelona, Spain. NASA, Goddard Space Flight Ctr, GEST, Greenbelt, MD 20771 USA. Delft Univ Technol, NL-2629 JA Delft, Netherlands. RP Hernandez-Pajares, M (reprint author), Univ Politecn Catalunya, Grp Astron & Geomat, C Nord 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; Hernandez-Pajares, Manuel/0000-0002-9687-5850 NR 12 TC 11 Z9 11 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 SEP 1 PY 2001 VL 28 IS 17 BP 3267 EP 3270 DI 10.1029/2001GL012930 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 467JM UT WOS:000170698700013 ER PT J AU Martonchik, JV Kahn, RA Diner, DJ West, RA AF Martonchik, JV Kahn, RA Diner, DJ West, RA TI Comments on: Retrieval of aerosol properties over the ocean using multispectral and multiangle photopolarimetric measurements from the Research Scanning Polarimeter SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INSTRUMENT AB A recent paper [Chowdhary et al., 2001] (hereafter CCM&T) presents an aerosol retrieval case study using airborne RSP (Research Scanning Polarimeter) data over dark water to demonstrate the contribution polarization measurements can make to passive aerosol remote sensing. The paper also suggests that instruments such as MODIS (Moderate Resolution Imaging Spectroradiometer) [Barnes et al., 1998], MISR (Multi-angle Imaging SpectroRadiometer) [Diner et al., 1998], and POLDER (Polarization and Directionality of Earth Reflectances) (Deschamps et al., 1994], provide only a subset of the retrieval capabilities that would be available from EOSP (Earth Observing Scanning Polarimeter) [Travis, 1993], a satellite version of RSP. In this response, we argue that EOSP is not a replacement but a valuable complement to other measurement approaches. We also contend that MISR is significantly more capable than CCM&T imply. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Martonchik, JV (reprint author), CALTECH, Jet Prop Lab, Mail Stop 169-237,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Kahn, Ralph/D-5371-2012 OI Kahn, Ralph/0000-0002-5234-6359 NR 11 TC 0 Z9 0 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 2001 VL 28 IS 17 BP 3275 EP 3276 DI 10.1029/2001GL013201 PG 2 WC Geosciences, Multidisciplinary SC Geology GA 467JM UT WOS:000170698700015 ER PT J AU Cairns, B Mishchenko, M Travis, L Chowdhary, J AF Cairns, B Mishchenko, M Travis, L Chowdhary, J TI Reply to comment on "Retrieval of aerosol properties over the ocean using multispectral and multiangle photopolarimetric measurements from the Research Scanning Polarimeter" SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SATELLITE RETRIEVAL; REFLECTED SUNLIGHT; POLARIZATION AB In a recent paper [Chowdhary et al., 2001; hereafter CCM&T], we showed that the inclusion of polarimetric information provides superior results in the retrieval of aerosol properties to those obtained using only the intensity. Having previously shown detailed theoretical analyses of the superiority of well calibrated polarimetric remote sensing to intensity only remote sensing of aerosols [Mishchenko and Travis 1997a, b], the purpose of CCM&T was to demonstrate that such analyses carry over to actual measurements. The excellent agreement between upward looking sunphotometer measurements of spectral optical depth and those inferred from the Research Scanning Polarimeter (RSP) measurements (Fig. 2 of CCM&T) provides a first demonstration of the validity of the previous theoretical analyses in a natural setting. In their commentary [this issue] Martonchik, Kahn, Diner and West (hereafter MKD&W) discuss the complementarity of polarimetric remote sensing and the type of measurements made by MISR. We would concur with MKD&W that it is "essential to validate retrieved spectral refractive indices and particle size distributions" that are possible with polarimetric measurements, just as it is essential to evaluate and validate the true capabilities of MISR. We look forward to such evaluation and analysis of RSP measurements in future co-ordinated field campaigns. In the following we discuss why we believe the set of measurements and the analysis presented in CCM&T provides a fair, although not perfect, representation of the capabilities of MISR and discuss the other issues raised by MKD&W. C1 Columbia Univ, Dept Appl Phys & Appl Math, New York, NY USA. RP Cairns, B (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Mishchenko, Michael/D-4426-2012 NR 12 TC 0 Z9 0 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 2001 VL 28 IS 17 BP 3277 EP 3278 DI 10.1029/2001GL013344 PG 2 WC Geosciences, Multidisciplinary SC Geology GA 467JM UT WOS:000170698700016 ER PT J AU Dunlop, DJ Kletetschka, G AF Dunlop, DJ Kletetschka, G TI Multidomain hematite: A source of planetary magnetic anomalies? SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Thermoremanent magnetization (TRM) in hematite is larger than TRM in magnetite for grain sizes greater than or equal to 10 mum. We show that hematite's weak spontaneous magnetization M-s causes its strong TRM, since the self-demagnetizing field H-d opposing large domain wall displacements is proportional to M-s. In hematite, H-d is comparable to the Earth's magnetic field but in magnetite, H-d is 1000 times larger. As a result, Earth's field TRM of MD hematite (approximate to0.3 Am-2/kg) outweighs TRM and induced magnetization of MD magnetite (approximate to0.01-0.02 Am-2/kg) and rivals TRM of single-domain and PSD magnetite as a source of magnetic anomalies on Earth and perhaps on Mars. C1 Univ Toronto, Dept Phys, Mississauga, ON L5L 1C6, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Dunlop, DJ (reprint author), Univ Toronto, Dept Phys, 3359 Mississuaga Rd N, Mississauga, ON L5L 1C6, Canada. RI Kletetschka, Gunther/C-9996-2011 OI Kletetschka, Gunther/0000-0002-0645-9037 NR 22 TC 40 Z9 40 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 SEP 1 PY 2001 VL 28 IS 17 BP 3345 EP 3348 DI 10.1029/2001GL013125 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 467JM UT WOS:000170698700034 ER PT J AU Gatebe, CK Tyson, PD Annegarn, HJ Helas, G Kinyua, AM Piketh, SJ AF Gatebe, CK Tyson, PD Annegarn, HJ Helas, G Kinyua, AM Piketh, SJ TI Characterization and transport of aerosols over equatorial eastern Africa SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID TROPICAL SOUTH-ATLANTIC; LONG-RANGE TRANSPORT; ATMOSPHERIC CHEMISTRY; SIZE DISTRIBUTION; TRACE-ELEMENTS; CLOUD ALBEDO; INDIAN-OCEAN; SAHARAN DUST; PIXE; CLIMATE AB Measurements of the composition of aerosol partitioned into two size fractions, fine (particle aerodynamic equivalent diameter, d(p) less than or equal to 2.5 mum) and coarse (2.5 < d(p) less than or equal to 10 mum) were made at a high-altitude site over equatorial eastern Africa on Mount Kenya to study long-range transport of aerosol and to determine the extent of interhemispheric transport at the equator. The two size fractions allow long-range transport aerosol to be distinguished from those more locally derived. Background midtropospheric elemental aerosol concentrations observed on Mount Kenya, for 3 example, S = 0.0157 mug m-(3), are lower than commensurate findings for remote areas in industrialized countries and elsewhere in Africa but are 3 factors higher than concentrations reported from the South Pole. Locally derived aerosols are frequently transported up the slopes of Mount Kenya by day in valley winds but are rarely transported at night in the stable conditions characterized by downslope katabatic, flow. Nocturnal conditions favor the measurement of long-range, midtropospheric transport products to Kenya from afar. Case studies reveal that anthropogenically derived S and Fe aerosols from both southernmost and central southern Africa may be observed on Mount Kenya after transport over distances > 6000 kin. So-called pristine marine air from the central Indian Ocean is shown to contain aged and recirculated Si that could only have been derived from land areas after transport over long distances. The nature of the aerosols measured on Mount Kenya depends critically on regional patterns of aerosol transport. Interregional transfers seem to be a feature of the transport climatology. Likewise, interhemispheric transport across the equator in east Africa is observed. C1 Maryland Psychiat Res Ctr, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21228 USA. Univ Witwatersrand, Climatol Res Grp, ZA-2050 Johannesburg, South Africa. Univ Witwatersrand, Atmospher & Energy Res Grp, ZA-2050 Johannesburg, South Africa. Max Planck Inst Chem, Biogeochem Dept, D-55020 Mainz, Germany. Univ Nairobi, Inst Nucl Sci, Nairobi, Kenya. RP Gatebe, CK (reprint author), Maryland Psychiat Res Ctr, Goddard Earth Sci & Technol Ctr, POB 21247, Baltimore, MD 21228 USA. RI Annegarn, Harold/A-9127-2008; Gatebe, Charles/G-7094-2011 OI Annegarn, Harold/0000-0001-6653-4679; Gatebe, Charles/0000-0001-9261-2239 NR 72 TC 9 Z9 9 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD SEP PY 2001 VL 15 IS 3 BP 663 EP 672 DI 10.1029/2000GB001340 PG 10 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA 468WJ UT WOS:000170780900010 ER PT J AU Nezlek, JB Austin-Lane, J Null, CH AF Nezlek, JB Austin-Lane, J Null, CH TI Multidimensional scaling analyses of the perceived social structure of informal groups SO GROUP DYNAMICS-THEORY RESEARCH AND PRACTICE LA English DT Article AB Four groups of student hallmates provided similarity ratings of each other, and they rated each other on various characteristics. Group-level multidimensional scaling analyses suggested that there was no consensual social structure in any of the four groups. In contrast, individual-level analyses found that individuals had coherent perceptions of the social structures of their groups, although no 2 members of any group perceived the social structure of their group similarly. Nevertheless, there was considerable similarity among people in the dimensions underlying their perceived structures. Conventionality, friendliness, influence, and interpersonal openness served as organizing dimensions for the majority of participants, and sense of humor, how hard it was to get along with people, introversion. interesting, and academic orientation were important bases for about a third of the participants. C1 Coll William & Mary, Dept Psychol, Williamsburg, VA 23187 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Nezlek, JB (reprint author), Coll William & Mary, Dept Psychol, POB 8795, Williamsburg, VA 23187 USA. RI LI, XIA/A-1235-2013; Demenkov, Valentin/B-4755-2014; Легкоступ, Ігор/C-9702-2016; Yehorov, Bohdan/Q-1365-2015; OI LI, XIA/0000-0003-3050-8529; Demenkov, Valentin/0000-0002-4016-8671; Легкоступ, Ігор/0000-0001-7839-874X; Yehorov, Bohdan/0000-0001-7526-0315; Nezlek, John/0000-0003-4963-3637 NR 15 TC 0 Z9 0 U1 0 U2 0 PU EDUCATIONAL PUBLISHING FOUNDATION PI WASHINGTON PA 750 FIRST ST, NE, WASHINGTON, DC 20002-4242 USA SN 1089-2699 J9 GROUP DYN-THEOR RES JI Group Dyn.-Theory Res. Pract. PD SEP PY 2001 VL 5 IS 3 BP 200 EP 207 DI 10.1037//1089-2699.5.3.200 PG 8 WC Psychology, Social SC Psychology GA 503CW UT WOS:000172780900004 ER PT J AU Alexander, MA Hill, DJT Connell, JW Watson, KA AF Alexander, MA Hill, DJT Connell, JW Watson, KA TI A study of the vacuum gamma-radiolysis of two aromatic polyimide fluoropolymers containing phenylphosphine oxide SO HIGH PERFORMANCE POLYMERS LA English DT Article ID RADIATION DEGRADATION; POLY(ARYLENE AB The vacuum gamma -radiolysis of two fluorinated polyimides containing phenylphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied at 77 K and 300 K. The phenyl phosphine oxide units provide protection of the polymers towards oxidation by oxygen atoms and the bulky fluoromethyl groups reduce the colouration of the polymers by limiting donor-acceptor complex formation through the aromatic units. At 77 K the radicals formed were identified to be a mixture of neutral radicals (60%) and anion radicals. At 300 K only neutral radicals were found. The G-values for radical formation were found to be 0.50 and 0.42 at 77 K and 0.051 and 0.052 at 300 K for TOR-RC and TOR-RC ODPA, respectively. Little change was observed in the visible spectra of the polyimides following vacuum radiolysis at 300 K up to a dose of 3.3 MGy, and the polymers were shown to undergo net cross linking with a gel dose of 0.45 MGy. C1 Univ Queensland, Dept Chem, Polymer Mat & Radiat Grp, Brisbane, Qld 4072, Australia. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hill, DJT (reprint author), Univ Queensland, Dept Chem, Polymer Mat & Radiat Grp, Brisbane, Qld 4072, Australia. NR 16 TC 1 Z9 1 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD SEP PY 2001 VL 13 IS 3 BP 67 EP 78 DI 10.1088/0954-0083/13/3/301 PG 12 WC Polymer Science SC Polymer Science GA 484GP UT WOS:000171682100016 ER PT J AU de Groh, KK Gummow, JD AF de Groh, KK Gummow, JD TI Effect of air and vacuum storage on the tensile properties of x-ray exposed aluminized-FEP SO HIGH PERFORMANCE POLYMERS LA English DT Article; Proceedings Paper CT 8th International Symposium on Materials in A Space Environment/5th International Conference on Protection of Materials and Structures from the Space Environment CY JUN 05-09, 2000 CL ARCACHON, FRANCE AB Metallized Teflon (R) FEP (fluorinated ethylene propylene), a common spacecraft thermal control material, which forms the exterior layer of the Hubble Space Telescope (HST) has become embrittled and suffers from extensive cracking. Teflon (R) samples retrieved during Hubble servicing missions and from the Long Duration Exposure Facility (LDEF) indicate that there may be continued degradation in the tensile properties over time. An investigation has been conducted to evaluate the effect of air and vacuum storage on the mechanical properties of x-ray exposed FER Aluminized-FEP (Al-FEP) tensile samples were irradiated with 15.3 kV Cu x-rays and stored in air or under vacuum for various time periods. Tensile data indicate that samples stored in air display larger decreases in their tensile properties than for samples stored under vacuum. Air-stored samples developed a hazy appearance, which corresponded to a roughening of the aluminized surface. Optical property changes were also characterized. These findings indicate that air exposure plays a role in the degradation of irradiated FEP, therefore proper sample handling and storage is necessary with materials retrieved from space. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. RP de Groh, KK (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS 309-2, Cleveland, OH 44135 USA. NR 14 TC 4 Z9 4 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD SEP PY 2001 VL 13 IS 3 BP S421 EP S431 PG 11 WC Polymer Science SC Polymer Science GA 484GP UT WOS:000171682100005 ER PT J AU de Groh, KK Dever, JA Sutter, JK Gaier, JR Gummow, JD Scheiman, DA He, C AF de Groh, KK Dever, JA Sutter, JK Gaier, JR Gummow, JD Scheiman, DA He, C TI Thermal contributions to the degradation of Teflon (R) FEP on the Hubble Space Telescope SO HIGH PERFORMANCE POLYMERS LA English DT Article; Proceedings Paper CT 8th International Symposium on Materials in A Space Environment/5th International Conference on Protection of Materials and Structures from the Space Environment CY JUN 05-09, 2000 CL ARCACHON, FRANCE AB Metallized Teflon (R) fluorinated ethylene propylene (FEP) thermal control material on the Hubble Space Telescope (HST) is degrading in the space environment. Teflon (R) FEP insulation was retrieved during servicing missions, which occurred in 1993, 1997 and 1999. During the second servicing mission (SM2), the 5 mil aluminized-FEP (Al-FEP) outer layer of multilayer insulation (MLI) covering the telescope was found to be cracked in many locations around the telescope. Teflon (R) FEP retrieved during SM2 was more embrittled than the FEP retrieved 2.8 years later from a different location, during the third servicing mission (SM3A). Studies have been conducted to understand the degradation of FEP on HST, and the difference in the degree of degradation of FEP from each of the servicing missions. The retrieved SM2 material experienced a higher temperature extreme during thermal cycling (200 degreesC) than the first servicing mission (SMI) and SM3A materials (upper temperature of 50 degreesC), therefore an investigation on the effects of heating FEP was also conducted. Samples of pristine FEP and SM1, SM2 and SM3A retrieved FEP were heated to 200 degreesC and evaluated for changes in properties. Heating at 130 degreesC was also investigated because FEP bi-stern thermal shields are expected to cycle to a maximum temperature of 130 degreesC on-orbit. Tensile, density, x-ray diffraction crystallinity and differential scanning calorimetry data were evaluated. It was found that heating pristine FEP caused an increase in the density and practically no change in tensile properties. However, when as-retrieved space samples were heated, the density increased and the tensile properties decreased. Upon heating, all samples experienced an increase in crystallinity, with larger increases in the space-exposed FER These results indicate that irradiation of FEP in space causes chain scission, resulting in embrittlement, and that excessive heating allows increased mobility of space-environment-induced scissioned chains. Thermal exposure was therefore found to have a major impact on the extent of embrittlement of FEP on HST. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Brookpark, OH 44142 USA. Dynacs Engn Inc, Brookpark, OH 44142 USA. Swales Aerosp, Beltsville, MD 20705 USA. RP de Groh, KK (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 11 TC 11 Z9 11 U1 0 U2 8 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD SEP PY 2001 VL 13 IS 3 BP S401 EP S420 PG 20 WC Polymer Science SC Polymer Science GA 484GP UT WOS:000171682100004 ER PT J AU Dever, JA Messer, R Powers, C Townsend, J Wooldridge, E AF Dever, JA Messer, R Powers, C Townsend, J Wooldridge, E TI Effects of vacuum ultraviolet radiation on thin polyimide films SO HIGH PERFORMANCE POLYMERS LA English DT Article; Proceedings Paper CT 8th International Symposium on Materials in A Space Environment/5th International Conference on Protection of Materials and Structures from the Space Environment CY JUN 05-09, 2000 CL ARCACHON, FRANCE AB This paper describes the vacuum ultraviolet (VUV) radiation durability screening testing of thin (12.7-25.4 mum) polyimide films proposed for use on the Next Generation Space Telescope (NGST) sunshield. Materials included in this screening test were Kapton (R)E, Kapton (R) HN, Upilex (R)S, CP1, CP1 with vapour deposited aluminium (VDA) on its back surface, and CP2 with a VDA coating on its back surface. Samples were exposed to approximately 1000 equivalent sun hours (ESH) of VUV radiation and examined for changes in solar absorptance, thermal emittance, ultimate tensile strength, and elongation at failure. Changes in the solar absorptance were observed for some materials, and, additionally, significant changes in spectral reflectance were observed in the ultraviolet to visible wavelength region for all of the polyimide. materials tested. Changes in the ultimate tensile strength and elongation at failure were within the experimental uncertainty for all samples. Longer exposures are needed to verify the observed trends and to develop performance predictions for these materials on the NGST sunshield. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Cleveland State Univ, Cleveland, OH 44115 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Dever, JA (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,MS 309-2, Cleveland, OH 44135 USA. NR 9 TC 5 Z9 5 U1 1 U2 9 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD SEP PY 2001 VL 13 IS 3 BP S391 EP S399 DI 10.1088/0954-0083/13/3/331 PG 9 WC Polymer Science SC Polymer Science GA 484GP UT WOS:000171682100003 ER PT J AU Dever, JA de Groh, KK Messer, RK McClendon, MW Viens, M Wang, LL Gummow, JD AF Dever, JA de Groh, KK Messer, RK McClendon, MW Viens, M Wang, LL Gummow, JD TI Mechanical properties of Teflon((R)) FEP retrieved from the hubble space telescope SO HIGH PERFORMANCE POLYMERS LA English DT Article; Proceedings Paper CT 8th International Symposium on Materials in A Space Environment/5th International Conference on Protection of Materials and Structures from the Space Environment CY JUN 05-09, 2000 CL ARCACHON, FRANCE AB Teflon (R) FEP (fluorinated ethylene propylene) surfaces on the Hubble Space Telescope (HST) have experienced significant degradation in mechanical properties during nearly ten years of exposure in the low Earth orbit environment. This paper describes results of mechanical properties testing of Teflon (R) FEP materials exposed on HST for 9.7 years between launch and the third servicing mission (SM3A) and for 2.8 years between the second servicing mission (SM2) and SM3A. The results of tensile testing, bend testing and microscopic examination of crack morphology are described. The effects of post-retrieval heating and air compared with vacuum storage on the mechanical properties of the FEP surfaces are described as they significantly affect the interpretation of the results regarding the durability of FEP on HST. This paper provides comparisons of the properties of FEP surfaces retrieved during SM3A to previously reported results for FEP materials retrieved during the first servicing mission (SM1) and SM2. The environmental exposure conditions for the HST exposed materials are also described. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Cleveland State Univ, Cleveland, OH 44115 USA. NASA, Goddard Space Flight Ctr, Swales Aerosp, Greenbelt, MD 20771 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. RP Dever, JA (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 13 TC 13 Z9 13 U1 0 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD SEP PY 2001 VL 13 IS 3 BP S373 EP S390 DI 10.1088/0954-0083/13/3/330 PG 18 WC Polymer Science SC Polymer Science GA 484GP UT WOS:000171682100002 ER PT J AU Oberst, J Mottola, S Di Martino, M Hicks, M Buratti, B Soderblom, L Thomas, N AF Oberst, J Mottola, S Di Martino, M Hicks, M Buratti, B Soderblom, L Thomas, N TI A model for rotation and shape of asteroid 9969 Braille from ground-based observations and images obtained during the deep space 1 (DS1) flyby SO ICARUS LA English DT Article DE asteroids; rotation ID BIDIRECTIONAL REFLECTANCE SPECTROSCOPY; RADAR AB Image data from the DSI encounter with Asteroid 9969 Braille and data from a coordinated ground-based photometric observing campaign are combined to study the physical properties of this small Mars crosser. From telescope data the object's brightness was found to vary by up to 0.5 mag from night to night, with the most probable synodic rotational period being 226.4 +/- 1.3 h (9.4 days) and a mean lightcurve magnitude R(1, alpha = 24) =17.04 +/- 0.10. During the flyby of the spacecraft, two frame images from a range of approximately 13,500 km and phase angle 82.4 degrees, which impose strong constraints on size, shape, and albedo of the object, were obtained. Using telescope and flyby data in combination, the asteroid is estimated to have a size of 2.1 x 1 x 1 km(3) and shown to have photometric properties similar to the asteroid 4 Vesta, notably a comparably high albedo. The high albedo supports the notion (L. Soderblom et at. 1999, Bull. Am. Astron. Soc. 31,) that Braille is of the V or Q taxonomic type. (C) 2001 Academic Press. C1 DLR, Inst Space Sensor Technol & Planetary Explorat, D-12489 Berlin, Germany. Osservatorio Torino, Turin, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. US Geol Survey, Flagstaff, AZ 86001 USA. Max Planck Inst Aeron, Katlenburg Duhm, Germany. RP Oberst, J (reprint author), DLR, Inst Space Sensor Technol & Planetary Explorat, Rutherfordstr 2, D-12489 Berlin, Germany. NR 27 TC 9 Z9 9 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 SEP PY 2001 VL 153 IS 1 BP 16 EP 23 DI 10.1006/icar.2001.6648 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 481JE UT WOS:000171515500002 ER PT J AU Kuzmin, RO Greeley, R Rafkin, SCR Haberle, R AF Kuzmin, RO Greeley, R Rafkin, SCR Haberle, R TI Wind-related modification of some small impact craters on Mars SO ICARUS LA English DT Article ID PATHFINDER LANDING SITE; CHAOTIC OBLIQUITY; CAMERA AB Inferred wind-related modifications of impact craters are observed in the vicinity of the Mars Pathfinder (MPF) site and in other regions of Mars. Mars Obiter Camera (MOC) images show three types of inferred wind-modified morphologies for craters 0.3-1 km in diameter. Such modifications could be related to seasonal variations of the strongest winds and a possible paleowind regime. Geomorphic mapping of Big Crater at the MPF shows evidence of former aeolian modification of the crater rim and interiors similar to smaller craters in the area. The morphologic patterns are in good agreement with the results from the Mars Regional Atmospheric Modeling Simulation (MRAMS) of topographically forced wind circulation and atmosphere-surface interactions generated by flow over small craters. Simulations show that the maximum surface stress is on the downwind crater rim, consistent with inferred wind modification of the crater rim seen in MOC images. The trend of the inferred paleowind regime at the MPF site cannot be explained by a change in the global atmospheric circulation resulting from changes in Mars' obliquity. We suggest that this wind regime could be associated with a regional meteorological pattern that is not modeled by global scale circulation. An alternative explanation is that Mars' spin axis was in a different geographic position than it is at present. (C) 2001 Academic Press. C1 VI Vernadskii Inst Geochem & Analyt Chem, Moscow 117975, Russia. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. San Jose State Univ, Dept Meteorol, San Jose, CA 95192 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kuzmin, RO (reprint author), VI Vernadskii Inst Geochem & Analyt Chem, Kosygin St 19,GSP-1, Moscow 117975, Russia. NR 21 TC 12 Z9 12 U1 1 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 SEP PY 2001 VL 153 IS 1 BP 61 EP 70 DI 10.1006/icar.2001.6654 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 481JE UT WOS:000171515500006 ER PT J AU Zahnle, K Schenk, P Sobieszczyk, S Dones, L Levison, HF AF Zahnle, K Schenk, P Sobieszczyk, S Dones, L Levison, HF TI Differential cratering of synchronously rotating satellites by ecliptic comets SO ICARUS LA English DT Article DE cratering; satellites; general; comets; satellites of Jupiter; Triton ID JUPITER-FAMILY COMETS; SIZE DISTRIBUTION; KUIPER-BELT; STATISTICS; CALLISTO; GANYMEDE; OBJECTS; CHAINS; POPULATION; SURFACE AB We use Monte Carlo methods to simulate impacts of ecliptic comets on the synchronously rotating satellites of giant planets. We reconfirm the long-standing prediction that the cratering rate should be much higher on the leading hemispheres than on the trailing hemisphere; indeed we find that previously published analytical formulations modestly underestimate the degree of apex-antapex asymmetry to be expected. We then compare our results to new mapping of impact craters on Ganymede, Callisto, and Triton. Ganymede reveals a pronounced apex-antapex asymmetry that is nonetheless much less than predicted. All of Triton's confirmed impact craters are clustered toward the apex of motion, far exceeding the predicted asymmetry. No asymmetry is observed on Callisto. In each case at least one of our basic assumptions must be wrong. Likely candidates include the following: (i) the surfaces of all but the most sparsely cratered satellites are saturated or nearly saturated with impact craters; (ii) these satellites have rotated nonsynchronously over geological time; (iii) most of the craters are made not by heliocentric (Sun-orbiting) comets and asteroids but rather by planetocentric (planet-orbiting) debris of indeterminate origin; or (iv) pathological endogenic resurfacing has created illusions of structure. Callisto's surface is readily classified as nearly saturated. Ganymede's bright terrains, although less heavily cratered than those of Callisto, can also be explained by crater densities approaching saturation on a world where endogenic processes were active. The leading alternative is nonsynchronous rotation, an explanation supported by the distribution of catenae (crater chains produced by impact of tidally disrupted comets). Triton's craters can be explained by planetocentric debris or by capricious resurfacing, but both hypotheses are inherently improbable. (C) 2001 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lunar & Planetary Inst, Houston, TX 77058 USA. Univ Wisconsin, Oshkosh, WI 54901 USA. SW Res Inst, Boulder, CO 80302 USA. RP Zahnle, K (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. EM kzahnle@mail.arc.nasa.gov RI Levison, Harold/C-6061-2013 OI Levison, Harold/0000-0001-5847-8099 NR 38 TC 64 Z9 64 U1 0 U2 7 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 2001 VL 153 IS 1 BP 111 EP 129 DI 10.1006/icar.2001.6668 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 481JE UT WOS:000171515500009 ER PT J AU Tokano, T Neubauer, FM Laube, M McKay, CP AF Tokano, T Neubauer, FM Laube, M McKay, CP TI Three-dimensional modeling of the tropospheric methane cycle on Titan SO ICARUS LA English DT Article DE Titan; atmospheres; structure; meteorology ID GENERAL-CIRCULATION; LOWER ATMOSPHERE; TEMPERATURE; OCEAN; REANALYSIS; NUCLEATION; AMMONIA; CLOUDS AB The tropospheric methane cycle on Titan including advection, diffusion, condensation, precipitation, evaporation, and surface source is simulated by a three-dimensional general circulation model. The model takes into account the different nucleation of methane in Titan's troposphere, and assumes condensation whenever the saturation ratio (relative humidity) exceeds a critical value of either 100 or 150%. The simulation with the latter critical saturation is shown to be more compatible with the Voyager data. The meridional circulation accounts for a seasonal methane transport from the winter to summer hemisphere in the mid-troposphere, causing a higher supersaturation in late summer and early autumn. Condensation preferentially occurs in this season at 15 km altitude at low latitudes. The occasional character may be explained by the high critical saturation ratio, which cannot be often exceeded. Falling rain evaporates during the descent, so no rain arrives at the surface. The hydrological cycle of methane on Titan takes place mostly within the atmosphere. The latitudinal methane distribution near the surface cannot be reproduced by transport, evaporation, condensation, and combinations of them, indicating some undetermined surface processes affecting the methane distribution. The zonal and meridional circulation is sensitive to the methane distribution. (C) 2001 Academic Press. C1 Univ Cologne, Inst Geophys & Meteorol, D-50923 Cologne, Germany. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Tokano, T (reprint author), Univ Cologne, Inst Geophys & Meteorol, Albertus Magnus Pl, D-50923 Cologne, Germany. NR 43 TC 62 Z9 62 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 SEP PY 2001 VL 153 IS 1 BP 130 EP 147 DI 10.1006/icar.2001.6659 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 481JE UT WOS:000171515500010 ER PT J AU Anderson, JD Jacobson, RA McElrath, TP Moore, WB Schubert, G Thomas, PC AF Anderson, JD Jacobson, RA McElrath, TP Moore, WB Schubert, G Thomas, PC TI Shape, mean radius, gravity field, and interior structure of Callisto SO ICARUS LA English DT Article ID INTERNAL STRUCTURE; GALILEAN SATELLITES; GANYMEDE; EUROPA; MODELS AB Radio Doppler data generated by the Deep Space Network (DSN) from five encounters of the Galileo spacecraft with Callisto, Jupiter's outermost Galilean satellite, have been used to determine the mass (GM) and unnormalized quadrupole gravity coefficients in Callisto's external gravitational field. The results are GM (7179.292 +/- 0.009) km(3) s(-2), J(2) = (32.7 +/- 0.8) x 10(-6), C-22 = (10.2 +/- 0.3) x 10(-6), S-22 =(-1.1 +/- 10.3) x 10(-6), C-21 = (0.0 +/- 0.3) x 10(-6), and S-21 = (0.0 +/- 1.6) x 10(-6). Also, four spacecraft images of Callisto have been used to determine its mean radius. The result is R = (2410.3 +/- 1.5) km, with no detectable deviation from sphericity. Derived parameters are Callisto's mean density of (1834.4 +/- 3.4) kg m(-3) and axial moment of inertia C/MR2 = 0.3549 +/- 0.0042. While the mean density indicates that Callisto is a mixture of rock and ice, the moment of inertia is too small for a homogeneous mixture. Accordingly, we present a suite of possible two- and three-layer interior models that satisfy the given constraints for radius, density, and moment of inertia. While not unique, these models show that Callisto cannot be entirely differentiated, and that there must exist a region of mixed ice and rock-metal, possibly extending to the center of the satellite. (C) 2001 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. RP Anderson, JD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 238-420, Pasadena, CA 91109 USA. NR 26 TC 87 Z9 92 U1 2 U2 8 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 2001 VL 153 IS 1 BP 157 EP 161 DI 10.1006/icar.2001.6664 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 481JE UT WOS:000171515500012 ER PT J AU Dello Russo, N Mumma, MJ DiSanti, MA Magee-Sauer, K Novak, R AF Dello Russo, N Mumma, MJ DiSanti, MA Magee-Sauer, K Novak, R TI Ethane production and release in Comet C/1995 O1 Hale-Bopp SO ICARUS LA English DT Article DE comets; Hale-Bopp; composition; infrared observations; ethane ID MU-M; INFRARED-SPECTROSCOPY; HYDROGEN-CYANIDE; EMISSION FEATURE; CARBON-MONOXIDE; HALLEYS-COMET; B2 HYAKUTAKE; SPECTRUM; METHANOL; WATER AB Ethane (C2H6) was detected in Comet C/1995 O1 Hale-Bopp on 13 dates between UT 1996 September 20.3 (R-h = 3.01 AU preperihelion) and 1997 September 25.7 (R-h = 2.83 AU post-perihelion) using high-resolution infrared spectroscopy. Production rates and rotational temperatures were measured, and the derived heliocentric dependence for ethane production was Q = (5.52 +/- 0.20) x 10(28) [R-h((-2.43 +/-0.13))] molecules s(-1). The spatial distribution of C2H6 molecules in the coma was consistent with all ethane being released directly from the nucleus, although the possibility that a small fraction was released as a distributed source cannot be excluded. When our derived production rates for ethane, water, and acetylene (C2H2) are compared, we obtain an average relative abundance of C2H6/H2O = (6.23 +/- 0.42) x 10(-3), and C2H6/C2H2 = 2.4 +/- 0.7. The high ethane abundance relative to acetylene in Hale-Bopp suggests its ices were altered by radiation processing and/or hydrogen-atom addition reactions on the surfaces of ice-mantled grains in the natal cloud. These results are not consistent with ices in Hale-Bopp originating in a thermally or chemically equilibrated region of the solar nebula. (C) 2001 Academic Press. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Rowan Univ, Dept Chem & Phys, Glassboro, NJ 08028 USA. Iona Coll, Dept Phys, New Rochelle, NY 10801 USA. RP Dello Russo, N (reprint author), Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RI mumma, michael/I-2764-2013; Magee-Sauer, Karen/K-6061-2015; Dello Russo, Neil/G-2727-2015 OI Magee-Sauer, Karen/0000-0002-4979-9875; Dello Russo, Neil/0000-0002-8379-7304 NR 62 TC 38 Z9 38 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 SEP PY 2001 VL 153 IS 1 BP 162 EP 179 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 481JE UT WOS:000171515500013 ER PT J AU D'Abramo, G Harris, AW Boattini, A Werner, SC Harris, AW Valsecchi, GB AF D'Abramo, G Harris, AW Boattini, A Werner, SC Harris, AW Valsecchi, GB TI A simple probabilistic model to estimate the population of near-Earth asteroids SO ICARUS LA English DT Article DE asteroids; population estimate AB A simple probabilistic model for estimating the population of near-Earth asteroids (NEAs) by comparing the rate of redetections of previously known asteroids of a given size with new detections during a test interval of time is described. We apply this method to the whole sample of NEA observations (discovery observations and observations from apparitions of previously known asteroids) made by the Lincoln near-Earth Asteroids Research Project within the period Jan. 1, 1999-Dec. 31, 2000 and published by the Minor Planet Center. The numbers of discoveries and redetections are sufficient to estimate the total population in the absolute magnitude range 13.5 < H less than or equal to 20.0. By this method we obtain an estimate of the number of NEAs of H less than or equal to 18.0 (diameter greater than or equal to 1 km) of 855 +/- 101. We note, however, that the expected biases of this method all work in the direction of underestimating the true population; thus our estimate is consistent with other recent estimates, for example, W. F. Bottke et al (2000, Science 288,2190-2194), who obtain 910 +/- 110. 2001 Academic Press. C1 CNR, IAS Planetol, Area Ric, I-00133 Rome, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Osserv Astron Roma, I-00136 Rome, Italy. DLR, Ins Space Sensor Technol & Planetary Explorat, D-12489 Berlin, Germany. RP D'Abramo, G (reprint author), CNR, IAS Planetol, Area Ric, Via Fosso Cavaliere 100, I-00133 Rome, Italy. RI Werner, Stephanie/A-6438-2012; OI Werner, Stephanie/0000-0001-5704-0909; Valsecchi, Giovanni/0000-0002-2915-1465 NR 3 TC 13 Z9 13 U1 1 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 SEP PY 2001 VL 153 IS 1 BP 214 EP 217 DI 10.1006/icar.2001.6650 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 481JE UT WOS:000171515500017 ER PT J AU Basdogan, C Ho, CH Srinivasan, MA AF Basdogan, C Ho, CH Srinivasan, MA TI Virtual environments for medical training: Graphical and haptic simulation of laparoscopic common bile duct exploration SO IEEE-ASME TRANSACTIONS ON MECHATRONICS LA English DT Article DE collision detection; computer-based training; deformable objects; finite element modeling; haptic feedback; laparoscopic surgery; real-time interaction; surgical simulation; virtual reality ID SURGERY; SKILLS AB We have developed a computer-based training system to simulate laparoscopic procedures in virtual environments (VEs) for medical training. The major hardware components of our system include a computer monitor to display visual interactions between three-dimensional (3-D) virtual models of organs and instruments together with a pair of force feedback devices interfaced with laparoscopic instruments to simulate haptic interactions. In order to demonstrate the practical utility of the training system, we have chosen to simulate a surgical procedure that involves inserting a catheter into the cystic duct using a pair of laparoscopic forceps. This procedure is performed during laparoscopic cholecystectomy (gallbladder removal) to search for gallstones in the common bile duct. Using the proposed system, the user can be trained to grasp and insert a flexible and freely moving catheter into the deformable cystic duct in virtual environments. As the catheter and the duct are manipulated via simulated laparoscopic. forceps, the associated deformations are displayed on the computer screen and the reaction forces are fed back to the user through the force feedback devices. A hybrid modeling approach was developed to simulate the real-time visual and haptic interactions that take place between the forceps and the catheter, as well as the duct; and between the catheter and the duct. This approach combines a finite element model and a particle model to simulate the flexible dynamics of the duct and the catheter, respectively. To simulate the deformable dynamics of the duct in real-time using finite element procedures, a modal analysis approach was implemented such that only the most significant vibration modes of the duct were selected to compute the deformations and the interaction forces. The catheter was modeled using a set of virtual particles that were uniformly distributed along the centerline of catheter and connected to each other via linear and torsional springs and damping elements. In order to convey to the user a sense of touching and manipulating deformable objects through force feedback devices, two haptic. interaction techniques that we have developed before were employed. The interactions between the particles of the catheter and the duct were simulated using a point-based haptic interaction technique. The interactions between the forceps and the duct as well as the catheter were simulated using the ray-based haptic. interaction technique where the laparoscopic. forceps were modeled as connected line segments. C1 MIT, Elect Res Lab, Lab Human & Machine Hapt, Cambridge, MA 02139 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP MIT, Elect Res Lab, Lab Human & Machine Hapt, Cambridge, MA 02139 USA. EM Cagatay.Basdogan@jpl.nasa.gov; chihhao@mit.edu; srini@mit.edu RI Basdogan, Cagatay /H-5192-2011 OI Basdogan, Cagatay /0000-0002-6382-7334 NR 42 TC 122 Z9 123 U1 7 U2 20 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1083-4435 EI 1941-014X J9 IEEE-ASME T MECH JI IEEE-ASME Trans. Mechatron. PD SEP PY 2001 VL 6 IS 3 BP 269 EP 285 DI 10.1109/3516.951365 PG 17 WC Automation & Control Systems; Engineering, Manufacturing; Engineering, Electrical & Electronic; Engineering, Mechanical SC Automation & Control Systems; Engineering GA 474TX UT WOS:000171123900008 ER PT J AU Lopes, LS Connell, JH Dario, P Murphy, R Bonasso, P Nebel, B Nilsson, N Brooks, RA AF Lopes, LS Connell, JH Dario, P Murphy, R Bonasso, P Nebel, B Nilsson, N Brooks, RA TI Sentience in robots: Applications and challenges SO IEEE INTELLIGENT SYSTEMS LA English DT Editorial Material C1 Scuola Super Sant Anna, Pisa, 33620, Italy. Univ S Florida, Lyndon B Johnson Space Ctr, Tampa, FL 77058 USA. NASA, Sch Engn, I-56100 Houston, TX USA. Univ Pisa, Pisa, Italy. RI Seabra Lopes, Luis/A-6012-2012 NR 3 TC 5 Z9 7 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1541-1672 EI 1941-1294 J9 IEEE INTELL SYST JI IEEE Intell. Syst. PD SEP-OCT PY 2001 VL 16 IS 5 BP 66 EP 69 DI 10.1109/5254.956083 PG 4 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 493WC UT WOS:000172245600013 ER PT J AU Knight, R Rabideau, G Chien, S Engelhardt, B Sherwood, R AF Knight, R Rabideau, G Chien, S Engelhardt, B Sherwood, R TI Casper: Space exploration through continuous planning SO IEEE INTELLIGENT SYSTEMS LA English DT Editorial Material C1 CALTECH, Jet Prop Lab, Dept Comp Sci, Pasadena, CA 91109 USA. RP Knight, R (reprint author), CALTECH, Jet Prop Lab, Dept Comp Sci, M-S 126-347,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 20 Z9 25 U1 0 U2 3 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1094-7167 J9 IEEE INTELL SYST JI IEEE Intell. Syst. PD SEP-OCT PY 2001 VL 16 IS 5 BP 70 EP 75 DI 10.1109/5254.956084 PG 6 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 493WC UT WOS:000172245600014 ER PT J AU Walsh, BM Barnes, NP Hutcheson, RL Equall, RW AF Walsh, BM Barnes, NP Hutcheson, RL Equall, RW TI Compositionally tuned 0.94-mu m lasers: A comparative laser material study and demonstration of 100-mJ Q-switched lasing at 0.946 and 0.9441 mu m SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article DE 0.94-mu m lasers; amplified spontaneous emission; compositional tuning; cross section; neodymium lasers; solid state lasers; Voigt lineshape; water vapor DIAL AB A new and innovative composite laser material Nd: YAG(x)YSAG((1-x)) has been developed with several objectives in mind; tunability, efficiency, and minimization of the deleterious effects of amplified spontaneous emission (ASE) in Q-switched operation. Wavelength tuning to the requisite wavelength 0.9441 mum was achieved by using the technique referred to as compositional tuning; that is, using nonstoichiometric laser materials to shift the wavelength for precise tuning. Laser efficiency was achieved by studying the physics of 0.94-mum transitions in nonstoichiometric materials; i.e., by examing the effects of the host on the linewidth and cross section of of 0.94 mum neodymium (Nd) transitions. ASE was minimized by choosing materials with a small ratio of 1.06- to 0.94-mum peak cross sections. A comparative study of six different Nd-doped mixed garnet laser material systems was performed to meet the objectives above. Within these six material systems, over 20 laser materials were spectroscopically analyzed. The optimal laser material was found to be Nd:YAG(x)YSAG((1-x)), which has been demonstrated to lase at the preselected wavelength of 0.9441 mum, an important wavelength for remote sensing of water vapor. Operating this laser on the F-4(3/2)--> I-4(9/2) transition in Nd:YAG((0.18))YSAG(0.82) at 0.9441 mum, has produced for the first time over 100 mJ in the Q-switched mode. This represents one of the few lasers that have been designed to operate at a specific, user-preselected wavelength. C1 Boston Coll, Chestnut Hill, MA 02167 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Sci Mat, Bozeman, MT 59715 USA. RP Walsh, BM (reprint author), Boston Coll, Chestnut Hill, MA 02167 USA. NR 7 TC 19 Z9 20 U1 2 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD SEP PY 2001 VL 37 IS 9 BP 1203 EP 1209 DI 10.1109/3.945326 PG 7 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA 468HW UT WOS:000170752900013 ER PT J AU Siegel, PH Divsalar, D Eleftheriou, E Hagenauer, J Rowitch, D Tranter, WH AF Siegel, PH Divsalar, D Eleftheriou, E Hagenauer, J Rowitch, D Tranter, WH TI The turbo principle: From theory to practice II SO IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS LA English DT Editorial Material C1 Univ Calif San Diego, La Jolla, CA 92093 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. IBM Res, CH-8803 Ruschlikon, Switzerland. Tech Univ Munich, D-80290 Munich, Germany. Qualcomm Inc, San Diego, CA 92121 USA. RP Siegel, PH (reprint author), Univ Calif San Diego, La Jolla, CA 92093 USA. NR 0 TC 9 Z9 9 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0733-8716 J9 IEEE J SEL AREA COMM JI IEEE J. Sel. Areas Commun. PD SEP PY 2001 VL 19 IS 9 BP 1657 EP 1661 DI 10.1109/JSAC.2001.947030 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 475WU UT WOS:000171193300001 ER PT J AU Pogorzelski, RJ AF Pogorzelski, RJ TI A two-dimensional coupled oscillator array (vol 10, pg 478, 2000) SO IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS LA English DT Correction 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 2 TC 0 Z9 0 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 1531-1309 J9 IEEE MICROW WIREL CO JI IEEE Microw. Wirel. Compon. Lett. PD SEP PY 2001 VL 11 IS 9 BP 391 EP 391 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA 473PG UT WOS:000171054100011 ER PT J AU Bejczy, AK AF Bejczy, AK TI Professor Adam Morecki (5 September 1929-20 May 2001) - In memory of a pioneer in robotics SO IEEE ROBOTICS & AUTOMATION MAGAZINE LA English DT Biographical-Item C1 CALTECH, JPL, Pasadena, CA 91125 USA. RP Bejczy, AK (reprint author), CALTECH, JPL, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 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 1070-9932 J9 IEEE ROBOT AUTOM MAG JI IEEE Robot. Autom. Mag. PD SEP PY 2001 VL 8 IS 3 BP 70 EP 71 PG 2 WC Automation & Control Systems; Robotics SC Automation & Control Systems; Robotics GA 476CW UT WOS:000171209500010 ER PT J AU Pinzon, JE Pierce, JF Tucker, CJ Brown, ME AF Pinzon, JE Pierce, JF Tucker, CJ Brown, ME TI Evaluating coherence of natural images by smoothness membership in Besov spaces SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE remote sensing; smoothness of image; wavelets ID AVHRR DATA SETS; DIGITAL IMAGES; COMPRESSION; LAND; DECOMPOSITION; ALGORITHMS; VEGETATION; VARIOGRAMS; SIGNAL; DESERT AB Smoothness membership in Besov spaces B-q(alpha) (I) is used to compare the spatial coherence of satellite images. Smoothness is given by a complexity index computed as the rate of decay of the approximation error epsilon (M) when the image is approximated by its M-largest quantized wavelet coefficient. The technique was applied to a set of nine normalized difference vegetation index (NDVI) time series data as a quantitative quality measure of spatial coherence. The NDVI data set comprises different compositing and atmospheric correction techniques. The estimates of the complexity index give a quantitative measure of the performance of these techniques that agrees well with visual evaluation and with the physics of the image collection process. We demonstrate the maximum value NDVI composites with Rayleigh, ozone, and water vapor correction consistently provide the highest spatial coherence among the compositing and atmospheric correction techniques evaluated. We also show the complexity index is regionally dependent and is higher in dry periods than in wet periods where residual cloud interference is more likely to appear. C1 NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. USN Acad, Dept Math, Annapolis, MD 21402 USA. NASA, Goddard Space Flight Ctr, Biospher Sci, Greenbelt, MD 20771 USA. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RP Pinzon, JE (reprint author), NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. EM pinzon@negev.gsfc.nasa.gov RI Brown, Molly/E-2724-2010; Brown, Molly/M-5146-2013 OI Brown, Molly/0000-0001-7384-3314; Brown, Molly/0000-0001-7384-3314 NR 37 TC 5 Z9 5 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 EI 1558-0644 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 2001 VL 39 IS 9 BP 1879 EP 1889 DI 10.1109/36.951078 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 473ZV UT WOS:000171080600006 ER PT J AU Durden, SL Im, E Li, FK Girard, R Pak, KS AF Durden, SL Im, E Li, FK Girard, R Pak, KS TI Surface clutter due to antenna sidelobes for spaceborne atmospheric radar SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE clouds; clutter; precipitation; radar; sidelobes ID TRMM AB A spaceborne radar for atmospheric observation must be able to detect atmospheric backscatter in the presence of clutter from the surface, due to antenna sidelobes. Such clutter can come from the same pulse as that observing the atmosphere if the radar antenna is pointed off-nadir. However, pulses both prior and subsequent to the pulse observing the atmosphere can also contribute to clutter, and surface clutter can be a problem even for nadir-looking radars. Here, the problem is analyzed by deriving a method for computing clutter which includes effects of all contributing transmit pulses, Doppler shifting, finite receiver bandwidth, and curved earth's surface. The results are applied to analysis of existing radars and design of future radar systems. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Canadian Space Agcy, St Hubert, PQ, Canada. RP Durden, SL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 8 Z9 9 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 2001 VL 39 IS 9 BP 1916 EP 1921 DI 10.1109/36.951082 PG 6 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 473ZV UT WOS:000171080600010 ER PT J AU Ni-Meister, W Jupp, DLB Dubayah, R AF Ni-Meister, W Jupp, DLB Dubayah, R TI Modeling lidar waveforms in heterogeneous and discrete canopies SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE geometric optical and radiative transfer (GORT); model; heterogeneous plant canopies; lidar waveforms ID DISCONTINUOUS PLANT CANOPIES; BOREAL CONIFER FORESTS; BIDIRECTIONAL REFLECTANCE; RADIATION; ALBEDO; AREA AB This study explores the relationship between laser waveforms and canopy structure parameters and the effects Of the spatial arrangement of canopy structure on this relationship through a geometric optical model. Studying laser waveforms for such plant canopies is needed for the advanced retrieval of three-dimensional (3-D) canopy structure parameters from the vegetation canopy lidar (VCL) mission. For discontinuous plant canopies, a hybrid geometric optical and radiative transfer (GORT) model describing the effects of 3-D canopy structure parameters of discrete canopies on the radiation environment has been modified for use with lidar. The GORT model is first used to describe the canopy lidar waveforms as a function of canopy structure parameters and then validated using scanning lidar imager of canopies by echo recovery (SLICER) data collected in conifer forests in central Canada during the boreal ecosystem-atmosphere study (BOREAS). Model simulations show that the clumping in natural vegetation, such as leaves clustering into tree crowns causes larger gap probability and smaller waveforms for discontinuous plant canopies than for horizontally homogeneous plant canopies. Ignoring the clumping effect can result in significantly lower values for the estimated foliage amount in the profile and in turn lower estimated biomass. Because of clumping, only the gap probability and apparent vertical projected foliage profile can be directly retrieved from the canopy lidar data. The retrieval is sensitive to the ratio of the volume backscattering coefficients of the vegetation and background, and this ratio depends on canopy architecture as well as foliage spectral characteristics. Extensions of the GORT model from single-layered canopies to include multilayered ones are also explored. C1 NASA, Goddard Space Flight Ctr, Goddard Earth Sci & Technol Ctr, Greenbelt, MD 20771 USA. CSIRO, EOC, Canberra, ACT 2601, Australia. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RP Ni-Meister, W (reprint author), NASA, Goddard Space Flight Ctr, Goddard Earth Sci & Technol Ctr, Greenbelt, MD 20771 USA. EM wenge@land-gsfc.nasa; david.jupp@eoc.csiro.au; rdubayah@geog.umd.edu RI Beckley, Matthew/D-4547-2013; OI Jupp, David/0000-0002-9467-1344 NR 34 TC 119 Z9 125 U1 3 U2 33 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 2001 VL 39 IS 9 BP 1943 EP 1958 DI 10.1109/36.951085 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 473ZV UT WOS:000171080600013 ER PT J AU Rubaai, A Kotaru, R Kankam, MD AF Rubaai, A Kotaru, R Kankam, MD TI Online training of parallel neural network estimators for control of induction motors SO IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS LA English DT Article; Proceedings Paper CT Annual Meeting of the Industry-Applications-Society CY OCT 03-07, 1999 CL PHOENIX, ARIZONA SP Ind Applicat Soc DE artificial neural networks; control of stator currents; induction motor; online learning; parallel processing ID IDENTIFICATION; ALGORITHM; OBSERVER AB This paper presents adaptive parallel control architecture, using an artificial neural network (ANN) which is trained while the controller is operating online. The proposed control structure incorporates five-multilayer feedforward ANNs, which are online trained using the Marquardt-Levenberg least-squares learning algorithm. The five networks are used exclusively for system estimation. The estimation mechanism uses online training to learn the unknown model dynamics and estimate the rotor fluxes of an inverter-fed induction motor. Subsequently, the estimated stator currents are fed into an adaptive controller to track the desired stator current trajectories. The adaptive controller is constructed as a feedback signal (a nonlinear control law), depending on estimated stator currents supplied by the neural estimators and the desired reference trajectories to be tracked by the output. The control of the direct and quadrature components of the stator current successfully tracked a wide variety of reference trajectories after relatively short online training periods. C1 Howard Univ, Dept Elect Engn, Washington, DC 20059 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Rubaai, A (reprint author), Howard Univ, Dept Elect Engn, Washington, DC 20059 USA. NR 15 TC 19 Z9 22 U1 0 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0093-9994 J9 IEEE T IND APPL JI IEEE Trans. Ind. Appl. PD SEP-OCT PY 2001 VL 37 IS 5 BP 1512 EP 1521 DI 10.1109/28.952529 PG 10 WC Engineering, Multidisciplinary; Engineering, Electrical & Electronic SC Engineering GA 476FT UT WOS:000171216100035 ER PT J AU Leroy, B Medioni, G Johnson, E Matthies, L AF Leroy, B Medioni, G Johnson, E Matthies, L TI Crater detection for autonomous landing on asteroids SO IMAGE AND VISION COMPUTING LA English DT Article; Proceedings Paper CT Workshop on Perception of Mobile Agents held in conjunction with the IEEE Conference on Computer Vision and Pattern Recognition CY 1999 CL FT COLLINS, COLORADO SP IEEE Comp Soc DE segmentation; feature extraction; perceptual grouping; autonomous spacecraft ID 3D DATA; SURFACE; INFERENCE; SPARSE; MODEL AB We describe a visual positioning system for use by a spacecraft to choose a landing site, while orbiting an asteroid. The spacecraft pose is refined using landmarks, such as craters, observed by a visual sensor. The craters, which have an elliptical shape, are detected using a multiscale method based on voting, and tensors as a representation. We propose a new robust method to infer curvature estimation from noisy sparse data. This method is applied on edge images in order to obtain the oriented normals of the edge curves. Using this information, a dense saliency map corresponding to the position and shape of the craters is computed. The detected craters in the image are matched with the craters projected from a 3D model, and the best transformation between these two sets is obtained. This system has been tested with both real images of Phobos and a synthetic model. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ So Calif, Inst Robot & Intelligent Syst, Los Angeles, CA 90089 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Leroy, B (reprint author), Univ So Calif, Inst Robot & Intelligent Syst, Univ Pk Campus, Los Angeles, CA 90089 USA. NR 10 TC 40 Z9 49 U1 1 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0262-8856 J9 IMAGE VISION COMPUT JI Image Vis. Comput. PD SEP 1 PY 2001 VL 19 IS 11 BP 787 EP 792 DI 10.1016/S0262-8856(00)00111-6 PG 6 WC Computer Science, Artificial Intelligence; Computer Science, Software Engineering; Computer Science, Theory & Methods; Engineering, Electrical & Electronic; Optics SC Computer Science; Engineering; Optics GA 476ZG UT WOS:000171258200009 ER PT J AU Haferl, S Butty, V Poulikakos, D Giannakouros, J Boomsma, K Megaridis, CM Nayagam, V AF Haferl, S Butty, V Poulikakos, D Giannakouros, J Boomsma, K Megaridis, CM Nayagam, V TI Freezing dynamics of molten solder droplets impacting onto flat substrates in reduced gravity SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article ID METAL SOLIDIFICATION PROCESS; 1ST STAGES; DEPOSITION; RESISTANCE; SURFACE AB The axisymmetric impingement of solidifying molten solder droplets onto smooth metallic substrates in a reduced gravity environment is investigated numerically to provide basic information on the heat and fluid flow phenomena and determine the governing parameters of the process. The numerical predictions are also tested against experimental data. Millimeter-sized droplet impact events in reduced gravity are employed for scale up modeling of the impingement of picoliter size droplets of molten eutectic 63%Sn-37%Pb solder used in electronic chip packaging. The present article reports on both numerical (the main focus of the paper) as well as experimental work (for the purpose of verification). To this end, the employed numerical model considers the axisymmetric impact and subsequent solidification of an initially spherical, molten solder droplet on a flat, smooth, metallic substrate. The laminar Navier-Stokes equations, combined with the energy transport equations are solved simultaneously in the liquid region (melt) using a Lagrangian approach. In the solid (substrate and solidified droplet material) the heat conduction equation is solved. A time and space averaged (but phase dependent) model of the thermal contact resistance between the impacting droplet and the substrate is also incorporated in the formulation. The numerical model is solved using a Galerkin finite element method, where a deforming, adaptive triangular-element mesh is employed to accurately simulate the large-domain deformations caused by the spreading and recoiling of the impinging droplet fluid. The experimental work has been conducted in reduced gravity in the range 2 x 10(-4) to 5 x 10(-4) g with technically relevant impact velocities of similar to 0.2 m/s, in order to provide validation of the numerical predictions. These impact conditions correspond to Re = O(100), We = O(1), and Fr = O(10,000), Ca = O(0.001). Presentation of the numerical results in terms of the Froude and the Ohnesorge numbers aids their interpretation. Among the results that stand out is the formation of a large number of frozen ripples on the droplet surface as a result of the simultaneous manifestation of rapid fluid oscillations and solidification. Furthermore, a non-intuitive behavior of the solidification times is reported. Specifically, the dependence of the solidification time on the Froude number is not monotonic, but features a minimum for each distinct value of Ohnesorge number considered in this study. Despite the complexity of the phenomena, the numerical model captures well the main features of the experimental results. In addition, the model offers key insights on the influence of the Ohnesorge and Froude numbers on the dynamics of the solidification process. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 ETH Ctr, Swiss Fed Inst Technol, Inst Energy Technol, Lab Thermodynam Emerging Technol, CH-8092 Zurich, Switzerland. Univ Illinois, Dept Mech Engn, Chicago, IL 60607 USA. NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Poulikakos, D (reprint author), ETH Ctr, Swiss Fed Inst Technol, Inst Energy Technol, Lab Thermodynam Emerging Technol, CH-8092 Zurich, Switzerland. EM poulikakos@ltnt.iet.mavt.ethz.ch RI poulikakos, dimos/O-2853-2014; OI poulikakos, dimos/0000-0001-5733-6478; Megaridis, Constantine/0000-0002-6339-6933 NR 24 TC 16 Z9 17 U1 1 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0017-9310 J9 INT J HEAT MASS TRAN JI Int. J. Heat Mass Transf. PD SEP PY 2001 VL 44 IS 18 BP 3513 EP 3528 DI 10.1016/S0017-9310(01)00015-1 PG 16 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA 454YK UT WOS:000169999200010 ER PT J AU Johnston, WE AF Johnston, WE TI Using computing and data grids for large-scale science and engineering SO INTERNATIONAL JOURNAL OF HIGH PERFORMANCE COMPUTING APPLICATIONS LA English DT Article; Proceedings Paper CT Workshop on Clusters and Computational Grids for Scientific Computing CY SEP 25-27, 2000 CL CHATEAU FAVERGES, FRANCE SP INRIA, Natl Sci Fdn, Myricom, Microsoft Res, Compaq, Turbo Linux, Univ Tennessee, Univ Claude Bernard Lyon 1 AB The term Grid is used to refer to a software system that provides uniform and location-independent access to geographically and organizationally dispersed, heterogeneous resources that are persistent and supported. These emerging data and computing Grids promise to provide a highly capable and scalable environment for addressing large-scale science problems. The author describes the requirements for science Grids, the resulting services and architecture of NASA's Information Power Grid and the Department of Energy's Science Grid, and some of the scaling issues that have come up in their implementation. C1 Lawrence Berkeley Natl Lab, Natl Energy Res Sci Comp Div, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, NAS, Moffett Field, CA 94035 USA. RP Johnston, WE (reprint author), Lawrence Berkeley Natl Lab, Natl Energy Res Sci Comp Div, 1 Cyclotron Rd,MS 50B-2239, Berkeley, CA 94720 USA. NR 12 TC 4 Z9 4 U1 0 U2 0 PU SAGE PUBLICATIONS INC PI THOUSAND OAKS PA 2455 TELLER RD, THOUSAND OAKS, CA 91320 USA SN 1094-3420 J9 INT J HIGH PERFORM C JI Int. J. High Perform. Comput. Appl. PD FAL PY 2001 VL 15 IS 3 BP 223 EP 242 DI 10.1177/109434200101500303 PG 20 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Computer Science, Theory & Methods SC Computer Science GA 474ZP UT WOS:000171137400003 ER PT J AU Sterling, T Katz, DS Bergman, L AF Sterling, T Katz, DS Bergman, L TI High performance computing systems for autonomous spaceborne missions SO INTERNATIONAL JOURNAL OF HIGH PERFORMANCE COMPUTING APPLICATIONS LA English DT Article; Proceedings Paper CT Workshop on Clusters and Computational Grids for Scientific Computing CY SEP 25-27, 2000 CL CHATEAU FAVERGES, FRANCE SP INRIA, Natl Sci Fdn, Myricom, Microsoft Res, Compaq, Turbo Linux, Univ Tennessee, Univ Claude Bernard Lyon 1 AB Future-generation space missions across the solar system to the planets, moons, asteroids, and comets may someday incorporate supercomputers both to expand the range of missions being conducted and to significantly reduce their cost. By performing science computation directly on the spacecraft itself, the amount of data required to be downlinked may be reduced by many orders of magnitude, thus greatly reducing the mass of the resources needed for communication while increasing the quality and quantity of the science achieved. By performing the mission planning in real time directly on the spacecraft, complex and highly responsive missions can be conducted out of range of direct human intervention, and the cost of mission management can be reduced. Through highly replicated computing structures, continued operation can be maintained in the presence of faults by means of graceful degradation. Two classes of systems, reflecting very different strategies of computer system architecture, are actively being pursued by the NASA Jet Propulsion Laboratory (JPL) to take advantage of the opportunity of embedded high performance computing on spacecraft for deep-space missions. Commodity off-the-shelf (COTS) clusters may permit the direct application of commercial computing hardware in loosely coupled ensembles to benefit from the enormous investment of industry in mass-market components. New processor-in-memory (PIM) architectures combine multiple nodes on a single chip of processor-memory pairs exposing the full memory bandwidth. This paper examines the driving issues motivating the use of supercomputing for future deep-space missions and describes two active research projects at NASA JPL that are pursuing both the COTS and PIM strategies for next-generation spaceborne computing. C1 CALTECH, Ctr Adv Comp Res, NASA Jet Prop Lab, Pasadena, CA 91125 USA. RP Sterling, T (reprint author), CALTECH, Ctr Adv Comp Res, NASA Jet Prop Lab, MC 158-79,1200 E Calif Blvd, Pasadena, CA 91125 USA. OI Katz, Daniel S./0000-0001-5934-7525 NR 16 TC 2 Z9 2 U1 0 U2 1 PU SAGE PUBLICATIONS INC PI THOUSAND OAKS PA 2455 TELLER RD, THOUSAND OAKS, CA 91320 USA SN 1094-3420 J9 INT J HIGH PERFORM C JI Int. J. High Perform. Comput. Appl. PD FAL PY 2001 VL 15 IS 3 BP 282 EP 296 DI 10.1177/109434200101500306 PG 15 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Computer Science, Theory & Methods SC Computer Science GA 474ZP UT WOS:000171137400006 ER PT J AU Pereira, JM Lerch, BA AF Pereira, JM Lerch, BA TI Effects of heat treatment on the ballistic impact properties of Inconel 718 for jet engine fan containment applications SO INTERNATIONAL JOURNAL OF IMPACT ENGINEERING LA English DT Article DE ballistic impact; adiabatic shear; Inconel 718; heat treatment ID ADIABATIC SHEAR BANDS; DUCTILE FRACTURE; TITANIUM; BEHAVIOR; METALS; ALLOY; PLATE; MODE AB The effects of heat treating Inconel 718 on the ballistic impact response and failure mechanisms were studied. Two different annealing conditions and an aged condition were considered. Large differences in the static properties were found between the annealed and the aged material, with the annealed condition having lower strength and hardness and greater elongation than the aged. High strain rate tests show similar results. Correspondingly large differences were found in the velocity required to penetrate material in the two conditions in impact tests involving 12.5 mm diameter, 25.4 mm long cylindrical Ti-6-4 projectiles impacting flat plates at velocities in the range of 150-300m/s. The annealed material was able to absorb over 25 percent more energy than the aged. This is contrary to results observed for ballistic impact response for higher velocity impacts typically encountered in military applications where it has been shown that there exists a correlation between target hardness and ballistic impact strength. Metallographic examination of impacted plates showed strong indication of failure due to adiabatic shear. In both materials localized bands of large shear deformation were apparent, and microhardness measurements indicated an increase in hardness in these bands compared to the surrounding material. These bands were more localized in the aged material than in the annealed material. In addition, the annealed material underwent significantly greater overall deformation before failure. The results indicate that lower elongation and reduced strain hardening behavior lead to a transition from shear to adiabatic shear failure, while high elongation and better strain hardening capabilities reduce the tendency for shear to localize and result in an unstable adiabatic shear failure. This supports empirical containment design methods that relate containment thickness to the static toughness. Published by Elsevier Science Ltd. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Pereira, JM (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. EM j.m.pereira@grc.nasa.gov NR 35 TC 49 Z9 52 U1 1 U2 13 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0734-743X J9 INT J IMPACT ENG JI Int. J. Impact Eng. PD SEP PY 2001 VL 25 IS 8 BP 715 EP 733 DI 10.1016/S0734-743X(01)00018-5 PG 19 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 461UT UT WOS:000170382400001 ER PT J AU Machin, RA Iacomini, CS Cerimele, CJ Stein, JM AF Machin, RA Iacomini, CS Cerimele, CJ Stein, JM TI Flight testing the parachute system for the space station crew return vehicle SO JOURNAL OF AIRCRAFT LA English DT Article AB NASA has developed and tested a large parafoil for use in landing the International Space Station crew return vehicle. A series of tests using low-velocity airdrop pallets and prototype lifting bodies flights has demonstrated that the parafoil recovery system is a viable option for safely landing a crewed vehicle. The aerodynamic characteristics of the parafoil system have been determined through a series of flight-test maneuvers and subsequently successfully modeled using an eight-degree-of-freedom simulation program. An introduction to the requirements for the crew return vehicle, a description of the parafoil system, an overview of the testing performed including several significant findings, a description of the techniques used to assess the aerodynamic performance of the parafoil system, and a discussion of the simulation of the parafoil system are presented. C1 NASA, Lyndon B Johnson Space Ctr, Aerosci & Flight Mech Div, Houston, TX 77058 USA. RP Machin, RA (reprint author), NASA, Lyndon B Johnson Space Ctr, Aerosci & Flight Mech Div, Mail Code EG5, Houston, TX 77058 USA. NR 18 TC 3 Z9 5 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 2001 VL 38 IS 5 BP 786 EP 799 DI 10.2514/2.2854 PG 14 WC Engineering, Aerospace SC Engineering GA 481NQ UT WOS:000171526200002 ER PT J AU Rumsey, CL Gatski, TB AF Rumsey, CL Gatski, TB TI Recent turbulence model advances applied to multielement airfoil computations SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 18th Applied Aerodynamics Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut ID HIGH-LIFT FLOWS; EQUATIONS AB A one-equation linear turbulence model and a two-equation nonlinear explicit algebraic stress model (EASM) are applied to the flow over a multielement airfoil. The effect of the K-epsilon and K-w forms of the two-equation model are explored, and the K-epsilon form is shown to be deficient in the wall-bounded regions of adverse pressure gradient flows. A new K-w form of EASM is introduced. Nonlinear terms present in EASM are shown to improve predictions of turbulent shear stress behind the trailing edge of the main element and near the midflap. Curvature corrections are applied to both the one- and two-equation turbulence models and yield only relatively small local differences in the flap region, where the flowfield undergoes the greatest curvature. Predictions of maximum lift are essentially unaffected by the turbulence model variations studied. C1 NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. RP Rumsey, CL (reprint author), NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Mail Stop 128, Hampton, VA 23681 USA. NR 31 TC 28 Z9 30 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 SEP-OCT PY 2001 VL 38 IS 5 BP 904 EP 910 DI 10.2514/2.2850 PG 7 WC Engineering, Aerospace SC Engineering GA 481NQ UT WOS:000171526200016 ER PT J AU Robins, RE Delisi, DP Greene, GC AF Robins, RE Delisi, DP Greene, GC TI Algorithm for prediction of trailing vortex evolution SO JOURNAL OF AIRCRAFT LA English DT Article ID STRATIFIED FLUID; MODEL; ATMOSPHERE; DECAY AB We describe an algorithm that predicts the trajectories and circulation decay of aircraft trailing vortices. We first present the methodology used by the algorithm to simulate trailing vortex behavior, including 1) the descent of the vortices through a realistic atmosphere defined by crosswind, turbulence, and stratification profiles and 2) the interaction of the vortices with the ground. Examples are presented to demonstrate the algorithm's capability. We then describe a database approach for quantifying comparisons between algorithm predictions and measurements of wake vortex transport and decay. The use of databases to optimize the constant factor k in the term governing the effect of turbulence on vortex decay is reported, with the result that k appears to depend on the intensity of ambient turbulence. Using selected groupings of cases from the database, we have determined that vortices not interacting with the ground decay about a factor of two faster in high-intensity ambient turbulence than in low-intensity ambient turbulence. We also show that the circulation decay for vortices in the ground effect appears to be independent of the ambient turbulence level. C1 NW Res Associates Inc, Bellevue, WA 98009 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Robins, RE (reprint author), NW Res Associates Inc, POB 3027, Bellevue, WA 98009 USA. NR 25 TC 10 Z9 10 U1 0 U2 3 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 SEP-OCT PY 2001 VL 38 IS 5 BP 911 EP 917 DI 10.2514/2.2851 PG 7 WC Engineering, Aerospace SC Engineering GA 481NQ UT WOS:000171526200017 ER PT J AU Milholen, WE AF Milholen, WE TI Efficient inverse aerodynamic design method for subsonic flows SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 38th Aerospace Sciences Meeting and Exhibit CY JAN 10-15, 2000 CL RENO, NEVADA SP Amer Inst Aeronatu & Astronaut AB Computational fluid dynamics based design methods are maturing to the point that they are beginning to be used in the aircraft design process. Many design methods, however, have demonstrated deficiencies in the leading-edge region of airfoil sections. The objective of the present research is to develop an efficient inverse design method that is valid in the leading-edge region. The new design method is a streamline curvature method, and a new technique is presented for modeling the variation of the streamline curvature normal to the surface. The new design method allows the surface coordinates to move normal to the surface and has been incorporated into the constrained direct iterative surface curvature design method. The accuracy and efficiency of the design method is demonstrated using both two-dimensional and three-dimensional design cases. C1 NASA, Langley Res Ctr, Configurat Aerodynam Branch, Hampton, VA 23681 USA. RP Milholen, WE (reprint author), NASA, Langley Res Ctr, Configurat Aerodynam Branch, Hampton, VA 23681 USA. NR 13 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 2001 VL 38 IS 5 BP 918 EP 923 DI 10.2514/2.2852 PG 6 WC Engineering, Aerospace SC Engineering GA 481NQ UT WOS:000171526200018 ER PT J AU Rouse, M Assadi, M AF Rouse, M Assadi, M TI Evaluation of scaling approach for stiffened composite flat panels loaded in compression SO JOURNAL OF AIRCRAFT LA English DT Article AB Results of an experimental study or the effects of geometric scaling on a graphite-epoxy flat stiffened-skin panel concept loaded in compression are presented. The scaled models were fabricated using an approach to laminate thickness scaling, referred to as the "ply-thickness method." The structural response and failure characteristics of full-, half-, and quarter-scale specimens fabricated with this scaling concept are discussed and compared. The scaled-up failure loads of the half- and quarter-scale models agree well with the failure load of the full-scale prototypes tested. The strength scale effects observed in the results were substantially smaller than those in earlier studies that employed other laminate scaling techniques. The experimental results indicate that failure initiated by crippling and delamination in the cap of the longitudinal stiffeners and skin-stiffener separation at the bond lines was followed by failure of the specimen skin. Nonlinear finite element analysis results correlate well with experimental results up to failure. C1 NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. Boeing Commercial Airplane Grp, Renton, WA 98055 USA. RP Rouse, M (reprint author), NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. NR 6 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 2001 VL 38 IS 5 BP 950 EP 955 DI 10.2514/2.2858 PG 6 WC Engineering, Aerospace SC Engineering GA 481NQ UT WOS:000171526200023 ER PT J AU Aboudi, J Pindera, MJ Arnold, SM AF Aboudi, J Pindera, MJ Arnold, SM TI Linear thermoelastic higher-order theory for periodic multiphase materials SO JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME LA English DT Article ID METAL-MATRIX COMPOSITES AB A new micromechanics model is presented which is capable of accurately estimating both the effective elastic constants of a periodic multiphase composite and the local stress and strain fields in the individual phases. The model is presently limited to materials characterized by constituent phases that are continuous in one direction, but arbitrarily distributed within the repeating unit cell which characterizes the material's periodic microstructure. The models analytical framework is based on the homogenization technique for periodic media, but the method of solution for the local displacement and stress fields borrows concepts previously employed by the authors in constructing the higher-order theory for functionally graded materials, in contrast with the standard finite element solution method typically used in conjunction with the homogenization technique. The present approach produces a closed-form macroscopic constitutive equation for a periodic multiphase material valid for both uniaxial and multiaxial loading which, in turn, can be incorporated into a structural analysis computer code. The models predictive accuracy is demonstrated by comparison with reported results of detailed finite element analyses of periodic composites as well as with the classical elasticity solution for an inclusion in an infinite matrix. C1 Tel Aviv Univ, IL-69978 Ramat Aviv, Israel. Univ Virginia, Dept Civil Engn, Charlottesville, VA 22903 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Aboudi, J (reprint author), Tel Aviv Univ, IL-69978 Ramat Aviv, Israel. NR 18 TC 71 Z9 71 U1 1 U2 9 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0021-8936 J9 J APPL MECH-T ASME JI J. Appl. Mech.-Trans. ASME PD SEP PY 2001 VL 68 IS 5 BP 697 EP 707 DI 10.1115/1.1381005 PG 11 WC Mechanics SC Mechanics GA 471MX UT WOS:000170934100001 ER PT J AU Madenci, E Barut, A Nemeth, MP AF Madenci, E Barut, A Nemeth, MP TI A complex potential-variational method for stress analysis of unsymmetric laminates with an elliptical cutout SO JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME LA English DT Article ID SHEAR; PLATE AB A combined complex potential-variational solution method is developed for the analysis of unsymmetrically laminated plates with finite planform geometry, subjected to arbitrary edge loads, and with an inclined elliptical cutout. This method uses complex potentials and their Laurent series expansions to reduce the potential energy of a plate to a contour integral that is evaluated numerically by the trapezoidal rule. A variational statement of equilibrium is applied to the potential energy to obtain a lineal, system of equations in terms of the unknown coefficients of the Laurent series, whose solutions yield the stress and displacement fields for a given problem. This approach represents a computationally efficient alternative to boundary collocation procedures that are typically used to solve problems based on complex potential theory. Comparisons are mode with corresponding results obtained from finite element analysis for a square unsymmetrically laminated plate with a central inclined elliptical cutout and subjected to biaxial tension. The results confirm the validity of the solution method. C1 Univ Arizona, Dept Aerosp & Mech Engn, Tucson, AZ 85721 USA. NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. RP Madenci, E (reprint author), Univ Arizona, Dept Aerosp & Mech Engn, Tucson, AZ 85721 USA. NR 15 TC 4 Z9 4 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0021-8936 J9 J APPL MECH-T ASME JI J. Appl. Mech.-Trans. ASME PD SEP PY 2001 VL 68 IS 5 BP 731 EP 739 DI 10.1115/1.1379528 PG 9 WC Mechanics SC Mechanics GA 471MX UT WOS:000170934100005 ER PT J AU Hash, DB Bose, D Rao, MVVS Cruden, BA Meyyappan, M Sharma, SP AF Hash, DB Bose, D Rao, MVVS Cruden, BA Meyyappan, M Sharma, SP TI Impact of gas heating in inductively coupled plasmas SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID 2-DIMENSIONAL FLUID MODEL; HIGH-DENSITY PLASMA; RF GLOW-DISCHARGES; SELF-CONSISTENT; HYBRID MODEL; LOW-PRESSURE; MULTICOMPONENT PLASMAS; PROCESSING REACTORS; AMBIPOLAR DIFFUSION; SIMULATION AB Recently it has been recognized that the neutral gas in inductively coupled plasma reactors heats up significantly during processing. The resulting gas density variations across the reactor affect reaction rates, radical densities, plasma characteristics, and uniformity within the reactor. A self-consistent model that couples the plasma generation and transport to the gas flow and heating has been developed and used to study CF4 discharges. A Langmuir probe has been used to measure radial profiles of electron density and temperature. The model predictions agree well with the experimental results. As a result of these comparisons along with the poorer performance of the model without the gas-plasma coupling, the importance of gas heating in plasma processing has been verified. (C) 2001 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Hash, DB (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 63 TC 37 Z9 40 U1 1 U2 4 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 SEP 1 PY 2001 VL 90 IS 5 BP 2148 EP 2157 DI 10.1063/1.1390503 PG 10 WC Physics, Applied SC Physics GA 465MZ UT WOS:000170593900006 ER PT J AU Ray, CA Vasques, M Miller, TA Wilkerson, MK Delp, MD AF Ray, CA Vasques, M Miller, TA Wilkerson, MK Delp, MD TI Effect of short-term microgravity and long-term hindlimb unloading on rat cardiac mass and function SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE heart; deconditioning; cardiac atrophy ID HEAD-DOWN SUSPENSION; SIMULATED MICROGRAVITY; BLOOD-FLOW; ECHOCARDIOGRAPHIC EVALUATION; ORTHOSTATIC INTOLERANCE; CHEMICAL SYMPATHECTOMY; BED-REST; SPACEFLIGHT; PRESSURE; EXERCISE AB The purpose of this study was to test the hypothesis that exposure to short-term microgravity or long-term hindlimb unloading induces cardiac atrophy in male Sprague-Dawley rats. For the microgravity study, rats were subdivided into four groups: preflight (PF, n = 12); flight (Fl, n = 7); flight cage simulation (Sim, n = 6), and vivarium control (Viv, n = 7). Animals in the Fl group were exposed to 7 days of microgravity during the Spacelab 3 mission. Animals in the hindlimb-unloading study were subdivided into three groups: control (Con, n = 20), 7-day hindlimb-unloaded (7HU, n = 10), and 28-day hindlimb-unloaded (28HU, n = 19). Heart mass was unchanged in adult animals exposed to 7 days of actual microgravity (PF 1.33 +/- 0.03 g; Fl 1.32 +/- 0.02 g; Sim 1.28 +/- 0.04 g; Viv 1.35 +/- 0.04 g). Similarly, heart mass was unaltered with hindlimb unloading (Con 1.40 +/- 0.04 g; 7HU 1.35 +/- 0.06 g; 28HU 1.42 +/- 0.03 g). Hindlimb unloading also had no effect on the peak rate of rise in left ventricular pressure, an estimate of myocardial contractility (Con 8,055 +/- 385 mmHg/s; 28HU 8,545 +/- 755 mmHg/s). These data suggest that cardiac atrophy does not occur after short-term exposure to microgravity and that neither short- nor long-term simulated microgravity alters cardiac mass or function. C1 Penn State Univ, Milton S Hershey Med Ctr, Coll Med, Div Cardiol H047,Dept Med, Hershey, PA 17033 USA. Penn State Univ, Coll Med, Dept Cellular & Mol Physiol, Hershey, PA 17033 USA. NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Texas A&M Univ, Dept Hlth & Kinesiol, College Stn, TX 77843 USA. Texas A&M Univ, Hlth Sci Ctr, Dept Med Physiol, College Stn, TX 77843 USA. Texas A&M Univ, Hlth Sci Ctr, Cardiovasc Res Inst, College Stn, TX 77843 USA. RP Ray, CA (reprint author), Penn State Univ, Milton S Hershey Med Ctr, Coll Med, Div Cardiol H047,Dept Med, Hershey, PA 17033 USA. FU NHLBI NIH HHS [HL-58503] NR 43 TC 20 Z9 22 U1 0 U2 3 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD SEP PY 2001 VL 91 IS 3 BP 1207 EP 1213 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 464VQ UT WOS:000170552800025 PM 11509517 ER PT J AU Arkoosh, MR Clemons, E Huffman, P Kagley, AN AF Arkoosh, MR Clemons, E Huffman, P Kagley, AN TI Increased susceptibility of juvenile Chinook salmon to vibriosis after exposure to chlorinated and aromatic compounds found in contaminated urban estuaries SO JOURNAL OF AQUATIC ANIMAL HEALTH LA English DT Article ID POLYCHLORINATED-BIPHENYLS; ONCORHYNCHUS-TSHAWYTSCHA; PUGET-SOUND; WASHINGTON; FISH AB Saltwater-adapted juvenile chinook salmon Oncorhynchus tshawytscha exposed to aromatic and chlorinated compounds, representative of contaminants found in urban estuaries in Puget Sound, have a higher susceptibility to vibriosis than do fish exposed only to the solvent vehicle. Susceptibility to vibriosis was assessed by examining the percent cumulative mortality of the salmon after exposure to the bacterial pathogen Vibrio anguillarum. The aromatic and chlorinated compounds examined consisted of a sediment extract from the Hylebos Waterway that was enriched in butadienelike compounds (chlorinated-enriched Hylebos Waterway sediment extract (CHWSE]), a model mixture of polycyclic aromatic hydrocarbons (PAHs), a polychlorinated biphenyl mixture (Aroclor 1254), hexachlorobutadiene (HCBD), and 7,12-dimethylbenz[a]anthracene (DMBA). Two trials were conducted. In trial 1, the percent cumulative mortality of juvenile chinook salmon exposed to V. anguillarum after receiving either CHWSE, HCBD, or the model mixture of PAHs ranged from 28% to 31% compared with the 16% observed in the acetone: emulphor control group at 7 d post-bacterial challenge. In trial 2, the net cumulative mortality of juvenile chinook salmon exposed to V. anguillarum after receiving either DMBA or Aroclor 1254 ranged from 46% to 49% compared with the 25% observed in the acetone:emulphor control group at 9 d postchallenge. The differences in mortality between groups of fish in the treated and control groups in both trials were significant at P less than or equal to 0.05. These findings suggest that a higher predisposition to infection and subsequent disease can occur in salmon exposed to chemical contaminants found in urban estuaries of Puget Sound, Washington. C1 NOAA, Environ Conservat Div, NW Fisheries Sci Ctr, Natl Marine Fisheries Serv, Newport, OR 97365 USA. NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Environm Conservat Div, Seattle, WA 98112 USA. RP Arkoosh, MR (reprint author), NOAA, Environ Conservat Div, NW Fisheries Sci Ctr, Natl Marine Fisheries Serv, 2030 S Marine Sci Dr, Newport, OR 97365 USA. NR 28 TC 53 Z9 57 U1 2 U2 14 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 USA SN 0899-7659 J9 J AQUAT ANIM HEALTH JI J. Aquat. Anim. Health PD SEP PY 2001 VL 13 IS 3 BP 257 EP 268 DI 10.1577/1548-8667(2001)013<0257:ISOJCS>2.0.CO;2 PG 12 WC Fisheries; Veterinary Sciences SC Fisheries; Veterinary Sciences GA 479AP UT WOS:000171382000009 ER PT J AU Chang, T Chapman, S Klimas, A AF Chang, T Chapman, S Klimas, A TI Forced and/or self-organized criticality (FSOC) in space plasmas - Preface SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Editorial Material C1 MIT, CSR, Ctr Theoret Geo Cosmo Plasma Phys, Cambridge, MA 02139 USA. Univ Warwick, Dept Phys, Space Astrophys Grp, Coventry CV4 7AL, W Midlands, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chang, T (reprint author), MIT, CSR, Ctr Theoret Geo Cosmo Plasma Phys, 37-271,77 Massachusetts Ave, Cambridge, MA 02139 USA. RI Chapman, Sandra/C-2216-2008 OI Chapman, Sandra/0000-0003-0053-1584 NR 0 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 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD SEP PY 2001 VL 63 IS 13 BP 1359 EP 1359 DI 10.1016/S1364-6826(00)00236-4 PG 1 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 456ZZ UT WOS:000170113800001 ER PT J AU Takalo, J Timonen, J Klimas, AJ Valdivia, JA Vassiliadis, D AF Takalo, J Timonen, J Klimas, AJ Valdivia, JA Vassiliadis, D TI A coupled map as a model of the dynamics of the magnetotail current sheet SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE self-organized criticality; magnetospheric dynamics; current sheet ID SELF-ORGANIZED CRITICALITY; PLASMA SHEET; AE; MAGNETOSPHERE; INDEXES; FIELD AB A magnetic field model of the magnetotail current sheet in the form of a coupled-map lattice (CML) is presented. It is continuously driven ("running") and based on the MHD diffusion equation. Solar wind vB(s) data (solar wind speed multiplied by the southward component of IMF) are used for driving the model, and it is shown to exhibit perturbations (avalanches) with power-law scalings in their distributions of duration and size. Such distributions may indicate self-organized critical (SOC) behavior. Furthermore, it is shown that the power spectra of the model outputs are of bicolor power-law form with different slopes for high and low frequencies. Although the "running" model gives power-law distributions independent of the strength of the driver, it is argued that the model is in SOC state only when driven slowly. When the driver is strong the model acts more like an input-output system, and the power laws are possibly due to the statistics of the driver. This is supported by the fact that durations of southward turnings of IMF have also a power-law distribution. It is also shown that by driving the model very strongly we can reproduce AE data with correlation 0.74 by using large resistivity, and Dst with correlation 0.79 by using small resistivity. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Jyvaskyla, Dept Phys, FIN-40351 Jyvaskyla, Finland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Takalo, J (reprint author), Univ Oulu, Inst Space Phys, Dept Phys Sci, POB 3000, FIN-90014 Oulu, Finland. RI Valdivia, Juan/A-3631-2008 OI Valdivia, Juan/0000-0003-3381-9904 NR 31 TC 8 Z9 8 U1 0 U2 2 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 SEP PY 2001 VL 63 IS 13 BP 1407 EP 1414 DI 10.1016/S1364-6826(00)00242-X PG 8 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 456ZZ UT WOS:000170113800007 ER PT J AU Uritsky, V Pudovkin, M Steen, A AF Uritsky, V Pudovkin, M Steen, A TI Geomagnetic substorms as perturbed self-organized critical dynamics of the magnetosphere SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE substorms; self-organized criticality; sandpiles; phase transitions ID SOLAR-WIND; AE-INDEX; MODEL; MANIFESTATION; RECONNECTION; MAGNETOTAIL; SPECTRA; SYSTEMS AB The effect of self-organized criticality (SOC), known from the theory of complex nonlinear systems, is considered as an internal mechanism of geomagnetic fluctuations accompanying the development of magnetospheric substorms. It is suggested that spatially localized current sheet instabilities, followed by magnetic reconnection in the magnetotail, can be considered as SOC avalanches, the superposition of which leads naturally to the 1/f(beta) power spectra (f - frequency, beta - numerical parameter) of geomagnetic activity. A running 2D avalanche model with controlled dissipation rate is proposed for numerical investigation of the multi-scale plasma sheet behavior in stationary and nonstationary states of the magnetosphere. Two basic types of perturbations have been studied, the first induced by an increase in the solar wind energy input rate and the second induced by a decrease in critical current density in the magnetotail. The intensity of large-scale perturbations in the model depends on accumulated energy level and internal dissipation in a manner similar to the dependence characteristic of real magnetospheric substorms. A spectral structure of model dynamics exposed to variations of solar wind parameters reveals distinctive features similar to natural geomagnetic fluctuations, including a spectral break at 5 h separating frequency bands with different spectral slopes. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. St Petersburg State Univ, Inst Phys, St Petersburg 198904, Russia. Swedish Inst Space Phys, S-98128 Kiruna, Sweden. RP Uritsky, V (reprint author), NASA, Goddard Space Flight Ctr, MC 692, Greenbelt, MD 20771 USA. NR 30 TC 19 Z9 19 U1 0 U2 2 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 SEP PY 2001 VL 63 IS 13 BP 1415 EP 1424 DI 10.1016/S1364-6826(00)00243-1 PG 10 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 456ZZ UT WOS:000170113800008 ER PT J AU Uritsky, VM Klimas, AJ Valdivia, JA Vassiliadis, D Baker, DN AF Uritsky, VM Klimas, AJ Valdivia, JA Vassiliadis, D Baker, DN TI Stable critical behavior and fast field annihilation in a magnetic field reversal model SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE self-organised criticality; geomagnetic substorms; magnetic reconnection ID SELF-ORGANIZED CRITICALITY; SPORADIC LOCALIZED RECONNECTIONS; PLASMA SHEET; INTERMITTENT TURBULENCE; GEOTAIL OBSERVATIONS; INNER MAGNETOTAIL; SCALE-INVARIANCE; SUBSTORM; MAGNETOSPHERE; INTENSIFICATIONS AB We show that the Lu (Phys. Rev. Lett. 74(13) (1995) 2511) model, which is known to exhibit some properties of a system in self-organized criticality (SOC) [Lu, 1995; Klimas et al. (J. Geophys. Res. 105 (2000) (A8),18,765-18,780.)], can be obtained through a reduction of the resistive MHD system to an idealized one-dimensional limit. Resistivity in this model is anomalous and localized and is due to the excitation of an idealized current-driven instability at positions where large spatial gradients appear in the magnetic field distribution, We note that, by reversing the reduction to the idealized one-dimensional limit, the Lu model presents an opportunity to construct a true MHD system that incorporates kinetic phenomena when small spatial scales are generated which may evolve into SOC under some conditions. We study the evolution of this model in a driven magnetic field reversal configuration on a high-resolution spatial grid. It has been shown earlier that the behavior of several parameters that are global measures of the state of the field reversal suggests that the reversal can evolve into SOC (Klimas et al., 2000). Here, we study the internal dynamics of the field reversal during the unloading phase of a loading-unloading cycle. Unloading is due to internal, localized, dynamic field annihilation; no flux is lost by the system through its boundaries. For this continuum model, we define an "avalanche' as a group of unstable grid points that are contiguous in position and time. We demonstrate scale-free power-law size and duration distributions for these avalanches during the unloading phase of a loading-unloading cycle. We further demonstrate the stability of these distributions; they do not evolve significantly as the unloading progresses. Box counting statistics on the position-time plane show that the avalanches can be characterized as intermittent one-dimensional structures; gaps in these otherwise one-dimensional structures lower their dimension to below one. The stable scale-free avalanche size and duration distributions, plus the fractal structure of the avalanches at small scales, provide further evidence that solutions of the continuum Lu model in a field reversal configuration can evolve into SOC. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Seabrook, MD USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. RP Uritsky, VM (reprint author), NASA, Goddard Space Flight Ctr, MC 692, Greenbelt, MD 20771 USA. EM vadim@roselott.gsfc.nasa.gov RI Valdivia, Juan/A-3631-2008 OI Valdivia, Juan/0000-0003-3381-9904 NR 41 TC 18 Z9 18 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD SEP PY 2001 VL 63 IS 13 BP 1425 EP 1433 DI 10.1016/S1364-6826(00)00244-3 PG 9 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 456ZZ UT WOS:000170113800009 ER PT J AU Wu, DL AF Wu, DL TI Horizontal wavenumber spectra of MLS radiance fluctuations SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE gravity wave spectrum; temperature fluctuations; satellite observations ID ATMOSPHERIC VELOCITY FLUCTUATIONS; GRAVITY-WAVE VARIANCE; MIDDLE ATMOSPHERE; UNIVERSAL SPECTRUM; VARIABILITY; CLIMATOLOGY; SATURATION; TURBULENCE; MESOSPHERE; DIFFUSION AB Radiance fluctuations from Upper Atmosphere Research Satellite Microwave Limb Sounder (UARS MLS) reflect atmospheric temperature oscillations of short ( greater than or equal to 30 km) horizontal and long (> 10 km) vertical wavelengths at 38-80 km altitudes. These radiance fluctuations often show wave-like structures with clear phase coherence among different altitudes. This paper applies a spectral analysis to MLS limb-tracking radiances and obtains a seasonal climatology of horizontal wavenumber spectra at scales of 50-800 km for 6 altitudes (38, 43, 48, 53, 61 and 80 km) and 8 latitudes (from 70 degreesS to 70 degreesN). Most of the power spectra exhibit a slope close to -2 but some can be as steep as -3 in wave active regions. The spectral power density is strongly season-and-latitude dependent in the stratosphere, which is thought largely due to the modulation of the background winds on the vertical wavenumber spectrum. The spectral amplitudes grow exponentially with height between 38 and 50 km but the growth rate becomes small or close to zero near and above 50 km. The growth rates at 38-53 km attitudes are scale-dependent showing less efficient vertical propagation for larger-scale waves. The near-zero growth in the lower mesosphere is thought mainly due to wave saturation/breaking at these altitudes. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wu, DL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Wu, Dong/D-5375-2012 NR 36 TC 14 Z9 14 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 SEP PY 2001 VL 63 IS 14 BP 1465 EP 1477 DI 10.1016/S1364-6826(01)00025-6 PG 13 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 469VT UT WOS:000170837300002 ER PT J AU Carlotti, M Ade, PAR Carli, B Chipperfield, M Hamilton, PA Mencaraglia, F Nolt, IG Ridolfi, M AF Carlotti, M Ade, PAR Carli, B Chipperfield, M Hamilton, PA Mencaraglia, F Nolt, IG Ridolfi, M TI Diurnal variability and night detection of stratospheric hydroxyl radical from far infrared emission measurements SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE hydroxyl radical; remote sensing; stratospheric spectroscopy ID OH; MESOSPHERE; DESIGN; LIDAR; HOX AB We report the measurement of the stratospheric hydroxyl radical (OH) performed with a balloon-borne far-infrared Fourier Transform Spectrometer. Continuous observations were made, on a mid-latitude air mass, between 15 km and about 38 km, with a cycling limb-scanning observation technique. The measurement period commenced before the local noon and ended just before sunrise on the following day, permitting nearly complete observations of the diurnal OH cycle. A retrieval analysis of the daytime observations has produced a set of altitude-distribution profiles of the volume-mixing ratio, from 22 to 38 km, that provides a picture of the variation of the radical as a function of the solar zenith angle at 1 km altitude steps. Above 38 km column density values have been determined. The observations taken at sunset show the expected rapid decay of OH. The nighttime data also show residual spectral features in correspondence to OH transitions. A spectroscopic analysis, carried out with the help of simulated spectra, indicates that these spectral features are most likely due to the OH transitions and hence these data provide the first positive detection of OH in the stratosphere in darkness. The retrieval analysis of the nighttime spectral features has established that the nighttime OH distribution is peaked around 36 km with a mixing ratio of 3.2 +/- 2.0 ppt; values for the column density are also determined above and below this altitude. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Bologna, Dipartimento Chim Fis & Inorgan, I-40136 Bologna, Italy. Univ London Queen Mary & Westfield Coll, Dept Phys, London E1 4NS, England. CNR, Ist Ric Onde Elettromagnet, I-50127 Florence, Italy. Univ Leeds, Sch Environm, Leeds LS2 9JT, W Yorkshire, England. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Carlotti, M (reprint author), Univ Bologna, Dipartimento Chim Fis & Inorgan, Viale Risorgimento 4, I-40136 Bologna, Italy. RI Chipperfield, Martyn/H-6359-2013 OI Chipperfield, Martyn/0000-0002-6803-4149 NR 24 TC 6 Z9 6 U1 1 U2 5 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 SEP PY 2001 VL 63 IS 14 BP 1509 EP 1518 DI 10.1016/S1364-6826(01)00030-X PG 10 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 469VT UT WOS:000170837300006 ER PT J AU Almeida, EAC Sutijono, D Damsky, CH Globus, RK AF Almeida, EAC Sutijono, D Damsky, CH Globus, RK TI Adhesion of primary osteoblasts to fibronectin activates focal adhesion kinase and promotes cell survival signaling. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif San Francisco, San Francisco, CA 94143 USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER SOC BONE & MINERAL RES PI WASHINGTON PA 2025 M ST, N W, STE 800, WASHINGTON, DC 20036-3309 USA SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD SEP PY 2001 VL 16 SU 1 BP S498 EP S499 PG 2 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 467MU UT WOS:000170709001523 ER PT J AU Arnaud, SB Thierry-Palmer, M Cleek, T Cappiello, D Dasalla, M Whalen, RT AF Arnaud, SB Thierry-Palmer, M Cleek, T Cappiello, D Dasalla, M Whalen, RT TI The effect of skeletal unloading on the strength of the femurs in Dahl salt-sensitive and salt-resistant female rats. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Morehouse Sch Med, Atlanta, GA 30310 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC BONE & MINERAL RES PI WASHINGTON PA 2025 M ST, N W, STE 800, WASHINGTON, DC 20036-3309 USA SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD SEP PY 2001 VL 16 SU 1 BP S364 EP S364 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 467MU UT WOS:000170709000936 ER PT J AU Evans, GL Kennedy, AM Morey-Holton, E Turner, RT AF Evans, GL Kennedy, AM Morey-Holton, E Turner, RT TI Effects of combined treatment of hindlimb unloaded rats with PTH and tamoxifen. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 Mayo Clin, Rochester, MN USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC BONE & MINERAL RES PI WASHINGTON PA 2025 M ST, N W, STE 800, WASHINGTON, DC 20036-3309 USA SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD SEP PY 2001 VL 16 SU 1 BP S539 EP S539 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 467MU UT WOS:000170709001703 ER PT J AU LeBlanc, AD Shackleford, L Driscoll, T Evans, H Rianon, N Smith, S AF LeBlanc, AD Shackleford, L Driscoll, T Evans, H Rianon, N Smith, S TI Alendronate as a potential countermeasure to microgravity induced bone loss. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 Baylor Coll Med, Houston, TX 77030 USA. Lyndon B Johnson Space Ctr, Houston, TX USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC BONE & MINERAL RES PI WASHINGTON PA 2025 M ST, N W, STE 800, WASHINGTON, DC 20036-3309 USA SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD SEP PY 2001 VL 16 SU 1 BP S285 EP S285 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 467MU UT WOS:000170709000607 ER PT J AU Shackelford, LC LeBlanc, A Feiveson, A Smith, SM Feeback, D Greenisen, M AF Shackelford, LC LeBlanc, A Feiveson, A Smith, SM Feeback, D Greenisen, M TI Exercise countermeasure to disuse osteoporosis. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Baylor Coll Med, Houston, TX 77030 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER SOC BONE & MINERAL RES PI WASHINGTON PA 2025 M ST, N W, STE 800, WASHINGTON, DC 20036-3309 USA SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD SEP PY 2001 VL 16 SU 1 BP S485 EP S485 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 467MU UT WOS:000170709001458 ER PT J AU Thierry-Palmer, M Pasquali, M Hatch, P Arnaud, SB AF Thierry-Palmer, M Pasquali, M Hatch, P Arnaud, SB TI The effect of a vitamin K supplement on bone loss induced by skeletal unloading. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 Morehouse Sch Med, Atlanta, GA 30310 USA. Emory Univ, Atlanta, GA 30322 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC BONE & MINERAL RES PI WASHINGTON PA 2025 M ST, N W, STE 800, WASHINGTON, DC 20036-3309 USA SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD SEP PY 2001 VL 16 SU 1 BP S448 EP S448 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 467MU UT WOS:000170709001306 ER PT J AU Simon, MK AF Simon, MK TI Evaluation of average bit error probability for space-time coding based on a simpler exact evaluation of pairwise error probability SO JOURNAL OF COMMUNICATIONS AND NETWORKS LA English DT Article DE space-time codes; fading channels; error probability performance ID RATE WIRELESS COMMUNICATION; FADING CHANNELS; PERFORMANCE; CODES AB The moment generating function method previously proposed by the author for the analysis of uncoded and coded digital communication over fading channels using only a single transmitter is applied to provide a simple exact evaluation of the pairwise error probability (PEP) for space-time coded systems with multiple transmitters. In certain scenarios. the PEP (and therefore the approximation to the average bit error probability (BEP)) can be evaluated in closed form. An example of such a closed-form evaluation is presented for the 4-state space-time code described in the literature with both slow (constant over the length of a codeword) and fast (constant over the duration of a symbol) Rayleigh fading. The method also has the additional advantage of allowing for direct evaluation of the transfer function upper bound on average BEP for the latter case. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Simon, MK (reprint author), CALTECH, Jet Prop Lab, Mail Stop 238-343, Pasadena, CA 91109 USA. NR 11 TC 51 Z9 53 U1 0 U2 0 PU KOREAN INST COMMUNICATIONS SCIENCES (K I C S) PI SEOUL PA HYUNDAI KIRIM OFFICETEL 1504-6 SEOCHODONG 1330-18, SEOCHOKU, SEOUL 137-070, SOUTH KOREA SN 1229-2370 J9 J COMMUN NETW JI J. Commun. Netw. PD SEP PY 2001 VL 3 IS 3 BP 257 EP 264 PG 8 WC Computer Science, Information Systems; Telecommunications SC Computer Science; Telecommunications GA 481EP UT WOS:000171507200009 ER PT J AU Dold, P Croll, A Lichtensteiger, M Kaiser, T Benz, KW AF Dold, P Croll, A Lichtensteiger, M Kaiser, T Benz, KW TI Floating zone growth of silicon in magnetic fields: IV. Rotating magnetic fields SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE computer simulation; rotating magnetic fields; segregation; thermocapillary convection; floating zone technique; semiconducting silicon ID SINGLE-CRYSTALS; FLUID-FLOW; HEAT AB Transverse rotating magnetic fields (B-max = 7.5 mT, f(rot) = 50 Hz) were applied to the floating zone growth of doped silicon. Non-periodic dopant fluctuations caused by time-dependent thermocapillary convection were considerably reduced by the rotating field. The radial segregation profiles (measured by a spreading resistance probe) became more homogeneous and more symmetric. The transition from a regime dominated by time-dependent thermocapillary convection to a flow state characterized by the rotating magnetic field was determined. This threshold depends on the height of the melt as well as the melt diameter (crystals between 8 and 14 mm have been investigated) and the efficiency of the applied field increases with larger melt zones. For a melt of 14 mm in diameter and an aspect ratio of I it is in the range of 2.5-3.75 mT/50 Hz (corresponding to a Taylor number of Ta = 9.3 x 10(3) -2.1 x 10(-4)). The change from a time-dependent 3D-flow without field to a quasi-axisymmetric 2D-flow with the magnetic field is corroborated by numerical simulations of the flow field: the thermocapillary driven irregular flow rolls are transformed to a nearly axisymmetric flow with high azimuthal flow velocities but reduced axial and radial components. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Freiburg, Inst Kristallog, D-79104 Freiburg, Germany. Tech Univ Freiberg, Inst NE Metalle & Reinststoffe, D-09599 Freiburg, Germany. NASA, MSFC, USRA, Huntsville, AL 35812 USA. RP Dold, P (reprint author), Univ Freiburg, Inst Kristallog, Hebelstr 25, D-79104 Freiburg, Germany. RI Croell, Arne/A-2480-2013 OI Croell, Arne/0000-0002-8673-9994 NR 33 TC 36 Z9 39 U1 2 U2 9 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 SEP PY 2001 VL 231 IS 1-2 BP 95 EP 106 DI 10.1016/S0022-0248(01)01491-9 PG 12 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 457DV UT WOS:000170122600014 ER PT J AU Coplan, MA Ipavich, F King, J Ogilvie, KW Roberts, DA Lazarus, AJ AF Coplan, MA Ipavich, F King, J Ogilvie, KW Roberts, DA Lazarus, AJ TI Correlation of solar wind parameters between SOHO and Wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA CORRELATIONS; TURBULENCE; FLUCTUATIONS; ISEE-1; PLANAR; WAVES AB We describe and interpret new results obtained by correlating measurements of solar wind speed, density, and flux made by the plasma instruments on the SOHO and Wind spacecraft at separations between +/- 150 Earth radii (R(E)) in the Y (GSE) direction and up to 280 R(E) in the X (GSE) direction. These measurements cover the period from 1996 to mid-1998 and all of 1999, a total of 3.5 years. We have correlated observations spaced 96 s apart over 2-hour intervals and observations spaced 300 s apart over 6-hour intervals. Typical average correlation coefficients for solar wind flux are 0.6 +/- 0.2 with 10% of the 2-hour intervals and 22% of the 6-hour intervals having correlation coefficients >0.8. Comparing the 2- and 6-hour results, correlation coefficients are systematically smaller for the higher time resolution data. This is a result of a larger random data component and fewer solar wind plasma parameter changes in the 2-hour data compared to the 6-hour data. We interpret the results in terms of inclined planar fronts which provide an attractive and useful way of organizing the data. The front azimuth angles are, on average, in the same quadrant as the average Parker spiral angle. A limited three-dimensional analysis of the fronts shows their normals to be inclined, on average, by a few tens of degrees to the ecliptic plane. Possible factors that could control front angles are examined, and long-term correlations with solar activity are discussed. The effect of discontinuities in the interplanetary medium is also discussed. C1 Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Coplan, MA (reprint author), Univ Maryland, Inst Phys Sci & Technol, CSS Bldg, College Pk, MD 20742 USA. EM coplan@glue.umd.edu; ipavich@umtof.umd.edu; joshking@pop.wam.umd.edu; keith.ogilvie@gsfc.nasa.gov; roberts@vayu.gsfc.nasa.gov; ajl@space.mit.edu RI Roberts, Dana/D-4625-2012 NR 29 TC 10 Z9 10 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 SEP 1 PY 2001 VL 106 IS A9 BP 18615 EP 18624 DI 10.1029/2000JA000459 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 468CB UT WOS:000170739600012 ER PT J AU Chi, PJ Russell, CT Raeder, J Zesta, E Yumoto, K Kawano, H Kitamura, K Petrinec, SM Angelopoulos, V Le, G Moldwin, MB AF Chi, PJ Russell, CT Raeder, J Zesta, E Yumoto, K Kawano, H Kitamura, K Petrinec, SM Angelopoulos, V Le, G Moldwin, MB TI Propagation of the preliminary reverse impulse of sudden commencements to low latitudes SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IONOSPHERIC MASS EJECTION; MAGNETIC-FIELD; MAGNETOSPHERE; EARTH; MAGNETOPAUSE; EQUATOR; MODEL; CME; SSC AB It has been thought that the preliminary reverse impulse (PRI) of the sudden commencements (SC) phenomena occurs simultaneously on the ground at different locations. A popular explanation is that the PRI propagates through the Earth-ionosphere waveguide at the 35 ground magnetometer stations during the SC event on September 24, 1998, and found clear differences in the arrival time of PRI. We calculated the MHD wave propagation time from the location of the first compression of the magnetosphere to the low-latitude ground stations and found good agreement with the observed PRI arrival times, Our calculation also indicates that the wavefront is seriously distorted by the inhomogeneity of the magnetosphere and the small difference in PRI arrival time between high-latitude and low-latitude observations cannot be an indicator of a super-Alfvenic propagation. We also found implications that high-latitude PRIs can be induced by the vortex of ionospheric currents at nearby latitudes, and the motion of the current vortex can affect the arrival time of high-latitude PRIs. C1 Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. Kyushu Univ 33, Dept Earth & Space Sci, Fukuoka 8128581, Japan. Lockheed Martin Adv Res Ctr, Palo Alto, CA 94304 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Chi, PJ (reprint author), Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. RI Moldwin, Mark/F-8785-2011; Le, Guan/C-9524-2012 OI Moldwin, Mark/0000-0003-0954-1770; Le, Guan/0000-0002-9504-5214 NR 32 TC 37 Z9 38 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 SEP 1 PY 2001 VL 106 IS A9 BP 18857 EP 18864 DI 10.1029/2001JA900071 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 468CB UT WOS:000170739600030 ER PT J AU Song, P Kozyra, JU Chandler, MO Russell, CT Peterson, WK Trattner, KJ Friedel, RHW Shue, JH Moore, TE Ogilvie, KW Lepping, RP McComas, DJ AF Song, P Kozyra, JU Chandler, MO Russell, CT Peterson, WK Trattner, KJ Friedel, RHW Shue, JH Moore, TE Ogilvie, KW Lepping, RP McComas, DJ TI Polar observations and model predictions during May 4, 1998, magnetopause, magnetosheath, and bow shock crossings SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SPACECRAFT; ELECTRON; INSTRUMENT; MISSION; ANGLE; SHAPE AB During the rise to the maximum phase of solar cycle 23, several periods of extreme solar wind conditions have occurred. During such an example on May 4, 1998, the solar wind monitors observed a period of strong southward interplanetary magnetic field (IMF) accompanied by a solar wind dynamic pressure that was 30 times higher than average. During this period the Polar spacecraft crossed the magnetopause and bow shock and experienced its first solar wind encounter. This case provides a rare opportunity to study the magnetopause, low-latitude boundary layer, magnetosheath, and bow shock and to test our ability to model the dynamic behavior of these boundary regions under extreme and highly variable solar wind conditions. In this study we use the gas dynamic convected field model to predict the time-dependent magnetic field and plasma properties upstream from the magnetopause and the location of the Polar spacecraft relative to the magnetopause and bow shock during the event. To test the accuracy of the prediction, model magnetic field characteristics are compared to the fields observed along the satellite track by the magnetometer on Polar. The predicted model plasma characteristics (density, velocity, and temperature) are compared to moments derived from TIDE observations, extrapolated to account for the higher energy portion of the magnetosheath distributions. Where ambiguities occur in identifying the satellite location, plasma distribution functions from two additional ion detectors (TIMAS and HYDRA) are used to resolve the observed location of Polar relative to the boundaries. With this procedure, carried out separately for ACE and Wind and for two different magnetopause models, observed features at Polar can be traced back to drivers in the solar wind, providing a unique opportunity to assess the evolution of the solar wind and its predictability from the solar wind monitors to the magnetopause. When the Polar apogee drifts to low latitudes in the future, it will provide more and more observations in this region. Therefore what we learn from this case can be indicative of what we will see in the future in Polar operations. The high-level correlation between the predictions and in situ measurements indicates that the solar wind monitors often provide adequate and useful solar wind conditions near the Earth. The tests indicate that in this event the vacuum dipole field magnetosphere model predicts a significantly larger magnetosphere than observed. While the empirical magnetopause model predictions are more consistent with the observations, they overpredict the response of the magnetosphere to transient southward turnings of the IMF, indicating that the magnetosphere does not respond to the southward IMF turnings on small timescales. Sometimes, there are significant differences at relatively small time scales between the measurements from the two solar wind monitors. It is possible for the solar wind conditions near the Earth to be different from the measurements made by at least one of the solar wind monitors. Cautions should be taken when interpreting near-Earth observations if the observations are inconsistent at small timescales with the predictions based on one solar wind monitor. C1 Univ Michigan, Space Phys Res Lab, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Calif Los Angeles, Inst Geophys & Space Phys, Los Angeles, CA 90095 USA. Lockheed Martin Corp, ATC, Palo Alto, CA 94304 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Song, P (reprint author), Univ Massachusetts, Dept Environm Earth & Atmospher Sci, 600 Suffolk St, Lowell, MA 01854 USA. EM paul_song@uml.edu; JUKozyra@umich.edu; ctrussell@igpp.ucla.edu; trattner@mail.spasci.com; friedel@lanl.gov; shuej1@oval.jhuapl.edu; dmccomas@lanl.gov RI Friedel, Reiner/D-1410-2012; Moore, Thomas/D-4675-2012; Peterson, WK/A-8706-2009 OI Friedel, Reiner/0000-0002-5228-0281; Moore, Thomas/0000-0002-3150-1137; Peterson, WK/0000-0002-1513-6096 NR 19 TC 5 Z9 5 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD SEP 1 PY 2001 VL 106 IS A9 BP 18927 EP 18942 DI 10.1029/2000JA900126 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 468CB UT WOS:000170739600039 ER PT J AU Zhou, XY Tsurutani, BT AF Zhou, XY Tsurutani, BT TI Interplanetary shock triggering of nightside geomagnetic activity: Substorms, pseudobreakups, and quiescent events SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA SHEET; MAGNETOSPHERIC SUBSTORMS; FIELD; MAGNETOTAIL; RECONNECTION; IONOSPHERE; WIND; DISRUPTION; DIVERSION; PARTICLE AB We use Wind solar wind data and Polar U-V imaging data to study the nightside magnetospheric/magnetotail responses to interplanetary shocks/pressure pulses. Of 53 interplanetary shock/pressure pulse events that occurred in 1997 and 1998 at Wind, there are 18 cases where Polar near-midnight UV images are available. All of these 18 events are used in this study. The nightside auroral responses can be classified into three types: substorm expansion phase (SS) (or substorm further intensification) events, pseudobreakup (PB) events, and quiescent (QE) events. It is found that the solar wind preconditions determine the causes of the different auroral responses. A similar to1.5-hour interplanetary magnetic field (IMF) B-s "precondition" (upstream of the interplanetary shock) gives good empirical results. The upstream IMF is strongly southward prior to substorm expansion phase triggerings (44% of all events), the IMF B-Z is similar to0 nT for PB triggerings (39% of all events), and the IMF is purely northward for quiescent events (17%). The evidence for IMF B-s preconditioning is interpreted in terms of a plasma sheet loading mechanism. The interplanetary shock compression effects on the near-Earth tail are discussed in light of existing substorm/PB triggering models. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Zhou, XY (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 46 TC 91 Z9 93 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD SEP 1 PY 2001 VL 106 IS A9 BP 18957 EP 18967 DI 10.1029/2000JA003028 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 468CB UT WOS:000170739600041 ER PT J AU Stevenson, BA Horwitz, JL Germany, G Moore, TE Giles, BL Craven, PD Chandler, MO Su, YJ Parks, GK AF Stevenson, BA Horwitz, JL Germany, G Moore, TE Giles, BL Craven, PD Chandler, MO Su, YJ Parks, GK TI Polar observations of topside field-aligned O+ flows and auroral forms SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ION-CYCLOTRON RESONANCE; HIGH-LATITUDE; IONOSPHERIC PLASMA; MAGNETOSPHERE; WIND; OUTFLOW; CONICS; WAVES; ACCELERATION; CLEFT AB Measurements of thermal O+ ion densities, field-aligned velocities, and fluxes from the Thermal Ion Dynamics Experiment (TIDE) on Polar obtained near 5000 km altitude over the Southern Hemisphere are compared with auroral images from the Ultraviolet Imager (UVI). Three passes were selected for analysis in this paper based on data availability from the TIDE and UVI instruments. Results indicate upward O+ flows in the cleft region but downward O+ flows in the polar cap region. Also, the O+ ion density follows a decreasing trend from the poleward side of the cusp region into the nightside. aurora region. The magnitude of the downward O+ parallel velocities increases from dayside to nightside across the polar cap boundary. The upflows tend to occur over or near auroral forms, while the downflows are seen in relatively dark regions, such as the polar cap. These results are consistent with a cleft ion fountain source for the polar cap O+ ions. In the nightside polar cap, the results indicate a transition from downward to upflowing field-aligned O+ ions near boundaries of bright auroral arcs. C1 Univ Alabama, Ctr Space Plasma & Aeron Res, Huntsville, AL 35899 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Washington, Geophys Program, Seattle, WA 98195 USA. RP Stevenson, BA (reprint author), Axcelis Technol Inc, 108 Cherry Hill Dr, Beverly, MA 01915 USA. RI Moore, Thomas/D-4675-2012; OI Moore, Thomas/0000-0002-3150-1137; Stevenson, Benjamin/0000-0001-9918-1240 NR 43 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 SEP 1 PY 2001 VL 106 IS A9 BP 18969 EP 18979 DI 10.1029/2000JA003042 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 468CB UT WOS:000170739600042 ER PT J AU Tsurutani, BT Arballo, JK Galvan, C Zhang, LD Zhou, XY Lakhina, GS Hada, T Pickett, JS Gurnett, DA AF Tsurutani, BT Arballo, JK Galvan, C Zhang, LD Zhou, XY Lakhina, GS Hada, T Pickett, JS Gurnett, DA TI Polar cap boundary layer waves: An auroral zone phenomenon SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ELECTROSTATIC SOLITARY WAVES; WEAK DOUBLE-LAYERS; ELECTRIC-FIELD STRUCTURES; BAND PLASMA-WAVES; DAYSIDE MAGNETOPAUSE; ACCELERATION REGION; DIFFUSION-PROCESSES; FREQUENCY WAVES; NOISE; MAGNETOSPHERE AB Polar cap boundary layer waves are ELF/VLF electric and magnetic waves detected on field lines just adjacent to the polar cap. Intense waves are present at this location essentially all (96%) of the time. The wave latitude-local time distribution is shown to be the same as that of the Feldstein auroral oval, a distribution centered at similar to 75 degrees at local noon and similar to 65 degrees at local midnight. The most intense waves are detected coincident with the strongest magnetic field gradients (field-aligned currents). Statistically, the, wave intensities are greatest near local noon (10(-13) mV(2) m(-1) at 3 kHz) and midnight and are least near dawn and dusk (similar to5 x 10(-15) mV(2) m(-1) at 3 kHz). The noon and midnight wave intensities increase slightly when the interplanetary magnetic field is directed southward. The dawn and dusk waves appear to be controlled by the solar wind speed. Using high-resolution data, specific frequency bands of electromagnetic whistler-mode waves are identified: similar to 200 Hz and 1-2 and similar to5 kHz. These may correspond to previously identified "magnetic noise bursts" and "auroral hiss", respectively. Assuming cyclotron resonant interactions, the 1- to 5-kHz auroral hiss is shown to be resonant with similar to 50-eV to similar to1.0-keV electrons. Several mechanisms, both resonant (nonlocal) and nonresonant (local), are suggested for the generation of the similar to 200-Hz electromagnetic waves. Three types of intense electric signals are present: solitary bipolar pulses (electron holes), waves at similar to4 x 10(2) to 6 x 10(3) Hz (lower hybrid waves), and narrowband waves at similar to 10 kHz (electrostatic waves near the upper hybrid resonance frequency). Solitary bipolar pulse onset events have been detected for the first time. The bipolar pulses reached 2 mV in(-1) peak-to-peak amplitudes within 3 ms. An exponential growth rate of 0.72 ms, or 0.25f(ec), was determined. The previously reported "broadband nature" of the polar cap boundary layer (and low-latitude boundary layer) waves is now postulated to be caused by a fast switching between the various electromagnetic and electrostatic modes described above. The polar cap boundary layer waves are most likely a consequence of instabilities associated with auroral zone field-aligned currents carried by similar to 50-eV to 1.0-keV electrons and protons. The currents in turn have been ascribed to be driven by the solar wind-magnetosphere global interaction. One consequence of the presence of the waves at high altitudes is diffusion of magnetosheath plasma into the magnetosphere and magnetospheric plasma out into the magnetosheath (cross-field diffusion, due to parasitic wave-particle interactions). It is speculated that field-aligned currents and similar wave modes will be detected at all planetary magnetospheres. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Indian Inst Geomagnetism, Bombay 400005, Maharashtra, India. Kyushu Univ, Fukuoka 8168580, Japan. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. RP Tsurutani, BT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Lakhina, Gurbax /C-9295-2012; U-ID, Kyushu/C-5291-2016; OI Lakhina, Gurbax /0000-0002-8956-486X NR 65 TC 12 Z9 12 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 SEP 1 PY 2001 VL 106 IS A9 BP 19035 EP 19055 DI 10.1029/2000JA003007 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 468CB UT WOS:000170739600047 ER PT J AU Le, G Blanco-Cano, X Russell, CT Zhou, XW Mozer, F Trattner, KJ Fuselier, SA Anderson, BJ AF Le, G Blanco-Cano, X Russell, CT Zhou, XW Mozer, F Trattner, KJ Fuselier, SA Anderson, BJ TI Electromagnetic ion cyclotron waves in the high-altitude cusp: Polar observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LOW-FREQUENCY WAVES; VIKING SATELLITE; HOT PLASMA; MAGNETOSHEATH; REGION; PRECIPITATION; INSTRUMENT; ELECTRON; MISSION; CLEFT AB High-resolution magnetic field data from the Polar Magnetic Field Experiment (NIFE) show that narrowband waves at frequencies similar to0.2-3 Hz are a permanent feature in the vicinity of the polar cusp. The waves have been found in the magnetosphere adjacent to the cusp (both poleward and equatorward of the cusp) and in the cusp itself. The occurrence of waves is coincident with. depression of magnetic field strength associated with enhanced plasma density, indicating the entry of magnetosheath plasma into the cusp region. The wave frequencies are generally scaled by the local proton cyclotron frequency and vary between 0.2 and 1.7 times local proton cyclotron frequency. This suggests that the waves are generated in the cusp region by the precipitating magnetosheath plasma. The properties of the waves are highly variable. The waves exhibit both left-handed and right-handed polarization in the spacecraft frame. The propagation angles vary from nearly parallel to nearly perpendicular to the magnetic field. We find no correlation among wave frequency, propagation angle, and polarization. Combined magnetic field and electric field data for the waves indicate that the energy flux of the waves is guided by the background magnetic field and points downward toward the ionosphere. C1 Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Natl Autonomous Univ Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Lockheed Martin Palo Alto Res Lab, Palo Alto, CA 94304 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. RP Le, G (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RI Le, Guan/C-9524-2012; Anderson, Brian/I-8615-2012 OI Le, Guan/0000-0002-9504-5214; NR 24 TC 46 Z9 46 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 SEP 1 PY 2001 VL 106 IS A9 BP 19067 EP 19079 DI 10.1029/2000JA900163 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 468CB UT WOS:000170739600049 ER PT J AU Baker, DN Kanekal, SG Blake, JB Pulkkinen, TI AF Baker, DN Kanekal, SG Blake, JB Pulkkinen, TI TI The global efficiency of relativistic electron production in the Earth's magnetosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; ACCELERATION; ISTP; RADIATION; MERCURY; EVENTS; SSC AB Data from sensors on board the Polar, Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX), and other Earth-orbiting spacecraft show that high-energy electron intensities vary in a global, coherent way throughout the outer trapping zone of the terrestrial magnetosphere. Long-term measurements of very energetic trapped electrons provide a comprehensive view of the large variability of intensities on timescales less than I day to times corresponding to the 11-year sun-spot cycle. The average density of relativistic electrons within the outer magnetospheric trapping region (2.5 2.0.CO;2 PG 22 WC Oceanography SC Oceanography GA 473QZ UT WOS:000171060600004 ER PT J AU Sun, S Bleck, R AF Sun, S Bleck, R TI Thermohaline circulation studies with an Isopycnic Coordinate Ocean Model SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID GREENLAND-SCOTLAND RIDGE; ANTARCTIC BOTTOM WATER; NORTH-ATLANTIC; DEEP-WATER; INDIAN-OCEAN; TRANSPORT; EXCHANGE; THROUGHFLOW; ATMOSPHERE; FLOW AB The thermohaline circulation (THC) in a 1000-yr near-global numerical simulation using the Miami Isopycnic Coordinate Ocean Model is analyzed and compared to observations. The model, driven by observed monthly atmospheric climatology, uses potential density referenced to 2000 M (sigma (2)) as the vertical coordinate and accounts for compressibility (thermobaricity) effects. Examination of the three-dimensional mass flux field reveals that the model comes fairly close to quantitatively reproducing a number of global and basin-scale circulation features, such as the vertical-meridional overturning rate in the three major basins, the meridional heat flux, and the transport through the major passages. Methods are presented that allow the construction of composite diagrams revealing quantitative regional aspects of the modeled circulation in potential density space. The diagrams reveal many features of the modeled THC that adhere to observations. the most noticeable shortcoming being a weaker-than-observed northward penetration of bottom water into the three major basins caused by insufficient production of Antarctic Bottom Water. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Los Alamos Natl Lab, Los Alamos, NM USA. RP Sun, S (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Sun, Shan/H-2318-2015 NR 54 TC 18 Z9 18 U1 0 U2 2 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 SEP PY 2001 VL 31 IS 9 BP 2761 EP 2782 DI 10.1175/1520-0485(2001)031<2761:TCSWAI>2.0.CO;2 PG 22 WC Oceanography SC Oceanography GA 473QZ UT WOS:000171060600014 ER PT J AU Sorte, CJ Peterson, WT Morgan, CA Emmett, RL AF Sorte, CJ Peterson, WT Morgan, CA Emmett, RL TI Larval dynamics of the sand crab, Emerita analoga, off the central Oregon coast during a strong El Nino period SO JOURNAL OF PLANKTON RESEARCH LA English DT Article ID NORTHEAST PACIFIC; OCEAN; VARIABILITY; DECAPODA AB Populations of the sand crab, Emerita analoga, are well established on the California coast. However, populations in Oregon occur sporadically and appear to be restocked by larvae drifting north from California. Due to increased northward transport in winter during El Nino events, we would expect that larval recruitment to northern populations should be higher during these periods. This hypothesis was tested by comparing larval abundances between non-El Nino and El Nino years, 1997 and 1998, respectively. In 1997, larval abundances and seasonality were similar to historical data from 1969-71. First zoeal (Z1) stage larvae were present during these summers, but in low numbers, indicating th at E. analoga spawned off the coast of Oregon. In 1998, strong larval recruitment from the south occurred, demonstrated by a large number of fifth zoeal stage (Z5) larvae collected off Oregon in April and May. The large numbers of Z1 found in summer 1998 indicate that the Z5, which arrived from, California earlier that spring, successfully recruited to adulthood and reproduced. These data indicate that Oregon E.analoga populations are probably dependent on larvae travelling from California in the Davidson Current. It follows that this species could be used as an indicator of coastal current fluctuations such as those seen during El Nino events. C1 Whitman Coll, Dept Biol, Walla Walla, WA 99362 USA. Oregon State Univ, Hatfield Marine Sci Ctr, NW Fisheries Sci Ctr, Natl Marine Fisheries Serv, Newport, OR 97365 USA. Oregon State Univ, Hatfield Marine Sci Ctr, Cooperat Inst Marine Resources Studies, Newport, OR 97365 USA. RP Sorte, CJ (reprint author), Arizona State Univ, Dept Biol, Tempe, AZ 85287 USA. NR 21 TC 19 Z9 19 U1 0 U2 9 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0142-7873 J9 J PLANKTON RES JI J. Plankton Res. PD SEP PY 2001 VL 23 IS 9 BP 939 EP 944 DI 10.1093/plankt/23.9.939 PG 6 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA 477MF UT WOS:000171286800003 ER PT J AU Chakrabarti, S Schmidt, GR AF Chakrabarti, S Schmidt, GR TI Impact of energy gain and subsystem characteristics on fusion propulsion performance SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Rapid transport of large payloads and human crews throughout the solar system requires propulsion systems having very high specific impulse (1(sp) greater than or equal to 10(4) to 10(5) s). It also calls for systems with extremely low mass-power ratios (alpha less than or equal to 10(-1) kg/kW). Such low alpha are beyond the reach of conventional power-limited propulsion, but may be attainable with fusion and other nuclear concepts that produce energy within the propellant. The magnitude of energy gain must be large enough to sustain the nuclear process while still providing a high jet power relative to the massive energy-intensive subsystems associated with these concepts. This paper evaluates the impact of energy gain and subsystem characteristics on alpha. Central to the analysis are general parameters that embody the essential features of any "gain-limited" propulsion power balance. Results show that the gains required to achieve alpha similar to 10(-1) kg/kW with foreseeable technology range from similar to 100 to over 2000, which is three to five orders of magnitude greater than current fusion state of the art. Sensitivity analyses point to the parameters exerting the most influence for either 1) lowering alpha and improving mission performance or 2) relaxing gain requirements and reducing demands on the fusion process. The greatest impact comes from reducing mass and increasing efficiency of the thruster and subsystems downstream of the fusion process. High relative gain, through enhanced fusion processes or more efficient drivers and processors, is also desirable. There is a benefit in improving driver and subsystem characteristics upstream of the fusion process, but it diminishes at relative gains greater than or equal to 100. C1 NASA, George C Marshall Space Flight Ctr, Prop Res Ctr, Huntsville, AL 35812 USA. RP Chakrabarti, S (reprint author), NASA, George C Marshall Space Flight Ctr, Prop Res Ctr, Huntsville, AL 35812 USA. NR 12 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 2001 VL 17 IS 5 BP 988 EP 994 DI 10.2514/2.5859 PG 7 WC Engineering, Aerospace SC Engineering GA 472VM UT WOS:000171005700005 ER PT J AU Lorenzo, CF Ray, A Holmes, MS AF Lorenzo, CF Ray, A Holmes, MS TI Nonlinear control of a reusable rocket engine for life extension SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID DAMAGE-MITIGATING CONTROL; SYSTEMS AB The conceptual development and a design methodology are presented for life-extending control where the objective is to achieve high performance and structural durability of complex dynamic systems. A life-extending controller is designed for a reusable rocket engine via damage mitigation in both the fuel (H-2) and oxidizer (O-2) turbine blades while satisfying the dynamic performance requirements of the combustion chamber pressure and O-2/H-2 mixture ratio. The design procedure makes use of a combination of linear and nonlinear techniques and also allows adaptation of the life-extending controller module to augment a conventional performance controller of the rocket engine. The nonlinear part of the controller is designed by optimizing selected parameters in a prescribed dynamic structure of damage compensation. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Penn State Univ, University Pk, PA 16802 USA. RP Lorenzo, CF (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 14 TC 2 Z9 2 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 2001 VL 17 IS 5 BP 998 EP 1004 DI 10.2514/2.5861 PG 7 WC Engineering, Aerospace SC Engineering GA 472VM UT WOS:000171005700007 ER PT J AU Steinetz, BM Dunlap, PH AF Steinetz, BM Dunlap, PH TI Development of thermal barriers for solid rocket motor nozzle joints SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT 35th Conference of AIAA-ASME-SAE-ASEE on Joint Propulsion CY JUN 22-25, 2000 CL LOS ANGELES, CALIFORNIA SP AIAA, ASME, SAE, ASEE AB Space shuttle solid rocket motor case assembly joints are sealed using conventional O-ring seals that are protected from 5500+degreesF combustion gases by thick layers of insulation and special joint-fill compounds. In the current nozzle-to-case joint design NASA has observed hot gas penetration through defects in the joint-fill compound to the innermost O-ring in one out of seven motors. While not threatening motor safety, evidence of hot gas penetration to the O-rings results in extensive reviews before resuming flight. This paper presents burn-resistance, temperature drop, flow, and resiliency test results for several types of NASA braided carbon fiber thermal barriers that are being implemented in a redesign of the nozzle-to-case joint. In burn-resistance tests the thermal barriers lasted for over six minutes when exposed to the flame of an oxyacetylene torch at 5500 degreesF. Temperature drops of 2500 to 2800 degreesF were measured through the diameter of the thermal barrier in a compressed state when subjected to an oxyacetylene torch flame. Gas temperatures 1/4 in. downstream of the thermal barrier were within the downstream O-ring temperature limit of 600 degreesE. In subscale rocket "char" motor tests the thermal barrier reduced the incoming 3200 degreesF hot gas by 2200 degreesF, spread the incoming jet flow, and blocked hot slag, thereby protecting the downstream O-rings. C1 NASA, John H Glenn Res Ctr Lewis Field, Mech Components Branch, Cleveland, OH 44135 USA. RP Steinetz, BM (reprint author), NASA, John H Glenn Res Ctr Lewis Field, Mech Components Branch, Cleveland, OH 44135 USA. NR 11 TC 1 Z9 1 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 2001 VL 17 IS 5 BP 1023 EP 1034 DI 10.2514/2.5840 PG 12 WC Engineering, Aerospace SC Engineering GA 472VM UT WOS:000171005700011 ER PT J AU Park, C Mehta, UB Bogdanoff, DW AF Park, C Mehta, UB Bogdanoff, DW TI Magnetohydrodynamics energy bypass scramjet performance with real gas effects SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The theoretical performance of a scramjet propulsion system incorporating a magnetohydrodynamic (MHD) energy bypass scheme is calculated. The one-dimensional analysis developed earlier, in which the theoretical performance is calculated neglecting skin friction and using a sudden-freezing approximation for the nozzle flow, is modified to incorporate the method of Van Driest for turbulent skin friction and a finite-rate chemistry calculation in the nozzle. Unlike in the earlier design, in which four ramp compressions occurred in the pitch plane, in the present design the first two ramp compressions occur in the pitch plane, and the next two compressions occur in the yaw plane. The results for the simplified design of a spaceliner show that 1) skin friction substantially reduces thrust and specific impulse and 2) the specific impulse of the MHD-bypass system is still better than the non-MHD system and typical rocket over a range of flight speeds and design parameters. Results suggest that the energy management with MHD principles offers the possibility of improving the performance of the scramjet for the spaceliner application and for the globecruiser application. The technical issues needing further studies are identified. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. Eloret Corp, Sunnyvale, CA 94087 USA. NASA, Ames Res Ctr, Reacting Flow Environm Branch, Moffett Field, CA 94035 USA. RP Park, C (reprint author), NASA, Ames Res Ctr, Space Technol Div, Mail Stop 229-1, Moffett Field, CA 94035 USA. NR 11 TC 10 Z9 13 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 2001 VL 17 IS 5 BP 1049 EP 1057 DI 10.2514/2.5843 PG 9 WC Engineering, Aerospace SC Engineering GA 472VM UT WOS:000171005700014 ER PT J AU Horvath, TJ Berry, SA Hollis, BR Liechty, DS Hamilton, HH Merski, NR AF Horvath, TJ Berry, SA Hollis, BR Liechty, DS Hamilton, HH Merski, NR TI X-33 experimental aeroheating at Mach 6 using phosphor thermography SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SHUTTLE AB The goal of the NASA reusable launch vehicle technology program is to mature and demonstrate essential, cost-effective technologies for next-generation launch systems. The X-33 flight vehicle presently being developed by Lockheed Martin is an experimental single-stage-to-orbit demonstrator that seeks to validate critical technologies and ensure applicability to a full-scale reusable launch vehicle. As with the design of any hypersonic vehicle, the aeroheating environment is an important issue, and one of the key technologies being demonstrated on X-33 is an advanced metallic thermal protection system. As part of the development of this thermal protection system, the X-33 aeroheating environment is being defined through conceptual analysis, ground-based testing, and computational fluid dynamics. An overview of the hypersonic aeroheating wind-tunnel program conducted at the NASA Langley Research Center in support of the ground-based testing activities is provided. Global surface heat transfer images, surface streamline patterns, and shock shapes were measured on 0.013 scale (10-in.) ceramic models of the proposed X-33 configuration in Mach 6 air. The test parametrics include angles of attack from -5 to 40 deg, unit Reynolds numbers from I x 10(6) to 8 x 10(6)/ft, and body-flap deflections of 0, 10, and 20 deg. Experimental and computational results indicate the presence of shock/shock interactions that produced localized heating on the deflected flaps and boundary-layer transition on the canted fins. Comparisons of the experimental data to laminar and turbulent predictions were performed. Laminar windward heating data from the wind tunnel was extrapolated to flight surface temperatures and generally compared to within 50 degreesF of flight prediction along the centerline. When coupled with the phosphor technique, this rapid extrapolation method would serve as an invaluable thermal protection system design tool. C1 NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. RP Horvath, TJ (reprint author), NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NR 32 TC 10 Z9 10 U1 0 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 2001 VL 38 IS 5 BP 634 EP 645 DI 10.2514/2.3748 PG 12 WC Engineering, Aerospace SC Engineering GA 482JQ UT WOS:000171573400001 ER PT J AU Berry, SA Horvath, TJ Hollis, BR Thompson, RA Hamilton, HH AF Berry, SA Horvath, TJ Hollis, BR Thompson, RA Hamilton, HH TI X-33 hypersonic boundary-layer transition SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID ORBITER; NASA AB Boundary-layer and aeroheating characteristics of several X-33 configurations have been experimentally examined in the NASA Langley Research Center 20-Inch Mach 6 Air Tunnel. Global surface heat transfer distributions, surface streamline patterns, and shock shapes were measured on 0.013-scale models at Mach 6 in air. Parametric variations include angles of attack of 20, 30, and 40 deg; Reynolds numbers based on model length of 9 x 10(5) to 6.6 x 10(6); and body-flap deflections of 0, 10, and 20 deg. The effects of discrete and distributed (in the form of wavy wall bowed panels) roughness on boundary-layer transition, which included trip height, size, location, and distribution, both on and off the windward centerline, were investigated. The discrete roughness results on centerline were used to provide a transition correlation for the X-33 flight vehicle that was applicable across the range of reentry angles of attack. The attachment line discrete roughness results were shown to be consistent with the centerline results because no increased sensitivity to roughness along the attachment line was identified. The effect of bowed panels was qualitatively shown to be less effective than the discrete trips; however, the distributed nature of the bowed panels affected a larger percent of the aft-body windward surface than a single discrete trip. C1 NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. RP Berry, SA (reprint author), NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NR 43 TC 20 Z9 20 U1 1 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 2001 VL 38 IS 5 BP 646 EP 657 DI 10.2514/2.3750 PG 12 WC Engineering, Aerospace SC Engineering GA 482JQ UT WOS:000171573400002 ER PT J AU Hollis, BR Horvath, TJ Berry, SA Hamilton, HH Thompson, RA Alter, SJ AF Hollis, BR Horvath, TJ Berry, SA Hamilton, HH Thompson, RA Alter, SJ TI X-33 computational aeroheating predictions and comparisons with experimental data SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SCHEMES AB A computational hypersonic aeroheating study conducted at the NASA Langley Research Center to support development of the X-33 thermal protection system is detailed. In this research, laminar and turbulent aeroheating predictions were generated at wind-tunnel test conditions using two finite volume, Navier-Stokes solvers and a coupled inviscid-solver/boundary-layer-code engineering method. The wind-tunnel computations were performed at Mach 6 for angles of attack of 20-40 deg. Laminar beating distribution comparisons between the predictions and wind-tunnel data were generally within +/- 10% for the Navier-Stokes method and +/- 25% for the engineering code method, whereas turbulent computations were within +/- 20% of the data. Laminar aeroheating computations were also performed at flight conditions using the two Navier-Stokes solvers. Flight-case results from the two Navier-Stokes codes were found to agree to within less than +/- 10%. C1 NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. RP Hollis, BR (reprint author), NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NR 35 TC 11 Z9 11 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 2001 VL 38 IS 5 BP 658 EP 669 DI 10.2514/2.3751 PG 12 WC Engineering, Aerospace SC Engineering GA 482JQ UT WOS:000171573400003 ER PT J AU Murphy, KJ Nowak, RJ Thompson, RA Hollis, BR Prabhu, R AF Murphy, KJ Nowak, RJ Thompson, RA Hollis, BR Prabhu, R TI X-33 hypersonic aerodynamic characteristics SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Lockheed Martin Skunk Works, under a cooperative agreement with NASA, will design, build, and fly the X-33, a half-scale prototype of a rocket-based, single-stage-to-orbit, reusable launch vehicle. A 0.007-scale model of the X-33 604B0002G configuration was tested in five supersonic/hypersonic facilities at the NASA Langley Research Center to examine vehicle aerodynamic characteristics and to establish the aerodynamic flight database for the hypersonic regime. Effects of Mach number and specific heat ratio on hypersonic aerodynamic characteristics were also studied. These results were complemented with computational aerodynamic data, experimental configuration buildup information, and various types of surface and flowfield visualizations to enhance the understanding of experimentally observed aerodynamic trends. Data at both Mach 6 and Mach 10 show the baseline configuration achieves a maximum hypersonic LID of approximately 1.2 between 20 and 30 deg angle of attack. With the center-of-gravity location at 66% of vehicle reference length, the configuration was found to be longitudinally controllable with less than half of the total body flap deflection capability across the angle of attack range at both Mach 6 and Mach 10. The vehicle also was shown to be longitudinally stable or neutrally stable for typical (greater than 20 deg) hypersonic flight attitudes. At Mach 6 and Mach 10, the baseline configuration demonstrated positive dihedral effect (roll stability) but was directionally unstable. Effects of Mach number on longitudinal aerodynamics were shown to be small relative to X-33 control authority. Effects of specific heat ratio on vehicle pitching moment characteristics were shown to be significant at higher angles of attack, but with a maximum flight Mach number of approximately 10, real-gas phenomena are not expected to occur for the X-33's suborbital flights. C1 NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. Lockheed Martin Engn & Sci, Langley Program Off, Hampton, VA 23681 USA. RP Murphy, KJ (reprint author), NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NR 15 TC 10 Z9 16 U1 2 U2 16 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 SEP-OCT PY 2001 VL 38 IS 5 BP 670 EP 683 DI 10.2514/2.3752 PG 14 WC Engineering, Aerospace SC Engineering GA 482JQ UT WOS:000171573400004 ER PT J AU Hollis, BR Thompson, RA Murphy, KJ Nowak, RJ Riley, CJ Wood, WA Alter, SJ Prabhu, RK AF Hollis, BR Thompson, RA Murphy, KJ Nowak, RJ Riley, CJ Wood, WA Alter, SJ Prabhu, RK TI X-33 aerodynamic computations and comparisons with wind-tunnel data SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A computational fluid dynamics study conducted at the NASA Langley Research Center to support the phase II development of the X-33 vehicle is detailed. Aerodynamic computations for the X-33 vehicle were performed using two finite volume, Navier-Stokes solvers and an inviscid Enter code. Computations were made for a range of wind-tunnel test conditions from Mach 4.63 to 10.0 with angles of attack from 10 to 48 deg and body flap deflections of 0, +10, and +20 deg. Additional computations were performed over a parametric range of freestream conditions with Mach numbers of 4-10 and angles of attack of 10-50 deg. Computational results and comparisons with wind-tunnel aerodynamic data are presented. C1 NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. Lockheed Martin Engn & Sci, Hampton, VA 23681 USA. RP Hollis, BR (reprint author), NASA, Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NR 25 TC 4 Z9 6 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 SEP-OCT PY 2001 VL 38 IS 5 BP 684 EP 691 DI 10.2514/2.3753 PG 8 WC Engineering, Aerospace SC Engineering GA 482JQ UT WOS:000171573400005 ER PT J AU Landis, GA Linne, DL AF Landis, GA Linne, DL TI Mars rocket vehicle using in situ propellants SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Mars In-Situ Propellants Rocket (MIPR) is a small vehicle proposed to fly autonomously on Mars, using in-situ propellant production to manufacture rocket propellant directly out of the Martian atmosphere, thus demonstrating the feasibility of using local resources to "live off the land." It is proposed as a payload on a Mars Surveyor class lander as a reusable "hopper" vehicle. The vehicle explores the Martian surface under rocket power and can repeatedly take off and land, carrying a suite of science instruments over a range of hundreds of meters to several kilometers per hop. The flight demonstration will accomplish a range of technology objectives important to both unmanned probes and to future human missions, including demonstration of a suborbital Mars launch vehicle, demonstrating storage of cryogenic propellants on the Mars surface, demonstration of a pressure-fed cryogenic propulsion system for Mars ascent vehicles, demonstration of a lightweight space engine, and use for the first time of propellants manufactured in situ on another planetary body. In addition to these technology objectives, the MIPR vehicle can carry a science payload that will advance our understanding of the surface and atmosphere of Mars. C1 NASA, John H Glenn Res Ctr, Power & Inspace Prop Div, Cleveland, OH 44135 USA. NASA, John H Glenn Res Ctr, Turbomachinery & Prop Syst Div, Cleveland, OH 44135 USA. RP Landis, GA (reprint author), NASA, John H Glenn Res Ctr, Power & Inspace Prop Div, Lewis Field,Mail Stop 302-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 14 TC 8 Z9 8 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 2001 VL 38 IS 5 BP 730 EP 735 DI 10.2514/2.3739 PG 6 WC Engineering, Aerospace SC Engineering GA 482JQ UT WOS:000171573400010 ER PT J AU Kerut, EK Norfleet, WT Plotnick, GD Giles, TD AF Kerut, EK Norfleet, WT Plotnick, GD Giles, TD TI Patent foramen ovale: A review of associated conditions and the impact of physiological size SO JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY LA English DT Review ID ATRIAL SEPTAL ANEURYSM; TRANSESOPHAGEAL CONTRAST ECHOCARDIOGRAPHY; YOUNG STROKE PATIENTS; TO-LEFT SHUNT; DECOMPRESSION-SICKNESS; PLATYPNEA-ORTHODEOXIA; PARADOXICAL EMBOLISM; SEVERE HYPOXEMIA; DIVERS; DIAGNOSIS AB Patent foramen ovale (PFO) is implicated in platypnea-orthodeoxia, stroke and decompression sickness (DCS) in divers and astronauts. However, PFO size in relation to clinical illness is largely unknown since few studies evaluate PFO, either functionally or anatomically. The autopsy incidence of PFO is approximately 27% and 6% for a large defect (0.6 cm to 1.0 cm). A PFO is often associated with atrial septal aneurysm and Chiari network, although these anatomic variations are uncommon. Methodologies for diagnosis and anatomic and functional sizing of a PFO include transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) and transcranial Doppler (TCD), with saline contrast. Saline injection via the right femoral vein appears to have a higher diagnostic yield for PFO than via the right antecubital vein. Saline contrast with TTE using native tissue harmonics or transmitral pulsed wave Doppler have quantitated PFO functional size, while TEE is presently the reference standard. The platypnea-orthodeoxia syndrome is associated with a large resting PFO shunt. Transthoracic echocardiography, TEE and TCD have been used in an attempt to quantitate PFO in patients with cryptogenic stroke. The larger PFOs (approximately greater than or equal to4 mm size) or those with significant resting shunts appear to be clinically significant. Approximately two-thirds of divers with unexplained DCS have a PFO that may be responsible and may be related to PFO size. Limited data are available on the incidence of PFO in high altitude aviators with DCS, but there appears to be a relationship. A large decompression stress is associated with extra vehicular activity (EVA) from spacecraft. After four cases of serious DCS in EVA simulations, a resting PFO was detected by contrast TTE in three cases. Patent foramen ovales vary in both anatomical and functional size, and the clinical impact of a particular PFO in various situations (platypnea-orthodeoxia, thromboembolism, DCS in underwater divers, DCS in high-altitude aviators and astronauts) may be different. (C) 2001 by the American College of Cardiology. C1 Louisiana State Univ, Hlth Sci Ctr, Div Cardiol, Cardiovasc Res Lab, New Orleans, LA 70112 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Maryland Hosp, Div Cardiol, Baltimore, MD 21201 USA. RP Giles, TD (reprint author), Louisiana State Univ, Hlth Sci Ctr, Div Cardiol, Cardiovasc Res Lab, 1542 Tulane Ave,Room 331E, New Orleans, LA 70112 USA. NR 66 TC 210 Z9 218 U1 1 U2 11 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0735-1097 J9 J AM COLL CARDIOL JI J. Am. Coll. Cardiol. PD SEP PY 2001 VL 38 IS 3 BP 613 EP 623 DI 10.1016/S0735-1097(01)01427-9 PG 11 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA 469PG UT WOS:000170823600003 PM 11527606 ER PT J AU Fu, WB Venkat, R Meyyappan, M AF Fu, WB Venkat, R Meyyappan, M TI Theoretical study of GaN molecular beam epitaxy growth using electron cyclotron resonance nitrogen plasma SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article; Proceedings Paper CT 19th North American Conference on Molecular Beam Epitaxy (NAMBE-19) CY OCT 15-18, 2000 CL ARIZONA STATE UNIV, TEMPE, ARIZONA HO ARIZONA STATE UNIV ID GALLIUM NITRIDE; FILMS; GAAS; MBE AB III-V nitrides (GaN, InN, and AIN) are intensely researched for optoelectronic applications spanning the entire visible spectrum. In spite of the realization of commercial devices and advances in processing of materials and devices, the understanding of the processing and epitaxial growth of these materials is incomplete. In this study, a rate equation based on physically sound surface processes to investigate the molecular beam epitaxial growth of GaN using an electron cyclotron resonance (ECR) plasma source is proposed. A surface riding layer of Ga and N plasma species is included in the model. The surface riding species are allowed to undergo several physical and chemical processes. Rates of all surface processes are assumed Arrhenius type. In the ECR plasma, the flux and reactivity of the active nitrogen are modeled based on plasma dynamics and used in our study. The necessary model parameters, which are unknown, were found by fitting results from simulation to experimental values. As the ECR power increases, the flux of active nitrogen and all other N species, which are by-products, increase almost linearly. Thus the Ga to active N flux ratio increases and hence Ga incorporation rate increases and saturates at a maximum rate. Results of growth rate versus temperature behavior are also presented and discussed based on physical mechanisms. Electron concentration obtained from bulk vacancy concentrations of Ga and N decreases linearly with ECR power, unlike the experimental observation of exponential decrease. The discrepancy is due to the fact that the electron concentration is strongly influenced by the incorporation of unintentional impurities from the plasma chamber such as Si, C, and O, which are not modeled in our study. (C) 2001 American Vacuum Society. C1 Univ Nevada, Dept Comp Engn, Las Vegas, NV 89154 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Fu, WB (reprint author), Univ Nevada, Dept Comp Engn, Las Vegas, NV 89154 USA. NR 16 TC 0 Z9 0 U1 1 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD SEP-OCT PY 2001 VL 19 IS 5 BP 1803 EP 1807 DI 10.1116/1.1396637 PG 5 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA 486ED UT WOS:000171804700021 ER PT J AU Ostro, SJ Hudson, RS Benner, LAM Nolan, MC Giorgini, JD Scheeres, DJ Jurgens, RF Rose, R AF Ostro, SJ Hudson, RS Benner, LAM Nolan, MC Giorgini, JD Scheeres, DJ Jurgens, RF Rose, R TI Radar observations of asteroid 1998 ML14 SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID ORBITS; SHAPE AB Goldstone and Arecibo delay-Doppler radar imaging of asteroid 1998 ML14 shortly after its discovery reveals a 1 km diameter spheroid with prominent topography on one side and subdued topography on the other. The object's radar and optical properties are typical for S-class near-Earth asteroids. The gravitational slopes of a shape model derived from the images and assumed to have a uniform density are shallow, exceeding 30 degrees over only 4% of the surface. If 1998 ML14's density distribution is uniform, then its orbital environment is similar to a planetary body with a spheroidal gravitational field and is relatively stable. Integration of a radar-refined orbit reveals that the 1998 apparition was the asteroid's closest approach to Earth since at least 1100 and until 2283, when it approaches to within 2.4 lunar distances. Outside of that time interval, orbit uncertainties based on the present set of observations preclude reliable prediction. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Washington State Univ, Dept Elect Engn & Comp Sci, Pullman, WA 99164 USA. Arecibo Observ, Arecibo, PR 00612 USA. Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. RP Ostro, SJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Nolan, Michael/H-4980-2012 OI Nolan, Michael/0000-0001-8316-0680 NR 12 TC 19 Z9 20 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 SEP PY 2001 VL 36 IS 9 BP 1225 EP 1236 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 478JU UT WOS:000171343900004 ER PT J AU Colombo, JFA Morrell, NI Niemela, VS Corcoran, MF AF Colombo, JFA Morrell, NI Niemela, VS Corcoran, MF TI Optical spectroscopy of X-Mega targets - I. CPD-59 degrees 2635: a new double-lined O-type binary in the Carina Nebula SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : general; stars : early-type; stars : individual : CPD-59 degrees 2635; open clusters and associations : individual : Trumpler 16; X-rays : stars ID MASSIVE STARS; SYSTEM AB Optical spectroscopy of CPD -59 degrees 2635, one of the O-type stars in the open cluster Trumpler 16 in the Carina Nebula, reveals this star to be a double-lined binary system. We have obtained the first radial velocity orbit for this system, consisting of a circular solution with a period of 2.2999 d and semi-amplitudes of 208 and 273 km s(-1). This results in minimum masses of 15 and 11 M-. for the binary components of CPD -59 degrees 2635, which we classified as O8V and O9.5V, although spectral type variations of the order of I subclass, which we identify as the Struve-Sahade effect, seem to be present in both components. From ROSAT HRI observations of CPD -59 degrees 2635 we determine a luminosity ratio log(L-x/L-bol) approximate to -7, which is similar to that observed for other O-type stars in the Carina Nebula region. No evidence of light variations is present in the available optical or X-ray data sets. C1 Natl Univ La Plata, Fac Ciencias Astron & Geofis, RA-1900 La Plata, Argentina. Univ Space Res Assoc, Seabrook, MD 20706 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Colombo, JFA (reprint author), Natl Univ La Plata, Fac Ciencias Astron & Geofis, Paseo Bosque S-N, RA-1900 La Plata, Argentina. NR 29 TC 11 Z9 11 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD SEP 1 PY 2001 VL 326 IS 1 BP 78 EP 84 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 473BK UT WOS:000171019300010 ER PT J AU Morrell, NI Barba, RH Niemela, VS Corti, MA Colombo, JFA Rauw, G Corcoran, M Morel, T Bertrand, JF Moffat, AFJ St-Louis, N AF Morrell, NI Barba, RH Niemela, VS Corti, MA Colombo, JFA Rauw, G Corcoran, M Morel, T Bertrand, JF Moffat, AFJ St-Louis, N TI Optical spectroscopy of X-Mega targets - II. The massive double-lined O-type binary HD 93205 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : general; stars : early-type; stars : individual : HD 93205; X-rays : stars ID EARLY-TYPE STARS; ETA-CARINAE; CLUSTER TRUMPLER-14; STELLAR CONTENT; RAY-EMISSION; EM-CARINAE; FREQUENCY; NEBULA; PARAMETERS; SYSTEMS AB A new high-quality set of orbital parameters for the O-type spectroscopic binary HD 93205 has been obtained combining echelle and coude CCD observations. The radial velocity orbits derived from the He II lambda 4686 Angstrom (primary component) and Hei lambda 4471 Angstrom (secondary component) absorption lines yield semi-amplitudes of 133 +/- 2 and 314 +/- 2 km s(-1) for each binary component, resulting in minimum masses of 31 and 13 M-. (q = 0.42). We also confirm for the binary components the spectral classification of O3 V + O8 V previously assigned. Assuming for the O8 V component a 'normal' mass of 22-25 M-. we would derive for the primary O3 Va mass of 'only' 52-60 M-. and an inclination of about 55 degrees for the orbital plane. We have also determined for the first time a period of apsidal motion for this system, namely 185 +/- 16 yr using all available radial velocity data sets of HD 93205 (from 1975 to 1999). Phase-locked variations of the X-ray emission of HD 93205 consisting of a rise of the observed X-ray flux near periastron passage are also discussed. C1 Natl Univ La Plata, Fac Ciencias Astron & Geofis, La Plata, Argentina. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. Univ Space Res Assoc, Seabrook, MD 20706 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. IUCAA, Pune 411007, Maharashtra, India. Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada. Observ Mont Megant, Montreal, PQ H3C 3J7, Canada. RP Morrell, NI (reprint author), Natl Univ La Plata, Fac Ciencias Astron & Geofis, Paseo Bosque S-N, La Plata, Argentina. RI Barba, Rodolfo/P-4649-2014 OI Barba, Rodolfo/0000-0003-1086-1579 NR 50 TC 28 Z9 28 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 SEP 1 PY 2001 VL 326 IS 1 BP 85 EP 94 DI 10.1046/j.1365-8711.2001.04500.x PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 473BK UT WOS:000171019300011 ER PT J AU Park, S Srivastava, D Cho, KJ AF Park, S Srivastava, D Cho, KJ TI Local reactivity of fullerenes and nano-device applications SO NANOTECHNOLOGY LA English DT Article; Proceedings Paper CT 8th Foresight Conference on Molecular Nanotechnology CY NOV 03-05, 2000 CL BETHESDA, MARYLAND ID C-60; C60 AB A conceptual framework to understand the chemical reactivity of fullerenes is developed as a design tool for nano-scale device applications. The internal and external chemical reactivity of fullerenes is found to depend strongly on the curvature and local atomic structure. As examples, we study C-36, C-60 and graphite, and use a hydrogen atom to probe chemical reactivity as a function of local atomic structure. The analysis shows that the balance of strain energy and chemical binding energy determines the local reactivity. This understanding provides an insight into the use of chemically doped endo-fullerenes as suitable target material for a recently proposed design of a solid-state quantum computer. C1 Stanford Univ, Dept Chem Engn, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Computat Nanotechnol CSC NAS, Moffett Field, CA 94035 USA. Stanford Univ, Dept Mech Engn, Dept Mech & Computat, Stanford, CA 94305 USA. RP Park, S (reprint author), Stanford Univ, Dept Chem Engn, Stanford, CA 94305 USA. NR 21 TC 17 Z9 18 U1 0 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0957-4484 J9 NANOTECHNOLOGY JI Nanotechnology PD SEP PY 2001 VL 12 IS 3 BP 245 EP 249 DI 10.1088/0957-4484/12/3/308 PG 5 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied SC Science & Technology - Other Topics; Materials Science; Physics GA 480GR UT WOS:000171454100010 ER PT J AU Nguyen, CV Chao, KJ Stevens, RMD Delzeit, L Cassell, A Han, J Meyyappan, M AF Nguyen, CV Chao, KJ Stevens, RMD Delzeit, L Cassell, A Han, J Meyyappan, M TI Carbon nanotube tip probes: stability and lateral resolution in scanning probe microscopy and application to surface science in semiconductors SO NANOTECHNOLOGY LA English DT Article; Proceedings Paper CT 8th Foresight Conference on Molecular Nanotechnology CY NOV 03-05, 2000 CL BETHESDA, MARYLAND ID ATOMIC-FORCE MICROSCOPY; GROWTH AB In this paper we present results on the stability and lateral resolution capability of carbon nanotube (CNT) scanning probes as applied to atomic force microscopy (AFM). Surface topography images of ultra-thin films (2-5 nm thickness) obtained with AFM are used to illustrate the lateral resolution capability of single-walled carbon nanotube probes. Images of metal films prepared by ion beam sputtering exhibit grain sizes ranging from greater than 10 nm to as small as similar to2 mn for gold and iridium. respectively. In addition, the imaging stability and lifetime of multi-walled carbon nanotube scanning probes are studied on a relatively hard surface of silicon nitride (Si3N4). AFM images of the Si3N4 surface collected after more than 15 h of continuous scanning show no detectable degradation in lateral resolution. These results indicate the general feasibility of CNT tips and scanning probe microscopy for examining nanometre-scale surface features of deposited metals as well as non-conductive thin films. AFM coupled with CNT tips offers a simple and nondestructive technique for probing a variety of surfaces, and has immense potential as a surface characterization tool in integrated circuit manufacture. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Charles Evans & Associates, Sunnyvale, CA 94086 USA. RP Nguyen, CV (reprint author), NASA, Ames Res Ctr, MS 229-1, Moffett Field, CA 94035 USA. NR 11 TC 124 Z9 126 U1 3 U2 17 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0957-4484 J9 NANOTECHNOLOGY JI Nanotechnology PD SEP PY 2001 VL 12 IS 3 BP 363 EP 367 DI 10.1088/0957-4484/12/3/326 PG 5 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied SC Science & Technology - Other Topics; Materials Science; Physics GA 480GR UT WOS:000171454100028 ER PT J AU Srivastava, D AF Srivastava, D TI Special issue featuring selected papers from the 8th Foresight Conference on Molecular Nanotechnology (Bethesda, Maryland, USA, 3-5 November 2000) - Guest editor's introduction SO NANOTECHNOLOGY LA English DT Editorial Material C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Srivastava, D (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0957-4484 J9 NANOTECHNOLOGY JI Nanotechnology PD SEP PY 2001 VL 12 IS 3 BP U5 EP U5 PG 1 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied SC Science & Technology - Other Topics; Materials Science; Physics GA 480GR UT WOS:000171454100002 ER PT J AU Xapsos, MA Summers, GP Burke, EA Poivey, C AF Xapsos, MA Summers, GP Burke, EA Poivey, C TI Microdosimetry theory for microelectronics applications SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS LA English DT Article; Proceedings Paper CT Summer School on Advanced Topics in Radiation Dosimetry CY JUL 03-07, 2001 CL ATHENS, GREECE SP St Gobain Crystals & Detectors DE microdosimetry; ionizing radiation; dose mean lineal energy; shot noise multiplier; microelectronics; optical imager; charge-coupled device (CCD); static RAM; hard error ID LINEAR-ENERGY-TRANSFER; CHARGE COLLECTION; DOSE FLUCTUATIONS; GATE OXIDES; MOS DEVICES; DEPOSITION; IONS; DISTRIBUTIONS; SILICON; APPLICABILITY AB Although classical microdosimetry theory was originally intended for radiation biology applications, understanding the effect of ionizing radiations on small target volumes has become an important consideration in a number of research areas. In this paper we review the application of microdosimetry to radiation effects problems in microelectronics, with emphasis on large arrays of devices such as optical imagers and memories. A brief historical background of the evolution of microdosimetry theory for microelectronics is presented. An overview of some of the theory is given, with emphasis on compound Poisson process theory. An important consideration is how to evaluate the fundamental distributions that contribute to ionization fluctuations - the incident radiation linear energy transfer (LET) spectrum, the path lengths of primary charged particles in the microvolume. and the energy-loss straggling distribution. Methods of accomplishing this for microelectronics applications are discussed. The rapid evolution of microelectronics to smaller dimensions, larger arrays and new materials has presented challenges that have led to the development of approaches not found in classical microdosimetry. Two such developments are discussed. The first is a versatile and analytic approach for describing dose fluctuations induced by ions in microvolumes. It accounts for both ion (direct) events and electron (indirect) events, and is called the two component model. The second is the use of extreme value theory in conjunction with microdosimetry theory to assess the threshold dose at which a large array of devices begins to fail. (C) 2001 Elsevier Science B.V. All rights reserved. C1 USN, Res Lab, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SGT Inc, Greenbelt, MD 20771 USA. RP Xapsos, MA (reprint author), USN, Res Lab, Code 6818, Washington, DC 20375 USA. NR 74 TC 14 Z9 15 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-583X J9 NUCL INSTRUM METH B JI Nucl. Instrum. Methods Phys. Res. Sect. B-Beam Interact. Mater. Atoms PD SEP PY 2001 VL 184 IS 1-2 BP 113 EP 134 DI 10.1016/S0168-583X(01)00716-9 PG 22 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 478HN UT WOS:000171341100007 ER PT J AU Refaat, TF Elsayed-Ali, HE DeYoung, RJ AF Refaat, TF Elsayed-Ali, HE DeYoung, RJ TI Drift-diffusion model for reach-through avalanche photodiodes SO OPTICAL ENGINEERING LA English DT Article DE photodiodes; avalanche photodiode; reach-through structure; drift-diffusion model ID PPM COMMUNICATION-SYSTEMS; SILICON; RECOVERY AB A 1-D drift-diffusion model is developed for reach-through avalanche photodiodes. Based on this model an equivalent circuit is suggested for these devices. The equivalent circuit is suitable for simulating the device in circuit simulation packages such as PSpice. The model is validated by simulating an actual reach-through silicon avalanche photodiode in the steady state and the transient conditions. Some of the simulation results are compared to the manufacturer data by estimating the device parameters. This model is also used to investigate the effect of the device microstructure on its performance. For a certain operating bias voltage and wavelength, it is found that the multiplication width has a critical value for defining the device stability. The absorption width defines the wavelength for peak responsivity, which suggests a structure enhancement for IR detection. Also the effect of varying the doping concentration is studied. (C) 2001 Society of Photo-Optical Instrumentation Engineers. C1 Old Dominion Univ, Dept Elect & Comp Engn, Norfolk, VA 23508 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Refaat, TF (reprint author), Old Dominion Univ, Dept Elect & Comp Engn, 231 Kaufman Hall, Norfolk, VA 23508 USA. NR 17 TC 2 Z9 2 U1 0 U2 3 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD SEP PY 2001 VL 40 IS 9 BP 1928 EP 1935 DI 10.1117/1.1396655 PG 8 WC Optics SC Optics GA 478XK UT WOS:000171373700023 ER PT J AU Bhatia, AK Temkin, A AF Bhatia, AK Temkin, A TI Complex-correlation Kohn T-matrix method of calculating total and elastic cross sections: Electron-hydrogen elastic scattering SO PHYSICAL REVIEW A LA English DT Article ID MODEL AB We report on a study of electron-hydrogen scattering using a method [Bhatia, Schneider, and Temkin, Phys. Rev. Lett. 70, 1936 (1993)] that allows for the ab initio calculation of total and elastic cross sections at higher energies. In its general form the method uses complex-"radial" correlation functions, in a (Kohn) T-matrix formalism. The complex-correlation Kohn T-matrix method is reviewed in the context of electron-hydrogen scattering, including the derivation of the equation for the (complex) scattering function, and the extraction of the scattering information from the latter. The calculation reported here is restricted to S waves in the elastic region, where the correlation functions can be taken, without loss of generality, to be real. Phase shifts are calculated using Hylleraas-type correlation functions with up to 95 terms. Results are rigorous lower bounds; they are in general agreement with those of Schwartz [Phys. Rev. 124, 1468 (1961)], but they are more accurate and outside his error bounds at a couple of energies. C1 NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Bhatia, AK (reprint author), NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 18 TC 13 Z9 13 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD SEP PY 2001 VL 64 IS 3 AR 032709 DI 10.1103/PhysRevA.64.032709 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 472HT UT WOS:000170978600054 ER PT J AU Cerf, NJ Iblisdir, S AF Cerf, NJ Iblisdir, S TI Phase conjugation of continuous quantum variables SO PHYSICAL REVIEW A LA English DT Article ID CLONING; INFORMATION AB The phase conjugation of an unknown Gaussian state cannot be realized perfectly by any physical process. A heuristic argument is used to derive a tight lower bound on the noise that must be introduced by an approximate phase conjugation operation. A universal transformation achieving the optimal imperfect phase conjugation is then presented, which is the continuous counterpart of the universal-NOT transformation for quantum bits. In addition, it is shown that more information can be encoded into a pair of conjugate Gaussian states than by using the same state twice. C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Cerf, NJ (reprint author), Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. NR 10 TC 26 Z9 27 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD SEP PY 2001 VL 64 IS 3 AR 032307 DI 10.1103/PhysRevA.64.032307 PG 3 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 472HT UT WOS:000170978600035 ER PT J AU Chrien, NL Bruegge, CJ Gaitley, BJ AF Chrien, NL Bruegge, CJ Gaitley, BJ TI AirMISR laboratory calibration and in-flight performance results SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID INSTRUMENT DESCRIPTION; MISR AB An airborne Multi-angle Imaging SpectroRadiometer (AirMISR) instrument has been developed to assist in validation of the Earth Observing System (EOS) MISR experiment. The airborne instrument is built to the same performance specifications as MISR. Both instruments view the earth at nine discrete view angles, provide data products that are radiance scaled to Systeme International (SI) units, registered among the view angles, and geolocated. Whereas on-orbit MISR will acquire a global data set every 9 days, the aircraft version is restricted to a target size of 9 x 11 km per aircraft run. AirMISR does, however, have the advantages of offering a means to testbed new mission procedures or camera designs, provide data sets that predate the MISR launch, and a means of returning to the laboratory to update the camera calibrations. This paper provides the AirMISR laboratory calibration results. (C) 2001 Elsevier Science Inc. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chrien, NL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 306-392, Pasadena, CA 91109 USA. NR 4 TC 3 Z9 3 U1 0 U2 0 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 SEP PY 2001 VL 77 IS 3 BP 328 EP 337 DI 10.1016/S0034-4257(01)00212-7 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 470BK UT WOS:000170850400007 ER PT J AU Abdou, WA Conel, JE Pilorz, SH Helmlinger, MC Bruegge, CJ Gaitley, BJ Ledeboer, WC Martonchik, JV AF Abdou, WA Conel, JE Pilorz, SH Helmlinger, MC Bruegge, CJ Gaitley, BJ Ledeboer, WC Martonchik, JV TI Vicarious calibration - A reflectance-based experiment with AirMISR SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID INSTRUMENT DESCRIPTION; SPECTRORADIOMETER AB A vicarious reflectance-based calibration experiment for the Multiangle Imaging SpectroRadiometer (MISR) airborne simulator, AirMISR, is described as one precursor experiment of this type planned for postlaunch application to MISR itself The experiment produces a set of multiangle near-top-of-atmosphere radiances that are compared with the multiangle AirMISR radiances, established using a laboratory calibration. The field and aircraft data were collected as part of an engineering test flight at Moffett Field, CA, on November 5, 1997. A concrete tarmac was used as the field target. Atmospheric optical depth data were collected adjacent to the target throughout the actual overflight period using a single Reagan solar radiometer. For logistical reasons, the surface hemispherical directional reflectance factor (HDRF) was determined 7 days later using the Portable Apparatus for Rapid Acquisition of Bidirectional Observation of the Land and Atmosphere III (PARABOLA III), along with the areally averaged spectral HDRF at normal incidence, obtained with an Analytical Spectral Devices (ASD) FieldSpec moderate resolution field spectrometer. AirMISR overflew the target under clear sky conditions though the aerosol turbidity was high (similar to 0.3 at 550 nm). Good to fair agreement has been obtained at all angles and wavelengths between the top-of-atmosphere (TOA) radiances calculated for the measured atmospheric and surface conditions and the radiances incident at AirMISR as determined from the laboratory calibration. Some systematic disagreements are present. The largest disagreements (similar to 15% in the blue) are found at the highest view angles and the smallest at nadir viewing (<5%). Possible explanations for the differences in radiances at large view angles are discussed. (C) 2001 Elsevier Science Inc. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Abdou, WA (reprint author), CALTECH, Jet Prop Lab, MS 169-237,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 13 Z9 13 U1 1 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 SEP PY 2001 VL 77 IS 3 BP 338 EP 353 DI 10.1016/S0034-4257(01)00213-9 PG 16 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 470BK UT WOS:000170850400008 ER PT J AU Bruegge, C Chrien, N Haner, D AF Bruegge, C Chrien, N Haner, D TI A spectralon BRF data base for MISR calibration applications SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID IMAGING SPECTRORADIOMETER MISR; EARTH-ORBITING SENSORS; IN-FLIGHT CALIBRATION; BIDIRECTIONAL REFLECTANCE; PANELS AB The Multi-angle Imaging SpectroRadiometer (MISR) is an Earth-observing sensor, which provides global retrievals of aerosols, clouds, and land surface parameters. Instrument specifications require an accurate absolute calibration, as well as accurate camera-to-camera, band-to-band and pixel-to-pixel relative response determinations. In order to achieve these requirements, MISR makes use of an on-board calibrator (OBC), as well as vicarious calibration (VC) experiments. The OBC makes use of two Spectralon diffuse panels in order to provide a flatfield illumination. Bi-monthly deployments of these panels into the camera fields-of-view will be made. At these times, solar-reflected radiance values are measured by photodiode detector standards. Accurate relative bidirectional reflectance factor (BRF) data are required to transfer these photodiode-measured radiances into camera-incident values. An independent calibration pathway, known as VC, will also be implemented in order to reduce systematic errors and to provide a crosscheck on the OBC findings. Here, the top-of-atmosphere radiances are computed from in situ observations of surface reflectance and atmospheric transmittances, Key to these measurements is knowledge of the hemispheric/directional reflectance factor (HDRF) of the field reflectance standards. This report describes the BRF measurements of the MISR flight panels, and provides an estimation as to the differences between HDRF and BRF for the MISR view angles. This BRF data base is available from the MISR web site, http://www-misr.jpl.nasa.gov. (C) 2001 Published by Elsevier Science Inc. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bruegge, C (reprint author), CALTECH, Jet Prop Lab, MS 169-237,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 17 Z9 17 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD SEP PY 2001 VL 77 IS 3 BP 354 EP 366 DI 10.1016/S0034-4257(01)00214-0 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 470BK UT WOS:000170850400009 ER PT J AU Brown, SW Johnson, BC Yoon, HW Butler, JJ Barnes, RA Biggar, S Spyak, P Thome, K Zalewski, E Helmlinger, M Bruegge, C Schiller, S Fedosejevs, G Gauthier, R Tsuchida, S Machida, S AF Brown, SW Johnson, BC Yoon, HW Butler, JJ Barnes, RA Biggar, S Spyak, P Thome, K Zalewski, E Helmlinger, M Bruegge, C Schiller, S Fedosejevs, G Gauthier, R Tsuchida, S Machida, S TI Radiometric characterization of field radiometers in support of the 1997 Lunar Lake, Nevada, experiment to determine surface reflectance and top-of-atmosphere radiance SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID CALIBRATION AB A continuing series of field campaigns to Lunar Lake, Nevada, has been established to develop measurement protocols and assess the uncertainties of ground-based calibrations of on-orbit satellite sensors. In June 1997, an ensemble of field radiometers was deployed to validate the fundamental reflectance and radiance measurements of the Land Satellite (Landsat-5) Thematic Mapper (TM) and Satellite Pour l'Observation de la Terre (SPOT-2) Haute Resolution Visible (HRV) satellite instruments. Prior their deployment to Lunar Lake, many of the field instruments measured a common sphere source at the University of Arizona (UA). The results, presented in this work, showed variations in the relative stabilities of the field instruments, and demonstrate the need for in-depth characterization of field instruments for an accurate assessment of instrument performance and measurement uncertainty. (C) 2001 Published by Elsevier Science Inc. C1 Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Gen Sci Corp, SAIC, Laurel, MD USA. Univ Arizona, Tucson, AZ USA. CALTECH, Jet Prop Lab, NASA, Pasadena, CA USA. S Dakota State Univ, Brookings, SD 57007 USA. Canada Ctr Remote Sensing, Ottawa, ON K1A OY7, Canada. Geol Survey Japan, Tsukuba, Ibaraki 305, Japan. Earth Remote Sensing Data Anal Ctr, Tokyo, Japan. RP Brown, SW (reprint author), Natl Inst Stand & Technol, 100 Bur Dr,Stop 8442, Gaithersburg, MD 20899 USA. RI Thome, Kurtis/D-7251-2012; Butler, James/D-4188-2013 NR 9 TC 9 Z9 9 U1 1 U2 1 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 SEP PY 2001 VL 77 IS 3 BP 367 EP 376 DI 10.1016/S0034-4257(01)00215-2 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 470BK UT WOS:000170850400010 ER PT J AU Liu, TS Finley, TD AF Liu, TS Finley, TD TI Estimating bias error distributions SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB In this article we formulate a general methodology for estimating the bias error distribution of a device in a measurement domain from less accurate measurements when a minimal number of standard values (typically no more than two values) are available. A new perspective is that the bias error distribution can be found as a solution of an intrinsic functional equation in a domain. Based on this theory, the scaling- and translation-based methods for determining the bias error distribution are developed. These methods are applicable to virtually any device as long as the bias error distribution of the device can be sufficiently described by a power series (a polynomial) or a Fourier series in a domain. These methods were validated through computational simulations and laboratory calibration experiments for a number of different devices. C1 NASA, Model Syst Branch, Langley Res Ctr, Hampton, VA 23681 USA. RP Liu, TS (reprint author), NASA, Model Syst Branch, Langley Res Ctr, MS 238, Hampton, VA 23681 USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD SEP PY 2001 VL 72 IS 9 BP 3561 EP 3571 DI 10.1063/1.1394188 PG 11 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 466LV UT WOS:000170647800012 ER PT J AU Rhim, WK Ishikawa, T AF Rhim, WK Ishikawa, T TI Noncontact surface tension measurement by drop rotation SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID LIQUID-DROPS AB Validity of the surface tension measurement technique that was proposed by Elleman was experimentally verified. The technique was based on Brown and Scriven's work on the shape evolution of rotating drops. Molten tin and aluminum drops were levitated in high vacuum by the electrostatic levitator and rotated by applying a rotating magnetic field. This technique offers an alternative technique for those liquids where the drop oscillation technique cannot be used. As a demonstration, the technique was applied to a glass-forming alloy (Zr41.2Ti13.8Cu12.5Ni10.0Be22.5) and its surface tension was measured down to the lower temperature where the drop oscillation technique could not be applied due to its high viscosity. (C) 2001 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Rhim, WK (reprint author), CALTECH, Dept Mat Sci, M-S 138-78, Pasadena, CA 91125 USA. NR 10 TC 15 Z9 17 U1 1 U2 6 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD SEP PY 2001 VL 72 IS 9 BP 3572 EP 3575 DI 10.1063/1.1388215 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 466LV UT WOS:000170647800013 ER PT J AU Welander, PB Hahn, I AF Welander, PB Hahn, I TI Miniature high-resolution thermometer for low-temperature applications SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID CONFINED HELIUM; HEAT-CAPACITY; LAMBDA-POINT; 2 K AB We report on a new miniature, high-resolution, susceptibility thermometer that employs LaxGd1-xCl3 as the paramagnetic material for temperature measurement below 4 K. The thermometer utilizes small permanent disk magnets to provide the required magnetic field, and has a total mass of only 2 g. The thermometer shows a resolution of 0.2 nK in a 1 Hz bandwidth and an absolute drift rate less than 50 fK/s at 2.2 K. In this article, we describe the thermometer design, assembly procedure, and experimental test results, including its thermal time constant and susceptibility to external magnetic fields. (C) 2001 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Welander, PB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 17 TC 12 Z9 13 U1 2 U2 4 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD SEP PY 2001 VL 72 IS 9 BP 3600 EP 3604 DI 10.1063/1.1396663 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 466LV UT WOS:000170647800018 ER PT J AU Yungster, S Radhakrishnan, K AF Yungster, S Radhakrishnan, K TI Simulation of unsteady hypersonic combustion around projectiles in an expansion tube SO SHOCK WAVES LA English DT Article DE oblique detonation wave; chemically reacting flow; TVD and BDF numerical schemes ID REACTING FLOW ESTABLISHMENT; SHOCK-INDUCED COMBUSTION; RAM ACCELERATOR; BOUNDARY-LAYER AB The temporal evolution of combustion flowfields established by the interaction between wedge-shaped bodies and explosive hydrogen-oxygen-nitrogen mixtures accelerated to hypersonic speeds in an expansion tube is investigated. The analysis is carried out using a fully implicit, time-accurate, computational fluid dynamics code that we recently developed to solve the Navier-Stokes equations for a chemically reacting gas mixture. The numerical results are compared with experimental data from the Stanford University expansion tube for two different gas mixtures at Mach numbers of 4.2 and 5.2. The experimental work showed that flow unstart occurred for both the Mach 4.2 cases, These results are reproduced by our numerical simulations and, more significantly, the causes for unstart are explained. For the Mach 5.2 mixtures, the experiments and numerical simulations both produced stable combustion. However, the computations indicate that in one case the experimental data were obtained during the transient phase of the flow; that is, before steady state had been attained. C1 NASA, Glenn Res Ctr, Inst Computat Mech Prop, Cleveland, OH 44135 USA. RP NASA, Glenn Res Ctr, Inst Computat Mech Prop, MS 86-6, Cleveland, OH 44135 USA. EM s.Yungster@grc.nasa.gov NR 26 TC 2 Z9 3 U1 0 U2 2 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0938-1287 EI 1432-2153 J9 SHOCK WAVES JI Shock Waves PD SEP PY 2001 VL 11 IS 3 BP 167 EP 177 DI 10.1007/PL00004073 PG 11 WC Mechanics SC Mechanics GA 483EK UT WOS:000171620600002 ER PT J AU Plassman, GE Sobieszczanski-Sobieski, J AF Plassman, GE Sobieszczanski-Sobieski, J TI Experience with a genetic algorithm implemented on a multiprocessor computer SO STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION LA English DT Article; Proceedings Paper CT AIAA/NASA/USAF/ISSMO 8th Symposium on Multidisciplinary Analysis and Optimization CY SEP 06-08, 2000 CL LONG BEACH, CALIFORNIA SP Amer Inst Aeronaut & Astronaut, NASA, USAF, ISSMO DE Genetic Algorithm; multiprocessor AB Numerical experiments were conducted to find out the extent to which a Genetic Algorithm (GA) may benefit from a multiprocessor implementation, considering, on one hand, that analyses of individual designs in a population are independent of each other so that they may be executed concurrently on separate processors, and, on the other hand, that there are some operations in a GA that cannot be so distributed. The algorithm experimented with was based on a gaussian distribution rather than bit exchange in the GA reproductive mechanism, and the test case was a hub frame structure of up to 1080 design variables. The experimentation engaging up to 128 processors confirmed expectations of radical elapsed time reductions comparing to a conventional single processor implementation. It also demonstrated that the time spent in the nondistributable parts of the algorithm and the attendant crossprocessor communication may have a very detrimental effect on the efficient utilization of the multiprocessor machine and on the number of processors that can be used effectively in a concurrent manner. Three techniques were devised and tested to mitigate that effect, resulting in efficiency increasing to exceed 99 percent. Of particular interest to, the user, corresponding elapsed time compression factors approaching 128 are realized on 128 processors. C1 Comp Sci Corp, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Plassman, GE (reprint author), Comp Sci Corp, 3217 N Armistead Ave, Hampton, VA 23666 USA. NR 6 TC 0 Z9 0 U1 0 U2 2 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1615-147X J9 STRUCT MULTIDISCIP O JI Struct. Multidiscip. Optim. PD SEP PY 2001 VL 22 IS 2 BP 102 EP 115 PG 14 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary; Mechanics SC Computer Science; Engineering; Mechanics GA 478FD UT WOS:000171331500002 ER PT J AU Ricca, A Bauschlicher, CW AF Ricca, A Bauschlicher, CW TI A correlation-consistent basis set for Fe SO THEORETICAL CHEMISTRY ACCOUNTS LA English DT Article DE basis set; correlation-consistent; FeCO bond energies ID GAUSSIAN-BASIS SETS; COUPLED-CLUSTER THEORY; MOLECULAR CALCULATIONS; ELECTRON CORRELATION; EXCITATION-ENERGIES; TRANSITION-METALS; WAVE-FUNCTIONS; HARTREE-FOCK; ATOMS; SPECTROSCOPY AB A series of correlation-consistent basis sets are developed for Fe. Our best computed F-5-D-5 separation in the Fe atom is in excellent agreement with experiment. Our best estimate for the FeCO D-0 value is in good agreement with experiment. The 5 Sigma (-)-3 Sigma (-) separation in FeCO has an error of 3.6 kcal/mol; while the origin of this error is not clear, it is probably not due to the basis set. C1 NASA, Ames Res Ctr, ELORET Corp, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Space Technol Div, 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 32 TC 30 Z9 30 U1 0 U2 2 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1432-881X J9 THEOR CHEM ACC JI Theor. Chem. Acc. PD SEP PY 2001 VL 106 IS 4 BP 314 EP 318 DI 10.1007/s002140100279 PG 5 WC Chemistry, Physical SC Chemistry GA 476PY UT WOS:000171239000011 ER PT J AU Mestre, DR Masson, GS Stone, LS AF Mestre, DR Masson, GS Stone, LS TI Spatial scale of motion segmentation from speed cues SO VISION RESEARCH LA English DT Article DE motion perception; speed segmentation; speed discrimination; transparency; spatial scale; area V1; area MT ID KINETICALLY DEFINED BOUNDARIES; TRANSPARENT MOTION; MACAQUE MONKEY; AREA MT; CONTRAST SENSITIVITY; MAGNIFICATION FACTOR; DOT PATTERNS; PERCEPTION; V1; DISCRIMINATION AB For the accurate perception of multiple, potentially overlapping, surfaces or objects, the visual system must distinguish different local motion vectors and selectively integrate similar motion vectors over space to segment the retinal image properly. We recently showed that large differences in speed are required to yield a percept of motion transparency. In the present study. to investigate the spatial scale of motion segmentation from speed cues alone, we measured the speed-segmentation threshold (the minimum speed difference required for 75% performance accuracy) for 'corrugated' random-dot patterns, i.e. patterns in which dots with two different speeds were alternately placed in adjacent bars of variable width. In a first experiment, we found that, at large bar widths, a smaller speed difference was required to segment and perceive the corrugated pattern of moving dots, while at small bar-widths, a larger speed difference was required to segment the two speeds and perceive two transparent surfaces of moving dots. Both the perceptual and segmentation performance transitions occurred at a bar width of around 0.4 degrees. In a second experiment, speed-segmentation thresholds were found to increase sharply when dots with different speeds were paired within a local pooling area. The critical pairing distance was about 0.2 degrees in the fovea and increased linearly with stimulus eccentricity. However, across the range of eccentricities tested (up to 15 degrees), the critical pairing distance did not change much and remained close to the receptive field size of neurons within the primate primary visual cortex. In a third experiment, increasing dot density changed the relationship between speed-segmentation thresholds and bar width. Thresholds decreased for large bar widths, but increased for small bar widths. All of these results are well fit by a simple stochastic model, which estimates the probabilities of having identical or different motion vectors within a local pooling area whose size is the same as that of primate V1 neurons. Altogether, these results demonstrate that speed-based segmentation can function well, even at small spatial scales (i.e. high-spatial frequencies of spatial corrugation) and thereby emphasizes the critical role of a local pooling process early in the cortical motion-processing pathway. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 CNRS, Ctr Rech Neurosci Cognit, UPR 9012, F-13402 Marseille 20, France. NASA, Ames Res Ctr, Human Informat Proc Res Branch, Human Factors Res & Technol Div, Moffett Field, CA 94035 USA. RP Masson, GS (reprint author), CNRS, Ctr Rech Neurosci Cognit, UPR 9012, 31 Chemin Joseph Aiguier, F-13402 Marseille 20, France. RI Mestre, Daniel/J-9526-2015; MASSON, Guillaume/G-4615-2012 OI Mestre, Daniel/0000-0002-0399-4747; NR 47 TC 17 Z9 17 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0042-6989 J9 VISION RES JI Vision Res. PD SEP PY 2001 VL 41 IS 21 BP 2697 EP 2713 DI 10.1016/S0042-6989(01)00162-6 PG 17 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA 485YQ UT WOS:000171791400002 PM 11587721 ER PT J AU Reichle, RH Entekhabi, D McLaughlin, DB AF Reichle, RH Entekhabi, D McLaughlin, DB TI Downscaling of radio brightness measurements for soil moisture estimation: A four-dimensional variational data assimilation approach SO WATER RESOURCES RESEARCH LA English DT Article ID TEMPERATURE; RADIOBRIGHTNESS; MODEL AB This paper investigates the feasibility of estimating large-scale soil moisture profiles and related land surface variables from 1.4 GHz (L-band) passive microwave measurements, using variational data assimilation. Our four-dimensional assimilation algorithm takes into account both model and measurement uncertainties and provides dynamically consistent interpolation and extrapolation of remote sensing data over space and time. The land surface hydrologic model which forms the heart of the variational algorithm was expressly designed for data assimilation purposes. This model captures key physical processes while remaining computationally efficient. We test our algorithm with a series of synthetic experiments based on the Southern Great Plains 1997 Hydrology Experiment. These experiments provide insights about three issues that are crucial to the design of an operational soil moisture assimilation system. Our first synthetic experiment shows that soil moisture can be satisfactorily estimated at scales finer than the resolution of the brightness images. This downscaling experiment indicates that brightness images with a resolution of tens of kilometers can yield soil moisture profile estimates on a scale of a few kilometers, provided that micrometeorological, soil texture, and land cover inputs are available at the finer scale. In our second synthetic experiment we show that adequate soil moisture estimates can be obtained even if quantitative precipitation data are not available. Model error terms estimated from radio brightness measurements are able to account in an aggregate way for the effects of precipitation events. In our third experiment we show that reductions in estimation performance resulting from a decrease in the length of the assimilation time interval are offset by a substantial improvement in computational efficiency. C1 MIT, Dept Civil & Environm Engn, Ralph M Parsons Lab, Cambridge, MA 02139 USA. RP Reichle, RH (reprint author), NASA, Goddard Space Flight Ctr, Code 974, Greenbelt, MD 20771 USA. RI Reichle, Rolf/E-1419-2012 NR 25 TC 100 Z9 112 U1 3 U2 19 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0043-1397 J9 WATER RESOUR RES JI Water Resour. Res. PD SEP PY 2001 VL 37 IS 9 BP 2353 EP 2364 DI 10.1029/2001WR000475 PG 12 WC Environmental Sciences; Limnology; Water Resources SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Water Resources GA 466AV UT WOS:000170622900007 ER PT J AU Rozas, LP Minello, TJ AF Rozas, LP Minello, TJ TI Marsh terracing as a wetland restoration tool for creating fishery habitat SO WETLANDS LA English DT Article DE fishery species; Gulf of Mexico; habitat comparisons; habitat selection; nursery areas; penaeid shrimps; tidal marsh; restoration ID SALT-MARSH; PENAEUS-AZTECUS; GALVESTON BAY; BROWN SHRIMP; NEKTON USE; DECAPOD CRUSTACEANS; NATANT MACROFAUNA; AQUATIC HABITATS; PREDATION RATES; TEXAS USA AB Terracing is a relatively new wetland-restoration technique used to convert shallow subtidal bottom to marsh. This method uses existing bottom sediments to form terraces or ridges at marsh elevation. A terrace field is constructed by arranging these ridges in some pattern that maximizes intertidal edge and minimizes fetch between ridges; the intertidal area is planted with marsh vegetation. We examined the habitat value of terracing for fishery species at Sabine National Wildlife Refuge, Louisiana (USA) in spring and fall 1999 by quantifying and comparing nekton densities in a 9-yr-old terrace field and nearby reference area using a 1-m(2) drop sampler. Decapod crustaceans were more abundant than fishes, composing 62% and 95% of all organisms we collected in spring and fall, respectively. White shrimp Litopenaeus setiferus, daggerblade grass shrimp Palaemonetes pugio, blue crab Callinectes sapidus, and brown shrimp Farfantepenaeus aztecus accounted for 94% of all crustaceans, whereas 60% of all fishes were gulf menhaden Brevoortia patronus. Mean densities of white shrimp (fall), daggerblade grass shrimp, blue crab, and brown shrimp (spring) were significantly greater in terrace marsh than on non-vegetated bottom in the reference pond. Densities of most nekton on non-vegetated bottom were similar in the terrace field and the reference pond, but gulf menhaden and white shrimp had higher densities at terrace pond sites and brown shrimp (spring) were more abundant at reference pond sites. The pattern for biomass was similar to that for density in that the mean biomass of most species was significantly greater at terrace marsh sites than reference pond sites and similar at terrace and reference pond sites. Terrace marsh, however, was not functionally equivalent to natural marsh, as mean densities of daggerblade grass shrimp (fall), brown shrimp (spring), and blue crab and mean biomass of white shrimp (fall), striped mullet Mugil cephalus (spring), and spotted seatrout Cynoscion nebulosus (fall) were greater at reference marsh sites than terrace marsh sites. Using these density and biomass patterns and the percentage of marsh and pond area in the terrace field, we concluded that terrace fields support higher standing crops of most fishery species compared with shallow marsh ponds of similar size. Future restoration projects could include design changes to increase the proportion of marsh in a terrace field and enhance the habitat value of marsh terraces for fishery species. C1 SE Fisheries Sci Ctr, NOAA, Natl Marine Fisheries Serv, Galveston, TX 77551 USA. RP Rozas, LP (reprint author), SE Fisheries Sci Ctr, NOAA, Natl Marine Fisheries Serv, 4700 Ave U, Galveston, TX 77551 USA. NR 45 TC 28 Z9 29 U1 4 U2 25 PU SOC WETLAND SCIENTISTS PI LAWRENCE PA 810 E TENTH ST, P O BOX 1897, LAWRENCE, KS 66044 USA SN 0277-5212 J9 WETLANDS JI Wetlands PD SEP PY 2001 VL 21 IS 3 BP 327 EP 341 DI 10.1672/0277-5212(2001)021[0327:MTAAWR]2.0.CO;2 PG 15 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA 477KB UT WOS:000171281800002 ER PT J AU Ebisawa, K Maeda, Y Kaneda, H Yamauchi, S AF Ebisawa, K Maeda, Y Kaneda, H Yamauchi, S TI Origin of the hard X-ray emission from the galactic plane SO SCIENCE LA English DT Article ID SUPERNOVA-REMNANTS; RIDGE; ASCA; EXOSAT; LINE AB The Galactic plane is a strong emitter of hard x-rays (2 to 10 kiloelectron volts), and the emission forms a narrow continuous ridge. The currently known hard x-ray sources are far too few to explain the ridge x-ray emission, and the fundamental question of whether the ridge emission is ultimately resolved into numerous dimmer discrete sources or truly diffuse emission has not yet been settled. In order to obtain a decisive answer, using the Chandra X-ray Observatory, we carried out the deepest hard x-ray survey of a Galactic plane region that is devoid of known x-ray point sources. We detected at least 36 new hard x-ray point sources in addition to strong diffuse emission within a 17' by 17' field of view. The surface density of the point sources is comparable to that at high Galactic latitudes after the effects of Galactic absorption are considered. Therefore, most of these point sources are probably extragalactic, presumably active galaxies seen through the Galactic disk. The Galactic ridge hard x-ray emission is diffuse, which indicates omnipresence within the Galactic plane of a hot plasma, the energy density of which is more than one order of magnitude higher than any other substance in the interstellar space. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Seabrook, MD 20706 USA. Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. Iwate Univ, Fac Humanities & Social Sci, Morioka, Iwate 0208550, Japan. RP Ebisawa, K (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 20 TC 74 Z9 74 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 AUG 31 PY 2001 VL 293 IS 5535 BP 1633 EP 1635 DI 10.1126/science.1063529 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 469FA UT WOS:000170802900055 PM 11498545 ER PT J AU Ma, Z Mohammadi, S Bhattacharya, P Katehi, LPB Alterovitz, SA Ponchak, GE Strohm, KM Luy, JF AF Ma, Z Mohammadi, S Bhattacharya, P Katehi, LPB Alterovitz, SA Ponchak, GE Strohm, KM Luy, JF TI Ku-band (12.6GHz) SiGe/Si high-power heterojunction bipolar transistors SO ELECTRONICS LETTERS LA English DT Article AB Large-area multifinger Si0 7Ge0 3/Si heterojunction bipolar transistors for high-power and high-frequency operation have been designed. fabricated and characterised. For a nine-emitter finger device, an f(max) of 100GRz was achieved with a maximum available gain of 14dB. ne peak power-added efficiency in the Ku-band (12.6GHz) in the common-base configuration for a 15-emitter finger device was 23% with associated power gain of 7.4 dB and an output power of 22 dBm under class AB operation. The device delivered a maximum output power of 24.4 dBm under the same matching conditions. C1 Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Daimler Chrysler Res Ctr, Ulm, Germany. RP Ma, Z (reprint author), Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. NR 5 TC 5 Z9 6 U1 0 U2 1 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD SG1 2AY, ENGLAND SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD AUG 30 PY 2001 VL 37 IS 18 BP 1140 EP 1142 DI 10.1049/el:20010770 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA 472NC UT WOS:000170989500028 ER PT J AU Sokolik, IN Winker, DM Bergametti, G Gillette, DA Carmichael, G Kaufman, YJ Gomes, L Schuetz, L Penner, JE AF Sokolik, IN Winker, DM Bergametti, G Gillette, DA Carmichael, G Kaufman, YJ Gomes, L Schuetz, L Penner, JE TI Introduction to special section: Outstanding problems in quantifying the radiative impacts of mineral dust SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AEROSOL OPTICAL-PROPERTIES; TROPOSPHERIC AEROSOL; LIGHT-ABSORPTION; LAND SURFACES; SAHARAN DUST; WATER-VAPOR; SATELLITE; POLARIZATION; RETRIEVAL; SPACE AB This paper provides an introduction to the special section of the Journal of Geophysical Research on mineral dust. We briefly review the current experimental and theoretical approaches used to quantify the dust radiative impacts, highlight the outstanding issues, and discuss possible strategies to overcome the emerging problems. We also introduce the contributing papers of this special section. Despite the recent notable advances in dust studies, we demonstrate that the radiative effects of dust remain poorly quantified due to both limited data and incomplete understanding of relative physical and chemical processes. The foremost needs are (1) to quantify the spatial and temporal variations of dust burden in the atmosphere and develop a predictive capability for the size- and composition-resolved dust particle distribution; (2) to develop a quantitative description of the processes that control the spatial and temporal variabilities of dust physical and chemical properties and radiative effects; (3) to develop new instrumentation (especially to measure the dust particle size distribution in a wide range from about 0.01 mum to 100 tm, scattering phase function and light absorption by dust particles); and (4) to develop new techniques for interpreting and merging the diverse information from satellite remote sensing, in situ and ground-based measurements, laboratory studies, and model simulations. Because dust distribution and effects are heterogeneous, both spatially and temporally, a promising strategy to advance our knowledge is to perform comprehensive studies at the targeted regions affected by mineral dust of both natural and anthropogenic origin. C1 Univ Colorado, Boulder, CO 80309 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Paris 12, Paris, France. NOAA, ARL, Res Triangle Pk, NC 27615 USA. Univ Iowa, Iowa City, IA 52240 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johannes Gutenberg Univ Mainz, D-55099 Mainz, Germany. Univ Michigan, Ann Arbor, MI 48109 USA. RP Sokolik, IN (reprint author), Univ Colorado, Boulder, CO 80309 USA. EM sokolik@lasp.colorado.edu; d.m.winker@larc.nasa.gov; ebergametti@lisa.univ-paris12.fr; GILLETTE.DALE@epamail.epa.gov; gcarmich@engineering.uiowa.edu; kaufman@climate.gsfe.nasa.gov; gomes@lisa.univ-paris12.fr; schuetz@mail.uni-mainz.de; penner@umich.edu RI Penner, Joyce/J-1719-2012 NR 59 TC 292 Z9 312 U1 0 U2 15 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2001 VL 106 IS D16 BP 18015 EP 18027 DI 10.1029/2000JD900498 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 465FR UT WOS:000170579400025 ER PT J AU Perlwitz, J Tegen, I Miller, RL AF Perlwitz, J Tegen, I Miller, RL TI Interactive soil dust aerosol model in the GISS GCM 1. Sensitivity of the soil dust cycle to radiative properties of soil dust aerosols SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; MINERAL DUST; OPTICAL-THICKNESS; SIZE DISTRIBUTION; CLIMATE-CHANGE; DESERT DUST; SURFACE; SIMULATIONS; TROPOSPHERE; DISTRIBUTIONS AB The sensitivity of the soil dust aerosol cycle to radiative forcing by the soil dust aerosol particles themselves is studied. Four experiments with the NASA GISS atmospheric general circulation model, which includes a soil dust aerosol model, are compared, all using a prescribed climatological sea surface temperature as a lower boundary condition. In one experiment, dust is included as a dynamic tracer with no radiative effect, whereas dust interacts with radiation in the other simulations. The single-scattering albedo of dust particles is prescribed to be globally uniform in the experiments with radiatively active dust, although this albedo is varied from experiment to experiment. On a global scale the radiative forcing by dust generally causes a reduction in the atmospheric dust load, corresponding to a decreased dust source flux. The dust source flux and its changes are analyzed in more detail for the main source regions. This analysis shows that the reduction varies both with the season and with the single-scattering albedo of the dust particles. The experiments show that dust radiative forcing can lead to significant changes both in the soil dust cycle and in the climate state. To estimate dust concentration and radiative forcing by dust more accurately, dust size distributions and dust single-scattering albedo in the model should be a function of the source region, because dust concentration and the climate response to dust radiative forcing are sensitive to dust radiative parameters. C1 Columbia Univ, Dept Appl Phys & Appl Math, NASA GISS, New York, NY 10025 USA. Max Planck Inst Biochem, D-07745 Jena, Germany. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Perlwitz, J (reprint author), Columbia Univ, Dept Appl Phys & Appl Math, NASA GISS, 2880 Broadway, New York, NY 10025 USA. EM jperlwitz@giss.nasa.gov; itegen@bgc-jena.mpg.de; rmiller@giss.nasa.gov RI Miller, Ron/E-1902-2012 NR 50 TC 82 Z9 89 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2001 VL 106 IS D16 BP 18167 EP 18192 DI 10.1029/2000JD900668 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 465FR UT WOS:000170579400037 ER PT J AU Tanre, D Kaufman, YJ Holben, BN Chatenet, B Karnieli, A Lavenu, F Blarel, L Dubovik, O Remer, LA Smirnov, A AF Tanre, D Kaufman, YJ Holben, BN Chatenet, B Karnieli, A Lavenu, F Blarel, L Dubovik, O Remer, LA Smirnov, A TI Climatology of dust aerosol size distribution and optical properties derived from remotely sensed data in the solar spectrum SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SKY BRIGHTNESS MEASUREMENTS; AIRBORNE MINERAL AEROSOLS; TROPICAL NORTH-ATLANTIC; ECLATS FIELD EXPERIMENT; SCALE AIR-POLLUTION; SAHARAN DUST; RADIATIVE CHARACTERISTICS; SATELLITE MEASUREMENTS; TROPOSPHERIC AEROSOLS; LIGHT-SCATTERING AB Simultaneous spectral remote observations of dust properties from space and from the ground create a powerful tool for the determination of ambient dust properties integrated on the entire atmospheric column. The two measurement methods have a complementary sensitivity to variety of dust properties. The methodology is demonstrated using spectral measurements (0.47-2.21 mum) from Landsat (TM) over the bright Senegalian coast and dark ocean, and Aerosol Robotic Network (AERONET) radiances measured in several locations. We derive (1) the dust size distribution, showing a dominant coarse mode at 1-5 mum and a secondary mode around 0.5 mum effective radius; (2) dust absorption, which is found to be substantially smaller than reported from previous measurements; (3) the real part of the refractive index which varies within the range 1.53-1.46; and we show that (4) the effect of the dust nonspherical shape on its optical properties is not significant for scattering angles < 120 degrees. C1 Univ Sci & Technol Lille, Opt Atmospher Lab, CNRS, F-59655 Villeneuve Dascq, France. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. Univ Paris 07, Lab Interuniv Syst Atmospher, CNRS, F-94010 Creteil, France. Univ Paris 12, Lab Interuniv Syst Atmospher, CNRS, F-94010 Creteil, France. Ben Gurion Univ Negev, Jacob Blaustein Inst Desert Res, IL-84993 Sede Boqer, Israel. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. CESBIO CNES, F-31401 Toulouse, France. RP Tanre, D (reprint author), Univ Sci & Technol Lille, Opt Atmospher Lab, CNRS, F-59655 Villeneuve Dascq, France. EM tanre@loa.univ-lille1.fr RI Dubovik, Oleg/A-8235-2009; Smirnov, Alexander/C-2121-2009 OI Dubovik, Oleg/0000-0003-3482-6460; Smirnov, Alexander/0000-0002-8208-1304 NR 63 TC 125 Z9 140 U1 3 U2 15 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2001 VL 106 IS D16 BP 18205 EP 18217 DI 10.1029/2000JD900663 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 465FR UT WOS:000170579400039 ER PT J AU Kahn, R Banerjee, P McDonald, D AF Kahn, R Banerjee, P McDonald, D TI Sensitivity of multiangle imaging to natural mixtures of aerosols over ocean SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GLOBAL 3-DIMENSIONAL MODEL; TROPOSPHERIC AEROSOLS; ANTHROPOGENIC AEROSOLS; INSTRUMENT DESCRIPTION; LIGHT-SCATTERING; AVHRR DATA; RETRIEVAL; RADIANCES; SATELLITE; PRODUCT AB Multiangle remote sensing data can discriminate among aerosol air mass types, as represented by climatologically probable, external mixtures of component particles. Retrievals are performed over a comparison space of four-component mixtures, selected from six commonly observed components having assumed, fixed microphysical properties but with mixing ratios free to vary from 0% to 100%. We refer to this approach, which assumes climatologically probable component particles and derives aerosol mixtures from the observations, as a "climatological retrieval." On the basis of simulated Multiangle Imaging Spectroradiometer (MISR) observations over dark water, the retrieval can distinguish mixtures containing large, spherical particles (sea salt), nonspherical particles (accumulation and coarse mode dust), and small, dark particles (black carbon) to within 20% or better of each component's true mixing ratio. This is sufficient to distinguish maritime from continental aerosol air masses. The retrievals, which use all nine MISR angles and the two wavelengths least affected by ocean surface reflectance (672 and 867 nm), are not good at distinguishing medium, spherical, nonabsorbing (sulfate) from medium, spherical, absorbing (carbonaceous') particles. However, the sum is retrieved to within 20% of the true mixing ratio or better. This is significantly more detail about the properties of particle mixtures than has previously been retrieved from satellite data, and in all cases, the derived total column aerosol optical depth remains well constrained, to at least 0.05 or 20%, whichever is larger. We expect the MISR data, with its frequent global coverage, to complement in situ and field data, which can provide greater detail about aerosol size and composition locally. This combined effort should advance our knowledge of aerosol behavior globally and our ability to model the impact of aerosols on the climatically important solar radiation budget. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kahn, R (reprint author), CALTECH, Jet Prop Lab, MS 169-237,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM ralph.kahn@jpl.nasa.gov RI Kahn, Ralph/D-5371-2012 OI Kahn, Ralph/0000-0002-5234-6359 NR 46 TC 119 Z9 120 U1 1 U2 16 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2001 VL 106 IS D16 BP 18219 EP 18238 DI 10.1029/2000JD900497 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 465FR UT WOS:000170579400040 ER PT J AU Cakmur, RV Miller, RL Tegen, I AF Cakmur, RV Miller, RL Tegen, I TI A comparison of seasonal and interannual variability of soil dust aerosols over the Atlantic Ocean as inferred by the TOMS AI and AVHRR AOT retrievals SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID METEOSAT ISCCP-B2 DATA; OPTICAL-THICKNESS; MINERAL DUST; SAHARAN DUST; NORTH-ATLANTIC; TROPOSPHERIC AEROSOLS; TROPICAL ATLANTIC; TRADE WINDS; SATELLITE; LOAD AB The seasonal cycle and interannual variability of two estimates of soil (or "mineral") dust aerosols axe compared: advanced very high resolution radiometer (AVHRR) aerosol optical thickness (AOT) and Total Ozone Mapping Spectrometer (TOMS) aerosol index (Al). Both data sets, comprising more than a decade of global, daily images, axe commonly; used to evaluate aerosol transport models. The present comparison is based on monthly averages, constructed from daily images of each data set for the period between 1984 and 1990, a period that excludes contamination from volcanic eruptions. The comparison focuses on the Northern Hemisphere subtropical Atlantic Ocean, where soil dust aerosols make the largest contribution to the aerosol load, and are assumed to dominate the variability of each data set. While each retrieval is sensitive, to a different aerosol radiative property (absorption for the TOMS Al versus reflectance for the AVHRR AOT), the seasonal cycles of dust loading implied by each retrieval are consistent, if seasonal variations in the height of the aerosol layer are taken into account when interpreting the TOMS Al. On interannual timescales, the correlation is low at most locations. It is suggested that the poor interannual correlation is at least partly a consequence of data availability. When the monthly averages axe constructed using only days common to both data sets, the correlation is substantially increased: this consistency suggests that both TOMS and AVHRR accurately measure the aerosol load in any given scene. However, the two retrievals have only a few days in common per month, so these restricted monthly averages have a large uncertainty. Calculations suggest that at least 7 to 1.0 daily images are needed to estimate reliably the average dust load during any particular month, a threshold that is rarely satisfied by the AVHRR AOT due to the presence of clouds in the domain. By rebinning each data set onto a coarser grid, the availability of the AVHRR AOT is increased during any particular month, along with its interannual correlation with the TOMS AL The latter easily exceeds the sampling threshold due to its greater ability to infer the aerosol load in the presence of clouds. Whether the TOMS Al should be regarded as a more reliable indicator of interannual variability depends on the extent of contamination by subpixel clouds. C1 Columbia Univ, Dept Appl Phys & Appl Math, New York, NY 10027 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Max Planck Inst Biogeochem, D-07745 Jena, Germany. RP Cakmur, RV (reprint author), Columbia Univ, Dept Appl Phys & Appl Math, New York, NY 10027 USA. EM rc241@columbia.edu; rmiller@giss.nasa.gov; itegen@bgc-jena.mpg.de RI Miller, Ron/E-1902-2012 NR 36 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-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2001 VL 106 IS D16 BP 18287 EP 18303 DI 10.1029/2000JD900525 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 465FR UT WOS:000170579400044 ER PT J AU Sabbah, I Ichoku, C Kaufman, YJ Remer, L AF Sabbah, I Ichoku, C Kaufman, YJ Remer, L TI Full year cycle of desert dust spectral optical thickness and precipitable water vapor over Alexandria, Egypt SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DEPTH; AEROSOLS; REGIONS; TOMS AB We study the annual cycle of dust loading in Alexandria, Egypt. Observations were performed from December 1997 to November 1998, including during the Karnaseen storms of March 1998. A ground-based, manual Sun photometer was used to measure aerosol optical thickness (tau (a)) at four spectral bands in the 340-870 nm wavelength range (namely 340, 440, 675, 870). Total precipitable water vapor (TV) was also measured simultaneously, based on the 936 nm channel measurements and extrapolations of the aerosol optical thickness from the neighboring 675 and 870 nm channels. Aerosol optical thickness tau (a) at all the four spectral bands were very high (averaging 2.0-4.0) during the Kamaseen storms of late March 1998. Correspondingly, the Angstrom wavelength exponent a of the optical thickness fell close to zero during that time, implying a substantial increase in dust. Overall, the monthly mean and median aerosol optical thickness were highest during January-May and lowest in June-October. During the January-May period total precipitable water vapor and Angstrom exponent were lower than during the June-October period. There is a high correlation between the Angstrom exponent and the optical thickness (r = 0.63), with a ranging from 0.0 to 0.5 for tau (a) > 1.0, indicating high dust concentration. Trajectory analysis shows that the presence of dust was associated with air masses arriving predominantly from the Sahara or North Africa. No significant correlation was found between the optical thickness and the precipitable water vapor. These basic systematic observations are vital for assessing dust climatology in this important part of the world and also for validating satellite observations and dust transport models. C1 Univ Alexandria, Fac Sci, Dept Phys, Alexandria, Egypt. NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Climate & Radiat Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Sabbah, I (reprint author), Univ Alexandria, Fac Sci, Dept Phys, Alexandria, Egypt. RI Ichoku, Charles/E-1857-2012 OI Ichoku, Charles/0000-0003-3244-4549 NR 30 TC 28 Z9 28 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2001 VL 106 IS D16 BP 18305 EP 18316 DI 10.1029/2000JD900410 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 465FR UT WOS:000170579400045 ER PT J AU Husar, RB Tratt, DM Schichtel, BA Falke, SR Li, F Jaffe, D Gasso, S Gill, T Laulainen, NS Lu, F Reheis, MC Chun, Y Westphal, D Holben, BN Gueymard, C McKendry, I Kuring, N Feldman, GC McClain, C Frouin, RJ Merrill, J DuBois, D Vignola, F Murayama, T Nickovic, S Wilson, WE Sassen, K Sugimoto, N Malm, WC AF Husar, RB Tratt, DM Schichtel, BA Falke, SR Li, F Jaffe, D Gasso, S Gill, T Laulainen, NS Lu, F Reheis, MC Chun, Y Westphal, D Holben, BN Gueymard, C McKendry, I Kuring, N Feldman, GC McClain, C Frouin, RJ Merrill, J DuBois, D Vignola, F Murayama, T Nickovic, S Wilson, WE Sassen, K Sugimoto, N Malm, WC TI Asian dust events of April 1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NORTH PACIFIC; HAWAIIAN-ISLANDS; ECOSYSTEM DEVELOPMENT; CHANGING SOURCES; AIR-POLLUTION; MAUNA-LOA; TRANSPORT; AEROSOL; OCEAN; NETWORK AB On April 15 and 19, 1998, two intense dust storms were generated over the Gobi desert by springtime low-pressure systems descending from the northwest. The windblown dust was detected and its evolution followed by its yellow color on SeaWiFS satellite images, routine surface-based monitoring, and through serendipitous observations. The April 15 dust cloud was recirculating, and it was removed by a precipitating weather system over east Asia. The April 19 dust cloud crossed the Pacific Ocean in 5 days, subsided to the surface along the mountain ranges between British Columbia and California, and impacted severely the optical and the concentration environments of the region. In east Asia the dust clouds increased the albedo over the cloudless ocean and land by up to 10-20%, but it reduced the near-UNI cloud reflectance, causing a yellow coloration of all surfaces. The yellow colored backscattering by the dust eludes a plausible explanation using simple Mie theory with constant refractive index. Over the West Coast the dust layer has increased the spectrally uniform optical depth to about 0.4, reduced the direct solar radiation by 30-40%, doubled the diffuse radiation, and caused a whitish discoloration of the blue sky. On April 29 the average excess surface-level dust aerosol concentration over the valleys of the West Coast was about 20-50 mug/m(3) with local peaks > 100 mug/m(3). The dust mass mean diameter was 2-3 mum, and the dust chemical fingerprints were evident throughout the West Coast and extended to Minnesota. The April 1998 dust event has impacted the surface aerosol concentration 2-4 times more than any other dust event since 1988. The dust events were observed and interpreted by an ad hoc international web-based virtual community. It would be useful to set up a community-supported web-based infrastructure to monitor the global aerosol pattern for such extreme aerosol events, to alert and to inform the interested communities, and to facilitate collaborative analysis for improved air quality and disaster management. C1 Washington Univ, Ctr Air Pollut Impact & Trend Anal, St Louis, MO 63130 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Washington, Seattle, WA 98195 USA. Texas Tech Univ, Dept Geosci, Lubbock, TX 79409 USA. Pacific NW Natl Lab, Richland, WA 99352 USA. China Meteorol Adm, Natl Satellite Meteorol Ctr, Beijing, Peoples R China. US Geol Survey, Washington, DC 20242 USA. Meteorol Res Inst, Seoul, South Korea. Naval Res Lab, Monterey, CA 93943 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Cent Florida, Orlando, FL 32816 USA. Univ British Columbia, Dept Geog, Vancouver, BC, Canada. Univ San Diego, Scripps Inst Oceanog, La Jolla, CA 92110 USA. Univ Rhode Isl, Ctr Atmospher Chem Studies, Kingston, RI 02881 USA. New Mexico Environm Dept, Air Qual Bur, Santa Fe, NM 87505 USA. Univ Oregon, Solar Monitoring Lab, Eugene, OR 97403 USA. Tokyo Univ Mercantile Marine, Dept Phys, Tokyo, Japan. Univ Malta, Euro Mediterranean Ctr Insular Coastal Dynam ICoD, Valletta, Malta. US EPA, Natl Ctr Environm Assessment, Res Triangle Pk, NC 27711 USA. Univ Utah, Dept Meteorol, Salt Lake City, UT 84112 USA. Natl Inst Environm Studies, Tsububa, Iburaki, Japan. Colorado State Univ, NPS Air Resources Div, Ft Collins, CO 80521 USA. RP Husar, RB (reprint author), Washington Univ, Ctr Air Pollut Impact & Trend Anal, Campus Box 1124, St Louis, MO 63130 USA. RI Husar, Rudolf/A-9000-2009; Tratt, David/A-7884-2009; Sugimoto, Nobuo/C-5189-2015; DuBois, David/F-6380-2015; Gasso, Santiago/H-9571-2014; OI Tratt, David/0000-0002-3942-6848; Sugimoto, Nobuo/0000-0002-0545-1316; DuBois, David/0000-0003-2560-505X; Gasso, Santiago/0000-0002-6872-0018; Gill, Thomas E/0000-0001-9011-4105 NR 51 TC 485 Z9 519 U1 8 U2 63 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2001 VL 106 IS D16 BP 18317 EP 18330 DI 10.1029/2000JD900788 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 465FR UT WOS:000170579400046 ER PT J AU Tratt, DM Frouin, RJ Westphal, DL AF Tratt, DM Frouin, RJ Westphal, DL TI April 1998 Asian dust event: A southern California perspective SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AEROSOL BACKSCATTER MEASUREMENTS; SKY RADIANCE MEASUREMENTS; OPTICAL-PROPERTIES; FORECAST MODEL; AIR-POLLUTION; TRANSPORT; LIDAR; RETRIEVAL; NETWORK; AERONET AB In late April 1998 an extreme Asian dust episode reached the U.S. western seaboard. This event was observed by several in situ and remote sensing atmospheric measurement stations. Dramatic reductions in boundary layer visibility were recorded and the resultant peak backscatter coefficients exceeded prevailing upper tropospheric background conditions by at least 2 orders of magnitude. An analysis of this event is given using lidar vertical backscatter profilometry, concurrent Sun photometer opacity data, and transport modeling. At San Nicolas Island the measured and modeled aerosol optical thickness at 500 nm increased dramatically from 0.15 on April 25 to 0.52 on April 26-27. Volume size distribution on April 27 exhibited a prominent coarse mode at 1-2 mum radius, and single-scattering albedo was observed to increase from 0.90 in the blue to 0.93 in the near infrared. Concurrent lidar observations tracked the evolution of the plume vertical structure, which consisted of up to three well-defined layers distributed throughout the free troposphere. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. Naval Res Lab, Marine Meteorol Div, Monterey, CA 93943 USA. RP Tratt, DM (reprint author), CALTECH, Jet Prop Lab, MS 168-214,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Tratt, David/A-7884-2009 OI Tratt, David/0000-0002-3942-6848 NR 28 TC 70 Z9 76 U1 2 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 2001 VL 106 IS D16 BP 18371 EP 18379 DI 10.1029/2000JD900758 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 465FR UT WOS:000170579400050 ER PT J AU Bonitz, R Slostad, J Bon, B Braun, D Brill, R Buck, C Fleischner, R Haldeman, A Herman, J Hetzel, M Noon, D Pixler, G Schenker, P Ton, T Tucker, C Zimmerman, W AF Bonitz, R Slostad, J Bon, B Braun, D Brill, R Buck, C Fleischner, R Haldeman, A Herman, J Hetzel, M Noon, D Pixler, G Schenker, P Ton, T Tucker, C Zimmerman, W TI Mars Volatiles and Climate Surveyor Robotic Arm SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB The primary purpose of the Mars Volatiles And Climate Surveyor (MVACS) Robotic Arm is to support the other MVACS science instruments by digging trenches in the Martian soil; acquiring and dumping soil samples into the Thermal Evolved Gas Analyzer; positioning the Soil Temperature Probe in the soil; positioning the Robotic Arm Air Temperature Sensor at various heights above the surface, and positioning the Robotic Arm Camera for taking images of the surface, trench, soil samples, magnetic targets, and other objects of scientific interest within its workspace. In addition to data collected from the Robotic Arm sensors during science support operations, the Robotic Arm will perform experiments along with the other science instruments to yield additional information on Martian soil mechanics in the vicinity of the lander. The experiments include periodic imaging of dumped soil piles, surface scraping and soil chopping experiments, compaction tests, insertion of the various end-effector tools into the soil, and trench cave-in tests. Data from the soil mechanics experiments will yield information on Martian soil properties such as angle of repose, cohesion, bearing strength, and grain size distribution. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90025 USA. RP Bonitz, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 5 Z9 5 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 2001 VL 106 IS E8 BP 17623 EP 17634 DI 10.1029/1999JE001140 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 465FU UT WOS:000170579600008 ER PT J AU Malin, MC Bell, JF Calvin, W Clancy, RT Haberle, RM James, PB Lee, SW Thomas, PC Caplinger, MA AF Malin, MC Bell, JF Calvin, W Clancy, RT Haberle, RM James, PB Lee, SW Thomas, PC Caplinger, MA TI Mars Color Imager (MARCI) on the Mars Climate Orbiter SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SOUTH POLAR-CAP; GENERAL-CIRCULATION MODEL; HUBBLE-SPACE-TELESCOPE; MARTIAN ATMOSPHERE; DUST STORMS; REFLECTANCE SPECTRA; SURFACE-COMPOSITION; PHYSICAL-PROPERTIES; LAYERED DEPOSITS; WIND STREAKS AB The Mars Color Imager, or MARCI, experiment on the Mars Climate Orbiter (MCO) consists of two cameras with unique optics and identical focal plane assemblies (FPAs), Data Acquisition System (DAS) electronics, and power supplies. Each camera is characterized by small physical size and mass (similar to6 X 6 X 12 cm, including baffle; < 500 g), low power requirements (< 2.5 W, including power supply losses), and high science performance (1000 X 1000 pixel, low noise). The Wide Angle (WA) camera will have the capability to map Mars in five visible and two ultraviolet spectral bands at a resolution of better than 8 km/pixel under the worst case downlink data rate. Under better downlink conditions the WA will provide kilometer-scale global maps of atmospheric phenomena such as clouds, hazes, dust storms, and the polar hood. Limb observations will provide additional detail on atmospheric structure at 1/3 scale-height resolution. The Medium Angle (MA) camera is designed to study selected areas of Mars at regional scale. From 400 km altitude its 6 degrees FOV, which covers similar to 40 km at 40 m/pixel, will permit all locations on the planet except the poles to be accessible for image acquisitions every two mapping cycles (roughly 52 sols). Eight spectral channels between 425 and 1000 nm provide the ability to discriminate both atmospheric and surface features on the basis of composition. The primary science objectives of MARCI are to (1) observe Martian atmospheric processes at synoptic scales and mesoscales, (2) study details of the interaction of the atmosphere with the surface at a variety of scales in both space and time, and (3) examine surface features characteristic of the evolution of the Martian climate over time. MARCI will directly address two of the three high-level goals of the Mars Surveyor Program: Climate and Resources. Life, the third goal, will be addressed indirectly through the environmental factors associated with the other two goals. C1 Malin Space Sci Syst, San Diego, CA 92191 USA. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. US Geol Survey, Flagstaff, AZ 86001 USA. Space Sci Inst, Boulder, CO 80303 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Toledo, Dept Astron, Toledo, OH 43606 USA. Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA. RP Malin, MC (reprint author), Malin Space Sci Syst, POB 910148, San Diego, CA 92191 USA. NR 81 TC 24 Z9 24 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 2001 VL 106 IS E8 BP 17651 EP 17672 DI 10.1029/1999JE001145 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 465FU UT WOS:000170579600010 ER PT J AU May, RD Forouhar, S Crisp, D Woodward, WS Paige, DA Pathare, A Boynton, WV AF May, RD Forouhar, S Crisp, D Woodward, WS Paige, DA Pathare, A Boynton, WV TI The MVACS tunable diode laser spectrometers SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SIMULTANEOUS INSITU MEASUREMENTS; QUANTUM-WELL LASERS; ATMOSPHERIC MEASUREMENTS; OPEN-PATH; NO2; N2O; CH4; ALIAS; HNO3; H2O AB Two independent tunable diode laser spectrometers are resident aboard the Mars Polar Lander as part of the Mars Volatiles and Climate Surveyor payload. One spectrometer is located on the meteorological mast for measurements of H2O and CO2 in the free atmosphere, and the other serves as the H2O and CO2 analyzer for the Thermal and Evolved Gas Analyzer. Water vapor is measured using a tunable diode laser operating at 1.37 Am, while CO2 is measured using a second laser operating near 2.05 mum. The 2.05 Am laser also has isotopic analysis capability. In addition to the major CO2 isotopomer ( (COO)-C-12-O-16-O-16), analyses of (COO)-C-13-O-16-O-16 and (COO)-C-12-O-18-O-16 in the atmosphere and in the Thermal and Evolved Gas Analyzer are possible under certain conditions. The spectrometers were designed and built at the Jet Propulsion Laboratory and have their heritage in a series of tunable diode laser spectrometers developed for Earth atmospheric studies using high-altitude aircraft and balloon platforms. The 137 mum diode laser on the meteorological mast will provide the first in situ measurements of water vapor in the Martian boundary layer, with a detection sensitivity an order of magnitude greater than the water vapor abundances inferred from the remote-sensing observations by the Viking Orbiters. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ N Carolina, Chapel Hill, NC USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA. Univ Arizona, Dept Planetary Sci, Tucson, AZ 85721 USA. RP May, RD (reprint author), SpectraSensors Inc, 2400 Lincoln Ave, Altadena, CA 91001 USA. NR 17 TC 8 Z9 8 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-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 2001 VL 106 IS E8 BP 17673 EP 17682 DI 10.1029/1999JE001146 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 465FU UT WOS:000170579600011 ER PT J AU Boynton, WV Bailey, SH Hamara, DK Williams, MS Bode, RC Fitzgibbon, MR Ko, WJ Ward, MG Sridhar, KR Blanchard, JA Lorenz, RD May, RD Paige, DA Pathare, AV Kring, DA Leshin, LA Ming, DW Zent, AP Golden, DC Kerry, KE Lauer, HV Quinn, RC AF Boynton, WV Bailey, SH Hamara, DK Williams, MS Bode, RC Fitzgibbon, MR Ko, WJ Ward, MG Sridhar, KR Blanchard, JA Lorenz, RD May, RD Paige, DA Pathare, AV Kring, DA Leshin, LA Ming, DW Zent, AP Golden, DC Kerry, KE Lauer, HV Quinn, RC TI Thermal and Evolved Gas Analyzer: Part of the Mars Volatile and Climate Surveyor integrated payload SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SNC METEORITES; GROUND ICE; ISOTOPIC COMPOSITION; MARTIAN REGOLITH; CARBON-DIOXIDE; POLAR-REGION; H2O; STABILITY; ATMOSPHERE; SUBSURFACE AB The Thermal and Evolved Gas Analyzer (TEGA) on the Mars Polar Lander spacecraft is composed of two separate components which are closely coupled: a Differential Scanning Calorimeter (DSC) and an Evolved Gas Analyzer (EGA). TEGA has the capability of performing differential scanning calorimetry on eight small (0.038 mL) soil samples selected in the vicinity of the lander. The samples will be heated in ovens to temperatures up to 950 degreesC, and the volatile compounds water and carbon dioxide, which are released during the heating, will be analyzed in the EGA. The power required by the sample oven is continuously monitored during the heating and compared to that required to heat simultaneously a similar, but empty, oven. The power difference is the output of the DSC. Both endothermic and exothermic phase transitions can be detected, and the data can be used in the identification of the phases present. By correlating the gas release with the calorimetry, the abundance of the volatile compounds associated with the different phases can be determined. The EGA may also be able to detect the release of oxygen associated with any superoxide that may be on the surface of the soil grains. The instrument can detect the melting of ice in the DSC down to abundances on the order of 0.2% of the sample, and it can detect the decomposition of calcite, CaCO3, down to abundances of 0.5%. Using the EGA, TEGA can detect small amounts of water, down to 8 ppm in the sample, and it can detect the associated release of CO2 down to the equivalent abundances of 0.03%. The EGA also has the ability to determine the C-13/C-12 ratio in the evolved CO2, but it is not clear if the accuracy of this ratio will be sufficient to address the scientific issues. C1 Univ Arizona, Dept Planetary Sci, Lunar & Planetary Lab, Tucson, AZ 85721 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA. Johnson Space Ctr, Houston, TX USA. Ames Res Ctr, Moffett Field, CA USA. RP Boynton, WV (reprint author), Univ Arizona, Dept Planetary Sci, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RI Lorenz, Ralph/B-8759-2016 OI Lorenz, Ralph/0000-0001-8528-4644 NR 45 TC 17 Z9 17 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 2001 VL 106 IS E8 BP 17683 EP 17698 DI 10.1029/1999JE001153 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 465FU UT WOS:000170579600012 ER PT J AU Awaki, H Terashima, Y Hayashida, K Sakano, M AF Awaki, H Terashima, Y Hayashida, K Sakano, M TI Estimation of central black hole masses in low-luminosity active galactic nuclei SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE active; galaxies : evolution; galaxies : nuclei; X-rays : galaxies ID X-RAY VARIABILITY; ADVECTION-DOMINATED ACCRETION; GALAXIES; LINERS; EMISSION; SEARCH; M81 AB We analyzed six low-luminosity active galactic nuclei (hereafter LLAGNs), which consist of two bright LINERS (low-ionization nuclear emission line region) with broad Hoe, and of four bright low-luminosity Seyferts observed by the X-ray satellite ASCA. We examined the time variabilities of these targets, and found that most targets show no significant time variabilities, although these galaxies belong to LLAGNs. By applying Fourier analysis to their light curves in the 2-10 keV band, we obtained the lower limits of their time variability scales, which correspond to their central black hole masses greater than several times 10(6) M-circle dot. Our result suggests that these LLAGNs are harbors of super-massive black holes. but the emitting powers are only < 1% of the Eddington luminosities of the central engines in the LLAGNs due to their small accretion rates. Since a black hole would grow by mass accretion, it is hard to create Such a super-massive black hole under a small accretion rate. Therefore, the mass-accretion rates in the past must have been larger than those at present, and the galaxies have probably been as luminous as QSOs. This will be a hint to find out the cause of the lack of QSOs in the local universe. C1 Ehime Univ, Fac Sci, Dept Phys, Matsuyama, Ehime 7908577, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Osaka Univ, Fac Sci, Dept Astrophys, Toyonaka, Osaka 5600043, Japan. NASDA, TKSC, Tsukuba, Ibaraki 3058505, Japan. RP Ehime Univ, Fac Sci, Dept Phys, Bunkyo Cho, Matsuyama, Ehime 7908577, Japan. EM awaki@astro.phys.sci.ehime-u.ac.jp NR 31 TC 17 Z9 17 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD AUG 25 PY 2001 VL 53 IS 4 BP 647 EP 652 DI 10.1093/pasj/53.4.647 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 468XE UT WOS:000170782800012 ER PT J AU Walch, SP Ramalingam, S Sriraman, S Aydil, ES Maroudas, D AF Walch, SP Ramalingam, S Sriraman, S Aydil, ES Maroudas, D TI Mechanisms and energetics of SiH3 adsorption on the pristine Si(001)-(2 x 1) surface SO CHEMICAL PHYSICS LETTERS LA English DT Article ID HYDROGENATED AMORPHOUS-SILICON; MOLECULAR-DYNAMICS SIMULATIONS; FILM GROWTH; ATOMISTIC SIMULATION; RADICAL DEPOSITION; PLASMA DEPOSITION; SOLAR-CELLS; BASIS-SETS; ABSTRACTION; DISCHARGES AB A theoretical study is presented of the adsorption mechanisms and energetics of the silyl (SiH3) radical on the pristine Si(0 0 1)-(2 x 1) surface based on density functional theory and molecular-dynamics (MD) simulations. Adsorption mechanisms include: (i) SiH3 attachment to a surface dangling bond, (ii) dissociative adsorption that involves insertion between dimer atoms and breaking of the dimer bond, (iii) bonding to two surface dimer atoms of neighboring pairs in the same dimer row, and (iv) bridging of neighboring dimer rows. The dissociative adsorption where the Si-Si surface dimer bond is broken is the most exothermic mechanism. (C) 2001 Published by Elsevier Science BY. C1 Univ Calif Santa Barbara, Dept Chem Engn, Santa Barbara, CA 93106 USA. NASA, Ames Res Ctr, Thermosci Inst, Moffett Field, CA 94035 USA. RP Maroudas, D (reprint author), Univ Calif Santa Barbara, Dept Chem Engn, Santa Barbara, CA 93106 USA. NR 30 TC 16 Z9 16 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 AUG 24 PY 2001 VL 344 IS 3-4 BP 249 EP 255 DI 10.1016/S0009-2614(01)00777-1 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 466ZL UT WOS:000170676000001 ER PT J AU Sheth, RK Hui, L Diaferio, A Scoccimarro, R AF Sheth, RK Hui, L Diaferio, A Scoccimarro, R TI Linear and non-linear contributions to pairwise peculiar velocities SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : clusters : general; cosmology : theory; dark matter ID DARK-MATTER HALOES; ANALYTIC MODEL; GALAXIES; DENSITY; STATISTICS; UNIVERSE; DISTRIBUTIONS; PERTURBATIONS; FLUCTUATIONS; DISPERSION AB We write the correlation function of dark matter particles, xi (r), as the sum of two terms one which accounts for non-linear evolution, and dominates on small scales, and another which is essentially the term from linear theory, and dominates on large scales. We use models of the number and spatial distribution of haloes and halo density profiles to describe the non-linear term and its evolution. The result provides a good description of the evolution of xi (r) in simulations. We then use this decomposition to provide simple and accurate models of how the single-particle velocity dispersion evolves with time, and how the first and second moments of the pairwise velocity distribution depend on scale. The key idea is to use the simple physics of linear theory on large scales, the simple physics of the virial theorem on small scales and our model for the correlation function to tell us how to weight the two types of contributions (linear and non-linear) to the pairwise velocity statistics. When incorporated into the streaming model, our results will allow a simple accurate description of redshift-space distortions over the entire range of linear to highly non-linear regimes. C1 NASA, Fermilab Astrophys Grp, Batavia, IL 60510 USA. Inst Adv Study, Sch Nat Sci, Princeton, NJ 08540 USA. Columbia Univ, Dept Phys, New York, NY 10027 USA. Univ Turin, Dipartimento Fis Gen Amedeo Avogadro, Turin, Italy. RP Sheth, RK (reprint author), NASA, Fermilab Astrophys Grp, MS 209, Batavia, IL 60510 USA. NR 42 TC 60 Z9 61 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 21 PY 2001 VL 325 IS 4 BP 1288 EP 1302 DI 10.1046/j.1365-8711.2001.04222.x PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 469CF UT WOS:000170794900004 ER PT J AU Meyer, WV Smart, AE Brown, RGW AF Meyer, WV Smart, AE Brown, RGW TI Photon correlation and scattering: introduction to the feature issue SO APPLIED OPTICS LA English DT Editorial Material AB This feature issue of Applied Optics contains 31 research papers on photon correlation and scattering, many of which were presented at an OSA Topical Meeting that was held 21-23 August 2000 in Whistler, British Columbia, Canada. These papers focus on research in dynamic light scattering, surface light scattering, photon correlation, and laser velocimetry and their applications to physical, chemical, and biological processes. (C) 2001 Optical Society of America. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. Inst Phys, Bristol BS1 6BE, Avon, England. Univ Nottingham, Dept Elect & Elect Engn, Nottingham NG7 2RD, England. RP Meyer, WV (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, 2100 Brookpk Rd,MS 110-3, Cleveland, OH 44135 USA. EM william.v.meyer@grc.nasa.gov NR 17 TC 4 Z9 4 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 2001 VL 40 IS 24 BP 3965 EP 3968 DI 10.1364/AO.40.003965 PG 4 WC Optics SC Optics GA 464QM UT WOS:000170543300001 PM 18360430 ER PT J AU Smart, AE Edwards, RV Meyer, WV AF Smart, AE Edwards, RV Meyer, WV TI Quantitative simulation of errors in correlation analysis SO APPLIED OPTICS LA English DT Article ID CORRELATION SPECTROSCOPY; PHOTON-CORRELATION; LIGHT-SCATTERING; NOISE AB Bounding the errors of measurements derived from correlation functions of light scattered from some physical systems is typically complicated by the ill conditioning of the data inversion. Parameter values are estimated from fitting well-chosen models to measurements taken for long enough to look acceptable, or at least to yield convergence to some reasonable result. We show some simple numerical simulation that indicate the possibility of substantial and unanticipated errors even in comparatively simple experiments. We further show quantitative evidence for the effectiveness of a number of ad hoc aspects of the art of performing good light-scattering experiments and recovering useful measurements from them. Separating data-inversion properties from experimental inconsistencies may lead to a better understanding and better bounding of some errors, giving new ways to improve overall experimental accuracy. (C) 2001 Optical Society of America. C1 Case Western Reserve Univ, Cleveland, OH 44106 USA. NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. RP Smart, AE (reprint author), 2857 Europa Dr, Costa Mesa, CA 92626 USA. EM antnysmart@aol.com; rve2@po.cwru.edu; william.v.meyer@grc.nasa.gov NR 16 TC 5 Z9 6 U1 1 U2 10 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 AUG 20 PY 2001 VL 40 IS 24 BP 4064 EP 4078 DI 10.1364/AO.40.004064 PG 15 WC Optics SC Optics GA 464QM UT WOS:000170543300014 PM 18360443 ER PT J AU Mann, JA Crouser, PD Meyer, WV AF Mann, JA Crouser, PD Meyer, WV TI Surface fluctuation spectroscopy by surface-light-scattering spectroscopy SO APPLIED OPTICS LA English DT Article ID CAPILLARY WAVES; VISCOSITY; TENSION; FILMS; INTERFACE; DYNAMICS; FLUID; WATER AB In recent years surface-light-scattering spectroscopy has been transformed from a complex optical experiment requiring substantial effort to operate effectively to a simpler instrument for which an accurate theory of operation has been developed. The accuracy and precision are sufficiently enhanced that refinement of the theory of spectral band shapes is justified to include more subtle effects such as bending moduli and thin-film forces associated with the van der Waals and the Casimir effects. We show how to develop extensions of the theory of interfacial fluctuations through the mass and the momentum balances of interfacial transport. We also show that free-energy functionals can be used to express curvature effects crisply. The results are detailed formulas that can be used to fit experimental spectra. (C) 2001 Optical Society of America. C1 Case Western Reserve Univ, Dept Chem Engn, Cleveland, OH 44106 USA. Couser Associates, Bay Village, OH 44140 USA. NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. RP Mann, JA (reprint author), Case Western Reserve Univ, Dept Chem Engn, Cleveland, OH 44106 USA. EM jam12@po.cwru.edu; PCrouser@megsINet.net; william.v.meyer@grc.nasa.gov NR 39 TC 8 Z9 8 U1 3 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 2001 VL 40 IS 24 BP 4092 EP 4112 DI 10.1364/AO.40.004092 PG 21 WC Optics SC Optics GA 464QM UT WOS:000170543300017 PM 18360446 ER PT J AU Meyer, WV Wegdam, GH Fenistein, D Mann, JA AF Meyer, WV Wegdam, GH Fenistein, D Mann, JA TI Advances in surface-light-scattering instrumentation and analysis: noninvasive measuring of surface tension, viscosity, and other interfacial parameters SO APPLIED OPTICS LA English DT Article ID CAPILLARY WAVES; SPECTROSCOPY AB A new generation of vibration-mitigating surface-light-scattering instrumentation has been designed and built. The computational application of an instrument function derived by use of Fourier optics is presented. This instrument and its accompanying suite of analysis software allow us to easily make accurate and noninvasive measurements of the interfacial tension, volume viscosity, and other interfacial parameters of fluids. We derived the necessary surface response function algorithms to study both simple fluids and binary fluids at their wetting transition and near their critical points. These developments can be applied to study systems with liquid-vapor and liquid-liquid interfaces, including spread monolayers, whenever optical access for a laser beam is available. (C) 2001 Optical Society of America. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. Univ Amsterdam, Van der Waals Zeeman Inst, NL-1018 XE Amsterdam, Netherlands. Case Western Reserve Univ, Dept Chem Engn, Cleveland, OH 44106 USA. RP Meyer, WV (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. EM william.v.meyer@grc.nasa.gov; Wegdam@Phys.UvA.Nl; jam12@po.cwru.edu NR 16 TC 10 Z9 10 U1 2 U2 6 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 2001 VL 40 IS 24 BP 4113 EP 4133 DI 10.1364/AO.40.004113 PG 21 WC Optics SC Optics GA 464QM UT WOS:000170543300018 PM 18360447 ER PT J AU Fenistein, D Wegdam, GH Meyer, WV Mann, JA AF Fenistein, D Wegdam, GH Meyer, WV Mann, JA TI Capillary waves on an asymmetric liquid film of pentane on water SO APPLIED OPTICS LA English DT Article ID LIGHT-SCATTERING; SURFACE-TENSION; SPECTROSCOPY; INTERFACE; MEMBRANES; FORCES AB Surface light-scattering measurements have been carried out on thin asymmetric films of pentane on water. We vary the film thickness l over a wide range (10(-9) m < l < 10(-5) m). Compared with the ripplons wavelength 1/q, thick films of pentane (l much greater than 1/q) display the same power spectrum as a pure pentane-vapor interface: a single peak. When thinning the film down to l approximate to 1/q, hydrodynamic coupling between the layers of the interface is revealed by the appearance of a second peak beside the first one. We describe the thickness dependence of the two coupled modes through variations of the positions, the widths, and the amplitudes of both peaks. (C) 2001 Optical Society of America. C1 Univ Amsterdam, Van der Waals Zeeman Inst, NL-1018 XE Amsterdam, Netherlands. NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. Case Western Reserve Univ, Cleveland, OH 44106 USA. RP Fenistein, D (reprint author), Univ Amsterdam, Van der Waals Zeeman Inst, Valckenierstr 65, NL-1018 XE Amsterdam, Netherlands. EM denis@wins.uva.nl NR 34 TC 5 Z9 5 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 2001 VL 40 IS 24 BP 4134 EP 4139 DI 10.1364/AO.40.004134 PG 6 WC Optics SC Optics GA 464QM UT WOS:000170543300019 PM 18360448 ER PT J AU Cheng, ZD Zhu, JX Russel, WB Meyer, WV Chaikin, PM AF Cheng, ZD Zhu, JX Russel, WB Meyer, WV Chaikin, PM TI Colloidal hard-sphere crystallization kinetics in microgravity and normal gravity SO APPLIED OPTICS LA English DT Article ID DYNAMIC LIGHT-SCATTERING; DENSITY-FLUCTUATIONS; GLASS-TRANSITION; CRYSTALS; GROWTH; SUSPENSIONS; NUCLEATION; ENTROPY; SYSTEMS; STATE AB The hard-sphere disorder-order transition serves as the paradigm for crystallization. We used time-resolved Bragg light scattering from the close-packed planes to measure the kinetics of nucleation and growth of colloidal hard-sphere crystals. The effects of gravity are revealed by comparison of the experiments in microgravity and normal gravity. Crystallites grow faster and larger in microgravity, and the coarsening between crystallites is suppressed by gravity. The face-centered-cubic structure was strongly indicated as being the stable structure for hard-sphere crystals. For a sample with a volume fraction of 0.552, the classic nucleation and growth picture is followed. (C) 2001 Optical Society of America. C1 Princeton Univ, Dept Phys, Princeton, NJ 08540 USA. Princeton Univ, Dept Chem Engn, Princeton, NJ 08540 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Cheng, ZD (reprint author), Exxon Mobil Res & Engn Co, 1545 Route 22 E, Annandale, NJ 08801 USA. EM chaikin@pupgg.princeton.edu NR 32 TC 23 Z9 23 U1 3 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 AUG 20 PY 2001 VL 40 IS 24 BP 4146 EP 4151 DI 10.1364/AO.40.004146 PG 6 WC Optics SC Optics GA 464QM UT WOS:000170543300021 PM 18360450 ER PT J AU Vasilkov, AP Goldin, YA Gureev, BA Hoge, FE Swift, RN Wright, CW AF Vasilkov, AP Goldin, YA Gureev, BA Hoge, FE Swift, RN Wright, CW TI Airborne polarized lidar detection of scattering layers in the ocean SO APPLIED OPTICS LA English DT Article ID LASER; WATER; LIGHT; PARAMETERS; TURBIDITY; PROFILES; MEDIA AB A polarized lidar technique based on measurements of waveforms of the two orthogonal-polarized components of the backscattered light pulse is proposed to retrieve vertical profiles of the seawater scattering coefficient, The physical rationale for the polarized technique is that depolarization of backscattered light originating from a linearly polarized laser beam is caused largely by multiple small-angle scattering from particulate matter in seawater. The magnitude of the small-angle scattering is determined by the scattering coefficient. Therefore information on the vertical distribution of the scattering coefficient can be derived potentially from measurements of the time-depth dependence of depolarization in the backscattered laser pulse. The polarized technique was verified by field measurements conducted in the Middle Atlantic Bight of the western North Atlantic Ocean that were supported by in situ measurements of the beam attenuation coefficient. The airborne polarized lidar measured the time-depth dependence of the backscattered laser pulse in two orthogonal-polarized components. Vertical profiles of the scattering coefficient retrieved from the time-depth depolarization of the backscattered laser pulse were compared with measured profiles of the beam attenuation coefficient. The comparison showed that retrieved profiles of the scattering coefficient clearly reproduce the main features of the measured profiles of the beam attenuation coefficient. Underwater scattering layers were detected at depths of 20-25 m in turbid coastal waters. The improvement in dynamic range afforded by the polarized lidar technique offers a strong potential benefit for airborne lidar bathymetric applications. C1 Raytheon Informat Technol & Sci Serv, Greenbelt, MD 20770 USA. Shirshov Inst Oceanol, Moscow, Russia. NASA Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Isl, VA 23337 USA. RP Vasilkov, AP (reprint author), Raytheon Informat Technol & Sci Serv, 7701 Greenbelt Rd, Greenbelt, MD 20770 USA. EM hoge@osb1.wff.nasa.gov NR 31 TC 24 Z9 26 U1 0 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 AUG 20 PY 2001 VL 40 IS 24 BP 4353 EP 4364 DI 10.1364/AO.40.004353 PG 12 WC Optics SC Optics GA 464QM UT WOS:000170543300047 PM 18360476 ER PT J AU Flood, DJ AF Flood, DJ TI Space photovoltaics - History, progress and promise SO MODERN PHYSICS LETTERS B LA English DT Article; Proceedings Paper CT Meeting of the 3rd Workshop on Optoelectronic Materials and their Applications (Including Solar Cells) CY AUG 28-SEP 01, 2000 CL OAXACA, MEXICO ID SOLAR-CELLS; SILICON; RADIATION AB The first space solar array was carried aloft on Vanguard I on March 17, 1958. Vanguard I was the second satellite successfully launched by the U.S. space program following the launch of Sputnik I by the (then) USSR on October 4, 1957. The array on Vanguard I consisted of six photovoltaic panels mounted on the outer surface of the satellite. The array produced about one watt of power for over six years. The cells on that first array were single crystal silicon, each 2cm. x 0.5cm in size, and about 10% efficient at 28C. Solar arrays are now the primary source of power for all earth orbiting satellites. Space solar arrays and power systems have grown in size and complexity since 1958. This paper will provide an overview of a typical satellite power system along with the current status of solar cell technology development in the U.S. C1 Nanodielect Corp, Oberlin, OH 44074 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Flood, DJ (reprint author), Nanodielect Corp, Oberlin, OH 44074 USA. NR 87 TC 1 Z9 1 U1 3 U2 12 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA 5 TOH TUCK LINK, SINGAPORE 596224, SINGAPORE SN 0217-9849 J9 MOD PHYS LETT B JI Mod. Phys. Lett. B PD AUG 20 PY 2001 VL 15 IS 17-19 BP 561 EP 570 DI 10.1142/S0217984901002038 PG 10 WC Physics, Applied; Physics, Condensed Matter; Physics, Mathematical SC Physics GA 488AB UT WOS:000171910900002 ER PT J AU Sassi, F Salby, M Read, WG AF Sassi, F Salby, M Read, WG TI Relationship between upper tropospheric humidity and deep convection SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GLOBAL CLOUD IMAGERY; WATER-VAPOR; UARS MLS; MULTIPLE SATELLITES AB Satellite measurements of upper tropospheric humidity (UTH) are used together with global cloud imagery to study the relationship between deep convection and moisture in the upper troposphere. Throughout the tropics, regions of cold cloud coincide with regions of enhanced UTH,in time-mean distributions, in daily synoptic maps, and even on the short scales that characterize individual convective systems. Cold-cloud fraction and UTH have very similar instantaneous structure. The horizontal correlation scales are narrow for both cloud fraction and UTH at 315 hPa and 215 hPa. The correlation scale of UTH expands at 146 hPa, signaling an increased role of horizontal transport. Ventilation of the upper troposphere by convection is also evidenced by thermal structure: Inside regions of deep convection the vertical separation of theta surfaces is expanded, stability being weakened by convective mixing inside a deep layer centered near 200 hPa. Supported by a cloud detrainment, convection humidifies the upper troposphere, elevating mixing ratio surfaces over their surroundings. The reverse is observed at subtropical latitudes, where air is anomalously dry. Jointly, these features characterize vertical transport by the Hadley and Walker circulations. C1 Atmospher Syst & Anal, Westminster, CO USA. Univ Colorado, Program Atmospher & Ocean Sci, Boulder, CO 80309 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sassi, F (reprint author), Atmospher Syst & Anal, 1400 W 122nd Ave,Suite 101, Westminster, CO USA. OI Sassi, Fabrizio/0000-0002-9492-7434 NR 13 TC 16 Z9 17 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2001 VL 106 IS D15 BP 17133 EP 17146 DI 10.1029/2001JD900121 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 463BP UT WOS:000170457200005 ER PT J AU Jensen, EJ Pfister, L Ackerman, AS Tabazadeh, A Toon, OB AF Jensen, EJ Pfister, L Ackerman, AS Tabazadeh, A Toon, OB TI A conceptual model of the dehydration of air due to freeze-drying by optically thin, laminar cirrus rising slowly across the tropical tropopause SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC WATER-VAPOR; SUBVISIBLE CIRRUS; UPPER TROPOSPHERE; ICE NUCLEATION; RELATIVE-HUMIDITY; CLOUDS; AEROSOL; STEP; SCATTERING; PARTICLES AB In this study, we use a cloud model to simulate dehydration which occurs due to formation of optically thin, laminar cirrus as air rises slowly across the tropopause. The slow ascent and adiabatic cooling, which balances the radiative heating near the tropopause, drives nucleation of a very small number of ice crystals (< 1 L-1). These crystals grow rapidly and sediment out within a few hours. The clouds never become optically thick enough to be visible from the ground. The ice crystal nucleation and growth prevents the relative humidity with respect to ice (RHI) from rising more than a few percent above the threshold for ice nucleation (RHInuc similar or equal to 110-160%, depending upon the aerosol composition); hence, laminar cirrus can limit the mixing ratio of water vapor entering the stratosphere. However, the ice number densities are too low and their sedimentation is too rapid to allow dehydration of the air from RHInuc, down to saturation (RHI = 100%). The net result is that air crosses the tropopause with water vapor mixing ratios about 1.1 to 1.6 times the ice saturation mixing ratio corresponding to the tropopause temperature, depending on the threshold of ice nucleation on aerosols in the tropopause region. If the cross-tropopause ascent rate is larger than that calculated to balance radiative heating (0.2 cm s(-1)), then larger ice crystal number densities are generated., and more effective dehydration is possible (assuming a fixed temperature). The water vapor mixing ratio entering the stratosphere decreases with increasing ascent rate (approaching the tropopause ice saturation mixing ratio) until the vertical wind speed exceeds the ice crystal terminal velocity (about 10 cm s(-1)). More effective dehydration can also be provided by temperature oscillations associated with wave motions. The water vapor mixing ratio entering the stratosphere is essentially controlled by the tropopause temperature at the coldest point in the wave. Hence, the efficiency of dehydration at the tropopause depends upon both the effectiveness of upper tropospheric aerosols as ice nuclei and the occurrence of wave motions in the tropopause region. In situ humidity observations from tropical aircraft campaigns and balloon launches over the past several years have provided a few examples of ice-supersaturated air near the tropopause. However, given the scarcity of data and the uncertainties in water vapor measurements, we lack definitive evidence that air entering the stratosphere is supersaturated with respect to ice. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. RP Jensen, EJ (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. RI Ackerman, Andrew/D-4433-2012 OI Ackerman, Andrew/0000-0003-0254-6253 NR 45 TC 65 Z9 66 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2001 VL 106 IS D15 BP 17237 EP 17252 DI 10.1029/2000JD900649 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 463BP UT WOS:000170457200012 ER PT J AU Jensen, EJ Toon, OB Vay, SA Ovarlez, J May, R Bui, TP Twohy, CH Gandrud, BW Pueschel, RF Schumann, U AF Jensen, EJ Toon, OB Vay, SA Ovarlez, J May, R Bui, TP Twohy, CH Gandrud, BW Pueschel, RF Schumann, U TI Prevalence of ice-supersaturated regions in the upper troposphere: Implications for optically thin ice cloud formation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID WATER-VAPOR MEASUREMENTS; RELATIVE-HUMIDITY; CIRRUS CLOUDS; RESIDUAL PARTICLES; NORTH-ATLANTIC; NUCLEATION; SCATTERING; AEROSOL; SUCCESS; CONTRAILS AB In situ measurements of water vapor and temperature from recent aircraft campaigns have provided evidence that the upper troposphere is frequently supersaturated with respect to ice. The peak relative humidities with respect, to ice (RHI) occasionally approached water saturation at temperatures ranging from -40 degreesC to 70 degreesC in each of the campaigns. The occurrence frequency of ice supersaturation ranged from about 20% to 45%. Even oil flight segments when no ice crystals were detected, ice supersaturation was measured about 5-20% of the time. A numerical cloud model is used to simulate the formation of optically thin, low ice number density cirrus clouds in these supersaturated regions. The potential for scavenging of ice nuclei (IN) by these clouds is evaluated. The simulations suggest that if less than about 5 x 10(-3) to 2 x 10(-2) cm(-3) ice nuclei are present when these supersaturations are generated, then the cirrus formed should be subvisible. These low ice number density clouds scavenge the IN from the supersaturated layer, but the crystals sediment out too rapidly to prevent buildup of high supersaturations. If higher numbers of ice nuclei are present. then the clouds that form are visible and deposition growth of the ice crystals reduces the RHI down to near 100%. Even if no ice clouds form. increasing the RHI from 100% to 150% between 10 and 10.5 km results in a decrease in outgoing lon-wave radiative flux at the top of the atmosphere of about 8 W m(-2). If 0.02-0.1 cm(-3) IN are present, the resulting cloud radiative forcing reduces the net radiative flux several watts per square meter further. Given the high frequency of supersaturated regions without optically thick clouds in the upper troposphere. there is a potential for a climatically important class of optically thin cirrus with relatively low ice crystal number densities. The optical properties of these clouds will depend very strongly on the abundance of ice nuclei in the upper troposphere. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Colorado, Dept Atmospher & Ocean Sci, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Ecole Polytech, Meteorol Dynam Lab, F-91128 Palaiseau, France. Jet Propuls Lab, Pasadena, CA USA. Natl Ctr Atmospher Res, ATD, Boulder, CO 80307 USA. Inst Phys Atmosphare, Deut Zent Luft & Faumfahrt, D-82230 Oberpfaffenhofen, Germany. RP Jensen, EJ (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. OI Schumann, Ulrich/0000-0001-5255-6869 NR 33 TC 73 Z9 74 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2001 VL 106 IS D15 BP 17253 EP 17266 DI 10.1029/2000JD900526 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 463BP UT WOS:000170457200013 ER PT J AU Yang, P Gao, BC Baum, BA Wiscombe, WJ Hu, YX Nasiri, SL Soulen, PF Heymsfield, AJ McFarquhar, GM Miloshevich, LM AF Yang, P Gao, BC Baum, BA Wiscombe, WJ Hu, YX Nasiri, SL Soulen, PF Heymsfield, AJ McFarquhar, GM Miloshevich, LM TI Sensitivity of cirrus bidirectional reflectance to vertical inhomogeneity of ice crystal habits and size distributions for two Moderate-Resolution Imaging Spectroradiometer (MODIS) bands SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SINGLE-SCATTERING PROPERTIES; AIRBORNE SIMULATOR IMAGERY; SOLAR RADIATIVE-TRANSFER; MU-M WINDOW; LIGHT-SCATTERING; PHASE FUNCTIONS; ACCURATE PARAMETERIZATION; MULTIPLE-SCATTERING; INFRARED RADIANCES; OPTICAL-THICKNESS AB A common assumption in satellite imager-based cirrus retrieval algorithms is that the radiative properties of a cirrus cloud may be represented by those associated with a specific ice crystal shape (or habit) and a single particle size distribution. However, observations of cirrus clouds have shown that the shapes and sizes of ice crystals may vary substantially with height within the clouds. In this study we investigate the sensitivity of the top-of-atmosphere bidirectional reflectances for two Moderate-Resolution Imaging Spectroradiometer (MODIS) bands centered at 0.65 mum and 2.11 mum to cirrus models composed of either a single homogeneous layer or three distinct, but contiguous, layers. First, we define the single- and three-layer cirrus cloud models with respect to ice crystal habit and size distributions on the basis of in situ replicator data acquired during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE-II), held in Kansas during the fall of 1991. Subsequently, fundamental light-scattering and radiative transfer theory is employed to determine the single-scattering and the bulk radiative properties of the cirrus cloud. For radiative transfer computations we present a discrete form of the adding/doubling principle that is computationally straightforward and efficient. For the 0.65 mum band, at which absorption by ice is negligible, there is little difference between the bidirectional reflectances calculated for the one- and three-layer cirrus models. This result suggests that the vertical inhomogeneity effect is relatively unimportant at 0.65 mum. At 2.11 mum the bidirectional reflectances computed for both optically thin (tau = 1) and thick (tau = 10) cirrus clouds show significant differences between the results for the one- and three-layer models. The reflectances computed for the three-layer cirrus model are substantially larger than those computed for the single-layer cirrus. Furthermore, our analysis shows that the cirrus reflectances at both the 0.65 and 2.11 mum bands are very sensitive to the optical properties of the small crystals that predominate in the top layer of the three-layer cirrus model. It is critical to define the most realistic geometric shape for the small "quasi-spherical" ice crystals in the top layer for obtaining reliable single-scattering parameters and bulk radiative properties of cirrus. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. USN, Res Lab, Remote Sensing Div, Washington, DC 20375 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Univ Wisconsin, Cooperat Inst Meteorol Satellite Studies, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Yang, P (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, MS 420, Hampton, VA 23681 USA. RI Yang, Ping/B-4590-2011; Baum, Bryan/B-7670-2011; Heymsfield, Andrew/E-7340-2011; Nasiri, Shaima/C-8044-2011; Wiscombe, Warren/D-4665-2012; Hu, Yongxiang/K-4426-2012; OI Baum, Bryan/0000-0002-7193-2767; Wiscombe, Warren/0000-0001-6844-9849; McFarquhar, Greg/0000-0003-0950-0135 NR 65 TC 44 Z9 44 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2001 VL 106 IS D15 BP 17267 EP 17291 DI 10.1029/2000JD900618 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 463BP UT WOS:000170457200014 ER PT J AU Green, RO AF Green, RO TI Atmospheric water vapor sensitivity and compensation requirement for Earth-looking imaging spectrometers in the solar-reflected spectrum SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AVIRIS DATA; SPECTROSCOPY AB An increasing number of Earth-looking imaging spectrometers are being developed to derive properties of the surface from measured upwelling spectral radiance that has passed through the atmosphere. However, the measurements are influenced by the amount of atmospheric water vapor. Water vapor is present in every spectrum and is highly variable through space and time. This research assesses the sensitivity to the accurate knowledge of atmospheric water vapor of imaging spectrometers with surface measurement objectives. This sensitivity is explored for a range of imaging spectrometer spectral resolutions from 5 to 20 nm as well as for a range of atmospheric water vapor from normal to dry conditions. The effect of atmospheric water vapor errors of 50, 25, 10, 5, and 1% is analyzed. In all cases the derived surface reflectance is shown to be strongly sensitive to the accurate knowledge of water vapor in the imaging spectrometer measurement. This result leads to a general requirement of 1% or better knowledge of atmospheric water vapor in order to derive surface reflectance that is largely free of water-vapor-induced errors, distortions, and spectral artifacts. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. RP Green, RO (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 28 TC 11 Z9 11 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2001 VL 106 IS D15 BP 17443 EP 17452 DI 10.1029/2000JD900799 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 463BP UT WOS:000170457200026 ER PT J AU Planet, WG Miller, AJ Horvath, K Nagatani, R Flynn, LE Hilsenrath, E Kondragunta, S Cebula, RP DeLand, MT AF Planet, WG Miller, AJ Horvath, K Nagatani, R Flynn, LE Hilsenrath, E Kondragunta, S Cebula, RP DeLand, MT TI Total ozone determinations from National Oceanic and Atmospheric Administration operational solar backscattered ultraviolet 2 instrument observations: An update SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NORTHERN-HEMISPHERE; TRENDS; SBUV; ACCURACY; TOMS AB Total ozone amounts have been derived from observations of the Solar Backscattered Ultraviolet 2 (SBUV/2) instruments on National Oceanic and Atmospheric Administration (NOAA) operational satellites since 1985. The data from the NOAA-9 instrument for the period 1985-1997 have been reprocessed using instrument characterizations based on in-orbit operation and comparisons with Shuttle Solar Backscattered Ultraviolet (SSBUV) observations. The data from the NOAA-11 satellite for the period 1989-1994 have also been reprocessed using mainly internal spacecraft information. The data from the NOAA-14 satellite for the period 1995-1998 have been reprocessed using complete instrument characterization. The NOAA-11 and NOAA-14 data for 1998 to the present, briefly discussed herein, are preliminary. The calibration adjustments used in the reprocessing of NOAA-9, NOAA-11, and NOAA-14 total ozone data are internal, with the exception of those derived from SSBUV analysis, and are independent of Dobson and Total Ozone Mapping Spectrometer (TOMS) total ozone measurements. The reprocessed data have been validated with ground-based Dobson spectrophotometer observations, and are compared to other sources of total column ozone amounts. The mean bias between NOAA-9 data and Dobson data is 1.9% +/- 0.6% over the 12-year record with a trend of 0.1% per year. The mean bias between NOAA-11 and Dobson data is 0.8% +/- 0.2% with a near-zero trend. The mean bias between NOAA-14 and Dobson data is 1.5% +/- 0.3% with a trend of 0.2% per year; the NOAA-14 calibration and characterization data for the period 1998 to the present are not yet fully analyzed. The methods used in the validations are discussed here, as are some reasons for the results. Finally, a recommendation is made for the use of a relatively continuous total ozone data set. C1 NOAA, Off Res & Applicat, Natl Environm Satellite Data & Informat Serv, Camp Springs, MD 20746 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NOAA, Climate Predict Ctr, Weather Serv, Camp Springs, MD 20746 USA. Res & Data Syst Corp, Greenbelt, MD USA. Raytheon Co, Informat Technol Serv, Lanham, MD USA. Raytheon Co, Sci Serv, Lanham, MD USA. RP Planet, WG (reprint author), 13115 14 St, Bowie, MD USA. RI Flynn, Lawrence/B-6321-2009; Kondragunta, Shobha/F-5601-2010 OI Flynn, Lawrence/0000-0001-6856-2614; Kondragunta, Shobha/0000-0001-8593-8046 NR 23 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 16 PY 2001 VL 106 IS D15 BP 17471 EP 17478 DI 10.1029/2000JD900729 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 463BP UT WOS:000170457200028 ER PT J AU Chen, KY Yeh, HC Su, SY Liu, CH Huang, NE AF Chen, KY Yeh, HC Su, SY Liu, CH Huang, NE TI Anatomy of plasma structures in an Equatorial Spread F Event SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HILBERT SPECTRUM; WAVES AB This paper investigates the small scale plasma structures observed by ROCSAT-1 in the equatorial F region through the newly developed Hilbert-Huang transform (HHT) method in the time (space) domain under the frozen-in approximation. The new method allows us to decompose the non-stationary, nonlinear data into a finite number of intrinsic scale modes. In this report the structures of vertical ion velocity and horizontal density gradient inside a plasma bubble are analyzed mode by mode anatomically without making the usual linearization assumption. We found that the intrinsic modes for velocity and density gradient of the selected event have identical wave form for structures with scales between 300 m and 50 m. This implies that the vertical velocity fluctuations induced from the electric field follows the exact Boltzmann relation in the limited regime of scale length between 300 m and 50 m. A spectral break at 50 m is clearly seen in the velocity HHT spectrum. The spectral form of velocity differs greatly from that of density gradient at scale lengths shorter than 50 m. C1 Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chen, KY (reprint author), Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan. NR 7 TC 12 Z9 12 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 AUG 15 PY 2001 VL 28 IS 16 BP 3107 EP 3110 DI 10.1029/2000GL012805 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 461CV UT WOS:000170348100012 ER PT J AU Diner, DJ Abdou, WA Bruegge, CJ Conel, JE Crean, KA Gaitley, BJ Helmlinger, MC Kahn, RA Martonchik, JV Pilorz, SH Holben, BN AF Diner, DJ Abdou, WA Bruegge, CJ Conel, JE Crean, KA Gaitley, BJ Helmlinger, MC Kahn, RA Martonchik, JV Pilorz, SH Holben, BN TI MISR aerosol optical depth retrievals over southern Africa during the SAFARI-2000 dry season campaign SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID IMAGING SPECTRORADIOMETER; LAND AB This paper presents, for the first time, retrievals of aerosol optical depths from Multi-angle Imaging Spectro-Radiometer (MISR) observations over land. Application of the MISR operational algorithm to data taken over southern Africa during the SAFARI-2000 dry season campaign yields results that compare favorably with coincident surface-based measurements taken by the AERONET radiometer network. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Diner, DJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 169-237, Pasadena, CA 91109 USA. RI Kahn, Ralph/D-5371-2012 OI Kahn, Ralph/0000-0002-5234-6359 NR 18 TC 90 Z9 95 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 AUG 15 PY 2001 VL 28 IS 16 BP 3127 EP 3130 DI 10.1029/2001GL013188 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 461CV UT WOS:000170348100017 ER PT J AU Azeem, SMI Palo, SE Wu, DL Froidevaux, L AF Azeem, SMI Palo, SE Wu, DL Froidevaux, L TI Observations of the 2-day wave in UARS MLS temperature and ozone measurements SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERE; MESOSPHERE; JANUARY AB Mesospheric ozone and temperature data obtained by the Microwave Limb Sounder (MLS) on board the Upper Atmosphere Research Satellite (UARS) have been analyzed to elucidate quasi-two day wave activity. Data from January 1993 were analyzed to investigate the evolution and structure of the two day wave. During this period, the wave amplitude in ozone attained its maximum value in late January near 30 degrees in the summer hemisphere. The evolution of the wave amplitude indicates a shift of the peak amplitude to higher latitudes with increasing height. Correlation of the two day wave phase observed in MLS ozone and temperature measurements indicates that the perturbations are out of phase. During the same period, the amplitudes of the perturbations in temperature and ozone were positively correlated. The results suggest that the variations in ozone are photochemically driven in the mesosphere region via changes in reaction rates that are strongly temperature dependent. C1 Univ Colorado, Boulder, CO 80309 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Azeem, SMI (reprint author), Univ Colorado, UCB 429, Boulder, CO 80309 USA. RI Wu, Dong/D-5375-2012; OI PALO, SCOTT/0000-0002-4729-4929 NR 12 TC 17 Z9 19 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 15 PY 2001 VL 28 IS 16 BP 3147 EP 3150 DI 10.1029/2001GL013119 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 461CV UT WOS:000170348100022 ER PT J AU Richard, EC Aikin, KC Andrews, AE Daube, BC Gerbig, C Wofsy, SC Romashkin, PA Hurst, DF Ray, EA Moore, FL Elkins, JW Deshler, T Toon, GC AF Richard, EC Aikin, KC Andrews, AE Daube, BC Gerbig, C Wofsy, SC Romashkin, PA Hurst, DF Ray, EA Moore, FL Elkins, JW Deshler, T Toon, GC TI Severe chemical ozone loss inside the Arctic Polar Vortex during winter 1999-2000 inferred from in-situ airborne measurements (vol 28, pg 2197, 2001) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Correction C1 NOAA, Aeron Lab, Boulder, CO 80303 USA. Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO USA. Harvard Univ, Div Appl Sci, Cambridge, MA 02138 USA. Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Univ Wyoming, Dept Atmospher Sci, Laramie, WY 82071 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Richard, EC (reprint author), NOAA, Aeron Lab, 325 Broadway, Boulder, CO 80303 USA. RI Aikin, Kenneth/I-1973-2013; Gerbig, Christoph/L-3532-2013; Hurst, Dale/D-1554-2016 OI Gerbig, Christoph/0000-0002-1112-8603; Hurst, Dale/0000-0002-6315-2322 NR 1 TC 1 Z9 1 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 15 PY 2001 VL 28 IS 16 BP 3167 EP 3167 DI 10.1029/2001GL013627 PG 1 WC Geosciences, Multidisciplinary SC Geology GA 461CV UT WOS:000170348100027 ER PT J AU Venegas, SA Drinkwater, MR AF Venegas, SA Drinkwater, MR TI Sea ice, atmosphere and upper ocean variability in the Weddell Sea, Antarctica SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SOUTHERN-OCEAN; CLIMATE VARIABILITY; COASTAL POLYNYAS; BOTTOM WATER; INTERANNUAL VARIABILITY; SURFACE-TEMPERATURE; CIRCUMPOLAR WAVE; MOTION; CIRCULATION; EXCHANGE AB A frequency domain singular value decomposition is performed on 20 years (1979-1998) of monthly sea ice concentration, sea ice drift and sea level pressure data in the Weddell Sea, Antarctica. Interannual oscillations with periods of around 3-4 years are found to dominate the variability in this region. Anomalous atmospheric patterns periodically reach the 'Weddell Sea from the west and perturb the sea ice circulation and distribution in the Weddell Gyre through changes in the intensity and direction of the climatological winds. Sea ice accumulates in the southeastern Weddell Sea every 3-4 years owing to two atmospherically driven processes: (1) weak ice export to the north due to a weak northward branch of the gyre (driven by weak southerly winds) and (2) large ice import from the east due to a strong East Wind Drift (driven by strong easterly winds along the coast). The opposite situation gives rise to a depletion of sea ice in the same region half a cycle later. Sea ice anomalies are then advected north-northeastward before turning eastward in the gyre circulation. The eastward propagation of ice anomalies along the ice margin accounts for the passage of the Antarctic Circumpolar Wave through the Atlantic sector of the Southern Ocean. A low frequency signal is also detected in the Weddell Sea variations, albeit rather speculatively in this 20-year-long record. Sea ice variability on this timescale appears to be associated with a change in the shape and characteristics of the Weddell Gyre circulation around 1990. This mode of variability implicates feedbacks between the gyre and Weddell Deep Water temperature variations, whose impact is observed near the Maud Rise topographic feature. C1 Univ Copenhagen, Niels Bohr Inst Astron Phys & Geophys, Danish Ctr Earth Syst Sci, DK-2100 Copenhagen, Denmark. European Space Agcy, Estec, Oceans Ice Unit,APP, FSO, NL-2200 AG Noordwijk, Netherlands. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Venegas, SA (reprint author), Univ Copenhagen, Niels Bohr Inst Astron Phys & Geophys, Danish Ctr Earth Syst Sci, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark. OI Drinkwater, Mark/0000-0002-9250-3806 NR 66 TC 37 Z9 41 U1 1 U2 9 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 2001 VL 106 IS C8 BP 16747 EP 16765 DI 10.1029/2000JC000594 PG 19 WC Oceanography SC Oceanography GA 460UB UT WOS:000170326000010 ER PT J AU Garcia-Gorriz, E Carr, ME AF Garcia-Gorriz, E Carr, ME TI Physical control of phytoplankton distributions in the Alboran Sea: A numerical and satellite approach SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID MEDITERRANEAN-SEA; ANTICYCLONIC GYRES; STRAIT; CIRCULATION; GIBRALTAR; DYNAMICS; WATER; ZONE AB This study aims to identify the controlling processes of phytoplankton distributions in the Alboran Sea (western Mediterranean Sea). A three-dimensional primitive equation model, the Navy Layered Ocean Model, forced by satellite-measured winds from the European Remote Sensing satellites (ERS-1 and 2) and the NASA scatterometer (NSCAT), is used to examine circulation from January 1996 to December 1998 and to simulate the distribution of passive tracers within the basin. We discuss the impact of the basin circulation on the observed patterns of chlorophyll observed by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the Ocean Color and Temperature Scanner (OCTS). The upper layer is fertilized with nutrients which are transported by the western anticyclonic gyre front the coastal upwelling sites in the northwest. Nutrients are supplied also by eddy-induced upwelling in the periphery of the gyre path (found to be 20 to 60% of the supply due to advection in the present simulations). Circulation controls the supply of nutrients and the observed phytoplankton biomass in the upper layer during the nonbloom months (late spring, summer, and early fall). During the bloom regime, seasonal destratification is the dominant fertilizing process for the entire basin. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP European Commiss, Joint Res Ctr, TP-272, I-21020 Ispra, VA, Italy. EM elisa.garcia-gorriz@jrc.it; mec@pacific.jpl.nasa.gov NR 25 TC 39 Z9 39 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9275 EI 2169-9291 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD AUG 15 PY 2001 VL 106 IS C8 BP 16795 EP 16805 DI 10.1029/1999JC000029 PG 11 WC Oceanography SC Oceanography GA 460UB UT WOS:000170326000013 ER PT J AU Giauque, PH Cherry, HB Nicolet, MA AF Giauque, PH Cherry, HB Nicolet, MA TI Thermal stability of amorphous thin films: Ti3Si1O8 vs. TiO2 and mictamict compounds SO THIN SOLID FILMS LA English DT Article DE mictamict compounds; amorphous materials; optical coatings; silicon oxide; titanium oxide ID CHEMICAL-VAPOR-DEPOSITION; SI-N FILMS; DIFFUSION-BARRIERS; MIXED FILMS; COEVAPORATION; EVAPORATION; SYSTEM; STRESS AB We have. synthesized amorphous Ti3Si1O8 films 220 am thick by rf sputtering of a Ti3Si target with a mixed argon-oxygen gas. The composition and structure of the films, as-deposited and upon thermal annealing in vacuum, was monitored by 2 MeV He-4(2+) backscattering spectrometry, X-ray diffraction, and transmission electron microscopy. We contrast these results against those obtained for TiO2 films 100 and 300 nm thick obtained by the same deposition process from a titanium target. The results confirm earlier reports that show that the incorporation of SiO2, in a TiO2 film raises the crystallization temperature. We point out that Ti-Si-O films share this phenomenon with other ternary films. They form a particular class of materials, the mictamict compounds, of which Ti-Si-O films are but one member. (C) 2001 Elsevier Science BY. All rights reserved. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Nicolet, MA (reprint author), CALTECH, Pasadena, CA 91125 USA. NR 30 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0040-6090 J9 THIN SOLID FILMS JI Thin Solid Films PD AUG 15 PY 2001 VL 394 IS 1-2 BP 136 EP 141 PG 6 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA 466ZG UT WOS:000170675600018 ER PT J AU Quackenbush, SL Casey, RN Murcek, RJ Paul, TA Work, TM Limpus, CJ Chaves, A duToit, L Perez, JV Aguirre, AA Spraker, TR Horrocks, JA Vermeer, LA Balazs, GH Casey, JV AF Quackenbush, SL Casey, RN Murcek, RJ Paul, TA Work, TM Limpus, CJ Chaves, A duToit, L Perez, JV Aguirre, AA Spraker, TR Horrocks, JA Vermeer, LA Balazs, GH Casey, JV TI Quantitative analysis of herpesvirus sequences from normal tissue and fibropapillomas of marine turtles with real-time PCR SO VIROLOGY LA English DT Article DE herpesvirus; fibropapilloma; real-time PCR; marine turtles ID GREEN TURTLE; CHELONIA-MYDAS; CUTANEOUS FIBROPAPILLOMAS AB Quantitative real-time PCR has been used to measure fibropapilloma-associated turtle herpesvirus (FPTHV) pol DNA loads in fibropapillomas, fibromas, and uninvolved tissues of green, loggerhead, and olive ridley turtles from Hawaii, Florida, Costa Rica, Australia, Mexico, and the West Indies. The viral DNA loads from tumors obtained from terminal animals were relatively homogenous (range 2-20 copies/cell), whereas DNA copy numbers from biopsied tumors and skin of otherwise healthy turtles displayed a wide variation (range 0.001-170 copies/cell) and may reflect the stage of tumor development. FPTHV DNA loads in tumors were 2.5-4.5 logs higher than in uninvolved skin from the same animal regardless of geographic location, further implying a role for FPTHV in the etiology of fibropapillomatosis. Although FPTHV pol sequences amplified from tumors are highly related to each other, single signature amino acid substitutions distinguish the Australia/Hawaii, Mexico/Costa Rica, and Florida/Caribbean groups. (C) 2001 Academic Press. C1 Cornell Univ, Coll Vet Med, Dept Microbiol & Immunol, Vet Med Ctr C5153, Ithaca, NY 14853 USA. Univ Kansas, Dept Mol Biosci, Lawrence, KS 66045 USA. US Geol Survey, Natl Wildlife Hlth Ctr, Honolulu Field Stn, Honolulu, HI 96850 USA. Queensland Parks & Wildlife Serv, Brisbane, Qld 4002, Australia. Inst Nacl Pesca, Ctr Mexicano Tortuga, Puerto Angel, Oaxaca National, Mexico. Wildlife Trust, Prospect Pk, PA 19076 USA. Colorado State Univ, State Vet Diagnost Lab, Ft Collins, CO 80523 USA. Univ W Indies, Dept Biol & Chem Sci, Cave Hill, St Michael, Barbados. Bellairs Res Inst, Barbados Sea Turtle Project, St James, Barbados. NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, Honolulu, HI 96822 USA. RP Casey, JV (reprint author), Cornell Univ, Coll Vet Med, Dept Microbiol & Immunol, Vet Med Ctr C5153, Ithaca, NY 14853 USA. RI Work, Thierry/F-1550-2015 OI Work, Thierry/0000-0002-4426-9090 FU NCI NIH HHS [5T32CA09682] NR 17 TC 44 Z9 47 U1 0 U2 10 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0042-6822 J9 VIROLOGY JI Virology PD AUG 15 PY 2001 VL 287 IS 1 BP 105 EP 111 DI 10.1006/viro.2001.1023 PG 7 WC Virology SC Virology GA 465TT UT WOS:000170606600012 PM 11504546 ER PT J AU Johnson, PV Kanik, I AF Johnson, PV Kanik, I TI Inelastic differential electron scattering cross sections of molecular oxygen (O-2) in the 20-100 eV impact energy range SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID EXCITATION AB We report absolute differential electron scattering cross sections (DCSs) of molecular oxygen (O-2) at 20, 30, 50 and 100 eV impact energies (E-0). DCSs were measured for inelastic features in the 6.5-12.5 energy-loss range including the Schumann-Runge (SR) continuum, the longest band (LB) and the second band (2B) along with the summed DCS for the third band (3B) plus the 10.76 and 11.03 eV energy-loss features. Measurements were performed at scattering angles of 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees and 25 degrees using a conventional electrostatic electron energy-loss spectrometer. Inelastic electron energy-loss spectra Of O-2 were measured giving relative inelastic DCSs, which were then normalized via the relative flow technique using inelastic He and Ne transitions as standards. Past works (Trajmar et al 1972, Shyn et al 1994) have shown good relative agreement while displaying significant discrepancies in absolute terms. The current normalization technique represents an improvement over those employed in previous inelastic O-2 DCS work. As such, the present results serve to firmly establish the absolute normalization of these DCSs. Furthermore, the current results are able to provide an additional test of the relative angular distributions of previous works throughout the important low-angle region where the DCSs undergo the most rapid change. This paper also represents the first measurements of inelastic O-2 DCSs to extend right down to the forward-scattering limit. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnson, PV (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Johnson, Paul/D-4001-2009 OI Johnson, Paul/0000-0002-0186-8456 NR 17 TC 5 Z9 5 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD AUG 14 PY 2001 VL 34 IS 15 BP 3041 EP 3051 DI 10.1088/0953-4075/34/15/310 PG 11 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 470DM UT WOS:000170855200015 ER PT J AU Murray, AE Lies, D Li, G Nealson, K Zhou, J Tiedje, JM AF Murray, AE Lies, D Li, G Nealson, K Zhou, J Tiedje, JM TI DNA/DNA hybridization to microarrays reveals gene-specific differences between closely related microbial genomes SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID DNA ARRAYS; IDENTIFICATION; EXPRESSION; RNA; AMPLIFICATION; SHEWANELLA; SEQUENCES; SCALE; PCR AB DNA microarrays constructed with full length ORFs from Shewanella oneidensis, MR-1, were hybridized with genomic DNA from nine other Shewanella species and Escherichia coli K-12. This approach enabled visualization of relationships between organisms by comparing individual ORF hybridizations to 164 genes and is further amenable to high-density high-throughput analyses of complete microbial genomes. Conserved genes (arcA and ATP synthase) were identified among all species investigated. The mtr operon, which is involved in iron reduction, was poorly conserved among other known metal-reducing Shewanella species. Results were most informative for closely related organisms with small subunit rRNA sequence similarities greater than 93% and gyrB sequence similarities greater than 80%. At this level of relatedness, the similarity between hybridization profiles was strongly correlated with sequence divergence in the gyrB gene. Results revealed that two strains of S. oneidensis (MR-1 and DLM17) were nearly identical, with only 3% of the ORFs hybridizing poorly, in contrast to hybridizations with Shewanella putrefaciens, formerly considered to be the same species as MR-1, in which 63% of the ORFs hybridized poorly (log ratios below -0.75). Genomic hybridizations showed that genes in operons had consistent levels of hybridization across an operon in comparison to a randomly sampled data set, suggesting that similar applications will be informative for identification of horizontally acquired genes. The full value of microbial genomic hybridizations lies in providing the ability to understand and display specific differences between closely related organisms providing a window into understanding microheterogeneity, bacterial speciation, and taxonomic relationships. C1 Desert Res Inst, Reno, NV 89512 USA. Jet Prop Lab, Dept Geol & Planetary Sci, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91109 USA. Oak Ridge Natl Lab, Div Environm Sci, Oak Ridge, TN 37831 USA. Michigan State Univ, Ctr Microbial Ecol, E Lansing, MI 48824 USA. RP Murray, AE (reprint author), Desert Res Inst, Reno, NV 89512 USA. NR 31 TC 128 Z9 135 U1 1 U2 7 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 14 PY 2001 VL 98 IS 17 BP 9853 EP 9858 DI 10.1073/pnas.171178898 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 464NX UT WOS:000170539600071 PM 11493693 ER PT J AU Sarkisov, SS Curley, MJ Kukhtarev, NV Fields, A Adamovsky, G Smith, CC Moore, LE AF Sarkisov, SS Curley, MJ Kukhtarev, NV Fields, A Adamovsky, G Smith, CC Moore, LE TI Holographic surface gratings in iron-doped lithium niobate SO APPLIED PHYSICS LETTERS LA English DT Article ID PHOTOREFRACTIVE CRYSTALS; WAVES AB Surface gratings associated with holographic volume gratings in photorefractive crystals of iron-doped lithium niobate have been studied using diffraction of a reflected probe beam and high-resolution phase-shifted interferometric profilometry. Both techniques show that the surface gratings exist in the form of periodical corrugations of the same period as that of the volume grating. The maximum amplitude of the periodical surface relief measured by both techniques is close to 6.5 nm. We also demonstrated that the periodical electric forces on the surface were capable of assembling polystyrene microspheres along the fringes of the grating. Large amplitude of the periodic electric field (1.6x10(4) V/cm) is associated with the photogalvanic effect. (C) 2001 American Institute of Physics. C1 Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Sarkisov, SS (reprint author), Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. NR 20 TC 12 Z9 12 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD AUG 13 PY 2001 VL 79 IS 7 BP 901 EP 903 DI 10.1063/1.1394176 PG 3 WC Physics, Applied SC Physics GA 459XV UT WOS:000170277500003 ER PT J AU Barstow, MA Bannister, NP Holberg, JB Hubeny, I Bruhweiler, FC Napiwotzki, R AF Barstow, MA Bannister, NP Holberg, JB Hubeny, I Bruhweiler, FC Napiwotzki, R TI Far-ultraviolet spectroscopy of the hot DA white dwarf WD 2218+706 (DeHt5) with STIS SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE stars : abundances; stars : atmospheres; stars : individual : WD 2218+706; white dwarfs; planetary nebulae : individual : DeHt5; ultraviolet : stars ID MASS-LOSS; STELLAR EVOLUTION; HELIUM; STARS; MODEL; ATMOSPHERES; ABUNDANCE; G191-B2B; GD-50 AB We report a study of the photospheric composition of the hot DA white dwarf WD 2218+706, which is also the central star of the old planetary nebula DeHt5. Helium is detected in the far-UV spectrum. In addition, the star clearly contains significant quantities of elements heavier than He at abundances generally a factor of 2 to 10 higher than those found in the archetypal heavy element-rich DA G191-B2B. This is the first detection of trace He using the He II gimel 1640 line in an isolated DA white dwarf, but the low surface gravity is more indicative of a binary evolution route from the red giant branch rather than a path along the asymptotic giant branch (AGB) as a single star. However, the absence of any evidence for a companion star and the uncertainty in the measured mass for WD 2218+706 still allow the possibility of an origin along an AGB evolutionary track. We reanalyse the existing optical spectra of WD 2218+706 using our latest pure H and heavy element-rich model atmospheres, obtaining a good match between the observed and synthetic spectra with either set of models. We find little evidence of any inconsistency in the temperature required to fit individual Balmer lines, as reported elsewhere for this star. Any discrepancies we see are confined to the Ha line and the core of HG but they do not compromise our analysis. C1 Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Astron & Solar Phys Lab, GSFC, Greenbelt, MD 20711 USA. Catholic Univ Amer, Dept Phys, IACS, Washington, DC 20064 USA. Dr Remeis Sternwarte, D-96049 Bamberg, Germany. RP Barstow, MA (reprint author), Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England. EM mab@star.le.ac.uk NR 36 TC 16 Z9 16 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 11 PY 2001 VL 325 IS 3 BP 1149 EP 1156 DI 10.1046/j.1365-8711.2001.04533.x PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 466VG UT WOS:000170666400022 ER PT J AU Gierlinski, M Maciolek-Niedzwiecki, A Ebisawa, K AF Gierlinski, M Maciolek-Niedzwiecki, A Ebisawa, K TI Application of a relativistic accretion disc model to X-ray spectra of LMC X-1 and GRO J1655-40 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; relativity; stars : individual : GRO J 1655-40; stars : individual : LMC X-1; X-rays : stars ID BLACK-HOLE CANDIDATES; QUASI-PERIODIC OSCILLATIONS; SUPERLUMINAL SOURCE; OPTICAL COUNTERPART; CYGNUS X-1; SOFT STATE; MASS; BINARIES; LMC-X-1; GINGA AB We present a general relativistic accretion disc model and its application to the soft-state X-ray spectra of black hole binaries. The model assumes a flat, optically thick disc around a rotating Kerr black hole. The disc locally radiates away the dissipated energy as a blackbody. Special and general relativistic effects influencing photons emitted by the disc are taken into account. The emerging spectrum, as seen by a distant observer, is parametrized by the black hole mass and spin, the accretion rate, the disc inclination angle and the inner disc radius. We fit the ASCA soft-state X-ray spectra of LMC X-1 and GRO J1655-40 by this model. We find that, having additional limits on the black hole mass and inclination angle from optical/UV observations, we can constrain the black hole spin from X-ray data. In LMC X-1 the constraint is weak, and we can only rule out the maximally rotating black hole. In GRO J1655-40 we can limit the spin much better, and we find 0.68 less than or equal to a less than or equal to 0.88. Accretion discs in both sources are radiation-pressure dominated. We do not find Compton reflection features in the spectra of any of these objects. C1 Jagiellonian Univ, Astron Observ, PL-30244 Krakow, Poland. Nicholas Copernicus Astron Ctr, PL-00716 Warsaw, Poland. Univ Lodz, Dept Phys, PL-90236 Lodz, Poland. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. RP Gierlinski, M (reprint author), Univ Durham, Dept Phys, Sci Labs, South Rd, Durham DH1 3LE, England. OI Gierlinski, Marek/0000-0001-9149-3514 NR 67 TC 67 Z9 68 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 AUG 11 PY 2001 VL 325 IS 3 BP 1253 EP 1265 DI 10.1046/j.1365-8711.2001.04540.x PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 466VG UT WOS:000170666400032 ER PT J AU Collinge, MJ Brandt, WN Kaspi, S Crenshaw, DM Elvis, M Kraemer, SB Reynolds, CS Sambruna, RM Wills, BJ AF Collinge, MJ Brandt, WN Kaspi, S Crenshaw, DM Elvis, M Kraemer, SB Reynolds, CS Sambruna, RM Wills, BJ TI High-resolution X-ray and ultraviolet spectroscopy of the complex intrinsic absorption in NGC 4051 with Chandra and the Hubble Space Telescope SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 4051); galaxies : nuclei; galaxies : Seyfert; ultraviolet : galaxies; X-rays : galaxies AB We present the results from simultaneous observations of the narrow-line Seyfert 1 galaxy NGC 4051 with the Chandra High Energy Transmission Grating Spectrometer and the Hubble Space Telescope Space Telescope Imaging Spectrograph. The X-ray grating spectrum reveals absorption and emission lines from hydrogen-like and helium-like ions of O, Ne, Mg, and Si. We resolve two distinct X-ray absorption systems: a high-velocity blueshifted system at -2340 +/- 130 km s(-1) and a low-velocity blue-shifted system at -600 +/- 130 km s(-1). In the UV spectrum we detect strong absorption, mainly from C IV, N V, and Si IV, that is resolved into as many as nine different intrinsic absorption systems with velocities between -650 and 30 km s(-1). Although the low-velocity X-ray absorption is consistent in velocity with many of the UV absorption systems, the high-velocity X-ray absorption seems to have no UV counterpart. In addition to the absorption and emission lines, we also observe rapid X-ray variability and a state of low X-ray flux during the last approximate to 15 ks of the observation. NGC 4051 has a soft X-ray excess that we fit in both the high and low X-ray flux states. The high-resolution X-ray spectrum directly reveals that the soft excess is not composed of narrow emission lines and that it has significant spectral curvature. A power-law model fails to fit it, while a blackbody produces a nearly acceptable fit. We compare the observed spectral variability with the results of previous studies of NGC 4051. C1 Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Colorado, JILA, Boulder, CO 80303 USA. George Mason Univ, Dept Phys & Astron, Fairfax, VA 22030 USA. George Mason Univ, Sch Computat Sci, Fairfax, VA 22030 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. RP Collinge, MJ (reprint author), Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. RI Brandt, William/N-2844-2015 OI Brandt, William/0000-0002-0167-2453 NR 0 TC 101 Z9 101 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2001 VL 557 IS 1 BP 2 EP 17 DI 10.1086/321635 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XF UT WOS:000170558100002 ER PT J AU Kraemer, SB Crenshaw, DM Gabel, JR AF Kraemer, SB Crenshaw, DM Gabel, JR TI STIS echelle observations of the intrinsic UV absorption in the Seyfert 1 galaxy NGC 3783 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 3783); galaxies : Seyfert; ultraviolet : galaxies; X-rays : galaxies ID X-RAY-ABSORPTION; C-IV ABSORPTION; ACTIVE GALACTIC NUCLEI; ULTRAVIOLET; LINES; NGC-3783; NGC-5548; DISCOVERY; CONTINUUM; NGC-4151 AB We present observations of the UV absorption lines in the Seyfert 1 galaxy NGC 3783, obtained with the medium resolution (lambda/Delta lambda approximate to 40,000) echelle gratings of the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST). The spectra reveal the presence of three kinematic components of absorption in Ly alpha, C IV, and N V, at radial velocities of -1365, -548, and -724 km s(-1) with respect to the systemic velocity of the host galaxy (components 1, 2 and 3, respectively); component 1 also shows absorption by Si IV. Component 3 was not detected in any of the earlier Goddard High Resolution Spectrograph (GHRS) spectra, and the C IV absorption in the other components has changed since the most recent GHRS observation obtained similar to5 yr earlier. Somewhat unexpectedly, each component has a covering factor (of the continuum source+broad emission line region) of similar to0.6. We have calculated photoionization models to match the UV column densities in each of the three components. The models predict a zone characterized by high-ionization parameter (U = 0.65-0.80) and column density (6.4 x 10(20)-1.5 x 10(21) cm(-2)) for each component, and a second, low-ionization (U = 0.0018) and low column density (4.9 x 10(18) cm(-2)) zone for component 1. Based on the model results, there should be strong absorption in the bandpass of the Far Ultraviolet Spectroscopic Explorer (FUSE), 912-1200 Angstrom, including saturated O VI lines at each component velocity. The models also predict large O VII and O VIII column densities, but suggest that the UV absorbers cannot account for all of the X-ray absorption detected in recent Chandra spectra. Finally, there is no evidence for a correlation between the characteristics of the UV absorbers and the UV continuum flux, and, by inference, the ionizing continuum. Hence, we suggest that the variations observed in the GHRS and STIS spectra are due in a large part to changes in the column densities of the absorbers as the result of transverse motion. C1 Catholic Univ Amer, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kraemer, SB (reprint author), Catholic Univ Amer, Code 681, Greenbelt, MD 20771 USA. NR 30 TC 32 Z9 32 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2001 VL 557 IS 1 BP 30 EP 38 DI 10.1086/321619 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XF UT WOS:000170558100005 ER PT J AU Levenson, NA Fernandes, RC Weaver, KA Heckman, TM Storchi-Bergmann, T AF Levenson, NA Fernandes, RC Weaver, KA Heckman, TM Storchi-Bergmann, T TI The obscuring starburst of NGC 6221 and implications for the hard X-ray background SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 6221); galaxies : Seyfert; galaxies : starburst; X-rays : diffuse background; X-rays : galaxies ID STAR-FORMING GALAXIES; INFRARED SPECTRAL DISTRIBUTIONS; GALACTIC NUCLEUS CONNECTION; EMISSION-LINE GALAXIES; SEYFERT 2 GALAXIES; ROSAT DEEP SURVEY; ALL-SKY SURVEY; ACTIVE GALAXIES; OPTICAL EXTINCTION; ASCA OBSERVATIONS AB We present NGC 6221 as a case study of "X-ray-loud composite galaxies," which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in X-rays. The net optical spectrum of NGC 6221 is properly characterized as a starburst galaxy, but in X-rays, NGC 6221 is similar to Seyfert 1 galaxies, exhibiting a power-law continuum spectrum, a broad Fe K alpha line, and continuum variability on timescales of days and years. High-resolution images reveal that the detected active nucleus is relatively weak, not only at optical, but also at near-infrared wavelengths. An obscuring starburst, in which the interstellar gas and dust associated with the starburst conceal the active nucleus, accounts for these peculiar features. We demonstrate quantitatively that obscuration by column density N-H = 10(22) cm(-2) combined with relatively weak intrinsic nuclear activity can produce an optical spectrum that is characteristic of the surrounding starburst alone. While optical surveys would not identify the active nuclei that make these galaxies significant X-ray sources, such galaxies may, in fact, be important contributors to the X-ray background. C1 Johns Hopkins Univ, Dept Phys & Astron, Bloomberg Ctr, Baltimore, MD 21218 USA. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Fed Rio Grande do Sul, Inst Fis, BR-91501970 Porto Alegre, RS, Brazil. RP Levenson, NA (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Bloomberg Ctr, Baltimore, MD 21218 USA. EM levenson@pha.jhu.edu; cid@pha.jhu.edu; kweaver@cleo.gsfc.nasa.gov; heckman@pha.jhu.edu; thaisa@if.ufrgs.br RI Fernandes, Roberto/M-7334-2014 OI Fernandes, Roberto/0000-0001-9672-0296 NR 70 TC 19 Z9 19 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 10 PY 2001 VL 557 IS 1 BP 54 EP 66 DI 10.1086/321656 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XF UT WOS:000170558100007 ER PT J AU Silberman, L Dekel, A Eldar, A Zehavi, I AF Silberman, L Dekel, A Eldar, A Zehavi, I TI Cosmological density and power spectrum from peculiar velocities: Nonlinear corrections and principal component analysis SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; cosmology : theory; dark matter; galaxies : clusters : general; galaxies : distances and redshifts; large-scale structure of universe ID TULLY-FISHER RELATION; LARGE-SCALE STRUCTURE; REDSHIFT SURVEY; BACKGROUND-RADIATION; INITIAL FLUCTUATIONS; LIKELIHOOD ANALYSIS; DISTANCE DATA; HUBBLE FLOW; SC GALAXIES; UNIVERSE AB We allow for nonlinear effects in the likelihood analysis of galaxy peculiar velocities and obtain similar to 35% lower values for the cosmological density parameter Omega (m) and for the amplitude of mass density fluctuations sigma (8) Omega (0.6)(m). This result is obtained under the assumption that the power spectrum in the linear regime is of the flat Lambda CDM model (h = 0.65, n = 1, COBE normalized) with only Omega (m) as a free parameter. Since the likelihood is driven by the nonlinear regime, we "break" the power spectrum at k(b) similar to 0.2 (h(-1) Mpc)(-1) and fit a power law at k > k(b). This allows for independent matching of the nonlinear behavior and an unbiased fit in the linear regime. The analysis assumes Gaussian fluctuations and errors and a linear relation between velocity and density. Tests using mock catalogs that properly simulate nonlinear effects demonstrate that this procedure results in a reduced bias and a better fit. We find for the Mark III and SFI data Omega (m) = 0.32 +/- 0.06 and 0.37 +/- 0.09, respectively, with sigma (8) Omega (0.6)(m) = 0.49 +/- 0.06 and 0.63 +/- 0.08, in agreement with constraints from other data. The quoted 90% errors include distance errors and cosmic variance, for fixed values of the other parameters. The improvement in the likelihood due to the nonlinear correction is very significant for Mark III and moderately significant for SFI. When allowing deviations from Lambda CDM, we find an indication for a wiggle in the power spectrum: an excess near k similar to 0.05 (h(-1) Mpc)(-1) and a deficiency at k similar to 0.1 (h(-1) Mpc)(-1), or a "cold flow." This may be related to the wiggle seen in the power spectrum from redshift surveys and the second peak in the cosmic microwave background (CMB) anisotropy. A chi (2) test applied to modes of a principal component analysis (PCA) shows that the nonlinear procedure improves the goodness of fit and reduces a spatial gradient that was of concern in the purely linear analysis. The PCA allows us to address spatial features of the data and to evaluate and fine-tune the theoretical and error models. It demonstrates in particular that the models used are appropriate for the cosmological parameter estimation performed. We address the potential for optimal data compression using PCA. C1 Hebrew Univ Jerusalem, Racah Inst Phys, IL-91904 Jerusalem, Israel. Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Grp, Batavia, IL 60510 USA. RP Silberman, L (reprint author), Hebrew Univ Jerusalem, Racah Inst Phys, IL-91904 Jerusalem, Israel. NR 72 TC 25 Z9 25 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2001 VL 557 IS 1 BP 102 EP 116 DI 10.1086/321663 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XF UT WOS:000170558100010 ER PT J AU Zhao, JW Kosovichev, AG Duvall, TL AF Zhao, JW Kosovichev, AG Duvall, TL TI Investigation of mass flows beneath a sunspot by time-distance helioseismology SO ASTROPHYSICAL JOURNAL LA English DT Article DE methods : data analysis; Sun : helioseismology; sunspots ID MAGNETIC-FLUX TUBES; TOMOGRAPHY AB A time-distance helioseismic technique is employed to analyze a set of high-resolution Dopplergram observations of a large sunspot by SOHO/MDI on 1998 June 18. A regularized, damped least-squares inversion is applied to the measurements of travel times to infer mass flows around the sunspot below the solar surface. Powerful converging and downward directed flows are detected at depths of 1.5-5 Mm, which may provide observational evidence for the downdrafts and vortex flows that were suggested by Parker for a cluster model of sunspots. Strong outflows extending more than 30 Mm are found below the downward and converging flows. It is suggested that the sunspot might be a relatively shallow phenomenon, with a depth of 5-6 Mm, as defined by its thermal and hydrodynamic properties. A strong mass flow across the sunspot is found at depths of 9-12 Mm, which may provide more evidence in support of the cluster model, as opposed to the monolithic sunspot model. We suggest that a new magnetic emergence that was found 5 hr after our analysis period is related to this mass flow. C1 Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Zhao, JW (reprint author), Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA. RI Zhao, Junwei/A-1177-2007; Duvall, Thomas/C-9998-2012 NR 22 TC 196 Z9 198 U1 2 U2 5 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 10 PY 2001 VL 557 IS 1 BP 384 EP 388 DI 10.1086/321491 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XF UT WOS:000170558100037 ER PT J AU Angelini, L Loewenstein, M Mushotzky, RF AF Angelini, L Loewenstein, M Mushotzky, RF TI The X-ray globular cluster population in NGC 1399 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : elliptical and lenticular, cD; galaxies : individual (NGC 1399) globular clusters : general; X-rays : binaries; X-rays : galaxies ID EARLY-TYPE GALAXIES; BINARIES; ASCA AB We report on the Chandra observations of the elliptical galaxy NGC 1399, concentrating on the X-ray sources identified with globular clusters (GCs). A large fraction of the 2-10 keV X-ray emission in the 8' x 8' Chandra image is resolved into point sources with luminosities greater than or equal to5 x 10(37) ergs s(-1). These sources are most likely low-mass X-ray binaries (LMXBs). In a region imaged by the Hubble Space Telescope, about 70% of the X-ray sources are located within GCs. This association suggests that in giant elliptical galaxies luminous X-ray binaries preferentially form in GCs. Many of the GC sources have super-Eddington luminosities (for an accreting neutron star), and their average luminosity is higher than the non-GC sources. The X-ray spectral properties of both GC and non-GC sources are similar to those of LMXBs in our Galaxy. Two of the brightest sources, one of which is in a GC, have an ultrasoft spectrum, similar to that seen in the high state of black hole candidates. The "apparent" super-Eddington luminosity in many cases may be due to multiple LMXB systems within individual GCs but with some of the most extremely luminous systems containing massive black holes. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Angelini, L (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 24 TC 92 Z9 92 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2001 VL 557 IS 1 BP L35 EP L38 DI 10.1086/323026 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XG UT WOS:000170558200009 ER PT J AU Brown, GV Beiersdorfer, P Chen, H Chen, MH Reed, KJ AF Brown, GV Beiersdorfer, P Chen, H Chen, MH Reed, KJ TI Diagnostic utility of the relative intensity of 3C to 3D in Fe XVII SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; line : identification; stars : coronae; Sun : Corona; Sun : X-rays, gamma rays; X-rays : general ID X-RAY-SPECTRA; INNER-SHELL EXCITATION; LABORATORY MEASUREMENTS; COLLISION STRENGTHS; ELECTRON-BEAM; LINE EMISSION; ACTIVE-REGION; IONS; SPECTROMETER; TRANSMISSION AB The relative intensity R of the resonance and intercombination line in neon-like Fe XVII, located at 15.01 and 15.26 Angstrom, respectively, has been measured at the Lawrence Livermore National Laboratory electron beam ion trap EBIT-II as a function of the relative abundance of sodium-like Fe XVI. Our measurements identify several Fe xvi lines and one Fe XV line in this region. We show that an Fe xvi inner shell satellite line coincides with the intercombination line and can significantly reduce the apparent R. We measure R = 1.90 +/- 0.11 when the relative abundance of Fe XVI to Fe XVII is similar to1. This explains the anomalously low ratios observed in the solar and stellar coronae. The fact that the apparent relative intensity of the resonance and intercombination line in Fe XVII is sensitive to the strength of an Fe XVI inner shell satellite, and therefore, the relative abundance of Fe XVI to Fe XVII, makes the line ratio a diagnostic of temperature. C1 Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. RP Brown, GV (reprint author), Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 36 TC 65 Z9 67 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2001 VL 557 IS 1 BP L75 EP L78 DI 10.1086/323004 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XG UT WOS:000170558200018 ER PT J AU Chiang, J Blaes, O AF Chiang, J Blaes, O TI Thermal comptonization and disk thermal reprocessing in NGC 3516 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 3516); galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; BROAD-LINE REGION; ACCRETION DISKS; CONTINUUM; NGC-5548; MODELS; NGC-3516; STEPS; SIZE AB We present an application of the thermal Comptonization/disk reprocessing model recently proposed by Zdziarski, Lubinski, & Smith. We show that the absence of strong optical variations in the presence of strong concurrent X-ray variations, similar to those found by Hubble Space Telescope (HST)/Rossi X-Ray Timing Explorer (RXTE) monitoring observations of NGC 3516, can be explained by changing the geometry of the Comptonizing plasma rather than the accretion disk itself. The total X-ray luminosity of the Comptonizing plasma must decrease as its spatial extent increases. In contrast, the disk inner radius must be roughly fixed in order not to produce optical/ ultraviolet color variations stronger than observed. By including emission due to internal viscous dissipation in the disk, we can roughly match the optical and X-ray flux levels and variability amplitudes seen from NGC 3516 during the HST/RXTE campaign. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. RP Chiang, J (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. NR 19 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 2001 VL 557 IS 1 BP L15 EP L18 DI 10.1086/323077 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XG UT WOS:000170558200004 ER PT J AU Kashlinsky, A Hernandez-Monteagudo, C Atrio-Barandela, F AF Kashlinsky, A Hernandez-Monteagudo, C Atrio-Barandela, F TI Determining cosmic microwave background structure from its peak distribution SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : miscellaneous; methods : numerical ID AMERICAN TEST FLIGHT; BOOMERANG; SPECTRUM AB We present a new method for time-efficient and accurate extraction of the power spectrum from future cosmic microwave background (CMB) maps based on properties of peaks and troughs of the Gaussian CMB sky. We construct a statistic describing their angular clustering analogously to galaxies, the two-point angular correlation function xi (nu)(theta). We show that for increasing peak threshold nu, xi (nu)(theta) is strongly amplified and becomes measurable for nu greater than or similar to 1 on angular scales less than or equal to 10 degrees. Its amplitude at every scale depends uniquely on the CMB temperature correlation function, C(theta), and thus the measured xi (nu) can be uniquely inverted to obtain C(theta) and its Legendre transform, the power spectrum of the CMB field. Because in this method the CMB power spectrum is deduced from high peaks/troughs of the CMB field, the procedure takes only [f(nu)]N-2(2) operations, where f(nu) is the fraction of pixels with \deltaT\ greater than or equal to nu standard deviations in the map of N pixels and is, e.g., 0.045 and 0.01 for nu = 2 and 2.5, respectively. We develop theoretical formalism for the method and show with detailed simulations, using the Microwave Anisotropy Probe mission parameters, that this method allows us to determine very accurately the CMB power spectrum from the upcoming CMB maps in only similar to (10(-4) to 10(-3)) N-2 operations. C1 Raytheon ITSS, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Salamanca, Fac Ciencias, E-37008 Salamanca, Spain. RP Raytheon ITSS, Goddard Space Flight Ctr, Code 685, Greenbelt, MD 20771 USA. EM kashlinsky@stars.gsfe.nasa.gov; chm@otion.usal.es; atrio@orion.usal.es RI Atrio-Barandela, Fernando/A-7379-2017 OI Atrio-Barandela, Fernando/0000-0002-2130-2513 NR 23 TC 8 Z9 8 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 10 PY 2001 VL 557 IS 1 BP L1 EP L5 DI 10.1086/323172 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 464XG UT WOS:000170558200001 ER PT J AU Fibich, G Tsynkov, S AF Fibich, G Tsynkov, S TI High-order two-way artificial boundary conditions for nonlinear wave propagation with backscattering SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE artificial boundary conditions (ABCs); two-way ABCs; radiation; Helmholtz equation; nonlinearity; nonparaxiality; fourth-order schemes; self-focusing; backscattering ID SCHRODINGER-EQUATION; HELMHOLTZ-EQUATION; OPTICAL BEAMS; DOMAINS AB When solving linear scattering problems, one typically first solves for the impinging wave in the absence of obstacles. Then, using the linear superposition principle, the original problem is reduced to one which involves only the scattered wave (which is driven by the values of the impinging field at the surface of the obstacles). When the original domain is unbounded, special artificial boundary conditions (ABCs) have to be set at the outer (artificial) boundary of the finite computational domain in order to guarantee the reflectionless propagation of waves through this external artificial boundary. The situation becomes conceptually different when the propagation equation is nonlinear. In this case the impinging and scattered waves can no longer be separated, and the problem has to be solved in its entirety. In particular, the boundary on which the incoming field values are prescribed should transmit the given incoming waves in one direction and simultaneously be transparent to all the outgoing waves that travel in the opposite direction. We call such boundary conditions two-way ABCs. In the paper, we construct the two-way ABCs for the nonlinear Helmholtz equation, which models a continuous-wave laser hewn propagation in a medium with a Kerr nonlinear index of refraction. In this case, the forward propagation of the beam is accompanied by backscattering, i.e., generation of waves in the opposite direction to that of the incoming signal. Our two-way ABCs generate no reflection of the backscattered waves and at the same time impose the correct values of the incoming wave. The ABCs are obtained in the framework of a fourth-order accurate discretization to the Helmholtz operator inside the computational domain. The fourth-order convergence of our methodology is corroborated experimentally by solving linear model problems. We also present solutions in the nonlinear case using the two-way ABC which, unlike the traditional Dirichlet boundary condition approach, allows for direct calculation of the magnitude of backscattering. (C) 2001 Academic Press. C1 Tel Aviv Univ, Sch Math Sci, IL-69978 Tel Aviv, Israel. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Fibich, G (reprint author), Tel Aviv Univ, Sch Math Sci, IL-69978 Tel Aviv, Israel. RI Fibich, Gadi/A-4116-2008 NR 36 TC 20 Z9 23 U1 0 U2 0 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 AUG 10 PY 2001 VL 171 IS 2 BP 632 EP 677 DI 10.1006/jcph.2001.6800 PG 46 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 464AJ UT WOS:000170509800009 ER PT J AU Rame, E AF Rame, E TI The spreading of surfactant-laden liquids with surfactant transfer through the contact line SO JOURNAL OF FLUID MECHANICS LA English DT Article ID SOLID-SURFACES; FLUID INTERFACE; STEADY MOVEMENT; MAXIMUM SPEED; MOTION; DYNAMICS; FLOW; HYDRODYNAMICS; SIMULATIONS; ANGLES AB We examine the spreading of a liquid on a solid surface when the liquid surface has a spread monolayer of insoluble surfactant, and the surfactant transfers through the contact line between the liquid surface and the solid. We show that, as in surfactant-free systems, a singularity appears at the moving contact line. However, unlike surfactant-free systems, the singularity cannot be removed by the same assumptions as long as surfactant transfer takes place. In an attempt to avoid modelling difficulties posed by the question of how the singularity might be removed, we identify parameters which describe the dynamics of the macroscopic spreading process. These parameters, which depend on the details of the fluid motion next to the contact line as in the pure-fluid case, also depend on the state of the spread surfactant in the macroscopic region, in sharp contrast to the pure-fluid case where actions at the macroscopic scale did not affect material spreading parameters. A model of the viscous-controlled region near the contact line which accounts for surfactant transfer shows that, at steady state, some ranges of dynamic contact angles and of capillary number are forbidden. For a given surfactant-liquid pair, these disallowed ranges depend upon the actual contact angle and on the transfer flux of surfactant. We also examine a possible inner model which accounts for the transfer via surface diffusivity and regularizes the stress via a slip model. We show that the asymptotic behaviour of this model at distances from the contact line large compared to the inner length scale matches to the viscous-controlled region. An example of how the information propagates is given. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. RP Rame, E (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, 21000 Brookpk Rd,MS 110-3, Cleveland, OH 44135 USA. NR 44 TC 13 Z9 13 U1 0 U2 4 PU CAMBRIDGE UNIV PRESS PI PORT CHESTER PA 110 MIDLAND AVE, PORT CHESTER, NY 10573-9863 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD AUG 10 PY 2001 VL 440 BP 205 EP 234 PG 30 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 463VR UT WOS:000170498400007 ER PT J AU Kriss, GA Shull, JM Oegerle, W Zheng, W Davidsen, AF Songaila, A Tumlinson, J Cowie, LL Deharveng, JM Friedman, SD Giroux, ML Green, RF Hutchings, JB Jenkins, EB Kruk, JW Moos, HW Morton, DC Sembach, KR Tripp, TM AF Kriss, GA Shull, JM Oegerle, W Zheng, W Davidsen, AF Songaila, A Tumlinson, J Cowie, LL Deharveng, JM Friedman, SD Giroux, ML Green, RF Hutchings, JB Jenkins, EB Kruk, JW Moos, HW Morton, DC Sembach, KR Tripp, TM TI Resolving the structure of ionized helium in the intergalactic medium with the Far Ultraviolet Spectroscopic Explorer SO SCIENCE LA English DT Article ID COLD DARK-MATTER; LY-ALPHA FOREST; ABSORPTION; CLOUDS; MODEL; EVOLUTION; SPECTRUM; HYDROGEN; OPACITY; QUASARS AB The neutral hydrogen (H I) and ionized helium (He II) absorption in the spectra of quasars are unique probes of structure in the early universe. We present Far-Ultraviolet Spectroscopic Explorer observations of the line of sight to the quasar HE2347-4342 in the 1000 to 1187 angstrom band at a resolving power of 15,000. We resolve the He II Lyman alpha (Ly alpha) absorption as a discrete forest of absorption lines in the redshift range 2.3 to 2.7. About 50 percent of these features have H I counterparts with column densities N-HI > 10(12.3) per square centimeter that account for most of the observed opacity in He II Ly alpha. The He if to H I column density ratio ranges from 1 to >1000, with an average of similar to 80. Ratios of <100 are consistent with photoionization of the absorbing gas by a hard ionizing spectrum resulting from the integrated light of quasars, but ratios of >100 in many locations indicate additional contributions from starburst galaxies or heavily filtered quasar radiation. The presence of He II Ly alpha absorbers with no H I counterparts indicates that structure is present even in low-density regions, consistent with theoretical predictions of structure formation through gravitational instability. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Ctr Astrophys Sci, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Colorado, Dept Astrophys & Planetary Sci, JILA, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Astron Spatiale Lab, F-13376 Marseille 12, France. Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V8X 4M6, Canada. RP Kriss, GA (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012; Kruk, Jeffrey/G-4047-2012; Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 34 TC 106 Z9 106 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD AUG 10 PY 2001 VL 293 IS 5532 BP 1112 EP 1116 DI 10.1126/science.1062693 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 462RB UT WOS:000170432600052 PM 11498584 ER PT J AU Chang, J Han, J Yang, L Jaffe, RL Yoon, DY AF Chang, J Han, J Yang, L Jaffe, RL Yoon, DY TI Structure and properties of polymethylene melt surfaces from molecular dynamics simulations SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID LIQUID-VAPOR INTERFACE; LENNARD-JONES FLUID; TEST PARTICLE METHOD; ATOMISTIC SIMULATION; TENSION; EQUILIBRIUM; FILMS; THERMODYNAMICS; TEMPERATURE; DEPENDENCE AB Thermodynamic, structural, and dynamic properties of polymethylene melt surfaces are studied by molecular dynamics simulations using both an explicit atom and a united atom model. N-tridecane (C13H28) melt films with a thickness of about 30 Angstrom are studied by NVT-MD simulation method at the temperatures from 300 K to 450 K. We obtain stable surface properties such as surface tension, density profile, order parameter, and diffusivity upon performing the simulation on these films for 1 or 2 ns. When compared with experiment, simulations give a reasonable agreement for the surface tension with error of ca. 20%. It is observed that the density of chain-end group (methyl) is enhanced near the free surface, while it is depleted in the region below the surface. The interfacial thickness of the density transition region defined as liquid density divided by maximum density gradient is estimated to be about 5 Angstrom at room temperature. In this interfacial region, a slight preference for chain segments to orient along the direction parallel to the surface is observed with practically no difference in the chain conformation from the bulk value. The molecular diffusivity along the film surface is enhanced by a factor of ca. 3 compared with the diffusivity along the surface normal in the interfacial region. Both the explicit atom and the united atom model show almost the same thermodynamic and structural properties near the surface. (C) 2001 American Institute of Physics. C1 Seoul Natl Univ, Sch Chem, Seoul 151742, South Korea. ELORET Corp, Sunnyvale, CA 94086 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Yoon, DY (reprint author), Seoul Natl Univ, Sch Chem, Seoul 151742, South Korea. NR 41 TC 38 Z9 38 U1 0 U2 2 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 AUG 8 PY 2001 VL 115 IS 6 BP 2831 EP 2840 DI 10.1063/1.1379536 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 458BA UT WOS:000170172300051 ER PT J AU Boer, EA Brongersma, ML Atwater, HA Flagan, RC Bell, LD AF Boer, EA Brongersma, ML Atwater, HA Flagan, RC Bell, LD TI Localized charge injection in SiO2 films containing silicon nanocrystals SO APPLIED PHYSICS LETTERS LA English DT Article ID SCANNING FORCE MICROSCOPY; CONTACT ELECTRIFICATION; STORAGE; MEMORY; RESOLUTION AB An atomic-force microscope (AFM) is used to locally inject, detect, and quantify the amount and location of charge in SiO2 films containing Si nanocrystals (size similar to2-6 nm). By comparison with control samples, charge trapping is shown to be due to nanocrystals and not ion-implantation-induced defects in samples containing ion-beam-synthesized Si nanocrystals. Using an electrostatic model and AFM images of charge we have estimated the amount of charge injected in a typical experiment to be a few hundred electrons and the discharge rate to be similar to 35 +/- 15 e/min. (C) 2001 American Institute of Physics. C1 CALTECH, Thomas J Watson Lab Appl Phys, Pasadena, CA 91125 USA. CALTECH, Dept Chem Engn, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP CALTECH, Thomas J Watson Lab Appl Phys, Pasadena, CA 91125 USA. EM Elizabeth.Boer@alcatel.fr RI Brongersma, Mark/R-6099-2016 NR 16 TC 55 Z9 55 U1 2 U2 11 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0003-6951 EI 1077-3118 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD AUG 6 PY 2001 VL 79 IS 6 BP 791 EP 793 DI 10.1063/1.1383574 PG 3 WC Physics, Applied SC Physics GA 458YM UT WOS:000170223100030 ER PT J AU Andriotis, AN Menon, M Srivastava, D Chernozatonskii, L AF Andriotis, AN Menon, M Srivastava, D Chernozatonskii, L TI Rectification properties of carbon nanotube "Y-junctions" SO PHYSICAL REVIEW LETTERS LA English DT Article ID MOLECULAR-DYNAMICS; DEVICES; TRANSPORT AB Quantum conductivity of single-wall carbon nanotube Y-junctions is calculated. The current versus voltage characteristics of these junctions show asymmetry and rectification, in agreement with recent experimental results. Furthermore, rectification is found to be independent of the angle between the branches of these junctions, indicating this to be an intrinsic property of symmetric Y-junctions. The implications for the Y-junction to function as a nanoscale molecular electronic switch are investigated. C1 Fdn Res & Technol Hellas, Inst Elect Struct & Laser, Iraklion 71110, Crete, Greece. Univ Kentucky, Dept Phys & Astron, Lexington, KY 40506 USA. Univ Kentucky, Ctr Computat Sci, Lexington, KY 40506 USA. NASA, Ames Res Ctr, CSC, Moffett Field, CA 94035 USA. Russian Acad Sci, Inst Biochem Phys, Moscow 117977, Russia. RP Andriotis, AN (reprint author), Fdn Res & Technol Hellas, Inst Elect Struct & Laser, POB 1527, Iraklion 71110, Crete, Greece. EM andriot@iesl.forth.gr; super250@pop.uky.edu; deepak@nas.nasa.gov; cherno@sky.chph.ras.ru RI Andriotis, Antonios/A-2848-2014 NR 23 TC 112 Z9 113 U1 2 U2 16 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 6 PY 2001 VL 87 IS 6 AR 066802 DI 10.1103/PhysRevLett.87.066802 PG 4 WC Physics, Multidisciplinary SC Physics GA 460LZ UT WOS:000170310200026 ER PT J AU von Klitzing, W Long, R Ilchenko, VS Hare, J Lefevre-Seguin, V AF von Klitzing, W Long, R Ilchenko, VS Hare, J Lefevre-Seguin, V TI Tunable whispering gallery modes for spectroscopy and CQED experiments SO NEW JOURNAL OF PHYSICS LA English DT Article ID FUSED-SILICA MICROSPHERES; SPONTANEOUS EMISSION; OPTICAL CAVITY; SINGLE PHOTONS; ATOM; MICROCAVITY; LASER; RESONANCES; RESONATOR; THRESHOLD AB We have tuned the whispering gallery modes of a fused silica microresonator over nearly 1 nm at 800 nm, i.e. over half of a free spectral range or the equivalent of 10(6) linewidths of the resonator. This has been achieved by a new method based on the stretching of a two-stem microsphere. The devices described below will permit new cavity-QED experiments with this ultra high finesse optical resonator when it is desirable to optimize its coupling to emitters with given transition frequencies. The tuning capability demonstrated is compatible with both UHV and low temperature operation, which should be useful for future experiments with laser cooled atoms or single quantum dots. A general overview of the current state of the art in microspheres is given as well as a more general introduction. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Ecole Normale Super, Dept Phys, Lab Kastler Brossel, F-75231 Paris 05, France. RP von Klitzing, W (reprint author), FOM, Inst Atom & Mol Phys, Quantum Gases Grp, Kruislaan 407, NL-1098 SJ Amsterdam, Netherlands. EM W.v.Klitzing@amolf.nl; Valerie.Lefevre@lkb.ens.fr RI Long, Romain/C-3095-2013; von Klitzing, Wolf /K-7482-2012 OI von Klitzing, Wolf /0000-0001-6172-8407 NR 28 TC 44 Z9 44 U1 0 U2 13 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 1367-2630 J9 NEW J PHYS JI New J. Phys. PD AUG 3 PY 2001 VL 3 BP 141 EP 1414 AR 14 PG 14 WC Physics, Multidisciplinary SC Physics GA 459AW UT WOS:000170228500001 ER PT J AU Catling, DC Zahnle, KJ McKay, CP AF Catling, DC Zahnle, KJ McKay, CP TI Biogenic methane, hydrogen escape, and the irreversible oxidation of early Earth SO SCIENCE LA English DT Article ID ATMOSPHERIC OXYGEN; CONTINENTAL-CRUST; REDOX STATES; EVOLUTION; DOLOMITE; MANTLE; PHOTOSYNTHESIS; GREENHOUSE; AUSTRALIA; PALEOSOLS AB The low O-2 content of the Archean atmosphere implies that methane should have been present at levels similar to 10(2) to 10(3) parts per million volume (ppmv) (compared with 1.7 ppmv today) given a plausible biogenic source. CH4 is favored as the greenhouse gas that countered the lower luminosity of the early Sun. But abundant CH4 implies that hydrogen escapes to space (up arrow space) orders of magnitude faster than today. Such reductant loss oxidizes the Earth. Photosynthesis splits water into O-2 and H, and methanogenesis transfers the H into CH4. Hydrogen escape after CH4 photolysis, therefore, causes a net gain of oxygen [CO2 + 2H(2)O CH4 --> 2O(2) --> CO2 + O-2 + 4H(up arrow space)]. Expected irreversible oxidation (similar to 10(12) to 10(13) moles oxygen per year) may help explain how Earth's surface environment became irreversibly oxidized. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. SETI Inst, Mountain View, CA 94043 USA. RP NASA, Ames Res Ctr, Div Space Sci, Mail Stop 245-3, Moffett Field, CA 94035 USA. EM catling@humbabe.arc.nasa.gov RI Catling, David/D-2082-2009; OI Catling, David/0000-0001-5646-120X NR 46 TC 199 Z9 214 U1 4 U2 69 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 EI 1095-9203 J9 SCIENCE JI Science PD AUG 3 PY 2001 VL 293 IS 5531 BP 839 EP 843 DI 10.1126/science.1061976 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 459FU UT WOS:000170241000038 PM 11486082 ER PT J AU Banger, KK Cowen, J Harris, J McClarnon, R Riga, A Duraj, S Hepp, AF AF Banger, KK Cowen, J Harris, J McClarnon, R Riga, A Duraj, S Hepp, AF TI Facile modulation and preparation of single source precursors for low-temperature deposition of ternary chalcopyrite materials. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Ohio Aerospace Inst, Cleveland, OH 44142 USA. Cleveland State Univ, Dept Chem, Cleveland, OH 44115 USA. NASA, Glenn Res Ctr, Photovolta & Space Environm Effects Branch, Cleveland, OH 44125 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 PY 2001 VL 222 MA 367-INOR BP U601 EP U601 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 467ET UT WOS:000170690003094 ER PT J AU Chang, J Han, J Jaffe, RL Yang, L Yoon, DY AF Chang, J Han, J Jaffe, RL Yang, L Yoon, DY TI Structural, thermodynamic, and dynamic properties of surfaces and thin films of polymer melts from atomistic molecular dynamics simulations. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Seoul Natl Univ, Sch Chem, Seoul 151742, South Korea. NASA, Ames Res Ctr, Computat Chem Branch, Moffett Field, CA 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 PY 2001 VL 222 MA 289-PMSE BP U384 EP U385 PN 2 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA 467EU UT WOS:000170690102160 ER PT J AU Chang, J Jaffe, RL Yang, L Yoon, DY AF Chang, J Jaffe, RL Yang, L Yoon, DY TI Structure and properties of perfluoroalkane melts from molecular dynamics simulations. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Seoul Natl Univ, Sch Chem, Seoul 151742, South Korea. NASA, Ames Res Ctr, Comp Chem Branch, Moffett Field, CA USA. ELORET Corp, Sunnyvale, CA 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 PY 2001 VL 222 MA 143-PMSE BP U362 EP U362 PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 467EU UT WOS:000170690102014 ER PT J AU Cowen, J Raffaelled, R Hehemann, D Duraj, S Hepp, AF AF Cowen, J Raffaelled, R Hehemann, D Duraj, S Hepp, AF TI Increasing efficient production of thin-film solar cells with cis as an absorber layer by electrodeposition. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Cleveland State Univ, Dept Chem, Cleveland, OH 44115 USA. Rochester Inst Technol, Dept Phys, Rochester, NY USA. NASA Glenn Res Ctr, Photovoltaics & Space Environm Effects Branch, Cleveland, OH 44135 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 PY 2001 VL 222 MA 359-INOR BP U600 EP U600 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 467ET UT WOS:000170690003086 ER PT J AU Harris, JD Raffaelle, RP Hepp, AF Scheiman, DA Cowen, JE AF Harris, JD Raffaelle, RP Hepp, AF Scheiman, DA Cowen, JE TI Thin-film microelectronic solar power systems. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Cleveland State Univ, Dept Chem, NASA Glenn Res Ctr, Cleveland, OH 44135 USA. Rochester Inst Technol, Dept Phys, Rochester, NY USA. NASA, Glenn Res Ctr, Photovoltaics & Space Environm Branch, Cleveland, OH 44135 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 PY 2001 VL 222 MA 361-INOR BP U600 EP U601 PN 1 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA 467ET UT WOS:000170690003088 ER PT J AU Kojiro, DR Sheverev, VA Khromov, NA AF Kojiro, DR Sheverev, VA Khromov, NA TI Chemical detection and identification techniques for Exobiology Flight Experiments. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG PY 2001 VL 222 MA 29-ANYL BP U83 EP U83 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 467ET UT WOS:000170690000331 ER PT J AU Kulis, MJ Perry, DS Miller, FJ AF Kulis, MJ Perry, DS Miller, FJ TI Diode laser diagnostic for use in microgravity. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Univ Akron, Dept Chem, Akron, OH 44325 USA. NASA, Glenn Res Ctr, NCMR, Cleveland, OH 44135 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 PY 2001 VL 222 MA 49-ANYL BP U86 EP U86 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 467ET UT WOS:000170690000351 ER PT J AU Raffaelle, R Maranchi, J Kumta, P Scheiman, D Khan, M Hepp, A AF Raffaelle, R Maranchi, J Kumta, P Scheiman, D Khan, M Hepp, A TI Integrated microelectronic lithium ion polymer batteries for space power. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Rochester Inst Technol, Dept Phys, Rochester, NY 14623 USA. Carnegie Mellon Univ, Pittsburgh, PA 15213 USA. Ohio Aerosp Inst, Photovoltaic & Space Environm Effects Branch, Brookpark, OH USA. NASA, Glenn Res Ctr, Photovoltaic & Space Environ Effects Branch, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG PY 2001 VL 222 MA 360-INOR BP U600 EP U600 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 467ET UT WOS:000170690003087 ER PT J AU Vander Wal, RL Hall, L Berger, G AF Vander Wal, RL Hall, L Berger, G TI Flame synthesis of single- and multi-walled carbon nanotubes. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 Natl Ctr Micrograv Res, NCMR, NASA Glenn, Cleveland, OH 44135 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG PY 2001 VL 222 MA 93-FUEL BP U473 EP U473 PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA 467ET UT WOS:000170690002424 ER PT J AU Aljuri, AN Bursac, N Marini, R Cohen, RJ AF Aljuri, AN Bursac, N Marini, R Cohen, RJ TI System identification of dynamic closed-loop control of total peripheral resistance by arterial and cardiopulmonary baroreceptors SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 13th IAA Humans in Space Symposium CY MAY 21-25, 2000 CL SANTORINI, GREECE SP Greek Aerosp Med Assoc AB Prolonged exposure to microgravity it? space flight missions (days) impairs the mechanisms responsible for defense of arterial blood pressure (ABP) and cardiac output (CO) against orthostatic stress in the post flight period. The mechanisms responsible for the observed orthostatic intolerance are not yet completely understood. Additionally, effective counter measures to attenuate this pathophysiological response are not available. The aim of this study was to investigate the ability of our proposed system identification method to predict closed-loop dynamic changes in TPR induced by changes in mean arterial pressure (MAP) and right atrial pressure (RAP). For this purpose we designed and employed a novel experimental animal model for the examination of arterial and cardiopulmonary baroreceptors in the dynamic closed-loop control of total peripheral resistance (TPR), and applied system identification to the analysis of beat-to-beat fluctuations in the measured signals. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Harvard Mit Div Hlth Sci & Technol, NASA, Ctr Quantitat Cardiovas Physiol, Cambridge, MA 02142 USA. RP Aljuri, AN (reprint author), Harvard Mit Div Hlth Sci & Technol, NASA, Ctr Quantitat Cardiovas Physiol, Cambridge, MA 02142 USA. NR 6 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 AUG-NOV PY 2001 VL 49 IS 3-10 BP 167 EP 170 PG 4 WC Engineering, Aerospace SC Engineering GA 468HK UT WOS:000170751900009 PM 11669106 ER PT J AU Wilson, JW Shinn, JL Tripathi, RK Singleterry, RC Clowdsley, MS Thibeault, SA Cheatwood, FM Schimmerling, W Cucinotta, FA Badhwar, GD Noor, AK Kim, MY Badavi, FF Heinbockel, JH Miller, J Zeitlin, C Heilbronn, L AF Wilson, JW Shinn, JL Tripathi, RK Singleterry, RC Clowdsley, MS Thibeault, SA Cheatwood, FM Schimmerling, W Cucinotta, FA Badhwar, GD Noor, AK Kim, MY Badavi, FF Heinbockel, JH Miller, J Zeitlin, C Heilbronn, L TI Issues in deep space radiation protection SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 13th IAA Humans in Space Symposium CY MAY 21-25, 2000 CL SANTORINI, GREECE SP Greek Aerosp Med Assoc ID RELATIVE BIOLOGICAL EFFECTIVENESS; GALACTIC COSMIC-RAY; CROSS-SECTIONS; FRAGMENTATION MODEL; DOSE-EQUIVALENT; TRANSPORT; SHUTTLE; IONS AB The exposures in deep space are largely from the Galactic Cosmic Rays (GCR) for which there is as yet little biological experience. Mounting evidence indicates that conventional linear energy transfer (LET) defined protection quantities (quality factors) may not be appropriate for GCR ions. The available biological data indicates that aluminum alloy structures may generate inherently unhealthy internal spacecraft environments in the thickness range for space applications. Methods for optimization of spacecraft shielding and the associated role of materials selection are discussed. One material which may prove to be an improtant radiation protection material is hydrogenated carbon nanofibers. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Wilson, JW (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 38 TC 45 Z9 47 U1 0 U2 6 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 AUG-NOV PY 2001 VL 49 IS 3-10 BP 289 EP 312 DI 10.1016/S0094-5765(01)00107-2 PG 24 WC Engineering, Aerospace SC Engineering GA 468HK UT WOS:000170751900021 PM 11669118 ER PT J AU Denkins, P Badhwar, G Obot, V Wilson, B Jejelewo, O AF Denkins, P Badhwar, G Obot, V Wilson, B Jejelewo, O TI Radiation transport modeling and assessment to better predict radiation exposure, dose, and toxicological effects to human organs on long duration space flights SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 13th IAA Humans in Space Symposium CY MAY 21-25, 2000 CL SANTORINI, GREECE SP Greek Aerosp Med Assoc AB NASA is very interested in improving its ability to monitor and forecast the radiation levels that pose a health risk to space-walking astronauts as they construct the International Space Station and astronauts that will participate in long-term and deep-space missions. Human exploratory missions to the moon and Mars within the next quarter century, will expose crews to transient radiation from solar particle events which include high-energy galactic cosmic rays and high-energy protons. Because the radiation levels in space are high and solar activity is presently unpredictable, adequate shielding is needed to minimize the deleterious health effects of exposure to radiation. Today, numerous models have been developed and used to predict radiation exposure. Such a model is the Space Environment Information Systems (SPENVIS) modeling program, developed by the Belgian Institute for Space Aeronautics. SPENVIS, which has been assessed to be an excellent tool in characterizing the radiation environment for microelectronics and investigating orbital debris, is being evaluated for its usefulness with determining the dose and dose-equivalent for human exposure. Thus far, the calculations for dose-depth relations under varying shielding conditions have been in agreement with calculations done using HZETRN and PDOSE, which are well-known and widely used models for characterizing the environments for human exploratory missions. There is disagreement when assessing the impact of secondary radiation particles since SPENVIS does a crude estimation of the secondary radiation particles when calculating LET versus Flux. SPENVIS was used to model dose-depth relations for the blood-forming organs. Radiation sickness and cancer are life-threatening consequences resulting from radiation exposure. In space, exposure to radiation generally includes all of the critical organs. Biological and toxicological impacts have been included for discussion along with alternative risk mitigation methods - shielding arid anti-carcinogens. Published by Elsevier Science Ltd. C1 Lyndon B Johnson Space Ctr, Syst Engn & Technol Assessment, Houston, TX 77058 USA. RP Denkins, P (reprint author), Lyndon B Johnson Space Ctr, Syst Engn & Technol Assessment, Houston, TX 77058 USA. NR 10 TC 8 Z9 10 U1 2 U2 3 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 AUG-NOV PY 2001 VL 49 IS 3-10 BP 313 EP 319 DI 10.1016/S0094-5765(01)00108-4 PG 7 WC Engineering, Aerospace SC Engineering GA 468HK UT WOS:000170751900022 PM 11669119 ER PT J AU Doerr, DF AF Doerr, DF TI Development of an advanced rocket propellant Handler's suit SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 13th IAA Humans in Space Symposium CY MAY 21-25, 2000 CL SANTORINI, GREECE SP Greek Aerosp Med Assoc AB Most launch vehicles and satellites in the US inventory rely upon the use of hypergolic rocket propollants, many of which are toxic to humans. These fuels and oxidizers, such as hydrazine and nitrogen tetroxide have threshold limit values as low as 0.01 PPM. It is essential to provide space workers handling these agents whole body protection as they are universally hazardous not only to the respiratory system, but the skin as well. This paper describes a new method for powering a whole body protective garment to assure the safety of ground servicing crews. A new technology has been developed through the small business innovative research program at the Kennedy Space Center. Currently, liquid air is used in the environmental control unit (ECU) that powers the propellant handlers suit (PHE). However, liquid air exhibits problems with attitude dependence, oxygen enrichment, and difficulty with reliable quantity measurement. The new technology employs the storage of the supply air as a supercritical gas. This method of air storage overcomes ail of three problems above while maintaining high density storage at relatively low vessel pressures (< 7000 kPa or similar to 1000 psi). A one hour prototype ECU was developed and tested to prove the feasibility of this concept. This was upgraded by the design of a larger supercritical dewar capable of holding 7 Kg of air, a supply which provides a 2 hour duration to the PHE. A third version is being developed to test the feasibility of replacing existing air cooling methodology with a liquid cooled garment for relief of heat stress in this warm Florida environment. Testing of the first one hour prototype yielded data comprobable to the liquid air powered predecessor, but enjoyed advantages of attitude independence and oxygen level stability. Thermal data revealed heat stress relief at least as good as liquid air supplied units. The application of supercritical air technology to this whole body protective ensemble marked an advancement in the state-of-the-art in personal protective equipment. Not only was long duration environmental control provided, but it was done without a high pressure vessel. The unit met human performance needs for attitude independence, oxygen stability, and relief of heat stress. This supercritical air (and oxygen) technology is suggested for microgravity applications in life support such as the Extravehicular Mobility Unit. (C) 2001 Published by Elsevier Science Ltd. C1 NASA, Kennedy Space Ctr, FL 32899 USA. RP Doerr, DF (reprint author), NASA, Kennedy Space Ctr, FL 32899 USA. NR 0 TC 3 Z9 3 U1 2 U2 6 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 AUG-NOV PY 2001 VL 49 IS 3-10 BP 463 EP 468 DI 10.1016/S0094-5765(01)00122-9 PG 6 WC Engineering, Aerospace SC Engineering GA 468HK UT WOS:000170751900035 PM 11669132 ER PT J AU Miller, LJ Haven, CP McCollum, SG Lee, AM Kamman, MR Baumann, DK Anderson, ME Buderer, MC AF Miller, LJ Haven, CP McCollum, SG Lee, AM Kamman, MR Baumann, DK Anderson, ME Buderer, MC TI The International Space Station Human Life Sciences experiment implementation process SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 13th IAA Humans in Space Symposium CY MAY 21-25, 2000 CL SANTORINI, GREECE SP Greek Aerosp Med Assoc AB The selection, definition, and development phases of a Life Sciences flight research experiment has been consistent throughout the past decade. The implementation process, however, has changed significantly within the past two years. This change is driven primarily by the shift from highly integrated, dedicated research missions on platforms with well defined processes to self contained experiments with stand alone operations on platforms which are being concurrently designed. For experiments manifested on the International Space Station (ISS) and I or on short duration missions, the more modular, streamlined, and independent the individual experiment is, the more likely it is to be successfully implemented before the ISS assembly is completed. During the assembly phase of the ISS, science operations are lower in priority than the construction of the station. After the station has been completed, it is expected that more resources will be available to perform research. The complexity of implementing investigations increases with the logistics needed to perform the experiment. Examples of logistics issues include: hardware unique to the experiment; large up and down mass and volume needs; access to crew and hardware during the ascent or descent phases; maintenance of hardware and supplies with a limited shelf life; baseline data collection schedules with lengthy sessions or sessions close to the launch or landing; onboard stowage availability, particularly cold stowage; and extensive training where highly proficient skills must be maintained. As the ISS processes become better defined, experiment implementation will meet new challenges due to distributed management, on-orbit resource sharing and adjustments to crew availability pre- and postincrement. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Miller, LJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 1 Z9 2 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD AUG-NOV PY 2001 VL 49 IS 3-10 BP 477 EP 482 DI 10.1016/S0094-5765(01)00130-8 PG 6 WC Engineering, Aerospace SC Engineering GA 468HK UT WOS:000170751900037 PM 11669134 ER PT J AU Borgstahl, GEO Vahedi-Faridi, A Lovelace, J Bellamy, HD Snell, EH AF Borgstahl, GEO Vahedi-Faridi, A Lovelace, J Bellamy, HD Snell, EH TI A test of macromolecular crystallization in microgravity: large well ordered insulin crystals SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article ID X-RAY-DIFFRACTION; GROWTH; RESOLUTION AB Crystals of insulin grown in microgravity on Space Shuttle Mission STS-95 were extremely well ordered and unusually large (many >2 mm). The physical characteristics of six microgravity and six earth-grown crystals were examined by X-ray analysis employing superfine phi slicing and unfocused synchrotron radiation. This experimental setup allowed hundreds of reflections to be precisely examined from each crystal in a short period of time. The microgravity crystals were on average 34 times larger, had sevenfold lower mosaicity, had 54-fold higher reflection peak heights and diffracted to significantly higher resolution than their earth-grown counterparts. A single mosaic domain model could account for the observed reflection profiles in microgravity crystals, whereas data from earth crystals required a model with multiple mosaic domains. This statistically significant and unbiased characterization indicates that the microgravity environment was useful for the improvement of crystal growth and the resultant diffraction quality in insulin crystals and may be similarly useful for macromolecular crystals in general. C1 Univ Toledo, Dept Chem, Toledo, OH 43606 USA. Stanford Synchrotron Radiat Lab, Menlo Park, CA 94025 USA. NASA, George C Marshall Space Flight Ctr, Struct Biol Lab, Huntsville, AL 35812 USA. RP Borgstahl, GEO (reprint author), Univ Toledo, Dept Chem, 2801 W Bancroft St, Toledo, OH 43606 USA. NR 14 TC 46 Z9 46 U1 0 U2 2 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 2001 VL 57 BP 1204 EP 1207 DI 10.1107/S0907444901007892 PN 8 PG 4 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA 455RV UT WOS:000170041200032 PM 11468418 ER PT J AU Frendi, A Nesman, TE Wang, TS AF Frendi, A Nesman, TE Wang, TS TI Computational and experimental study of linear aerospike engine noise SO AIAA JOURNAL LA English DT Article ID SUPERSONIC JET NOISE; TURBULENCE AB Experimental and computational results of X-33 linear aerospike engine noise tests are presented. Only noise sources external to the nozzle are considered Ino combustion noise). The experimental setup is such that the engine, located 18.3 m above the ground, has its exhaust plume diverted from a vertical position to a nearly horizontal position located 3 m above the ground using a J deflector. Experimental measurements are made at several locations in the midfield. A semi-empirical model is derived that accounts for the nonaxisymmetry of the engine exit plane. The model uses mean flow quantities obtained from a computational fluid dynamics computation using a k-epsilon turbulence model. Midfield results obtained using the semi-empirical model are in reasonable agreement with the experimental measurements. The semi-empirical model was able to explain the source of a low-frequency peak observed in the spectra (near 10 Hz). In addition, the midfield directivity pattern and overall sound pressure levels given by the semi-empirical model are in good agreement with the measurements. C1 Univ Alabama, Dept Mech & Aerosp Engn, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Space Transportat Directorate, Appl Fluid Dynam Anal Grp, Huntsville, AL 35812 USA. RP Frendi, A (reprint author), Univ Alabama, Dept Mech & Aerosp Engn, TH N264, Huntsville, AL 35899 USA. NR 24 TC 6 Z9 6 U1 2 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 2001 VL 39 IS 8 BP 1485 EP 1492 DI 10.2514/2.1499 PG 8 WC Engineering, Aerospace SC Engineering GA 458XW UT WOS:000170221600008 ER PT J AU Tang, DM Kholodar, D Juang, JN Dowell, EH AF Tang, DM Kholodar, D Juang, JN Dowell, EH TI System identification and proper orthogonal decomposition method applied to unsteady aerodynamics SO AIAA JOURNAL LA English DT Article AB The representation of unsteady aerodynamic flowfields in terms of global aerodynamic modes has proven to be a useful method for reducing the size of the aerodynamic model over those representations that use local variables at discrete grid points in the How field. Eigenmodes and proper orthogonal decomposition modes have been used for this purpose with good effect. This suggests that system identification models may also be used to represent the aerodynamic flowfield. Implicit in the use of a systems identification technique is the notion that a relative small state-space model can be useful in describing a dynamical system. The proper orthogonal decomposition model is first used to show that indeed a reduced-order model can be obtained from a much larger numerical aerodynamical model (the vortex lattice method is used for illustrative purposes), and the results from the proper orthogonal decomposition model and the system identification methods are then compared. For the example considered the two methods are shown to give comparable results in terms of accuracy and reduced model size. The advantages and limitations of each approach are briefly discussed. Both appear promising and complementary in their characteristics. C1 Duke Univ, Dept Mech Engn & Mat Sci, Durham, NC 27708 USA. NASA, Langley Res Ctr, Dept Mech Engn & Mat Sci, Hampton, VA 23681 USA. Duke Univ, Dept Mech Engn & Mat Sci, Durham, NC 27708 USA. RP Tang, DM (reprint author), Duke Univ, Dept Mech Engn & Mat Sci, Durham, NC 27708 USA. NR 5 TC 33 Z9 33 U1 0 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 2001 VL 39 IS 8 BP 1569 EP 1576 DI 10.2514/2.1482 PG 8 WC Engineering, Aerospace SC Engineering GA 458XW UT WOS:000170221600018 ER PT J AU Elliott, AR Shea, SA Dijk, DJ Wyatt, JK Riel, E Neri, DF Czeisler, CA West, JB Prisk, GK AF Elliott, AR Shea, SA Dijk, DJ Wyatt, JK Riel, E Neri, DF Czeisler, CA West, JB Prisk, GK TI Microgravity reduces sleep-disordered breathing in humans SO AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE LA English DT Article DE obstructive sleep apnea; airway collapse; arousals; gravitational effect ID UPPER AIRWAY DIMENSIONS; SUSTAINED MICROGRAVITY; LUNG-VOLUME; VENTILATORY RESPONSE; GENIOGLOSSUS MUSCLE; REFLEX CONTROL; IN-SPACE; APNEA; BARORECEPTOR; SPACEFLIGHT AB To understand the factors that alter sleep quality in space, we studied the effect of spaceflight on sleep-disordered breathing. We analyzed 77 8-h, full polysomnographic recordings (PSGs) from five healthy subjects before spaceflight, on four occasions per subject during either a 16- or 9-d space shuttle mission and shortly after return to earth. Microgravity was associated with a 55% reduction in the apnea-hypopnea index (AHI), which decreased from a preflight value of 8.3 +/- 1.6 to 3.4 +/- 0.8 events/h inflight. This reduction in AHI was accompanied by a virtual elimination of snoring, which fell from 16.5 +/- 3.0% of total sleep time preflight to 0.7 +/- 0.5% inflight. Electroencephalogram (EEG) arousals also decreased in microgravity (by 19%), and this decrease was almost entirely a consequence of the reduction in respiratory-related arousals, which fell from 5.5 +/- 1.2 arousals/h preflight to 1.8 +/- 0.6 inflight. Postflight there was a return to near or slightly above preflight levels in these variables. We conclude that sleep quality during spaceflight is not degraded by sleep-disordered breathing. This is the first direct demonstration that gravity plays a dominant role in the generation of apneas, hypopneas, and snoring in healthy subjects. C1 Univ Calif San Diego, Dept Med 0931, La Jolla, CA 92093 USA. Brigham & Womens Hosp, Dept Med, Div Endocrinol, Neuroendocrine & Sleep Disorders Sect, Boston, MA 02115 USA. Harvard Med Sch, Boston, MA USA. NASA, Ames Res Ctr, Mt View, CA USA. RP Prisk, GK (reprint author), Univ Calif San Diego, Dept Med 0931, 9500 Gilman Dr, La Jolla, CA 92093 USA. RI Dijk, Derk-Jan/D-8387-2011; Wyatt, James/F-1785-2011 FU NHLBI NIH HHS [U01-HL53208-01] NR 47 TC 24 Z9 26 U1 0 U2 2 PU AMER THORACIC SOC PI NEW YORK PA 1740 BROADWAY, NEW YORK, NY 10019-4374 USA SN 1073-449X J9 AM J RESP CRIT CARE JI Am. J. Respir. Crit. Care Med. PD AUG 1 PY 2001 VL 164 IS 3 BP 478 EP 485 PG 8 WC Critical Care Medicine; Respiratory System SC General & Internal Medicine; Respiratory System GA 466NG UT WOS:000170651200027 PM 11500354 ER PT J AU Gao, Q Fang, A Pierson, DL Mishra, SK Demain, AL AF Gao, Q Fang, A Pierson, DL Mishra, SK Demain, AL TI Shear stress enhances microcin B17 production in a rotating wall bioreactor, but ethanol stress does not SO APPLIED MICROBIOLOGY AND BIOTECHNOLOGY LA English DT Article ID SIMULATED MICROGRAVITY; HEAT-SHOCK; ESCHERICHIA-COLI; STREPTOMYCES-CLAVULIGERUS; SECONDARY METABOLISM; GROWTH; BIOSYNTHESIS AB Stress, including that caused by ethanol, has been shown to induce or promote secondary metabolism in a number of microbial systems. Rotating-wall bioreactors provide a low stress and simulated microgravity environment which, however, supports only poor production of microcin B17 by Escherichia coli ZK650, as compared to production in agitated flasks. We wondered whether the poor production is due to the low level of stress and whether increasing stress in the bioreactors would raise the amount of microcin B17 formed. We found that applying shear stress by addition of a single Teflon bead to a rotating wall bioreactor improved microcin B17 production. By contrast, addition of various concentrations of ethanol to such bioreactors (or to shaken flasks) failed to increase microcin B17 production. Ethanol stress merely decreased production and, at higher concentrations, inhibited growth. Interestingly, cells growing in the bioreactor were much more resistant to the growth-inhibitory and production-inhibitory effects of ethanol than cells growing in shaken flasks. 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, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Demain, AL (reprint author), MIT, Dept Biol, Fermentat Microbiol Lab, Cambridge, MA 02139 USA. NR 22 TC 26 Z9 28 U1 0 U2 3 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 AUG PY 2001 VL 56 IS 3-4 BP 384 EP 387 PG 4 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA 465UP UT WOS:000170608600011 PM 11549006 ER PT J AU Vanek, MD Nolt, IG Tappan, ND Ade, PAR Gannaway, FC Hamilton, PA Lee, C Evans, KF Davis, JE Predko, S AF Vanek, MD Nolt, IG Tappan, ND Ade, PAR Gannaway, FC Hamilton, PA Lee, C Evans, KF Davis, JE Predko, S TI Far-infrared sensor for cirrus (FIRSC): an aircraft-based Fourier-transform spectrometer to measure cloud radiance (vol 40, pg 2169, 2001) SO APPLIED OPTICS LA English DT Correction C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Queen Mary Univ London, London E1 4NS, England. Univ Colorado, Boulder, CO 80309 USA. Cochise Instruments, Hereford, AZ 85615 USA. Univ Oregon, Eugene, OR 97403 USA. RP Vanek, MD (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 1 TC 0 Z9 0 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 AUG 1 PY 2001 VL 40 IS 22 BP 3710 EP 3710 DI 10.1364/AO.40.003710 PG 1 WC Optics SC Optics GA 457VL UT WOS:000170157500012 PM 18360403 ER PT J AU Shibata, R Ishida, M Kunieda, H Endo, T Honda, H Misaki, K Ishida, J Imamura, K Hidaka, Y Maeda, M Tawara, Y Ogasaka, Y Furuzawa, A Watanabe, M Terashima, Y Yoshioka, T Okajima, T Yamashita, K Serlemitsos, PJ Soong, Y Chan, KW AF Shibata, R Ishida, M Kunieda, H Endo, T Honda, H Misaki, K Ishida, J Imamura, K Hidaka, Y Maeda, M Tawara, Y Ogasaka, Y Furuzawa, A Watanabe, M Terashima, Y Yoshioka, T Okajima, T Yamashita, K Serlemitsos, PJ Soong, Y Chan, KW TI X-ray telescope onboard Astro-E. II. Ground-based x-ray characterization SO APPLIED OPTICS LA English DT Article ID EFFECTIVE AREA; CALIBRATION; SATELLITE; DETECTOR AB X-ray characterization measurements of the x-ray telescope (XRT) onboard the Astro-E satellite were carried out at the Institute of Space and Astronautical Science (Japan) x-ray beam facility by means of a raster scan with a narrow x-ray pencil beam. The on-axis half-power diameter (HPD) was evaluated to be 1.8 ' -2.2 ', irrespective of the x-ray energy. The on-axis effective areas of the XRTs for x-ray imaging spectrometers (XISs) were approximately 440, 320, 240, and 170 cm(2) at energies of 1.49, 4.51, 8.04, and 9.44 keV, respectively. Those of the x-ray spectrometer (YRS) were larger by 5-10%. The replication method introduced for reflector production significantly improved the imaging capability of the Advanced Satellite for Cosmology and Astrophyics (ASCA) XRT, whose HPD is similar to3.6 '. The increase in the effective area by a factor of 1.5-2.5, depending upon the x-ray energy, compared with that of the ASCA, was brought about by mechanical scale up and longer focal lengths. The off-axis HPDs were almost the same as those obtained on the optical axis. The field of view is defined as the off-axis angle at which the effective area becomes half of the on-axis value. The diameter of the field of view was similar to 19 ' at 1.49 keV, decreasing with increasing x-ray energy, and became similar to 13 ' at 9.44 keV. The intensity of stray light and the distribution of this kind of light on the focal plane were measured at the large off-axis angles 30' and 60 '. In the entire XIS field of view (25.4 mm X 25.4 mm), the intensity of the stray light caused by a pointlike x-ray source became at most 1% of the same pointlike source that was on the optical axis. (C) 2001 Optical Society of America. C1 Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Nagoya Univ, Dept Phys, Fac Sci, Nagoya, Aichi 4648602, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Shibata, R (reprint author), Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2298510, Japan. EM shibata@astro.isas.ae.jp NR 11 TC 25 Z9 25 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 AUG 1 PY 2001 VL 40 IS 22 BP 3762 EP 3783 DI 10.1364/AO.40.003762 PG 22 WC Optics SC Optics GA 457VL UT WOS:000170157500020 PM 18360411 ER PT J AU Cockell, CS Lee, P Schuerger, AC Hidalgo, L Jones, JA Stokes, MD AF Cockell, CS Lee, P Schuerger, AC Hidalgo, L Jones, JA Stokes, MD TI Microbiology and vegetation of micro-oases and polar desert, Haughton impact crater, Devon Island, Nunavut, Canada SO ARCTIC ANTARCTIC AND ALPINE RESEARCH LA English DT Article ID PLANT-COMMUNITIES; ELLESMERE ISLAND; DIET SELECTION; NITROGEN; NWT; SUCCESSION; PHOTOSYNTHESIS; ASSOCIATION; TEMPERATURE; PATTERNS AB The input of nutrients into arctic polar deserts, aided by some physical processes, can result in localized areas of high biological productivity-"micro-oases." We examined the vegetation cover, and microbial and nematode abundance in the polar desert and in 38 micro-oases at the Haughton impact crater, Devon Island, Arctic Canada. Our sites were split between the alluvial terraces along the banks of the Haughton River and the breccia deposits resulting from the asteroid or comet impact 22 Myr ago that flank the alluvial terraces. The alluvial terraces have a vegetation cover that ranges from 2 to 11% depending on substrate and water availability with a species richness of 5 in most locations. The vegetation cover on the breccia is much lower, between 0.02 and 3% depending on water availability. The micro-oases on both substrates support between 2 and 98% cover, but they are smaller and more sparsely distributed than similar features found in the Truelove Lowland, Devon Island, and on Bathurst Island. Microbial and nematode numbers were an order of magnitude greater inside the micro-oases compared to outside. Micro-oases are often dominated by a particular species, resulting in well-defined groups of micro-oases that were separated by TWINSPAN analysis. The micro-oases at Haughton Crater provide insights into the process of colonization of a substrate resulting from an asteroid or comet impact and the unique biological characteristics of such substrates. C1 British Antarctic Survey, Cambridge CB3 0ET, England. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. Dynamac Corp, Kennedy Space Ctr, FL 32899 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. RP Cockell, CS (reprint author), British Antarctic Survey, High Cross,Madingley Rd, Cambridge CB3 0ET, England. NR 59 TC 22 Z9 22 U1 0 U2 7 PU INST ARCTIC ALPINE RES PI BOULDER PA UNIV COLORADO, BOULDER, CO 80309 USA SN 1523-0430 J9 ARCT ANTARCT ALP RES JI Arct. Antarct. Alp. Res. PD AUG PY 2001 VL 33 IS 3 BP 306 EP 318 DI 10.2307/1552238 PG 13 WC Environmental Sciences; Geography, Physical SC Environmental Sciences & Ecology; Physical Geography GA 469VF UT WOS:000170836200008 ER PT J AU Dawson, S Stern, D Bunker, AJ Spinrad, H Dey, A AF Dawson, S Stern, D Bunker, AJ Spinrad, H Dey, A TI Serendipitously detected galaxies in the Hubble Deep Field SO ASTRONOMICAL JOURNAL LA English DT Article DE cosmology : observations; early universe; galaxies : distances and redshifts; galaxies : high-redshift ID LYMAN-BREAK GALAXIES; RESOLUTION IMAGING SPECTROMETER; LY-ALPHA EMISSION; X-RAY SOURCES; HIGH-REDSHIFT; KECK SPECTROSCOPY; ELLIPTIC GALAXIES; PRIMEVAL GALAXIES; DISTANT GALAXIES; RADIO-EMISSION AB We present a catalog of 74 galaxies detected serendipitously during a campaign of spectroscopic observations of the Hubble Deep Field North (HDF) and its environs. Among the identified objects are five candidate Ly alpha emitters at z greater than or similar to 5, a galaxy cluster at z = 0.85, and a Chandra source with a heretofore undetermined redshift of z = 2.011. We report redshifts for 25 galaxies in the central HDF, 13 of which had no prior published spectroscopic redshift. Of the remaining 49 galaxies, 30 are located in the single-orbit HDF flanking fields. We discuss the redshift distribution of the serendipitous sample, which contains galaxies in the range 0.10 < z < 5.77 with a median redshift of z = 0.85, and we present strong evidence for redshift clustering. By comparing our spectroscopic redshifts with optical/IR photometric studies of the HDF, we find that photometric redshifts are in most cases capable of producing reasonable predictions of galaxy redshifts. Finally, we estimate the line-of-sight velocity dispersion and the corresponding mass and expected X-ray luminosity of the galaxy cluster, we present strong arguments for interpreting the Chandra source as an obscured active galactic nucleus, and we discuss in detail the spectrum of one of the candidate z greater than or similar to 5 Ly alpha emitters. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. RP Dawson, S (reprint author), Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA. NR 69 TC 86 Z9 86 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2001 VL 122 IS 2 BP 598 EP 610 DI 10.1086/321160 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462PQ UT WOS:000170429300008 ER PT J AU Holden, BP Stanford, SA Rosati, P Squires, G Tozzi, P Fosbury, RAE Papovich, C Eisenhardt, P Elston, R Spinrad, H AF Holden, BP Stanford, SA Rosati, P Squires, G Tozzi, P Fosbury, RAE Papovich, C Eisenhardt, P Elston, R Spinrad, H TI Rx J0848+4456: Disentangling a moderate redshift cluster SO ASTRONOMICAL JOURNAL LA English DT Article DE catalogs; cosmology : observations; galaxies : clusters : general ID VELOCITIES AB We present a multiwavelength study of RX J0848+4456, a cluster of galaxies discovered through X-ray emission in the ROSAT Deep Cluster Survey. Our observations consist of WFPC2 imaging, optical spectra, and X-ray data collected with the Chandra X-Ray Observatory. We find that RX J0848+4456 consists of an X-ray-emitting cluster of galaxies at a redshift of z = 0.570 and a group at a slightly lower redshift, z = 0.543, with little X-ray emission. This lower redshift system, however, is a gravitational lens, with the lensed galaxy being an unusual AGN or star-forming system at z = 3.356. The cluster has an X-ray temperature of kT = 3.6 +/- 0.4 keV, a bolometric luminosity of 1.0 +/- 0.3 10(44) ergs s(-1) and a velocity dispersion of 670 +/- 50 km s(-1). These values all agree with the low-redshift correlations for clusters of galaxies, implying a relaxed system with the intracluster medium in equilibrium with the dark matter potential. The lower redshift group of galaxies at z = 0.543 has, at most, one-fifth, and more likely 1/10, of the X-ray luminosity of RX J0848+4456. Despite being a gravitational lens, this is a low-mass system, with an X-ray temperature of kT = 2.3(-0.4)(+0.5) keV and a velocity dispersion of only 430 +/- 20 km s(-1). Our observations show the importance of detailed studies of clusters of galaxies when using them as probes of cosmological mass functions. C1 Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. European So Observ, D-85748 Garching, Germany. CALTECH, Pasadena, CA 91125 USA. Osserv Astron Trieste, I-34131 Trieste, Italy. Space Telescope European Coordinating Facil, D-85748 Garching, Germany. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. RP Holden, BP (reprint author), Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. NR 25 TC 29 Z9 29 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2001 VL 122 IS 2 BP 629 EP 636 DI 10.1086/321163 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462PQ UT WOS:000170429300011 ER PT J AU Kuchinski, LE Madore, BF Freedman, WL Trewhella, M AF Kuchinski, LE Madore, BF Freedman, WL Trewhella, M TI Quantitative morphology of galaxies observed in the ultraviolet SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : fundamental parameters; galaxies : individual (M51, M63, NGC 1097, NGC 1313, NGC 1512); galaxies : photometry ID HUBBLE DEEP FIELD; STAR-FORMING GALAXIES; REDSHIFT GALAXIES; PECULIAR GALAXIES; DISTANT GALAXIES; NEARBY GALAXIES; CLASSIFICATION; TELESCOPE; EVOLUTION; CATALOG AB We present a quantitative study of the far-ultraviolet (FUV) and optical morphology in 32 nearby galaxies and estimate the "morphological k-correction" expected if these objects were observed unevolved at high redshift. Using the common indices of central concentration (C) and rotational asymmetry (A) to quantify morphology, we consider independently two phenomena that give rise to this k-correction. Bandshifting, the decrease in the rest-frame wavelength of light observed through optical filters, is explored by measuring these indices in several passbands for each galaxy, and it is found to be the primary driver of changes in C and A. In general, the optical trend found for decreasing C and increasing A when going to shorter wavelengths extends to the FUV. However, the patchy nature of recent star formation in late-type galaxies, which is accentuated in the FUV, results in poor quantitative correspondence between morphologies determined in the optical and FUV. We then artificially redshift our FUV images into the Hubble Deep Field (HDF) filters to simulate various cosmological distance effects, such as surface brightness dimming and loss of spatial resolution. Hubble types of many galaxies in our sample are not readily identifiable at redshifts beyond z similar to 1, and the galaxies themselves are difficult to detect beyond z similar to 3. Because only features of the highest surface brightness remain visible at cosmological distances, the change in C and A between simulated high-z galaxies and their unredshifted counterparts depends on whether their irregular features are primarily bright or faint. Our simulations suggest that k-corrections alone are indeed capable of producing the peculiar morphologies observed at high redshift; for example, several spiral galaxies have C and A indices typical of irregular or peculiar HDF objects viewed at z greater than or equal to 2. We briefly discuss some elements of a scheme to classify rest-frame UV images, mergers, protogalaxies, and other objects for which classical Hubble types do not adequately encompass the existing morphology. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Observ Carnegie Inst Washington, Pasadena, CA 91101 USA. CALTECH, NASA IPAC Extragalact Database, Pasadena, CA 91125 USA. RP Kuchinski, LE (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, MS 100-22,770 S Wilson Ave, Pasadena, CA 91125 USA. NR 60 TC 31 Z9 31 U1 1 U2 2 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 2001 VL 122 IS 2 BP 729 EP 749 DI 10.1086/321181 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462PQ UT WOS:000170429300016 ER PT J AU Dickel, JR Williams, RM Carter, LM Milne, DK Petre, R Amy, SW AF Dickel, JR Williams, RM Carter, LM Milne, DK Petre, R Amy, SW TI Supernova remnants in the southwestern part of the Small Magellanic Cloud SO ASTRONOMICAL JOURNAL LA English DT Article DE Magellanic Clouds; supernova remnants ID SMC AB We have compared radio images from the Australia Telescope Compact Array and X-ray images from ROSAT of an area about 560 pc in diameter around the very extended emission nebula N19 on the southwestern edge of the bright ridge of the Small Magellanic Cloud. These data have allowed us to identify tentatively seven supernova remnants in this region. This number is large enough to suggest that the area has recently undergone some starburst activity. N19 itself appears to contain two overlapping supernova remnants within the extended H II region. C1 Univ Illinois, Dept Astron, Urbana, IL 61801 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Australia Telescope Natl Facil, Epping, NSW 1710, Australia. Univ Sydney, Dept Astrophys, Sydney, NSW 2006, Australia. RP Dickel, JR (reprint author), Univ Illinois, Dept Astron, 1002 W Green St, Urbana, IL 61801 USA. RI Carter, Lynn/D-2937-2012 NR 25 TC 16 Z9 16 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2001 VL 122 IS 2 BP 849 EP 857 DI 10.1086/321150 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462PQ UT WOS:000170429300025 ER PT J AU Hyung, S Aller, LH Feibelman, WA Lee, WB AF Hyung, S Aller, LH Feibelman, WA Lee, WB TI Abundances in the planetary nebula IC 5217 SO ASTRONOMICAL JOURNAL LA English DT Article DE planetary nebulae : general; planetary nebulae : individual (IC 5217) ID EMISSION-LINES; OPTICAL-SPECTRUM; EVOLUTION; DISTANCE; CARBON; STARS AB High-resolution optical wavelength spectroscopic data were secured in the optical wavelengths, 3700-10050 Angstrom, for the planetary nebula IC 5217 with the Hamilton Echelle Spectrograph at Lick Observatory. These optical spectra have been analyzed along with the near-UV and UV archive data. Diagnostic analyses indicate a nebular physical condition with electron temperature of about 10,700 K (from the [O III] lines) and the density of N-epsilon = 5000 cm(-1). Ionic concentrations have been derived with the representative diagnostics, and with the aid of a photoionization model construction, we derived the elemental abundances. Contrary to the previous studies found in the literature, He and C appear to be depleted compared to the average planetary nebula and to the Sun (and S marginally so), while the remaining elements appear to be close to the average value. IC 5217 may have evolved from an O-rich progenitor, and the central star temperature of IC 5217 is likely to be 92,000 K. C1 Korea Astron Observ, Taejon 305348, South Korea. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Hyung, S (reprint author), Korea Astron Observ, 61-1 Whaam Dong, Taejon 305348, South Korea. NR 35 TC 11 Z9 11 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2001 VL 122 IS 2 BP 954 EP 965 DI 10.1086/321171 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462PQ UT WOS:000170429300034 ER PT J AU Ray, A Petre, R Schlegel, EM AF Ray, A Petre, R Schlegel, EM TI Chandra and ASCA X-ray observations of the type II-L supernova SN1979C in NGC 4321 SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4321); supernovae : general; supernovae : individual (SN 1979C) ID NOVA 1979C; SN 1979C; RADIO SUPERNOVAE; VIRGO CLUSTER; EMISSION; M100; DISTANCE; OUTBURST; SN-1979C; REGION AB We report on the X-ray observation of the radio-selected supernova SN 1979C carried out with ASCA in 1997 December and serendipitously available from a Chandra Guaranteed Time Observation in 1999 November. The supernova, of type SN II-linear (SN II-L), was first observed in the optical and occurred in the weakly barred, almost face-on spiral galaxy NGC 4321 (M100). The galaxy, a member of the Virgo S Cluster, is at a distance of 17.1 Mpc and contains at least three other supernovae discovered in this century. The useful exposure time was similar to 25 ks for the Solid-State Imaging Spectrometer (SIS), similar to 28 ks for the Gas Scintillation Imaging Spectrometer, and similar to2.5 ks for the Chandra Advanced CCD Imaging Spectrometer. No point source was detected at the radio position of SN 1979C in a 3' diameter, half-power response circle in the ASCA data. The background- and galaxy-subtracted supernova (SN) signal had a 3 sigma upper limit to the flux of 6.3 x 10(-14) ergs cm(-2) s(-1) in the full ASCA SIS band (0.4-10.0 keV) and a 3 sigma upper limit of less than (3-4) x 10(-14) erg cm(-2) s(-1) in the 2-10 keV band. In the Chandra data, a source at the position of SN 1979C is marginally detected at energies below 2 keV at a flux consistent with the ROSAT HRI detection in 1995. At energies above 2 keV, no source is detected with an upper limit of similar to3 x 10(-14) ergs cm(-2) s(-1). These measurements give the first ever X-ray flux limit of a Type II-L SN above 2 keV, which is an important diagnostic of the outgoing shock wave plowing through the circumstellar medium. C1 Tata Inst Fundamental Res, Mumbai 400005, India. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Aspen Ctr Phys, Aspen, CO USA. RP Ray, A (reprint author), Tata Inst Fundamental Res, Homi Bhabha Rd, Mumbai 400005, India. NR 36 TC 7 Z9 7 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2001 VL 122 IS 2 BP 966 EP 970 DI 10.1086/321172 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462PQ UT WOS:000170429300035 ER PT J AU Roe, HG Graham, JR Mc Lean, IS de Pater, I Becklin, EE Figer, DF Gilbert, AM Larkin, JE Levenson, NA Teplitz, HI Wilcox, MK AF Roe, HG Graham, JR Mc Lean, IS de Pater, I Becklin, EE Figer, DF Gilbert, AM Larkin, JE Levenson, NA Teplitz, HI Wilcox, MK TI The altitude of an infrared-bright cloud feature on Neptune from near-infrared spectroscopy SO ASTRONOMICAL JOURNAL LA English DT Article DE infrared radiation; planets and satellites : individual (Neptune) ID COORDINATED 1996 HST; ADAPTIVE OPTICS; ATMOSPHERIC STRUCTURE; ABSORPTION SPECTRA; H-2-HE PAIRS; METHANE; TEMPERATURES; TELESCOPE; BAND; CONSTRAINTS AB We present 2.03-2.30 mum near-infrared spectroscopy of Neptune taken 1999 June 2 (UT) with the W. M. Keck Observatory's near-infrared spectrometer (NIRSPEC) during the commissioning of the instrument. The spectrum is dominated by a bright cloud feature, possibly a storm or upwelling, in the southern hemisphere at approximately 50 degrees south latitude. The spectrum also includes light from a dimmer northern feature at approximately 30 degrees north latitude. We compare our spectra (lambda/Delta lambda similar to 2000) of these two features with a simple model of Neptune's atmosphere. Given our model assumption that the clouds are flat reflecting layers, we find that the top of the bright southern cloud feature sat at a pressure level of 0.14(-0.03)(+0.05) bars, and thus this cloud did not extend into the stratosphere (P less than or similar to 0.1 bars). A similar analysis of the dimmer northern feature yields a cloud-top pressure of 0.084 +/- 0.026 bars. This suggests that the features we observed efficiently transport methane to the base of the stratosphere but do not directly transport methane to the upper stratosphere (P < 10(-2) to 10(-3) bars), where photolysis occurs. Our observations do not constrain how far these clouds penetrate down into the troposphere. We find that our model fits to the data restrict the fraction of H(2) in ortho-para thermodynamic equilibrium to greater than 0.8. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Roe, HG (reprint author), Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA. NR 42 TC 6 Z9 6 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 2001 VL 122 IS 2 BP 1023 EP 1029 DI 10.1086/321157 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462PQ UT WOS:000170429300042 ER PT J AU Negishi, T Onaka, T Chan, KW Roellig, TL AF Negishi, T Onaka, T Chan, KW Roellig, TL TI Global physical conditions of the interstellar medium in nearby galaxies SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE galaxies : ISM; infrared : ISM; lines and bands : ISM; radiation mechanisms : thermal ID ISO-LWS SPECTROSCOPY; C-II LINE; PHOTODISSOCIATION REGIONS; STAR-FORMATION; VIRGO-CLUSTER; CENTAURUS-A; GHZ ATLAS; N-II; EMISSION; SAMPLE AB Far-infrared spectra (43-197 mum) of 34 nearby galaxies obtained by the Long Wavelength Spectrometer (LWS) aboard the Infrared Space Observatory (ISO) were analyzed to investigate the general properties of interstellar matter in galaxies. The present sample includes not only normal galaxies but also starbursts and active galactic nuclei (AGNs). Far-infrared forbidden lines, such as [C II]158 mum, [O I]63 mum, [N II]122 mum, and [O III]88 mum, were detected in most of the sample galaxies. [O I]145 mum line was detected in 13 galaxies. The line fluxes of [C II]158 mum and[N II]122 mum relative to the total far-infrared flux (FIR) decrease as the far-infrared color becomes bluer, while the ratio of the [O I]63 mum flux to FIR does not show a systematic trend with the color. The [O III]88 mum to FIR ratio shows a large scatter with a weak trend of increase with the color. AGNs do not show any distinguishable trend from normal and starburst galaxies in the far-infrared spectra, suggesting that the far-infrared emission is mainly driven by star-formation activities even in AGNs. We estimate the physical conditions of photodissociation regions (PDRs) in the sample galaxies, such as the far-ultraviolet radiation field intensity G(0) and the gas density n by assuming that all the observed [O I]63 mum and far-infrared continuum emissions come from PDRs. Comparison with PDR models indicates that G(0) ranges from 10(2)-10(4) and n similar to 10(2)-10(4) cm(-3). The present results also suggest that n varies proportionally with G(0). The ratio of [C II] 158 mum to CO (J = 1-0) line emission supports the linear increase in n with G(0). We estimate that about a half of [C II]158 mum emission originates from PDRs and attribute the rest to the emission as coming from low-density diffuse ionized gas. The estimated intensity of [C II]158 mum from the ionized gas is compatible with the observed intensity of [N II]122 mum if both lines come from the same diffuse ionized gas. The present analysis suggests that the decrease in [C II]158 mum/FIR with the far-infrared color may not be accounted for by the decrease in the photoelectric heating efficiency owing to the increase in positive charges of dust grains because a measure of the efficiency, G(0)/n, is found to stay constant with the far-infrared color. Instead the decrease can be interpreted in terms of either the increase in the collisional de-excitation of the [C ii] transition due to the increase in the gas density or the decrease in the ionized component relative to the far-infrared intensity suggested by the decrease in [N II]122 mum/FIR. Based on the present analysis, we derive average relations of the far-infrared color with G(0) and n in galaxies, which can be applied to the investigation of interstellar matter in distant galaxies. C1 Univ Tokyo, Sch Sci, Dept Astron, Bunkyo Ku, Tokyo 1130033, Japan. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Onaka, T (reprint author), Univ Tokyo, Sch Sci, Dept Astron, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan. EM onaka@astron.s.u-tokyo.ac.jp NR 66 TC 76 Z9 76 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 2001 VL 375 IS 2 BP 566 EP 578 DI 10.1051/0004-6361:20010817 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 458VL UT WOS:000170216100024 ER PT J AU Curdt, W Brekke, P Feldman, U Wilhelm, K Dwivedi, BN Schuhle, U Lemaire, P AF Curdt, W Brekke, P Feldman, U Wilhelm, K Dwivedi, BN Schuhle, U Lemaire, P TI The SUMER spectral atlas of solar-disk features SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : UV radiation; Sun : chromosphere; Sun : transition region; Sun : corona; line : identification; atlases ID CORONAL DIAGNOSTIC SPECTROMETER; EXTREME-ULTRAVIOLET SPECTRUM; QUIET-SUN; RADIOMETRIC CALIBRATION; SOHO MISSION; TELESCOPE; LINES; EMISSION; UV; SPECTROGRAPH AB A far-ultraviolet and extreme-ultraviolet (FUV, EUV) spectral atlas of the Sun between 670 Angstrom and 1609 Angstrom in the first order of diffraction has been derived from observations obtained with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory). The atlas contains spectra of the average quiet Sun, a coronal hole and a sunspot on the disk. Different physical parameters prevalent in the bright network (BN) and in the cell interior (CI)-contributing in a distinct manner to the average quiet-Sun emission-have their imprint on the BN/CI ratio, which is also shown for almost the entire spectral range. With a few exceptions, all major lines are given with their identifications and wavelengths. Lines that appear in second order are superimposed on the first order spectra. These lines are clearly marked in the atlas. The spectra include emissions from atoms and ions in the temperature range 6 x 10(3) K to 2 x 10(6) K, i.e., continua and emission lines emitted from the lower chromosphere to the corona. This spectral atlas, with its broad wavelength coverage, provides a rich source of new diagnostic tools to study the physical parameters in the chromosphere, the transition region and the corona. In particular, the wavelength range below 1100 Angstrom as observed by SUMER represents a significant improvement over the spectra produced in the past. In view of the manifold appearance and temporal variation of the solar atmosphere, it is obvious that our atlas can only be a-hopefully typical-snapshot. Brief descriptions of the data reduction and calibration procedures are given. The spectral radiances are determined with a relative uncertainty of 0.15 to 0.30 (1 sigma) and the wavelength scale is accurate to typically 10 m Angstrom. The atlas is also available in a machine readable form. C1 Max Planck Inst Aeron, D-37191 Katlenburg Duhm, Germany. Univ Oslo, Inst Theoret Astrophys, N-0315 Oslo 3, Norway. NASA, ESA, Dept Space Sci, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, EO Hulburt Ctr Space Res, Res Lab, Washington, DC 20375 USA. Banaras Hindu Univ, Dept Appl Phys, Varanasi 221005, Uttar Pradesh, India. Univ Paris 11, Inst Astrophys Spatiale, CNRS, Unite Mixte, F-91405 Orsay, France. RP Curdt, W (reprint author), Max Planck Inst Aeron, D-37191 Katlenburg Duhm, Germany. EM curdt@linmpi.mpg.de NR 64 TC 180 Z9 182 U1 2 U2 14 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 2001 VL 375 IS 2 BP 591 EP 613 DI 10.1051/004-6361:20010364 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 458VL UT WOS:000170216100027 ER PT J AU Patzold, M Hausler, B Wennmacher, A Aksnes, K Anderson, JD Asmar, SW Barriot, JP Boehnhardt, H Eidel, W Neubauer, FM Olsen, O Schmitt, J Schwinger, J Thomas, N AF Patzold, M Hausler, B Wennmacher, A Aksnes, K Anderson, JD Asmar, SW Barriot, JP Boehnhardt, H Eidel, W Neubauer, FM Olsen, O Schmitt, J Schwinger, J Thomas, N TI Gravity field determination of a comet nucleus: Rosetta at P/Wirtanen SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE celestial mechanics; space vehicles : Rosetta; comets : individual : 46 P/Wirtanen ID 46P/WIRTANEN; EROS AB One of the prime objectives of the Rosetta Radio Science Investigations (RSI) experiment is the determination of the mass, the bulk density and the low degree and order gravity of the nucleus of comet P/Wirtanen, the target object of the international Rosetta mission. The RSI experiment will use the spacecraft's radio carrier frequencies at X-band (8.4 GHz) and S-band (2.3 GHz) in order to measure slight changes of the orbit velocity via the classical Doppler effect induced by the gravity attraction of the comet nucleus. Based on an estimate of the background Doppler noise, it is expected that a mass determination (assuming a representative radius of 700 m and a bulk density of 500 kg/m(3)) at an accuracy of 0.1% can be achieved if the spacecraft's orbit is iteratively reduced below 7 km altitude. The gravity field of degree and order two can be detected for reasonable tracking times below 5 km altitude. The major competing forces acting on the spacecraft are the radiation pressure and the gas mass flux from cometary activity. While the radiation pressure may be predicted, it is recommended to begin a gravity mapping campaign well before the onset of outgassing activity (>3.25 AU heliocentric distance). Radial acceleration by water outgassing is larger by orders of magnitude than the accelerations from the low degree and order gravity field and will mask the contributions from the gravity field. C1 Univ Cologne, Inst Geophys & Meteorol, D-50923 Cologne, Germany. Univ Munich, Inst Raumfahrttech, D-85557 Neubiberg, Germany. Univ Oslo, Inst Theoret Astrophys, Oslo, Norway. CALTECH, Jet Prop Lab, Pasadena, CA 91107 USA. Observ Midi Pyrenees, F-31400 Toulouse, France. European So Observ, Santiago, Chile. Max Planck Inst Aeron, D-37189 Katlenburg Duhm, Germany. RP Patzold, M (reprint author), Univ Cologne, Inst Geophys & Meteorol, Albertus Magnus Pl, D-50923 Cologne, Germany. EM paetzold@geo.Uni-Koeln.DE; Bernd.Haeusler@UniBW-Muenchen.DE; wennmach@geo.Uni-Koeln.DE; Kaare.Aksnes@uio.no; John.D.Anderson@jpl.nasa.gov; Sami.W.Asmar@jpl.nasa.gov; jean-pierre.barriot@cnes.fr; hboehnha@eso.org; werner.eidel@UniBW-Muenchen.DE; Oystein.Olsen@uio.no; thomas@linmpi.mpg.de NR 25 TC 8 Z9 8 U1 0 U2 3 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG PY 2001 VL 375 IS 2 BP 651 EP 660 DI 10.1051/0004-6361:20010829 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 458VL UT WOS:000170216100033 ER PT J AU Gansicke, BT Szkody, P Sion, EM Hoard, DW Howell, S Cheng, FH Hubeny, I AF Gansicke, BT Szkody, P Sion, EM Hoard, DW Howell, S Cheng, FH Hubeny, I TI HST/STIS spectroscopy of the exposed white dwarf in the short-period dwarf nova EK TrA SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE accretion, accretion disks; stars : individual : EKTrA; stars : novae, cataclysmic variables; stars : white dwarfs; ultraviolet : stars ID CATACLYSMIC VARIABLES; VW HYI; TELESCOPE OBSERVATIONS; TRIANGULI AUSTRALIS; U-GEMINORUM; SUPEROUTBURST; QUIESCENCE; OUTBURST AB We present high resolution Hubble Space Telescope ultraviolet spectroscopy of the dwarf nova EK TrA obtained in deep quiescence. The Space Telescope Imaging Spectrograph data reveal the broad Ly alpha absorption profile typical of a moderately cool white dwarf, overlayed by numerous broad emission lines of He, C, N, and Si and by a number of narrow absorption lines, mainly of C I and Si II. Assuming a white dwarf mass in the range 0.3-1.4 M. we derive T-eff = 17 500-23 400 K for the primary in EK TrA; T-eff = 18 800 K for a canonical mass of 0.6 M.. From the narrow photospheric absorption lines, we measure the white dwarf rotational velocity, v sin i = 200 +/- 100 km s(-1). Even though the strong contamination of the photospheric white dwarf absorption spectrum by the emission lines prevents a detailed quantitative analysis of the chemical abundances of the atmosphere, the available data suggest slightly sub-solar abundances. The high time resolution of the STIS data allows us to associate the observed ultraviolet flickering with the emission lines, possibly originating in a hot optically thin corona above the cold accretion disk. C1 Univ Sternwarte, D-37083 Gottingen, Germany. Univ Washington, Dept Astron, Seattle, WA 98195 USA. Villanova Univ, Dept Astron & Astrophys, Villanova, PA 19085 USA. Natl Opt Astron Observ, Cerro Tololo Inter Amer Observ, La Serena, Chile. Planetary Sci Inst, Astrophys Grp, Tucson, AZ 85705 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20711 USA. RP Gansicke, BT (reprint author), Univ Sternwarte, Geismarlandstr 11, D-37083 Gottingen, Germany. EM boris@uni-sw.gwdg.de RI Gaensicke, Boris/A-9421-2012 OI Gaensicke, Boris/0000-0002-2761-3005 NR 24 TC 11 Z9 11 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 AUG PY 2001 VL 374 IS 2 BP 656 EP 661 DI 10.1051/004-6361:20010787 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 458VH UT WOS:000170215800027 ER PT J AU Moran, TG AF Moran, TG TI Interpretation of coronal off-limb spectral line width measurements SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : corona; solar wind; solar-terrestrial relations ID HOLES; SUMER; SOHO AB Spectral line widths measured above the solar limb have been used to infer wave velocity amplitude height dependencies, supporting Alfven wave coronal heating and wave driven solar wind models. Comparison of the inferred amplitude/density dependence with a constant magnetic field strength, undamped wave propagation model have shown good agreement, providing the first strong support of Alfven wave heating models. We derive the density dependence for wave propagation in an expanding flux tube with decreasing field strength, and show that the resulting density dependence is identical to that of the constant field strength case. We use the expanding flux tube propagation model to infer the wave amplitude in the low photosphere, which is a factor of 9 lower than granulation velocities. C1 Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Moran, TG (reprint author), Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. EM moran@orpheus.nascom.nasa.gov NR 7 TC 28 Z9 28 U1 1 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 AUG PY 2001 VL 374 IS 2 BP L9 EP L11 DI 10.1051/0004-6361:20010643 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 458VH UT WOS:000170215800001 ER PT J AU Loewenstein, M AF Loewenstein, M TI The contribution of population III to the enrichment and preheating of the intracluster medium SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : general; galaxies : formation; intergalactic medium; stars : abundances ID INITIAL MASS FUNCTION; INTRA-CLUSTER MEDIUM; METAL-LINE RATIOS; LY-ALPHA FOREST; INTERGALACTIC MEDIUM; ELLIPTIC GALAXIES; ABUNDANCES; GAS; FRAGMENTATION; EVOLUTION AB Intracluster medium (ICM) abundances are higher than expected assuming enrichment by supernovae with progenitors belonging to the simple stellar population (SSP) observed in cluster galaxies if stars formed with a standard initial mass function (IMF). Moreover, new results on ICM oxygen abundances imply that nucleosynthesis occurred with nonstandard yields. The hypothesis that hypernovae in general, and hypernovae associated with Population III (Pop III) stars in particular, may significantly contribute to ICM enrichment is presented and evaluated. The observed abundance anomalies can be explained by a hypernova-producing subpopulation of the SSP, but only if the subpopulation accounts for half of all supernova explosions and if Type Ia supernova rates are very low. Also, the implied energy release may be excessive. However, an independent Pop III contribution-in the form of metal-free, very massive stars that evolve into hypernovae-can also account for all of the observed abundances while avoiding these drawbacks and accommodating a normal IMF in subsequent stellar generations. The required number of Pop III stars provides sufficient energy injection (at high redshift) to explain the ICM "entropy floor." Pop III hypernovae preenrich the intergalactic medium and can produce a significant fraction of the metals observed in the Ly alpha forest. Several testable predictions for ICM and intergalactic medium observations are made. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Loewenstein, M (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 44 TC 42 Z9 42 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG PY 2001 VL 557 IS 2 BP 573 EP 577 DI 10.1086/322256 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 467LN UT WOS:000170704800008 ER PT J AU Jewell, J AF Jewell, J TI A statistical characterization of Galactic dust emission as a non-Gaussian foreground of the cosmic microwave background SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; dust, extinction; methods : statistical ID COSMOLOGICAL DENSITY PERTURBATIONS; INFLATIONARY UNIVERSE; WAVELETS; MAPS; REIONIZATION; FLUCTUATIONS AB A statistical characterization of the Galactic dust emission as observed in the Infrared Astronomical Satellite (IRAS) maps of Schlegel and colleagues is provided by the continuous wavelet transform. The wave-let coefficients of the dust emission have highly non-Gaussian marginal densities, as quantified by their skewness and kurtosis. An information theoretic measure of the distinguishability of the IRAS maps and random phase realizations is also investigated and found to give a highly significant detection of non-Gaussianity. The efficiency of these wavelet-based statistics is quantified by the rate at which the detection of non-Gaussianity is lost as a function of the fraction of phases randomized. The statistics considered here can be used to test for residual dust emission in maps of the cosmic microwave background, or to test for non-Gaussianity of a spatially localized nature. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jewell, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-506, Pasadena, CA 91109 USA. NR 25 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG PY 2001 VL 557 IS 2 BP 700 EP 713 DI 10.1086/321677 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 467LN UT WOS:000170704800020 ER PT J AU Langer, WD Willacy, K AF Langer, WD Willacy, K TI Preprotostellar core properties from far-infrared observations SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; infrared : ISM : continuum; ISM : clouds; ISM : individual (B68, B133, L1498) ID MOLECULAR CLOUD CORES; DENSE CORES; DARK CLOUDS; AMBIPOLAR DIFFUSION; MAGNETIC BRAKING; STAR-FORMATION; DUST EMISSION; PROTOSTARS; ISOCAM; EXTINCTION AB We, present the results of far-infrared ISOPHOT observations of the preprotostellar cores L1498, B133, and B68. Comparison of the 100 and 200 mum data suggest the presence of two dust temperatures along the line, of sight. Using a two-temperature model that assumes a cold central core surrounded by a slightly warmer envelope, we have isolated the 200 mum emission from the cold core. We use 160 and 1300 mum observations where available together with the isolated 200 mum data to derive a dust temperature for the core. The radial mass and density distributions were determined in each core, and the stability of the cores was considered by comparing the mass estimates from the 200 Pm data with the virial masses. The cores can be divided into three regions with different radial density dependences, each of which can be described by a power law rho proportional to r(-alpha) : a relatively flat inner region with alpha similar to 1.2, a steeper region with alpha similar to 1.8, and a very sharp outer edge with alpha greater than or similar to 4. These power-law results are in agreement with other derivations of preprotostellar core density profiles. The results presented here are also consistent with several different models of core evolution. In addition, we find that the inner regions of the core are less bound than the outer ones, suggesting that the outer layers are confining the central regions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Langer, WD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-506, Pasadena, CA 91109 USA. NR 43 TC 11 Z9 11 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG PY 2001 VL 557 IS 2 BP 714 EP 726 DI 10.1086/322257 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 467LN UT WOS:000170704800021 ER PT J AU Lin, RP Feffer, PT Schwartz, RA AF Lin, RP Feffer, PT Schwartz, RA TI Solar hard X-ray bursts and electron acceleration down to 8 kev SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; Sun : corona; Sun : flares; Sun : X-rays, gamma rays ID QUIET SUN; FREQUENCY-DISTRIBUTIONS; TRANSIENT BRIGHTENINGS; ENERGY-DISTRIBUTION; FLARES; NANOFLARES; CORONA; PARAMETERS; MICROFLARES; ENERGETICS AB In 2 days that were typical of solar maximum (1991 October 1-2), the CGRO/BATSE Spectroscopy Detectors observed more than five solar X-ray bursts per hour above 8 keV [8-13 keV flux greater than 0.4 (cm(2) s keV)(-1)]. Only approximately one-third of these were detected above 25 keV [25-59 keV flux greater than 1.7 x 10(-3) (cm(2) s keV)(-1)] by the BATSE Large Area Detectors (LADs). Most of the >8 keV bursts are impulsive and similar to solar hard X-ray bursts observed above 20 keV-the bursts occurred on the most rapid rise of the GOES thermal soft X-ray burst, and the ratio of 8-13 keV to greater than 13 keV flux for the impulsive bursts fitted a power-law spectrum [dJ/d(h nu) similar to (h nu)(-gamma)] with gamma = 3-7. More than half of the bursts that should be detected by the LADs if the power law extends to high energies are not detected, indicating that the spectrum steepens or cuts off above similar to 25 keV. These findings suggest that the acceleration of electrons occurs for essentially all impulsive energy releases but may only be detectable at low energies in smaller releases. The burst occurrence frequency vanes with energy TV(>8 keV) in accelerated electrons as dn/dW similar to W-1.6 above W similar to 10(29) ergs, with an average rate of energy deposition of similar to 10(26) ergs s(-1), about 100 times that above 20 keV. Comparison with the occurrence frequency of the energy content in active region transient brightenings (ARTBs) detected by the Yohkoh soft X-ray telescope suggests that accelerated electrons may provide a significant fraction of the total energy in ARTBs. C1 Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Raytheon Informat Technol & Sci Serv, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Lin, RP (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NR 31 TC 43 Z9 43 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG PY 2001 VL 557 IS 2 BP L125 EP L128 DI 10.1086/323270 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 467LM UT WOS:000170704700012 ER PT J AU Berger, E Diercks, A Frail, DA Kulkarni, SR Bloom, JS Sari, R Halpern, J Mirabel, N Taylor, GB Hurley, K Pooley, G Becker, KM Wagner, RM Terndrup, DM Statler, T Wik, DR Mazets, E Cline, T AF Berger, E Diercks, A Frail, DA Kulkarni, SR Bloom, JS Sari, R Halpern, J Mirabel, N Taylor, GB Hurley, K Pooley, G Becker, KM Wagner, RM Terndrup, DM Statler, T Wik, DR Mazets, E Cline, T TI GRB 000418: A hidden jet revealed SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; infrared : general; radio continuum : general ID GAMMA-RAY-BURST; LIGHT CURVES; RADIO AFTERGLOW; SUPERNOVA; SYSTEMS; SCINTILLATION; PROGENITORS; PHOTOMETRY; GRB-991216; FIREBALL AB We report on optical, near-infrared, and centimeter radio observations of GRB 000418 that allow us to follow the evolution of the afterglow from 2 to 200 days after the gamma -ray burst (GRB). In modeling these broadband data, we find that an isotropic explosion in a constant-density medium is unable to simultaneously fit both the radio and optical data. However, a jetlike outflow into either a constant density or wind-stratified medium with an opening angle of 10 degrees -20 degrees provides a good description of the data. The evidence in favor of a jet interpretation is based on the behavior of the radio light curves, since the expected jet break is masked at optical wavelengths by the light of the host galaxy. We also find evidence for extinction, presumably arising from within the host galaxy, with A(V)(host) = 0.4 mag, as well as host flux densities of F-R = 1.1 mu Jy and F-K = 1.7 mu Jy. These values supersede previous work on this burst as a result of the availability of a broadband data set allowing a global fitting approach. A model in which the GRB explodes isotropically into a wind-stratified circumburst medium cannot be ruled out by these data. However, in examining a sample of other bursts (e.g., GRB 990510, GRB 000301C), we favor the jet interpretation for GRB 000418. C1 CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Natl Radio Astron Observ, Socorro, NM 87801 USA. Columbia Univ, Dept Astron, New York, NY 10027 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Cambridge, Cavendish Lab, Mullard Radio Astron Observ, Cambridge CB3 0HE, England. Oberlin Coll, Dept Phys, Oberlin, OH 44074 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Ohio Univ, Clippinger Res Labs, Dept Phys & Astron, Athens, OH 45701 USA. AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Berger, E (reprint author), CALTECH, Palomar Observ, Mail Code 105-24, Pasadena, CA 91125 USA. NR 50 TC 52 Z9 52 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2001 VL 556 IS 2 BP 556 EP 561 DI 10.1086/321612 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300003 ER PT J AU Chatzichristou, ET AF Chatzichristou, ET TI Multicolor optical imaging of infrared-warm Seyfert galaxies. III. Surface photometry: Light profile decomposition SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : interactions; galaxies : photometry; galaxies : Seyfert ID ACTIVE GALACTIC NUCLEI; DISK DOMINATED GALAXIES; POINT-SOURCE CATALOG; SPIRAL GALAXIES; X-RAY; BRIGHTNESS DISTRIBUTIONS; MORPHOLOGICAL ANALYSIS; MULTIBAND ANALYSIS; FIELD GALAXIES; UCM GALAXIES AB This paper is the third in a series studying the optical properties of a sample of mid-infrared warm Seyfert galaxies and a control sample of mid-infrared cold galaxies. This paper is devoted to the analysis of the radial light distributions characterizing the galaxies outside their central 2 kpc. The light profiles are decomposed in inner and outer components using two generalized exponentials. Each component is characterized by a profile shape, a central surface brightness, and a scale length. We find that the warm Seyfert 1 galaxies tend to he in earlier-type hosts with more centrally concentrated light profiles as compared with the warm Seyfert 2 galaxies: the Seyfert 1 and 2 bulges have similar shapes, but the former are characterized by larger central surface brightness and smaller scale length. The cold galaxies are disk-dominated systems with complex morphologies. All these differences are confirmed at statistical significance levels better than 95%. The three parameters characterizing the bulge component correlate with each other for all samples within a limited range of bulge luminosities. The disk structural parameters span similar ranges (with large scatter) for both warm and cold samples. The parametrization of light profiles, as described in this paper, shows that the warm Seyfert 1, Seyfert 2, and cold samples occupy different loci in parameter space, clearly suggesting intrinsic differences between their host galaxy populations. This conclusion will be reinforced in two forthcoming papers, in which we will explore the color distributions and the interaction characteristics of our samples. C1 Leiden Observ, NL-2300 RA Leiden, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands. EM eleni@astarti.gsfe.nasa.gov NR 81 TC 4 Z9 4 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2001 VL 556 IS 2 BP 653 EP 675 DI 10.1086/323672 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300011 ER PT J AU Chatzichristou, ET AF Chatzichristou, ET TI Multicolor optical imaging of infrared-warm Seyfert galaxies. IV. Surface photometry: Color distributions SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : interactions; galaxies : photometry; galaxies : Seyfert ID INITIAL MASS FUNCTION; POINT-SOURCE CATALOG; STAR-FORMATION; STELLAR POPULATIONS; SPECTRAL EVOLUTION; IRAS OBSERVATIONS; DISK GALAXIES; GRADIENTS; SAMPLE; DUST AB This paper is the fourth in a series studying the optical properties of a sample of mid-infrared warm Seyfert galaxies and of a control sample of mid-infrared cold galaxies. The present paper is devoted to the analysis of the color distributions characterizing the hosts. The warm Seyfert 1 and 2 galaxies show opposite color gradients and their color profiles are depicting age and dust effects within single-burst, solar-metallicity models. In particular, we find ample evidence for the occurrence of strong star formation in the Seyfert 2 disks: their color and emission line two-dimensional maps suggest dust extinction associated with ongoing star formation in spiral and tidal features; their color profiles show starbursts of 0.5-1 Gyr or younger, superposed on the older underlying galaxy population. Most of these properties are shared with the cold galaxies, while the warm Seyfert 1 galaxies show mostly older stellar populations and, in only a few cases, evidence for circumnuclear star formation. C1 Leiden Observ, NL-2300 RA Leiden, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chatzichristou, ET (reprint author), Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands. NR 34 TC 5 Z9 6 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2001 VL 556 IS 2 BP 676 EP 693 DI 10.1086/323673 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300012 ER PT J AU Jorstad, SG Marscher, AP Mattox, JR Aller, MF Aller, HD Wehrle, AE Bloom, SD AF Jorstad, SG Marscher, AP Mattox, JR Aller, MF Aller, HD Wehrle, AE Bloom, SD TI Multiepoch Very Long Baseline Array observations of EGRET-detected quasars and BL Lacertae objects: Connection between superluminal ejections and gamma-ray flares in blazars SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects : general; galaxies : jets; gamma rays : observations; quasars : general; radio continuum : galaxies ID VLBI OBSERVATIONS; RADIO-SOURCES; JET; MODELS; GHZ AB We examine the coincidence of times of high gamma -ray flux and ejections of superluminal components from the core in EGRET blazars based on a Very Long Baseline Array (VLBA) monitoring program at 22 and 43 GHz from 1993 November to 1997 July. In 23 cases of gamma -ray flares for which sufficient VLBA data exist, 10 of the flares (in eight objects) fall within 1 sigma uncertainties of the extrapolated epoch of zero separation from the core of a superluminal radio component. In each of two sources (0528 + 134 and 1730-130), two successive gamma -ray flares were followed by the appearance of new superluminal components. We carried out statistical simulations that show that if the number of coincidences is greater than or equal to 10, the radio and gamma -ray events are associated with each other at greater than 99.999% confidence. Our analysis of the observed behavior, including variability of the polarized radio flux, of the sources before, during, and after the gamma -ray flares suggests that the gamma -ray events occur in the superluminal radio knots. This implies that the gamma -ray flares are caused by inverse Compton scattering by relativistic electrons in the parsec-scale regions of the jet rather than closer to the central engine. C1 Boston Univ, Inst Astrophys Res, Boston, MA 02215 USA. St Petersburg State Univ, Astron Inst, St Petersburg 198904, Russia. Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Hampden Sydney Coll, Hampden Sydney, VA 23943 USA. RP Jorstad, SG (reprint author), Boston Univ, Inst Astrophys Res, 725 Commonwealth Ave, Boston, MA 02215 USA. RI Jorstad, Svetlana/H-6913-2013 OI Jorstad, Svetlana/0000-0001-9522-5453 NR 30 TC 138 Z9 140 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2001 VL 556 IS 2 BP 738 EP 748 DI 10.1086/321605 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300016 ER PT J AU Walker, RC Benson, JM Unwin, SC Lystrup, MB Hunter, TR Pilbratt, G Hardee, PE AF Walker, RC Benson, JM Unwin, SC Lystrup, MB Hunter, TR Pilbratt, G Hardee, PE TI The structure and motions of the 3C 120 radio jet on scales of 0.6-300 parsecs SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (3C 120); galaxies : jets; hydrodynamics radio; continuum : galaxies; relativity ID SUPERLUMINAL MOTION; MERLIN OBSERVATIONS; RELATIVISTIC JETS; GALAXY 3C120; 3C-120; VARIABILITY; EMISSION; 3C-345; VLBI; GHZ AB Results are presented from long-term very long baseline interferometry monitoring of the parsec-scale radio jet in 3C 120 at 5 and 1.7 GHz. The 5 GHz sequence includes a few early epochs at 10.7 GHz. Superluminal features are seen leaving the core at intervals of less than a year, about as often as new features could be distinguished with the 0.6 pc resolution of the observations. The underlying jet is continuous but not smooth, and the measured features are simply the bright points in the convolution of the observing beam with brightness fluctuations that occur on many scales. The velocity of different features varies, but not by more than about a factor of 2. Clear variations in the velocity of an individual feature are not seen. Some features that were observed leaving the core in the 5 GHz observations with 0.6 pc resolution are followed at 1.7 GHz with 2.4 pc resolution to projected distances in excess of 25 pc from the core. Older features up to at least 150 pc in projection from the core are still moving at superluminal apparent speeds and are therefore presumed to be relativistic. Beyond that, the data are inadequate for motion measurements. The region where the jet slows to nonrelativistic speeds has not been found. There are suggestions of stationary features, or brightening and dimming regions, through which the moving features pass. These may be locations where there is interaction with the external medium, or they may simply be the result of variations in the jet angle to the line of sight. The observation of stationary features in an otherwise moving jet reinforces the idea that the lack of motion of the knot at 4 " (2 kpc), which has been found not to be superluminal in other observations, might not actually imply that the jet has slowed by that position. The structure of the jet in the vicinity of the most likely stationary feature is suggestive of a helical pattern seen in projection. The deprojected wavelength of the pattern is very long relative to the jet radius, unlike the situation in sources such as M87 (Owen and coworkers). If the 3C 120 jet does contain a slowly moving, helical structure, then theory suggests that the jet resides in a relatively cool medium, not in a relativistically hot cocoon or lobe. C1 Natl Radio Astron Observ, Socorro, NM 87801 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Portland State Univ, Portland, OR 97207 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. ESA, Div Astrophys, Dept Space Sci, Noordwijk, Netherlands. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. RP Walker, RC (reprint author), Natl Radio Astron Observ, Socorro, NM 87801 USA. NR 36 TC 34 Z9 34 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2001 VL 556 IS 2 BP 756 EP 772 DI 10.1086/321548 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300018 ER PT J AU Cannizzo, JK AF Cannizzo, JK TI The V-EUV delay for dwarf nova outbursts: A case study for VW Hydri, U Geminorum, and SS Cygni SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; stars : dwarf novae; stars : individual (SS Cygni, U Geminorum, VW Hydri) ID DISK-INSTABILITY MODEL; WEAKLY MAGNETIZED DISKS; LOCAL SHEAR INSTABILITY; CLOSE BINARY-SYSTEMS; X-RAY BINARIES; ACCRETION DISKS; CATACLYSMIC VARIABLES; LIMIT-CYCLE; PARAMETER-ALPHA; LINEAR-ANALYSIS AB We present a parameter study using time-dependent calculations of the thermal limit cycle model for dwarf nova outbursts. Our goal is to delineate the dependence of the delay between the initial rapid rise of the visual and EUV fluxes during the start of an outburst on model parameters, concentrating on three bright nearby systems for which complete optical and EUV observations exist: VW Hydri, U Geminorum, and SS Cygni. For each system we compute 15 models spanning the early part of an outburst, taking the ratio of the instigation radius to the outer disk radius to be 0.5, 0.7, or 1.0 and adopting a value for the alpha viscosity parameter in the ionized disk of 0.1, 0.15, 0.2, 0.25, or 0.3. We confirm Smak's findings, which show a consistency of the standard model with observations. For these systems we infer that the outburst must be triggered at similar to0.7-0.8 of the outer disk radius to produce delays that are in accord with observations. We show that the level of EUV flux in outburst is dictated by the amount of material carried within the inward-moving heating front spike as it reaches the inner edge of the disk, and we reaffirm earlier work by Meyer et al. that found the heating front speed to be given by the alpha parameter times the sound speed within the heating spike. We also see a stagnation, or period of slow warming (first noted by Mineshige), during the early stages of thermal instability but find that it does not influence the V-EUV delay since it precedes the rapid rise in V at the start of the outburst. In studying the sensitivity of our results to the initial mass distribution, we find that if one decreases the surface density in the inner disk, interior to the instigation radius, the V-EUV delay can be lengthened by as much as a factor of 2. In addition, we find there to be a weak relation between the V-EUV delay and the value of the alpha viscosity parameter in quiescence. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Emergent Informat Technol Inc, Greenbelt, MD 20771 USA. RP Cannizzo, JK (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Emergent Informat Technol Inc, Code 662, Greenbelt, MD 20771 USA. EM cannizzo@stars.gsfc.nasa.gov NR 63 TC 15 Z9 15 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 1 PY 2001 VL 556 IS 2 BP 847 EP 857 DI 10.1086/321595 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300025 ER PT J AU Ackerman, AS Marley, MS AF Ackerman, AS Marley, MS TI Precipitating condensation clouds in substellar atmospheres SO ASTROPHYSICAL JOURNAL LA English DT Article DE planetary systems; stars : low-mass, brown dwarfs ID EXTRASOLAR GIANT PLANETS; TROPOSPHERIC GAS-COMPOSITION; NORTH EQUATORIAL BELT; BROWN DWARFS; BOUNDARY-LAYER; JUPITER; MODELS; SPECTRA; ALBEDO; MICROPHYSICS AB We present a method to calculate vertical profiles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent diffusion and sedimentation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with results from previous methods. An adjustable parameter describing the efficiency of sedimentation allows the new model to span the range of predictions made by previous models. Calculations for the Jovian ammonia cloud are consistent with observations. Example calculations are provided for water, silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant planet. We find that precipitating cloud decks naturally account for the characteristic trends seen in the spectra of L- and T-type ultracool dwarfs. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ackerman, AS (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Ackerman, Andrew/D-4433-2012; Marley, Mark/I-4704-2013 OI Ackerman, Andrew/0000-0003-0254-6253; NR 61 TC 330 Z9 333 U1 2 U2 6 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2001 VL 556 IS 2 BP 872 EP 884 DI 10.1086/321540 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300027 ER PT J AU Mitchell, RC Baron, E Branch, D Lundqvist, P Blinnikov, S Hauschildt, PH Pun, CSJ AF Mitchell, RC Baron, E Branch, D Lundqvist, P Blinnikov, S Hauschildt, PH Pun, CSJ TI Ni-56 mixing in the outer layers of SN 1987A SO ASTROPHYSICAL JOURNAL LA English DT Article DE line : formation; nuclear reactions, nucleosynthesis, abundances; radiative transfer; supernovae : individual (SN 1987A) ID LATE SPECTRAL EVOLUTION; SUPERNOVA 1987A; LIGHT-CURVE; MODEL ATMOSPHERES; LINE EMISSION; DREDGE-UP; SN-1987A; 1993J; NUCLEOSYNTHESIS; INSTABILITIES AB Supernova 1987A remains the most well observed and well studied supernova to date. Observations have produced excellent broadband photometric and spectroscopic coverage over a wide wavelength range at all epochs. Here we focus on the very early spectroscopic observations. Only recently have numerical models been of sufficient detail to accurately explain the observed spectra. In SN 1987A, good agreement has been found between observed and synthetic spectra for day 1, but by day 4, the predicted Balmer lines become much weaker than the observed lines. We present the results of work based on a radiation-hydrodynamic model by Blinnikov and collaborators. Synthetic non-LTE spectra generated from this model by the general radiation transfer code PHOENIX strongly support the theory that significant mixing of Ni-56 into the outer envelope is required to maintain strong Balmer lines. Preliminary results suggest a lower limit to the average nickel mass of 1.0 x 10(-5) M. is required above 5000 km s(-1) by day 4. PHOENIX models thus have the potential to be a sensitive probe for nickel mixing in the outer layers of a supernova. C1 Univ Oklahoma, Dept Phys & Astron, Norman, OK 73019 USA. Stockholm Univ, Stockholm Observ, SE-13336 Saltsjobaden, Sweden. Inst Theoret & Expt Phys, Moscow 117218, Russia. Univ Georgia, Dept Phys & Astron, Athens, GA 30602 USA. Univ Georgia, Ctr Simulat Phys, Athens, GA 30602 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Mitchell, RC (reprint author), Univ Oklahoma, Dept Phys & Astron, 440 W Brooks St, Norman, OK 73019 USA. EM mitchell@mail.nhn.ou.edu; baron@maii.nhn.ou.edu; branch@mail.nhn.ou.edu; peter@astro.su.se; blinn@sai.msu.su; yeti@hal.physast.uga.edu; pun@congee.gsfc.nasa.gov RI Baron, Edward/A-9041-2009 OI Baron, Edward/0000-0001-5393-1608 NR 42 TC 22 Z9 22 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 1 PY 2001 VL 556 IS 2 BP 979 EP 986 DI 10.1086/321623 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300038 ER PT J AU Harding, AK Muslimov, AG AF Harding, AK Muslimov, AG TI Pulsar polar cap heating and surface thermal X-ray emission. I. Curvature radiation pair fronts SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : general; radiation mechanisms : nonthermal; relativity; stars : neutron; X-rays : stars ID NEUTRON-STAR; GAPS; CASCADES AB We investigate the effect of pulsar polar cap (PC) heating produced by positrons returning from the upper pair formation front. Our calculations are based on a self-consistent treatment of the pair dynamics and the effect of electric field screening by the returning positrons. We calculate the resultant X-ray luminosities and discuss the dependence of the PC heating efficiencies on pulsar parameters, such as characteristic spin-down age, spin period, and surface magnetic field strength. In this study we concentrate on the regime where the pairs are produced in a magnetic field by curvature photons emitted by accelerating electrons. Our theoretical results are not in conflict with the available observational X-ray data and suggest that the effect of PC heating should significantly contribute to the thermal X-ray fluxes from middle-aged and old pulsars. The implications for current and future X-ray observations of pulsars are briefly outlined. C1 NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Emergent Informat Technol Inc, Space Sci Sector, Upper Marlboro, MD 20774 USA. RP Harding, AK (reprint author), NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 32 TC 95 Z9 95 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2001 VL 556 IS 2 BP 987 EP 1001 DI 10.1086/321589 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462NC UT WOS:000170425300039 ER PT J AU Lehner, N Fullerton, AW Sembach, KR Massa, DL Jenkins, EB AF Lehner, N Fullerton, AW Sembach, KR Massa, DL Jenkins, EB TI The influence of stellar wind variability on measurements of interstellar OVI along sight lines to early-type stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE line : profiles; stars : early-type; stars : mass loss; stars : winds, outflows ID PROFILES AB A primary goal of the Far Ultraviolet Spectroscopic Explorer mission is to understand the origin of the O VI ion in the interstellar medium of the Galaxy and the Magellanic Clouds. Along sight lines to OB-type stars, these interstellar components are usually blended with O VI stellar wind profiles, which frequently vary in shape. In order to assess the effects of this time-dependent blending on measurements of the interstellar O VI lines, we have undertaken a minisurvey of repeated observations toward OB-type stars in the Galaxy and the Large Magellanic Cloud. These sparse time series, which consist of two to three observations separated by intervals ranging from a few days to several months, show that wind variability occurs commonly in O VI (similar to 60% of a sample of 50 stars), as indeed it does in other resonance lines. However, in the interstellar O VI lambda 1032 region, the O VI lambda 1038 wind varies only in similar to 30% of the cases. By examining cases exhibiting large amplitude variations, we conclude that stellar wind variability generally introduces negligible uncertainty for single interstellar O VI components along Galactic lines of sight but can result in substantial errors in measurements of broader components or blends of components like those typically observed toward stars in the Large Magellanic Cloud. Due to possible contamination by discrete absorption components in the stellar O VI line, stars with terminal velocities greater than or equal to the doublet separation (1654 km s(-1)) should be treated with care. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. NASA, Goddard Space Flight Ctr, Emergent IT, Greenbelt, MD 20771 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. RP Lehner, N (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. RI Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 14 TC 13 Z9 13 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 2001 VL 556 IS 2 BP L103 EP L106 DI 10.1086/323025 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462ND UT WOS:000170425400009 ER PT J AU Stephens, DC Marley, MS Noll, KS Chanover, N AF Stephens, DC Marley, MS Noll, KS Chanover, N TI L-band photometry of L and T dwarfs SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : low-mass, brown dwarfs ID INFRARED SPECTRAL CLASSIFICATION; DIGITAL SKY SURVEY; LOW-MASS STARS; BROWN DWARFS; STANDARD STARS; MAIN-SEQUENCE; ATMOSPHERES; METHANE; COLORS; DENIS AB We present K- and L-band photometry obtained with the Keck I telescope for a representative sample of L and T dwarfs. These observations were motivated in part by the dominant role H(2)O and CH(4) play in shaping the flux near 2 and 3 mum and by the potential use of these bands as indicators of spectral class in the infrared. In addition, these observations aid the determination of the bolometric luminosity of L and T dwarfs. Here we report the K, L', and L(s) magnitudes of our objects and the trends observed in the (K-L') and (K-L(s)) colors as a function of L and T dwarf spectral class. We compare these colors with theoretical models, derive a relationship between effective temperature and L spectral class, and compare our temperature estimates with others. C1 New Mexico State Univ, Dept Astron, Las Cruces, NM 88012 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Stephens, DC (reprint author), New Mexico State Univ, Dept Astron, Box 30001,MSC 4500, Las Cruces, NM 88012 USA. EM densteph@nmsu.cdu; mmarley@nmsu.edu; noll@stsci.edu; nchanove@nmsu.edu RI Noll, Keith/C-8447-2012; Marley, Mark/I-4704-2013 NR 28 TC 24 Z9 24 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 1 PY 2001 VL 556 IS 2 BP L97 EP L101 DI 10.1086/322938 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 462ND UT WOS:000170425400008 ER PT J AU Mattox, JR Hartman, RC Reimer, O AF Mattox, JR Hartman, RC Reimer, O TI A quantitative evaluation of potential radio identifications for 3EG EGRET sources SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies : active; gamma rays : observations; quasars : general ID NRAO PMN SURVEYS; SOURCE CATALOG; GAMMA-RAYS AB The method of Mattox et al. for identifying EGRET sources with 5 GHz radio sources has been applied to the 3EG EGRET catalog of Hartman et al. Complete results are tabulated. We tabulate separately 46 EGRET sources with radio identifications which we expect to have a high probability of being correct. We suggest that these sources are appropriate for most studies of the properties of c-ray blazars as a class. All but one of these 46 sources were classified by Hartman et al. as high-confidence identifications; and the additional source was classified by Hartman et al. as a plausible identification. We also tabulate separately 37 additional "plausible identifications of EGRET sources with radio sources" These less secure possibilities include the remaining 21 "high-confidence identifications" of Hartman et al., three of the 27 "lower confidence potential blazar identifications" of Hartman et al., and an additional 15 plausible identifications which have not been suggested previously. Many of these sources require new radio and optical observations to establish them as blazars. We suggest that the 23 "lower-confidence potential blazar identifications" of Hartman et al. which we do not find plausible should not be used in studies of the properties of the EGRET blazars. For this analysis, we have made elliptical fits to the 95% confidence contours of the position uncertainty regions of the 3EG sources which are tabulated in an Appendix. C1 Boston Univ, Inst Astrophys Res, Boston, MA 02215 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Mattox, JR (reprint author), Boston Univ, Inst Astrophys Res, 725 Commonwealth Ave, Boston, MA 02215 USA. RI Reimer, Olaf/A-3117-2013 OI Reimer, Olaf/0000-0001-6953-1385 NR 20 TC 131 Z9 132 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD AUG PY 2001 VL 135 IS 2 BP 155 EP 175 DI 10.1086/321782 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 460TC UT WOS:000170323800002 ER PT J AU Koscheyev, VS Leon, GR Trevino, RC AF Koscheyev, VS Leon, GR Trevino, RC TI Efficacy of wrist/palm warming as an EVA countermeasure to maintain finger comfort in cold conditions SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE thermoregulation; wrist/palm warming; finger comfort AB Introduction: This study explored the effectiveness of local wrist/palm warming as a potential countermeasure for providing finger comfort during extended duration EVA. Methods: There were six subjects (five males and one female) who were evaluated in a liquid cooling/warming garment (LCWG) wearing modified liquid cooling/warming (LCW) gloves in three different experimental conditions: Condition 1: Stage 1 no LCWG, LCW glove inlet water temperature 33 degreesC; Stage 2 - no LCWG, LCW glove inlet water temperature cooled to 8 degreesC; Stage 3 - no LCWG, LCW glove inlet water temperature warmed to 45 degreesC; Condition 2: Stage 1 - LCWG and LCW glove inlet water temperature 33 degreesC; Stage 2 - LCWG inlet temperature cooled to 31 degreesC, LCW gloves, 8 degreesC; Stage 3 - LCWG inlet water temperature remains at 3 1 OC, LCW glove inlet water temperature warmed to 45 degreesC; Condition 3: Stage 1 - LCWG and LCW gloves 33 degreesC; Stage 2 - LCWG inlet water temperature cooled to 28 degreesC, LCW gloves, 8 degreesC; Stage 3 - LCWG remains at 28 degreesC, LCW glove water temperature warmed to 45 degreesC. Results: Wrist/palm area warming showed a statistically significant increase in finger temperature (T-fing) in Stage 3 compared with Stage 2. Blood perfusion showed a trend toward a significantly greater value in Stage 3 compared with Stage 2. The LCW gloves were significantly more effective in increasing Stage 3 Tfing in Condition 1 (33 degreesC) compared with Condition 3 (28 degreesC). Across conditions, subjective perception of heat in the hands was significantly greater at Stage 3 than Stage 2; perception of overall body heat showed a trend for higher heat ratings in Stage 3 than Stage 2. Conclusions: Local wrist/palm warming was effective in increasing blood circulation to the distal upper extremities, suggesting the potential usefulness of this technique for enhancing astronaut comfort during EVA while decreasing power requirements. C1 Univ Minnesota, Dept Psychol, Minneapolis, MN 55455 USA. NASA, Lyndon B Johnson Space Ctr, EVA Project Off, Houston, TX 77058 USA. NR 26 TC 8 Z9 9 U1 0 U2 4 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD AUG PY 2001 VL 72 IS 8 BP 713 EP 719 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 459JQ UT WOS:000170247600003 PM 11506232 ER PT J AU Kaiser, MK AF Kaiser, MK TI What is internalized? SO BEHAVIORAL AND BRAIN SCIENCES LA English DT Editorial Material AB Hecht provides insights concerning the difficulty of empirically, testing Shepard's internalization hypothesis, but his argument for an externalization hypothesis suffers from similar sins. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kaiser, MK (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH ST, NEW YORK, NY 10011-4221 USA SN 0140-525X J9 BEHAV BRAIN SCI JI Behav. Brain Sci. PD AUG PY 2001 VL 24 IS 4 BP 680 EP + PG 15 WC Psychology, Biological; Behavioral Sciences; Neurosciences SC Psychology; Behavioral Sciences; Neurosciences & Neurology GA 609ZU UT WOS:000178936900033 ER PT J AU Seidler, RD Bloomberg, JJ Stelmach, GE AF Seidler, RD Bloomberg, JJ Stelmach, GE TI Patterns of transfer of adaptation among body segments SO BEHAVIOURAL BRAIN RESEARCH LA English DT Article; Proceedings Paper CT 9th Annual Meeting of the Society-for-the-Neural-Control-of-Movement CY APR 16-19, 1999 CL PRINCEVILLE, HAWAII SP Soc Neural Control Movement DE transfer of adaptation; body segments; top-down transfer ID VESTIBULO-OCULAR REFLEX; VISUAL PERCEPTIONS; HEAD STABILIZATION; LOCOMOTOR TASKS; EYE-MOVEMENTS; ARM MOVEMENTS; SPACE; PERFORMANCE; HYPOTHESIS; PREMOTOR AB Two experiments were conducted in order to determine the patterns of transfer of visuomotor adaptation between arm and head pointing. An altered gain of display of pointing movements was used to induce a conflict between visual and somatosensory representations. Two subject groups participated in Experiment wi: group 1 adapted shoulder pointing movements, and group 2 adapted wrist pointing movements to a 0.5 gain of display. Following the adaptation regimen, subjects performed a transfer test in which the shoulder group performed wrist movements and the wrist group performed shoulder movements. The results demonstrated that both groups displayed typical adaptation curves, initially undershooting the target followed by a return to baseline performance. Transfer tests revealed that both groups had high transfer of the acquired adaptation to the other joint. Experiment 2 followed a similar design except that group 1 adapted head pointing movements and group 2 adapted arm pointing movements. The arm adaptation had high transfer to head pointing while the head adaptation had very little transfer to arm pointing. These results imply that, while the arm segments may share a common target representation for goal-directed actions. individual but functionally dependent target representations may exist for the control of head and arm movements. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Arizona State Univ, ESPE Dept, Motor Control Lab, Tempe, AZ 85287 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Univ Minnesota, Dept Neurosci, Vet Affairs Med Ctr, Minneapolis, MN 55417 USA. Univ Minnesota, Brain Sci Ctr, Vet Affairs Med Ctr, Minneapolis, MN 55417 USA. RP Stelmach, GE (reprint author), Arizona State Univ, ESPE Dept, Motor Control Lab, POB 870404, Tempe, AZ 85287 USA. FU NIA NIH HHS [AG14676] NR 45 TC 19 Z9 19 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0166-4328 J9 BEHAV BRAIN RES JI Behav. Brain Res. PD AUG 1 PY 2001 VL 122 IS 2 BP 145 EP 157 DI 10.1016/S0166-4328(01)00183-8 PG 13 WC Behavioral Sciences; Neurosciences SC Behavioral Sciences; Neurosciences & Neurology GA 454VK UT WOS:000169992300004 PM 11334645 ER PT J AU Beck, MW Heck, KL Able, KW Childers, DL Eggleston, DB Gillanders, BM Halpern, B Hays, CG Hoshino, K Minello, TJ Orth, RJ Sheridan, PF Weinstein, MR AF Beck, MW Heck, KL Able, KW Childers, DL Eggleston, DB Gillanders, BM Halpern, B Hays, CG Hoshino, K Minello, TJ Orth, RJ Sheridan, PF Weinstein, MR TI The identification, conservation, and management of estuarine and marine nurseries for fish and invertebrates SO BIOSCIENCE LA English DT Article ID HABITAT STRUCTURE; SHALLOW SEAGRASS; SIZE-STRUCTURE; SALT-MARSHES; ABUNDANCE; RECRUITMENT; ASSEMBLAGES; ECOLOGY; ATLANTIC; BEDS C1 Univ Calif Santa Cruz, Ctr Ocean Hlth, Inst Marine Sci, Santa Cruz, CA 95060 USA. Dauphin Isl Sea Lab, Dauphin Isl, AL 36528 USA. Univ S Alabama, Dauphin Isl, AL 36528 USA. Rutgers State Univ, Marine Field Stn, Tuckerton, NJ USA. Rutgers State Univ, Inst Marine & Coastal Sci, Piscataway, NJ 08855 USA. Florida Int Univ, SE Environm Res Ctr, Dept Biol Sci, Miami, FL 33199 USA. N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Raleigh, NC 27695 USA. Univ Calif Santa Barbara, Santa Barbara, CA 93106 USA. Univ Calif Santa Cruz, Dept Ecol Evolut & Marine Biol, Santa Cruz, CA 95064 USA. Univ Calif Santa Cruz, Bren Sch Environm, Santa Cruz, CA 95064 USA. Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. Natl Marine Fisheries Serv, Fishery Ecol Branch, Galveston, TX USA. Natl Marine Fisheries Serv, SW Fisheries Sci Ctr Lab, Galveston, TX USA. Virginia Inst Marine Sci, Coll William & Mary, Sch Marine Sci, Gloucester Point, VA 23062 USA. New Jersey marine Sci Consortium, Ft Hancock, NJ 07732 USA. RP Beck, MW (reprint author), Univ Calif Santa Cruz, Ctr Ocean Hlth, Inst Marine Sci, Santa Cruz, CA 95060 USA. RI Langhamer, Olivia/J-3425-2012; Gillanders, Bronwyn/B-4218-2013 OI Gillanders, Bronwyn/0000-0002-7680-2240 NR 54 TC 1048 Z9 1076 U1 51 U2 379 PU AMER INST BIOLOGICAL SCI PI WASHINGTON PA 1444 EYE ST, NW, STE 200, WASHINGTON, DC 20005 USA SN 0006-3568 J9 BIOSCIENCE JI Bioscience PD AUG PY 2001 VL 51 IS 8 BP 633 EP 641 DI 10.1641/0006-3568(2001)051[0633:TICAMO]2.0.CO;2 PG 9 WC Biology SC Life Sciences & Biomedicine - Other Topics GA 467CT UT WOS:000170683500008 ER PT J AU Lachter, J AF Lachter, J TI Object similarity, not identity: Getting at Bedford's core arguments SO CAHIERS DE PSYCHOLOGIE COGNITIVE-CURRENT PSYCHOLOGY OF COGNITION LA English DT Article C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lachter, J (reprint author), NASA, Ames Res Ctr, MS 262-4, Moffett Field, CA 94035 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU ADRSC-ASSOC DIFFUSION RECHERCHES SCIENCES COGNITIVES PI MARSEILLE CEDEX 20 PA C N R S-C R N C, 31, CHEMIN JOSEPH ALGUIER, 13402 MARSEILLE CEDEX 20, FRANCE SN 0249-9185 J9 CAH PSYCHOL COGN JI Cah. Psychol. Cogn.-Curr. Psychol. Cogn. PD AUG PY 2001 VL 20 IS 3-4 BP 231 EP 236 PG 6 WC Psychology, Experimental SC Psychology GA 477ZF UT WOS:000171316400009 ER PT J AU Meador, MAB Johnston, JC Frimer, AA Gilinsky-Sharon, P Gottlieb, HE AF Meador, MAB Johnston, JC Frimer, AA Gilinsky-Sharon, P Gottlieb, HE TI 7-hydroxynadic acid: A new end cap for improved oxidation resistance in addition polyimides SO CHEMISTRY OF MATERIALS LA English DT Article ID DEGRADATION; POLYMERS; PRODUCTS; MODEL AB We consider possible replacements for the norbornenyl end cap in addition polyimides that should favor bridge degradation and lead to lower weight loss in the resin system. Our preliminary evaluation demonstrates that molding powder made with 7-hydroxynorbornene-2,3-dicarboxylic acid, 17, as the end cap can be fully imidized at 200 degreesC. By differential scanning calorimetry (DSC), onset of cross-linking occurs approximately 50 degreesC lower than that for the unsubstituted end cap. The hydroxy-bearing carbon on 17 is more easily oxidized to carbonyl on aging in the polymer than the parent end cap. Therefore, the new end cap more highly favors bridge degradation. However, processing studies, long-term weight loss, and careful evaluation of degradation mechanisms must be carried out to fully assess 17 as a more thermo-oxidatively stable replacement for the parent norbornenyl end cap. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Bar Ilan Univ, Dept Chem, Ethel & David Resnick Chair Act Oxygen Chem, IL-52900 Ramat Gan, Israel. RP Meador, MAB (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. OI Meador, Mary Ann/0000-0003-2513-7372 NR 37 TC 6 Z9 7 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0897-4756 J9 CHEM MATER JI Chem. Mat. PD AUG PY 2001 VL 13 IS 8 BP 2649 EP 2655 DI 10.1021/cm010134r PG 7 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 466AA UT WOS:000170621100031 ER PT J AU Bruyns, CD Senger, S AF Bruyns, CD Senger, S TI Interactive cutting of 3D surface meshes SO COMPUTERS & GRAPHICS-UK LA English DT Article; Proceedings Paper CT International Workshop on Intelligent Interactive Assistance and Mobile Multimedia Computing (IMC 2000) CY NOV 09-10, 2001 CL WARNEMUNDE, GERMANY DE graphics data structures and data types interaction techniques; medicine and science AB Engineers and scientists from many fields are using three-dimensional reconstruction for visualization and analysis of physical and abstract data. Beyond observing the recreated objects in artificial space, it is desirable to develop methods that allow one to interactively manipulate and alter the geometry in an intuitive and efficient manner. In the case of medical data, a baseline interactive task Would be to simulate cutting, removal and realignment of tissue. In order to provide for operational realism, the underlying mathematical calculations and topological changes need to be invisible to the user so that the user feels as though they are performing the task just its they Would on the real world counterpart of the reconstructed object. We have developed a method that allows the user to directly sketch the desired cut contour on a three-dimensional Surface in a manner that simulates dragging scissors through fabric. This new method can be employed interactively, allowing the user to perform the task in an intuitive, natural manner. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Ctr Bioinformat, Moffett Field, CA 94035 USA. Univ Wisconsin, Dept Comp Sci, La Crosse, WI 54601 USA. RP Bruyns, CD (reprint author), NASA, Ames Res Ctr, Ctr Bioinformat, Mail Stop 239-11, Moffett Field, CA 94035 USA. EM cbruyns@mail.arc.nasa.gov NR 12 TC 28 Z9 31 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0097-8493 J9 COMPUT GRAPH-UK JI Comput. Graph.-UK PD AUG PY 2001 VL 25 IS 4 BP 635 EP 642 DI 10.1016/S0097-8493(01)00092-9 PG 8 WC Computer Science, Software Engineering SC Computer Science GA 464JH UT WOS:000170529100011 ER PT J AU Turner, W Sterling, EJ Janetos, AC AF Turner, W Sterling, EJ Janetos, AC TI Special section: Contributions of remote sensing to biodiversity conservation: a NASA approach SO CONSERVATION BIOLOGY LA English DT Editorial Material C1 NASA, Off Earth Sci, Washington, DC 20546 USA. Amer Museum Nat Hist, Ctr Divers & Conservat, New York, NY 10024 USA. World Resources Inst, Washington, DC 20002 USA. RP Turner, W (reprint author), NASA, Off Earth Sci, Washington, DC 20546 USA. NR 4 TC 10 Z9 10 U1 2 U2 7 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 USA SN 0888-8892 J9 CONSERV BIOL JI Conserv. Biol. PD AUG PY 2001 VL 15 IS 4 BP 832 EP 834 PG 3 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 458EE UT WOS:000170179600010 ER PT J AU Steininger, MK Tucker, CJ Ersts, P Killeen, TJ Villegas, Z Hecht, SB AF Steininger, MK Tucker, CJ Ersts, P Killeen, TJ Villegas, Z Hecht, SB TI Clearance and fragmentation of tropical deciduous forest in the Tierras Bajas, Santa Cruz, Bolivia SO CONSERVATION BIOLOGY LA English DT Article ID SEASONALLY DRY FORESTS; AMAZONIAN FORESTS; EASTERN AMAZON; DEFORESTATION; BIOMASS; CARBON; FIRE; TRANSPIRATION; RADIATION; PASTURES AB The Tierras Bajas is an area of 20,000 km(2) of lowland deciduous forest in eastern Santa Cruz, Bolivia, that has undergone rapid change during the past two decades. As part of the largest remaining area of intact deciduous tropical forest in the world, it has been nominated a priority area for conservation by several environmental organization. We quantified the spatial and temporal patterns of deforestation in the area by digital processing of high-resolution satellite imagery from 1975 thru 1998. The estimated rate of deforestation was among the highest in the world for such a limited area, ranging from 160 km(2)/year in the early 1980s to almost 1200 km(2)/year in the late 1990s. Although most deforestation up to 1983 was in Bolivian peasant and Mennonite colonies, most deforestation after 1984 was in non-Mennonite industrial soybean farms. The level of fragmentation of uncut forest, caused by the spatial patterns of deforestation, also differed among these broad land-use types. Deforestation is planned and spontaneous peasant colonies was complex in shape, forming relatively large areas of edge-affected forest, whereas that in Mennonite and other industrial farms was in large, rectangular increments, creating relatively less edge. But the distribution of these farms and the practice of initially clearing around the peripheries of properties resulted in the isolation of large areas of forest. In 1998 four-fifths of the remaining forest were either within 1 km of a clearance edge or in isolated fragments of <50 km(2). Compared with deforested area, the areas of isolated and edge-affected forest were disproportionately large during the early stages of frontier colonization. These results imply that if the fragmentation effects of deforestation are to be minimized, conservation planning must occur at the earliest stages of frontier development. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Missouri Bot Garden, St Louis, MO 63110 USA. Museo Hist Nat Noel Kempff Mercado, Santa Cruz, Bolivia. Univ Calif Los Angeles, Sch Publ Policy, Dept Reg Planning, Los Angeles, CA 90095 USA. RP Steininger, MK (reprint author), Conservat Int, Ctr Appl Biodivers Sci, 1919 M St NW, Washington, DC 20037 USA. NR 63 TC 72 Z9 80 U1 2 U2 26 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 USA SN 0888-8892 J9 CONSERV BIOL JI Conserv. Biol. PD AUG PY 2001 VL 15 IS 4 BP 856 EP 866 DI 10.1046/j.1523-1739.2001.015004856.x PG 11 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 458EE UT WOS:000170179600013 ER PT J AU Saatchi, S Agosti, D Alger, K Delabie, J Musinsky, J AF Saatchi, S Agosti, D Alger, K Delabie, J Musinsky, J TI Examining fragmentation and loss of primary forest in the southern Bahian Atlantic forest of Brazil with radar imagery SO CONSERVATION BIOLOGY LA English DT Article ID RAIN-FOREST; CONSERVATION; AMAZON; DEFORESTATION; BIOMASS AB The Atlantic rainforest of southern Babia is one of the last remnants of the lowland forest of eastern Brazil that once covered The entire coastal area from Rio Grande do Norte to Rio Grande do Sul (lat 8 degrees 28 degreesS) and bas been deforested to a small fraction of its original cover (1-12%). All recent vegetation surveys have been based on optic il satellite data, which is hampered by cloud cover and by southern Bahia's intricate mix of forest patches with other tree crops, especially cocoa. We describe the application of radar remote-sensing data to distinguish forest patches from cocoa planted in the shade of natural-forest trees, Radar, unlike optical sensors, is not obstructed by cloud cover and can acquire information about-forest structure by penetrating into the vegetation canopy The vegetation map generated from radar data clearly separates forest patches based on the degree of structural disturbance such as the density of shaded trees, the openness of the canopy, and the density of the monodominant Erythyrina shaded trees. The structural classification based on the radar data, and shown on the map, can help researchers assess the degree of fragmentation of the original Atlantic coastal forest and delineate areas of less disturbance with higher potential for conservation of biodiversity. This information can then be applied to conservation planning, especially the design and monitoring of nature reserves and the modeling of biological corridors. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Amer Museum Nat Hist, New York, NY 10024 USA. Conservat Int, Washington, DC USA. CEPLEC, Itabuna, Brazil. RP Saatchi, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 45 TC 48 Z9 56 U1 4 U2 21 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 USA SN 0888-8892 J9 CONSERV BIOL JI Conserv. Biol. PD AUG PY 2001 VL 15 IS 4 BP 867 EP 875 DI 10.1046/j.1523-1739.2001.015004867.x PG 9 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 458EE UT WOS:000170179600014 ER PT J AU Robinson, JA Lulla, KP Kashiwagi, M Suzuki, M Nellis, MD Bussing, CE Long, WJL McKenzie, LJ AF Robinson, JA Lulla, KP Kashiwagi, M Suzuki, M Nellis, MD Bussing, CE Long, WJL McKenzie, LJ TI Conservation applications of astronaut photographs of Earth: Tidal-flat loss (Japan), elephant effects on vegetation (Botswana), and seagrass and mangrove monitoring (Australia) SO CONSERVATION BIOLOGY LA English DT Article ID NORTHERN BOTSWANA; SPACE; MEADOWS; IMAGERY AB National Aeronautics and Space Administration (NASA) photographs taken by astronauts from low Earth orbit can provide information relevant to conservation biology. This data source is now more accessible because of improvements in digitizing technology. Internet file transfer, and availability of image processing software. We present three examples of conservation-related projects that benefited from the use of astronaut photographs. First, NASA scientist requested that astronauts photograph the area of the controversial Isahaya Bay reclamation project in Japan. Japanese researches used photograph from before and after the reclamation as a tool for communication with the public about the effects of tidal-flat loss. The newly acquired images and the availability of high-resolution digital images from NASA archives provided timely public information on the observed changes. Second, we digitally classified and analyzed a Space Shuttle photograph of Chobe National Park in Botswana to identify the locations of woodlands affected by elephants. Field validation later confirmed that area identified on the image showed evidence of elephant damage. Third, we used a summary map from intensive field surveys of seagrasses in Shoalwater Bay, Australia, as reference data for a supervised classification of a digitized photograph taken from orbit. The classification distinguished seagrasses, sediments and mangroves with accuracy approximating that in studies using other satellite remote-sensing data. Astronaut photographs are in the public domain, and the database of nearly 400,000 photographs from the late 1960s to the present is available as a single searchable location on the Internet (http://eol.jsc.nasa.gov/sseop). These photographs can be used by conservation biologists as a source of general information about the landscaped and for quantitative mapping. C1 NASA, Lyndon B Johnson Space Ctr, Earth Sci & Image Anal, Houston, TX 77058 USA. Japan Wetlands Act Network, Tokyo Off, Hino, Tokyo 191, Japan. W Virginia Univ, Dept Geol & Geog, Morgantown, WV 26505 USA. W Virginia Univ, Eberly Coll Arts & Sci, Morgantown, WV 26505 USA. Kansas State Univ, Dept Geog, Manhattan, KS 66506 USA. Queensland Dept Primary Ind, No Fisheries Ctr, Cairns, Qld 4870, Australia. RP Robinson, JA (reprint author), NASA, Lyndon B Johnson Space Ctr, Earth Sci & Image Anal, 2400 NASA Rd 1,C23, Houston, TX 77058 USA. OI Robinson, Julie/0000-0002-6832-6459; McKenzie, Leonard/0000-0003-1294-3770 NR 37 TC 5 Z9 6 U1 0 U2 6 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 USA SN 0888-8892 J9 CONSERV BIOL JI Conserv. Biol. PD AUG PY 2001 VL 15 IS 4 BP 876 EP 884 DI 10.1046/j.1523-1739.2001.015004876.x PG 9 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 458EE UT WOS:000170179600015 ER PT J AU Carey, C Heyer, WR Wilkinson, J Alford, RA Arntzen, JW Halliday, T Hungerford, L Lips, KR Middleton, EM Orchard, SA Rand, AS AF Carey, C Heyer, WR Wilkinson, J Alford, RA Arntzen, JW Halliday, T Hungerford, L Lips, KR Middleton, EM Orchard, SA Rand, AS TI Amphibian declines and environmental change: Use of remote-sensing data to identify environmental correlates SO CONSERVATION BIOLOGY LA English DT Review ID RAIN-FOREST FROGS; PERSISTENT ORGANOCHLORINE COMPOUNDS; UV-B RADIATION; ULTRAVIOLET-RADIATION; POPULATION DECLINES; CLIMATE-CHANGE; THERMAL ACCLIMATION; GLOBAL DISTRIBUTION; MASS MORTALITY; BOREAL TOADS AB Populations of many amphibian species are declining worldwide, and a few species appear to have become extinct, In an attempt to evaluate the potential usefulness of remote-sensing techniques as a tool for identifying the causes of These declines, we compiled a database that contains descriptions of 120 localities, both at which declines have been documented and at which no declines are yet known. Tbe number of species involved, dates and degree of declines, habitat characteristics, and other factors are provided for each locality. Four relatively undisturbed areas in northeastern Australia, Costa Rica-Panama, central Colorado, and Puerto Rico were chosen for examination of environmental correlates coincident with mass mortalities at these localities. We used data predicted by models or collected by satellites, airplanes, or direct sampling on the ground to evaluate variations over time In temperature, precipitation, wind direction, UV-B radiation, and concentrations of certain contaminants at these sites. We asked whether unusual changes in these environmental variables occurred either just in advance of or concurrent with dates of amphibian mass mortalities, The variation in certain environmental variables documented by others (Alexander & Eischeid 2001; Middleton et cit. 2001; Stallard 2001 [all this issue]) appears unlikely to have directly caused amphibian deaths. But correlations between these environmental changes and the occurrence of amphibian die-offs, invite further investigation into synergistic interactions among environmental variables and possible indirect causal relationships. C1 Univ Colorado, Dept Environm Populat & Organism Biol, Boulder, CO 80309 USA. Smithsonian Inst, Natl Museum Nat Hist, Div Amphibians & Reptiles, MRC 162, Washington, DC 20560 USA. Open Univ, Dept Biol Sci, Milton Keynes MK7 6AA, Bucks, England. James Cook Univ N Queensland, Sch Trop Biol, Townsville, Qld 4811, Australia. James Cook Univ N Queensland, Cooperat Res Ctr Trop Rainforest Ecol & Managemen, Townsville, Qld 4811, Australia. Naturalis Natl Museum Nat Hist, Collect & Res, NL-2300 RA Leiden, Netherlands. So Illinois Univ, Dept Zool, Carbondale, IL 62901 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. World Wildlife Fund Nature Australia, Sydney, NSW, Australia. Smithsonian Trop Res Inst, Balboa, Panama. RP Carey, C (reprint author), Univ Colorado, Dept Environm Populat & Organism Biol, Boulder, CO 80309 USA. EM careyc@spot.colorado.edu RI Alford, Ross/H-1577-2011; Arntzen, Jan/E-7108-2016; OI Alford, Ross/0000-0002-3010-6768; Arntzen, Jan/0000-0003-3229-5993; Lips, Karen/0000-0002-2719-1551 NR 103 TC 50 Z9 56 U1 2 U2 27 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0888-8892 EI 1523-1739 J9 CONSERV BIOL JI Conserv. Biol. PD AUG PY 2001 VL 15 IS 4 BP 903 EP 913 DI 10.1046/j.1523-1739.2001.015004903.x PG 11 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 458EE UT WOS:000170179600018 ER PT J AU Middleton, EM Herman, JR Celarier, EA Wilkinson, JW Carey, C Rusin, RJ AF Middleton, EM Herman, JR Celarier, EA Wilkinson, JW Carey, C Rusin, RJ TI Evaluating ultraviolet radiation exposure with satellite data at sites of amphibian declines in Central and South America SO CONSERVATION BIOLOGY LA English DT Article ID UV-B RADIATION; RAIN-FOREST FROGS; POPULATION DECLINES; NATURAL FLUCTUATIONS; TROPICAL MOUNTAIN; OZONE DEPLETION; MASS MORTALITY; EARTHS SURFACE; CLIMATE-CHANGE; HUMAN IMPACTS AB Many amphibian species have experienced substantial population declines or have disappeared altogether during the last several decades at a number of amphibian survey sites in Central and South America. Our study addresses the use of trends in solar UV-B radiation exposure (280-320 mn) tit these sites over the last two decades, derived from the Total Ozone Mapping Spectrometer satellite data. It is intended to demonstrate a role for satellite observations In determining whether UVB radiation is a contributing factor in amphibian declines. We used these data to calculate the daily erythemal (sunburning) UV-B or UV-B-ery, exposure at the latitude, longitude, and elevation of each of 20 survey sites. The annually average UV-B-ery dose, as well as the maximum values, have been increasing in both Central and South America, with higher levels reached at the Central American sites. The annually averaged UV-B-ery exposure increased significantly from 1979-1998 at all 11 Central American site; we examined (r(2) = 0.60-0.79; p less than or equal to0.015), with smaller but significant increases at five of the nine South American sites (r(2) = 0.24-0.42- p less than or equal to0.05). The number of days having the highest UV-B exposure (greater than or equal to6.75 kJ/m(2)/day) increased in both regions from <40 days per year to approximately 58 days per year in 1998 (r(2) = 0.24-0.42- p 0.001). In Central America, the contribution of these very, high UV-B-ery exposure levels to the annual UV-B-ery total increased from approximately 5 to approximately 15% over the 19-year period, but actual daily exposures for each species are unknown, A UV-B ratio, the highest monthly UVB exposure relative to the annual average for the highest UV-B category (greater than or equal to6.75 kJ/m(2)), increased in both regions over this time period (r(2) = 0.73; p less than or equal to0.001). This UV index was consistently higher for Central America, where species declines have been the most severe. These results should justify further research into whether UV-B-ery radiation plays a role in amphibian population declines and extinctions. We discuss synergy among UV-B radiation and other factors, especially those associated with alterations of water chemistry (e.g., acidification) in aqueous habitats. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Software Corp Amer, Beltsville, MD 20705 USA. Open Univ, Dept Biol Sci, Milton Keynes MK7 6AA, Bucks, England. Univ Colorado, Dept Environm Populat & Organism Biol, Boulder, CO 80309 USA. Bowie State Univ, Dept Nat Sci, Bowie, MD 20715 USA. RP Middleton, EM (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Code 923, Greenbelt, MD 20771 USA. OI Herman, Jay/0000-0002-9146-1632 NR 77 TC 53 Z9 57 U1 7 U2 16 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 USA SN 0888-8892 J9 CONSERV BIOL JI Conserv. Biol. PD AUG PY 2001 VL 15 IS 4 BP 914 EP 929 DI 10.1046/j.1523-1739.2001.015004914.x PG 16 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 458EE UT WOS:000170179600019 ER PT J AU Jacobson, NS Opila, EJ Lee, KN AF Jacobson, NS Opila, EJ Lee, KN TI Oxidation and corrosion of ceramics and ceramic matrix composites SO CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE LA English DT Review ID SIO2 SCALE VOLATILITY; HIGH-TEMPERATURE OXIDATION; SILICON-CARBIDE; COMBUSTION CONDITIONS; MULLITE COATINGS; BORON-NITRIDE; RECESSION; KINETICS; MECHANISMS; SI3N4 AB Ceramics and ceramic matrix composites are candidates for numerous applications in high temperature environments with corrosive gases and deposits. High temperature oxidation and corrosion issues must be considered for these materials. The most important oxidation and corrosion studies have recently focused on four major areas. These are: (I) oxidation of precursor-based ceramics, (II) studies of the interphase material in ceramic matrix composites, (III) water vapor interactions with ceramics, particularly in combustion environments, (IV) development of refractory oxide coatings for silicon-based ceramics. This paper explores the most current work in each of these areas. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Cleveland State Univ, NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Jacobson, NS (reprint author), Cleveland State Univ, NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. EM nathan.s.jacobson@grc.nasa.gov; opila@grc.nasa.gov; kang.n.lee@grc.nasa.gov RI Jacobson, Nathan/A-9411-2009 NR 46 TC 54 Z9 54 U1 3 U2 50 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1359-0286 J9 CURR OPIN SOLID ST M JI Curr. Opin. Solid State Mat. Sci. PD AUG PY 2001 VL 5 IS 4 BP 301 EP 309 DI 10.1016/S1359-0286(01)00009-2 PG 9 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA 471EF UT WOS:000170914100008 ER PT J AU James-Pirri, MJ Raposa, KB Catena, JG AF James-Pirri, MJ Raposa, KB Catena, JG TI Diet composition of mummichogs, Fundulus heteroclitus, from restoring and unrestricted regions of a New England (USA) salt marsh SO ESTUARINE COASTAL AND SHELF SCIENCE LA English DT Article DE gut contents; Fundulus heteroclitus; tidal restoration; salt marsh ID MELAMPUS-BIDENTATUS SAY; TIDAL MARSH; RESTORATION; PREDATION; ABUNDANCE; GROWTH; HABITS; SIZE; POPULATIONS; IMPOUNDMENT AB Diet composition of mummichogs, Fundulus heteroclitus, from three marsh habitats (creeks, pools, and marsh surface) within tidally restored and an adjacent unrestricted (reference) region of Sachuest Point salt marsh (Middletown, RI, U.S.A.) was examined. Major diet components were detritus, copepods, diatoms, insects (larvae and adults), ostracods, and chironomids. Total length, wet weight, and gut fullness of mummichogs were equivalent within habitats between the restoring and unrestricted marshes. Diet composition and percent abundance of diet items were also similar within habitats between the unrestricted and restoring marshes. However, differences in diet patterns were observed among habitats (creeks, pools, and marsh surface) within each marsh. Fish collected from creeks had fuller guts than those sampled from the marsh surface for both the restoring and unrestricted marsh. Diet composition also differed among marsh habitats, but only within the restoring marsh. In the restoring marsh, fish sampled from the creeks consumed primarily detritus, diatoms, and ostracods, whereas fish from the pools consumed mainly detritus, copepods, chironomids, and insects. Differences in diet composition among habitats were most likely a reflection of prey availability. This study provides evidence that tidally restored marshes can provide similar food resources as unrestricted marshes, in terms of consumption patterns of dominant marsh consumers, within the first year after restoration, before major shifts in dominant vegetation (i.e. from Phragmites australis to Spartina spp.) occur. (C) 2001 Academic Press. C1 Univ Rhode Isl, Grad Sch Oceanog, Narragansett, RI 02882 USA. NOAA, Natl Marine Fisheries Serv, Restorat Ctr, Gloucester, MA 01930 USA. RP James-Pirri, MJ (reprint author), Univ Rhode Isl, Grad Sch Oceanog, Box 8,S Ferry Rd, Narragansett, RI 02882 USA. NR 42 TC 30 Z9 31 U1 1 U2 16 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0272-7714 J9 ESTUAR COAST SHELF S JI Estuar. Coast. Shelf Sci. PD AUG PY 2001 VL 53 IS 2 BP 205 EP 213 DI 10.1006/ecss.2001.0807 PG 9 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA 474UP UT WOS:000171125500008 ER PT J AU Esteban, EP Kazanas, D AF Esteban, EP Kazanas, D TI Gravitational potentials of triaxial ellipsoids in Weyl gravity SO GENERAL RELATIVITY AND GRAVITATION LA English DT Article DE Weyl gravity; ellipsoids ID GALACTIC ROTATION CURVES; EXACT VACUUM SOLUTION; PROLATE SPHEROIDS; STABILITY; DISKS AB We present analytic expressions for the gravitational potentials associated with triaxial ellipsoids, spheroids, spheres and disks in Weyl gravity. The gravitational potentials of these configurations in Newtonian gravity, i.e. the potentials derived by integration of the Poisson equation Green's function 1/\r- r'\ over the volume of the configuration, are well known in the literature. Herein we present the results of the integration of \r-r'\, the Green's function associated with the fourth order Laplacian del (4) of Weyl gravity, over the volume of the configuration to obtain the resulting gravitational potentials within this specific theory. As an application of our calculations, we solve analytically Euler's equations pertaining to incompressible rotating fluids to show that, as in the case of Newtonian gravity, homogeneous prolate configurations are not allowed within Weyl gravity either. C1 Univ Puerto Rico, Dept Phys, Humacao, PR 00791 USA. NASA, Goddard Space Flight Ctr, Lab High Energy & Astrophys, Washington, DC 20546 USA. RP Esteban, EP (reprint author), Univ Puerto Rico, Dept Phys, Humacao, PR 00791 USA. NR 16 TC 0 Z9 0 U1 0 U2 1 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0001-7701 J9 GEN RELAT GRAVIT JI Gen. Relativ. Gravit. PD AUG PY 2001 VL 33 IS 8 BP 1281 EP 1303 DI 10.1023/A:1012001407185 PG 23 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 489QR UT WOS:000172003400002 ER PT J AU Berberian, M Jackson, JA Fielding, E Parsons, BE Priestley, K Qorashi, M Talebian, M Walker, R Wright, TJ Baker, C AF Berberian, M Jackson, JA Fielding, E Parsons, BE Priestley, K Qorashi, M Talebian, M Walker, R Wright, TJ Baker, C TI The 1998 March 14 Fandoqa earthquake (M-w 6.6) in Kerman province, southeast Iran: re-rupture of the 1981 Sirch earthquake fault, triggering of slip on adjacent thrusts and the active tectonics of the Gowk fault zone SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE continental tectonics; earthquakes; Iran; SAR interferometry; seismology ID SISTAN SUTURE ZONE; PLATE CONVERGENCE; RADAR INTERFEROMETRY; EASTERN IRAN; DEFORMATION; SURFACE; TURKEY; NORTH; FIELD; BELT AB The 1998 March 14 Fandoqa earthquake (M-s 6.6) was the penultimate in a series of five substantial earthquakes on the Gowk fault system of southeast Iran since 1981, all of which were associated with co-seismic surface ruptures. We use observations of surface faulting, analysis of P and SH body waves, SAR interferometry and geomorphology to investigate the ruptures in these earthquakes and how they are related both to each other and to the regional active tectonics. The 1998 Fandoqa earthquake produced 23 km of surface faulting with up to 3 m right-lateral strike-slip and 1 m vertical offsets. SAR interferometry and seismic waveforms show that the main rupture plane dipped west at similar to 50 degrees and had a normal component, although the surface ruptures were more complicated, being downthrown to both the east and the west on steep faults in nearsurface sediments. In addition, SAR interferometry shows that a nearby thrust with a similar strike but dipping at similar to6 degreesW moved about 8 cm in a time interval and in a position that makes it likely that its slip was triggered by the Fandoqa earthquake. The 1998 surface ruptures in the Gowk valley followed part of a much longer (similar to 80 km) set of co-seismic ruptures with smaller offsets that were observed after larger earthquakes in 1981 (M-w 6.6 and 7.1). The main ruptures in these 1981 earthquakes probably occurred on different, deeper parts of the same fault system, producing only minor reactivation of the shallower faults at the surface. Although the 1981-1998 earthquake sequence apparently ruptured parts of the same fault system repeatedly, these earthquakes had very different rupture characteristics: an important lesson for the interpretation of both palaeoseismological trenching investigations and historical accounts of earthquakes. The regional kinematics, which involve oblique right-lateral and convergent motion, are evidently achieved by a complex configuration of faults with normal, reverse and strike-slip components. Some of the complexity at the surface may be related to a ramp-and-flat fault geometry at depth, but could also be related to the large topographic contrast of similar to 2000 m across the fault system, which separates the high Kerman plateau from the low Dasht-e-Lut desert. Details of the fault geometry at depth remain speculative, but it must be unstable and evolve with time. It may be this requirement that causes the principal features of geological 'flower structures' to develop, such as series of subparallel faults which accommodate dip-slip components of motion. C1 Najarian Associates, Eatontown, NJ 07724 USA. Univ Cambridge, Dept Earth Sci, Bullard Labs, Cambridge CB3 OEZ, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Oxford, Dept Earth Sci, Oxford OX1 3PR, England. Geol Survey Iran, Tehran, Iran. RP Berberian, M (reprint author), Najarian Associates, Suite E,1 Ind Way W, Eatontown, NJ 07724 USA. RI Walker, Richard/D-9908-2011; Wright, Tim/A-5892-2011; Parsons, Barry/K-4716-2012; Fielding, Eric/A-1288-2007 OI Berberian, Manuel/0000-0003-2379-5064; Wright, Tim/0000-0001-8338-5935; Fielding, Eric/0000-0002-6648-8067 NR 31 TC 84 Z9 84 U1 0 U2 4 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 2001 VL 146 IS 2 BP 371 EP 398 DI 10.1046/j.1365-246x.2001.01459.x PG 28 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 462NK UT WOS:000170426000007 ER PT J AU Popp, PJ Northway, MJ Holecek, JC Gao, RS Fahey, DW Elkins, JW Hurst, DF Romashkin, PA Toon, GC Sen, B Schauffler, SM Salawitch, RJ Webster, CR Herman, RL Jost, H Bui, TP Newman, PA Lait, LR AF Popp, PJ Northway, MJ Holecek, JC Gao, RS Fahey, DW Elkins, JW Hurst, DF Romashkin, PA Toon, GC Sen, B Schauffler, SM Salawitch, RJ Webster, CR Herman, RL Jost, H Bui, TP Newman, PA Lait, LR TI Severe and extensive denitrification in the 1999-2000 Arctic winter stratosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TOTAL REACTIVE NITROGEN; POLAR VORTEX; OZONE LOSS; AEROSOL; RECOVERY; CLOUD; OXIDE; HNO3; H2O AB Observations in the 1999-2000 Arctic winter stratosphere show the most severe and extensive denitrification ever observed in the northern hemisphere. Denitrification was inferred from in situ measurements conducted during high-altitude aircraft flights between January and March 2000. Average removal of more than 60% of the reactive nitrogen reservoir (NOy) was observed in air masses throughout the core of the Arctic vortex. Denitrification was observed at altitudes between 16 and 21 km, with the most severe denitrification observed at 20 to 21 km. Nitrified air masses were also observed, primarily at lower altitudes. These results show that denitrification in the Arctic lower stratosphere can approach the severity and extent of that previously observed only in the Antarctic. C1 NOAA, Aeron Lab, Boulder, CO 80305 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80305 USA. Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Popp, PJ (reprint author), NOAA, Aeron Lab, Boulder, CO 80305 USA. RI Salawitch, Ross/B-4605-2009; Newman, Paul/D-6208-2012; Herman, Robert/H-9389-2012; Gao, Ru-Shan/H-7455-2013; Hurst, Dale/D-1554-2016; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Newman, Paul/0000-0003-1139-2508; Herman, Robert/0000-0001-7063-6424; Hurst, Dale/0000-0002-6315-2322; Fahey, David/0000-0003-1720-0634 NR 25 TC 62 Z9 61 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 2001 VL 28 IS 15 BP 2875 EP 2878 DI 10.1029/2001GL013132 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 457VK UT WOS:000170157400001 ER PT J AU Gao, RS Richard, EC Popp, PJ Toon, GC Hurst, DF Newman, PA Holecek, JC Northway, MJ Fahey, DW Danilin, MY Sen, B Aikin, K Romashkin, PA Elkins, JW Webster, CR Schauffler, SM Greenblatt, JB McElroy, CT Lait, LR Bui, TP Baumgardner, D AF Gao, RS Richard, EC Popp, PJ Toon, GC Hurst, DF Newman, PA Holecek, JC Northway, MJ Fahey, DW Danilin, MY Sen, B Aikin, K Romashkin, PA Elkins, JW Webster, CR Schauffler, SM Greenblatt, JB McElroy, CT Lait, LR Bui, TP Baumgardner, D TI Observational evidence for the role of denitrification in Arctic stratospheric ozone loss SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID POLAR VORTEX; WINTER; RECOVERY; DEPLETION; AEROSOL AB Severe and extensive denitrification, chlorine activation, and photochemical ozone loss were observed throughout the lower stratosphere in the 1999-2000 Arctic vortex. A large number of air parcels sampled between late February and mid-March, 2000, were photochemically intercomparable for chemical O-3 loss rates. In these air parcels, the temporal evolution of the correlations Of O-3 with the NOy remaining after denitrification provides strong evidence for the role of NOy in moderating O-3 destruction. In 71%-denitrified air parcels, a chemical O-3 destruction rate of 63 ppbv/day was calculated, while in 43%-denitrified air parcels the destruction rate was only 43 ppbv/day. These observational results show that representative denitrification models will be required for accurate prediction of future Arctic O-3 changes. C1 NOAA, Aeron Lab, Boulder, CO 80305 USA. Univ Colorado, CIRES, Boulder, CO 80303 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80305 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Atmospher & Environm Res Inc, Lexington, MA 02421 USA. Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80307 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Atmospher Environm Serv, Downsview, ON, Canada. Univ Nacl Autonoma Mexico, Ctr Ciencias Atmosfera, Mexico City 04510, DF, Mexico. RP Gao, RS (reprint author), NOAA, Aeron Lab, Boulder, CO 80305 USA. RI Fahey, David/G-4499-2013; Newman, Paul/D-6208-2012; Gao, Ru-Shan/H-7455-2013; Aikin, Kenneth/I-1973-2013; Hurst, Dale/D-1554-2016 OI Fahey, David/0000-0003-1720-0634; Newman, Paul/0000-0003-1139-2508; Hurst, Dale/0000-0002-6315-2322 NR 19 TC 31 Z9 31 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 1 PY 2001 VL 28 IS 15 BP 2879 EP 2882 DI 10.1029/2001GL013173 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 457VK UT WOS:000170157400002 ER PT J AU Jackman, CH McPeters, RD Labow, GJ Fleming, EL Praderas, CJ Russell, JM AF Jackman, CH McPeters, RD Labow, GJ Fleming, EL Praderas, CJ Russell, JM TI Northern Hemisphere atmospheric effects due to the July 2000 solar proton event SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EARTHS MIDDLE ATMOSPHERE; 2-DIMENSIONAL MODEL; ODD NITROGEN; NITRIC-OXIDE; OZONE; STRATOSPHERE; CHEMISTRY AB The third largest solar proton event in the past thirty years took place during July 14-16, 2000, and had a significant impact on the earth's atmosphere. These energetic protons produced both HOx (H, OH, HO2) and NOx (N, NO, NO2) constituents in the mesosphere and upper stratosphere at polar latitudes (> 60 degrees geomagnetic) of both hemispheres. The temporal evolution of increases in NO and NO2 during the event at northern polar latitudes were measured by the UARS HALOE instrument. Increases in mesospheric NO, of over 50 ppbv were found in the HALOE measurements. Measurements from the UARS HALOE and NOAA 14 SBUV/2 instruments indicate short-term (similar to day) middle mesospheric ozone decreases of over 70% caused by short-lived HOx during the event with a longer-term (several days) upper stratospheric ozone depletion of up to 9% caused by longer-lived NOx. We believe this is the first time that the three constituents NO, NO2, and ozone were all measured simultaneously during a proton event. The observations constitute a dramatic confirmation of the impact of a large particle event in the control of ozone in the polar middle atmosphere and offer the opportunity to test theories of constituent changes driven by particle precipitation. C1 NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Greenbelt, MD 20771 USA. Emergent Informat Technol Inc, Arlington, VA 22201 USA. Hampton Univ, Ctr Atmospher Sci, Hampton, VA 23668 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Jackman, CH (reprint author), NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Code 916, Greenbelt, MD 20771 USA. RI Jackman, Charles/D-4699-2012; McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 18 TC 107 Z9 107 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 2001 VL 28 IS 15 BP 2883 EP 2886 DI 10.1029/2001GL013221 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 457VK UT WOS:000170157400003 ER PT J AU Steele, M Ermold, W Hakkinen, S Holland, D Holloway, G Karcher, M Kauker, F Maslowski, W Steiner, N AF Steele, M Ermold, W Hakkinen, S Holland, D Holloway, G Karcher, M Kauker, F Maslowski, W Steiner, N TI Adrift in the Beaufort Gyre: A model intercomparison SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ARCTIC-OCEAN; SEA-ICE; DYNAMICS; HALOCLINE AB Output from six regional sea ice-ocean climate model simulations of the arctic seas is compared to investigate the models' ability to accurately reproduce the observed late winter mean sea surface salinity. The results indicate general agreement within the Nordic seas, strong differences on the arctic continental shelves, and the presence of a climate drift that leads to a high salinity bias in most models within the Beaufort Gyre. The latter is highly sensitive to the wind forcing and to the simulation of freshwater sources on the shelves and elsewhere. C1 Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NYU, New York, NY USA. Inst Ocean Sci, Sidney, BC, Canada. AWI, Bremerhaven, Germany. USN, Postgrad Sch, Monterey, CA USA. RP Steele, M (reprint author), Univ Washington, Appl Phys Lab, 1013 NE 40th St, Seattle, WA 98105 USA. EM mas@apl.washington.edu RI Hakkinen, Sirpa/E-1461-2012 NR 20 TC 33 Z9 33 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 2001 VL 28 IS 15 BP 2935 EP 2938 DI 10.1029/2001GL012845 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 457VK UT WOS:000170157400016 ER EF