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  • 1
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    Hematological measurements in rats flown on Spacelab shuttle, SL-3 (1987)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Previous studies have shown that a decrease in red cell mass occurs in astronauts, and some studies indicate a leukocytosis occurs. A life science module housing young and mature rats was flown on shuttle mission Spacelab 3 (SL-3), and the results of hematology studies of flight and control rats are presented. Statistically significant increases in the hematocrit, red blood cell counts, and hemoglobin determinations, together with a mild neutrophilia and lymphopenia, were found in flight animals. No significant changes were found in bone marrow and spleen cell differentials or erythropoietin determinations. Clonal assays demonstrated an increased erythroid colony formation of flight animal bone marrow cells at erythropoietin doses of 0.02 and 1.0 U/ml but not 0.20 U/ml. These results agree with some but vary from other previously published studies. Erythropoietin assays and clonal studies were performed for the first time.
    Keywords: Life Sciences (General)
    Type: The American journal of physiology (ISSN 0002-9513); Volume 252; 2 Pt 2; R216-21
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  • 2
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    Tensile creep and creep-recovery behavior of a SiC-fiber-Si3N4-matrix composite (1993)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The tensile creep and creep-recovery behavior of a hot-pressed unidirectional SiC-fiber/Si3N4-matrix composite was investigated at 1200 C in air, in order to determine how various sustained and cyclic creep loading histories would influence the creep rate, accumulated creep strain, and the amount of strain recovered upon specimen unloading. The data accumulated indicate that the fundamental damage mode for sustained tensile creep at stresses of 200 and 250 MPa was periodic fiber fracture and that the creep life and the failure mode at 250 MPa were strongly influenced by the rate at which the initial creep stress was applied. Cyclic loading significantly lowered the duration of primary creep and the overall creep-strain accumulation. The implications of the results for microstructural and component design are discussed.
    Keywords: COMPOSITE MATERIALS
    Type: American Ceramic Society, Journal (ISSN 0002-7820); 76; 5; p. 1281-1293.
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  • 3
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    Infrared, microwave, and spaceborne radar simulations of a deep convective system using a 3-D cloud ensemble method (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A 3D cloud model is used to simulate the storm structure, and the results are linked to microwave and infrared radiative transfer models for simulation of aircraft observations. Spaceborne radar data are also simulated along the aircraft flight track. The cloud and radiative model simulations are studied and compared with aircraft observations. The initial results indicate that the 3D cloud model is capable of simulating the major features of observed storm systems when given a representative atmospheric sounding to initialize the convective systems. The simulations of infrared and microwave radiances provide reasonably good comparisons with the observations.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: In: Conference on Satellite Meteorology and Oceanography, 6th, Atlanta, GA, Jan. 5-10, 1992, Preprints (A93-36051 14-47); p. 226-229.
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  • 4
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    An approach to estimate the areal rain-rate distribution from spaceborne radar by the use of multiple thresholds (1993)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Estimates of rain rate derived from a spaceborne weather radar will be most reliable over an intermediate range of values. In forming an area average of the rain rate, an alternative to the averaging of the high-resolution estimates, irrespective of their individual accuracies, is a multiple threshold approach. The method is based on the fact that the fractional area above a particular rain-rate threshold R(j) is related to the cumulative distribution of rain rates evaluated at R(j). Varying the threshold over the effective dynamic range of the radar yields the cumulative distribution function over this range. To obtain the distribution at all rain rates, a lognormal or gamma test function is selected such that the mean-square error between the test function and the measured values is minimized. Once the unknown parameters are determined, the first-order statistics of the areawide rain-rate distribution can be found. Tests of the method with data from the SPANDAR radar provide comparisons between it and the single threshold and the direct averaging approaches.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 32; 2; p. 386-398.
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  • 5
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    Numerical modeling of crystal growth on a centrifuge for unstable natural convection configurations (1993)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The fluid mechanics associated with crystal growth processes on centrifuges is modeled using 2D and 3D models. Two-dimensional calculations show that flow bifurcations exist in such crystal growth configurations where the ampoule is oriented in the same direction as the resultant gravity vector and a temperature gradient is imposed on the melt. A scaling analysis is formulated to predict the flow transition point from the natural convection dominated regime to the Coriolis force dominated regime. Results of 3D calculations are presented for two thermal configurations of the crystal growth cell: top heated and bottom heated with respect to the centrifugal acceleration. In the top heated configuration, a substantial reduction in the convection intensity within the melt can be attained by centrifuge operations, and close to steady diffusion-limited thermal conditions can be achieved over a narrow range of the imposed microgravity level. In the bottom heated configuration the Coriolis force has a stabilizing effect on fluid motion by delaying the onset of unsteady convection.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Crystal Growth (ISSN 0022-0248); p. 655-674.
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  • 6
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    Global configuration of a magnetic cloud (1990)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A magnetic cloud associated with a 2N flare on January 1, 1978 was observed by IMP-8, Helios A, Helios B, and Voyager 2. The variation of the magnetic field observed at each spacecraft is represented to good approximation by Lundquist's solution for a cylindrically symmetric force-free magnetic field with constant alpha. A least-squares fit of Lundquist's solution to the data from each spacecraft gives the local orientation of the axis of the magnetic cloud. The times of the estimated boundaries of the magnetic cloud at each spacecraft, together with the speeds of the boundaries and the spacecraft position, give the positions of the boundaries at a given time. From these results the magnetic cloud is determined to resemble a flux rope whose minor radius is approximately 0.15 AU at 1 AU, and whose radius of curvature at 1 AU is approximately 1/3 AU.
    Keywords: SOLAR PHYSICS
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  • 7
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    Siderophile elements and the earth's formation (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Two comments on a work by Murthy (1991) concerning the abundances of siderophile elements in the earth's mantle are presented. In the first comment it is asserted that the basis of Murthy's extrapolation is the assumption that the Gibbs free energy change for the partitioning reaction is independent of temperature, and as this is generally not a valid assumption thermodynamically, and as this is contradicted by most experimental data, the issue of mantle siderophile elements remains unresolved. In the second comment it is asserted that the extrapolation method used by Murthy does not appear to be valid thermodynamically, and that an extrapolation based on generally accepted thermodynamic assumptions yields different results. In a reply, Murthy takes issue with the comments.
    Keywords: GEOPHYSICS
    Type: Science (ISSN 0036-8075); 257; 5074,; 1281-128
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  • 8
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    Magnetic field structure of interplanetary magnetic clouds at 1 AU (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Interplanetary magnetic clouds emerge as a feature of the solar wind at 1 AU, exhibiting enhanced field strength and lower plasma temperature and density than the surrounding plasma. A least-squares program has been developed which fits magnetic field data within a cloud, while estimating such cloud properties as its size, maximum field strength, and axis inclination. The results obtained from a study of 12 clouds observed at 1 AU point to a probable cloud axis direction within 15 deg of the ecliptic plane and about 100 deg from the sun's direction, when projected into the ecliptic plane. A wide variety of orientations is observed; some extend to 80 deg from the ecliptic.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 11957-11
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  • 9
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    Sorption cooler technology development at JPL (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Simple heating and cooling of chemisorption and physisorption compressors provide high pressure gas, which, when expanded through a Joule-Thomson (J- T) valve, can provide cooling from 0.3 to 200 K depending on the sorbent/gas combination. System life tests are under way on Pr(1-n)Ce(n)O(x)/O2 (PCO/O2) chemisorption compressors for 65-80 K cooling and on carbon/krypton (C/Kr) physisorption compressors for 120-140 K cooling. Investigations have been initiated to examine reliability physics issues related to critical compressor components such as sorbents, container materials and electrical heaters.
    Keywords: ENGINEERING (GENERAL)
    Type: Cryogenics (ISSN 0011-2275); 30; 239-245
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  • 10
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    Partitioning of siderophile elements in the Fe-Ni-S system - 1 bar to 80 kbar (1991)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Partition coefficients for Au, Ni, P, and Ge between solid Fe-Ni metal and sulfur-bearing metallic liquids have been measured at 7, 27 and 80 kbar. These are the only such data for Au, P, and Ge at high pressure. Comparison of the present partitioning results to those obtained at 1 bar indicate that only the 80-kbar Ge data differ significantly from the 1-bar experiments. Thus, many low-pressure partitioning experiments in the Fe-Ni-S-P system may have applicability to the greater portion of the earth's upper mantle or, alternatively, the entire mantle of Mars.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth and Planetary Science Letters (ISSN 0012-821X); 105; 1-3,; 127-133
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