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  • 1
    Publication Date: 2011-08-24
    Description: We investigated the effect of peripherally administered caffeine (50 mg/kg), choline (30, 60, or 120 mg/kg) or combinations of both drugs on the spontaneous release of acetylcholine (ACh) from the corpus striatum of anesthetized rats using in vivo microdialysis. Caffeine alone or choline in the 30 or 60 mg/kg dose failed to increase ACh in microdialysis samples; the 120 mg/kg choline dose significantly enhanced ACh during the 80 min following drug administration. Coadministration of caffeine with choline significantly increased ACh release after each of the choline doses tested. Peak microdialysate levels with the 120 mg/kg dose were increased 112% when caffeine was additionally administered, as compared with 54% without caffeine. These results indicate that choline administration can enhance spontaneous ACh release from neurons, and that caffeine, a drug known to block adenosine receptors on these neurons, can amplify the choline effect.
    Keywords: Life Sciences (General)
    Type: Life sciences (ISSN 0024-3205); Volume 51; 20; 1597-601
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  • 2
    Publication Date: 2011-08-24
    Description: Interstitial fluid flow may mediate skeletal remodeling in response to mechanical loading. Because nitric oxide (NO) has been shown to be an osteoblast mitogen and inhibitor of osteoclastic resorption, we investigated and characterized the role of fluid shear on the release of NO in osteoblasts. Rat calvarial cells in a stationary culture produced undetectable levels of NO. Fluid shear stress (6 dyn/cm2) rapidly increased NO release rate to 9.8 nmol.h-1.mg protein-1 and sustained this production for 12 h of exposure to flow. Cytokine treatment also induced NO synthesis after a 12-h lag phase of zero production, followed by a production rate of 0.6 nmol.h-1.mg protein-1. Flow-induced NO production was blocked by the NO synthase (NOS) inhibitor NG-amino-L-arginine, but not by dexamethasone, which suggests that the flow stimulated a constitutive NOS isoform. This is the first time that a functional constitutively present NOS isoform has been identified in osteoblasts. Moreover, fluid flow represents the most potent stimulus of NO release in osteoblasts reported to date. Fluid flow-induced NO production may therefore play a primary role in bone maintenance and remodeling.
    Keywords: Life Sciences (General)
    Type: The American journal of physiology (ISSN 0002-9513); Volume 271; 1 Pt 1; E205-8
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  • 3
    Publication Date: 2011-08-24
    Description: A comprehensive characterization program is underway at JPL to generate test data on long-life, miniature Stirling-cycle cryocoolers for space application. The key focus of this paper is on the thermal performance of the British Aerospace (BAe) 80 K split-Stirling-cycle cryocooler as measured in a unique calorimetric thermal-vacuum test chamber that accurately simulates the heat-transfer interfaces of space. Two separate cooling fluid loops provide precise individual control of the compressor and displacer heatsink temperatures. In addition, heatflow transducers enable calorimetric measurements of the heat rejected separately by the compressor and displacer. Cooler thermal performance has been mapped for coldtip temperatures ranging from below 45 K to above 150 K, for heatsink temperatures ranging from 280 K to 320 K, and for a wide variety of operational variables including compressor-displacer phase, compressor-displacer stroke, drive frequency, and piston-displacer dc offset.
    Keywords: ENGINEERING (GENERAL)
    Type: In: IECEC '92; Proceedings of the 27th Intersociety Energy Conversion Engineering Conference, San Diego, CA, Aug. 3-7, 1992. Vol. 5 (A93-25851 09-44); p. 5.101-5.107.
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  • 4
    Publication Date: 2011-08-24
    Description: This paper provides a summary overview of the vibration characteristics of split Stirling cryocoolers of the Oxford type and describes means being developed to achieve vibration levels consistent with the exacting requirements of sensitive infrared spectrometer instruments currently under development for NASA applications. A key emphasis of the paper is on exploring both active and passive means of reducing the residual upper harmonics of the drive frequency that remain with nulled back-to-back compressor and displacer units. Vibration supression results, measured with JPL's unique six-DOF force dynamometer, are presented for an 80 K Stirling cooler.
    Keywords: ENGINEERING (GENERAL)
    Type: In: Advances in cryogenic engineering. Vol. 37B - Proceedings of the 1991 Cryogenic Engineering Conference, Univ. of Alabama, Huntsville, June 11-14, 1991 (A93-48578 20-37); p. 1019-1027.
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  • 5
    Publication Date: 2011-08-24
    Description: For redundant miniature Stirling-cycle cryocoolers in space applications, the off-state heat conduction down the coldfinger of one cooler is a parasitic heat load on the other coolers. At JPL, a heat flow transducer specifically designed to measure this load has been developed, and measurements have been performed on the coldfinger of a British Aerospace 80 K Stirling cooler with the tip temperature ranging between 40 and 170 K. Measurements have also been made using a transient warmup technique, where the warmup rates of the coldtip under various applied heat loads are used to determine the static conduction load. There is a difference between the results of these two methods, and these differences are discussed with regard to the applicability of the transient warmup method to a nonoperating coldfinger.
    Keywords: ENGINEERING (GENERAL)
    Type: In: Advances in cryogenic engineering. Vol. 37B - Proceedings of the 1991 Cryogenic Engineering Conference, Univ. of Alabama, Huntsville, June 11-14, 1991 (A93-48578 20-37); p. 1037-1043.
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  • 6
    Publication Date: 2011-08-24
    Description: The white blood cell (WBC) elements and the bone marrow myeloid progenitor cell populations were analyzed to ascertain adaptation to micro-gravity and subsequent readaptation to 1 G in rats flown on the 14-day Spacelab Life Sciences-2 (SLS-2) mission. Bone marrow cells were harvested from one group of rats killed inflight (FD13) and blood was drawn from three other groups at various times. The WBC level was normal on FD14 with the exception of neutrophilia. On FD13, numbers of colony-forming units-granulocyte (CFU-G), CFU-GM, and CFU-M from flight animals were decreased compared with ground controls when incubated with recombinant rat interleukin-3 (rrIL-3) alone or in combination with recombinant human erythropoietin (rhEpo). On recovery (R + 0), flight rats had decreased numbers of total leukocytes and absolute numbers of lymphocytes and monocytes with elevated neutrophils compared with control rats. They had lower numbers of CD4, CD8, CD2, CD3, and B cells in the peripheral blood but no differences in spleen lymphocytes.
    Keywords: Life Sciences (General)
    Type: Journal of leukocyte biology (ISSN 0741-5400); Volume 60; 1; 37-43
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  • 7
    Publication Date: 2004-12-03
    Description: Combustion synthesis, otherwise known as self-propagating high temperature synthesis (SHS), can be used to produce engineered advanced porous material implants which offer the possibility for bone ingrowth as well as a permanent structure framework for the long-term replacement of bone defects. The primary advantage of SHS is based on its rapid kinetics and favorable energetics. The structure and properties of materials produced by SHS are strongly dependent on the combustion reaction conditions. Combustion reaction conditions such as reaction stoichiometry, particle size, green density, the presence and use of diluents or inert reactants, and pre-heating of the reactants, will affect the exothermicity of the reaction. A number of conditions must be satisfied in order to obtain high porosity materials: an optimal amount of liquid, gas and solid phases must be present in the combustion front. Therefore, a balance among these phases at the combustion front must be created by the SHS reaction to successfully engineer a bone replacement material system. Microgravity testing has extended the ability to form porous products. The convective heat transfer mechanisms which operate in normal gravity, 1 g, constrain the combustion synthesis reactions. Gravity also acts to limit the porosity which may be formed as the force of gravity serves to restrict the gas expansion and the liquid movement during reaction. Infiltration of the porous product with other phases can modify both the extent of porosity and the mechanical properties.
    Keywords: Materials Processing
    Type: Fifth International Microgravity Combustion Workshop; 145-148; NASA/CP-1999-208917
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  • 8
    Publication Date: 2006-06-13
    Description: We will use TOPEX/POSEIDON altimetry in combination with ongoing and planned efforts, including data from the European Remote Sensing satellite (ERS-1), in situ measurements designed specifically to complement satellite altimetry, and assimilation of these several data types into eddy-resolving numerical models in order to understand the dynamics and energetics of midlatitude western boundary currents (specifically, the Gulf Stream and the Kuroshio Extension). A better understanding of the recirculation of midlatitude gyres can best be undertaken in the format of such regional, eddy-resolving experiments. Such regional programs will enhance and be enhanced by the larger scale circulation studies of the World Ocean Circulation Experiment (WOCE) as well as by global-scale eddy-resolving models that we will develop prior to the TOPEX/POSEIDON mission. This effort includes participation on the TOPEDX/POSEIDON Science Team.
    Keywords: OCEANOGRAPHY
    Type: JPL, TOPEX(Poseidon Science Investigations Plan; p 95-102
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  • 9
    Publication Date: 2006-02-14
    Description: Cell design criteria were established which can result in a safe lithium/thionyl chloride cell. A cell vent, a low area internal anode cell, cell balance and composition of the cathode-electrolyte solution were found to be important factors in the design of a safe cell. In addition to routine testing, both undischarged and discharged cells were subjected to electrical abuse, environmental abuse and mechanical abuse without disassembly.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA. Goddard Space Flight Center The 1982 Goddard Space Flight Center Battery Workshop; p 75-84
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  • 10
    Publication Date: 2006-04-12
    Description: The geostationary and polar satellites comprising the current operational system are discussed. The data acquisition capabilities of both satellite types and their complementary functions are reviewed. The advanced very high resolution radiometer on the TIROS N satellites is particularly addressed along with the imaging and atmospheric sounding instrumentation aboard the GOES satellites. The dissemination of the satellite data to the prospective users is also discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: The Conception, Growth, Accomplishments and Future of Meteorol. Satellites; p 34-40
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