5,105 research outputs found

    Effects of the Cosmos 1129 Soviet paste diet on body composition in the growing rat

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    Six Simonsen albino rats (45 days of age) were placed on a regimen of 40 g/day the semipurified Soviet paste diet used in the 18.5 day Cosmos 1129 spacecraft was to support the rats for various experiments on the physiological effects of weightlessness. The animals were maintained on the Soviet paste diet for 35 days, metabolic rate was measured and body composition was determined by direct analysis. The results were compared with a control group of rates of the same age, which had been kept on a standard commercial grain diet during the same period of time

    CONCEPTUAL DESIGN OF A 2000 kW NUCLEAR HEAT SOURCE SUITABLE FOR SPACE ELECTRIC POWER.

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    A conceptual design of a 2000 kW/sub/t Rankine system for nuclear-electric space power is described. The system includes a unique reactor-boiler unit operating at 1500°K that utilizes heatpipes in lieu of a conventionally pump primary loop. An efficient heatpipe radiator rejects waste hea at 1035°K. Overall system efficiency is 18.8% yielding a net electrical output of 375 kW. The system specific mass is 10 g/W including a generous shadow shield for unmanned payloads

    Development of a three-dimensional time-dependent flow field model

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    A three-dimensional, time-dependent mathematical model to represent Mobile Bay was developed. Computer programs were developed which numerically solve the appropriate conservation equations for predicting bay and estuary flow fields. The model is useful for analyzing the dispersion of sea water into fresh water and the transport of sediment, and for relating field and physical model data

    A three-dimensional, time-dependent model of Mobile Bay

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    A three-dimensional, time-variant mathematical model for momentum and mass transport in estuaries was developed and its solution implemented on a digital computer. The mathematical model is based on state and conservation equations applied to turbulent flow of a two-component, incompressible fluid having a free surface. Thus, bouyancy effects caused by density differences between the fresh and salt water, inertia from thare river and tidal currents, and differences in hydrostatic head are taken into account. The conservation equations, which are partial differential equations, are solved numerically by an explicit, one-step finite difference scheme and the solutions displayed numerically and graphically. To test the validity of the model, a specific estuary for which scaled model and experimental field data are available, Mobile Bay, was simulated. Comparisons of velocity, salinity and water level data show that the model is valid and a viable means of simulating the hydrodynamics and mass transport in non-idealized estuaries

    Body composition data from the rat subjects of Cosmos 1129 experiment K-316

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    The effects of 18.5 days of weightlessness on the body composition of young, growing, male laboratory rats were examined. Three groups of 5 rats each were examined. It is indicated that exposure of young, growing, male rats to 18.5 days of weightlessness produces: (1) no effect on the quantity of fat stored by the body; (2) a slight reduction in the quantity of fat free tissue laid down by the body; (3) a small reduction in the fraction of water contained by the fat free body mass; (4) a similar reduction in the fraction of water contained by the fat free skin and fat free carcass; (5) a shift in relative distribution of the total body water from skin to viscera; (6) a diminution in the fraction of extracellular water contained by the fat free body; (7) no effect on the fraction of total skeletal musculature contained by the fat free body, as indicated by body creatine content; (8) a sizeable reduction in the fraction of bone mineral contained by the fat free body, as calculated from body calcium content. The nature of the physiological changes induced by unloading from Earth gravity in the mammalian organism are illustrated

    Nonaxisymmetric Magnetorotational Instability in Proto-Neutron Stars

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    We investigate the stability of differentially rotating proto-neutron stars (PNSs) with a toroidal magnetic field. Stability criteria for nonaxisymmetric MHD instabilities are derived using a local linear analysis. PNSs are expected to have much stronger radial shear in the rotation velocity compared to normal stars. We find that nonaxisymmetric magnetorotational instability (NMRI) with a large azimuthal wavenumber mm is dominant over the kink mode (m=1m=1) in differentially rotating PNSs. The growth rate of the NMRI is of the order of the angular velocity Ω\Omega which is faster than that of the kink-type instability by several orders of magnitude. The stability criteria are analogous to those of the axisymmetric magnetorotational instability with a poloidal field, although the effects of leptonic gradients are considered in our analysis. The NMRI can grow even in convectively stable layers if the wavevectors of unstable modes are parallel to the restoring force by the Brunt-V\"ais\"al\"a oscillation. The nonlinear evolution of NMRI could amplify the magnetic fields and drive MHD turbulence in PNSs, which may lead to enhancement of the neutrino luminosity.Comment: 24pages, 7figures, Accepted for publication in the Astrophysical Journal (December 12, 2005

    An in vitro comparison between two methods of electrical resistance measurement for occlusal caries detection

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    Because of different measurement techniques and the easier design of the CRM prototype, this in vitro study aimed to compare the diagnostic performance and reproducibility of two electrical methods (Electronic Caries Monitor III, ECM and Cariometer 800, CRM) for occlusal caries detection, and to evaluate the effect of staining/ discoloration of fissures on diagnostic performance. Hundred and seventeen third molars with no apparent occlusal cavitation were selected. Six examiners inspected all specimens independently, using the CRM, and a subgroup of 4 using the ECM. Histological validation using a stereomicroscope was performed after hemisectioning. Intra- and interexaminer reproducibility was assessed by Lin's concordance correlation coefficient (CCC) and Bland and Altman analysis. Diagnostic performance parameters included sensitivity (SE), specificity (SP) and area under the ROC curve (A(z)). The CCC yielded an intra- and interexaminer reproducibility of 0.69/0.62 (ECM) and of 0.79/0.74 (CRM). The mean intra- and interexaminer 95% range of measurements (range between Bland and Altman limits of agreement) given in percentages of the instrument reading were 67%/65% for the ECM and 28%/33% for the CRM. A(z) at the D3-4 level was 0.74 (ECM) and 0.78 (CRM). The CRM showed at least equivalent diagnostic performance to the ECM. However, improvement is still desirable. Diagnostic performance appeared to be enhanced in discolored lesions; however, this may be related to sample lesion distribution characteristics. Copyright (C) 2006 S. Karger AG, Basel

    Neurophysiology

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    Contains reports on two research projects.Teagle Foundation, IncorporatedNational Institutes of HealthBell Telephone Laboratories, Incorporate
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