19,666 research outputs found

    Biomedical applications of NASA science and technology Final report, 15 Jun. 1966 - 14 Jun. 1967

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    Information retrieval efforts by biomedical applications team to supply clinical and research personnel with NASA science and technolog

    Growth, Characterization, and Electrochemical Properties of Doped n-Type KTaO_3 Photoanodes

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    The effects of compositionally induced changes on the semiconducting properties, optical response, chemical stability, and overall performance of KTaO_3 photoanodes in photoelectrochemical (PEC) cells have been investigated. Single crystals of n-type Ca- and Ba-doped KTaO_3 with carrier concentrations ranging from 0.45 to 11.5×10^(19) cm^(−3) were grown and characterized as photoanodes in basic aqueous electrolyte PEC cells. The PEC properties of the crystals, including the photocurrent, photovoltage, and flatband potential in contact with 8.5 M NaOH(aq) were relatively independent of whether Ca or Ba was used to produce the semiconducting form of KTaO_3. All of the Ca- or Ba-doped KTaO_3 single-crystal photoanodes were chemically stable in the electrolyte and, based on the open-circuit potential and the band-edge positions, were capable of unassisted photochemical H_2 and O_2 evolution from H_2O. The minority-carrier diffusion lengths values were small and comparable to the depletion region width. Photoanodic currents were only observed for photoanode illumination with light above the bandgap (i.e., λ<340 nm). The maximum external quantum yield occurred at λ=255 nm (4.85 eV), and the depletion width plus the minority-carrier diffusion length ranged from 20 to 65 nm for the various KTaO_3-based photoanode materials

    Applications of aerospace technology in biology and medicine

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    Utilization of National Aeronautics and Space Administration (NASA) technology in medicine is discussed. The objective is best obtained by stimulation of the introduction of new or improved commercially available medical products incorporating aerospace technology. A bipolar donor/recipient model of medical technology transfer is presented to provide a basis for the team's methodology. That methodology is designed to: (1) identify medical problems and NASA technology that, in combination, constitute opportunities for successful medical products; (2) obtain the early participation of industry in the transfer process; and (3) obtain acceptance by the medical community of new medical products based on NASA technology. Two commercial transfers were completed: the Stowaway, a lightweight wheelchair that provides mobility for the disabled and elderly in the cabin of commercial aircraft, and Micromed, a portable medication infusion pump for the reliable, continuous infusion of medications such as heparin or insulin. The marketing and manufacturing factors critical to the commercialization of the lightweight walker incorporating composite materials were studied. Progress was made in the development and commercialization of each of the 18 currently active projects

    Religion, race and abstinence from drug use among American adolescents

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    https://deepblue.lib.umich.edu/bitstream/2027.42/137867/1/occ58.pd

    Reanalysis of Farmer Willingness to Tolerate Deer Damage in Western New York

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    Crop depredation by white-tailed deer (Odocoileus uirginianus) has been examined and discussed by wildlife managers since at least the early 1930\u27s (Leopold 1933:283). As with most aspects of game management in those early years, managers\u27 efforts focused on the biological parameters of depredation and control. In the 1960\u27s a few researchers began examining the social implications of deer management and found farmers to be surprisingly tolerant of most deer damage (McDowell and Benson 1960, McNeil 1962:81, Flyger and Thoerig 1962:48). Because of changing agricultural, habitat, and deer population conditions, studies of farmer tolerance of deer damage were initiated in New York (Brown et al. 1977, 1978, 1979, 1980). This research helped to systematically quantify and apply the concept of farmer tolerance of deer damage as a determinant of deer range carrying capacity on agricultural lands in New York State

    A Liquid Model Analogue for Black Hole Thermodynamics

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    We are able to characterize a 2--dimensional classical fluid sharing some of the same thermodynamic state functions as the Schwarzschild black hole. This phenomenological correspondence between black holes and fluids is established by means of the model liquid's pair-correlation function and the two-body atomic interaction potential. These latter two functions are calculated exactly in terms of the black hole internal (quasilocal) energy and the isothermal compressibility. We find the existence of a ``screening" like effect for the components of the liquid.Comment: 20 pages and 6 Encapsulated PostScript figure

    Free Energy and Entropy for Semi-classical Black Holes in the Canonical Ensemble

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    We consider the thermodynamics of a black hole coupled to thermal radiation in a spatially finite (spherical) region. Thermodynamic state functions are derived in the canonical ensemble, defined by elements of radius ror_o and boundary temperature T(ro)T(r_o). Using recent solutions of the semi-classical back reaction problem, we compute the O(ℏ)O(\hbar) corrections to the mass of the black hole, thermal energy, the entropy and free energy due to the presence of hot conformal scalars, massless spinors and U(1) gauge quantum fields in the vicinity of the hole. The free energy is particularly important for assessing under what conditions the nucleation of black holes from hot flat space is likely to occur.Comment: 25 pages, not including 10 Figures available upon request from the author: LAEFF-94/08. Typed in LaTe

    Integral Relaxation Time of Single-Domain Ferromagnetic Particles

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    The integral relaxation time \tau_{int} of thermoactivating noninteracting single-domain ferromagnetic particles is calculated analytically in the geometry with a magnetic field H applied parallel to the easy axis. It is shown that the drastic deviation of \tau_{int}^{-1} from the lowest eigenvalue of the Fokker-Planck equation \Lambda_1 at low temperatures, starting from some critical value of H, is the consequence of the depletion of the upper potential well. In these conditions the integral relaxation time consists of two competing contributions corresponding to the overbarrier and intrawell relaxation processes.Comment: 8 pages, 3 figure

    Semiclassical charged black holes with a quantized massive scalar field

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    Semiclassical perturbations to the Reissner-Nordstrom metric caused by the presence of a quantized massive scalar field with arbitrary curvature coupling are found to first order in \epsilon = \hbar/M^2. The DeWitt-Schwinger approximation is used to determine the vacuum stress-energy tensor of the massive scalar field. When the semiclassical perturbation are taken into account, we find extreme black holes will have a charge-to-mass ratio that exceeds unity, as measured at infinity. The effects of the perturbations on the black hole temperature (surface gravity) are studied in detail, with particular emphasis on near extreme ``bare'' states that might become precisely zero temperature ``dressed'' semiclassical black hole states. We find that for minimally or conformally coupled scalar fields there are no zero temperature solutions among the perturbed black holes.Comment: 19 pages; 1 figure; ReVTe
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