10,598 research outputs found

    Zonal and tesseral harmonic coefficients for the geopotential function, from zero to 18th order

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    Zonal and tesseral harmonic coefficients for the geopotential function are usually tabulated in normalized form to provide immediate information as to the relative significance of the coefficients in the gravity model. The normalized form of the geopotential coefficients cannot be used for computational purposes unless the gravity model has been modified to receive them. This modification is usually not done because the absolute or unnormalized form of the coefficients can be obtained from the simple mathematical relationship that relates the two forms. This computation can be quite tedious for hand calculation, especially for the higher order terms, and can be costly in terms of storage and execution time for machine computation. In this report, zonal and tesseral harmonic coefficients for the geopotential function are tabulated in absolute or unnormalized form. The report is designed to be used as a ready reference for both hand and machine calculation to save the user time and effort

    Asymptotic solution of a model for bilayer organic diodes and solar cells

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    The current voltage characteristics of an organic semiconductor diode made by placing together two materials with dissimilar electron affinities and ionisation potentials is analysed using asymptotic methods. An intricate boundary layer structure is examined. We find that there are three regimes for the total current passing through the diode. For reverse bias and moderate forward bias the dependency of the voltage on the current is similar to the behaviour of conventional inorganic semiconductor diodes predicted by the Shockley equation and are governed by recombination at the interface of the materials. There is then a narrow range of currents where the behaviour undergoes a transition. Finally for large forward bias the behaviour is different with the current being linear in voltage and is primarily controlled by drift of charges in the organic layers. The size of the interfacial recombination rate is critical in determining the small range of current where there is rapid transition between the two main regimes. The extension of the theory to organic solar cells is discussed and the analogous current voltage curves derived in the regime of interest

    Evaluation of dry lubricants and bearings for spacecraft applications

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    Performance of dry film lubricated ball bearings in high vacuum environmen

    A comprehensive computer program for predicting solar cell performance

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    Comprehensive computer program for predicting solar cell performanc

    The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5

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    We present Hubble Space Telescope (HST) near-infrared photometry of the coldest known brown dwarf, WISE J085510.83−-071442.5 (WISE 0855−-0714). WISE 0855−-0714 was observed with the Wide Field Camera 3 (WFC3) aboard HST using the F105W, F125W, and F160W filters, which approximate the YY, JJ, and HH near-infrared bands. WISE 0855−-0714 is undetected at F105W with a corresponding 2σ\sigma magnitude limit of ∼\sim26.9. We marginally detect WISE 0855−-0714 in the F125W images (S/N ∼\sim4), with a measured magnitude of 26.41 ±\pm 0.27, more than a magnitude fainter than the J−J-band magnitude reported by Faherty and coworkers. WISE J0855−-0714 is clearly detected in the F160W band, with a magnitude of 23.90 ±\pm 0.02, the first secure detection of WISE 0855−-0714 in the near-infrared. Based on these data, we find that WISE 0855−-0714 has extremely red F105W−-F125W and F125W−-F160W colors relative to other known Y dwarfs. We find that when compared to the models of Saumon et al. and Morley et al., the F105W−-F125W and F125W−-F160W colors of WISE 0855−-0714 cannot be accounted for simultaneously. These colors likely indicate that we are seeing the collapse of flux on the Wien tail for this extremely cold object.Comment: Accepted for publication in ApJ Letter

    Scholarly and Institutional Challenges to the Law of Evidence: From Bentham to the ADR Movement

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    The Effects of Acute Ammonia Toxicity on Certain Homogram Parameters in Sheep

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    Due to the rapidly expanding human population, one of the greatest problems facing agricultural scientists is the development of adequate food resources to meet the growing demand for quality protein. The development of more economical and higher quality feed for ruminant animals is essential since they are one of man\u27s primary sources of animal protein. Microorganisms in the ruminant stomach convert relatively cheap non-protein nitrogen compounds into bacterial proteins, which are digested, absorbed, and utilized by the host animal. Urea, a common non-protein nitrogen compound, is hydrolyzed into ammonia and carbon dioxide by bacterial urease. When urea is hydrolyzed faster than it is utilized by bacteria, quantities of ammonia are absorbed through the rumen wall into the bloodstream. This normally creates no problem, since the ammonia is converted into urea by the liver, however, toxicity may occur if the blood ammonium-nitrogen (BAN) level surpasses the animal\u27s detoxification capacity. High levels of BAN are not only toxic, but result in an efficient utilization of nitrogen for protein synthesis. There have been extensive investigations involving the physiological, nutritional, and metabolic effects of an elevated BAN level. However, inadequate information is available concerning body fluid, differential tissue ammonia content, and blood hemogram quantities resulting from toxic BAN levels. The purpose of this investigation was to detect changes in the following hemogram parameters resulting from acute ammonia intoxication: packed cell volume (PCV), hemoglobin concentration (Hb), total red blood cell count (RBC), and total white blood cell count (WBC)
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