30,442 research outputs found

    Optical monitoring system

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    Instrument can measure optical transmission, reflectance, and scattering. This information can be used to identify changes in optical properties or deviations from required optical standards. Device consists of monochromatic source, photo detector, transfer mirror, and hemiellipsoid. System might be used to measure optical properties of thin film

    Design and performance evaluation of small, two- and four-stage depressed collectors for a 4.8 to 9.6 GHz high-performance traveling wave tube

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    A program to improve the efficiency of traveling wave tubes (TWT's) for use in electronic countermeasure (ECM) systems by applying multistage depressed collector (MDC) and spent beam refocusing techniques is studied. Three dimensional electron trajectories are computed through-out the slow wave structure of the TWT, the spent beam refocuser, and the depressed collector. Both TWT and MDC performances are analytically evaluated

    Computer program for calculating aerodynamic characteristics of upper-surface-blowing and over-wing-blowing configurations

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    The program is based on the inviscid wing-jet interaction theory of Lan and Campbell, and the jet entrainment theory of Lan. In the interaction theory, the flow perturbations are computed both inside and outside the jet, separately, and then matched on the jet surface to satisfy the jet boundary conditions. The jet Mach number is allowed to be different from the free stream value (Mach number nonuniformity). These jet boundary conditions require that the static pressure be continuous across the jet surface which must always remain as a stream surface. These conditions, as well as the wing-surface tangency condition, are satisified only in the linearized sense. The detailed formulation of these boundary conditions is based on the quasi-vortex-lattice method of Lan

    An Archaeological Study of the McPherson Road Extension Project Laredo, Texas

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    In October 1977, the Commissioners Court of Webb County and the Center for Archaeological Research, The University of Texas at San Antonio, entered into a contract for an archaeological assessment of the McPherson Road Extension Project, Laredo, Texas. The object of this survey was to locate, record and evaluate archaeological or historical resources that might be present within the proposed right-of-way. As a result of the survey, three archaeological sites (41 WB 64, 41 WB 65 and 41 WB 66) were located within the right-of-way, and it was determined that these sites would be affected by road construction. Sites 41 WB 64 and 41 WB 65 were recommended for limited testing to evaluate their potential. Site 41 WB 66 was considered to be of little archaeological significance

    Fabrication and structural analysis of ZnO coated fiber optic phase modulators

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    Fiber optic modulators were fabricated by coating optical fibers with electrode and piezoelectric ZnO layers. The techniques of piezoelectric fiber optic modulator (PFOM) fabrication are presented, and the microstructure and crystallographic texture of the coatings are analyzed. In order to produce thick (approximately 5 μm) ZnO coatings, it was necessary to study the reactive dc magnetron sputtering process in O2/Ar gas mixtures under conditions close to the transition between an oxidized and nonoxidized Zn target surface. In situ quartz crystal microbalance measurements of the deposition rate revealed thee distinct regions in the deposition rate (R) vs oxygen partial pressure behavior, at constant total pressure, for sputtering under conditions that provided an oxidized Zn target surface. Additionally, a transition between oxygen and argon dominated sputtering as observed by varying the sputtering pressure while maintaining a constant The transition between oxygen and argon dominated sputtering influences R to varying extents within the three R vs regions for an oxidized target surface. Correlations among the cathode current and voltage, deposition rate, and gas flow rate are presented to give a better understanding of the reactive sputtering processes occurring at the oxidized Zn target surface. Sputtering conditions optimized for a high ZnO deposition rate were used to produce 〈001〉 radially oriented ZnO fiber coatings for PFOM devices that can produce optical phase shifts as large as 0.38 rad/

    Effect of Piezo Electric Oscillations on X-Ray Patterns of Quartz

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    Experiments have been made to determine the amplitude of vibration of the atoms in a quartz lattice due to piezo electric oscillations. A series of Laue X-ray patterns have been made of quartz plates cut at various angles to the electric axes. Very marked intensity differences are apparent between the patterns made with the plates oscillating and not oscillating

    Complying With Feed Additive and Drug Withdrawl Periods

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    Most drugs are accumulated in excretory organs such as the kidneys and liver , and they are found in higher levels for a longer time in these organs than in other tissue. Due to a continuous excretion of the drugs from these organs, tissue levels are usually rapidly reduced after the drug is no longer fed or injected. The rate of excretion of a drug and its end products from animal tissues must be established before it can be considered for approval by the Food and Drug Administration. Then withdrawal periods that are sufficiently long enough to permit complete or near complete elimination of the drug from animal tissues , milk or eggs are established. Once a feed additive is approved it means that the FDA considers it completely safe for use in animal feeds without unsafe levels of residues occurring in the animal tis sue or its products if the withdrawal period is observed and it is fed at recommended levels

    Association between urinary sodium, creatinine, albumin, and long term survival in chronic kidney disease

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    Dietary sodium intake is associated with hypertension and cardiovascular risk in the general population. In patients with chronic kidney disease, sodium intake has been associated with progressive renal disease, but not independently of proteinuria. We studied the relationship between urinary sodium excretion and urinary sodium:creatinine ratio and mortality or requirement for renal replacement therapy in chronic kidney disease. Adults attending a renal clinic who had at least one 24-hour urinary sodium measurement were identified. 24-hour urinary sodium measures were collected and urinary sodium:creatinine ratio calculated. Time to renal replacement therapy or death was recorded. 423 patients were identified with mean estimated glomerular filtration rate of 48ml/min/1.73m<sup>2</sup>. 90 patients required renal replacement therapy and 102 patients died. Mean slope decline in estimated glomerular filtration rate was -2.8ml/min/1.73m<sup>2</sup>/year. Median follow-up was 8.5 years. Patients who died or required renal replacement therapy had significantly higher urinary sodium excretion and urinary sodium:creatinine but the association with these parameters and poor outcome was not independent of renal function, age and albuminuria. When stratified by albuminuria, urinary sodium:creatinine was a significant cumulative additional risk for mortality, even in patients with low level albuminuria. There was no association between low urinary sodium and risk, as observed in some studies. This study demonstrates an association between urinary sodium excretion and mortality in chronic kidney disease, with a cumulative relationship between sodium excretion, albuminuria and reduced survival. These data support reducing dietary sodium intake in chronic kidney disease but further study is required to determine the target sodium intake
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