10,932 research outputs found

    Extreme Precision Antenna Reflector Study Results

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    Thermal and mechanical distortion degrade the RF performance of antennas. The complexity of future communications antennas requires accurate, dimensionally stable antenna reflectors and structures built from materials other than those currently used. The advantages and disadvantages of using carbon fibers in an epoxy matrix are reviewed as well as current reflector fabrications technology and adjustment. The manufacturing sequence and coefficient of thermal expansion of carbon fiber/borosilicate glass composites is described. The construction of a parabolic reflector from this material and the assembling of both reflector and antenna are described. A 3M-aperture-diameter carbon/glass reflector that can be used as a subassembly for large reflectors is depicted. The deployment sequence for a 10.5M-aperture-diameter antenna, final reflector adjustment, and the deployment sequence for large reflectors are also illustrated

    Both critical and applied? Action research and transformative change in the UK water sector

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    Social research on water is often critical or applied but rarely both. In this chapter, we share our experiences of negotiating tensions of critical and applied action research through the interdisciplinary and cross-sector UK water research project TWENTY65. By stressing a variety of perspectives, and highlighting the plurality of available options, we argue that action research on water can be constructive, collaborative and yet still critical. However, three key issues of performing action research seeking to support transformative change in technical fields are identified. These issues relate to translation and integrity, applicability, and influence. Despite this, we argue that action research is particularly suitable for working in technical fields because these areas significantly impact upon society and the environment and still are dominated by technocratic decision making with limited democratic or social justice input. Action research in technical areas provides an opportunity for social science to present its perspectives outside of ‘normal’ social science contexts, supporting greater attention to ethical, justice and environmental concerns. Applying critical action research to water management enables informed dialogue with technical decision makers, raising and pushing forward socially and environmentally progressive futures

    Apollo applications program data archives

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    Apollo applications program data archives to collect, store, retrieve, and distribute experiments-related dat

    Risk factors for failure of outpatient parenteral antibiotic therapy (OPAT) in infective endocarditis

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    Objectives: To identify risk factors for failure of outpatient antibiotic therapy (OPAT) in infective endocarditis (IE). Patients and methods: We identified IE cases managed at a single centre over 12 years from a prospectively maintained database. ‘OPAT failure’ was defined as unplanned readmission or antibiotic switch due to adverse drug reaction or antibiotic resistance. We analysed patient and disease-related risk factors for OPAT failure by univariate and multivariate logistic regression. We also retrospectively collected follow-up data on adverse disease outcome (defined as IE-related death or relapse) and performed Kaplan–Meier survival analysis up to 36 months following OPAT. Results: We identified 80 episodes of OPAT in IE. Failure occurred in 25/80 episodes (31.3%). On multivariate analysis, cardiac or renal failure [pooled OR 7.39 (95% CI 1.84–29.66), P = 0.005] and teicoplanin therapy [OR 8.69 (95% CI 2.01–37.47), P = 0.004] were independently associated with increased OPAT failure. OPAT failure with teicoplanin occurred despite therapeutic plasma levels. OPAT failure predicted adverse disease outcome up to 36 months (P = 0.016 log-rank test). Conclusions: These data caution against selecting patients with endocarditis for OPAT in the presence of cardiac or renal failure and suggest teicoplanin therapy may be associated with suboptimal OPAT outcomes. Alternative regimens to teicoplanin in the OPAT setting should be further investigated

    A mechanical, thermal and electrical packaging design for a prototype power management and control system for the 30 cm mercury ion thruster

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    A prototype electric power management and thruster control system for a 30 cm ion thruster is described. The system meets all of the requirements necessary to operate a thruster in a fully automatic mode. Power input to the system can vary over a full two to one dynamic range (200 to 400 V) for the solar array or other power source. The power management and control system is designed to protect the thruster, the flight system and itself from arcs and is fully compatible with standard spacecraft electronics. The system is easily integrated into flight systems which can operate over a thermal environment ranging from 0.3 to 5 AU. The complete power management and control system measures 45.7 cm (18 in.) x 15.2 cm (6 in.) x 114.8 cm (45.2 in.) and weighs 36.2 kg (79.7 lb). At full power the overall efficiency of the system is estimated to be 87.4 percent. Three systems are currently being built and a full schedule of environmental and electrical testing is planned

    The swept angle retarding mass spectrometer: Initial results from the Michigan auroral probe sounding rocket

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    Data from a sounding rocket flight of the swept angle retarding ion mass spectrometer (SARIMS) are presented to demonstrate the capability of the instrument to make measurements of thermal ions which are differential in angle, energy, and mass. The SARIMS was flown on the Michigan auroral probe over regions characterized first by discrete auroral arcs and later by diffuse precipitation. The instrument measured the temperature, densities, and flow velocities of the ions NO(+) and O(+). Measured NO(+) densities ranged from 10 to the 5th power up to 3 x 10 to the 5th power ions/cu cm, while the measured O(+) densities were a factor of 5-10 less. Ion temperatures ranged from 0.15 up to 0.33 eV. Eastward ion flows approximately 0.5 km/sec were measured near the arcs, and the observed flow magnitude decreased markedly inside the arcs

    Liver Transplantation for Advanced Liver Disease with Alpha-1antitrypsin Deficiency

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    ALPHA-1-antitrypsin deficiency associated with chronic obstructive airway disease was recognized in 1963 by Laurell and Ericksson.1 In 1969, Sharp2 described the first cases of alpha-1-antitrypsin-deficiency disease in children with cirrhosis. Since then, this inborn error has been recognized as one of the more common factors in cirrhosis of infancy and childhood,3 including “neonatal hepatitis.”4 Alpha-1-antitrypsin is a glycoprotein that accounts for a major portion of the alpha-1 globulin fraction of the serum.5 It is responsible for approximately 90 per cent of the antitrypsin activity6 of the serum, and it also inhibits several other plasma enzymes, including plasmin,7 elastase,8 collagenase,9 and. © 1980, Massachusetts Medical Society. All rights reserved

    Chemical Equilibrium Abundances in Brown Dwarf and Extrasolar Giant Planet Atmospheres

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    We calculate detailed chemical abundance profiles for a variety of brown dwarf and extrasolar giant planet atmosphere models, focusing in particular on Gliese 229B, and derive the systematics of the changes in the dominant reservoirs of the major elements with altitude and temperature. We assume an Anders and Grevesse (1989) solar composition of 27 chemical elements and track 330 gas--phase species, including the monatomic forms of the elements, as well as about 120 condensates. We address the issue of the formation and composition of clouds in the cool atmospheres of substellar objects and explore the rain out and depletion of refractories. We conclude that the opacity of clouds of low--temperature (\le900 K), small--radius condensibles (specific chlorides and sulfides), may be responsible for the steep spectrum of Gliese 229B observed in the near infrared below 1 \mic. Furthermore, we assemble a temperature sequence of chemical transitions in substellar atmospheres that may be used to anchor and define a sequence of spectral types for substellar objects with Teff_{eff}s from \sim2200 K to \sim100 K.Comment: 57 pages total, LaTeX, 14 figures, 5 tables, also available in uuencoded, gzipped, and tarred form via anonymous ftp at www.astrophysics.arizona.edu (cd to pub/burrows/chem), submitted to Ap.

    Status and Harvests of Sandhill Cranes: Mid-Continent & Rocky Mountain Populations 2005

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    Annual indices to abundance of the Mid-Continent Population of Sandhill Cranes has been relatively stable since the early 1980s, compared to the increases that were recorded in the 1970s. The Central Platte River Valley, Nebraska spring index for 2005, uncorrected for visibility bias, was 412,000. The photo-corrected 3-year average for 2002-2004 was 363,167, which is within the established population-objective range of 343,000- 465,000 cranes. All Central Flyway states, except Nebraska, allowed crane hunting in portions of their respective states during 2004-05. About 9,300 hunters participated in these seasons, which was 12% higher than the number that participated in the previous year’s seasons. Hunters harvested 15,124 cranes in the U.S. portion of the Central Flyway during the 2004-05 seasons, which was 18% lower than the estimated harvest for the previous year. The retrieved harvest of Mid-Continent Population sandhill cranes in hunt areas for the Rocky Mountain Population of sandhill cranes (Arizona & New Mexico), Alaska, Canada, and Mexico combined was estimated at 14,528 during 2004-05. The preliminary estimate for the North American sport harvest, including crippling losses, was 33,847, which is 5% lower than the previous year’s estimate of 35,671. The long-term (1982-2004) trends for the Mid-Continent Population indicate that harvests have been increasing at a higher rate than population growth. The fall 2004 pre-migration survey estimate for the Rocky Mountain Population was 18,510, which was 5.5% lower than the previous year’s estimate of 19,523. The 3-year average for 2002-2004 is 18,945, which is within established population objectives of 17,000 - 21,000. Hunting seasons during 2004-05 in portions of Arizona, Idaho, Montana, New Mexico, Utah, and Wyoming, resulted in a harvest of 594 cranes, a 13% increase from the harvest of 528 the year before

    Wildlife Biologist, Division of Migratory Bird Management, U.S. Fish and Wildlife Service, Denver, Colorado

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    The abundance of the Mid-Continent Population of Sandhill Cranes has been relatively stable since the early 1980s, compared to the increases that were recorded in the 1970s. The Central Platte River Valley, Nebraska spring index for 2004, uncorrected for visibility bias, was 356,850. The photo-corrected 3-year average for 2001-2003 was 370,300, which is within the established population objective range of 343,000-465,000 cranes. All Central Flyway states, except Nebraska, allowed crane hunting in portions of their respective states during 2003- 04. About 7,700 hunters participated in these seasons, which was similar to the number that participated in the previous year’s seasons. Hunters harvested 18,527 in the Central Flyway during the 2003-04 seasons, which was 42% higher than the harvest for the previous year. The retrieved harvest in the Pacific Flyway, Canada, and Mexico combined was estimated at 13,109 during 2003-04. The preliminary estimate for the North American sport harvest, including crippling losses, was 35,706, which is 28% higher than the previous year’s estimate of 27,839 and the second highest harvest recorded. The long-term (1982-2000) trends for the Mid- Continent Population indicate that harvests have been increasing at a higher rate than population growth. The fall 2003 pre-migration survey estimate for the Rocky Mountain Population was 19,523, which was similar to the previous year’s estimate of 18,803. The 3-year average for 2001-2003 is 18,295, which is within established population objectives of 17,000 - 21,000. Hunting seasons during 2003-04 in portions of Arizona, Idaho, Montana, New Mexico, Utah, and Wyoming, resulted in a harvest of 528 cranes, a 17% decrease from the harvest of 639 the year before
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