7,212 research outputs found

    Aerothermal test results from the first flight of the Pegasus air-launched space booster

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    A survey of temperature measurements at speeds through Mach 8.0 on the first flight of the Pegasus air-launched booster system is discussed. In addition, heating rates were derived from the temperature data obtained on the fuselage in the vicinity of the wing shock interaction. Sensors were distributed on the wing surfaces, leading edge, and on the wing-body fairing or fillet. Side-by-side evaluations were obtained for a variety of sensor installations. Details of the trajectory reconstruction through first-stage separation are provided. Given here are indepth descriptions of the sensor installations, temperature measurements, and derived heating rates along with interpretations of the results

    Study of cost/benefit tradeoffs for reducing the energy consumption of the commercial air transportation system

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    Economic studies were conducted for three general fuel conserving options: (1) improving fuel consumption characteristics of existing aircraft via retrofit modifications; (2) introducing fuel efficient derivations of existing production aircraft and/or introducing fuel efficient, current state-of-the-art new aircraft; and (3) introducing an advanced state-of-the-art turboprop airplane. These studies were designed to produce an optimum airline fleet mix for the years 1980, 1985 and 1990. The fleet selected accommodated a normal growth market by introducing somewhat larger aircraft while solving for maximum departure frequencies and a minimum load factor corresponding to a 15% investment hurdle rate. Fuel burnt per available-seat-mile flown would drop 22% from 1980 to 1990 due to the use of more fuel efficient aircraft designs, larger average aircraft size, and increased seating density. An inflight survey was taken to determine air traveler attitudes towards a new generation of advanced turboprops

    Optical Studies of Er-doped Yttrium Aluminium Garnet Phosphor Materials

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    The need for materials application in solid-state lasers, medical devices, and optoelectronic devices has made the investigation of ceramic materials of increasing importance. A detail study of the optical properties of rare earth element typically from luminescent materials when intentionally doped inside the host materials and in particular crystal (such as YAG) is reported for the photoluminescence, power and lifetime measurement. The rare-earth dopants usually form trivalent lanthanide ions and the energy transfer and optical transitions involved originate from 4f-4f transitions of the ions and between these states and the host material. In order to understand the energy transfer processes in more detail we need to better understand the accompanying optical processes that give rise to the emission they display and it is this that forms the focus of the work presented. Following this second (and higher) order processes are considered that lead to upconversion in erbium-doped yttrium aluminum garnet (Er:YAG) materials

    Structural Insights into Differences in Drug-binding Selectivity between Two Forms of Human Ī±1-Acid Glycoprotein Genetic Variants, the A and F1*S Forms

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    Human Ī±1-acid glycoprotein (hAGP) in serum functions as a carrier of basic drugs. In most individuals, hAGP exists as a mixture of two genetic variants, the F1*S and A variants, which bind drugs with different selectivities. We prepared a mutant of the A variant, C149R, and showed that its drug-binding properties were indistinguishable from those of the wild type. In this study, we determined the crystal structures of this mutant hAGP alone and complexed with disopyramide (DSP), amitriptyline (AMT), and the nonspecific drug chlorpromazine (CPZ). The crystal structures revealed that the drug-binding pocket on the A variant is located within an eight-stranded Ī²-barrel, similar to that found in the F1*S variant and other lipocalin family proteins. However, the binding region of the A variant is narrower than that of the F1*S variant. In the crystal structures of complexes with DSP and AMT, the two aromatic rings of each drug interact with Phe-49 and Phe-112 at the bottom of the binding pocket. Although the structure of CPZ is similar to those of DSP and AMT, its fused aromatic ring system, which is extended in length by the addition of a chlorine atom, appears to dictate an alternative mode of binding, which explains its nonselective binding to the F1*S and A variant hAGPs. Modeling experiments based on the co-crystal structures suggest that, in complexes of DSP, AMT, or CPZ with the F1*S variant, Phe-114 sterically hinders interactions with DSP and AMT, but not CPZ. Ā© 2011 by The American Society for Biochemistry and Molecular Biology, Inc

    Managing health worker migration: A qualitative study of the Philippine response to nurse brain drain

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    Background: The emigration of skilled nurses from the Philippines is an ongoing phenomenon that has impacted the quality and quantity of the nursing workforce, while strengthening the domestic economy through remittances. This study examines how the development of brain drain-responsive policies is driven by the effects of nurse migration and how such efforts aim to achieve mind-shifts among nurses, governing and regulatory bodies, and public and private institutions in the Philippines and worldwide. Methods:Interviews and focus group discussions were conducted to elicit exploratory perspectives on the policy response to nurse brain drain. Interviews with key informants from the nursing, labour and immigration sectors explored key themes behind the development of policies and programmes that respond to nurse migration. Focus group discussions were held with practising nurses to understand policy recipientsā€™ perspectives on nurse migration and policy. Results: Using the qualitative data, a thematic framework was created to conceptualize participantsā€™ perceptions of how nurse migration has driven the policy development process. The framework demonstrates that policymakers have recognised the complexity of the brain drain phenomenon and are crafting dynamic policies and programmes that work to shift domestic and global mindsets on nurse training, employment and recruitment. Conclusions: Development of responsive policy to Filipino nurse brain drain offers a glimpse into a domestic response to an increasingly prominent global issue. As a major source of professionals migrating abroad for employment, the Philippines has formalised efforts to manage nurse migration. Accordingly, the Philippine paradigm, summarised by the thematic framework presented in this paper, may act as an example for other countries that are experiencing similar shifts in healthcare worker employment due to migration

    CYCLICAL CONCENTRATION AND CONSOLIDATION IN BIOTECH R&D: A NEO-SCHUMPETERIAN MODEL

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    Over the past fifteen years, the agricultural biotechnology industry has exhibited cyclical behavior in concentration and consolidation. This paper provides a theoretical model of endogenous R&D, in which industry concentration exhibits cyclical behavior. The model also generates additional testable hypotheses, and policy implications.Industrial Organization, Research and Development/Tech Change/Emerging Technologies,

    Visual and Electronic Evaluations of Detached Strawberry Leaves Inoculated with \u3ci\u3eColletotrichum\u3c/i\u3e Species

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    Inoculation of detached strawberry leaves with Colletotrichum species may provide an accurate, rapid, non-destructive method of identifying anthracnose resistant germplasm. Two assessments of anthracnose disease severity were compared on detached strawberry leaves inoculated with Colletotrichum fragariae and C. gloeosporioides: a quantitative assessment made via computer-based image analysis and a visual assessment made by two independent raters. The image analysis provided a precise measurement of percent lesion area of infected leaves. There was a strong positive correlation between percent lesion area and the visual disease scores of the raters

    Plasma exchange and intravenous immunoglobulin for the periā€operative management of type 2 heparinā€induced thrombocytopaenia in a patient requiring urgent surgery for critical limb ischaemia

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    Summary: We report the case of a 61ā€yearā€old female who developed heparinā€induced thrombocytopaenia following treatment of a submassive pulmonary embolism, and who then required an above knee amputation for critical limb ischaemia. Heparinā€induced thrombocytopaenia is a rare, immuneā€mediated complication associated with an inā€hospital mortality rate of 10%. It is more common in surgical patients, with patients undergoing orthopaedic surgery more likely to develop it than patients undergoing cardiac surgery, but heparinā€dependent immunoglobulin G antibodies are more likely to be formed in the latter. Periā€operative management remains a challenge. Ideally, it is preferable to wait for the platelet count to improve; but in certain cases, surgery cannot be delayed. Heparinā€induced thrombocytopaenia is usually managed with direct thrombin inhibitors, such as argatroban and bivalirudin. Newer therapeutic modalities, such as plasmapheresis and intravenous immunoglobulin, as used in this case, can rapidly remove antibodies, but the certainty of evidence is low. Our case adds to the literature regarding the use of these modalities and highlights the multidisciplinary team approach required to manage such complex cases
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