2,710 research outputs found

    Prospects from systems serology research

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142338/1/imm12861.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142338/2/imm12861_am.pd

    Low Temperature Flux Growth of 2H-SiC and Beta-Gallium Oxide

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    We present brief overview of our study on the low temperature flux growth of two very important novel wide bandgap materials 2H-SiC and Beta-gallium oxide (Beta-Ga2O3). We have synthesized and grown 5 millimeter to 1 centimeter size single crystals of Beta-gallium oxide (Beta-Ga2O3). We used a flux and semi wet method to grow transparent good quality crystals. In the semi-wet method Ga2O3 was synthesized with starting gallium nitrate solution and urea as a nucleation agent. In the flux method we used tin and other metallic flux. This crystal was placed in an alumina crucible and temperature was raised above 1050 degrees Centigrade. After a time period of thirty hours, we observed prismatic and needle shaped crystals of gallium oxide. Scanning electron microscopic studies showed step growth morphology. Crystal was polished to measure the properties. Bandgap was measured 4.7electronvolts using the optical absorption curve. Another wide bandgap hexagonal 2H-SiC was grown by using Si-Al eutectic flux in the graphite crucible. We used slight AlN also as the impurity in the flux. The temperature was raised up to 1050 degrees Centigrade and slowly cooled to 850 degrees Centigrade. Preliminary characterization results of this material are also reported

    Sums over Graphs and Integration over Discrete Groupoids

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    We show that sums over graphs such as appear in the theory of Feynman diagrams can be seen as integrals over discrete groupoids. From this point of view, basic combinatorial formulas of the theory of Feynman diagrams can be interpreted as pull-back or push-forward formulas for integrals over suitable groupoids.Comment: 27 pages, 4 eps figures; LaTeX2e; uses Xy-Pic. Some ambiguities fixed, and several proofs simplifie

    Classical Lattice Gauge Fields with Hard Thermal Loops

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    We propose a formulation of the long-distance dynamics of gauge theories at finite temperature on a lattice in Minkowski space, including the effects of hard thermal loops on the dynamics of the long wavelength modes. Our approach is based on the dual classical limits of quantum fields as waves and particles in the infrared and ultraviolet limits, respectively. It exhibits manifest invariance under space-dependent lattice gauge transformations and conserves Gauss' law.Comment: 11 pages, plain latex file, with major revisions to include details on the algorith

    Ergodic Properties of Classical SU(2) Lattice Gauge Theory

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    We investigate the relationship between the Lyapunov exponents of periodic trajectories, the average and fluctuations of Lyapunov exponents of ergodic trajectories, and the ergodic autocorrelation time for the two-dimensional hyperbola billiard. We then study the fluctuation properties of the ergodic Lyapunov spectrum of classical SU(2) gauge theory on a lattice. Our results are consistent with the notion that this system is globally hyperbolic. Among the many powerful theorems applicable to such systems, we discuss one relating to the fluctuations in the entropy growth rate.Comment: 21 pages, 7 figure

    A novel use of honey's aggregation approach to the analysis of repertory grids

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    This paper examines and appraises a novel approach to generating shared group constructs through aggregative analysis: the application of Honey’s aggregation procedure to repertory grid technique (RGT) data. Revisiting Personal Construct Theory’s underlying premises and adopting a social constructivist epistemology, we argue that, whilst “implicit theories” of the world, elicited via RGT, are unique to individuals, the constructs on which they are founded may be shared collectively. Drawing on a study of workplace performance, we outline a protocol for this novel use of Honey’s (1979a; 1979b) approach demonstrating how it can be utilized to generate shared constructs inductively to facilitate theory building. We argue that, unlike other grid aggregation processes, the approach does not compromise data granularity, offering a useful augmentation to traditional idiographic approaches examining individual-level constructs only. This approach appears especially suited to addressing complex and implicit topics, where individuals struggle to convey thoughts and ideas

    Effect of Processing on Morphology of Hydroxyapatites: Bioactive Glasses and Crystalline Composites

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    Recent studies on multinary oxides for applications as laser hosts and high dielectric capacitors have shown that processing at high temperature provides glassy or crystalline materials based on thermal treatments and cooling rates. Since hydroxyapatites are now subject of great interests due to their bioactivity, interest in producing soft and hard materials with glassy and crystalline nature by processing parameters has become very important. Crystalline materials by using Bridgman, Czochralski and flux growth methods are costly and require huge investment. We have observed that even low temperature solidification in organic flux produced oriented fibers. This organic treated material has different characteristics than in situ oxide materials prepared by sintering and grain growth. Examples of phosphate and silicate-based systems will be presented to demonstrate soft and hard materials. Effect of TiO2 and other hardening elements will be also reported

    Enhanced immune activation linked to endotoxemia in HIV-1 seronegative MSM

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    This study assessed cellular and soluble markers of immune activation in HIV-1 seronegative MSM. MSM immune profiles were characterized by an increased expression of CD57 on T cells and endotoxemia. Endotoxin presence was linked to recent high-risk exposure and associated with elevated cytokine levels and decreased CD4+/CD8+ T cell ratios. Taken together, these data show elevated levels of inflammation linked to periods of endotoxemia resulting in a significantly different immune phenotype in a subset of MSM at a high risk of HIV-1 acquisition.National Institutes of Health (U.S.) (Grant P01 AI074415

    Design and Characteristics of Hydroxyapatites: Effect of Radiation

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    Hydroxyapatites single crystals have been investigated their applications as the laser host material. Czochralksi and flux growth methods have been utilized to achieve single crystals. Because of their bioactivities with tissues these have attracted interest for bone applications. For low temperature processing we have used several techniques. We utilized some organic melt and oriented the grains by the directional solidification method. This organic treated material has different characteristics than coarsened oxide materials. Our approach involved low temperature processing using nano-engineered powders of the material system MgO-Na2O-K2O-CaO-SrO-SiO2 and also borates were processed by sintering and grain growth. Our results indicate that substitution of calcium and strontium with some other elements such as gallium and magnesium have great potential to improve the mechanical properties of bones
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