3,253 research outputs found

    A new approach for shaping of dual-reflector antennas

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    The shaping of 2-D dual-reflector antenna systems to generate a prescribed distribution with uniform phase at the aperture of the second reflector is examined. This method is based on the geometrical nature of Cassegrain and Gregorian dual-reflector antennas. The method of syntheses satisfies the principles of geometrical optics which are the foundations of dual-reflector designs. Instead of setting up differential equations or heuristically designing the subreflector, a set of algebraic equations is formulated and solved numerically to obtain the desired surfaces. The caustics of the reflected rays from the subreflector can be obtained and examined. Several examples of 2-D dual-reflector shaping are shown to validate the study. Geometrical optics and physical optics are used to calculate the scattered fields from the reflectors

    Heterozygous mis-sense mutations in Prkcb as a critical determinant of anti-polysaccharide antibody formation

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    To identify rate-limiting steps in T cell-independent type 2 (TI-2) antibody production against polysaccharide antigens, we performed a genome-wide screen by immunizing several hundred pedigrees of C57BL/6 mice segregating ENU-induced mis-sense mutations. Two independent mutations, Tilcara and Untied, were isolated that semi-dominantly diminished antibody against polysaccharide but not protein antigens. Both mutations resulted from single amino acid substitutions within the kinase domain of Protein Kinase C Beta (PKCβ). In Tilcara, a Ser552>Pro mutation occurred in helix G, in close proximity to a docking site for the inhibitory N-terminal pseudosubstrate domain of the enzyme, resulting in almost complete loss of active, autophosphorylated PKCβI whereas the amount of alternatively spliced PKCβII protein was not markedly reduced. Circulating B cell subsets were normal and acute responses to BCR-stimulation such as CD25 induction and initiation of DNA synthesis were only measurably diminished in Tilcara homozygotes, whereas the fraction of cells that had divided multiple times was decreased to an intermediate degree in heterozygotes. These results, coupled with evidence of numerous mis-sense PRKCB mutations in the human genome, identify Prkcb as a genetically sensitive step likely to contribute substantially to population variability in anti-polysaccharide antibody levels

    Development of physical and mathematical models for the Porous Ceramic Tube Plant Nutrification System (PCTPNS)

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    A physical model of the Porous Ceramic Tube Plant Nutrification System (PCTPNS) was developed through microscopic observations of the tube surface under various operational conditions. In addition, a mathematical model of this system was developed which incorporated the effects of the applied suction pressure, surface tension, and gravitational forces as well as the porosity and physical dimensions of the tubes. The flow of liquid through the PCTPNS was thus characterized for non-biological situations. One of the key factors in the verification of these models is the accurate and rapid measurement of the 'wetness' or holding capacity of the ceramic tubes. This study evaluated a thermistor based moisture sensor device and recommendations for future research on alternative sensing devices are proposed. In addition, extensions of the physical and mathematical models to include the effects of plant physiology and growth are also discussed for future research

    RasGRP1 Transduces Low-Grade TCR Signals which Are Critical for T Cell Development, Homeostasis, and Differentiation

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    AbstractTwo important Ras-guanyl nucleotide exchange factors, Sos and RasGRP1, control Ras activation in thymocytes. However, the relative contribution of these two exchange factors to Ras/ERK activation and their resulting impact on positive and negative selection is unclear. We have produced two lines of RasGRP1−/− TCR transgenic mice to determine the effect of RasGRP1 in T cell development under conditions of defined TCR signaling. Our results demonstrate that RasGRP1 is crucial for thymocytes expressing weakly selecting TCRs whereas those that express stronger selecting TCRs are more effective at utilizing RasGRP1-independent mechanisms for ERK activation and positive selection. Analysis of RasGRP1−/− peripheral T cells also revealed hitherto unidentified functions of RasGRP1 in regulating T cell homeostasis and sustaining antigen-induced developmental programming

    Real-time information processing of environmental sensor network data using Bayesian Gaussian processes

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    In this article, we consider the problem faced by a sensor network operator who must infer, in real time, the value of some environmental parameter that is being monitored at discrete points in space and time by a sensor network. We describe a powerful and generic approach built upon an efficient multi-output Gaussian process that facilitates this information acquisition and processing. Our algorithm allows effective inference even with minimal domain knowledge, and we further introduce a formulation of Bayesian Monte Carlo to permit the principled management of the hyperparameters introduced by our flexible models. We demonstrate how our methods can be applied in cases where the data is delayed, intermittently missing, censored, and/or correlated. We validate our approach using data collected from three networks of weather sensors and show that it yields better inference performance than both conventional independent Gaussian processes and the Kalman filter. Finally, we show that our formalism efficiently reuses previous computations by following an online update procedure as new data sequentially arrives, and that this results in a four-fold increase in computational speed in the largest cases considered

    Numerical analysis of spray-dic modeling for fruit concentration drying process into powder based on computational fluid dynamic

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    The drying process is most popular preservation methods. It is important in producing the powder and natural dye by concentration fruit drying. Spray-DIC is one of the concentration techniques for drying process using the nozzle flow application in computational fluid dynamic. The mathematical modeling for drying process in this paper includes mass conservation and energy conservation of fruit concentration based on partial differential equation. The discretization of mathematical model will use the finite difference method with the initial and boundary conditions of nozzle flow application. The mathematical modeling computes numerical in sequential algorithm. Jacobi and Gauss-Seidel scheme will use to solve the linear system of mathematical modeling. The execution time, no of iteration, accuracy, root mean square error and maximum error are measured for investigating the numerical analysis. The results show the Gauss Seidel method is the alternative method compared to Jacobi method for solving the Spray-DIC modeling

    NOTATIONAL ANALYSIS OF INTERNATIONAL BADMINTON COMPETITIONS

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    Notational analysis of competitions is a widely used method for observing the playing patterns of many sports. An experiment was carried out to determine the playing tactics adopted by athletes in international badminton competitions. A total of 10 major competitions were recorded and the data was processed using a generic notational analysis software. The types of techniques used, the success and failure rates of the various shots were computed and compared using statistical methods of analysis. The results showed that the top three most popular shots used were Lift, Net and Clear. It was also found' that there were significant differences among the percentage of shots used in the three court areas as well, as the type of shots used by males and females

    2′,3,4,4′-Tetra­meth­oxy­chalcone

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    In the title compound [systematic name: 1-(2,4-dimethoxyphenyl)-3-(3,4-dimethoxyphenyl)prop-2-en-1-one], C19H20O5, the dihedral angle between the benzene rings is 26.88 (5)°. One of the meth­oxy groups is twisted slightly away from the plane [C—O—C—C torsion angle = −12.8 (3)°] while the others are almost co-planer [C—O—C—C torsion angles = −3.2 (3), 2.6 (3) and −3.6 (3)°]. The crystal packing is stabilized by inter­molecular C—H⋯O inter­actions. A weak intra­molecular C—H⋯O inter­action occurs
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