16,793 research outputs found

    Remote sensing X-ray spectrometer

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    Spectrometer measures chemical composition of lunar rocks by remote sensing from orbit and senses lunar X-rays produced by interaction of solar X-rays and elements on the lunar surface. Instrument features high sensitivity, data handling system that accumulates and prepares data for telemetry, and automatic calibration

    Black Extended Objects, Naked Singularities and P-Branes

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    We treat the horizons of charged, dilaton black extended objects as quantum mechanical objects. We show that the S matrix for such an object can be written in terms of a p-brane-like action. The requirements of unitarity of the S matrix and positivity of the p-brane tension equivalent severely restrict the number of space-time dimensions and the allowed values of the dilaton parameter a. Generally, black objects transform at the extremal limit into p-branes.Comment: 9 pages, REVTE

    Comment about pion electro-production and the axial form factors

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    The claim by Haberzettl (Phys.Rev.Lett.85 (2000) 3576) that the axial form factor of the nucleon cannot be accessed through threshold pion electroproduction is unfounded

    Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae) in Northwestern Pennsylvania

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    A two-year emergence trap study of black flies at four sites in northwestern Pennsylvania yielded 1%3 individuals of nine species. The collections included Prosimulium mixtum, P. jU5cum, Stegapterna mutata, Simulium aureum, S. excisum (recorded for the first time from Pennsylvania), S. gauldingi, S. sp. nr. innacens, S. vittatum, and S. tuberasum. Species richness for all sites peaked during May. Emergence collections below a sewage plant effluent outfall represented fewer individuals and species than collections above the effluent outfall. Chromosomal analysis of supplementary larval collections revealed the IIIL-l and IS-7 sibling species of S. vittatum and the FG sibling of S. tuberasum

    An Energy-Minimization Finite-Element Approach for the Frank-Oseen Model of Nematic Liquid Crystals: Continuum and Discrete Analysis

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    This paper outlines an energy-minimization finite-element approach to the computational modeling of equilibrium configurations for nematic liquid crystals under free elastic effects. The method targets minimization of the system free energy based on the Frank-Oseen free-energy model. Solutions to the intermediate discretized free elastic linearizations are shown to exist generally and are unique under certain assumptions. This requires proving continuity, coercivity, and weak coercivity for the accompanying appropriate bilinear forms within a mixed finite-element framework. Error analysis demonstrates that the method constitutes a convergent scheme. Numerical experiments are performed for problems with a range of physical parameters as well as simple and patterned boundary conditions. The resulting algorithm accurately handles heterogeneous constant coefficients and effectively resolves configurations resulting from complicated boundary conditions relevant in ongoing research.Comment: 31 pages, 3 figures, 3 table

    High Temperature Expansion Study of the Nishimori multicritical Point in Two and Four Dimensions

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    We study the two and four dimensional Nishimori multicritical point via high temperature expansions for the ±J\pm J distribution, random-bond, Ising model. In 2d2d we estimate the the critical exponents along the Nishimori line to be γ=2.37±0.05\gamma=2.37\pm 0.05, ν=1.32±0.08\nu=1.32\pm 0.08. These, and earlier 3d3d estimates γ=1.80±0.15\gamma =1.80\pm 0.15, ν=0.85±0.08\nu=0.85\pm 0.08 are remarkably close to the critical exponents for percolation, which are known to be γ=43/18\gamma=43/18, ν=4/3\nu=4/3 in d=2d=2 and γ=1.805±0.02\gamma=1.805\pm0.02 and ν=0.875±0.008\nu=0.875\pm 0.008 in d=3d=3. However, the estimated 4d4d Nishimori exponents γ=1.80±0.15\gamma=1.80\pm 0.15, ν=1.0±0.1\nu=1.0\pm 0.1, are quite distinct from the 4d4d percolation results γ=1.435±0.015\gamma=1.435\pm 0.015, ν=0.678±0.05\nu=0.678\pm 0.05.Comment: 5 pages, RevTex, 3 postscript files; To appear in Physical Review

    Symmetry Breaking for Matter Coupled to Linearized Supergravity From the Perspective of the Current Supermultiplet

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    We consider a generic supersymmetric matter theory coupled to linearized supergravity, and analyze scenarios for spontaneous symmetry breaking in terms of vacuum expectation values of components of the current supermultiplet. When the vacuum expectation of the energy momentum tensor is zero, but the scalar current or pseudoscalar current gets an expectation, evaluation of the gravitino self energy using the supersymmetry current algebra shows that there is an induced gravitino mass term. The structure of this term generalizes the supergravity action with cosmological constant to theories with CP violation. When the vacuum expectation of the energy momentum tensor is nonzero, supersymmetry is broken; requiring cancellation of the cosmological constant gives the corresponding generalized gravitino mass formula.Comment: 11 page
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