6,735 research outputs found

    Dependence of shock-tube boundary layers on shock strength

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    Using familiar considerations of vorticity transport, the essential behavior of shock-tube boundary layers is explicitly exhibited; the nearly constant functions that cannot be calculated analytically are evaluated numerically and compared with Mirels' correlations

    Fast computation of MadGraph amplitudes on graphics processing unit (GPU)

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    Continuing our previous studies on QED and QCD processes, we use the graphics processing unit (GPU) for fast calculations of helicity amplitudes for general Standard Model (SM) processes. Additional HEGET codes to handle all SM interactions are introduced, as well assthe program MG2CUDA that converts arbitrary MadGraph generated HELAS amplitudess(FORTRAN) into HEGET codes in CUDA. We test all the codes by comparing amplitudes and cross sections for multi-jet srocesses at the LHC associated with production of single and double weak bosonss a top-quark pair, Higgs boson plus a weak boson or a top-quark pair, and multisle Higgs bosons via weak-boson fusion, where all the heavy particles are allowes to decay into light quarks and leptons with full spin correlations. All the helicity amplitudes computed by HEGET are found to agree with those comsuted by HELAS within the expected numerical accuracy, and the cross sections obsained by gBASES, a GPU version of the Monte Carlo integration program, agree wish those obtained by BASES (FORTRAN), as well as those obtained by MadGraph. The performance of GPU was over a factor of 10 faster than CPU for all processes except those with the highest number of jets.Comment: 37 pages, 12 figure

    Method for producing heat-resistant semi-inorganic compounds

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    The method for producing a heat resistant, semi-inorganic compound is discussed. Five examples in which various alcohols, phenols, and aromatic carbonic acids are used to test heat resistance and solubility are provided

    Organometalic carbosilane polymers containing vanadium and their preparation

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    The present invention concerns a new organometallic polymer material containing in part a vanadium-siloxane linkage (V-0-Si), which has excellent resistance to heat and oxidation and a high residue ratio after high temperature treatment in a non-oxidizing atmosphere, for example, nitrogen, argon, helium, ammonia, or hydrogen

    Magnification effect on the detection of primordial non-Gaussianity from photometric surveys

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    We present forecast results for constraining the primordial non-Gaussianity from photometric surveys through a large-scale enhancement of the galaxy clustering amplitude. In photometric surveys, the distribution of observed galaxies at high redshifts suffers from the gravitational-lensing magnification, which systematically alters the number density for magnitude-limited galaxy samples. We estimate size of the systematic bias in the best-fit cosmological parameters caused by the magnification effect, particularly focusing on the primordial non-Gaussianity. For upcoming deep and/or wide photometric surveys like HSC, DES and LSST, the best-fit value of the non-Gaussian parameter, fNL, obtained from the galaxy count data is highly biased, and the true values of fNL would typically go outside the 3-sigma error of the biased confidence region, if we ignore the magnification effect in the theoretical template of angular power spectrum. The additional information from cosmic shear data helps not only to improve the constraint, but also to reduce the systematic bias. As a result, the size of systematic bias on fNL would become small enough compared to the expected 1-sigma error for HSC and DES, but it would be still serious for deep surveys with z_m > 1.5, like LSST. Tomographic technique improves the constraint on fNL by a factor of 2-3 compared to the one without tomography, but the systematic bias would increase.Comment: 12 pages, 10 figure

    Infrared study of valence transition compound YbInCu4 using cleaved surfaces

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    Optical reflectivity R(w) of YbInCu4 single crystals has been measured across its first-order valence transition at T_v ~ 42 K, using both polished and cleaved surfaces. R(w) measured on cleaved surfaces Rc(w) was found much lower than that on polished surface Rp(w) over the entire infrared region. Upon cooling through T_v, Rc(w) showed a rapid change over a temperature range of less than 2 K, and showed only minor changes with further cooling. In contrast, Rp(w) showed much more gradual and continuous changes across T_v, similarly to previously reported data on polished surfaces. The present result on cleaved surfaces demonstrates that the microscopic electronic structures of YbInCu4 observed with infrared spectroscopy indeed undergo a sudden change upon the valence transition. The gradual temperature-evolution of Rp(w) is most likely due to the compositional and/or Yb-In site disorders caused by polishing.Comment: 4 pages, 4 figures, Fig.1(a) correcte
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