15,589 research outputs found

    First Principles Simulations of Boron Diffusion in Graphite

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    Boron strongly modifies electronic and diffusion properties of graphite. We report the first ab initio study of boron interaction with the point defects in graphite, which includes structures, thermodynamics, and diffusion. A number of possible diffusion mechanisms of boron in graphite are suggested. We conclude that boron diffuses in graphite by a kick-out mechanism. This mechanism explains the common activation energy, but large magnitude difference, for the rate of boron diffusion parallel and perpendicular to the basal plane. © 2007 The American Physical Society

    Kvantno-elektrodinamičke pospravke za polarizirano Møllerovo raspršenje

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    Principal contributions to QED radiative effects for Moller scattering of polarized particles are investigated. Explicit formulae for the cross section of radiative effects are given in covariant form. A FORTRAN code based on exact expressions for radiative corrections to cross section was used to calculate the results. Detailed numerical analysis for cross sections as well as for polarization asymmetries is given.Istražuju se glavni doprinosi kvantno-elektrodinamičkih popravaka za Møllerovo raspršenje polariziranih čestica. Izlažu se podrobni ishodi računa za udarne presjeke i polarizacijske asimetrije

    Kvantno-elektrodinamičke pospravke za polarizirano Møllerovo raspršenje

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    Principal contributions to QED radiative effects for Moller scattering of polarized particles are investigated. Explicit formulae for the cross section of radiative effects are given in covariant form. A FORTRAN code based on exact expressions for radiative corrections to cross section was used to calculate the results. Detailed numerical analysis for cross sections as well as for polarization asymmetries is given.Istražuju se glavni doprinosi kvantno-elektrodinamičkih popravaka za Møllerovo raspršenje polariziranih čestica. Izlažu se podrobni ishodi računa za udarne presjeke i polarizacijske asimetrije

    Characterization of some aflatoxin-deficient mutants of Aspergillus parasiticus

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    Aflatoxins are polyketide secondary metabolites produced by isolates of Aspergillus flavus and A. parasiticus. Since 1960, when a wide toxic outbreak was associated with moldy feed contaminated with aflatoxins, many efforts have been concentrated on this topic because of both the carcinogenic properties of these mycotoxins, and the worldwide occurrence of aflatoxin-producing fungi in cereal, cereal products and other agricultural commodities

    MERRA-2: File Specification

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    The second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) is a NASA atmospheric reanalysis that begins in 1980. It replaces the original MERRA reanalysis (Rienecker et al., 2011) using an upgraded version of the Goddard Earth Observing System Model, Version 5 (GEOS-5) data assimilation system. The file collections for MERRA-2 are described in detail in this document, including some important changes from those of the MERRA dataset (Lucchesi, 2012)

    Quantum correlations versus Multisimultaneity: an experimental test

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    Multisimultaneity is a causal model of relativistic quantum physics which assigns a real time ordering to any set of events, much in the spirit of the pilot-wave picture. Contrary to standard quantum mechanics, it predicts a disappearance of the correlations in a Bell-type experiment when both analysers are in relative motion such that, each one in its own inertial reference frame, is first to select the output of the photons. We tested this prediction using acousto-optic modulators as moving beam-splitters and interferometers separated by 55 m. We didn't observe any disappearance of the correlations, thus refuting Multisimultaneity.Comment: 4 pages, 3 figures, RevTex 4 versio

    CMOS-3D smart imager architectures for feature detection

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    This paper reports a multi-layered smart image sensor architecture for feature extraction based on detection of interest points. The architecture is conceived for 3-D integrated circuit technologies consisting of two layers (tiers) plus memory. The top tier includes sensing and processing circuitry aimed to perform Gaussian filtering and generate Gaussian pyramids in fully concurrent way. The circuitry in this tier operates in mixed-signal domain. It embeds in-pixel correlated double sampling, a switched-capacitor network for Gaussian pyramid generation, analog memories and a comparator for in-pixel analog-to-digital conversion. This tier can be further split into two for improved resolution; one containing the sensors and another containing a capacitor per sensor plus the mixed-signal processing circuitry. Regarding the bottom tier, it embeds digital circuitry entitled for the calculation of Harris, Hessian, and difference-of-Gaussian detectors. The overall system can hence be configured by the user to detect interest points by using the algorithm out of these three better suited to practical applications. The paper describes the different kind of algorithms featured and the circuitry employed at top and bottom tiers. The Gaussian pyramid is implemented with a switched-capacitor network in less than 50 μs, outperforming more conventional solutions.Xunta de Galicia 10PXIB206037PRMinisterio de Ciencia e Innovación TEC2009-12686, IPT-2011-1625-430000Office of Naval Research N00014111031
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