12,539 research outputs found

    Architecture and data processing alternatives for the tse computer. Volume 4: Image rotation using tse operations

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    The tse computer's capability of achieving image congruence between temporal and multiple images with misregistration due to rotational differences is reported. The coordinate transformations are obtained and a general algorithms is devised to perform image rotation using tse operations very efficiently. The details of this algorithm as well as its theoretical implications are presented. Step by step procedures of image registration are described in detail. Numerous examples are also employed to demonstrate the correctness and the effectiveness of the algorithms and conclusions and recommendations are made

    The Chern-Simons Coefficient in Supersymmetric Non-abelian Chern-Simons Higgs Theories

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    By taking into account the effect of the would be Chern-Simons term, we calculate the quantum correction to the Chern-Simons coefficient in supersymmetric Chern-Simons Higgs theories with matter fields in the fundamental representation of SU(n). Because of supersymmetry, the corrections in the symmetric and Higgs phases are identical. In particular, the correction is vanishing for N=3 supersymmetric Chern-Simons Higgs theories. The result should be quite general, and have important implication for the more interesting case when the Higgs is in the adjoint representation.Comment: more references and explanation about rgularization dpendence are included, 13 pages, 1 figure, latex with revte

    Signature of Schwinger's pair creation rate via radiation generated in graphene by strong electric current

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    Electron - hole pairs are copuously created by an applied electric field near the Dirac point in graphene or similar 2D electronic systems. It was shown recently that for sufficiently large electric fields and ballistic times the I-V characteristics become strongly nonlinear due to Schwinger's pair creation. Since there is no energy gap the radiation from the pairs' annihilation is enhanced. The spectrum of radiation is calculated. The angular and polarization dependence of the emitted photons with respect to the graphene sheet is quite distinctive. For very large currents the recombination rate becomes so large that it leads to the second Ohmic regime due to radiation friction.Comment: 9 pages, 7 figure

    Ballistic transport, chiral anomaly and emergence of the neutral electron - hole plasma in graphene

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    The process of coherent creation of particle - hole excitations by an electric field in graphene is quantitatively described using a dynamic "first quantized" approach. We calculate the evolution of current density, number of pairs and energy in ballistic regime using the tight binding model. The series in electric field strength EE up to third order in both DC and AC are calculated. We show how the physics far from the two Dirac points enters various physical quantities in linear response and how it is related to the chiral anomaly. The third harmonic generation and the imaginary part of conductivity are obtained. It is shown that at certain time scale tnlE1/2t_{nl}\propto E^{-1/2} the physical behaviour dramatically changes and the perturbation theory breaks down. Beyond the linear response physics is explored using an exact solution of the first quantized equations. While for small electric fields the I-V curve is linear characterized by the universal minimal resistivity σ=π/2(e2/h)\sigma =\pi /2(e^{2}/h)%, at t>tnlt>t_{nl} the conductivity grows fast. The copious pair creation (with rate E3/2E^{3/2}), analogous to Schwinger's electron - positron pair creation from vacuum in QED, leads to creation of the electron - hole plasma at ballistic times of order tnlt_{nl}. This process is terminated by a relaxational recombination.Comment: 15 pages, 5 figures

    SUSY QCD Corrections to Higgs Pair Production from Bottom Quark Fusion

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    We present a complete next-to-leading order (NLO) calculation for the total cross section for inclusive Higgs pair production via bottom-quark fusion at the CERN Large Hadron Collider (LHC) in the minimal supersymmetric standard model (MSSM) and the minimal supergravity model (mSUGRA). We emphasize the contributions of squark and gluino loops (SQCD) and the decoupling properties of our results for heavy squark and gluino masses. The enhanced couplings of the b quark to the Higgs bosons in supersymmetric models with large tanb yield large NLO SQCD corrections in some regions of parameter space.Comment: 24 pages, 10 figure

    Replica Placement on Bounded Treewidth Graphs

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    We consider the replica placement problem: given a graph with clients and nodes, place replicas on a minimum set of nodes to serve all the clients; each client is associated with a request and maximum distance that it can travel to get served and there is a maximum limit (capacity) on the amount of request a replica can serve. The problem falls under the general framework of capacitated set covering. It admits an O(\log n)-approximation and it is NP-hard to approximate within a factor of o(logn)o(\log n). We study the problem in terms of the treewidth tt of the graph and present an O(t)-approximation algorithm.Comment: An abridged version of this paper is to appear in the proceedings of WADS'1

    A proton-coupled conformational switch of Escherichia coli 5S ribosomal RNA.

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