12,643 research outputs found

    Conatraints on ΔG\Delta G from Prompt Photon plus Jet Production at HERA-N\vec{N}

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    The utility of prompt photon plus associated jet production for constraining the size and shape of the polarized gluon density of the proton ΔG\Delta G is examined at S=40\sqrt{S}=40 GeV, appropriate for the proposed HERA-N\vec{N} polarized pp\vec{p}\vec{p} collider experiment. The calculation is performed at next-to-leading order (O(ααs2\alpha\alpha_s^2)) in QCD. The reliability of the predictions are examined in some detail.Comment: 16 pages, 3 figure

    Global Research Report – South and East Asia

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    Global Research Report – South and East Asia by Jonathan Adams, David Pendlebury, Gordon Rogers & Martin Szomszor. Published by Institute for Scientific Information, Web of Science Group

    The almost alternating diagrams of the trivial knot

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    Bankwitz characterized an alternating diagram representing the trivial knot. A non-alternating diagram is called almost alternating if one crossing change makes the diagram alternating. We characterize an almost alternaing diagram representing the trivial knot. As a corollary we determine an unknotting number one alternating knot with a property that the unknotting operation can be done on its alternating diagram.Comment: 29 pages, 18 figure

    The Beginning of the End of the Anthropic Principle

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    We argue that if string theory as an approach to the fundamental laws of physics is correct, then there is almost no room for anthropic arguments in cosmology. The quark and lepton masses and interaction strengths are determined.Comment: 12 page

    Gaussian Process Kernels for Pattern Discovery and Extrapolation

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    Gaussian processes are rich distributions over functions, which provide a Bayesian nonparametric approach to smoothing and interpolation. We introduce simple closed form kernels that can be used with Gaussian processes to discover patterns and enable extrapolation. These kernels are derived by modeling a spectral density – the Fourier transform of a kernel – with a Gaussian mixture. The proposed kernels support a broad class of stationary covariances, but Gaussian process inference remains simple and analytic. We demonstrate the proposed kernels by discovering patterns and performing long range extrapolation on synthetic examples, as well as atmospheric CO2 trends and airline passenger data. We also show that it is possible to reconstruct several popular standard covariances within our framework.Engineering and Applied Science

    Engineering polymer informatics: Towards the computer-aided design of polymers

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    The computer-aided design of polymers is one of the holy grails of modern chemical informatics and of significant interest for a number of communities in polymer science. The paper outlines a vision for the in silico design of polymers and presents an information model for polymers based on modern semantic web technologies, thus laying the foundations for achieving the vision

    Strong Anisotropy in Liquid Water upon Librational Excitation using Terahertz Laser Fields

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    Tracking the excitation of water molecules in the homogeneous liquid is challenging due to the ultrafast dissipation of rotational excitation energy through the hydrogen-bonded network. Here we demonstrate strong transient anisotropy of liquid water through librational excitation using single-color pump-probe experiments at 12.3 THz. We deduce a third order response of chi^3 exceeding previously reported values in the optical range by three orders of magnitude. Using a theory that replaces the nonlinear response with a material response property amenable to molecular dynamics simulation, we show that the rotationally damped motion of water molecules in the librational band is resonantly driven at this frequency, which could explain the enhancement of the anisotropy in the liquid by the external Terahertz field. By addition of salt (MgSO4), the hydration water is instead dominated by the local electric field of the ions, resulting in reduction of water molecules that can be dynamically perturbed by THz pulses
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