22,396 research outputs found

    A Systems-Based Approach to the Identification of User/Infrastructure Interdependencies as a Precursor to Identifying Opportunities to Improve Infrastructure Project Value/Cost Ratios

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    The bulk of the investment needed for infrastructure renewal in the United Kingdom will have to come from private sector investors, who will require attractive value/cost ratios. Government recognises infrastructure interdependencies can help deliver these, but returns remain uncertain. New business models are required to overcome this problem, which take account of enterprise-centred infrastructure interdependencies (interdependencies between social and economic enterprises and the infrastructures they use). The complex and closely coupled nature of enterprise and infrastructure systems can stand in the way of identifying these interdependencies; however, model-based systems engineering techniques offer a framework for dealing with this complexity. This paper describes research that the iBUILD project is doing to develop a methodology for modelling the interdependencies between infrastructure and the enterprises that use it, as a precursor to identifying opportunities to improve infrastructure project value/cost ratios. The methodology involves: identifying the suite of policy, strategy and operational documents relating to the enterprise-of-interest; eliciting system data from the documents and integrating it to create an enterprise system model; and, generating N2 diagrams from the model to identify the interdependencies

    Vector form factor in K_l3 semileptonic decay with two flavors of dynamical domain-wall quarks

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    We calculate the vector form factor in K \to \pi l \nu semileptonic decays at zero momentum transfer f_+(0) from numerical simulations of two-flavor QCD on the lattice. Our simulations are carried out on 16^3 \times 32 at a lattice spacing of a \simeq 0.12 fm using a combination of the DBW2 gauge and the domain-wall quark actions, which possesses excellent chiral symmetry even at finite lattice spacings. The size of fifth dimension is set to L_s=12, which leads to a residual quark mass of a few MeV. Through a set of double ratios of correlation functions, the form factor calculated on the lattice is accurately interpolated to zero momentum transfer, and then is extrapolated to the physical quark mass. We obtain f_+(0)=0.968(9)(6), where the first error is statistical and the second is the systematic error due to the chiral extrapolation. Previous estimates based on a phenomenological model and chiral perturbation theory are consistent with our result. Combining with an average of the decay rate from recent experiments, our estimate of f_+(0) leads to the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V_{us}|=0.2245(27), which is consistent with CKM unitarity. These estimates of f_+(0) and |V_{us}| are subject to systematic uncertainties due to the finite lattice spacing and quenching of strange quarks, though nice consistency in f_+(0) with previous lattice calculations suggests that these errors are not large.Comment: 23 pages, 11 figures, 7 tables, RevTeX4; v3: one table added, results and conclusions unchanged, final version to appear in Phys.Rev.

    Chiral-logarithmic Corrections to the S and T Parameters in Higgsless Models

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    Recently, Higgsless models have proven to be viable alternatives to the Standard Model (SM) and supersymmetric models in describing the breaking of the electroweak symmetry. Whether extra-dimensional in nature or their deconstructed counterparts, the physical spectrum of these models typically consists of ``towers'' of massive vector gauge bosons which carry the same quantum numbers as the SM W and Z. In this paper, we calculate the one-loop, chiral-logarithmic corrections to the S and T parameters from the lightest (i.e. SM) and the next-to-lightest gauge bosons using a novel application of the Pinch Technique. We perform our calculation using generic Feynman rules with generic couplings such that our results can be applied to various models. To demonstrate how to use our results, we calculate the leading chiral-logarithmic corrections to the S and T parameters in the deconstructed three site Higgsless model. As we point out, however, our results are not exclusive to Higgsless models and may, in fact, be used to calculate the one-loop corrections from additional gauge bosons in models with fundamental (or composite) Higgs bosons.Comment: 45 pages, 15 figures, added references, analysis of three site model expanded to include delocalized fermion

    Very Merry Christmas

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    HQ. Co. 1st Bn. 365th Infantryhttps://dh.howard.edu/prom_greetings/1006/thumbnail.jp

    A Complete Atlas of HI Absorption toward HII Regions in the Southern Galactic Plane Survey (SGPS1)

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    We present a complete catalog of H I emission and absorption spectrum pairs, toward H II regions, detectable within the boundaries of the Southern Galactic Plane Survey (SGPS I), a total of 252 regions. The catalog is presented in graphical, numerical and summary formats. We demonstrate an application of this new dataset through an investigation of the locus of the Near 3kpc Arm.Comment: Accepted for publication by ApJS Feb 6, 2014. Data files and Figure Set (252 images) to appear in the on-line version of the journa
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