13,931 research outputs found

    The Necessary And Sufficient Condition for Generalized Demixing

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    Demixing is the problem of identifying multiple structured signals from a superimposed observation. This work analyzes a general framework, based on convex optimization, for solving demixing problems. We present a new solution to determine whether or not a specific convex optimization problem built for generalized demixing is successful. This solution will also bring about the possibility to estimate the probability of success by the approximate kinematic formula

    Neutrino mixing in matter

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    Three-neutrino mixing in matter is studied through a set of evolution equations which are based on a rephasing invariant parametrization. Making use of the known properties of measured neutrino parameters, analytic, approximate, solutions are obtained. Their accuracy is confirmed by comparison with numerical integration of these equations. The results, when expressed in the elements squared of the mixing matrix, exhibit striking patterns as the matter density varies.Comment: Revised, 5 pages, 3 figures, references added

    New class of 3D topological insulator in double perovskite

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    We predict a new class of three-dimensional topological insulators (TIs) in which the spin-orbit coupling (SOC) can more effectively generate a large band gap at Γ\Gamma point. The band gap of conventional TI such as Bi2_2Se3_3 is mainly limited by two factors, the strength of SOC and, from electronic structure perspective, the band gap when SOC is absent. While the former is an atomic property, we find that the latter can be minimized in a generic rock-salt lattice model in which a stable crossing of bands {\it at} the Fermi level along with band character inversion occurs for a range of parameters in the absence of SOC. Thus, large-gap TI's or TI's comprised of lighter elements can be expected. In fact, we find by performing first-principle calculations that the model applies to a class of double perovskites A2_2BiXO6_6 (A = Ca, Sr, Ba; X = Br, I) and the band gap is predicted up to 0.55 eV. Besides, more detailed calculations considering realistic surface structure indicate that the Dirac cones are robust against the presence of dangling bond at the boundary with a specific termination.Comment: submitted; title changed and new references added; see DOI for published versio

    Pleiotropic Effects of Vitamin D in Kidney Disease

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    Vitamin D is metabolized in the liver and kidneys and then converted to the active form, 1.25-dihydroxyvitamin D [1.25(OH)2D]. Chronic kidney disease patients usually lack both 25-hydroxyvitamin D [25(OH)D] and 1.25(OH)2D due to impaired renal function and 1α-hydroxylase deficiency. Chronic kidney disease patients have a high incidence of cardiovascular and infectious morbidities. Increasing evidence indicates a relationship between vitamin D deficiency and cardiovascular and infectious mortality risks. Vitamin D may have significant biological effects beyond its traditional roles on mineral and bone metabolism. Many extrarenal cells have the capability to produce local active 1.25(OH)2D in an intracrine or paracrine fashion. Vitamin D has a significant association with nonskeletal diseases, such as immunodeficiency, metabolic syndrome, insulin resistance, diabetes, hyperlipidemia, cardiovascular disease, proteinuria, and acute kidney injury. This article aims to review and summarize the pleiotropic effects of vitamin D in patients with kidney disease, particularly the immunological, metabolic, cardiovascular, and renal effects

    The Impact of Big Data Analytics Use on Supply Chain Performance --- Efficiency and Adaptability as Mediators

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    This paper develops a conceptual model to examine how big data analysis use affect supply chain performance in an omnichannel. A research model is developed which comprises 4 constructs and 4 research hypotheses, the efficiency and adaptability as mediating constructs. The model is tested on data collected from 245 top manufacturing firms in Taiwan, using structural equation modeling. The research findings highlight the importance of efficiency and adaptability as mediators for ensuring supply chain performance by reinforcing big data analytics use
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