14 research outputs found

    U(N) Instantons on N=1/2 superspace -- exact solution & geometry of moduli space

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    We construct the exact solution of one (anti)instanton in N=1/2 super Yang-Mills theory defined on non(anti)commutative superspace. We first identify N = 1/2 superconformal invariance as maximal spacetime symmetry. For gauge group U(2), SU(2) part of the solution is given by the standard (anti)instanton, but U(1) field strength also turns out nonzero. The solution is SO(4) rotationally symmetric. For gauge group U(N), in contrast to the U(2) case, we show that the entire U(N) part of the solution is deformed by non(anti)commutativity and fermion zero-modes. The solution is no longer rotationally symmetric; it is polarized into an axially symmetric configuration because of the underlying non(anti)commutativity. We compute the `information metric' of one (anti) instanton. We find that moduli space geometry is deformed from hyperbolic space (Euclidean anti-de Sitter space) in a way anticipated from reduced spacetime symmetry. Remarkably, the volume measure of the moduli space turns out to be independent of the non(anti)commutativity. Implications to D-branes in Ramond- Ramond flux background and Maldacena's gauge-gravity correspondence are discussed.Comment: 39 pages, 3 figures, JHEP style; v2. typos corrected + a paragraph adde

    Gauge Theory on Noncommutative Supersphere from Supermatrix Model

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    We construct a supermatrix model which has a classical solution representing the noncommutative (fuzzy) two-supersphere. Expanding supermatrices around the classical background, we obtain a gauge theory on a noncommutative superspace on sphere. This theory has osp(12)osp(1|2) supersymmetry and u(2L+12L)u(2L+1|2L) gauge symmetry. We also discuss a commutative limit of the model keeping radius of the supersphere fixed.Comment: 16 pages, Latex, typos corrected, references adde

    Business and Society in Japan and the United States

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    This essay is an extension of my recent book, The Embedded Corporation: Corporate Governance and Employment Relations in Japan and the United States. It considers some recent differences in Japanese and U.S. internal labor markets to do with decentralization, outsourcing, and intra-firm transfers. Then it elaborates an historical interpretation of how Japanese and U.S. companies are embedded in their societies despite overlap in their corporate structures and management philosophies. The essay closely by speculating on the future of corporate governance and employment relations in Japan and the United States, examining in particular the role of social norms

    Too much of a good thing : why it is bad to stimulate the beta cell to secrete insulin

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    In many countries, first- or second-line pharmacological treatment of patients with type 2 diabetes consists of sulfonylureas (such as glibenclamide [known as glyburide in the USA and Canada]), which stimulate the beta cell to secrete insulin. However, emerging evidence suggests that forcing the beta cell to secrete insulin at a time when it is struggling to cope with the demands of obesity and insulin resistance may accelerate its demise. Studies on families with persistent hyperinsulinaemic hypoglycaemia of infancy (PHHI), the primary defect of which is hypersecretion of insulin, have shown that overt diabetes can develop later in life despite normal insulin sensitivity. In addition, in vitro experiments have suggested that reducing insulin secretion from islets isolated from patients with diabetes can restore insulin pulsatility and improve function. This article will explore the hypothesis that forcing the beta cell to hypersecrete insulin may be counterproductive and lead to dysfunction and death via mechanisms that may involve the endoplasmic reticulum and oxidative stress. We suggest that, in diabetes, therapeutic approaches should be targeted towards relieving the demand on the beta cell to secrete insulin. <br /
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