2,725 research outputs found

    Looks Can Be Deceiving—A Comparison of Initial Public Offering Procedures Under Japanese and U.S. Securities Laws

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    In order to examine the divergent administration of statutes that are by their terms similar, the initial public offering procedures that a non-sovereign domestic issuer follows in the US and Japan are described

    Vasopressin

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    Antidiuretic hormone liberated the vertebrates from their aqueous environment, and permitted them to establish themselves on dry land. The combination of sensitive volume and osmoreceptors, a pituitary secretory apparatus which can vary its output from virtually zero to high levels in a short space of time, and receptor cells functioning in the countercurrent system of the renal medulla, has resulted in a water conservation system of great efficiency. The hormone rapidly alters the luminal membrane of receptor cells in the collecting tubule and collecting duct, increasing the permeability of these structures to water.1 The permeability of the collecting duct to urea and sodium is also increased.This review will be centered on the sequence of events that follows the attachment of vasopressin to its receptors in the distal nephron. This has become an area of intense activity since the discovery by Sutherland and his colleagues of the central role of cyclic AMP in the action of hormones [2]. The review will cover in brief much of the ground covered by the extensive review of Handler and OrlofT [3], emphasizing recent additions to the literature. It is regrettable that the important advances in our understanding of the synthesis and release of antidiuretic hormone cannot be included; the reader is referred to recent symposia and reviews in this area [4–6], as well as in the comparative physiology of water regulation [7] and the countercurrent system [8]

    Wavelets and Field Forecast Verification

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    Regulatory activity revealed by dynamic correlations in gene expression noise

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    Gene regulatory interactions are context dependent, active in some cellular states but not in others. Stochastic fluctuations, or 'noise', in gene expression propagate through active, but not inactive, regulatory links^(1,2). Thus, correlations in gene expression noise could provide a noninvasive means to probe the activity states of regulatory links. However, global, 'extrinsic', noise sources generate correlations even without direct regulatory links. Here we show that single-cell time-lapse microscopy, by revealing time lags due to regulation, can discriminate between active regulatory connections and extrinsic noise. We demonstrate this principle mathematically, using stochastic modeling, and experimentally, using simple synthetic gene circuits. We then use this approach to analyze dynamic noise correlations in the galactose metabolism genes of Escherichia coli. We find that the CRP-GalS-GalE feed-forward loop is inactive in standard conditions but can become active in a GalR mutant. These results show how noise can help analyze the context dependence of regulatory interactions in endogenous gene circuits

    Staircase polygons: moments of diagonal lengths and column heights

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    We consider staircase polygons, counted by perimeter and sums of k-th powers of their diagonal lengths, k being a positive integer. We derive limit distributions for these parameters in the limit of large perimeter and compare the results to Monte-Carlo simulations of self-avoiding polygons. We also analyse staircase polygons, counted by width and sums of powers of their column heights, and we apply our methods to related models of directed walks.Comment: 24 pages, 7 figures; to appear in proceedings of Counting Complexity: An International Workshop On Statistical Mechanics And Combinatorics, 10-15 July 2005, Queensland, Australi

    Pure point diffraction and cut and project schemes for measures: The smooth case

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    We present cut and project formalism based on measures and continuous weight functions of sufficiently fast decay. The emerging measures are strongly almost periodic. The corresponding dynamical systems are compact groups and homomorphic images of the underlying torus. In particular, they are strictly ergodic with pure point spectrum and continuous eigenfunctions. Their diffraction can be calculated explicitly. Our results cover and extend corresponding earlier results on dense Dirac combs and continuous weight functions with compact support. They also mark a clear difference in terms of factor maps between the case of continuous and non-continuous weight functions.Comment: 30 page
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