303,746 research outputs found

    Microscopic and Macroscopic Stress with Gravitational and Rotational Forces

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    Many recent papers have questioned Irving and Kirkwood's atomistic expression for stress. In Irving and Kirkwood's approach both interatomic forces and atomic velocities contribute to stress. It is the velocity-dependent part that has been disputed. To help clarify this situation we investigate [1] a fluid in a gravitational field and [2] a steadily rotating solid. For both problems we choose conditions where the two stress contributions, potential and kinetic, are significant. The analytic force-balance solutions of both these problems agree very well with a smooth-particle interpretation of the atomistic Irving-Kirkwood stress tensor.Comment: Fifteen pages with seven figures, revised according to referees' suggestions at Physical Review E. See also Liu and Qiu's arXiv contribution 0810.080

    The ABC\u27s of Schizophrenia

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    SCHIZOPHRENIA GENESIS, THE ORIGINS OF MADNESS Irving I. Gottesman W.H. Freeman and Company, New York, 1991 296 pages, $14.95, paperbac

    “In fellowship of death”: Animals and Nonhuman Nature in Irving Layton’s Ecopoetics

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    Irving Layton is not usually considered a “nature poet,” yet his work often features careful observations of nonhuman nature. Jacob Bachinger’s ecocritical reading of a few of Irving Layton\u27s most frequently anthologized poems examines the underappreciated ecopoetic aspect of his work. Bachinger pays specific attention to a recurring theme in many of Layton\u27s best known poems, such as “The Bull Calf” and “A Tall Man Executes a Jig”—the poet’s examination of a dead or dying animal. Layton’s examination of the deaths of these animals exists on a continuum in which the poet moves from an antipastoral to a postpastoral position

    Boston University Choral Ensembles, October 19, 2013

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    This is the concert program of the Boston University Choral Ensembles performance on Saturday, October 19, 2013 at 8:00 p.m., at Marsh Chapel, 735 Commonwealth Avenue, Boston, Massachusetts. Works performed were Three Choruses from Alive in Wonderland by Irving Fine, A Jubilant Song by Norman Dello Joio, Design for October by Irving Fine, Liebes Walzer, op. 52 by Johannes Brahms, Selections from The Company of Heaven by Benjamin Britten, and Old Folks at Home and Oh! Susanne by Stephen Foster. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund

    The stable marriage problem with master preference lists

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    We study variants of the classical stable marriage problem in which the preferences of the men or the women, or both, are derived from a master preference list. This models real-world matching problems in which participants are ranked according to some objective criteria. The master list(s) may be strictly ordered, or may include ties, and the lists of individuals may involve ties and may include all, or just some, of the members of the opposite sex. In fact, ties are almost inevitable in the master list if the ranking is done on the basis of a scoring scheme with a relatively small range of distinct values. We show that many of the interesting variants of stable marriage that are NP-hard remain so under very severe restrictions involving the presence of master lists, but a number of special cases can be solved in polynomial time. Under this master list model, versions of the stable marriage problem that are already solvable in polynomial time typically yield to faster and/or simpler algorithms, giving rise to simple new structural characterisations of the solutions in these cases

    Searching for Irving Fisher

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    There is a long-standing debate as to whether the Fisher effect operated during the classical gold standard period. We break new ground on this question by developing a market-based measure of inflation expectations during the gold standard. We derive a measure of silver-gold inflation expectations using the interest-rate differential between Austrian silver and gold perpetuity bonds. Our use of the silver-gold interest rate differential is motivated by the fact that both gold and silver served as numeraires in the pre-WWI period, so that a change in the price of either precious metal would impact the prices of all goods and services. The empirical evidence suggests that silver-gold inflation expectations exhibited significant persistence at the weekly, monthly, and annual frequencies. Further, we find that there is a one-to-one relationship between silver-gold inflation expectations and the interest rate on Austrian perpetuity bonds that were denominated in paper currency. The analysis suggests the operation of a Fisher effect during the classical gold standard period

    Hard variants of stable marriage

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    The Stable Marriage Problem and its many variants have been widely studied in the literature (Gusfield and Irving, The Stable Marriage Problem: Structure and Algorithms, MIT Press, Cambridge, MA, 1989; Roth and Sotomayor, Two-sided matching: a study in game-theoretic modeling and analysis, Econometric Society Monographs, vol. 18, Cambridge University Press, Cambridge, 1990; Knuth, Stable Marriage and its Relation to Other Combinatorial Problems, CRM Proceedings and Lecture Notes, vol. 10, American Mathematical Society, Providence, RI, 1997), partly because of the inherent appeal of the problem, partly because of the elegance of the associated structures and algorithms, and partly because of important practical applications, such as the National Resident Matching Program (Roth, J. Political Economy 92(6) (1984) 991) and similar large-scale matching schemes. Here, we present the first comprehensive study of variants of the problem in which the preference lists of the participants are not necessarily complete and not necessarily totally ordered. We show that, under surprisingly restrictive assumptions, a number of these variants are hard, and hard to approximate. The key observation is that, in contrast to the case where preference lists are complete or strictly ordered (or both), a given problem instance may admit stable matchings of different sizes. In this setting, examples of problems that are hard are: finding a stable matching of maximum or minimum size, determining whether a given pair is stable––even if the indifference takes the form of ties on one side only, the ties are at the tails of lists, there is at most one tie per list, and each tie is of length 2; and finding, or approximating, both an `egalitarian' and a `minimum regret' stable matching. However, we give a 2-approximation algorithm for the problems of finding a stable matching of maximum or minimum size. We also discuss the significant implications of our results for practical matching schemes

    From Ichabod to Ebenezer

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    Excerpt: The notion of moving from Ichabod to Ebenezer may produce any of several images in our minds. We may meander mentally from Washington Irving\u27s gangly Ichabod Crane to Charles Dickens\u27s miserly Ebenezer Scrooge enjoying memories of their stories along the way

    Irving Fisher and the UIP Puzzle: Meeting the Expectations a Century Later

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    We review Irving Fisher’s seminal work on UIP and on the closely related equation linking interest rates and inflation. Like Fisher, we find that the failures of UIP are connected to individual episodes in which errors surrounding exchange rate expectations are persistent, but eventually transitory. We find considerable commonality in deviations from UIP and PPP, suggesting that both of these deviations are driven by a common factor. Using a dynamic latent factor model, we find that deviations from UIP are almost entirely due to expectational errors in exchange rates, rather than attributable to the risk premium; a result consistent with those reported by Fisher a century ago.exchange rates;PPP;interest rates;UIP;inflation;Irving Fisher
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