9,085 research outputs found

    Asymptotic efficiency of two nonparametric competitors of Wilcoxon's two sample test

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    Asymptotic efficiency of two nonparametric competitors of Mann-Whitney-Wilcoxon U tes

    Storing and Querying Probabilistic XML Using a Probabilistic Relational DBMS

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    This work explores the feasibility of storing and querying probabilistic XML in a probabilistic relational database. Our approach is to adapt known techniques for mapping XML to relational data such that the possible worlds are preserved. We show that this approach can work for any XML-to-relational technique by adapting a representative schema-based (inlining) as well as a representative schemaless technique (XPath Accelerator). We investigate the maturity of probabilistic rela- tional databases for this task with experiments with one of the state-of- the-art systems, called Trio

    Torsional rigidity for cylinders with a Brownian fracture

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    We obtain bounds for the expected loss of torsional rigidity of a cylinder ΩL=(L/2,L/2)×ΩR3\Omega_L=(-L/2,L/2) \times \Omega\subset \R^3 of length LL due to a Brownian fracture that starts at a random point in ΩL,\Omega_L, and runs until the first time it exits ΩL\Omega_L. These bounds are expressed in terms of the geometry of the cross-section ΩR2\Omega \subset \R^2. It is shown that if Ω\Omega is a disc with radius RR, then in the limit as LL \rightarrow \infty the expected loss of torsional rigidity equals cR5cR^5 for some c(0,)c\in (0,\infty). We derive bounds for cc in terms of the expected Newtonian capacity of the trace of a Brownian path that starts at the centre of a ball in R3\R^3 with radius 1,1, and runs until the first time it exits this ball.Comment: 18 page

    Heat content and inradius for regions with a Brownian boundary

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    In this paper we consider β[0;s]\beta[0; s], Brownian motion of time length s>0s > 0, in mm-dimensional Euclidean space Rm\mathbb R^m and on the mm-dimensional torus Tm\mathbb T^m. We compute the expectation of (i) the heat content at time tt of Rmβ[0;s]\mathbb R^m\setminus \beta[0; s] for fixed ss and m=2,3m = 2,3 in the limit t0t \downarrow 0, when β[0;s]\beta[0; s] is kept at temperature 1 for all t>0t > 0 and Rmβ[0;s]\mathbb R^m\setminus \beta[0; s] has initial temperature 0, and (ii) the inradius of Rmβ[0;s]\mathbb R^m\setminus \beta[0; s] for m=2,3,m = 2,3,\cdots in the limit ss \rightarrow \infty.Comment: 13 page

    Stretched Exponential Relaxation in the Biased Random Voter Model

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    We study the relaxation properties of the voter model with i.i.d. random bias. We prove under mild condions that the disorder-averaged relaxation of this biased random voter model is faster than a stretched exponential with exponent d/(d+α)d/(d+\alpha), where 0<α20<\alpha\le 2 depends on the transition rates of the non-biased voter model. Under an additional assumption, we show that the above upper bound is optimal. The main ingredient of our proof is a result of Donsker and Varadhan (1979).Comment: 14 pages, AMS-LaTe

    'Subject to control': shifting geographies of race and labour in US sugar agroindustry, 1930-1950

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    This article analyses how processes of racialization and place making converged in south Florida as the region's sugar agroindustry shifted from a southern US to a Caribbean labour market. The article engages theoretically at the intersection of the literatures on the geographies of race and labour, paying particular attention to ideas about the role of the state in each. I argue that such an engagement not only enhances the collective analytical power of such approaches, but that it is also critical for understanding agroindustry labour practices in south Florida. The empirical materials used include historical documents, reports and publications of the US Government and the United States Sugar Corporation (USSC). The analysis shows how ideas of corporate paternalism and industrial managerialism promoted by USSC were melded to an agricultural enterprise embedded in the racism of the Jim Crow South and the history of plantation slavery. The contradictions between USSC's dependence on cheap labour disciplined by Jim Crow violence and its corporate paternalism would never be fully reconciled and ultimately would prove untenable. As a consequence, sugar industry investors in collaboration with state labour regulators reimagined the ideal cane worker, elaborating intraracial categories of black labour based on place of origin. As the geography of labour markets was rescaled to the international level, the primary mechanism of labour control shifted from Jim Crow to summary deportation of foreign black workers from the Caribbean. This study contributes to our understanding of how historic processes of racialization are bound together with the political and economic processes of regional agroindustrial development

    The renormalization transformation for two-type branching models

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    This paper studies countable systems of linearly and hierarchically interacting diffusions taking values in the positive quadrant. These systems arise in population dynamics for two types of individuals migrating between and interacting within colonies. Their large-scale space-time behavior can be studied by means of a renormalization program. This program, which has been carried out successfully in a number of other cases (mostly one-dimensional), is based on the construction and the analysis of a nonlinear renormalization transformation, acting on the diffusion function for the components of the system and connecting the evolution of successive block averages on successive time scales. We identify a general class of diffusion functions on the positive quadrant for which this renormalization transformation is well-defined and, subject to a conjecture on its boundary behavior, can be iterated. Within certain subclasses, we identify the fixed points for the transformation and investigate their domains of attraction. These domains of attraction constitute the universality classes of the system under space-time scaling.Comment: 48 pages, revised version, to appear in Ann. Inst. H. Poincare (B) Probab. Statis

    Interdisciplinary (retail) research: The business of geography and the geography of business

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    NoAt the 2005 British Academy of Management conference several well-known economic geographers, including Neil Wrigley, Gordon Clark, and Susan Christopherson, called for management researchers to engage with economic geographers on interrelated geographical and managerial issues in the study of (retail) firms. In this commentary we reflect upon the present geography -management interface.We begin by considering the term `interdisciplinary research' and its relationship to any management - geography interface. This is followed by a context-specific discussion of international retailing and the role of research on the retail transnational corporation (TNC) in developing an interdisciplinary agenda. This commentary represents an initial more business and management focused response to the call from geography academics for more/better interdisciplinary research at the geography - management interface
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