1,830,322 research outputs found

    Finite-Size Effects and Scaling for the Thermal QCD Deconfinement Phase Transition within the Exact Color-Singlet Partition Function

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    We study the finite-size effects for the thermal QCD Deconfinement Phase Transition (DPT), and use a numerical finite size scaling analysis to extract the scaling exponents characterizing its scaling behavior when approaching the thermodynamic limit. For this, we use a simple model of coexistence of hadronic gas and color-singlet Quark Gluon Plasma (QGP) phases in a finite volume. The Color-Singlet Partition Function (CSPF) of the QGP cannot be exactly calculated and is usually derived within the saddle point approximation. When we try to do calculations with such an approximate CSPF, a problem arises in the limit of small temperatures and/or volumes (VT3<<1), requiring then additional approximations if we want to carry out calculations. We propose in this work a new method for an accurate calculation of any quantity of the finite system, without explicitly calculating the CSPF itself and without any approximation. By probing the behavior of some useful thermodynamic response functions on the hole range of temperature, it turns out that in a finite size system, all singularities in the thermodynamic limit are smeared out and the transition point is shifted away. A numerical finite size scaling analysis of the obtained data allows us to determine the scaling exponents of the QCD DPT. Our results expressing the equality between their values and the space dimensionality is a consequence of the singularity characterizing a first order phase transition and agree very well with the predictions of other FSS theoretical approaches and with the results of both lattice QCD and Monte Carlo models calculations.Comment: 09 pages, 11 Postscript figure

    Near-threshold production of omega mesons in the pn -> d omega reaction

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    The first measurement of the p n -> d omega total cross section has been achieved at mean excess energies of Q = 28 and 57 MeV by using a deuterium cluster-jet target. The momentum of the fast deuteron was measured in the ANKE spectrometer at COSY-Juelich and that of the slow "spectator" proton p(sp) from the p d -> p(sp) d omega reaction in a silicon telescope placed close to the target. The cross sections lie above those measured for p p -> p p omega but seem to be below theoretical predictions.Comment: 7 pages, 8 figures; second approach to describe the background has been added; results changed insignificantly, EPJ in pres

    Three-party qutrit-state sharing

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    A three-party scheme for securely sharing an arbitrary unknown single-qutrit state is presented. Using a general Greenberger-Horne-Zeilinger (GHZ) state as the quantum channel among the three parties, the quantum information (i.e., the qutrit state) from the sender can be split in such a way that the information can be recovered if and only if both receivers collaborate. Moreover, the generation of the scheme to multi-party case is also sketched.Comment: 7 page

    Section 337 and National Treatment under GATT: A Proposal for Legislative Reform

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    This Article discusses the GATT panel reports on Section 337, the U.S. reaction to the GATT findings and possible amendments to Section 337 that would put the United States in compliance with its international obligations. Taking into account the difficult balancing act necessary to change Section 337 the authors attempt to take these requirements into account in suggesting ways out of the quandary in which the United States and its trading partners now find themselves

    Model reconstructions for the Si(337) orientation

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    Although unstable, the Si(337) orientation has been known to appear in diverse experimental situations such as the nanoscale faceting of Si(112), or in the case of miscutting a Si(113) surface. Various models for Si(337) have been proposed over time, which motivates a comprehensive study of the structure of this orientation. Such a study is undertaken in this article, where we report the results of a genetic algorithm optimization of the Si(337)-(2×1)(2\times 1) surface. The algorithm is coupled with a highly optimized empirical potential for silicon, which is used as an efficient way to build a set of possible Si(337) models; these structures are subsequently relaxed at the level of ab initio density functional methods. Using this procedure, we retrieve most of the (337) reconstructions proposed in previous works, as well as a number of novel ones.Comment: 5 figures (low res.); to appear in J. Appl. Phy

    Money Management by Low-Income Households: Earning, Spending, Saving, and Accessing Financial Services

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    Opening and maintaining a checking or savings account at a credit union or bank are crucial steps for establishing the kinds of relationships with financial institutions that lead to qualifying for credit and developing assets. An estimated 22.2 million households or 56 million adults in the U.S. did not have a bank account in 2002. The lack of a bank account is more pervasive among low -income families than higher income families: 83% of families without bank accounts earn less than 25,000peryear.Furthermore,asmanyas2225,000 per year. Furthermore, as many as 22% of low-income families -- more than 8.4 million families earning less than 25,000 -- do not have a checking or savings account. Families in the lowest income group are even less likely to have accounts. An estimated 29.1% of families with incomes in the lowest twentieth percentile (10,300orless)arewithoutaccounts,whichismorethanthreetimesthemedianof9.110,300 or less) are without accounts, which is more than three times the median of 9.1% for all families.Classifying households as either banked or unbanked is conventional in the literature on the use of financial services by low-income households. However, a continuum that encompasses banked, formerly banked, underbanked, marginally banked, aspiring to bank, and unbanked better characterizes the way low-income persons access the broad array of financial services available to them. For example, approximately one -half of those currently without a bank account had one in the past; people may have a bank account and still use alternative financial institutions such as check cashing outlets (CCOs), known as currency exchanges in the Chicago area; and 30% of persons without an account report some kind of ongoing relationship with a bank. In fact, the terms mainstream and fringe or alternative themselves depend on one's perspective. That is, what may be regarded as fringe or alternative in one community might be ordinary and mainstream in another.A bank account can be a vehicle for maintaining and accumulating savings. However, having an account does not ensure that account holders are able to save. For example, although an estimated 78% of families with an annual income less than 25,000 had bank accounts in 2001, 53.4% of this income group reported having saved in the previous year. For households in the lowest income quintile ($10,300 or less), the savings rate is 30.0%. Furthermore, the reasons for saving differ among income levels, with families at lower income levels saving for more immediate expenditures such as rent and holiday gifts, compared with the longer timeframe of savings by higher income groups for future expenditures such as children's education and retirement

    Hydromechanics of low-Reynolds-number flow. Part 2. Singularity method for Stokes flows

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    The present study furthcr explores the fundamental singular solutions for Stokes flow that can be useful for constructing solutions over a wide range of free-stream profiles and body shapes. The primary singularity is the Stokeslet, which is associated with a singular point force embedded in a Stokes flow. From its derivatives other fundamental singularities can be obtained, including rotlets, stresslets, potential doublets and higher-order poles derived from them. For treating interior Stokes-flow problems new fundamental solutions are introduced; they include the Stokeson and its derivatives, called the roton and stresson. These fundamental singularities are employed here to construct exact solutions to a number of exterior and interior Stokes-flow problems for several specific body shapes translating and rotating in a viscous fluid which may itself be providing a primary flow. The different primary flows considered here include the uniform stream, shear flows, parabolic profiles and extensional flows (hyperbolic profiles), while the body shapcs cover prolate spheroids, spheres and circular cylinders. The salient features of these exact solutions (all obtained in closed form) regarding the types of singularities required for the construction of a solution in each specific case, their distribution densities and the range of validity of the solution, which may depend on the characteristic Reynolds numbers and governing geometrical parameters, are discussed

    The history of written language disorders: reexamining Pitres’ case (1884) of pure agraphia

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    The first clinical description of pure agraphia was reported by the French neurologist Pitres in 1884. Pitres used the case study evidence to argue for modality-specific memory representations and the localization of writing. This article reviews Pitres’s contribution to the study of acquired writing disorders, the components of writing models and the cerebral localization which subserve writing, in light of the views entertained by his contemporaries and current authors. Although numerous cases have been reported throughout this century, the view that writing can be impaired while other language functions and motor activities remain intact is still challenged

    School self-evaluation: a response to the Byron Review

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    Students' Conceptions of Scale Regarding Groundwater

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    Provides pedagogical insight concerning learners' pre-conceptions and misconceptions about groundwater The resource being annotated is: http://www.dlese.org/dds/catalog_SERC-STARTINGPOINT-000-000-000-337.htm
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