22,106 research outputs found

    Ground State Entropy of the Potts Antiferromagnet on Cyclic Strip Graphs

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    We present exact calculations of the zero-temperature partition function (chromatic polynomial) and the (exponent of the) ground-state entropy S0S_0 for the qq-state Potts antiferromagnet on families of cyclic and twisted cyclic (M\"obius) strip graphs composed of pp-sided polygons. Our results suggest a general rule concerning the maximal region in the complex qq plane to which one can analytically continue from the physical interval where S0>0S_0 > 0. The chromatic zeros and their accumulation set B{\cal B} exhibit the rather unusual property of including support for Re(q)<0Re(q) < 0 and provide further evidence for a relevant conjecture.Comment: 7 pages, Latex, 4 figs., J. Phys. A Lett., in pres

    The political economy of trade protection: the determinants and welfare impact of the 2002 US emergency steel safeguard measures

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    This paper analyses the political economy of trade protection in the context of the factors determining the US Emergency Safeguard Measures for steel imposed March 2002. The paper identifies several factors in addition to the official justification stated problems of global over-capacity and the penetration of imports in the US market, namely the continued failure to restructure poorly performing firms, failure of previous attempts at protection and the influence of the domestic steel lobby and short-term political gains to the Bush Administration of protectionist action. The paper also reviews several ex ante and ex post empirical studies of the impact of the steel Safeguards on the steel industry and downstream steel-consuming activities. All of these studies find that the costs of the Safeguard Measures outweighed their benefits in terms of aggregate GDP and employment as well as having an important redistributive impact. The paper provides a brief summary of the subsequent WTO steel case and the final resolution of the dispute. The evidence suggests that the steel Safeguards owed more to political expediency than justification for protection under the WTO rules.

    Trade dispute settlement mechanisms: the WTO dispute settlement understanding in the wake of the GATT

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    A critical feature of the GATT Uruguay Round negotiations was the establishment of a new and more effective system of dealing with international trade disputes, known as the WTO Dispute Settlement Understanding (DSU). The original GATT dispute settlement system comprised rudimentary remnants of a more thorough framework contained in the defunct Havana Charter of the International Trade Organization (ITO). By the time of the start of the Uruguay Round negotiations in Punta del Este in 1986, the effectiveness and credibility of the GATT dispute settlement system was being very seriously questioned. The primary reason for the increasing lack of confidence in the system was the propensity of GATT contracting countries to ignore the findings of Panels, resulting in a stalemate in a number of high profile trade disputes. Several trade disputes between the EU and the United States discussed were initiated under the GATT dispute settlement system but remained unresolved. These disputes became increasingly acrimonious as a direct consequence of the failure of the GATT system to enforce a satisfactory resolution. This paper provides an outline of the workings of the GATT and WTO dispute settlement systems underlie several recent trade disputes. The first two sections deal with the GATT system of settling trade disputes. The first details the key elements of the GATT dispute settlement system while the second considers its performance in resolving disputes. Section 3 outlines the origins of the WTO DSU and summarises its principal Articles. The WTO DSU is appraised on the basis of its first nine years of operation in Section 4 followed by a brief discussion of the key issues that have arisen from its operation. The final Section makes some concluding comments on the relative efficacy of the GATT and WTO dispute settlement systems.

    Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components Quarterly progress report, 1 Jul. - 30 Sep. 1969

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    Ecology and thermal inactivation of microbes in and on interplanetary space vehicle component

    Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components Quarterly progress report, 1 Apr. - 30 Jun. 1970

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    Ecology and thermal inactivation of microbes in and on interplanetary space vehicle component

    Ground State Entropy of Potts Antiferromagnets on Cyclic Polygon Chain Graphs

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    We present exact calculations of chromatic polynomials for families of cyclic graphs consisting of linked polygons, where the polygons may be adjacent or separated by a given number of bonds. From these we calculate the (exponential of the) ground state entropy, WW, for the q-state Potts model on these graphs in the limit of infinitely many vertices. A number of properties are proved concerning the continuous locus, B{\cal B}, of nonanalyticities in WW. Our results provide further evidence for a general rule concerning the maximal region in the complex q plane to which one can analytically continue from the physical interval where S0>0S_0 > 0.Comment: 27 pages, Latex, 17 figs. J. Phys. A, in pres

    Tool for use in lifting pin supported objects

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    A tool for use in lifting a pin-supported, electronic package mounted in juxtaposition with the surface of an electronic circuit board is described. The tool is configured to be received beneath a pin-supported package and is characterized by a manually operable linkage, including an elongated, rigid link is supported for axial reciprocation and a pivotal link pinned to the body and supported for oscillation induced in response to axial motion imparted to the rigid link. A lifting plate is pivotally coupled to the distal end of the pivotal link so that oscillatory motion imparted to the pivotal link serves to move the plate vertically for elevating the plate into lifting engagement with the electronic package positioned thereabove
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