2,571 research outputs found

    Improving the efficiency of variational tensor network algorithms

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    We present several results relating to the contraction of generic tensor networks and discuss their application to the simulation of quantum many-body systems using variational approaches based upon tensor network states. Given a closed tensor network T\mathcal{T}, we prove that if the environment of a single tensor from the network can be evaluated with computational cost κ\kappa, then the environment of any other tensor from T\mathcal{T} can be evaluated with identical cost κ\kappa. Moreover, we describe how the set of all single tensor environments from T\mathcal{T} can be simultaneously evaluated with fixed cost 3κ3\kappa. The usefulness of these results, which are applicable to a variety of tensor network methods, is demonstrated for the optimization of a Multi-scale Entanglement Renormalization Ansatz (MERA) for the ground state of a 1D quantum system, where they are shown to substantially reduce the computation time.Comment: 12 pages, 8 figures, RevTex 4.1, includes reference implementation. Software updated to v1.02: Resolved two scenarios in which multienv would generate errors for valid input

    Descending Price Optimally Coordinates Search

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    Investigating potential purchases is often a substantial investment under uncertainty. Standard market designs, such as simultaneous or English auctions, compound this with uncertainty about the price a bidder will have to pay in order to win. As a result they tend to confuse the process of search both by leading to wasteful information acquisition on goods that have already found a good purchaser and by discouraging needed investigations of objects, potentially eliminating all gains from trade. In contrast, we show that the Dutch auction preserves all of its properties from a standard setting without information costs because it guarantees, at the time of information acquisition, a price at which the good can be purchased. Calibrations to start-up acquisition and timber auctions suggest that in practice the social losses through poor search coordination in standard formats are an order of magnitude or two larger than the (negligible) inefficiencies arising from ex-ante bidder asymmetries.Comment: JEL Classification: D44, D47, D82, D83. 117 pages, of which 74 are appendi

    John Burnett - A Social History of Housing, 1815-1985 (second edition).

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    Telluric current survey over two known geothermal areas

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    American fundamentalism and nuclear deterrence a critique

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    This paper is an attempt to deal with two trends which have recently received a great deal of attention. One trend is an increasing questioning of the role which nuclear deterrence plays in securing a better world for our own and future generations. The other trend is the rise of the New Christian Right and its mixing of religion and American patriotism. These two trends have come face to face in the New Christian Right’s emphasis on restoring American superiority in its relative position to the Soviet Union—a country which they believe is the source of a monolithic Communist threat. The efforts of the New Christian Right to deal with nuclear deterrence are applauded but not accepted as representing the final word on how the gospel message is to be applied to such issues. The analysis of the New Christian Right’s position focuses on several areas. These include the following: anthropology, history, faith and reason, and biblical interpretation. It is concluded that their attempt to absolutize American values and America’s need for nuclear superiority does not square with the prophetic voice of the gospel, which stands in judgment on all human points of view, systems and structures. Thus the Christian approach to nuclear deterrence involves not an absolute faith commitment to the defense of the American point of view, but an emphasis on dialogue with those communities which have endorsed values which are sometimes in opposition to these. Such a dialogue can be pursued in economic terms, striving to discover the strength and weaknesses of both Capitalism and Communism. This attempt affirms that truth is not limited to any one particular community and that, through dialogue, values which point towards global peace and justice can be affirmed

    Experimental improvement of flyash as a growth medium for plants through addition of selected solid wastes

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    Large quantities of coal are consumed in South Africa as a result of the generation of electricity and the manufacture of automotive fuel. A consequence of this was the production of more than 15 Mt of ash and associated coal combustion by-products in 1987 alone. This poses a large scale waste-disposal problem. Flyash, the major waste product is from South African coal sources, an alkaline, saline material the pozzolanic nature of which results in the formation of massive, compacted and cemented ash deposits which have significant environmental impacts. Efforts made to limit this impact by revegetation, in many locations throughout the world, have had limited success due to the mobility of phytotoxic concentrations of some elements, including As, B, Cr, Cu, Mo, Ni, S and Se. Flyash also has limited quantities of bioavailable Fe, Mn, P and Zn and these elemental limitations are associated with the alkaline nature of the flyash. Another element that is deficient, is N, it is unavailable in flyash as it is lost from coal during combustion. Aside from the chemical limitations to plant growth, the compacted nature results in low porosity which can limit plant available moisture. Plant root penetration is also impeded which limits nutrient uptake. The basis of this study was to incorporate other selected waste materials into the flyash to produce, by co-disposal, a combined waste material that is geochemically inert and a satisfactory plant growth medium. The ameliorants selected for inclusion in this study included interphase sulphur, a Vcontaminated waste sulphur product from the sulphur recovery plant at the SASOL' s Secunda petrochemical production facility and Catpoly, a spent catalyst consisting of phosphoric acidimpregnated diatomaceous earth, also obtained from SASOL's Secunda operation

    The Doctrine of Justification According to the Parable of the Merciless Servant (Matt 18)

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    It is an accepted maxim that theologia parabolica non est argumentativa. It is, thus, not accepted procedure to derive a doctrine from a parable. Yet the proposition of this thesis is to show how the doctrine of justification is related to this parable by demonstrating how God\u27s act of justifying men is described herein

    Laser-induced fluorescence study of the reaction F + I2 -> IF + I

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    The Relationship Between Personality as Measured by the Minnesota Multiphasic Personality Inventory and Interest as Measured by the Kuder Preference Record

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    Counselors frequently use batteries of psychological tests in helping students to select appropriate educational and occupational choices. The task of interpreting scores on a battery of tests to students is not at any time a simple undertaking. The trend toward emphasis on the importance of the relationship among the various scores in a battery of tests, has further complicated test interpretation. Vocational choice theories suggest an interrelationship between vocational interests and personality characteristics. They further suggest that different educational majors and occupations require different types of vocational interest and personality characteristics. Two tests, The Minnesota Multiphasic Personality Inventory (hereafter referred to as the MMPI) and the Kuder Preference Record-Vocational (hereafter referred to as the Kuder), are frequently used to help students make educational and occupational choices. To help counselors make better interpretations, a number of research studies, using the MMPI and Kuder to determine the relationship of measured interest to measured personality traits have been conducted. The results of these studies have tended to disagree. Some studies have found no significant relationships between the two variables; while others have found significant relationships. There have also been many research studies, using the MMPI and Kuder, to determine personality and interest differences among the different college majors. These studies, too, have disagreed. Because of these limitations, there appears to be a need for a more systematic and dependable method of establishing relationships among the MMPI and Kuder, and of interpreting the patterns which are formed by those relationships

    You Can\u27t Get There from Here: Movement SF and the Picaresque

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    This dissertation examines the crisis of authenticity in postmodern culture and argues that contemporary science fiction, specifically the subgenre of Movement SF, has evolved a unique answer to this crisis by adopting, perhaps spontaneously, the picaresque narrative structure. Postmodern fiction has a tenuous relationship with the issue of authenticity, such that the average postmodern subject is utterly without true authenticity at all, alternately victim to the socioeconomic conditions of his or her culture and to the elision of the self as a result of the homogenizing effects of advertising, television, etc. Postmodern SF also carries this bleak perception of the possibility of agency; William Gibson\u27s Sprawl and Bridge trilogies are rife with negations of human agency at the metaphorical hands of various aspects and incarnations of what Fredric Jameson terms the technological sublime. This dissertation puts forth the argument that a group of post-Eighties SF texts all participate in a spontaneous revival of the picaresque mode, using the picaresque journey and related motifs to re-authenticate subjects whose identity and agency are being erased by powerful social and economic forces exterior to and normally imperceptible by the individual. This dissertation is organized around three loosely connected parts. Part 1 attempts to define Movement SF by separating the various, often confusing marketing labels (such as cyberpunk, postcyberpunk, etc.) and extracting a cluster of core characteristics that have shaped the genre since its inception in the early 80s. Part 1 further examines how these core characteristics (or premises) of Movement SF provide fertile ground for picaresque narrative strategies. Part 2 describes in detail the picaresque as it appears in Movement SF, examining worldbuilding strategies, the persistence and evolution of tropes and motifs common to the traditional picaresque, and the generation of new tropes and motifs unique to Movement picaresques. Part 3 examines the spatial tactics used in Movement picaresque narratives to enable picaresque marginality in totalized, globalized environments. Furthermore, Part 3 examines the use of psychological plurality as an internal tactic to escape closed environments
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