48,321 research outputs found

    Instantiation in Trope Theory

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    The concept of instantiation is realized differently across a variety of metaphysical theories. A certain realization of the concept in a given theory depends on what roles are specified and associated with the concept and its corresponding term as well as what entities are suited to fill those roles. In this paper, the classic realization of the concept of instantiation in a one-category ontology of abstract particulars or tropes is articulated in a novel way and defended against unaddressed objections

    Describing mixed spin-space entanglement of pure states of indistinguishable particles using an occupation number basis

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    Quantum mechanical entanglement is a resource for quantum computation, quantum teleportation, and quantum cryptography. The ability to quantify this resource correctly has thus become of great interest to those working in the field of quantum information theory. In this paper, we show that all existing entanglement measures but one fail important tests of fitness when applied to n particle, m site states of indistinguishable particles, where n,m>=2. The accepted method of measuring the entanglement of a bipartite system of distinguishable particles is to use the von Neumann entropy of the reduced density matrix of one half of the system. We show that expressing the full density matrix using a site-spin occupation number basis, and reducing with respect to that basis, gives an entanglement which meets all currently known fitness criteria for systems composed of either distinguishable or indistinguishable particles. We consider an output state from a previously published thought experiment, a state which is entangled in both spin and spatial degrees of freedom, and show that the site entropy measure gives the correct total entanglement. We also show how the spin-space entanglement transfer occurring within the apparatus can be understood in terms of the transfer of probability from single-occupancy to double-occupancy sectors of the density matrix.Comment: 2 figures; added Appendix A; added Figure 2; made changes to take account of v2 of quant-ph/0105120; some typos remove

    An Evening Spent with Bill van Zwet

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    Willem Rutger van Zwet was born in Leiden, the Netherlands, on March 31, 1934. He received his high school education at the Gymnasium Haganum in The Hague and obtained his Masters degree in Mathematics at the University of Leiden in 1959. After serving in the army for almost two years, he obtained his Ph.D. at the University of Amsterdam in 1964, with Jan Hemelrijk as advisor. In 1965, he was appointed Associate Professor of Statistics at the University of Leiden and promoted to Full Professor in 1968. He remained in Leiden until his retirement in 1999, while also serving as Associate Professor at the University of Oregon (1965), William Newman Professor at the University of North Carolina at Chapel Hill (1990--1996), frequent visitor and Miller Professor (1997) at the University of California at Berkeley, director of the Thomas Stieltjes Institute of Mathematics in the Netherlands (1992--1999), and founding director of the European research institute EURANDOM (1997--2000). At Leiden, he was Dean of the School of Mathematics and Natural Sciences (1982--1984). He served as chair of the scientific council and member of the board of the Mathematics Centre at Amsterdam (1983--1996) and the Leiden University Fund (1993--2005).Comment: Published in at http://dx.doi.org/10.1214/08-STS261 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Investigation looking at the repeatability of 20 Society of Master Saddlers (SMS) qualified saddle fitters’ observations during static saddle fit

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    Saddle fit is widely considered to be a crucial factor for the health and performance of riding horses; however, there have been no studies looking at the agreement between professionals who fit and assess saddles. The aim of the study was to determine the agreement between Society of Master Saddlers (SMSs) qualified saddle fitters when statically fitting a saddle following the SMS guidelines. Twenty SMS qualified saddle fitter volunteers were recruited via social media and asked to statically assess the fit of the saddle following the “7 points of saddle fit” guidelines of the SMS in 10 horses. Descriptive statistics and Fleiss Kappa (as a measure of agreement beyond chance) were used to determine agreement between fitters. Agreement varied from slight to substantial between the different saddle assessment criteria with the assessment of overall saddle fit resulting in a fair agreement of k = 0.32. Substantial agreement was found for saddle clearance front (k = 0.66), top (k = 0.78), and rear (k = 0.81). Fair agreement was found for clearance of the saddle—side (k = 0.28) and how the girth straps line up with girth groove (k = 0.31) and panel contact (k = 0.38). Slight agreement was found for tree width and length (k = 0.12) and tree length (k = 0.12). Horse height in some criteria affected agreement. Agreement varied between the standard criteria. In cases where it was difficult to visually evaluate saddle fit, agreement was lower. Further work should aim to standardize the criteria which had suboptimal agreement

    Observation of fine one-dimensionally disordered layers in silicon carbide

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    The improved resolution of synchrotron edge-topography is enabling thinner (less than 100 microns), silicon carbide crystals to be studied, and is providing a more detailed and wider database on polytype depth profiles. Fine long-period and one-dimensionally-disordered layers, 5-25 microns thick, can now be confidently resolved and are found to be very common features, often in association with high-defect density bands. These features are illustrated in this paper using three examples. A new long period polytype LPP (152H/456R) has been discovered and reported here for the first time

    Party finance reform as constitutional engineering? The effectiveness and unintended consequences of party finance reform in France and Britain

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    In both Britain and France, party funding was traditionally characterized by a laissez faire approach and a conspicuous lack of regulation. In France, this was tantamount to a 'legislative vacuum'. In the last two decades, however, both countries have sought to fundamentally reform their political finance regulation regimes. This prompted, in Britain, the Political Parties, Elections and Referendums Act 2000, and in France a bout of 'legislative incontinence' — profoundly transforming the political finance regime between 1988 and 1995. This article seeks to explore and compare the impacts of the reforms in each country in a bid to explain the unintended consequences of the alternative paths taken and the effectiveness of the new party finance regime in each country. It finds that constitutional engineering through party finance reform is a singularly inexact science, largely due to the imperfect nature of information, the limited predictability of cause and effect, and the constraining influence of non-party actors, such as the Constitutional Council in France, and the Electoral Commission in Britain

    A New Wideband, Fully Steerable, Decametric Array at Clark Lake

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    A fully steerable, decametric array for radio astronomy is under construction at the Clark Lake Radio Observatory near Borrego Springs, California. This array will be a T of 720 conical spiral antennas (teepee-shaped antennas, hence the array is called the TPT), 3.0 km by 1.8 km capable of operating between 15 and 125 MHz. Both its operating frequency and beam position will be adjustable in less than one millisecond, and the TPT will provide a 49-element picture around the central beam position for extended source observations. Considerable experience was gained in the operation of completed portions of the array, and successful operation of the final array is assured. The results are described of the tests which were conducted with the conical spirals, and the planned electronics and data processing systems are described
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