19,004 research outputs found

    Scottish social survey data, past present and future:Does Scotland need its own data strategy?

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    The UK now has a National Data Strategy. In this paper we explore whether or not in addition Scotland needs its own specific data strategy. This paper is intended to be a ‘think piece’ or critical essay, the motivation being to encourage debate about Scottish social survey data. Post-devolution, with the emergence of new forms of governance and new institutional arrangements, the political desire to research Scotland in the 21st Century has been brought into sharper resolution. Social and economic life in Scotland shares both similarities and differences with life south of the border. It is important that these characteristics are correctly identified with empirical data rather than simply being assumed. Scotland is a small territory with a good social science tradition and a healthy research sector. There is an increasing amount of survey data collecting measures relating to social and economic life in Scotland. These include both United Kingdom or Great Britain based surveys with a Scottish component, and Scotland focussed surveys. In this paper we outline a number of key issues relating to Scottish social science data resources. We provide a number of critical recommendations for social science data collection in Scotland. Finally, we examine the potential benefits of a comprehensive data strategy

    M-Theory and Hypercharge

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    We discuss the possibility that the electro-weak and strong interactions arise as the low energy effective description of branes in M-theory. As a step towards constructing such a model we show how one can naturally obtain SU(N_1)\times SU(N_2)\times U(1) gauge theories from branes, including matter in the bi-fundamental representation of SU(N_1)\times SU(N_2) which are fractionally charged under U(1).Comment: 29 pages Phyzzx. Two figure

    N=2 Superfields and the M-Fivebrane

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    In this paper we provide a manifestly N=2 supersymmetric formulation of the M-fivebrane in the presence of threebrane solitons. The superspace form of four-dimensional effective equations for the threebranes are readily obtained and yield the complete Seiberg-Witten equations of motion for N=2 super-Yang-Mills. A particularly simple derivation is given by introducing an N=2 superfield generalisation of the Seiberg-Witten differential.Comment: 14 pages phyzzx. Added paragraph on the existence of a six-dimensional action. To appear in Phys. Lett.

    Partial inner product spaces: Some categorical aspects

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    We make explicit in terms of categories a number of statements from the theory of partial inner product spaces (PIP spaces) and operators on them. In particular, we construct sheaves and cosheaves of operators on certain PIP spaces of practical interest.Comment: 21 page

    The Threebrane Soliton of the M-Fivebrane

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    We discuss the supersymmetry algebra of the M theory fivebrane and obtain a new threebrane soliton preserving half of the six-dimensional supersymmetry. This solution is dimensionally reduced to various D-p-branes.Comment: 10 pages, phyzz

    A New Massive Type IIA Supergravity From Compactification

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    We consider the most general form for eleven dimensional supersymmetry compatible with on-shell superfields. This allows for the introduction of a conformal Spin(1,10) connection. In eleven dimensional Minkowski space this modification is trivial and can be removed by a field redefinition, however, upon compactification on S^1 it is possible to introduce a non-trivial `Wilson line'. The resulting ten dimensional supergravity has massive 1-form and 3-form potentials and a cosmological constant. This theory does not possess a supersymmetric eightbrane soliton but it does admit a supersymmetric non-static cosmological solution.Comment: 13 pages, phyzzx. The introduction is clarifed and a reference adde

    Branes and Calibrated Geometries

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    The fivebrane worldvolume theory in eleven dimensions is known to contain BPS threebrane solitons which can also be interpreted as a fivebrane whose worldvolume is wrapped around a Riemann surface. By considering configurations of intersecting fivebranes and hence intersecting threebrane solitons, we determine the Bogomol'nyi equations for more general BPS configurations. We obtain differential equations, generalising Cauchy-Riemann equations, which imply that the worldvolume of the fivebrane is wrapped around a calibrated geometry.Comment: Latex, 35 pages. References added, minor change

    Suppression of Giant Magnetoresistance by a superconducting contact

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    We predict that current perpendicular to the plane (CPP) giant magnetoresistance (GMR) in a phase-coherent magnetic multilayer is suppressed when one of the contacts is superconducting. This is a consequence of a superconductivity-induced magneto-resistive (SMR) effect, whereby the conductance of the ferromagnetically aligned state is drastically reduced by superconductivity. To demonstrate this effect, we compute the GMR ratio of clean (Cu/Co)_nCu and (Cu/Co)_nPb multilayers, described by an ab-initio spd tight binding Hamiltonian. By analyzing a simpler model with two orbitals per site, we also show that the suppression survives in the presence of elastic scattering by impurities.Comment: 5 pages, 4 figures. Submitted to PR
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