3,318 research outputs found

    Reconnaissance excavations on early historic fortifications and other royal sites in Scotland, 1974-84: 3, excavations at Dundurn, Strathearn, Perthshire

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    As part of a long-term programme of research on historically documented fortifications, excavations were carried out in 1976-77 at Dundurn, Strathearn, principally on the defences. A complicated sequence, spanning the sixth to the ninth centuries AD, was revealed in the citadel and encircling terrace rampart. The printed report gives a synthesis of the excavation results, and discusses the classification of hierarchically-organized forts and the material culture and economy of Dundurn

    Universal behavior of quantum Green's functions

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    We consider a general one-particle Hamiltonian H = - \Delta_r + u(r) defined in a d-dimensional domain. The object of interest is the time-independent Green function G_z(r,r') = . Recently, in one dimension (1D), the Green's function problem was solved explicitly in inverse form, with diagonal elements of Green's function as prescribed variables. The first aim of this paper is to extract from the 1D inverse solution such information about Green's function which cannot be deduced directly from its definition. Among others, this information involves universal, i.e. u(r)-independent, behavior of Green's function close to the domain boundary. The second aim is to extend the inverse formalism to higher dimensions, especially to 3D, and to derive the universal form of Green's function for various shapes of the confining domain boundary.Comment: 46 pages, the shortened version submitted to J. Math. Phy

    Normal state properties of high angle grain boundaries in (Y,Ca)Ba2Cu3O7-delta

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    By lithographically fabricating an optimised Wheatstone bridge geometry, we have been able to make accurate measurements of the resistance of grain boundaries in Y1-xCaxBa2Cu3O7-d between the superconducting transition temperature, Tc, and room temperature. Below Tc the normal state properties were assessed by applying sufficiently high currents. The behaviour of the grain boundary resistance versus temperature and of the conductance versus voltage are discussed in the framework charge transport through a tunnel barrier. The influence of misorientation angle, oxygen content, and calcium doping on the normal state properties is related to changes of the height and shape of the grain boundary potential barrier.Comment: 17 pages, 1 table, 5 figures, submitted to PR
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