22,772 research outputs found

    Hydrogeology of Closed Basins and Deserts of South America, ERTS-1 Interpretations

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    Hydrogeology of closed basins and deserts of South America (Bolivia, Argentina, Chile, and Peru), ERTS-1 interpretation

    ERTS-1 image contributes to understanding of geologic structures related to Managua earthquake, 1972

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    ERTS-1 imaged the western portion of Nicaragua on December 24, 1972, one day after the central part of the city of Managua was devastated by a major earthquake which measured 5.6 on the Richter scale. ERTS-1 images reveal sets of lineaments (which may reflect fault systems) along any one of which movement could have taken place. One set includes a line of active volcanoes that parallels the coast and constitutes the southwestern edge of the Nicaraguan Depression, a regional graben which cuts obliquely across the Central American isthmus. This trend is offset approximately 10km in a right lateral geometric sense just west of the city of Managua. A parallel lineament, north of Lake Managua, marks the northeast edge of the graben. A second set, extends northward to northwestward from the mouth of the Rio Grande (Viejo) north of Lake Managua and can be projected southward across the lake to Managua. It is this set along which geometric offset of the volcanic lineament appears to have taken place

    Staticity Theorem for Higher Dimensional Generalized Einstein-Maxwell System

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    We derive formulas for variations of mass, angular momentum and canonical energy in Einstein (n-2)-gauge form field theory by means of the ADM formalism. Considering the initial data for the manifold with an interior boundary which has the topology of (n-2)-sphere we obtained the generalized first law of black hole thermodynamics. Supposing that a black hole evevt horizon comprisesw a bifurcation Killing horizon with a bifurcate surface we find that the solution is static in the exterior world, when the Killing timelike vector field is normal to the horizon and has vanishing electric or magnetic fields on static slices.Comment: 10 pages, REVTEX, to published in Phys.Rev. D1

    Renormalisation of gravitational self interaction for wiggly strings

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    It is shown that for any elastic string model with energy density UU and tension TT, the divergent contribution from gravitational self interaction can be allowed for by an action renormalisation proportional to (U−T)2(U-T)^2. This formula is applied to the important special case of a bare model of the transonic type (characterised by a constant value of the product UTUT) that represents the macroscopically averaged effect of shortwavelength wiggles on an underlying microscopic model of the Nambu-Goto type (characterised by U=TU=T).Comment: 11 pages, Latex; original 8 page version extended to include estimates of relevant orders of magnitude. To be published in Physical Review,

    Transonic Elastic Model for Wiggly Goto-Nambu String

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    The hitherto controversial proposition that a ``wiggly" Goto-Nambu cosmic string can be effectively represented by an elastic string model of exactly transonic type (with energy density UU inversely proportional to its tension TT) is shown to have a firm mathematical basis.Comment: 8 pages, plain TeX, no figure
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