81,173 research outputs found

    Intraplate deformation due to continental collisions: A numerical study of deformation in a thin viscous sheet

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    A model of crustal deformation from continental collision that involves the penetration of a rigid punch into a deformable sheet is investigated. A linear viscous flow law is used to compute the magnitude and rate of change of crustal thickness, the velocity of mass points, strain rates and their principal axes, modes of deformation, areal changes, and stress. In general, a free lateral boundary reduces the magnitude of changes in crustal thickening by allowing material to more readily escape the advancing punch. The shearing that occurs diagonally in front of the punch terminates in compression or extension depending on whether the lateral boundary is fixed or free. When the ratio of the diameter of the punch to that of the sheet exceeds one-third, the deformation is insenstive to the choice of lateral boundary conditions. When the punch is rigid with sharply defined edges, deformation is concentrated near the punch corners. With non-rigid punches, shearing results in deformation being concentrated near the center of the punch. Variations with respect to linearity and nonlinearity of flow are discussed

    Thermal breakdown of coherent backscattering: a case study of quantum duality

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    We investigate coherent backscattering of light by two harmonically trapped atoms in the light of quantitative quantum duality. Including recoil and Doppler shift close to an optical resonance, we calculate the interference visibility as well as the amount of which-path information, both for zero and finite temperature.Comment: published version with minor changes and an added figur

    Decoherence and dephasing in strongly driven colliding Bose-Einstein condensates

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    We report on a series of measurements of decoherence and wavepacket dephasing between two colliding, strongly coupled, identical Bose-Einstein condensates. We measure, in the strong excitation regime, a suppression of the mean-field shift, compared to the shift which is observed for a weak excitation. This suppression is explained by applying the Gross-Pitaevskii energy functional. By selectively counting only the non-decohered fraction in a time of flight image we observe oscillations for which both inhomogeneous and Doppler broadening are suppressed, in quantitative agreement with a full Gross-Pitaevskii equation simulation. If no post selection is used, the decoherence rate due to collisions can be extracted, and is in agreement with the local density average calculated rate.Comment: 4 pages, 5 figure

    Standardized Pearson type 3 density function area tables

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    Tables constituting extension of similar tables published in 1936 are presented in report form. Single and triple parameter gamma functions are discussed. Report tables should interest persons concerned with development and use of numerical analysis and evaluation methods
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