2,793 research outputs found

    Wind direction azimuthal signature in the stokes emission vector from the ocean surface at microwave frequencies

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    Includes bibliographical references (page 431).An ocean polarimetric emission model is presented. It is found that skewness and upwind/cross-wind rms slopes are responsible for the first and second azimuthal harmonic, respectively. Atmospheric effects contribute significantly at low wind speeds, and at horizontal polarization at certain observation angles. Simulation results compare favorably with reported JPL-WINDRAD measurements

    Black Branes in a Box: Hydrodynamics, Stability, and Criticality

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    We study the effective hydrodynamics of neutral black branes enclosed in a finite cylindrical cavity with Dirichlet boundary conditions. We focus on how the Gregory-Laflamme instability changes as we vary the cavity radius R. Fixing the metric at the cavity wall increases the rigidity of the black brane by hindering gradients of the redshift on the wall. In the effective fluid, this is reflected in the growth of the squared speed of sound. As a consequence, when the cavity is smaller than a critical radius the black brane becomes dynamically stable. The correlation with the change in thermodynamic stability is transparent in our approach. We compute the bulk and shear viscosities of the black brane and find that they do not run with R. We find mean-field theory critical exponents near the critical point.Comment: 23 pages, 3 figures. v2: added comments on first-order phase transitio

    M2-M5 blackfold funnels

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    We analyze the basic M2-M5 intersection in the supergravity regime using the blackfold approach. This approach allows us to recover the 1/4-BPS self-dual string soliton solution of Howe, Lambert and West as a three-funnel solution of an effective fivebrane worldvolume theory in a new regime, the regime of a large number of M2 and M5 branes. In addition, it allows us to discuss finite temperature effects for non-extremal self-dual string soliton solutions and wormhole solutions interpolating between stacks of M5 and anti-M5 branes. The purpose of this paper is to exhibit these solutions and their basic properties.Comment: 19 pages, 5 figures, harvmac; typo corrected in equation (3.19
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