718,980 research outputs found

    Space-frequency correlation of classical waves in disordered media: high-frequency and small scale asymptotics

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    Two-frequency radiative transfer (2f-RT) theory is developed for geometrical optics in random media. The space-frequency correlation is described by the two-frequency Wigner distribution (2f-WD) which satisfies a closed form equation, the two-frequency Wigner-Moyal equation. In the RT regime it is proved rigorously that 2f-WD satisfies a Fokker-Planck-like equation with complex-valued coefficients. By dimensional analysis 2f-RT equation yields the scaling behavior of three physical parameters: the spatial spread, the coherence length and the coherence bandwidth. The sub-transport-mean-free-path behavior is obtained in a closed form by analytically solving a paraxial 2f-RT equation

    Draft Genome Sequence of Fructophilic Lactobacillus florum.

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    Herein we report the first genome sequence for Lactobacillus florum. L. florum 2F was isolated from Valencia orange leaves and is fructophilic, like other strains of this species. The draft genome of L. florum 2F contains 1,261,842 bp with a G+C content of 41.5% in 46 contigs (≥500 bp)

    A theory of the strain-dependent critical field in Nb3Sn, based on anharmonic phonon generation

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    We propose a theory to explain the strain dependence of the critical properties in A15 superconductors. Starting from the strong-coupling formula for the critical temperature, and assuming that the strain sensitivity stems mostly from the electron-phonon alpha^2F function, we link the strain dependence of the critical properties to a widening of alpha^2F. This widening is attributed to the nonlinear generation of phonons, which takes place in the anharmonic deformation potential induced by the strain. Based on the theory of sum- and difference-frequency wave generation in nonlinear media, we obtain an explicit connection between the widening of alpha^2F and the anharmonic energy. The resulting model is fit to experimental datasets for Nb3Sn, and the anharmonic energy extracted from the fits is compared with first-principles calculations.Comment: 10 pages, 3 figure
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