3,378 research outputs found

    A model for the wind direction signature in the stokes smissin sector from the ocean surfaces at microwave frequencies

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    This paper presents a model of the Stokes emission vector from the ocean surface. The ocean surface is described as an ensemble of facets with Cox and Munk's (1954) Gram-Charlier slope distribution. The study discusses the impact of different up-wind and cross-wind rms slopes, skewness, peakedness, foam cover models and atmospheric effects on the azimuthal variation of the Stokes vector, as well as the limitations of the model. Simulation results compare favorably, both in mean value and azimuthal dependence, with SSM/I data at 53/spl deg/ incidence angle and with JPL's WINDRAD measurements at incidence angles from 30/spl deg/ to 65/spl deg/, and at wind speeds from 2.5 to 11 m/s.Peer ReviewedPostprint (published version

    Experimental Investigation of the Evolution of Gaussian Quantum Discord in an Open System

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    Gaussian quantum discord is a measure of quantum correlations in Gaussian systems. Using Gaussian discord we quantify the quantum correlations of a bipartite entangled state and a separable two-mode mixture of coherent states. We experimentally analyze the effect of noise addition and dissipation on Gaussian discord and show that the former noise degrades the discord while the latter noise for some states leads to an increase of the discord. In particular, we experimentally demonstrate the near-death of discord by noisy evolution and its revival through dissipation.Comment: 5 pages, 5 figure

    Influence of detector motion in entanglement measurements with photons

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    We investigate how the polarization correlations of entangled photons described by wave packets are modified when measured by moving detectors. For this purpose, we analyze the Clauser-Horne-Shimony-Holt Bell inequality as a function of the apparatus velocity. Our analysis is motivated by future experiments with entangled photons designed to use satellites. This is a first step towards the implementation of quantum information protocols in a global scale

    A model of the wind direction signature in the Stokes emission vector from the ocean surface at microwave frequencies

    Get PDF
    This paper presents a model of the Stokes emission vector from the ocean surface. The ocean surface is described as an ensemble of facets with Cox and Munk's (1954) Gram-Charlier slope distribution. The study discusses the impact of different up-wind and cross-wind rms slopes, skewness, peakedness, foam cover models and atmospheric effects on the azimuthal variation of the Stokes vector, as well as the limitations of the model. Simulation results compare favorably, both in mean value and azimuthal dependence, with SSM/I data at 53° incidence angle and with JPL's WINDRAD measurements at incidence angles from 30° to 65°, and at wind speeds from 2.5 to 11 m/s.Peer Reviewe

    Detection of small bowel tumors in endoscopic capsule images by modeling non-gaussianity of texture descriptors

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    This paper presents an approach to the automatic detection of small bowel tumors by processing endoscopic capsule images. The most significant texture information is selected by using wavelet processing and captured in the image domain from an appropriate synthesized image. Co-occurrence matrices are used to derive texture descriptors by modeling second order statistics of color image levels. These descriptors are then modeled by using third and fourth order moments in order to cope with distributions that tend to become non-Gaussian especially in some pathological cases. The proposed approach is supported by a classifier based on radial basis functions procedure for the characterization of the image regions along the video frames. The whole methodology has been applied on real data and shows that higher order moments can be effective in modeling capsule endoscopic images regarding tumor detection.Centre Algoritm

    Site specific spin dynamics in BaFe2As2: tuning the ground state by orbital differentiation

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    The role of orbital differentiation on the emergence of superconductivity in the Fe-based superconductors remains an open question to the scientific community. In this investigation, we employ a suitable microscopic spin probe technique, namely Electron Spin Resonance (ESR), to investigate this issue on selected chemically substituted BaFe2_{2}As2_{2} single crystals. As the spin-density wave (SDW) phase is suppressed, we observe a clear increase of the Fe 3dd bands anisotropy along with their localization at the FeAs plane. Such an increase of the planar orbital content interestingly occurs independently on the chemical substitution responsible for suppressing the SDW phase. As a consequence, the magnetic fluctuations combined with the resultant particular symmetry of the Fe 3dd bands are propitious ingredients to the emergence of superconductivity in this class of materials.Comment: 6 pages, 5 figure
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