6,766 research outputs found

    Invariant measures on multimode quantum Gaussian states

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    We derive the invariant measure on the manifold of multimode quantum Gaussian states, induced by the Haar measure on the group of Gaussian unitary transformations. To this end, by introducing a bipartition of the system in two disjoint subsystems, we use a parameterization highlighting the role of nonlocal degrees of freedom -- the symplectic eigenvalues -- which characterize quantum entanglement across the given bipartition. A finite measure is then obtained by imposing a physically motivated energy constraint. By averaging over the local degrees of freedom we finally derive the invariant distribution of the symplectic eigenvalues in some cases of particular interest for applications in quantum optics and quantum information.Comment: 17 pages, comments are welcome. v2: presentation improved and typos corrected. Close to the published versio

    GRB Flares: UV/Optical Flaring (Paper I)

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    We present a new algorithm for the detection of flares in gamma-ray burst (GRB) light curves and use this algorithm to detect flares in the UV/optical. The algorithm makes use of the Bayesian Information Criterion (BIC) to analyze the residuals of the fitted light curve, removing all major features, and to determine the statistically best fit to the data by iteratively adding additional `breaks' to the light curve. These additional breaks represent the individual components of the detected flares: T_start, T_stop, and T_peak. We present the detection of 119 unique flaring periods detected by applying this algorithm to light curves taken from the Second Swift Ultraviolet/Optical Telescope (UVOT) GRB Afterglow Catalog. We analyzed 201 UVOT GRB light curves and found episodes of flaring in 68 of the light curves. For those light curves with flares, we find an average number of ~2 flares per GRB. Flaring is generally restricted to the first 1000 seconds of the afterglow, but can be observed and detected beyond 10^5 seconds. More than 80% of the flares detected are short in duration with Delta t/t of < 0.5. Flares were observed with flux ratios relative to the underlying light curve of between 0.04 to 55.42. Many of the strongest flares were also seen at greater than 1000 seconds after the burst.Comment: Submitted to ApJ. 20 pages (including 8 figures and 1 table

    Influence of the pressing system on pomegranate juice physical-chemical properties

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    Pomegranate juice has many health properties as the fruits contain anticarcinogenic, antimicrobial and antiviral compounds. Its consumption has greatly increased throughout the world in recent years due to the potential of its different components, polyphenols and anthocyanins among all. Many studies have been performed on the pomegranate juice yield demonstrating its influence on the organoleptic and physicochemical properties of the juice. Commercial pomegranate juice production involves pressing fruits procedures. As a consequence, there is a need to investigate the pressing machine types and optimization in order to achieve juice yield and enhance its health properties. The aim of this study was to assess the influence of the pressing systems on pomegranate juice yield and health properties after the extraction. Pomegranate fruits of the Wonderful One variety were manually harvested in November 2014 and mechanically processed to extract juice. Two different pressing systems were used. The first one was an hydraulic pressing machine where the fruits were put after being sliced in half; the second extraction method consisted in using a destemming machine for the entire fruit followed by a pneumatic press, typically applied in grape processing. The juices obtained with the two systems were analyzed and compared in order to identify the extraction performances and quantitatively identify the health care of the juice properties
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