55 research outputs found

    PAMELA results on the cosmic-ray antiproton flux from 60 MeV to 180 GeV in kinetic energy

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    The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray antiproton flux and the antiproton-to-proton flux ratio which extends previously published measurements down to 60 MeV and up to 180 GeV in kinetic energy. During 850 days of data acquisition approximately 1500 antiprotons were observed. The measurements are consistent with purely secondary production of antiprotons in the galaxy. More precise secondary production models are required for a complete interpretation of the results.Comment: 11 pages, 3 figures, 1 table. Accepted for publication in Physical Review Letter

    Unexpected changes in the oxic/anoxic interface in the Black Sea

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    THE Black Sea is the largest anoxic marine basin in the world today1. Below the layer of oxygenated surface water, hydrogen sulphide builds up to concentrations as high as 425 μM in the deep water down to a maximum depth of 2,200 m (ref. 2). The hydrographic regime is characterized by low-salinity surface water of river origin overlying high-salinity deep water of Mediterranean origin1,3. A steep pycnocline, centred at about 50 m is the primary physical barrier to mixing and is the origin of the stability of the anoxic (oxygen/hydrogen sulphide) interface. Here we report new observations, however, that indicate dramatic changes in the oceanographic characteristics of the anoxic interface of the Black Sea over decadal or shorter timescales. The anoxic, sulphide-containing interface has moved up in the water column since the last US cruises in 1969 and 1975. In addition, a suboxic zone overlays the sulphide-containing deep water. The expected overlap of oxygen and sulphide was not present. We believe that these observations result from horizontal mixing or flushing events that inject denser, saltier water into the relevant part of the water column. It is possible that man-made reduction in freshwater inflow into the Black Sea could cause these changes, although natural variability cannot be discounted. © 1989 Nature Publishing Group

    Mod-Ď• Convergence, II: Estimates on the Speed of Convergence

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    In this paper, we give estimates for the speed of convergence towards a limiting stable law in the recently introduced setting of mod-ϕ convergence. Namely, we define a notion of zone of control, closely related to mod-ϕ convergence, and we prove estimates of Berry–Esseen type under this hypothesis. Applications include: - the winding number of a planar Brownian motion; - classical approximations of stable laws by compound Poisson laws; - examples stemming from determinantal point processes (characteristic polynomials of random matrices and zeroes of random analytic functions); - sums of variables with an underlying dependency graph (for which we recover a result of Rinott, obtained by Stein’s method); - the magnetization in the d-dimensional Ising model; - and functionals of Markov chains
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