1,104 research outputs found

    The Centre-Periphery Dialectics in Eastern Sicily Retail System. An Exploratory Research

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    This paper aims at scrutinizing from an historical perspective the deep trans-formations shaped by retail spaces and new consumption patterns challenging long-entrenched dichotomies, such as the centre-periphery one. In particular, the exploratory research explores the territorial reconfiguration of the main Eastern Sicily metropol-itan areas, Catania and Messina, from the lens of the retail geography, namely after the diffusion of new suburban retail formats which have completely upset deeply-rooted relations between urban core and suburban rings

    PAMELA and FERMI-LAT limits on the neutralino-chargino mass degeneracy

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    Searches for Dark Matter (DM) particles with indirect detection techniques have reached important milestones with the precise measurements of the anti-proton and gamma-ray spectra, notably by the PAMELA and FERMI-LAT experiments. While the gamma-ray results have been used to test the thermal Dark Matter hypothesis and constrain the Dark Matter annihilation cross section into Standard Model (SM) particles, the anti-proton flux measured by the PAMELA experiment remains relatively unexploited. Here we show that the latter can be used to set a constraint on the neutralino-chargino mass difference. To illustrate our point we use a Supersymmetric model in which the gauginos are light, the sfermions are heavy and the Lightest Supersymmetric Particle (LSP) is the neutralino. In this framework the W^+ W^- production is expected to be significant, thus leading to large anti-proton and gamma-ray fluxes. After determining a generic limit on the Dark Matter pair annihilation cross section into W^+ W^- from the anti-proton data only, we show that one can constrain scenarios in which the neutralino-chargino mass difference is as large as ~ 20 GeV for a mixed neutralino (and intermediate choices of the anti-proton propagation scheme). This result is consistent with the limit obtained by using the FERMI-LAT data. As a result, we can safely rule out the pure wino neutralino hypothesis if it is lighter than 450 GeV and constitutes all the Dark Matter.Comment: 22page

    The Casimir force on a surface with shallow nanoscale corrugations: Geometry and finite conductivity effects

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    We measure the Casimir force between a gold sphere and a silicon plate with nanoscale, rectangular corrugations with depth comparable to the separation between the surfaces. In the proximity force approximation (PFA), both the top and bottom surfaces of the corrugations contribute to the force, leading to a distance dependence that is distinct from a flat surface. The measured Casimir force is found to deviate from the PFA by up to 15%, in good agreement with calculations based on scattering theory that includes both geometry effects and the optical properties of the material
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