55,115 research outputs found

    Implications of the isotope effects on the magnetization, magnetic torque and susceptibility

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    We analyze the magnetization, magnetic torque and susceptibility data of La2-xSrxCu(16,18)O4 and YBa2(63,65)CuO7-x near Tc in terms of the universal 3D-XY scaling relations. It is shown that the isotope effect on Tc mirrors that on the anisotropy. Invoking the generic behavior of the anisotropy the doping dependence of the isotope effects on the critical properties, including Tc, correlation lengths and magnetic penetration depths are traced back to a change of the mobile carrier concentration.Comment: 5 pages, 3 figure

    Pressure and isotope effect on the anisotropy of MgB2_{2}

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    We analyze the data for the pressure and boron isotope effect on the temperature dependence of the magnetization near TcT_{c}. Invoking the universal scaling relation for the magnetization at fixed magnetic field it is shown that the relative shift of TcT_{c}, induced by pressure or boron isotope exchange, mirrors essentially that of the anisotropy. This uncovers a novel generic property of anisotropic type II superconductors, inexistent in the isotropic case. For MgB2_{2} it implies that the renormalization of the Fermi surface topology due to pressure or isotope exchange is dominated by a mechanism controlling the anisotropy.Comment: 7 pages, 3 figure

    Comment on "Spatio-temporal filling of missing points in geophysical data sets" by D. Kondrashov and M. Ghil, Nonlin. Processes Geophys., 13, 151–159, 2006

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    Kondrashov and Ghil (2006) (KG hereafter) describe a method for imputing missing values in incomplete datasets that can exploit both spatial and temporal covariability to estimate missing values from available values. Temporal covariability has not been exploited as widely as spatial covariability in imputing missing values in geophysical datasets, but, as KG show, doing so can improve estimates of missing values. However, there are several inaccuracies in KG’s paper. Since similar inaccuracies have surfaced in other recent papers, for example, in the literature on paleo-climate reconstructions, I would like to point them out here
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