100 research outputs found

    Superfluid drag of two-species Bose-Einstein condensates in optical lattices

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    We study two-species Bose-Einstein condensates in quasi two-dimensional optical lattices of varying geometry and potential depth. Based on the numerically exact Bloch and Wannier functions obtained using the plane-wave expansion method, we quantify the drag (entrainment coupling) between the condensate components. This drag originates from the (short range) inter-species interaction and increases with the kinetic energy. As a result of the interplay between interaction and kinetic energy effects, the superfluid-drag coefficient shows a non-monotonic dependence on the lattice depth. To make contact with future experiments, we quantitatively investigate the drag for mass ratios corresponding to relevant atomic species.Comment: 6 pages, 4 figures. Accepted in its original form but minor changes have been don

    Metallic spin-glasses beyond mean-field: An approach to the impurity-concentration dependence of the freezing temperature

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    A relation between the freezing temperature (TgT^{}_{\rm g}) and the exchange couplings (JijJ^{}_{ij}) in metallic spin-glasses is derived, taking the spin-correlations (GijG^{}_{ij}) into account. This approach does not involve a disorder-average. The expansion of the correlations to first order in Jij/TgJ^{}_{ij}/T^{}_{\rm g} leads to the molecular-field result from Thouless-Anderson-Palmer. Employing the current theory of the spin-interaction in disordered metals, an equation for TgT^{}_{\rm g} as a function of the concentration of impurities is obtained, which reproduces the available data from {\sl Au}Fe, {\sl Ag}Mn, and {\sl Cu}Mn alloys well.Comment: 4 figures. This is a strongly revised version, where several aspects have been improved, and the equation for the freezing temperature has been refined. It is equivalent to the published version in J. Phys.: Condens. Matter 25 (2013) 13600

    A Novel Technology for the Imaging of Acidic Prostate Tumors by Positron Emission Tomography

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    Solid tumors often develop an acidic environment due to the Warburg effect. The effectiveness of diagnosis and therapy may therefore be enhanced by the design and use of pH-sensitive agents that target acidic tumors. Recently, a novel technology was introduced to target acidic tumors using pH low insertion peptide (pHLIP), a peptide that inserts across cell membranes as an α-helix when the extracellular pH (pHe) is acidic. In this study, we expanded the application of the pHLIP technology to include positron emission tomography imaging of the acidic environment in prostate tumors using 64Cu conjugated to the pHLIP (64Cu-DOTA-pHLIP). Studies showed that this construct avidly accumulated in LNCaP and PC-3 tumors, with higher uptake and retention in the LNCaP tumors. Uptake correlated with differences in the bulk pHe of PC-3 and LNCaP tumors measured in magnetic resonance spectroscopy experiments by the 31P chemical shift of the pHe marker 3-aminopropylphosphonate. This article introduces a novel class of noninvasive pH-selective positron emission tomography imaging agents and opens new research directions in the diagnosis of acidic solid tumors

    The TOEPLITZ package implementation guide

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    Remark on “Algorithm 535: The QZ Algorithm to Solve the Generalized Eigenvalue Problem”

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