934 research outputs found

    Glycocalyx production in teleosts [Translation from: Verhandlungen der Deutschen Zoologischen Gesellschaft, p.286, 1970]

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    Shielding the organism against harmful effects from the environment is one of the most important tasks of the outer covering of all animals. The epidermis of primarily aquatic organisms and the epithelia of organs which are exposed to water, such as the digestive or the urinary system, possess a film of glycoproteins and mucopolysaccharides, the glycocalyx. This short paper examines the relationship of the mucus cells with the glycocalyx

    Sensitivity to alpha-variation in ultracold atomic-scattering experiments

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    We present numerical calculations for cesium and mercury to estimate the sensitivity of the scattering length to the variation of the fine structure constant alpha. The method used follows ideas Chin and Flambaum [Phys. Rev. Lett. 96, 230801 (2006)], where the sensitivity to the variation of the electron to proton mass ratio, beta, was considered. We demonstrate that for heavy systems, the sensitivity to variation of alpha is of the same order of magnitude as to variation of beta. Near narrow Feshbach resonances the enhancement of the sensitivity may exceed nine orders of magnitude.Comment: 5 pages, 1 figur

    Enhanced Sensitivity to the Time Variation of the Fine-Structure Constant and mp/mem_p/m_e in Diatomic Molecules: A Closer Examination of Silicon Monobromide

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    Recently it was pointed out that transition frequencies in certain diatomic molecules have an enhanced sensitivity to variations in the fine-structure constant α\alpha and the proton-to-electron mass ratio mp/mem_p/m_e due to a near cancellation between the fine-structure and vibrational interval in a ground electronic multiplet [V.~V.~Flambaum and M.~G.~Kozlov, Phys. Rev. Lett.~{\bf 99}, 150801 (2007)]. One such molecule possessing this favorable quality is silicon monobromide. Here we take a closer examination of SiBr as a candidate for detecting variations in α\alpha and mp/mem_p/m_e. We analyze the rovibronic spectrum by employing the most accurate experimental data available in the literature and perform \emph{ab initio} calculations to determine the precise dependence of the spectrum on variations in α\alpha. Furthermore, we calculate the natural linewidths of the rovibronic levels, which place a fundamental limit on the accuracy to which variations may be determined.Comment: 8 pages, 2 figure

    Homogeneous Gold Catalysis through Relativistic Effects: Addition of Water to Propyne

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    In the catalytic addition of water to propyne the Au(III) catalyst is not stable under non-relativistic conditions and dissociates into a Au(I) compound and Cl2. This implies that one link in the chain of events in the catalytic cycle is broken and relativity may well be seen as the reason why Au(III) compounds are effective catalysts.Comment: 12 pages, 3 figures, 1 tabl

    The convergence of the ab-initio many-body expansion for the cohesive energy of solid mercury

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    A many-body expansion for mercury clusters of the form E = \sum_{i<j}\Delta \epsilon_{ij} + \sum_{i<j<k}\Delta \epsilon_{ijk} + ... \quad, does not converge smoothly with increasing cluster size towards the solid state. Even for smaller cluster sizes (up to n=6), where van der Waals forces still dominate, one observes bad convergence behaviour. For solid mercury the convergence of the many-body expansion can dramatically be improved by an incremental procedure within an embedded cluster approach. Here one adds the coupled cluster many-body electron correlation contributions of the embedded cluster to the bulk HF energy. In this way we obtain a cohesive energy (not corrected for zero-point vibration) of 0.79 eV in perfect agreement with the experimental value.Comment: 10 pages, 3 figures, accepted PR
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