15,609 research outputs found

    Broken Promises: The Case of Mothers of Srebrenica vs. The State of the Netherlands

    Full text link
    Critical discourse analysis of the legal proceedings of the Mothers of Srebrenica case brought against the UN and the Dutch government. This analysis explores the nature of culpability and blame-making among international actors

    Total reaction cross sections from 141^{141}141Pr(α\alpha,α\alpha)141^{141}Pr elastic scattering and α\alpha-induced reaction cross sections at low energies

    Full text link
    Elastic scattering data for 141^{141}Pr(α\alpha,α\alpha)141^{141}Pr have been analyzed to derive a new energy-dependent local potential for the 141^{141}Pr-α\alpha system. This potential is used successfully to predict the cross section of the 141^{141}Pr(α\alpha,n)144^{144}Pm reaction at low energies where new experimental data have become available very recently. Contrary to various global potentials, this new potential is able to reproduce simultaneously elastic scattering data around and above the Coulomb barrier and reaction data below the Coulomb barrier for the 141^{141}Pr-α\alpha system. Reasons for the partial failure of the global potentials are explained by intrinsic properties of the scattering matrix and their variation with energy. The new local potential may become the basis for the construction of a new global α\alpha-nucleus potential.Comment: 12 pages, 8 figures, Phys. Rev. C, accepte

    The Effects of Clumping and Substructure on ICM Mass Measurements

    Get PDF
    We examine an ensemble of 48 simulated clusters to determine the effects of small-scale density fluctuations and large-scale substructure on X-ray measurements of the intracluster medium (ICM) mass. We measure RMS density fluctuations in the ICM which can be characterized by a mean mass-weighted clumping factor C = /^2 between 1.3 and 1.4 within a density contrast of 500 times the critical density. These fluctuations arise from the cluster history of accretion shocks and major mergers, and their presence enhances the cluster's luminosity relative to the smooth case. We expect, therefore, that ICM mass measurements utilizing models which assume uniform density at a given radius carry a bias of order sqrt(C) = 1.16. We verify this result by performing ICM mass measurements on X-ray images of the simulations and finding the expected level of bias. The varied cluster morphologies in our ensemble also allow us to investigate the effects of departures from spherical symmetry on our measurements. We find that the presence of large-scale substructure does not further bias the resulting gas mass unless it is pronounced enough to produce a second peak in the image of at least 1% the maximum surface brightness. We analyze the subset of images with no secondary peaks and find a bias of 9% and a Gaussian random error of 4% in the derived mass.Comment: To appear in ApJ

    Improving the Quality and Efficiency of the Medicare Program Through Coverage Policy

    Get PDF
    Outlines Medicare coverage and payment policy on new technologies and recommends changes that could help achieve the Triple Aim goals of enhancing the individual experience of care, improving population health, and reducing per capita costs of care

    Fragment Approach to Constrained Density Functional Theory Calculations using Daubechies Wavelets

    Full text link
    In a recent paper we presented a linear scaling Kohn-Sham density functional theory (DFT) code based on Daubechies wavelets, where a minimal set of localized support functions is optimized in situ and therefore adapted to the chemical properties of the molecular system. Thanks to the systematically controllable accuracy of the underlying basis set, this approach is able to provide an optimal contracted basis for a given system: accuracies for ground state energies and atomic forces are of the same quality as an uncontracted, cubic scaling approach. This basis set offers, by construction, a natural subset where the density matrix of the system can be projected. In this paper we demonstrate the flexibility of this minimal basis formalism in providing a basis set that can be reused as-is, i.e. without reoptimization, for charge-constrained DFT calculations within a fragment approach. Support functions, represented in the underlying wavelet grid, of the template fragments are roto-translated with high numerical precision to the required positions and used as projectors for the charge weight function. We demonstrate the interest of this approach to express highly precise and efficient calculations for preparing diabatic states and for the computational setup of systems in complex environments

    Lamb Shift of 3P and 4P states and the determination of α\alpha

    Get PDF
    The fine structure interval of P states in hydrogenlike systems can be determined theoretically with high precision, because the energy levels of P states are only slightly influenced by the structure of the nucleus. Therefore a measurement of the fine structure may serve as an excellent test of QED in bound systems or alternatively as a means of determining the fine structure constant α\alpha with very high precision. In this paper an improved analytic calculation of higher-order binding corrections to the one-loop self energy of 3P and 4P states in hydrogen-like systems with low nuclear charge number ZZ is presented. A comparison of the analytic results to the extrapolated numerical data for high ZZ ions serves as an independent test of the analytic evaluation. New theoretical values for the Lamb shift of the P states and for the fine structure splittings are given.Comment: 33 pages, LaTeX, 4 tables, 4 figure

    QED self-energy contribution to highly-excited atomic states

    Get PDF
    We present numerical values for the self-energy shifts predicted by QED (Quantum Electrodynamics) for hydrogenlike ions (nuclear charge 60Z11060 \le Z \le 110) with an electron in an n=3n=3, 4 or 5 level with high angular momentum (5/2j9/25/2\le j \le 9/2). Applications include predictions of precision transition energies and studies of the outer-shell structure of atoms and ions.Comment: 20 pages, 5 figure

    Two-Loop Bethe Logarithms

    Get PDF
    We calculate the two-loop Bethe logarithm correction to atomic energy levels in hydrogen-like systems. The two-loop Bethe logarithm is a low-energy quantum electrodynamic (QED) effect involving multiple summations over virtual excited atomic states. Although much smaller in absolute magnitude than the well-known one-loop Bethe logarithm, the two-loop analog is quite significant when compared to the current experimental accuracy of the 1S-2S transition: it contributes -8.19 and -0.84 kHz for the 1S and the 2S state, respectively. The two-loop Bethe logarithm has been the largest unknown correction to the hydrogen Lamb shift to date. Together with the ongoing measurement of the proton charge radius at the Paul Scherrer Institute its calculation will bring theoretical and experimental accuracy for the Lamb shift in atomic hydrogen to the level of 10^(-7).Comment: 4 pages, RevTe
    corecore