663 research outputs found

    High-momentum proton removal from 16O and the (e,e'p) cross section

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    The cross section for the removal of high-momentum protons from 16O is calculated for high missing energies. The admixture of high-momentum nucleons in the 16O ground state is obtained by calculating the single-hole spectral function directly in the finite nucleus with the inclusion of short-range and tensor correlations induced by a realistic meson-exchange interaction. The presence of high-momentum nucleons in the transition to final states in 15N at 60-100 MeV missing energy is converted to the coincidence cross section for the (e,e'p) reaction by including the coupling to the electromagnetic probe and the final state interactions of the outgoing proton in the same way as in the standard analysis of the experimental data. Detectable cross sections for the removal of a single proton at these high missing energies are obtained which are considerably larger at higher missing momentum than the corresponding cross sections for the p-wave quasihole transitions. Cross sections for these quasihole transitions are compared with the most recent experimental data available.Comment: 26 RevTex pages, 7 ps figure

    Microoptical Realization of Arrays of Selectively Addressable Dipole Traps: A Scalable Configuration for Quantum Computation with Atomic Qubits

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    We experimentally demonstrate novel structures for the realisation of registers of atomic qubits: We trap neutral atoms in one and two-dimensional arrays of far-detuned dipole traps obtained by focusing a red-detuned laser beam with a microfabricated array of microlenses. We are able to selectively address individual trap sites due to their large lateral separation of 125 mu m. We initialize and read out different internal states for the individual sites. We also create two interleaved sets of trap arrays with adjustable separation, as required for many proposed implementations of quantum gate operations

    Effective DBHF Method for Asymmetric Nuclear Matter and Finite Nuclei

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    A new decomposition of the Dirac structure of nucleon self-energies in the Dirac Brueckner-Hartree-Fock (DBHF) approach is adopted to investigate the equation of state for asymmetric nuclear matter. The effective coupling constants of σ\sigma , ω\omega , δ\delta and ρ\rho mesons with a density dependence in the relativistic mean field approach are deduced by reproducing the nucleon self-energy resulting from the DBHF at each density for symmetric and asymmetric nuclear matter. With these couplings the properties of finite nuclei are investigated. The agreement of charge radii and binding energies of finite nuclei with the experimental data are improved simultaneously in comparison with the projection method. It seems that the properties of finite nuclei are sensitive to the scheme used for the DBHF self-energy extraction. We may conclude that the properties of the asymmetric nuclear matter and finite nuclei could be well described by the new decomposition approach of the G matrix.Comment: 16 pages, 5 figure

    a qualitative study

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    Objectives: It is known that transition, as a shift of care, marks a vulnerable phase in the adolescents’ lives with an increased risk for non- adherence and allograft failure. Still, the transition process of adolescents and young adults living with a kidney transplant in Germany is not well defined. The present research aims to assess transition-relevant structures for this group of young people. Special attention is paid to the timing of the process. Setting: In an observational study, we visited 21 departments of paediatric nephrology in Germany. Participants were doctors (n=19), nurses (n=14) and psychosocial staff (n=16) who were responsible for transition in the relevant centres. Structural elements were surveyed using a short questionnaire. The experiential viewpoint was collected by interviews which were transcribedverbatim before thematic analysis was performed. Results: This study highlights that professionals working within paediatric nephrology in Germany are well aware of the importance of successful transition. Key elements of transitional care are well understood and mutually agreed on. Nonetheless, implementation within daily routine seems challenging, and the absence of written, structured procedures may hamper successful transition. Conclusions: While professionals aim for an individual timing of transfer based on medical, social, emotional and structural aspects, rigid regulations on transfer age as given by the relevant health authorities add on to the challenge. Trial registration number: ISRCTN Registry no 22988897; results (phase I) and pre-results (phase II)

    Neutron rich nuclei in density dependent relativistic Hartree-Fock theory with isovector mesons

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    Density dependent relativistic Hartree-Fock theory has been extended to describe properties of exotic nuclei. The effects of Fock exchange terms and of pi - and rho - meson contributions are discussed. These effects are found to be more important for neutron rich nuclei than for nuclei near the valley of stability.Comment: 10 pages, 5 figures, LaTeX, macro packages graphicx and time

    Application of the density dependent hadron field theory to neutron star matter

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    The density dependent hadron field (DDRH) theory, previously applied to isospin nuclei and hypernuclei is used to describe β\beta-stable matter and neutron stars under consideration of the complete baryon octet. The meson-hyperon vertices are derived from Dirac-Brueckner calculations of nuclear matter and extended to hyperons. We examine properties of density dependent interactions derived from the Bonn A and from the Groningen NN potential as well as phenomenological interactions. The consistent treatment of the density dependence introduces rearrangement terms in the expression for the baryon chemical potential. This leads to a more complex condition for the β\beta-equilibrium compared to standard relativistic mean field (RMF) approaches. We find a strong dependence of the equation of state and the particle distribution on the choice of the vertex density dependence. Results for neutron star masses and radii are presented. We find a good agreement with other models for the maximum mass. Radii are smaller compared to RMF models and indicate a closer agreement with results of non-relativistic Brueckner calculations.Comment: 28 pages, 11 figure

    “Seal Harbor’s Patron Saint”: John D. Rockefeller, Jr., and the Mount Desert Larger Parish

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    The Mount Desert Larger Parish (1925-1984) was the brainchild of John D. Rockefeller, Jr., who sought to apply modern industrial models to meet the religious needs of towns on the island where he established his summer home. Beyond his personal philanthropy, Rockefeller’s active involvement in the Parish extended to fund-raising and staff recruitment. Rockefeller was persuaded that Mount Desert was the perfect setting for this experiment in interdenominational cooperation, and he imagined its success would generate similar partnerships that would reshape American Protestantism. The challenges the Parish experienced through its six decades reveal the tensions between the island’s “summer people” and its year-long residents as well as rural Maine’s resistance to Rockefeller’s business models. John R. Muether earned his B.A. from Gordon College in Wenham,Mass., and masters degrees from Westminster Theological Seminary and Simmons Graduate School of Library and Information Science. Since 1989 he has served as Library Director and Associate Professor of Church History at Reformed Theological Seminary in Orlando, Florida, when he is not vacationing in coastal Maine. His most recent book is SEEKING A BETTER COUNTRY: 300 YEARS OF AMERICAN PRESBYTERIANISM (co-authored with D. G. Hart). Together with his wife Kathryn he has co-edited LITERARY MOUNT DESERT: AN ANTHOLOGY (forthcoming in 2008 from Islandport Press)
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