14,840 research outputs found

    Proton emission induced by polarized photons

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    The proton emission induced by polarized photons is studied in the energy range above the giant resonance region and below the pion emission threshold. Results for the 12C, 16O and 40Ca nuclei are presented. The sensitivity of various observables to final state interaction, meson exchange currents and short range correlations is analyzed. We found relevant effects due to the virtual excitation of the Δ\Delta resonance.Comment: 12 pages, 11 figures, 1 tabl

    Low-lying magnetic excitations of doubly-closed-shell nuclei and nucleon-nucleon effective interactions

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    We have studied the low lying magnetic spectra of 12C, 16O, 40Ca, 48Ca and 208Pb nuclei within the Random Phase Approximation (RPA) theory, finding that the description of low-lying magnetic states of doubly-closed-shell nuclei imposes severe constraints on the spin and tensor terms of the nucleon-nucleon effective interaction. We have first made an investigation by using four phenomenological effective interactions and we have obtained good agreement with the experimental magnetic spectra, and, to a lesser extent, with the electron scattering responses. Then we have made self-consistent RPA calculations to test the validity of the finite-range D1 Gogny interaction. For all the nuclei under study we have found that this interaction inverts the energies of all the magnetic states forming isospin doublets.Comment: 19 pages, 13 figures, 7 tables, accepted for publication in Phys. Rev.

    Magnetic excitations in nuclei with neutron excess

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    The excitation of the 1+1^+, 2−2^- and 3+3^+ modes in 16^{16}O, 22^{22}O, 24^{24}O, 28^{28}O, 40^{40}Ca, 48^{48}Ca, 52^{52}Ca and 60^{60}Ca nuclei is studied with self-consistent random phase approximation calculations. Finite-range interactions of Gogny type, containing also tensor-isospin terms, are used. We analyze the evolution of the magnetic resonances with the increasing number of neutrons, the relevance of collective effects, the need of a correct treatment of the continuum and the role of the tensor force.Comment: 18 pages, 12 figures, 2 tables, accepted for publication in Physical Review

    Effects of state dependent correlations on nucleon density and momentum distributions

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    The proton momentum and density distributions of closed shell nuclei are calculated within a model treating short--range correlations up to first order in the cluster expansion. The validity of the model is verified by comparing the results obtained with purely scalar correlations with those produced by finite nuclei Fermi Hypernetted Chain calculations. State dependent correlations are used to calculate momentum and density distributions of 12C, 16O, 40Ca, and 48Ca, and the effects of their tensor components are studied.Comment: 16 pages, latex, 8 figures, accepted for publication in Phys. Rev.

    Treatment of hepatic epithelioid hemangioendothelioma with liver transplantation

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    Ten patients received liver transplants for unresectable epithelioid hemangioendothelioma (EHE). At the time of transplantation, four patients had microscopic metastases to the hilar lymph nodes, and one of the four also had metastases to a rib. The fifth patient had metastases to the lung, pleura, and diaphragm. The remaining five patients were believed to be free of metastatic disease. Two of these five patients died of metastatic disease at 3 and 16 months, respectively, after transplantation. Interestingly, all five patients with metastatic involvement are currently alive 40.6 ± 22 months (mean ± standard error of mean [SEM]) after transplantation, although one of these patients currently has metastatic disease to the lungs and mediastinum. Thus, the projected 5‐year actuarial survival rate is 76%, with two patients at risk after the third year. In conclusion, liver transplantation is a reasonable procedure for bulky, otherwise unresectable, EHE even in the presence of metastatic disease. Copyright © 1988 American Cancer Societ

    Short-range Correlations in a CBF description of closed-shell nuclei

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    The Correlated Basis Function theory (CBF) provides a theoretical framework to treat on the same ground mean-field and short-range correlations. We present, in this report, some recent results obtained using the CBF to describe the ground state properties of finite nuclear systems. Furthermore we show some results for the excited state obtained with a simplified model based on the CBF theory.Comment: 10 latex pages plus 6 uuencoded figure

    An automatic visual analysis system for tennis

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    This article presents a novel video analysis system for coaching tennis players of all levels, which uses computer vision algorithms to automatically edit and index tennis videos into meaningful annotations. Existing tennis coaching software lacks the ability to automatically index a tennis match into key events, and therefore, a coach who uses existing software is burdened with time-consuming manual video editing. This work aims to explore the effectiveness of a system to automatically detect tennis events. A secondary aim of this work is to explore the bene- fits coaches experience in using an event retrieval system to retrieve the automatically indexed events. It was found that automatic event detection can significantly improve the experience of using video feedback as part of an instructional coaching session. In addition to the automatic detection of key tennis events, player and ball movements are automati- cally tracked throughout an entire match and this wealth of data allows users to find interesting patterns in play. Player and ball movement information are integrated with the automatically detected tennis events, and coaches can query the data to retrieve relevant key points during a match or analyse player patterns that need attention. This coaching software system allows coaches to build advanced queries, which cannot be facilitated with existing video coaching solutions, without tedious manual indexing. This article proves that the event detection algorithms in this work can detect the main events in tennis with an average precision and recall of 0.84 and 0.86, respectively, and can typically eliminate man- ual indexing of key tennis events

    A Moonlight Meander / words by S. M. Roberts

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    Cover: drawing of an African American couple strolling through the moonlight; description reads characteristic march or two-step; Publisher: Eclipse Publishing Co. (Philadelphia)https://egrove.olemiss.edu/sharris_b/1003/thumbnail.jp
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