277 research outputs found

    New primary renal diagnosis codes for the ERA-EDTA

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    The European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) Registry has produced a new set of primary renal diagnosis (PRD) codes that are intended for use by affiliated registries. It is designed specifically for use in renal centres and registries but is aligned with international coding standards supported by the WHO (International Classification of Diseases) and the International Health Terminology Standards Development Organization (SNOMED Clinical Terms). It is available as supplementary material to this paper and free on the internet for non-commercial, clinical, quality improvement and research use, and by agreement with the ERA-EDTA Registry for use by commercial organizations. Conversion between the old and the new PRD codes is possible. The new codes are very flexible and will be actively managed to keep them up-to-date and to ensure that renal medicine can remain at the forefront of the electronic revolution in medicine, epidemiology research and the use of decision support systems to improve the care of patients

    Microscopic calculation of 6Li elastic and transition form factors

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    Variational Monte Carlo wave functions, obtained from a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana-IX three-nucleon interactions, are used to calculate the 6Li ground-state longitudinal and transverse form factors as well as transition form factors to the first four excited states. The charge and current operators include one- and two-body components, leading terms of which are constructed consistently with the two-nucleon interaction. The calculated form factors and radiative widths are in good agreement with available experimental data.Comment: 9 pages, 2 figures, REVTeX, submitted to Physical Review Letters, with updated introduction and reference

    Photo- and Electro-Disintegration of 3He at Threshold and pd Radiative Capture

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    The present work reports results for: pd radiative capture observables measured at center-of-mass (c.m.) energies in the range 0--100 keV and at 2 MeV by the TUNL and Wisconsin groups, respectively; contributions to the Gerasimov-Drell-Hearn (GDH) integral in 3He from the two- up to the three-body breakup thresholds, compared to experimental determinations by the TUNL group in this threshold region; longitudinal, transverse, and interference response functions measured in inclusive polarized electron scattering off polarized 3He at excitation energies below the threshold for breakup into ppn, compared to unpolarized longitudinal and transverse data from the Saskatoon group. The calculations are based on a realistic Hamiltonian with two- and three-nucleon interactions and a realistic current operator, including one- and two-body components. The theoretical predictions obtained by including only one-body currents are in violent disagreement with data. These differences between theory and experiment are, to a large extent, removed when two-body currents are taken into account, although some rather large discrepancies remain in the c.m. energy range 0--100 keV, particularly for the pd differential cross section and tensor analyzing power at small angles, and contributions to the GDH integral. A rather detailed analysis indicates that these discrepancies have, in large part, a common origin, and can be traced back to an excess strength obtained in the theoretical calculation of the E1 reduced matrix element associated with the pd channel having L,S,J=1,1/2,3/2. It is suggested that this lack of E1 strength observed experimentally might have implications for the nuclear interaction at very low energies. Finally, the validity of the long-wavelength approximation for electric dipole transitions is discussed.Comment: 47 pages RevTex file, 10 PostScript figures, submitted to Phys. Rev.

    Stability and Representation Dependence of the Quantum Skyrmion

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    A constructive realization of Skyrme's conjecture that an effective pion mass ``may arise as a self consistent quantal effect'' based on an ab initio quantum treatment of the Skyrme model is presented. In this quantum mechanical Skyrme model the spectrum of states with I=JI=J, which appears in the collective quantization, terminates without any infinite tower of unphysical states. The termination point depends on the model parameters and the dimension of the SU(2) representation. Representations, in which the nucleon and Δ33\Delta_{33} resonance are the only stable states, exist. The model is developed for both irreducible and reducible representations of general dimension. States with spin larger than 1/2 are shown to be deformed. The representation dependence of the baryon observables is illustrated numerically.Comment: 19 pages, Late

    Parity-Violating Electron-Deuteron Scattering

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    The longitudinal asymmetry due to Z0Z^0 exchange is calculated in quasi-elastic electron-deuteron scattering at momentum transfers ∣Q2∣≃0.1|Q^2| \simeq 0.1 GeV2^2 relevant for the SAMPLE experiment. The deuteron and pnpn scattering-state wave functions are obtained from solutions of a Schr\"odinger equation with the Argonne v18v_{18} potential. Electromagnetic and weak neutral one- and two-nucleon currents are included in the calculation. The two-nucleon currents of pion range are shown to be identical to those derived in Chiral Perturbation Theory. The results indicate that two-body contributions to the asymmetry are small (≃\simeq 0.2%) around the quasi-elastic peak, but become relatively more significant (≃\simeq 3%) in the high-energy wing of the quasi-elastic peak.Comment: 23 pages, 10 figure

    Resolving the Large-N Nuclear Potential Puzzle

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    The large NcN_c nuclear potential puzzle arose because three- and higher-meson exchange contributions to the nucleon-nucleon potential did not automatically yield cancellations that make these contributions consistent with the general large NcN_c scaling rules for the potential. Here it is proposed that the resolution to this puzzle is that the scaling rules only apply for energy-independent potentials while all of the cases with apparent inconsistencies were for energy-dependent potentials. It is shown explicitly how energy-dependent potentials can have radically different large N behavior than an equivalent energy-independent one. One class of three-meson graphs is computed in which the contribution to the energy-independent potential is consistent with the general large N rules even though the energy-dependent potential is not.Comment: Corrections to the toy mode

    Extraction of electromagnetic neutron form factors through inclusive and exclusive polarized electron scattering on polarized 3He target

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    Inclusive 3He(e,e') and exclusive 3He(e,e'n) processes with polarized electrons and 3He have been theoretically analyzed and values for the magnetic and electric neutron form factors have been extracted. In both cases the form factor values agree well with the ones extracted from processes on the deuteron. Our results are based on Faddeev solutions, modern NN forces and partially on the incorporation of mesonic exchange currents.Comment: 28 pages, 29 Postscript figure

    Strangeness, charm and bottom in a chiral quark-meson model

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    In this paper we investigate an SU(3) extension of the chiral quark-meson model. The spectra of baryons with strangeness, charm and bottom are considered within a "rigid oscillator" version of this model. The similarity between the quark part of the Lagrangian in the model and the Wess-Zumino term in the Skyrme model is noted. The binding energies of baryonic systems with baryon number B=2 and 3 possessing strangeness or heavy flavor are estimated. The results obtained are in good qualitative agreement with those obtained previously in the topological soliton (Skyrme) model.Comment: 12 pages, no figures. Journal ref: submitted to Nucl.Phys.

    Excited ΛQ\Lambda_Q Baryons in the Large NcN_c Limit

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    The spectrum of excited ΛQ\Lambda_Q-type heavy baryons is considered in the large NcN_c limit. The universal form factors for Λb\Lambda_b semileptonic decay to excited charmed baryons are calculated in the large NcN_c limit. We find that the Bjorken sum rule (for the slope of the Isgur--Wise function) and Voloshin sum rule (for the mass of the light degrees of freedom) are saturated by the first doublet of excited ΛQ\Lambda_Q states.Comment: 9 pages, use phyzzx, CALT-68-191

    Origin of Relativistic Effects in the Reaction D(e,e'p)n at GeV Energies

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    In a series of recent publications, a new approach to the non-relativistic reduction of the electromagnetic current operator in calculations of electro-nuclear reactions has been introduced. In one of these papers, the conjecture that at energies of a few GeV, the bulk of the relativistic effects comes from the current and not from the nuclear dynamics was made, based on the large relativistic effects in the transverse-longitudinal response. Here, we explicitly compare a fully relativistic, manifestly covariant calculation performed with the Gross equation, with a calculation that uses a non-relativistic wave function and a fully relativistic current operator. We find very good agreement up to missing momenta of 400 MeV/c, thus confirming the previous conjecture. We discuss slight deviations in cross sections for higher missing momenta and their possible origin, namely p-wave contributions and off-shell effects.Comment: 25 pages, 11 figure
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