977 research outputs found

    Apicoetomy and Root Canal Therapy of Canine Teeth in the Dog

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    When the root canal of the canine tooth of a dog is exposed due to wear or fracture, the result may be abscessation, bone resorption, and evulsion of the alveolus. The tooth must be extracted or endodontic therapy may be performed to restore the root canal. Techniques are described to stabilize both maxillary and mandibular canine teeth through root canal restoration and apicoectomy to seal the apex of the root and prevent future infection and abcessation

    Improved radiative corrections for (e, e'p) experiments: Beyond the peaking approximation and implications of the soft-photon approximation

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    Abstract.: Analyzing (e, e'p) experimental data involves corrections for radiative effects which change the interaction kinematics and which have to be carefully considered in order to obtain the desired accuracy. Missing momentum and energy due to bremsstrahlung have so far often been incorporated into the simulations and the experimental analyses using the peaking approximation. It assumes that all bremsstrahlung is emitted in the direction of the radiating particle. In this article we introduce a full angular Monte Carlo simulation method which overcomes this approximation. As a test, the angular distribution of the bremsstrahlung photons is reconstructed from H(e, e'p) data. Its width is found to be underestimated by the peaking approximation and described much better by the approach developed in this work. The impact of the soft-photon approximation on the photon angular distribution is found to be minor as compared to the impact of the peaking approximatio

    Parametrization of nuclear parton distributions

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    Optimum nuclear parton distributions are obtained by analyzing available experimental data on electron and muon deep inelastic scattering (DIS). The distributions are given at Q^2=1 GeV^2 with a number of parameters, which are determined by a chi^2 analysis of the data. Valence-quark distributions are relatively well determined at medium x, but they are slightly dependent on the assumed parametrization form particularly at small x. Although antiquark distributions are shadowed at small x, their behavior is not obvious at medium x from the F_2 data. The gluon distributions could not be restricted well by the inclusive DIS data; however, the analysis tends to support the gluon shadowing at small x. We provide analytical expressions and computer subroutines for calculating the nuclear parton distributions, so that other researchers could use them for applications to other high-energy nuclear reactions.Comment: 1+11 pages, LaTeX, amsmath.sty, wrapfig.sty, graphicx.sty, ias.cls, ias.sty, pramana.sty, pmana10.sty, pbib.sty, times.sty, 9 eps figures. Invited talk given at the International Symposium on Nuclear Physics, Mumbai, India, Dec. 18-22, 2000, to be published in proceedings. Complete postscript file is available at http://www-hs.phys.saga-u.ac.jp Email: [email protected], [email protected], [email protected]

    Effect of kinematics on final state interactions in (e,e'p) reactions

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    Recent data from experiment E97-006 at TJNAF using the 12C(e,e'p) reaction at very large missing energies and momenta are compared to a calculation of two-step rescattering. A comparison between parallel and perpendicular kinematics suggests that the effects of final state interactions can be strongly reduced in the former case.Comment: 10 pages, 3 figures, submitted to LP

    Probing Correlated Ground States with Microscopic Optical Model for Nucleon Scattering off Doubly-Closed-Shell Nuclei

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    The RPA long range correlations are known to play a significant role in understanding the depletion of single particle-hole states observed in (e, e') and (e, e'p) measurements. Here the Random Phase Approximation (RPA) theory, implemented using the D1S force is considered for the specific purpose of building correlated ground states and related one-body density matrix elements. These may be implemented and tested in a fully microscopic optical model for NA scattering off doubly-closed-shell nuclei. A method is presented to correct for the correlations overcounting inherent to the RPA formalism. One-body density matrix elements in the uncorrelated (i.e. Hartree-Fock) and correlated (i.e. RPA) ground states are then challenged in proton scattering studies based on the Melbourne microscopic optical model to highlight the role played by the RPA correlations. Effects of such correlations which deplete the nuclear matter at small radial distance (r << 2 fm) and enhance its surface region, are getting more and more sizeable as the incident energy increases. Illustrations are given for proton scattering observables measured up to 201 MeV for the 16^{16}O, 40^{40}Ca, 48^{48}Ca and 208^{208}Pb target nuclei. Handling the RPA correlations systematically improves the agreement between scattering predictions and data for energies higher than 150 MeV.Comment: 20 pages, 7 figure

    y scaling in electron-nucleus scattering

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    Data on inclusive electron scattering from A = 4, 12, 27, 56, 197 nuclei at large momentum transfer are presented and analyzed in terms of y scaling. We find that the data do scale for y 1), and we study the convergence of the scaling function with the momentum transfer Q^2 and A

    A high-precision polarimeter

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    We have built a polarimeter in order to measure the electron beam polarization in hall C at JLAB. Using a superconducting solenoid to drive the pure-iron target foil into saturation, and a symmetrical setup to detect the Moller electrons in coincidence, we achieve an accuracy of <1%. This sets a new standard for Moller polarimeters.Comment: 17 pages, 9 figures, submitted to N.I.

    Impaired cardiac autonomic nervous control after cardiac bypass surgery for congenital heart disease

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    We undertook a study to describe changes in heart rate variability (HRV) postoperatively in children undergoing cardiac bypass surgery for congenital heart disease (CHD). HRV was recorded for a 1-h period preoperatively and a 24-h period postoperatively in 20 children with CHD. We found a highly significant reduction in HRV in both time and frequency domain indices compared to preoperative values, which was sustained throughout the 24-h study period. There was a negative correlation between both time and frequency domain HRV measurements and length of cardiac bypass. HRV is reduced postoperatively and correlates with cardiac bypass time. Length of cardiac bypass time may be one mechanism whereby HRV is reduced following surgery

    Superscaling in inclusive electron-nucleus scattering

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    We investigate the degree to which the scaling functions F(ψ′)F(\psi') derived from cross sections for inclusive electron-nucleus quasi-elastic scattering define the same function for different nuclei. In the region where the scaling variable ψ′<0\psi'< 0, we find that this superscaling is experimentally realized to a high degree.Comment: Corrected previously mislabeled figures and cross references; 9 pages, 4 color figures, using BoxedEPS and REVTeX; email correspondence to [email protected]
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