298 research outputs found

    Threshold pi^0 photo- and electro-production in a meson-exchange model

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    We show that, within a meson-exchange dynamical model describing well most of the existing pion electromagnetic production data up to the second resonance region, one is also able to obtain a good agreement with the pi^0 photo- and electroproduction data near threshold. In the case of pi^0 production, the effects of final state interaction in the threshold region are nearly saturated by single charge exchange rescattering. This indicates that in ChPT, it might be sufficient to carry out the calculation just up to one-loop diagrams for threshold neutral pion production.Comment: 6 pages LATEX including 1 tables and 4 figures, uses espcrc1.st

    Generalized polarizabilities and electroexcitation of the nucleon

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    Generalized nucleon polarizabilities for virtual photons can be defined in terms of electroproduction cross sections as function of the 4-momentum transfer Q2Q^2. In particular, the sum of the generalized electric and magnetic polarizabilities Σ=α+β\Sigma=\alpha+\beta and the spin polarizability γ\gamma can be expressed by virtual photon absorption cross sections integrated over the excitation energy. These quantities have been calculated within the framework of the recently developed unitary isobar model for pion photo- and electroproduction on the proton, which describes the available experimental data up to an excitation energy of about 1 GeV. Our results have been compared to the predictions of chiral perturbation theory.Comment: 21 pages, latex, 14 figure

    Cardiovascular mortality and its predictors in the republic of tatarstan (Russia)

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    © 2016, International Journal of Pharmacy and Technology. All rights reserved.Cardiovascular diseases remain the main cause of death in the population around the world. The US and Western European countries have tendency to reduction in cardiovascular mortality in recent decades. At the same time, in the Russian Federation, cardiovascular mortality is more than two times higher as compared to the US. Cardiovascular disease in the Russian Federation is the cause of at least 50% of all deaths. Objective: To evaluate the cardiovascular mortality in rural and urban areas of the Republic of Tatarstan of the Russian Federation during 2002-2007. To identify the predictors of cardiovascular mortality. Materials and methods: The first phase of the study was carried out in 2002. Cardiovascular diseases were diagnosed, and the risk factors were evaluated. Re-examination was conducted in 2007. The study involved total 2,353 persons. Results: cardiovascular mortality in the Republic of Tatarstan in 2002-2007 was 821.64 per 100,000 population. In the mortality structure, cardiovascular disease accounted for 66.67%. The most significant predictors of cardiovascular mortality are chronic heart failure and diabetes mellitus

    Singularity structure of the pi N scattering amplitude in a meson-exchange model up to energies W < 2.0 GeV

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    Within the previously developed Dubna-Mainz-Taipei meson-exchange model, the singularity structure of the pi N scattering amplitudes has been investigated. For all partial waves up to F waves and c.m. energies up to W = 2 GeV, the T-matrix poles have been calculated by three different techniques: analytic continuation into the complex energy plane, speed-plot and the regularization method. For all 4-star resonances, we find a perfect agreement between the analytic continuation and the regularization method. We also find resonance poles for resonances that are not so well established, but in these cases the pole positions and residues obtained by analytic continuation can substantially differ from the results predicted by the speed-plot and regularization methods.Comment: 21 pages, 4 figures, 4 table

    Singularity structure of the pi N scattering amplitude in a meson-exchange model up to energies W < 2.0 GeV

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    Within the previously developed Dubna-Mainz-Taipei meson-exchange model, the singularity structure of the pi N scattering amplitudes has been investigated. For all partial waves up to F waves and c.m. energies up to W = 2 GeV, the T-matrix poles have been calculated by three different techniques: analytic continuation into the complex energy plane, speed-plot and the regularization method. For all 4-star resonances, we find a perfect agreement between the analytic continuation and the regularization method. We also find resonance poles for resonances that are not so well established, but in these cases the pole positions and residues obtained by analytic continuation can substantially differ from the results predicted by the speed-plot and regularization methods.Comment: 21 pages, 4 figures, 4 table

    Elastic Pion Scattering on the Deuteron in a Multiple Scattering Model

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    Pion elastic scattering on deuterium is studied in the KMT multiple scattering approach developed in momentum space. Using a Paris wave function and the same methods and approximations as commonly used in pion scattering on heavier nuclei excellent agreement with differential cross section data is obtained for a wide range of pion energies. Only for Tπ>250T_{\pi}>250 MeV and very backward angles, discrepancies appear that are reminiscent of disagreements in pion scattering on 3^3He, 3^3H, and 4^4He. At low energies the second order corrections have been included. Polarization observables are studied in detail. While tensor analyzing powers are well reproduced, vector analyzing powers exhibit dramatic discrepancies.Comment: 25 pages LATEX and 9 postscript figures in a self-extracting uufile archiv

    Experimental study of the influence of pulse electrophoresis of blood plasma 0 (I) on healing of wounds and formation of normotrophic scars in laboratory animals

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    In experimental study confirmed the acceleration of wound healing and forming normotrophic scars tissue in laboratory animals using the transdermal administration of blood plasma 0 (I) by pulsed electrophoresis under the influence of an external magnetic field. It was established that the method proposed by the authors prevents the development of hypertrophic and keloid scars, and also stimulates tissue regeneration in the surgical area due to the activation of local regeneration processes

    Measurement of the LT-asymmetry in \pi^0 electroproduction at the energy of the \Delta (1232) resonance

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    The reaction p(e,e'p)pi^0 has been studied at Q^2=0.2 (GeV/c)^2 in the region of W=1232 MeV. From measurements left and right of q, cross section asymmetries \rho_LT have been obtained in forward kinematics \rho_LT(\theta_\pi^0=20deg) = (-11.68 +/- 2.36_stat +/- 2.36_sys)$ and backward kinematics \rho_LT(\theta_\pi^0=160deg) =(12.18 +/- 0.27_stat +/- 0.82_sys). Multipole ratios \Re(S_1+^* M_1+)/|M_1+|^2 and \Re(S_0+^* M_1+)/|M_1+|^2 were determined in the framework of the MAID2003 model. The results are in agreement with older data. The unusally strong negative \Re(S_0+^* M_1+)/|M_1+|^2 required to bring also the result of Kalleicher et al. in accordance with the rest of the data is almost excluded.Comment: 7 pages, 7 figures, 4 tables. Changed content. Accepted for publication in EPJ

    Temperature dependent fluorescence in disordered Frenkel chains: interplay of equilibration and local band-edge level structure

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    We model the optical dynamics in linear Frenkel exciton systems governed by scattering on static disorder and lattice vibrations, and calculate the temperature dependent fluorescence spectrum and lifetime. The fluorescence Stokes shift shows a nonmonotonic behavior with temperature, which derives from the interplay of the local band-edge level structure and thermal equilibration. The model yields excellent fits to experiments performed on linear dye aggregates.Comment: 4 pages, 3 figure
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