352 research outputs found

    Evaluation of coronary arteries in non-ischemic cardiomyopathies: A case report

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    Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a congenital cardiac disease with myocardial involvement, most probably right ventricular (RV) dysfunction, accounting for 20 of sudden cardiac deaths. Characterized by the fibro-fatty infiltration of the RV free wall, ARVD/C presents in adolescents with ventricular arrhythmias and heart failure symptoms and as biventricular failure in adults. The coronary risk in these patients is not clear. We present an incidental finding: the left anterior descending artery cut-off in a middle-aged man with ARVD/C. He had been under treatment for heart failure symptoms, which had decompensated frequently commencing 6 months earlier, and therefore he was scheduled for stem cell injection. He had no chest pain or coronary artery disease risk factors. Two-dimensional transthoracic echocardiography demonstrated RV enlargement with moderate to severe dysfunction and left ventricular ejection fraction (LVEF) of 35-40, which was 45-50 two years before. Selective coronary angiography performed 8 years previously was normal but a new one revealed the cut-off of the left anterior descending artery at the proximal portion, for which percutaneous coronary intervention was performed and showed no significant lesion in the other vessels. One should consider coronary artery disease in uncontrolled heart failure with LVEF reduction, even in the absence of typical chest pain. It may not be the natural course of the underlying disease. © 2016, Tehran Heart Center. All rights reserved

    Precision Measurement of the p(e,e \u27 p)pi(0) Reaction at Threshold

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    New results are reported from a measurement of pi(0) electroproduction near threshold using the p(e , e\u27p)pi(0) reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the. phi*(pi) and. theta*(pi) angles in the p pi(0) center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q(2) coverage ranges from 0.05 to 0.155 (GeV/c)(2) in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q(2) \u3e 0.07 (GeV/c)(2), while the s-wave predictions are in reasonable agreement

    Effect of intensive melt shearing on the formation of Fe-containing intermetallics in LM24 Al-alloy

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    Fe is one of the inevitable and detrimental impurities in aluminium alloys that degrade the mechanical performance of castings. In the present work, intensive melt shearing has been demonstrated to modify the morphology of Fe-containing intermetallic compounds by promoting the formation of compact α-Al(Fe,Mn)Si at the expense of needle-shaped β-AlFeSi, leading to an improved mechanical properties of LM24 alloy processed by MC-HPDC process. The promotion of the formation of α -Al(Fe, Mn)Si phase is resulted from the enhanced nucleation on the well dispersed MgAl 2O 4 particles in the melt. The Fe tolerance of LM24 alloy can be effectively improved by combining Mn alloying and intensive melt shearing

    Effect of Phosphorus and Strontium Additions on Formation Temperature and Nucleation Density of Primary Silicon in Al-19 Wt Pct Si Alloy and Their Effect on Eutectic Temperature

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    The influence of P and Sr additions on the formation temperature and nucleation density of primary silicon in Al-19 wt pct Si alloy has been determined, for small volumes of melt solidified at cooling rates _T of ~0.3 and 1 K/s. The proportion of ingot featuring primary silicon decreased progressively with increased Sr addition, which also markedly reduced the temperature for first formation of primary silicon and the number of primary silicon particles per unit volume �Nv: When combined with previously published results, the effects of amount of P addition and cooling rate on �Nv are in reasonable accord with �Nv� _T ¼ ðp=6fÞ1=2 109 [250 � 215 (wt pct P)0.17]�3, where �Nv is in mm�3, _T is in K/s, and f is volume fraction of primary silicon. Increased P addition reduces the eutectic temperature, while increased Sr appears to generate a minimum in eutectic temperature at about 100 ppmw Sr

    Recoil Polarization Measurements of the Proton Electromagnetic Form Factor Ratio to Q^2 = 8.5 GeV^2

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    Among the most fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents; indeed, recent proton data have attracted intense theoretical interest. In this letter, we report new measurements of the proton electromagnetic form factor ratio using the recoil polarization method, at momentum transfers Q2=5.2, 6.7, and 8.5 GeV2. By extending the range of Q2 for which GEp is accurately determined by more than 50%, these measurements will provide significant constraints on models of nucleon structure in the non-perturbative regime

    Measurements of the Electric Form Factor of the Neutron up to Q2=3.4 GeV2 using the Reaction He3(e,e'n)pp

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    The electric form factor of the neutron was determined from studies of the reaction He3(e,e'n)pp in quasi-elastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2-range over which it is known, we find GEn = 0.0225 +/- 0.0017 (stat) +/- 0.0024 (syst), 0.0200 +/- 0.0023 +/- 0.0018, and 0.0142 +/- 0.0019 +/- 0.0013 for Q2 = 1.72, 2.48, and 3.41 GeV2, respectively.Comment: submitted to PR
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