49 research outputs found

    The Multifragmentation Freeze--Out Volume in Heavy Ion Collisions

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    The reduced velocity correlation function for fragments from the reaction Fe + Au at 100 A~MeV bombarding energy is investigated using the dynamical--statistical approach QMD+SMM and compared to experimental data to extract the Freeze--Out volume assuming simultaneous multifragmentation.Comment: 8 pages; 3 uuencoded figures available with figures command, LateX, UCRL-J-1157

    Dielectron Cross Section Measurements in Nucleus-Nucleus Reactions at 1.0 A GeV

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    We present measured dielectron production cross sections for Ca+Ca, C+C, He+Ca, and d+Ca reactions at 1.0 A GeV. Statistical uncertainties and systematic effects are smaller than in previous DLS nucleus-nucleus data. For pair mass < 0.35 GeV/c2 : 1) the Ca+Ca cross section is larger than the previous DLS measurement and current model results, 2) the mass spectra suggest large contributions from pi0 and eta Dalitz decays, and 3) dsigma/dM is proportional to ApAt. For M > 0.5 GeV/c2 the Ca+Ca to C+C cross section ratio is significantly larger than the ratio of ApAt values.Comment: Submitted to Physical Review Letters. Further analysis information will be posted on our web pages -- http://macdls.lbl.gov Figure 1 has been redrawn to make more legible. Text modified to support redrawn figur

    Генетические факторы, влияющие на проникновение ВИЧ в клетку-мишень

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    Succeptibility to HIV and the dynamics of HIV infection progression to AIDS are dependent on unique individual factors. Revealing genetic features of natural resistance to HIV infection is of great importance for the development of effective strategies for disease control. This review presents an analysis of host gene alleles coding receptors and their ligands participating in viral entrance to target cell. These allelic variants and their combinations can have a significant influence on the individual resistance/sensitivity to HIV infection and may be associated with the HIV infection progression to AIDS.Восприимчивость к ВИЧ-инфекции, а также динамика развития заболевания носят индивидуальный характер. Раскрытие генетических основ естественной резистентности к ВИЧ чрезвычайно важно для выработки эффективных стратегий контроля заболевания. Обзор посвящен анализу аллельных вариантов генов хозяина, которые кодируют рецепторы и их лиганды, участвующие в процессе проникновения вируса в клетку-мишень. Эти аллельные варианты и их сочетания способны оказывать значимое влияние на устойчивость либо чувствительность индивидуума к ВИЧ-инфекции, а также могут быть ассоциированы со скоростью прогрессии ВИЧ-инфекции в СПИД

    Differential Transverse Flow in Central C-Ne and C-Cu Collisions at 3.7 GeV/nucleon

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    Differential transverse flow of protons and pions in central C-Ne and C-Cu collisions at a beam energy of 3.7 GeV/nucleon was measured as a function of transverse momentum at the SKM-200-GIBS setup of JINR. In agreement with predictions of a transversely moving thermal model, the strength of proton differential transverse flow is found to first increase gradually and then saturate with the increasing transverse momentum in both systems. While pions are preferentially emitted in the same direction of the proton transverse flow in the reaction of C-Ne, they exhibit an anti-flow to the opposote direction of the proton transverse flow in the reaction of C-Cu due to stronger shadowing effects of the heavier target in thr whole range of transverse momentum.Comment: 15 pages, 5 figure

    Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

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    Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (mu_B > 500 MeV), effects of chiral symmetry, and the equation-of-state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2022, in the context of the worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal

    Calculation of photon-radiation mass attenuation coefficient

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    Genetic factors influencing HIV entry into target cells

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    Succeptibility to HIV and the dynamics of HIV infection progression to AIDS are dependent on unique individual factors. Revealing genetic features of natural resistance to HIV infection is of great importance for the development of effective strategies for disease control. This review presents an analysis of host gene alleles coding receptors and their ligands participating in viral entrance to target cell. These allelic variants and their combinations can have a significant influence on the individual resistance/sensitivity to HIV infection and may be associated with the HIV infection progression to AIDS

    Allelic variants of human genes affecting HIV intracellular life cycle and regulating immune response to HIV infection

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    Host genetic factors influencing the intracellular part of HIV live cycle and regulating of HIV-specific immune response are reviewed. Its include genes coding proteins which support viral replication and assembly of new virions, genes coding antiviral defense proteins, HLA genes and some others. Variants of these genes and its compositions affect individual succeptibility/resistance to HIV infection, influence the pathogenesis of the disease and also associate with efficacy of antiretroviral therapy
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