1,594 research outputs found

    Polymorphism of the tumor necrosis factor beta gene in systemic lupus erythematosus

    Get PDF
    We investigated the Nco I restriction fragment length polymorphism (RFLP) of the tumor necrosis factor beta (TNFB) gene in 173 patients with systemic lupus erythematosus (SLE), 192 unrelated healthy controls, and eleven panel families, all of German origin. The phenotype frequency of the TNFB*I allele was significantly increased in patients compared to controls (63.6% vs 47.1%, RR = 1.96, p <0.002). The results of a two-point haplotype statistical analysis between TNFB and HLA alleles show that there is linkage disequilibrium between TNFB*I and HLA-A1, Cw7, B8, DR3, DQ2, and C4A DE. The frequency of TNFB*I was compared in SLE patients and controls in the presence or absence of each of these alleles. TNFB*I is increased in patients over controls only in the presence of the mentioned alleles. Therefore, the whole haplotypeA1, Cw7, B8, TNFB* I, C4A DE, DR3, DQ2 is increased in patients and it cannot be determined which of the genes carried by this haplotype is responsible for the susceptibility to SLE. In addition, two-locus associations were analyzed in 192 unrelated healthy controls for TNFB and class I alleles typed by serology, and for TNFB and class II alleles typed by polymerase chain reaction/oligonucleotide probes. We found positive linkage disequilibrium between TNFB*I and the following alleles: HLA-A24, HLA-B8, DRBI*0301, DRBI*ll04, DRBI*1302, DQAI*0501, DQBI*0201, DQBI*0604, and DPBI*OIO1. TNFB*2 is associated with HLA-B7, DRBI*1501, and DQB I *0602

    A novel approach to track finding in a drift tube chamber

    Get PDF
    A novel track finding approach for drift tube detectors

    Universality of Long-Range Correlations in Expansion-Randomization Systems

    Full text link
    We study the stochastic dynamics of sequences evolving by single site mutations, segmental duplications, deletions, and random insertions. These processes are relevant for the evolution of genomic DNA. They define a universality class of non-equilibrium 1D expansion-randomization systems with generic stationary long-range correlations in a regime of growing sequence length. We obtain explicitly the two-point correlation function of the sequence composition and the distribution function of the composition bias in sequences of finite length. The characteristic exponent χ\chi of these quantities is determined by the ratio of two effective rates, which are explicitly calculated for several specific sequence evolution dynamics of the universality class. Depending on the value of χ\chi, we find two different scaling regimes, which are distinguished by the detectability of the initial composition bias. All analytic results are accurately verified by numerical simulations. We also discuss the non-stationary build-up and decay of correlations, as well as more complex evolutionary scenarios, where the rates of the processes vary in time. Our findings provide a possible example for the emergence of universality in molecular biology.Comment: 23 pages, 15 figure

    A Finite Difference Representation of Neutrino Radiation Hydrodynamics in Spherically Symmetric General Relativistic Space-Time

    Full text link
    We present an implicit finite difference representation for general relativistic radiation hydrodynamics in spherical symmetry. Our code, Agile-Boltztran, solves the Boltzmann transport equation for the angular and spectral neutrino distribution functions in self-consistent simulations of stellar core collapse and postbounce evolution. It implements a dynamically adaptive grid in comoving coordinates. Most macroscopically interesting physical quantities are defined by expectation values of the distribution function. We optimize the finite differencing of the microscopic transport equation for a consistent evolution of important expectation values. We test our code in simulations launched from progenitor stars with 13 solar masses and 40 solar masses. ~0.5 s after core collapse and bounce, the protoneutron star in the latter case reaches its maximum mass and collapses further to form a black hole. When the hydrostatic gravitational contraction sets in, we find a transient increase in electron flavor neutrino luminosities due to a change in the accretion rate. The muon- and tauon-neutrino luminosities and rms energies, however, continue to rise because previously shock-heated material with a non-degenerate electron gas starts to replace the cool degenerate material at their production site. We demonstrate this by supplementing the concept of neutrinospheres with a more detailed statistical description of the origin of escaping neutrinos. We compare the evolution of the 13 solar mass progenitor star to simulations with the MGFLD approximation, based on a recently developed flux limiter. We find similar results in the postbounce phase and validate this MGFLD approach for the spherically symmetric case with standard input physics.Comment: reformatted to 63 pages, 24 figures, to be published in ApJ

    General-Relativistic Thomas-Fermi model

    Get PDF
    A system of self-gravitating massive fermions is studied in the framework of the general-relativistic Thomas-Fermi model. We study the properties of the free energy functional and its relation to Einstein's field equations. A self-gravitating fermion gas we then describe by a set of Thomas-Fermi type self-consistency equations.Comment: 7 pages, LaTex, to appear in Gen. Rel. Gra

    Semi-Hard Scattering Unraveled from Collective Dynamics by Two-Pion Azimuthal Correlations in 158 A GeV/c Pb + Au Collisions

    Full text link
    Elliptic flow and two-particle azimuthal correlations of charged hadrons and high-pTp_T pions (pT>p_T> 1 GeV/cc) have been measured close to mid-rapidity in 158A GeV/cc Pb+Au collisions by the CERES experiment. Elliptic flow (v2v_2) rises linearly with pTp_T to a value of about 10% at 2 GeV/cc. Beyond pTp_T\approx 1.5 GeV/cc, the slope decreases considerably, possibly indicating a saturation of v2v_2 at high pTp_T. Two-pion azimuthal anisotropies for pT>p_T> 1.2 GeV/cc exceed the elliptic flow values by about 60% in mid-central collisions. These non-flow contributions are attributed to near-side and back-to-back jet-like correlations, the latter exhibiting centrality dependent broadening.Comment: Submitted to Phys. Rev. Letters, 4 pages, 5 figure

    The consequences of nuclear electron capture in core collapse supernovae

    Full text link
    The most important weak nuclear interaction to the dynamics of stellar core collapse is electron capture, primarily on nuclei with masses larger than 60. In prior simulations of core collapse, electron capture on these nuclei has been treated in a highly parameterized fashion, if not ignored. With realistic treatment of electron capture on heavy nuclei come significant changes in the hydrodynamics of core collapse and bounce. We discuss these as well as the ramifications for the post-bounce evolution in core collapse supernovae.Comment: Accepted by PRL, 5 pages, 2 figure
    corecore