6,646 research outputs found

    Gender And The Evaluation Of Physicists

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    Vibrationally resolved partial cross sections and asymmetry parameters for carbon K-shell photoionization of the CO_2 molecule

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    We have measured the vibrationally resolved partial cross sections \sigma_{v_1^{\prime}} and asymmetry parameters \beta_{v_1^{\prime}} for C K-shell photoionization of the CO2 molecule in the Σu shape resonance region above the C K-shell ionization threshold. The positions of both the maxima of \sigma_{v_1^{\prime}} and the minima of \beta_{v_1^{\prime}} move towards the C K-shell threshold with increasing symmetric stretching vibrational excitation v'1 in the C 1s single-hole state. Calculations employing the relaxed-core Hartree–Fock approach reproduce the observed vibrational effects

    Properties of the cosmological filament between two clusters: A possible detection of a large-scale accretion shock by SuzakuSuzaku

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    We report on the results of a SuzakuSuzaku observation of the plasma in the filament located between the two massive clusters of galaxies Abell 399 and Abell 401. Abell 399 (zz=0.0724) and Abell 401 (zz=0.0737) are expected to be in the initial phase of a cluster merger. In the region between the two clusters, we find a clear enhancement in the temperature of the filament plasma from 4 keV (expected value from a typical cluster temperature profile) to kTkT\sim6.5 keV. Our analysis also shows that filament plasma is present out to a radial distance of 15' (1.3 Mpc) from a line connecting the two clusters. The temperature profile is characterized by an almost flat radial shape with kTkT\sim6-7 keV within 10' or \sim0.8 Mpc. Across rr=8'~from the axis, the temperature of the filament plasma shows a drop from 6.3 keV to 5.1 keV, indicating the presence of a shock front. The Mach number based on the temperature drop is estimated to be M{\cal M}\sim1.3. We also successfully determined the abundance profile up to 15' (1.3 Mpc), showing an almost constant value (ZZ=0.3 solar) at the cluster outskirt. We estimated the Compton yy-parameter to be \sim14.5±1.3×106\pm1.3\times10^{-6}, which is in agreement with PlanckPlanck's results (14-17×106\times10^{-6} on the filament). The line of sight depth of the filament is ll\sim1.1 Mpc, indicating that the geometry of filament is likely a pancake shape rather than cylindrical. The total mass of the filamentary structure is \sim7.7×1013 M\times10^{13}~\rm M_{\odot}. We discuss a possible interpretation of the drop of X-ray emission at the rim of the filament, which was pushed out by the merging activity and formed by the accretion flow induced by the gravitational force of the filament.Comment: 8 pages, 8 figures, accepted for publication in A&

    A critical Mach number for electron injection in collisionless shocks

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    Electron acceleration in collisionless shocks with arbitrary magnetic field orientations is discussed. It is shown that the injection of thermal electrons into diffusive shock acceleration process is achieved by an electron beam with a loss-cone in velocity space that is reflected back upstream from the shock through shock drift acceleration mechanism. The electron beam is able to excite whistler waves which can scatter the energetic electrons themselves when the Alfven Mach number of the shock is sufficiently high. A critical Mach number for the electron injection is obtained as a function of upstream parameters. The application to supernova remnant shocks is discussed.Comment: 4 pages, 2 figure, accepted for publication in Physical Review Letter

    Innate immunity and adjuvants

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    Innate immunity was for a long time considered to be non-specific because the major function of this system is to digest pathogens and present antigens to the cells involved in acquired immunity. However, recent studies have shown that innate immunity is not non-specific, but is instead sufficiently specific to discriminate self from pathogens through evolutionarily conserved receptors, designated Toll-like receptors (TLRs). Indeed, innate immunity has a crucial role in early host defence against invading pathogens. Furthermore, TLRs were found to act as adjuvant receptors that create a bridge between innate and adaptive immunity, and to have important roles in the induction of adaptive immunity. This paradigm shift is now changing our thinking on the pathogenesis and treatment of infectious, immune and allergic diseases, as well as cancers. Besides TLRs, recent findings have revealed the presence of a cytosolic detector system for invading pathogens. I will review the mechanisms of pathogen recognition by TLRs and cytoplasmic receptors, and then discuss the roles of these receptors in the development of adaptive immunity in response to viral infection

    Mass singularity and confining property in QED3QED_3

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    We discuss the properties of the position space fermion propagator in three dimensional QED which has been found previouly based on Ward-Takahashi-identity for soft-photon emission vertex and spectral representation.There is a new type of mass singularity which governs the long distance behaviour.It leads the propagator vanish at large distance.This term corresponds to dynamical mass in position space.Our model shows confining property and dynamical mass generation for arbitrary coupling constant.Since we used dispersion retation in deriving spectral function there is a physical mass which sets a mass scale.For finite cut off we obtain the full propagator in the dispersion integral as a superposition of different massses.Low energy behaviour of the proagator is modified to decrease by position dependent mass.In the limit of zero infrared cut-off the propagator vanishes with a new kind of infrared behaviour.Comment: 22pages,4figures,revtex4,Notational sloppiness are crrected.Submitted to JHE
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