5,099 research outputs found

    The search for the Standard Model Higgs at the Tevatron

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    I present a short summary of the Higgs searches at the Tevatron as of Summer 2011. In this paper I will highlight a few turning points of this search

    Universal Properties of Galactic Rotation Curves and a First Principles Derivation of the Tully-Fisher Relation

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    In a recent paper McGaugh, Lelli, and Schombert showed that in an empirical plot of the observed centripetal accelerations in spiral galaxies against those predicted by the Newtonian gravity of the luminous matter in those galaxies the data points occupied a remarkably narrow band. While one could summarize the mean properties of the band by drawing a single mean curve through it, by fitting the band with the illustrative conformal gravity theory with fits that fill out the width of the band we show here that the width of the band is just as physically significant. We show that at very low luminous Newtonian accelerations the plot can become independent of the luminous Newtonian contribution altogether, but still be non-trivial due to the contribution of matter outside of the galaxies (viz. the rest of the visible universe). We present a new empirical plot of the difference between the observed centripetal accelerations and the luminous Newtonian expectations as a function of distance from the centers of galaxies, and show that at distances greater than 10 kpc the plot also occupies a remarkably narrow band, one even close to constant. Using the conformal gravity theory we provide a first principles derivation of the empirical Tully-Fisher relation.Comment: 6 pages, 15 figures. The paper is a comment on S. S. McGaugh, F. Lelli, and J. M. Schombert, Phys. Rev. Lett. 117, 201101 (2016). Updated to include a first principles derivation of the Tully-Fisher relation using the conformal gravity theory. Submitted to Physics Letters

    Liquid crystal anchoring transitions on aligning substrates processed by plasma beam

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    We observe a sequence of the anchoring transitions in nematic liquid crystals (NLC) sandwiched between the hydrophobic polyimide substrates treated with the plasma beam. There is a pronounced continuous transition from homeotropic to low tilted (nearly planar) alignment with the easy axis parallel to the incidence plane of the plasma beam (the zenithal transition) that takes place as the exposure dose increases. In NLC with positive dielectric anisotropy, a further increase in the exposure dose results in in-plane reorientation of the easy axis by 90 degrees (the azimuthal transition). This transition occurs through the two-fold degenerated alignment characteristic for the second order anchoring transitions. In contrast to critical behavior of anchoring, the contact angle of NLC and water on the treated substrates monotonically declines with the exposure dose. It follows that the surface concentration of hydrophobic chains decreases continuously. The anchoring transitions under consideration are qualitatively interpreted by using a simple phenomenological model of competing easy axes which is studied by analyzing anchoring diagrams of the generalized polar and non-polar anchoring models.Comment: revtex4, 18 pages, 10 figure

    Leukocyte adhesion deficiency disorder in an infant.

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    Leukocyte adhesion defect (LAD) is an inherited disorder of phagocytic function. The three different alpha-chains of the leukocyte integrin family (CD 11a, 11b, 11c) are all dependent on the common beta chain (CD18) for proper insertion into the cell membrane. Deficiency of CD 18 thus causes an inability to express any of these proteins and results in the syndrome of LAD type 1. Clinical features include delayed separation of the umbilical cord, persistent leukocytosis and recurrent infection. A case of severe LAD occurred in a 1 month-old infant. The immunological pattern of the baby showed pathological values of CD11b and CD18 (1.3% and 0.2% respectively) when compared with normal values (50-70%) and lack of random (1.0 nm vs normal of 10±5) and casein-induced (22.0 nm vs normal of 60-120nm) chemotaxis. The baby is now waiting for bone marrow transplantation. Although LAD is a rare form of congenital immune deficiency this disease should be considered when delayed wound healing and recurrent bacterial skin infections are present in a newborn


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    Oocyte quality is one of the main factors for the success of in vitro fertilization protocols. Apoptosis is known to affect oocyte quality and may impair subsequent embryonic development and implantation. The aim of this study was to investigate the apoptosis rate of single and pooled cumulus cells of cumulus cell\u2013oocyte complexes (COCs), as markers of oocyte quality, prior to intracytoplasmatic sperm injection (ICSI).We investigated the apoptosis rate by TUNEL assay (DNA fragmentation) and caspase-3 immunoassay of single and pooled cumulus cells of COCs. The results showed that DNA fragmentation in cumulus cells was remarkably lower in patients who achieved a pregnancy than in those who did not. Cumulus cell apoptosis rate could be a marker for the selection of the best oocytes to be fertilized by intracytoplasmatic sperm injection

    A New Configuration of Vertical Axis Wind Turbine: Towards the Development of a highly distributed and efficient Wind Power Generation

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    Preliminary results obtained for a new configuration lift based vertical-axis wind turbine are shown. The turbine rotor is a cross flow fan type made with high curvature aerodynamic profiles. A reduced scale model of the turbine rotor has been designed and preliminary tested at the Department of Aerospace Engineering of the University of Pisa (rotor diameter 250 mm, rotor height 210 mm). The reduced scale model shows an efficiency of about eighteen per cent. The rotor is of a self-starting type. Two-dimensional CFD analyses have been performed applying both the Moving Reference Frame and the Moving Mesh conditions to the grid which surrounds the rotor blades (Fluent® Rel. 6.3 and STAR-CCM+® Rel. 6.04 have been used). Noticeable scale effects have been found numerically, so, the efficiency of a full scale lift based vertical axis multi-blades optimized wind turbine is expected to be comparable with lift based horizontal-axis wind turbines
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