2,340 research outputs found

    Positive fast sealing union connections

    Get PDF
    Union connections are designed for connecting high pressure flexible hoses from gas storage manifolds to gas transport trailers. Connection uses O ring seals which can be quickly assembled and disassembled without use of wrenches, and which do not twist hose. Worn or damaged O rings are easily replaced

    Lorentz-violating effects in the Bose-Einstein condensation of an ideal bosonic gas

    Full text link
    We have studied the effects of Lorentz-violation in the Bose-Einstein condensation (BEC) of an ideal boson gas, by assessing both the nonrelativistic and ultrarelativistic limits. Our model describes a massive complex scalar field coupled to a CPT-even and Lorentz-violating background. We irst analyze the nonrelativistic case, at this level by using experimental data, we obtain upper-bounds for some LIV parameters. In the sequel, we have constructed the partition function for the relativistic ideal boson gas which to be able of a consistent description requires the imposition of severe restrictions on some LIV coefficients. In both cases, we have demonstrated that the LIV contributions are contained in an overall factor, which multiplies almost all thermodynamical properties. An exception is the fraction of the condensed particles.Comment: 7 pages Latex2e. To be published in Modern Physics Letters

    Temperature dependence of chemical and biophysical rate processes: Phenomenological approach to deviations from Arrhenius law

    Get PDF
    Arrhenius plots, which are used to represent the effects of temperature on the rates of chemical and biophysical processes and on various transport phenomena in materials science, may exhibit deviations from linearity. Account of curvature is provided here by a formula which involves a deformation of the exponential function, of the kind recently encountered in treatments of non-extensivity in statistical mechanics. We present here examples on diverse topics – respiration rates of plants, speed of gliding of bacteria, quantum mechanical tunneling in a chemical reaction – illustrating the variety of possible applications and the additional insight that can be gained

    Four-path interference and uncertainty principle in photodetachment microscopy

    Full text link
    We study the quantal motion of electrons emitted by a pointlike monochromatic isotropic source into parallel uniform electric and magnetic fields. The two-path interference pattern in the emerging electron wave due to the electric force is modified by the magnetic lens effect which periodically focuses the beam into narrow filaments along the symmetry axis. There, four classical paths interfere. With increasing electron energy, the current distribution changes from a quantum regime governed by the uncertainty principle, to an intricate spatial pattern that yields to a semiclassical analysis.Comment: submitted to Europhysics Letter

    Gravitational magnetic monopoles and Majumdar-Papapetrou stars

    Full text link
    A large amount of work has been dedicated to studying general relativity coupled to non-Abelian Yang-Mills type theories. It has been shown that the magnetic monopole, a solution of the Yang-Mills-Higgs equations can be coupled to gravitation. For a low Higgs mass there are regular solutions, and for a sufficiently massive monopole the system develops an extremal magnetic Reissner-Nordstrom quasi-horizon. These solutions, called quasi-black holes, although non-singular, are arbitrarily close to having a horizon. However, at the critical value the quasi-black hole turns into a degenerate spacetime. On the other hand, for a high Higgs mass, a sufficiently massive monopole develops also a quasi-black hole, but it turns into an extremal true horizon, with matter fields outside. One can also put a small Schwarzschild black hole inside the magnetic monopole, an example of a non-Abelian black hole. Surprisingly, Majumdar-Papapetrou systems, Abelian systems constructed from extremal dust, also show a resembling behavior. Previously, we have reported that one can find Majumdar-Papapetrou solutions which can be arbitrarily close of being a black hole, displaying quasi-black hole behavior. With the aim of better understanding the similarities between gravitational monopoles and Majumdar-Papapetrou systems, we study a system composed of two extremal electrically charged spherical shells (or stars, generically) in the Einstein--Maxwell--Majumdar-Papapetrou theory. We review the gravitational properties of the monopoles, and compare with the properties of the double extremal electric shell system. These quasi-black holes can help in the understanding of true black holes, and can give insight into the nature of the entropy of black holes in the form of entanglement.Comment: 38 pages,9 Figures, minor change

    Exposure to violence and PTSD symptoms among Somali women

    Get PDF
    Posttraumatic stress disorder (PTSD) symptoms, exposure to traumatic stressors, and health care utilization were examined in 84 women attending a primary health care clinic in Mogadishu, Somalia. The Somalia-Posttraumatic Diagnostic Scale was used in this active warzone to measure symptoms. Nearly all women reported high levels of confrontations with violence; half described being exposed to a potentially traumatizing event. Nearly one third had significant PTSD symptoms. Compared to those who did not, women who reported exposure to a traumatic stressor reported more confrontations with violence (7.1 vs. 3.3; p < . 001), health complaints (3.8 vs. 2.9; p = .03), and nearly 3 times as much (p = .03) health service utilization. A potentially traumatizing event was found to be a simplified proxy for assessing mental health distress in women attending a primary health care facility in highly insecure, unpredictable, resource-limited settings

    High pressure torsion of nickel powders obtained by electrodeposition

    Get PDF
    A new synthesis route for the production of bulk nanostructured materials is presented. Fine Ni powder was made by selected appropriate electrolysis conditions. A compact material with an average grain size below 40 nm was obtained by subsequent cold pressing. Then, using the high pressure torsion (HPT) deformation technique dense bulk nanocrystalline Ni was achieved. The detailed structural investigations of the asprepared and HPT deformed Ni powder, including X-ray diffraction (XRD) and transmission electron microscopy (TEM), reveal in both cases the presence of a face centered cubic (FCC) phase without presence of any oxides. Coherently scattering domain size measurements by XRD show a value of 24 nm for the as-deposited powder and an even smaller value of 13.5 nm after HPT deformation. In addition, optical emission spectroscopy was employed to determine the impurity content of the obtained nanostructured material, showing a relatively low content of 0.9 % carbon and oxygen. The microhardness increased after deformation from (1.5 ± 0.08) GPa for the as-deposited Ni powder to (6.6 ± 0.2) GPa for the HPT deformed Ni powder. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2061
    corecore