2,807 research outputs found

    Studies of parton distributions at a neutrino factory

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    The determination of parton distribution functions in the nucleon and nuclei is important for obtaining precise hadron-reaction cross sections, from which any new exotic signature could be found. We show that a future neutrino factory could provide important information on the parton distributions. First, a recent effort concerning the parametrization of nuclear parton distributions is explained. It suggests that the factory should be important for determining unknown behavior of valence-quark distributions in nuclei at small xx. Second, the facility could be used for understanding nucleon spin structure and isospin violation in the parton distributions.Comment: 1+3 pages, LaTeX2e, elsart.cls, wrapfig.sty, 1 eps figure. Talk given at the Third International Workshop on Neutrino Factories based on Muon Storage Rings (NuFACT'01), May 24 - 30, 2001, Tsukuba, Japan. To be published in proceedings. Email: [email protected], WWW: http://hs.phys.saga-u.ac.j

    Cosmological Implications of the Tetron Model of Elementary Particles

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    Based on a possible solution to the tetron spin problem, a modification of the standard Big Bang scenario is suggested, where the advent of a spacetime manifold is connected to the appearance of tetronic bound states. The metric tensor is constructed from tetron constituents and the reason for cosmic inflation is elucidated. Furthermore, there are natural dark matter candidates in the tetron model. The ratio of ordinary to dark matter in the universe is calculated to be 1:5.Comment: 23 page

    Cholesterol and coronary heart disease: screening and treatment

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    Coronary heart disease (CHD) is a major cause of morbidity and mortality in the United Kingdom, accounting for just under one quarter of all deaths in 1995: 27% among men and 21% among women.1 Although many CHD deaths occur among elderly people, CHD accounts for 31% of male and 13% of female deaths within the 45–64 age group

    Polarized top decay into polarized W: t(up)->W(up) + b at O(alpha_s)

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    We consider the decay of a polarized top quark into a polarized W-boson plus a bottom quark, followed by the decay of the W-boson into a pair of leptons or quarks. The polar angle distribution of the top spin relative to the W-momentum and the polar angle distribution of the lepton (or quark) in the W-rest frame is governed by three polarized and three unpolarized rate functions which are related to the double density matrix elements of the decay tW++bt \to W^+ + b. We obtain analytical expressions for the O(αs)O(\alpha_s) radiative corrections to the three polarized and three unpolarized rate functions. We also provide a comprehensive discussion of the dependence of the longitudinal, transverse and normal polarization of the top quarks produced at e+ee^+e^--colliders on beam polarization parameters.Comment: 13 pages, 3 postscript figures added, file standard.sty included, material on normal polarization added, some misprints correcte

    MOD-0A 200 kW wind turbine generator design and analysis report

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    The design, analysis, and initial performance of the MOD-OA 200 kW wind turbine generator at Clayton, NM is documented. The MOD-OA was designed and built to obtain operation and performance data and experience in utility environments. The project requirements, approach, system description, design requirements, design, analysis, system tests, installation, safety considerations, failure modes and effects analysis, data acquisition, and initial performance for the wind turbine are discussed. The design and analysis of the rotor, drive train, nacelle equipment, yaw drive mechanism and brake, tower, foundation, electricl system, and control systems are presented. The rotor includes the blades, hub, and pitch change mechanism. The drive train includes the low speed shaft, speed increaser, high speed shaft, and rotor brake. The electrical system includes the generator, switchgear, transformer, and utility connection. The control systems are the blade pitch, yaw, and generator control, and the safety system. Manual, automatic, and remote control are discussed. Systems analyses on dynamic loads and fatigue are presented

    The MOD-OA 200 kilowatt wind turbine generator design and analysis report

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    The project requirements, approach, system description, design requirements, design, analysis, system tests, installation safety considerations, failure modes and effects analysis, data acquisition, and initial performance for the MOD-OA 200 kw wind turbine generator are discussed. The components, the rotor, driven train, nacelle equipment, yaw drive mechanism and brake, tower, foundation, electrical system, and control systems are presented. The rotor includes the blades, hub and pitch change mechanism. The drive train includes the low speed shaft, speed increaser, high speed shaft, and rotor brake. The electrical system includes the generator, switchgear, transformer, and utility connection. The control systems are the blade pitch, yaw, and generator control, and the safety system. Manual, automatic, and remote control and Dynamic loads and fatigue are analyzed

    New proton polarized structure functions in charged current processes at HERA

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    Estimates for longitudinal spin asymmetries which single out new polarized nucleon structure functions in deeply inelastic charged current interactions at HERA energies are given, exploiting their interpretation in terms of polarized quark distributions. These asymmetries turn out to be large and allow a measurement of the new polarized structure functions g1Wg_1^{W} and g5Wg_5^{W}, which would add valuable tests and information on the spin content of quarks inside a polarized proton. We also show that single spin asymmetries in neutral current interactions are very small.Comment: LaTeX, 8 pages, 6 figure

    The development of a ε-polycaprolactone (PCL) scaffold for CNS repair

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    Potential treatment strategies for the repair of spinal cord injury (SCI) currently favour a combinatorial approach incorporating several factors, including exogenous cell transplantation and biocompatible scaffolds. The use of scaffolds for bridging the gap at the injury site is very appealing although there has been little investigation into CNS neural cell interaction and survival on such scaffolds before implantation. Previously we demonstrated that aligned micro-grooves 12.5-25 µm wide on ε-polycaprolactone (PCL) promoted aligned neurite orientation and supported myelination. In this study we identify the appropriate substrate and its topographical features required for the design of a 3D scaffold intended for transplantation in SCI. Using an established myelinating culture system of dissociated spinal cord cells, recapitulating many of the features of the intact spinal cord, we demonstrate that astrocytes plated on the topography secrete soluble factors(s) that delay oligodendrocyte differentiation but do not prevent myelination. However, as myelination does occur after a further 10-12 days in culture this does not prevent the use of PCL as a scaffold material as part of a combined strategy for the repair of SCI
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