1,463 research outputs found

    Quantitative Magnetic Resonance Angiography

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    Angular momentum non-conserving decays in isotropic media

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    Various processes that are forbidden in the vacuum due to angular momentum conservation can occur in a medium that is isotropic and does not carry any angular momentum. We illustrate this by considering explicitly two examples. The first one is the decay of a spin-0 particle into a photon and another spin-0 particle, using a model involving the Yukawa interactions of the scalar particles with a charged fermion field. The second one involves the decay of a neutrino into another neutrino and a graviton, in the standard model of particle interactions augmented with the linearized gravitational couplings.Comment: 22 pages, Latex, uses axodraw.sty. 3 figures embedded in the tex file. This paper contains the same material as that presented in two earlier papers, arXiv:0901.2981 and arXiv:0901.2982, written by us. This version supersedes those two paper

    ECONOMIC ANALYSIS OF TEMIK ON CITRUS IN THE INDIAN RIVER AREA IN SOUTHEASTERN FLORIDA

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    Temik [R](aldicarb) is a pesticide labeled for use on several citrus crops to control rust mite, whitefly, nematode and brown citrus aphid pests. Analysis of previous research experiments indicates that this pesticide is beneficial to both orange and grapefruit production and that both cost savings and higher yields can be experienced in many types of groves. Actual grove data shows that net returns for mature grapefruit that receive Temik [R] can be $500 per acre greater than net returns for identical acreage that uses other pest control options. Also, based on grove reset data it is shown that with an application of Temik [R] the resulting increased yields for three-year-old trees more than cover the additional cost of applying the Temik [R].mature citrus, resets, revenue-cost, net return, grapefruit, Crop Production/Industries,

    A feasibility study of a hypersonic real-gas facility

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    A four month feasibility study of a hypersonic real-gas free flight test facility for NASA Langley Research Center (LARC) was performed. The feasibility of using a high-energy electromagnetic launcher (EML) to accelerate complex models (lifting and nonlifting) in the hypersonic, real-gas facility was examined. Issues addressed include: design and performance of the accelerator; design and performance of the power supply; design and operation of the sabot and payload during acceleration and separation; effects of high current, magnetic fields, temperature, and stress on the sabot and payload; and survivability of payload instrumentation during acceleration, flight, and soft catch

    A study of the applicability/compatibility of inertial energy storage systems to future space missions

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    The applicability/compatibility of inertial energy storage systems like the homopolar generator (HPG) and the compensated pulsed alternator (CPA) to future space missions is explored. Areas of CPA and HPG design requiring development for space applications are identified. The manner in which acceptance parameters of the CPA and HPG scale with operating parameters of the machines are explored and the types of electrical loads which are compatible with the CPA and HPG are examined. Potential applications including the magnetoplasmadynamic (MPD) thruster, pulsed data transmission, laser ranging, welding and electromagnetic space launch are discussed

    Gauge Independence of Limiting Cases of One-Loop Electron Dispersion Relation in High-Temperature QED

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    Assuming high temperature and taking subleading temperature dependence into account, gauge dependence of one-loop electron dispersion relation is investigated in massless QED at zero chemical potential. The analysis is carried out using a general linear covariant gauge. The equation governing the gauge dependence of the dispersion relation is obtained and used to prove that the dispersion relation is gauge independent in the limiting case of momenta much larger than eTeT. It is also shown that the effective mass is not influenced by the leading temperature dependence of the gauge dependent part of the effective self-energy. As a result the effective mass, which is of order eTeT, does not receive a correction of order e2Te^2T from one loop, independent of the gauge parameter.Comment: Revised and enlarged version, 14 pages, Revte

    On finite--temperature and --density radiative corrections to the neutrino effective potential in the early Universe

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    Finite-temperature and -density radiative corrections to the neutrino effective potential in the otherwise CP-symmetric early Universe are considered in the real-time approach of Thermal Field Theory. A consistent perturbation theory endowed with the hard thermal loop resummation techniques developed by Braaten and Pisarski is applied. Special attention is focused on the question whether such corrections can generate any nonzero contribution to the CP-symmetric part of the neutrino potential, if the contact approximation for the W-propagator is used.Comment: 11 pages, revtex styl

    The Boltzmann Equation in Scalar Field Theory

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    We derive the classical transport equation, in scalar field theory with a V(phi) interaction, from the equation of motion for the quantum field. We obtain a very simple, but iterative, expression for the effective action which generates all the n-point Green functions in the high-temperature limit. An explicit closed form is given in the static case.Comment: 10 pages, using RevTeX (corrected TeX misprints
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