54,623 research outputs found

    Research study of an aircraft-contained radar zero-zero landing system, volume 1 Final report, Jan. - Dec. 1967

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    Two rapid scan radar/display techniques evaluated for use in aircraft-contained zero-zero landing syste

    Research study of an aircraft-contained radar zero-zero landing system, volume 2 Final report, Jan. - Dec. 1967

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    Conceptual development of long wave radar display based on processed plan position indicator and cross beam raster scan technique

    Skeletal stressing method and apparatus Patent

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    Method and apparatus for applying compressional forces to skeletal structure of subject to simulate force during ambulatory condition

    Weight simulator

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    Device applies compressive force to bone to minimize loss of bone calcium during weightlessness or bedrest. Force is applied through weights, or hydraulic, pneumatic or electrically actuated devices. Device is lightweight and easy to maintain and operate

    Chiral extrapolation and physical insights

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    It has recently been established that finite-range regularisation in chiral effective field theory enables the accurate extrapolation of modern lattice QCD results to the chiral regime. We review some of the highlights of extrapolations of quenched lattice QCD results, including spectroscopy and magnetic moments. The Δ\Delta resonance displays peculiar chiral features in the quenched theory which can be exploited to demonstrate the presence of significant chiral corrections.Comment: 6 pages, 5 figures, presented at LHP2003, Cairns, Australi

    Hadron structure on the back of an envelope

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    In order to remove a little of the mysticism surrounding the issue of strangeness in the nucleon, we present simple, physically transparent estimates of both the strange magnetic moment and charge radius of the proton. Although simple, the estimates are in quite good agreement with sophisticated calculations using the latest input from lattice QCD. We further explore the possible size of systematic uncertainties associated with charge symmetry violation (CSV) in the recent precise determination of the strange magnetic moment of the proton. We find that CSV acts to increase the error estimate by 0.003 \mu_N such that G_M^s = -0.046 +/- 0.022 \mu_N.Comment: 9 pages, 1 figure, Invited talk at First Workshop on Quark-Hadron Duality and the Transition to pQCD, Frascati, June 6-8 200

    Chiral Symmetry and the Intrinsic Structure of the Nucleon

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    Understanding hadron structure within the framework of QCD is an extremely challenging problem. In order to solve it, it is vital that our thinking should be guided by the best available insight. Our purpose here is to explain the model independent consequences of the approximate chiral symmetry of QCD for two famous results concerning the structure of the nucleon. We show that both the apparent success of the constituent quark model in reproducing the ratio of the proton to neutron magnetic moments and the apparent success of the Foldy term in reproducing the observed charge radius of the neutron are coincidental. That is, a relatively small change of the current quark mass would spoil both results.Comment: RevTeX, 10 pages, 2 figure

    Extrapolation of lattice QCD results beyond the power-counting regime

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    Resummation of the chiral expansion is necessary to make accurate contact with current lattice simulation results of full QCD. Resummation techniques including relativistic formulations of chiral effective field theory and finite-range regularization (FRR) techniques are reviewed, with an emphasis on using lattice simulation results to constrain the parameters of the chiral expansion. We illustrate how the chiral extrapolation problem has been solved and use FRR techniques to identify the power-counting regime (PCR) of chiral perturbation theory. To fourth-order in the expansion at the 1% tolerance level, we find 0 \le m_pi \le 0.18 GeV for the PCR, extending only a small distance beyond the physical pion mass.Comment: 12 pages, 5 figures, plenary talk at BARYONS 2004, Paris, Oct. 25-2

    Evaluation of dry lubricants and bearings for spacecraft applications

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    Performance of dry film lubricated ball bearings in high vacuum environmen
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