4,523 research outputs found

    Evidence for prevention and screening: recommendations in adults.

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    A growing body of evidence supports preventive interventions in asymptomatic adults. Primary prevention, which includes counselling (in particular for smoking cessation) and review of immunisation status, has been shown to be more cost-effective than secondary prevention. Evidence supports screening for hypertension, hyperlipidaemia, cervical cancer, colorectal cancer, breast cancer and obesity. Screening for lung, pancreatic and ovarian cancer has no effect on outcome and should not be performed. Controversial preventive interventions include general screening for diabetes mellitus, thyroid disorders and prostate cancer. Physicians should be aware of a possible hidden agenda in patients presenting for a checkup

    Equation of motion for a domain wall coupled to gravitational field

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    The equation of motion for a domain wall coupled to gravitational field is derived from the Nambu-Goto action. The domain wall is treated as a source of gravitational field. The perturbed equation is also obtained with gravitational back reaction on the wall motion taken into account. For general spherically symmetric background case, the equation is expressed in terms of the gauge-invariant variables.Comment: 13 pages, latex, no figures, uses REVTe

    An Observational Test of Two-field Inflation

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    We study adiabatic and isocurvature perturbation spectra produced by a period of cosmological inflation driven by two scalar fields. We show that there exists a model-independent consistency condition for all two-field models of slow-roll inflation, despite allowing for model-dependent linear processing of curvature and isocurvature perturbations during and after inflation on super-horizon scales. The scale-dependence of all spectra are determined solely in terms of slow-roll parameters during inflation and the dimensionless cross-correlation between curvature and isocurvature perturbations. We present additional model-dependent consistency relations that may be derived in specific two-field models, such as the curvaton scenario.Comment: 6 pages, latex with revtex, no figures; v2, minor changes, to appear in Physical Review

    Structural and magnetic properties of E-Fe_{1-x}Co_xSi thin films deposited via pulsed laser deposition

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    We report pulsed laser deposition synthesis and characterization of polycrystalline Fe1-xCox Si thin films on Si (111). X-ray diffraction, transmission electron, and atomic force microscopies reveal films to be dense, very smooth, and single phase with a cubic B20 crystal structure. Ferromagnetism with significant magnetic hysteresis is found for all films including nominally pure FeSi films in contrast to the very weak paramagnetism of bulk FeSi. For Fe1-xCoxSi this signifies a change from helimagnetism in bulk, to ferromagnetism in thin films. These ferromagnetic thin films are promising as a magnetic-silicide/silicon system for polarized current production, manipulation, and detection.Comment: 12 pages, 4 figures accepted in the Applied Physics Letter

    SO(10) Cosmic Strings and SU(3) Color Cheshire Charge

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    Certain cosmic strings that occur in GUT models such as SO(10)SO(10) can carry a magnetic flux which acts nontrivially on objects carrying SU(3)colorSU(3)_{color} quantum numbers. We show that such strings are non-Abelian Alice strings carrying nonlocalizable colored ``Cheshire" charge. We examine claims made in the literature that SO(10)SO(10) strings can have a long-range, topological Aharonov-Bohm interaction that turns quarks into leptons, and observe that such a process is impossible. We also discuss flux-flux scattering using a multi-sheeted formalism.Comment: 37 Pages, 8 Figures (available upon request) phyzzx, iassns-hep-93-6, itp-sb-93-6

    Gravity Waves from Instantons

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    We perform a first principles computation of the spectrum of gravity waves produced in open inflationary universes. The background spacetime is taken to be the continuation of an instanton saddle point of the Euclidean no boundary path integral. The two-point tensor correlator is computed directly from the path integral and is shown to be unique and well behaved in the infrared. We discuss the tensor contribution to the cosmic microwave background anisotropy and show how it may provide an observational discriminant between different types of primordial instantons.Comment: 19 pages, RevTex file, including two postscript figure file

    Upper Limit on the molecular resonance strengths in the 12{}^{12}C+12{}^{12}C fusion reaction

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    Carbon burning is a crucial process for a number of important astrophysical scenarios. The lowest measured energy is around Ec.m._{\rm c.m.}=2.1 MeV, only partially overlapping with the energy range of astrophysical interest. The currently adopted reaction rates are based on an extrapolation which is highly uncertain because of potential resonances existing in the unmeasured energy range and the complication of the effective nuclear potential. By comparing the cross sections of the three carbon isotope fusion reactions, 12{}^{12}C+12{}^{12}C, 12{}^{12}C+13{}^{13}C and 13{}^{13}C+13{}^{13}C, we have established an upper limit on the molecular resonance strengths in 12{}^{12}C+12{}^{12}C fusion reaction. The preliminary results are presented and the impact on nuclear astrophysics is discussed.Comment: 4 pages, 3 figures, FUSION11 conference proceedin

    Optical study of the electronic phase transition of strongly correlated YbInCu_4

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    Infrared, visible and near-UV reflectivity measurements are used to obtain conductivity as a function of temperature and frequency in YbInCu_4, which exhibits an isostructural phase-transition into a mixed-valent phase below T_v=42 K. In addition to a gradual loss of spectral weight with decreasing temperature extending up to 1.5 eV, a sharp resonance appears at 0.25 eV in the mixed-valent phase. This feature can be described in terms of excitations into the Kondo (Abrikosov-Suhl) resonance, and, like the sudden reduction of resistivity, provides a direct reflection of the onset of coherence in this strongly correlated electron system.Comment: 4 pages, 3 figures (to appear in Phys. Rev. B

    Bubble wall perturbations coupled with gravitational waves

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    We study a coupled system of gravitational waves and a domain wall which is the boundary of a vacuum bubble in de Sitter spacetime. To treat the system, we use the metric junction formalism of Israel. We show that the dynamical degree of the bubble wall is lost and the bubble wall can oscillate only while the gravitational waves go across it. It means that the gravitational backreaction on the motion of the bubble wall can not be ignored.Comment: 23 pages with 3 eps figure

    Thermo-mechanical behaviour of a compacted swelling clay

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    Compacted unsaturated swelling clay is often considered as a possible buffer material for deep nuclear waste disposal. An isotropic cell permitting simultaneous control of suction, temperature and pressure was used to study the thermo-mechanical behaviour of this clay. Tests were performed at total suctions ranging from 9 to 110 MPa, temperature from 25 to 80 degrees C, isotropic pressure from 0.1 to 60 MPa. It was observed that heating at constant suction and pressure induces either swelling or contraction. The results from compression tests at constant suction and temperature evidenced that at lower suction, the yield pressure was lower, the elastic compressibility parameter and the plastic compressibility parameter were higher. On the other hand, at a similar suction, the yield pressure was slightly influenced by the temperature; and the compressibility parameters were insensitive to temperature changes. The thermal hardening phenomenon was equally evidenced by following a thermo-mechanical path of loading-heating-cooling-reloading
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