3,752 research outputs found

    Financing Public Broadcasting

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    Self-Similar Random Processes and Infinite-Dimensional Configuration Spaces

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    We discuss various infinite-dimensional configuration spaces that carry measures quasiinvariant under compactly-supported diffeomorphisms of a manifold M corresponding to a physical space. Such measures allow the construction of unitary representations of the diffeomorphism group, which are important to nonrelativistic quantum statistical physics and to the quantum theory of extended objects in d-dimensional Euclidean space. Special attention is given to measurable structure and topology underlying measures on generalized configuration spaces obtained from self-similar random processes (both for d = 1 and d > 1), which describe infinite point configurations having accumulation points

    Some Variations on Maxwell's Equations

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    In the first sections of this article, we discuss two variations on Maxwell's equations that have been introduced in earlier work--a class of nonlinear Maxwell theories with well-defined Galilean limits (and correspondingly generalized Yang-Mills equations), and a linear modification motivated by the coupling of the electromagnetic potential with a certain nonlinear Schroedinger equation. In the final section, revisiting an old idea of Lorentz, we write Maxwell's equations for a theory in which the electrostatic force of repulsion between like charges differs fundamentally in magnitude from the electrostatic force of attraction between unlike charges. We elaborate on Lorentz' description by means of electric and magnetic field strengths, whose governing equations separate into two fully relativistic Maxwell systems--one describing ordinary electromagnetism, and the other describing a universally attractive or repulsive long-range force. If such a force cannot be ruled out {\it a priori} by known physical principles, its magnitude should be determined or bounded experimentally. Were it to exist, interesting possibilities go beyond Lorentz' early conjecture of a relation to (Newtonian) gravity.Comment: 26 pages, submitted to a volume in preparation to honor Gerard Emch v. 2: discussion revised, factors of 4\pi corrected in some equation

    Gauge Transformations in Quantum Mechanics and the Unification of Nonlinear Schr\"odinger Equations

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    Beginning with ordinary quantum mechanics for spinless particles, together with the hypothesis that all experimental measurements consist of positional measurements at different times, we characterize directly a class of nonlinear quantum theories physically equivalent to linear quantum mechanics through nonlinear gauge transformations. We show that under two physically-motivated assumptions, these transformations are uniquely determined: they are exactly the group of time-dependent, nonlinear gauge transformations introduced previously for a family of nonlinear Schr\"odinger equations. The general equation in this family, including terms considered by Kostin, by Bialynicki-Birula and Mycielski, and by Doebner and Goldin, with time-dependent coefficients, can be obtained from the linear Schr\"odinger equation through gauge transformation and a subsequent process we call gauge generalization. We thus unify, on fundamental grounds, a rather diverse set of nonlinear time-evolutions in quantum mechanics.Comment: RevTeX, 20 pages, no figures. also available on http://www.pt.tu-clausthal.de/preprints/asi-tpa/021-96.htm

    Antinuclear antibodies (ANA) in chronic hepatitis C virus infection: correlates of positivity and clinical relevance.

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    We examined correlates of antinuclear antibody (ANA) positivity (ANA+) in individuals with chronic hepatitis C virus (HCV) infection and the effect of positivity on clinical outcome of HCV. Pretreatment sera from 645 patients from three centres in Sweden (n = 225), the UK (n = 207) and Italy (n = 213) were evaluated by indirect immunofluorescence on Hep-2 cells for ANA pattern and titre by a single laboratory. Liver biopsies were all scored by one pathologist. A total of 258 patients were subsequently treated with interferon monotherapy. There was a significant difference in the prevalence of ANA (1:40) by geographic location: Lund 4.4%, London 8.7%, Padova 10.3% [odds ratio (OR) = 0.66; 95% CI: 0.46-0.94; P = 0.023]. Duration of HCV infection, age at infection, current age, route of infection, viral genotype, alcohol consumption, fibrosis stage and inflammatory score were not correlated with ANA+ or ANA pattern. Female gender was correlated with ANA+ and this association persisted in multivariable analyses (OR = 3.0; P = 0.002). Increased plasma cells were observed in the liver biopsies of ANA-positive individuals compared with ANA-negative individuals, while a trend towards decreased lymphoid aggregates was observed [hazard ratio (HR) = 9.0, P = 0.037; HR = 0.291, P = 0.118, respectively]. No correlations were observed between ANA positivity and nonresponse to therapy (OR = 1.4; P = 0.513), although ANA+ was correlated with faster rates of liver fibrosis, this was not statistically significant (OR = 1.8; P = 0.1452). Low titre ANA+ should not be a contraindication for interferon treatment. Our observation of increased plasma cells in ANA+ biopsies might suggest B-cell polyclonal activity with a secondary clinical manifestation of increased serum immunoglobulins

    On the virial coefficients of nonabelian anyons

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    We study a system of nonabelian anyons in the lowest Landau level of a strong magnetic field. Using diagrammatic techniques, we prove that the virial coefficients do not depend on the statistics parameter. This is true for all representations of all nonabelian groups for the statistics of the particles and relies solely on the fact that the effective statistical interaction is a traceless operator.Comment: 9 pages, 3 eps figure

    Intensity-Modulated Radiation Therapy, Proton Therapy, or Conformal Radiation Therapy and Morbidity and Disease Control in Localized Prostate Cancer

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    There has been rapid adoption of newer radiation treatments such as intensitymodulated radiation therapy (IMRT) and proton therapy despite greater cost and limited demonstrated benefit compared with previous technologies
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