547 research outputs found

    The Kindergarten Journal, Summer 1910

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    Includes the essay, The Value of Character , by Elizabeth Harrison (page 28), Personal Mention (page 20) and Alumnae Report (page 29) by Edna Dean Baker, and Extension (page 25) by J.N. Crouse, co-principal of the Chicago Kindergarten College. Journal editors: Mrs. Todd Lunsford and Mrs. Florence Capronhttps://digitalcommons.nl.edu/harrison-writings/1029/thumbnail.jp

    Reconstruction of Black Hole Metric Perturbations from Weyl Curvature

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    Perturbation theory of rotating black holes is usually described in terms of Weyl scalars ψ4\psi_4 and ψ0\psi_0, which each satisfy Teukolsky's complex master wave equation and respectively represent outgoing and ingoing radiation. On the other hand metric perturbations of a Kerr hole can be described in terms of (Hertz-like) potentials Κ\Psi in outgoing or ingoing {\it radiation gauges}. In this paper we relate these potentials to what one actually computes in perturbation theory, i.e ψ4\psi_4 and ψ0\psi_0. We explicitly construct these relations in the nonrotating limit, preparatory to devising a corresponding approach for building up the perturbed spacetime of a rotating black hole. We discuss the application of our procedure to second order perturbation theory and to the study of radiation reaction effects for a particle orbiting a massive black hole.Comment: 6 Pages, Revtex

    Limits on Electron-Neutrino Oscillations from the GALLEX 51^{51}Cr Source Experiment

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    The recent result from the chromium source experiment carried out by the GALLEX collaboration implies interesting limits on the parameters Δm2\Delta m^2 and sin⁡22ξ\sin^22\theta describing neutrino oscillations. Values of Δm2 > 0.17\Delta m^2~>~0.17 eV2^2 for maximal mixing and of sin⁡22ξ>0.38\sin^22\theta > 0.38 for Δm2>1\Delta m^2 > 1~eV2^2 are ruled out at 90\% C.L. This result improves by more than an order of magnitude previous limits on Δm2\Delta m^2 derived from electron-neutrino oscillation experiments at accelerators.Comment: 6 pages (REVTEX) + one figure (postscript), all in uuencoded forma

    ASTEC -- the Aarhus STellar Evolution Code

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    The Aarhus code is the result of a long development, starting in 1974, and still ongoing. A novel feature is the integration of the computation of adiabatic oscillations for specified models as part of the code. It offers substantial flexibility in terms of microphysics and has been carefully tested for the computation of solar models. However, considerable development is still required in the treatment of nuclear reactions, diffusion and convective mixing.Comment: Astrophys. Space Sci, in the pres

    The imposition of Cauchy data to the Teukolsky equation I: The nonrotating case

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    Gravitational perturbations about a Kerr black hole in the Newman-Penrose formalism are concisely described by the Teukolsky equation. New numerical methods for studying the evolution of such perturbations require not only the construction of appropriate initial data to describe the collision of two orbiting black holes, but also to know how such new data must be imposed into the Teukolsky equation. In this paper we show how Cauchy data can be incorporated explicitly into the Teukolsky equation for non-rotating black holes. The Teukolsky function % \Psi and its first time derivative ∂tι\partial_t \Psi can be written in terms of only the 3-geometry and the extrinsic curvature in a gauge invariant way. Taking a Laplace transform of the Teukolsky equation incorporates initial data as a source term. We show that for astrophysical data the straightforward Green function method leads to divergent integrals that can be regularized like for the case of a source generated by a particle coming from infinity.Comment: 9 pages, REVTEX. Misprints corrected in formulas (2.4)-(2.7). Final version to appear in PR

    Analysis of Complex Inflatable Structures Using a Multi-Body Dynamics Approach

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    The analysis of facial beauty: an emerging area of research in pattern analysis

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    Much research presented recently supports the idea that the human perception of attractiveness is data-driven and largely irrespective of the perceiver. This suggests using pattern analysis techniques for beauty analysis. Several scientific papers on this subject are appearing in image processing, computer vision and pattern analysis contexts, or use techniques of these areas. In this paper, we will survey the recent studies on automatic analysis of facial beauty, and discuss research lines and practical application

    Protein sequence and structure: Is one more fundamental than the other?

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    We argue that protein native state structures reside in a novel "phase" of matter which confers on proteins their many amazing characteristics. This phase arises from the common features of all globular proteins and is characterized by a sequence-independent free energy landscape with relatively few low energy minima with funnel-like character. The choice of a sequence that fits well into one of these predetermined structures facilitates rapid and cooperative folding. Our model calculations show that this novel phase facilitates the formation of an efficient route for sequence design starting from random peptides.Comment: 7 pages, 4 figures, to appear in J. Stat. Phy

    Observation of the Ankle and Evidence for a High-Energy Break in the Cosmic Ray Spectrum

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    We have measured the cosmic ray spectrum at energies above 101710^{17} eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric calibrations, and the analysis techniques for the two detectors. We fit the spectrum to models describing galactic and extragalactic sources. Our measured spectrum gives an observation of a feature known as the ``ankle'' near 3×10183\times 10^{18} eV, and strong evidence for a suppression near 6×10196\times 10^{19} eV.Comment: 14 pages, 9 figures. To appear in Physics Letters B. Accepted versio
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