10,175 research outputs found

    An essay on character portrayal, style, and technique of writing in Maxwell Anderson\u27s biographical plays in verse

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    The purpose of this chapter is to acquaint the reader with the general scope and trend of Maxwell Anderson\u27s work in order to give a more complete conspectus for the discussion of his plays. By so doing a foundation will be laid for a more intelligible discussion of the specific aspects of the seven plays concerned in the thesis proper, the title of which is, An Essay on Character Portrayal, Style, and Technique of\u27 Writing in Maxwell Anderson\u27s Biographical Plays in Verse

    A Cosmic Microwave Background feature consistent with a cosmic texture

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    The Cosmic Microwave Background provides our most ancient image of the Universe and our best tool for studying its early evolution. Theories of high energy physics predict the formation of various types of topological defects in the very early universe, including cosmic texture which would generate hot and cold spots in the Cosmic Microwave Background. We show through a Bayesian statistical analysis that the most prominent, 5 degree radius cold spot observed in all-sky images, which is otherwise hard to explain, is compatible with having being caused by a texture. From this model, we constrain the fundamental symmetry breaking energy scale to be phi_0 ~ 8.7 x 10^(15) GeV. If confirmed, this detection of a cosmic defect will probe physics at energies exceeding any conceivable terrestrial experiment.Comment: Accepted by Science. Published electronically via Science Express on 25 October 2007, http://www.sciencemag.org/cgi/content/abstract/114869

    Computational science and re-discovery: open-source implementations of ellipsoidal harmonics for problems in potential theory

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    We present two open-source (BSD) implementations of ellipsoidal harmonic expansions for solving problems of potential theory using separation of variables. Ellipsoidal harmonics are used surprisingly infrequently, considering their substantial value for problems ranging in scale from molecules to the entire solar system. In this article, we suggest two possible reasons for the paucity relative to spherical harmonics. The first is essentially historical---ellipsoidal harmonics developed during the late 19th century and early 20th, when it was found that only the lowest-order harmonics are expressible in closed form. Each higher-order term requires the solution of an eigenvalue problem, and tedious manual computation seems to have discouraged applications and theoretical studies. The second explanation is practical: even with modern computers and accurate eigenvalue algorithms, expansions in ellipsoidal harmonics are significantly more challenging to compute than those in Cartesian or spherical coordinates. The present implementations reduce the "barrier to entry" by providing an easy and free way for the community to begin using ellipsoidal harmonics in actual research. We demonstrate our implementation using the specific and physiologically crucial problem of how charged proteins interact with their environment, and ask: what other analytical tools await re-discovery in an era of inexpensive computation?Comment: 25 pages, 3 figure

    Sommerfeld's image method in the calculation of van der Waals forces

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    We show how the image method can be used together with a recent method developed by C. Eberlein and R. Zietal to obtain the dispersive van der Waals interaction between an atom and a perfectly conducting surface of arbitrary shape. We discuss in detail the case of an atom and a semi- infinite conducting plane. In order to employ the above procedure to this problem it is necessary to use the ingenious image method introduced by Sommerfeld more than one century ago, which is a generalization of the standard procedure. Finally, we briefly discuss other interesting situations that can also be treated by the joint use of Sommerfeld's image technique and Eberlein-Zietal method.Comment: To appear in the proceedings of Conference on Quantum Field Theory under the Influence of External Conditions (QFEXT11

    Detection of the ISW effect and corresponding dark energy constraints made with directional spherical wavelets

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    Using a directional spherical wavelet analysis we detect the integrated Sachs-Wolfe (ISW) effect, indicated by a positive correlation between the first-year Wilkinson Microwave Anisotropy Probe (WMAP) and NRAO VLA Sky Survey (NVSS) data. Detections are made using both a directional extension of the spherical Mexican hat wavelet and the spherical butterfly wavelet. We examine the possibility of foreground contamination and systematics in the WMAP data and conclude that these factors are not responsible for the signal that we detect. The wavelet analysis inherently enables us to localise on the sky those regions that contribute most strongly to the correlation. On removing these localised regions the correlation that we detect is reduced in significance, as expected, but it is not eliminated, suggesting that these regions are not the sole source of correlation between the data. This finding is consistent with predictions made using the ISW effect, where one would expect weak correlations over the entire sky. In a flat universe the detection of the ISW effect provides direct and independent evidence for dark energy. We use our detection to constrain dark energy parameters by deriving a theoretical prediction for the directional wavelet covariance statistic for a given cosmological model. Comparing these predictions with the data we place constraints on the equation-of-state parameter ww and the vacuum energy density ΩΛ\Omega_\Lambda. We also consider the case of a pure cosmological constant, i.e. w=−1w=-1. For this case we rule out a zero cosmological constant at greater than the 99.9% significance level. All parameter estimates that we obtain are consistent with the standand cosmological concordance model values.Comment: 16 pages, 13 figures; replaced to match version accepted by MNRA

    Observations of Foraging Northern Fulmars (Fulmarus Glacialis) in the Canadian High Arctic

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    We summarize observations of foraging northern fulmars (Fulmarus glacialis) in the Barrow Strait-Lancaster Sound region of the Northwest Territories from June to September 1984-90 and in Admiralty Inlet, N.W.T., in July 1989. In each year, fulmars scavenged hunter-killed marine mammal remains in the vicinity of Resolute Bay. Large feeding flocks, aggregated primarily along tide lines and at upwelling sites, exploited primarily calanoid copepods by surface seizing and diving. Late-season onshore movement of Arctic cod (Boreogadus saida) resulted in flocks of several thousand fulmars capturing cod by surface and pursuit diving. We determined experimentally that northern fulmars are capable of diving to 3 m to retrieve cod.Key words: northern fulmar, Fulrmarus glacialis, feeding behaviour, diving, Barrow Strait, Lancaster SoundRÉSUMÉ. On résume les observations faites sur des fulmars boréaux (Fulmarus glacialis) en train de se ravitailler dans la région du détroit de Barrow et du détroit de Lancaster dans les Territoires du Nord-Ouest, de juin à septembre 1984 à 1990, et dans l'inlet de l'Amirauté (T.N.-O.) en juillet1989. Chaque année, les fulmars se repaissaient des restes de mammifères marins tués par des chasseurs à proximité de la baie Resolute. De grandes volées s'attroupaient pour se nourrir, surtout le long des laisses de marée et aux sites d'émergence, et pêchaient principalement des calanus,en les saisissant à la surface et en plongée. La migration de fin de saison de la morue polaire (Boreogadus saida) vers le rivage attirait des volées composées de plusieurs milliers de fulmars qui capturaient la morue en piquant à la surface et en la poursuivant sous l'eau. On a déterminé expérimentalement que le fulmar boréal est capable de plonger à 3 m sous la surface pour retrouver la morue.Mots clés: fulmar boréal, Fulrnarus glacialis, comportement alimentaire, plongée, détroit de Barrow, détroit de Lancaste
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