858 research outputs found

    On the usefulness of finding charts Or the runaway carbon stars of the Blanco & McCarthy field 37

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    We have been recently faced with the problem of cross--identifying stars recorded in historical catalogues with those extracted from recent fully digitized surveys (such as DENIS and 2MASS). Positions mentioned in the old catalogues are frequently of poor precision, but are generally accompanied by finding charts where the interesting objects are flagged. Those finding charts are sometimes our only link with the accumulated knowledge of past literature. While checking the identification of some of these objects in several catalogues, we had the surprise to discover a number of discrepancies in recent works.The main reason for these discrepancies was generally the blind application of the smallest difference in position as the criterion to identify sources from one historical catalogue to those in more recent surveys. In this paper we give examples of such misidentifications, and show how we were able to find and correct them.We present modern procedures to discover and solve cross--identification problems, such as loading digitized images of the sky through the Aladin service at CDS, and overlaying entries from historical catalogues and modern surveys. We conclude that the use of good finding charts still remains the ultimate (though time--consuming) tool to ascertain cross--identifications in difficult cases.Comment: 4 pages, 1 figure, accepted by A&

    On The 5D Extra-Force according to Basini-Capozziello-Leon Formalism and five important features: Kar-Sinha Gravitational Bending of Light, Chung-Freese Superluminal Behaviour, Maartens-Clarkson Black Strings, Experimental measures of Extra Dimensions on board International Space Station(ISS) and the existence of the Particle ZZ due to a Higher Dimensional spacetime

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    We use the Conformal Metric as described in Kar-Sinha work on Gravitational Bending of Light in a 5D Spacetime to recompute the equations of the 5D Force in Basini-Capozziello-Leon Formalism and we arrive at a result that possesses some advantages. The equations of the Extra Force as proposed by Leon are now more elegant in Conformal Formalism and many algebraic terms can be simplified or even suppressed. Also we recompute the Kar-Sinha Gravitational Bending of Light affected by the presence of the Extra Dimension and analyze the Superluminal Chung-Freese Features of this Formalism describing the advantages of the Chung-Freese BraneWorld when compared to other Superluminal spacetime metrics(eg:Warp Drive) and we describe why the Extra Dimension is invisible and how the Extra Dimension could be made visible at least in theory.We also examine the Maartens-Clarkson Black Holes in 5D(Black Strings) coupled to massive Kaluza-Klein graviton modes predicted by Extra Dimensions theories and we study experimental detection of Extra Dimensions on-board LIGO and LISA Space Telescopes.We also propose the use of International Space Station(ISS) to measure the additional terms(resulting from the presence of Extra Dimensions) in the Kar-Sinha Gravitational Bending of Light in Outer Space to verify if we really lives in a Higher Dimensional Spacetime.Also we demonstrate that Particle ZZ can only exists if the 5D spacetime exists.Comment: Withdrawn: author no longer wishes to post work on arXi

    Difficultés de la surveillance épidémiologique de la rougeole en Afrique : exemple de la Côte d'Ivoire

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    En zone tropicale, les cas de rougeole sont souvent sous-déclarés mais les auteurs exposent deux épidémies qui ont été considérées au début comme des manifestations de rougeole. La première épidémie s'est manifestée comme une épidémie de viroses à Chikungunya avec éruptions, hyperthermie et algies importantes, elle était due à un arbovirus Igbo-Ora. Dans l'autre cas il s'agissait d'enfants atteints d'éruptions avec hyperthermie et adénopathies évoquant la rubéole. Les auteurs évoquent la possibilité de diagnostic par excès dans le cadre de la surveillance de cette maladie-cible du PEV (Programme Elargi de Vaccination), hypothèse confirmée par la répartition des cas déclarés au niveau national avec une fréquence élevée des cas en contre-saison et chez certains adultes. (Résumé d'auteur

    Interface fracture of hybrid joint of glass-/steel-fiber composite

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    DOI 10.1108/02644401211235861Purpose - In order to connect a fiberglass composite structure to a steel structure, a hybrid composite made of glass and steel fibers has been studied. The hybrid composite has one end section with all glass fibers and the opposite end section with all steel fibers. As a result, it contains a transition section in the middle of the hybrid composite changing from glass to steel fibers to steel fibers. The purpose of this paper is to examine interface strength at the glass to steel fiber transition section, in order to evaluate the effectiveness of the hybrid composite as a joining technique between a polymer composite structure and a metallic structure

    Mass-loss rates and luminosity functions of dust-enshrouded AGB stars and red supergiants in the LMC

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    A radiative transfer code is used to model the spectral energy distributions of 57 mass-losing Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud (LMC) for which ISO spectroscopic and photometric data are available. As a result we derive mass-loss rates and bolometric luminosities. A gap in the luminosity distribution around M_bol = -7.5 mag separates AGB stars from RSGs. The luminosity distributions of optically bright carbon stars, dust-enshrouded carbon stars and dust-enshrouded M-type stars have only little overlap, suggesting that the dust-enshrouded AGB stars are at the very tip of the AGB and will not evolve significantly in luminosity before mass loss ends their AGB evolution. Derived mass-loss rates span a range from Mdot about 10^-7 to 10^-3 M_sun/yr. More luminous and cooler stars are found to reach higher mass-loss rates. The highest mass-loss rates exceed the classical limit set by the momentum of the stellar radiation field, L/c, by a factor of a few due to multiple scattering of photons in the circumstellar dust envelope. Mass-loss rates are lower than the mass consumption rate by nuclear burning, Mdot_nuc, for most of the RSGs. Two RSGs have Mdot >> Mdot_nuc, however, suggesting that RSGs shed most of their stellar mantles in short phases of intense mass loss. Stars on the thermal pulsing AGB may also experience episodes of intensified mass loss, but their quiescent mass-loss rates are usually already higher than Mdot_nuc.Comment: 15 pages, 11 figures. Accepted for publication in Astronomy and Astrophysics Main Journa

    The Nature and Frequency of the Gas Outbursts in Comet 67P/Churyumov-Gerasimenko observed by the Alice Far-ultraviolet Spectrograph on Rosetta

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    Alice is a far-ultraviolet imaging spectrograph onboard Rosetta that, amongst multiple objectives, is designed to observe emissions from various atomic and molecular species from within the coma of comet 67P/Churyumov-Gerasimenko. The initial observations, made following orbit insertion in August 2014, showed emissions of atomic hydrogen and oxygen spatially localized close to the nucleus and attributed to photoelectron impact dissociation of H2O vapor. Weaker emissions from atomic carbon were subsequently detected and also attributed to electron impact dissociation, of CO2, the relative H I and C I line intensities reflecting the variation of CO2 to H2O column abundance along the line-of-sight through the coma. Beginning in mid-April 2015, Alice sporadically observed a number of outbursts above the sunward limb characterized by sudden increases in the atomic emissions, particularly the semi-forbidden O I 1356 multiplet, over a period of 10-30 minutes, without a corresponding enhancement in long wavelength solar reflected light characteristic of dust production. A large increase in the brightness ratio O I 1356/O I 1304 suggests O2 as the principal source of the additional gas. These outbursts do not correlate with any of the visible images of outbursts taken with either OSIRIS or the navigation camera. Beginning in June 2015 the nature of the Alice spectrum changed considerably with CO Fourth Positive band emission observed continuously, varying with pointing but otherwise fairly constant in time. However, CO does not appear to be a major driver of any of the observed outbursts.Comment: 6 pages, 4 figures, accepted for publication in the Astrophysical Journal Letter
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