234,090 research outputs found

    The Effects of Galaxy Shape and Rotation on the X-ray Haloes of Early-Type Galaxies

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    We present a detailed diagnostic study of the observed temperatures of the hot X-ray coronae of early-type galaxies. By extending the investigation carried out in Pellegrini (2011) with spherical models, we focus on the dependence of the energy budget and temperature of the hot gas on the galaxy structure and internal stellar kinematics. By solving the Jeans equations we construct realistic axisymmetric three-component galaxy models (stars, dark matter halo, central black hole) with different degrees of flattening and rotational support. The kinematical fields are projected along different lines of sight, and the aperture velocity dispersion is computed within a fraction of the circularized effective radius. The model parameters are chosen so that the models resemble real ETGs and lie on the Faber-Jackson and Size-Luminosity relations. For these models we compute T_* (the stellar heating contribution to the gas injection temperature) and T_gm (the temperature equivalent of the energy required for the gas escape). In particular, different degrees of thermalisation of the ordered rotational field of the galaxy are considered. We find that T_* and T_gm can vary only mildly due to a pure change of shape. Galaxy rotation instead, when not thermalised, can lead to a large decrease of T_*; this effect can be larger in flatter galaxies that can be more rotationally supported. Recent temperature measurements T_x, obtained with Chandra, are larger than, but close to, the T_* values of the models, and show a possible trend for a lower T_x in flatter and more rotationally supported galaxies; this trend can be explained by the lack of thermalisation of the whole stellar kinetic energy. Flat and rotating galaxies also show lower L_x values, and then a lower gas content, but this is unlikely to be due to the small variation of T_gm found here for them.Comment: 16 pages, 7 figures, accepted for publication in MNRA

    The "Canone Inverso": when tobacco was not so bad. A Look Back at the Primordial Debate on the tobacco effects in the Occupational Medicine

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    AIM: The article provides an overview on the beginning and evolutions of medical observations on tobacco induced diseases between Eighteenth and Nineteenth century. METHODS: By searching for historical medical literature, first studies on tobacco-induced diseases focused on production risks rather than on adverse effects that the use of tobacco has for the human health. RESULTS: The approach induced first eighteenth-century authors to define this substance as a non-pathogenic and, consequently, not to consider tobacco factories dangerous for health workers. In those years, tobacco was employed in therapy as a stimulant treatment and it was considered harmless and even healthy and preventive of several acute diseases. CONCLUSIONS: Authors will show that studies on pathogenic effects of smoking will only start around late nineteenth century, when the idea of the healthiness of tobacco industry was already supported

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    Extraordinary rendition

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    The 'Foce' monumental cemetery in Sanremo: mirror of the city as outstanding tourist destination during the Belle Epoque (1880-1915)

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    The monumental cemetery of Sanremo, was founded in 1838 and now counts about 2000 graves, one third of which belongs to foreigners, evidences of the city as outstanding tourist destination. The city with a good climate was also choosen for the recovery from the disease of chest by many people, even by Maria Alessandrovna, Csarina of Russia. Many important people came to Sanremo from all over the world and sometimes here passed by and were buried: people like the painter Edward Lear, the anatomist Arthur Hill Hassal, Lady Caroline Giffard Phillipson, Prussian nobles, a good number of Russian aristocrats, and many others..

    Saturated fusion systems with parabolic families

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    Let G be group; a finite p-subgroup S of G is a Sylow p-subgroup if every finite p-subgroup of G is conjugate to a subgroup of S. In this paper, we examine the relations between the fusion system over S which is given by conjugation in G and a certain chamber system C, on which G acts chamber transitively with chamber stabilizer N_G(S). Next, we introduce the notion of a fusion system with a parabolic family and we show that a chamber system can be associated to such a fusion system. We determine some conditions the chamber system has to fulfill in order to assure the saturation of the underlying fusion system. We give an application to fusion systems with parabolic families of classical type.Comment: 28 page
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