235,665 research outputs found
The Effects of Galaxy Shape and Rotation on the X-ray Haloes of Early-Type Galaxies
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
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
Saturated fusion systems with parabolic families
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
Modern Narcissus: the lingering reflections of myth in modern art
Why has myth continued to fascinate modern artists, and why the myth of Narcissus, with its modern association with narcissism? This article considers the relationship between the Narcissus myth and the lineage of modern art that runs from Symbolism to surrealism through the polymorphous prism of the Greco-Roman Pantheon to which Narcissus belongs. The article offers an interpretation of the role of mythology in modern art that moves beyond psychoanalysis to incorporate the longer span of the art-historical tradition. Addressing issues of aesthetics, gender and sexuality, the following account highlights Narcissus‟s double nature as an erotic myth that comprises both identity formation and intersubjectivity, as enacted in the field of representation. The myths associated with Narcissus in the history of Western art will help us reconsider his role as a powerful figure capable to activate that slippage between word and image, identity and sociability, representation and reality which was celebrated by the Symbolists and formed the centre of the surrealists‟ social-aesthetic project
Indirect CP violation results and HFAG averages
The current status of the search for indirect CP violation in the neutral D
meson system at the B-factories and at LHCb is reported. The indirect CP
asymmetry search is performed by the measurement of the proper-time asymmetry
() in decays of mesons to CP eigenstates,
and , and by , the ratio between the effective lifetime
measured in decay to a CP eigenstate and that to the mixed eigenstate .
All results are consistent with the no CP violation hypothesis. The latest
world averages for mixing and CP asymmetry in the charm sector evaluated by the
Heavy Flavour Averaging Group are presented. The no mixing hypothesis is
excluded at more than 12 standard deviations. The search for direct and
indirect CP violation in the charm sector is consistent with no CP violation at
2.0% confident level.Comment: to appear in the proceedings of The 6th International Workshop on
Charm Physics (CHARM 2013
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