Azimuthal dependence of the density distribution in outer galactic discs accreting intergalactic flows

AIMS. The amplitude and scaleheight of the Galactic gas disc density are not axisymmetric against expectations in a self-gravity axisymmetric disc. However, this lopsidedness can be explained in terms of intergalactic accretion flows, which produce non-axisymmetric pressure on the disc. This mechanism could be also responsible for the formation of a warp. METHODS. We analytically derive the relationship between the disc density and the self-gravity and external pressure. RESULTS. The same scenario of accretion as we proposed years ago to explain the formation of the warp explains the azimuthal dependence of the density and its scaleheight, with minimum/maximum in the positions of maximum amplitude of the warp (phi=95 deg. and 275 deg.), as expected from its pressure distribution.Comment: 4 pages, accepted to be published in A&A-letter

Old stellar Galactic disc in near-plane regions according to 2MASS: scales, cut-off, flare and warp

We have pursued two different methods to analyze the old stellar population near the Galactic plane, using data from the 2MASS survey. The first method is based on the isolation of the red clump giant population in the color-magnitude diagrams and the inversion of its star counts to obtain directly the density distribution along the line of sight. The second method fits the parameters of a disc model to the star counts in 820 regions. Results from both independent methods are consistent with each other. The qualitative conclusions are that the disc is well fitted by an exponential distribution in both the galactocentric distance and height. There is not an abrupt cut-off in the stellar disc (at least within R<15 kpc). There is a strong flare (i.e. an increase of scale-height towards the outer Galaxy) which begins well inside the solar circle, and hence there is a decrease of the scale-height towards the inner Galaxy. Another notable feature is the existence of a warp in the old stellar population whose amplitude is coincident with the amplitude of the gas warp. It is shown for low latitude stars (mean height: |z|~300 pc) in the outer disc (galactocentric radius R>6 kpc) that: the scale-height in the solar circle is h_z(R_sun)=3.6e-2 R_sun, the scale-length of the surface density is h_R=0.42 R_sun and the scale-length of the space density in the plane (i.e. including the effect of the flare) is H=0.25 R_sun. The variation of the scale-height due to the flare follows roughly a law h_z(R) =~ h_z(R_sun) exp [(R-R_\odot)/([12-0.6R(kpc)] kpc)] (for R<~15 kpc; R_sun=7.9 kpc). The warp moves the mean position of the disc to a height z_w=1.2e-3 R(kpc)^5.25 sin(phi+(5 deg.)) pc (for R<~13 kpc; R_sun=7.9 kpc).Comment: LaTEX, 20 pages, 23 figures, accepted to be published in A&

Near-infrared and optical observations of galactic warps: A common, unexplained feature of most discs

Context: Warps occurring in galactic discs have been studied extensively in HI and in the optical, but rarely in the near-infrared (NIR) bands that trace the older stellar populations. Aims: We provide NIR data of nearby edge-on galaxies, combined with optical observations, for direct comparison of the properties of galactic warps as a function of wavelength, and calculate warp curves for each galaxy and obtain the characteristic warp parameters. We discuss these properties as possible constraints to the different mechanisms that have been proposed for the development and persistence of galactic warps. Methods: We observed 20 galaxies that were selected from a statistically complete diameter-limited subsample of edge-on disc galaxies. We used the Cerro Tololo Infrared Imager (CIRIM) at the CTIO 1.5m Ritchey-Chretien telescope to acquire the NIR data. We used the 1.54m Danish and 0.92m Dutch telescopes at the European Southern Observatory's La Silla site for our optical observations. Results: Our results show that 13 of our 20 sample galaxies are warped, with the warp more pronounced in the optical than at NIR wavelengths. In the remaining seven galaxies, no warp is apparent within the limitations of our automated detection method. The transition between the unperturbed inner disc and the outer, warped region is rather abrupt. S0 galaxies exhibit very small or no warps. The magnetic model remains one of a number of interesting formation scenarios.Comment: 16 page

La ética y el derecho en la producción y el consumo del entretenimiento

Contiene las ponencias y comunicaciones del congreso

A catalog of warps in spiral and lenticular galaxies in the Southern hemisphere

A catalog of optical warps of galaxies is presented. This can be considered complementary to that reported by Sanchez-Saavedra et al., with 42 galaxies in the northern hemisphere, and to that by Reshetnikov & Combes, with 60 optical warps. The limits of the present catalog are: logr25 > 0.60, B_{t} < 14.5, delta(2000) < 0, -2.5 < t < 7. Therefore, lenticular galaxies have also been considered. This catalog lists 150 warped galaxies out of a sample of 276 edge-on galaxies and covers the whole southern hemisphere, except the Avoidance Zone. It is therefore very suitable for statistical studies of warps. It also provides a source guide for detailed particular observations. We confirm the large frequency of warped spirals: nearly all galaxies are warped. The frequency and warp angle do not present important differences for the different types of spirals. However, no lenticular warped galaxy has been found within the specified limits. This finding constitutes an important restriction for theoretical models.Comment: 12 pages, 6 figures, to be published in Astronomy and Astrophysic

Elaboració de material docent per a assignatures d'estadística industrial

La finalitat del projecte és elaborar material d'ajuda i suport a la docència per assignatures relacionades amb l'estadística industrial. Ens centrem fonamentalment en les assignatures “Mètodes estadístics de l’enginyeria 1”, d’enginyeria industrial, i “Estadística”, d’enginyera química, per la gran repercussió que tenen els canvis en aquestes assignatures (un total de 500 estudiants matriculats per any). El projecte es pot entendre com la continuació d’un altre projecte que va rebre un ajut de l’ICE i que es va desenvolupar durant el curs 2007-2008, titulat “Elaboració de material docent per a assignatures de control i millora de la qualitat” i coordinat per Lourdes Rodero de Lamo. La necessitat de creació de nou material sorgeix a partir de decidir canvis – alineats amb l’enfocament de l’EEES – en la metodologia docent. Els canvis venen motivats no només pel fet que aquestes dues assignatures entren en la fase pilot d’implantació de l’EEES a l’ETSEIB, sinó també – i sobretot – a partir de la constatació de fets que no ens agradaven als professors: poca assistència a classe, sensació de que els estudiants “no segueixen” l’assignatura, oblit ràpid del que s’ha aprés, etc.Peer Reviewe

Current status of the cryopreservation of embryogenic material of woody species

Cryopreservation, or the storage at liquid nitrogen temperatures (-196°C), of embryogenic cells or somatic embryos allows their long-term conservation without loss of their embryogenic capacity. During the last decade, protocols for cryopreservation of embryogenic material of woody species have been increasing in number and importance. However, despite the large experimental evidence proved in thousands of embryogenic lines, the application for the large-scale conservation of embryogenic material in cryobanks is still limited. Cryopreservation facilitates the management of embryogenic lines, reducing costs and time spent on their maintenance, thus limiting the risk of the appearance of somaclonal variation or contamination. Somatic embryogenesis in combination with cryopreservation is especially useful to preserve the juvenility of lines while the corresponding clones are being field-tested. Hence, when tree performance has been evaluated, selected varieties can be propagated from the cryostock. The traditional method of slow cooling or techniques based on vitrification are mostly applied procedures. For example, slow cooling methods are widely applied to conserve embryogenic lines of conifers. Desiccation based procedures, although simpler, have been applied in a smaller number of species. Genetic stability of the cryopreserved material is supported by multiloci PCR-derived markers in most of the assayed species, whereas DNA methylation status assays showed that cryopreservation might induce some changes that were also observed after prolonged subculture of the embryogenic lines. This article reviews the cryopreservation of embryogenic cultures in conifers, fruit species, deciduous forest species and palms, including a description of the different cryopreservation procedures and the analysis of their genetic stability after storage in liquid nitrogen

Bending instabilities at the origin of persistent warps: a new constraint on dark matter halos

A substantial fraction of the warps in spiral galaxies may result from bending instabilities if the disks are essentially self-gravitating. With N-body simulations, we show that galaxies with self-gravitating disks as thick as HI disks are subject to bending instabilities generating S-shaped, U-shaped or asymmetric warps. S-shaped warps persist during several rotations and keep the line of node straight. The warp amplitudes generated by bending instabilities remain however modest. Other factors must be invoked for extreme warped disks. However, bending instabilities can account for most of the cases reported in optical surveys, where the warp angle is generally less than $5^\circ$. This mode of warping is very sensitive to the disk flattening. It also constrains the fraction of dark matter distributed in the disk and in the dark halo.Comment: 11 pages. Accepted for publication on A&A Main Journal. Paper with full resolution images is available at : http://obswww.unige.ch/~revaz/bending/bending.pdf http://obswww.unige.ch/~revaz/bending/bending.ps.g

Procedimiento de inserción del catéter central de inserción periférica (PICC) en adultos FEMORA. Procedimientos de enfermería: canalización y cuidados de vías vasculares

O programa FEMORA recompila procedementos estandarizados, con evidencia científica, para os profesionais do Sergas. A protocolización dos coidados confórmase como instrumento indispensable de soporte para a práctica clínica. Entre as súas numerosas vantaxes cabe destacar a redución na diversidade inapropiada da práctica clínica, o que propicia unha atención máis xusta e equitativa aos pacientes. Este procedemento unifica, así mesmo, criterios de actuación que serven de punto de partida para unha avaliación de calidade do proceso asistencial.El programa FEMORA recopila procedimientos estandarizados, con evidencia científica, para los profesionales del Sergas. La protocolización de los cuidados se conforma como instrumento indispensable de soporte para la práctica clínica. Entre sus numerosas ventajas cabe destacar la reducción en la diversidad inapropiada de la práctica clínica, lo que les propicia una atención más justa y equitativa a los pacientes. Este procedimiento unifica, asimismo, criterios de actuación que sirven de punto de partida para una evaluación de calidad del proceso asistencial

What is the closest black hole to the Sun?

We examine the distance of the two galactic microquasars GRO J1655-40 and A0620-00, which are potentially the two closest black holes to the Sun. We aim to provide a picture as wide and complete as possible of the problem of measuring the distance of microquasars in our Galaxy. The purpose of this work is to fairly and critically review in great detail every distance method used for these two microquasars in order to show that the distances of probably all microquasars in our galaxy are much more uncertain than currently admitted. Moreover, we show that many confirmations of quantitative results are often entangled and rely on very uncertain measurements. We also present a new determination of the maximum distance of GRO J1655-40 using red clump giant stars, and show that it confirms our earlier result of a distance less than 2 kpc instead of 3.2 kpc. Since it then becomes more likely that GRO J1655-40 could originate from the stellar cluster NGC 6242, located at 1.0 kpc, we review the distance estimations of A0620-00, which is so far the closest black hole with an average distance of about 1.0 kpc. We show that the distance methods used for A0620-00 are also problematic. Finally, we present a new analysis of spectroscopic and astrometric archival data on this microquasar, and apply the maximum-distance method of Foellmi et al. (2006). It appears that A0620-00 could indeed be even closer to the Sun than currently estimated, and consequently would be the closest known black hole to the Sun.Comment: Accepted for publication in New Astronomy. 27 pages, 7 figures, Added new column in Table 1. Corrected definition of mass ratio in Equ 1