Cosmic Feedback from AGN

Accretion onto the massive black hole at the centre of a galaxy can feed energy and momentum into its surroundings via radiation, winds and jets. Feedback due to radiation pressure can lock the mass of the black hole onto the M-sigma relation, and shape the final stellar bulge of the galaxy. Feedback due to the kinetic power of jets can prevent massive galaxies greatly increasing their stellar mass, by heating gas which would otherwise cool radiatively. The mechanisms involved in cosmic feedback are discussed and illustrated with observations.Comment: 9 pages, 13 figures, Proceedings IAU Symposium 267, Co-Evolution of Central Black Holes and Galaxie

The Nature of the H2-Emitting Gas in the Crab Nebula

Understanding how molecules and dust might have formed within a rapidly expanding young supernova remnant is important because of the obvious application to vigorous supernova activity at very high redshift. In previous papers, we found that the H2 emission is often quite strong, correlates with optical low-ionization emission lines, and has a surprisingly high excitation temperature. Here we study Knot 51, a representative, bright example, for which we have available long slit optical and NIR spectra covering emission lines from ionized, neutral, and molecular gas, as well as HST visible and SOAR Telescope NIR narrow-band images. We present a series of CLOUDY simulations to probe the excitation mechanisms, formation processes and dust content in environments that can produce the observed H2 emission. We do not try for an exact match between model and observations given Knot 51's ambiguous geometry. Rather, we aim to explain how the bright H2 emission lines can be formed from within the volume of Knot 51 that also produces the observed optical emission from ionized and neutral gas. Our models that are powered only by the Crab's synchrotron radiation are ruled out because they cannot reproduce the strong, thermal H2 emission. The simulations that come closest to fitting the observations have the core of Knot 51 almost entirely atomic with the H2 emission coming from just a trace molecular component, and in which there is extra heating. In this unusual environment, H2 forms primarily by associative detachment rather than grain catalysis. In this picture, the 55 H2-emitting cores that we have previously catalogued in the Crab have a total mass of about 0.1 M_sun, which is about 5% of the total mass of the system of filaments. We also explore the effect of varying the dust abundance. We discuss possible future observations that could further elucidate the nature of these H2 knots.Comment: 51 pages, 15 figures, accepted for publication in MNRAS, revised Figure 12 results unchange

Drug Abuse Prevention Campaigns in Chile (2004-2014): Between Prohibitionism and Stigmatisation

This paper studies the presence and reproduction of the ‘prohibitionist’ paradigm in the Chilean state’s drug policy by studying its drug abuse prevention campaigns. By means of a content analysis of the television spots broadcast between 2004 and 2014, the discursive and ideological elements present in these campaigns were examined. First and foremost, the results show that, despite institutional change and the creation of bodies such as the National Service for the Prevention and Rehabilitation of Drug and Alcohol Use (SENDA) and the National Council for Narcotics Control (CONACE), the state’s discourse has remained focused on the prohibitionist paradigm, resorting to highly stereotyped emotional messages. Secondly, drug consumption has been stigmatised and framed in profoundly dramatic contexts in which users belong to the criminal underworld or have physical and/or cognitive impairments. Thirdly, notwithstanding the fact that there are certain differences between the communication approaches employed by the SENDA and the CONACE, the discourses of both institutions are very uniform and reductionist. In order to design more efficient media campaigns, target audiences should be encouraged to analyse and ponder reflectively on the issue by conveying rational messages that contrast facts and data and offer a positive vision stressing the benefits of a healthy lifestyle.Este artículo cuestiona la presencia y reproducción del paradigma “prohibicionista” en la política de drogas del Estado chileno, a través del estudio de sus campañas de comunicación para la prevención del consumo de drogas. Mediante un análisis de contenido de los spots televisivos aparecidos entre 2004-2014 se estudiaron los elementos discursivos e ideológicos presentes en las campañas. Los resultados mostraron primero que, pese al cambio institucional y la creación de organismos como SENDA y CONACE, los contenidos elaborados y reproducidos por el discurso estatal se han mantenido enfocados en el paradigma prohibicionista recurriendo a mensajes emocionales, muy estereotipados. Segundo, que el usuario de drogas está estigmatizado y se sitúa en contextos con fuerte carga dramática donde los consumidores pertenecen al ámbito criminal o al de la discapacidad intelectual. Tercero, que a pesar de que existen ciertas diferencias en el tratamiento comunicacional entre SENDA y CONACE, ambas instituciones mantienen un discurso muy homogéneo y reduccionista. Para lograr una mejor eficiencia de las campañas mediáticas, por el contrario, debería inducirse al receptor a realizar un análisis y reflexión crítica en torno al tema y mostrar mensajes racionales que contrasten hechos y datos y ofrezcan una visión positiva que refuerce los beneficios de un estilo de vida saludable

Cold gas in the Intra Cluster Medium: implications for flow dynamics and powering optical nebulae

We show that the mechanical energy injection rate generated as the intra-cluster medium (ICM) flows around cold clouds may be sufficient to power the optical and near infra-red emission of nebulae observed in the central regions of a sample of seven galaxy clusters. The energy injection rate is extremely sensitive to the velocity difference between the ICM and cold clouds, which may help to explain why optical and infra-red luminosity is often larger than expected in systems containing AGNs. We also find that mass recycling is likely to be important for the dynamics of the ICM. This effect will be strongest in the central regions of clusters where there is more than enough cold gas for its evaporation to contribute significantly to the density of the hot phase.Comment: 8 pages, 2 figures, accepted for publication in MNRA

Nuclear microprobe: the tool to characterize new materials for energy conversion [Poster]

N/

Structural, mineralogical, and biochemical diversity in the lower part of the pearl layer of cultivated seawater pearls from Polynesia

A series of Polynesian pearls has been investigated with particular attention to the structural and compositional patterns of the early developmental stages of the pearl layer. These initial steps in pearl formation bear witness of the metabolic changes that have occurred during the pearl-sac formation. The resulting structurally and biochemically complex structures have been investigated using a variety of techniques that provide us with information concerning both mineral phases and the organic components. Results are discussed with respect to our understanding of the biomineralization mechanisms, as well as for the grafting process

Probiotic potential of fructo-oligosaccharides produced by Aspergillus ibericus

The gastrointestinal tract harbours a diverse and dynamic microbial community that directly impacts human health. Prebiotics, such as fructo-oligosaccharides (FOS), play a crucial role in the modulation of colonic microbiota, reducing pathophysiological disorders and associated chronic diseases. The prebiotic potential of FOS produced by a newly isolated strain Aspergillus ibericus was studied. FOS fermentability by the probiotic Lactobacillus rhamnosus was evaluated. L. rhamnosus was grown in de Man-Rogosa-Sharpe (MRS) broth, with different carbon sources: glucose (positive control), no sugar (negative control), microbial-derived FOS from A. ibericus and Raftilose®P95, a non-microbial commercial FOS sample (from Beneo-Orafti, Belgium). A final concentration of 2 % (w/v) in sugar was used. Fermentation was carried out in a 96-well microplate and a shake flask, for 24 h, at 37 ºC, with an agitation of 120 rpm. Biomass growth was analysed by optical density at 620 nm. The consumption of sugars and the production of short chain fatty acids (SCFA) and lactate was quantified by HPLC. Maximum cell growth was reached at approximately 12 h, for all carbon sources. The highest growth was achieved for glucose samples, followed by the microbial-derived FOS, then Raflitose and finally the negative control. Although the microbial-derived FOS promoted great cellular growth, only kestose (GF2), together with residual amounts of glucose and sucrose presented in the sample, were consumed. This may explain the two different slopes exhibited during the exponential phase growth. Most likely hypothesis is that probiotic bacteria was cleaving GF2 in the first hours of fermentation, using only the smallest sugars present for growing. And Nystose (GF3) and fructofuranosylnystose (GF4) were not consumed, even when prolonging the fermentation up to 48 h. SCFA identified were valerate and propionate, as well as succinate, formate, acetate, iso-butyrate and nbutirate, although in lower amount. Higher amount of SCFA and lactate were determined while growing in the microbial-derived FOS, as compared to the commercial sample. Overall, lactate was the main metabolite produced during the fermentations. In conclusion, the prebiotic potential of microbial-derived FOS synthesized by A. ibericus was demonstrated, providing promising indication of its usability as food ingredient with strong prebiotic features.info:eu-repo/semantics/publishedVersio

Star Formation in the Outer Filaments of NGC 1275

We present photometry of the outer star clusters in NGC 1275, the brightest galaxy in the Perseus cluster. The observations were taken using the Hubble Space Telescope Advanced Camera for Surveys. We focus on two stellar regions in the south and south-east, far from the nucleus of the low velocity system (~22 kpc). These regions of extended star formation trace the H alpha filaments, drawn out by rising radio bubbles. In both regions bimodal distributions of colour (B-R)_0 against magnitude are apparent, suggesting two populations of star clusters with different ages; most of the H alpha filaments show no detectable star formation. The younger, bluer population is found to be concentrated along the filaments while the older population is dispersed evenly about the galaxy. We construct colour-magnitude diagrams and derive ages of at most 10^8 years for the younger population, a factor of 10 younger than the young population of star clusters in the inner regions of NGC 1275. We conclude that a formation mechanism or event different to that for the young inner population is needed to explain the outer star clusters and suggest that formation from the filaments, triggered by a buoyant radio bubble either rising above or below these filaments, is the most likely mechanism.Comment: Accepted for publication in MNRAS, 14 pages, 14 figures, 3 table

A comparison between biotic indices and predictive models in stream water quality assessment based on benthic diatom communities

http://www.sciencedirect.com/science/article/B6W87-4TBVPV7-1/2/9410c28d535e230ea5a4b3bc5f30512