Estimating gas accretion in disc galaxies using the Kennicutt-Schmidt law

We show how the existence of a relation between the star formation rate and the gas density, i.e. the Kennicutt-Schmidt law, implies a continuous accretion of fresh gas from the environment into the discs of spiral galaxies. We present a method to derive the gas infall rate in a galaxy disc as a function of time and radius, and we apply it to the disc of the Milky Way and 21 galaxies from the THINGS sample. For the Milky Way, we found that the ratio between the past and current star formation rates is about 2-3, averaged over the disc, but it varies substantially with radius. In the other disc galaxies there is a clear dependency of this ratio with galaxy stellar mass and Hubble type, with more constant star formation histories for small galaxies of later type. The gas accretion rate follows very closely the SFR for every galaxy and it dominates the evolution of these systems. The Milky Way has formed two thirds of its stars after z=1, whilst the mass of cold gas in the disc has remained fairly constant with time. In general, all discs have accreted a significant fraction of their gas after z=1. Accretion moves from the inner regions of the disc to the outer parts, and as a consequence star formation moves inside-out as well. At z=0 the peak of gas accretion in the Galaxy is at about 6-7 kpc from the centre.Comment: 14 pages, 10 figures, accepted for publication in MNRA

The Radio - X-ray relation as a star formation indicator: Results from the VLA--E-CDFS Survey

In order to trace the instantaneous star formation rate at high redshift, and hence help understanding the relation between the different emission mechanisms related to star formation, we combine the recent 4 Ms Chandra X-ray data and the deep VLA radio data in the Extended Chandra Deep Field South region. We find 268 sources detected both in the X-ray and radio band. The availability of redshifts for $\sim 95$ of the sources in our sample allows us to derive reliable luminosity estimates and the intrinsic properties from X-ray analysis for the majority of the objects. With the aim of selecting sources powered by star formation in both bands, we adopt classification criteria based on X-ray and radio data, exploiting the X-ray spectral features and time variability, taking advantage of observations scattered across more than ten years. We identify 43 objects consistent with being powered by star formation. We also add another 111 and 70 star forming candidates detected only in the radio or X-ray band, respectively. We find a clear linear correlation between radio and X-ray luminosity in star forming galaxies over three orders of magnitude and up to $z \sim 1.5$. We also measure a significant scatter of the order of 0.4 dex, higher than that observed at low redshift, implying an intrinsic scatter component. The correlation is consistent with that measured locally, and no evolution with redshift is observed. Using a locally calibrated relation between the SFR and the radio luminosity, we investigate the L_X(2-10keV)-SFR relation at high redshift. The comparison of the star formation rate measured in our sample with some theoretical models for the Milky Way and M31, two typical spiral galaxies, indicates that, with current data, we can trace typical spirals only at z<0.2, and strong starburst galaxies with star-formation rates as high as $\sim 100 M_\odot yr^{-1}$, up to $z\sim 1.5$.Comment: 21 pages, 10 figures, 5 table

Cosmic star formation rate: a theoretical approach

The cosmic star formation rate (CSFR), is an important clue to investigate the history of the assembly and evolution of galaxies. Here, we develop a method to study the CSFR from a purely theoretical point of view. Starting from detailed models of chemical evolution, we obtain the histories of star formation of galaxies of different morphological types. These histories are then used to determine the luminosity functions of the same galaxies by means of a spectro-photometric code. We obtain the CSFR under different hypothesis. First, we study the hypothesis of a pure luminosity evolution scenario, in which all galaxies are supposed to form at the same redshift and then evolve only in luminosity. Then we consider scenarios in which the number density or the slope of the LFs are assumed to vary with redshift. After comparison with available data we conclude that a pure luminosity evolution does not provide a good fit to the data, especially at very high redshift, although many uncertainties are still present in the data. On the other hand, a variation in the number density of ellipticals and spirals as a function of redshift can provide a better fit to the observed CSFR. We also explore cases of variable slope of the LFs with redshift and variations of number density and slope at the same time. We cannot find any of those cases which can improve the fit to the data respect to the solely number density variation. Finally, we compute the evolution of the average cosmic metallicity in galaxies with redshift.Comment: 13 pages, 10 figures, accepted for publication in MNRAS. arXiv admin note: substantial text overlap with arXiv:1108.504

Le visite pastorali del vescovo Francesco Zeno nella diocesi di Capodistria (1660-1680)

This paper emphasises the pastoral work of Francesco Zeno, born in Candia (Crete), but originally from Venice, who was Bishop of the Diocese of Koper from 1660 to 1680. The paper includes the reading and analysis of the five pastoral visits made by Zeno to the Diocese of Koper during his episcopate, a study as well as a comparison with his ad limina report, from which it will be possible to learn about different aspects of the history of the local church and, more generally, of the entire community. The sources used prove that this was a very peaceful diocese, without any particular problems. The Bishop repeatedly and punctually visited ithe paid attention to the problems, and patiently tried to improve the effectiveness of pastoral actio

PROTOCOLO DE ISOLAMENTO DE BACTERIÓFAGOS PARA PSEUDOMONAS AERUGINOSA A PARTIR DE AMOSTRAS DE SECREÇÃO TRAQUEAL

Introdução: As infecções relacionadas à assistência à saúde (IRAS) constituem uma preocupação crescente que exige atenção dos profissionais da saúde, especialmente quando se trata de microrganismos resistentes a múltiplos antimicrobianos (MDR). Pseudomonas aeruginosa, um bacilo Gram-negativo não fermentador, é frequentemente associado a IRAS de alta morbimortalidade e apresenta comumente um perfil MDR. Nesse contexto, a fagoterapia tem emergido como uma alternativa promissora ao uso de antimicrobianos, consistindo no uso de bacteriófagos altamente específicos para o combate às infecções bacterianas. Objetivos: Estabelecer um protocolo de isolamento de bacteriófago de P. aeruginosa isolada de amostra de secreção traqueal. Metodologia: Foram utilizadas amostras de secreção traqueal provenientes do Laboratório de Análises Clínicas da Universidade do Oeste Paulista (UNOESTE), destinadas ao descarte. As amostras clínicas foram diluídas em tampão específico e submetidas à centrifugação. O sobrenadante resultante foi reservado e tratado com clorofórmio para reduzir a presença de células bacterianas, obtendo-se assim um lisado bacteriano que foi mantido a 7°C em geladeira. Os isolados bacterianos, previamente identificados como P. aeruginosa, foram utilizados para cultura do lisado, em meio Luria-Bertani para realização de streak e spot testes. Os plaques formados foram imersos em tampão e armazenados em geladeira para análises moleculares posteriores. Resultados: foi isolado um bacteriófago específico para P. aeruginosa a partir de um total de 10 isolados clínicos testados durante a fase inicial do estudo. Além disso, construiu-se um banco de lisados e isolados a partir de 147 amostras clínicas para análise futura. Conclusão: Esses achados preliminares indicam que a metodologia empregada neste estudo possui um promissor potencial para o isolamento de bacteriófagos específicos para P. aeruginosa. A busca por terapias alternativas ao uso de antimicrobianos é de suma importância para o controle adequado das IRAS e das infecções comunitárias causadas por microrganismos de difícil tratamento. Os resultados obtidos contribuem significativamente para o avanço do conhecimento científico nessa área e podem ter implicações relevantes no desenvolvimento de novas estratégias terapêuticas para o controle das infecções relacionadas à assistência à saúde

Ultrasound characterization of the coelomic cavity organs of the red-footed tortoise ( Chelonoidis carbonaria )

ABSTRACT: Herein it was describe sonographic morphology and sintopy of the bowels of the coelomic cavity in the red-footed tortoise. Coelomic cavity of 19 males and 19 females were scanned through cervical and prefemoral access with a multifrequency sector transducer. Morphology, syntopy and echogenicity of the heart, thyroid, liver, gallbladder, reproductive organs, stomach, small intestine, large intestine, urinary bladder and kidneys were evaluated. The heart showed two atria and one ventricle with a thick, trabecular wall. The thyroid was oval and hyperecoic, visualized in the cardiac portion of the ultrasound. The liver, gallbladder and digestive system were similar to those seen in mammals and turtles. However, the tortoise liver was relatively more hyperechoic than mammals. The kidneys appeared as triangular structures, which were hypoechoic, homogeneous and vascularized; the bladder was observed mostly as being elongated with anechoic content, and its wall appeared as a thin hyperechoic line when free fluid was present. The testes were observed to be elongated, homogeneous and more hyperechoic than kidneys. The ovarian follicles were seen as hyperechoic, echogenic balls of variable size and quantity, the oviduct as a sigmoid tubular structure and the eggs as thin hyperechoic lines with posterior acoustic shadowing. In some animals, there were variable amounts of fluid around the heart and in the coelomic cavity