Gamma-ray burst jet propagation, development of angular structure, and the luminosity function

The fate and observable properties of gamma-ray burst jets depend crucially on their interaction with the progenitor material that surrounds the central engine. We present a semi-analytical model of such interaction, which builds upon several previous analytical and numerical works, aimed at predicting the angular distribution of jet and cocoon energy and Lorentz factor after breakout, given the properties of the ambient material and of the jet at launch. Using this model, we construct synthetic populations of structured jets, assuming either a collapsar (for long gamma-ray bursts -- LGRBs) or a binary neutron star merger (for short gamma-ray bursts -- SGRBs) as progenitor. We assume all progenitors to be identical, and we allow little variability in the jet properties at launch: our populations therefore feature a quasi-universal structure. These populations are able to reproduce the main features of the observed LGRB and SGRB luminosity functions, although several uncertainties and caveats remain to be addressed.Comment: 15 pages, 12 figures. Revised version, submitted to A&A (several new figures and expanded discussion. Conclusions unchanged). Comments and suggestions are welcome

Fine Scale Analysis of Crossover and Non-Crossover and Detection of Recombination Sequence Motifs in the Honeybee (Apis mellifera)

BACKGROUND: Meiotic exchanges are non-uniformly distributed across the genome of most studied organisms. This uneven distribution suggests that recombination is initiated by specific signals and/or regulations. Some of these signals were recently identified in humans and mice. However, it is unclear whether or not sequence signals are also involved in chromosomal recombination of insects. METHODOLOGY: We analyzed recombination frequencies in the honeybee, in which genome sequencing provided a large amount of SNPs spread over the entire set of chromosomes. As the genome sequences were obtained from a pool of haploid males, which were the progeny of a single queen, an oocyte method (study of recombination on haploid males that develop from unfertilized eggs and hence are the direct reflect of female gametes haplotypes) was developed to detect recombined pairs of SNP sites. Sequences were further compared between recombinant and non-recombinant fragments to detect recombination-specific motifs. CONCLUSIONS: Recombination events between adjacent SNP sites were detected at an average distance of 92 bp and revealed the existence of high rates of recombination events. This study also shows the presence of conversion without crossover (i. e. non-crossover) events, the number of which largely outnumbers that of crossover events. Furthermore the comparison of sequences that have undergone recombination with sequences that have not, led to the discovery of sequence motifs (CGCA, GCCGC, CCGCA), which may correspond to recombination signals

Clinical treatment adherence of health care workers and students exposed to potentially infectious biological material

OBJECTIVE To assess adherence to clinical appointments by health care workers (HCW) and students who suffered accidents with potentially infectious biological material. METHOD A retrospective cross-sectional study that assessed clinical records of accidents involving biological material between 2005 and 2010 in a specialized unit. RESULTS A total of 461 individuals exposed to biological material were treated, of which 389 (84.4%) were HCWs and 72 (15.6%) students. Of the 461 exposed individuals, 307 (66.6%) attended a follow-up appointment. Individuals who had suffered an accident with a known source patient were 29 times more likely to show up to their scheduled follow-up appointments (OR: 29.98; CI95%: 16.09-55.83). CONCLUSION The predictor in both univariate and multivariate analyses for adherence to clinical follow-up appointment was having a known source patient with nonreactive serology for the human immunodeficiency virus and/or hepatitis B and C

Factors influencing adherence to standard precautions among nursing professionals in psychiatric hospitals

OBJECTIVE Evaluate and correlate individual, work-related and organizational factors that influence adherence to standard precautions among nursing professionals of psychiatric hospitals in São Paulo. METHOD An exploratory cross-sectional study conducted with 35 nursing professionals, using the assessment tool for adherence to standard precautions through the Likert scale, ranging from 1 to 5. RESULTS Knowledge of the precautions received a high score (4.69); adherence received (3.86) and obstacles (3.78), while intermediaries and the scales of organizational factors received low scores (2.61). There was a strong correlation between the magnitude adherence scale and the personal protective equipment availability (r = 0.643; p = 0.000). The training scale for prevention of HIV exposure (p = 0.007) was statistically different between the nurses and nursing assistants. CONCLUSION The organizational factors negatively contributed to adherence to standard precautions, indicating that psychiatric institutions lack safe working conditions, ongoing training and management actions to control infections

Caratterizzazione minerologica-petrografica I caso studio dell’impianto Fenza Daniela di Rovigo.

In questo lavoro, differenti frazioni granulometriche, ottenute da una selezione “on-site” da un impianto di lavorazione di Rovigo (NE Italy), sono state caratterizzate mediante fluorescenza di Raggi X e diffrattometria di Raggi X. Questo al fine di migliorare le metodologie di riciclaggio già presenti ed utilizzate per questi materiali.I risultati emersi da questo studio hanno evidenziato che attraverso un opportuno trattamento di frantumazione e selezione è possibile ottenere frazioni granulometriche composizionalmente omogenee. Sono state in particolare investigate le frazioni più fini ed è emerso che, oltre all’uso di questi materiali nella produzione di malte idrauliche (nel caso in cui la frazione allumo-silicatica sia elevata nella produzione di materiali a caratteristiche pozzolaniche), si potrebbe pensare di utilizzare le frazioni fini provenienti dal trattamento di C&D anche nella produzione di cementi e di prodotti ceramici

Educational Offers of University Museums: Towards a Shared Redesign with Territory

Nowadays we are witnessing a complex development of cultural demand as well as an escalating enrichment of educational networks: even university museums are committed to interact through their human and material resources with a wider audience. This paper focuses on the educational processes involved in two experiences carried out at the University of Padua: 1. the \u201cMuseum of Education\u201d, which was born as a place where to preserve and to study the history of education but which has soon widened its educational offer to schools and to the territory, by suggesting multiple and diversified approaches as requested from schools, cultural associations, local authorities, etc. 2. the partnership between CAM (University Centre for Museums) and ISS project for Padua whose aim is to improve the teaching of science. CAM and ISS are co-developing and sharing a common language (about educational and didactical issues) and they are jointly planning to develop new educational programs with schools and museums. Both experiences suggest we need to plan the University Heritage for the future applying a constructive dialogue between partners. This dialogue could pave the way for a shared redesign of the educational offer, which will then be perceived as a network of different organizations working to achieve common goal by using complementary strategies

New linewidth enhancement determination method in semiconductor lasers based on spectrum analysis above and below threshold

International audienceLinewidth measurements of singlemode and multimode InGaAsP lasers were made above and below threshold with adapted interferometers. Linewidth against inverse power plots, Δv = f(1/P), show different Schawlow–Townes slopes above and below threshold. Differences have been observed depending on singlemode or multimode laser behaviour. In the singlemode case the linewidth enhancement factor has been determined (α = 2.6) by extrapolating and correlating results above and below threshold