204 research outputs found
On the Progenitors of Core-Collapse Supernovae
Theory holds that a star born with an initial mass between about 8 and 140
times the mass of the Sun will end its life through the catastrophic
gravitational collapse of its iron core to a neutron star or black hole. This
core collapse process is thought to usually be accompanied by the ejection of
the star's envelope as a supernova. This established theory is now being tested
observationally, with over three dozen core-collapse supernovae having had the
properties of their progenitor stars directly measured through the examination
of high-resolution images taken prior to the explosion. Here I review what has
been learned from these studies and briefly examine the potential impact on
stellar evolution theory, the existence of "failed supernovae", and our
understanding of the core-collapse explosion mechanism.Comment: 7 Pages, invited review accepted for publication by Astrophysics and
Space Science (special HEDLA 2010 issue
Efeito de sĂȘmen resfriado e diluĂdo em Beltsville Thawing Solution, Zorlesco-modificado e BTZOR no desempenho reprodutivo de fĂȘmeas suĂnas inseminadas
A estreita porta de entrada do Sistema Ănico de SaĂșde (SUS): uma avaliação do acesso na EstratĂ©gia de SaĂșde da FamĂlia
CaracterĂsticas espermĂĄticas de sĂȘmen resfriado de suĂno e conservado em diferentes diluentes
Performance and carcass traits of Santa InĂȘs lambs finished with different sources of forage
Pedunculated Morphology of T1 Colorectal Tumors Associates With Reduced Risk of Adverse Outcome
Cellular mechanisms in basic and clinical gastroenterology and hepatolog
Anticorpo monoclonal contra uma proteĂna macho-especĂfica de 19 kDa em espermatozĂłides bovinos: uma metodologia promissora para imunosexagem
Pilot-scale biofiltration at a materials recovery facility: The impact on bioaerosol control
This study investigated the performance of four pilot-scale biofilters for the removal of bioaerosols from waste airstreams in a materials recovery facility (MRF) based in Leeds, UK. A six-stage Andersen sampler was used to measure the concentrations of four groups of bioaerosols (Aspergillus fumigatus, total fungi, total mesophilic bacteria and Gram negative bacteria) in the airstream before and after passing through the biofilters over a period of 11 months. The biofilters achieved average removal efficiency (RE) of 70% (35 to 97%) for A. fumigatus, 71% (35 to 94%) for total fungi, 68% (47 to 86%) for total mesophilic bacteria and 50% (-4 to 85%) for Gram negative bacteria, provided that the inlet concentration was high (103â105 - cfu mïżœ3), which is the case for most waste treatment facilities. The performance was highly variable at low inlet concentration with some cases showing an increase in outlet concentrations, suggesting that biofilters had the potential to be net emitters of bioaerosols. The gas phase residence time did not appear to have any statistically significant impact on bioaerosol removal efficiency. Particle size distribution varied between the inlet and outlet air, with the outlet having a greater proportion of smaller sized particles that represent a greater human health risk as they can penetrate deep into the respiratory system where gaseous exchange occurs. However, the outlet concentrations were low and would further be diluted by wind in full scale applications. In conclusion, this study shows that biofilters designed and operated for odour degradation can also achieve significant bioaerosol control in waste gas
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