172 research outputs found
Castigo y responsabilidad: ensayos de filosofía del derecho
- Divulgação dos SUMÁRIOS das obras recentemente incorporadas ao acervo da Biblioteca Ministro Oscar Saraiva do STJ. Em respeito à Lei de Direitos Autorais, não disponibilizamos a obra na íntegra.- Localização na estante: 343:340.12 H325
Super and massive AGB stars - IV. Final fates - Initial to final mass relation
We explore the final fates of massive intermediate-mass stars by computing
detailed stellar models from the zero age main sequence until near the end of
the thermally pulsing phase. These super-AGB and massive AGB star models are in
the mass range between 5.0 and 10.0 Msun for metallicities spanning the range
Z=0.02-0.0001. We probe the mass limits M_up, M_n and M_mass, the minimum
masses for the onset of carbon burning, the formation of a neutron star, and
the iron core-collapse supernovae respectively, to constrain the white
dwarf/electron-capture supernova boundary. We provide a theoretical initial to
final mass relation for the massive and ultra-massive white dwarfs and specify
the mass range for the occurrence of hybrid CO(Ne) white dwarfs. We predict
electron-capture supernova (EC-SN) rates for lower metallicities which are
significantly lower than existing values from parametric studies in the
literature. We conclude the EC-SN channel (for single stars and with the
critical assumption being the choice of mass-loss rate) is very narrow in
initial mass, at most approximately 0.2 Msun. This implies that between ~ 2-5
per cent of all gravitational collapse supernova are EC-SNe in the metallicity
range Z=0.02 to 0.0001. With our choice for mass-loss prescription and computed
core growth rates we find, within our metallicity range, that CO cores cannot
grow sufficiently massive to undergo a Type 1.5 SN explosion.Comment: 15 pages, 7 figures, accepted for publication in MNRA
Sulindac Enhances the Killing of Cancer Cells Exposed to Oxidative Stress
BACKGROUND:Sulindac is an FDA-approved non-steroidal anti-inflammatory drug (NSAID) that affects prostaglandin production by inhibiting cyclooxygenases (COX) 1 and 2. Sulindac has also been of interest for more than decade as a chemopreventive for adenomatous colorectal polyps and colon cancer. PRINCIPAL FINDINGS:Pretreatment of human colon and lung cancer cells with sulindac enhances killing by an oxidizing agent such as tert-butyl hydroperoxide (TBHP) or hydrogen peroxide. This effect does not involve cyclooxygenase (COX) inhibition. However, under the conditions used, there is a significant increase in reactive oxygen species (ROS) within the cancer cells and a loss of mitochondrial membrane potential, suggesting that cell death is due to apoptosis, which was confirmed by Tunel assay. In contrast, this enhanced killing was not observed with normal lung or colon cells. SIGNIFICANCE:These results indicate that normal and cancer cells handle oxidative stress in different ways and sulindac can enhance this difference. The combination of sulindac and an oxidizing agent could have therapeutic value
Primordial to extremely metal-poor AGB and Super-AGB stars: White dwarf or supernova progenitors?
Getting a better understanding of the evolution and nucleosynthetic yields of the most metal-poor stars ( Z ¿ 10 ¿5 ) is critical because they are part of the big picture of the history of the primitive universe. Yet many of the remaining unknowns of stellar evolution lie in the birth, life, and death of these objects. We review stellar evolution of intermediate-mass Z = 10 ¿5 models existing in the literature, with a particular focus on the problem of their final fates. We emphasise the importance of the mixing episodes between the stellar envelope and the nuclearly processed core, which occur after stars exhaust their central He (second dredge-up and dredge-out episodes). The depth and efficiency of these episodes are critical to determine the mass limits for the formation of electron-capture SNe. Our knowledge of these phenomena is not complete because they are strongly affected by the choice of input physics. These uncertainties affect stars in all mass and metallicity ranges. However, difficulties in calibration pose additional challenges in the case of the most metal-poor stars. We also consider the alternative SN I1/2 channel to form SNe out of the most metal-poor intermediate-mass objects. In this case, it is critical to understand the thermally pulsing Asymptotic Giant Branch evolution until the late stages. Efficient second dredge-up and, later, third dredge-up episodes could be able to pollute stellar envelopes enough for the stars to undergo thermal pulses in a way very similar to that of higher initial Z objects. Inefficient second and/or third dredge-up may leave an almost pristine envelope, unable to sustain strong stellar winds. This may allow the H-exhausted core to grow to the Chandrasekhar mass before the envelope is completely lost, and thus let the star explode as an SN I1/2. After reviewing the information available on these two possible channels for the formation of SNe, we discuss existing nucleosynthetic yields of stars of metallicity Z = 10 ¿5 and present an example of nucleosynthetic calculations for a thermally pulsing Super-Asymptotic Giant Branch star of Z = 10 ¿5 . We compare theoretical predictions with observations of the lowest [Fe/H] objects detected. The review closes by discussing current open questions as well as possible fruitful avenues for future research.Peer ReviewedPostprint (author's final draft
The depth of sewage filters and the degree of purification
"Bulletins of the state Water survey": 1 leaf at end.At head of title: State of Illinois. Department of registration and education. Division of the state Water survey. A.M. Buswell, chief...Bibliography: p. 78-80.Enumeration continues from preceding title
Crop Updates 2006 - Katanning
This session covers sixteen papers from different authors
2006 SEASONAL OUTLOOK, David Stephens and Michael Meuleners, Department of Agriculture
Review of climate model summaries reported in the Department of Agriculture’s growing season outlooks, Meredith Fairbanks, Department of Agriculture
Farmers commodity outlook 2006, Thomas Schulz, Department of Agriculture
Why is salinity such a difficult problem for plant breeders? T J Flowers, TD Colmer, University of Western Australia
Matching nitrogen supply to wheat demand in 2005, Narelle Simpson, Ron McTaggart, Wal Anderson, Lionel Martin and Dave Allen, Department of Agriculture
Wheat varieties in 2006, Brenda Shackley, Department of Agriculture
Performance of dwarf potential milling oat varieties in Western Australian environments, Raj Malik and Kellie Winfield, Department of Agriculture
Field pea lessons for 2006, Rodger Beermir, Department of Agriculture
Better returns from Durum wheat, Shahahan Miyan, Department of Agriculture
Summer weeds can reduce grain yield and protein, Dr. Abul Hashem, Department of Agriculture, Dr Shahab Pathan, Department of Agriculture, Vikki Osten, Queensland Department of Primary Industries and Fisheries
Management of Summer Weeds, Alex Douglas, Department of Agriculture
Frost or Friction, Garren Knell, Steve Curtin, Wade Longmuir, Consult Ag Pty Ltd
PROFITING FROM MARGINAL LAND SEMINAR
Producing Bio-Diesel and rubber from marginal land?? Dr Henry Brockman, Department of Agriculture
SGSL Producer network – on ground implementation of saltbush based pastures, Justin Hardy, Arjen Ryder, John Paul Collins and Jessica Johns, Department of Agriculture
Enhancing the profitability of “Edenia” using saltbush and perenials, SGSL Producer case study, John Pepall, Jinka’s Hill LCDC
Investment in saltland pastures, Allan Herbert, Department of Agricultur
Roadmap on Electronic Structure Codes in the Exascale Era
Electronic structure calculations have been instrumental in providing many
important insights into a range of physical and chemical properties of various
molecular and solid-state systems. Their importance to various fields,
including materials science, chemical sciences, computational chemistry and
device physics, is underscored by the large fraction of available public
supercomputing resources devoted to these calculations. As we enter the
exascale era, exciting new opportunities to increase simulation numbers, sizes,
and accuracies present themselves. In order to realize these promises, the
community of electronic structure software developers will however first have
to tackle a number of challenges pertaining to the efficient use of new
architectures that will rely heavily on massive parallelism and hardware
accelerators. This roadmap provides a broad overview of the state-of-the-art in
electronic structure calculations and of the various new directions being
pursued by the community. It covers 14 electronic structure codes, presenting
their current status, their development priorities over the next five years,
and their plans towards tackling the challenges and leveraging the
opportunities presented by the advent of exascale computing.Comment: Submitted as a roadmap article to Modelling and Simulation in
Materials Science and Engineering; Address any correspondence to Vikram
Gavini ([email protected]) and Danny Perez ([email protected]
- …