5,472 research outputs found
Halo gas cross sections and covering fractions of MgII absorption selected galaxies
We examine halo gas cross sections and covering fractions, fc, of intermediate-redshift Mg II absorption selected galaxies. We computed statistical absorber halo radii, Rx, using current values of dN/dz and Schechter luminosity function parameters, and have compared these values to the distribution of impact parameters and luminosities from a sample of 37 galaxies. For equivalent widths Wr(2796) ā„ 0.3 Ć
, we find 43 ā¤ Rx ā¤ 88 kpc, depending on the lower luminosity cutoff and the slope, Ī², of the Holmberg-like luminosity scaling, R ā Ī± L^Ī² . The observed distribution of impact parameters, D, are such that several absorbing galaxies lie at D > Rx and several non-absorbing galaxies lie at D ~ 0.5 for our sample. Moreover, the data suggest that halo radii of Mg II absorbing galaxies do not follow a luminosity scaling with Ī² in the range of 0.2ā0.28, if fc = 1 as previously reported. However, provided fc ~ 0.5, we find that halo radii can remain consistent with a Holmberg-like luminosity relation with Ī² ā 0.2 and Rā = Rx/ā(fc) ~ 110 kpc. No luminosity scaling (Ī² = 0) is also consistent with the observed distribution of impact parameters if fc ā¤ 0.37. The data support a scenario in which gaseous halos are patchy and likely have non-symmetric geometric distributions about the galaxies. We suggest that halo gas distributions may not be governed primarily by galaxy mass/luminosity but also by stochastic processes local to the galaxy
Deuterium Abundance in the Most Metal-Poor Damped Lyman alpha System: Converging on Omega_baryons
The most metal-poor DLA known to date, at z = 2.61843 in the spectrum of the
QSO Q0913+072, with an oxygen abundance only about 1/250 of the solar value,
shows six well resolved D I Lyman series transitions in high quality echelle
spectra recently obtained with the ESO VLT. We deduce a value of the deuterium
abundance log (D/H) = -4.56+/-0.04 which is in good agreement with four out of
the six most reliable previous determinations of this ratio in QSO absorbers.
We find plausible reasons why in the other two cases the 1 sigma errors may
have been underestimated by about a factor of two. The addition of this latest
data point does not change significantly the mean value of the primordial
abundance of deuterium, suggesting that we are now converging to a reliable
measure of this quantity. We conclude that = -4.55+/-0.03 and
Omega_b h^2 (BBN) = 0.0213+/-0.0010 (68% confidence limits). Including the
latter as a prior in the analysis of the five year data of WMAP leads to a
revised best-fitting value of the power-law index of primordial fluctuations
n_s = 0.956+/-0.013 (1 sigma) and n_s < 0.990 with 99% confidence. Considering
together the constraints provided by WMAP 5, (D/H)_p, baryon oscillations in
the galaxy distribution, and distances to Type Ia supernovae, we arrive at the
current best estimates Omega_b h^2 = 0.0224+/-0.0005 and n_s = 0.959+/-0.013.Comment: 13 pages, 8 Figures. Revised version following referee's comments.
Accepted for publication in Monthly Notices of the Royal Astronomical
Society. A few typos correcte
Marooned on an Extinct Volcano: the Conservation Status of Four Endemic Land Snails (Gastropoda: Pulmonata) at Mount Kaputar, New South Wales
Volcanic activity in northern inland New South Wales between 40 and 15 million years ago was followed by general continental-scale drying and coastward contraction of mesic ecosystems between 15 and 2 million years ago. Together, these processes resulted in the creation of high-elevation climatic refuges such as Coolah Tops, Mount Kaputar and the Warrumbungle Range as western outposts of the mesic eastern highlands on the dry western slopes. These areas are important hotspots of land snail species diversity and endemism. A high-elevation and dry rainforest land snail community at Mount Kaputar, recognised as being of outstanding conservation signiļ¬cance, was listed as an endangered ecological community under NSW legislation in 2013. Two species from this community, the Kaputar Pink Slug Triboniophorus sp. nov. āKaputarā and Bronze Rippled Pinwheel Snail Cralopa kaputarensis , are currently listed on the IUCN Red List , as endangered and data deļ¬cient respectively. This paper provides an updated assessment of the conservation status of the Kaputar Pink Slug, a reassessment of the Bronze Rippled Pinwheel Snail and original assessment of another two endemic Mount Kaputar species (Kaputar Carnivorous Snail Vitellidelos kaputarensis and Kaputar Keeled Snail Thersites sp. nov. āKaputarā), concluding that all four species meet the criteria for listing as endangered on the IUCN Red List
Structural/functional analysis of the human OXR1 protein: identification of exon 8 as the anti-oxidant encoding function
BACKGROUND: The human OXR1 gene belongs to a class of genes with conserved functions that protect cells from reactive oxygen species (ROS). The gene was found using a screen of a human cDNA library by its ability to suppress the spontaneous mutator phenotype of an E. coli mutH nth strain. The function of OXR1 is unknown. The human and yeast genes are induced by oxidative stress and targeted to the mitochondria; the yeast gene is required for resistance to hydrogen peroxide. Multiple spliced isoforms are expressed in a variety of human tissues, including brain.
RESULTS: In this report, we use a papillation assay that measures spontaneous mutagenesis of an E. coli mutM mutY strain, a host defective for oxidative DNA repair. Papillation frequencies with this strain are dependent upon a G-\u3eT transversion in the lacZ gene (a mutation known to occur as a result of oxidative damage) and are suppressed by in vivo expression of human OXR1. N-terminal, C-terminal and internal deletions of the OXR1 gene were constructed and tested for suppression of the mutagenic phenotype of the mutM mutY strain. We find that the TLDc domain, encoded by the final four exons of the OXR1 gene, is not required for papillation suppression in E. coli. Instead, we show that the protein segment encoded by exon 8 of OXR1 is responsible for the suppression of oxidative damage in E. coli.
CONCLUSION: The protein segment encoded by OXR1 exon 8 plays an important role in the anti-oxidative function of the human OXR1 protein. This result suggests that the TLDc domain, found in OXR1 exons 12-16 and common in many proteins with nuclear function, has an alternate (undefined) role other than oxidative repair
Mitochondria as a therapeutic target for common pathologies.
Although the development of mitochondrial therapies has largely focused on diseases caused by mutations in mitochondrial DNA or in nuclear genes encoding mitochondrial proteins, it has been found that mitochondrial dysfunction also contributes to the pathology of many common disorders, including neurodegeneration, metabolic disease, heart failure, ischaemia-reperfusion injury and protozoal infections. Mitochondria therefore represent an important drug target for these highly prevalent diseases. Several strategies aimed at therapeutically restoring mitochondrial function are emerging, and a small number of agents have entered clinical trials. This Review discusses the opportunities and challenges faced for the further development of mitochondrial pharmacology for common pathologies
Teaching important relational skills for children with autism spectrum disorder and intellectual disability using freely available (GO-IRAP) software
Prison as Seen by Convict Criminologists
Most criminologists tend to base their view of prison on ideological assumptions gathered from secondary sources, with at best limited entry to the prison world. They nearly always get it wrong, as they systematically exclude the perspectives and real life experiences of their human subjects. These academic researchers have contributed to poor public policy that promotes the violent repression of prisoners in the USA and other countries. In response, Convict Criminologists are exāconvicts working as criminology and criminal justice professors, along with ānonāconā associates, that insist that as a means for societies to develop humane, effective, and cost efficient prisons, we must develop ways to incorporate the voice of prisoners in our theorizing about, policy recommendations for, and management of the prison
Aggressive Surveillance Is Needed to Detect Endoleaks and Junctional Separation between Device Components after Zenith Fenestrated Aortic Reconstruction
Background
Junctional separation and resulting type IIIa endoleak is a well-known problem after EVAR (endovascular aneurysm repair). This complication results in sac pressurization, enlargement, and eventual rupture. In this manuscript, we review the incidence of this late finding in our experience with the Cook Zenith fenestrated endoprosthesis (ZFEN, Bloomington, IN).
Methods
A retrospective review was performed of a prospectively maintained institutional ZFEN fenestrated EVAR database capturing all ZFENs implanted at a large-volume, academic hospital system. Patients who experienced junctional separation between the fenestrated main body and distal bifurcated graft (with or without type IIIa endoleak) at any time after initial endoprosthesis implantation were subject to further evaluation of imaging and medical records to abstract clinical courses.
Results
In 110 ZFENs implanted from October 2012 to December 2017 followed for a mean of 1.5 years, we observed a 4.5% and 2.7% incidence of clinically significant junctional separation and type IIIa endoleak, respectively. Junctional separation was directly related to concurrent type Ib endoleak in all 5 patients. Three patients presented with sac enlargement. One patient did not demonstrate any evidence of clinically significant endoleak and had a decreasing sac size during follow-up imaging. The mean time to diagnosis of modular separation in these patients was 40 months. Junctional separation was captured in surveillance in 2 patients and reintervened upon before manifestation of endoleak. However, the remaining 3 patients completed modular separation resulting in rupture and emergent intervention in 2 and an aortic-related mortality in the other.
Conclusions
Junctional separation between the fenestrated main and distal bifurcated body with the potential for type IIIa endoleak is an established complication associated with the ZFEN platform. Therefore, we advocate for maximizing aortic overlap during the index procedure followed by aggressive surveillance and treatment of stent overlap loss captured on imaging
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