Dust and Metal Column Densities in Gamma-Ray Burst Host Galaxies

In this paper we present the results from the analysis of a sample of 28 gamma-ray burst (GRB) afterglow spectral energy distributions, spanning the X-ray through to near-infrared wavelengths. This is the largest sample of GRB afterglow spectral energy distributions thus far studied, providing a strong handle on the optical depth distribution of soft X-ray absorption and dust-extinction systems in GRB host galaxies. We detect an absorption system within the GRB host galaxy in 79% of the sample, and an extinction system in 71% of the sample, and find the Small Magellanic Cloud (SMC) extinction law to provide an acceptable fit to the host galaxy extinction profile for the majority of cases, consistent with previous findings. The range in the soft X-ray absorption to dust-extinction ratio, N_{H,X}/Av, in GRB host galaxies spans almost two orders of magnitude, and the typical ratios are significantly larger than those of the Magellanic Clouds or Milky Way. Although dust destruction could be a cause, at least in part, for the large N_{H,X}/Av ratios, the good fit provided by the SMC extinction law for the majority of our sample suggests that there is an abundance of small dust grains in the GRB environment, which we would expect to have been destroyed if dust destruction were responsible for the large N_{H,X}/Av ratios. Instead, our analysis suggests that the distribution of N_{H,X}/Av in GRB host galaxies may be mostly intrinsic to these galaxies, and this is further substantiated by evidence for a strong negative correlation between N_{H,X}/Av and metallicity for a subsample of GRB hosts with known metallicity. Furthermore, we find the N_{H,X}/Av ratio and metallicity for this subsample of GRBs to be comparable to the relation found in other more metal-rich galaxies.Comment: 23 pages, 10 figures, accepted for publication in MNRA

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Relaxing Goodness is Still Good for SPDIs

Polygonal hybrid systems (SPDIs) are planar hybrid systems, whose dynamics are defined in terms of constant differential inclusions, one for each of a number of polygonal regions partitioning the plane. The reachability problem for SPDIs is known to be decidable, but depends on the goodness assumption — which states that the dynamics do not allow a trajectory to both enter and leave a region through the same edge. In this paper we extend the decidability result to generalised SPDIs (GSPDI), SPDIs not satisfying the goodness property, and give an algorithmic solution to decide reachability of such systems.

Pharmacokinetics of Solithromycin (CEM-101) after Single or Multiple Oral Doses and Effects of Food on Single-Dose Bioavailability in Healthy Adult Subjects▿

The pharmacokinetics of orally administered solithromycin (CEM-101), a novel fluoroketolide, were evaluated in healthy subjects in three phase 1 studies. In two randomized, double-blinded, placebo-controlled studies, escalating single oral doses of solithromycin (50 to 1,600 mg) or seven oral daily doses (200 to 600 mg) of solithromycin were administered. A third study evaluated the effects of food on the bioavailability of single oral doses (400 mg) of solithromycin. Following single doses, the median time to peak concentration (Tmax) ranged from 1.5 h to 6 h. The mean maximum measured plasma concentration (Cmax) ranged from 0.0223 μg/ml to 19.647 μg/ml, and the area under the concentration-versus-time curve from time zero to time t (AUC0–t) ranged from 0.0402 μg · h/ml to 28.599 μg · h/ml. There was no effect of high-fat food on the oral bioavailability of solithromycin. In the multiple-dose study, after 7 days, the mean maximum measured plasma solithromycin concentration at steady-state (Cmax,ss) ranged from 0.248 to 1.50 μg/ml, and the area under the concentration-versus-time curve over the final dosing interval (AUCτ) ranged from 2.310 to 18.41 μg · h/ml. These values indicate a greater than proportional increase in exposure at 200 and 400 mg but a proportional exposure at 600 mg. Median Tmax values remained constant between day 1 and day 7. Moderate accumulation ratios of solithromycin were observed after 7 days of dosing. All dose regimens of solithromycin were well tolerated, and no discontinuations due to an adverse event occurred. The human pharmacokinetic profile and tolerability of solithromycin, combined with its in vitro potency and efficacy in animal models against a broad spectrum of pathogens, support further development of solithromycin

International perspectives on quality in initial teacher education : an exploratory review of selected international documentation on statutory requirements and quality assurance

This review aims to inform both the policy and the research debates about the relationship between the organisation, management and framework for initial teacher education and its quality. It aims to inform the policy debate by providing an analytical, but accessible, international review of the evidence about, and approaches to, the impact of structures on quality. Further, it aims to support the development of practice by offering a systematic survey of international perspectives on the relationship between structures and quality