Host Galaxies of Gamma-ray Bursts: Spectral Energy Distributions and Internal Extinction

We present BVRcIc broad-band flux spectra for the host galaxies of GRB970508, GRB980613, GRB980703, GRB990123 and GRB991208 obtained with the 6-m telescope of SAO RAS. The BVRcIc of these hosts are best fitted by the spectral properties of template SEDs of starburst galaxies and that there is a significant internal extinction in these host galaxies. We derived the absolute magnitudes of the GRB host galaxies making use of SEDs for the starburst galaxies. We performed the population synthesis modeling of the continuum spectral energy distribution of the host galaxies of GRB970508 and GRB980703 using different extinction laws and assuming burst and exponential scenarios of star formation. The comparison of BVRcIc broad-band flux spectra with the local starburst galaxies templates and theoretical templates as well as direct estimates (using Balmer emission lines) of the internal extinction shows that it is likely to be of great importance to take into account effects of the internal extinction in the host galaxies. From the SED of the host galaxy of GRB991208 and from the intensity of their spectral lines it follows that this is a GRB galaxy with the highest massive star-formation rate of all known GRB galaxies. The reduced luminosity of these dusty galaxies (e.g. for the host of GRB970508 A_V\sim 2 mag, for the host of GRB980703 A_V\sim 0.6 mag and for the host of GRB991208 A_V\sim 2 mag) could explain the observational fact: none of the observed GRB host galaxies with known distances is brighter than the local galaxies with the luminosity L_*.Comment: Added acknowledgement

Evaluation of PCR Testing of Ethanol-Fixed Nasal Swab Specimens as an Augmented Surveillance Strategy for Influenza Virus and Adenovirus Identification

Viral culture isolation has been widely accepted as the “gold standard” for laboratory confirmation of viral infection; however, it requires ultralow temperature specimen storage. Storage of specimens in ethanol at room temperature could expand our ability to conduct active surveillance and retrospective screenings of viruses with rapid and inexpensive real-time PCR tests, including isolates from remote regions where freezing specimens for culture is not feasible. Molecular methods allow for rapid identification of viral pathogens without the need to maintain viability. We hypothesized that ethanol, while inactivating viruses, can preserve DNA and RNA for PCR-based methods. To evaluate the use of ethanol-stored specimens for augmenting surveillance for detection of influenza viruses A and B and adenoviruses (AdV), paired nasal swab specimens were collected from 384 recruits with febrile respiratory illness at Fort Jackson, S.C., in a 2-year study. One swab was stored at ambient temperature in 100% ethanol for up to 6 months, and the other swab was stored at −70°C in viral medium. For viral detection, frozen specimens were cultured for a variety of respiratory viruses, and ethanol-fixed specimens were tested with TaqMan (TM) probe and LightCycler SYBR green (SG) melting curve assays with at least two different PCR targets for each virus. The sensitivities of the TM and SG assays on specimens stored in ethanol for 1 month were 75% and 58% for influenza A, 89% and 67% for influenza B, and 93 to 98% and 57% for AdV, respectively. Lower specificities of the real-time assays corresponded to the increased detection of PCR-positive but culture-negative specimens. Influenza virus RNA was detected as well or better after 6 months of storage in ethanol

Educator supply and demand in the South African public education system: integrated report

Education plays a key role in the development of any society. Responding to the need for empirical evidence on the demand for and supply of public educators in South Africa, the Education Labour Relations Council (ELRC) commissioned the Human Sciences Research Council-led consortium to conduct nation-wide research on the factors determining educator supply and demand in South African public education system. Growth demand for educators depends on learner enrolments and the learner-educator ratio, while replacement demand for educators depends on employment trends, demographics and attrition (including morbidity and morality). Educator supply depends on a number of factors, such as education graduates, morbidity and morality, and educators returning after a break from the profession. This report is an integration of the seven reports which emerged from the research, and pulls together the findings arising from it. What emerges is that the resignation, death and ageing of the present educator force is likely to have a significant effect on replacement demand for educators over the next four years