An r -process enhanced star in the dwarf galaxy Tucana III

Chemically peculiar stars in dwarf galaxies provide a window for exploring the birth environment of stars with varying chemical enrichment. We present a chemical abundance analysis of the brightest star in the newly discovered ultra-faint dwarf galaxy candidate Tucana III. Because it is particularly bright for a star in an ultra-faint Milky Way (MW) satellite, we are able to measure the abundance of 28 elements, including 13 neutron-capture species. This star, DES J235532.66−593114.9 (DES J235532), shows a mild enhancement in neutron-capture elements associated with the r-process and can be classified as an r-I star. DES J235532 is the first r-I star to be discovered in an ultra-faint satellite, and Tuc III is the second extremely low-luminosity system found to contain rprocess enriched material, after Reticulum II. Comparison of the abundance pattern of DES J235532 with r-I and r-II stars found in other dwarf galaxies and in the MW halo suggests a common astrophysical origin for the neutron-capture elements seen in all r-process enhanced stars. We explore both internal and external scenarios for the r-process enrichment of Tuc III and show that with abundance patterns for additional stars, it should be possible to distinguish between them

Candidate Polyanionic Microbicides Inhibit Human T-Cell Lymphotropic Virus Type 1 Receptor Interactions, Cell-Free Infection, and Cell-Cell Spread

The human T-cell lymphotropic virus type 1 (HTLV-1) is the cause of adult T-cell leukemia and inflammatory diseases including HTLV-1-associated myelopathy/tropical spastic paraparesis. HTLV-1 can be transmitted through sexual contact, mother-to-child transmission, and exposure to contaminated blood. Microbicides are agents that interfere with microbial infectivity at mucous membranes, and candidates are under development for use against sexually transmitted viruses such as human immunodeficiency virus type 1. We previously demonstrated that cell surface polyanionic heparan sulfate proteoglycans bind the HTLV-1 envelope glycoprotein surface subunit gp46, facilitating cell-cell and cell-free virus spread in vitro. We now show, using assays for Env-receptor binding inhibition, Env-induced cell-cell fusion, cell-cell virus spread, and pseudotype HTLV-1 infectivity, that the soluble polyanions PRO 2000 and dextran sulfate are potent inhibitors of HTLV-1 spread in vitro, with PRO 2000 being the more promising candidate. The results of these studies suggest that candidate topical microbicides may be of use in reducing HTLV-1 sexual transmission

A study of quasar selection in the supernova fields of the Dark Energy Survey

We present a study of quasar selection using the supernova fields of the Dark Energy Survey (DES). We used a quasar catalog from an overlapping portion of the SDSS Stripe 82 region to quantify the completeness and efficiency of selection methods involving color, probabilistic modeling, variability, and combinations of color/ probabilistic modeling with variability. In all cases, we considered only objects that appear as point sources in the DES images. We examine color selection methods based on the Wide-field Infrared Survey Explorer (WISE) mid- IR W1 - W2 color, a mixture of WISE and DES colors (g − i and i - W1), and a mixture of Vista Hemisphere Survey and DES colors (g − i and i − K ). For probabilistic quasar selection, we used XDQSO, an algorithm that employs an empirical multi-wavelength flux model of quasars to assign quasar probabilities. Our variability selection uses the multi-band χ2-probability that sources are constant in the DES Year 1 griz-band light curves. The completeness and efficiency are calculated relative to an underlying sample of point sources that are detected in the required selection bands and pass our data quality and photometric error cuts. We conduct our analyses at two magnitude limits, i85% for both i-band magnitude limits and efficiencies of >80% to the bright limit and >60% to the faint limit; however, the giW1 and giW1+variability methods give the highest quasar surface densities. The XDQSOz method and combinations of W1W2/giW1/XDQSOz with variability are among the better selection methods when both high completeness and high efficiency are desired. We also present the OzDES Quasar Catalog of 1263 spectroscopically confirmed quasars from three years of OzDES observation in the 30 deg2 of the DES supernova fields. The catalog includes quasars with redshifts up to z4 and brighter than i = 22 mag, although the catalog is not complete up to this magnitude limit