Photometry of 40 LMC Cepheids

We present V and I_c CCD photometry for 40 LMC Cepheids at 1 to 3 epochs. This represents a significant increase in the number of LMC Cepheids with $I$-band data, and, as we show, is a useful addition to the sample which can be used to calibrate the period--luminosity relations in these important bands

Greening Consumer Electronics: Moving Away From Bromine and Chlorine

Presents case studies of seven electronics companies that have engineered environmental solutions that eliminate the use of most brominated and chlorinated chemicals that generate toxic materials. Discusses global standards and regulations

GRBs as Probes of the IGM

Gamma-ray Bursts (GRBs) are the most powerful explosions known, capable of outshining the rest of gamma-ray sky during their short-lived prompt emission. Their cosmological nature makes them the best tool to explore the final stages in the lives of very massive stars up to the highest redshifts. Furthermore, studying the emission from their low-energy counterparts (optical and infrared) via rapid spectroscopy, we have been able to pin down the exact location of the most distant galaxies as well as placing stringent constraints on their host galaxies and intervening systems at low and high-redshift (e.g. metallicity and neutral hydrogen fraction). In fact, each GRB spectrum contains absorption features imprinted by metals in the host interstellar medium (ISM) as well as the intervening intergalactic medium (IGM) along the line of sight. In this chapter we summarize the progress made using a large dataset of GRB spectra in understanding the nature of both these absorbers and how GRBs can be used to study the early Universe, in particular to measure the neutral hydrogen fraction and the escape fraction of UV photons before and during the epoch of re-ionization.Comment: 18 pages; 5 Figures. Accepted for publication in Space Science Review