i) Pressure Support vs. Thermal Broadening in the Lyman-alpha Forest I: Effects of the Equation of State on Longitudinal Structure
astro-ph
ii) Pressure Support vs. Thermal Broadening in the Lyman-alpha Forest II: Effects of the Equation of State on Transverse Structure
astro-ph

i) D'Odorico et al.: The rise of the CIV mass density at z<2.5
astro-ph
ii) Barton & Cooke: MgII absorption characteristics of a volume-limited sample of galaxies at z~0.1
astro-ph

Abstract: We present new results from the SDSS Spectroscopic Quasar survey, examining the clustering properties of quasars via the 2-point correlation function. The evolution of quasar bias is discussed and put in context with recent observational measurements at z~2 and comparisons to theoretical models are made. We then look ahead to the high redshift part of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) which will use the existing SDSS telescope with upgraded spectrographs to perform a large galaxy and quasar redshift survey in order to provide a percent level measurement of the expansion history of the Universe at z<0.7 and z~2.5.

Abstract: In planetary nebulae, abundances of oxygen and other heavy elements derived from optical recombination lines are systematically higher than those derived from collisionally excited lines. I investigate the hypothesis that the destruction of solid bodies may produce pockets of cool, high-metallicity gas that could explain these abundance discrepancies. Under the assumption of maximally efficient radiative ablation, I derive two fundamental constraints that the solid bodies must satisfy in order that their evaporation during the planetary nebula phase should generate a high enough gas phase metallicity. A local constraint implies that the bodies must be larger than tens of meters, while a global constraint implies that the total mass of the solid body reservoir must exceed a few hundredths of a solar mass. This mass greatly exceeds the mass of any population of comets or large debris particles expected to be found orbiting evolved low- to intermediate-mass stars. I therefore conclude that contemporaneous solid body destruction cannot explain the observed abundance discrepancies in planetary nebulae. However, similar arguments applied to the sublimation of solid bodies during the preceding asymptotic giant branch (AGB) phase do not lead to such a clear-cut conclusion. In this case, the required reservoir of volatile solids is only one ten-thousandth of a solar mass, which is comparable to the most massive debris disks observed around solar-type stars, implying that this mechanism mazy contribute to abundance discrepancies in at least some planetary nebulae, so long as mixing of the high metallicity gas is inefficient.