The UV spectrum of the bright quasar PHL 1811 at zem = 0.192 reveals a foreground gas system at z = 0.080923 with logN(H I) = 17.98 ± 0.05. We have determined the abundances of various atomic species in this system from a spectrum covering the wavelength range 1160 to 1730 Å recorded at 7 km s resolution by the E140M grating of STIS on the Hubble Space Telescope (HST), supplemented by coverage ...

We investigate the evolution of the star formation rate in the early Galaxy using beryllium and oxygen abundances in metal poor stars. Specifically, we show that stars belonging to two previously identified kinematical classes (the so-called “accretion” and “dissipative” populations) are neatly separated in the [O/Fe] vs. log(Be/H) diagram. The dissipative population follows the predictions of ...

We have calculated the evolution of low metallicity red giant stars under the assumption of deep mixing between the convective envelope and the hydrogen burning shell. We find that the extent of the observed abundance anomalies, and in particular the universal O-Na anticorrelation, can be totally explained by mixing which does not lead to significant helium enrichment of the envelope. On the ot...

In this study, we present a novel method to isolate and enrich low concentrations of Campylobacter pathogens. This method, Acanthamoeba-Campylobacter coculture (ACC), is based on the intracellular survival and multiplication of Campylobacter species in the free-living protozoan Acanthamoeba polyphaga. Four of the Campylobacter species relevant to humans and livestock, Campylobacter jejuni, C. c...

The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapid...

An ultra-high-resolution analysis of major and trace element contents from the Cretaceous-Paleogene boundary interval in the Caravaca section, southeast Spain, reveals a quick recovery of depositional conditions after the impact event. Enrichment/depletion profiles of redox sensitive elements indicate significant geochemical anomalies just within the boundary ejecta layer, supporting an instant...

[1] The carbon and oxygen isotopic compositions of tree ring cellulose were examined for trees along a precipitation gradient in western Oregon, United States. Two years of cellulose from four sites dominated by coniferous forests ranging in precipitation from 227 to 2129 mm were sampled in conjunction with studies that measured the dO and dC of ecosystem respiration. The mean tree ring cellulo...

The formation of formaldehyde via hydrogen atom transfer from the methoxy radical to molecular oxygen is a key step in the atmospheric photochemical oxidation of methane, and in the propagation of deuterium from methane to molecular hydrogen. We report the results of the first investigation of the branching ratio for HCHO and HCDO formation in the CH2DO + O2 reaction. Labeled methoxy radicals (...

We present the results of two-and three-dimensional calculations of turbulent nuclear burning of hydrogen-rich material accreted onto a white dwarf of 1.0 M. The main aim of the present paper is to investigate the question as to whether and how the general properties of the burning are aaected by dimension-ality and numerical resolution eeects. In particular, we want to see whether or not conve...

Basically, the activity of the methane oxidizing bacteria is limited by the availability of oxygen in the landfill cover soil. Enforced by the use of fine-grained soils like silt, the surface tends to crust due to vertical erosion, blocking pores required for gas exchange. A column study was carried out to examine the impact of vegetation on improving the aeration of critical soil material and ...