Accretion disks in Algols: progenitors and evolution

There are only a few Algols with measured accretion disk parameters. These measurements provide additional constraints for tracing the origin of individual systems, narrowing down the initial parameter space. We investigate the origin and evolution of 6 Algol systems with accretion disks to find the initial parameters and evolutionary constraints for them. With a modified binary evolution code, series of close binary evolution are calculated to obtain the best match for observed individual systems. Initial parameters for 6 Algol systems with accretion disks were determined matching both the present system parameters and the observed disk characteristics. When RLOF starts during core hydrogen burning of the donor, the disk lifetime was found to be short. The disk luminosity is comparable to the luminosity of the gainer during a large fraction of the disk lifetime.Comment: 8 pages, 6 figures , accepted by A&

The effect of intermediate mass close binaries on the chemical evolution of Globular Clusters

Context. The chemical processes during the Asymptotic Giant Branch (AGB) evolution of intermediate mass single stars predict most of the observations of the different populations in globular clusters although some important issues still need to be further clarified. In particular, to reproduce the observed anticorrelations of Na-O and Al-Mg, chemically enriched gas lost during the AGB phase of intermediate mass single stars must be mixed with matter with a pristine chemical composition. The source of this matter is still a matter of debate. Furthermore, observations reveal that a significant fraction of the intermediate mass and massive stars are born as components of close binaries. Aims. We will investigate the effects of binaries on the chemical evolution of Globular Clusters and on the origin of matter with a pristine chemical composition that is needed for the single star AGB scenario to work Methods. We use a population synthesis code that accounts for binary physics in order to estimate the amount and the composition of the matter returned to the interstellar medium of a population of binaries. Results. We demonstrate in the present paper that the mass lost by a significant population of intermediate mass close binaries in combination with the single star AGB pollution scenario may help to explain the chemical properties of the different populations of stars in Globular Clusters.Comment: 11 pages, 4 figures. Paper accepted for Astron. & Astrophy

A new approach to immunoFET operation

A new method is presented for the detection of an immunological reaction taking place in a membrane, which covers the gate area of an ISFET. By stepwise changing the electrolyte concentration of the sample solution, a transient diffusion of ions through the membrane-protein layer occurs, resulting in a transient membrane potential, which is measured by the ISFET. The diffusion rate is determined by the immobile charge density in the amphoteric protein layer, which changes upon formation of antibody—antigen complexes. No membrane potential is induced at zero fixed charge density as occurs at a protein characteristic pH. Isoeletric points of embedded proteins can be determined by detecting the zero potential response.\ud \ud Up to now, the authors have studied the membrane adsorption of lysozyme, human serum albumin (HSA) and the immune reaction of HSA with the antibody anti-human serum albumin (αHSA). The influence of protein parameters on the amplitude of the transient can be described with an empirical equation. Assuming Langmuir behaviour, the protein concentration in the solution can well be correlated with the concentration in the membrane.\ud \ud This new detection method is unique concerning direct measurements of charge densities and isoelectric points of amphoteric macromolecules adsorbed in the membrane. The simple procedure of one incubation stage followed by one detection stage, without separate washing and labelling techniques, gives direct information about specific charge properties of the macromolecules to be studied

Organic farming effects on clay dispersion in carbon-exhausted soils

Many Danish soils are depleted in organic matter (OM) after decades of intensive cereal cultivation (Schjønning et al., 2009). In this paper we show that clay particles (colloids) in soils that are low in OM content are easily dispersed in the soil water, which in turn has important effects on soil ecosystem functions and services. Organic farming systems generally tend to increase soil OM contents and may thus mitigate the negative effects

Molecular gas in extreme star-forming environments: the starbursts Arp220 and NGC6240 as case studies

We report single-dish multi-transition measurements of the 12^CO, HCN, and HCO^+ molecular line emission as well as HNC J=1-0 and HNCO in the two ultraluminous infra-red galaxies Arp220 and NGC6240. Using this new molecular line inventory, in conjunction with existing data in the literature, we compiled the most extensive molecular line data sets to date for such galaxies. The many rotational transitions, with their different excitation requirements, allow the study of the molecular gas over a wide range of different densities and temperatures with significant redundancy, and thus allow good constraints on the properties of the dense gas in these two systems. The mass (~(1-2) x 10^10 Msun) of dense gas (>10^5-6 cm^-3) found accounts for the bulk of their molecular gas mass, and is consistent with most of their IR luminosities powered by intense star bursts while self-regulated by O,B star cluster radiative pressure onto the star-forming dense molecular gas. The highly excited HCN transitions trace a gas phase ~(10-100)x denser than that of the sub-thermally excited HCO^+ lines (for both galaxies). These two phases are consistent with an underlying density-size power law found for Galactic GMCs (but with a steeper exponent), with HCN lines tracing denser and more compact regions than HCO^+. Whether this is true in IR-luminous, star forming galaxies in general remains to be seen, and underlines the need for observations of molecular transitions with high critical densities for a sample of bright (U)LIRGs in the local Universe -- a task for which the HI-FI instrument on board Herschel is ideally suited to do.Comment: 38 pages (preprint ApJ style), 3 figures, accepted for Ap