Use of diamond sensors for a high-flux, high-rate X-ray pass-through diagnostic.

X-ray free-electron lasers (XFELs) deliver pulses of coherent X-rays on the femtosecond time scale, with potentially high repetition rates. While XFELs provide high peak intensities, both the intensity and the centroid of the beam fluctuate strongly on a pulse-to-pulse basis, motivating high-rate beam diagnostics that operate over a large dynamic range. The fast drift velocity, low X-ray absorption and high radiation tolerance properties of chemical vapour deposition diamonds make these crystals a promising candidate material for developing a fast (multi-GHz) pass-through diagnostic for the next generation of XFELs. A new approach to the design of a diamond sensor signal path is presented, along with associated characterization studies performed in the XPP endstation of the LINAC Coherent Light Source (LCLS) at SLAC. Qualitative charge collection profiles (collected charge versus time) are presented and compared with those from a commercially available detector. Quantitative results on the charge collection efficiency and signal collection times are presented over a range of approximately four orders of magnitude in the generated electron-hole plasma density.

Selection and evolutionary potential of spring arrival phenology in males and females of a migratory songbird.

The timing of annual life-history events affects survival and reproduction of all organisms. A changing environment can perturb phenological adaptations and an important question is if populations can evolve fast enough to track the environmental changes. Yet, little is known about selection and evolutionary potential of traits determining the timing of crucial annual events. Migratory species, which travel between different climatic regions, are particularly affected by global environmental changes. To increase our understanding of evolutionary potential and selection of timing traits, we investigated the quantitative genetics of arrival date at the breeding ground using a multigenerational pedigree of a natural great reed warbler (Acrocephalus arundinaceus) population. We found significant heritability of 16.4% for arrival date and directional selection for earlier arrival in both sexes acting through reproductive success, but not through lifespan. Mean arrival date advanced with 6 days over 20 years, which is in exact accordance with our predicted evolutionary response based on the breeder's equation. However, this phenotypic change is unlikely to be caused by microevolution, because selection seems mainly to act on the nongenetic component of the trait. Furthermore, demographical changes could also not account for the advancing arrival date. Instead, a strong correlation between spring temperatures and population mean arrival date suggests that phenotypic plasticity best explains the advancement of arrival date in our study population. Our study dissects the evolutionary and environmental forces that shape timing traits and thereby increases knowledge of how populations cope with rapidly changing environments.

Relative efficacy of chelating agents as antidotes for acute nickel(II) acetate intoxication.

The relative efficacy of 14 chelating agents in alleviating acute nickel(II) acetate (ip) intoxication has been determined. The LD50 for ip nickel(II) acetate in mice was found to be 45.7 mg/kg with a 95% confidence limit of 39.2--53.3 mg/kg. For a level of 62 mg/kg ip of nickel(II) acetate (i.e. approximately LD90 or greater), the most effective antidotes were D-penicillamine and Na2CaEDTA, but several other chelating agents with rather different arrangements of donor atoms were almost as effective. The acetylation of the amino group in penicillamine to give N-Acetyl-D,L-penicillamine effectively destroys the antidotal action, as would be expected if coordination to the nitrogen were essential to the process.

The relative effectiveness of some chelating agents in acute copper intoxication in the mouse.

The relative efficacy of 9 chelating agents in offsetting the acute toxicity of ip copper sulfate has been determined. Included in this group are almost all of the compounds which have been used in, or suggested for use in human cases of acute or chronic copper toxicity. Under the conditions used, sodium 2,3-dimercapto-1-propanesulfonate is by far the most effective antidote of the compounds examined.