Average mass of seeds encountered by foraging dabbling ducks in Western Europe

Many dabbling ducks Anas spp. are largely granivorous, consuming a variety of seeds chiefly from aquatic plants. To assess the relative value and carrying capacity of wetlands for dabbling ducks, species-specific information about seed mass is needed, but it is still largely missing or scattered in the literature. By combining weights of seeds collected in the field with a literature review, we provide a reference table for seed mass of 200 western European plant taxa frequently encountered by foraging dabbling ducks. Seeds collected in the field were sampled in microhabitats and at depths at which ducks were observed to forage, and study sites represent wintering, staging as well as breeding areas within a flyway in western Europe. When combined with calorimetric data, the present reference table will aid managers and scientists in assessing the importance of seed food resources at different sites and during different parts of the annual cycle.</p

Polycrystalline Solar Cells From Up-graded Metallurgical Silicon.

A process to obtain solar grade polycrystalline silicon from metallurgical silicon is presented. The raw material (99% purity) is purified by chemical leaching, melted in a graphite crucible and unidirectionally solidified. Results on impurity content at each step of the process and on the final structure are presented. p-n solar cells were fabricated on selected wafers. Conversion efficiencies greater than 5% were obtained for small-area cells. Future improvements are considered.1395139

Focal-plane-assisted pyramid wavefront sensor: Enabling frame-by-frame optical gain tracking

Aims. With its high sensitivity, the pyramid wavefront sensor (PyWFS) is becoming an advantageous sensor for astronomical adaptive optics (AO) systems. However, this sensor exhibits significant non-linear behaviours leading to challenging AO control issues. Methods. In order to mitigate these effects, we propose to use in addition to the classical pyramid sensor a focal plane image combined with a convolutive description of the sensor to fast track the PyWFS non-linearities, the so-called optical gains (OG). Results. We show that this additional focal plane imaging path only requires a small fraction of the total flux while representing a robust solution to estimating the PyWFS OG. Finally, we demonstrate the gain that our method brings with specific examples of bootstrapping and handling non-common path aberrations