Photoselective Metal Deposition on Amorphous Silicon p-i-n Solar Cells\ud

A novel method is described for the patternwise metallization of amorphous silicon solar cells, based on photocathodic deposition. The electric field of the p-i-n structure is used for the separation of photogenerated charge carriers. The electrons are driven to the interface of the n+-layer with the solution where they reduce metal ions to metal. The large difference between the conductivity of dark and illuminated areas and the high sheet resistance of the n-type layer makes it possible to define a metal pattern by selective illumination. It is shown that both nickel and gold patterns can be deposited using this method. After annealing, an ohmic nickel contact is formed and the cell exhibits good photovoltaic characteristics

Etude du régime alimentaire de la Chouette effraie Tyto alba (Strigiforme,Tytonidae) dans la région de Lalla Mimouna dans la plaine du Gharb, plaine du Maroc atlantique

Nous présentons dans ce travail les résultats de l’analyse du régime alimentaire d’un rapace nocturne (la Chouette effraie Tyto alba) dans les plaines du Maroc atlantique à partir de plusieurs lots de pelotes de réjection collectées en 2012. Il s’agit de deux régions de la plaine du Gharb, une située dans un milieu forestier anthropisé (Sidi Boubker El Haj) et l’autre en plein milieu irrigué et intensément cultivé (domaine des Drader à Moulay Bousselhame). L’étude des pelotes a fournie 1285 proies réparties sur plusieurs groupes zoologiques formants l’essentiel du régime de ce rapace. Les mammifères sont beaucoup plus représentés avec environ 64% de ce régime, les insectes sont représentés avec plus de 27% alors que les oiseaux et les amphibiens forment moins de 10%. Ce régime diffère fortement de celui des effraies des plaines semi-arides du Maroc atlantique (Rihane, 2003, 2004 et 2005) caractérisé par une nette abondance des oiseaux.Mots-clés: régime alimentaire, chouette effraie, Lalla Mimouna , plaine du Gharb, Maroc atlantique. Study of the diet of the Barn Owl Tyto alba (Strigiforme, Tytonidae) in Lalla Mimouna region in the Gharb plain (plain of Atlantic Morocco)We present in this work the results of the analysis of the diet of the Barn owl Tyto alba in the plains of Atlantic Morocco, from several batches of diet pellets collected in 2012. These study covers two regions of the Gharb plain, one located in ananthropized forest (Sidi Boubker El Haj) and the other in the middle irrigated and intensively cultivated (field Drader Moulay Bouselhame). The study of several lots of pellets has provided 1285 prey over several zoological groups making the most of the diet of this predator. Mammals are much more represented with approximately 64% of the diet,the insects are strongly represented with more than 27% while birds and amphibians make up less than 10%. The scheme of this diet differs greatly from that of semi-arid plains of Atlantic Morocco (Rihane, 2003, 2004 and 2005) characterized by a marked abundance of birds.Keywords: diet, barn Owl, Lalla Mimouna, gharb plain, Atlantic Morocco

Microscopic nanomechanical dissipation in gallium arsenide resonators

We report on a systematic study of nanomechanical dissipation in high-frequency (approximatively 300 MHz) gallium arsenide optomechanical disk resonators, in conditions where clamping and fluidic losses are negligible. Phonon-phonon interactions are shown to contribute with a loss background fading away at cryogenic temperatures (3 K). Atomic layer deposition of alumina at the surface modifies the quality factor of resonators, pointing towards the importance of surface dissipation. The temperature evolution is accurately fitted by two-level systems models, showing that nanomechanical dissipation in gallium arsenide resonators directly connects to their microscopic properties. Two-level systems, notably at surfaces, appear to rule the damping and fluctuations of such high-quality crystalline nanomechanical devices, at all temperatures from 3 to 300K

Carbonate mounds of the Moroccan Mediterranean margin: Facies and environmental controls

Sedimentological and geochemical studies of boxcores from the Brittlestar Ridge I and Cabliers carbonate mounds, along the Moroccan Mediterranean margin, show that sediments are composed of cold water scleratian corals and micritic mud, muddy micrite or muddy allochem limestone matrix, outlining seven different facies that can be attributed to “cluster reefs”. The mixed siliciclastic/carbonate sediments have been derived from both extra- and intrabasinal sources. Extra-basinal sources may be the geological formations outcropping in the Moroccan hinterland and Sahara, the latter including corals and associated bioclasts. Sediments were transported by wind and rivers and redistributed by bottom currents and local upwelling. Our results confirm the role of tectonics in the genesis of these carbonate mounds and reveal that their developments during the Holocene (10.34–0.91ka BP) was controlled by climatic fluctuations (e.g. Holocene Climate Optimum and Little Ice Age), eustatic sea level change, and hydrodynamic regime

Palaeomagnetism of the Ordovician dolerites of the Crozon Peninsula (France)

In order to obtain a Lower Palaeozoic pole for the Armorican Massif and to test the origin of the Ibero-Armorican arc, the Ordovician dolerites of the Crozon peninsula have been palaeomagnetically studied. The samples show a multicomponent magnetization which has been revealed by AF and thermal demagnetization and thoroughly investigated with rock magnetic experiments, polished section examinations and K/Ar dating. Four groups of directions have been recognized, often superimposed on each other in an individual sample. One component (D) has always the lowest blocking temperatures and coercivities and is considered to be of viscous origin, acquired recently in situ or in the laboratory during storage. Two components (A and B) are interpreted to be of secondary origin and to correspond to the observed K/Ar age distribution between 300 and 190 Myr. These ages represent the time interval between two regional thermo-tectonic events, associated with the Hercynian orogeny and the intrusion of dykes related to the early opening of the Central Atlantic Ocean and the Bay of Biscay. A fourth component (C) could be of Ordovician or younger Palaeozoic age; it is not clear whether the age of the magnetization is pre- or post-folding, but a pre-folding age would yield a direction of magnetization similar to Ordovician results from the Iberian peninsula. The latter interpretation suggests a fairly high palaeolatitude, which is in agreement with a glacio-marine postulated for sediments overlying the dolerite sills.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73214/1/j.1365-246X.1983.tb03785.x.pd