The Triassic-Jurassic boundary in eastern North America

Rift basins of the Atlantic passive margin in eastern North America are filled with thousands of meters of continental rocks termed the Newark Supergroup which provide an unprecedented opportunity to examine the fine scale structure of the Triassic-Jurassic mass extinction in continental environments. Time control, vital to the understanding of the mechanisms behind mass extinctions, is provided by lake-level cycles apparently controlled by orbitally induced climate change allowing resolution at the less than 21,000 year level. Correlation with other provinces is provided by a developing high resolution magnetostratigraphy and palynologically-based biostratigraphy. A large number of at least local vertebrate and palynomorph extinctions are concentrated around the boundary with survivors constituting the earliest Jurassic assemblages, apparently without the introduction of new taxa. The palynofloral transition is marked by the dramatic elimination of a relatively high diversity Triassic pollen assemblage with the survivors making up a Jurassic assemblage of very low diversity overwhelmingly dominated by Corollina. Based principally on palynological correlations, the hypothesis that these continental taxonomic transitions were synchronous with the massive Triassic-Jurassic marine extinctions is strongly corroborated. An extremely rapid, perhaps catastrophic, taxonomic turnover at the Triassic-Jurassic boundary, synchronous in continental and marine realms is hypothesized and discussed

Detailed opacity calculations for astrophysical applications

Nowadays, several opacity codes are able to provide data for stellar structure models, but the computed opacities may show significant differences. In this work, we present state-of-the-art precise spectral opacity calculations, illustrated by stellar applications. The essential role of laboratory experiments to check the quality of the computed data is underlined. We review some X-ray and XUV laser and Z-pinch photo-absorption measurements as well as X-ray emission spectroscopy experiments involving hot dense plasmas produced by ultra-high-intensity laser irradiation. The measured spectra are systematically compared with the fine-structure opacity code SCO-RCG. Focus is put on iron, due to its crucial role in understanding asteroseismic observations of $\beta$ Cephei-type and Slowly Pulsating B stars, as well as of the Sun. For instance, in $\beta$ Cephei-type stars, the iron-group opacity peak excites acoustic modes through the "kappa-mechanism". A particular attention is paid to the higher-than-predicted iron opacity measured at the Sandia Z-machine at solar interior conditions. We discuss some theoretical aspects such as density effects, photo-ionization, autoionization or the "filling-the-gap" effect of highly excited states.Comment: submitted to "Atoms

Detailed Opacity Calculations for Stellar Models

Radiative opacity is an important quantity in the modeling of stellar structure and evolution. In the present work we recall the role of opacity in the interpretation of pulsations of different kinds of stars. The detailed opacity code SCO-RCG for local-thermodynamic-equilibrium (LTE) plasmas is described, as well as the OPAMCDF project dedicated to the spectroscopy of LTE and non-LTE plasmas. Interpretations, with the latter codes, of several laser and Z pinch experiments in conditions relevant to astrophysical applications are also presented and our work in progress as concerns the internal solar conditions is illustrated.Comment: submitted to ASP Conf. Se

En Torno a La Filantropía de las Elites Económicas en España: un estudio empírico como punto de partida

De la investigación de las pautas filantrópicas de aquellos que integran el segmento con más recursos económicos de una sociedad cabe extraer información no sólo sobre cómo sus miembros entienden y practican la filantropía, sino también sobre cómo perciben la sociedad y el Estado, y cómo se perciben a sí mismos en relación con una y otro

Evolution of employment of female immigrants in the Spanish labour market. The impact of the current financial crisis

Este artículo aborda el impacto de la actual crisis económica sobre el nivel de ocupación de las mujeres inmigrantes. Para ello se utilizan datos de la Encuesta de Población Activa desde 2000 hasta 2010. Los resultados muestran que las mujeres extranjeras están soportando mejor el efecto de la recesión que sus connacionales, cuyas tasas de paro han crecido en mayor medida. Además, el capital humano de las mujeres inmigrantes ofrece una mayor resistencia frente a la caída de la tasa de empleo que el de los inmigrantes varones. A partir de la recesión, el nivel de ocupación de las mujeres españolas es de todos los grupos el que experimenta pérdidas más moderadas, aunque en su caso un nivel educativo alto no implica un descenso más suave de la tasa de empleo. Por otra parte, un mayor tiempo en el mercado laboral sólo parece ser un factor de protección en el caso de las mujeres españolas.This paper explores the impact of the current financial crisis on employment of female immigrants by conducting empirical analysis based on the Spanish Labour Force Survey, from 2000 until 2010. Results show that female immigrants are less affected by the recession in comparison to male immigrants. At the same time, human capital of female immigrants is more effective against the employment fall in comparison to male immigrants, of which the unemployment rate shows a higher growth. As for Spanish women, employment rates show the smallest drop since the recession, having the same effect on high as well as low educated women. Finally, time in the labour market only has a positive impact on prospects of female natives

Solidarités patronales et formation des interlocks entre les principaux administrateurs du CAC40

National audienceBecause of multiple directorships, the overlaps among the boards of CAC40 companies form a particularly dense network. Focusing on the directors who seat in more than two boards of CAC40 companies, we aim to emphasize the underlying bases of the solidarity, which trigger intercooptations. If the solidarity based upon an education provided by a same elite school, essentially Polytechnique and ENA, highlights a part of these ties, ideological affinities and friendships, measured by common memberships in clubs and liberal thinks tanks, also play a significant role.Avec les cumuls de mandats, les entrecroisements entre les conseils d'administration (en anglais interlocks) des sociétés du CAC40 forment un réseau particulièrement dense. Les intercooptations reflètent des solidarités, dont nous cherchons à élucider quelques uns des fondements, en nous focalisant sur les dirigeants qui cumulent au moins trois sièges dans les organes de gouvernance des sociétés du CAC40. Si les solidarités de corps liées au passage par les mêmes grandes écoles, essentiellement Polytechnique et l'ENA, éclairent une part de ces liens, il apparaît que les affinités idéologiques voire les relations d'amitié, mesurées à partir des coappartenances dans des clubs ou think tanks libéraux, jouent également un rôle

Enzymatic competition: Modeling and verification with timed hybrid petri nets

International audienceThe formalism of hybrid functional petri nets (HFPN) has proved its convenience for simulating biological systems. The drawback of the noticeable expressiveness of HFPN is the difficulty to perform formal verifications of dynamical properties. In this article, we propose a model-checking procedure for timed hybrid petri nets (THPN), a sub-class of HFPN. This procedure is based on the translation of the THPN model and of the studied property into real-time automata. It is applied to model enzymatic competitions existing in amphibian metamorphosis

Self‐assembled quantum dots of InSb grown on InP by atomic layer molecular beam epitaxy: Morphology and strain relaxation

Self-organized InSb dots grown by atomic layer molecular beam epitaxy on InP substrates have been characterized by atomic force and transmission electron microscopy. Measurement of high-energy electron diffraction during the growth indicates a Stransky–Krastanov growth mode beyond the onset of 1.4 InSb monolayer ~ML! deposition. The dots obtained after a total deposition of 5 and 7 ML of InSb present a truncated pyramidal morphology with rectangular base oriented along the ^110& directions, elongated towards the @110# direction with $111$113%/$114$111%A lateral facets in @11 ¯ 0# views, and ~001! flat top surfaces. The mismatch between the dot and the substrate has been accommodated by a network of 90° misfit dislocation at the interface. A corrugation of the InP substrate surrounding the dot has been also observedThis work has been funded by the Spanish CICYT Project MAT95-0966.Peer reviewe