Validation of a food frequency questionnaire. II. Nutrients and biochemical markers

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Tumor growth and oxidant-antioxidant status

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Late Aptian-Albian primitive Radiolitidae (bivalves, hippuritoidea) from Spain and SW France

The late Aptian-Albian radiolitid taxa, Praeradiolites cantabricus (Douvillé) and Praeradiolites ibizanus Astre, from SW France and Spain, are transferred to Eoradiolites. Eoradiolites jumillensis nov. sp. is described from southern Spain, while the so-called “Sphaerulites cantabricus” sensu Toucas (1907) is moved to Praeradiolites and may be of Late Cretaceous age. The Eoradiolites cantabricus group of species is mainly Clansayesian-early Albian in age and possesses an advanced evolutionary status, mainly regarding shell size and cellular structure. Praeradiolites may have been derived from Eoradiolites jumillensis nov. sp. through paedomorphosis while Eoradiolites cantabricus may have been the source for Sphaerulites. Our study shows that the names Sphaerulites and Praeradiolites cannot be applied to pre-Cenomanian Radiolitidae and that Eoradiolites was the foremost genus in Late Aptian-Albian times in terms of species biodiversity. The Eoradiolites cantabricus group is restricted to the northwestern Mediterranean Tethyan margin.Our field investigation in southern Spain have been founded by the Ministerio de Ciencia y Tecnologia of Spain, number of project: REN2001-1067/GLO (Aplicacion de tecnicas del analisis de cuencas sedimentarias en el uso no destructivo del patrimonio natural en al Prebetico oriental. El altiplano de Jumilla-Yecla). At the Université de Provence, we have benefited from the technical assistance of A. Arnoux. Fruitful discussions with L. Villiers (Université de Provence, Marseille)Peer reviewe

An athermal measurement technique for long time constants traps characterization in GaN HEMT transistors

International audienceGaN High Electron Mobility Transistors (HEMTs) are very promising for high power switching and radiofrequency operation. However, the lack of reliability feedback is one of its major drawbacks. Trapping effect especially is one of the main performance limitations of such components. Many measurement techniques exist for trapping effects characterization, especially for short time constant traps (s to several ms). However for longer time constants, self-heating may distort the measurements. This paper presents an electrical and athermal transient measurement method which has been developed to study the trapping and detrapping time constants of such components. It allows the extraction of slow transients without self-heating problems and is usable in long term electrical stress experiments. A simulation of this method with a simplified component’s model and the measurements results are presented. With this technique, we investigated especially the long time constants (τ>20 ms) over a range of temperature from 10°C to 105°C. We observed three thermally activated trap signatures on GaN devices with our method