The use of quantitative mineralogy linked to palynological studies in palaeoenvironmental reconstruction : the case study of the "Lagoa Campestre" lake, Salitre, Minas Gerais, Brazil

La comparaison des contenus minéraux déterminés par spectroscopie IRTF et polliniques de sédiments lacustres de la région de Salitre (Brésil) montre que les variations des teneurs en phases minérales répercutent des changements régionaux ou locaux de l'environnement. Une évolution inverse entre couvert forestier et charge détritique des sédiments est observée pendant la phase lacustre pleistocène. La méthode utilisée permet la détection d'un hiatus sédimentaire marqué par un changement brutal du contenu minéral, ainsi que l'évaluation du caractère abrupt de certains changements du couvert végétal qui, en l'absence de datation, pourraient être confondus avec un hiatus sédimentaire. (Résumé d'auteur

An extrasolar planetary system with three Neptune-mass planets

Over the past two years, the search for low-mass extrasolar planets has led to the detection of seven so-called 'hot Neptunes' or 'super-Earths' around Sun-like stars. These planets have masses 5-20 times larger than the Earth and are mainly found on close-in orbits with periods of 2-15 days. Here we report a system of three Neptune-mass planets with periods of 8.67, 31.6 and 197 days, orbiting the nearby star HD 69830. This star was already known to show an infrared excess possibly caused by an asteroid belt within 1 AU (the Sun-Earth distance). Simulations show that the system is in a dynamically stable configuration. Theoretical calculations favour a mainly rocky composition for both inner planets, while the outer planet probably has a significant gaseous envelope surrounding its rocky/icy core; the outer planet orbits within the habitable zone of this star.Comment: 17 pages, 3 figures, preprint of the paper published in Nature on May 18, 200

Multifocal Ectopic Purkinje-Related Premature Contractions: A New SCN5A-Related Cardiac Channelopathy.: MEPPC: a new SCN5A-related cardiac channelopathy

International audienceOBJECTIVES: The aim of this study was to describe a new familial cardiac phenotype and to elucidate the electrophysiological mechanism responsible for the disease. BACKGROUND: Mutations in several genes encoding ion channels, especially SCN5A, have emerged as the basis for a variety of inherited cardiac arrhythmias. METHODS: Three unrelated families comprising 21 individuals affected by multifocal ectopic Purkinje-related premature contractions (MEPPC) characterized by narrow junctional and rare sinus beats competing with numerous premature ventricular contractions with right and/or left bundle branch block patterns were identified. RESULTS: Dilated cardiomyopathy was identified in 6 patients, atrial arrhythmias were detected in 9 patients, and sudden death was reported in 5 individuals. Invasive electrophysiological studies demonstrated that premature ventricular complexes originated from the Purkinje tissue. Hydroquinidine treatment dramatically decreased the number of premature ventricular complexes. It normalized the contractile function in 2 patients. All the affected subjects carried the c.665G>A transition in the SCN5A gene. Patch-clamp studies of resulting p.Arg222Gln (R222Q) Nav1.5 revealed a net gain of function of the sodium channel, leading, in silico, to incomplete repolarization in Purkinje cells responsible for premature ventricular action potentials. In vitro and in silico studies recapitulated the normalization of the ventricular action potentials in the presence of quinidine. CONCLUSIONS: A new SCN5A-related cardiac syndrome, MEPPC, was identified. The SCN5A mutation leads to a gain of function of the sodium channel responsible for hyperexcitability of the fascicular-Purkinje system. The MEPPC syndrome is responsive to hydroquinidine

Future Exoplanet Research: Science Questions and How to Address Them

Started approximately in the late 1980s, exoplanetology has up to now unveiled the main gross bulk characteristics of planets and planetary systems. In the future it will benefit from more and more large telescopes and advanced space missions. These instruments will dramatically improve their performance in terms of photometric precision, detection speed, multipixel imaging, high-resolution spectroscopy, allowing to go much deeper in the knowledge of planets. Here we outline some science questions which should go beyond these standard improvements and how to address them. Our prejudice is that one is never too speculative: experience shows that the speculative predictions initially not accepted by the community have been confirmed several years later (like spectrophotometry of transits or circumbinary planets).Comment: Invited review, accepte

Origine métamorphique des grenats des volcanites acides d'âge viséen supérieur dans le nord-est du Massif central français

Garnets of acid volcanics (called « tufs anthracifères ») from the upper Visean, North-East of the French Central Massif, which occur either in metamorphic enclaves or in free xenocrysts, are of metamorphic origin. This result is based upon a comparison of these garnets with those of the neighbouring metamorphic basement of the Forez area. The chemical composition of garnets shows that they first belonged to sillimanite-cordierite bearing rocks. Original metamorphic zoning is preserved in most of the mineral. At the rim, the evolution of the almandine/pyrope ratio in garnets from volcanics is the opposite of that in garnets from the metamorphic basement. This is a consequence of the ultimate magmatic stage of these minerals, during which a plagioclase-biotite reaction rim appears around free garnets. These results suggest the need for reexamining the magmatic origin proposed by several authors for garnets of intermediate and acid volcanics occurring in different areas, these garnets having zoning and chemical characteristics similar to those of the « tufs anthracifères » garnets. Finally, this study of garnets supports the assumption of the origin of acid magmatism from the upper Visean by anatectic melting of continental crust.Les grenats des volcanites acides d'âge Viséen supérieur du Nord-Est du Massif Central français (tufs anthracifères), qu'ils soient libres ou contenus dans des enclaves métamorphiques, ont tous une origine métamorphique. Ce résultat s'appuie sur la comparaison de ces grenats avec ceux du socle métamorphique voisin du Forez. La composition chimique des grenats atteste de leur appartenance première à des roches à sillimanite˗cordiérite. La zonation d'origine, de type métamorphique, est conservée dans la plus grande partie du minéral. En bordure, l'évolution du rapport almandin/pyrope dans les grenats des volcanites est l'inverse de celle des grenats du socle. Ceci témoigne de l'étape magmatique finale de ces minéraux, qui se traduit en outre pour les grenats libres par l'apparition d'une bordure de réaction à plagioclase + biotite. Ces résultats remettent en question l'origine magmatique proposée dans la littérature pour des grenats de volcanites acides et intermédiaires de diverses provinces, leurs caractères chimiques et de zonation étant identiques à ceux des tufs anthracifères. Enfin, l'étude des grenats vient à l'appui de l'hypothèse de l'origine du magmatisme acide du Viséen supérieur par fusion anatectique de croûte continentale.Bertaux Jacques. Origine métamorphique des grenats des volcanites acides d'âge viséen supérieur dans le nord-est du Massif central français. In: Bulletin de Minéralogie, volume 105, 2, 1982. pp. 212-222

Guillou (sous la dir. de André). Les outils dans les Balkans du Moyen Age à nos jours. I. Nomenclature et formes. II. Planches, par Giustina Ostuni, s.d. [1986]. (Documents et recherches sur le monde byzantin néohellénique et balkanique, XIV et XV)

Bertaux J.J. Guillou (sous la dir. de André). Les outils dans les Balkans du Moyen Age à nos jours. I. Nomenclature et formes. II. Planches, par Giustina Ostuni, s.d. [1986]. (Documents et recherches sur le monde byzantin néohellénique et balkanique, XIV et XV). In: Archéologie médiévale, tome 19, 1989. pp. 404-405

À propos des saints en Normandie : érémitisme, iconographie, culte populaire : Les religieux et la mer. Actes du colloque de Lille-Baie de Somme, 21-23 septembre 2001

Bertaux Jean-Jacques. À propos des saints en Normandie : érémitisme, iconographie, culte populaire : Les religieux et la mer. Actes du colloque de Lille-Baie de Somme, 21-23 septembre 2001. In: Annales de Normandie, 55ᵉ année, n°4, 2005. pp. 377-381

Pour l'histoire de l'enseignement

Bertaux Jean-Jacques. Pour l'histoire de l'enseignement. In: Annales de Normandie, 25ᵉ année, n°2, 1975. p. 134