La réception de Dostoïevski en France au début du XXIème siècle

La réception de Dostoïevski en France au début du XXIème siècl

Stabilising a nulling interferometer using optical path difference dithering

Context. Nulling interferometry has been suggested as the underlying principle for the Darwin and TPF-I exoplanet research missions. Aims. There are constraints both on the mean value of the nulling ratio, and on its stability. Instrument instability noise is most detrimental to the stability of the nulling performance. Methods. We applied a modified version of the classical dithering technique to the optical path difference in the scientific beam. Results. Using only this method, we repeatedly stabilised the dark fringe for several hours. This method alone sufficed to remove the 1/ f component of the noise in our setup for periods of 10 minutes, typically. These results indicate that performance stability may be maintained throughout the long-duration data acquisitions typical of exoplanet spectroscopy. Conclusions. We suggest that further study of possible stabilisation strategies should be an integral part of Darwin/TPF-I research and developmen

Gene organization, evolution and expression of the microtubule-associated protein ASAP (MAP9)

International audienceBackground : ASAP is a newly characterized microtubule-associated protein (MAP) essential for propercell-cycling. We have previously shown that expression deregulation of human ASAP results in profounddefects in mitotic spindle formation and mitotic progression leading to aneuploidy, cytokinesis defects and/or cell death. In the present work we analyze the structure and evolution of the ASAP gene, as well as thedomain composition of the encoded protein. Mouse and Xenopus cDNAs were cloned, the tissueexpression characterized and the overexpression profile analyzed. Results : Bona fide ASAP orthologs are found in vertebrates with more distantly related potentialorthologs in invertebrates. This single-copy gene is conserved in mammals where it maps to syntenicchromosomal regions, but is also clearly identified in bird, fish and frog. The human gene is stronglyexpressed in brain and testis as a 2.6 Kb transcript encoding a ~110 KDa protein. The protein containsMAP, MIT-like and THY domains in the C-terminal part indicative of microtubule interaction, while the N-terminal part is more divergent. ASAP is composed of ~42% alpha helical structures, and two main coiled-coil regions have been identified. Different sequence features may suggest a role in DNA damage response. As with human ASAP, the mouse and Xenopus proteins localize to the microtubule network in interphaseand to the mitotic spindle during mitosis. Overexpression of the mouse protein induces mitotic defectssimilar to those observed in human. In situ hybridization in testis localized ASAP to the germ cells, whereasin culture neurons ASAP localized to the cell body and growing neurites. Conclusion : The conservation of ASAP indicated in our results reflects an essential function invertebrates. We have cloned the ASAP orthologs in mouse and Xenopus, two valuable models to studythe function of ASAP. Tissue expression of ASAP revealed a high expression in brain and testis, two tissuesrich in microtubules. ASAP associates to the mitotic spindle and cytoplasmic microtubules, and representsa key factor of mitosis with possible involvement in other cell cycle processes. It may have a role inspermatogenesis and also represents a potential new target for antitumoral drugs. Possible involvement inneuron dynamics also highlights ASAP as a candidate target in neurodegenerative disease

Archéologie et hydrogéologie

Le programme sur la gestion de l’eau dans la ville antique de Solonte (Santa Flavia, PA) a été lancé dans le cadre du réseau HYDRΩMED (http://hydromed.hypotheses.org/), dirigé par Sophie Bouffier (Centre Camille Jullian, Aix-Marseille Université) et financé par la fondation A*Midex. Interdisciplinaire, ce projet a pour finalité une meilleure compréhension des différentes modalités d’adaptation des populations antiques à l’environnement méditerranéen en mettant l’accent sur les ressources en e..

South Luberon massif travertines : long postglacial sedimentary sequences

Les séquences travertineuses du piémont méridional du Grand Luberon, en cours d’étude, délivrent des données nouvelles sur plus de 12000 ans d’évolution du paysage luberonnais et dans la compréhension des relations complexes entre l’Homme et le milieu « naturel ». L’extrême sensibilité de ces systèmes carbonatés, par rapport aux conditions environnementales locales et extra-régionales (climat, occupations humaines), en fait des enregistreurs privilégiés de haute résolution permettant de saisir au mieux les changements de dynamique morphogéniques ayant cours au postglaciaire et instaure les bases de nouvelles pistes de réflexion.New important Holocene data are displayed from the travertine sequences of the Grand Luberon meridional. These data give new information on landscape evolution of the Luberon area and on the complex relations between Man and his natural environment. These carbonates are very sensitive on environmental climatic and anthropic variations at local and regional scales. Therefore, they provide high resolution record of post-glacial morphogenic dynamics which setlle the basis for new hypotheses

Archéologie et hydrogéologieDe nouvelles données concernant la gestion de l’eau dans la cité deSolonte (nord-ouest Sicile, Italie)

International audienc

Tests of achromatic phase shifters performed on the SYNAPSE test bench: a progress report

The achromatic phase shifter (APS) is a component of the Bracewell nulling interferometer studied in preparation for future space missions (viz. Darwin/TPF-I) focusing on spectroscopic study of Earth-like exo-planets. Several possible designs of such an optical subsystem exist. Four approaches were selected for further study. Thales Alenia Space developed a dielectric prism APS. A focus crossing APS prototype was developed by the OCA, Nice, France. A field reversal APS prototype was prepared by the MPIA in Heidelberg, Germany. Centre Spatial de Li\`ege develops a concept based on Fresnel's rhombs. This paper presents a progress report on the current work aiming at evaluating these prototypes on the SYNAPSE test bench at the Institut d'Astrophysique Spatiale in Orsay, France

Substrate-controlled allotropic phases and growth orientation of TiO2 epitaxial thin films

International audienceTiO2 thin films were grown by pulsed laser deposition on a wide variety of oxide single-crystal substrates and characterized in detail by four-circle X-ray diffraction. Films grown at 873 K on (100)-oriented SrTiO3 and LaAlO3 were (001)-oriented anatase, while on (100) MgO they were (100)-oriented. On (110) SrTiO3 and MgO, (102) anatase was observed. On M-plane and R-plane sapphire, (001)- and (101)-oriented rutile films were obtained, respectively. On C-plane sapphire, the coexistence of (001) anatase, (112) anatase and (100) rutile was found; increasing the deposition temperature tended to increase the rutile proportion. Similarly, films grown at 973 K on (100) and (110) MgO showed the emergence, besides anatase, of (110) rutile. All these films were epitaxically grown, as shown by ' scans and/or pole figures, and the various observed orientations were explained on the basis of misfit considerations and interface arrangement

Sr1-xBaxSnO3 system applied in the photocatalytic discoloration of an azo-dye

International audienceSemiconductor materials have received substantial attention as photocatalysts for controlling water pollution. Among these materials, perovskite-structured SrSnO3 is a promising candidate for this application, whereas BaSnO3 exhibits very low activity. In the present work, Sr1−xBaxSnO3 (x = 0, 0.25, 0.50, 0.75 and 1) was synthesized by solid-state reaction and was applied in the photocatalytic discoloration of the organic dye Remazol Golden Yellow. The perovskite structure was obtained for all compositions of the solid solutions with both Sr2+ and Ba2+ present in the lattice. A remarkable change in the short-range symmetry was observed as the amount of Ba2+ increased, and this change led to a decrease in the band gap of the material. Although the BaSnO3 was not active toward water photolysis, the discoloration induced by this perovskite was twice that induced by SrSnO3. The two materials appear to feature different mechanisms of photodegradation: the direct mechanism prevails in the case of BaSnO3, whereas the indirect mechanism appears to play a key role in the case of SrSnO3

Helical bunching and symmetry lowering inducing multiferroicity in Fe langasites

International audienceThe chiral Fe-based langasites represent model systems of triangle-based frustrated magnets with a strong potential for multiferroicity. We report neutron scattering measurements for the multichiral Ba3MFe3Si2O14 (M = Nb, Ta) langasites revealing new important features of the magnetic order of these systems: the bunching of the helical modulation along the c-axis and the in-plane distortion of the 120° Fe-spin arrangement. We discuss these subtle features in terms of the microscopic spin Hamiltonian, and provide the link to the magnetically-induced electric polarization observed in these systems. Thus, our findings put the multiferroicity of this attractive family of materials on solid ground