Philippe JEAN-PIERRE

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• Type de publi. : Ouvrage (y compris édition critique et traduction)
• Date de publi. : 01/01/2007
• Auteurs : Philippe Martin
• Organismes : LAboratoire de Recherche Historique Rhône-Alpes - UMR5190

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2007
• Auteurs : Laurent JordaPhilippe LamyG. FauryHorst Uwe KellerStubbe F. HviidMichael KüppersDetlef KoschnyJean LecacheuxPedro J. GutierrezLuisa M. Lara
• Organismes : Laboratoire d'Astrophysique de Marseille Laboratoire d'Astrophysique de Marseille Laboratoire d'Astrophysique de Marseille Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research Research and Scientific Support Department, ESA-ESTEC Observatoire de Paris Laboratoire d'études spatiales et d'instrumentation en astrophysique Pôle Planétologie du LESIA Instituto de Astrofísica de Andalucía = Institute of Astrophysics of Andalusia Instituto de Astrofísica de Andalucía = Institute of Astrophysics of Andalusia
• Publié dans Icarus le 30/10/2020

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Résumé : We present an analysis of the observations of the Deep Impact event performed by the OSIRIS narrow angle camera aboard the Rosetta spacecraft over two weeks, in an effort to characterize the cometary dust grains ejected from the nucleus of Comet 9P/Tempel 1. We adopt a Monte Carlo approach to generate calibrated synthetic images, and a linear combination of them is fitted to the calibrated images so as to determine the physical parameters of the dust cloud. Our model considers spherical olivine particles with a density of 3780 kg m ^-3. It incorporates constraints on the direction of the cone of emission coming from additional images obtained at Pic du Midi observatory, and constraints on the dust terminal velocities coming from the physics of the impact. We find that the slope of the differential dust size distribution of grains with radii 0.008) is 3.1±0.3, a value typical of cometary dust tails. This shows that there is no evidence in our data for an enhancement in sub-micron particles in the ejecta compared to the typical dust distribution of active comets. We estimate the mass of particles with radii 0.14) to be 1.5±0.2×10 kg. These particles represent more than 80% of the cross-section of the observed dust cloud. The mass carried by larger particles depends whether the gas significantly increases the kinetic energy of the grains in the inner coma; it lies in the range 1-14×10 kg for particles with radii 0.002). We obtain the distribution of terminal velocities reached by the dust after the dust-gas interaction which is very well constrained between 10 and 600 m s ^-1. It is characterized by Gaussian with a maximum at about 190 m s ^-1 and a width at half maximum of 150 m s ^-1.

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• Type de publi. : Chapître d'ouvrage
• Date de publi. : 01/01/2007
• Auteurs : Philippe Martin
• Organismes : LAboratoire de Recherche Historique Rhône-Alpes - UMR5190

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• Type de publi. : Autre publication
• Date de publi. : 01/01/2007
• Auteurs : Philippe Martin
• Organismes : LAboratoire de Recherche Historique Rhône-Alpes - UMR5190

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2007
• Auteurs : Christophe VignyJean-Bernard de ChabalierJean-Claude RueggPhilippe HuchonKurt L. FeiglRodolphe CattinLaike AsfawKhaled Kanbari
• Organismes : Laboratoire de géologie de l'ENS Institut de Physique du Globe de Paris Institut de Physique du Globe de Paris Laboratoire de tectonique Department of Geology and Geophysics [Madison] Laboratoire de géologie de l'ENS Geophysical Observatory, Space Science and Asreonomy [Addis Ababa] Department of Geosciences
• Publié dans Journal of Geophysical Research : Solid Earth le 27/10/2020

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Résumé : Since most of Tadjoura-Asal rift system sits on dry land in the Afar depression near the triple junction between the Arabia, Somalia, and Nubia plates, it is an ideal natural laboratory for studying rifting processes. We analyze these processes in light of a time series of geodetic measurements from 1978 through. A network of about 30 GPS sites covers the Republic of Djibouti. Additional points were also measured in Yemen and Ethiopia. Stations lying in the Danakil block have almost the same velocity as Arabian plate, indicating that opening near the southern tip of the Red Sea is almost totally accommodated in the Afar depression. Inside Djibouti, the Asal-Ghoubbet rift system accommodates 16 ± 1 mm/yr of opening perpendicular to the rift axis and exhibits a pronounced asymmetry with essentially null deformation on its southwestern side and significant deformation on its northeastern side. This rate, slightly higher than the large-scale Arabia-Somalia motion (13 ± 1 mm/yr), suggests transient variations associated with relaxation processes following the Asal-Ghoubbet seismovolcanic sequence of 1978. Inside the rift, the deformation pattern exhibits a clear two-dimensional pattern. Along the rift axis, the rate decreases to the northwest, suggesting propagation in the same direction. Perpendicular to the rift axis, the focus of the opening is clearly shifted to the northeast, relative to the topographic rift axis, in the ''Petit Rift,'' a rift-in-rift structure, containing most of the active faults and the seismicity. Vertical motions, measured by differential leveling, show the same asymmetric pattern with a bulge of the northeastern shoulder. Although the inner floor of the rift is subsiding with respect to the shoulders, all sites within the rift system show uplift at rates varying from 0 to 10 mm/yr with respect to a far-field reference outside the rift.

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Fichiers liés : jgrb4488.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2007
• Auteurs : Emilie BagnarolJean PopoviciNicole AlloisioJoelle MarechalPierre PujicPhilippe NormandMaria P. Fernandez
• Organismes : Laboratoire d'Ecologie Microbienne - UMR 5557 Laboratoire d'Ecologie Microbienne - UMR 5557 Laboratoire d'Ecologie Microbienne - UMR 5557 Laboratoire d'Ecologie Microbienne - UMR 5557 Laboratoire d'Ecologie Microbienne - UMR 5557 Laboratoire d'Ecologie Microbienne - UMR 5557 Laboratoire d'Ecologie Microbienne - UMR 5557
• Publié dans Physiologia Plantarum le 31/10/2020

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Résumé : Two-dimensional gel electrophoresis was used to identify differentially displayed proteins expressed during the early symbiotic interactions between the bacterium Frankia and actinorhizal plants. Myricaceae, the most primitive actinorhizal family, was used as an experimental model to study specificity mechanisms because it includes species with either narrowor large specificity. Seed phenolic extracts from two Myricaceae species, Myrica gale, a narrow specificity host and Morella cerifera considered as a promiscuous host, were used to induce three Frankia strains ACN14a, M16467 and Ea112. The global protein pattern was altered by exposure to the plant extracts. The addition of 30 mg l21 of seed phenolic extracts provoked the inhibition of many protein biosynthesis whereas 1 and 10 mg l21 induced a global reprogramming of Frankia protein pattern. Changes in intensity of 115 spots in response to seed extracts were detected and analyzed by matrix-assisted laser desorption/ ionization time of flight mass spectrometry. Fifty proteins were efficiently identified with Frankia protein data banks deduced from the sequences of Frankia strains ACN14a and EaN1pec genomes. Differential proteins were involved in different metabolism pathways such as glycolysis and gluconeogenesis, transcription, fatty acids, carbohydrates, coenzymes and purines metabolisms. Chaperones biosynthesis and iron transport regulation, essential for nitrogen fixation, seem to be strain dependant. Several proteins possibly involved in the regulation of nodulation were also differentially expressed. The most obvious response was the upregulation of oxidative stress proteins such as FeSOD and Tellurium resistance proteins, suggesting a reorganization of Frankia metabolism to protect against host plant defense.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2007
• Auteurs : Marie LorinRaphaël DelépéeJean-Claude MaurizotJean-Paul RibetPhilippe Morin
• Organismes : Institut de Chimie Organique et Analytique Institut de Chimie Organique et Analytique Centre de biophysique moléculaire Institut de Recherche Pierre Fabre Institut de Chimie Organique et Analytique
• Publié dans Chirality le 29/10/2020

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Résumé : The quality control of chiral drugs requires the determination of their enantiomeric purity. Nowadays, circular dichroism (CD) spectroscopy is gaining increasing importance in pharmaceutical analysis because of the commercially available CD detector in liquid chromatography. The separation of the two enantiomers of a basic drug (efaroxan) was achieved by high performance liquid chromatography using an amylose-derivated column with both UV and CD detections. A baseline-resolved separation (resolution: 5) was obtained after optimization of the mobile phase composition with hexane-ethanol-diethylamine (90:10:0.05; v/v/v). The use of a commercial low-pass electronic noise filter of the CD signal has improved the signal-to-noise ratio by a factor twelve and allowed the quantitation of each enantiomer in the 1.25-300 g ml-1 concentration range. The CD linear calibration curve, expressed in terms of stereoisomer height ratio versus concentration ratio, was plotted over the 0.4-6% range. A correlation coefficient greater than 0.999 was obtained by least-squares regression and the limit of detection for the distomer/eutomer ratio was estimated at 0.14%. Although the method validation showed good repeatability on the retention times (RSD < 0.9%), on the peak height ratios (RSD < 8.7%) of each enantiomer only up to 99.2% enantiomeric purity was achieved.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2007
• Auteurs : Jean-Pierre ChaomleffelGérard DalmazPhilippe Vergne
• Organismes : Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne]
• Publié dans Tribology International le 25/10/2020

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2007
• Auteurs : Marie-Estelle GouzeJoëlle LaffittePhilippe PintonGeneviève DedieuxAnne GalinierJean-Paul ThouvenotNicolas LoiseauIsabelle P. OswaldPierre Galtier
• Organismes :
• Publié dans Veterinary Research le 26/10/2020

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Résumé : Nivalenol (NIV) is a toxic Fusarium secondary trichothecene metabolite occurring naturally in cereal grains. In order to evaluate the no observed adverse effect level (NOAEL), we tested the effects of a large array of oral doses of this toxin for responses on plasma biochemistry, the immune system and hepatic drug metabolism in mice. C57Bl6 mice received oral doses of toxin (0.014, 0.071, 0.355, 1.774 or 8.87 mg/kg bw) 3 days a week for 4 weeks. Only the highest dose of NIV induced an increase in plasma phosphate, decreases in plasma urea and immunoglobulin M and additional changes like increases in plasma alkaline phosphatase and immunoglobulin G. Interleukin 4 production was increased in cultured murine splenocytes. Regarding liver drug metabolising enzymes, the only glutathione transferase activity accepting 1-chloro-2,4-dinitro-benzene as substrate was transiently increased in mice receiving low doses (0.071 and 0.355 mg/kg bw) of NIV. Regarding the cytochrome P450 monooxygenases, no significant change was observed in ethoxyresorufin $O$-deethylase activity whereas both methoxyresorufin and pentoxyresorufin $O$-dealkylase activities were decreased by 38-45% for the highest dose (8.87 mg/kg bw) of NIV. However, when analysed by Western blot analysis, the protein expression of mouse P450 1a, 2b, 2c, 3a and 4a subfamilies was unchanged in animals receiving NIV. In conclusion, the NOAEL of this toxin in our study was 1.774 mg/kg bw, corresponding to an exposure to 5 ppm contaminated food. Indeed hepatotoxicity appears in the only mice treated with a five fold higher oral dose of 8.87 mg/kg bw of NIV. Such exposure levels appear to be by far higher than the maximal natural occurrence measured in European cereals, known to range from 0.34 to 1.86 ppm.

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Fichiers liés : hal-00902889.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2007
• Auteurs : Adeline PezierAdrien AcquistapaceMichel M. RenouJean-Pierre J.-P. RosparsPhilippe Lucas
• Organismes : Physiologie de l'Insecte : Signalisation et Communication Physiologie de l'Insecte : Signalisation et Communication Physiologie de l'Insecte : Signalisation et Communication Physiologie de l'Insecte : Signalisation et Communication Physiologie de l'Insecte : Signalisation et Communication
• Publié dans Chemical Senses le 29/10/2020

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Résumé : The role of Ca2+ in insect olfactory transduction was studied in the moth Spodoptera littoralis. Single sensillum recordings were made to investigate in vivo the role of sensillar Ca2+ on the electrophysiological properties of sex pheromone responsive olfactory receptor neurons (ORNs). Lowering the sensillar Ca2+ concentration to 2 x 10(-8) M increased ORN spontaneous firing activity and induced long bursts of action potentials (APs) superimposed on spontaneous negative deflections of the transepithelial potential. We inferred that Ca2+ stabilizes the membrane potential of ORNs, keeping the spontaneous firing activity at a low and regular level. Neither the amplitude and kinetics of the rising phase of sensillar potentials (SPs) recorded in response to pheromone stimuli nor the AP generation during stimulation depended on the extracellular Ca2+ concentration. Thus, extracellular Ca2+ is not absolutely necessary for ORN response. Partial inhibition of responses with a calmodulin antagonist, W-7, also indicates that intracellular Ca2+ contributes to the ORN response and suggests that Ca2+ release from internal stores is involved. In 2 x 10(-8) M Ca2+, the repolarization of the SP was delayed when compared with higher Ca2+ concentrations. Therefore, in contrast to depolarization, ORN repolarization depends on extracellular Ca2+. Ca2+-gated K+ channels identified from cultured ORNs with whole-cell recordings are good candidates to mediate ORN repolarization.

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