Philippe JEAN-PIERRE

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : Pierre MahéNobuhisa UedaTatsuya AkutsuJean-Luc PerretJean-Philippe Vert
• Organismes : Centre de Bioinformatique Centre de Bioinformatique
• Publié dans Journal of Chemical Information and Modeling le 27/10/2020

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Résumé : The support vector machine algorithm together with graph kernel functions has recently been introduced to model structure-activity relationships (SAR) of molecules from their 2D structure, without the need for explicit molecular descriptor computation. We propose two extensions to this approach with the double goal to reduce the computational burden associated with the model and to enhance its predictive accuracy: description of the molecules by a Morgan index process and definition of a second-order Markov model for random walks on 2D structures. Experiments on two mutagenicity data sets validate the proposed extensions, making this approach a possible complementary alternative to other modeling strategies.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : Jean-Pierre MothetLoredano PollegioniGilles OuanounouMagalie MartineauPhilippe FossierGérard Baux
• Organismes : Laboratoire de neurobiologie cellulaire et moléculaire Department of Biotechnology and Molecular Sciences Laboratoire de neurobiologie cellulaire et moléculaire Laboratoire de neurobiologie cellulaire et moléculaire Laboratoire de neurobiologie cellulaire et moléculaire Laboratoire de neurobiologie cellulaire et moléculaire
• Publié dans Proceedings of the National Academy of Sciences of the United States of America le 31/10/2020

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Résumé : The gliotransmitter D-serine is released upon (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate and metabotropic glutamate receptor stimulation, but the mechanisms involved are unknown. Here, by using a highly sensitive bioassay to continuously monitor extracellular D-serine levels, we have investigated the pathways used in its release. We reveal that D-serine release is inhibited by removal of extracellular calcium and augmented by increasing extracellular calcium or after treatment with the Ca(2+) ionophore A23187. Furthermore, release of the amino acid is considerably reduced after depletion of thapsigargin-sensitive intracellular Ca(2+) stores or chelation of intracellular Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetate-acetoxymethyl ester. Interestingly, D-serine release also was markedly reduced by concanamycin A, a vacuolar-type H(+)-ATPase inhibitor, indicating a role for the vesicular proton gradient in the transmitter storage/release. In addition, agonist-evoked D-serine release was sensitive to tetanus neurotoxin. Finally, immunocytochemical and sucrose density gradient analysis revealed that a large fraction of D-serine colocalized with synaptobrevin/VAMP2, suggesting that it is stored in VAMP2-bearing vesicles. In summary, our study reveals the cellular mechanisms subserving D-serine release and highlights the importance of the glial cell exocytotic pathway in influencing CNS levels of extracellular D-serine.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 01/01/2005
• Auteurs : Lise Crevier-BuchmanMieke MoermanJean-Pierre MartensVirginie WoisardPhilippe Dejonckere
• Organismes : LPP - Laboratoire de Phonétique et Phonologie - UMR 7018 Hôpital Européen Georges Pompidou [APHP]

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : David BessonOlivier ParizeJean-Loup RubinoJean-Pierre AguilarMarie-Pierre AubryBernard BeaudoinWilliam A. BerggrenGeorges ClauzonPhilippe CrumeyrolleYann DexcotéNicolas FietSilvia IaccarinoGonzalo Jiménez-MorenoCécile Laporte-GalaaJacques MichauxKatharina von SalisJean-Pierre SucJean-Yves ReynaudRoland Wernli
• Organismes : Centre de Géotechnique et d'exploitation du sous sol Centre de Géotechnique et d'exploitation du sous sol Total, CST JF–TG/ISS Institut des Sciences de l'Evolution de Montpellier Centre de Géotechnique et d'exploitation du sous sol Total, CST JF–TG/ISS Centre de Géotechnique et d'exploitation du sous sol PaleoEnvironnements et PaleobioSphere Total, CST JF–TG/ISS Institut des Sciences de l'Evolution de Montpellier PaleoEnvironnements et PaleobioSphere
• Publié dans Comptes Rendus. Géoscience le 29/07/2021

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Résumé : An integrated study combining facies analysis, multiple group biostratigraphy, identification of depositional sequences and mapping has been conducted on the Miocene Molasse Basin of the external Alps (southeastern France). The filling of the basin is described as resulting from a succession of fluvial incisions subsequently filled during marine transgressions. The major incision is dated as Latest Burdigalian and the major transgression as Langhian. This revised interpretation of the Miocene physiographic evolution of the Molasse Basin implies a re-examination of previous stratigraphic correlations within the basin

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : Ivan FaveroGuillaume CassaboisC. VoisinC. DelalandeP. RoussignolR. FerreiraC. CouteauJean-Philippe PoizatJm Gerard
• Organismes : Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire de Spectrométrie Physique Laboratoire de Spectrométrie Physique Nanophysique et Semiconducteurs
• Publié dans Physical Review B: Condensed Matter and Materials Physics (1998-2015) le 02/11/2020

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Résumé : Exciton spin relaxation is investigated in single epitaxially grown semiconductor quantum dots in order to test the expected spin relaxation quenching in this system. We study the polarization anisotropy of the photoluminescence signal emitted by isolated quantum dots under steady-state or pulsed nonresonant excitation. We find that the longitudinal exciton spin relaxation time is strikingly short (<= 100 ps) even at low temperature. This result breaks down the picture of a frozen exciton spin in quantum dots.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 01/01/2005
• Auteurs : Stéphane HaïkDamien GalanaudBaptiste FaucheuxN. PrivatI. Laffont-ProustMarius George LinguraruNicholas AyacheJ.J. HauwDidier DormontJean-Philippe Brandel
• Organismes : Laboratoire de Neuropathologie Raymond Escourolle [CHU Pitié-Salpétriêre] Centre de résonance magnétique biologique et médicale CHU Pitié-Salpêtrière [AP-HP] Medical imaging and robotics Medical imaging and robotics Analysis and Simulation of Biomedical Images CHU Pitié-Salpêtrière [AP-HP] Neurosciences cognitives et imagerie cérébrale Laboratoire d'Imagerie Fonctionnelle Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière Neuroépidémiologie

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Résumé : Recently, several reports underlined the usefulness of brain MRI for the diagnosis of Creutzfeldt-Jakob dis ease. FLAIR sequence and diffusion-weighted imaging (DWI) are considered as high sensitive sequences to detect signal alteration of the cortex and the deep grey matter. Recent advances in therapeutic approach of patients with prion diseases have emphasized the need for earlier diagnostic markers that would authorize the onset of treatment before massive and irreversible lesions of the brain have occurred. Consequently, we designed a radio -clinical study using a multimodality MRI standardized procedure that aimed to estimate differential sensitivity of FLAIR, DWI and MR spectroscopy for the diagnosis of human TSE. Here we report a case of familial fatal insomnia with the D178N-129M mutation. FLAIR and diffusion-weighted sequences were normal in the whole brain notably in both thalami. However, spectroscopic study showed a striking increase of the peak of myo-inositol (mI) and of the mI/NAA ratio in the thalamus when compared to the other studied brain regions of the patient (frontal isocortex, lenticular nucleus and cerebellar vermis) and to the thalami of control cases (n = 10). This metabolite pattern is indicating of gliosis. Because the MRI study was performed only two days before death, we were able to strictly correlate the spectroscopic data with the neuropathological lesions (including the severity of astrogliosis and microglial activation) observed in the thalamus. From this observation, we can conclude that 1) MR spectroscopy can detect prion-related lesions even when other sequences appear normal 2) spectroscopic metabolite pattern well correlates with the neuropathological one.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : Philippe DrobinskiSophie BastinV. GuenardJean-Luc CacciaAlain DabasP. DelvilleAlain ProtatOlivier ReitebuchC. Werner
• Organismes : Service d'aéronomie Service d'aéronomie Laboratoire de sondages électromagnétiques de l'environnement terrestre Laboratoire de sondages électromagnétiques de l'environnement terrestre Centre national de recherches météorologiques Division technique INSU/SDU Centre d'étude des environnements terrestre et planétaires
• Publié dans Quarterly Journal of the Royal Meteorological Society le 27/10/2020

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Résumé : The paper examines the three-dimensional structure and dynamics of the mistral at the Rhône valley exit on 28 June 2001. The mistral refers to a severe wind that develops along the Rhône valley in southern France. This summer mistral event was documented in the framework of the ESCOMPTE field experiment. The dynamical processes driving the circulation of the mistral in the Rhône valley and particularly wake formation and planetary boundary layer (PBL) inhomogeneity at the scale of Rhône valley delta are investigated. Several important data sources are used (airborne Doppler lidar, radiosondes and surface stations) as well as non-hydrostatic mesoscale simulations. This paper analyses experimentally, numerically and theoretically the mechanism of wake formation. It shows that the flow impinging on the Alpine range and the Massif Central becomes supercritical all along the ridge line, including the Rhône valley and continues to accelerate in the lee regions until a hydraulic jump occurs. It leads to the formation of wakes behind and close to the mountain peaks. Compared to the Massif Central wake, the origin of the western Alps wake is rather complicated. In this study, the observations and simulations suggest a combined wall separation/gravity wave breaking mechanism to explain the western Alps wake. Indeed, it is shown that in addition to the flow descending the western Alps slopes and experiencing a strong hydraulic jump, the point where the mistral flow separates from the eastern flank of the Rhône valley located at about 44°N is associated with a 'flank-shock' which is an oblique hydraulic jump (i.e.the downstream Froude number is supercritical). Wake formation in the lee of the Alps and the Massif Central causes large inhomogeneity of the PBL with differences between land and sea. In the Massif Central and western Alps wakes, the continental PBL is deeper (1.8 km) than in the mistral flow (1 km), which is consistent with a subcritical regime associated with enhanced turbulent mixing. The supercritical air flow, descending the Massif Central and Alps slopes and transitioning to subcritical flow, increases the near-surface air temperature due to the föhn effect. Over the Mediterranean, the surface heat fluxes are slightly negative (between–50 and 0 W m –2) and the main source of PBL turbulence is mechanical (wind shear). The PBL depth within the mistral flow does not vary over land (1 km), whereas the absence of convection but also of strong winds prevent PBL development over the sea in the wakes of the Massif Central and the Alps (PBL depth of about 0.5 km).

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : Jean-François GhiglioneMarièle LarcherPhilippe Lebaron
• Organismes : Laboratoire d'océanographie biologique de Banyuls Laboratoire d'océanographie biologique de Banyuls Laboratoire d'océanographie biologique de Banyuls
• Publié dans Aquatic Microbial Ecology le 02/11/2020

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Fichiers liés : a040p229.pdf

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : Jean‐sébastien LauretChristophe VoisinSébastien BergerGuillaume CassaboisClaude DelalandePhilippe RoussignolLaurence Goux-CapesArianna Filoramo
• Organismes : Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire d'Electronique Moléculaire Laboratoire d'Electronique Moléculaire
• Publié dans Physical Review B: Condensed Matter and Materials Physics (1998-2015) le 02/11/2020

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Résumé : Carrier dynamics is investigated in both luminescent and non luminescent samples of single wall carbon nanotubes -obtained by laser ablation- by means of two-color pump-probe experiments. The recombination dynamics is monitored by probing the transient photobleaching observed on the interband transitions of semi-conducting nanotubes. Interband and inter-subband relaxation times are about one order of magnitude slower in isolated nanotubes than in ropes of nanotubes bringing evidence of the environment influence on the carrier dynamics. The relaxation dynamics is non-exponential and is interpreted as a consequence of the inhomogeneity of the sample. Slow components up to 250 ps are measured which is significantly greater than values previoulsy reported in HiPCo nanotubes. These observations show the great dependence of the electronic properties of carbon nanotubes on the synthesis method and on their environment.

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Fichiers liés : voisin_prb.pdf

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• Type de publi. : Communication dans un congrès
• Date de publi. : 01/01/2005
• Auteurs : Sébastien BergerJean‐sébastien LauretGuillaume CassaboisChristophe VoisinPhilippe RoussignolClaude DelalandeLaurence Goux-CapesArianna Filoramo
• Organismes : Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Laboratoire Pierre Aigrain Service de physique de l'état condensé Service de physique de l'état condensé

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