Philippe JEAN-PIERRE

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• Type de publi. : Communication dans un congrès
• Date de publi. : 01/08/2007
• Auteurs : Valérie BossePhilippe BoulvaisPierre GautierM. TiepoloGilles RuffetJean-Luc Devidal
• Organismes : Laboratoire Magmas et Volcans Géosciences Rennes Géosciences Rennes Géosciences Rennes Laboratoire Magmas et Volcans

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Résumé : The monazite U-Th-Pb chronometer is extensively used to date metamorphic rocks because it is usually considered to be resistant to diffusive Pb loss at temperatures as high as 800°C. However, age perturbations are sometimes documented in monazite grains showing distinct compositional and age domains. The mechanism by which Pb is lost is not well understood. Fluid-assisted recrystallization has been shown to constitute an efficient mean to reset the monazite chronometer in experimental conditions (Seydoux-Guillaume et al. 2002). Whether the same holds true in natural systems remains to be documented. Here we present in situ U-Th-Pb ages on monazite from foliated pegmatitic veins from highly strained levels of the Central Rhodope metamorphic pile (Greece, Bulgaria), together with oxygen isotope characterization and 40Ar-39Ar data. U-Th-Pb ages were obtained by (LA)-ICPMS on 8 monazite grains from three samples. In one sample from Bulgaria, the ages are concordant at 35 Ma, and no chemical zonation is observed. Quartz and feldspar have ..18O values consistent with equilibration at high temperatures. Microfabrics in the vein and the host rocks indicate high grade conditions of deformation. In the two other samples, from Greece, monazite grains show distinct chemical domains and yield discordant U-Th-Pb ages ranging from 52 to 36 Ma. Strong oxygen isotope disequilibrium between quartz and feldspar argues for a complex fluid history: high-..18O fluids first invaded rocks and were followed by low-..18O fluids at lower temperatures. Low temperature fluid circulation at around 36 Ma is consistent with 40Ar-39Ar dating of both samples at 33-34 Ma (mica plateau ages) and with microfabrics documenting a transition from high grade to greenschist facies conditions of deformation during intense shearing. These data confirm the capacity of fluids in disturbing significantly the monazite chronometer.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/08/2007
• Auteurs : Juan Gil YacobazzoPierre-Marie PreuxAhmadou AlioumCarlos KetzoianJean-Claude DesportMichel Druet-CabanacPhilippe Couratier
• Organismes : Neuroépidémiologie Tropicale et Comparée Neuroépidémiologie Tropicale et Comparée Laboratoire de Biostatistique et d'Informatique Médicale Service de l'Information Médicale et de l'Évaluation [CHU Limoges] Neuroépidémiologie Tropicale et Comparée Service d'Hépato-gastro-entérologie et Nutrition [CHU Dupuytren 1, Limoges] Neuroépidémiologie Tropicale et Comparée Service de Santé au Travail [CHU Limoges] Unité Fonctionnelle Registre Général des Cancers du Limousin Neuroépidémiologie Tropicale et Comparée Service de Neurologie [CHU Limoges]
• Publié dans Critical Reviews in Oncology/Hematology le 31/10/2020

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Résumé : Although several prognostic factors have been identified in ALS, there remains some discordance concerning the prognostic significance of the age and clinical form at onset. In order to clarify these findings, we have analysed already known prognostic factors using a multi-state model. Two hundred and twenty-two sporadic ALS patients were followed. A simple unidirectional three-states model was used to summarize clinical course of ALS. States 1 and 2 reflected the progression of neurological impairment and state 3 represented the end of follow-up (tracheotomy or death). Gender, diagnostic delay, body mass index (BMI) and slow vital capacity (SVC) were also recorded. A time-inhomogeneous Markov model with piecewise constant transition intensities was used to estimate the effect of the covariates in each transition. The bulbar form at onset was only correlated with a more rapid clinical progression between state 1 and state 2. In contrast, an advanced age at diagnosis affected only survival from state 2. This methodological approach suggests that these two factors have a different prognostic significance: age at onset is related to patient's survival and the clinical form at onset predicts the progression of motoneuronal impairment in different regions.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/08/2007
• Auteurs : Christophe BureauJuan Carlos Garcia PaganGilles Pomier LayrarguesSophie MetivierPablo BellotPierre PerreaultPhilippe OtalJuan-G AbraldesJean Marie PeronHervé RousseauJaume BoschJean Pierre Vinel
• Organismes : Institut de médecine moléculaire de Rangueil Service de Gastroentérologie et pancréatologie [CHU Toulouse] Hepatic Hemodynamic Liver Unit Liver Unit Institut de médecine moléculaire de Rangueil Hepatic Hemodynamic Liver Unit Liver Unit Service Radiologie et imagerie médicale - Rangueil / Larrey [CHU Toulouse] Hepatic Hemodynamic Liver Unit Service de Gastroentérologie et pancréatologie [CHU Toulouse] Service Radiologie et imagerie médicale - Rangueil / Larrey [CHU Toulouse] Hepatic Hemodynamic Liver Unit Institut de médecine moléculaire de Rangueil Service de Gastroentérologie et pancréatologie [CHU Toulouse]
• Publié dans Liver International le 25/10/2020

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Résumé : An 80% dysfunction rate at 2 years limits the use of transjugular intrahepatic portosystemic shunts (TIPS) in the treatment of complications of portal hypertension. The use of covered stents could improve shunt patency; however, long-term effect and safety remain unknown. Eighty patients randomized to be treated by TIPS either with a covered stent (Group 1) or an uncovered prosthesis (Group 2) were followed-up for 2 years. Doppler US was performed every 3 months. Angiography and portosystemic pressure gradient measurement were performed every 6 months or whenever dysfunction was suspected. Actuarial rates of primary patency in Groups 1 and 2 were 76% and 36% respectively (P=0.001). Clinical relapse occurred in four patients (10%) in Group 1 and 12 (29%) in Group 2 (P<0.05). Actuarial rates of being free of encephalopathy were 67% in Group 1 and 51% in Group 2 (P<0.05). Probability of survival was 58% and 45% at 2 years, respectively, in Groups 1 and 2 (NS). The mean Child-Pugh score improved only in Group 1 (from 8.1+/-1.6 to 7+/-2.2 at 2 years -P<0.05). We also compared the Doppler-US parameters between patent and dysfunctioning shunts. In patent shunts, the mean velocity within the portal vein was significantly higher but the performance of Doppler-US was not accurate enough to predict shunt dysfunction. In conclusion, the improvement in TIPS patency by using covered prostheses is maintained over time with a decreased risk of encephalopathy, while the risk of death was not increased.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 27/07/2007
• Auteurs : Jean-Guillaume DumasPhilippe Elbaz-VincentPascal GiorgiAnna Urbanska
• Organismes : Calculs Algébriques et Systèmes Dynamiques Institut de Mathématiques et de Modélisation de Montpellier Laboratoire de Physique Appliquée et d'Automatique Calculs Algébriques et Systèmes Dynamiques

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Résumé : This paper deals with the computation of the rank and of some integer Smith forms of a series of sparse matrices arising in algebraic K-theory. The number of non zero entries in the considered matrices ranges from 8 to 37 millions. The largest rank computation took more than 35 days on 50 processors. We report on the actual algorithms we used to build the matrices, their link to the motivic cohomology and the linear algebra and parallelizations required to perform such huge computations. In particular, these results are part of the first computation of the cohomology of the linear group GL_7(Z).

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Fichiers liés : parank.pdf

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• Type de publi. : Communication dans un congrès
• Date de publi. : 23/07/2007
• Auteurs : Kauzar Saleh ContellWigneron J.-P.Patricia de RosnayMaria Jose EscorihuelaYann H. KerrJean-Christophe CalvetMike SchwankPhilippe Waldteufel
• Organismes : Department of Geography [Cambridge, UK] Écologie fonctionnelle et physique de l'environnement Centre d'études spatiales de la biosphère Centre d'études spatiales de la biosphère Centre d'études spatiales de la biosphère Centre national de recherches météorologiques Institute of Terrestrial Ecosystems Service d'aéronomie

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Résumé : This paper compares L-band measurements from three different experiments in areas covered by grass. The main objective is to assess soil moisture retrievals based on the L-band Microwave Emission of the Biosphere model (L-MEB) used by the Soil Moisture and Ocean Salinity mission (SMOS). Results indicate that over grass the vegetation is isotropic to the microwave propagation at horizontal polarisation, while at vertical polarisation non-zero scattering is observed for all the grass data sets. Surface soil moisture is retrieved with enough accuracy for all data sets as long as the soil roughness and litter emission are calibrated beforehand. The study also highlights the importance of detecting strong attenuation by wet vegetation and litter due to rainfall interception. We show that strong rainfall interception can be flagged using a microwave polarisation index.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 23/07/2007
• Auteurs : Kauzar Saleh ContellYann H. KerrGilles BouletPhilippe MaisongrandePatricia de RosnayDana FloricioiuMaria Jose EscorihuelaWigneron J.-P.Aurelio CanoErnesto Lopez-BaezaJennifer P. Grant
• Organismes : Department of geography Centre d'études spatiales de la biosphère Centre d'études spatiales de la biosphère Centre d'études spatiales de la biosphère Centre d'études spatiales de la biosphère Centre d'études spatiales de la biosphère Centre d'études spatiales de la biosphère Écologie fonctionnelle et physique de l'environnement Universitat de València = University of Valencia = Universidade de Valencia Universitat de València = University of Valencia = Universidade de Valencia Vrije Universiteit Amsterdam [Amsterdam]

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• Type de publi. : Communication dans un congrès
• Date de publi. : 23/07/2007
• Auteurs : Gabriel VasileEmmanuel TrouvéLionel ValetJean-Marie NicolasLionel BombrunMichel GayIvan PétillotPhilippe BolonVasile Buzuloiu
• Organismes : GIPSA - Signal Images Physique GIPSA - Signal Images Physique Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance Laboratoire Traitement et Communication de l'Information GIPSA - Signal Images Physique GIPSA-Services GIPSA - Signal Images Physique Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance Laboratoire API

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Résumé : SAR interferometry (InSAR) performs two acquisitions (spatially separated by the baseline) of the signal back-scattered by the resolution cell which contains height and/or displacement information. Repeat pass spaceborne interferometry provides multi-interferograms which can be used to extract such information either by combining the multi-temporal results of conventional interferometry or by a different approach based on specific targets: the coherent stable scatterers (CSS). In this paper a two-step approach is proposed to obtain specific features from multi-temporal InSAR data sets. The first step consists in extracting image attributes related to the useful information. The second step consists in merging the attributes using an interactive fuzzy fusion technique. The interactive fuzzy fusion is proposed to provide end-users with a simple and easily understandable tool for tuning the detection results. The method is applied on a data set of five co-registered ERS 1/2 tandems from the French Alps (the Mont-Blanc region), including two temperate glaciers: the Argenti'ere and the Mer-de-glace. The results illustrate how the end-user can combine the proposed attributes to detect the presence of CSS or distributed stable scatterers usefull for multi-temporal analysis.

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Fichiers liés : IGARSS_2007_1.pdf

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• Type de publi. : Communication dans un congrès
• Date de publi. : 23/07/2007
• Auteurs : Sonia ZineJacqueline BoutinJ. FontCarolina GabarróMarco TaloneNicolas ReulJoseph TenerelliPhilippe WaldteufelFrançois PetitcolinJean-Luc Vergely
• Organismes : Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques Institute of Marine Sciences / Institut de Ciències del Mar [Barcelona] Institute of Marine Sciences / Institut de Ciències del Mar [Barcelona] Institute of Marine Sciences / Institut de Ciències del Mar [Barcelona] Laboratoire d'Océanographie Spatiale Laboratoire d'Océanographie Spatiale Service d'aéronomie Analytic and Computational Research, Inc. - Earth Sciences Analytic and Computational Research, Inc. - Earth Sciences

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Résumé : The Soil Moisture and Ocean Salinity (SMOS) mission (launch scheduled for 2008) aims at obtaining global maps of soil moisture and sea surface salinity (SSS). It uses an L-band (1.4 GHz) microwave interferometric radiometer to obtain brightness temperatures (Tb) at the Earth surface at horizontal and vertical polarizations. They will be used to retrieve both geophysical variables, following specifically designed algorithms that will be applied when the satellite field-of-view is covering land or ocean surfaces respectively. The retrieval of salinity is a complex process that requires the knowledge of environmental information and an accurate processing of the radiometer measurements, because of the narrow range of ocean Tb and the strong impact on the measures of geophysical parameters (such as sea state). Here we present the baseline approach chosen to retrieve sea surface salinity from SMOS data, as developed and implemented by the joint team of scientists and engineers responsible for the SMOS Salinity Level 2 Prototype Processor. We present academic tests conducted over homogeneous scenes with the prototype. In these configurations, external perturbation sources (sky radiation, sun glint, ...) are not taken into account. Roughness is the main sea surface signal disturbing SSS retrieval. In dual pol, wind speed biases are better corrected at the center of the swath than at the edge.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 23/07/2007
• Auteurs : Sonia ZineJacqueline BoutinJordi FontCarolina GabarróMarco TaloneNicolas ReulJoseph TenerelliPhilippe WaldteufelFrançois PetitcolinJean-Luc Vergely
• Organismes : Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques Mediterranean Center for Marine and Environmental Research Mediterranean Center for Marine and Environmental Research Mediterranean Center for Marine and Environmental Research Laboratoire d'Océanographie Spatiale Laboratoire d'Océanographie Spatiale Analytic and Computational Research, Inc. - Earth Sciences Analytic and Computational Research, Inc. - Earth Sciences

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Résumé : The Soil Moisture and Ocean Salinity (SMOS) mission (launch scheduled for 2008) aims at obtaining global maps of soil moisture and sea surface salinity (SSS). It uses an L-band (1.4 GHz) microwave interferometric radiometer to obtain brightness temperatures (Tb) at the Earth surface at horizontal and vertical polarizations. They will be used to retrieve both geophysical variables, following specifically designed algorithms that will be applied when the satellite field-of-view is covering land or ocean surfaces respectively. The retrieval of salinity is a complex process that requires the knowledge of environmental information and an accurate processing of the radiometer measurements, because of the narrow range of ocean Tb and the strong impact on the measures of geophysical parameters (such as sea state). Here we present the baseline approach chosen to retrieve sea surface salinity from SMOS data, as developed and implemented by the joint team of scientists and engineers responsible for the SMOS Salinity Level 2 Prototype Processor. We present academic tests conducted over homogeneous scenes with the prototype. In these configurations, external perturbation sources (sky radiation, sun glint, ...) are not taken into account. Roughness is the main sea surface signal disturbing SSS retrieval.

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• Type de publi. : Communication dans un congrès
• Date de publi. : 18/07/2007
• Auteurs : Lionel BombrunIvan PétillotGabriel VasileMichel GayEmmanuel TrouvéPhilippe BolonJean-Marie NicolasTania Landes
• Organismes : GIPSA - Signal Images Physique Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance GIPSA-Services GIPSA - Signal Images Physique Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance Département Réseaux, Sécurité et Multimédia Modèles et simulation pour l'architecture, l'urbanisme et le paysage

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Résumé : Temperate glaciers are an indicator of the local effects of global climate change. For economical and security reasons in the surrounding areas, the monitoring of those geophysical objects is being a necessity. SAR data are expected to provide dense measurements of physical parameters which are necessary to detect significant changes and to constrain glacier flow models. In this paper, five descending one-day ERS- 1/2 tandem interferometric data pairs from July 1995 to April 1996 are studied in the Chamonix Mont-Blanc area (French Alps). This multi-temporal interferogram series is used to analyse the coherence levels and fringe patterns over nine glaciers. Moreover, when the coherence is sufficient, Differential SAR Interferometry (D-InSAR) processing are applicable to derive a three-dimensional (3-D) velocity fields. An expert knowledge and a ten years measurements analysis of glacier flow are used to fix the line of sight (LOS) displacement offset. Finally, an analysis of the wrapped phase difference between interferograms is exposed to detect the presence of residual topographic fringes and to characterize the surface flow field evolution.

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Fichiers liés : Bombrun_07_MULTITEMP.pdf

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