Philippe JEAN-PIERRE

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : John MozleyPhilippe HyafilGilles NoguesMichel BruneJean-Michel RaimondSerge Haroche
• Organismes : Laboratoire Kastler Brossel Laboratoire Kastler Brossel Laboratoire Kastler Brossel Laboratoire Kastler Brossel Laboratoire Kastler Brossel Laboratoire Kastler Brossel Laboratoire Kastler Brossel
• Publié dans The European Physical Journal D : Atomic, molecular, optical and plasma physics le 28/10/2020

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Résumé : We propose to apply atom-chip techniques to the trapping of a single atom in a circular Rydberg state. The small size of microfabricated structures will allow for trap geometries with microwave cut-off frequencies high enough to inhibit the spontaneous emission of the Rydberg atom, paving the way to complete control of both external and internal degrees of freedom over very long times. Trapping is achieved using carefully designed electric fields, created by a simple pattern of electrodes. We show that it is possible to excite, and then trap, one and only one Rydberg atom from a cloud of ground state atoms confined on a magnetic atom chip, itself integrated with the Rydberg trap. Distinct internal states of the atom are simultaneously trapped, providing us with a two-level system extremely attractive for atom-surface and atom-atom interaction studies. We describe a method for reducing by three orders of magnitude dephasing due to Stark shifts, induced by the trapping field, of the internal transition frequency. This allows for, in combination with spin-echo techniques, maintenance of an internal coherence over times in the second range. This method operates via a controlled light shift rendering the two internal states' Stark shifts almost identical. We thoroughly identify and account for sources of imperfection in order to verify at each step the realism of our proposal.

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Fichiers liés : version2.pdf

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• Type de publi. : Chapître d'ouvrage
• Date de publi. : 01/01/2005
• Auteurs : Stéphane GallandFrédéric GrimaudPhilippe BeauneJean−pierre Campagne
• Organismes : Département Systèmes Multi-Agents Département Méthodes Scientifiques pour la Gestion Industrielle Département Systèmes Multi-Agents Laboratoire de Productique et Informatique des systèmes manufacturiers Laboratoire d'Informatique pour l'Entreprise et les Systèmes de Production

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Résumé : We are located in the context of the industrial system simulation, which are complex and distributed in operational, informational and decisional terms. In this chapter, we present the problems and a methodological solution. This methodology is based on the systemic approach and on multi-agent systems. It allows the modelling of distributed industrial systems such as enterprise consortiums. Moreover, it proposes a software platform architecture whish is currently instanced with Arena and dedicated agents.

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : Nancy TerrierDavid GlissantJérôme GrimpletFrançois BarrieuPhilippe AbbalCarole CoutureAgnès AgeorgesRossitza AtanassovaCéline LéonJean-Pierre RenaudinFabienne DédaldéchampCharles RomieuSerge DelrotSaïd Hamdi
• Organismes : Sciences Pour l'Oenologie Transport des assimilats [UMR 6161] Sciences Pour l'Oenologie UMR 619 Equipe Biologie de la Vigne Sciences Pour l'Oenologie UMR 619 Equipe Biologie de la Vigne Sciences Pour l'Oenologie Transport des assimilats [UMR 6161] UMR 619 Equipe Biologie de la Vigne UMR 619 Equipe Biologie de la Vigne Transport des assimilats [UMR 6161] Sciences Pour l'Oenologie Transport des assimilats [UMR 6161] UMR 619 Equipe Biologie de la Vigne
• Publié dans Planta le 31/10/2020

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Résumé : The transition from a green, hard, and acidic pericarp to a sweet, soft, coloured, and sugar-rich ripe fruit occurs in many unrelated fruit species. High throughput identification of differentially expressed genes in grape berry has been achieved by the use of 50-mers oligoarrays bearing a set of 3,200 Unigenes from Vitis vinifera to compare berry transcriptome at nine developmental stages. Analysis of transcript profiles revealed that most activations were triggered simultaneously with softening, occurring within only 24 h for an individual berry, just before any change in colouration or water, sugar, and acid content can be detected. Although most dramatically induced genes belong to unknown functional categories, numerous changes occur in the expression of isogenes involved in primary and secondary metabolism during ripening. Focusing on isogenes potentially significant in development regulation (hormonal control of transcription factor) revealed a possible role for several hormones (cytokinin, gibberellin, or jasmonic acid). Transcription factor analysis revealed the induction of RAP2 and WRKY genes at veraison, suggesting increasing biotic and abiotic stress conditions during ripening. This observation was strengthened by an increased expression of multiple transcripts involved in sugar metabolism and also described as induced in other plant organs during stress conditions. This approach permitted the identification of new isogenes as possible control points: a glutathione S-transferase exhibits the same expression profile as anthocyanin accumulation and a new putative sugar transporter is induced in parallel with sugar import. Berries, collected from nine development stages (green to overripe) of the cv Shiraz (Vitis vinifera) and from two development stages (half-green and half-ripe) of the cvs Chardonnay and Cabernet Sauvignon, were used to detect differentially expressed genes; it was achieved by micro-array analysis developing 50-mer oligo arrays representing a set of 3,175 Unigenes from EST 3' sequencing of seven different libraries. Analysis of transcript profiles revealed a simultaneous activation of hundreds of genes at the berry softening, occurring within a shorter period of 48 h, and just before any change in color, water, sugar, and acid content. Although most induced genes belong to unknown functions, numerous changes occur in the expression of isogenes involved in primary and secondary ripening metabolism, in biotic and abiotic stress conditions and in hormonal control.

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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 : Jean-Philippe DelahayeChristophe MoyPierre LerayJacques Palicot
• Organismes : Institut d'Électronique et des Technologies du numéRique Institut d'Electronique et de Télécommunications de Rennes Institut d'Electronique et de Télécommunications de Rennes Institut d'Electronique et de Télécommunications de Rennes

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Résumé : This paper deals with partial reconfiguration issues on heterogeneous prototyping platforms (DSP/ FPGA). An analysis of multi-standard physical layer applications in terms of reconfiguration needs permits to extract several use cases of reconfiguration in a multi-standard handset: standard switching, mode switching, bug fixing, etc. The main difference between these schemes of reconfiguration is the level of granularity of the reconfiguration. We argue that a configuration manager needs to handle this multi-granularity of reconfiguration to optimize the change of context (either reconfigurable hardware or programmable software processing components) in terms of size of code, time to reconfigure, etc. The analysis also helps to determine the accurate level of flexibility needed through the reconfigurable architecture at different scales. Within this framework partial reconfiguration is an essential feature for optimizing the reconfiguration inside FPGA. We aim indeed at providing reconfiguration adequacy between re-configurability capabilities of hardware resources and reconfiguration needs of Software Defined Radio applications. Architectural solutions are proposed to implement partial reconfiguration on existing hardware combining DSP and FPGA.

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Fichiers liés : 02.2-01.PDF

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• Type de publi. : Article dans une revue
• Date de publi. : 01/01/2005
• Auteurs : Jean-Pierre PonssardDominique PlihonPhilippe Zarlowski
• Organismes : Département d'Économie de l'École Polytechnique Centre d'Economie de l'Université Paris Nord (ancienne affiliation) ESSEC Business School
• Publié dans Corporate Ownership and Control le 24/10/2020

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Résumé : A new hybrid model of corporate governance seems to be emerging as a mixture of the shareholder and the stakeholder models. Its two main characteristics consist in an increased control of corporate executives by strong minority shareholders: this strengthened financial control is balanced by the rise of the social and environmental responsibilities of firms. This paper elaborates on this hypothesis and reviews the forces at work in this emerging process.

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