Fiabilité des diodes lasers DFB 1,55 µm pour des applications de télécommunication : approche statistique et interaction composant-système

Ces travaux de thèse décrivent le développement et la mise en oeuvre d’une méthodologie d’estimation de la fiabilité à long terme d’une technologie stabilisée de diode laser à contre-réaction répartie (DFB) 1,55µm à couche active InGaAsP sur substrat InP pour des applications de télécommunication. Elle est basée sur la mesure de caractéristiques électriques et optiques analysées après l'application de contraintes de vieillissement combinant différents facteurs d’accélération. Une méthode de reconstruction statistique de distributions de durée de vie, basées sur les tirages de Monte-Carlo, a été mise en oeuvre pour palier à la faible population de composants et aux faibles variations paramétriques induites par les tests accélérés. Enfin, l'interaction composant-système est analysée par l'intermédiaire de simulations d'une liaison de télécommunication 4 canaux utilisant le multiplexage de longueurs d’onde (WDM) avec un débit 2,5 Gbits/s par canal. Ces simulations ont permis d'évaluer l'impact des dérives expérimentales sur les performances de ce type de liaison, en conditions opérationnelles, en prévision de futures architectures de réseaux métropolitains et locaux.This work describes the development and the setting of a methodology to estimate longterm reliability of mature distributed feedback (DFB) 1,55µm laser diode with InGaAsP active layer on InP substrate for applications of telecommunication. This methodology is based on the measurement of electric and optical characteristics analyzed after application of ageing combining various factors of acceleration. A statistical method of lifetime distribution rebuilding, based on Monte-Carlo random selection, was carried out in order to compensate for the weak population of components and the weak parametric variations induced by the accelerated tests. Lastly, the component-system interaction is analyzed via simulations of a 4 channels telecommunication link using the multiplexing wavelengths (WDM) with a 2,5 Gbits/s bit rate by channel. These simulations made it possible to evaluate the impact of experimental drifts on this kind of link performances, in operational conditions, in preparation for future architectures of local and metropolitan area network

GABAergic and Cortical and Subcortical Glutamatergic Axon Terminals Contain CB1 Cannabinoid Receptors in the Ventromedial Nucleus of the Hypothalamus

Background: Type-1 cannabinoid receptors (CB1R) are enriched in the hypothalamus, particularly in the ventromedial hypothalamic nucleus (VMH) that participates in homeostatic and behavioral functions including food intake. Although CB1R activation modulates excitatory and inhibitory synaptic transmission in the brain, CB1R contribution to the molecular architecture of the excitatory and inhibitory synaptic terminals in the VMH is not known. Therefore, the aim of this study was to investigate the precise subcellular distribution of CB1R in the VMH to better understand the modulation exerted by the endocannabinoid system on the complex brain circuitries converging into this nucleus. Methodology/Principal Findings: Light and electron microscopy techniques were used to analyze CB1R distribution in the VMH of CB1R-WT, CB1R-KO and conditional mutant mice bearing a selective deletion of CB1R in cortical glutamatergic (Glu-CB1R-KO) or GABAergic neurons (GABA-CB1R-KO). At light microscopy, CB1R immunolabeling was observed in the VMH of CB1R-WT and Glu-CB1R-KO animals, being remarkably reduced in GABA-CB1R-KO mice. In the electron microscope, CB1R appeared in membranes of both glutamatergic and GABAergic terminals/preterminals. There was no significant difference in the percentage of CB1R immunopositive profiles and CB1R density in terminals making asymmetric or symmetric synapses in CB1R-WT mice. Furthermore, the proportion of CB1R immunopositive terminals/preterminals in CB1R-WT and Glu-CB1R-KO mice was reduced in GABA-CB1R-KO mutants. CB1R density was similar in all animal conditions. Finally, the percentage of CB1R labeled boutons making asymmetric synapses slightly decreased in Glu-CB1R-KO mutants relative to CB1R-WT mice, indicating that CB1R was distributed in cortical and subcortical excitatory synaptic terminals. Conclusions/Significance: Our anatomical results support the idea that the VMH is a relevant hub candidate in the endocannabinoid-mediated modulation of the excitatory and inhibitory neurotransmission of cortical and subcortical pathways regulating essential hypothalamic functions for the individual's survival such as the feeding behavior.L. Reguero is in receipt of a Predoctoral Fellowship from the Basque Country Government (BFI 07.286); I. Buceta is in receipt of a Predoctoral Fellowship from the Basque Country University. Dr. Pedro Grandes' laboratory is supported by The Basque Country Government grant GIC07/70-IT-432-07, by Ministerio de Ciencia e Innovacion (SAF2009-07065) and by Red de Trastornos Adictivos, RETICS, Instituto de Salud Carlos III, MICINN, grant RD07/0001/2001. Dr. Giovanni Marsicano's laboratory is supported by AVENIR/INSERM (with the Fondation Bettencourt-Schueller), by ANR (ANR-06-NEURO-043-01), by European Foundation for the Study of Diabetes (EFSD), by the EU-FP7 (REPROBESITY, contract number HEALTH-F2-2008-223713) and European Commission Coordination Action ENINET (contract number LSHM-CT-2005-19063). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe

Observation of tW production in the single-lepton channel in pp collisions at root s=13 TeV

A measurement of the cross section of the associated production of a single top quark and a W boson in final states with a muon or electron and jets in proton-proton collisions at root s = 13 TeV is presented. The data correspond to an integrated luminosity of 36 fb(-1) collected with the CMS detector at the CERN LHC in 2016. A boosted decision tree is used to separate the tW signal from the dominant t (t) over bar background, whilst the subleading W+jets and multijet backgrounds are constrained using data-based estimates. This result is the first observation of the tW process in final states containing a muon or electron and jets, with a significance exceeding 5 standard deviations. The cross section is determined to be 89 +/- 4 (stat) +/- 12 (syst) pb, consistent with the standard model.Peer reviewe

Measurement of the top quark mass using events with a single reconstructed top quark in pp collisions at root s=13 TeV

Abstract:A measurement of the top quark mass is performed using a data sample en-riched with single top quark events produced in thetchannel. The study is based on proton-proton collision data, corresponding to an integrated luminosity of 35.9 fb−1, recorded at√s= 13TeV by the CMS experiment at the LHC in 2016. Candidate events are selectedby requiring an isolated high-momentum lepton (muon or electron) and exactly two jets,of which one is identified as originating from a bottom quark. Multivariate discriminantsare designed to separate the signal from the background. Optimized thresholds are placedon the discriminant outputs to obtain an event sample with high signal purity. The topquark mass is found to be172.13+0.76−0.77GeV, where the uncertainty includes both the sta-tistical and systematic components, reaching sub-GeV precision for the first time in thisevent topology. The masses of the top quark and antiquark are also determined separatelyusing the lepton charge in the final state, from which the mass ratio and difference aredetermined to be0.9952+0.0079−0.0104and0.83+1.79−1.35GeV, respectively. The results are consistentwithCPTinvariance

Search for a heavy Higgs boson decaying into two lighter Higgs bosons in the tau tau bb final state at 13 TeV

A search for a heavy Higgs boson H decaying into the observed Higgs boson h with a mass of 125 GeV and another Higgs boson h(S) is presented. The h and h(S) bosons are required to decay into a pair of tau leptons and a pair of b quarks, respectively. The search uses a sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137 fb(-1). Mass ranges of 240-3000 GeV for m(H) and 60-2800 GeV for m(hS) are explored in the search. No signal has been observed. Model independent 95% confidence level upper limits on the product of the production cross section and the branching fractions of the signal process are set with a sensitivity ranging from 125 fb (for m(H) = 240 GeV) to 2.7 fb (for m(H) = 1000 GeV). These limits are compared to maximally allowed products of the production cross section and the branching fractions of the signal process in the next-to-minimal supersymmetric extension of the standard model.Peer reviewe