Algorithmes mémétiques de détection de communautés dans les réseaux complexes (techniques palliatives de la limite de résolution)

Les réseaux complexes, issus de relevés de terrain d origines trèsvariées, en biologie, science de l information ou sociologie,présentent une caractéristique remarquable dénommée structurecommunautaire. Des groupes, ou communautés, à l intérieur duréseau, ont une cohésion interne forte et des liens entre eux plusfaibles. Sans connaissance a priori du nombre de communautés, ladifficulté réside dans la caractérisation d un bon partitionnement encommunautés. La modularité est une mesure globale de qualité departitionnement très utilisée qui capture les contraintes de cohésioninterne forte et de liens externes faibles. Elle transforme le problèmede détection de communautés en problème d optimisationNP-difficile. Elle souffre d un défaut, la limite de résolution, qui tendà rendre indétectables les très petites communautés d autant plusque le réseau est grand. L algorithme le plus efficace pour optimiserla modularité, dit de Louvain, procède par fusion de communautés.Cette thèse s attache à modifier cet algorithme pour qu il réalisemajoritairement des fusions pertinentes, qui n aggravent pas lalimite de résolution, en utilisant une condition de fusion. De plus, enl associant à un algorithme mémétique, les partitions proposéessont très proches des partitions attendues pour des graphesgénérés par un modèle qui reproduit les caractéristiques desréseaux complexes. Enfin, cet algorithme mémétique réduitfortement l inconsistance de solution, défaut de la modularité selonlequel deux partitions trouvées à partir d un examen des noeudsdans un ordre aléatoire, pour le même graphe, peuvent êtrestructurellement très différentes, rendant leur interprétation délicate.From various applications, in sociology or biology for instance,complex networks exhib the remarquable property of communitystructure. Groups, sometimes called communities, has a stronginternal cohesion and poor links between them. Whithout priorknowledge of the number of communities, the difficulty lies in thecharacterization of a good clustering. Modularity is an overallmeasure of clustering quality widely used to capture the doubleconstraint, internal and external, of well formed communities. Theproblem became a NP-hard optimization problem. The main weakof modularity is the resolution limit, which tends to makeundetectable very small communities especially as the network islarge. The algorithm of Louvain, one of the most efficient one tooptimize modularity, proceeds by merging communities. This thesisattempts to modify the algorithm so that it mainly produces relevantmerges that do not make worse the effects of resolution limit, usinga merge condition. In addition, by combining it with a memeticalgorithm, proposed clusterings are very close to the expected onesfor graphs generated by a model that reproduces the characteristicsof complex networks. Finally, the memetic algorithm greatly reducesthe inconsistency of solution, another weakness of modularity suchthat, for the same graph, two partitions found from an exploration ofnodes in a random order can be structurally very different, makingthem difficult to interpret.LE MANS-BU Sciences (721812109) / SudocSudocFranceF

Effect of Tizanidine on Spasticity in Pediatric Patients with Cerebral Palsy: A Systematic Review

Purpose Cerebral palsy (CP) is a permanent, non-progressive disorder of the developing brain. Tizanidine is an effective treatment for spastic CP; however, insufficient evidence exists regarding its effect on motor function and side-effect profile. This review explored the effects and safety of tizanidine in treating spasticity among pediatric patients with CP. Methods Two reviewers conducted a literature search. The Cochrane risk of bias tool and the 14-item National Institutes of Health Quality Assessment Tool were used to evaluate the risk of bias. A systematic review was performed for relevant studies. Results Five studies were included: three randomized controlled trials (RCTs) and two observational studies. The control group received a placebo in two RCTs, while baclofen was used in the remaining studies. Tizanidine dosage and duration varied across reports, except for the two observational studies. Excepting one observational study, tizanidine was associated with a greater improvement on the modified Ashworth scale. Pain reduction was also greater with tizanidine treatment compared to the placebo, as evidenced by one RCT. Three studies evaluating gross motor function reported superior results with tizanidine compared to baclofen. Two RCTs indicated similar safety profiles between tizanidine and the placebo. The remaining studies reported a more favorable safety profile for tizanidine than baclofen. Conclusion The studies examined in this review reported beneficial effects of tizanidine on spasticity, pain, and gross motor function. Tizanidine usage was associated with no serious adverse events, reflecting a better safety profile than baclofen. Nevertheless, high-quality RCTs are recommended to support tizanidine administration in pediatric patients

Overlap between flesh-footed shearwater <i>Puffinus</i> <i>carneipes</i> foraging areas and commercial fisheries in New Zealand waters

On page 250, the text erroneously states (in reference to flesh-footed shearwaters): 'A world population of ca. 740000 pairs was estimated by Lavers (2015) following recent Australian surveys.' The correct value is 74000 pairs

The first determination of Generalized Polarizabilities of the proton by a Virtual Compton Scattering experiment

Absolute differential cross sections for the reaction (e+p -> e+p+gamma) have been measured at a four-momentum transfer with virtuality Q^2=0.33 GeV^2 and polarization \epsilon = 0.62 in the range 33.6 to 111.5 MeV/c for the momentum of the outgoing photon in the photon-proton center of mass frame. The experiment has been performed with the high resolution spectrometers at the Mainz Microtron MAMI. From the photon angular distributions, two structure functions which are a linear combination of the generalized polarizabilities have been determined for the first time.Comment: 4 pages, 3 figure

In Vivo Delta Opioid Receptor Internalization Controls Behavioral Effects of Agonists

GPCRs regulate a remarkable diversity of biological functions, and are thus often targeted for drug therapies. Stimulation of a GPCR by an extracellular ligand triggers receptor signaling via G proteins, and this process is highly regulated. Receptor activation is typically accompanied by desensitization of receptor signaling, a complex feedback regulatory process of which receptor internalization is postulated as a key event. The in vivo significance of GPCR internalization is poorly understood. In fact, the majority of studies have been performed in transfected cell systems, which do not adequately model physiological environments and the complexity of integrated responses observed in the whole animal.In this study, we used knock-in mice expressing functional fluorescent delta opioid receptors (DOR-eGFP) in place of the native receptor to correlate receptor localization in neurons with behavioral responses. We analyzed the pain-relieving effects of two delta receptor agonists with similar signaling potencies and efficacies, but distinct internalizing properties. An initial treatment with the high (SNC80) or low (AR-M100390) internalizing agonist equally reduced CFA-induced inflammatory pain. However, subsequent drug treatment produced highly distinct responses. Animals initially treated with SNC80 showed no analgesic response to a second dose of either delta receptor agonist. Concomitant receptor internalization and G-protein uncoupling were observed throughout the nervous system. This loss of function was temporary, since full DOR-eGFP receptor responses were restored 24 hours after SNC80 administration. In contrast, treatment with AR-M100390 resulted in retained analgesic response to a subsequent agonist injection, and ex vivo analysis showed that DOR-eGFP receptor remained G protein-coupled on the cell surface. Finally SNC80 but not AR-M100390 produced DOR-eGFP phosphorylation, suggesting that the two agonists produce distinct active receptor conformations in vivo which likely lead to differential receptor trafficking.Together our data show that delta agonists retain full analgesic efficacy when receptors remain on the cell surface. In contrast, delta agonist-induced analgesia is abolished following receptor internalization, and complete behavioral desensitization is observed. Overall these results establish that, in the context of pain control, receptor localization fully controls receptor function in vivo. This finding has both fundamental and therapeutic implications for slow-recycling GPCRs

Lack of association between serological evidence of past Coxiella burnetii infection and incident ischaemic heart disease: nested case-control study

BACKGROUND: Coxiella burnetii causes the common worldwide zoonotic infection, Q fever. It has been previously suggested that patients who had recovered from acute Q fever (whether symptomatic or otherwise) may be at increased risk of ischaemic heart disease. We undertook this study to determine if past infection with Coxiella burnetii, the aetiological agent of Q fever, is a risk factor for the subsequent development of ischaemic heart disease. METHODS: A nested case-control study within the Prospective Epidemiological Study of Myocardial Infarction (PRIME). The PRIME study is a cohort study of 10,593 middle-aged men undertaken in France and Northern Ireland in the 1990s. A total of 335 incident cases of ischaemic heart disease (IHD) were identified and each case was matched to 2 IHD free controls. Q fever seropositivity was determined using a commercial IgG ELISA method. RESULTS: Seroprevalence of Q fever in the controls from Northern Ireland and France were 7.8% and 9.0% respectively. No association was seen between seropositivity and age, smoking, lipid levels, or inflammatory markers. The unadjusted odds ratio (95% CI) for Q fever seropositivity in cases compared to controls was 0.95 (0.59, 1.57). The relationship was substantially unaltered following adjustment for cardiovascular risk factors and potential confounders. CONCLUSION: Serological evidence of past infection with C. burnetii was not found to be associated with an increased risk of IHD

Broad Antiviral Activity of Carbohydrate-Binding Agents against the Four Serotypes of Dengue Virus in Monocyte-Derived Dendritic Cells

BACKGROUND: Dendritic cells (DC), present in the skin, are the first target cells of dengue virus (DENV). Dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) is present on DC and recognizes N-glycosylation sites on the E-glycoprotein of DENV. Thus, the DC-SIGN/E-glycoprotein interaction can be considered as an important target for inhibitors of viral replication. We evaluated various carbohydrate-binding agents (CBAs) against all four described serotypes of DENV replication in Raji/DC-SIGN(+) cells and in monocyte-derived DC (MDDC). METHODOLOGY/PRINCIPAL FINDINGS: A dose-dependent anti-DENV activity of the CBAs Hippeastrum hybrid (HHA), Galanthus nivalis (GNA) and Urtica dioica (UDA), but not actinohivin (AH) was observed against all four DENV serotypes as analyzed by flow cytometry making use of anti-DENV antibodies. Remarkably, the potency of the CBAs against DENV in MDDC cultures was significantly higher (up to 100-fold) than in Raji/DC-SIGN(+) cells. Pradimicin-S (PRM-S), a small-size non-peptidic CBA, exerted antiviral activity in MDDC but not in Raji/DC-SIGN(+) cells. The CBAs act at an early step of DENV infection as they bind to the viral envelope of DENV and subsequently prevent virus attachment. Only weak antiviral activity of the CBAs was detected when administered after the virus attachment step. The CBAs were also able to completely prevent the cellular activation and differentiation process of MDDC induced upon DENV infection. CONCLUSIONS/SIGNIFICANCE: The CBAs exerted broad spectrum antiviral activity against the four DENV serotypes, laboratory-adapted viruses and low passage clinical isolates, evaluated in Raji/DC-SIGN(+) cells and in primary MDDC

Dominique Py : Environnements interactifs d’apprentissage et démonstration en géométrie, HDR en informatique de l’université de Rennes I, 5 juillet 2001

Py Dominique. Dominique Py : Environnements interactifs d’apprentissage et démonstration en géométrie, HDR en informatique de l’université de Rennes I, 5 juillet 2001. In: Sciences et techniques éducatives, volume 8 n°3-4, 2001. Interaction homme-machine pour la formation et l'apprentissage humain, sous la direction de Elisabeth Delozanne et Pierre Jacobini. pp. 447-448

Informatique et limites de la planète : quelles implications pour l'EIAH ?

National audienceRecent research in Computing within limits studies the impact of ecological and energy boundaries on computer science. This paper examines how TEL research can address this emerging issue.Les travaux récents conduits en informatique dans des limites étudient l'impact des limites écologiques et énergétiques sur l'informatique. Cet article examine comment la recherche en EIAH peut aborder cette question émergente. Mots-clés. Limites, informatique de l'effondrement, adaptation, low-tech