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Rencontre autour de la physique : A la découverte de la supraconductivité
...UNE CONFERENCE « CENTENAIRE DE LA SUPRACONDUCTIVITE » par Dimitri RODITCHEV, Directeur de recherche, membre de l’Institut des NanoSciences de Paris, responsable de l’équipe « dispositifs quantiques contrôlés : nanofabrication propriétés... Voir la vidéole (44m9s)
Action recognition from video: some recent results
While recognition in still images has received a lot of attention over the past years, recognition in videos is just emerging. In this talk I will present some recent results. Bags of features have demonstrated good performance for action recognition in videos. We briefly review the underlying principles and introduce trajectory-based video features, which have shown to outperform the state of the art. These features are obtained by dense point sampling in each frame and tracking them based on displacement information from a dense optical flow field. Trajectory descriptors are obtained from motion boundary histograms, which are robust to ... Voir la vidéole (48m54s)
Introduction to Kernelization
Preprocessing or data reductions means reducing the input to something simpler by solving an easy part of the input and this is the type of algorithms used in almost every application. In spite of wide practical applications of preprocessing, a systematic theoretical study of such algorithms remains elusive. The framework of parameterized complexity can be used as an approach to analyse preprocessing algorithms. Input to parameterized algorithms include a parameter (in addition to the input) which is likely to be small, and this resulted in a study of preprocessing algorithms that reduce the size of the input to a ... Voir la vidéole (1h7m16s)
Réseaux d'automates: trente ans de recherche
Ma complicité avec ce sujet date de longtemps, pas tout à fait assez pour dire que j’y étais depuis le début, mais quand même.... Ainsi, je vais vous raconter comment on a obtenu, aux alentours de l'année 1979, les premiers résultats mathématiques sur la dynamique de ce qui s’appelle aujourd'hui les réseaux de neurones artificiels et qui font aujourd’hui partie du cursus classique de toute école d’ingénieurs. Puis, le succès de ces résultats m’a amené, à partir d’une étrange lettre que j’ai reçue au début de vacances à Grenoble, à me passionner pour les fourmis. Je suis quand même ... Voir la vidéole (53m2s)
Mathematical models for the cardiovascular system
Mathematical models for the cardiovascular system: analysis, numerical simulation, applications The role of mathematics in understanding and simulating fluid dynamics and biochemical processes in the physiological and pathological functioning of the human cardiovascular system is becoming more and more crucial. These phenomena are indeed correlated with the origin of some major cardiovascular pathologies, and influence the efficacy of the treatments to heal the arteries from their diseases. Mathematical models allow the description of the complex fluid-structure interaction which govern the artery wall deformation under the pressure pulse. Moreover, appropriate reduction strategies can be devised to allow for an ... Voir la vidéole (1h3m13s)
Graphes, hypergraphes et réseaux (série : Colloquium Jacques Morgenstern)
Le but de la conférence est d'exposer des problèmes simples de conception de réseaux qui m'ont intrigués pendant de nombreuses années et continuent de m'intriguer. Les réseaux de télécommunications mais aussi les réseaux routiers ou sociaux se modélisent bien avec des graphes. Les sommets représentent les routeurs (abonnés, villes, individus...) et les arêtes des liaisons ou des relations. Je partirai d'un problème simple à énoncer mais difficile à résoudre : comment construire des réseaux (graphes) de degré et de diamètre donnés. J'essaierai de montrer l'imagination débordante dans les outils utilisés (géométries finies, graphes probabilistes, groupes, constructions récursives, constructions sur alphabets, ... Voir la vidéole (1h1m43s)
Competition and Cooperation
Numerous applications of economics are based on models that assume individual economic actors take prices as given. Indeed, this assumption underlies many empirical studies. The question of whether such an assumption can be justified as arising in the context of individual and group optimizing behavior has been the subject of extensive investigation.One answer to the question originates with the work of Edgeworth (1881), which argues that groups individuals cannot improve upon their part of a price-taking economic equilibrium by cooperation, that is, the set of outcomes that are stable against collective activities of groups – the core-- is equivalent to ... Voir la vidéole (58m54s)
Swarms: First Class Citizens in the Future Internet (série : Colloquium Jacques Morgenstern)
The current Internet consists of tens of thousand different interconnected autonomous networks. It was designed to support large populations of point-to-point content transfers. This introduces considerable headaches due imbalances in traffic flows, which has the effect of complicating network management, reducing the robustness of the Internet, and reducing user performance. In this talk, I review the sources of traffic in the Internet over the last 20 years. We will observe that this an increasing fraction of traffic was generated by peer-to-peer (P2P) "swarm" technology from 2000 to 2007. I examine how and why P2P swarm technology simplifies network management, ... Voir la vidéole (55m20s)


