Prochainement

Jeudi 13 décembre 14:00-15:00 Christopher Shirley (LJLL)
Propriétés de transport des opérateurs de Schrödinger stationnaires à petit désordre

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Lieu : IMO, Salle 3L8

Résumé : Dans cet exposé, je reviendrai dans un premier temps sur les liens entre le spectre des opérateurs de Schrödinger et les propriétés de transport ainsi que sur la conjecture d’Anderson. Dans un second temps, nous verrons comment nous pouvons obtenir des résultats de transport ballistique jusqu’à des temps qui dépendent du désordre et du type de stationnarité en développant une théorie spectrale approchée.

Propriétés de transport des opérateurs de Schrödinger stationnaires à petit désordre  Version PDF

Passés

Jeudi 29 novembre 14:00-15:00 Benjamin Mauroy  (Université de Nice)
Natural selection of lung’s geometry

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Lieu : IMO, Salle 3L8

Résumé : Mammals’ lung is an organ that transports ambient air to and from the air/blood interface, where exchanges of oxygen and carbon dioxide take place. This interface is large, about one hundred square meters in humans, and folded into the thoracic cage. To reach it, the lung’s geometry is shaped as a dichotomous tree. Each branch of that tree is a tube where air is flowing, and each leaves of the tree feeds a portion of the air/blood interface. Successive internalisations and externalisation of a volume of air allow to perform an efficient lung’s ventilation.
During this talk, we will focus more specifically on lung’s geometry : we will see how the use of a wide spectra of modelling and mathematical approaches can bring important insights on why and how lung’s geometry could have been selected. We will first show how the efficiency of its function as an organ is related to its geometry, next we will discuss lung’s development, before linking the two into a global and plausible scenario of lung’s geometry selection by evolution.

Natural selection of lung’s geometry  Version PDF

Jeudi 22 novembre 14:00-15:00 Ping Zhang  (Chinese Academy of Science)
Global solutions of 3D Navier-Stokes system with small unidirectional derivative

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Lieu : IMO, Salle 3L8

Résumé : We prove that as long as  | \partial_3 u_0 |_{H^{-\frac12,0}} is sufficiently small, then the 3D Navier-Stokes system with initial data  u_0 has a unique global solution.

Global solutions of 3D Navier-Stokes system with small unidirectional derivative  Version PDF

Jeudi 15 novembre 14:00-15:00 Masayasu Mimura  (Musashino University and Meiji University, Tokyo)
Model-aided understanding of the Neolithic transition from farmers to hunter-gatherers in Europe

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Lieu : IMO, Salle 3L8

Résumé : The Neolithic transition began the spread of early agriculture throughout Europe through interactions between farmers and hunter-gatherers about 10,000 years ago. Archeological evidence produced by radiocarbon dating indicates that the expanding velocity of farming is roughly constant all over Europe. Theoretical understanding of such evidence has been performed from mathematical modeling viewpoint. We propose a new model of reaction-diffusion type which consists of two different types of farmers (sedentary and migratory) and hunter-gatherers from the viewpoint of the influence of farming technology. In this talk, the relation between the expanding velocity of farmers and the farming technology us discussed.
The analysis of the model has been jointly working with J. Elias (Univ. Graz), D. Hilhorst (Paris Sud Univ.), M. H. Kabir (Jahangirnagar Univ.), Y. Morita (Ryukoku Univ.) and J. C. Tsai (National Tsing Hua Univ.).

Model-aided understanding of the Neolithic transition from farmers to hunter-gatherers in Europe  Version PDF