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Séminaires Invités

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Séminaires donnés par des invités extérieurs au LIPhy.

Ce sont des séminaires généraux qui s’adressent à tous les membres du LIPhy. Par conséquent, l’introduction, la plus large possible, y joue un rôle important.

Les séminaires durent environ 1heure dont 15mn accordées aux questions. Ils ont lieu les lundis à 14h, en salle de conférence du laboratoire au deuxième étage. La langue des séminaires est en général l’anglais.

L’accès au laboratoire peut-être obtenu en contactant le secrétariat Nadine D’Andréa ou Chantal Reignier par l’intercom à l’entrée principale.


  • Lundi 25 octobre 14:00-15:30 - Hugo Perrin - TU Delft

    Dense suspensions : hysteresis and finite-size effects.

    Résumé : Dense amorphous media close to the solid-liquid transition present a rich phenomenology such as hysteresis, finite-size, or nonlocal effects and dilatancy. Understanding these phenomena is a major challenge to describe the flow of granular media, foams, or soft glassy materials. It is also important in geophysics to comprehend the occurrence of earthquakes, landslides or avalanches. In those experimental studies, we developed a model granular system in which it is experimentally possible to tune, and even eliminate, solid friction between grains. This system allow for the first time to identify the origin of hysteresis and finite-size effects. On the one hand, we showed that interparticular friction is the key ingredient for hysteresis and leads to a velocity-weakening rheology ( On the other hand, our recent experimental study of finite-size effects on avalanche angle evidence that they do not cause hysteresis but reflect the jamming criticality in frictionless granular flows. ( These results challenge previous interpretations and could lead to new theoretical models based on the physics at the particle scale.

    Contact : Romain Lhermerout

  • Lundi 8 novembre 11:00-12:30 - Eric Dufresne - Department of Materials, ETH Zürich

    Séminaire LIPhy

  • Mardi 9 novembre 14:00-15:30 - Michel Cloitre - MMC, ESPCI

    Séminaire LIPhy

    Résumé : Contact : Romain Mari

  • Lundi 15 novembre 14:00-15:30 - Yusuke Suenaga - Department of Molecular Carcinogenesis, Chiba Cancer Centre Research Institute, Japan

    Functional and structural characterization of de novo evolved proteins

    Résumé : New coding genes that evolved from the non-genic region are called de novo evolved genes, which encode functional proteins in taxonomically restricted species and characterize their lineage/species-specific phenotypes. In contrast to new genes that originated from pre-existing genes by duplication, de novo genes do not have known functional motifs or domains and show random-like amino acid sequences. We have previously found that NCYM, an antisense gene of the oncogene MYCN, encodes a de novo evolved gene product that stabilizes MYCN and promotes metastasis of neuroblastoma, a human pediatric tumor. Since NCYM is registered in the database as a non-coding RNA, it is possible that there are many unknown de novo evolved genes that are misclassified as non-coding RNAs. Therefore, there is a need to identify new factors that determine the coding potential.
    Recently, we discovered a mathematical structure that distinguishes non-coding RNAs from coding RNAs, which we named the PTI (potential translated island) score. This PTI score can be uniquely calculated from RNA sequences, and when calculated for all human transcripts, the relationship with coding potential was approximated by a linear function passing through the origin. Human noncoding RNAs with high coding potential were predicted to be associated with cerebral development and cancer. Furthermore, we calculated more than 3.4 million transcripts of 100 species and found that PTI is commonly associated with coding potential in cellular organisms.
    To investigate the relationship between structure and function of de novo evolved proteins, we analyzed the secondary structure of NCYM by vacuum ultraviolet circular dichroism and identified the amino acids involved in MYCN stabilization. These results suggest that the combination of structural and evolutionary analyses of de novo proteins is useful for elucidating the mechanism of new gene birth.
    Contact : Judith Peters

  • Lundi 22 novembre 14:00-15:30 - Amélie Chardac - Lab. Physique ENS Lyon

    Life and death of topological defects in polar active matter

    Résumé : Active-matter physics describes the mesmerizing dynamics of interacting motile bodies : from bird flocks and cell colonies, to collections of synthetic units independently driven far from equilibrium. When motile units self-assemble into flocks where all particles propel along the same direction, they realize one of the most robust ordered phase observed in Nature. But, after twenty five years of intense research the very mechanism controlling the ordering dynamics of both living and artificial flocks has remained unsettled.
    In this talk, building on model experiments based on Quincke rollers, I will first explain how a flock suppresses its singularities to form an ordered spontaneous flow. Combining experiments, simulations and theory I will show how to elucidate the elementary excitations of 2D polar active matter and explain their phase ordering dynamics as a self-similar process emerging from the annihilation of +/- 1 defects along a filamentous network of domain walls with no counterparts in passive systems (
    In a second part, I will address the robustness of long range order and discuss the stabilization of topological defects in a polar active fluid through disordered media. Combining experiments and theory, I will show that colloidal flocks collectively cruise through disorder without relaxing the topological singularities of their flows, unlike in pure systems. Introducing colloidal flocks in micro patterned circular chambers, we reveal a state of strongly disordered active matter with no counterparts in equilibrium : a dynamical vortex glass. The resulting state is highly dynamical but the flow patterns, shaped by a finite density of frozen vortices, are stationary and exponentially degenerate (
    Contact : Salima Rafai

  • Lundi 29 novembre 14:00-15:30 - Florent Gimbert - IGE Grenoble

    Séminaire LIPhy

    Résumé : Contact : Romain Mari

    Notes de dernières minutes :

  • Lundi 6 décembre 14:00-15:30 - Sylvain Patinet - PMMH, ESPCI

    Séminaire LIPhy

    Résumé : contact : Romain Mari

  • Lundi 13 décembre 14:00-15:30 - Adrien Bussonnière - MSC. Univ. Paris / CNRS

    Séminaire LIPhy

    Résumé : Contact : Benjamin Dollet

  • Lundi 17 janvier 2022 14:00-15:30 - Ramiro Gaudoy-Diana et Benjamin Thiria - PMMH, ESPCI

    Séminaire LIPhy

    Résumé : Contact : Aurélie Dupont / Philippe Peyla

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  • Mercredi 10 novembre 14:00-17:30 - Nicolas Cuny

    PhD Nicolas Cuny

    Résumé : Dérivations de modèles constitutifs : de la microstructure à la rhéologie des suspensions denses molles
    Jury :

    • Madame Catherine Barentin, Professeur Université Lyon 1
    • Monsieur Ludovic Berthier, Directeur de Recherche CNRS, Université de Montpellier
    • Monsieur Michel Cloitre, Directeur de Recherche CNRS, ESPCI Paris
    • Monsieur Vincent Démery, Maître de conférence, ESPCI Paris
    • Monsieur Pierre Saramito, Directeur de Recherche CNRS, Université Grenoble-Alpes
    • Monsieur Gilles Tarjus, Directeur de Recherche CNRS, Sorbonne Université

    Lieu : Salle de conférence LIPhy

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