ESPCI web site
Le séminaire hebdomadaire du laboratoire PMMH a lieu tous les vendredis à 11h, au premier étage Barre Cassan, campus Jussieu (plan).
Stéphane Perrard
Etienne Reyssat
Virgile Thiévenaz
PMMH
BARRE CASSAN
BAT A 1ER ETAGE CASE 18
7 QUAI SAINT BERNARD
75005 PARIS
France
Tel : (33) 1 40 79 45 22
Fernando Peruani (Université de Nice)
Quasi-long range order and sub-diffusion in systems of active particles in heterogeneous media
The rapidly expanding study of active particles has focused so far almost exclusively, theoretically as well as experimentally, on the statistical description of particle motion in idealized, homogeneous spaces. However, the great majority of natural active particle systems takes place, in the wild, in heterogeneous media : from active transport inside the cell, which occurs in a space that is filled by organelles and vesicles, to bacterial motion, which takes place in highly heterogeneous environments such as the soil or complex tissues such as in the gastrointestinal tract. I will show that the presence of spatial heterogeneities brings new physics unseen in homogeneous systems at the level of the transport properties and collective dynamics of such systems. I will show first that a random distribution of “obstacles” can lead to spontaneous trapping of active particles. Such “obstacles” represent undesirable areas that the active particles avoid and may correspond to a source of a repellent chemical, a light gradient, or whatever threat sensed by the moving particles. Inside traps, active particles exhibit a vortex-like motion and remain arbitrary long times. Particle motion then becomes genuinely sub-diffusive. We also find that the presence of such obstacles has a dramatic effect on the collective dynamics of usual self-propelled particle systems. In particular, we observe : i) the existence of an optimal (angular) noise amplitude that maximizes collective motion, and ii) quasi-long range order and the existence of two critical points.
This collection of results opens a new perspective for the design and control of active particle systems.
References :
- O. Chepizhko, E. Altmann, F. Peruani, PRL 110, 238101 (2013)
- O. Chepizhko, F. Peruani, (to appear in PRL) (2013)
Séminaires (4)
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Séminaire PMMH - Francesca Borghi Università degli Studi di Milano
Vendredi 20 juin de 11h00 à 12h00 - Salle réunion PMMH 1
REPROGRAMMABLE HARDWARE FOR DATA PROCESSING AT THE EDGE : A NEW COMPUTING PARADIGM BASED ON NEUROMORPHIC SYSTEMS
The brain's ability to perform efficient and fault-tolerant data processing is strongly related with its peculiar interconnected adaptive architecture, based on redundant neural circuits interacting at different scales. By emulating the brain's processing and learning mechanisms, computing technologies strive to (…) -
Séminaire PMMH - Francesca Borghi Università degli Studi di Milano
Vendredi 20 juin de 11h00 à 12h00 - Salle réunion PMMH 1
REPROGRAMMABLE HARDWARE FOR DATA PROCESSING AT THE EDGE : A NEW COMPUTING PARADIGM BASED ON NEUROMORPHIC SYSTEMS
The brain's ability to perform efficient and fault-tolerant data processing is strongly related with its peculiar interconnected adaptive architecture, based on redundant neural circuits interacting at different scales. By emulating the brain's processing and learning mechanisms, computing technologies strive to (…) -
Séminaire PMMH - Salvatore Federico (University of Calgary, Canada)
Vendredi 4 juillet de 11h00 à 12h00 - Salle réunion PMMH 1
Continuum Mechanics of Hydrated Fibre-Reinforced Soft Tissues
Biological tissues can be represented as bi-phasic continua, with a porous solid phase saturated by an interstitial fluid and reinforced by collagen fibers. This lecture will give an overview of the modelling techniques for fibre-reinforced porous composite materials with statistical orientation of the fibers. Both (…) -
Séminaire PMMH - Salvatore Federico (University of Calgary, Canada)
Vendredi 4 juillet de 11h00 à 12h00 - Salle réunion PMMH 1
Continuum Mechanics of Hydrated Fibre-Reinforced Soft Tissues
Biological tissues can be represented as bi-phasic continua, with a porous solid phase saturated by an interstitial fluid and reinforced by collagen fibers. This lecture will give an overview of the modelling techniques for fibre-reinforced porous composite materials with statistical orientation of the fibers. Both (…)
Instructions générales pour les conférenciers
Le public du séminaire est très hétérogène (rien qu’au PMMH nous travaillons sur des thématiques très diverses, mécanique des fluides, des milieux granulaires, des solides, physique statistique, physique du mouillage, micro-fluidique, biophysique,...) l’objectif est donc de ne pas faire un séminaire trop spécialiste : au moins la première moitié du séminaire à un niveau accessible pour celui qui ne connaît rien sur le sujet.
Le séminaire a lieu à 11h. rendez-vous 15 minutes avant pour installer et tester la projection.
Le séminaire dure environ 45 minutes pour laisser un peu de temps pour discuter à la fin.
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- Séminaire de Mécanique d’Orsay (page web LIMSI)
- Séminaire de Mécanique des Fluides de l’Institut Jean le Rond d’Alembert
- Séminaires du laboratoire MSC, Paris VII
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