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UID:0-1078@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20251128T110000
DTEND;TZID=Europe/Paris:20251128T120000
DTSTAMP:20251121T174555Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-marc-lagoin/
SUMMARY:Physics-Biology Interface seminar: Marc Lagoin - Moyen Amphi\, Buil
 ding 510\, Université Paris-Saclay Orsay - 28 Nov 25 11:00
DESCRIPTION:Thermodynamics of Nonequilibrium Systems\, from Maxwell Demons 
 to Active Microswimmers in Confined Flows\nMarc Lagoin (LOMA\, U. Bordeaux
 )\n\nMany physical systems can be described using a few coarse variables\,
  ignoring most microscopic details. This idea\, formalized in Langevin’s
  theory of Brownian motion [3]\, allows us to understand how fluctuations 
 and dissipation produce predictable behaviours even in systems far from eq
 uilibrium.In this talk\, I will present two experiments that illustrate th
 is approach.\n\n\nFirst\, in a driven granular gas\, we built a macroscopi
 c version of a Feynman-type ratchet [4\,7] and measured how fluctuations c
 an be rectified to produce motion. This work is described in Ref. [2] and 
 provides a simple experimental test of stochastic models.Second\, we studi
 ed Chlamydomonas reinhardtii microswimmers in oscillatory Poiseuille flows
 . By tracking their motion\, we measured their long-time dispersion and in
 terpreted it using a coarse-grained Brownian-particle description [8]. Thi
 s leads to an active version of the classical Taylor–Aris dispersion [5\
 ,6]\, as shown in Ref. [1].\n\n\nThese two studies show that simple stocha
 stic descriptions can help in understanding the behaviour of nonequilibriu
 m systems\, from macroscopic mechanical devices to suspensions of active m
 icroorganisms.\n\n\nM.Lagoin\, J. Lacherez\, G. de Tournemire\, A. Badr\, 
 Y. Amarouchene\, A. Allard\, and T. Salez\, Enhanced dispersion of active 
 microswimmers in confined flows\, PNAS (2025)\; arXiv:2507.08369.\nM. Lago
 in\, C. Crauste-Thibierge\, A. Naert\, A human-scale Brownian ratchet\, Ph
 ys. Rev. Lett. (2022)\; HAL: hal-03650213.\nP. Langevin\, Sur la théorie 
 du mouvement brownien\, C. R. Acad. Sci. (1908).\nR. P. Feynman\, The Feyn
 man Lectures on Physics\, Vol. I\, Ch. 46: Ratchet and Pawl (1964).\nG. I.
  Taylor\, Dispersion of soluble matter in solvent flowing slowly through a
  tube\, Proc. R. Soc. A (1953).\nR. Aris\, On the dispersion of a solute i
 n a fluid flowing through a tube\, Proc. R. Soc. A (1956).\nM. von Smoluch
 owski\, early works on fluctuation-induced transport (1912).\nH. Risken\, 
 The Fokker–Planck Equation: Methods of Solution and Applications.\n
CATEGORIES:physbio,seminars
LOCATION:Moyen Amphi\, Building 510\, Université Paris-Saclay Orsay\, 15 R
 ue Georges Clemenceau\, orsay\, France
GEO:48.698187;2.181768
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  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=Moyen Amphi\, Building 510\, Un
 iversité Paris-Saclay Orsay:geo:48.698187,2.181768
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