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BEGIN:VEVENT
UID:1-399@lptms.universite-paris-saclay.fr
DTSTART:20151214T110000Z
DTEND:20151214T120000Z
DTSTAMP:20151130T182904Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-etienne-fodor/
SUMMARY:Physics-Biology interface seminar: Étienne Fodor - Moyen Amphi\, B
 uilding 510\, Université Paris-Saclay Orsay - 14 Déc 15 11:00
DESCRIPTION:Tracking nonequilibrium physics in living systems\nÉtienne Fod
 or (Université Paris-Diderot)\nLiving systems operate far from equilibriu
 m due to the continuous injection of energy provided by ATP supply. The dy
 namics of the intracellular components is driven by both thermal equilibri
 um fluctuations and active stochastic forces generated by the molecular mo
 tors. Tracer particles are injected in living cells to study these fluctua
 tions. Alternatively\, vesicles which are already present in the cytoplasm
  serve as probes of the intracellular dynamics.\nTo sort out genuine noneq
 uilibrium fluctuations from purely thermal effects\, we combine passive an
 d active microrheology methods. They consist in measuring the spontaneous 
 tracer fluctuations and extracting the response from an external oscillato
 ry perturbation. By testing the fluctuation-dissipation theorem\, we quant
 ify the deviation from equilibrium appearing at low frequency. Removing th
 e thermal contribution in the tracer fluctuations\, we estimate the spectr
 um of the active forces. Eventually\, we report  non-Gaussian tails in the
  tracer displacement distribution as a result of  directed motion events.\
 nWe recapitulate theoretically the observed fluctuations by modeling the d
 ynamics with a confining harmonic potential which experiences random burst
 s as a result of motor activity [1]. This minimal model allows us to quant
 ify the time and length scales of the active forces\, along with the energ
 y scale injected by the ensuing fluctuations [2\, 3]. Finally\, we estimat
 e the energy dissipated by the tracers in the surrounding environment\, le
 ading us to define an efficiency of the energy conversion driving the trac
 er dynamics [4].\n\nReferences\n\n	[1] É. Fodor et al.\, Phys. Rev. E 90\
 , 042724 (2014)\n	[2] É. Fodor et al.\, EPL 110\, 48005 (2015)\n	[3] W. W
 . Ahmed et al.\, arXiv:1510.08299 \n	[4] É. Fodor et al.\, arXiv:1511.009
 21\n\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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