BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//wp-events-plugin.com//6.4.7.2//EN
TZID:Europe/Paris
X-WR-TIMEZONE:Europe/Paris
BEGIN:VEVENT
UID:1-396@lptms.universite-paris-saclay.fr
DTSTART:20160125T110000Z
DTEND:20160125T121500Z
DTSTAMP:20160114T121537Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-denis-grebenkov/
SUMMARY:Physics-Biology interface seminar: Denis Grebenkov - LPTMS\, salle 
 201\, 2ème étage\, Bât 100\, Campus d'Orsay - 25 Jan 16 11:00
DESCRIPTION:Inferring anomalous diffusion from single particle trajectories
 \nDenis Grebenkov (PMC\, École polytechnique)\nSPECIAL LOCATION\nTranspor
 t of macromolecules\, organelles and vesicles in living cells \nis a very 
 complicated process that essentially determines and controls \nmany bioche
 mical reactions\, growth and functioning of cells. The passive \nthermal d
 iffusion through the overcrowded cytoplasm is combined with \nthe active t
 ransport by motor proteins attached to microtubules. This \nintricate mech
 anism results in anomalous diffusions that found abundant \nexperimental e
 vidences but no consensus on the physical mechanism and \nthe appropriate 
 mathematical model is achieved so far. Single-particle \ntracking (SPT) ex
 periments survey random trajectories of individual \ntracers inside living
  cells and can thus provide the missing information \non the intracellular
  transport in order to discriminate between different \nphysical mechanism
 s and to identify the appropriate theoretical model \nof anomalous diffusi
 on. In SPT\, an ensemble average of the quantities \nof interest (e.g.\, d
 iffusivity\, viscosity\, first passage times\, etc.) \nis often unavailabl
 e or even undesired\, as tracers move in spatially \nheterogeneous and tim
 e evolving media such as living cells. One faces \ntherefore a challenging
  problem of inferring dynamical\, structural and \nfunctional properties o
 f living cells from a limited (small) number of \nindividual random realiz
 ations of an unknown stochastic process.\nAfter a short introduction to th
 eoretical aspects of the intracellular\ntransport\, we discuss the recent 
 progress onto probing ergodicity of\nthe tracer dynamics from a single par
 ticle trajectory. The proposed \nestimators are first investigated for sev
 eral models of anomalous \ndiffusion.  In the case of nonergodic continuou
 s time random walks\, \nwe show analytically that both estimators do not v
 anish even for \ninfinitely long trajectories.  The estimators are then ap
 plied to \ntwo sets of earlier published trajectories: mRNA molecules insi
 de \nlive E. coli cells and Kv2.1 potassium channels in the plasma membran
 e.\nThese tests suggest that the former set exhibits ergodic behavior\nwhi
 le the latter reveals both ergodic and nonergodic features.
CATEGORIES:physbio,seminars
LOCATION:LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay\, 15 
 Rue Georges Clemenceau\, Orsay\, 91405\, France
GEO:48.698185;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  Orsay\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS\, salle 201\, 2è
 me étage\, Bât 100\, Campus d'Orsay:geo:48.698185,2.181768
END:VEVENT
END:VCALENDAR