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SUMMARY:Emergence of defect motility in pulsating active matter - Luca  Ca
 sgrande (Université du Luxembourg)
DTSTART:20250911T144000Z
DTEND:20250911T144500Z
UID:TALK233365@talks.cam.ac.uk
DESCRIPTION:When heartbeats become irregular due to tachycardia or fibrill
 ation\, spiral waves and motile defects emerge at the surface of cardiac t
 issues. Capturing the emergence of such defects in confluent tissues witho
 ut any cellular flow is a theoretical challenge which has recently been ta
 ckled by models of actively deforming particles. In dense assemblies where
  particles are subject to an individual pulsation of their sizes\, the int
 erplay between synchronization and repulsion can produce deformation waves
  resembling those observed in cardiac tissues. Combining particle-based an
 d hydrodynamic approaches\, we examine the statistics of defects in the co
 llective deformation of particles. We rationalize the emergence of defect 
 motility\, despite the absence of any microscopic self-propulsion\, as ste
 mming from the breakdown of time-reversal and spatial symmetries. Specific
 ally\, we provide analytical predictions for the deformation profile near 
 the defect core to quantify the angular and translational velocities of de
 fects. These results lead to identify the dominant topological mechanism u
 nderlying some transitions between deformation patterns in contractile tis
 sues\, with broader implications for understanding similar phenomena in ot
 her active systems.
LOCATION:External
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