Dresden 2017 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 46: Active Matter II (Joint Session DY/BP/CPP)

BP 46.8: Vortrag

Donnerstag, 23. März 2017, 11:45–12:00, HÜL 186

Defect dynamics in topological active matter — •Axel Voigt and Francesco Alaimo — Institute für Wissenschaftliches rechnen, TU Dresden

If active systems are confined on curved surfaces, topological constraints strongly influence the emerging spatiotemporal patterns. Using these topological constraints to guide collective cell behavior might be a key in morphogenesis and active nematic films on surfaces have been proposed as a promising road to engineer synthetic materials that mimic living organisms. Recent experiments consider an active nematic film of microtubules and molecular motors encapsulated within a lipid vesicle. As in passive systems the mathematical Poincare-Hopf theorem forces topological defects to be present in the nematic film. On a spherical vesicles this leads to an equilibrium defect configuration with four +1/2 disclinations arranged as a tetrahedron. In active systems unbalanced stresses drive this configuration out of equilibrium. But in contrast to planar active nematics with continuous creation and annihilation of defects the creation of additional defect pairs can be suppresses on curved surfaces. This led to the discovery of a tunable periodic state that oscillates between the tetrahedral and a planar defect configuration. We confirm this finding by computer simulations. For non-constant Gaussian curvature constraints local geometric properties can be used to control defect dynamics. We are concerned with a systematic investigation of the impact of such constraints on the emergence of complex patterns and oscillations.