Dresden 2017 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 25: Posters - Cytoskeletal Filaments

BP 25.6: Poster

Dienstag, 21. März 2017, 14:00–16:00, P2-EG

Derivation of continuous equations for an isotropic active elastic network — •Karin John and Eric Bertin — Laboratoire Interdisciplinaire de Physique Grenoble, France

The standard active gel theory postulates phenomenological continuous equations for the density, stress, and local orientation fields on the basis of symmetry and linear irreversible thermodynamics arguments. In most cases, the gels considered behave as liquids on long time scales, but 'solid' active gels, which do not flow at long time under an externally applied shear, have also been studied. In this work, we derive the large-scale continuous description of an isotropic elastic network in the presence of force dipoles (a crude modeling of an actin network with molecular motors) which generate an active stress. The main results of this explicit coarse-graining procedure are two-fold. First, the derivation yields non-linear terms able to saturate the instability reported in linear active gel theory. Second, activity (i.e., the strength of force dipoles) not only generates new 'active' terms with respect to the passive case, but also 'renormalizes' the passive elastic properties of the medium. This change of the elastic properties leads to an instability for extensile force dipoles, while standard active gel theory yields an instability for contractile dipoles.