Nonlinear Rheology in a Model Biological Tissue
  Mechanical signaling plays a key role in biological processes like embryo development and cancer growth. One prominent way to probe mechanical properties of tissues is to study their response to externally applied forces. Using a particle-based model featuring random apoptosis and environment-dependent division rates, we evidence a crossover from linear flow to a shear-thinning regime with increasing shear rate. To rationalize this non-linear flow we derive a theoretical mean-field scenario that accounts for the interplay of mechanical and active noise in local stresses. These noises are respectively generated by the elastic response of the cell matrix to cell rearrangements and by the internal activity. 
D. A. Matoz-Fernandez, Elisabeth Agoritsas, Jean-Louis Barrat, Eric   Bertin and Kirsten Martens
cond-mat.soft cond-mat.other cond-mat.stat-mech physics.bio-ph