Helen Ansell - Anomalous dynamics and nonlinear rheology in epithelial tissue models

Abstract: Epithelial tissues exhibit complex collective dynamics during processes such as collective cell migration and morphogenesis. Many aspects of this behavior are reminiscent of soft materials, motivating the use of coarse-grained geometric cell models as a minimal approach for probing their structure and dynamics. In this talk, I will focus on the response of these cell models under shear. At low shear stresses, we observe anomalous disordered dynamics that deviate from expectations in standard glassformers. At higher shear stresses, a rich array of nonlinear rheological features emerges, including shear thinning, shear thickening, and shear jamming. I will demonstrate how universal scaling can be used to characterize these different regimes, and discuss structural changes in the system as it shear jams. Finally, I will discuss the open questions these findings raise both in the physics of shear jamming and in the material response of in vivo tissues, pointing towards future directions in bridging understanding of soft matter physics and biological systems.

Biosketch: Dr. Helen Ansell is currently the Tarbutton Postdoctoral Fellow in the Physics Dept at Emory University.  She earned her PhD in Physics from UPenn in 2021 with a thesis entitled "Spiraling out of Disorder: Investigating the Behavior of Nematic Liquid Crystalline Systems and Soft Vortex Matter under Geometrical Confinement," with Randy Kamien. She then had a 2-year postdoctoral fellowship at Northwestern Univ with Istvan Kovacs. In 2023, she started her Tarbutton fellowship at Emory, working with Daniel Sussman. She uses theoretical and computational techniques to investigate emergent structural features in soft and biological materials. You can find Dr. Ansell's publications here.