Séminaire fluide: Samuel BELL (LJP, Paris)

Biological systems leave traces of their passage through an environment. The traces may be chemical (the pheremones that allow ants to form trails), or physical (a rabbit's footprints), but in each case these traces encode information about a system's previous state into the environment. Crucially, these traces may then provide a stimulus to other agents in the system, leading to non-trivial dynamics. One example of this can be seen in the dynamics of cancer-associated fibroblasts. Cancer-associated fibroblasts lay down fibronectin, a fibrous protein, and form capsules around tumours, compressing them, and changing the tumour microenvironment. The laying down of fibronectin leads to a slowdown of the fibroblasts' dynamics, which may have implications in cancer progression. In this talk, I will develop an active field theory to show how a reciprocal coupling between fibroblasts and fibronectin can explain this freezing. I will then discuss more general considerations that arise from considering such a class of field theories: the transition from disorder to order, the transition from order to flow, and the possibility of non-reciprocal interactions.