Cell life-cycle processes such as growth, division and death, often all happen on a similar timescale, as do the resultant mechanical and dynamical responses of the cell assembly (such as a colony, biofilm or tissue). An archetypal example is E. Coli where growth, division and the subsequent relative motion of the daughter cells all happen at roughly the same rate. However there are also examples of another type of system showing abrupt processes, including `snapping' cell division in Actinobacteria and `explosive' bacterial lysis.

Here we test whether going from the first type of growth-dominated active matter system to the other by introducing a second fast timescale in one of the microscopic processes can affect the macroscopic mechano-dynamics, such as the homeostatic pressure[1]. Specifically we simulate a closed 1D channel of immotile cells that grow and divide to fill up the channel balanced by cell removal (via death or extrusion) when the active pressure[2] builds up. We focus on varying the timescale of the cell removal process, keeping growth and division timescales fixed. We show a clear distinction in the macroscopic system properties between  abrupt vs. gradual cell removal, such as a significant decrease in the homeostatic  pressure.

[1] M. Basan, T. Risler, J.-F. Joanny, X. Sastre-Garau, and J. Prost, “Homeostatic competition drives tumorgrowth and metastasis nucleation”, HFSP journal 3, 265–272 (2009).

[2]Y. Fily, Y. Kafri, A. P. Solon, J. Tailleur, and A. Turner, “Mechanical pressure and momentum conservationin dry active matter”, Journal of Physics A: Mathematical and Theoretical 51, 044003 (2017).