Browsing by Author "Álvarez Murphy, Fidel Gerardo"

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    Growth Dynamics in a Mechanical Model of Cellular Colonies
    (2024) Álvarez Murphy, Fidel Gerardo; Düring, Gustavo; Pontificia Universidad Católica de Chile. Instituto de Física
    Cellular colonies are structures of microorganisms that remain attached toeach other and/or to a surface. To study the effects of mechanical stress on thedynamics of a growing colony, a minimal discrete physical model of these cellu-lar systems is proposed considering only microscopic quantities from mechanicalforces, and a cell growth and division process. Using simulations that model thediscrete model evolution, macroscopic dynamics of contact and growth withinnon-motile circular-shaped cell colonies are successfully reproducible. To find alink between the microscopic quantities involved in the dynamics and the macro-scopic observables, an out-of-equilibrium continuum theory is developed.Theobserved dynamics in the discrete model are accurately described by the contin-uum theory at the mesoscopic limit, describing along the colony the existenceof maximum inner pressure and velocity as a function of microscopic quantities.Particularly, a constitutive relation between velocity and inter-particle overlapis found, describing that the growth dynamics of a colony are equivalent in twospatial configurations: a free and a channel-limited expansion. As a second partof this work, given the dynamics of the system, a competitive genetic surfingdynamic is studied considering two different cell strains in the channel-limitedconfiguration. The observed genetic surf shows a frequency distribution of domi-nance between strains that transits from an exponential law with exponent ´3{2to a log-normal distribution depending on the initial strain relative proportionand the channel width, suggesting that this system’s competitive dynamics canbe described by mean-field theories that describe growth processes.