PhD project: Theory and Simulation of Microbial Swimmers and Subcellular Liquid Crystals

Project description

A new type of soft condensed matter, called 'active matter', arises in biological systems which continually convert one form of energy into another. Examples include subcellular networks of filaments and motors (the 'cytoskeleton'); and suspensions of swimming bacteria. Each contains self-propelled particles which tend to form ordered phases (the analogues of liquid crystals in conventional, passive materials). We have developed a range of simulation and theory tools to address these fascinating new materials. Models span from continuum descriptions of the new 'active liquid crystals' [1] to descriptions that resolve individual self-propelled particles with specified dynamical rules [2], coupled to fluid motion [3] or birth and death processes [4]. These models, reviewed in [5], can give new insights into subcellular physics and into pattern formation in the growth of bacterial colonies. This theoretical project offers exciting opportunities for (a) a student interested in large scale computational physics [1,3] and/or for (b) a student who wishes to combine relatively lightweight numerics with analytical modelling work [2,4].

[1] Shearing Active Gels Close to the Isotropic-Nematic Transition, M. E. Cates, S. M. Fielding, D. Marenduzzo, E. Orlandini and J. M. Yeomans, Physical Review Letters 101, 068102 (2008); Colloids in Active Fluids: Anomalous Microrheology and Negative Drag, G. Foffano, J. S. Lintuvuori, K. Stratford, M. E. Cates and D. Marenduzzo, Physical Review letters 109, 028103 (2012).

[2] Statistical Mechanics of Interacting Run-and-Tumble Particles, J.Tailleur and M. E. Cates, Physical Review Letters 100, 218103 (2008).

[3] Run and Tumble Particles with Hydrodynamics, R. W. Nash, R. Adhikari, J.Tailleur and M. E. Cates, Physical Review Letters 104, 258101 (2010).

[4] Arrested Phase Separation in Reproducing Bacteria Creates a Generic Route to Pattern Formation, M. E. Cates, D. Marenduzzo, I. Pagonabarraga and J. Tailleur, Proc. Nat. Acad. Sci. USA 107, 11715 (2010).

[5] Diffusive Transport without Detailed Balance in Motile Bacteria: Does Microbiology Need Statistical Physics?, M. E. Cates, Repts. Prog. Phys. 75, 042601 (2012).

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