Polymers driven by helical filaments

To understand how cells swim in vivo we need to study how polymer-based biofluids respond to the high-shear beating of a flagellum. We have conducted Brownian Dynamics simulations of a model flagellum hydrodynamically coupled to polymers of various size and have found that the polymers are stretched out and drawn inwards towards the rotating helical filament. Using techniques from stochastic thermodynamics we can use our findings conclude that the average work required to maintain a constant rotation rate must increase in a dilute suspension of polymers. This has implications for organisms which must constantly convert chemical energy in order to move through their viscoelastic surroundings.

Statistical mechanics of ferromagnetic Janus-rods

With collaborators in the Aarts Group from the Physical and Theoretical Chemistry Laboratory, I have studied an interesting ‘hopping transition’ that occurs in a ferromagnetic colloidal rod in the presence of a static external field. In our paper (Phys. Rev. Lett. 115, 248301) we show how this effect is entropic in nature and discuss how it arises due to a loss of degree of freedom similar to the classical mechanical effect known as gimbal-lock.

Vortex rings in polariton superfluids

I conducted my MPhys thesis project under M. Szymanska studying the optical parametric oscillation (OPO) phase of a 2-dimensional quantum fluid of polaritons –- coherent superpositions of excitons and microcavity photons. We discovered that when driven by a pump with radial currents, the fluid is unstable to the spontaneous breaking of circular symmetry and a steady ‘ring’ of vortices forms, imparting a persistent discrete net angular momentum on the fluid (EPL (Europhysics Letters), 110, 5).

Energy and entropy in artifical chemistries

I was awarded a national scholarship at the York Centre for Complex Systems Analysis to conduct a summer research project under Prof. Susan Stepney (computer science) and Dr Angelika Sebald (chemistry) in the field of artificial life. In this project I devised and implemented a toy model of an artificial chemistry which incorporates ideas from statistical mechanics and applies these to ‘molecules’ comprised of random boolean networks. We found that our minimal model was sufficient to reproduce chemical processes such as autocatalysis and primitive metabolic cycles –complex processes usually associated with the formation life.