@article {92226, title = {Whirligig beetles as corralled active Brownian particles.}, journal = {J R Soc Interface}, volume = {18}, year = {2021}, month = {04/2021}, pages = {20210114}, abstract = {

We study the collective dynamics of groups of whirligig beetles Dineutus discolor (Coleoptera: Gyrinidae) swimming freely on the surface of water. We extract individual trajectories for each beetle, including positions and orientations, and use this to discover (i) a density-dependent speed scaling like v \~{} ρ-ν with ν ≈ 0.4 over two orders of magnitude in density (ii) an inertial delay for velocity alignment of approximately 13 ms and (iii) coexisting high and low-density phases, consistent with motility-induced phase separation (MIPS). We modify a standard active Brownian particle (ABP) model to a corralled ABP (CABP) model that functions in open space by incorporating a density-dependent reorientation of the beetles, towards the cluster. We use our new model to test our hypothesis that an motility-induced phase separation (MIPS) (or a MIPS like effect) can explain the co-occurrence of high- and low-density phases we see in our data. The fitted model then successfully recovers a MIPS-like condensed phase for N = 200 and the absence of such a phase for smaller group sizes N = 50, 100.

}, doi = {10.1098/rsif.2021.0114}, author = {Devereux, HL and Twomey, CR and Turner, MS and Thutupalli, Shashi} } @article {36272, title = {Size-dependent recycling of membrane clusters}, journal = {EPL (Europhysics Letters)}, volume = {121}, year = {2018}, month = {03/2018}, abstract = {

The role of recycling in the control of membrane domains is a contentious issue and currently an open research question. In this context, we study the coarsening of strongly microphase-separated membrane domains in the presence of recycling of material. The dynamics of cluster size distribution is studied under both scale-free and size-dependent recycling. Closed-form solutions to the steady-state distribution and its associated moments are found in both cases. For the size-independent case, the time evolution of the moments is analytically obtained, providing exact results for their corresponding relaxation times. Since these moments and relaxation times are measurable quantities that may be determined by comparison with experimental data, our results provide a framework with which to understand and assess the interplay between membrane recycling and domain formation.

}, doi = {10.1209/0295-5075/121/58004 }, author = {Rautu, SA and Rowlands, G and Turner, MS} }