Physics Viewpoint!

viewpoint_synchrony

Together with Idan Tuval, I have been recently working on a Viewpoint for Physics, about an interesting recent PRL publication by Greta Quaranta, Marie-Eve Aubin Tam and Daniel Tam, from the University of Delft. They proved that flagellar synchronisation in Chlamydomonas depends on the presence of striated fibres joining the basal bodies of the two flagella. Apparenly, synchronisation of flagella from different cells or from the same cell can be based on completely different mechanisms! This is a really nice work, which opens a lot of new questions…

Scattering Microalgae

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Matteo’s first paper as just been accepted in Physical Review Letters!

The paper concerns the following problem: which forces determine the motion of microorganisms through heterogeneous media (think e.g. soil or bottom sediments in lakes or coastal areas)? Current theories are divided in two groups, those that consider this to be mainly a microhydrodynamics problem, and those which do not consider fluid dynamics at all and treat it as a contact interaction problem. So: which one is right? For microorganisms pushing themselves from the back, recent work has shown that the interaction is fundamentally hydrodynamic. Matteo has now shown that for organisms with front-mounted flagella, instead, the situation is much more complex and both fluid-mediated interactions and direct contact have to be taken into account. The paper is not out yet, but you can already read a draft version in the arXiv.

This work was a collaboration with Kela Lushi (Brown), Idan Tuval (IMEDEA), and Vasily Kantsler (Warwick).

Update: the paper has been published! Check it out here!

Raphael goes to Aberdeen

Raphael is leaving this evening for Aberdeen! He is going for a conference on Physics and Biology of Active Systems, where he will present his (almost completed) work on bioactive dispersal of tracers. He found a cool effect that was not noticed before but ends up dominating the statistical properties of the tracers, which disperse with an effective diffusivity more than one order of magnitude larger than previously estimated. We’ll write-up soon(ish) so watch this space!

Metachronal Wave Defects on Interface!

The Journal of the Royal Society: Interface just accepted our latest paper, which includes the first report of recurring defects in metachronal coordination of eukaryotic flagella (see also Arxiv version). These defects, which we observe in Volvox carteri, are a type of incomplete coordination which we think might originate from a variation, along the surface of Volvox, in the frequency at which cells beat their flagella. They might be related to so-called chimera states of groups of interacting oscillators…. More to come on this: we’re still working on it!