In Phase or Out of Phase, that is the question

 

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How do cilia synchronise? Through hydrodynamics? Elasticity? Intracellular coupling? The mechanism seems to depend on whether these oscillators belong to same cell or not. In the latter case, we have shown that hydrodynamic interactions suffice; in the former, however, direct intracellular coupling between the flagella is necessary (see here, here, and here). How is this coupling acting? How can it promote opposite types of synchronisation? Our idea is that synchronisation states depend on the cell actively stiffening/relaxing the internal fibres joining the ciliary basal bodies. We explore this hypothesis in our new paper, recently accepted in J. Roy. Soc. Interface, looking at a  minimal model of “cilia coupled by intracellular connections”. (ArXiv preprint. Full version and Supplementary Informations including animations). A big Thank to U. Melbourne and its Department of Mathematics and Statistics for hosting Marco during the final developments of this work!!

Fluids CDT Summer School @ Imperial

Last week I gave a couple of lectures at the Fluids CDT Summer School, organised by Eric Keaveny and Chiu Fan Lee. It was great fun (for me, at least), and I would have liked to be able to stay more than just one day… In any event, if you’re interested, you can find a PDF of my presentation on bacterial and eukaryotic motility (…as in swimming) here and here. Enjoy! …and please let me know your thoughts/comments!

Pilot Project from Network Plus

We’re delighted to share the news that we have received travel funds from the EPSRC Network Plus Emergence and Physics Far From Equilibrium to kickstart a collaboration with the groups of Dr. Giorgio Volpe (UCL, UK), Dr. Nuno Araújo (U. Lisbon, Portugal) and Dr. Idan Tuval (IMEDEA-UIB, Spain). The project, which will start later this year, focusses on understanding and controlling transport properties of binary suspensions where microscopic active particles interact with passive ones (cargoes).

Microparticle entrainment à la Taylor

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Close contact between microorganisms underpins fundamental interactions including infection, microbial grazing and fertilisation, but whether or not these interactions actually happen depends critically on the duration of contact. For swimming microorganisms, prolonged contact with an object should manifest as entrainment, and its extend hinge on the physics of escape from the entrained state. At present, neither the existence of entrainment nor the physical mechanisms determining its duration are well established. In our new paper, published in Physical Review Fluids, we combine experiments and theory to show that particle entrainment is indeed a generic feature of swimming microorganisms, and that its duration depends on an interplay between advection and diffusion. A Taylor-dispersion-type theory rationalises the dependence of the distribution of contact times on swimmers’ parameters, and predicts an optimal size for entrainment (~1μm), which we confirm experimentally.  [ArXiv Preprint]

Dr. Matteo Contino

Matteo had a great Ph.D. viva yesterday, and is finally Dr. Contino! (Ok, he still has some minor corrections… but still). He will now move to Oxford to work for a spin-off of the University of Oxford.

Well done Matteo and good luck for the future!