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Home page > Séminaires > Séminaires 2021 > MSC Visio-Seminar. 16h00 April 26th 2021. Alexander Petroff (Clark University, USA) : "Formation and Dynamics of Active Crystals by Fast-Swimming Bacteria".

MSC Visio-Seminar. 16h00 April 26th 2021. Alexander Petroff (Clark University, USA) : "Formation and Dynamics of Active Crystals by Fast-Swimming Bacteria"

Sauf mention contraire, les séminaires et les soutenances se déroulent à 11h30 en salle 454A du bâtiment Condorcet.


There will be a live diffusion with Zoom.

Exceptional schedule. Monday April 26th 16h.

Contact Michael Berhanu to attend the video seminar

Formation and Dynamics of Active Crystals by Fast-Swimming Bacteria

Pr. Alexander Petroff

Department of Physics, Clark University

Clark University, Worcester, Massachusetts, USA

Abstract : We investigate a new form of collective dynamics displayed by Thiovulum majus, one of the fastest-swimming bacteria known. Cells spontaneously organize on a surface into a visually striking two-dimensional hexagonal lattice of rotating cells. As each constituent cell rotates its flagella, it creates a tornado like flow that pulls neighboring cells towards and around it. In the first part of the talk, we describe the earliest stage of crystallization, the attraction of two bacteria into a hydrodynamically-bound dimer. In the second part of the talk, we present the dynamics of bacterial crystals, which are composed of 5—200 hydrodynamically bound cells. As cells rotate against their neighbors, they exert forces on one another, causing the crystal to rotate and cells to reorganize. We show how these dynamics arise from hydrodynamic and steric interactions between cells. We derive the equations of motion for a crystal, show that this model explains several aspects of the observed dynamics, and discuss the stability of these active crystals.


Contact : Équipe séminaires / Seminar team - Published on / Publié le 20 avril


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