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Résumé |
Swimming microorganisms often live in confined, complex environments, where they
transition between bulk and near-surface dynamics. Their dynamics can be
quantified in terms of first-passage statistics. In this talk, I will first
consider run-and-tumble bacteria confined in a channel. Combining theoretical
predictions based on a renewal framework with experimental observations of
Escherichia coli, we study the statistics of the time required, after leaving one
wall, to encounter either wall. I will discuss how incorporating heterogeneity in
tumbling rates or non-exponential run-duration distributions affects the survival
probability.
In the second part of the talk, I will consider active Brownian dynamics between
two walls. Using a systematic expansion, we compute first-passage properties.
Exploiting Siegmund duality, we infer the corresponding spatial properties for
active Brownian particles confined between hard walls and reveal a transition
towards a wall-accumulated state, reminiscent of experimental observations. |
