Sommaire:

Among the many models aimed to describe the emergence of directional motion in active particles, an important class relies on the use of effective, velocity-dependent forces which, when coupled to an asymmetric potential, give rise to directed transport. A common feature of such models is that velocity-dependent forces are anti-dissipative in a range of velocities, which is consistent with a locally negative effective friction coefficient. In this talk I will present a new model for chemotactic response which does not rely on the introduction of a chemotactic potential, but in a nonequilibrium quasi-Onsagerian mesoscopic chemo-mechanical coupling. When sufficiently coarsegrained, our model can be reduced to an effective description in terms of a velocity dependent force. Remarkably, such force leads to directed motion allowing the motor even to carry a cargo, in spite of the effective friction coefficient being strictly possitive, i.e., dissipative, for all velocities. I will discuss on the mechanics and thermodynamics of such a motor, and clarify that the origin of directed motion in this apparently dissipative system resides on the breakdown of the time-reversal symmetry of the effective friction coefficient.

Pour plus d'informations, merci de contacter Parmeggiani A.