Rigidity generation by nonthermal fluctuations and muscle contraction
Lev Truskinovsky (ESPCI, Paris)
Active stabilization in systems with zero or negative stiffness is an essential element of a wide variety of technological processes. We discuss a prototypical example of this phenomenon in a biological setting and show how active rigidity, interpreted as a formation of a pseudo-well in the effective energy landscape, can be generated in an over-damped stochastic system. We link the transition from negative to positive rigidity with time correlations in the additive noise, and show that subtle differences in the out-of-equilibrium driving may compromise the emergence of a pseudo-well. We apply our results to the description of the power stroke machinery in skeletal muscles which is behind their remarkable ability to take up an applied slack in a ms time scale. Along the way we draw some interesting parallels between muscle physiology and the theory of spin glasses.