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DY: Fachverband Dynamik und Statistische Physik

DY 9: Statistical Physics far from Thermal Equilibrium

DY 9.12: Vortrag

Montag, 17. März 2025, 18:15–18:30, H47

Fluctuating diffusivity in living cells: Analog of Carnot engine — •Yuichi Itto — Aichi Institute of Technology, Japan — ICP, Universität Stuttgart, Germany

The diffusivity fluctuating over local areas of living cells is experimentally known to obey the exponential law for normal/anomalous diffusion. In Ref. [1], a formal analogy of the fluctuating diffusivity to thermodynamics has been studied. Remarkably, the exponential law is formally equivalent to the ``canonical distribution": the diffusivity, which is proportional to local temperature of the cell in nonequilibrium stationary states [2], is identified with the analog of the system energy. Consequently, the analogs of the internal energy, the quantity of heat, work, and the Clausius inequality have been established.

Here, the analog of the heat engine is constructed for the fluctuating diffusivity [3]. This heat-like engine consists of processes realized by compression/expansion of the cell and the change of temperature, along which the average value of the diffusivity or local temperature is kept fixed. The efficiency of the engine in a cycle, which characterizes how much the diffusivity change as the analog of work is extracted, is found to formally take that of Carnot's. The result is expected to be useful, for example, for tuning the rates of biochemical reactions in cells, see, e.g., Ref. [4].

References [1] Y. Itto, Entropy, 23, 333 (2021). [2] Y. Itto and C. Beck, J. Royal Society Interface, 18, 20200927 (2021). [3] Y. Itto, in preparation. [4] N. Bellotto, J. Agudo-Canalejo, R. Colin, R. Golestanian, G. Malengo, and V. Sourjik, eLife, 11, e82654 (2022).

Keywords: Analogy with thermodynamics; Analog of Carnot engine; Efficiency; Fluctuating diffusivity in living cells