Fluctuating diffusivity of RNA-protein particles: Analogy with thermodynamics

TL;DR

This paper explores a formal analogy between fluctuating diffusivity of RNA-protein particles in living cells and thermodynamic principles, proposing a thermodynamics-like framework for understanding diffusivity fluctuations.

Contribution

It introduces a thermodynamics analogy for fluctuating diffusivity, defining heat, work, and entropy analogs, and examines the geometric aspects of fluctuation distributions.

Findings

Clausius-like inequality holds for diffusivity fluctuation entropy

Analogies established between diffusivity and thermodynamic quantities

Geometric perspective on fluctuation distribution changes

Abstract

A formal analogy of fluctuating diffusivity to thermodynamics is discussed for messenger RNA molecules fluorescently fused to a protein in living cells. Regarding the average value of the fluctuating diffusivity of such RNA-protein particles as the analog of the internal energy, the analogs of the quantity of heat and work are identified. The Clausius-like inequality is shown to hold for the entropy associated with diffusivity fluctuations, which plays a role analogous to the thermodynamic entropy, and the analog of the quantity of heat. The change of the statistical fluctuation distribution is also examined from a geometric perspective. The present discussions may contribute to a deeper understanding of the fluctuating diffusivity in view of the laws of thermodynamics.