Diffusion of Asymmetric Swimmers

TL;DR

This paper studies how particles with curved trajectories diffuse due to fluctuating curvature, revealing a novel speed-dependent diffusivity and implications for intracellular vesicle transport.

Contribution

It introduces a model for diffusion of asymmetric swimmers with fluctuating curvature and uncovers a new exponent linking diffusivity to particle speed.

Findings

Diffusivity is independent of speed at low velocities.

At higher speeds, diffusivity depends on speed via a new exponent.

Effective diffusivity increases with vesicle size, aiding intracellular transport.

Abstract

Particles moving along curved trajectories will diffuse if the curvature fluctuates sufficiently in either magnitude or orientation. We consider particles moving at a constant speed with either a fixed or with a Gaussian distributed curvature magnitude. At small speeds the diffusivity is independent of the speed. At larger particle speeds, the diffusivity depends on the speed through a novel exponent. We apply our results to intracellular transport of vesicles. In sharp contrast to thermal diffusion, the effective diffusivity increases with vesicle size and so may provide an effective means of intracellular transport.