Abstract
The normal diffusion of a tracer under stationary conditions in complex environments may approach a Laplace (or exponential) distribution. Inspired by biological systems, the authors show that the diffusion of a passive tracer along a narrow corrugated channel can exhibit this very property simply as an effect of a random opening and closing of the channel pores.
Highlights
Recent observations [1,2,3,4,5,6] of particle diffusion in fluctuating crowded environments manifestly contradict the common belief that normal diffusion is associated with a Gaussian distribution of spatial displacements
We investigated how the non-Gaussian normal diffusion mechanism depends on ε0
The dependence of D on ε0 in the absence and presence of channel fluctuations is compared in the inset of Fig. 4
Summary
Recent observations [1,2,3,4,5,6] of particle diffusion in fluctuating crowded environments manifestly contradict the common belief that normal diffusion is associated with a Gaussian distribution of spatial displacements. If for simplicity, we restrict ourselves to one dimensional (1D) geometries, the displacement, x(t ) = x(t ) − x(0), of a standard overdamped Brownian particle suspended in a homogeneous Newtonian fluid [7] (i) grows with time according to the EinsteinStokes law, x2(t ) = 2Dt; and (ii) is distributed according to a re√scaled Gaussian probability density function (pdf), p( x/ t ) with half-variance D Under these circumstances, the random variable x(t ) is said to undergo Gaussian normal (or Fickian) diffusion. We investigate both numerically and analytically the directed diffusion of an overdamped Brownian particle in a narrow quasi-1D corrugated channel [22,23] of fluctuating width Such a time variable geometry is inspired to cell biology [24,25] and models the key ingredient of the phenomenon under study, namely slow environmental fluctuations. V, the compartmentalization of particle’s diffusion emerges as a prerequisite of non-Gaussian normal diffusion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
