FIG. 3.

A random walk from Ref. 96 in this issue. Continuous time random walks (CTRWs) are stochastic models for anomalous diffusion (AD) processes. AD is characterized by pronounced trapping periods, during which the particle cannot move. This may happen, for instance, when small tracer particles are successively caged in a matrix of semiflexible biopolymers, such as the ultrastructure in living cells. Such environments are intrinsically noisy: the matrix itself evolves in time and fluctuates thermally, rattling the particle during trapping periods. Noisy CTRWs can account for such rattling effects. The red line shows the case when the thermal noise only weakly disturbs the trapping events (horizontal plateaus between sudden changes in position). In the blue line strong noise completely changes the trajectory with the same initial condition, highlighting the importance of an evolving environment for the single particle dynamics.