Ralf Metzler (Potsdam), Aljaz Godec (Potsdam)
In 1905 Einstein formulated the laws of diffusion, and in 1908 Perrin published his Nobel-prize winning studies determining Avogadro’s number from diffusion measurements. With similar, more refined techniques the diffusion behaviour in complex systems such as the motion of tracer particles in living biological cells is nowadays measured with high precision. Often the diffusion turns out todeviate from Einstein’s laws. This talk will discuss the basic mechanisms leading to anomalous diffusion as well as point out the physical consequences. In particular the unconventional behaviour of non-ergodic, ageing systems will be addressed within the framework of different stochastic processes [1,2]. Specific physical systems such as the motion of particles in granular gases, tracer diffusion in flexible gels and in living biological cells, as well as in quenched energy landscapes will be analysed in further detail.
 R. Metzler, J.-H. Jeon, A. G. Cherstvy E. Barkai, Phys. Chem. Chem. Phys.16, 24128 (2014).
 E. Barkai, Y. Garini R. Metzler, Phys. Today 65(8), 29 (2012).
The precision of signaling in biological cells and novel diagnostic devices is limited due to the noise imposed by the thermal diffusion of molecules. We show how a random albeit directed delivery of molecules improves the precision of biochemical concentration measurements by reducing the noise. The conditions for improved sensing are compatible with observations in living cells.