Active Brownian particles refer to a theory that is used in order to model the self-propelled
motion of biological entities such as, for example, cells migrating on substrates. For this purpose the
friction coefficient of ordinary Langevin dynamics is assumed to be velocity dependent, representing
the take-up of energy from some external reservoir and its conversion into kinetic energy. Other
well-known generalizations of Langevin equations are deterministic thermal reservoirs for which
the Nos´e-Hoover thermostat is a simple example. After introducing these two seemingly different
concepts I will show that they are quite related to each other. Particularly, I will focus onto
the origin of bimodal velocity distributions, which are produced by both types of generalized
Langevin dynamics. Starting from Nos´e-Hoover thermostats, I will argue that the bimodality can
be understood in terms of a combination of canonical with microcanonical distributions.

Ref.: R.Klages, Microscopic chaos, fractals and transport in nonequilibrium statistical mechanics
(World Scientific, Singapore, 2007), Chapter 16.