  We consider moving particles in media with nonlinear friction and drive them
by an asymmetric dichotomic Markov process. Due to different energy
dissipations, during the forward and backward stroke, we obtain a mean
non-vanishing directed flow of the particles. Starting with the stationary
velocity distribution, we calculate the stationary current of particles, the
variance and the relative variance in dependence on the degree of nonlinearity
of the friction, on the asymmetry and for different strengths of friction. In
two dimensions the particle performs diffusional motion, if in addition the
direction of the asymmetric drive changes stochastically.
