Momentum transfer in non-equilibrium steady states
  When a Brownian object interacts with non-interacting gas particles under non-equilibrium conditions, the energy dissipation associated to the Brownian motion causes an additional force on the object as a `momentum transfer deficit'. This principle is demonstrated first by a new NESS model and then applied to several known models such as adiabatic piston for which simple explanation has been lacking. 
Antoine Fruleux, Ryoichi Kawai, Ken Sekimoto
cond-mat.stat-mech