Pumping-Restriction Theorem for Stochastic Networks
  We formulate an exact result, which we refer to as the pumping restriction theorem (PRT). It imposes strong restrictions on the currents generated by periodic driving in a generic dissipative system with detailed balance. Our theorem unifies previously known results with the new ones and provides a universal nonperturbative approach to explore further restrictions on the stochastic pump effect in non-adiabatically driven systems. 
V. Y. Chernyak, N. A. Sinitsyn