Affinity and Fluctuations in a Mesoscopic Noria
  We exhibit the invariance of cycle affinities in finite state Markov processes under various natural probabilistic constructions, for instance under conditioning and under a new combinatorial construction that we call ``drag and drop''. We show that cycle affinities have a natural probabilistic meaning related to first passage non-equilibrium fluctuation relations that we establish. 
M. Bauer and F. Cornu
cond-mat.stat-mech