Model study on steady heat capacity in driven stochastic systems
  We explore two- and three-state Markov models driven out of thermal equilibrium by non-potential forces to demonstrate basic properties of the steady heat capacity based on the concept of quasistatic excess heat. It is shown that large enough driving forces can make the steady heat capacity negative. For both the low- and high-temperature regimes we propose an approximative thermodynamic scheme in terms of "dynamically renormalized" effective energy levels. 
Jiri Pesek, Eliran Boksenbojm, Karel Netocny
cond-mat.stat-mech