ABSTRACT
Athermal and glassy systems driven by shear or other external forces are by definition not in thermal equilibrium. Fluctuations in these systems are induced by the driving force and do not arise from random thermal motion. However, there are obvious similarities between equilibrium thermal systems and driven systems that reach a nonequilibrium steady-state. In fact, there have been many attempts to develop thermodynamic and statistical descriptions (Casas-Vazquez & Jou 2003) of these systems including kinetic theories for driven granular gases (Jenkins & Richman 1985), the Edward’s entropy formalism for granular packings (Edwards & Oakeshott 1989; Coniglio et al. 2001), and applications of equilibrium linear response and fluctuation-dissipation (FD) relations (Cugliandolo et al. 1997) to define effective temperatures in aging (Barrat & Kob 1999; Leonardo et al. 2000) and sheared glasses (Berthier & Barrat 2002; O’Hern et al. 2004) and compacting (Colizza et al. 2002; Coniglio & Nicodemi 2000) and sheared granular materials (Makse & Kurchan 2002; Kondic & Behringer 2004).
