  We use mesoscopic non-equilibrium thermodynamics theory to describe RNA
unfolding under tension. The theory introduces reaction coordinates,
characterizing a continuum of states for each bond in the molecule. The
unfolding considered is so slow that one can assume local equilibrium in the
space of the reaction coordinates. In the quasi-stationary limit of high
sequential barriers, our theory yields the master equation of a recently
proposed sequential-step model. Non-linear switching kinetics is found between
open and closed states. Our theory unifies the thermodynamic and kinetic
descriptions and offers a systematic procedure to characterize the dynamics of
the unfolding process
