  We use the internal-variable, effective-temperature thermodynamics developed
in two preceding papers to reformulate the shear-transformation-zone (STZ)
theory of amorphous plasticity. As required by the preceding analysis, we make
explicit approximations for the energy and entropy of the STZ internal degrees
of freedom. We then show that the second law of thermodynamics constrains the
STZ transition rates to have an Eyring form as a function of the effective
temperature. Finally, we derive an equation of motion for the effective
temperature for the case of STZ dynamics.
