  This paper examines the stability of a previously proposed version of the
shear-transformation-zone (STZ) theory of plasticity where the total STZ
population is determined by an effective temperature and compares it to
experimental results for a metallic glass. In particular, the addition of
effective temperature dynamics to the shear transformation zone theory leads to
the existence of a range of strain rates for which the strain localizes into
shear bands. Yet while the steady-state results qualitatively agree, the
instability of the dynamics of the system while loading begins better describes
the experimental observations.
