  We study the dynamics of a class of two dimensional stochastic processes,
depending on two parameters, which may be interpreted as two different
temperatures, respectively associated to interfacial and to bulk noise. Special
lines in the plane of parameters correspond to the Ising model, voter model and
majority vote model. The dynamics of this class of models may be described
formally in terms of reaction diffusion processes for a set of coalescing,
annihilating, and branching random walkers. We use the freedom allowed by the
space of parameters to measure, by numerical simulations, the persistence
probability of a generic model in the low temperature phase, where the system
coarsens. This probability is found to decay at large times as a power law with
a seemingly constant exponent $\theta\approx 0.22$. We also discuss the
connection between persistence and the nature of the interfaces between
domains.
