  We introduce a Langevin equation characterized by a time dependent drift. By
assuming a temporal power-law dependence of the drift we show that a great
variety of behavior is observed in the dynamics of the variance of the process.
In particular diffusive, subdiffusive, superdiffusive and stretched
exponentially diffusive processes are described by this model for specific
values of the two control parameters. The model is also investigated in the
presence of an external harmonic potential. We prove that the relaxation to the
stationary solution is power-law in time with an exponent controlled by one of
model parameters.
