Resonant activation in a simple kinetic model

We present a very simple Markovian kinetic model displaying a stochastic resonant behavior which is similar to the one found in the escape of a particle over a fluctuating potential barrier. The basic mechanism that is responsible for the existence of resonance is identified. This allows the generalization of the model in different ways, leading to a variety of models where a similar phenomenon is to be expected. It is also shown that the initial conditions play an important role in determining whether the resonant activation actually shows up.