The Periodic Response of Periodically Perturbated Stochastic Systems
  The paper introduces a new numerical characteristic of one dimensional stochastic systems. This quantity is a measure of minimal periodicity, can be detected in the process deep differential structure. The claim is that this new measure of stochasticity is also a well adapted characteristic for research of stochastic resonance phenomena. 
A.Yu.Shahverdian, A.V.Apkarian