A Langevin model for complex cardiological time series
  There has been considerable efforts to understand the underlying complex dynamics in physiological time series. Methods originated from statistical physics revealed a non-Gaussian statistics and long range correlations in those signals. This suggests that the regulatory system operates out of equilibrium. Herein the complex fluctuations in blood pressure time series were successful described by physiological motivated Langevin equation under a sigmoid restoring force with multiplicative noise. 
C.E.C. Galhardo, B. C. Coutinho, T.J.P.Penna, M.A. de Menezes and   P.P.S. Soares
q-bio.NC cond-mat.stat-mech