Inference of a nonlinear stochastic model of the cardiorespiratory   interaction
  A new technique is introduced to reconstruct a nonlinear stochastic model of the cardiorespiratory interaction. Its inferential framework uses a set of polynomial basis functions representing the nonlinear force governing the system oscillations. The strength and direction of coupling, and the noise intensity are simultaneously inferred from a univariate blood pressure signal, monitored in a clinical environment. The technique does not require extensive global optimization and it is applicable to a wide range of complex dynamical systems subject to noise. 
V.N. Smelyanskiy, D.G. Luchinsky, A. Stefanovska, P.V.E. McClintock