A study on a self-organized criticality in a dynamical many-body system
  A novel mechanism for the generation of self-organized criticality (SOC) is discussed in terms of the coupled-vibration model where the total system is forced under the uniform expansion of the Hubble type. This system shows a robust SOC behavior while the maximum size of the fluctuation, number of correlated particles in it and the temporal size of the system evolve as a function of time. 
Akira Iwamoto and Shinpei Chikazumi