A Growth Model for Dna Evolution (submitted to Nature)
  We introduce a simple model for DNA evolution. Using the method of Peng et al.$^1$, we investigate the fractal properties of the system. For small chains and chains of intermediate size we find a fractal exponent that indicates the existence of long-range correlations, as in real DNA sequences. However, when very large chains are studied the fractal exponent asymptotically converge to the value of a random sequence. We verify that the mutations are responsible for the apparent existence of long-range correlations. 
Maria de Sousa Vieira and Hans J. Herrmann