Figure 1

Detecting long-range correlations through DFA. Log-log plots of the fluctuation function F(ℓ) vs. the length scale ℓ. The scaling exponent α is given by the slope of the linear fit. The artificial sequence was generated using a standard method to create long-range correlated sequences [31] by imposing that α = 0.90, and the DFA recovers correctly this scaling exponent. The DNA sequence analyzed is the largest contig from human chr. IV mapped into a binary sequence using the SW (strong-weak) mapping rule: C or G → 1, A or T → 0. Its scaling exponent is α_fit = 0.76.