Variations in the power spectrum indices with velocity thickness for the different GMCs. The error bars correspond to the 1σ statistical uncertainties on the fit. The dotted horizontal lines indicate the saturation index for each GMC, corresponding to the thick regime where density fluctuations dominate. The dashed vertical lines show the respective velocity dispersion, σ_V, for each GMC. The data points used to compute the thin and thick indices (γ_thin and γ_thick), are indicated with diamonds and square symbols, respectively. These values, as well as the index of the second order structure function (m), are indicated in each panel (see text for details).