Structural universality class from time-dependent diffusion

For the diffusion coefficient $D(t)$ in tissue approaching its long-time value as $D(t) - D_{\infty} \sim t^{-\theta}$, with $\theta = (p + d)/2$ where d is the spatial dimension of the relevant disorder and p the structural exponent of its density correlations at long wavelengths, measure $\theta$ and assign p for white matter along and across axons, grey matter and muscle. An answer is a classification of tissues by p with measured exponents and uncertainty.

Oscillating and pulsed-gradient measurements over diffusion times spanning at least a decade, fitted against the competing power laws with model-selection statistics.