Figure 4.
Uncertainty quantification and scale-dependence of morphological metrics (Specimens 1 and 2). (a) Fluctuations of placental villous tissue area fraction in Specimen 2 for the ROI with a volume of approximately 1.22 × 1.22 × 1.22 mm3 (insets illustrate selected slices). (b) Volume fraction fluctuations (mean ± s.d.) versus effective ROI size. (c) Scale-dependence of a relative error in the tissue volume fraction (ϕ) and specific surface area (Sv) estimates; the inset compares to the theoretical prediction of ∼(ROI volume)1/2 on a logarithmic scale (see electronic supplementary material, S9). (d) Radial two-point autocorrelation function (mean; s.d. is shown with shaded lines); the corresponding approximate transition range to uncorrelated mesoscale (mean autocorrelation ≲1%) is shown as a grey stripe in (c).