Is the ratio of flow-mediated dilation and shear rate a statistically sound approach to normalization in cross-sectional studies on endothelial function? - Atkinson, G; Batterham, A M; Black, M A; Cable, N T; Hopkins, N D; Dawson, E A; Thijssen, D H; Jones, H; Tinken, T M; Green, D J (J Appl Physiol, 2009)