Fig. 4
From: Cerebral arterial flow dynamics during systole and diastole phases in young and older healthy adults
Examples of arterial flow waveforms (AFW) in two subjects. (A) The behaviour of the AFW enables the automatic selection of point M1, as it demonstrates a sign change in the first derivative accompanied by a change in the curve’s concavity. (B) The AFW monotonically decreases between AP1 and AP2, indicating that the curve does not increase between these points. Consequently, no sign change was observed in the first derivative at point M1, which necessitated manual selection