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. 2022 Nov 24;43(4):552–564. doi: 10.1177/0271678X221142527

Figure 1.

Figure 1.

Separation of the original mean arterial blood pressure (MAP) signal (a) into its positive (b) and negative (c) derivatives for a 22 year-old male subject during the repeated squat-stand maneuver at 0.05 Hz. (d) time-integral of the positive derivative signal; (e) time-integral of the negative derivative signal. After linear detrending of the signals in (d) and (e), (f) shows the integrated positive (P+D) and negative (P−D) derivative signals used as inputs to a multivariate autoregressive-moving average (ARMA) model with middle cerebral artery velocity (MCAv) as output. The mathematical derivation of P+D and P-D is described in Methods (Mathematical background).