Pulse rate decrease in SEP1 phrases units. In blue (circles) the measures of pulse rate by mean of a summed auto-correlation method except the value of 1970 which is taken from literature1. In red (crosses), the points are computed by estimation of the frequency peak (by a FFT) divided by 3 and 4 for units B and C respectively ((a) and (b)). The errors bars are computed as for SEP2. The line is the linear interpolation by least-square error of the points displayed in the graph.