Fig. 3.

Histograms showing: a v _x for EF=0 mV/mm; b v _y for EF=0 mV/mm; c v _x for EF=100 mV/mm; d v _y for EF=100 mV/mm; e v _x for EF=200 mV/mm; f v _y for EF=200 mV/mm; g v _x for EF=400 mV/mm; h v _y for EF=400 mV/mm; i D _x for EF=0 mV/mm; j D _y for EF=0 mV/mm; k D _x for EF=100 mV/mm; l D _y for EF=100 mV/mm; m D _x for EF=200 mV/mm; n D _y for EF=200 mV/mm; o D _x for EF=400 mV/mm; p D _y for EF=400 mV/mm. A red vertical line is superimposed on each histogram to indicate the sample mean. The sample mean value for each histogram is indicated in the top left of each subfigure