Figure 2.

Motion analysis of the swarming front. (A) Phase-contrast image of the swarming front is shown at the start of the time-lapse image series. (B) Whole-image-series temporal variance analysis indicates patches of different intense motion activity: high variance (red) and low variance (blue). (C) The fraction of time with significant variance analysis reveals decreasing motion toward the swarming front: large fraction of time with significant variance (red) and small fraction of time with significant variance (blue). (D) The fraction of pixels with significant variance is plotted against the distance from the front averaged from three independent replicates. To see this figure in color, go online.