A nonlinear distribution of PEFs can suppress the oscillations of peripheral sister KT pairs. (A) Distribution of PEFs in the spindle: for KT pairs in the middle of the spindle, the PEFs initially decrease linearly away from the equator then stay constant toward the poles (black line). In contrast, for KT pairs at the periphery of the spindle, the PEFs are very low near the equator, then increase sharply (nonlinear) to high levels (red line). See Materials and methods for additional quantitative details. (B) KT–pole (left KT, red; right KT, blue) and inter-KT distance (green), and cohesin rest length (purple) over time. Note the erratic dynamic behavior. (C) Position of sister KTs (left KT in red, right KT in blue) and spindle poles (black) over time, compare with Fig. 1 B. (D and E) Inter- (D) and intra-KT (E) distances produced by the model (2.22 ± 0.16 µm [n = 400] and 0.12 ± 0.01 µm [n = 60], respectively) shown side-by-side with the distances observed experimentally in live (inter-KT distances, n = 530) or fixed (intra-KT distances, n = 228) cells. Experimental data are shown in dark red and model data are shown in light red. The inset in E shows a close-up of the distribution of the data produced by the model. (F and G) Time evolution of the total number of attached MTs (16 ± 3 and 42% in depolymerization state; F) and the total number of attached Ndc80 complexes (44 ± 16; G) for the left (red) and right (blue) sister KTs. An example of a model simulation of KT and kMT dynamics for a nonoscillating peripheral KT pair is shown in Video 1 (bottom).