This results in alternating periods of quiescence and activity - remarkably like the build-up and collapse of a sand pile.

这会导致变换的静止和活动的周期-与沙堆的堆砌和崩塌非常相像。

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From the other two, there were signs of sleep-brief periods of activity alternating with periods of silence.

其它二个细胞有短暂睡眠期和寂静交替期相互交替信号。

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