This was thought to be caused by the difficulty of achieving an accurate injection of a tiny heart that beats 600 times a minute.

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Inspired by what I had seen so far, I opted to squeeze in a last-minute jeep tour of the tiny Nairobi National Park that borders the runways of the domestic Wilson Airport.

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As for battery usage, Kempton says that initially utilities would need only tiny bursts of power to balance cycles for a minute or two, so there would be no need to fully discharge the car's battery.

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