Distribution and Variability of Icebergs in the Eastern Davis Strait 63°N to 68°N

Pulsatile cardiopulmonary flow closely approximating a natural heartbeat is generated in a heart-lung machine by using a proportioning valve to partly convey blood in the machine's cardiopulmonary circuit to the arterial supply line, and to partly recycle that blood into the cardiopulmonary circuit upstream of the arterial pump. The relative proportions of conveying and recycling are varied in accordance with a waveform approximating the waveform of a human heartbeat.