> Perhaps the most innovative modification involved fluid mechanics, one of Vrselja’s specialties in graduate school. As the British mathematician John Womersle

> Perhaps the most innovative modification involved fluid mechanics, one of Vrselja’s specialties in graduate school. As the British mathematician John Womersley managed to quantify more than half a century ago, blood does not circulate through our arteries at a uniform rhythm — it circulates in pulses, in concert with the shudder of our hearts. To account for that dynamic, the BMI unit had shipped with an automated “pulse generator,” a device that replicates the heartbeat’s pulsatility in the organs. > But the pulse generator’s settings proved unsuitable for brains, which have a different flow pattern than the rest of the body. Before Sestan’s team adjusted the settings, the fluid might not completely permeate the vasculature of the organ, leaving parts of the brain essentially untreated. In such tissue, Daniele told me, “you’d end up with this sludgy, white yogurt-ish substance. It was a mess.” Conversely, if the pressure was too high, “the brain could just physically not stand it.” The organ fell apart. > By that summer, Vrselja and Daniele had fine-tuned the pulse generator and attached a number of custom sensors[...] It sounds like it was a lot of work getting the pulsation right. If they actually needed pulsation at all that seems like an interesting finding unto itself, since humans and cattle do fine with continuous-flow hearts: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3423277 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3423277