X-Message-Number: 13890 Date: Sat, 10 Jun 2000 14:06:04 -0700 From: Jeff Davis <> Subject: Re: cryostats and economics of scale Dr. Ettinger in #13852, re my post (#13844) about cryostats and economics of scale, writes: >Jeff also misspoke himself or erred in a couple of places. For one, he said > >>with two cryostats, one ten times as large as the other, the boil-off per >>patient--assuming that the number of patients inside the larger cryostat is >>proportionately >>larger: ten times as many--the cost per patient for liquid nitrogen >>replenishment would be reduced by a factor of ten. It's a bit embarrassing, but he's right. So let me go back and try to clear things up. There was a math error, and there was a communications error. Unfortunately, they went together all too well, distracting from and perhaps tending to discredit the point I was trying to make. First, the math error. When I wrote: "...assuming that the number of patients inside the larger cryostat is proportionately larger: ten times as many..." Whoops! Seriously wrong. It should have been "a thousand times as many". Because--and here's the communications error--when I said that one cryostat was ten times larger than the other, I was thinking of an increase in linear dimension by a factor of ten. Since volume is proportional to the cube of the linear dimension, an increase in linear dimension by a factor of ten results in an increase in volume by a factor of a thousand. However, I rather deftly botched the chance of getting that point across when I wrote, "ten times larger than the other", which, inevitably and logically would be interpreted as "ten times greater capacity", which is to say ten times greater internal volume. All these numbers making your head spin? Thinking to yourself, "It's not really all that interesting to me."? Well, you're right. It was my screw-up. No need to bother with it. Or, in the words of Rosanne Reannadanna, " Nevermind." Allow me, however, to quote Dr. Ettinger's from his post: "Eventually, as Jeff says, economies of scale will reduce liquid nitrogen cost per patient, regardless of the system used." Best, Jeff Davis "Everything's hard till you know how to do it." Ray Charles Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13890