Please try the URL privacy information feature enabled by clicking the flashlight icon above. This will reveal two icons after each link the body of the digest. The shield takes you to a breakdown of Terms of Service for the site - however only a small number of sites are covered at the moment. The flashlight take you to an analysis of the various trackers etc. that the linked site delivers. Please let the website maintainer know if you find this useful or not. As a RISKS reader, you will probably not be surprised by what is revealed…
[This item illustrates the need for awareness of the technology by people in the environment. The interference problem is also relevant to RISKS.] In the Thursday 5 June 1986 issue of The New York Times, there is an article about an accident that occurred with a magnetic resonance imager--the first serious accident of this type. The device uses a huge magnet with a hollow cylinder for the patient to lie inside. The accident occurred in a converted semitrailer used for mobile diagnosis. A technician was in the hollow when two steel tines, weighing more than 80 pounds each, were ripped off by the magnet from an (intentionally) approaching forklift, and ended up knocking the man 15 feet away, and breaking many bones. The magnet complicated rescue work. A doctor could not approach until he removed his stethoscope. A paramedic's scissors flew off when he tried to cut the injured man's pants. A policeman nearly had his gun pulled from his holster. Rescuers were slow to grasp just how strong the magnetic field was, and to realize that all metal objects had to be removed in order to approach the injured. And finally--here's where the computer connection comes in!--the magnetic bank cards of the rescuers were erased. The magnet's emergency shutdown could not be used, as it hadn't been fully installed yet. So it took 20 minutes instead. The article pointed out that in normal usage these difficulties are not present, as normally special equipment is used and all nearby personnel are familiar with its power. But as revealed by the accident, emergency workers do not have such training. (They also do not have training for lots of special and exotic situations. There is a certain iatrogenic irony in this situation — which is not uncommon in medical practice.) ["Iatrogenic" implies that a problem is caused or made worse inadvertently by doctors and/or medicine in what might otherwise be perceived as an attempted cure or improvement. [[As a result, one suffers from inadvertigo?]] The use of "irony" seems like an attractive pun in this context. Thanks. PGN] Note--some details are slightly unclear from the article I read. If anyone wants more details, you are referred to a recent letter in The New England Journal of Medicine, by(?) Drs. Syverud and Fowler. -Matthew ucbvax!brahms!weemba Matthew P Wiener/UCB Math Dept/Berkeley CA 94720
After watching the reports on TV giving the conclusions of the Rogers Commission, a question occurred to me that may be relevant to Risks. A lot of attention has been given to the fact that some of the rocket engineers recommended against launching the Challenger. What I haven't heard anyone talk about is whether such recommendations before a launch were common. The media coverage has always implied that the engineer's protests were an unusual event, but is this really the case? I can easily imagine a scenario where before every launch a different engineer recommends against launching, but management decides that their reasons are not adequate (after all, one of management's jobs is to evaluate such recommendations) and goes ahead and launches as scheduled. After awhile the situation might become similar to the little boy who cried wolf. I'm not trying to defend NASA, or implying that the above scenario describes the situation. I'm just trying to understand the context of their decision to launch Challenger. Can anyone shed any light on this? /Don [I hope one of our readers can respond. With regard to the software problems, there have been complaints that the new mission software was frequently delivered only at the very last minute, and that no extensive simulation testing could be done. The impression is given that whatever the state of the software was at the final scheduled delivery date, that is what was delivered — irrespective of how buggy it might be. I think it would be very helpful to understand the circumstances better. Tasteful reports on this subject — as well as the more general question raised by Don — would be welcome. PGN]
Estell makes the following comment: The "complexity" and "historical" arguments even interact. Peter Denning observed years ago that the difficulty of understanding a program is a function of size (among other things). He speculated that difficulty is proportional to the SQUARE of the number of "units of under- standing" (about 100 lines of code). Old tactical software, in assembly language, tends to run into the hundreds of thousands of lines of code; e.g., a 500,000 line program has 5000 units of understanding, with a diffi- culty index of 25 million. That same program, written in FORTRAN, might shrink to 100,000 lines thus only 1000 units of understanding, thence a difficulty index of one million. That's worth doing! I believe that the same program written in a "high level" language, like Fortran, would probably have about the same number "units of understanding" ~ 5000, in this case. Assuming that the "units of understanding" are understood to be higher level concepts, Fortran would enable one to write those units with fewer lines of code. But I wouldn't expect the number of those units to decline with nearly the same scale factor. Of course the likelihood of a typographical error would be reduced by such a scale factor, but that's not the major concern here. --Martin Purvis
I believe there were several retractions - enough for me to believe, at any rate. If I hadn't been so tired when I sent that bit to Peter I would have expounded further on the delightful topic of various matters hitting the fan, etc. I *hope* that whoever designed the helicopter-rotor-selection algorithm did more than simply search for cyclic doppler. There are too many things out in the real world that rotate but aren't helicopters. - Wind turbines on a barn - The rotating beacon at some airports - Windmills - Cooling fans on the roof of a large building - Cooling fans on top of a diesel/electric locomotive By the way, I have patronized a fair number of outhouses down in the Shenandoah Valley - While almost all needed (desperately!) ventilating fans, only one or two had them - and they sounded like squirrel cage blowers within a ventilating pipe, not likely to be picked up by Sgt. York's radar. Nose yes, radar no. - Mike McLaughlin <mikemcl@nrl-csr> [I understand that, inspired by these reports, particle physicists are now working on a new approach: Latrinos. Note: I expect that future submissions to RISKS on this subject will get flushed. (Please replace all DIVADs.) PGN]
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