for the next three weeks. There might be an issue or two, but don't bet on it. Keep sending in the good stuff in any case. Thanks. The Management
[This is a message from Dimitri Mihalas (email@example.com). Mark Bartelt, Canadian Institute of Theoretical Astrophysics] in case you have not heard: from a reliable inside source i found out that the problem with ST is that the SOFTWARE driving the polisher was defective. the corrections for spherical aberration were put in with the wrong sign. consequently the mirror is not corrected for sph. abb., but has an added dose of it. the error was not detected during testing because no test with collimated light was ever done. (editorial remark: unthinkable!) apparently this was a $30M economy measure in the face of the Challenger accident. likewise none of the optics were ever tested in vacuum. the primary was and is "perfect" relative to the specified curve; but alas the specification was wrong. sigh. from my amateur astronomer days (does that include 1990?) i recall that spherical aberration is EASY to detect with the foucault test, which is done with a pinhole, not collimated light. it is hard to believe that ANYONE could have made such a blunder.. the only reason that people know this much is that the same software was used for AXAF. the errors there were so huge as to be immediately noticeable, and when the software was corrected, the mirror was "perfect". i don't know whether the information from axaf was available prior to the launch of ST, but it seems that it had to be. in which case one wonders why PE didn't issue a "hold everything!". the future: no chance of bringing the whole telescope down for a refit. best plan is to design compensating optics into the lightpath for future instruments: relatively easy to do. but that will still take 3-5 years. i suppose it's "win a few, lose a few..." but i personally think that nasa, the government, and the people should stick it into PE and TURN it hard until they agree to refund the cost of the mistake and of the repairs. i'm sick of seeing defense and defense-related contractors get away with bloody murder and just get fatter and fatter on the profits. back to theory dimitri
Y. Radai <ADAI1@HBUNOS.BITNET> writes: > So the statements that an impenetrable code has been broken and that >organizations need to change their cryptographic systems because of this >achievement seem a wee bit exaggerated. On the other hand, the NPR report mentioned that the Bank of England was planning to use a 150 digit number as a key in a new transaction processing system, but changed it to something "much larger" when they learned of the 9th Fermat prime factoring.
A while back I sent to RISKS an (itself rather buggy) description of a bug that turned up in the Lexis/Nexis database when I was doing date delimited searches in the library containing the fulltext opinions of the United States Supreme Court. A representative of Mead Data Central--the owner of the Nexis/Lexis service--has since contacted me to explain the nature of the bug and to assure me that it will be corrected on June 30. In the first place, it appears that the bug is _not_ in the basic software that searches through the database for cases decided on, after, or before a specified date. Secondly, it is clear that the bug did _not_ cause me to miss any cases that I should have located, it just turned up some additonal cases that were not decided within the period that I was searching. That is the good news. The bad news is that the problem relates to the way that the Lexis/Nexis system parses dates in the database and that the proposed fix will work only until the year 2000, at which time a new variant of the bug should cause real havoc. Here is a corrected version of the type of search that exposed the bug: Entitlement and date(aft 12/31/39 and bef 1/1/50) That search, when conducted in the Supreme Court file, should find all opinions, and only those opinions, decided by the United States Supreme Court during the decade of the 1940's that contained the word `entitlement'. (Lexis warned me that it assumed that I meant after 12/31/1939 and before 1/1/1950.) As it happens, there are no cases that meet those criteria. But Lexis reported that it had found a dozen or so cases--cases that did contain the word `entitlement' but that were decided in the 1960's, 70's, and 80's. It seems that a couple of months ago Mead Data Central decided to include the argued-date as well as the decided-date within the date field, and it is this enhancement that caused the bug. The fix that will be implimented this Saturday is to once again exclude the argued-date from the date field. Since cases are not always decided in the same year that they are argued, including the argued-date in the date field will, of course, cause some cases to be reported as occurring in two different decades, which would be a nuisance. But that is only a miniscule part of the bug. The real problem occurs because some cases are argued on more than one date, so that the argued-date field would appear in the database as, say: "argued June 22-23, 1980" and the decided date field as: "July 3, 1980)." At first glance that would not seem to cause any problem. And it wouldn't, except for the fact that the Lexis system parses the date fields in the same way that it parses user input, and thus concludes that "June 22-23" means "June 22-1923". Thus our hypothetical case would have a date of July 3, 1980 (which is after December 31, 1939) and would also have a date of June 22, 1923 (which is before January 1, 1950). If that case--decided, you will recall, in 1980--contains the word `entitlement' it will turn up in my search for cases in the decade of the 1940's, and in my searches in the 1950's, and in the 1960's, etc. I can understand why the system parses user input so as to interpret 1/1/50 as 1/1/1950--but I never dreamed that a system would parse its own data. According to the people at Mead Data Central, however, their system parses the data fields in exactly the same way that it parses user input. It seems that the Lexis/Nexis database contains texts--especially news reports--with dates in the form "nn/nn/nn". Today those dates are parsed as "nn/nn/19nn", but what is going to happen in the year 2000? It would seem that ambiguous data in the data base will be much harder to find and fix than a software bug. Peter D. Junger, CWRU Law School
I am a long time sufferer of CTS. The first symptoms I recall were during high school, nearly twenty years ago, but it was not properly diagnosed until I was in excruciating pain, dropping things, not sleeping because my hand was burning at night and more, all about four years ago. Tests said that I had "a very mild case"!? That reassuring info did not make my hand better. I used splints, Motrin, ice until I finally insisted on the carpal tunnel relief operation. That was two years ago, this month, but I still have recurrences - especially when I meet the same RISK which pushed my CTS over the edge: using a MOUSE. The typical mouse promotes all the bad habits that can result in CTS symptoms. One typically rests the heel of the palm on the mouse, and press the chord keys - frequently with constant pressure (on Apple's mice, the required pressure is substantial for me, and their new mouse reqlly aggravates the problem with its stylized, aerodynamic "look"). I cannot use a mouse to this day without suffering a "mouse hangover". Track balls are better for me, but I still would rather avoid them. I am really looking forward to _getting_my_hands_on_ ;-) a touch screen. I've seen some very nice ones with quite satisfactory resolution! And please - If you think that you might have CTS - don't waste time. See Your M.D. Terry Kane, Sales Technologies, Inc, Atlanta, GA (404) 841-4000
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