Thanks Gerard for all those explanations, I'm particularly convinced by
the last one.
Poor of me, who believed that the "B" stood for Boltzman or something
like that, I now have the correct answer!
Cheers
Virgile
Gerard DVD Kleywegt a écrit :
>> May be too trivial, I was just wondering
>> what "B" stands for in the term "B-factor".
>
> i don't really know, but i do have some wild theories, none of which
> are necessarily based in fact:
>
> - the B-factor is also called the Debye-Waller factor. now, someone
> assumed that peter debye was french (instead of dutch) and that his
> name should be written "de Bye"; hence the B as the "first" letter in
> his name (something similar happened to monsieur luzzati whose
> oft-abused 1952 paper is headed "Par V. Luzzati" which probably led
> some people to believe he was swedish and that "Par" was his first
> name. once "P.V. Luzzati" made it into the x-plor manual (e.g.,
> http://nmr.cit.nih.gov/xplor-nih/xplorMan/node484.html) mis-citations
> of this kind mushroomed, mostly by people who couldn't read the
> original paper because it was in french, in which language "par" means
> (written) "by")
>
> - there was a lot of buzz when the concept was first introduced which
> led to associations with bees; hence "bee-factor" or, shortened,
> "B-factor"
>
> - they wanted to call it "A-factor" first, but realised that the A
> could be mistaken for the indefinite article which they definitively
> didn't want. i mean, how cool is "a factor" ? hence the B-factor
>
> - the name follows the same path as that of the programming language
> "C" (which was simply the third version of a draft, where the earlier
> versions had been called "A" and "B"), but they got it right in only
> two tries. the first draft ("A-factor") was correct down to a factor
> of pi. once the bug had been removed, the second version (that we
> still use today) was called the "B-factor"
>
> - around 1920, there was a heated debate as to whether or not a
> thermal factor was really necessary or merely a modernistic luxury.
> this discussion was held in the carrier-pigeon-based predecessor of
> the ccp4 bulletin board (little-known fact: a lot of carrier pigeons
> had been bred by the british for communication duties during world war
> I and they found good jobs after the war in operating various bulletin
> boards) where a classically trained crystallographer semi-facetiously
> titled the thread "thermal factors - to be or not to be ?". When the
> debate subsided and the need for a new factor was agreed upon, it was
> only logical to call it the "B-factor" (actually, it was first called
> the "2B-factor" which differed from the modern B-factor by a factor of
> 2, but this was deemed too confusing)
>
> - the name "B-factor" was first coined by george sheldrick. by
> coincidence, he had just exhausted all the possible Fortran variable
> names starting with A (A, A1, A2, A3, ...) when he was about to
> implement isotropic thermal factor refinement in SHELX53. so the
> logical (and bold, if painful) step george took was to make this
> parameter the first in a (for him) whole new universe of Fortran
> variable names: B
>
> - it was invented by sacha baron cohen's great-grandfather. indeed,
> "B-factor" is an anagram of "Borat FC" ("fc" meaning "football club")
>
> i'm sure other ccp4bb-ers can come up with better explanations
>
> --dvd
>
> ******************************************************************
> Gerard J. Kleywegt
> [Research Fellow of the Royal Swedish Academy of Sciences]
> Dept. of Cell & Molecular Biology University of Uppsala
> Biomedical Centre Box 596
> SE-751 24 Uppsala SWEDEN
>
> http://xray.bmc.uu.se/gerard/ mailto:[log in to unmask]
> ******************************************************************
> The opinions in this message are fictional. Any similarity
> to actual opinions, living or dead, is purely coincidental.
> ******************************************************************
>
>
>
