> 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
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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]
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The opinions in this message are fictional. Any similarity
to actual opinions, living or dead, is purely coincidental.
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