Hi Tim,
Maybe it's too early in the day for me, but why can't electrons be a unit? You
seem to be confusing physical (in-)divisibility of an entity with the symbolic
use of fractions of that entity in calculations. We can speak of the average
number of cows per acre of land without having to cut up cows into small pieces
(although I love a good steak as much as the next person - and probably a lot
more than that), or the average number of people on a plane without having to
remove some limbs of a particular person to represent that number (although
amputation of my legs would make my journeys a lot more comfortable in terms of
legroom).
--dvd
Disclaimer: this answer does not involve any (mention of) CCP4 software. Mea
culpa.
On Fri, 26 Feb 2010, Tim Gruene wrote:
Dear all,
I just stumbled across the question about what is the unit of f' and f''.
The
first couple of hits from ixquick.com claim it was e^-. Since e^- is not a
unit
but symbolises an elemtary particle (of which fractions are considered
non-existent), I was wondering whether the unit of f, f', and f'' is actually
e
(a positive charge!) and the value of f^0 of Fe at its K-edge was actually
26e
or -26e - see e.g. Table 1 in
http://www.ccp4.ac.uk/courses/proceedings/1997/j_smith/main.html
Cheers, Tim
--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
GPG Key ID = A46BEE1A
Best wishes,
--Gerard
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Gerard J. Kleywegt
Dept. of Cell & Molecular Biology University of Uppsala
Biomedical Centre Box 596
SE-751 24 Uppsala SWEDEN
http://xray.bmc.uu.se/gerard/ mailto:[email protected]
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