My preference is also for the full structure factor amplitude. I
would have said that I'd never seen the term structure amplitude used.
However, I just looked this up in my old Stout & Jensen (1968 edition
- brown cover) and find that (on p. 195) where |F| is introduced they
define it as: 'the most important quantity derived from the
intensities is the structure factor modulus (structure amplitude).
(Italics are theirs, not mine).
Sue
On Jan 12, 2009, at 8:37 AM, Andrew Purkiss-Trew wrote:
On Mon, 2009-01-12 at 10:42 +0000, Ian Tickle wrote:
I was taught 'structure amplitude' - makes perfect sense to me! Why
does 'structure amplitude' make any less sense than 'structure
factor'?
It also clearly made sense to Phil Coppens, a crystallographer of
considerable repute, see ITC Vol. B (2nd Ed.), sect 1.2., p.10: 'The
Structure Factor'. To quote the introduction to the section: "The
'structure factor' is the central concept in structure analysis by
diffraction methods. Its modulus is called the 'structure
amplitude'".
Also I did a 'Google vote' for the two terms. 'Structure
amplitude' has
11300 hits. 'Structure factor amplitude' has only 4750. So all
round I
would say that 'structure amplitude' wins by a considerable margin.
Having had a quick look at the google results myself, I think that
there
is a problem is the methodology. Google doesn't take into account
punctuation when searching. So the first search includes results
such as
'structure. Amplitude', where the two words are in different
sentences,
or 'structure, amplitude' where the words are part of a list. Given
this
case, the winning margin is likely to be less.
My preference would also be for the full 'Structure factor amplitude'.
'Structure amplitude' leaves me with visions of comparing the pdb
files
of a small single domain protein and a ribosome. Two structures having
different sizes (or amplitudes).
Cheers
-- Ian
-----Original Message-----
From: owner-ccp...@jiscmail.ac.uk
[mailto:owner-ccp...@jiscmail.ac.uk] On Behalf Of Pavel Afonine
Sent: 11 January 2009 03:01
To: Ethan A Merritt
Cc: CCP4BB@jiscmail.ac.uk
Subject: Re: [ccp4bb] structure (factor) amplitude
On 1/10/2009 5:14 PM, Ethan A Merritt wrote:
On Saturday 10 January 2009, Bernhard Rupp wrote:
Dear All,
I am getting conflicting comments on the use of
'structure factor amplitude'
vs. just
'structure amplitude'
for |F|.
???
That's just... odd.
|F| is the amplitude of F.
But no way F is a "structure".
I agree. If F is a structure factor then |F| is a structure
factor amplitude. "structure amplitude" doesn't make much sense...
Pavel.
Disclaimer
This communication is confidential and may contain privileged
information intended solely for the named addressee(s). It may not
be used or disclosed except for the purpose for which it has been
sent. If you are not the intended recipient you must not review,
use, disclose, copy, distribute or take any action in reliance upon
it. If you have received this communication in error, please notify
Astex Therapeutics Ltd by emailing i.tic...@astex-therapeutics.com
and destroy all copies of the message and any attached documents.
Astex Therapeutics Ltd monitors, controls and protects all its
messaging traffic in compliance with its corporate email policy.
The Company accepts no liability or responsibility for any onward
transmission or use of emails and attachments having left the Astex
Therapeutics domain. Unless expressly stated, opinions in this
message are those of the individual sender and not of Astex
Therapeutics Ltd. The recipient should check this email and any
attachments for the presence of computer viruses. Astex
Therapeutics Ltd accepts no liability for damage caused by any
virus transmitted by this email. E-mail is susceptible to data
corruption, interception, unauthorized amendment, and tampering,
Astex Therapeutics Ltd only send and receive e-mails on the basis
that the Company is not liable for any such alteration or any
consequences thereof.
Astex Therapeutics Ltd., Registered in England at 436 Cambridge
Science Park, Cambridge CB4 0QA under number 3751674
Dr. Sue A. Roberts
Biochemistry & Molecular Biophysics
University of Arizona
520 621 8171
s...@email.arizona.edu
http://www.biochem.arizona.edu/xray