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I agree with Eleanor, I have often felt that crystallographic programs
evolve by Darwinian selection - the fitter versions (e.g. the ones that
get the hand right) survive and the others don't. Sometimes it is
difficult to explain why some approaches work better than others, but
natural selection wins in the end.
George
Eleanor Dodson wrote:
This is one of the advantages of much of the CCP4 code - it is old but
tested to destruction many times obver. As one of the original authors I
have made many many mistakes but a pretty substantial fraction have
probably now been found..
The main reason for the sign swap in F+ and F- though has been the
inconsistencies between different outputs from the Xray equipment, and
users selecting incorrect input defaults - Rigaku instead of Mar etc..
This should be avoided if the software read the Image headers but it has
been a long battle to a) get the headers written and b) get the software
to read it.
For the record the first two structures I worked on were on the wrong
hand. One through ignorance and the next through carelessness. But
pre-automatic building software we very soon noticed left handed helices..
Eleanor
Felix Frolow wrote:
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a. "To use XPLORE one need a license..."
Attributed to Harrison-Wiley laboratory folklore.
b. Another matter: for how many other data sets, for how many years
and by how many crystallographers misterious faulty home-made program
was used?
The name of the program should be stated as many of us her and there
are using programs still from our postdoctoral times which can go
back as far
as 25 - 30 years and maybe luck of "sky-rocket" careere for many of
us is due to use of such software.
Dr Felix Frolow
Professor of Structural Biology and Biotechnology
Department of Molecular Microbiology
and Biotechnology
Tel Aviv University 69978, Israel
Acta Crystallographica D, co-editor
e-mail: [EMAIL PROTECTED]
Tel: ++972-3640-8723
Fax: ++972-3640-9407
On Jan 7, 2007, at 4:25 AM, Charlie Bond wrote:
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Following the ABC transporter discussion, I thought I'd mention for
those who are not very experienced how easy it is to process data in
the wrong hand. It does not require faulty home-made programs, but
is quite possible with many established data processing programs.
All it takes is an error in maybe one of those parameters which you
don't normally change (something like YSCALE -1, for example).
Often at the synchrotron one is in a tired hurry to get an image
indexed and processed. If the wrong parameters are used (eg the ones
from the home lab with a bit of editing), a dataset in the wrong
hand can be quickly produced.
Increasingly beamlines automatically prepare the correct parameter
files for you, but it is cases where images are difficult to process
(low resolution, disorder) that processing may occur later at home
and the details of the beamline may be disregarded.
Correct me if I'm wrong, but even the deposition of images would not
help this as the critical information is the geometry of the
beamline set up which is probably not recored with the images.
Cheers,
Charlie
--
Charlie Bond
Professorial Fellow
University of Western Australia
School of Biomedical, Biomolecular and Chemical Sciences
M310
35 Stirling Highway
Crawley WA 6009
Australia
[EMAIL PROTECTED]
+61 8 6488 4406
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at the Tel-Aviv University CC.
--
Prof. George M. Sheldrick FRS
Dept. Structural Chemistry,
University of Goettingen,
Tammannstr. 4,
D37077 Goettingen, Germany
Tel. +49-551-39-3021 or -3068
Fax. +49-551-39-2582
