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CCP4 bulletin board <[log in to unmask]> wrote on 08/17/2007 07:38:00 AM: > > Thus, I analyzed the distribution of the experimental sigmas in three > structures: > 1E3M and two structures of mine at the same resolution (1CTN, 1E3M) > > The results are in: > > http://xtal.nki.nl/nature-debate/ > > To add my two cents to Tassos' very enlightening graphs, I'll just say that the reflections with enormous F/sigF are probably generated by lines like this in the cif file: 1 1 1 -57 31 21 o 63.4 ****** I believe the asterisks are supposed to represent a sigma(F) > 10,000, since there are sigmas all the way up to that limit in the file. Granted, this is supposed to be a high-resolution reflection, but I'm not aware of any data processing program which will output reflections with F/sigF less than 0.006! Indeed, I just looked through one of my old datasets processed with HKL2000, then Truncate, and confirmed that my F/sigF drops smoothly and asymptotically to 1, and not below. The paper in question says they used HKL2000 followed by CCP4 programs for MR and refinement, so you'd expect something similar, no? There are lots of odd F/sigF in the 2hr0 cif file - even excluding the reflections with 0.0 or *** for a sigF, there are still 14 reflections with an F/sigF less than 0.01, 1028 reflections with F/sigF < 0.1, and 12626 reflections (6.5% of the total) with F/sigF < 1. I think this is even more unusual than the sharp upper limit of the F/sigF distribution. - Matt PS. The above are my views, not those of ImClone Systems, CCP4, the companies which send this email, the Boy Scouts, or any other organization which I may be associated with now, in the past, or in the future :P -- Matthew Franklin , Ph.D. Senior Scientist, ImClone Systems 180 Varick Street, 6th floor New York, NY 10014 phone:(917)606-4116 fax:(212)645-2054 Confidentiality Note: This e-mail, and any attachment to it, contains privileged and confidential information intended only for the use of the individual(s) or entity named on the e-mail. If the reader of this e-mail is not the intended recipient, or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that reading it is strictly prohibited. If you have received this e-mail in error, please immediately return it to the sender and delete it from your system. Thank you.