Dear Herman, this might work. To get more realistic scaling/ merging statistics, one should expand to P1, add independent noise to U's and coordinates, create the hkl and force it back into the original symmetry.
Best, Tim On 02/13/2014 04:38 PM, [email protected] wrote: > By applying a high temperature factor, one should not suffer Fourier ripples, > since the "missing" high resolution reflections have negligible intensities, > or put differently, one simulates a poorly diffracting crystal. > > Best, > Herman > > -----Ursprüngliche Nachricht----- > Von: CCP4 bulletin board [mailto:[email protected]] Im Auftrag von Tim > Gruene > Gesendet: Donnerstag, 13. Februar 2014 16:22 > An: [email protected] > Betreff: Re: [ccp4bb] create a lower resolution data set by truncating a high > resolution data > > Dear Blaine Mooers, > > I don't think that you avoid Fourier ripples with this method. You may, > however, increase the noise level so that the Fourier ripples drown in the > noise. > > You don't really generate a low resolution data set by truncation for that > very reason. Crystals that only diffract to 3.5A, say, usually do this > because of a high degree of disorder with leeds to more noise. > > Of course you could add noise to the sigma-values, but this is merely > cosmetics. > > There are repositories for frames (JCSG?), where you might want to get real > data that diffract to the desired resolution, reprocess and then carry out > the phasing experiments. > > Best, > Tim > > On 02/13/2014 03:54 PM, Mooers, Blaine H.M. (HSC) wrote: >> For some simulated phasing experiments, I want to create a lower >> resolution diffraction data set by truncating a high resolution data >> set. I would like to avoid Fourier ripples due to the truncation of >> the high resolution data by downscaling the data such that >> <I/sigma>=2.0 in the highest resolution shell of the truncated data. >> What is the best way to do this? > >> Blaine Mooers Assistant Professor Department of Biochemistry and >> Molecular Biology University of Oklahoma Health Sciences Center S.L. >> Young Biomedical Research Center Rm. 466 > >> Shipping address: 975 NE 10th Street, BRC 466 Oklahoma City, OK >> 73104-5419 > >> Letter address: P.O. Box 26901, BRC 466 Oklahoma City, OK 73190 > > >> office: (405) 271-8300 lab: (405) 271-8313 fax: (405) 271-3910 >> e-mail: [email protected] > >> Faculty webpage: >> http://www.oumedicine.com/department-of-biochemistry-and-molecular-bio >> logy/faculty/blaine-mooers-ph-d- > >> X-ray lab webpage: >> http://www.oumedicine.com/department-of-biochemistry-and-molecular-bio >> logy/department-facilities/macromolecular-crystallography-laboratory > >> Small Angle Scattering webpage: >> http://www.oumedicine.com/docs/default-source/ad-biochemistry-workfile >> s/small-angle-scattering-links.html?sfvrsn=0 > > > -- Dr Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A
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