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:CCP4BB@JISCMAIL.AC.UK] Im Auftrag von Tim Gruene Gesendet: Donnerstag, 13. Februar 2014 16:22 An: CCP4BB@JISCMAIL.AC.UK Betreff: Re: [ccp4bb] create a lower resolution data set by truncating a high resolution data -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 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: blaine-moo...@ouhsc.edu > > 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 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iD8DBQFS/OMOUxlJ7aRr7hoRAmShAJ9ML9rKT1IiW8FGa+j748FYmAegHwCgmDGK zmPCnjjlQ2vVbXSh4FMPvG4= =RXur -----END PGP SIGNATURE-----
