Herman
Thanks. 5-10 degrees is certainly high whatever definition one uses. In the list I gave, I didn't include "relative to the angular separation of the diffraction spots in reciprocal space." I would like to say that I didn't include it to see if anyone else came up with this one. In fact, I just forgot it. This definition is (I think) independent of the instrument and depends on things like the resolution of the data and the unit cell size. I guess I am coming to this from the point of view of separating out the intrinsic and instrument dependent features in order to identify the limitations of data collection procedures. Of course, this is no use at all to José who raised the original question so apologies to him and others who have addressed his question more directly. Regards Colin From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of [email protected] Sent: 28 January 2011 15:05 To: [email protected] Subject: Re: [ccp4bb] Merging data to increase multiplicity For me, it means a reflecting-range (as defined by XDS) of 5-10 or more degrees and spots being visible on at least 5 or more frames (when using 1° frames). Good crystals (in our hands) have reflection-ranges in the order of 0.5-1.0°. Of course we trust that the synchrotron where we measure (ESRF, SLS) has a well-colimated beam with low beam divergence etc. So I guess, my definition would be high relative to the rotation range. I hope this answers your question, Herman ________________________________ From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Colin Nave Sent: Friday, January 28, 2011 3:50 PM To: [email protected] Subject: Re: [ccp4bb] Merging data to increase multiplicity Can people say how "high mosaicity" is defined. High relative to what? Is it high relative to the rotation range for each image, high relative to the incident beam divergence, high relative to the (angular) detector resolution or something else? Regards Colin From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of [email protected] Sent: 28 January 2011 14:36 To: [email protected] Subject: Re: [ccp4bb] Merging data to increase multiplicity My experience (unpublished) is that XDS works very well for high-mosaicity crystals due to the 3-dimensional profile fitting. For low mosaicity crystals, I did not notice much of a difference between different programs. However, since bad crystals tend to have a high to very high mosaicity, I fully agree with Jürgens statement. Best regards, Herman ________________________________ From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Van Den Berg, Bert Sent: Friday, January 28, 2011 2:38 PM To: [email protected] Subject: Re: [ccp4bb] Merging data to increase multiplicity I have heard this before. I'm wondering though, does anybody know of a systematic study where different data processing programs are compared with real-life, non-lysozyme data? Bert On 1/28/11 7:58 AM, "Bosch, Juergen" <[email protected]> wrote: I was a bit reductive with my statement (iPhone....) The equation below is suppose to read: If you have bad data, then you need to process with XDS in order to get the maximum out of your data. Thanks Tim, Jürgen - Jürgen Bosch Johns Hopkins Bloomberg School of Public Health Department of Biochemistry & Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Phone: +1-410-614-4742 Lab: +1-410-614-4894 Fax: +1-410-955-3655 http://web.mac.com/bosch_lab/ <http://web.me.com/bosch_lab/> On Jan 28, 2011, at 7:44 AM, Tim Gruene wrote: Dear Jürgen, is this an assignment operator or an equal sign? For if it's the latter it could read that the result of processing data with XDS are bad data, which is rather rude and probably not what you meant. Tim On Fri, Jan 28, 2011 at 06:55:43AM -0500, Jürgen Bosch wrote: Bad data = processing with XDS Jürgen ...................... Jürgen Bosch Johns Hopkins Bloomberg School of Public Health Department of Biochemistry & Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Phone: +1-410-614-4742 Lab: +1-410-614-4894 Fax: +1-410-955-3655 http://web.mac.com/bosch_lab/ On Jan 28, 2011, at 6:46, José Trincão <[email protected]> wrote: Hello all, I have been trying to squeeze the most out of a bad data set (P1, anisotropic, crystals not reproducible). I had very incomplete data due to high mosaicity and lots of overlaps. The completeness was about 80% overall to ~3A. Yesterday I noticed that I could process the data much better fixing the mosaicity to 0.5 in imosflm. I got about 95% complete up to 2.5A but with a multiplicity of 1.7. I tried to integrate the same data fixing the mosaicity at different values ranging from 0.2 to 0.6 and saw the trend in completeness, Rmerge and multiplicity. Now, is there any reason why I should not just merge all these together and feed them to scala in order to increase multiplicity? Am I missing something? Thanks for any comments! Jose José Trincão, PhD CQFB@FCT-UNL 2829-516 Caparica, Portugal "It's very hard to make predictions... especially about the future" - Niels Bohr
