Dear Pavel, I believe words have a meaning, but they are not defined. This may make languages a little more demanding than mathematics, since you have to deal with a variety of a few hundred thousand to millions, depending how popular the language in question is, but personally I enjoy the challenge.
W.r.t. the thread, 3.8A resolution is poorer than 1.8A. I understand this is what John meant to clarify. Best, Tim On Sunday, February 5, 2017 11:12:10 AM CET Pavel Afonine wrote: > Hi Tim, hi Natesh, > > one expression is mathematically, the other one is technically 'more > > > correct'. > > I favour the terms poor and good resolution to avoid confusion, or > > explicitly > > list the values. > > just out of curiosity.. what's your definition of 'poor' and 'good' > resolutions? I suspect there are as many definitions as many subscribers to > this list are -;) > > One way to quantify resolution is that what kind of detail you can see in > the map, like for example: > > - deformation density (~0.7A and higher) = ultra-high, sub-atomic, > sub-Angstrom; > - H atoms (~0.9A and higher) = not sure what the name is; > - individual non-H atoms (~1.2A and higher) = atomic; > - hole in rings (~2A and higher?) = high; > - medium; > - still can see side chains (up to 4.5A); > - no side-chains but SS elements (such as tubes of density for helices) = > low > - no SS, molecular envelopes = very low. > > Note, resolution alone is not a good measure though. Data completeness is > similarly important, e.g. a map corresponding to 2A resolution may look > like a 3ish A resolution if you miss some low-resolution data or > high-resolution end is severely incomplete (Acta Cryst. (2014). D70, > 2593-2606). > > Low resolution --> worse than 2.7 A > > > Ultra high resolution --> better than 0.95 A > > Looking into this in some systematic way one can define low-resolution as > 6A and lower, and ultra-high resolution as 0.7A and higher (Page 1291: Acta > Cryst. (2009). D65, 1283–1291). > > All the best, > Pavel -- -- Paul Scherrer Institut Tim Gruene - persoenlich - OFLC/102 CH-5232 Villigen PSI phone: +41 (0)56 310 5297 GPG Key ID = A46BEE1A
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