Re: [ccp4bb] Free Reflections as Percent and not a Number

2014-11-28 Thread Tim Gruene
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Dear Jacob, you don't necessarily want to find the global minimum - the global minimum of the target function might be an overfitted set of parameters. At low resolution the (local) minimum you do want to reach may not be very sharp. This is best

[ccp4bb] Job posting: Postdoc Lead Discovery at Bayer in Berlin

2014-11-28 Thread Christian Stegmann
Dear all, we have an open postdoc position at Bayer in Berlin. This postdoc is embedded in a collaborative academic and industrial research consortium (IMI K4DD). Please submit job applications at www.career.bayer.de . Best wishes, Christian PostDoc Lead Discovery (m/f) YOUR TASKS AND

Re: [ccp4bb] Treating Missing Reflections as Zero or Fcalc

2014-11-28 Thread Tim Gruene
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Dear Gregg, your post raised my curiosity and I look at the map after a round of refinement with shelxl. I thought you might be interested in two observations: 1) shelxl refines the occupancy of the 1Q1 ligand to 60% rather than 78% (I don't think

Re: [ccp4bb] Treating Missing Reflections as Zero or Fcalc

2014-11-28 Thread Gregg Crichlow
Dear Tim, Thank you for your quick review of the map, and your reply. Actually, I always check every water molecule manually one by one before finalizing my structures because I know that automated algorithms often get them wrong, and also often place waters in ligand density. I'm away from

Re: [ccp4bb] Free Reflections as Percent and not a Number

2014-11-28 Thread Ian Tickle
Tim, Overfitting has nothing to do with whether or not the refinement is at the global (or local) minimum. You can predict how much a model will be overfitted before you even start the refinement, because it has everything to do with choices you made or were forced upon you right at the

Re: [ccp4bb] Free Reflections as Percent and not a Number

2014-11-28 Thread Tim Gruene
Dear Ian, On Fri, Nov 28, 2014 at 11:26:03AM +, Ian Tickle wrote: [...] Overfitting has nothing to do with whether or not the refinement is at the global (or local) minimum. [...] I don't think I said that. Let's assume for a moment that you are right and optimisations should be

Re: [ccp4bb] Treating Missing Reflections as Zero or Fcalc

2014-11-28 Thread Alexandre OURJOUMTSEV
Dear Gregg and Tim, Thank you for an interesting discussion and data. It may be useful to point out, in particular for other readers of the CCP4bb, that there are a couple of relevant issues (the role of a few missed reflections on a quality of images and the choice of the cut-off level when

[ccp4bb] New postdoctoral position available at the HZB-BESSY II MX group in Berlin, Germany

2014-11-28 Thread Müller , Uwe
The MX-group at HZB/BESSY II (Berlin) is operating three beamlines for macromolecular crystallography (see: http://www.helmholtz-berlin.de/bessy-mx) . These facilities are currently the most productive MX-stations in Germany with more 200 new PDB-entries annually. The facilities are used by

Re: [ccp4bb] Treating Missing Reflections as Zero or Fcalc

2014-11-28 Thread Bryan Lepore
On Nov 28, 2014, at 00:22, Gregg Crichlow gregg.crich...@gmail.com wrote: ... The paper now has been published, ... PDB ID 4K9G. ... The primary citation in the PDB summary is (2014) INT J ONCOL. 45: 1457-1468 ... unless any others are worth mentioning here... -Bryan

[ccp4bb]

2014-11-28 Thread rohit kumar
Dear all, i am solving a structure of 2.5 A resolution by PHASER but every time i got this following warning. $TEXT:Warning: $$ Baubles Markup $$ - Large non-origin Patterson peak indicates that translational

[ccp4bb] Fwd: [ccp4bb]

2014-11-28 Thread rohit kumar
Dear all, i am solving a structure of 2.5 A resolution by PHASER but every time i got this following warning. $TEXT:Warning: $$ Baubles Markup $$ - Large non-origin Patterson peak indicates that translational

[ccp4bb] PHASER warning

2014-11-28 Thread rohit kumar
Dear all, i am solving a structure of 2.5 A resolution by PHASER but every time i got this following warning. $TEXT:Warning: $$ Baubles Markup $$ - Large non-origin Patterson peak indicates that translational

[ccp4bb]

2014-11-28 Thread Randy Read
Hi, Working with Phaser in the presence of tNCS is not necessarily as automatic as in the absence of tNCS. It can be rather complicated, and not all decisions are necessarily made correctly. So I would suggest reading some new documentation on this:

Re: [ccp4bb] Fwd: [ccp4bb]

2014-11-28 Thread Eleanor Dodson
Are you testing all SGs? for your known point group? Eleanor On 28 November 2014 at 13:34, rohit kumar rohit...@gmail.com wrote: Dear all, i am solving a structure of 2.5 A resolution by PHASER but every time i got this following warning. $TEXT:Warning: $$ Baubles Markup $$

Re: [ccp4bb] Fwd: [ccp4bb]

2014-11-28 Thread rohit kumar
yes...right know its monoclinic (p21) space gp. On Fri, Nov 28, 2014 at 7:24 PM, Eleanor Dodson eleanor.dod...@york.ac.uk wrote: Are you testing all SGs? for your known point group? Eleanor On 28 November 2014 at 13:34, rohit kumar rohit...@gmail.com wrote: Dear all, i am solving a

Re: [ccp4bb] PHASER warning

2014-11-28 Thread Rebuffet Etienne
Dear Rohit, Are you sure about your space group? I think you should look at this first Hope it helps. Etienne Etienne Rebuffet, PhD Tel: +334 86 97 73 34 Laboratory of 'integrative Structural Chemical Biology (iSCB)' Cancer Research Center of Marseille (CRCM) CNRS UMR 7258; INSERM U 1068;

Re: [ccp4bb] Fwd: [ccp4bb]

2014-11-28 Thread Eleanor Dodson
And what is the NC translation vector (in fractional coordinates)? If it is x, 1/2, z then your SG could be P2 - the NC translation will generate absences along the 0k0 diffraction vector. Eleanor On 28 November 2014 at 14:01, rohit kumar rohit...@gmail.com wrote: yes...right know its

[ccp4bb] Postdoctoral position, Bethesda MD, Henry Jackson Foundation

2014-11-28 Thread Linda Miallau
A postdoctoral position is immediately available within the Henry Jackson Foundation at the Uniformed Services University of the Health Sciences across the NIH in Bethesda, Maryland, to work on toxin-antitoxin complexes of *Mycobacterium tuberculosis *under the supervision of Dr Linda Miallau.

Re: [ccp4bb] Free Reflections as Percent and not a Number

2014-11-28 Thread Pavel Afonine
Hi Tim, you don't necessarily want to find the global minimum (...) this contradicts the definition of crystallographic structure refinement. If finding the global minimum is not what you ultimately want then either the refinement target or model parameterization are poor. Clearly, given

Re: [ccp4bb] Free Reflections as Percent and not a Number

2014-11-28 Thread Tim Gruene
Dear Pavel, there is a beautiful paper called 'Where freedom is given, liberties are taken' by Kleywegt and Jones, but also a wide variety of articles that (fortunately) fought hard for the introduction of Rfree to the (macro-)crystallographic community. In there is mentioned the threading of an

Re: [ccp4bb] Free Reflections as Percent and not a Number

2014-11-28 Thread Ian Tickle
On 28 November 2014 at 19:40, Tim Gruene t...@shelx.uni-ac.gwdg.de wrote: Where freedom is given, liberties are taken' by Kleywegt and Jones Tim First to summarise the correct procedure: One performs optimisations with one of more starting models. By 'model' I mean here the mathematical

Re: [ccp4bb] Free Reflections as Percent and not a Number

2014-11-28 Thread Pavel Afonine
Hi Tim, your examples are valid and valuable, and clearly exemplify existing problems, limitations as well as common misconceptions. However, if you follow mathematics and strict definitions thereof, then crystallographic structure refinement is nothing but an optimization problem that,