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According to the paper, the data was refined in REFMAC in 'twin mode' which, I believe, calculates the R-factor using a  non-conventional R-factor equation which usually lower than the conventional R-factor. I believe this is dependent on the twin fraction which wasn't mentioned in the paper (or supplementary info) unless I missed it.

Jon

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Jonathan P. Schuermann, Ph. D.
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On 02/09/2011 05:11 PM, James Holton wrote:
[log in to unmask]" type="cite">This was "molecular replacement" from 1jb0, so the phases came from the model.  Probably more properly called "direct refinement" since all we did was a few cycles of rigid body.  Personally, I was quite impressed by how good the R factors were, all things considered.

-James Holton
MAD Scientist

On Wed, Feb 9, 2011 at 2:56 PM, Bernhard Rupp (Hofkristallrat a.D.) <[log in to unmask]> wrote:
Any idea where then phases came from?
BR

-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Thomas
Juettemann
Sent: Wednesday, February 09, 2011 12:16 PM
To: [log in to unmask]
Subject: Re: [ccp4bb] First images of proteins and viruses caught with an
X-ray laser

Thank you for clarifying this James. Those details are indeed  often
lost/misinterpreted when the paper is discussed in journal club, so your
comment was especially helpful.

Best wishes,
Thomas

On Wed, Feb 9, 2011 at 20:38, James Holton <[log in to unmask]> wrote:
>
> As one of the people involved (I'm author #74 out of 88 on PMID
> 21293373), I can tell you that about half of the three million
> snapshots were blank, but we wanted to be honest about the number that
> were collected, as well as the "minimum" number that were needed to
> get a useful data set.  The blank images were on purpose, since the
> nanocrystals were diluted so that there would be relatively few
> double-hits.  As many of you know, multiple lattices crash autoindexing
algorithms!
>
> Whether or not a blank image or a failed autoindexing run qualifies as
> "conforming to our existing model" or not I suppose is a matter of
> semantics.  But yes, I suppose some details do get lost between the
> actual work and the press release!
>
> In case anyone wants to look at the data, it has been deposited in the
> PDB under 3PCQ, and the detailed processing methods published under PMID:
> 20389587.
>
> -James Holton
> MAD Scientist
>
> On 2/9/2011 10:38 AM, Thomas Juettemann wrote:
>>
>> http://www.nanowerk.com/news/newsid=20045.php
>>
>> http://home.slac.stanford.edu/pressreleases/2011/20110202.htm
>>
>> I think it is pretty exciting, although they only take the few
>> datasets that conform to their existing model:
>>
>> "The team combined 10,000 of the three million snapshots they took to
>> come up with a good match for the known molecular structure of
>> Photosystem I."
>
>