Dear all,
I find myself posed with a rather interesting if somewhat confusing problem.
Two crystals grown from the same conditions, let's call them A and B..
A:
Resolution 2.1A
SpacegroupP4?
Rmerge0.137 (0.324)
Mean((I)/sd(I)) 41.0 (17.8)
Completeness
Apologies, I think I neglected to attach the wilson plots...I'll do so
on Friday.
best,
Iain
Iain Kerr wrote:
Dear all,
I find myself posed with a rather interesting if somewhat confusing
problem.
Two crystals grown from the same conditions, let's call them A and B..
A:
Resolution
Thanks very much for all the suggestions so far.
While I am pursuing all the checks and balances for twinning here are
the Wilson plots I forgot to attach before..I am not sure what is going
on, especially in B !
best,
Iain
On Oct 25 2007, Iain Kerr wrote:
Dear all,
I find myself pose
Wilson plots are not very informative for the detection of twinning.
The spikes you see in your Wilson plots, could be due to ise ring
issues (both 3.89 and 2.24 A are at ice ring related d scapings.) The
very large mean intensity in those resolution shells could be due to
the fact that only str
> the Nz test says no twinning
and the intensity stats say this as well.
> but the Britton and H-plots give a twin fraction of
> 0.46-0.47 !
The britton and H test give an estimate of the twin fraction IF THE
DATA IS WOULD BE TWINNED. The fact it gives a non zero value does not
indicate the pres
Well - the wilson plots only indicate ice rings - they dont tell much
about twinning, except that I would prob restrict the tests to exclude
the suspect data.
( use resolution range low - to 3.5 for one, low - 2.4 for the other or
some such..)
The moments are the best indicators providing th
On Mon, 29 Oct 2007, Iain Kerr wrote:
The cumulative intensity distribution plot from crystal A did suggest
partial twinning (attached, doesn't look too bad though..)
notwithstanding other plots/statistics, does the cum. intens. dist. plot
(e.g. from truncate) really show a continuum from untw
al Message-
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of
Bryan W. Lepore
Sent: 30 October 2007 17:29
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] Pseudo-merohedral twinning and Molecular
replacement
On Mon, 29 Oct 2007, Iain Kerr wrote:
> The cumulative intensity distrib
The cumulative intensity depends on correctly estimating weak
reflections, so it is a bit vulnerable to the integration procedures.
I prefer the 4th moment of E - 2nd moment of I. Providing there is no
pseudo-translation they are pretty reliable indicators of twinning
Eleanor
Bryan W. Lepore
On Mon, 29 Oct 2007, Iain Kerr wrote:
The cumulative intensity distribution plot from crystal A did suggest partial
twinning (attached, doesn't look too bad though..)
notwithstanding other plots/statistics, does the cum. intens. dist. plot (e.g.
from truncate) really show a continuum from untw
I am a big fan of the RvR statistic
(http://journals.iucr.org/d/issues/2006/01/00/ba5089/index.html)
This statistic is very usefull when a model is available.
When no model is present, the L test is nice as well and is relatively
robust in the presence of pseudo centring.
P
2007/10/31, Elean
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