Dear Jacob,
That's a good question, as you can see from the amount of debate you've
inspired. There have been a lot of good answers already.
Depending on how your intuition works, you might prefer Gerard's explanation in
terms of convolutions, or Bart's in terms of the size of errors in the el
Dear Francis Reyes,
from the self-rotation function at kappa=120 degrees, you can see that
one threefold NCS axis is perpendicular to a crystallographic twofold
axis. I haven't worked this out for your particular case, but the
combination of a threefold (n-fold) NCS axis perpendicular to a
cr
... and here a slightly clearer version where I numbered the NCS-related
positions 1,2,3 and their crystallographic equivalent positions
1',2',3', which makes the NCS dyads a bit easier to understand ...
Sorry for sending two pictures.
Best regards,
Dirk.
Am 19.03.10 10:31, schrieb Dirk Kost
On Thu, Mar 18, 2010 at 10:36 PM, Edward A. Berry wrote:
> I have been politely reminded offline that by definition amplitudes
> cannot be negative. We could call them coefficients, but:
Hi Edward
This obviously depends on whether you're talking about the physical
entity 'amplitude' or the quant
Hi all
I'd like to add a phase error to my PHIB's and FOM's (experimental phases) that
increases linearly with higher resolution.. it's akin to taking good phases and
making them bad. Any approaches on how this can be done?
Thanks
FR
-
Francis Reyes M
Dirk, I'm not sure this is right, the NCS 2-folds clearly occur at phi
= 45, 135 ..., not at phi = 30, 150 ... as required by your
explanation. Also you haven't explained the very clear peaks near
theta = 45, phi = 0. 90 ... . I won't be convinced until I see the
results from RFCORR!
Cheers
--
Hi Ian,
o yes, I didn't work out the particular case that Francis Reyes was
asking for, but intended to give a more general idea where additional
twofold NCS axes could come from, by a combination of a NCS axis
perpendicular to a crystallographic twofold axis. The image should just
support th
On Thu, 2010-03-18 at 12:51 -0500, Jacob Keller wrote:
> Does anybody have a good way to understand this?
Sure, it just depends on what would one consider a "good" way to
understand. For a pure empiricist, it's good enough to see one of those
two-dimensional phase swap pictures. For a "mathemat
Dear Critton
We have done a case, which was to remove the ligand A from the crystal in
complex with ligand B and metal ions. Please see the link of this case below
(Methods).
http://www.ncbi.nlm.nih.gov/pubmed/20139160
Cheers,
Tao-Hsin
Just sending along the answers to my question about the imosflm crystal
missets and mosaicity plot from Ethan Meritt and Harry Powell.
>Value of the parameter as a function of diffraction image number.
If the parameter didn't vary, it would show as a horizontal line.
phi(x), etc are the crystal
Francis, I would at least compute all the maps to the same resolution,
and as I suggested earlier use all the Fobs data you have, and finally
try using E's. The differences could be due to the solvent model (or
lack of it) in the Fcalc's, though I concede that doesn't explain the
difference betwee
You want to have an intuitive picture without
any mathematics and theorems, here it is:
each black spot you measure on the detector is
the square of an amplitude of a wavelet. The amplitude
says simply how much the wavelet goes up and down
in space.
Now, you can imagine that when you have many
wav
Hi Francis,
On Thu, Mar 18, 2010 at 09:03:13AM -0600, Francis E Reyes wrote:
> Hi all
>
> I have a solved structure that crystallizes as a trimer
I guess you mean that you have 3 mol/asu? And not just "a trimer in
solution that then forms crystals", right?
> to a reasonable R/Rfree, but I'm try
Perhaps this was really my question:
Do phases *necessarily* dominate a reconstruction of an entity from phases
and amplitudes, or are we stuck in a Fourier-based world-view? (Lijun
pointed out that the Patterson function is an example of a reconstruction
which ignores phases, although obvious
> Perhaps this was really my question:
>
> Do phases *necessarily* dominate a reconstruction of an entity from phases
> and amplitudes, or are we stuck in a Fourier-based world-view? (Lijun
> pointed out that the Patterson function is an example of a reconstruction
> which ignores phases, although
The great thing with diffraction, from crystals and
from objects in microscopy is THAT this is
A NATURALLY OCCURRING FORM of Fourier transform once
one accepts that light is a wave (could be something
else).
If Fourier transform would not have been invented with
another problem from engineering, th
Dear Marius,
Thank you for pointing this out - I was about to argue in the same
direction, i.e. that the Fourier transform is at the heart of diffraction
and is not just a convenient, but perhaps renegotiable, procedure for
analysing diffraction data.
Another instance of such natural "
Hi Tony,
maybe Glycon in Germany might be useful for you (www.glycon.de). They
sell bDDM for around 900 Euro/25 g and also can make bulk pricing on
request. We have been very happy with their quality in the past
(especially the content of alpha was lower than in products from other
companies)
Hi Francis,
Check out the CALC command in sftools. It allows you to apply quite a
number of mathematical operations on MTZ column data, including phases.
It also has built-in funtions to return the resolution of reflections
which you can use in your calculation. CALC HELP should explain how to
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