>PS: I am grappling with the meaning of resolution in NMR. I can see that it
>could be related to comparable data/parameter ratios, although I am even
>less clear about the weights of NMR restraint weights than in the case of MX...
>some cross-trained person out there who can explain?
Dear Bernhar
On 12 January 2012 13:02, Weiergräber, Oliver H.
wrote:
> I think the problem is related to the term "coherence" being used to describe
> both the type of *radiation* and the mode of *scattering*.
> When talking about (xray) radiation, it denotes the phase relationship
> between photons, and the
ax: +49 2461 61-1448
From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] On Behalf Of Dirk Kostrewa
[kostr...@genzentrum.lmu.de]
Sent: Thursday, January 12, 2012 12:25 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] NMR review
I'm no
On 12 January 2012 11:25, Dirk Kostrewa wrote:
> I'm not a physicist - but isn't (in)coherence also used to describe the
> property of sources of electromagnetic waves with constant wavelength? For
> instance, an incoherent sodium vapour light source (only looking at one
> emission band) compared
I'm not a physicist - but isn't (in)coherence also used to describe the
property of sources of electromagnetic waves with constant wavelength?
For instance, an incoherent sodium vapour light source (only looking at
one emission band) compared to a coherent Laser, or the incoherent
emission from
On 12 January 2012 10:33, Dirk Kostrewa wrote:
> My understanding of coherence is a constant phase relation between waves.
Correct. For a perfect crystal all the unit cells are identical so
they scatter in phase
and this gives rise to the interference effect we see as Bragg spots,
as you say ari
> We don't see any change of frequency (or wavelength) in the majority
> of the scattering from disordered regions so it's Rayleigh (coherent)
> scattering. There will be a small amount of Compton (incoherent)
> scattering resulting from the ionisation events which are responsible
> for radiation
out of phase imply incoherent scattering? I though it means inelastic
Compton scattering?
-Original Message-
From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Dirk
Kostrewa
Sent: Thursday, January 12, 2012 1:58 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] NMR
-BEGIN PGP SIGNED MESSAGE-
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Dear Bernhard,
without ever having looked at an NMR experiment, intuitively the
resolution of an NMR experiment should be given as the magnitude of the
minimal chemical shift that could be observed/distinguished. Beware that
'resolution' does not nece
On 12 January 2012 09:57, Dirk Kostrewa wrote:
> That doesn't sound wrong to me: the flexible parts are at different relative
> positions in the unit cells and thus their "partial-structure scattering
> waves" do not have a constant phase relation to each other, i.e., they don't
> give a coherent
] NMR review
Dear Bernhard,
Am 12.01.12 10:30, schrieb Bernhard Rupp (Hofkristallrat a.D.):
> Dear All,
>
> I read an interesting statement in an NMR review:
>
> " regions of a protein or
> DNA / RNA molecule that are ?exible in the crystal do not provide
> coherent
Dear Bernhard,
Am 12.01.12 10:30, schrieb Bernhard Rupp (Hofkristallrat a.D.):
Dear All,
I read an interesting statement in an NMR review:
" regions of a protein or
DNA ⁄ RNA molecule that are flexible in the crystal do
not provide coherent X-ray scattering and hence do
not contribute to th
Dear All,
I read an interesting statement in an NMR review:
" regions of a protein or
DNA ⁄ RNA molecule that are flexible in the crystal do
not provide coherent X-ray scattering and hence do
not contribute to the final electron density map. Thus,
for all intents and purposes, they can effectiv
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