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<p>Hi Stelnar,</p>
<p><br>
</p>
<p>Perhaps you have double (overlapping) particles, as a result of
double picking or translations during refinement for example. A
quick way to check for this is to make particle half-sets from
different tomograms (split tomograms in two groups and make each
half particle set from one group). In this way, double particles
will always be in the same particle half-set. If the FSC between
these halves goes to 0, it's double particles.</p>
<p><br>
</p>
<p>Just a guess, hope it helps</p>
<p><br>
</p>
<p>Best,</p>
<p>Vladan<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 11/2/18 5:44 PM, Steinar Halldorsson
wrote:<br>
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<p style="margin-top:0;margin-bottom:0">Hi all</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
<p style="margin-top:0;margin-bottom:0">I have something which
looks like an artefact in my FSC curves from tomography data
calculated in Relion. Basically the curves hover around 0.1
instead of reaching 0... And this is not coming from my mask
btw. There is quite a lot of information (protein) outside of
the mask, you can see clear but slightly smeary density from
neighbours in the final maps, and I wonder if this is causing
these correlations? One way I have thought to test this is to
take my two half maps, somehow add random noise to parts
outside of my region of interest and then recalculate my FSC. </p>
<p style="margin-top:0;margin-bottom:0"><br>
Firstly, does this sound like a reasonable thing to try?<br>
Secondly, does anyone have a suggestion of how to actually do
the random noise addition outside of my region of interest?<br>
<br>
Cheers,</p>
<p style="margin-top:0;margin-bottom:0">Steinar</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
<p style="margin-top:0;margin-bottom:0">---</p>
<p style="margin-top:0;margin-bottom:0">Steinar Halldorsson</p>
<p style="margin-top:0;margin-bottom:0">Postdoctorate Fellow</p>
<p style="margin-top:0;margin-bottom:0">Rosenthal lab</p>
<p style="margin-top:0;margin-bottom:0">The Francis Crick
Institute<br>
London, United Kingdom</p>
</div>
<p style="color:rgb(112,113,115);font-family: 'Trebuchet MS',
'Lucida Grande'; font-style: italic; font-size: 10pt;">
The Francis Crick Institute Limited is a registered charity in
England and Wales no. 1140062 and a company registered in
England and Wales no. 06885462, with its registered office at 1
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