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<p>Hi Henning,</p>
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<p>Greetings from New York. </p>
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<p>This is an interesting photo. How reproducible is this behavior? </p>
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<p>My first step would be to insert a cross grating and have a look at the information limit; after seeing that we could start to theorize what the problem could really be.<br>
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<p>Best,<br>
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<p>Mark<br>
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<p><font face="Calibri,Arial,Helvetica,sans-serif"><strong></strong></font></p>
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Mark Ebrahim</strong></font>
<p><font face="Calibri,Arial,Helvetica,sans-serif">Senior Staff Scientist</font></p>
<p><font face="Calibri,Arial,Helvetica,sans-serif">Cryo Electron Microscopy Resource Center (CEMRC)</font></p>
<div style="margin:0px"><span style="font-size:11pt"><font face="Calibri,Arial,Helvetica,sans-serif" size="3">The Rockefeller University</font></span></div>
<div style="margin:0px"><span style="font-size:11pt"><font face="Calibri,Arial,Helvetica,sans-serif" size="3">1230 York Avenue</font></span></div>
<div style="margin:0px"><span style="font-size:11pt"><font face="Calibri,Arial,Helvetica,sans-serif" size="3">New York, NY 10065</font></span></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> 3dem <3dem-bounces@ncmir.ucsd.edu> on behalf of Henning Stahlberg <henning.stahlberg@unibas.ch><br>
<b>Sent:</b> Thursday, May 11, 2017 9:08 AM<br>
<b>To:</b> 3dem<br>
<b>Subject:</b> [3dem] Request for help to find source of resolution loss in cryo-EM</font>
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<div>Hi,<br class="">
<br class="">
We have a strange problem on one of our instruments (Titan Krios with Quantum-LS GIF and K2 Summit in counting mode).<br class="">
When recording images at low mag (1.04 A/px for the 4k images) and low-dose conditions of a partly devitrified sample, and compute the FFTs, we can see the 3.7A ice ring and also the second-order 2.1A ice ring, sometimes a third-order ring in the corners at
1.7A resolution.<br class="">
We recently observed a resolution loss visible in the FFTs only in the vertical direction, shown by an amplitude decay in the upper and lower quarter of the FFTs. <br class="">
However, while the 3.7A ring shows that anisotropic resolution loss, the 2.1A ring is still isotropically present. An example image is attached.<br class="">
<br class="">
Does anybody have an idea what could cause such a behavior?<br class="">
<br class="">
Thanks,<br class="">
<br class="">
Henning.<br class="">
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<br class="">
<br class="">
<div class="">Henning Stahlberg, PhD<br class="">
Prof. for Structural Biology, C-CINA, Biozentrum, University Basel<br class="">
Mattenstrasse 26 | D-BSSE | WRO-1058 | CH-4058 Basel | Switzerland<br class="">
<a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__c-2Dcina.org&d=DwMFAg&c=JeTkUgVztGMmhKYjxsy2rfoWYibK1YmxXez1G3oNStg&r=yFrUlH9O04U9FBwxVIdysCYHghM3ThWbjLvKfnev9gQ&m=O8br31vcM9PsZG9JLWoGbKKE3Fn8LksrXXsWo0uQeuo&s=gD8H_SbRDYBegOWKgL_wUmFQV274mYNF8p4Ayx3Mxho&e=" class="">http://c-cina.org</a>
| Tel. +41-61-387 32 62<br class="">
<br class="">
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