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--></style></head><body bgcolor="white" lang="EN-AU" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Hi Henning,</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Is the behaviour specific of the imaging conditions you describe or can you see a similar result at other magnifications?</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">We had some grounding issues that displayed a similar behaviour. It took some time to get to the root of it.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">In our case the resolution cut was independent from the magnification, but fixed at about 2/3 Nyquist,</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Best</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Alex</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p><div><div style="border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> 3dem [mailto:<a href="mailto:3dem-bounces@ncmir.ucsd.edu">3dem-bounces@ncmir.ucsd.edu</a>] <b>On Behalf Of </b>Mark Ebrahim<br><b>Sent:</b> Friday, 12 May 2017 6:05 AM<br><b>To:</b> Henning Stahlberg <<a href="mailto:henning.stahlberg@unibas.ch">henning.stahlberg@unibas.ch</a>>; 3dem <<a href="mailto:3dem@ncmir.ucsd.edu">3dem@ncmir.ucsd.edu</a>><br><b>Subject:</b> Re: [3dem] Request for help to find source of resolution loss in cryo-EM</span></p></div></div><p class="MsoNormal"> </p><p><span style="font-family:"Calibri",sans-serif;color:black">Hi Henning,</span></p><p><span style="font-family:"Calibri",sans-serif;color:black"> </span></p><p><span style="font-family:"Calibri",sans-serif;color:black">Greetings from New York. </span></p><p><span style="font-family:"Calibri",sans-serif;color:black"> </span></p><p><span style="font-family:"Calibri",sans-serif;color:black">This is an interesting photo. How reproducible is this behavior? </span></p><p><span style="font-family:"Calibri",sans-serif;color:black"> </span></p><p><span style="font-family:"Calibri",sans-serif;color:black">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.</span></p><p><span style="font-family:"Calibri",sans-serif;color:black"></span></p><p><span style="font-family:"Calibri",sans-serif;color:black"> </span></p><p><span style="font-family:"Calibri",sans-serif;color:black">Best,</span></p><p><span style="font-family:"Calibri",sans-serif;color:black">Mark</span></p><p><span style="font-family:"Calibri",sans-serif;color:black"> </span></p><div id="Signature"><div name="divtagdefaultwrapper"><div class="MsoNormal" align="center" style="text-align:center"><strong><span style="font-family:"Calibri",sans-serif;color:black"><hr size="2" width="100%" align="center"></span></strong></div><p class="MsoNormal"><strong><span style="font-family:"Calibri",sans-serif;color:black">Mark Ebrahim</span></strong><span style="font-family:"Calibri",sans-serif;color:black"> </span></p><p><span style="font-family:"Calibri",sans-serif;color:black">Senior Staff Scientist</span></p><p><span style="font-family:"Calibri",sans-serif;color:black">Cryo Electron Microscopy Resource Center (CEMRC)</span></p><div><p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">The Rockefeller University</span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">1230 York Avenue</span></p></div><div><p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">New York, NY 10065</span></p></div></div></div><div><div class="MsoNormal" align="center" style="text-align:center"><span style="font-family:"Calibri",sans-serif;color:black"><hr size="2" width="98%" align="center"></span></div><div id="divRplyFwdMsg"><p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black"> 3dem <<a href="mailto:3dem-bounces@ncmir.ucsd.edu">3dem-bounces@ncmir.ucsd.edu</a>> on behalf of Henning Stahlberg <<a href="mailto:henning.stahlberg@unibas.ch">henning.stahlberg@unibas.ch</a>><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</span><span style="font-family:"Calibri",sans-serif;color:black"> </span></p><div><p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"> </span></p></div></div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-family:"Calibri",sans-serif;color:black">Hi,<br><br>We have a strange problem on one of our instruments (Titan Krios with Quantum-LS GIF and K2 Summit in counting mode).<br>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>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>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><br>Does anybody have an idea what could cause such a behavior?<br><br>Thanks,<br><br>Henning.<br><br><br></span></p><div><p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-family:"Calibri",sans-serif;color:black">Henning Stahlberg, PhD<br>Prof. for Structural Biology, C-CINA, Biozentrum, University Basel<br>Mattenstrasse 26 | D-BSSE | WRO-1058 | CH-4058 Basel | Switzerland<br><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=">http://c-cina.org</a> | Tel. +41-61-387 32 62<br><br></span></p></div><p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><img border="0" width="876" height="856" id="_x0030_66316CC-995C-4F56-A073-8679AD175598" src="cid:image001.jpg@01D2CAE6.BDBC9FB0"></span></p></div></div></div></body></html>