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<p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Dear Friends,</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">We would like to invite you to One World Cryo-EM, an online seminar series about algorithms and mathematics in cryo-EM. We hope that these seminars will allow our community to catch up and welcome new members. </span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">First talk: </span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Cryo-EM and Helical Polymers: A Natural Affinity. </span></strong></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Edward H Egelman. </span></strong></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">September 23rd at 8am PT / 11am ET / 4pm BST / 5pm CEST / 11pm China, via Zoom</span></strong><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">. Join us 10 minutes early for informal tea time and to check that everything works. </span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Please register early</span></strong><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">: </span><a style="background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt;color:rgb(74,110,224)" target="_blank" href="https://urldefense.com/v3/__https://yale.zoom.us/meeting/register/tJApcu6grD4iGdFaQsDVdpJEaGD1oE-3VOjB__;!!Mih3wA!Tpypsbm9Jhum8Y9PdlhGu5QaxuU0znb-oUNm73O7NQrpnVr_Di7g23WCdqgLmn02eA$" class="gmail-_e75a791d-denali-editor-page-rtfLink"><span style="background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt;color:rgb(74,110,224)">https://yale.zoom.us/meeting/register/tJApcu6grD4iGdFaQsDVdpJEaGD1oE-3VOjB</span></a></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Unfortunately, we have to approve your free registration manually. Please register early using your institution or company email and with information that would help us verify that you are a human.</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Future seminars, every other Wednesday, will include additional networking and lightning talk opportunities.</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">See you there!</span></strong></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"> Joakim Andén</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"> Dorit Hanein</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"> Roy R. Lederman</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"> Steven J. Ludtke</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">For updates:</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Visit: <a href="https://urldefense.com/v3/__https://cryoem.world/__;!!Mih3wA!Tpypsbm9Jhum8Y9PdlhGu5QaxuU0znb-oUNm73O7NQrpnVr_Di7g23WCdqi8Pjk3IA$">https://cryoem.world/</a></span></strong></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Follow: @OWCryoEM</span></strong></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Join our mailing list (read-only announcements): <a href="https://urldefense.com/v3/__https://mailman.yale.edu/mailman/listinfo/ow_cryoem__;!!Mih3wA!Tpypsbm9Jhum8Y9PdlhGu5QaxuU0znb-oUNm73O7NQrpnVr_Di7g23WCdqgNXQxuwQ$">https://mailman.yale.edu/mailman/listinfo/ow_cryoem</a> .</span></strong></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">----------------------------</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Cryo-EM and Helical Polymers: A Natural Affinity</span></strong></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><strong style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Edward H Egelman</span></strong><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">, Professor, Biochemistry and Molecular Genetics, University of Virginia</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Date and time: 9/23/2020 Wednesday, at 8am PT / 11am ET/ 4pm BST / 5pm CEST / 11pm China</span></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">Please register in advance: </span><a style="background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt;color:rgb(74,110,224)" target="_blank" href="https://urldefense.com/v3/__https://yale.zoom.us/meeting/register/tJApcu6grD4iGdFaQsDVdpJEaGD1oE-3VOjB__;!!Mih3wA!Tpypsbm9Jhum8Y9PdlhGu5QaxuU0znb-oUNm73O7NQrpnVr_Di7g23WCdqgLmn02eA$" class="gmail-_e75a791d-denali-editor-page-rtfLink"><span style="background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt;color:rgb(74,110,224)">https://yale.zoom.us/meeting/register/tJApcu6grD4iGdFaQsDVdpJEaGD1oE-3VOjB</span></a></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><br></p><p style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt"><span style="color:rgb(14,16,26);background:transparent none repeat scroll 0% 0%;margin-top:0pt;margin-bottom:0pt">It was over fifty years ago that the first 3D reconstruction from electron microscopy was published (DeRosier and Klug, 1968), and this happened to be a helical phage tail. It was no accident that this was a helical specimen, and not just because helical polymers are so abundant in biology. From one point of view helical objects are the simplest to reconstruct: a single image of a helical filament may provide all of the information needed for a 3D reconstruction. Fourier-Bessel methods of reconstruction dominated the field for the next 30 years, but now real-space approaches have become the standard. With the advent of direct-electron detectors, reaching a near-atomic resolution for helical polymers has become the standard, rather than the exception. However, problems in determining the correct helical symmetry can persist even when one reaches a resolution of ~ 5 Å. I will discuss how the best approach to determining helical symmetry involves an averaged power spectrum from the images, and explain why the power spectrum of an averaged image (such as using Class2D) is not the same as the averaged power spectrum. In addition, the highly anisotropic environment present in thin films prior to vitrification, the compressional forces associated with these thin films, and fluid flow with associated shear, can all impact the structure of the filaments being examined. I will discuss these problems and potential solutions while giving an overview of some of our own efforts involving everything from viruses infecting hosts living in nearly boiling acid to microbial nanowires, with stops along the way at bacterial and archaeal flagellar filaments and bacterial and archaeal pili.</span></p>
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