<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class=""><span class=""><font face="HelveticaNeue" class="">Dear Soft Matter & Complex Systems Colleagues and Friends,</font></span></div><div class=""><span class=""><font face="HelveticaNeue" class=""><br class=""></font></span></div><div class=""><div class=""><font face="HelveticaNeue" class="">On Friday 16 June 2023 at 9:30 AM at the UW Faculty of Physics (Pasteura 5, Warsaw; room 1.40) we are hosting the last seminar of the term, during which</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><b class=""><font face="HelveticaNeue" class=""><br class=""></font></b></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue" class=""><b class="">Jonasz Słomka </b>(ETH Zürich)</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue" class=""><br class=""></font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">will give a talk</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue" class=""><br class=""></font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><h2 style="margin: 6px 0px 12px; padding: 0px; caret-color: rgb(68, 68, 68);" class=""><span style="font-size: 12px;" class=""><font face="HelveticaNeue" class="">How BioEncounters at the microscale prime microbial interactions in the ocean</font></span></h2></div></div></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><b class=""><font face="HelveticaNeue" class="">Abstract</font></b></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class=""><span style="caret-color: rgb(68, 68, 68); text-align: justify; background-color: rgb(255, 255, 255);" class="">Microbial interactions critically depend on the rate of physical cell-cell or cell-resource encounters: these microscale processes control the rate of many fundamental ecological functions. In the ocean, a prominent example is the encounters among phytoplankton that lead to the formation of marine snow following a phytoplankton bloom. Another example is bacterial encounters with sinking marine snow particles that bacteria degrade, exerting an important control on carbon export from the upper ocean (the ‘biological pump’). Microscale encounters are nearly always modeled as encounters between inanimate spheres, borrowing from physical models of gases, coagulating colloids, and rain formation. However, these physics-based approaches fail to account for important traits of microorganisms, for example, cell elongation. Yet, certain traits of microorganisms combined with environmental conditions significantly impact many types of encounters in the ocean. For example, cell shape, in conjunction with buoyancy and turbulence, can increase encounter rates and thus speed up the formation of marine snow by elongated phytoplankton nearly ten-fold: this result provides a mechanistic explanation for the rapid clearance of blooms of elongated phytoplankton species. Similarly, encounters between bacteria and sinking marine snow depend on cell shape, motility, and fluid shear, and these factors can alter the encounter rate by orders of magnitude. Finally, microbes can harness encounters - </span><em style="caret-color: rgb(68, 68, 68); text-align: justify;" class="">Trichodesmium</em><span style="caret-color: rgb(68, 68, 68); text-align: justify; background-color: rgb(255, 255, 255);" class="">, a key marine nitrogen fixer, uses smart reversals to convert random encounters between cells into organized active aggregates. I will outline how more realistic models of encounters and aggregation at the microscale can contribute to our understanding of fundamental ecological processes controlled by microbes.</span></font></div></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><div class="" style="margin: 0cm; background-color: white;"><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class=""><br class=""></font></div></div></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">We warmly welcome everyone to attend the talk and the Soft Matter Coffee Break after the seminar, held in room 2.63 (2nd floor).</font></div></div><div class=""><font face="HelveticaNeue" class=""><br class=""></font></div><div class=""><div dir="auto" class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div class=""><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Maria Ekiel-Jeżewska</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Maciej Lisicki</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Piotr Szymczak</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Panagiotis Theodorakis</font></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue" class="">Marek Trippenbach</font></div></div></div></div><div class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; 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