Lecturer: Dr. Victor Yashunsky, Ben-Gurion University in the Negev
 Abstract:
Multicellular systems, such as tissues and bacterial colonies, function as dynamic assemblies of self-propelled units that exhibit collective behaviors, resulting in complex biological functions. These systems, often characterized by elongated particles, display "nematic" ordering, with spatial organization described by a director field. Within this field, topological defects emerge as inherent structural features, significantly impacting the system’s dynamics and evolution. The interactions among these defects—including attraction, repulsion, and alignment—play a crucial role in driving reorganization within the system. In this presentation, I will share experimental findings from various multicellular systems, focusing on flow patterns around nematic defects and the interactions between defects during annihilation and creation events.