Faculty of Science, Technology and Medicine
Faculty of Law, Economics and Finance
Faculty of Humanities, Education and Social Sciences
Interdisciplinary Centre for Security, Reliability and Trust
Luxembourg Centre for Systems Biomedicine
Luxembourg Centre for Contemporary and Digital History
Luxembourg Centre for European Law
Luxembourg Centre for Socio-Environmental Systems
“Non-equilibrium Phase Transitions in Biological Systems”
Abstract:
In this talk, I will give two examples of non-equilibrium phase transitions in biological systems. The first example is related to the formation of biological condensates that are formed by a local phase separation in cells. We consider the condensates as an active emulsion where the activity is due to achemical reaction between two solutes, maintained out of equilibrium. By coarse-graining, we obtain a hydrodynamic theory with one conserved order parameter, which is the sum of the concentrations of the two solutes. The coarse-grained equations are very similar to what has been called Active model B+. The model shows in some limits inverse Ostwald ripening and exotic phases including a bubble phase.
The second example studies the self-organisation of microtubules, (which are polar filaments) and two types of molecular motors walking each in one direction along the filaments. The microtubules self-organize into bands separating domains of the two motors. The phase transition is not due to direct interactions between the two types of motors but to the sorting of the two motors by the microtubules acting pumps for the motors. We construct a non-equilibrium Cahn-Hillard theory, which shows that the phase separation can be either mesoscopic or macroscopic.
About the speaker:
Jean-François Joanny has started his career as a CNRS researcher at Collège de France and then in Lyon. He was appointed as a professor at University Louis Pasteur in Strasbourg in 1989 and then at University Pierre et Marie Curie in Paris in 2003. He is a theoretical physicist and he has worked on various aspects of Soft Condensed Matter Physics and then of Physics for Biology. Between 2014 and 2018, he was the director General of Ecole Supérieure de Physique et Chimie Industrielles. He has been a professor at Collège de France since September 2018. When he moved to UPMC in Paris, he became director of the Physics Unit of Institut Curie. Since that time, he has worked on cell biophysics and fundamental cellular processes, the mechanics and growth of tissues and cancer physics. He describes all these biological phenomena with the concept of active matter. Jean-François Joanny has received several awards including the Bronze and Silver medals of the CNRS or the Ampère prize of the academy of sciences. He was a junior and senior member of Institut Universitaire de France.
Distinguished Physics Colloquium will follow a new format:
- The colloquium will take place on Wednesday, April 29, at 1:00 PM in room BSC 0.03 at the Bâtiment des Sciences on the Limpertsberg campus;
- Before the colloquium, we warmly invite you to a lunch break at 12:00 PM in the seminar room BSC 0.13 of the Bâtiment des Sciences. This is a great opportunity to engage with Prof. Jean-François Joanny and connect with fellow attendees over a nice lunch. For logistics purposes, please register for the lunch break by Friday, April 24, using the Lunch registration link below;
- Following the main talk, a dedicated session for PhD students with Prof. Jean-François Joanny will take place in room BSC 0.04 from 2:00 PM until 4:00 PM.
- Attendance in person is preferred. If you are unable to join us in person, you can still participate in the event remotely through the Webex link provided below. Meeting number (access code): 2793 828 7771; Meeting password: vvGqBZvk622.