2021 Giovanni Paladin Prize - Award ceremony SIFS
Award ceremony for the 2021 Giovanni Paladin Prize Link: https://www.fisicastatistica.org/premio-giovanni-paladin Seminar of the winner of the 2021 Giovanni Paladin Prize Winner: Dr. Livio Nicola Carenza - Leiden University, Lorentz Institute Title: Self-propulsion, Turbulence and Topological Defects in Active Fluids Abstract: Active systems are composed by a large number of constituents capable to consume internal or chemical energy to perform some work on the surrounding environment, so that they inherently evolve out of equilibrium. This property, common to many systems of biological origin, gives rise to a plethora of collective behaviors, not observable in absence of activity. In this seminar, I will focus on the physics of active fluids -for instance bacterial or cytoskeletal suspensions- where small-scale energy injection is able to excite self-sustained flows, leading to phenomena such as 'spontaneous flow' (namely the occurrence of coherent hydrodynamic states) and 'active turbulence' (a chaotic regime characterized by flows resembling those observed in a turbulent medium that evolves at high Reynolds number). Making use of the active gel theory and numerical simulations, I will discuss some features common to this wide class of phenomena and I will show how their physical properties can be explained in terms of the rate at which energy injected in the systems via active forcing is dissipated by viscosity or absorbed by reactive effects. In particular, I will discuss the case of an intrinsically chiral droplet where the mutual interaction between activity and topological constraints enables a new motility mode, where the rotational motion of surface defects is converted into propulsion. Finally, I will discuss how active topological defects interact with geometry and how this could play a crucial role in morphogenetic processes in animal tissues. To do this, I will consider a thin deformable disk embedded in the full 3D space of active liquid crystal featuring a +1 disclination at the centre. Here, the cooperative interaction of activity and geometry drives the buckling instability of the active membrane. This eventually results in the formation of long protrusions with a tentacle shape or even the nucleation of a vesicle. 0:00 - 1:47 Opening (Prof. Roberto Livi - SIFS President) 1:47 - 4:27 Presentation of the "Giovanni Paladin" Prize (Prof. Vittorio Loreto - Chair of the Paladin Prize Commission) 4:27 - 12:20 Brief speech in memory of Giovanni Paladin (Prof. Giorgio Parisi - 2021 Nobel Prize Laureate in Physics) 12:20 - 20:13 Brief speech in memory of Giovanni Paladin (Prof. Vittorio Loreto - Chair of the Paladin Prize Commission) 20:13 - 27:00 Announcement of the Winner of the "Giovanni Paladin" Prize 27:00 - 31:26 Announcement of Special Mentions 31:26 - 1:27:01 Seminar of Dr. Livio Nicola Carenza (Leiden University, Lorentz Institute), Winner of the 2021 Giovanni Paladin Prize 1:27:01 - 1:28:17 Closure (Prof. Roberto Livi - SIFS President)
Award ceremony for the 2021 Giovanni Paladin Prize Link: https://www.fisicastatistica.org/premio-giovanni-paladin Seminar of the winner of the 2021 Giovanni Paladin Prize Winner: Dr. Livio Nicola Carenza - Leiden University, Lorentz Institute Title: Self-propulsion, Turbulence and Topological Defects in Active Fluids Abstract: Active systems are composed by a large number of constituents capable to consume internal or chemical energy to perform some work on the surrounding environment, so that they inherently evolve out of equilibrium. This property, common to many systems of biological origin, gives rise to a plethora of collective behaviors, not observable in absence of activity. In this seminar, I will focus on the physics of active fluids -for instance bacterial or cytoskeletal suspensions- where small-scale energy injection is able to excite self-sustained flows, leading to phenomena such as 'spontaneous flow' (namely the occurrence of coherent hydrodynamic states) and 'active turbulence' (a chaotic regime characterized by flows resembling those observed in a turbulent medium that evolves at high Reynolds number). Making use of the active gel theory and numerical simulations, I will discuss some features common to this wide class of phenomena and I will show how their physical properties can be explained in terms of the rate at which energy injected in the systems via active forcing is dissipated by viscosity or absorbed by reactive effects. In particular, I will discuss the case of an intrinsically chiral droplet where the mutual interaction between activity and topological constraints enables a new motility mode, where the rotational motion of surface defects is converted into propulsion. Finally, I will discuss how active topological defects interact with geometry and how this could play a crucial role in morphogenetic processes in animal tissues. To do this, I will consider a thin deformable disk embedded in the full 3D space of active liquid crystal featuring a +1 disclination at the centre. Here, the cooperative interaction of activity and geometry drives the buckling instability of the active membrane. This eventually results in the formation of long protrusions with a tentacle shape or even the nucleation of a vesicle. 0:00 - 1:47 Opening (Prof. Roberto Livi - SIFS President) 1:47 - 4:27 Presentation of the "Giovanni Paladin" Prize (Prof. Vittorio Loreto - Chair of the Paladin Prize Commission) 4:27 - 12:20 Brief speech in memory of Giovanni Paladin (Prof. Giorgio Parisi - 2021 Nobel Prize Laureate in Physics) 12:20 - 20:13 Brief speech in memory of Giovanni Paladin (Prof. Vittorio Loreto - Chair of the Paladin Prize Commission) 20:13 - 27:00 Announcement of the Winner of the "Giovanni Paladin" Prize 27:00 - 31:26 Announcement of Special Mentions 31:26 - 1:27:01 Seminar of Dr. Livio Nicola Carenza (Leiden University, Lorentz Institute), Winner of the 2021 Giovanni Paladin Prize 1:27:01 - 1:28:17 Closure (Prof. Roberto Livi - SIFS President)