Alberto Dinelli (Genève)

Motility regulation in active (eco)systems

Active matter describes systems whose constituents generate non-conservative forces on their environment, leading to the wealth of emergent phenomena encountered in the living world. In particular, the regulation of motility at the particle scale, either via external cues or quorum-sensing interactions with peers, can dramatically affect the self-organization of active systems.
In the first part of my talk, I will show how one can bridge the gap between particle-based dynamics and hydrodynamic descriptions of motility-regulated active systems, by deriving generalized Green-Kubo relations for a broad class of motility-regulated active systems. [1,2]
Building on these results, I will investigate the role of random motility regulation in the self-organization of microbial ecosystems consisting of N >> 1 species. Combining particle-based simulations with random matrix theory, I will show how weak, random interactions are sufficient to fragment the ecosystem into distinct, spatially segregated communities. Our results hold for a variety of motility-regulation mechanisms, and highlight the need to characterize the role of motility regulation in experimentally relevant situations. [3]

[1] AD, P. L. Muzzeddu, arXiv 2604.09447 (2026)
[2] AD, P. L. Muzzeddu, arXiv 2604.09453 (2026)
[3] AD, A. Altieri, J. Tailleur, Phys. Rev. E 114, 014404 (2026)