Banca de DEFESA: LUCAS GABRIEL BEZERRA DE SOUZA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUCAS GABRIEL BEZERRA DE SOUZA
DATE: 28/11/2025
TIME: 09:00
LOCAL: Google Meet
TITLE:

How quorum sensing shapes clustering in active matter

KEY WORDS:

Active matter, biological physics, quorum-sensing, steric interactions, phase behavior

PAGES: 99
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUBÁREA: Física Geral
SPECIALTY: Física Estatística e Termodinâmica
SUMMARY:

Active matter refers to nonequilibrium systems composed of large ensembles of self-propelled entities, such as bacteria, tissue cells,
animal flocks, and colloids. A common trait among them is collective behavior, arising from interactions between individuals. One
communication strategy between microorganisms is chemically sensing others' presence, a mechanism known as quorum sensing.
This mechanism induces a response in which the organisms regulate their movement to achieve ecologically favorable spatial
distributions. However, motion can be limited by excluded-volume interactions. When self-propulsion directions fluctuate slowly,
the combination of persistent motion and excluded volume can lead to particle clustering. Quorum-sensing regulation may then alter
this scenario, generating diverse spatiotemporal patterns. In this thesis, we show that active particles with steric repulsion and
quorum-sensing motility reduction display reentrant clustering. As control parameters are varied, clustering disappears and then
reappears. In other words, a One of the phase behaviors that emerges from this interplay is a previously unexplored class of active gels
induced by quorum sensing. While quorum sensing can mimic attraction, it also produces strong effects in dilute regions, leading to
distinct phase behavior. Remarkably, quorum sensing leads to kinetically-arrested transient states with long memory of the system’s
initial condition. We then present a quorum-sensing kinetic theory that captures these phenomena. These results link phenomena in
synthetic and biological systems and show how quorum sensing, often overlooked in modeling, redefines self-organization, opening
paths in active matter physics. In a parallel project in another area of statistical physics, we construct, from first principles, Lévy α-stab
le distributions that are consistent with special relativity.

 

 

COMMITTEE MEMBERS:
Externo à Instituição - LEONARDO GREGORY BRUNNET - UFRGS
Interno - 1345774 - CLAUDIONOR GOMES BEZERRA
Externo à Instituição - CLÉCIO CLEMENTE DE SOUZA SILVA - UFPE
Interno - 1753234 - GUSTAVO ZAMPIER DOS SANTOS LIMA
Interno - 1294916 - MADRAS VISWANATHAN GANDHI MOHAN
Externo à Instituição - PABLO SOUZA DE CASTRO MELO - UNESP