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DTSTAMP:20260424T125152Z
UID:6827042636c76044268953@ist.ac.at
DTSTART:20251127T110000
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DESCRIPTION:Speaker: Giulia Janzen\nhosted by Andela Saric\nAbstract: Biolo
 gical systems are typically not flat\, with curvature appearing across a w
 ide range of length scales\, from the subcellular structures and individua
 l cells to tissues and organs. The presence of curvature is tightly linked
  to biological function\, shaping processes from morphogenesis to cellular
  organization. With active matter providing a powerful framework for under
 standing the physics of living systems\, a natural question arises: how do
 es curvature influence collective behavior in active matter? To address th
 is question\, we study both polar active particles and semiflexible active
  filaments. For non-interacting particles\, curvature alone produces a str
 iking effect: it bends their trajectories in a manner reminiscent of gravi
 tational lensing. This deflection can lead to intermittent trapping of par
 ticles\, which profoundly alters their flocking behavior. In this sense\, 
 curvature acts as a geometric torque that reshapes collective dynamics [1]
 .Interestingly\, this picture changes significantly when we move from part
 icles to extended objects such as active filaments. Active filaments have 
 intrinsic curvature\, so their energy-minimizing configurations generally 
 do not align with geodesics\, except in special cases such as spherical su
 rfaces. On surfaces with non-uniform curvature\, however\, their motion em
 erges from a subtle interplay of activity\, bending rigidity\, density\, a
 nd geometrical constraints. Whereas particles may become trapped by geodes
 ic trajectories\, including closed loops or long\, recurrent paths\, filam
 ents instead localize in particular regions of the surface. These results 
 show how curvature and topology can be harnessed to guide or constrain fil
 ament organization [2].Together\, these results highlight how surface curv
 ature affects active system behavior\, with broad implications for biologi
 cal function and the design of synthetic active materials. Figure 1: Each
  filament is shown in a different grayscale shade\, while the surface is c
 olor-coded by curvature. On a sphere\, filaments follow geodesics\, but on
  closed surfaces with non-uniform curvature\, they become trapped in speci
 fic regions. REFERENCES[1] E. D. Mackay\, G. Janzen\, D. Fernandez\, and 
 R. Sknepnek\, arXiv preprint arXiv:2505.24730 (2025).[2] G. Janzen\, E. D.
  Mackay\, R. Sknepnek\, and D. Matoz-Fernandez\, arXiv preprint arXiv:2507
 .23616 (2025).
LOCATION:Office Bldg West / Ground floor / Heinzel Seminar Room (I21.EG.101
 )\, ISTA
ORGANIZER:cpetz@ist.ac.at
SUMMARY:Giulia Janzen: How Curvature Shapes Active Systems
URL:https://talks-calendar.ista.ac.at/events/6071
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