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Morphogenesis emerges from dynamic feedback among geometry, mechanics, and chemistry; however, disentangling these contributions in living systems remains challenging. Here, we focus on the interplay between geometry and mechanics by…

Cells are fundamental building blocks of living organisms displaying an array of shapes, morphologies, and textures that encode specific functions and physical behaviors. Elucidating the rules of this code remains a challenge. In this work,…

Inspired by recent experiments that highlight the role of nematic defects in the morphogenesis of epithelial tissues, we develop a minimal framework to study the dynamics of an active curved surface driven by its nematic texture. Allowing…

Soft Condensed Matter · Physics 2022-09-14 Farzan Vafa , L. Mahadevan

Topological defects are fundamental to the collective dynamics of non-equilibrium systems and in active matter, mediating spontaneous flows, dynamic self-organization, and emergent pattern formation. Here, we reveal critical states in…

Directional media, such as nematic liquid crystals and ferromagnets, are characterized by their topologically stabilized defects in directional order. In nematics, boundary conditions and surface-treated inclusions often create complex…

Soft Condensed Matter · Physics 2015-06-03 Simon Čopar , Slobodan Žumer

Using computer simulations we investigate the microscopic structure of the singular director field within a nematic droplet. As a theoretical model for nematic liquid crystals we take hard spherocylinders. To induce an overall topological…

Soft Condensed Matter · Physics 2009-10-31 J. Dzubiella , M. Schmidt , H. Loewen

Point-like topological defects are singular configurations that occur in a variety of in and out of equilibrium systems with two-dimensional orientational order. As they are associated with a nonzero circuitation condition, the presence of…

Statistical Mechanics · Physics 2023-07-13 Jacopo Romano , Benoît Mahault , Ramin Golestanian

Using novel micro-printing techniques, we develop a versatile experimental setup that allows us to study how lateral confinement tames the active flows and defect properties of the microtubule/kinesin active nematic system. We demonstrate…

A simple and efficient analytical model is proposed for analyzing plasmonic phenomena arising in nanoscale defects on metal surfaces, specifically low aspect ratio dome-shaped protrusions and depressions. The model enables the calculation,…

Optics · Physics 2025-07-03 Anton V. Dyshlyuk , Oleg B. Vitrik

We perform dynamical simulations of a two-dimensional active nematic fluid in coexistence with an isotropic fluid. Drops of active nematic become elongated, and an effective anchoring develops at the nematic-isotropic interface. The…

Soft Condensed Matter · Physics 2014-12-17 Matthew L. Blow , Sumesh P. Thampi , Julia M. Yeomans

We present a hydrodynamic model for a thin spherical shell of active nematic liquid crystal with an arbitrary configuration of defects. The active flows generated by defects in the director lead to the formation of stable vortices,…

Soft Condensed Matter · Physics 2017-11-13 Diana Khoromskaia , Gareth P. Alexander

We present a framework to take new measurements in nematic systems that contain active elements such as molecular motors. Spatio-temporal fields of stress, traction, velocity, pressure, and forces are estimated jointly from microscopy…

Soft Condensed Matter · Physics 2024-12-02 Aleix Boquet-Pujadas , Jérôme Hardouïn , Junhao Wen , Jordi Ignés-Mullol , Francesc Sagués

Active matter is characterized by its ability to induce motion by self-generated stress. In the case of a solid, such motion can lead to shape transformations. The stress-generating components can be anisotropic endowing the material with…

Soft Condensed Matter · Physics 2022-05-16 D. J. G. Pearce , S. Gat , G. Livne , A. Bernheim-Groswasser , K. Kruse

Active nematics are dense systems of rodlike particles that consume energy to drive motion at the level of the individual particles. They exist in natural systems like biological tissues and artificial materials such as suspensions of…

Soft Condensed Matter · Physics 2023-12-14 Yunrui Li , Zahra Zarei , Phu N. Tran , Yifei Wang , Aparna Baskaran , Seth Fraden , Michael F. Hagan , Pengyu Hong

Topological defects are at the root of the large-scale organization of liquid crystals. In two-dimensional active nematics, two classes of topological defects of charges $\pm 1/2$ are known to play a major role due to active stresses.…

Soft Condensed Matter · Physics 2022-04-08 Louis Brézin , Thomas Risler , Jean-François Joanny

Inverse nematic emulsions in which surfactant-coated water droplets are dispersed in a nematic host fluid have distinctive properties that set them apart from dispersions of two isotropic fluids or of nematic droplets in an isotropic fluid.…

Soft Condensed Matter · Physics 2009-10-30 T. C. Lubensky , David Pettey , Nathan Currier , Holger Stark

The dynamics of active smectic liquid crystals confined on a spherical surface is explored through an active phase field crystal model. Starting from an initially randomly perturbed isotropic phase, several types of topological defects are…

Soft Condensed Matter · Physics 2025-03-11 Michael Nestler , Simon Praetorius , Zhi-Feng Huang , Hartmut Löwen , Axel Voigt

Topological defects are one of the most conspicuous features of liquid crystals. In two dimensional nematics, they have been shown to behave effectively as particles with both, charge and orientation, which dictate their interactions. Here,…

Soft Condensed Matter · Physics 2021-07-14 Daniel J. G. Pearce , Karsten Kruse

Active turbulence in dense active systems is characterized by high vorticity on a length scale that is large compared to that of individual entities. We describe the properties of active turbulence as momentum propagation is screened by…

Soft Condensed Matter · Physics 2014-12-24 Sumesh P. Thampi , Ramin Golestanian , Julia M. Yeomans

The self-propulsion of +1/2 topological defects is a hallmark of active nematic fluids, where the defects are advected by the flow field they themselves generate. In this paper we propose a minimal model for defect self-propulsion in a…

Soft Condensed Matter · Physics 2025-08-08 Fridtjof Brauns , Myles O'Leary , Arthur Hernandez , Mark J. Bowick , M. Cristina Marchetti