| 03/2024 Tangential diffusion and motility-induced mixing transition in exponentially growing multicellular spheroids Torben Sunkel et al. Growth is a known driver of cellular dynamics in a range of dense aggregates from bacterial colonies to developing tissues to tumors. Hence, universal physical principles underlying these dynamics are of great interdisciplinary interest. Here, we study the emergent dynamics arising from the interplay of growth, steric repulsion and motility in a minimal agent-based model of exponentially growing t … |
| 03/2024 Multiphase Field Model of Cells on a Substrate: From 3D to 2D Michael Chiang et al. Multiphase field models have emerged as an important computational tool for understanding biological tissue while resolving single-cell properties. While they have successfully reproduced many experimentally observed behaviors of living tissue, the theoretical underpinnings have not been fully explored. We show that a two-dimensional version of the model, which is commonly employed to study tissue … |
| 03/2024 Heterogeneous Nucleation and Growth of Sessile Chemically Active Droplets Noah Ziethen et al. Droplets are essential for spatially controlling biomolecules in cells. To work properly, cells need to control the emergence and morphology of droplets. On the one hand, driven chemical reactions can affect droplets profoundly. For instance, reactions can control how droplets nucleate and how large they grow. On the other hand, droplets coexist with various organelles and other structures inside … |
| 03/2024 Beyond Pairwise: Higher-order physical interactions affect phase separation in multi-component liquids Chengjie Luo et al. Phase separation, crucial for spatially segregating biomolecules in cells, is well-understood in the simple case of a few components with pairwise interactions. Yet, biological cells challenge the simple picture in at least two ways: First, biomolecules, like proteins and nucleic acids, exhibit complex, higher-order interactions, where a single molecule may interact with multiple others simultaneo … |
| 03/2024 Collective self-caging of active filaments in virtual confinement Maximilian Kurjahn et al. Motility coupled to responsive behavior is essential for many microorganisms to seek and establish appropriate habitats. One of the simplest possible responses, reversing the direction of motion, is believed to enable filamentous cyanobacteria to form stable aggregates or accumulate in suitable light conditions. Here, we demonstrate that filamentous morphology in combination with responding to lig … |
| 02/2024 3D active nematic disclinations behave as Majorana quasiparticles Louise C. Head et al. Quasiparticles are low-energy excitations with important roles in condensed matter physics. An intriguing example is provided by Majorana fermions, quasiparticles which are identical to their antiparticles. Despite being implicated in neutrino oscillations and topological superconductivity, their experimental realisations remain scarce. Here we propose a purely classical realisation of Majorana fe … |
| 02/2024 Chemotactic particles as strong electrolytes: Debye-Hückel approximation and effective mobility law Pierre Illien et al. We consider a binary mixture of chemically active particles, that produce or consume solute molecules, and that interact with each other through the long-range concentrations fields they generate. We analytically calculate the effective phoretic mobility of these particles when the mixture is submitted to a constant, external concentration gradient, at leading order in the overall concentration. R … |
| 02/2024 Nonreciprocal collective dynamics in a mixture of phoretic Janus colloids Gennaro Tucci et al. A multicomponent mixture of Janus colloids with distinct catalytic coats and phoretic mobilities is a promising theoretical system to explore the collective behavior arising from nonreciprocal interactions. An active colloid produces (or consumes) chemicals, self-propels, drifts along chemical gradients, and rotates its intrinsic polarity to align with a gradient. As a result the connection from m … |
| 02/2024 Bringing together two paradigms of non-equilibrium: Driven dynamics of aging systems Diego Tapias et al. There are two fundamental paradigms for non-equilibrium dynamics: on the one hand, aging towards an equilibrium state that cannot be reached on reasonable timescales; on the other, external driving that can lead to non-equilibrium steady states. We explore how these two mechanisms interact, by studying the behaviour of trap models, which are paradigmatic descriptions of slow glassy dynamics, when … |
| 02/2024 Controlling flow patterns and topology in active emulsions Giuseppe Negro et al. Active emulsions and liquid crystalline shells are intriguing and experimentally realisable types of topological matter. Here we numerically study the morphology and spatiotemporal dynamics of a double emulsion, where one or two passive small droplets are embedded in a larger active droplet. We find activity introduces a variety of rich and nontrivial nonequilibrium states in the system. First, a … |