Dresden 2026 – scientific programme

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BP: Fachverband Biologische Physik

BP 14: Poster Session II

BP 14.96: Poster

Tuesday, March 10, 2026, 18:00–21:00, P2

Noisy mixtures at the mesoscale: Vacuoles dancing in chemically active droplets — •Estéban Araspin, Leonardo Silva Dias, and Christoph A. Weber — Faculty of Mathematics, Natural Sciences, and Materials Engineering: Institute of Physics, University of Augsburg, Universitätsstrasse 1, 86159 Augsburg, Germany.

Understanding biological mixtures at the mesoscale calls for models that connect microscopic reactions with emergent continuum behavior in a thermodynamically consistent way. At such coarse-grained scales, noise, generally of multiplicative nature, is essential to capture phenomena like nucleation or stochastic switching between non-equilibrium steady states.

We developed a theoretical framework based on effective mesoscopic reaction-diffusion master equations that is applicable to both passive systems and non-equilibrium scenarios in which chemostatted fluxes make the mixture active. The framework connects to the macroscopic limit, recovering reactive Cahn-Hilliard-Cook dynamics.

As an application, we explore chemically active droplets in which a chemostatted ATP concentration leads to striking morphological dynamics. We find dilute-phase vacuoles that form and dissolve, reminiscent of bubbly phase separation in Model B+. We observe growth of small vacuoles at the expense of larger ones, dynamics that can be considered an inverse-ripening process.

Our results highlight the value of mesoscopic stochastic frameworks for understanding active phase separation and other soft-matter systems maintained away from equilibrium.

Keywords: Stochastic; Active; Phase; Reactions; Model