SKM 2023 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 4: Pattern Formation, Delay and Nonlinear Stochastic Systems

DY 4.10: Vortrag

Montag, 27. März 2023, 12:00–12:15, ZEU 250

Stochastic pH oscillator confined to lipid vesicles — •Arthur Straube1, Stefanie Winkelmann1, and Felix Höfling2, 11Zuse Institute Berlin — 2Institut für Mathematik, Freie Universität Berlin

We study an urea-urease-based pH oscillator confined to lipid vesicles serving as an open reactor [1,2]. In contrast to conventional pH oscillators in closed reactors, the exchange with the vesicle exterior periodically resets the pH clock that switches the system from acid to basic, resulting in self-sustained oscillations. Stochastic simulations for microscopically small vesicles predict a significant statistical variation of the oscillation period. Although the mean period remains remarkably robust for vesicle sizes down to nearly 200 nm, the periodicity of the rhythm is gradually destroyed for smaller vesicles [1]. We analyze the structure of the limit cycle, which controls the dynamics for giant vesicles and dominates the strongly stochastic oscillations in small vesicles of submicrometer size. We derive reduced two-variable models, amenable to analytic treatments, and show that the accuracy of predictions, including the period of oscillations, is highly sensitive to the choice of the reduction scheme [2]. The accurate description of a single pH oscillator is crucial for rationalizing experiments and understanding communication of vesicles and synchronization of rhythms.

[1] A. Straube, S. Winkelmann, C. Schütte, F. Höfling, J. Phys. Chem. Lett. 12, 9888 (2021). [2] A. Straube, S. Winkelmann, F. Höfling, ZIB Report 22-21 (2022), preprint (DOI: 10.12752/8817).

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