arXiv subjects

Ryosuke Nishide

Publications and source records attributed to Ryosuke Nishide.

5 recordsLinked to original sources

arXiv2026

Self-Organized Dynamic Reactors: Product-Condensate Feedback Accelerates Reactions

Condensates can accelerate reactions by concentrating reactants, yet product accumulation can eliminate this advantage. We show that product-induced suppression of condensation generates rotating, deforming, and propagating condensate domains through spontaneous symmetry breaking. Their reorganization shifts reaction sites away from accumulated products while retaining reactant enrichment, yielding rates above those of static condensates and homogeneous states. Reaction flows can thus self-organize condensates into dynamic reactors, with implications for biological and synthetic systems.

physics.bio-ph↗

arXiv2026

Self-Organized Bioelectricity via Collective Pump Alignment: Toward a Physical Origin of Chemiosmosis

Directional ion transport across membranes maintains living systems in nonequilibrium, which underlies chemiosmotic energy conversion. However, the physical origin of collectively organized ion transport in primitive cellular systems remains unclear. Here, we propose a minimal model in which ion pumps collectively align through feedback between ion transport and electrostatic interactions. In the model, directional ion transport generates a membrane potential, while the resulting electrochemical potential biases pump orientation, leading to self-organized collective alignment. Numerical simulations and mean-field analysis reveal a nonequilibrium transition from a disordered state without net transport to a pump-alignment state with sustained membrane potentials. The critical behavior is consistent with the mean-field Ising universality class; however, the effective field is generated self-consistently by nonequilibrium ion transport. We further show that protocell asymmetry can bias the polarity of the membrane potential. These results provide a generic self-organizing mechanism for the emergence of bioelectricity and a physical route toward chemiosmotic coupling in protocells.

physics.bio-ph↗

arXiv2024

Weakly nonlinear analysis of Turing pattern dynamics on curved surfaces

Pattern dynamics on curved surfaces are ubiquitous. Although the effect of surface topography on pattern dynamics has gained much interest, there is a limited understanding of the roles of surface geometry and topology in pattern dynamics. Recently, we reported that a static pattern on a flat plane can become a propagating pattern on a curved surface [Nishide and Ishihara, Phys. Rev. Lett. 2022]. By examining reaction-diffusion equations on axisymmetric surfaces, certain conditions for the onset of pattern propagation were determined. However, this analysis was limited by the assumption that the pattern propagates at a constant speed. Here, we investigate the pattern propagation driven by surface curvature using weakly nonlinear analysis, which enables a more comprehensive approach to the aforementioned problem. The analysis reveals consistent conditions of the pattern propagation similar to our previous results, and further predicts that rich dynamics other than pattern propagation, such as periodic and chaotic behaviors, can arise depending on the surface geometry. This study provides a new perspective on the relationship between surfaces and pattern dynamics and a basis for controlling pattern dynamics on surfaces.

nlin.PS↗

arXiv2024

Oscillatory and chaotic pattern dynamics driven by surface curvature

Patterns on curved surfaces are ubiquitous, yet the influence of surface geometry on pattern dynamics remains elusive. We recently reported a new mechanism of pattern propagation in which a static pattern on a flat plane becomes a propagating pattern on a curved surface [Nishide and Ishihara, Phys. Rev. Lett. 2022]. Here, we address whether surface curvature can drive more complex pattern dynamics beyond propagation. By employing a combination of weakly nonlinear analysis and numerical simulation, we show that oscillatory and chaotic pattern dynamics can emerge by controlling the surface shapes. These findings highlight a new role of surface topography in pattern formation and dynamics.

nlin.CD↗

arXiv2022

Pattern Propagation Driven by Surface Curvature

Pattern dynamics on curved surfaces are found everywhere in nature. The geometry of surfaces have been shown to influence dynamics and play a functional role, yet a comprehensive understanding is still elusive. Here, we report for the first time that a static Turing pattern on a flat surface can propagate on a curved surface, as opposed to previous studies, where the pattern is presupposed to be static irrespective of the surface geometry. To understand such significant changes on curved surfaces, we investigate reaction-diffusion systems on axisymmetric curved surfaces. Numerical and theoretical analyses reveal that both the symmetries of the surface and pattern participate in the initiation of pattern propagation. This study provides a novel and generic mechanism of pattern propagation that is caused by surface curvature, as well as insights into the general role of surface geometry.

nlin.PS↗