arXiv subjects

Ivan Sudakow

Publications and source records attributed to Ivan Sudakow.

4 recordsLinked to original sources

arXiv2026

Modeling the response of the marine carbon cycle to extreme CO$_2$ injection events

We explore how the response of a conceptual model of the marine carbon cycle depends on the way in which carbon is injected from the atmosphere. We find that, for single-injection pulses, the threshold amount required for a large response of the excitable system depends on pulse duration but not on its specific form. We do, however, see differences in the number of large transient responses in carbon and, correspondingly, the duration of the response for different pulse shapes. These differences are magnified as the system is pushed towards increased excitability and can be understood in terms of the geometry of an increasingly winding heteroclinic orbit. Inspired by Large Igneous Provinces (LIPs), we also consider random sequences of injection pulses. We find a wide range of possible responses for a given overall amount injected and duration, depending on the mean characteristics of the individual pulses. We also identify a resonance-like "Goldilocks" zone, in which intermediate pulse durations or arrival frequencies produce the largest number of repeated transients, and we test the framework with illustrative scenarios motivated by the Siberian Traps and Columbia River Basalt Group.

physics.ao-ph↗

arXiv2026

Mixed phases in feedback Ising models

We study mean-field Ising models in which the coupling depends on the magnetization via a feedback function. We identify mixed phases (MPs) and show that they can be stable at zero temperature for sufficiently strong feedback. Moreover, stable MPs are always super-stable, meaning that perturbations decay linearly in time. Feedback Ising models (FIMs) provide a useful framework for phase transformations between aligned phases via stable and unstable intermediate phases in multistable systems. We also analyze the dynamical behavior of FIMs driven by a varying magnetic field and discuss basic properties of finite-dimensional FIMs.

cond-mat.stat-mech↗

arXiv2026

Dynamics of feedback Ising model

We study the dynamics of a mean-field Ising model whose coupling depends on the magnetization via a linear feedback function. A key feature of this linear feedback Ising model (FIM) is the possibility of temperature-induced bistability, where a temperature increase can favor bistability between two phases. We show that the linear FIM provides a minimal model for a transcritical bifurcation as the temperature varies. Moreover, there can be two or three critical temperatures when the external magnetic field is non-negative. In the bistable region, we identify a Maxwell temperature where the two phases are equally probable, and we find that increasing the temperature favors the lower phase. We show that the probability distribution becomes non-Gaussian on certain time intervals when the magnetization converges algebraically at either zero temperature or critical temperatures. Near critical points in the parameter space, we derive a Fokker-Planck equation, construct the families of equilibrium distributions, and formulate scaling laws for transition rates between two stable equilibria. The linear FIM offers considerable flexibility in controlling steady-state bifurcations and their associated equilibrium distributions, which can be desirable for modeling feedback systems across various disciplines.

cond-mat.stat-mech↗

arXiv2021

Chaotic waves serve as universal pattern generators

Excitable media are prevalent models for describing physical, chemical, and biological systems which support wave propagation. In this letter, we show that the time evolution of the medium state at the wave fronts can be determined by complicated chaotic attractors. Wave front dynamics can be controlled by initial data choice. Building on this groundwork, we show that there is a mechano-chemical analog of the Universal Turing machine for morphogenesis problems. Namely, a fixed mechano-chemical system can produce any prescribed cell pattern depending on its input (initial data). This universal mechanism uses fundamental physical effects: spontaneous symmetry breaking with formation of many interfaces (kinks), which interact non-locally via a fast diffusing reagent. This interaction creates chaos. We present algorithms allowing us to obtain a prescribed target cell pattern.

nlin.CD↗