{"title":"Strongly perturbed bondorbital attractors for generalized systems.","authors":"A Dlamini, E F Doungmo Goufo, M Khumalo","doi":"10.1063/5.0249237","DOIUrl":"https://doi.org/10.1063/5.0249237","url":null,"abstract":"<p><p>This paper analyzes a generalized chaotic system of differential equations characterized by attractors with bondorbital structures. Both classical and fractional-order cases are examined analytically and numerically, with convergence and stability analyses provided. The numerical findings confirm the presence of bondorbital attractors in the classical system. In contrast, bondorbital attractors also emerge in the fractional model employing the Caputo-Fabrizio operator, albeit with significant perturbations for specific fractional orders. To validate these results, an electric circuit implementation of the fractional-order system using an field-programmable gate array board was conducted, yielding consistent outcomes. This study highlights the potential of fractional calculus, particularly the Caputo-Fabrizio operator, in capturing the memory effects and complex dynamics of chaotic systems. The work bridges theoretical modeling and practical hardware applications, offering valuable insights for modeling complex systems.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143122406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A logarithm law for non-autonomous systems rapidly converging to equilibrium and mean field coupled systems.","authors":"Stefano Galatolo, Davide Faranda","doi":"10.1063/5.0221721","DOIUrl":"https://doi.org/10.1063/5.0221721","url":null,"abstract":"<p><p>We prove that if a non-autonomous system has in a certain sense a fast convergence to equilibrium (faster than any power law behavior), then the time τr(x,y) needed for a typical point x to enter for the first time in a ball B(y,r) centered at y, with small radius r, scales as the local dimension of the equilibrium measure μ at y, i.e., limr→0logτr(x,y)-logr=dμ(y). We then apply the general result to concrete systems of different kinds, showing such a logarithm law for asymptotically autonomous solenoidal maps and mean field coupled expanding maps.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143122046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Evolutionary dynamics of cooperation driven by a mixed update rule in structured prisoner's dilemma games.","authors":"Longhao Lin, Chengrui Li, Xiaojie Chen","doi":"10.1063/5.0245574","DOIUrl":"https://doi.org/10.1063/5.0245574","url":null,"abstract":"<p><p>How to understand the evolution of cooperation remains a scientific challenge. Individual strategy update rule plays an important role in the evolution of cooperation in a population. Previous works mainly assume that individuals adopt one single update rule during the evolutionary process. Indeed, individuals may adopt a mixed update rule influenced by different preferences such as payoff-driven and conformity-driven factors. It is still unclear how such mixed update rules influence the evolutionary dynamics of cooperation from a theoretical analysis perspective. In this work, in combination with the pairwise comparison rule and the conformity rule, we consider a mixed updating procedure into the evolutionary prisoner's dilemma game. We assume that individuals adopt the conformity rule for strategy updating with a certain probability in a structured population. By means of the pair approximation and mean-field approaches, we obtain the dynamical equations for the fraction of cooperators in the population. We prove that under weak selection, there exists one unique interior equilibrium point, which is stable, in the system. Accordingly, cooperators can survive with defectors under the mixed update rule in the structured population. In addition, we find that the stationary fraction of cooperators increases as the conformity strength increases, but is independent of the benefit parameter. Furthermore, we perform numerical calculations and computer simulations to confirm our theoretical predictions.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143122270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Rate-induced biosphere collapse in the Daisyworld model.","authors":"Constantin W Arnscheidt, Hassan Alkhayuon","doi":"10.1063/5.0240983","DOIUrl":"https://doi.org/10.1063/5.0240983","url":null,"abstract":"<p><p>There is much interest in the phenomenon of rate-induced tipping, where a system changes abruptly when forcings change faster than some critical rate. Here, we demonstrate and analyze rate-induced tipping in the classic \"Daisyworld\" model. The Daisyworld model considers a hypothetical planet inhabited only by two species of daisies with different reflectivities and is notable because the daisies lead to an emergent \"regulation\" of the planet's temperature. The model serves as a useful thought experiment regarding the co-evolution of life and the global environment and has been widely used in the teaching of Earth system science. We show that sufficiently fast changes in insolation (i.e., incoming sunlight) can cause life on Daisyworld to go extinct, even if life could in principle survive at any fixed insolation value among those encountered. Mathematically, this occurs due to the fact that the solution of the forced (nonautonomous) system crosses the stable manifold of a saddle point for the frozen (autonomous) system. The new discovery of rate-induced tipping in such a classic, simple, and well-studied model provides further supporting evidence that rate-induced tipping-and indeed, rate-induced collapse-may be common in a wide range of systems.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143439877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Role of short-term plasticity and slow temporal dynamics in enhancing time series prediction with a brain-inspired recurrent neural network.","authors":"Artem Pilzak, Matias Calderini, Nareg Berberian, Jean-Philippe Thivierge","doi":"10.1063/5.0233158","DOIUrl":"https://doi.org/10.1063/5.0233158","url":null,"abstract":"<p><p>Typical reservoir networks are based on random connectivity patterns that differ from brain circuits in two important ways. First, traditional reservoir networks lack synaptic plasticity among recurrent units, whereas cortical networks exhibit plasticity across all neuronal types and cortical layers. Second, reservoir networks utilize random Gaussian connectivity, while cortical networks feature a heavy-tailed distribution of synaptic strengths. It is unclear what are the computational advantages of these features for predicting complex time series. In this study, we integrated short-term plasticity (STP) and lognormal connectivity into a novel recurrent neural network (RNN) framework. The model exhibited rich patterns of population activity characterized by slow coordinated fluctuations. Using graph spectral decomposition, we show that weighted networks with lognormal connectivity and STP yield higher complexity than several graph types. When tested on various tasks involving the prediction of complex time series data, the RNN model outperformed a baseline model with random connectivity as well as several other network architectures. Overall, our results underscore the potential of incorporating brain-inspired features such as STP and heavy-tailed connectivity to enhance the robustness and performance of artificial neural networks in complex data prediction and signal processing tasks.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143467090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Coherence resonance and energy dynamics in a memristive map neuron.","authors":"Zhao Lei, Jun Ma","doi":"10.1063/5.0251352","DOIUrl":"https://doi.org/10.1063/5.0251352","url":null,"abstract":"<p><p>Nonlinear circuits can be tamed to produce similar firing patterns as those detected from biological neurons, and some suitable neural circuits can be obtained to propose reliable neuron models. Capacitor C and inductor L contribute to energy storage while resistors consume energy, and the time constant RC or L/R provides a reference scale for neural responses. The inclusion of memristors introduces memory effects by coupling energy flow with the historical states of the circuit. A nonlinear resistor introduces nonlinearity, enriching the circuit's dynamic characteristics. In this work, a neural circuit is constructed and one branch circuit contains a constant voltage source E. The relation between physical variables is confirmed and a memristive oscillator with an exact energy function is proposed. Furthermore, an equivalent map neuron is derived when a linear transformation is applied to the sampled variables of the oscillator-like neuron. The energy function for the memristive oscillator is calculated following Helmholtz's theorem, and the memristive map is expressed with an energy description. It is found that the energy of the periodic state is higher than that of the chaotic state, which highlights the key role of energy in mode conversion. Noise-induced coherence resonance or stochastic resonance is induced under an external field. The adaptive control mechanism influenced by Hamilton energy is investigated, revealing its impact on neural mode transitions. These findings bridge the gap between physical circuit design and neural modeling, providing theoretical insights into applications in neuromorphic computing, signal processing, and energy-efficient control systems.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143472383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Nonlinear light control in optical couplers: Harnessing PPTT-symmetry for enhanced beam propagation.","authors":"C P Jaseera, K Aysha Muhsina, A R Thasneem","doi":"10.1063/5.0245649","DOIUrl":"https://doi.org/10.1063/5.0245649","url":null,"abstract":"<p><p>This study explored the evolution of nonlinear eigenmodes in coupled optical systems supported by PT-symmetric Rosen-Morse complex potential, in which one channel is with gain and the other is with loss. We assessed that the threshold potential above which PT-symmetry breakdown occurs is enhanced by coupling constant, by examining low- and high-frequency eigenmodes of ground and first excited states. The stability of eigenmodes was verified by stability analysis using Bogoliubov-de-Gennes (BdG) equations and it was established that even though the Rosen-Morse potential-supported system can create eigenmodes, it cannot support stable soliton solutions for any potential values. The investigation was extended using the modified Rosen-Morse potential that is nearly PT-symmetric and deduced the conditions for better-defined thresholds, improved damping of growth of perturbation which destabilizes eigenmodes, and advanced control mechanisms to manage perturbations and potential interactions. Propagation dynamics of the eigenmodes and power switching between channels have been studied and the controlling mechanism has been discussed to use coupled systems as optical regulators to precisely direct light between multiple paths. We have explored the significance of couplers in signal-processing applications because they control the intensity of various frequency modes. Optical couplers can be used to develop devices that let light travel in one direction while restricting it in the other which find applications in optical sensing.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143472384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Kuramoto model with stochastic resetting and coupling through an external medium.","authors":"Paul C Bressloff","doi":"10.1063/5.0246886","DOIUrl":"https://doi.org/10.1063/5.0246886","url":null,"abstract":"<p><p>Most studies of collective phenomena in oscillator networks focus on directly coupled systems, as exemplified by the classical Kuramoto model. However, there are a growing number of examples in which oscillators interact indirectly via a common external medium, including bacterial quorum sensing (QS) networks, pedestrians walking on a bridge, and centrally coupled lasers. In this paper, we analyze the effects of stochastic phase resetting on a Kuramoto model with indirect coupling. All the phases are simultaneously reset to their initial values at a random sequence of times generated from a Poisson process. On the other hand, the external environmental state is not reset. We first derive a continuity equation for the population density in the presence of resetting and show how the resulting density equation is itself subject to stochastic resetting. We then use an Ott-Antonsen (OA) Ansatz to reduce the infinite-dimensional system to a four-dimensional piecewise deterministic system with subsystem resetting. The latter is used to explore how synchronization depends on a cell density parameter. (In bacterial QS, this represents the ratio of the population cell volume and the extracellular volume.) At high densities, we recover the OA dynamics of the classical Kuramoto model with global resetting. On the other hand, at low densities, we show how subsystem resetting has a major effect on collective synchronization, ranging from noise-induced transitions to slow/fast dynamics.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143499599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luca Angelani, Alessandro De Gregorio, Roberto Garra
{"title":"Generalized time-fractional kinetic-type equations with multiple parameters.","authors":"Luca Angelani, Alessandro De Gregorio, Roberto Garra","doi":"10.1063/5.0243533","DOIUrl":"https://doi.org/10.1063/5.0243533","url":null,"abstract":"<p><p>In this paper, we study a new generalization of the kinetic equation emerging in run-and-tumble models [see, e.g., Angelani et al., J. Stat. Phys. 191, 129 (2024) for a time-fractional version of the kinetic equation]. We show that this generalization leads to a wide class of generalized fractional kinetic (GFK) and telegraph-type equations that depend on two (or three) parameters. We provide an explicit expression of the solution in the Laplace domain and show that, for a particular choice of the parameters, the fundamental solution of the GFK equation can be interpreted as the probability density function of a stochastic process obtained by a suitable transformation of the inverse of a subordinator. Then, we discuss some particularly interesting cases, such as generalized telegraph models, fractional diffusion equations involving higher order time derivatives, and fractional integral equations.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143122372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A K Misra, Ashutosh Upadhayay, Mamta Kumari, Jyoti Maurya
{"title":"Graph-theoretic approach and bifurcation analysis of skill acquisition and its effect on unemployment.","authors":"A K Misra, Ashutosh Upadhayay, Mamta Kumari, Jyoti Maurya","doi":"10.1063/5.0244559","DOIUrl":"https://doi.org/10.1063/5.0244559","url":null,"abstract":"<p><p>In developing countries, the informal sector plays a crucial role in employing unskilled labor workforce and contributes significantly to economic growth. Informal sector also facilitates skill acquisition, which enhances workers' employability. This research work presents a dynamical model examining how skilled individuals in the informal sector influence unemployment dynamics. The model considers unemployed persons (both unskilled and skilled) and employed persons as dynamic variables. We analyze the feasibility and stability of all equilibria for the proposed dynamical system. A quantity R0, analogous to the basic reproductive ratio in epidemic models, is derived. We also demonstrate the existence of various bifurcations, including transcritical, saddle-node, Hopf, and Bogdanov-Takens bifurcations. Additionally, we apply a graph-theoretical approach to analyze unemployment patterns and connections within the labor workforce. This provides insights into the structure and dynamics of unemployment networks, complementing the dynamical system's analysis. By combining dynamical system's theory with graph theory, this study provides a comprehensive, multi-dimensional understanding of unemployment dynamics in developing economies characterized by substantial informal sector.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143254910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}