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Visualizzazione dei post in ordine di data per la query gst. Ordina per pertinenza Mostra tutti i post
Visualizzazione dei post in ordine di data per la query gst. Ordina per pertinenza Mostra tutti i post

mercoledì 2 luglio 2025

# gst: turbulence spreading and anomalous diffusion on combs.

<< This (AA) paper presents a simple model for such processes as chaos spreading or turbulence spillover into stable regions. In this simple model the essential transport occurs via inelastic resonant interactions of waves on a lattice. The process is shown to result universally in a subdiffusive spreading of the wave field. The dispersion of this spreading process is found to depend exclusively on the type of the interaction process (three- or four-wave), but not on a particular underlying instability. The asymptotic transport equations for field spreading are derived with the aid of a specific geometric construction in the form of a comb. >>

<< The results can be summarized by stating that the asymptotic spreading proceeds as a continuous-time random walk (CTRW) and corresponds to a kinetic description in terms of fractional-derivative equations. The fractional indexes pertaining to these equations are obtained exactly using the comb model. >>

<< A special case of the above theory is a situation in which two waves with oppositely directed wave vectors couple together to form a bound state with zero momentum. This situation is considered separately and associated with the self-organization of wave-like turbulence into banded flows or staircases. >>

<< Overall, (AA) find that turbulence spreading and staircasing could be described based on the same mathematical formalism, using the Hamiltonian of inelastic wave-wave interactions and a mapping procedure into the comb space. Theoretically, the comb approach is regarded as a substitute for a more common description based on quasilinear theory. Some implications of the present theory for the fusion plasma studies are discussed and a comparison with the available observational and numerical evidence is given. >>

Alexander V. Milovanov, Alexander Iomin, Jens Juul Rasmussen. Turbulence spreading and anomalous diffusion on combs. Phys. Rev. E 111, 064217 – Published 24 June, 2025

Also: waves, turbulence, walk, self-assembly, instability, chaos, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, turbulence, walk, self-assembly, instability, chaos, comb model, inelastic resonant interactions, inelastic wave-wave interactions, continuous-time random walk, self-organization of wave-like turbulence, Lévy flights, Lévy walks

lunedì 30 giugno 2025

# gst: topological phase transition under infinite randomness

<< In clean and weakly disordered systems, topological and trivial phases having a finite bulk energy gap can transit to each other via a quantum critical point. In presence of strong disorder, both the nature of the phases and the associated criticality can fundamentally change. >>

Here AA << investigate topological properties of a strongly disordered fermionic chain where the bond couplings are drawn from normal probability distributions which are defined by characteristic standard deviations. Using numerical strong disorder renormalization group methods along with analytical techniques, (AA) show that the competition between fluctuation scales renders both the trivial and topological phases gapless with Griffiths like rare regions. >>

<< Moreover, the transition between these phases is solely governed by the fluctuation scales, rather than the means, rendering the critical behavior to be determined by an infinite randomness fixed point with an irrational central charge. (AA) work points to a host of novel topological phases and atypical topological phase transitions which can be realized in systems under strong disorder. >>

Saikat Mondal, Adhip Agarwala. Topological Phase Transition under Infinite Randomness. arXiv: 2506.19913v1 [cond-mat.dis-nn]. Jun 24, 2025.

Also: order, disorder, disorder & fluctuations, random, transition, forms of power, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, order, disorder, disorder & fluctuations, randomness, criticality, transitions, forms of power

FonT: who knows if during some master's courses on the organization and evolution of social enclosures, held by the legendary "Frattocchie School" ( https://it.m.wikipedia.org/wiki/Scuola_delle_Frattocchie ) during the early 80s (but also early 90s) some bizarre theoretician advanced the imaginative, up in the air, absolutely unfounded hypothesis (here it is emphasized: absolutely), about the possibility of an immediate cracking of a social structure due to the action of idiots (?) disguised as idiots until the complete, universal, ontheback breakthrough anzicheforse?

sabato 28 giugno 2025

# gst: predicting the response of structurally altered and asymmetrical networks.

AA << investigate how the response of coupled dynamical systems is modified due to a structural alteration of the interaction. The majority of the literature focuses on additive perturbations and symmetrical interaction networks. >>

<< Here, (AA) consider the challenging problem of multiplicative perturbations and asymmetrical interaction coupling. (They) introduce a framework to approximate the averaged response at each network node for general structural perturbations, including non-normal and asymmetrical ones. >>

Their << findings indicate that both the asymmetry and non-normality of the structural perturbation impact the global and local responses at different orders in time. (AA) propose a set of matrices to identify the nodes whose response is affected the most by the structural alteration. >>

Melvyn Tyloo. Predicting the response of structurally altered and asymmetrical networks. arXiv: 2506.14609v1 [cond-mat.dis-nn]. Jun 17, 2025.


Keywords: gst, networks, multiplicative perturbations, asymmetrical interaction coupling

venerdì 27 giugno 2025

# gst: random interaction in active matter models; critical changes in Vicsek's scenario.


<< Randomness plays a key role in the order transition of active matter but has not yet been explicitly considered in pairwise interaction connection. In this paper, (AA) introduce the perception rate 𝑃 into the Vicsek model as the probability of the interaction connections and model the connections as superposition states. (They) show that with increasing 𝑃, the polar order number undergoes an order transition and then saturation. >>

<< The order transition is a first-order phase transition with band formation, and the effect of 𝑃 is different from density. The change of the order number is linked with the interaction structure. The order transition, order saturation, and phase separation correspond to different critical changes in the local interaction number. >>

<< The global interaction structure is further analyzed as a network. The decrease of 𝑃 is comparable to random edge removal, under which the network experiences modal transitions near the critical points of the order number, and the network exhibits surprising robustness.  (AA) results suggest that random interaction can be a new important factor in active matter models, with potential applications in robotic swarms and social activities. >>

Ruizhi Jin, Kejun Dong. Role of random interaction connection in the order transition of active matter based on the Vicsek model. Phys. Rev. E 111, 064122. Jun 17, 2025.

arXiv: 2501.10669v1 [cond-mat.soft]. Jan 18, 2025. 

Also: network, random, perception, transition, swarm, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, active matter, network, randomness, perception, criticality, transitions, swarm.

mercoledì 25 giugno 2025

# gst: interactive anisotropic walks in 2D generated from a 3-state opinion dynamics model.


<< A system of interacting walkers is considered in a two-dimensional hypothetical space, where the dynamics of each walker are governed by the opinion states of the agents of a fully connected three-state opinion dynamics model. Such walks, studied in different models of statistical physics, are usually considered in one-dimensional virtual spaces. >>

In this article AA has performed the mapping << in such a way that the walk is directed along the 𝑌 axis while it can move either way along the 𝑋 axis. The walk shows that there are three distinct regions as the noise parameter, responsible for driving a continuous phase transition in the model, is varied. In absence of any noise, the scaling properties and the form of the distribution along either axis do not follow any conventional form. >>

<< For any finite noise below the critical point the bivariate distribution of the displacements is found to be a modified biased Gaussian function while above it, only the marginal distribution along one direction is Gaussian. The marginal probability distributions can be extracted and the scaling forms of different quantities, showing power-law behavior, are obtained. The directed nature of the walk is reflected in the marginal distributions as well as in the exponents. >>

Surajit Saha, Parongama Sen. Interactive anisotropic walks in two dimensions generated from a three-state opinion dynamics model. Phys. Rev. E 111, 064123. Jun 18, 2025.

arXiv: 2409.10413v3 [cond-mat.stat-mech]. Apr 28, 2025. 

Also: walk, noise, random, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, walk, walking, random walk, randomness, noise, transitions, noise-induced transitions, criticality.

martedì 24 giugno 2025

# gst: far-from-equilibrium complex landscapes


<< Systems with a complex dynamics like glasses or models of biological evolution are often pictured in terms of a complex landscape, with a large number of possible collective states. (AA) show on the example of a stochastic spin model with nonreciprocal and heterogeneous interactions how the complex landscape picture can be generalized far from equilibrium, where collective states may become time-dependent and exhibit, e.g., spontaneous oscillations, often hidden by the presence of disorder. >>

AA << identify relevant observables, like the density of entropy production rate, to unveil the spontaneous collective time dependence, and  determine a configurational entropy which counts the number of oscillating collective states when this number grows exponentially with system size. >>

Laura Guislain, Eric Bertin. Far-from-equilibrium complex landscapes. Phys. Rev. E 111, L062101 Jun 16, 2025.

arXiv: 2405.08452v1 [cond-mat.dis-nn]. May 14, 2024.

Also: evolution, order, disorder, disorder & fluctuations, chaos, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, evolution, complexity, entropy, configurational entropy, order, disorder, disorder & fluctuations, spontaneous oscillations, chaos.

lunedì 23 giugno 2025

# gst: active drive towards elastic spinodals


<< Active matter, exemplified by adaptive living materials such as the actomyosin cytoskeleton, can navigate material parameter space, leading to unconventional mechanical responses. In particular, it can self-drive toward elastic spinodal regimes, where inhomogeneous floppy modes induce elastic degeneracy and enable a controlled interplay between rigidity loss and recovery. Proximity to such marginal states leads to stress localization and the formation of force chains that can be actively assembled and disassembled. >> 

Here AA << extend the classical notion of spinodal states to active solids and demonstrate how these extreme mechanical regimes can be actively accessed. Moreover, (They) show that in a nonlinear setting, crossing elastic spinodals generates new energy wells and makes force channeling an intrinsic feature of the emerging microstructure. >>

Ayan Roychowdhury, Madan Rao, Lev Truskinovsky. Active drive towards elastic spinodals. Phys. Rev. E 111, 065416. Jun 20, 2025.

arXiv: 2403.17517v3 [cond-mat.soft]. May 20, 2025.

Also: elastic, transition, instability, disorder & fluctuations, self-assembly, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, transitions, instability, disorder & fluctuations, active matter, elasticity, elastic forces, elastic deformation, elastic spinodals, self-assembly.

sabato 21 giugno 2025

# gst: a note on spinning billiards and chaos


AA << investigate the impact of internal degrees of freedom - specifically spin - on the classical dynamics of billiard systems. While traditional studies model billiards as point particles undergoing specular reflection, (AA) extend the paradigm by incorporating finite-size effects and angular momentum, introducing a dimensionless spin parameter that characterizes the moment of inertia. Using numerical simulations across circular, rectangular, stadium, and Sinai geometries, (AA) analyze the resulting trajectories and quantify chaos via the leading Lyapunov exponent. >>

<< Strikingly, (They) find that spin regularizes the dynamics even in geometries that are classically chaotic: for a wide range of α, the Lyapunov exponent vanishes at late times in the stadium and Sinai tables, signaling suppression of chaos. This effect is corroborated by phase space analysis showing non-exponential divergence of nearby trajectories. >>

AA << results suggest that internal structure can qualitatively alter the dynamical landscape of a system, potentially serving as a mechanism for chaos suppression in broader contexts. >>

Jacob S. Lund, Jeff Murugan, Jonathan P. Shock. A Note on Spinning Billiards and Chaos. arXiv: 2505.15335v1 [nlin.CD]. May 21, 2025.

Also: billiard, chaos, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, billiard, spinning billiards, chaos.

mercoledì 18 giugno 2025

# gst: spontaneous flow instability in active nematics; when quiescent and flowing states may coexist.


<< Active nematics exhibit spontaneous flows through a well-known linear instability of the uniformly aligned quiescent state. Here, (AA) show that even a linearly stable uniform state can experience a nonlinear instability, resulting in a discontinuous transition to spontaneous flows. In this case, quiescent and flowing states may coexist. >>

<< Through a weakly nonlinear analysis and a numerical study, (AA) trace the bifurcation diagram of striped patterns and show that the underlying pitchfork bifurcation switches from supercritical (continuous) to subcritical (discontinuous) by varying the flow-alignment parameter. >>

AA << predict that the discontinuous spontaneous flow transition occurs for a wide range of parameters, including systems of contractile flow-aligning rods. (AA) predictions are relevant to active nematic turbulence and can potentially be tested in experiments on either cell layers or active cytoskeletal suspensions. >>

Ido Lavi, Ricard Alert, et al. Nonlinear Spontaneous Flow Instability in Active Nematics. Phys. Rev. Lett. 134, 238301. Jun 9, 2025.

arXiv: 2403.16841v1 [cond-mat.soft].

Also: instability, turbulence, transition, in https://www.inkgmr.net/kwrds.html 

Also: Active nematics, in A. Doostmohammadi, et al. Nat Comm vol 9, no 3246 (2018). 

Keywords: gst, instability, turbulence, transitions, supercritical-- subcritical bifurcations, active nematics.

martedì 17 giugno 2025

# gst: early warning skill, extrapolation and tipping for accelerating cascades; if the upstream system crosses a tipping point, this can shorten the timescale of valid extrapolation.

AA << investigate how nonlinear behaviour (both of forcing in time and of the system itself) can affect the skill of early warning signals to predict tipping in (directionally) coupled bistable systems when using measures based on critical slowing down due to the breakdown of extrapolation. (They) quantify the skill of early warnings with a time horizon using a receiver-operator methodology for ensembles where noise realisations and parameters are varied to explore the role of extrapolation and how it can break down. >>

AA << highlight cases where this can occur in an accelerating cascade of tipping elements, where very slow forcing of a slowly evolving ``upstream'' system forces a more rapidly evolving ``downstream'' system. If the upstream system crosses a tipping point, this can shorten the timescale of valid extrapolation. >>

<< In particular, ``downstream-within-upstream'' tipping will typically have warnings only on a timescale comparable to the duration of the upstream tipping process, rather than the timescale of the original forcing. >>

Peter Ashwin, Robbin Bastiaansen, et al. Early warning skill, extrapolation and tipping for accelerating cascades.arXiv: 2506.01981v1 [nlin.CD]. May 16, 2025.

Also: crack, fracture, noise, track changes in noise, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, climate, early warning, tipping prediction, accelerating cascade, crossing a tipping point, multiple tipping points, fragmented tipping, criticality, noise, noise-induced tipping, crack, fracture

venerdì 13 giugno 2025

# gst: self-organization to multicriticality; when a system can self-organize to a new type of phase transition while staying on the verge of another.

<< Self-organized criticality is a well-established phenomenon, where a system dynamically tunes its structure to operate on the verge of a phase transition. Here, (AA) show that the dynamics inside the self-organized critical state are fundamentally far more versatile than previously recognized, to the extent that a system can self-organize to a new type of phase transition while staying on the verge of another. >>

<< In this first demonstration of self-organization to multicriticality, (AA) investigate a model of coupled oscillators on a random network, where the network topology evolves in response to the oscillator dynamics. (They) 
 show that the system first self-organizes to the onset of oscillations, after which it drifts to the onset of pattern formation while still remaining at the onset of oscillations, thus becoming critical in two different ways at once. >>
 
<< The observed evolution to multicriticality is robust generic behavior that (AA) expect to be widespread in self-organizing systems. Overall, these results offer a unifying framework for studying systems, such as the brain, where multiple phase transitions may be relevant for proper functioning.>>

Silja Sormunen, Thilo Gross, Jari Saramäki. Self-organization to multicriticality. arXiv: 2506.04275v1 [nlin.AO]. Jun 4, 2025. 

Also: network, random, self-assembly, transition, brain, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, network, random, self-assembly, transition, phase transition, multiple phase transitions, self-organizing systems, self-organized criticality, multicriticality, brain.

giovedì 12 giugno 2025

# gst: unstable fixed points in chaotic networks

<< Understanding the high-dimensional chaotic dynamics occurring in complex biological systems such as recurrent neural networks or ecosystems remains a conceptual challenge. For low-dimensional dynamics, fixed points provide the geometric scaffold of the dynamics. However, in high-dimensional systems, even the location of fixed points is unknown. >>

Here, AA << analytically determine the number and distribution of fixed points for a canonical model of a recurrent neural network that exhibits high-dimensional chaos. This distribution reveals that fixed points and dynamics are confined to separate shells in state space. Furthermore, the distribution enables (AA) to determine the eigenvalue spectra of the Jacobian at the fixed points, showing that each fixed point has a low-dimensional unstable manifold. >>

<< Despite the radial separation of fixed points and dynamics, (They)  find that the principal components of fixed points and dynamics align and that nearby fixed points act as partially attracting landmarks for the dynamics. >>

AA results << provide a detailed characterization of the fixed point geometry and its interplay with the dynamics, thereby paving the way towards a geometric understanding of high-dimensional chaos through their skeleton of unstable fixed points. >>

Jakob Stubenrauch, Christian Keup, et al. Fixed point geometry in chaotic neural networks. Phys. Rev. Research 7, 023203. May 29, 2025.

Also: chaos, disorder & fluctuations, instability, transition, network, brain, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, chaos, networks, neural networks, ecosystems, fixed points, unstable fixed points.

mercoledì 11 giugno 2025

# gst: apropos of weakness, weak but influential; nonlinear contributions of structural connectivity to human cognitive abilities and brain functions.

<< Diverse human cognitive abilities are rooted in brain structural connectivity which has weights spanning several orders of magnitude. However, due to false-positive challenges in tractography, weak connectivity has been often treated as noise and ignored - despite its prevalence across mammalian brains. >>

Here AA show << that weak connectivity significantly predicts human cognitive abilities and supports brain functions through amplification of its small weight in a nonlinear manner. >>

AA found that << weak connectivity involves high individual variability and significantly predicts general cognitive ability and memory in individuals, and it is also critical for whole-brain dynamic simulation and structure-function coupling. Importantly, fusing two post-tractography filtering methods of streamlines potentially results in more reliable connectivity that preserves weak links and outperforms conventional thresholding in predicting cognitive abilities and functional connectivity. >>

<< At the network level, weak connectivity expands the operational capacity of brain networks to enhance both global integration and fine-grained segregation, thereby supporting a functional balance essential for cognitive abilities. >>

<< Finally, (AA) identified a specific type of weak connectivity mainly linking visual/motor to limbic areas with negative gene co-expression, which has a disproportionately large impact on cognitive predictions and network dynamics. >>

Rong Wang, Zhao Chang, et al. Weak but influential: Nonlinear contributions of structural connectivity to human cognitive abilities and brain functions. arXiv: 2505.24125v1 [q-bio.NC]. May 30, 2025.

Also: brain, network, weak, noise, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, brain, network, noise,  weakness, weak connectivity,  brain structural connectivity, tractography, multiple tractography algorithms, cognitive ability and memory, individual variability, global integration, fine-grained segregation, limbic areas.

martedì 10 giugno 2025

# gst: collective behavior based on topological vision.

<< The collective dynamics of active particles with topological vision are investigated. The topological vision, defined as a combination of the visual field and topological neighborhoods, breaks the action-reaction symmetry, thereby indicating that active particles exhibit the nonreciprocal topological interactions. >>

<< Furthermore, (AA) model considers position-based attractive force, wherein moving particles navigate using instantaneous visual information from neighboring particles within the topological vision, distinct from conventional models based on the velocity-velocity alignment. (They) demonstrate that the competition between the noise and the nonreciprocal topological interactions results in the emergence of four typical phases: gas phase, ordered phase, nematic bands, and aggregate traveling polar band. >>

<< Moreover, the nonreciprocal topological interactions impact both anomalous diffusion and ergodicity breaking. Specifically, the weak nonreciprocal topological interactions lead to ergodic subdiffusion, while the strong nonreciprocal topological interactions give rise to nonergodic superdiffusion. These findings provide a theoretical basis for understanding the nonequilibrium collective transport of active particles with topological vision. >>

Hongda Shi, Luchun Du, Wei Guo. Collective behavior based on topological vision. Phys. Rev. Research 7, 023234. Jun 6, 2025. 

Also: particle, noise, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particles, active 
particles, noise, topological vision, 
reciprocal- nonreciprocal topological interactions, gas phase, ordered phase, nematic bands, aggregate traveling polar band.

lunedì 9 giugno 2025

# gst: double burst transition in hypergraphs.

Fig.2 - Bifurcation diagram. A two-parameter stability diagram in K2-d_th space depicting the different synchronization transition regimes. Blue, gray, cyan, red, light green, magenta, and dark gray present the regimes for continuous, tiered, classical explosive, forward and  backward double jump, forward double jump, explosive with stable middle states, and backward double jump synchronization transitions, respectively

This AA study << aims to develop a generalized concept that will enable double explosive transitions in the forward and backward directions or a combination thereof. >>

AA << found two essential factors for generating such phase transitions: the use of higher-order (triadic) interactions and the partial adaptation of a global order parameter acting on the triadic coupling. A compromise between the two factors may result in a double explosive transition. >>

<< To reinforce numerical observations, (They) employed the Ott-Antonsen ansatz. (AA) observed that for a wide class of hypergraphs, combining two elements can result in a double explosive transition. >>

Sangita Dutta, Prosenjit Kundu, et al. Double explosive Kuramoto transition in hypergraphs. Phys. Rev. Research 7, L022049. June 2, 2025.

Also: transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, transitions, phase transitions.

venerdì 6 giugno 2025

# gst: symmetry breaking in time-dependent billiards.

AA << investigate symmetry breaking in a time-dependent billiard that undergoes a continuous phase transition when dissipation is introduced. The system presents unlimited velocity, and thus energy growth for the conservative dynamics. When inelastic collisions are introduced between the particle and the boundary, the velocity reaches a plateau after the crossover iteration. The system presents the expected behavior for this type of transition, including scale invariance, critical exponents related by scaling laws, and an order parameter approaching zero in the crossover iteration. >>

AA << analyze the velocity spectrum and its averages for dissipative and conservative dynamics. The transition point in velocity behavior caused by the physical limit of the boundary velocity and by the introduced dissipation coincides with the crossover interaction obtained from the Vrms (root mean sq V) curves. Additionally, (they) examine the velocity distributions, which lose their symmetry once the particle's velocity approaches the lower limit imposed by the boundary's motion and the system's control parameters. This distribution is also characterized analytically by an expression P(V,n), which attains a stationary state, with a well-defined upper bound, only in the dissipative case. >>

Anne Kétri Pasquinelli da Fonseca, Edson Denis Leonel. Symmetry breaking in time-dependent billiards. arXiv: 2505.20488v1 [nlin.CD]. May 26, 2025.

Also: billiard, transition, dissipation,  in https://www.inkgmr.net/kwrds.html 

Keywords: gst, billiard, particles, transitions, dissipation, symmetry breaking, inelastic collisions.

giovedì 5 giugno 2025

# gst: spreading and retraction dynamics of drop impact onto elastic surfaces.

In this study, AA << numerically investigate the impact of droplets on elastic plates using a two-phase lattice Boltzmann method, with a particular focus on how vertical surface movements influence the spreading and retraction dynamics of the droplet. >>

<< The results show that, during the spreading phase, the spreading diameter is smaller on elastic surfaces compared to rigid ones due to the vertical velocity of the surface. A universal linear evolution of the drop spreading is derived for the early stage across both rigid and elastic substrates, accounting for the surface motion by rescaling time, and this relationship is in good agreement with the numerical results. >>

<< In the retraction phase, unlike the nearly constant retraction speed observed on rigid surfaces, the retraction speed 𝑉ret oscillates with the vibrations of the elastic surface, with the oscillation period remaining relatively consistent. Further analysis reveals that the variation in 𝑉ret is not influenced by the surface's velocity but rather by its acceleration, as additional inertia is introduced during surface acceleration. >>

<< Based on this understanding, a predictive model for 𝑉ret during droplet impacts on moving surfaces is proposed, which demonstrates strong agreement with the numerical findings. >>

Yufei Ma, Haibo Huang. Spreading and retraction dynamics of drop impact onto elastic surfaces. Phys. Rev. Fluids 10, 053607. May 15, 2025.

Also: drop, droplet, droploid, elastic, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drops, droplets, droploids, elasticity, elastic surfaces, surface acceleration, vertical surface movements, spreading phase, retraction phase.

mercoledì 4 giugno 2025

# gst: disorder, chimera state, traveling chimera state, and synchronization by weak temporal couplings.

<< The mechanisms of self-sustained oscillations of brain rhythms have been studied for a long time and it is revealed that the emergence of a pacemaker loop takes a key role for these rhythms. However, it is unclear how this pacemaker loop plays a role in the resting state of the brain, where the characteristic slow-wave activities show a multi-scaled feature and can switch easily between different dynamics states. >>

<< To study this problem, herein (AA) present a neural model of pacemaker looplike network, with a weak temporal electrical coupling to mark the resting state of the brain. (They) find that different dynamics patterns can be generated by this model, including the disorder, traveling chimera state, chimera state, and synchronization. >>

<< Interestingly, (AA) observe a sensitive switching effect between the region of traveling chimera state and that of chimera state, which may provide new insights to the mechanism of quickly switching between different rhythms of the brain in the resting state. >>

<< Further, (AA) introduce an index 𝑄 to describe the fluctuations of the local order parameter of network and conjecture that there is a new regularity caused by the fluctuations. (They) find that 𝑄 is optimally dependent on the matching of parameters and thus confirms the conjecture. Moreover, (they) show that the observed traveling chimera state is robust to different forms of temporal couplings. >>

Wenbin Mao, Guoshen Liang, Zonghua Liu. Traveling chimera states by weak temporal couplings. Phys. Rev. E 111, 054220. May 27, 2025.

Also: network, brain, disorder & fluctuations, waves, chimera, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, network, brain, disorder & fluctuations, waves, chimera, brain rhythms, brain resting state, self-sustained oscillations, pacemaker loop network, traveling chimera state, temporal coupling.

martedì 3 giugno 2025

# gst: diffusion and decay of an expanding turbulent blob; the cascade can leave an indelible footprint far into the decay process


<< Turbulence, left unforced, decays and invades the surrounding quiescent fluid. Though ubiquitous, this simple phenomenon has proven hard to capture within a simple and general framework. >>

Here, AA << circumvent these issues by creating a spatially-localized blob of turbulent fluid using eight converging vortex generators focused towards the center of a tank of water, and observe its decay and spread over decades in time, using particle image velocimetry with a logarithmic sampling rate. >>

<< The blob initially expands and decays until it reaches the walls of the tank and eventually transitions to a second regime of approximately spatially uniform decay. (AA) interpret these dynamics within the framework of a nonlinear diffusion equation, which predicts that the ideal quiescent-turbulent fluid boundary is sharp and propagates non-diffusively, driven by turbulent eddies while decaying with characteristic scaling laws. >>

AA << find direct evidence for this model within the expansion phase of (their) turbulent blob and use it to account for the detailed behavior (they) observe, in contrast to earlier studies. (AA) work provides a detailed spatially-resolved narrative for the behavior of turbulence once the forcing is removed, and demonstrates unexpectedly that the turbulent cascade leaves an indelible footprint far into the decay process. >>

Takumi Matsuzawa, Minhui Zhu, et al. Nonlinear Diffusion and Decay of an Expanding Turbulent Blob. arXiv: 2505.22737v2 [physics.flu-dyn]. May 30, 2025

Also: turbulence, vortex, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, quiescence, quiescent fluids, blobs, turbulent blobs, turbulent eddies, turbulent cascade, expansion and decay.

lunedì 2 giugno 2025

# gst: apropos of ambiguous scenarios, very persistent random walkers reveal transitions in landscape topology

AA << study the typical behavior of random walkers on the microcanonical configuration space of mean-field disordered systems. Passive walks have an ergodicity-breaking transition at precisely the energy density associated with the dynamical glass transition, but persistent walks remain ergodic at lower energies. >>

<< In models where the energy landscape is thoroughly understood, (They) show that, in the limit of infinite persistence time, the ergodicity-breaking transition coincides with a transition in the topology of microcanonical configuration space. (They) conjecture that this correspondence generalizes to other models, and use it to determine the topological transition energy in situations where the landscape properties are ambiguous. >>

Jaron Kent-Dobias. Very persistent random walkers reveal transitions in landscape topology. arXiv: 2505.16653v2 [cond-mat.dis-nn]. May 23, 2025. 

Also: random, walk, walking, disorder, transition, in https://www.inkgmr.net/kwrds.html

Also: ambiguity in FonT  https://flashontrack.blogspot.com/search?q=ambiguity     ambiguity in Notes (quasi-stochastic poetry)  https://inkpi.blogspot.com/search?q=ambiguita

Keywords: mean-field disordered systems, disorder, randomness, random walker, transitions, topological transition energy, ambiguity.