# gst: chaotic billiards inside mixed curvatures

<< The boundary of a billiard system dictates its dynamics, which can be integrable, mixed, or fully chaotic. >>️

This AA study << introduces two such billiards: a bean-shaped billiard and a peanut-shaped billiard, the latter being a variant of Cassini ovals. Unlike traditional chaotic billiards, these systems incorporate both focusing and defocusing regions along their boundaries, with no neutral segments. >>

AA << examine both classical and quantum dynamics of these billiards and observe a strong alignment between the two perspectives. For classical analysis, the billiard flow diagram and billiard map reveal sensitivity to initial conditions, a hallmark of classical chaos. In the quantum domain, (AA) use nearest-neighbour spacing distribution and spectral complexity as statistical measures to characterise chaotic behaviour. >>

<< Both classical and quantum mechanical analysis are in firm agreement with each other. One of the most striking quantum phenomena (They) observe is the eigenfunction scarring (both scars and super-scars). Scarring phenomena serve as a rich visual manifestation of quantum and classical correspondence, and highlight quantum suppression chaos at a local level. >>

Pranaya Pratik Das, Tanmayee Patra, Biplab Ganguli. Manifestations of chaos in billiards: the role of mixed curvature. arXiv: 2501.08839v1 [nlin.CD]. Jan 15, 2025.

https://arxiv.org/abs/2501.08839

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

Keywords: gst, billiard, chaos

# gst: apropos of subdiffusive behaviors, the boomerang effect in classical stochastic models.

<< The phenomenon of Anderson localization, occurring in a disordered medium, significantly influences the dynamics of quantum particles. A fascinating manifestation of this is the “quantum boomerang effect” (QBE), observed when a quantum particle, propelled with a finite initial velocity, reverses its average trajectory, eventually halting at its starting point. >>

AA << uncover evidence of a similar effect in classical systems, characterized by the absence of typical diffusion processes. (Their) investigation encompasses both simplified probabilistic models and more complex phenomenological models that link classical with quantum mechanics. The results indicate that the boomerang effect is not confined to the quantum realm and may also be present in diverse systems exhibiting subdiffusive behavior. >>️

Santiago Zamora, Lisan M. M. Durao, et al. Boomerang effect in classical stochastic models. Phys. Rev. E 111, 024104. Feb 3, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.024104 

Also: behav, particle, disorder, disorder & fluctuations, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, behavior, particles, disorder, disorder & fluctuations, stocasticity, boomerang effect

# life: apropos of singular bizarre synchronies and extreme syntheses

(●) Black Sabbath, Ozzy Osbourne, et al. Back to the Beginning. Birmingham Villa Park. Saturday Doors: 12:00

https://www.livenation.co.uk/back-to-the-beginning-tickets-adp1561055

(●) << Learn 2 chords and then get a good lawyer before learning the 3rd. >>. Tony Iommi

https://www.azquotes.com/quote/1522713 

Also: Ozzy, in FonT https://flashontrack.blogspot.com/search?q=ozzy

Also: music, jazz, dance, three balls, in https://www.inkgmr.net/kwrds.html 

Keywords: life, music, jazz, dance, three balls, Ozzy

# gst: criticality and multistability in quasi-2D turbulence

       Fig. 1(a) Helmholtz resonators

<< Two-dimensional (2D) turbulence, despite being an idealization of real flows, is of fundamental interest as a model of the spontaneous emergence of order from chaotic flows. The emergence of order often displays critical behavior, whose study is hindered by the long spatial and temporal scales involved. >>

Here AA << experimentally study turbulence in periodically driven nanofluidic channels with a high aspect ratio using superfluid helium. (They) find a multistable transition behavior resulting from cascading bifurcations of large-scale vorticity and critical behavior at the transition to quasi-2D turbulence consistent with phase transitions in periodically driven many-body systems. >>

AA << demonstrate that quasi-2D turbulent systems can undergo an abrupt change in response to a small change in a control parameter, consistent with predictions for large-scale atmospheric or oceanic flows. >>️

Filip Novotny, Marek Talir, et al. Critical behavior and multistability in quasi-two-dimensional turbulence. arXiv: 2406.08566v1 [physics.flu-dyn]. Jun 12, 2024.

https://arxiv.org/abs/2406.08566

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

Keywords: gst, order, disorder, disorder & fluctuations, criticality, turbulence, transition 

# life: spontaneous emergence of run-and-tumble-like dynamics in coupled self-propelled bots.

<< Drawing inspiration from the motility behaviour of microorganisms, we introduce a highly tunable, robotic system self-actuating into the run-and-tumble (RT)-like motion. It comprises two disk-shaped, centimeter-scale programmable robots individually programmed to perform overdamped active Brownian (AB) motion and connected by a rigid rod. The rod is attached to pivot points located on off-centered, mirror-symmetric points on each robot, allowing for its free rotation at both ends. >>

AA << show that the collective dynamics of this system execute RT-like motion with characteristic sharp tumble events and exponentially distributed run times, similar to those observed in microorganisms. (They) further quantify emerging dynamics in terms of tumbling frequency and tune it over a wide range of experimental parameters. >>

AA << also develop a theoretical model that reproduces our experimental results and elucidates the underlying physical mechanisms governing the rich phase behavior of RT motion. >>

 ️

Somnath Paramanick, Umashankar Pardhi, et al. Spontaneous emergence of run-and-tumble-like dynamics in coupled self-propelled robots: experiment and theory. arXiv: 2502.01257v1 [cond-mat.soft]. Feb 3, 2025.

https://arxiv.org/abs/2502.01257

Also: behav, evolution, bot, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, life, behavior, evolution, bots, self-propelled bots, run-and-tumble motion 

# life: chameleon machines

<< Large language model-based (LLM-based) agents have become common in settings that include non-cooperative parties. In such settings, agents' decision-making needs to conceal information from their adversaries, reveal information to their cooperators, and infer information to identify the other agents' characteristics. To investigate whether LLMs have these information control and decision-making capabilities, (AA) make LLM agents play the language-based hidden-identity game, The Chameleon. >>️

<< Based on the empirical results and theoretical analysis of different strategies, (AA) deduce that LLM-based non-chameleon agents reveal excessive information to agents of unknown identities. (Their) results point to a weakness of contemporary LLMs, including GPT-4, GPT-4o, Gemini 1.5, and Claude 3.5 Sonnet, in strategic interactions. >>

️

Mustafa O. Karabag, Ufuk Topcu. Do LLMs Strategically Reveal, Conceal, and Infer Information? A Theoretical and Empirical Analysis in The Chameleon Game. arXiv: 2501.19398v1 [cs.AI]. Jan 31, 2025.

https://arxiv.org/abs/2501.19398

Also: games, ai (artificial intell), nfulaw, in https://www.inkgmr.net/kwrds.html 

Keywords: life, games, chameleon game, ai, artificial intelligence, LLMs, privacy, nfulaw

# gst: discontinuous transitions to active nematic turbulence.

<< Active fluids exhibit chaotic flows at low Reynolds number known as active turbulence. Whereas the statistical properties of the chaotic flows are increasingly well understood, the nature of the transition from laminar to turbulent flows as activity increases remains unclear. Here, through simulations of a minimal model of unbounded active nematics, (AA) find that the transition to active turbulence is discontinuous. (They) show that the transition features a jump in the mean-squared velocity, as well as bistability and hysteresis between laminar and chaotic flows. >>

<< From distributions of finite-time Lyapunov exponents, (AA) identify the transition at a value A∗≈4900 of the dimensionless activity number. Below the transition to chaos, (They) find subcritical bifurcations that feature bistability of different laminar patterns. These bifurcations give rise to oscillations and to chaotic transients, which become very long close to the transition to turbulence. Overall, (Their) findings contrast with the continuous transition to turbulence in channel confinement, where turbulent puffs emerge within a laminar background. >>

AA << propose that, without confinement, the long-range hydrodynamic interactions of Stokes flow suppress the spatial coexistence of different flow states, and thus render the transition discontinuous. >>️

Malcolm Hillebrand, Ricard Alert. Discontinuous Transition to Active Nematic Turbulence. arXiv: 2501.06085v1 [cond-mat.soft]. Jan 10, 2025.

https://arxiv.org/abs/2501.06085

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

Keywords: gst, chaos, transition, turbulence, jumps, active nematics

# gst: quadrupolar stress drives collapse of nematic order on frictional substrates.

<< The field of active nematics has traditionally employed descriptions based on dipolar activity, with interactions that align along a single axis. However, it has been theoretically predicted that interactions with a substrate, prevalent in most biological systems, would require novel forms of activity, such as quadrupolar activity, that are governed by hydrodynamic screening. >>

<< Here, by combining experiments and numerical simulations, (AA) show that upon light-induced solidification of the underlying medium, microtubule-kinesin mixtures undergo a transformation that leads to a biphasic active suspension. Using an active lyotropic model, (They) prove that the transition is governed by screening effects that alter the dominant form of active stress. Specifically, the combined effect of friction and quadrupolar activity leads to a hierarchical folding that follows the intrinsic bend instability of the active nematic layer. >>

AA << results demonstrate the dynamics of the collapse of orientational order in active nematics and present a new route for controlling active matter by modifying the activity through changing the surrounding environment. >>️

Aleksandra Ardaseva, Ignasi Velez-Ceron, et al. Beyond Dipolar Activity: Quadrupolar Stress Drives Collapse of Nematic Order on Frictional Substrates. arXiv: 2407.03723v3 [cond-mat.soft]. Jan 14, 2025. 

https://arxiv.org/abs/2407.03723

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

Keywords: gst, transition, collapse, active nematics, stress 

# gst: limit cycles and chaos in planar hybrid systems.

<< The main inspiration of (this AA) work is the paper of Llibre and Teixeira (Nonlinear Dyn. 91, No. 1, 249-255, 2018) about Filippov systems formed by two linear centers and having x = 0 as discontinuity line. One of the main conclusions of the paper is that such systems cannot have limit cycles. Actually, either it does not have periodic orbits or every orbit is periodic. Therefore, its dynamics is relatively simple. Inspired by this work and the raising notion of hybrid systems, (AA) wondered what could happen if we allow jumps on the discontinuity line. As a result, (They) discovered not only that limit cycles are allowed with arbitrarily small “perturbations” in the jump, (..), but also that such systems allow chaotic dynamics. Therefore, (AA) conclude that hybrid systems with simple formulation can have rich dynamics. (They) also observe that a complete characterization of the dynamics of X ∈ Xn depends on the characterization of its first return map, which is a piecewise polynomial map on the real line. This, together with the fact that the systems studied here are a generalization of the Filippov systems (..), illustrates that hybrid systems can be seen as a three-fold bridge connecting continuous, piecewise continuous and discrete dynamical systems. >>️

Jaume Llibre, Paulo Santana. Limit cycles and chaos in planar hybrid systems. arXiv: 2407.05151v2 [math.DS]. Oct 1, 2024. 

https://arxiv.org/abs/2407.05151

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

Keywords: gst, limit cycles, chaos, transitions, small perturbations, jumps  

# gst: instability, shocks, and competition interfaces in the Brownian last-passage percolation model

<<  For stochastic Hamilton-Jacobi (SHJ) equations, instability points are the space-time locations where two eternal solutions with the same asymptotic velocity differ. Another crucial structure in such equations is shocks, which are the space-time locations where the velocity field is discontinuous. >>

AA << provide a detailed analysis of the structure and relationships between shocks, instability, and competition interfaces in the Brownian last-passage percolation model, which serves as a prototype of a semi-discrete inviscid stochastic HJ equation in one space dimension. >>

AA << show that the shock trees of the two unstable eternal solutions differ within the instability region and align outside of it. Furthermore, (They) demonstrate that one can reconstruct a skeleton of the instability region from these two shock trees. >>️

Firas Rassoul-Agha, Mikhail Sweeney. Shocks and instability in Brownian last-passage percolation. arXiv:  2407.07866v2 [math.PR]. Oct 18, 2024. 

https://arxiv.org/abs/2407.07866

Also: Brownian last-passage percolation (LPP) model. In: S. GANGULY,  A. HAMMOND. Stability and chaos in dynamical last passage percolation. Jun 7, 2024. 

 https://doi.org/10.1090/cams/35 

Keywords: gst, instability, shock, competition, chaos, percolation

# gst: multiple Pareto-optimal solutions of the dissipation-adaptation trade-off

<< Adaptation refers to the ability to recover and maintain “normal” function on perturbations of internal or external conditions and is essential for sustaining life. Biological adaptation mechanisms are dissipative, i.e., they require a supply of energy such as the coupling to the hydrolysis of ATP. Via evolution the underlying biochemical machinery of living organisms evolved into highly optimized states. However, in the case of adaptation processes two quantities are optimized simultaneously, the adaptation speed or accuracy and the thermodynamic cost. In such cases one typically faces a trade-off, where improving one quantity implies worsening the other. The solution is no longer unique but rather a Pareto set—the set of all physically attainable protocols along which no quantity can be improved without worsening another. >> 

AA << investigate Pareto fronts in adaptation-dissipation trade-offs for a cellular thermostat and a minimal ATP-driven receptor-ligand reaction network. (They) find convex sections of Pareto fronts to be interrupted by concave regions, implying the coexistence of distinct optimization mechanisms. (They) discuss the implications of such “compromise-optimal” solutions and argue that they may endow biological systems with a superior flexibility to evolve, resist, and adapt to different environments. >>️

Jorge Tabanera-Bravo, Aljaz Godec. Multiple Pareto-optimal solutions of the dissipation-adaptation trade-off. 

Phys. Rev. Research 7, 013020. Jan 7, 2025.

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.7.013020

Also: 'dissipation' in FonT  https://flashontrack.blogspot.com/search?q=dissipation

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

(b) https://inkpi.blogspot.com/search?q=adattamento

Keywords: gst, adaptation, dissipation

# gst: wake interference effects on flapping dynamics of elastic inverted foil.

AA << study the self-induced flapping dynamics of an inverted elastic foil when placed in tandem with a stationary circular cylinder. The effect of wake interference on the inverted foil's coupled dynamics is examined at a fixed Reynolds number (Re) as a function of nondimensional bending rigidity (𝐾B) and the structure-to-fluid mass ratio (𝑚*). >>

AA << results show that there exists a critical 𝐾B (..), above which the downstream foil is synchronized with the unsteady wake, and the cylinder controls the flapping response and the wake vortex dynamics. During synchronization, two additional flapping modes, namely, the small- and moderate-amplitude flapping mode, are observed as a function of decreasing 𝐾B. Below 𝐾B,Cr, the downstream foil undergoes self-induced large-amplitude flapping (LAF) similar to that of an isolated foil counterpart. >>

<< When the dynamics of the downstream foil are analyzed for a range of 𝑚*, (AA) can characterize the response dynamics into two regions: low and high sensitivity. The high-sensitivity region is observed when the dynamics are controlled by the cylinder vortex shedding, i.e., for foils with high stiffness. In this regime, the foil dynamics is negatively correlated with 𝐾B and 𝑚*. >>

<< The low-sensitivity region is observed when the downstream foil is no longer synchronized with the wake and undergoes an LAF response, with dynamics that are weakly correlated with 𝐾B. A nondimensional parameter is proposed that combines the effect of the foil's inertia and elastic forces and can capture the foil's response when it is subjected to wake interference effects. >>

Aarshana R. Parekh, Rajeev K. Jaiman. Wake interference effects on flapping dynamics of elastic inverted foil. Phys. Rev. Fluids 10, 014702. Jan 16, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.014702    arXiv: 2311.09339v3 [physics.flu-dyn]. Apr 25, 2024.   https://arxiv.org/abs/2311.09339

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

Keywords: gst, self-induced flapping dynamics, vortex, elasticity, transitions

# gst: tuning to the edge of instability (in the cochlea)

<< Sound produces surface waves along the cochlea's basilar membrane. To achieve the ear's astonishing frequency resolution and sensitivity to faint sounds, dissipation in the cochlea must be canceled via active processes in hair cells, effectively bringing the cochlea to the edge of instability. But how can the cochlea be globally tuned to the edge of instability with only local feedback? >>

<< Surprisingly, (AA) find the basilar membrane supports two qualitatively distinct sets of modes: a continuum of localized modes and a small number of collective extended modes. Localized modes sharply peak at their resonant position and are largely uncoupled. As a result, they can be amplified almost independently from each other by local hair cells via feedback reminiscent of self-organized criticality. >>

<< However, this amplification can destabilize the collective extended modes; avoiding such instabilities places limits on possible molecular mechanisms for active feedback in hair cells. >>

AA << work illuminates how and under what conditions individual hair cells can collectively create a critical cochlea. >>️

Asheesh S. Momi, Michael C. Abbott, et al. Hair Cells in the Cochlea Must Tune Resonant Modes to the Edge of Instability without Destabilizing Collective Modes. PRX Life 3, 013001. Jan 2, 2025.

https://journals.aps.org/prxlife/abstract/10.1103/PRXLife.3.013001 

Also: sound, music, pause, silence, instability, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, acoustics, bifurcations, sensory processes, sound detection, auditory system, ear, criticality, self-organized criticality, sound, music, pause, silence, instability

# gst: phenomenology of cracks in thin colloidal films (undergoing desiccation)

<< A number of geometric and topological properties of samples of crack-template based conductive films are examined to assess the degree to which Voronoi diagrams can successfully model structure and conductivity in such networks. >>

AA << analysis suggests that although Poisson-Voronoi diagrams are only partially successful in modeling structural features of real-world crack patterns formed in films undergoing desiccation, such diagrams can nevertheless be useful in situations where topological characteristics are more important than geometric ones. A phenomenological model is proposed that is more accurate at capturing features of the real-world crack patterns. >>️

Yuri Yu. Tarasevich, Andrei V. Eserkepov, et al. Phenomenological model of crack patterns in thin colloidal films undergoing desiccation. arXiv: 2501.07303v1 [cond-mat.dis-nn]. Jan 13, 2025.

https://arxiv.org/abs/2501.07303

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

Keywords: gst, crack, particles, network, crack pattern networks, Voronoi tessellations 

# jazz: "Spanish Fly" - VAN HALEN II (1979).

<< Un volo pindarico di sola chitarra, di poco meno di un minuto, che si libra tra i solchi incandescenti del secondo album, VAN HALEN II. La leggenda narra che, durante le registrazioni del disco, Eddie si fosse ubriacato una sera a casa del produttore Ted Templeman e si fosse messo a suonare una chitarra acustica. Sconvolto da ciò che stava ascoltando, Templeman decise di inserire quella perla nel disco in lavorazione. In quel minuto Eddie esegue una prova di virtuosismo che lascia senza parole: non è solo abilità tecnica, ma pura musicalità, con un groove che trasforma quella che poteva essere una semplice dimostrazione tecnica in una gemma autentica e compiuta. >>

Gianni Rojatti. Eddie Van Halen oltre "Jump": 5 perle da riscoprire. Jan 26, 2025. 

https://www.radiofreccia.it/notizie/articoli/eddie-van-halen-oltre-jump-5-perle-da-riscoprire/

 "Spanish Fly" - VAN HALEN II (1979).

https://youtu.be/cM7GZXeH6-g 

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

Keywords: jazz, music

# life: the Age of hallucinatory artificial intelligence (AI); the beginning.

<< It’s well known that all kinds of generative AI, including the large language models (LLMs) behind AI chatbots, make things up. This is both a strength and a weakness. It’s the reason for their celebrated inventive capacity, but it also means they sometimes blur truth and fiction, inserting incorrect details into apparently factual sentences. >>

<< They sound like politicians, they tend to make up stuff and be totally confident no matter what. >> Santosh Vempala. ️

<< Chatbots err for many reasons, but computer scientists tend to refer to all such blips as hallucinations. It’s a term not universally accepted, with some suggesting ‘confabulations’ or, more simply, ‘bullshit’. The phenomenon has captured so much attention that the website Dictionary.com picked ‘hallucinate’ as its word of the year for 2023. >>️

<< Because AI hallucinations are fundamental to how LLMs work, researchers say that eliminating them completely is impossible. >>️

Nicola Jones. AI hallucinations can’t be stopped — but these techniques can limit their damage. Nature. 637, 778-780. Jan 21,  2025. 

https://www.nature.com/articles/d41586-025-00068-5

Also: ai (artificial intell) (bot), nfulaw, in https://www.inkgmr.net/kwrds.html 

Keywords: life, ai, artificial intell, LLMs, bot, nfulaw

# gst: scattered waves fuel emergent activity.

<< Active matter taps into external energy sources to power its own processes. Systems of passive particles ordinarily lack this capacity, but can become active if the constituent particles interact with each other nonreciprocally. By reformulating the theory of classical wave-matter interactions, (AA) demonstrate that interactions mediated by scattered waves generally are not constrained by Newton's third law. The resulting center-of-mass forces propel clusters of scatterers, enabling them to extract energy from the wave and rendering them active. This form of activity is an emergent property of the scatterers' state of organization and can arise in any system where mobile objects scatter waves. Emergent activity flips the script on conventional active matter whose nonreciprocity emerges from its activity, and not the other way around. >>

AA << combine theory, experiment, and simulation to illustrate how emergent activity arises in wave-matter composite systems and to explore the phenomenology of emergent activity in experimentally accessible models. These preliminary studies suggest that heterogeneity is a singular perturbation to the dynamics of wave-matter composite systems, and induces emergent activity under all but the most limited circumstances. >>️

Ella M. King, Mia C. Morrell, et al. Scattered waves fuel emergent activity. Phys. Rev. Research 7, 013055. Jan 15, 2025

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.7.013055

Also: waves, particle, self-assembly, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, particle, self-assembly

# gst: apropos of viscoelastic flow instabilities, uncertainty in elastic turbulence.

<< Elastic turbulence can lead to increased flow resistance, mixing and heat transfer. Its control - either suppression or promotion - has significant potential, and there is a concerted ongoing effort by the community to improve our understanding. >>

AA << identify four regimes of uncertainty evolution, characterised by I) rapid transfer to large scales, with large scale growth rates of τ6 (where τ represents time), II) a dissipative reduction of uncertainty, III) exponential growth at all scales, and IV) saturation. These regimes are governed by the interplay between advective and polymeric contributions (which tend to amplify uncertainty), viscous, relaxation and dissipation effects (which reduce uncertainty), and inertial contributions. >>

<< In elastic turbulence, reducing Reynolds number increases uncertainty at short times, but does not significantly influence the growth of uncertainty at later times. At late times, the growth of uncertainty increases with Weissenberg number, with decreasing polymeric diffusivity, and with the logarithm of the maximum length scale, as large flow features adjust the balance of advective and relaxation effects. >>

Jack R. C. King, Robert J. Poole, et al. Uncertainty in Elastic Turbulence. arXiv: 2501.09421v1 [physics.flu-dyn]. Jan 16, 2025. 

https://arxiv.org/abs/2501.09421

Also: uncertainty, elastic, turbulence, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, uncertainty, elastic, elasticity, turbulence 

# life: dear Mr. Donald, fuzzy evidence should be sharper, sooner or later, by Nature

       Nature | 637 | 16 Jan 2025 | 517

<< Mr President-elect, science is a self-correcting process in which bad actors and wrong ideas sooner or later get rooted out and fuzzy evidence becomes sharper. That is the joy and the beauty of the method that has made the modern world what it is. >>️

Editorial. Dear Donald Trump: A letter from Nature on how to make science thrive. Nature 637, 517. Jan 15, 2025.

https://www.nature.com/articles/d41586-025-00050-1

Also: Mr. Donald, forms of power, virus, sars* covid* (aka 1or2achoos), dance, are you ready for all this, in https://www.inkgmr.net/kwrds.html 

Also: A new exception within the FDA Cures Act Informed Consent, the intriguing concept of 'Minimal Risk Clinical Investigations'. FonT. Feb 1, 2024. 

https://flashontrack.blogspot.com/2024/02/life-new-exception-within-fda-cures-act.html 

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

Keywords: life, Mr. Donald, forms of power, virus, sars, covid, 1or2achoos, acad, dance, are you ready

# gst: traveling strings of active dipolar colloids.

AA << study an intriguing new type of self-assembled active colloidal polymer system in 3D. It is obtained from a suspension of Janus particles in an electric field that induces parallel dipoles in the particles as well as self-propulsion in the plane perpendicular to the field. >>

<< At low volume fractions, in experiment, the particles self-assemble into 3D columns that are self-propelled in 2D. Explicit numerical simulations combining dipolar interactions and active self-propulsion find an activity dependent transition to a string phase by increasing dipole strength. >>

AA << classify the collective dynamics of strings as a function of rotational and translational diffusion. (..) (They) also discover long range correlations of the fluctuations along the string contour that grow with the active persistence time, a purely active effect that disappears in the thermal limit. >>

Xichen Chao, Katherine Skipper, et al. Traveling Strings of Active Dipolar Colloids. Phys. Rev. Lett. 134, 018302. Jan 6, 2025. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.018302

Also: particle, colloids, self-assembly, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particle, colloids, self-assembly, Janus, polymers, strings, transition

# gst: diffusion of active particles driven by odd interactions.

<< Odd systems do not conserve energy, violate time-reversal symmetry, and remain far from equilibrium. How odd interactions between particles affect their diffusion remains unknown. >>

<< To investigate this issue, (AA) studied the diffusion and glass transition of a two-dimensional Kob-Andersen mixture, where Brownian particles interact via the Lennard-Jones potential and nonconservative odd forces. (Their) findings indicate a significant influence of odd interactions on the system's diffusion dynamics. Odd interactions always promote diffusion. These interactions lead to a nonmonotonic relationship between the effective diffusion coefficient and particle number density. >>

<< Specifically, in systems with low oddness, the diffusion coefficient decreases steadily with increasing particle number density. Conversely, in systems with moderate oddness, an optimal particle number density exists that maximizes the diffusion coefficient. For systems with high oddness, (AA) observe two distinct peaks in the diffusion coefficient-particle number density relationship. >>

<< Furthermore, (AA) investigation into the glass transition under dense conditions reveals that adjusting the oddness at low temperatures can induce a transition from a glassy state to a liquid state. >>

Rui-xue Guo, Jia-jian Li, Bao-quan Ai.

Diffusion of active particles driven by odd interactions. Phys. Rev. E 111, 014105. Jan 3, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.014105

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

Keywords: gst, particles, diffusion, 

active brownian particles, oddness, odd interactions

# gst: chaotic dynamics creates and destroys branched flow.

<< The phenomenon of branched flow, visualized as a chaotic arborescent pattern of propagating particles, waves, or rays, has been identified in disparate physical systems ranging from electrons to tsunamis, with periodic systems only recently being added to this list. >>

Here, AA << explore the laws governing the evolution of the branches in periodic potentials. On one hand, (They) observe that branch formation follows a similar pattern in all nonintegrable potentials, no matter whether the potentials are periodic or completely irregular. Chaotic dynamics ultimately drives the birth of the branches. >>

<< On the other hand, (AA) results reveal that for periodic potentials the decay of the branches exhibits new characteristics due to the presence of infinitely stable branches known as superwires. Again, the interplay between branched flow and superwires is deeply connected to Hamiltonian chaos. >>

Alexandre Wagemakers, Aleksi Hartikainen, et al. Chaotic dynamics creates and destroys branched flow. Phys. Rev. E 111, 014214. Jan 7, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.014214

arXiv: 2406.12922v2 [nlin.PS]. 

https://arxiv.org/abs/2406.12922

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

Keywords: gst, chaos, waves, branched flows, superwires, transitions

# gst: acceleration of enzymatic reactions due to nearby inactive binding sites.

<< Many biological molecular motors and machines are driven by chemical reactions that occur in specific catalytic sites. (AA) study whether the arrival of molecules to such an active site can be accelerated by the presence of a nearby inactive site.  >>️

AA << identify two parameter regimes in which the reaction is accelerated. >>️

<< In the first regime, the inactive site stores a molecule in order to release it following a reaction, when the neighboring catalytic site is empty. >>

<< In the second regime, the inactive site releases a molecule when the catalytic site is full, in order to impede the molecules from leaving the active site before they react. For the storage mechanism, which is more likely to be biologically relevant, the acceleration can reach up to 15%, depending on parameters. >>️

Hila Katznelson, Saar Rahav. Acceleration of enzymatic reactions due to nearby inactive binding sites. arXiv: 2501.01662v1 [cond-mat.stat-mech]. Jan 3, 2025.

https://arxiv.org/abs/2501.01662  

Phys. Rev. Research 6, 043330. Dec 30, 2024. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.043330

Keywords: gst, enzymes, enzymatic catalysis, catalytic sites, inactivity, inactive binding sites

# gst: dynamics of swarmalators in the presence of a contrarian.

<< Swarmalators are entities that combine the swarming behavior of particles with the oscillatory dynamics of coupled phase oscillators and represent a novel and rich area of study within the field of complex systems. >>

<< Unlike traditional models that treat spatial movement and phase synchronization separately, swarmalators exhibit a unique coupling between their positions and internal phases, leading to emergent behaviors that include clustering, pattern formation, and the coexistence of synchronized and desynchronized states, etc. >>

This AA paper << presents a comprehensive analysis of a two-dimensional swarmalator model in the presence of a predatorlike agent that (They) call a contrarian. The positions and the phases of the swarmalators are influenced by the contrarian and (They)  observe the emergence of intriguing collective states. >>

AA find << that swarmalator phases are synchronized even with negative coupling strength when their interaction with the contrarian is comparatively strong. Through a combination of analytical methods and simulations, (They) demonstrate how varying these parameters can lead to transitions between different collective states. >>

Gourab Kumar Sar, Sheida Ansarinasab, et al. Dynamics of swarmalators in the presence of a contrarian. Phys. Rev. E 111, 014209. Jan 7, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.014209 

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

Keywords: gst, swarm, swarmalators, transitions, behavior, behaviour

# gst: trade-off between coherence and dissipation for excitable phase oscillators.

<< Thermodynamic uncertainty relation (TUR) bounds coherence in stochastic oscillatory systems. In this paper, (AA) show that both dynamical and thermodynamic bounds play important roles for the excitable oscillators, e.g. neurons. >>

<< Excitable systems such as neurons have distinctive coherence features compared with other oscillators having no excitability. >>️

AA << combined the well-established results, i.e. the fluctuation of the ISI (inter-spike-interval) limited by 1/3 and the coherence resonance phenomenon, together with the TUR developed in recent years to investigate the coherence in the excitable phase oscillators. (AA) find quite different trade-off relation in the subthreshold (excitable) region and superthreshold (oscillatory) region, separated by the SNIC (saddle-node on an invariant circle) bound but meanwhile lower bounded by the TUR. Furthermore, (They) found that there is an optimal entropy production corresponding to the maximum coherence, which could serve as an alternative interpretation of the coherence resonance. It implies that more entropy production does not necessarily result in higher accuracy of currents. >>️

Chunming Zheng. Trade-off between coherence and dissipation for excitable phase oscillators. arXiv: 2412.16603v1 [cond-mat.stat-mech]. Dec 21, 2024.

https://arxiv.org/abs/2412.16603

Also: brain, entropy, dissipation, uncertainty, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, brain, neurons, entropy, oscillators, excitable phase oscillators, coherence, dissipation, uncertainty

# gst: stochastic Scovil-Schulz-DuBois (SSDB) machine and its three types of cycles

<< Three types of cycles are identified in the quantum jump trajectories of the Scovil–Schulz-DuBois (SSDB) machine. An R cycle as refrigeration, an H cycle as a heat engine, and an N cycle in which the machine is neutral. >>

AA << find that in the large time limit, whether the machine operates as a heat engine or refrigerator depends on the ratio between the numbers of R cycles and H cycles per unit time. Further increasing the hot bath temperature above a certain threshold does not increase the machine's power output. The cause is that, in this situation, the N cycle has a greater probability than the H cycle and R cycle. >>

<< Although the SSDB machine operates by randomly switching between these three cycles, at the level of a single quantum jump trajectory, its heat engine efficiency and the refrigerator's coefficient of performance remain constant. >>

Fei Liu, Jiayin Gu. Stochastic Scovil–Schulz-DuBois machine and its three types of cycles. Phys. Rev. E 111, 014108. Jan 3, 2025. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.014108 

arXiv: 2409.04124v2 [cond-mat.stat-mech]. Jan 5, 2025. 

https://arxiv.org/abs/2409.04124

Keywords: gst, stochasticity, quantum heat engines & refrigerators, stochastic Scovil–Schulz-DuBois (SSDB) machine 

# gst: equilibrium and breakup regimes of stretched soap bubbles

AA << combine experiments and theoretical derivations to study the evolution of a stretched soap bubble and compare it with an open film to highlight the effect of volume conservation. (They) identify a critical length for both surfaces, beyond which a bottleneck develops in the middle and begins to shrink irreversibly, ultimately pinching off into multiple compartments. >>

<< Before leaving the equilibrium regime, surface energy minimization governs the shape, which can be addressed theoretically via the variational method. In contrast to open films, soap bubble volume conservation introduces a Lagrange multiplier, analogous to a pressure difference, mediating long-range shape evolution. >>

<< By examining how boundary constraints influence deformation, (AA) contrast the bubble's convex-to-concave transition with the behavior of soap films under similar conditions. (Their) analysis of equilibrium and breakup regimes reveals critical differences between bubble and film stability profiles, shedding light on universal behaviors in non-equilibrium fluid mechanics, with implications for biological and material sciences.

>>️

Wei-Chih Li, Chih-Yao Shih, et al. How soap bubbles change shape while maintaining a fixed volume of air? arXiv: 2412.17870v1 [physics.flu-dyn]. Dec 21, 2024. 

https://arxiv.org/abs/2412.17870

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

Keywords: gst, bubble, drop, droplet, droploid, transition

# gst: black swan ... or black rabbit?

<<

In his book The Black Swan: The Impact of the Highly Improbable, Nassim Nicholas Taleb explores the profound and unpredictable events that shape our world, which he calls “Black Swans.” These events are characterized by three main features: they are rare and unpredictable, they have an extreme impact, and in hindsight, they often seem explainable or inevitable. Taleb argues that our world is increasingly shaped by these Black Swans, from financial crises to technological breakthroughs, and yet humans are inherently ill equipped to anticipate them due to cognitive biases and reliance on standard predictive models. By analogy with this term, (AA) have named Black Rabbits events that exhibit all the external characteristics of a Black Swan but are entirely determined by the state of the system itself. These phenomena are not artificial examples or mere curiosities; they exist wherever hyperbolic meadows are found. When we witness a social catastrophe or a financial crisis, could it be not a stray Black Swan but a local Black Rabbit? How can one determine in advance that a system is pregnant with a crisis? What indicators can be used? Is it possible to control the system to prevent it from becoming unstable? These are intriguing questions, perhaps too complex, especially when dealing not with simple mathematical models but with real-world systems. Yet, we must still strive to find answers to them.

>>

Alexey Solyanik. The Black Rabbits of Fibonacci. arXiv: 2412.20222v1 [math.DS]. Dec 28, 2024.

https://arxiv.org/abs/2412.20222

Also: gst - general system theory, analogy, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, analogy

# life: a bizarre 'aleatorio torneamento' revisited; Mickey Mouse (et al.) collapsed, by Ann

<< nelle gronde d' estremo tono dal ristagno d' eterno memento ... //

(..)

tr'astratti lamenti dallo sciamante stenotermo sognante tremore // >>

Aleatorio torneamento. Notes. (quasi-stochastic poetry). Feb 09, 2006.

https://inkpi.blogspot.com/2006/02/1955-aleatorio-torneamento.html 

<< Ann Telnaes, a long-time Washington Post cartoonist, created a cartoon of Mr Bezos and other tycoons kneeling before a statue of President-elect Donald Trump. >>

<< In the cartoon, Mr Bezos, Meta founder Mark Zuckerberg and OpenAI's Sam Altman are depicted on their knees giving bags of cash to a statue of Trump.

Mickey Mouse is also depicted prostrate in the cartoon. ABC News – which is owned by Disney – last month agreed to pay $15m to settle a defamation lawsuit filed by Trump. >>

Ana Faguy. Washington Post cartoonist quits after Bezos satire is rejected. Jan 4, 2025. https://www.bbc.com/news/articles/cn4xk4y2emro  

Ann Telnaes. Why I'm quitting the Washington Post. Jan 4, 2025. 

https://anntelnaes.substack.com/p/why-im-quitting-the-washington-post     https://anntelnaes.com     https://x.com/AnnTelnaes     https://en.m.wikipedia.org/wiki/Ann_Telnaes

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

Keywords: life, Donald, Potus, Potus race

# gst: floating droplets excited with Faraday waves

<< The Faraday instability has been extensively studied in bounded containers but only recently has research on this phenomenon in flexible domains been conducted. (AA) study floating liquid droplets with Faraday waves excited on their surface, which undergo a slow time evolution toward a stable noncircular shape. (AA) develop a theoretical model for the evolution of the boundary of the droplet, thus allowing to simulate its full transient motion toward steady state. >>

<< By changing the forcing frequency and amplitude of (the) system, (They) observe a variety of stable droplet shapes. (..) Interesting transient behavior such as hysteresis is also discussed, where the final droplet shape depends on its previous shape. Finally, (They) touch upon droplets that do not reach a steady state shape, instead oscillating periodically in time or rotating at a constant angular velocity. >>️

L. Mazereeuw. Theoretical and experimental investigation of the shapes formed by floating droplets excited with Faraday waves. Phys. Rev. Fluids 9, 124404. Dec 19, 2024.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.124404

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

Keywords: drops, droplets, droploids, waves, instability, Faraday instability, transitions   

# gst: soliton dynamics over a disordered topography

AA << report on the dynamics of a soliton propagating on the surface of a fluid in a 4-m-long canal with a random or periodic bottom topography. Using a full space-and-time resolved wave field measurement, (They) evidence, for the first time experimentally, how the soliton is affected by the disorder, in the context of Anderson localization, and how localization depends on nonlinearity. >>

<< For weak soliton amplitudes, the localization length is found in quantitative agreement with a linear shallow-water theory. For higher amplitudes, this spatial attenuation of the soliton amplitude is found to be enhanced. >>

<< Behind the leading soliton slowed down by the topography, different experimentally unreported dynamics occur: fission into backward and forward nondispersive pulses for the periodic case, and scattering into dispersive waves for the random case. >>

Guillaume Ricard, Eric Falcon. Soliton Dynamics over a Disordered Topography. Phys. Rev. Lett. 133, 264002. Dec 27, 2024.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.133.264002

Also: soliton, waves, disorder, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, soliton, waves, disorder

# gst: self-organized critical dynamic on the Sierpinski carpet.

<< Self-organized criticality is a dynamical system property where, without external tuning, a system naturally evolves towards its critical state, characterized by scale-invariant patterns and power-law distributions.  >>️

In this paper, AA << explored a self-organized critical dynamic on the Sierpinski carpet lattice, a scale-invariant structure whose dimension is defined as a power law with a noninteger exponent, i.e., a fractal. To achieve this, (They) proposed an Ising–bond-correlated percolation model as the foundation for investigating critical dynamics.  >>️

<< Within this framework, (AA) outlined a feedback mechanism for critical self-organization and followed an algorithm for its numerical implementation. The results obtained from the algorithm demonstrated enhanced efficiency when driving the Sierpinski carpet towards critical self-organization compared to a two-dimensional lattice.  >>️

Viviana Gomez, Gabriel Tellez. Self-organized critical dynamic on the Sierpinski carpet. Phys. Rev. E 110, 064141. Dec 20, 2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.110.064141 

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

Keywords: gst, self-assembly, criticality, self-organized critical dynamics, transitions.