# 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.

https://arxiv.org/abs/2505.20488

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

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

# 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.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.053607

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.

# 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.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.054220

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.

# 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

https://arxiv.org/abs/2505.22737

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.

# 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. 

https://arxiv.org/abs/2505.16653

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.

# life: oops! Artificial intelligence (AI) could use your data to blackmail you if you try to disconnect it

<< Anthropic released the next iterations of its Claude AI models on Thursday. Artificial intelligence (AI) firm Anthropic says testing of its new system revealed it is sometimes willing to pursue "extremely harmful actions" such as attempting to blackmail engineers who say they will remove it. >>

<< The firm launched Claude Opus 4 on Thursday, saying it set "new standards for coding, advanced reasoning, and AI agents." >>

https://www.anthropic.com/news/claude-4

<< But in an accompanying report, it also acknowledged the AI model was capable of "extreme actions" if it thought its "self-preservation" was threatened. >>

https://www-cdn.anthropic.com/4263b940cabb546aa0e3283f35b686f4f3b2ff47.pdf

<< Potentially troubling behaviour by AI models is not restricted to Anthropic. >>

<< Commenting on X, Aengus Lynch - who describes himself on LinkedIn as an AI safety researcher at Anthropic - wrote: "It's not just Claude. >>

https://x.com/aengus_lynch1/status/1925746802147426450

Liv McMahon. AI system resorts to blackmail if told it will be removed. BBC. May 23, 2025.

https://www.bbc.com/news/articles/cpqeng9d20go

Also: "qui non e' impossibile immaginare",  in: anomalous formation of molecules after vapor deposition. FonT. Dec 31, 2015.

https://flashontrack.blogspot.com/2015/12/rmx-s-gst-anomalous-formation-of.html

Also: ai (artificial intell), oops, are you ready, in https://www.inkgmr.net/kwrds.html 

Keywords: life, oops, AI, artificial intelligence, high-agency behavior, self-preservation, sycophantic AI, blackmail, opportunistic blackmail, extreme blackmail behavior, are you ready.

# gst: apropos of double-wells, stabilizing role of multiplicative noise in nonconfining potentials.

AA << provide a simple framework for the study of parametric (multiplicative) noise, making use of scale parameters. (They) focus on a large class of one-dimensional stochastic differential equations in which the deterministic drift pushes trajectories toward infinity. (AA) show that increasing the multiplicative noise intensity surprisingly causes the mass of the stationary probability distribution to become increasingly concentrated around the points of minimal multiplicative noise strength. Under quite general conditions the trajectory exhibits intermittent burstlike jumps away from these minima. (AA) framework relies on first-term expansions, which become more accurate for larger noise intensities. >>

<< In this work (AA) show that the full width at half maximum in addition to the maximum is appropriate for quantifying the stationary probability distribution (instead of the mean and variance, which are often undefined). (They) define a corresponding kind of weak-sense stationarity. (AA) end by applying these results to the problem of a double-well potential with multiplicative noise, where noise stabilizes unstable fixed points. >>

Ewan T. Phillips, Benjamin Lindner, Holger Kantz. Stabilizing role of multiplicative noise in nonconfining potentials. Phys. Rev. Research 7, 023146. May 14, 2025.

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.7.023146

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

Keywords: gst, noise, multiplicative noise intensity, intermittency, intermittent burstlike jumps, stationary probability distribution, weak-sense stationarity, double-well potential.