martedì 15 luglio 2025

# gst: additional jamming transition in two-dimensional bidisperse granular packings.

AA << ️present a jamming diagram for two-dimensional bidisperse granular systems, capturing two distinct jamming transitions. The first occurs as large particles form a jammed structure, while the second, emerging at a critical small-particle concentration, 𝑋*_S ≈0.21, and size ratio, 𝛿*≈0.25, involves small particles jamming into the voids of the existing large-particle structure upon further compression. >>

<< ️Below this threshold, small particles fill voids within the large-particle network, increasing packing density. Beyond this point, excess small particles disrupt efficient packing, resulting in looser structures. These results, consistent with previous three-dimensional studies, demonstrate that the second transition occurs at a well-defined point in the (𝑋_S,𝛿) plane, independent of dimensionality, likely driven by the geometric saturation of available space around particles, void closure, and structural arrangement. >>

<< ️The second transition reveals that jamming in mixtures of differently sized particles does not occur through a single, unified process. Instead, it can involve multiple, distinct transitions, each associated with a specific particle size and contributing uniquely to the emergence of rigidity through excluded area effects and spatial organization. >>

Juan C. Petit, Matthias Sperl. Additional jamming transition in two-dimensional bidisperse granular packings. Phys. Rev. Research 7, L022073. Jun 20, 2025.

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

Keywords: gst, particles, granular packing, jamming, disorder, transitions. 

lunedì 14 luglio 2025

# gst: dynamics and chaotic properties of the fully disordered Kuramoto model.

<< ️Frustrated random interactions are a key ingredient of spin glasses. From this perspective, (AA) study the dynamics of the Kuramoto model with quenched random couplings: the simplest oscillator ensemble with fully disordered interactions. (AA) answer some open questions by means of extensive numerical simulations and a perturbative calculation (the cavity method). (They) show frequency entrainment is not realized in the thermodynamic limit and that chaotic dynamics are pervasive in parameter space.  >>

<< ️In the weak coupling regime, (AA) find closed formulas for the frequency shift and the dissipativeness of the model. Interestingly, the largest Lyapunov exponent is found to exhibit the same asymptotic dependence on the coupling constant irrespective of the coupling asymmetry, within the numerical accuracy. >>

Iván León, Diego Pazó. Dynamics and chaotic properties of the fully disordered Kuramoto model. arXiv:2507.05168v1 [cond-mat.dis-nn]. Jul 7, 2025.

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

Keywords: gst, disorder & fluctuations, weakness, chaos, transitions, volcano transition, slow relaxation, quasientrainment, freezing, nonreciprocity.

sabato 12 luglio 2025

# gst: chimera states with multiple coexisting solutions.

AA << ️report on the emergence of chimera states in extended systems characterized by the coexistence of more than two spatiotemporal solutions. Specifically, (They) show that three-domain chimeras may generically appear in reaction-diffusion systems under three conditions, with a crucial role played by the existence of a Maxwell point. >>

AA << verify the universality of (their) findings by analyzing five different models, and demonstrate that such new chimeras are independent of the boundary conditions imposed. >>

Gui-Quan Sun, Zhi-Chao Xue, et al. Chimera states with multiple coexisting solutions. Phys. Rev. Research 7, 023289. Jun 20, 2025.

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

Keywords: gst, chimera, chaos, transitions.

venerdì 11 luglio 2025

# gst: wave-kinetic dynamics of forced-dissipated turbulent internal gravity waves

<< Internal gravity waves are an essential feature of stratified media, such as oceans and atmospheres. >>

<< To investigate their dynamics, (AA) perform simulations of the forced-dissipated kinetic equation describing the evolution of the energy spectrum of weakly nonlinear internal gravity waves. >>

<< During the early evolution, three well-known nonlocal interactions, the elastic scattering, the induced diffusion, and the parametric subharmonic instability, together with a superharmonic resonance play a prominent role. >>

<< In contrast, local interactions are responsible for anisotropic energy cascade on longer timescales. >>

AA << reveal emergence of a condensate at small horizontal wave vectors that can be interpreted as a pure wave-wave interaction-mediated layering process. >>

Vincent Labarre, Giorgio Krstulovic, Sergey Nazarenko. Wave-Kinetic Dynamics of Forced-Dissipated Turbulent Internal Gravity Waves. Phys. Rev. Lett. 135, 014101. Jul 1, 2025.

arXiv:2407.11469v3 [physics.flu-dyn]. Mar 28, 2025.

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

Keywords: gst, waves, weakness, turbulence, transitions, stratified turbulence, wave-turbulence interactions, weak turbulence.

giovedì 10 luglio 2025

# gst: energy spectra and fluxes of 2D turbulent quantum droplets.

AA << explore the energy spectra and associated fluxes of turbulent two-dimensional quantum droplets subjected to a rotating paddling potential which is removed after a few oscillation periods. A systematic analysis on the impact of the characteristics (height and velocity) of the rotating potential and the droplet atom number reveals the emergence of different dynamical response regimes. >>

<< ️Significant distortions are observed in the droplet periphery in the presence of a harmonic trap. A direct energy cascade (from large to small length scales) is mainly identified through the flux. >>

Their << ️findings offer insights into the turbulent response of exotic phases of matter, featuring quantum fluctuations, and may inspire investigations aiming to unravel self-similar nonequilibrium dynamics. >>

Shawan Kumar Jha, Mahendra K. Verma, et al. Energy spectra and fluxes of two-dimensional turbulent quantum droplets. Phys. Rev. Fluids 10, 064618. Jun 25, 2025.

arXiv:2501.01771v1 [cond-mat.quant-gas]. Jan 3, 2025.

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

Keywords: gst, drop, droplet, droploid, turbulence, vortex, harmonic trap, quantum fluctuations, exotic phases of matter, self-similar nonequilibrium dynamics

mercoledì 9 luglio 2025

# gst: the evasion of tipping; pattern formation near a Turing-fold bifurcation

<< ️Model studies indicate that many climate subsystems, especially ecosystems, may be vulnerable to 'tipping': a 'catastrophic process' in which a system, driven by gradually changing external factors, abruptly transitions (or 'collapses') from a preferred state to a less desirable one. In ecosystems, the emergence of spatial patterns has traditionally been interpreted as a possible 'early warning signal' for tipping. More recently, however, pattern formation has been proposed to serve a fundamentally different role: as a mechanism through which an (eco)system may 'evade tipping' by forming stable patterns that persist beyond the tipping point. >>

<< ️Mathematically, tipping is typically associated with a saddle-node bifurcation, while pattern formation is normally driven by a Turing bifurcation. Therefore, (AA) study the co-dimension 2 Turing-fold bifurcation and investigate the question: 'When can patterns initiated by the Turing bifurcation enable a system to evade tipping?' >>

AA << develop (their) approach for a class of phase-field models and subsequently apply it to -component reaction-diffusion systems -- a class of PDEs often used in ecosystem modeling. (AA) demonstrate that a two-component system of modulation equations governs pattern formation near a Turing-fold bifurcation, and that tipping will be evaded when a critical parameter, β, is positive. (They) derive explicit expressions for β, allowing one to determine whether a given system may evade tipping. Moreover, (They) show numerically that this system exhibits rich behavior, ranging from stable, stationary, spatially quasi-periodic patterns to irregular, spatio-temporal, chaos-like dynamics. >>

Dock Staal, Arjen Doelman. The evasion of tipping: pattern formation near a Turing-fold bifurcation. arXiv: 2506.22251v1 [math.DS]. Jun 27, 2025.

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

Keywords: gst, disorder & fluctuations, pattern formation, Turing-fold bifurcation, transitions, tipping, collapse

lunedì 7 luglio 2025

# gst: allosteric lever: toward a principle of specific allosteric response.

<< ️Allostery, the phenomenon by which the perturbation of a molecule at one site alters its behavior at a remote functional site, enables control over biomolecular function. >>

<< ️However, a general principle of allostery, i.e., a set of quantitative and transferable “ground rules,” remains elusive. It is neither a set of structural motifs nor intrinsic motions. >>

<< ️Focusing on elastic network models, (AA) here show that an allosteric lever—a mode-coupling pattern induced by the perturbation—governs the directional, source-to-target, allosteric communication: A structural perturbation of an allosteric site couples the excitation of localized hard elastic modes with concerted long-range soft-mode relaxation. >>

<< ️Perturbations of nonallosteric sites instead couple hard and soft modes uniformly. The allosteric response is shown to be generally nonlinear and nonreciprocal, and allows for minimal structural distortions to be efficiently transmitted to specific changes at distant sites. Allosteric levers exist in proteins and “pseudoproteins”—networks designed to display an allosteric response. >>

<< ️Interestingly, protein sequences that constitute allosteric transmission channels are shown to be evolutionarily conserved. >>

Maximilian Vossel, Bert L. de Groot, Aljaž Godec. Allosteric Lever: Toward a Principle of Specific Allosteric Response. Phys. Rev. X 15, 021097. Jun 20, 2025


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

Keywords: gst, allostery, allosteric lever, elasticity, networks, elastic networks.

sabato 5 luglio 2025

# gst: transient and steady-state chaos in dissipative quantum systems.


<< Dissipative quantum chaos plays a central role in the characterization and control of information scrambling, non-unitary evolution, and thermalization, but it still lacks a precise definition. >>

AA << properly restore the quantum-classical correspondence through a dynamical approach based on entanglement entropy and out-of-time-order correlators (OTOCs), which reveal signatures of chaos beyond spectral statistics. Focusing on the open anisotropic Dicke model, (They) identify two distinct regimes: transient chaos, marked by rapid early-time growth of entanglement and OTOCs followed by low saturation values, and steady-state chaos, characterized by high long-time values. >>

AA << introduce a random matrix toy model and show that Ginibre spectral statistics signals short-time chaos rather than steady-state chaos. (Their) results establish entanglement dynamics and OTOCs as reliable diagnostics of dissipative quantum chaos across different timescales. >>

Debabrata Mondal, Lea F. Santos, S. Sinha. Transient and steady-state chaos in dissipative quantum systems. arXiv: 2506.05475v1 [quant-ph]. Jun 5, 2025. 

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

Keywords: gst, information scrambling, entropy, chaos, transient chaos, steady-state chaos.

venerdì 4 luglio 2025

# gst: chimera states on m-directed hypergraphs.

<< Chimera states are synchronization patterns in which coherent and incoherent regions coexist in systems of identical oscillators. This elusive phenomenon has attracted a lot of interest and has been widely studied, revealing several types of chimeras. Most cases involve reciprocal pairwise couplings, where each oscillator exerts and receives the same interaction, modeled via networks. >>️

<< However, real-world systems often have non-reciprocal, non-pairwise (many-body) interactions. From previous studies, it is known that chimera states are more elusive in the presence of non-reciprocal pairwise interactions, while easier to be found when the latter are reciprocal and higher-order (many-body). >>️

<< In this work, (AA) investigate the emergence of chimera states on non-reciprocal higher-order structures, called m-directed hypergraphs, and (They) show that, not only the higher-order topology allows the emergence of chimera states despite the non-reciprocal coupling, but also that chimera states can emerge because of the directionality. >>️

<< Finally, (AA) compare the latter results with the one resulting from non-reciprocal pairwise interactions: their elusiveness confirms that the observed phenomenon is thus due to the presence of higher-order interactions. The nature of phase chimeras has been further validated through phase reduction theory. >>️

Rommel Tchinda Djeudjo, Timoteo Carletti, et al. Chimera states on m-directed hypergraphs. arXiv: 2506.12511v1 [nlin.PS]. Jun 14, 2025. 

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

Keywords: gst, chimera, networks, non-reciprocal pairwise interactions, non-reciprocal higher-order structures, m-directed hypergraphs.

giovedì 3 luglio 2025

# gst: nonstationary critical phenomena: expanding the critical point.

<< A prototypical model of symmetry-broken active matter -- biased quorum-sensing active particles (bQSAPs) -- is used to extend notions of dynamic critical phenomena to the paradigmatic setting of driven transport, where characteristic behaviours are nonstationary and involve persistent fluxes. >>

<< To do so, (AA) construct an effective field theory with a single order-parameter -- a nonstationary analogue of active Model B -- that reflects the fact that different properties of bQSAPs can only be interpreted in terms of passive thermodynamics in appropriately chosen inertial frames. This codifies the movement of phase boundaries due to nonequilibrium fluxes between coexisting bulk phases in terms of a difference in effective chemical potentials and therefore an 'unequal' tangent construction on a bulk free energy density. >>

<< The result is both an anomalous form of coarsening and, more generally, an exotic phase structure; binodals are permitted to cross spinodal lines so that criticality is no longer constrained to a single point. >>

<< Instead, criticality, with exponents that are seemingly unchanged from symmetric QSAPs, is shown to exist along a line that marks the entry to an otherwise forbidden region of phase space. The interior of this region is not critical in the conventional sense, but retains certain features of criticality, which (AA) term pseudo-critical. >>

<< Whilst an inability to satisfy a Ginzburg criterion implies that fluctuations remain relevant at macroscopic scales, finite-wavenumber fluctuations grow at finite rates and exhibit non-trivial dispersion relations. The interplay between the growth of fluctuations and the speed at which they move relative to the bulk results in distinct regimes of micro- and meso-phase separation. >>

Richard E. Spinney, Richard G. Morris. Nonstationary critical phenomena: expanding the critical point. Phys. Rev. E 111, 064129. Jun 23, 2025.

arXiv: 2412.15627v2 [cond-mat.stat-mech]. Jun 25, 2025. 

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

Keywords: gst, particles, active particles, disorder & fluctuations, criticality, pseudo-criticality, transitions.

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

martedì 1 luglio 2025

# game: Parrondo's paradox in space-inhomogeneous quantum walks.

<< The term Parrondo's paradox refers to the apparently paradoxical effect whereby two or more dynamics in which a given quantity decreases are combined in such a way that the same quantity increases in the resulting dynamics. >>

AA << show that Parrondo's paradox can occur not only in the case of homogeneous but also in space-inhomogeneous one-dimensional discrete-time quantum walks. >>

<< Moreover, (They) demonstrate that for such quantum walks Parrondo's paradox can affect the time evolution of quantum entanglement differently than it does in the case of homogeneous ones. >>

Zbigniew Walczak, Jarosław H. Bauer. Parrondo's paradox in space-inhomogeneous quantum walks. Phys. Rev. E 111, 064218. Jun 25, 2025.

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

Keywords: Parrondo, games

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.

venerdì 20 giugno 2025

# life: Ozzy's unexpected, on the air, sweet gift to future generations; 'Clone Me, You Bastards'

<< Yes, we really got the Prince of Darkness to drink from 10 cans of our low-calorie Iced Tea. And yes, he actually crushed each can himself. In the process, he left behind trace DNA from his saliva that you can now own. He even hand-signed each packaging label. >>

<< Now, when technology and federal law permits, you’ll be able to replicate Ozzy Osbourne and enjoy him for hundreds of years into the future. But you better hurry, there are only 10 Infinitely Recyclable Ozzy cans available to buy here:   https://liquiddeath.com/en-it/pages/ozzy >>

Buy Ozzy Osbourne's DNA From Liquid Death. youtube.com. Jun 17, 2025.

   << 
  Flavors
● Sweet Reaper.
● Blueberry Buzzsaw.
● Slaughter Berry.
● Green Guillotine.
● Dead Billionaire.
● Rest In Peach.
   >>


<< The Prince of Darkness is teaming up with Liquid Death to sell empty iced tea cans he's drank from. >>

Marina Watts. Ozzy Osbourne Sells His DNA on Liquid Death Cans for the Low Price of $450: 'Clone Me, You Bastards'. People. Jun 18, 2025. 


Also: saliva, are you ready, in https://www.inkgmr.net/kwrds.html 

Also: a different way to approach cloning: exponential post-Donald (without Donald), how AI could interfere (drive) next political elections. FonT. May 9, 2023.   https://flashontrack.blogspot.com/2023/05/life-exponential-post-donald-without.html


Keywords: life, saliva, human cloning, are you ready

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

sabato 14 giugno 2025

# aibot: noise balance and stationary distribution of stochastic gradient descent.


<< The stochastic gradient descent (SGD) algorithm is the algorithm (is used) to train neural networks. However, it remains poorly understood how the SGD navigates the highly nonlinear and degenerate loss landscape of a neural network. >>

<< In this work, (AA) show that the minibatch noise of SGD regularizes the solution towards a noise-balanced solution whenever the loss function contains a rescaling parameter symmetry. Because the difference between a simple diffusion process and SGD dynamics is the most significant when symmetries are present, (AA) theory implies that the loss function symmetries constitute an essential probe of how SGD works. (They) then apply this result to derive the stationary distribution of stochastic gradient flow for a diagonal linear network with arbitrary depth and width. >>

<< The stationary distribution exhibits complicated nonlinear phenomena such as phase transitions, broken ergodicity, and fluctuation inversion. These phenomena are shown to exist uniquely in deep networks, implying a fundamental difference between deep and shallow models. >>

Liu Ziyin, Hongchao Li, Masahito Ueda. Noise balance and stationary distribution of stochastic gradient descent. Phys. Rev. E 111, 065303. Jun 6, 2025.

Also: ai (artificial intell) (bot), network, noise, disorder & fluctuations, in https://www.inkgmr.net/kwrds.html 

Keywords: ai, artificial intelligence, noise, stochasticity, networks, neural networks, deep learning,stochastic gradient descent (SGD), transitions, phase transitions, broken ergodicity, fluctuation inversion

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.

sabato 7 giugno 2025

# life: apropos of Trump-Musk dipole, an immediate MJQ apoptotic rift

<< In the last two days, the once powerful relationship between President Donald Trump and billionaire Elon Musk has unraveled as they took jabs at each other from their respective social media sites, X and Truth Social. Musk left his official role in the administration late last month. See how the digital confrontation devolved from complaints over the president’s tax bill to Musk alleging Trump was “in the Epstein files.” . >>

Rachel Lerman. A timeline of Musk and Trump’s devolving relationship. washingtonpost.com. Jun 6, 2025.

FonT: an Ivy League Academic (e.g. a Harvard academic) could, as a funny hypothesis (and just to check if and how it works), to try to restore this form of sadic intermittent acyclic pseudo MJQ dipole; in this regard He/She/? could be immediately operational as a catalytic fractal epizeusis entity (obviously without ideological prejudices) to play Parrondo game to drive a quasi-stochastic tit-for-tat cooperative strategy. 

Soloperosservarecosasuccedeanzicheforse ...

Also: tit-for-tat, game, Parrondo, 
game, apoptosis, Mr. Donald, in https://www.inkgmr.net/kwrds.html

Also: MJQ, in FonT https://flashontrack.blogspot.com/search?q=mjq. in Notes (quasi-stochastic poetry) Attrattore cooperativo bipolare (nell' elastici spigoli), Mar 5, 2007. https://inkpi.blogspot.com/2007/03/2124-attrattore-cooperativo-bipolare.html


Also: sadico, in Notes (quasi-stochastic poetry) https://inkpi.blogspot.com/search?q=sadico

Keywords: life, Parrondo, Tit-for-Tat, MJQ, epizeusis, POTUS, Mr.Donald, Trump-Musk, sadistic, apoptosis, billiards, dance.

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.

sabato 31 maggio 2025

# 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." >>

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

<< 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. >>

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

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

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.

venerdì 30 maggio 2025

# 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.

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.


mercoledì 28 maggio 2025

# gst: defect-free and defective adaptations of crystalline sheets to stretching deformation.

<< The elastic response of the crystalline sheet to the stretching deformation in the form of wrinkles has been extensively investigated. In this work, (AA) extend this fundamental scientific question to the plastic regime by exploring the adaptations of crystalline sheets to the large uniaxial mechanical stretching. >>

AA << reveal the intermittent plastic shear deformations leading to the complete fracture of the sheets wrapping the cylinder. Specifically, systematic investigations of crystalline sheets of varying geometry show that the fracture processes can be classified into defect-free and defective categories depending on the emergence of topological defects. >>

AA << highlight the characteristic mechanical and geometric patterns in response to the large stretching deformation, including the shear-driven intermittent lattice tilting, the vortex structure in the displacement field, and the emergence of mobile and anchored dislocations as plastic excitations. >>

<< The effects of noise and initial lattice orientation on the plastic deformation of the stretched crystalline sheet are also discussed. These results advance our understanding of the atomic level on the irreversible plastic instabilities of two-dimensional crystals under large uniaxial stretching and may have potential practical implications in the precise engineering of structural instabilities in packings of covalently bonded particulate systems. >>

Ranzhi Sun, Zhenwei Yao. Defect-free and defective adaptations of crystalline sheets to stretching deformation. Phys. Rev. E 111, 055504. May 21, 2025.

Also: elastic, intermittency, noise, instability, vortex, defect, fracture, crack, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, elastic, noise, intermittency, instability, vortex, defect, fracture, crack, stretch, deformation, wrinkles, tilting, plastic instabilities,  plastic excitations.

martedì 27 maggio 2025

# gst: dynamic expulsion of magnetic flux by vortices.

AA << study numerically the dynamical evolution of two different vorticity arrays with an initially uniform magnetic field in two-dimensional incompressible magnetohydrodynamics. (They)  concentrate particularly on the role of the strength of the background magnetic field, which is always assumed weak in the sense that its energy is much less than the kinetic energy of the vortical flows. >>

<< Within the context of a weak background field, (AA) are able to identify four distinct regimes. When the field is so weak that the back-reaction of the Lorentz force can be ignored (the kinematic regime), classical flux expulsion occurs. As the field strength is increased, the first signs of the dynamical influence of the small-scale field generated is in the disruption of vortex filaments, with flux expulsion still occurring in the vortex cores. A further increase in field strength leads to the regime of vortex disruption, in which the magnetic field is expelled, but is then of sufficient strength to disrupt or destroy the vortices. For yet stronger fields, even the large-scale field can be sufficiently strong to be dynamically active; flux expulsion is then prevented, and the field is dynamically active throughout the evolution. >>

<< Furthermore, in the case of a row of vortices, (AA) show that the orientation of the background field significantly influences the evolution, especially at higher field strengths. >>

Jonathan Tessier, Francis J. Poulin, David W. Hughes. Dynamic expulsion of magnetic flux by vortices. Phys. Rev. Fluids 10, 053702. May 19, 2025.

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

Keywords: gst, vortex, transitions, flux expulsion, vortex disruption.

lunedì 26 maggio 2025

# gst: apropos of attractive-- repulsive potentials in free boundary movements, stochastic and deterministic dynamics of free boundaries atop turbulent convection

AA << present a low-dimensional model that explains the coupled dynamics of floating boundaries that interact with turbulent flows in thermal convection. >>

<< The model consists of Langevin-type, stochastic differential equations, which captures the deterministic and stochastic movements of boundaries shown in an earlier experiment J.-Q. Zhong et al. [Phys. Rev. E 75, 055301(R) (2007)]. From the displacement, speed, and acceleration of the boundaries, (They) construct the force potentials that underlie two distinct boundary-size-dependent behaviors. >>

<< Namely, (AA) find a repulsive potential (when the boundary is small) that leads to an oscillatory state and an attractive potential (when the boundary is large) that leads to a trapped state. >>

<< The boundary movements, which are subject to thermal convection underneath, also inform us of the mean speed and turbulent fluctuations of the flows. >>

Wen-Tao Wu, Jun Zhang, Jin-Qiang Zhong. Stochastic and deterministic dynamics of free boundaries atop turbulent convection. Phys. Rev. Fluids 10, 053504. May 9, 2025.

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

Keywords: gst, convection, floating 
boundaries, turbulence, turbulent flows, turbulent fluctuations, disorder & fluctuations, trapped states

sabato 24 maggio 2025

# gst: apropos of absorbing targets, persistence exponents of self-interacting random walks


<< The persistence exponent, which characterizes the long-time decay of the survival probability of stochastic processes in the presence of an absorbing target, plays a key role in quantifying the dynamics of fluctuating systems. Determining this exponent for non-Markovian processes is known to be a difficult task, and exact results remain scarce despite sustained efforts. >> 

In their Letter, AA << consider the fundamental class of self-interacting random walks (SIRWs), which display long-range memory effects that result from the interaction of the random walker at time 𝑡 with the territory already visited at earlier times 𝑡′ <𝑡. (AA)  compute exactly the persistence exponent for all physically relevant SIRWs. As a byproduct, (They) also determine the splitting probability of these processes. >>

<< Besides their intrinsic theoretical interest, these results provide a quantitative characterization of the exploration process of SIRWs, which are involved in fields as diverse as foraging theory, cell biology, and nonreversible Monte Carlo methods. >>

J. Brémont, L. Régnier, et al. Persistence Exponents of Self-Interacting Random Walks. Phys. Rev. Lett. 134, 197103. May 16, 2025.

arXiv:2410.18699v1 [cond-mat.stat-mech]. 

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

Keywords: gst, walk, walking, self-interacting random walk, walker self-repulsion, walker self-attraction, stochasticity, absorbing targets.

venerdì 23 maggio 2025

# gst: toy model of turbulent shear flow using vortons.

AA << introduce a toy model for shear flows, exploiting the spatial intermittency and the scale separation between large-scale flows and small-scale structures. The model is highly sparse, focusing exclusively on the most intense structures, which are represented by vortons—dynamically regularized quasisingularities that experience rapid distortion from the large-scale shear. The vortons, in turn, influence the large-scale flow through the subgrid stress tensor. >>

<< Despite its simplicity, the model displays an interesting transition between two distinct regimes: (i) a laminar regime, where dissipation is entirely attributed to the large-scale flow and the vortons dynamics is essentially diffusive, and (ii) a turbulent regime, in which most of the dissipation arises from the vortons. These regimes correspond to different scalings of dissipation and the Grashof number as functions of the Reynolds number, with power-law relationships that resemble those observed in classical turbulence. >>

Wandrille Ruffenach, Lucas Fery, Bérengère Dubrulle. Toy model of turbulent shear flow using vortons. Phys. Rev. Fluids 10, 054601. May 1, 2025.

arXiv:2501.05779v2 [physics.flu-dyn]. 

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

Keywords: gst, turbulence, intermittency, transitions, vortons

giovedì 22 maggio 2025

# life: to protect freedoms, not just funding.

<< At Harvard University in Cambridge, Massachusetts, and Columbia University in New York City, cuts to previously granted federal research funds have been accompanied by demands from the government. If enacted, the changes to departmental oversight, disciplinary procedures, campus police and governance structures would allow the government to dictate hiring, student admissions and disciplinary decisions. >>

<< So far, the US science community has been outspoken about the threats that funding cuts pose to health, innovation and the economy. Yet, few researchers have decried the devastation wreaked on science by attacks on civil liberties and the rule of law. >>

Andrew M. Leifer, Andrea J. Liu, Sidney R. Nagel. US researchers must stand up to protect freedoms, not just funding. Nature 641, 592-593. May 13, 2025.

Also: people who turn career into a game playing ... FonT. May 31, 2017.

Also: minimal risk, in FonT 

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

Alsodance, game, transition, sars* covid* (aka 1or2achoos), forms of power, Mr. Donald, are you ready, in https://www.inkgmr.net/kwrds.html 

Also: nefst (e.g. not embedded, freestyle thinker) 

Keywords: life, acad, game, dance, transitions, nefst, 1or2achoos, minimal risk, turn career, forms of power, Mr. Donald, are you ready.

mercoledì 21 maggio 2025

# gst: accelerated first detection in discrete-time quantum walks using sharp restarts.

<< Restart is a common strategy observed in nature that accelerates first-passage processes, and has been extensively studied using classical random walks. In the quantum regime, restart in continuous-time quantum walks (CTQWs) has been shown to expedite the quantum hitting times [Phys. Rev. Lett. 130, 050802 (2023)]. >>

 Here, AA << study how restarting monitored discrete-time quantum walks (DTQWs) affects the quantum hitting times. (They) show that the restarted DTQWs outperform classical random walks in target searches, benefiting from quantum ballistic propagation, a feature shared with their continuous-time counterparts. >>

Kunal Shukla, Riddhi Chatterjee, C. M. Chandrashekar. Accelerated first detection in discrete-time quantum walks using sharp restarts. Phys. Rev. Research 7, 023069. Apr 21, 2025.

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

Keywords: gst, networks, randomness, walk, random walk, quantum walk, stochasticity, sharp restart.

martedì 20 maggio 2025

# gst: biased random walks on networks with stochastic resetting.

<< This study explores biased random walk dynamics with stochastic resetting on general networks. (AA) show that the combination of biased random walks and stochastic resetting makes significant contributions by analyzing the search efficiency. (They) derive two analytical expressions for the stationary distribution and the mean first passage time, which are related to the spectral representation of the probability transition matrix of a biased random walk without resetting. These expressions can be used to determine the capacity of a random walker to reach the specific target and probe a finite network. >>

AA << apply the analytical results to two types of networks, pseudofractal scale-free webs and T-fractals, which are constructed through an iterative process. (They) also extend a strategy to explore other complex structure networks or larger networks by leveraging the spectral properties. >>

Anlin Li, Xiaohan Sun. Biased random walks on networks with stochastic resetting. Phys. Rev. E 111, 054309. May 16, 2025.

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

Keywords: gst, networks, randomness, random walk, stochasticity, stochastic resetting.