# gst: triadic instabilities of internal wave standing modes.

<< ️This (AA) article presents (their) experimental study of the nonlinear destabilization of an internal wave standing mode in a uniformly stratified fluid within a rectangular domain. (They) measure the linear response of the system and target its resonances to generate a high-amplitude standing mode, prone to instabilities. Using modal decomposition tools, (They) determine the characteristics of the secondary waves and show that they have a standing-mode spatial structure. Box resonance conditions associated with nonlinear resonance conditions lead to a significant deviation from the internal wave dispersion relation and complex nonlinear interaction dynamics. >>

<< Following previous work, (AA) develop a weakly nonlinear analysis to understand the secondary wave characteristics. This approach, validated by experimental results, shows that the secondary wave characteristics as well as the general nonlinear dynamics are highly sensitive to the domain geometry and to the forcing mode. >>

Julie Deleuze, Ilias Sibgatullin, Philippe Odier, Sylvain Joubaud. Triadic instabilities of internal wave standing modes. Phys. Rev. Fluids 10, 124803. Dec 8, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/2pvv-wkc4

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

Keywords: gst, waves, instability.

# gst: bursting bubbles in Herschel-Bulkley fluids, dynamics and jetting transitions.

<< ️When a bubble rises to a free surface, its bursting dynamics in Newtonian fluids are governed by the interplay between viscous, capillary, and gravitational forces. In this work, (AA) extend this classical problem to Herschel-Bulkley fluids, elucidating the role of viscoplasticity and non-Newtonian rheology in bubble bursting. Using direct numerical simulations validated against experiments, (They) systematically explore the influence of the key governing dimensionless parameters, such as the Bond number, the Ohnesorge number, the shear-dependent behavior and the plastocapillary number, each varied over several orders of magnitude. >>

<< ️(AA) results reveal that viscoplasticity strongly controls the evolution and interaction of capillary waves within the cavity formed upon bubble rupture. Shear-thinning and shear-thickening effects are significant only for moderate Ohnesorge numbers, while at large Ohnesorge values the free surface dynamics converge to a non-flat equilibrium shape once the internal stresses fall below the yield stress. >>

<< ️These (AA) findings provide new insights into the coupled effects of viscosity, gravity, yield stress, and shear-dependent rheology in multiphase flows, with broad implications for natural and industrial processes involving gas-liquid interfaces. >>

A. H. Ghaemi, Z. Yang, A. Huang, et al. Bursting bubbles in Herschel-Bulkley fluids: dynamics and jetting transitions. arXiv: 2511.23345v1 [physics.flu-dyn]. Nov 28, 2025.

https://arxiv.org/abs/2511.23345

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

Keywords: gst, bubble, waves, capillary waves, bubble bursting, bubble rupture, viscosity, capillary and gravitational forces, shear-thinning and shear-thickening effects, yield stress, free surface dynamics, non-flat equilibrium.

# gst: instability triggered by mixed convection in a thin fluid layer.

<< ️(AA) investigate the convective stability of a thin, infinite fluid layer with a rectangular cross-section, subject to imposed heat fluxes at the top and bottom and fixed temperature along the vertical sides. The instability threshold depends on the Prandtl number as well as the normalized flux difference (f) and decreases with the aspect ratio (ϵ), following a ϵf^−1 power law. >>

<< ️Using 3D initial value and 2D eigenvalue calculations, (They) identify a dominant 3D mode characterized by two transverse standing waves attached to the domain edges. (They) characterize the dominant mode’s frequency and transverse wave number as functions of the Rayleigh number and aspect ratio. An analytical asymptotic solution for the base state in the bulk is obtained, valid over most of the domain and increasingly accurate for lower aspect ratios. >>

<< A local stability analysis, based on the analytical base state, reveals oscillatory transverse instabilities consistent with the global instability characteristics. The source term for this most unstable mode appears to be interactions between vertical shear and horizontal temperature gradients. >>

Florian Rein, Keaton J. Burns, Stefan G. Llewellyn Smith, et al. Instability triggered by mixed convection in a thin fluid layer. arXiv: 2512.02331v1 [physics.flu-dyn]. Dec 2, 2025.

https://arxiv.org/abs/2512.02331

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

Keywords: gst, waves, instability, transitions, convection, vertical shear, horizontal temperature gradients.

# gst: two instabilities in one liquid sheet.

<< ️Two cylindrical liquid jets (dia = 1 mm) of a glycerol-water mixture (80/20) impinge at 90º to one another, creating a thin liquid sheet bordered by a thick rim. Classical fish-bone shapes (sheet-thread-droplet) are formed where the rim instability is driven by Rayleigh-Plateau type mechanisms. >>

<< ️Here (AA) also see fish-bone shapes occurring for similar reasons. However, the waves on the sheet are formed by small imbalances between the two jet velocities (natural pipe driven oscillation), rather than the traditional Kelvin-Helmholtz instability. (They) stroboscopic photograph of the sheet reveals that both of these instabilities can coexist within a narrow range of operating conditions. >>

<< ️The breakup of the liquid sheet (lower down) is caused by the combined instability of spatially growing waves. The liquid sheet breaks down mainly through the growth of bounded waves. These waves eventually break, forming long threads at the bottom of the sheet, which further disintegrate into droplets due to the Rayleigh-Plateau instability of threads. >>

Sandip Dighe, Hrishikesh Gadgil, Tadd Truscott. Two instabilities in one liquid sheet. Phys. Rev. Fluids 10, 110501. Nov 20, 2025

https://journals.aps.org/prfluids/abstract/10.1103/nvkn-hk4g

77th Annual Meeting of the APS Division of Fluid Dynamics (Nov 24 — 26, 2024). P2692828: Two instabilities in one liquid. 

https://gfm.aps.org/meetings/dfd-2024/673f8914d88f37002bbe76d8

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

Keywords: gst, waves, instability, transitions.

# gst: degrees of universality in wave turbulence

<< ️Turbulence of weakly interacting waves displays a great deal of universality: independence of the details of the interaction and of the pumping and dissipation scales. Here (AA) study how inverse turbulent cascades (from small to large scales) transition from weak to strong. (They) find that while one-loop corrections can be dependent on excitation and dissipation scales, new types of universality appear in strong turbulence. (They) contrast turbulence of spin waves in ferromagnets with turbulent cascades in the Nonlinear Schrödinger Equation (NSE) and in an MMT-like (Majda-McLaughlin-Tabak) model in higher dimensions having a multiplicative interaction vertex: vertex renormalization gives rise to dependence on the pumping (UV scale) in the former but not in the latter. >>

<< ️As a result of this spectral nonlocality, spin-wave turbulence stops being weak if one is sufficiently far from the pumping scale, even when the interaction of waves with comparable wavenumbers is weak. (AA) paraphrase this as: nonlocality enhances nonlinearity. >>

<< ️(AA) then describe strong turbulence in a multi-component version of these models with a large number of components. (They) argue that strong spin-wave turbulence is similar to turbulence of the focusing NSE, as it realizes a critical-balance state. However, UV nonlocality causes the level of spin-wave turbulence at large scales to decrease with increasing pumping level, culminating in a state that is independent of the level of pumping. >>

Jiasheng Liu, Vladimir Rosenhaus, Gregory Falkovich. Degrees of universality in wave turbulence. arXiv: 2512.04866v1 [cond-mat.stat-mech]. Dec 4, 2025.

https://arxiv.org/abs/2512.04866

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

Keywords: gst, waves, turbulence, transitions.

# gst: spontaneous emergence of solitary waves in active flow networks.

<< ️Flow networks are fundamental for understanding systems such as animal and plant vasculature or power distribution grids. These networks can encode, transmit, and transform information embodied in the spatial and temporal distribution of their flows. >>

<< ️In this work, (AA) focus on a minimal yet physically grounded system that allows (Them) to isolate the fundamental mechanisms by which active flow networks generate and regulate emergent dynamics capable of supporting information transmission. The system is composed of active units that pump fluid and elastic units that store volume. From first principles, (They) derive a discrete model-an active flow network-that enables the simulation of large systems with many interacting units. >>

<< ️Numerically, (AA) show that the pressure field can develop solitary waves, resulting in the spontaneous creation and transmission of localized packets of information stored in the physical properties of the flow. (They) characterize how these solitary waves emerge from disordered initial conditions in a one-dimensional network, and how their size and propagation speed depend on key system parameters. >>

<< ️Finally, when the elastic units are coupled to their neighbors, the solitary waves exhibit even richer dynamics, with diverse shapes and finite lifetimes that display power-law behaviors that (They) can predict analytically. >>

Rodrigo Fernández-Quevedo García, Gonçalo Cruz Antunes, Jens Harting, et al. Spontaneous emergence of solitary waves in active flow networks. arXiv: 2511.13448v1 [physics.flu-dyn]. Nov 17, 2025.

https://arxiv.org/abs/2511.13448

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

Keywords: gst, solitons, waves, solitary waves, networks, active flow networks, active matter, fluid-structure interactions, elasticity.

# gst: energy transport and chaos in a one-dimensional disordered nonlinear stub lattice

<< ️(AA) investigate energy propagation in a one-dimensional stub lattice in the presence of both disorder and nonlinearity. In the periodic case, the stub lattice hosts two dispersive bands separated by a flat band; however, (They) show that sufficiently strong disorder fills all intermediate band gaps. By mapping the two-dimensional parameter space of disorder and nonlinearity, (AA) identify three distinct dynamical regimes (weak chaos, strong chaos, and self-trapping) through numerical simulations of initially localized wave packets. >>

<< ️When disorder is strong enough to close the frequency gaps, the results closely resemble those obtained in the one-dimensional disordered discrete nonlinear Schrödinger equation and Klein-Gordon lattice model. In particular, subdiffusive spreading is observed in both the weak and strong chaos regimes, with the second moment m_2 of the norm distribution scaling as m_2 ∝ t^0.33 and m_2 ∝ t^0.5, respectively. The system’s chaotic behavior follows a similar trend, with the finite-time maximum Lyapunov exponent Λ decaying as Λ ∝ t^−0.25 and Λ ∝ t^−0.3. For moderate disorder strengths, i.e., near the point of gap closing, (They) find that the presence of small frequency gaps does not exert any noticeable influence on the spreading behavior. >>

<< ️(AA) findings extend the characterization of nonlinear disordered lattices in both weak and strong chaos regimes to other network geometries, such as the stub lattice, which serves as a representative flat-band system. >>

Su Ho Cheong, Arnold Ngapasare, et al. Energy transport and chaos in a one-dimensional disordered nonlinear stub lattice. arXiv: 2511.04159v1 [nlin.CD].  Nov 6, 2025.

https://arxiv.org/abs/2511.04159

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

Keywords: gst, networks, waves, disorder, chaos, stub lattice, subdiffusive spreading.

# gst: coupling an elastic string to an active bath: the emergence of inverse damping.

<< ️The interaction between continuous media and particles is a central topic in much of modern physics, and this (AA) paper specifically addresses the transfer of persistence and activity between particles and waves. Indeed, setting up a nonequilibrium dynamics of continuous (field) degrees of freedom requires understanding how that arises from coupling with active matter degrees of freedom. >>

<< ️Within that program, (AA) have studied a system of fast-moving, overdamped, run-and-tumble particles moving on and interacting with a slower string modeled as a scalar Klein-Gordon field. Using time scale separation and weak coupling, (They) have derived an effective fluctuation dynamics for the field after integrating out the active bath. Akin to Landau (inverse) damping, the particles induce friction on the scalar field given by an explicit time correlation for bath observables. >>

<< ️Depending on the level of activity and persistence of the active particles (and their velocity distribution), this friction can be negative, leading to instability. This emergence of negative (linear) friction for an elastic string extends previous results where the probe is a slow inertial particle in an active medium, (..), except that the acceleration (creating transverse waves) is orthogonal to the active motion. >>

Aaron Beyen, Christian Maes, Ji-Hui Pei. Coupling an elastic string to an active bath: The emergence of inverse damping. arXiv: 2505.18665v2 [cond-mat.stat-mech]. Sep 1, 2025.

https://arxiv.org/abs/2505.18665

Phys. Rev. E 112, L042103. Oct 17, 2025.

https://journals.aps.org/pre/abstract/10.1103/g1zm-23sq

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

Keywords: gst, particles, run-and-tumble particles, waves, elasticity, elastic strings, wave-particle interactions.

# gst: apropos of waves that escape trapping; on internal wave whispering gallery modes in channels and critical-slope wave attractors.

<< ️Internal waves are an important feature of stratified fluids, both in oceanic and lake basins and in other settings. Many works have been published on the generic feature of internal wave trapping onto planar wave attractors and super-attractors in 2D & 3D and the exceptional class of standing global internal wave modes. >>

<< ️However, most of these works did not deal with waves that escape trapping. By using continuous symmetries (AA) analytically prove the existence of internal wave Whispering Gallery Modes (WGMs), internal waves that propagate continuously without getting trapped by attractors. WGMs neutral stability with respect to different perturbations enable whispering gallery beams, a continuum of rays propagating together coherently. The systems' continuous symmetries also enable projection onto 2D planes that yield effective 2D billiards preserving the original dynamics. >>

<< ️By examining rays deviating from these WGMs in parabolic channels (They) discover a new type of wave attractor which is located along the channel instead of across it as in previous works. This new wave attractor leads to a re-understanding of WGMs as sitting at the border between the two basins of attraction. >>

<< ️Finally, both critical-slope wave attractors and whispering gallery beams are used to propose explanations for along-channel energy fluxes in submarine canyons and tidal energy intensification near critical slopes. >>

Nimrod Bratspiess, Eyal Heifetz, Leo R. M. Maas. On internal wave whispering gallery modes in channels and critical-slope wave attractors. arXiv: 2510.07218v1 [physics.flu-dyn]. Oct 8, 2025.

https://arxiv.org/abs/2510.07218

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

Keywords: gst, waves, internal waves, internal wave whispering gallery modes (WGMs), wave attractors, basins of attraction, billiards.

# gst: spiral defect chaos with intermittency increases mean termination time

<< ️Cardiac models are examples of excitable systems and can support stable spiral waves. For certain parameter values, however, these spiral waves can become unstable, resulting in spiral defect chaos (SDC), characterized by the continuous creation and annihilation of spiral waves and thought to underlie atrial fibrillation. During SDC, the number of spiral waves fluctuates and drops to zero at termination. >>

<< ️In this work, (AA) demonstrate that varying a single parameter allows the system to transition from SDC to a single spiral wave, passing through an intermediate regime of intermittency. In such intermittent dynamics, intervals of SDC are sandwiched between non-SDC intervals during which the number of spiral waves remains small and constant. (They) quantify this intermittency and show that the mean termination time increases significantly as the control parameter approaches values for which a single spiral wave is stable. >>

<<  In addition, (AA) observe that quasistable spiral waves may intermittently persist in part of the computational domain, while the rest of the domain exhibits SDC. >> 

Mahesh Kumar Mulimani, Wouter-Jan Rappel. Spiral defect chaos with intermittency increases mean termination time. Phys. Rev. E 112, 034203. Sep 3, 2025.

https://journals.aps.org/pre/abstract/10.1103/bwpl-qqyl

arXiv: 2505.06427v1 [nlin.CD]. May 9,  2025

https://arxiv.org/abs/2505.06427

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

Keywords: gst, waves, spiral & scroll waves, intermittency, vortex, chaos, spiral defect chaos.

# gst: shock waves in classical dust collapse.

<< ️During gravitational collapse of dust in spherical symmetry, matter particles may collide forming shell crossing singularities (SCSs) at which the Einstein equations become indeterminate. >>

<< ️(AA) show that in the case of marginally bound dust collapse, there is a unique evolution beyond SCSs such that a propagating shock wave forms, the metric remains continuous, and the stress-energy tensor dynamically becomes that of a thin shell. (They) give numerical simulations that exhibit this result. >>

Viqar Husain, Hassan Mehmood. Shock waves in classical dust collapse. Phys. Rev. Research 7, 033215. Sep 3, 2025.

https://journals.aps.org/prresearch/abstract/10.1103/b317-86qs

arXiv: 2504.14883v1 [gr-qc]. Apr 21, 2025.

https://arxiv.org/abs/2504.14883

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

Keywords: gst, particles, singularity, shell crossing singularities, waves, shock waves, gravitational waves, collapse, dust collapse, gravitational collapse. 

# gst: falling viscoelastic liquid films on a slippery substrate.

<< This (AA) study develops a weighted-residual model for Oldroyd-B films on slippery substrates at moderate Reynolds number and large slippery length. >>

<< Linear stability analysis reveals that wall slip promotes perturbation growth rates, increases cut-off wave numbers, and accelerates long-wave propagation speed, demonstrating a destabilizing effect. Two distinct families of traveling waves are sought, which demonstrate that varying the slippery length can alter the bifurcation type of traveling wave families. >>

<< Particularly, large slippery length can cause the transition of drag-gravity regime into the drag-inertia regime. In the drag-gravity regime, slippery effect promotes the wave speed and height. However, in the drag-inertia regime, slippery effect can suppress the wave height even though the wave propagates faster. >>

<< Interestingly, plateau-type waves (They)  found in the Oldroyd-B film flow at large slippery length, which has not been reported previously. >>

Zhiwei Song, Zijing Ding. Falling viscoelastic liquid films on a slippery substrate. Phys. Rev. E 112, 025106. Aug 25, 2025. 

https://journals.aps.org/pre/abstract/10.1103/vv3p-cvk2

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

Keywords: gst, slipping, slippery substrates, waves, instability, instability of free-surface flows, transitions.

# gst: hidden qu-classical correspondence in chaotic billiards revealed by mutual information.

<< ️Avoided level crossings, commonly associated with quantum chaos, are typically interpreted as signatures of eigenstate hybridization and spatial delocalization, often viewed as ergodic spreading. >>

<< ️(AA) show that, contrary to this expectation, increasing chaos in quantum billiards enhances mutual information between conjugate phase space variables, revealing nontrivial correlations. Using an information-theoretic decomposition of eigenstate entropy, (They) demonstrate that spatial delocalization may coincide with increased mutual information between position and momentum. >>

<< These correlations track classical invariant structures in phase space and persist beyond the semiclassical regime, suggesting a robust information-theoretic manifestation of quantum-classical correspondence. >>

Kyu-Won Park, Soojoon Lee, Kabgyun Jeong. Hidden quantum-classical correspondence in chaotic billiards revealed by mutual information. Phys. Rev. E 112, 024209. Aug 13, 2025.

https://journals.aps.org/pre/abstract/10.1103/qpxx-csdj

arXiv:2505.08205v1 [nlin.CD]. May 13, 2025.

https://arxiv.org/abs/2505.08205

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

Keywords: gst, billiard, chaos, qu-chaos, waves, quantum-to-classical transition

# gst: nonreciprocal coupling triggers pinning-depinning transitions of wavefronts in bistable systems chains.

<< ️Coupled discrete systems with reciprocal and nonreciprocal couplings exhibit unexpected and counterintuitive phenomena compared to continuous systems. (AA) investigate the pinning-depinning transition induced by nonreciprocal coupling in nonlinear wave propagation connecting different equilibria in bistable system chains. >>

Experimentally, their system << ️exhibits the propagation of fronts between homogeneous states. The fronts display a pinning-depinning transition by increasing the nonreciprocal coupling, achieved by increasing optical feedback offset. Close to the bifurcation, the front velocity is characterized by a square root law as a function of the bifurcation parameter. >>

L. B. Ramirez-Moya, M. Diaz-Zuniga, et al. Nonreciprocal coupling triggers pinning-depinning transitions of wavefronts in bistable systems chains. Phys. Rev. Research 7, L032023. Aug 1, 2025.

https://journals.aps.org/prresearch/abstract/10.1103/9ypt-4kvs

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

Keywords: gst, waves, transitions, pinning-depinning transitions

# 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.

https://journals.aps.org/prl/abstract/10.1103/b82h-z21n

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

https://arxiv.org/abs/2407.11469

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.

# 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

https://journals.aps.org/pre/abstract/10.1103/cmf5-sf8x#d93038b1-6671-419d-be1e-219e5bf78523

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

# 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.

# life: the pervasive "soft power" of ancient India.

<< One of the big contentions of popular historian William Dalrymple’s latest book “The Golden Road: How Ancient India Transformed the World,” which came out in the United States a few weeks ago, is that the Indian subcontinent’s connections to the West, especially via the Roman Empire, were far richer than those of China (i.e. the “Silk Road” cited). Once the might of Rome reached Egypt and the maritime routes of the Red Sea, it brought the customers of the Mediterranean to India’s doorstep. It also saw Indian philosophy and mathematics travel west and east. >>

<< Once their economic links to the West thinned with the collapse of the Roman Empire, South Indian merchant guilds turned east, embarking on trade and contacts that spread Indian religion and ideas across a wide expanse of Asia and underlay the grandeur of centuries-old temple complexes like Angkor Wat in Cambodia or Borubudur in Indonesia. >>

<< it’s one of the great soft power miracles of world history, because unlike Islam and unlike quite a lot of Christianity, no one took Buddhism at the point of a sword. No one imposed Buddhism at any point. It was the sophistication of its ideas and particularly its attractiveness to the merchant classes, bizarrely. The Buddhist monasteries act as banks, as factories and as caravanserais. >>

Ishaan Tharoor with Rachel Pannett. How ancient India changed the world. WorldView (by mail). washingtonpost.com. May 19, 2025.

https://s2.washingtonpost.com/camp-rw/?trackId=660de34bb906a33aae6b8103&s=682aadf6f062960b82a2f3e6

Also:  forms of power, waves, attractor, Zen, compassion, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: life, forms of power, soft power, waves, attractors, Zen, compassion, transition.

# gst: transitions of breakup regimes for viscous droplets in airflow.

In this AA study, << the transitions of breakup regimes for viscous droplets are investigated experimentally using high-speed imaging taken from a side view and a 45 view. Based on the morphology change in the middle of the droplet, the breakup regimes are classified into no-breakup, bag breakup, bag-stamen, low-order multimode, high-order multimode, and shear-stripping breakup. The droplet morphologies in different regimes and the corresponding transitions are discussed in detail. >>

<< The droplet viscosity dissipates the kinetic energy transferred by the airflow during the initial droplet flattening, and affects the development of the Rayleigh-Taylor instability wave after the flattening. Through the analysis of the droplet deformation and the Rayleigh-Taylor instability with the droplet viscosity taken into account, the transition conditions of different regimes are obtained in a regime map. By further considering the relative velocity loss between the droplet and the airflow, the ranges of the dual-bag breakup in the low-order multimode regime and the droplet retraction in the bag-stamen regime are determined. >>

Zhikun Xu, Tianyou Wang, Zhizhao Che. Transitions of breakup regimes for viscous droplets in airflow. arXiv: 2504.14149v1 [physics.flu-dyn]. Apr 19, 2025.

https://arxiv.org/abs/2504.14149

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

Keywords: gst, drops, droplets, droploids, viscous droplets, droplet breakup, transitions, instability, waves

# gst: period-doubling route to chaos in viscoelastic flows

<< Polymer solutions can develop chaotic flows, even at low inertia. This purely elastic turbulence is well studied, but little is known about the transition to chaos. In two-dimensional (2D) channel flow and parallel shear flow, traveling wave solutions involving coherent structures are present for sufficiently large fluid elasticity. >>

AA << numerically study 2D periodic parallel shear flow in viscoelastic fluids, and (They) show that these traveling waves become oscillatory and undergo a series of period-doubling bifurcations en-route to chaos. >>

Jeffrey Nichols, Robert D. Guy, Becca Thomases. Period-doubling route to chaos in viscoelastic Kolmogorov flow. Phys. Rev. Fluids 10, L041301. Apr 17, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.L041301

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

Keywords: gst, chaos, waves, traveling waves, elasticity, viscoelastic fluids, turbulence, elastic turbulence, period-doubling bifurcations, transitions