# gst: correlated noise and critical dimensions.

<< In equilibrium, the Mermin-Wagner theorem prohibits the continuous symmetry breaking for all dimensions d≤2. In this work, (AA) discuss that this limitation can be circumvented in nonequilibrium systems driven by the spatiotemporally long-range anticorrelated noise. >>

<< results suggest that the critical dimensions increase when the noise is positively correlated in space and time and decrease when anticorrelated. (AA)  also report that the spherical model with the correlated noise shows the hyperuniformity and giant number fluctuation even well above the critical point. >>️

Harukuni Ikeda. Correlated noise and critical dimensions. Phys. Rev. E 108, 064119. Dec 13, 2023.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.064119 

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

Keywords: gst, noise, fluctuations

# gst: pulsating active matter.

<< the mechanical pulsation of locally synchronized particles is a generic route to propagate deformation waves. >>

️

AA << consider a model of dense repulsive particles whose activity drives periodic change in size of each individual. >>️

They << show that the competition between repulsion and synchronization triggers an instability which promotes a wealth of dynamical patterns, ranging from spiral waves to defect turbulence. >>️

Yiwei Zhang, Etienne Fodor. Pulsating Active Matter. Phys. Rev. Lett. 131, 238302. Dec 8, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.238302

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

Keywords: gst, waves, particle, transition, instability, turbulence

# gst: scanning inside a granular raft

<< Rheology of macroscopic particle-laden interfaces, called “granular rafts,” has been experimentally studied in the simple shear configuration.  >>️

<< Close to the walls of the rheometer cell, one can observe regions of large local shear rate while in the middle of the cell a quasistatic zone exists. >>

<< Measuring the probability density functions of the instantaneous local shear rate, (AA) provide evidence of a balance between positive and negative instantaneous local shear rate. This behavior is the signature of a quasistatic region inside the granular raft. >>️

️

J. Lalieu, A. Seguin, G. Gauthier. Rheology of granular rafts. Phys. Rev. E 107, 064901. June 29, 2023.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.107.064901

Also: Bavand Keshavarz, Michela Geri. Mandelbrot granular raft. Phys. Rev. Fluids 8, 110506. Nov 16, 2023.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.110506

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

Also: << l'invasiva scorribanda /

sull' oramai alla deriva lacerata randa. >>️ in: Schismi da vibrati di tangone. Notes. March 23, 2005. (quasi-stochastic poetry)

https://inkpi.blogspot.com/2005/03/1608b-schismi-da-vibrati-di-tangone.html

Keywords: gst, raft, particle, grain, granular raft, life

# gst: buckling instability of sticky bubbles.

<< A slender object undergoing an axial compression will buckle to alleviate the stress. Typically the morphology of the deformed object depends on the bending stiffness for solids, or the viscoelastic properties for liquid threads. >>️

AA << study a chain of uniform sticky air bubbles in an aqueous bath that rise due to buoyancy. A buckling instability of the bubble chain, with a characteristic wavelength, is observed in the absence of a bending stiffness. If a chain of bubbles is produced faster than it is able to rise, the dominance of viscous drag over buoyancy results in a compressive stress that is alleviated by buckling the bubble chain. >>

️

Carmen L. Lee, Kari Dalnoki-Veress. Buckling instability in a chain of sticky bubbles. arXiv: 2311.15452v1 [cond-mat.soft]. Nov 26, 2023.

https://arxiv.org/abs/2311.15452

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

Keywords: gst, bubble, instability, buckling instability

# gst: when a turbulence can be confined

<< Turbulence is hard to control. Its ephemeral nature prevents us from treating it as an ordinary state of matter. Here (AA) create a stationary and isolated blob of turbulence using only elemental building blocks: vortex rings.  The turbulence is confined in a spherical region, surrounded by a quiescent environment, initiated and sustained by vortex rings. Crucially, vortex rings can be endowed with conserved quantities such as energy and helicity, which can be transferred to the turbulent state. Using 2D particle image velocimetry and 3D particle tracking velocimetry, (AA) demonstrate how confinement of turbulence occurs when vortex rings repeatedly collide, in contrast to coherent vortex reconnections. The pathlines depict the difference between these states of flow. >>️

Takumi Matsuzawa, Noah P. Mitchell, Stéphane Perrard, William T. M. Irvine. Turbulence through sustained vortex ring collisions. Phys. Rev. Fluids 8, 110507. Nov 16, 2023.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.110507

75TH ANNUAL MEETING OF THE APS DIVISION OF FLUID DYNAMICS (NOVEMBER 20, 2022 — NOV 22, 2022). V0008: Turbulence through sustained vortex ring collisions. 

https://doi.org/10.1103/APS.DFD.2022.GFM.V0008

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

Keywords: gst, turbulence, vortex, vortex ring collisions

# gst: kirigami exposed to external flows.

<< Kirigami patterned materials have found several applications in recent years due to their ability to assume complicated shapes and exhibit emergent physical properties when exposed to external forces. >>️

<< Consisting of an array of cuts in a thin material, fabrication of these patterns can be quite simple. Here (AA) show that when they are placed in fluid flow, kirigami cut sheets with various patterns produce a verity of flow patterns in the wake. Through several sets of experiments, (AA) show that the kirigami sheets placed in flow can undergo static or dynamic flow-induced instabilities as a result of which they can buckle or undergo limit cycle oscillations, or they can remain stable while undergoing very large elongations. >>️

<< The ability to create controlled small-scale vortex shedding, induce desired flow-induced instabilities on structures, and form specifically-angled jets will enable several future applications in flow mixing (e.g., by producing small vortices in uniform flow at low Reynolds numbers), flow control (e.g., by controlling the direction and the number of jets that are produced downstream), and underwater soft robotics (e.g., by imposing desired flow-induced oscillations on structures). >>

️

Adrian G. Carleton, Yahya Modarres-Sadeghi. Kirigami Sheets in Fluid Flow.  arXiv: 2311.09381v1 [physics.flu-dyn]. Nov 15, 2023. 

https://arxiv.org/abs/2311.09381

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

Keywords: gst, kirigami, origami, fluid flows, vortex

# gst: collective patterns generated by capillary surfers.

<< Millimeter-sized “surfers” can self-propel across a vibrating liquid surface, interacting with other surfers to create collective patterns. >>

<< Self-propelled objects can move in mesmerizing patterns. The collective movements of groups of such objects typically occur in one of two flow regimes: the inertial regime—think swirling schools of fish in water—or the viscous regime—think swarming colonies of bacteria in mucus. Some self-propelled objects can travel in both flow regimes, a possibility that is less explored. >>️

AA << have studied the motion of a new system of self-propelled objects that move in this intermediate regime, finding that the objects organize into several distinct and tunable motion patterns. >>️️

<< Pairs of self-propelled surfers observed by the team move in one of seven different patterns (the video shows five). These include the “orbit,” where a pair of surfers rotate around a central point; the “tailgate,” where one surfer closely follows another, head to tail in a linear path; and the “jackknife,” where a pair of perpendicular surfers rotate stern to stern around their collision point. >>

<< When only one surfer was present, these mismatched amplitudes propelled the surfer in the direction of its bow. When there were two surfers close to each other, interactions among the waves caused the surfers to either repel each other so that they moved in opposite directions or to come together so that they collectively traced one of seven distinct patterns. >>️

️

Maggie Hudson. Synchronized Surfing of Self-Propelled Particles. Physics 16, s156. Nov 7, 2023. 

https://physics.aps.org/articles/v16/s156

Ian Ho, Giuseppe Pucci, Anand U. Oza, Daniel M. Harris. Capillary surfers: Wave-driven particles at a vibrating fluid interface. Phys. Rev. Fluids 8, L112001. Nov 7, 2023.

https://link.aps.org/doi/10.1103/PhysRevFluids.8.L112001

Anand U. Oza, Giuseppe Pucci, Ian Ho, Daniel M. Harris. Theoretical modeling of capillary surfer interactions on a vibrating fluid bath. Phys. Rev. Fluids 8, 114001. Nov 7, 2023.

https://link.aps.org/doi/10.1103/PhysRevFluids.8.114001

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

Keywords: gst, waves, wave-wave, capillary waves, particles, self-propelled particles, fluid-particle interactions, wave-particle interactions

gst: actually and counterintuitively a coherent jump could generate disorder.

AA << consider a quantized version of a model for “random walk in random environment.” (..) For a ring geometry (a chain with periodic boundary condition) it features a delocalization-transition as the bias in increased beyond a critical value, indicating that the relaxation becomes underdamped. Counterintuitively, the effective disorder is enhanced due to coherent hopping. >>

Ben Avnit, Doron Cohen. Quantum walk in stochastic environment. Phys. Rev. E 108, 054111. Nov 7, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.054111

Also:  Voli a casaccio. Notes (quasi-stochastic poetry). Oct 01, 2006.

https://inkpi.blogspot.com/2006/10/2066-voli-casaccio.html

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

Keywords: gst, walk, random walk, quantum walk, qu-walk, jump, transition, disorder, chaos

# gst: how to create a helix from a straight rod, “twist” or “bend” approaches.

<< There are two independent ways of creating a helix from a straight rod: curl the rod into a circle and then twist the rod all along its length to convert the ring into a helix (“twist” method), or deform the rod into a sine wave and then bend it with a sinusoidal distortion that curls at right angles to the first sine wave (“bend” method). Both procedures produce the same shape, but they generate different internal stresses within the rod, and their implementations require different amounts of energy. >>️

AA << say that their experiments could serve as a model for many physical systems that undergo handedness transitions, including the tendrils of plants, the flagella of microorganisms, and the strands of DNA molecules.  >>

️

David Ehrenstein. Two Experimental Observations of Helix Reversals. Physics 16, s158. Oct 24, 2023.  

https://link.aps.org/doi/10.1103/Physics.16.s158

Paul M. Ryan, Joshua W. Shaevitz,  Charles W. Wolgemuth. Bend or Twist? What Plectonemes Reveal about the Mysterious Motility of Spiroplasma. Phys. Rev. Lett. 131, 178401. Oct 24, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.178401

Emilien Dilly, Sebastien Neukirch, Julien Derr, Drazen Zanchi. Traveling Perversion as Constant Torque Actuator. Phys. Rev. Lett. 131, 177201. Oct 24, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.177201

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

Keywords: gst, elastic, elastic deformation, swimming

# gst: local elastic properties of strongly disordered matter

<< The local elastic properties of strongly disordered material are investigated using the theory of correlated random matrices. A significant increase in stiffness is shown in the interfacial region, the thickness of which depends on the strength of disorder. It is shown that this effect plays a crucial role in nanocomposites, in which interfacial regions are formed around each nanoparticle. >>️

D. A. Conyuh, A. A. Semenov, Y. M. Beltukov. Effective elastic moduli of composites with a strongly disordered host material. Phys. Rev. E 108, 045004. Oct 20, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.045004

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

Keywords: gst, elastic, noise, particle, nano

# gst: emergence of chimeras driven by non-normality

<< The emergence of order in nature manifests in different phenomena, with synchronization being one of the most representative examples. >>️

<< Particular attention has been paid to the emergence of chimera states, where subsets of synchronized oscillations coexist with asynchronous ones. Such coexistence of coherence and incoherence is a perfect example where order and disorder can persist in a long-lasting regime. >>

<< Based on a symmetry-breaking mechanism, in this paper, (AA) shed light on the role that non-normality, a ubiquitous structural property of real networks, has in the emergence of several diverse dynamical phenomena, e.g., amplitude chimeras or oscillon patterns. >>️

<< Specifically, (they) demonstrate that the prevalence of source or leader nodes in networks leads to the manifestation of phase chimera states. >>️

Riccardo Muolo, Joseph D. O'Brien, et al. Persistence of chimera states and the challenge for synchronization in real-world networks. arXiv: 2306.00237v1 [nlin.PS]. May 31, 2023.

https://arxiv.org/abs/2306.00237

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

Keywords: gst, chimera, network, synchronization, swarm, noise, order, disorder, normal

# gst: anisotropic active depletion around a self-propelled non-interactive colloids; three characteristic states could be identified.

<< Active colloids in a bath of inert particles of smaller size cause anisotropic depletion. >>️

Here AA << combine mesoscale hydrodynamic simulation as well as theoretical analysis to examine the physical origin for the active depletion around a self-propelled noninteractive colloid. >>️

Their << results elucidate that the variable hydrodynamic effect critically governs the microstructure of the depletion zone. Three characteristic states of anisotropic depletion are identified, depending on the strength and stress of activity. >>️

<< Furthermore, (AA) demonstrate that such depletion in nonequilibrium results in various clusters with ordered organization of squirmers, which follows a distinct principle contrary to that of the entropy scenario of depletion in equilibrium. >>

️

Lijun Dai, Haixiao Wan, et al. Hydrodynamic Anisotropy of Depletion in Nonequilibrium. Phys. Rev. Lett. 131, 134002. Sep 27, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.134002

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

Keywords: gst, particles, colloids, depletion, squirmers, self-propulsion systems

# gst: wandering domains: a hypothetical scenario with bounded orbits.

<< A significant open question in transcendental dynamics asks if it is possible for a point, and thus all points, of a wandering domain to have a bounded orbit. >>

<< In other words, is there a transcendental entire function f with a wandering domain U such that its forward orbit, U_n≥0 f^n(U), is bounded? >>

AA << give a partial answer to this question by constructing an example of a such a wandering domain U which has a nearly bounded orbit; >>

<< In other words, the set of natural numbers n for which f^n(U) is contained in D has upper (and lower) natural density one. >>

<< This is in particularly strong contrast to all existing examples of wandering domains, for which the quantity (..) is equal to zero for any choice of bounded domain D. >>

Leticia Pardo-Simon, David J. Sixsmith. Wandering domains with nearly bounded orbits. arXiv: 2307.16682v1 [math.DS]. Jul 31, 2023. 

https://arxiv.org/abs/2307.16682

Also: Unbounded fast escaping wandering domains. https://arxiv.org/abs/2210.13350 ; Escaping sets of continuous functions. https://arxiv.org/abs/1601.04010 

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

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

Keywords: gst, wandering domain, escape 

# gst: reconfiguration and oscillations of sheets subject to vortex

<< The dynamics of a thin low-density polyethylene sheet subject to periodic forcing due to Bénard-Kàrmàn vortices in a long narrow water channel is investigated here. In particular, the time-averaged sheet deflection and its oscillation amplitude are considered. >>

<< The former is first illustrated to be well-approximated by the static equilibrium between the buoyancy force, the elastic restoring force, and the profile drag based on the depth-averaged water speed. >>

AA << observations also indicate that the presence of upstream vortices hinder the overall reconfiguration effect, well-known in an otherwise steady flow. For the sheet-tip oscillations, a simple model based on a torsional-spring-mounted flat plate correctly captures the measured tip amplitude δb over a wide range of sheet physical properties and flow conditions. >>

<< Furthermore, a rich phenomenology of structural dynamics including vortex-forced-vibration, lock-in with the sheet natural frequency, and flow-induced vibration due to the sheet wake, multiple-frequency, and modal response is reported. >>

️

J. John Soundar Jerome, Yohann Bachelier, et al. Reconfiguration and oscillations of a vertical, cantilevered sheet subject to vortex shedding behind a cylinder. Phys. Rev. Fluids 8, 093801. Sep 15, 2023. 

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.093801

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

Keywords: gst, sheet, vortex, Benard-Karman vortices

# gst: apropos of transitions, three distinct new families of long-wave instabilities and potential new pathways to turbulence.

AA << reveal three previously unknown instabilities, distinct from the well-known Kelvin-Helmholtz Instability (KHI) and Holmboe Wave Instability (HWI), in that they have longer wavelengths (..) and often slower growth rates. >>

<< The circumstances under which turbulence can persist in strongly stratified flows remains a fascinating debate within the community. [AA] demonstrated that weakly unstable (very) long waves may trigger turbulence and mixing after long periods of time, even under initially very strongly stratified conditions. >>

Lu Zhu, Amir Atoufi, Adrien Lefauve, Rich R. Kerswell, P. F. Linden. Long-wave instabilities of sloping stratified exchange flows. arXiv:2309.10056v1 [physics.flu-dyn]. Sep 18, 2023.

https://doi.org/10.48550/arXiv.2309.10056

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

Keywords: gst, waves, instability, long-wave instability, transition, turbulence, chaos

# gst: apropos of collisions of a vortex dipoles, vortex unbinding, vortex pinning to the edge, and emission of rarefaction pulses.

<< Vortices and dark solitons are fundamental defects that appear in nonlinear physics at all scales, from nonlinear optics to cosmic fluids. In two or three dimensions, dark solitons are fundamentally connected to highly ordered vortex states through an intrinsic modulation instability in the surrounding matter. >>️

<< Here, [AA] report an experimental realization of ring dark soliton (RDS)  generation in a two-dimensional atomic superfluid trapped in a circular box. By quenching the confining box potential, [they] observe an RDS emitted from the edge and its peculiar signature in the radial motion. As an RDS evolves, [they] observe transverse modulations at discrete azimuthal angles, which clearly result in a patterned formation of a circular vortex dipole array. Through collisions of the vortex dipoles with the box trap, [they] observe vortex unbinding, vortex pinning to the edge, and emission of rarefaction pulses. >>

Hikaru Tamura, Cheng-An Chen, Chen-Lung Hung. Observation of Self-Patterned Defect Formation in Atomic Superfluids–from Ring Dark Solitons to Vortex Dipole Necklaces. Phys. Rev. X 13, 031029. Sep 14, 2023. 

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.13.031029

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

Keywords: gst, soliton, dark soliton, vortex, turbulence, waves. 

# gst: chimera resonance, in analogy with the effects of stochastic and coherence resonance

AA << explore numerically the impact of additive Gaussian noise on the spatio-temporal dynamics of ring networks of nonlocally coupled chaotic maps. >>

️

<<  It is shown that the coupling strength range can be the widest at a certain optimum noise level at which chimera states are observed with a high probability for a large number of different realizations of randomly distributed initial conditions and noise sources. >>

<< This phenomenon demonstrates a constructive role of noise in analogy with the effects of stochastic and coherence resonance and may be referred to as chimera resonance. >>️

Elena Rybalova, Vasilii Nechaev, Eckehard Schöll, Galina Strelkova. Chimera resonance in networks of chaotic maps. arXiv:2307.00006v2 [cond-mat.dis-nn]. Jul 5, 2023.

https://arxiv.org/abs/2307.00006

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

Keywords: gst, chimera, noise, chaos, network, chimera resonance

# gst: neural networks know their knots.

<< The use of neural networks in physics is booming. Recently, the tool has helped researchers uncover everything from new magnetic materials (..) to ways to reduce noise in electron beams produced at synchrotrons (..) Seeking their own neural network success, (AA) wondered if the tool could classify knots, a computationally challenging problem. >>

They << applied two different neural networks to the problem—a recurrent neural network (RNN) and a feed-forward neural network (FFNN). >>

<< The RNN achieved 99% accuracy >>

 

Katherine Wright. Neural Networks Know Their Knots. Physics 13, s19. Feb 11, 2020.

https://physics.aps.org/articles/v13/s19.

img  https://physics.aps.org/assets/b3a39285-5bde-4137-8a54-5f9d9b9e2738/es19_1.png

Olafs Vandans, Kaiyuan Yang, et al. Identifying knot types of polymer conformations by machine learning. Phys. Rev. E 101, 022502. Feb 11, 2020.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.101.022502

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

Keywords: gst, network, neural network, knots

# gst: emergence of self-organizing zigzag patterns among (magnetic) particles suspended in a liquid

<< When molecules or bacteria organize into a long-range pattern, researchers want to understand how the microscopic interactions lead to the macroscopic order. (AA) observed such self-organization in magnetic particles suspended in a liquid and subjected to an oscillating magnetic field. Through experiments and simulations, the team showed that the resulting zigzag pattern is explained by the fluid flow generated around the oscillating particles, not by any details of the particles or the applied field. Similar zigzag patterns have also been seen in charged colloids subjected to oscillating electric fields, so the explanation may cover a range of particle systems. The researchers also believe that understanding and controlling the effect could lead to useful applications in microfluidics devices. >>️

David Ehrenstein. Self-Organized Zigzags from Fluid Flow. Physics 16, 138. Aug 11, 2023.

https://physics.aps.org/articles/v16/138

Gaspard Junot, Marco De Corato, Pietro Tierno. Large Scale Zigzag Pattern Emerging from Circulating Active Shakers. Phys. Rev. Lett. 131, 068301. Aug 11, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.068301

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

Keywords: gst, behavior, particle, self-assembly, self-organization, chiral, active shakers, squirmers, alternating chirality

# gst: rich behaviors from stochastic walking with variable long jumps.

AA << propose a generalized model where the random walker takes stochastic jumps of lengths proportional to its present position with certain probability, otherwise it makes forward and backward jumps of fixed (unit) length with given rates. The model exhibits a rich stochastic dynamic behavior.  (AA) obtain exact analytic results for the first two moments of the walker's displacement and show that a phase transition from a diffusive to superdiffusive regime occurs if the stochastic jumps of lengths that are twice (or more) of its present positions are allowed. This phase transition is accompanied by a reentrant diffusive behavior. >> 

Upendra Harbola. Stochastic walker with variable long jumps. Phys. Rev. E 108, 014135. July 28, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.014135 

Also: walk, noise, fluctuations, dance,  in: https://www.inkgmr.net/kwrds.html

Keywords: gst, walks, random walks, noise, fluctuations