# gst life: apropos of critical points, love (at first sight and love from liking or friendship) might be a second-order phase transition.

<< The hypothesis of the human brain operation in vicinity of a critical point has been a matter of a hot debate in the recent years. >>

<< In this work, (AA) suggest that love might be an example of a second-order phase transition occurring in the brain. (They) show that this hypothesis explains a lot of well-known properties of love. Analyzing several most famous literature examples and a private diary, (they) show that the intensity of feelings exhibits a universal scaling behavior, distinguishing two cases: love at first sight and love developing from liking or friendship (friends first), both being studied in psychology. >>

The theory of second-order phase transitions developed by L.D. Landau (1980) << has inspired a lot of activity in physics, because it turned out that such transitions are characterized by a universal scaling behavior. Independently of the nature of the system, their parameters exhibit power law dependencies on the dimensionless parameter (temperature). >>

<< The key hypothesis of the present work is that love is a second-order phase transition occurring in the human brain under the influence of hormones, such as dopamine and serotonin (..). The brain switches from the normal operation in the critical regime to the supercritical regime because of the increase of the excitation (more dopamine) and reduction of the inhibition (less serotonin) (..). The order parameter of the transition is the intensity of feelings: before the transition, the subject has no particular feelings, while after the transition the feelings are non-zero. The most direct consequence is that the order parameter should exhibit a universal power law behavior: the feelings should grow as a square root of time α ∼√ >>

<< Since it is impossible to analyze the human feelings directly during such uncontrollable phenomenon as ”love at first sight”, (AA) have decided to perform a quantitative study of the intensity of feelings depicted in the literature. (..) (They) have chosen three well-known books for this analysis: ”Romeo and Juliet” (W. Shakespeare), ”The Lily of the Valley” (H. de Balzac, (..)), and ”Martin Eden” (J. London). >>

<< the case of a non-zero external ”bias”, which is a situation that occurs more often than love at first sight. Indeed, one usually knows several persons better than all the others, and thus some positive feelings towards some of them can be present before the transition occurs. (..) To study this transition quantitatively, (AA) have chosen another well-known book, ”Jane Eyre” by Charlotte Bronte. This books is also quite autobiographic, and famous for the psychological details, that got its author the title of ”first historian of the private consciousness”. The delay between the initial acquaintance and love is now of several weeks (about 45 days).

Dmitry Solnyshkov, Guillaume Malpuech. Love might be a second-order phase transition. arXiv: 2203.13246v1 [cond-mat.stat-mech]. Mar 24, 2022. 

https://arxiv.org/abs/2203.13246

Also

keyword 'transition' in FonT: 

https://flashontrack.blogspot.com/search?q=transition

keyword 'transizione' | 'transition' in Notes (quasi-stochastic poetry): 

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https://inkpi.blogspot.com/search?q=transition

keywords: gst, life, love, transitions,  critical point, phasetransition, second-order phase transition, brain, mind, behavior.

# gst: liquid–liquid phase transition, the two forms of liquid water (mixed with the natural antifreeze trehalose)

<< Liquids are structurally disordered, so it’s not immediately obvious how they can support two distinct structures with different densities. But that does seem to be possible for liquids in which some degree of directional bonding, such as hydrogen bonds between adjacent water molecules, makes distinct local structures possible. Liquid–liquid transitions have been reported, for example, in silicon, gallium, phosphorus and silicates. But finding one in supercooled water has proved very challenging. There have been previous claimed observations of a liquid–liquid transition in aqueous solutions at ambient pressure, (..) where the solute, such as the sugar glycerol, sometimes used as a cryoprotectant, lowers the freezing point. But such claims have been disputed.(..) Other researchers have reported liquid-like behaviour as the two well-established high- and low-density forms of amorphous (glass-like) ice interconvert. (..) >>

<< In 2014 Yoshiharu Suzuki (..) working with veteran water researcher Osamu Mishima, reported possible signs of a liquid–liquid transition, ending in a critical point where the two liquid states become indistinguishable, in emulsified, supercooled solutions of glycerol. (..) They saw signs of two distinct disordered states with different densities at a temperature of 150K. But there was no direct evidence that both were liquids, rather than amorphous ice. >>

<< Suzuki has now explored the same approach using trehalose as the solute – a sugar produced as a natural cryoprotectant by some organisms, such as insects, that experience extreme cold, to prevent their blood from freezing. He pressurised dilute emulsified solutions to about 0.6GPa at a range of temperatures below 159K, and then decompressed them again.  >>

<< Such hysteresis – whereby the density jumps at different pressures on compression and decompression – is normal for a first-order transition where a parameter such as density changes discontinuously. It reflects the fact that the transition has to start with the chance formation of a ‘nucleus’ of the new phase, which then grows. >>

<< Suzuki is not yet sure why trehalose stabilises water so well against crystallisation, compared with glycerol – but this might help explain why life uses it as an antifreeze. >>

Philip Ball. Direct evidence emerges for the existence of two forms of liquid water. Feb 1, 2022.

https://www.chemistryworld.com/news/direct-evidence-emerges-for-the-existence-of-two-forms-of-liquid-water/4015144.article  

Also

keyword 'water' in FonT

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keyword 'transition' | 'transitional' in FonT

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keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

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keywords: gst, transition, liquid-liquid transition, water

# gst: discontinuous transitions to active nematic turbulence.

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

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

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

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

https://arxiv.org/abs/2501.06085

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

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

# gst: apropos of transitions, perspectives on viscoelastic flow instabilities; the 'porous individualism'

<< given the observation that disorder can suppress the transition to elastic turbulence in 2D porous media (..), it has been unclear whether and how this transition manifests in disordered 3D media — though elastic turbulence has been speculated to underlie the long-standing observation that the macroscopic flow resistance of an injected polymer solution can abruptly increase above a threshold flow rate in a porous medium, but not in bulk solution >>️

AA << found that the transition to unstable flow in each pore is continuous, arising due to the increased persistence of discrete bursts of instability above a critical value of the characteristic (Weissenberg no.) Wi; however, the onset value varies from pore to pore. This observation that single pores exposed to the same macroscopic flow rate become unstable in different ways provides a fascinating pore-scale analog of “molecular individualism” [P.  De Gennes, Molecular individualism. Science 276, 1999–2000 (1997)], in which single polymers exposed to the same extensional flow elongate in different ways; the authors therefore termed it “porous individualism”, although it is important to note that here, this effect is still at the continuum (not molecular) scale. Thus, unstable flow is spatially heterogeneous across the different pores of the medium, with unstable and laminar regions coexisting >>

AA << quantitatively established that the energy dissipated by unstable pore-scale fluctuations generates an anomalous increase in flow resistance through the entire medium that agrees well with macroscopic pressure drop measurements. >>

Sujit S. Datta, Arezoo M. Ardekani, et al. Perspectives on viscoelastic flow instabilities and elastic turbulence. arXiv: 2108.09841v1 [physics.flu-dyn]. Aug 22, 2021. 

https://arxiv.org/abs/2108.09841

Also

keyword 'transition' | 'transitional' in FonT

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https://flashontrack.blogspot.com/search?q=transitional

keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

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keywords: gst, droplet, fluctuations, disorder, instability, viscoelastic flow instability, turbulence, elastic turbulence, individualism, porous individualism, transition

# gst: apropos of transitions, scrambling trajectories in a radiative random unitary circuit.

AA << study quantum information scrambling in a random unitary circuit that exchanges qubits with an environment (..). As a result, initially localized quantum information  not only spreads within the system, but also spills into the environment. >>

<< The transition is also easily extended to higher dimensions, where higher-dimensional DP (directed percolation) universality classes will control the critical behavior. >>

<<  The transition in operator spreading  coincides with an information-theoretic 3 transition, which can be framed by  viewing (AA) circuit as a toy model for an evaporating black hole (..). >>️

<< Depending on the initial state of the swapped-in qubits, (AA) observe a corresponding entanglement transition in the coherent information into the environment. >>

️

Zack Weinstein, Shane P. Kelly, Jamir Marino, Ehud Altman. Scrambling Transition in a Radiative Random Unitary Circuit. arXiv:2210.14242v1 [quant-ph]. Oct 25, 2022.

https://arxiv.org/abs/2210.14242

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

Keywords: transition, quantum information, entanglement transition, scrambling, directed percolation

# gst: the hypothesis of a first order phase transition (a type of abrupt phase transition) to originate black holes observed by LIGO/Virgo in binary mergers.

<<  To summarize, motivated by the ~10 M* (mass similar to that of the sun) black holes observed by LIGO/Virgo in binary mergers, (AA) entertained the possibility that the quark-gluon confinement phase transition was first order due to the effect of 6 light quarks. The larger number of light quarks, compared to the standard case, pushes the transition temperature below ∼100 MeV. The first order nature of the transition significantly improves the likelihood of forming primordial black holes and its lower temperature suggests that these black holes can potentially be as heavy as ∼10 M*, compared to ∼M* for the standard QCD transition. >>

Hooman Davoudiasl.  LIGO/Virgo Black Holes from a First Order Quark Confinement Phase Transition. Phys. Rev. Lett. 123, 101102. Sep 6, 2019.   https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.101102  

Ingrid Fadelli. Theory proposes that LIGO/Virgo black holes originate from a first order phase transition. Sep 23, 2019.    https://m.phys.org/news/2019-09-theory-ligovirgo-black-holes-phase.html  

QCD = quantum chromodynamic  
https://en.m.wikipedia.org/wiki/Standard_Model

# gst: breakthrough in unstable growth processes, shorter branches can revive when a striking transition of the leading branch reaches the boundary of the system.

<< Transport networks, such as vasculature or river networks, provide key functions in organisms and the environment. They often emerge as a result of unstable growth processes, in which growing branches compete for the available flux. This leads to effective repulsion between the branches and screening of the shorter ones. (AA) show that a striking transition in growth dynamics takes place as the leading branch reaches the boundary of the system. The shorter branches revive then and grow toward the leading one forming loops. These effects are observed both in living and inanimate systems. >>

Stanisław Zukowski, Annemiek Johanna Maria Cornelissen, et al. Finger revival and reconnections near breakthrough in unstable growth processes. arXiv: 2212.08878v1 [physics.flu-dyn]. Dec 17, 2022.

https://arxiv.org/abs/2212.08878

Also

keyword 'transition' in FonT: 

https://flashontrack.blogspot.com/search?q=transition

keyword 'transizione' | 'transition' in Notes (quasi-stochastic poetry): 

https://inkpi.blogspot.com/search?q=transizione

https://inkpi.blogspot.com/search?q=transition

Keywords: gst, transition, growth, growth dynamics, transport networks, spatial networks

# gst: apropos of transitions, rich behaviors from chimeras or solitary states to traveling waves

AA << study numerically the spatiotemporal dynamics of a ring network of nonlocally coupled nonlinear oscillators, each represented by a two-dimensional discrete-time model of the classical van der Pol oscillator. >>

<< It is shown that the discretized oscillator exhibits a richer behavior, combining the peculiarities of both the original system and its own dynamics. Moreover, a large variety of spatiotemporal structures is observed in the network of discrete van der Pol oscillators when the discretization parameter and the coupling strength are varied. Such regimes as the coexistence of multichimera state/traveling wave and solitary state are revealed for the first time and studied in detail. >>

<< It is established that the majority of the observed chimera/solitary states, including the newly found ones, are transient towards the purely traveling wave mode. The peculiarities of the transition process and the lifetime (transient duration) of the chimera structures and the solitary state are analyzed depending on the system parameters, observation time, initial conditions, and influence of external noise. >>

Elena Rybalova, Sishu Muni, Galina Strelkova. Transition from chimera/solitary states to traveling waves. arXiv: 2212.07990v1 [nlin.AO]. Dec 15, 2022. 

https://arxiv.org/abs/2212.07990

Also

keyword 'transition' | 'transitional' in FonT

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https://flashontrack.blogspot.com/search?q=transitional

keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

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keyword 'waves' in FonT

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keyword 'onda' in Notes (quasi-stochastic poetry)

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Keywords: gst, behavior, van der Pol oscillator, transition, chimera state, solitons, solitary state, waves, noise

# gst: simultaneous presence of attraction and repulsion in quantum self-sustained oscillators

AA << study the emergent dynamics of quantum self-sustained oscillators induced by the simultaneous presence of attraction and repulsion in the coupling path. >>

They << discover an interesting symmetry-breaking transition from quantum limit cycle oscillation to a quantum inhomogeneous steady state. This transition is contrary to the previously known symmetry-breaking transition from a quantum homogeneous state to an inhomogeneous steady state. >>

<< Remarkably, (they) find the generation of entanglement associated with the symmetry-breaking transition that has no analog in the classical domain. >>

Bulti Paul, Biswabibek Bandyopadhyay, Tanmoy Banerjee. Attractive-repulsive interaction in coupled quantum oscillators. Phys. Rev. E 110, 034210. Sept 19, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.110.034210

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

Keywords: gst, transition, symmetry-breaking transition, noise, attractive-repulsive interaction, coupled qu-oscillator

# gst: apropos of a immaginary transition (with a tipping point), which simulates the chaotic interactions of three black holes.

<< The interactions between three bodies such as stars or planets or black holes cannot be predicted with an elegant formula. Moerman (Arend Moerman) therefore used a computer that calculates what happens for a short period of time and then uses the result for the next period of time. >>

AA << varied the masses of the three interacting black holes. They started with one solar mass and went up to a billion times the mass of the sun. >>

<< Around ten million solar masses, there appeared to be a tipping point. In the simulations, black holes that are lighter than about ten million solar masses mostly eject each other through a gravitational slingshot. Black holes heavier than about ten million solar masses start to merge. First, two black holes merge. The third black hole will follow later. The black holes merge because they lose kinetic energy and that is because they emit gravitational waves. >>

<< Arend's work (..) has led to a new understanding of how black holes become supermassive. In the simulations, we see that heavy black holes no longer endlessly move around each other, but that, if they are heavy enough, they collide pretty much instantly. >> Simon Portegies Zwart. 

Simulating chaotic interactions of three black holes. Netherlands Research School for Astronomy. Oct 20, 2021. 

https://phys.org/news/2021-10-simulating-chaotic-interactions-black-holes.html

Tjarda C. N. Boekholt, Arend Moerman, Simon F. Portegies Zwart. Relativistic Pythagorean three-body problem. Phys. Rev. D 104, 083020. 14 Oct 14,  2021. 

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.104.083020

Also

more on the three-body problem (695 families of collisionless orbits). FonT. Oct 16, 2017. 

https://flashontrack.blogspot.com/2017/10/gst-more-on-three-body-problem-695.html

keyword 'black hole' | 'astro' in FonT

https://flashontrack.blogspot.com/search?q=black+hole

https://flashontrack.blogspot.com/search?q=astro

keyword 'transition' | 'transitional' in FonT

https://flashontrack.blogspot.com/search?q=transition

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keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

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keywords: gst, black hole, three-body problem, transition, chaos, chaotic interaction, tipping point.

# gst: apropos of the transition of order from chaos, a universal behavior near a critical point.

<< As the Reynolds number is increased, a laminar fluid flow becomes turbulent, and the range of time and length scales associated with the flow increases. Yet, in a turbulent reactive flow system, as we increase the Reynolds number, (AA) observe the emergence of a single dominant timescale in the acoustic pressure fluctuations, as indicated by its loss of multifractality. >>️

AA << study the evolution of short-time correlated dynamics between the acoustic field and the flame in the spatiotemporal domain of the system.   >>️

<< the susceptibility of the order parameter, correlation length, and correlation time diverge at a critical point between chaos and order. (AA) results show that the observed emergence of order from chaos is a continuous phase transition (..) the critical exponents characterizing this transition fall in the universality class of directed percolation. >>️

The << paper demonstrates how a real-world complex, nonequilibrium turbulent reactive flow system exhibits universal behavior near a critical point. >>️

Sivakumar Sudarsanan, Amitesh Roy, et al. Emergence of order from chaos through a continuous phase transition in a turbulent reactive flow system. Phys. Rev. E 109, 064214. Jun 20, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.064214

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

Keywords: gst, order, chaos, transition 

# gst: apropos of transitions to turbulence, pulsatility delays the transition to sustained turbulence in quasi-2D shear flows

<< Two-dimensional disturbances require high Reynolds numbers to incite transition from a steady base flow, as transient growth is modest. With the addition of an oscillatory base flow component, (AA) work shows that the transient growth experienced by two-dimensional initial perturbations is often well above that provided by the steady component. >>

<< However, as has been shown for three-dimensional flows [B. Pier and P. J. Schmid, J. Fluid Mech. 926, A11 (2021)], the transient growth is almost entirely composed of modal intracyclic growth, rather than a transient mechanism which takes advantage of non-normality. This lack of transient growth, relative to the severe decay induced by the favorable pressure gradient during the acceleration phase of the oscillatory base flow, only ever delays the transition to sustained turbulence. >>

<< Thus, a nonoscillatory driving force remains the most efficient strategy for sustained turbulence in quasi-two-dimensional shear flows. The only benefit provided by pulsatility is that the amplitude of the initial condition required to trigger intermittent turbulence is orders of magnitude smaller. >>️

Christopher J. Camobreco, Alban Pothérat, Gregory J. Sheard. Pulsatility delays the transition to sustained turbulence in quasi-two-dimensional shear flows. Phys. Rev. Fluids 10, 023905. Feb 25, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.023905

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

Keywords: gst, pause, transition, turbulence, vortex

# gst: towards (insights into) intermittency and inhomogeneity of turbulent mixing

<< Fluid elements deform in turbulence by stretching and folding. In this work, by projecting the material deformation tensor onto the largest stretching direction, the dynamics of folding is depicted through the evolution of the material curvature. Results from direct numerical simulation (DNS) show that the curvature growth exhibits two regimes, first a linear stage dominated by folding fluid elements through a persistent velocity Hessian which then transitions to an exponential growth driven by the stretching of already strongly bent fluid elements. This transition leads to strong curvature intermittency at later stages, which can be explained by a proposed curvature-evolution model. The link between velocity Hessian to folding provides a new way to understand the crucial steps in energy cascade and mixing in turbulence beyond the classical linear description. >>

Yinghe Qi, Charles Meneveau, Greg Voth, Rui Ni. Folding dynamics and its intermittency in turbulence. arXiv: 2301.10341v1 [physics.flu-dyn]. Jan 24, 2023. 

https://arxiv.org/abs/2301.10341

Also

keyword 'intermittency' in FonT

https://flashontrack.blogspot.com/search?q=intermittency

keyword 'turbulence' in FonT

https://flashontrack.blogspot.com/search?q=turbulence

keyword 'turbolento' | 'turbolenza' in Notes (quasi-stochastic poetry)

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https://inkpi.blogspot.com/search?q=turbolenza

keyword 'transition' | 'transitional' in FonT

https://flashontrack.blogspot.com/search?q=transition

https://flashontrack.blogspot.com/search?q=transitional

keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=transition

https://inkpi.blogspot.com/search?q=transizione

https://inkpi.blogspot.com/search?q=transizioni

Keywords: gst, intermittency, turbulence, transition

# gst: apropos of prolate- oblate spheroid transition, the chaotic behavior of a spinless entity around a black hole.

AA << investigate the long-term orbital dynamics of spinless extended bodies in Schwarzschild geometry, and show that periodic deviations from spherical symmetry in the shape of a test body may trigger the onset of chaos. (AA) do this by applying Dixon's formalism at quadrupolar order to a nearly spherical body whose shape oscillates between a prolate and an oblate spheroid. The late-time chaotic behavior is then verified by applying Melnikov's method. >>️

Ricardo A. Mosna, Fernanda F. Rodrigues, Ronaldo S. S. Vieira. Chaotic dynamics of a spinless axisymmetric extended body around a Schwarzschild black hole. arXiv: 2207.04341v1 [gr-qc]. Jul 9, 2022. 

https://arxiv.org/abs/2207.04341

Phys. Rev. D 106, 024016 (2022). 

https://doi.org/10.1103/PhysRevD.106.024016

Also - Oblate and Prolate Spheroid.  

<< The shape of the earth is that of a round ball or sphere slightly flattened at two opposite sides. Such a body is termed a spheroid. There are two kinds of spheroids-oblate and prolate; the former as the shape of an orange, the latter that of a lemon.  >>️

Oblate and Prolate Spheroid.  

https://etc.usf.edu/clipart/30500/30587/spheroid_30587.htm

img    https://etc.usf.edu/clipart/30500/30587/spheroid_30587_sm.gif

Also

keyword 'transition' in FonT: 

https://flashontrack.blogspot.com/search?q=transition

keyword 'transizione' | 'transition' in Notes (quasi-stochastic poetry): 

https://inkpi.blogspot.com/search?q=transizione

https://inkpi.blogspot.com/search?q=transition

Keywords: gst, spheroid, behavior, chaos, transition, black hole

# gst: the complex dynamics of a transition

<< The transition state is a central concept of chemistry (..) Everything we think about in reactions really hinges on the structure of the transition state, which we cannot directly observe. >> Robert Field.

<< there are two different mechanisms competing for transition states, >>

<< there are additional reaction mechanisms beyond those two, >>

Chemists glimpse the fleeting 'transition state' of a reaction. 

Massachusetts Institute of Technology. Dec 16, 2019.

https://m.phys.org/news/2019-12-chemists-glimpse-fleeting-transition-state.html

# gst: discontinuous transition to chaos in a canonical random neural network

AA << study a paradigmatic random recurrent neural network introduced by Sompolinsky, Crisanti, and Sommers (SCS). In the infinite size limit, this system exhibits a direct transition from a homogeneous rest state to chaotic behavior, with the Lyapunov exponent gradually increasing from zero. (AA)  generalize the SCS model considering odd saturating nonlinear transfer functions, beyond the usual choice 𝜙⁡(𝑥)=tanh⁡𝑥. A discontinuous transition to chaos occurs whenever the slope of 𝜙 at 0 is a local minimum [i.e., for 𝜙′′′⁢(0)>0]. Chaos appears out of the blue, by an attractor-repeller fold. Accordingly, the Lyapunov exponent stays away from zero at the birth of chaos. >>

In the figure 7 << the pink square is located at the doubly degenerate point (𝑔,𝜀)=(1,1/3). >>️️

Diego Pazó. Discontinuous transition to chaos in a canonical random neural network. Phys. Rev. E 110, 014201. July 1, 2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.110.014201

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

Keywords: gst, chaos, random, network, transition, neuro

# gst: helical instabilities from mixed mode transitions in boundary layers

<< Recent (..) direct numerical simulations (DNS) of adverse- and zero-pressure-gradient boundary layers beneath moderate levels of free stream turbulence (𝑇⁢𝑢≤2%) revealed a mixed mode transition regime, intermediate between orderly and bypass routes. >>️

<< In this regime, the amplitudes of the Klebanoff streaks and instability waves are similar, and both can contribute significantly as these interact. Three-dimensional visualizations of transitional eddies revealed a helical pattern, quite distinct from the sinuous and varicose forms seen in pure bypass transition. This raises the fundamental question of whether the helical pattern could be attributed to a previously unknown instability mode. >>️

In AA work << based on stability analyses, (they) show that it is indeed the case. Two-dimensional stability analyses are performed herein for base flows extracted from DNS flow fields. >>️

Rikhi Bose, Paul A. Durbin. Mixed mode transition in boundary layers: Helical instability. Phys. Rev. Fluids 9, 063905. Jun 12, 2024. 

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.063905

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

Keywords: gst, instability, transition, turbulence, waves

# gst: apropos of transitions, the vortex dynamics from a twisted baker map

<< A natural approach to understanding complicated systems is to analyze a col­lection of simple examples that retain some essential features of the complexity of the original systems. The baker map (..) is one of the simplest models of chaotic dynamical systems. It divides the unit square into p ≥ 2 equal vertical strips, and maps each strip to a horizontal one by squeezing it vertically by the factor p and stretching it horizontally by the same factor. The horizontal strips are laid out covering the square. Due to the squeezing/stretching, small initial errors get amplified under iteration, and results in an unpredictable long-term behavior. The name “baker” is used since the action of the map is reminiscent of the kneading dough (..). In this paper (AA) introduce a piecewise linear model of an interaction of stretching and twisting that produces vortex dynamics. >>

They << show that the set of hyperbolic repelling periodic points with complex conjugate eigenvalues and that without complex conjugate eigenvalues are simultaneously dense in the phase space >>

Yoshitaka Saiki, Hiroki Takahasi, James A. Yorke. The twisted baker map. arXiv: 2202.04304v2 [math.DS]. Feb 9, 2022. 

https://arxiv.org/abs/2202.04304

Also

keyword 'transition' | 'transitional' in FonT

https://flashontrack.blogspot.com/search?q=transition

https://flashontrack.blogspot.com/search?q=transitional

keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=transition

https://inkpi.blogspot.com/search?q=transizione

https://inkpi.blogspot.com/search?q=transizioni

keyword 'vortex' in FonT

https://flashontrack.blogspot.com/search?q=vortex

keyword 'vortice' in Notes

 (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=vortice

keywords: gst, transition, vortex, baker map

# life: a proposito di transizioni ...

a proposito di transizioni ... 

<< se si considera la limitatezza del numero degli standards da essi tante volte 'rigenerati'. >> 

<< Il problema qui - in una prospettiva sperimentale - non sembra la generazione (quasistocastica?) delle forme inattese, bensi' inerente la struttura logico- funzionale dei "filtri", dei setacci cioe', capaci di trattenere (e conservare) le soluzioni funzionali al codice, "metastabili" in senso evolutivo, con l'eliminazione di tutto cio' che puo' contribuire alla rigidita' strutturale dell' insieme.  >>

2134 - bizzarrie bop sugli standard. Notes. Apr 29, 2007. 

https://inkpi.blogspot.com/2007/04/2134-bizzarrie-bop-sugli-standard.html

https://twitter.com/flashontrack/status/1547867345502158853

Also

keyword 'transition' | 'transitional' in FonT

https://flashontrack.blogspot.com/search?q=transition

https://flashontrack.blogspot.com/search?q=transitional

keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=transition

https://inkpi.blogspot.com/search?q=transizione

https://inkpi.blogspot.com/search?q=transizioni

Keywords: life, transition, evolution, quasi-stochastic,  poetry, quasi-stochastic poetry,  fuzzypoe, droploids.

# gst: substrate friction and geometric confinement could act as transitional control parms (in active nematics).

<< Using a minimal continuum model, (AA) investigate the interplay between circular confinement and substrate friction in active nematics. Upon increasing the friction from low to high, (They) observe a dynamical phase transition from a circulating flow phase to an anisotropic flow phase in which the flow tends to align perpendicular to the nematic director at the boundary. (AA) demonstrate that both the flow structure and dynamic correlations in the latter phase differ from those of an unconfined, active turbulent system and may be controlled by the prescribed nematic boundary conditions. (AA) results show that substrate friction and geometric confinement act as valuable control parameters in active nematics. >> 

Cody D. Schimming, C. J. O. Reichhardt, C. Reichhardt. Friction-mediated phase transition in confined active nematics. Phys. Rev. E 108, L012602. Jul 27, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.L012602 

https://twitter.com/PhysRevE/status/1684921441651691520

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

Keywords: gst, transition, friction, friction-mediated phase transition, confinement, nematics