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Visualizzazione post con etichetta transition. Mostra tutti i post
Visualizzazione post con etichetta transition. Mostra tutti i post

venerdì 10 febbraio 2023

# gst: apropos of transitions, a perpetual dance between states of meta-stability and chaos (in brain).


<< Hello! Today: new research is shining a light on how our brains flit between states of stability and chaos, depending on what we’re doing. >>

<< Our brains exist in a state somewhere between stability and chaos as they help us make sense of the world, according to recordings of brain activity taken from volunteers over the course of a week. >>

<< As we go from reading a book to chatting with a friend, for example, our brains shift from one semi-stable state to another—but only after chaotically zipping through multiple other states in a pattern that looks completely random. >>

<< Understanding how our brains restore some degree of stability after chaos could help us work out how to treat disorders at either end of this spectrum. Too much chaos is probably what happens when a person has a seizure, whereas too much stability might leave a person comatose. >>

Jessica Hamzelou. Neuroscientists listened in on people’s brains for a week. They found order and chaos. Rhiannon Williams. MIT Download. Feb 8, 2023.


<< The team (Avniel Ghuman, Maxwell Wang, et al.) found some surprising patterns in brain activity over the course of the week. Specific brain networks seemed to communicate with each other in what looked like a “dance,” with one region appearing to “listen” while the other “spoke,” say the researchers, who presented their findings at the Society for Neuroscience annual meeting in San Diego last year. >>

Jessica Hamzelou. MIT Tech Rev. Feb 7, 2023. 

Also 

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

keyword 'dance' in FonT

keyword 'cervello' | 'brain' in Notes
(quasi-stochastic poetry)


keyword 'brain' in FonT

keyword 'chaos' | 'chaotic' in Font


keyword 'caos' | 'caotico' in Notes (quasi-stochastic poetry)


<< Amico, qualunque  cosa suonerai . . . >>  Jelly Roll Morton. cit.: 2113 - soniche a ramulo. Jan 28, 2007


Keywords: gst, brain, transition, chaos, dance



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Etichette: , , , ,

giovedì 22 dicembre 2022

# 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.

Also

keyword 'transition' in FonT: 

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



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







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Etichette: , , , , ,

mercoledì 21 dicembre 2022

# 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. 

Also

keyword 'transition' | 'transitional' in FonT



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




keyword 'waves' in FonT


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


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









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Etichette: , , , , , , , ,

martedì 20 dicembre 2022

# gst: slow dynamics of a interacting mobile impurity (in a bath of localized particles)

AA << investigate dynamics of a single mobile impurity immersed in a bath of Anderson localized particles and focus on the regime of relatively strong disorder and interactions. In that regime, the dynamics of the system is particularly slow, suggesting, at short times, an occurrence of many-body localization. Considering longer time scales, (AA) show that the latter is a transient effect and that, eventually, the impurity spreads sub-diffusively and induces a gradual delocalization of the Anderson insulator. The phenomenology of the system in the considered regime of slow dynamics includes a sub-diffusive growth of mean square displacement of the impurity, power-law decay of density correlation functions of the Anderson insulator and a power-law growth of entanglement entropy in the system. (AA) observe a similar regime of slow dynamics also when the disorder in the system is replaced by a sufficiently strong quasi-periodic potential. >>

Piotr Sierant, Titas Chanda, Maciej Lewenstein, Jakub Zakrzewski. Slow dynamics of a mobile impurity interacting with an Anderson insulator. arXiv: 2212.07107v1 [cond-mat.dis-nn]. Dec 14, 2022. 

Also

keyword 'particle' | 'quasiparticle' in FonT



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


Keywords: gst, particles, impurity, disorder, sub-diffusive growth, transition, entanglement entropy





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Etichette: , , , , , ,

venerdì 18 novembre 2022

# gst: apropos of transitions, the transition from sticking to slipping.

<< From hydrogels and plastics to liquid crystals, soft solids cover a wide array of synthetic and biological materials that play key enabling roles in advanced technologies >>️

<< Attempts to study the interactions between soft solids and liquids have largely focused on the wetting of soft solids and its resulting deformation at equilibrium or in a quasi-static state. Here, (AA) consider the frequently encountered case of unsteady wetting of a liquid on a soft solid and show that transient deformation of the solid is necessary to understand unsteady wetting behaviours. >>️

AA << find that the initial spreading of the liquid occurs uninterrupted in the absence of solid deformation. This is followed by intermittent spreading, in which transient deformation of the solid at the three-phase contact line (CL) causes the CL motion to alternate alternation between CL sticking and slipping. (They) identify the spreading rate of liquids and the viscoelastic reacting rate of soft solids as the two competing factors in dictating intermittent spreading. (They)  formulate and validate experimentally the conditions required for the contact line to transition from sticking to slipping. By considering the growing deformation of soft solids as dynamic surface heterogeneities, (AA) proposed conditions for stick-slip transition in unsteady wetting on soft solids broaden the classical theory on wetting hysteresis on rigid solids. >>️

Surjyasish Mitra, Quoc Vo, Marcus Lin, Tuan Tran. Unsteady wetting of soft solids. arXiv:2211.07043v1 [cond-mat.soft]. Nov 13, 2022.

Also

keyword 'drop' | 'droplet' | 'droploids' in FonT




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


Keywords: gst, behav, behaviour, transition, soft solids, drop, droplet, sticking, slipping.


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Etichette: , , , , , , , ,

venerdì 4 novembre 2022

# gst: apropos of transitions, disordered systems mimic genetic evolution.


<< A bacterial genome’s evolution under changing drug concentrations displays effects of memory formation and mimics how disordered solids respond to external forces. >>️

AA << simulate the effect on adaptation of an environment that is constantly changing. Using a model that describes how slow-moving disordered systems respond to external forces, (they) find that microbe evolution in changing drug concentrations exhibits hysteresis and memory formation. They use analytical methods and numerical simulations to connect these statistical physics concepts to bacterial drug resistance. >>️

AA << find that this behavior mimics that of disordered systems driven by external forces, such as ferromagnetic materials subjected to magnetic fields or amorphous materials subjected to a shearing force. They say that while their approach focuses on the evolution of drug resistance, the framework can be adapted to other problems in evolutionary biology that involve changing environmental parameters. >>
️
Rachel Berkowitz. Disordered Systems Mimic Genetic Evolution. Physics 15, s118. Sep 20, 2022. 

Suman G. Das, Joachim Krug, Muhittin Mungan. Driven Disordered Systems Approach to Biological Evolution in Changing Environments. Phys. Rev. X 12, 031040. Sep 20, 2022.

Also

keyword 'disorder' in FonT

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

Keywords: gst, disorder, disordered systems, evolution, genetic evolution 



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Etichette: , , , , ,

lunedì 17 ottobre 2022

# life: a proposito di bizzarri scenari, qui un ipotetico scenario22 dipinto dal reale ...

img: Congo Square, New Orleans, Louisiana (wikipedia.org)

In definitiva qui si configurerebbe un - intrigante assai - scenario che, grosso modo, si potrebbe sinteticamente 'dipingere' in questi termini: 

(i) entità tre palle destrogire, animate aciclicamente da interazioni attrattive- repulsive a causa di già a suo tempo disvelate pulsioni neuro cognitive arcaiche, riconducibili a visioni neuro predatorie CTZ estreme, perciò ipoteticamente (si fa per dire) a-priori ad esiti immediati e in prospettiva drammaticamente lesivi- autolesivi; 

(ii) entità tre palle levogire, animate da analoghe pulsività, purtuttavia in.forme  tenui, in modalità sottotraccia, frenate da feed-back a modalità allosterica, ombreggiate, stemperate, diluite, discrete, timidamente celate, talvolta fantasmatiche perfino, quasi ma non del tutto mai silenti, perciò anch'esse a tutti gli effetti operative, sebbene a dinamiche più fluide, lente, meno dirompenti rispetto alle destrogire; 

(iii) entrambe l'Entità destrogire e levogire animat(t)rici,  generat(t)rici di dinamiche bi-multi-forcate, transeunti, con picchi di improvvisi aciclici burst ad effetti RAG-time diretti e inversi;

(iv) lo scenario al contorno e forse anche all'interno, nei vari specifici contesti, riconducibile grosso modo alla formazione aciclica di ipotetici buchi neri non inerti, caratterizzati da aciclicità in compressione e dilatazione - come fossero fisarmoniche - animati (in perpetuo?) da multi vortici in ingresso e in uscita;

Non so se basti compulsare un manuale delle funzioni speciali per formalizzare in qualche adatto topo-modo questo pulsatile multi scenario, purtuttavia assolutamente intrigante ... 

Qui una AI operativa nella formalizzazione di analogie potrebbe modellizzare, forse ... (e.g. https://flashontrack.blogspot.com/2021/08/aibot-mechanism-of-analogy-could-be.html )

Quello che appare evidente è la complessità d'insieme, un bizzarro dipinto, uno scenario dinamico che, al confronto, le storiche danze in Congo Square potrebbero sembrare semplici, ordinate coreografie ... queste, rispetto a quelle, delle topo-forme  'primitive', per dire ed anzicheforse.

In sintesi, i riferimenti (ovviamente generici) del bizzarro scenario: 

(:) buco nero con vortici 

(:) scenari generati da 3 palle 
(a)
(b)

(:) effetti RAG-time (RAG: Ralph, Al, George) 
(a) (quasi-stochastic poetry)
(b)

(:) pulsioni predatorie supportate / giustificate da visioni neuro- post- CTZ nelle modalità arcaiche oppure friendly 

(:) Congo Square, jazz 
(a)
(b)
(c) (quasi-stochastic poetry)

(:) approccio Bertalanffy 

(:) un bizzarro tracciatore 

Anche

"Amico, qualunque cosa suonerai ... "
(a) (quasi-stochastic poetry)
(b)

Keywords: life, gst, Congo Square, jazz, Jelly Roll, transition, three-body, RAG, CTZ, black hole, bizarre tracker




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Etichette: , , , , , , , , , ,

giovedì 29 settembre 2022

# life: apropos of transitions, here is an erratic Creature that slightly fluctuates ...

Here is an erratic Creature 

that slightly fluctuates with quasi-stochastic movements in the natural scenario where everything is full of unpredictability;

what is the Creature looking for?

Perhaps a house, perhaps a vision, a perspective, a spark, a glimmer at least, that helps it to face the unstoppable becoming, anzicheforse ...

the Creature ...
cit Erica Snyder, The Download, MIT Tech Rev, Sept 9, 2022. << Watching this ribbon eel swim is mesmerizing. >>️

Also

keyword 'erratico' | 'erratica' in Notes
(quasi-stochastic poetry)



keyword 'erratic' in FonT


Keywords: life, transition, erratics, erratic creature


Pubblicato da alle Nessun commento:
Etichette: , , ,

giovedì 15 settembre 2022

# gst: solitons as 'emergent elastic objects with spatially dependent stiffness'

<< Since the 1950s, topological solitons have been used to describe elementary particles and particle-like field configurations that appear in systems ranging from subatomic to cosmological scales. Particles are topologically protected, for which transitions to states with different topological charges are restricted. However, formation and annihilation of solitons are universal in almost all branches of physics, which implies that topological protection collapses at certain condition unrevealed. >>

<< Here, (AA) show that solitons can be regarded as emergent elastic objects with spatially dependent stiffness, and a second-order topological phase transition initiates at its softened points, i.e., points with a vanishing eigenvalue of the emergent stiffness matrix. >>
️
Yangfan Hu. Emergent elasticity and topological stability of solitons. arXiv: 2208.14916v1 [nlin.PS]. Aug 31, 2022. 

Also

'Second-order phase transitions' 

keyword 'solitons' in FonT

Keywords: gst, solitons, transition, phase_transition







Pubblicato da alle Nessun commento:
Etichette: , , ,

giovedì 1 settembre 2022

# gst: apropos of transitions, evaporating binary microdroplets with phase segregation

<< Phase segregation triggered by selective evaporation can emerge in multicomponent systems, leading to complex physiochemical hydrodynamics. Recently, Li et al. (2018) and Kim & Stone (2018) reported a segregative behavior (i.e., demixing) in an evaporating binary droplet. In this work, by means of experiments and theoretical analysis, (AA) investigate the flow dynamics after the occurrence of the phase segregation. >>

<< First, (AA) experimentally reveal the overall physiochemical hydrodynamics of the evaporation process, including the segregative behavior and the resulting flow structure close to the substrate. By quantifying the evolution of the radial flow, (they) identify three successive life stages of the evaporation process. >>

<< At Stage I, a radially outward flow is observed. It is driven by the Marangoni effect. At the transition to Stage II, the radial flow partially reverses, starting from the contact line. This flow breaks the axial symmetry and remarkably is driven by the segregation itself. Finally at Stage III, the flow decays as the evaporation gradually ceases. At this stage the segregation has grown to the entire droplet, and the flow is again controlled by the Marangoni effect. The resulting Marangoni flow homogenizes the distribution of the entrapped volatile water over the whole droplet. >>️

Yaxing Li, Pengyu Lv, et al. Physiochemical hydrodynamics of the phase segregation in an evaporating binary microdroplet.arXiv:2208.07861v1 [physics.flu-dyn]  Aug 16, 2022.

Marangoni effect. 


Also

keyword 'drop' | 'droplet' in FonT


Keywords: gst, droplet, transition, evaporation, phase transition, phase segregation, Marangoni flow


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Etichette: , , , , , ,

martedì 19 luglio 2022

# 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. 


Phys. Rev. D 106, 024016 (2022). 


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.  



Also

keyword 'transition' in FonT: 


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



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







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Etichette: , , , , ,

venerdì 15 luglio 2022

# 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. 



Also

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

Pubblicato da alle Nessun commento:
Etichette: , , , , , , ,

sabato 28 maggio 2022

# gst: surface geometry for pattern dynamics, how a static model on a flat surface can propagate over a curved one

<< Pattern dynamics on curved surfaces are found everywhere in nature. The geometry of surfaces have been shown to influence dynamics and play a functional role, yet a comprehensive understanding is still elusive. >>

AA << report for the first time that a static Turing pattern on a flat surface can propagate on a curved surface, as opposed to previous studies, where the pattern is presupposed to be static irrespective of the surface geometry. To understand such significant changes on curved surfaces, (AA) investigate reaction-diffusion systems on axisymmetric curved surfaces. (..) both the symmetries of the surface and pattern participate in the initiation of pattern propagation. >>️

Ryosuke Nishide, Shuji Ishihara. Pattern Propagation Driven by Surface Curvature. arXiv:2205.08064v1 [nlin.PS]. May 17, 2022. 


Keywords: gst, pattern formation, curved surface, transition, geometry














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Etichette: , , , ,

giovedì 31 marzo 2022

# 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. 


Also

keyword 'transition' | 'transitional' in FonT



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




keyword 'vortex' in FonT


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


keywords: gst, transition, vortex, baker map









Pubblicato da alle Nessun commento:
Etichette: , , ,

giovedì 17 marzo 2022

# gst: apropos of weird transitions: from non-equilibrium conditions square droplets and liquid lattices can emerge.


<< Spontaneous emergence of organized states in materials driven by non-equilibrium conditions is of notable fundamental and technological interest. In many cases, the states are complex, and their emergence is challenging to predict. Here, (AA) show that an unexpectedly diverse collection of dissipative organized states emerges in a simple system of two liquids under planar confinement when driven by electrohydrodynamic shearing.

At low shearing, a symmetry breaking at the liquid-liquid interface leads to a one-dimensional corrugation pattern. 

At slightly stronger shearing, topological changes give raise to the emergence of Quincke rolling filaments, filament networks, and two-dimensional bicontinuous fluidic lattices. 

At strong shearing, the system transitions into dissipating polygonal, toroidal, and active droplets that form dilute gas-like states at low densities and complex active emulsions at higher densities. >>

Geet Raju, Nikos Kyriakopoulos, Jaakko V. I. Timonen. Diversity of non-equilibrium patterns and emergence of activity in confined electrohydrodynamically driven liquids. Science  Advances. Vol 7, Issue 38. doi: 10.1126/ sciadv.abh1642. 15 Sep 15, 2021.


<< Things in equilibrium tend to be quite boring, (..) It's fascinating to drive systems out of equilibrium and see if the non-equilibrium structures can be controlled or be useful. Biological life itself is a good example of truly complex behavior in a bunch of molecules that are out of thermodynamic equilibrium. >>  Jaakko Timonen.

Physicists make square droplets and liquid lattices. Aalto University. Sep 15, 2021. 


Also

keyword 'drop' | 'droplet' in FonT



keyword 'goccia' in Notes (quasi-stochastic poetry): 


keywords: gst, drop, droplet, lattice, transition, out of equilibrium.



Pubblicato da alle Nessun commento:
Etichette: , , , , ,

martedì 22 febbraio 2022

# 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. 


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


Also

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


keyword 'black hole' | 'astro' in FonT



keyword 'transition' | 'transitional' in FonT



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




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



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Etichette: , , , , , ,

martedì 15 febbraio 2022

# gst: transitional dynamics among gyrotactic (prolate spheroid) swimmers in turbulence


<< In this study, (AA) consider small, elongated, gyrotactic, swimming particles in homogenous isotropic turbulence (..). Many motile phytoplankton species are gyrotactic, i.e., their swimming direction results from the competition between shear-induced viscous torque and the stabilizing torque due to bottom-heaviness. (..)  Moreover, both single phytoplankton cells and multicellular phytoplankton chains can have elongated shapes, which makes the study of gyrotactic active particles with prolate shapes necessary. >>

AA addressed the following problems:
<< (i) How the clustering is affected by the swimming number Φ and the stability number Ψ? In particular, how to characterize the extent of clustering based on the three-dimensional Voronoi analysis?
(ii) How the clustering is related to the flow structures? This question has two perspectives.  From the space perspective, what are the regions that particles accumulate in? From the time perspective, how long do particles exist in an aggregated state? >>

Zehua Liu, Linfeng Jiang, Chao Sun. Accumulation and alignment of elongated gyrotactic swimmers in turbulence. arXiv:2202.04351v1 [physics.flu-dyn]. Feb 9, 2022.


Also

The effect of noise on the dynamics of microswimmers in externally-driven fluid flows.  


keywords 'turbulence' in FonT   


keywords 'turbolento' in Notes (quasi-stochastic poetry)


keywords: transition, swimmers,  gyrotactic swimmers, spheroids,  prolate spheroids, stability, turbulence


Pubblicato da alle Nessun commento:
Etichette: , , , , , ,

giovedì 10 febbraio 2022

# 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.


Also

keyword 'water' in FonT


keyword 'transition' | 'transitional' in FonT



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




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



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sabato 27 novembre 2021

# gst: apropos of hybrid nanostructures, the Kondo cloud effects on 'impurities' (inside superconductors).

<< when a metal contains magnetic impurities, conduction electrons can form a screening cloud, which essentially screens the impurity's spin. This physical phenomenon is known as the Kondo effect; thus, the resulting cloud is referred to as a Kondo cloud. >>

<< While the behavior of the Kondo cloud in normal systems is well-understood, its properties in the presence of superconducting materials have not yet been explored in depth. So far, most physicists have believed that the screening of impurity spins in hybrid nanostructures takes place predominantly in the screened, rather than in the unscreened, quantum phase. >>

<< The system we considered exhibits a quantum phase transition when the ground state changes between the Kondo state and the so-called Shiba state, (..) Up to now, it was believed that the screening occurs in the Kondo phase. Quite strikingly, we have however, demonstrated that the Kondo cloud exists also in the unscreened phase. >>  Ireneusz Weymann.

Ingrid Fadelli. Study predicts the behavior of a Kondo cloud in a superconductor. Phys.org. Nov  23, 2021. 


Catalin Pascu Moca, Ireneusz Weymann, et al. Kondo Cloud in a Superconductor.  Phys. Rev. Lett. 127, 186804. Oct 27, 2021.


keywords: gst, nano, hybrid nanostructure, superconductor, transition, impurity, Kondo cloud, Kondo effect


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sabato 30 ottobre 2021

# 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. 



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

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