# 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

# art: nature as a bizarre artist, the self-sculpted Sphinx.

<< There is evidence that the Great Sphinx was a natural landform before its surface features were chiseled by the ancient Egyptians. Is this controversial theory plausible? >>

AA << carried out experiments on the fluid mechanical erosion of clay. Based on accounts of the nonuniform composition of the Sphinx, we tested the effect of hard inclusions within hillocks of softer clay. The flow of a water tunnel mimics the prevailing winds of Giza, and three-dimensional optical scanning records the history and evolution of the shape as it erodes. >>

<< These results show what ancient peoples may have encountered in the deserts of Egypt and why they envisioned a fantastic creature. >>️

️

Samuel Boury, Scott Weady, Leif Ristroph. Sculpting the Sphinx. Phys. Rev. Fluids 8, 110503. Nov 16, 2023.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.110503

https://gfm.aps.org/meetings/dfd-2022/6323dcaf199e4c2c0873fad7

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

Keywords: art, sculpt, Sphinx, erosion, fluid mechanical erosion, brain, mind, perceptions.

# life: POTUS race 2024, Native voters could make a difference

<< There are predicted to be at least 5 million Native and Alaska Native-identifying voters in the U.S. in both rural and urban communities, according to the U.S. Census Bureau — although estimates are expected to be an undercount. >>️

<< Native Americans are incredibly influential and have the ability to really swing those elections on the margins, >> Jacqueline De Leon.

<< Hanging in the balance is control of House, Senate and the Oval Office in 2024. In a country in which turnout can make or break campaigns, organizers said courting Native voters can dictate a candidate's success. (..) Organizers argue Native voters are increasingly a coalition to watch, even if parties have not fully recognized them yet. (..) Here are some of the states where Native voters could have a significant impact on 2024 races for Congress, the Senate and for president. >>️️

Ximena Bustillo. Sometimes overlooked by campaigns, Native voters could decide major elections in 2024. NPR. Nov 21, 2023. 

https://www.npr.org/2023/11/20/1213525361/native-voters-influence-2024-elections-arizona-montana-wisconsin 

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

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

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

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

Keywords: potus, potus race, Native, Native voters, life, transition, edge, margin

# gene: bacteria and archaea CRISPR everywhere in nature

<< Single-celled bacteria and archaea use CRISPR systems to defend themselves against viruses known as bacteriophages. (..) Until now, researchers had identified six types of CRISPR system, designated I–VI. >>

AA << developed an algorithm called FLSHclust, which analyses genetic sequences in public databases. (..) By looking at the predicted function of the clusters, the researchers found around 130,000 genes associated in some way with CRISPR, 188 of which had never been seen before, >>️️

<< It’s a treasure trove for biochemists, >> Lennart Randau.

Sara Reardon. ‘Treasure trove’ of new CRISPR systems holds promise for genome editing. Nature. doi: 10.1038/ d41586-023-03697-w. Nov 23, 2023. 

https://www.nature.com/articles/d41586-023-03697-w

Han Altae-Tran, Soumya Kannan, Feng Zhang, et al. Uncovering the functional diversity of rare CRISPR-Cas systems with deep terascale clustering. 

Science, Vol 382, Issue 6673. doi: 10.1126/ science.adi1910. Nov 23, 2023. 

https://www.science.org/doi/10.1126/science.adi1910

Also: 'CRISPR' in https://flashontrack.blogspot.com/search?q=crispr  

Keywords: genome, gene, crispr, crispr system, ai, artificial intelligence

# 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

# behav: the self-care hypothesis of the puteketeke bird (great crested grebe, Podiceps cristatus)

<< The Puteketeke bird has been elected as New Zealand's Bird of the Century after John Oliver promoted the bird not just on his show, but around the world. >>

<< It also exhibits some unusual antics, like eating feathers to help it vomit up parasites,  >> AILSA CHANG

️

<< They have a mating dance where they both grab a clump of wet grass and chest bump each other... >> JOHN OLIVER

Kat Lonsdorf, Christopher Intagliata. The Puteketeke bird has been elected as New Zealand's Bird of the Century. npr.org Nov 15, 2023. 

https://www.npr.org/2023/11/15/1213287236/the-puteketeke-bird-has-been-elected-as-new-zealands-bird-of-the-century

L’uccello del secolo della Nuova Zelanda l’ha deciso John Oliver. ilpost.it. Nov 15, 2023. 

https://www.ilpost.it/2023/11/15/john-oliver-uccello-secolo-nuova-zelanda/

the bird: https://youtu.be/98ceB5SPRXI

John Oliver, an interview: https://youtu.be/uVE1hBzHn3s

many thanks to Tammi ( https://www.inkgmr.net/tammi ) for this news. 

Also: Self-perception of health and survival. A 10-year follow-up among Italians aged over sixty. INRCA, Technical Report, Genova, 7 March 1995: 1-19. Minerva Med 1997 Jan-Feb 88:1-2 15-23. [abst] https://pubmed.ncbi.nlm.nih.gov/9093288/

Also: 'behav', 'perception', in https://www.inkgmr.net/kwrds.html

Keywords: behaviour, self-care, perceptions

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

# life: a painted texture glimpsed through 25 words

<< If you want to understand the complicated nature of the United States in 2023, ask Americans to define their country themselves. In the past year, the American Communities Project did just that. It visited four different counties and asked passersby to define 25 words, including America, and the responses showed a range of opinions. >>️

<< The media tends to explain the divides in United States in binary terms — red/blue, left/right, urban/rural. News stories discuss war between two conflicting “cultures” in the country. Sometimes included is a third option for “independents” or “centrists.” But look closer and the picture is far more complicated, marked by fault lines that can be hard to see. >>️

Dante Chinni, Ari Pinkus. New Survey Breaks Down America’s Complicated Landscape. American Communities Project/Ipsos. Oct 26, 2023. 

https://www.americancommunities.org/new-survey-breaks-down-americas-complicated-landscape

Also: 

Immediate 'shot', the three second time window in art, music, poems and language processing. FonT. Apr 30, 2021.

https://flashontrack.blogspot.com/2021/04/gst-immediate-shot-three-second-time.html

Effetto Northridge. Notes. Sep 26, 2005.

(quasi-stochastic poetry)

https://inkpi.blogspot.com/2005/09/1887-effetto-northridge.html

Keywords: life, self-perception

# 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

# life: call for four Parrondo's paradox peacekeeper players

<< US President Joe Biden has said world history is at "an inflection point" as he made the case for a "smart investment" of ... >> Ukraine, Israel, Taiwan.

️

Holly Honderich, Sarah Smith. Biden seeks 'vital' (..) aid for Israel and Ukraine. BBC News, Oct 20, 2023. 

https://www.bbc.co.uk/news/world-us-canada-67164900

Also: Switch to three players within the Parrondo game. FonT. Jun 11, 2022.

https://flashontrack.blogspot.com/2022/06/gst-switch-to-three-players-within.html

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

Also: "Parrondo"[TIAB], in https://pubmed.ncbi.nlm.nih.gov/

Also: Parrondo, in https://arxiv.org/search/?query=Parrondo&searchtype=abstract&abstracts=show&order=-announced_date_first&size=50

Keywords: life, game, Parrondo, Potus, war, nfulaw

# game: noise-induced Parrondo's paradox in discrete-time qu-walks

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

AA << show that noise can induce Parrondo's paradox in one-dimensional discrete-time quantum walks with deterministic periodic as well as aperiodic sequences of two-state quantum coins where this paradox does not occur in the absence of noise. >>️

Zbigniew Walczak, Jarosław H. Bauer. Noise-induced Parrondo's paradox in discrete-time quantum walks. Phys. Rev. E 108, 044212. Oct 11, 2023.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.044212

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

Keywords: games, parrondo, walk, noise

# 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

# phys: a quantum gravity hypothesis on infalling matter (hunting for extreme Kerr black holes)

 << Quantum gravity refers to a group of theories—string theory, for example—that aims to reconcile the microscopic world of quantum physics with the macroscopic world of general relativity. >> 

 << Now theoretical work by Grant N.  Remmen (et al) shows that celestial objects called extremal Kerr black holes are highly sensitive to quantum gravity. >> 

 

  << A Kerr black hole is a rotating, electrically neutral black hole. It is said to be extremal if it has the highest possible angular momentum that is compatible with its mass.  Extremal Kerr black holes have yet to be detected, but many theories predict their existence. >> 

 

 They << point out that quantum corrections to general relativity would provide specific contributions to a quantity called the effective action, which describes the dynamics of a gravitational field. (..) under quantum gravity, the event horizon would develop curvature singularities—regions where the gravitational field is infinitely strong. >> 

 

 << the next step is to hunt for extremal Kerr black holes and to try to detect these curvature singularities through their effect on infalling matter. >> 

Ryan Wilkinson. New Physics Magnified in Spinning Black Holes. Physics 16, s117. Aug 31, 2023.

https://physics.aps.org/articles/v16/s117 

Gary T. Horowitz, Maciej Kolanowski, Grant N. Remmen, Jorge E. Santos. Extremal Kerr Black Holes as Amplifiers of New Physics. Phys. Rev. Lett. 131, 091402. Aug 31, 2023.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.091402

Also: Ingrid Fadelli. Theoretical study shows that Kerr black holes could amplify new physics. Phys.org. Sep 22, 2023. 

https://phys.org/news/2023-09-theoretical-kerr-black-holes-amplify.html

Also: astrophysics, black hole, in: https://www.inkgmr.net/kwrds.html

Keywords: astrophysics, black holes

# life: a proposito di '1or2achoos' (da Wuhan (?)), qui la cronologia

a proposito di '1or2achoos' (da Wuhan (?)), qui la cronologia di inizio dei 6 flu|covid che ho contratto dal gen2020 ad oggi con i relativi tempi di 'smorzamento' dell'infezione, trattati nebulizzando una miscela di alcool e H2O2 ( https://flashontrack.blogspot.com/2022/07/life-aproposito-di-1or2achoos-da-wuhan.html )

(1) 2020.04.11-16:04 ~12h (non vaccinato)

(2) 2021.09.01-07:40 ~12h (non vaccinato)

(3) 2022.06.11-08:26 18-36h (+1mese post vaccino, 3dosi)

(4) 2022.12.24-07:52 ~24h 

(5) 2023.02.28-12:09 ~24h 

(6) 2023.04.08-09:32 24-36h 

I tempi necessari per 'spegnere' questi  flu|covid sono tutti notevolmente inferiori (~80%) rispetto alle pregresse forme di flu che ho contratto delle quali ho memoria.

Invece non ho altre parole da aggiungere per commentare i diversi argomenti associabili a '1or2achoos' dal febbraio 2020 ad oggi.

Potrei (e.g. expectedepidemic, lockdown, greenpass, indicatori, statistiche, accademieacucciabili, sadichepredazioni, bucodibilancio, pastroky, ...) nelle bizzarre forme della poetica quasistocastica ( https://inkpi.blogspot.com/ ), ma mi astengo.

Anche: "Ricordo che quando si era ragazzi". in: "il pino di takata matsubara". Notes. Apr 1, 2011. https://inkpi.blogspot.com/2011/04/2157-il-pino-di-takata-matsubara.html

Anche: "e Da-Li' si sparse pell'aere". in: "cracker tendenziali". Notes. Apr 4, 2008. https://inkpi.blogspot.com/2008/04/cracker-tendenziali-around-matter.html

Anche: "in attesa del beffardo tsunami". in: "onda di carambola". Notes. Nov 29, 2004. 

https://inkpi.blogspot.com/2004/11/1619-onda-di-carambola.html

Anche: "aproposito di '1or2achoos' (da Wuhan (?)) ...". FonT. Jul 13, 2022. https://flashontrack.blogspot.com/2022/07/life-aproposito-di-1or2achoos-da-wuhan.html

Anche: 1or2achoos, sars, covid, virus, pastroky, in: 

https://www.inkgmr.net/kwrds.html

Keywords: life, virus, flu, coronavirus,  sarscov2, covid19, 1or2achoos, mask

# 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: tuning of Janus particles under flows

<< Active colloidal systems with nonequilibrium self-organization constitute a long-standing, challenging area in material sciences and biology. To understand how hydrodynamic flow may be used to actively control self-assembly of Janus particles (JPs), (AA)  developed a model for the many-body hydrodynamics of amphiphilic JPs suspended in a viscous fluid with imposed far-field background flows. >>

They << alter the hydrophobic distribution on the JP-solvent interface to investigate the hydrodynamics that underlies the various morphologies and rheological properties of the JP assembly in the suspension. (They) find that JPs assemble into unilamellar, multilamellar, and striated structures. >>

AA << characterize the effective material properties of the JP structures and find that the unilamellar structure increases orientation order under shear flow, the multilamellar structure behaves as a shear thinning fluid, and the striated structure possesses a yield stress. >> ️

Szu-Pei Fu, Rolf Ryham, Bryan Quaife, and Y.-N. Young. Effects of tunable hydrophobicity on the collective hydrodynamics of Janus particles under flows. Phys. Rev. Fluids 8, 050501. May 11, 2023.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.050501

Also: Janus, in FonT:  https://flashontrack.blogspot.com/search?q=janus

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

Keywords: particles, Janus, Janus particles, self-organization, self-assembly

# 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: sudden phase transitions among nonconservative system with nonreciprocal interactions

<< A nonconservative system with nonreciprocal interaction has been found to reveal exotic features where sudden phase transitions can occur. >>️

Here AA reported << the emanation of a chimera in a network of Stuart-Landau oscillators. >>

<< The findings could have pragmatic implications in the areas of active matter, networks, and photonics. >>

️

M. Paul Asir. Emergence of chimeras: An impetus by exceptional points. Phys. Rev. E 108, 024220. Aug 22, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.024220

Also: Stuart–Landau equation. 

https://en.m.wikipedia.org/wiki/Stuart%E2%80%93Landau_equation

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

Keywords: network, transition, chimera, chaos, pattern formation

# 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

# gst: stochastic resonance mediated by optimal noise level values; transport of colloidal particles induced by substrate concentration oscillations.

AA << show the existence of a  stochastic resonant regime in the transport of active colloidal particles under confinement. The periodic addition of substrate to the system causes the spectral amplification to exhibit a maximum for an optimal noise level value. The consequence of this is that particles can travel longer distances with lower fuel consumption. The stochastic resonance phenomenon found allows the identification of optimal scenarios for the transport of active particles, enabling them to reach regions that are otherwise difficult to access, and may therefore find applications in transport. >>️

J. D. Torrenegra-Rico, A. Arango-Restrepo, J. M. Rubi. Optimal transport of active particles induced by substrate concentration oscillations. Phys. Rev. E 108, 014134. July 28, 2023.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.014134

Img: https://twitter.com/PhysRevE/status/1687119409096089602

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

Keywords: gst, particle, colloids, noise, stochastic resonance, substrate oscillation

# 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

# behav: use of social information in flight (among ‘griffon’ vultures Gyps fulvus and G. rueppellii)

 <<Animals rely on a balance of personal and social information to decide when and where to move next in order to access a desired resource, such as food. The benefits from cueing on conspecifics to reduce uncertainty about resources availability can be rapidly overcome by the risks of within-group competition, often exacerbated toward low-ranked individuals. Being obligate soarers, relying on thermal updrafts to search for carcasses around which competition can be fierce, vultures represent ideal models to investigate the balance between personal and social information during foraging movements. Linking dominance hierarchy, social affinities and meteorological conditions to movement decisions of eight captive vultures, Gyps spp., released for free flights in natural-like soaring conditions,  (AA) found that they relied on social information (i.e. other vultures using/having used the thermals) to find the next thermal updraft, especially in unfavourable flight conditions. Low-ranked individuals were more likely to disregard social cues when deciding where to go next, possibly to minimise the competitive risk of social aggregation. These results exemplify the architecture of decision-making during flight in social birds. It suggests that the environmental context, the context of risk and the social system as a whole calibrate the balance between personal and social information use. >> 

Sassi Yohan, Nouzieres Basile, Scacco Martina, et al. The use of social information in vulture flight decisions. bioRxiv. doi: 10.1101/ 2023.07.26.550671. Jul 28, 2023.

https://www.biorxiv.org/content/10.1101/2023.07.26.550671v1

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

# gst: tipping in a low-dimensional model of a (tropical) cyclone.

 <<Tipping is the rapid, and often irreversible, change in the state of a system [Ashwin P. et al (2017)] >> 

AA << present a case study of both rate and noise-induced tipping between the stable states, relating to the destabilization or formation of a tropical cyclone. While the stochastic system exhibits transitions both to and from the non-storm state, noise-induced tipping is more likely to form a storm, whereas rate-induced tipping is more likely to be the way a storm is destabilized, and in fact, rate-induced tipping can never lead to the formation of a storm when acting alone. For rate-induced tipping acting as a destabilizer of the storm, a striking result is that both wind shear and maximal potential velocity have to increase, at a substantial rate, in order to effect tipping away from the active hurricane state. For storm formation through noise-induced tipping, (AA) identify a specific direction along which the non-storm state is most likely to get activated. >> 

Katherine Slyman, John A. Gemmer, et al. Tipping in a Low-Dimensional Model of a Tropical Cyclone. arXiv: 2307.15583v1 [math.DS]. Jul 28, 2023.

https://arxiv.org/abs/2307.15583

 

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

Keywords: gst, climate, storm, cyclone, vortex, noise, tipping, noise-induced tipping

# gst: dynamics and interactions of multiple bright droplets and bubbles, and interactions of kinks with droplets and with antikinks.

<< Droplets bearing different chemical potentials experience mass-exchange phenomena. Individual bubbles exhibit core expansion and mutual attraction prior to their destabilization. Droplets interacting with kinks are absorbed by them, a process accompanied by the emission of dispersive shock waves and gray solitons. Kink-antikink interactions are repulsive, generating counter-propagating shock waves. >> 

 

G. C. Katsimiga, S. I. Mistakidis, et al. Interactions and dynamics of one-dimensional droplets, bubbles and kinks. arXiv: 2306.07055v2 [cond-mat.quant-gas]. Jul 26, 2023.

https://arxiv.org/abs/2306.07055

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

Keywords: gst, drop, bubble, kink, wave, soliton, homoclinic orbits

# gst: transitions by coupled instabilities

AA << present an experimental study of quasiperiodic transitions between a highly ordered square-lattice pattern and a disordered, defect-riddled state, in a circular Faraday system. (They)  show that the transition is driven initially by a long-wave amplitude modulation instability, which excites the oscillatory transition phase instability, leading to the formation of dislocations in the Faraday lattice. The appearance of dislocations dampens amplitude modulations, which prevents further defects from being created and allows the system to relax back to its ordered state. The process then repeats itself in a quasiperiodic manner. >>

Valeri Frumkin, Shreyas Gokhale. Coupled instabilities drive quasiperiodic order-disorder transitions in Faraday waves. Phys. Rev. E 108, L012601. July 17, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.L012601

Also: parrondo, tit-for-tat, game, transition, chaos, in https://www.inkgmr.net/kwrds.html

Keywords: parrondo, tit-for-tat, game,  transition, chaos

# gst: inertial particles within co-rotating dusty vortices

 << dispersed particles with moderate inertia cause the vortex pair to push apart to a separation nearly twice as large as the initial separation. >>

 

 << antisymmetric vorticity generated by particles flung out of the rotational cores causes the vortex pair repulsion. Eventually, the two dusty vortices merge into a single vortex with most particles accumulating outside the core similar to the dusty Lamb-Oseen vortex described in Shuai & Kasbaoui (2022) >>

 

 << For weakly inertial particles, (AA) find that the merger dynamics follow the same mechanics as those of a single-phase flow, albeit with a density that must be adjusted to match the mixture density. >>

 

<< Lastly, highly inertial particles tend to fragment the vortex cores leading to murky merger dynamics. >>

Shuai Shuai, Anubhab Roy, M. Houssem Kasbaoui. The merger of co-rotating vortices in dusty flows. arXiv: 2307.05413v1 [physics.flu-dyn]. Jul 11, 2023. 

https://arxiv.org/abs/2307.05413

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

Keywords: gst, particle, vortex 

# gst: evolution of survivors compared to discrete vs continuous noise

<< Environmental variations can significantly influence how populations compete for resources, and hence shape their evolution. Here, (AA) study population dynamics subject to a fluctuating environment modeled by a varying carrying capacity changing continuously in time according to either binary random switches, or by being driven by a noise of continuous range. >>

<< the slow strain fixation probability can be greatly enhanced for a continuously varying environment compared to binary switches, even when the first two moments of the carrying capacity coincide. >>️

Ami Taitelbaum, Robert West, et al. Evolutionary dynamics in a varying environment: Continuous versus discrete noise. Phys. Rev. Research 5, L022004. April 4, 2023. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.L022004

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

Keywords: gst, evolution, noise, discrete vs continuous noise

# brain: the sense of hearing, the sense of silence.

<< Do we only hear sounds? Or can we also hear silence? These questions are the subject of a centuries-old philosophical debate between two camps: the perceptual view (we literally hear silence), and the cognitive view (we only judge or infer silence). >>

<< In all cases (concerning seven experiments), silences elicited temporal distortions perfectly analogous to their sound-based counterparts, suggesting that auditory processing treats moments of silence the way it treats sounds. Silence is truly perceived, not merely inferred. >>️

️

Rui Zhe Goh, Ian B. Phillips, Chaz Firestone. The perception of silence. 

PNAS. 120 (29) e2301463120. Jul 10, 2023. 

https://www.pnas.org/doi/10.1073/pnas.2301463120

Roberto Molar Candanosa. The sound of silence? Researchers prove we can  hear it. Johns Hopkins University - HUB. Jul 11, 2023. 

https://hub.jhu.edu/2023/07/11/can-we-hear-silence 

Researchers Prove We Hear the 

Sound of Silence. Jul 10, 2023. 

https://youtu.be/nCRosndUfMc

Also: silence, pause, sound, noise, perception, brain, in https://www.inkgmr.net/kwrds.html 

Keywords:  brain, perception, sound, noise, pause, silence

# gst: complex flows by hairpin vortices behind hills with different scales

 << In the flow around protuberance, separation bubbles occur ahead and behind the protuberance, and a coherent vortex structure exists in the wake. In such a flow field, heat, substance, and momentum are actively transported by the vortex. (..) When multiple protuberances are set in the flow, the wakes of the protuberances interfere with each other, resulting in complicated flows. >> 

 << This study performed a numerical analysis of the hairpin vortex and heat transport generated by the interference of the wakes behind two hills in a laminar boundary layer. In the case of hills with the same scale, the interference between hairpin vortices in the wake is more intensive than in the different-scale hills. When the hills with different scales are installed, hairpin vortices with different scales are periodically shed. >> 

 

  << Regardless of the scale ratio of the hills, when the hill spacing in the spanwise direction is narrowed, the asymmetry of the hairpin vortex in the wake increases due to the interference between the wakes. At this time, the turbulence caused by the leg and the horn-shaped secondary vortex on the spanwise center side in the hairpin vortex increases, and heat transport around the hairpin vortex becomes active. >> 

 

Hideki Yanaoka, Tatsuya Hamada. Hairpin vortices and heat transfer in the wakes behind two hills with different scales. arXiv: 2306.17365v1 [physics.flu-dyn]. Jun 30, 2023. 

https://arxiv.org/abs/2306.17365

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

Keywords: gst, vortex, hairpin vortex, turbulence

# life: declining towards turbulence, thus ecstatic (detotuthec)

(1/3) for our birthdays on July 11th (*1th) and July 25th (*9th) ... forever Nomads (*), curious, young.  

https://www.inkgmr.net   https://www.inkgmr.net/tammi

@flashontrack  11:36 11lug21

https://twitter.com/flashontrack/status/1414156586889748482

(2/3) (*) e.g. exotic, maverick, agnostic,  track seeker, meta-mechanic pulsating manipulator, ockhamistic, erratic, chaotic, #detotuthec (declining towards turbulence, thus ecstatic), ab-normal ...

@flashontrack 11:37 11lug21

https://twitter.com/flashontrack/status/1414156987240173569

(3/3) with mindfulness, compassion and tenacity, where also vengeance consists in (try) saving others (whatever 'others' means).

@flashontrack 11:38 11lug21

https://twitter.com/flashontrack/status/1414157124318507008

Keywords: detotutech, detect thou

# gst: myriad of complex dynamics from the atomization of acoustically levitated droplets

AA << report the dynamics of a droplet levitated in a single-axis acoustic levitator. The deformation and atomization behavior of the droplet in the acoustic field exhibits a myriad of complex phenomena, in sequences of steps. These include the primary breakup of the droplet through stable levitation, deformation, sheet formation, and equatorial atomization, followed by secondary breakup which could be umbrella breakup, bag breakup, bubble breakup or multistage breakup depending on the initial size of the droplet. >>

<< Both the primary and the secondary breakup of the droplet admit interfacial instabilities such as Faraday instability, Kelvin Helmholtz (KH) instability, RT instability, and RP instability and are well described with visual evidence. >>️

Sunil K. Saroj, Rochish M. Thaokar. Atomisation of an acoustically levitated droplet: Experimental observations of a myriad of complex phenomenon. arXiv: 2307.00400v1 [physics.flu-dyn]. Jul 1, 2023.

https://arxiv.org/abs/2307.00400

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

Keywords: gst, drop, droplet, transition, instability

# behav: how a microbiota (Curvibacter sp.) could modulate eating behavior in Hydra.

(AA) << studied the eating behavior of Hydra, a host that has a simple nervous system and a low-complexity microbiota. >>

(They) << demonstrate that different neuronal subpopulations are functioning together to control the eating behavior. The microbiota participates in control of the eating behavior since germ-free or mono-colonized animals have drastic difficulties in mouth opening. This was restored by adding a full complement of the microbiota. >>️

The << findings confirm and expand on the idea that in animals without a central nervous system, a complex behavior is controlled by multiple subpopulations of neurons, forming circuits and modules. (Their)  observations presented here show that this not only requires the coordination of multiple neuronal circuits, but also that signals from the microbial environment play an important role. >>

Christoph Giez, Denis Pinkle, et al.  Microbes as part of ancestral neuronal circuits: Bacterial produced signals affect neurons controlling eating behavior in Hydra. BioRxiv. doi: 10.1101/ 2023.04.28.538719. Apr 29, 2023. 

https://www.biorxiv.org/content/10.1101/2023.04.28.538719v1

Also: How a virus could cause context-dependent manipulation in host social behavior.  Apr 28, 2020.  https://flashontrack.blogspot.com/2020/04/gst-how-virus-could-cause-context.html

Keywords: behav, eating behavior, food, Hydra, microbiota 

# brain: spiral waves at the edge of neural tissue during cognitive processing.

AA << have discovered human brain signals travelling across the outer layer of neural tissue that naturally arrange themselves to resemble swirling spirals. >>️

<< The research (..) indicates these ubiquitous spirals, which are brain signals observed on the cortex during both resting and cognitive states, help organise brain activity and cognitive processing. >>️

<< Our study suggests that gaining insights into how the spirals are related to cognitive processing could significantly enhance our understanding of the dynamics and functions of the brain, (..) These spiral patterns exhibit intricate and complex dynamics, moving across the brain’s surface while rotating around central points known as phase singularities. >> Pulin Gong.

<< One key characteristic of these brain spirals is that they often emerge at the boundaries that separate different functional networks in the brain, >> Yiben Xu. 

Philip Ritchie. Scientists discover spiral-shaped signals that organise brain activity. sydney.edu.au. Jun 16, 2023. 

https://www.sydney.edu.au/news-opinion/news/2023/06/16/scientists-discover-spiral-shaped-signals-that-organise-brain-activity.html

https://youtu.be/YZlqokljqY8️

Yiben Xu, Xian Long, Jianfeng Feng & Pulin Gong. Interacting spiral wave patterns underlie complex brain dynamics and are related to cognitive processing. Nat Hum Behav. doi: 10.1038/ s41562-023-01626-5. Jun 15,  2023.

https://www.nature.com/articles/s41562-023-01626-5

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

Keywords: brain, vortex, waves,  cognition

# gst: a flapping forward flight (among Papilio polytes and Kallima inachus)

<< The effect of wing shape on a forward-flying butterfly via decoupled factors of the wing-swept angle and the aspect ratio (AR) was investigated numerically. >>️

<< The results show that, through (AA) models, the effects of the wing-swept angle and AR were decoupled; both have distinct flow mechanisms and aerodynamic force trends and are consistent in the two butterfly species (Papilio polytes and Kallima inachus). For a fixed AR, a backward-swept wing increases lift and drag because of the enhanced attachment of the leading-edge vortex with increased strength of the wingtip vortex and the spanwise flow. For a fixed wing-swept angle, a small AR wing increases lift and decreases drag because of the large region of low pressure downstream and the wake-capture effect. Coupling these effects, the largest lift-to-drag ratio occurs for a forward-swept wing with the smallest AR. These results indicate that, in a flapping forward flight, sweeping a forewing forward relative to a hindwing is suitable for cruising. >>

Sheng-Kai Chang, You-Jun Lin, Kuan-Lun Hsu, and Jing-Tang Yang. Decoupling wing-shape effects of wing-swept angle and aspect ratio on a forward-flying butterfly. Phys. Rev. E 107, 065105. Jun 23, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.107.065105

️

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

Keywords: gst, butterfly, wing, wing-shape, flight, vortex

# gst: laminar and turbulent flows detected in music, a fluid framework approach

<< The relationship between musical material and physical phenomena has become a topic in the musicological literature over the last several decades, particularly concerning elements of the musical system itself, and constructions found in the work of contemporary classical composers such as Gyorgy Ligeti and Iannis Xenakis. Most scholars, who adopt this approach, explore the physical phenomena of fractals in the analysis of musical works, but fluid mechanical frameworks, such as laminar and turbulent flows, offer a new avenue to be explored. In this paper (AA) will propose a novel method of musical analysis for examining musical structures in terms of fluid-like behaviour such that Ligeti etude no. 9 serves as a model, whereby the metaphors of laminar and turbulent flows take precedence. >>

Noah Chuipka. Musico-acoustic Depictions of Laminar and Turbulent Flows in Ligeti Piano Etude No. 9 and a Novel Method of Analysis. arXiv: 2306.10093v1 [cs.SD]. Jun 17, 2023. 

https://arxiv.org/abs/2306.10093

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

Keywords: gst, music, jazz, turbulence

# gst: apropos of the shepherding problem, a collision-free model between sheep and shepherd

<< The shepherding problem refers to guiding a group of agents (called sheep) to a specific destination using an external agent with repulsive forces (called shepherd). Although various movement algorithms for the shepherd have been explored in the literature, there is a scarcity of methodologies for selective guidance, which is a key technology for precise swarm control. >>️

AA << study investigates the problem of guiding a single target sheep within a swarm to a given destination using a shepherd. (AA) first present (their) model of the dynamics of sheep agents and the interaction between sheep and shepherd agents. The model is shown to be well-defined with no collision if the interaction magnitude between sheep and shepherd is reasonably limited. Based on the analysis with Lyapunov stability principles, (AA) design a shepherd control law to guide the target sheep to the origin while avoiding collisions among sheep agents. >>️

Yaosheng Deng, Aiyi Li, Masaki Ogura, Naoki Wakamiya. Collision-Free Shepherding Control of a Single Target within a Swarm. arXiv: 2306.12044v1 [nlin.AO]. Jun 21, 2023.

https://arxiv.org/abs/2306.12044

Also:  behav, swarm, game, sadistic, ctz  in:  https://www.inkgmr.net/kwrds.html

Keywords: gst, behav, swarm, game