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sabato 29 aprile 2023

# gst: pattern generation through turbulent cascades


<< Fully developed turbulence is a universal and scale-invariant chaotic state characterized by an energy cascade from large to small scales where the cascade is eventually arrested by dissipation. In this Letter, (AA) show how to harness these seemingly structureless turbulent cascades to generate patterns. Conceptually, pattern or structure formation entails a process of wavelength selection: patterns typically arise from the linear instability of a homogeneous state. By contrast, the mechanism (they) propose here is fully non-linear and triggered by a non-dissipative arrest of turbulent cascades. Instead of being dissipated, energy piles up at intermediate scales. Using a combination of theory and large-scale simulations, (AA) show that the tunable wavelength of these cascade-induced patterns is set by a non-dissipative transport coefficient called odd or gyro viscosity. This non-dissipative viscosity is ubiquitous in chiral systems (..). Beyond chiral fluids, cascade-induced pattern formation could occur in natural systems (..) as well as in industrial processes (..). >>

Xander M. de Wit, Michel Fruchart, et al. Pattern formation by non-dissipative arrest of turbulent cascades. arXiv: 2304.10444v1 [cond-mat.soft]. Apr 20, 2023.

Also: 'turbulence', 'vortex', 'game', 'evolution', 'ai' in https://www.inkgmr.net/kwrds.html

Keywords: gst, vortex, vorticity,  turbulence, turbulent cascade, pattern formation, game, evolution, ai (artificial intelligence)




giovedì 27 aprile 2023

# gst: like the slender body theory, the effect of curvature on the diffusion of colloidal bananas.


<< Anisotropic colloidal particles exhibit complex dynamics which play a crucial role in their functionality, transport, and phase behavior.  >>️

AA << investigate the two-dimensional diffusion of smoothly curved colloidal rods—also known as colloidal bananas—as a function of their opening angle α >>️

<< the experimental results are consistent with slender body theory, indicating that the dynamical behavior of the particles arises primarily from their local drag anisotropy. These results highlight the impact of curvature on the Brownian motion of elongated colloidal particles, which must be taken into account when seeking to understand the behavior of curved colloidal particles. >>️

Justin-Aurel Ulbrich, Carla Fernández-Rico, et al. Effect of curvature on the diffusion of colloidal bananas. Phys. Rev. E 107, L042602. April 21, 2023.


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

Keywords: gst, colloids, particles, behavior




martedì 25 aprile 2023

# evol: gentle bonobos vs. aggressive chimps ...


<< Among the great apes, the chimpanzees and the bonobos are the most genetically related to us as we share about 98.7% of our DNA with them. >>️

<< So where exactly do humans stand? We seem to have incorporated the traits of both species, resulting in a tension between our aggressive and harmonious proclivities. Our tendency for conflict mirrors the competitiveness of chimpanzees, and yet the bonobos teach us that we have it in us to be altruistic and that society can be organised in more peaceful ways. This selflessness underlies the large-scale cooperation that has helped Homo sapiens share ideas, form nations, explore the universe and outlast other early humans such as Homo erectus. >>️

Jose Yong. Bonobos and chimps: what our closest relatives tell us about humans. theconversation.com. April 4, 2023. 


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

Keywords: evolution, chimps, bonobos,  chimpanzees, behavior


lunedì 24 aprile 2023

# gst: emergent organization and polarization due to active fluctuations.


AA << introduce and study a model of active Brownian motion with multiplicative noise describing fluctuations in the self-propulsion or activity. (They) find that the standard picture of density accumulation in slow regions is qualitatively modified by active fluctuations, as stationary density profiles are generally not determined only by the mean self-propulsion speed landscape. As a result, activity gradients generically correlate the particle self-propulsion speed and orientation, leading to emergent polarization at interfaces pointing either towards dense or dilute regions depending on the amount of noise in the system.  >>
Benoit Mahault, Prakhar Godara, Ramin Golestanian. Emergent organization and polarization due to active fluctuations. Phys. Rev. Research 5, L022012. April 12, 2023. 

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

Keywords: gst, particle, organization, polarization, fluctuations, noise, self-propulsion, self-assembly 



sabato 22 aprile 2023

# gst: when droplets are capable of self-propulsion as if they were surfing on a self-generated wave.


<< active droplets can move autonomously or oscillate between confining walls (..). Those behaviors could provide a clue about how life emerged from inanimate material. >>️

<< in the past decades, it has become clear that weak physical interactions among biomolecules are a crucial part of the answer. Such interactions allow some molecules to stay together transiently while avoiding others, which can lead to the spontaneous formation of droplets whose composition differs from their surroundings. Although biochemist Alexander Oparin suggested such ideas a century ago (..), experimental corroboration arrived only recently >>️

<< The key contribution of Demarchi and his collaborators is to demonstrate that droplet drift can enhance the heterogeneity of substrate and product. The resulting positive feedback allows droplets to move continuously as if they were surfing on a self-generated wave. >>️

David Zwicker. Droplets Come to Life. Physics 16, 45. Mar 20, 2023. 

AA << find that condensates move toward the center of a confining domain when this feedback is weak. Above a feedback threshold, they exhibit self-propulsion, leading to oscillatory dynamics. Moreover, catalysis-driven enzyme fluxes can lead to interrupted coarsening, resulting in equidistant condensate positioning, and to condensate division. >>
Leonardo Demarchi, Andriy Goychuk, et al. Enzyme-Enriched Condensates Show Self-Propulsion, Positioning, and Coexistence. Phys. Rev. Lett. 130, 128401. Mar 20, 2023.

Also

'drop', 'droplet', 'droploid', 'transition' in 

Keywords: gst, drop, droplet, waves, transition, liquid-liquid phase transition, nonequilibrium systems




sabato 15 aprile 2023

# gst: the physiological emergence and evolution of cell-spanning vortices (inside Drosophila oocytes).


<< Life in complex systems, such as cities and organisms, comes to a standstill when global coordination of mass, energy, and information flows is disrupted. Global coordination is no less important in single cells, especially in large oocytes and newly formed embryos, which commonly use fast fluid flows for dynamic reorganization of their cytoplasm. Here, (AA) combine theory, computing, and imaging to investigate such flows in the Drosophila oocyte, where streaming has been proposed to spontaneously arise from hydrodynamic interactions among cortically anchored microtubules loaded with cargo-carrying molecular motors. >>️

Sayantan Dutta, Reza Farhadifar, et al. Self-organized intracellular twisters. arXiv: 2304.02112v2 [physics.bio-ph].  Apr 6, 2023. 

Also

keyword 'vortex' in FonT

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

Keywords: gst, fluid dynamics, vortex, vortices, vortexes, vorticity,


venerdì 14 aprile 2023

# gst: even a single bubble can produce creative musical outcomes


<< Producing original and arranging existing musical outcomes is an art that takes years of learning and practice to master. Yet, despite the constant advances in the field of AI-powered musical creativity, production of quality musical outcomes remains a prerogative of the humans. Here we demonstrate that a single bubble in water can be used to produce creative musical outcomes, when it nonlinearly oscillates under an acoustic pressure signal that encodes a piece of classical music. >>️

Ivan S. Maksymov. Musical creativity enabled by nonlinear oscillations of a bubble in water. arXiv:2304.00822v1 [cs.SD]. Apr 3, 2023. 

keyword "bubble" in FonT

Keywords: gst, ai, fluid dynamics, bubble, sound, music, audio processing