# 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

# gst: the effects of order- disorder on a system of swarmalators that move on a one-dimensional ring.

<< Swarmalators are phase oscillators that cluster in space, like fireflies flashing on a swarm to attract mates. >>

<< In this work, (AA) explore the effects of disorder induced by phase frustration on a system of Swarmalators that move on a one-dimensional ring. >>

They find << numerically and analytically, the ordered and disordered states that emerge in the system. The active states, not present in the model without disorder, resemble states found previously in numerical studies for the 2D Swarmalators system. One of these states, in particular, shows similarities to turbulence generated in a flattened media. (AA) show that all ordered states can be generated for any values of the coupling constants by tuning the phase frustration parameters only. Moreover, many of these combinations display multi-stability. >>️

Joao U.F. Lizarraga, Marcus A.M. de Aguiar. Sakaguchi Swarmalators. arXiv: 2305.08615v1 [nlin.PS]. May 15, 2023. 

https://arxiv.org/abs/2305.08615

Also:  'swarm', 'turbulence', 'noise', 'particle' in: https://www.inkgmr.net/kwrds.html

Keywords: gst, swarm, turbulence, noise, particle