# gst: intricate transitions in elastoactive structures.

<< The interplay between activity and elasticity often found in active and living systems triggers a plethora of autonomous behaviors ranging from self-assembly and collective motion to actuation. Among these, spontaneous self-oscillations of mechanical structures is perhaps the simplest and most widespread type of nonequilibrium phenomenon. >>️

<< Here, (AA) introduce a centimeter-sized model system for one-dimensional elastoactive structures. >>️

<< such structures exhibit flagellar motion when pinned at one end, self-snapping when pinned at two ends, and synchronization when coupled together with a sufficiently stiff link. (..) these transitions can be described quantitatively by simple models of coupled pendula with follower forces. >>️

Ellen Zheng, Martin Brandenbourger, et al. Self-Oscillation and Synchronization Transitions in Elastoactive Structures. Phys. Rev. Lett. 130, 178202. April 25, 2023. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.130.178202

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

Keywords: gst, transition, particle, self-assembly, elastic, pendulum

# jazz: when turbulence underneath it and on top of it.

<< The album title comes from poet and scholar Fred Moten, who described Gamedze's drumming in the internet forum Poesis as an "amazing interplay between turbulence and pulse. Pulse is supposed to regulate and also be regular, but the turbulence underneath it and on top of it, it's just extraordinary." >>️

Thom Jurek. Turbulence and Pulse. allmusic.com. May 5, 2023. 

https://www.allmusic.com/album/turbulence-and-pulse-mw0003947563?1684082977357 

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

Keywords: jazz, turbulence

# gst: the robustness of a edge spiking.

<< Excitable media, ranging from bioelectric tissues and chemical oscillators to forest fires and competing populations, are nonlinear, spatially extended systems capable of spiking. Most investigations of excitable media consider situations where the amplifying and suppressing forces necessary for spiking coexist at every point in space. In this case, spiking requires a fine-tuned ratio between local amplification and suppression strengths. But, in Nature and engineered systems, these forces can be segregated in space, forming structures like interfaces and boundaries. Here, (AA) show how boundaries can generate and protect spiking if the reacting components can spread out: even arbitrarily weak diffusion can cause spiking at the edge between two non-excitable media. This edge spiking is a robust phenomenon that can occur even if the ratio between amplification and suppression does not allow spiking when the two sides are homogeneously mixed. >> ️

Colin Scheibner, Hillel Ori, et al. Spiking at the edge. arXiv:2304.06940v1 [cond-mat.soft]. Apr 14, 2023. 

https://arxiv.org/abs/2304.06940  

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

Keywords: gst, excitable media, weak, spike, edge spiking  

# gst: to find a separation between plunging and spilling wave breakers

<< While understanding breaking waves is crucial for the development of parametrizations used in ocean wave modeling for both deep and shallow water, the complete process of wave breaking is not well understood. Here (AA) present direct numerical simulations of two-dimensional solitary waves that shoal and break on a uniform beach in shallow water, with the presence of storm surge represented by an inshore region. >>️

They << classify wave breaker types and find a separation between plunging and spilling breakers when scaled by breaking amplitude and depth. (AA) compare energy dissipation during the breaking process with results from the literature without storm surge.  >>️

They << conclude that a previously developed shallow-water inertial dissipation model for wave breaking on a uniform slope can be extended to this storm surge environment with good data collapse, and further discuss possibilities for a general parametrization of wave breaking valid across different depth regimes. >>️

Hunter Boswell, Guirong Yan, Wouter Mostert. Characterizing energy dissipation of shallow-water wave breaking in a storm surge. Phys. Rev. Fluids 8, 054801. May 5, 2023. 

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.054801

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

Keywords: gst, waves, soliton, drop 

# life: exponential post-Donald (without Donald), how AI could interfere (drive) next political elections.

<< Recent news that the Republican National Committee (RNC) has used an AI-generated video to criticize Joe Biden shows how likely AI is to transform our upcoming elections. >>️

<< Through templates that are easy and inexpensive to use, we are going to face a Wild West of campaign claims and counter-claims, with limited ability to distinguish fake from real material and uncertainty regarding how these appeals will affect the election. >>️

<< In the coming year, response times may drop to minutes, not hours or days. AI can scan the internet, think about strategy, and come up with a hard-hitting appeal. >>️

<< AI provides an inexpensive way to generate instant responses without having to rely on highly-paid consultants or expert videographers. >>️

<< AI enables very precise audience targeting, which is crucial in political campaigns. >>️

<< AI likely will democratize disinformation by bringing sophisticated tools to the average person interested in promoting their preferred candidates as well. People no longer must be coding experts or video wizards to generate text, images, video, or programs. They don’t necessarily have to work for a troll farm to create havoc with the opposition. They can simply use advanced technologies to spread the messages they want. In that sense, anyone can become a political content creator and seek to sway voters or the media. >>️

Darrell M. West. How AI will transform the 2024 elections. May 3, 2023.

https://www.brookings.edu/blog/techtank/2023/05/03/how-ai-will-transform-the-2024-elections/

Also: 'ai', 'analogy', 'Potus', 'RAG-time', 'CTZ', 'Donald' in https://www.inkgmr.net/kwrds.html

Keywords: life, ai, analogy, potus, RAG, CTZ, Donald

# gst: nematic order condensation and topological defects in inertial active nematics

<< Living materials at different length scales manifest active nematic features such as orientational order, nematic topological defects, and active nematic turbulence. Using numerical simulations (AA) investigate the impact of fluid inertia on the collective pattern formation in active nematics. >>️

<< an incremental increase in inertial effects due to reduced viscosity results in gradual melting of nematic order with an increase in topological defect density before a discontinuous transition to a vortex-condensate state. The emergent vortex-condensate state at low enough viscosities coincides with nematic order condensation within the giant vortices and the drop in the density of topological defects. (AA) further show flow field around topological defects is substantially affected by inertial effects. (..) no evidence of universal scaling at higher viscosities. >>

️

Roozbeh Saghatchi, Mehmet Yildiz, Amin Doostmohammadi. Nematic order condensation and topological defects in inertial active nematics. Phys. Rev. E 106, 014705. July 25, 2022.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.106.014705

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

Keywords: gst, behavior, collective behavior, patterns, turbulence, nematic turbulence, viscosity, vortex, defect, drop

# gst: riddles of the sphinx tilings, when at low temperatures you could find a chiral order.

<< The sphinx tile, a hexiamond composed of six equilateral triangles in the shape of a sphinx, has interesting and complex tiling behavior due to its chirality and asymmetry. >>️

<< for larger frames (AA) introduce a Monte Carlo (MC) method to create randomized tilings. Key to the latter is the identification of fundamental shapes ("polyads") that have multiple tilings and allow a rejection-free MC move once the polyad is identified. >>

AA << also introduce an Ising-like chiral interaction energy between neighboring sphinx tiles and study how the system behaves as a function of temperature; at low temperatures, chiral ordering is found. >>️

Greg Huber, Craig Knecht, Walter Trump, Robert M. Ziff. Riddles of the sphinx tilings. arXiv: 2304.14388v2 [cond-mat.stat-mech]. May 1, 2023.

https://arxiv.org/abs/2304.14388

Also: 'chiral', 'disorder' in https://www.inkgmr.net/kwrds.html

Keywords: gst, sphinx, sphinx tiles, chirality, asymmetry