# gst: noise as endogenous control

<< Systems biology faces the monumental task of synthesizing vast amounts of molecular facts into a cohesive whole. While it is recognized that stochasticity is ubiquitous in the cell, with noise playing a role in gene expression, differentiation, and switching (..), it is still commonly argued that the cell functions in spite of the noisy cellular environment. >>️

<< Stochastic systems have a control-theoretic interpretation in which noise plays the role of endogenous control. In the weak-noise limit, relevant at low temperatures or in large populations, control is optimal and an exact mathematical mapping from noise to control is described, where the maximizing the probability of a state becomes the control objective. >>

<< In Langevin dynamics noise is identified directly with control, while in general Markov jump processes, which include chemical reaction networks and electronic circuits, (AA) use the Doi-Zel'dovich-Grassberger-Goldenfeld-Peliti path integral to identify the `response' or `tilt' field π as control, which is proportional to the noise in the semiclassical limit. This solves the longstanding problem of interpreting π. >>

AA << illustrate the mapping on multistable chemical reaction networks and systems with unstable fixed points. The noise-control mapping builds intuition for otherwise puzzling phenomena of stochastic systems: why the probability is generically a non-smooth function of state out of thermal equilibrium; why biological mechanisms can work better in the presence of noise; and how agentic behavior emerges naturally without recourse to mysticism. >>

Eric De Giuli. Noise equals endogenous control. arXiv: 2503.15670v2 [q-bio.MN]. Mar 24, 2025.

https://arxiv.org/abs/2503.15670

Also: noise, disorder & fluctuations, transition, dance, jazz, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, noise, disorder, transition, ethno, crosstalk, gossip, misinformation, fake news, dance, jazz

# gst: odd electrical circuits

<< Non-reciprocal interactions in elastic media give rise to rich non-equilibrium behaviors, but controllable experimental realizations of such odd elastic phenomena remain scarce. Building on recent breakthroughs in electrical analogs of non-Hermitian solid-state systems, (AA) design and analyze scalable odd electrical circuits (OECs) as exact analogs of an odd solid. >>

AA << show that electrical work can be extracted from OECs via cyclic excitations and trace the apparent energy gain back to active circuit elements. (They) show that OECs host oscillatory modes that resemble recent experimental observations in living chiral crystals and identify active resonances that reveal a perspective on odd elasticity as a mechanism for mechanical amplification. >>️

Harry Walden, Alexander Stegmaier, et al. Odd electrical circuits. arXiv: 2503.14383v1 [cond-mat.soft]. Mar 18, 2025.

https://arxiv.org/abs/2503.14383

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

Keywords: gst, chirality, chiral crystals, chiral oscillations, chiral waves, oddity, odd elastic materials

# gst: droplet bag formation in turbulent airflows.

AA << present numerical simulations investigating the evolution of liquid droplets into baglike structures in turbulent airflows. The droplet bag breakup problem is of significance for many multiphase processes in scientific and engineering applications. Turbulent fluctuations are introduced synthetically into a mean flow, and the droplet is inserted when the air-phase turbulence reaches a statistically stationary state. The morphological evolution of the droplet under different turbulence configurations is retrieved and analyzed in comparison with laminar aerobreakup results. While the detailed evolution history of individual droplets varies widely between different realizations of the turbulent flow, common dynamic and morphological evolution patterns are observed. >>

<< The presence of turbulence is found to enhance the drag coefficient of the droplet as it flattens. At late times, the droplet becomes tilted and increasingly corrugated under strong turbulence intensity. (AA) quantify these phenomena and discuss their possible governing mechanisms associated with turbulence intermittency. >>

<< Lastly, the influences of liquid-gas viscosity ratio are examined and the implications of air-phase turbulence on the later bag film breakup process are discussed. >>️

Kaitao Tang, Thomas A. A. Adcock, Wouter Mostert. Droplet bag formation in turbulent airflows. Phys. Rev. Fluids 10, 033604. March 19, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.033604

Also: drop, droplet, droploid, turbulence, fluctuations, intermittency, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drop, droplet, droploid, turbulence, fluctuations, intermittency

# gst: from alternating stripes to alternating labyrinths, the Belousov−Zhabotinsky transition

<< Alternating (temporally period-2) stripes and labyrinths have been observed in media of chemical and biochemical reactions; however, the mechanisms underlying the formation of these spatiotemporal patterns remain unclear. >>

AA << conduct computer simulation using a modified model of Belousov−Zhabotinsky reaction that incorporates a global feedback loop with a spatial strength profile of Gaussian distribution. The simulation results demonstrate that the transition from alternating stripes to alternating labyrinths occurs when the feedback is negative with a certain width of the Gaussian function. (AA) add the same Gaussian-weighted feedback loop to an amplitude equation to describe the amplitude dynamics of the period-2 oscillation and show that the pattern dynamics of the Belousov−Zhabotinsky reaction can be well captured by this amplitude equation. >>

<< Analyses of the amplitude equation demonstrate that the transition from stripes to labyrinths arises from the transverse instabilities of bistable fronts caused by the Gaussian-weighted negative global feedback. >>️

Chunli Huang, Zhen Song, Zhilin Qu. Transition from alternating stripes to alternating labyrinths in oscillatory media. Phys. Rev. E 111, L032201. Mar 13, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.L032201

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

Also: Orologio chimico. Notes (quasi-stochastic poetry). Apr 08, 2005.

https://inkpi.blogspot.com/2005/04/1558-orologio-chimico.html  

Keywords: gst, transitions, BZ reaction, labyrinths, alternating labyrinths

# gst: First-passage-time statistics of active Brownian particles: a perturbative approach.

AA << study the first-passage-time (FPT) properties of active Brownian particles to reach an absorbing wall in two dimensions. Employing a perturbation approach (They) obtain exact analytical predictions for the survival and FPT distributions for small Péclet numbers, measuring the importance of self-propulsion relative to diffusion. >>

<< While randomly oriented active agents reach the wall faster than their passive counterpart, their initial orientation plays a crucial role in the FPT statistics. Using the median as a metric, (AA) quantify this anisotropy and find that it becomes more pronounced at distances where persistent active motion starts to dominate diffusion. >>️

Yanis Baouche, Magali Le Goff, et al. First-passage-time statistics of active Brownian particles: a perturbative approach. arXiv: 2503.05401v1 [cond-mat.soft]. Mar 7, 2025.

https://arxiv.org/abs/2503.05401

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

Keywords: gst, particles, active particles, perturbation approach, randomness, stochasticity, stochastic resetting, rotational diffusion, anisotropy

# poe: onda di gioco

<<  

Nota a far mescole coll' endogeno docile avo melode /

declamando su traccia nevale di dondolio di geco /

l' evento d' onde nella forma di compressa logica ode /

che, se liberata, s' autoespande in frange d' agile eco.

>>

14.31 13/09/2004

'solebat quid esset litus ita definire: "qua fluctus eluderet"'. In: Cicerone. 'de natura deorum'.

https://inkpi.blogspot.com/2005/03/1782-onda-di-gioco.html  

Anche:  waves, in   

Notes (quasi-stochastic poetry)  https://inkpi.blogspot.com/search?q=onda 

FonT  https://flashontrack.blogspot.com/search?q=waves 

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

Anche: World Poetry Day, in

 https://en.m.wikipedia.org/wiki/World_Poetry_Day     https://nationaltoday.com/world-poetry-day

Keywords: poe, poetry, quasi-stochastic poetry, PoetryDay, WorldPoetryDay, InternationalPoetryDay, waves, rogue waves, shock waves, solitons, turbulence, instability

# aibot: I think, therefore I hallucinate: minds, machines, and the art of being wrong.

<< This theoretical work examines 'hallucinations' in both human cognition and large language models, comparing how each system can produce perceptions or outputs that deviate from reality. Drawing on neuroscience and machine learning research, (AA) highlight the predictive processes that underlie human and artificial thought. >>

<< In humans, complex neural mechanisms interpret sensory information under uncertainty, sometimes filling in gaps and creating false perceptions. This inference occurs hierarchically: higher cortical levels send top-down predictions to lower-level regions, while mismatches (prediction errors) propagate upward to refine the model. LLMs, in contrast, rely on auto-regressive modeling of text and can generate erroneous statements in the absence of robust grounding. >>

<< Despite these different foundations - biological versus computational - the similarities in their predictive architectures help explain why hallucinations occur. (AA) propose that the propensity to generate incorrect or confabulated responses may be an inherent feature of advanced intelligence. In both humans and AI, adaptive predictive processes aim to make sense of incomplete information and anticipate future states, fostering creativity and flexibility, but also introducing the risk of errors. (Their) analysis illuminates how factors such as feedback, grounding, and error correction affect the likelihood of 'being wrong' in each system. (AA) suggest that mitigating AI hallucinations (e.g., through improved training, post-processing, or knowledge-grounding methods) may also shed light on human cognitive processes, revealing how error-prone predictions can be harnessed for innovation without compromising reliability. By exploring these converging and divergent mechanisms, the paper underscores the broader implications for advancing both AI reliability and scientific understanding of human thought. >>️

Sebastian Barros. I Think, Therefore I Hallucinate: Minds, Machines, and the Art of Being Wrong. arXiv: 2503.05806v1 [q-bio.NC]. 4 Mar 4, 2025.

https://arxiv.org/abs/2503.05806

Also: brain, curiosity, novelty, uncertainty, error, mistake, jazz, ai (artificial intell), in https://www.inkgmr.net/kwrds.html 

Keywords: brain, cognition, perceptions, curiosity, novelty, hallucinations, errors, prediction, prediction errors, error-prone predictions, AI, artificial intelligence, LLMs