# gst: stochastic surfing turbulent vorticity.

<< The chaotic dynamics of small-scale vorticity plays a key role in understanding and controlling turbulence, with direct implications for energy transfer, mixing, and coherent structure evolution. >>

Here AA << use a combination of experiments, theory and simulations to show that small magnetic particles of different densities, exploring flow regions of distinct vorticity statistics, can act as effective probes for measuring and forcing turbulence at its smallest scale. The interplay between the magnetic torque, from an externally controllable magnetic field, and hydrodynamic stresses, from small-scale turbulent vorticity, reveals an extremely rich phenomenology. >>

Notably, AA << present the first observation of stochastic resonance for particles in turbulence: turbulent fluctuations, effectively acting as noise, counterintuitively enhance the particle rotational response to external forcing. (They) identify a pronounced resonant peak in particle rotational phase-lag when the applied magnetic field matches the characteristic intensity of small-scale vortices. >>

<< Furthermore, (They) uncover a novel symmetry-breaking mechanism: an oscillating magnetic field with zero-mean angular velocity remarkably induces net particle rotation in turbulence with zero-mean vorticity, as turbulent fluctuations aid the particle in "surfing" the magnetic field. >>

Ziqi Wang, Xander M. de Wit, et al. Stochastic surfing turbulent vorticity. arXiv: 2504.08346v1 [physics.flu-dyn]. Apr 11, 2025. 

https://arxiv.org/abs/2504.08346

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

Keywords: gst, vortices, turbulence, turbulent fluctuations, small-scale turbulent vorticity, stochastic resonance, noise, transitions 

# gst: stochastic adaptation, stochastic resonance.

<< Stochastic resonance is a phenomenon possessed by some nonlinear oscillators, in which a weak signal is boosted by noise. Both the monostable and bistable Duffing oscillators can exhibit this property. However, stochastic resonance has a strong frequency-dependence, as only a band of frequencies may be boosted by noise. >>️

<< Adaptive oscillators are a subset of nonlinear oscillators that can learn the features of an external force. (In this AA work), an adaptive state is added to a Duffing oscillator. This adaptive state enables the Duffing adaptive oscillator to outperform stochastic resonance over a wide range of frequencies by learning a resonance condition. >>️

Edmon Perkins. Comparison of stochastic adaptation and stochastic resonance. Phys. Rev. E 110, 064225. Dec 27, 2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.110.064225 

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

Keywords: gst, fluctuations, noise, transition, stochasticity, stochastic adaptation, stochastic resonance

# 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: to reach detectability of a weak signal, they add background noise

<< In contrast to most sensors, for which noise is a problem that should be suppressed, (AA) found that adding just the right amount of background noise can actually increase a signal too weak for sensing by normal sensors, to a level that can reach detectability. >>

Walt Mills. To make a better sensor, just add noise. Pennsylvania State University. Sep 03, 2020. 

https://phys.org/news/2020-09-sensor-noise.html   

<< In this article, (AA) adopt a radical approach for next generation ultra-low-power sensor design by embracing the evolutionary success of animals with extraordinary sensory information processing capabilities that allow them to survive in extreme and resource constrained environments. Stochastic resonance (SR) is one of those astounding phenomena, where noise, which is considered detrimental for electronic circuits and communication systems, plays a constructive role in the detection of weak signals. >>

Akhil Dodda, Aaryan Oberoi, et al. 

Stochastic resonance in MoS2 photodetector. Nat Commun 11, 4406 (2020). doi: 10.1038/ s41467-020-18195-0. Sep 2, 2020.

https://www.nature.com/articles/s41467-020-18195-0   

Also 

keyword 'noise' in FonT

https://flashontrack.blogspot.com/search?q=noise

Also 

plus ambiguity and noise. Notes. Jul 06, 2007  (quasi-stochastic poetry)

https://inkpi.blogspot.com/2007/07/2136-plus-ambiguity-and-noise.html

# gst: the hypothesis to optimize multiplicative noise to enhance a signal-to-noise ratio

AA << study simple integrate-and-fire type models with multiplicative noise and consider the transmission of a weak and slow signal, >>

<< The specific question of interest is whether and how the state-dependence of the noise can be optimized with respect to information transmission >>

<< also in a biophysically more relevant situation, multiplicative noise can enhance the signal-to-noise ratio (..) results shed light on a so far unexplored aspect of stochastic signal transmission in neural systems. >>

Jonathan Bauermann Benjamin Lindner. Multiplicative noise is beneficial for the transmission of sensory signals in simple neuron models. Biosystems. Volume 178, Apr 2019, Pages 25-31. doi: 10.1016/ j.biosystems.2019.02.002

https://www.sciencedirect.com/science/article/pii/S0303264718303861