# gst: apropos of random walks, intermittent random walks under stochastic resetting

AA << analyze a one-dimensional intermittent random walk on an unbounded domain in the presence of stochastic resetting. In this process, the walker alternates between local intensive search, diffusion, and rapid ballistic relocations in which it does not react to the target. >>

AA << demonstrate that Poissonian resetting leads to the existence of a non-equilibrium steady state. (They) calculate the distribution of the first arrival time to a target along with its mean and show the existence of an optimal reset rate. In particular, (..) the initial condition of the walker, i.e., either starting diffusely or relocating, can significantly affect the long-time properties of the search process. >>

<< the presence of distinct parameter regimes for the global optimization of the mean first arrival time when ballistic and diffusive movements are in direct competition. >>️

Rosa Flaquer-Galmes, Daniel Campos,  Vicenc Mendez. Intermittent random walks under stochastic resetting. Phys. Rev. E 109, 034103. March 4, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.034103  

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

Keywords: gst, walk, intermittent random walk, stochasticity, stochastic resetting

# evol: the hypothesis of quasi-stochastic 'jazzy' metamechanics of biological evolution (in Arabidopsis thaliana)

<< Mutations occur when DNA is damaged and left unrepaired, creating a new variation. The scientists wanted to know if mutation was purely random or something deeper. What they found was unexpected. >>️

<< We always thought of mutation as basically random across the genome, (..) It turns out that mutation is very non-random and it's non-random in a way that benefits the plant. It's a totally new way of thinking about mutation. >> Grey Monroe. ️

Study challenges evolutionary theory that DNA mutations are random. UC Davis. Jan 12, 2022.

https://phys.org/news/2022-01-evolutionary-theory-dna-mutations-random.html

Monroe JG, Srikant T, et al. Mutation bias reflects natural selection in Arabidopsis thaliana. Nature. doi: 10.1038/ s41586-021-04269-6. Jan 12, 2022.

https://www.nature.com/articles/s41586-021-04269-6

FonT 

for a long time I have developed the suspicion that the small plant cared for by grandmother on the windowsill could be a not trivial image of (r)evolution ... 

The three ways of the plastoquinone inside the photosystem II complex. May 23, 2017.

https://flashontrack.blogspot.com/2017/05/s-phyto-three-ways-of-plastoquinone.html

Also

keyword 'evolution'  in FonT

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

keyword 'evolution' | 'evoluzione'  in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=evolution

https://inkpi.blogspot.com/search?q=evoluzione

keyword 'jazz' in FonT

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

keyword 'jazz' in Notes (quasi-stochastic poetry):

https://inkpi.blogspot.com/search?q=jazz

keywords: evol, dna, mutations, randomness, quasi-stochasticity, jazz

# gst: random walk model for dual cascades in wave turbulence.

<< Dual cascades in turbulent systems with two conserved quadratic quantities famously arise in both two-dimensional hydrodynamic turbulence and also in wave turbulence based on four-wave interactions. >>

<< in wave turbulence the systematic spectral fluxes observed in a dual cascade do not require an irreversible dynamical mechanism, rather, they arise as the inevitable outcome of blind chance. >>️️

Oliver Bühler. Random walk model for dual cascades in wave turbulence. Phys. Rev. E 109, 055102. May 1, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.055102

Also: waves, turbulence, random, weak, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, turbulence, weak turbulence, random, random walks

# gst: apropos of weakly coupled oscillators, a new approach to depict about their spontaneous stochastic activities

<<  Many systems in physics, chemistry and biology exhibit oscillations with a pronounced random component. Such stochastic oscillations can emerge via different mechanisms, for example linear dynamics of a stable focus with fluctuations, limit-cycle systems perturbed by noise, or excitable systems in which random inputs lead to a train of pulses. Despite their diverse origins, the phenomenology of random oscillations can be strikingly similar. >>

<< Here (AA) introduce a nonlinear transformation of stochastic oscillators to a new complex-valued function Q∗1(x) that greatly simplifies and unifies the mathematical description of the oscillator's spontaneous activity, its response to an external time-dependent perturbation, and the correlation statistics of different oscillators that are weakly coupled. >>

AA << approach makes qualitatively different stochastic oscillators comparable, provides simple characteristics for the coherence of the random oscillation, and gives a framework for the description of weakly coupled oscillators. >>️

Alberto Pérez-Cervera, Boris Gutkin, et al. A Universal Description of Stochastic Oscillators. arXiv: 2303.03198v1 [nlin.AO]. Feb 27, 2023. 

https://arxiv.org/abs/2303.03198

Also

'oscillations' in FonT

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

Keywords: gst, oscillations, random oscillations, weakly coupled oscillators

# gst: apropos of transitions, randomness can stabilize edge states in short- lifetime regions of disordered periodically-driven systems

<< lifetimes of the edge states exhibit universal behavior when random potentials exist since the edge- and bulk- dominant eigenstates are mixed, leading to that lifetimes are prolonged by random potentials in the region II (short- lifetime region) and shortened in the region I (long- lifetime region). >>

<<  it is an intriguing phenomenon that random potentials tend to stabilize edge states in the region II (short- lifetime regions). >>

Ken Mochizuki, Kaoru Mizuta, Norio Kawakami. Fate of Topological Edge States in Disordered Periodically-driven Nonlinear Systems. arXiv: 2108.00649 (nlin). Aug 2, 2021.

https://arxiv.org/abs/2108.00649

Also

keyword 'random' in FonT

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

keyword 'disorder' in FonT

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

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

https://inkpi.blogspot.com/search?q=disordine

# gst: random walk to describe a interplay between the inter-chain hopping and the intra-chain hopping in amorphous Polyimide nanofibers

AA << report the observation of a crossover of heat conduction behavior from three dimensions (3D) to quasi-one dimension (1D) in Polyimide(PI) nanofibers at a given temperature. A theoretical model based on the random walk theory has been proposed to quantitatively describe the interplay between the inter-chain hopping and the intra-chain hopping in nanofibers. This model explains well the diameter dependence of thermal conductivity and also speculates the upper limit of thermal conductivity of amorphous polymers in the quasi-1D limit. >>

Lan Dong, Qing Xi, et al. Dimensional crossover of heat conduction in amorphous Polyimide nanofibers. National Science Review. nwy004.  doi: 10.1093/nsr/nwy004. Jan 09,  2018.

https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwy004/4794956

<< The intrinsic structure of amorphous polymers is highly disordered with long, entangled molecular chains >>

Science China Press. "Random walk" of heat carriers in amorphous polymers. Mar 01, 2018.

https://m.phys.org/news/2018-03-random-carriers-amorphous-polymers.html

gst: actually and counterintuitively a coherent jump could generate disorder.

AA << consider a quantized version of a model for “random walk in random environment.” (..) For a ring geometry (a chain with periodic boundary condition) it features a delocalization-transition as the bias in increased beyond a critical value, indicating that the relaxation becomes underdamped. Counterintuitively, the effective disorder is enhanced due to coherent hopping. >>

Ben Avnit, Doron Cohen. Quantum walk in stochastic environment. Phys. Rev. E 108, 054111. Nov 7, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.054111

Also:  Voli a casaccio. Notes (quasi-stochastic poetry). Oct 01, 2006.

https://inkpi.blogspot.com/2006/10/2066-voli-casaccio.html

Also: 'random', 'transition', 'disorder', 'chaos', in https://www.inkgmr.net/kwrds.html

Keywords: gst, walk, random walk, quantum walk, qu-walk, jump, transition, disorder, chaos

# gst: apropos of transitions, scrambling trajectories in a radiative random unitary circuit.

AA << study quantum information scrambling in a random unitary circuit that exchanges qubits with an environment (..). As a result, initially localized quantum information  not only spreads within the system, but also spills into the environment. >>

<< The transition is also easily extended to higher dimensions, where higher-dimensional DP (directed percolation) universality classes will control the critical behavior. >>

<<  The transition in operator spreading  coincides with an information-theoretic 3 transition, which can be framed by  viewing (AA) circuit as a toy model for an evaporating black hole (..). >>️

<< Depending on the initial state of the swapped-in qubits, (AA) observe a corresponding entanglement transition in the coherent information into the environment. >>

️

Zack Weinstein, Shane P. Kelly, Jamir Marino, Ehud Altman. Scrambling Transition in a Radiative Random Unitary Circuit. arXiv:2210.14242v1 [quant-ph]. Oct 25, 2022.

https://arxiv.org/abs/2210.14242

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

Keywords: transition, quantum information, entanglement transition, scrambling, directed percolation

# gst: Parrondo paradox revisited, a chaotic switching approach

<< Parrondo's paradox is a phenomenon where the switching of two losing games results in a winning outcome. >>

<< Suppose I present to you the outcome of the quantum walker at the end of 100 coin tosses, knowing the initial position, can you tell me the sequence of tosses that lead to this final outcome?" (..) In the case of random switching, it is almost impossible to determine the sequence of tosses that lead to the end result. However, for periodic tossing, we could get the sequence of tosses rather easily, because a periodic sequence has structure and is deterministic. >> Joel Lai.

<< This led to the idea of incorporating chaotic sequences as a means to perform the switching. The authors discovered that using chaotic switching through a pre-generated chaotic sequence significantly enhances the work. For an observer who does not know parts of the information required to generate the chaotic sequence, deciphering the sequence of tosses is analogous to determining a random sequence. However, for an agent with information on how to generate the chaotic sequence, this is analogous to a periodic sequence. According to the authors, this information on generating the chaotic sequence is likened to the keys in encryption. >>

Using quantum Parrondo's random walks for encryption. Singapore University of Technology and Design. Oct15, 2021.

https://phys.org/news/2021-10-quantum-parrondo-random-encryption.html

Joel Weijia Lai, Kang Hao Cheong. Chaotic switching for quantum coin Parrondo's games with application to encryption. Phys. Rev. Research 3, L022019. June 2, 2021. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.3.L022019

Also

<< usando l'output di una logistica (per certi valori dei parms) un ipotetico Donald potrebbe avere il vezzo di ottenere stessi risultati con serialita' numerica generata meccanicamente anziche' in modalita' casuale; >>️

#POTUS race: Donald, what he can do (with less than four lines ...). FonT. May 23, 2016. 

https://flashontrack.blogspot.com/2016/05/p-usa-potus-race-donald-what-he-can-do.html

Also

keyword 'parrondo' in FonT

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

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

https://inkpi.blogspot.com/search?q=parrondo

Also

keyword 'chaos' | 'chaotic' in Font

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

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

keyword 'caos' | 'caotico' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=caos

https://inkpi.blogspot.com/search?q=caotico

keywords: gst, games, life, chaos, Parrondo, Parrondo chaotic switching approach

# gst: apropos of transitions: effects of random waves interacting with a coherent structure

<< Solitary waves interacting with random (..) waves (..) are studied. Two opposing types of dynamics are identified: First, the random thermal waves can erode the solitary wave; second, this structure can grow as a result of this interaction. These two types of behavior depend on a dynamical property of the solitary wave (its angular frequency), and on a statistical property of the thermal waves (the chemical potential). >>

<< Either process leads to an increase of the wave entropy. >>

Yuanting Chen, Benno Rumpf. Growth or decay of a coherent structure interacting with random waves. Phys. Rev. E 104, 034213. Sep 15, 2021.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.104.034213

Also

keyword 'waves' in FonT

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

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

https://inkpi.blogspot.com/search?q=onda

# gst: irregular sampling design to address behaviours

<< Animal movement studies have become ubiquitous in animal ecology for the estimation of space use and the analysis of movement behavior. In these studies, animal movement data are primarily collected at regular time intervals. (AA) propose an irregular sampling design that could lead to greater efficiency and information gain in animal movement studies. (The) novel sampling design, called lattice and random intermediate point (LARI), combines samples at regular and random time intervals. >>

<<  in each of the data and simulation examples explored in this paper, LARI sampling results in more accurate and precise parameter estimation and, thus, better prediction of missing data as well.  >>

Elizabeth Eisenhauer,  Ephraim Hanks. A lattice and random intermediate point sampling design for animal movement. Environmetrics. doi: 10.1002/env.2618. Jan 3, 2020.

https://onlinelibrary.wiley.com/doi/abs/10.1002/env.2618

Gail McCormick. Including irregular time intervals improves animal movement studies. Pennsylvania State University. Jan 15, 2020.

https://m.phys.org/news/2020-01-irregular-intervals-animal-movement.html

Also

keyword "pause" in Notes

https://inkpi.blogspot.com/search?q=pause

keyword "pause" in FonT

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

# gst: apropos of "Anomalous Diffusion"

<< Consider a chaotic dynamical system generating diffusionlike Brownian motion. Consider a second, nonchaotic system in which all particles localize. Let a particle experience a random combination of both systems by sampling between them in time. What type of diffusion is exhibited by this random dynamical system?  >>

Yuzuru Sato and Rainer Klages. Anomalous Diffusion in Random Dynamical Systems. Phys. Rev. Lett. 122, 174101 doi: 10.1103/PhysRevLett.122.174101 Apr 29, 2019.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.174101  

# gst: the generation of waves by random point sets

<< amorphous Chern insulators can be readily constructed from arbitrary underlying structures, including hyperuniform, jammed, quasi-crystalline and uniformly random point sets >>

Noah P. Mitchell, Lisa M. Nash, et al.  Amorphous topological insulators constructed from random point sets.
Nature Physics (2018)
doi: 10.1038/s41567-017-0024-5.
Jan 15, 2018

https://www.nature.com/articles/s41567-017-0024-5

<< You don't have to be perfectly organized to pull off a wave >>

Gyroscopes lead scientists to unusual state of matter in a disorganized structure. Jan 15, 2018.

https://m.phys.org/news/2018-01-gyroscopes-scientists-unusual-state-disorganized.html  

# gst: small-scale random perturbations, Arnold's cat spontaneously stochastic

<< Multi-scale systems (..) may possess a fascinating property of spontaneous stochasticity: a small-scale initial uncertainty develops into a randomly chosen largescale state in a finite time, and this behavior is not sensitive to the nature and magnitude of uncertainty (..). >>

A << intriguing form is the Eulerian spontaneous stochasticity (ESS) of the velocity field itself: an infinitesimal small-scale noise triggers stochastic evolution of velocity field at finite scales and times. >>

AA << prove that a formally deterministic system with scaling symmetry yields a stochastic process with Markovian properties if it is regularized with a vanishing small-scale random perturbation. Besides its significance for understanding turbulence, (their) model extends the phenomenon of ESS beyond the scope of fluid dynamics: (AA) discuss a prototype of a feasible experiment for observing ESS in optics or electronics, as well as potential applications in other physical systems.>>

Alexei A. Mailybaev, Artem Raibekas. Spontaneously stochastic Arnold's cat. arXiv:2111.03666v1 [nlin.CD]. Nov 5,  2021.

https://arxiv.org/abs/2111.03666

keywords: gst, Arnold's cat, randomness, stochasticity, spontaneous stochasticity, small-scale random perturbations, noise, turbulence, chaos 

# s-math: hijacking news: unexpected, surprisingly erratic biases inside PI

<< the distribution of the last digit of prime numbers are not as random as has been thought, which suggests prime's themselves are not >>

Bob Yirka. Mathematician pair find prime numbers aren't as random as thought. March 15, 2016

http://m.phys.org/news/2016-03-mathematician-pair-prime-random-thought.html

Robert J. Lemke Oliver, Kannan Soundararajan. Unexpected biases in the distribution of consecutive primes, arXiv:1603.03720 [math.NT]

http://arxiv.org/abs/1603.03720

# s-gst: Lévy flight hypothesis, not only for predation ...

<< When sharks and other ocean predators can’t find food, they abandon Brownian motion, the random motion seen in swirling gas molecules, for Lévy flight — a mix of long trajectories and short, random movements found in turbulent fluids [1] >>

<<  Lévy flights interspersed with Brownian motion can describe the animals' hunting patterns. Birds and other animals (including humans) [2] follow paths that have been modeled using Lévy flight (e.g. when searching for food).[3] >>

<< (..) a growing body of research on generative mechanisms suggests that Lévy walks can arise freely as by-products of otherwise innocuous behaviours; consequently their advantageous properties are purely coincidental. This suggests that the Lévy flight foraging hypothesis should be amended, or even replaced, by a simpler and more general hypothesis. This new hypothesis would state that 'Lévy walks emerge spontaneously and naturally from innate behaviours and innocuous responses to the environment but, if advantageous, then there could be selection against losing them'.  [4] >>

[1] - https://en.m.wikipedia.org/wiki/L%C3%A9vy_flight

[2] - Reynolds, Gretchen (January 1, 2014). "Navigating Our World Like Birds and some authors have claimed that the motion of bees". The New York Times.

http://well.blogs.nytimes.com/2014/01/01/navigating-our-world-like-birds-and-bees/?_r=0

[3] - Sims, David W., Reynolds, Andrew M. et al.  "Hierarchical random walks in trace fossils and the origin of optimal search behavior". Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1405966111. Retrieved 16 July 2014.

http://m.pnas.org/content/111/30/11073.abstract

[4] - Reynolds A. Liberating Lévy walk research from the shackles of optimal foraging. Review article. Phys Life Rev. 2015.

http://www.ncbi.nlm.nih.gov/m/pubmed/25835600/?i=5&from=/26205677/related

# gst: true randomness exists

<< On a good day, the machine produces 1,024 bits of data every 10 minutes, equivalent to typing 13 letters per minute. But it promises what even monkeys on typewriters can’t: completely random text >>

<< It's exciting to be able to say that randomness exists in the universe >> Peter Bierhorst.

Sophia Chen. Quantum Mechanics Could Solve Cryptography’s Random Number Problem. Apr 11, 2018.

https://www.wired.com/story/quantum-mechanics-could-solve-cryptographys-random-number-problem/

Peter Bierhorst, Emanuel Knill, et al. Experimentally generated randomness certified by the impossibility of superluminal signals. Nature. 2018; 556: 223–6. doi: 10.1038/s41586-018-0019-0. Apr 11, 2018.

https://www.nature.com/articles/s41586-018-0019-0

# behav: 'run and tumble' behavior (among bacteria)

<< Bacteria in groundwater move in surprising ways. They can passively ride flowing groundwater, or they can actively move on their own in what scientists call "run and tumble" behavior.  >>

AA << noted a distinct run (movement in one direction) followed by a tumble (a sudden, random change in direction). By calculating the length and timing of these movements, they could develop a simple Continuous Time Random Walk (CTRW) model to predict how the bacteria would move. When compared to current models for bacterial remediation, the CTRW model was better at predicting bacterial transport in many circumstances. The CTRW model is the first step in developing and testing new reactive transport models that incorporate bacterial transport behavior.  >>

Rishi Parashar. Calculating 'run and tumble' behavior of bacteria in groundwater. Environmental Molecular Sciences Laboratory. Oct 31, 2019. 

https://m.phys.org/news/2019-10-behavior-bacteria-groundwater.html  

Xueke Yang, Rishi Parashar, et al. On Modeling Ensemble Transport of Metal Reducing Motile Bacteria. Scientific Reports volume 9, Article number: 14638. Oct 10, 2019. 

https://www.nature.com/articles/s41598-019-51271-0

# gst: even tight-binding billiards could exhibit chaotic behaviors

<< Recent works have established universal entanglement properties and demonstrated validity of single-particle eigenstate thermalization in quantum-chaotic quadratic Hamiltonians. However, a common property of all quantum-chaotic quadratic Hamiltonians studied in this context so far is the presence of random terms that act as a source of disorder. >>

AA << introduce tight-binding billiards in two dimensions, which are described by non-interacting spinless fermions on a disorder-free square lattice subject to curved open boundaries. >>

They <<  show that many properties of tight-binding billiards match those of quantum-chaotic quadratic Hamiltonians (..) these properties indeed appear to be consistent with the emergence of quantum chaos in tight-binding billiards. This statement nevertheless needs to be taken with some care since there exist a sub-extensive (in lattice volume) set of single-particle eigenstates that are degenerate in the middle of the spectrum at zero energy (i.e., zero modes), for which the agreement with RMT (random matrix theory) predictions may not be established. >>

Iris Ulcakar, Lev Vidmar. Tight-binding billiards. arXiv:2206.07078v1 [cond-mat.stat-mech]. Jun 14, 2022. 

https://arxiv.org/abs/2206.07078

Also

keyword 'billiard' in FonT

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

keyword 'chaos' | 'chaotic' in Font

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

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

keyword 'caos' | 'caotico' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=caos

https://inkpi.blogspot.com/search?q=caotico

keywords: gst, billiard, chaos, chaotic behavior

# gst: when randomly-timed external impulses can synchronize

<< Random perturbations applied in tandem to an ensemble of objects can synchronize their motion. (AA) study multiple copies of an object in periodic motion such as a firing neuron, each with an arbitrary phase. Randomly-timed external impulses can synchronize these phases. For impulses slightly too strong to synchronize, (they) find remarkable erratic synchronization, with stochastic fluctuations from near-perfect to more random synchronization. The sampled entropies of these phase distributions themselves form a steady-state ensemble. A stochastic dynamics model for the entropy's evolution accounts for the observed exponential distribution of entropies and the stochastic synchronization. >>

<< One general virtue of noise-induced synchronization is that one may use it to induce synchronization without

specific knowledge about the limit cycle being synchronized, such as the phase map function or the cycle time.(..) As noted in the Introduction, synchronization of a remote oscillator enables transmission of information.

Stochastic synchronization appears to have comparable ability, potentially useable by technology or biology. >>️

<< The stochastic synchronization phenomenon explored above seems to be a distinctive mode of organization. It can be produced via broad classes of driving, and creates striking fluctuations of randomness. This model may aid understanding of other puzzling systems showing erratic fluctuations, such as strong turbulence. >>️

️

Yunxiang Song, Thomas A. Witten. Stochastic synchronization induced by noise. arXiv:2108.13172v1 [cond-mat.stat-mech]. Aug 16, 2021.

https://arxiv.org/abs/2108.13172

Also

<< stabilizzare il volo del fascio di aquiloni  >> in: ️2149 - onda di predazione (to knock seals off the ice).  Notes. Dec 17, 2007. (quasi-stochastic poetry)

https://inkpi.blogspot.com/2007/12/2149-onda-di-predazione-to-knock-seals.html

keyword 'noise' | 'fuzzy' in FonT

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

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