# gst: approaching uncertainty among many-body real-time dynamics

<< Analog quantum simulation is emerging as a powerful tool for uncovering classically unreachable physics such as many-body real-time dynamics. >>️

AA << examines the interplay of errors arising from simulation of approximate time evolution with those due to practical, real-world device constraints. >>️

Nikita A. Zemlevskiy, Henry F. Froland, Stephan Caspar. Optimization of algorithmic errors in analog quantum simulations. Phys. Rev. A 109, 052425. May 15, 2024. 

https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.052425

<< The new technique focuses on two sources of error that arise from the approximations used to map the quantum system of interest to the analog quantum simulator. In a real-world simulator, these error sources are linked in a complex way, and individually minimizing each error can increase the overall uncertainty of a simulation. (AA) tackled this problem by first isolating the two error sources and then carefully studying their interplay. This analysis enabled the researchers to finely tune a simulation’s parameters to minimize its overall uncertainty and to maximize its precision. >>️

Ryan Wilkinson. Quantifying Uncertainties in Quantum Simulations. 

Physics 17, s51. May 15, 2024. 

https://physics.aps.org/articles/v17/s51

Also: uncertainty, error, noise in https://www.inkgmr.net/kwrds.html 

Keywords: gst, uncertainty, error, noise

# s-acad: medical error in US hospitals

<< Medical  error  in  hospitals  is  the  third  leading  cause  of  death  in  the  U.S.  after  heart  disease  and cancer  -  an  estimated  210,000  to  400,000  deaths  a  year >>

Warning:  Your  hospital  may  kill  you  and  they  won’t  report  it. May  9,  2016.

http://www.kurzweilai.net/warning-your-hospital-may-kill-you-and-they-wont-report-it

<< Medical  error  is  not  included  on  death  certificates  or  in  rankings  of  cause  of  death >>

Makary MA, Daniel M. Medical  error - the  third  leading  cause  of  death  in  the  US. BMJ  2016 May 3;353:i2139. doi: 10.1136/bmj.i2139.

http://www.bmj.com/content/353/bmj.i2139

# music: masters of noise, Frank Zappa plays bicycles

Frank Zappa teaches Steve Allen to play The Bicycle (aired March 3, 1963).

https://youtu.be/QF0PYQ8IOL4

<< This televisual gem inspired me follow along which got me into endless trouble at family picnics and barbecues for playing my own symphonic masterpieces which, for some strange reason, nobody else seemed to enjoy. I extended Frank's genius to my exploration of the vacuum cleaner, ping pong balls and paddles, (..)  The next time you're out in a forest I challenge you to explore the musical nature of nature for yourself. Trees make great drums and often ring with higher tones - not to mention the musical benefits of rocks and stones. >>️️

That Hairy Canadian. Jun 21, 2014. 

https://m.youtube.com/@ThatHairyCanadian

Also: music, jazz, noise, error, in https://www.inkgmr.net/kwrds.html 

Keywords: music, jazz, noise, error

# gst: synchronous dynamics by uncorrelated noise

<< Synchronization is a widespread phenomenon observed in physical, biological, and social networks, which persists even under the influence of strong noise. Previous research on oscillators subject to common noise has shown that noise can actually facilitate synchronization, as correlations in the dynamics can be inherited from the noise itself. However, in many spatially distributed networks, such as the mammalian circadian system, the noise that different oscillators experience can be effectively uncorrelated. >>️

<< Here, (AA) show that uncorrelated noise can in fact enhance synchronization when the oscillators are coupled. Strikingly, (their) analysis also shows that uncorrelated noise can be more effective than common noise in enhancing synchronization. >>️

Zachary G. Nicolaou, Michael Sebek, et al. Coherent Dynamics Enhanced by Uncorrelated Noise. Phys. Rev. Lett. 125, 094101. Aug 24, 2020  

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.094101

https://arxiv.org/abs/2008.10654 

Also

keyword 'error' | 'fuzzy' | 'noise'  in FonT 

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

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

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

keywords 'errore' | 'errori' in Notes (quasi-stochastic poetry)

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

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

keywords 'jelly roll' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=jelly+roll

# brain: jazzy perceptions inside, there’s more to all the noise; even in the dark, neurons of the visual cortex chat

<< Scientists are now rethinking how they study and conceive of perception. >>

<< At every moment, neurons whisper, shout, sputter and sing, filling the brain with a dizzying cacophony of voices. Yet many of those voices don’t seem to be saying anything meaningful at all. They register as habitual echoes of noise, not signal; as static, not discourse. >>️

<< But over the past decade, that view has changed. (..) There’s more to all the noise, scientists realized, than they had assumed. >>️

<< Now, by analyzing both the neural activity and the behavior of mice in unprecedented detail, researchers have revealed a surprising explanation for much of that variability: Throughout the brain, even in low-level sensory areas like the visual cortex, neurons encode information about far more than their immediately relevant task. They also babble about whatever other behaviors the animal happens to be engaging in, even trivial ones — the twitch of a whisker, the flick of a hind leg. Those simple gestures aren’t just present in the neural activity. They dominate it. >>️

<< Our brains aren’t just thinking in our heads. Our brains are interacting with our bodies and the way that we move through the world. >> Cris Niell. 

<< Wait — maybe the brain isn’t noisy. Maybe it’s actually much more precise than we thought, >> David McCormick️.️

Jordana Cepelewicz. ‘Noise’ in the Brain Encodes Surprisingly Important Signals. Quantamag. Nov 7, 2019. 

https://www.quantamagazine.org/noise-in-the-brains-vision-areas-encodes-body-movements-20191107/

Salkoff DB, Zagha E, McCarthy E, McCormick DA. Movement and Performance Explain Widespread Cortical Activity in a Visual Detection Task. Cereb Cortex. 2020 Jan 10;30(1):421-437. doi: 10.1093/ cercor/bhz206. 

https://pubmed.ncbi.nlm.nih.gov/31711133/

Also

keyword 'perception' in FonT

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

keyword 'percezione' | 'percezioni' in Notes (quasi-stochastic poetry)

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

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

keyword 'error' | 'fuzzy' | 'noise'  in FonT 

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

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

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

keywords 'errore' | 'errori' in Notes (quasi-stochastic poetry)

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

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

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: brain, perception, visual cortex, noise

# gst: defects around obstacles, active nematic ratchet in asymmetric arrays

AA << numerically investigate the effect of an asymmetric periodic obstacle array in a two-dimensional active nematic. (They) find that activity in conjunction with the asymmetry leads to a ratchet effect or unidirectional flow of the fluid along the asymmetry direction. The directional flow is still present even in the active turbulent phase when the gap between obstacles is sufficiently small. >>️

AA << demonstrate that the dynamics of the topological defects transition from flow mirroring to smectic-like as the gap between obstacles is made smaller, and explain this transition in terms of the pinning of negative winding number defects between obstacles. >>

️

Cody D. Schimming, C. J. O. Reichhardt, C. Reichhardt. Active nematic ratchet in asymmetric obstacle arrays. Phys. Rev. E 109, 064602. Jun 3, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.064602 

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

Keywords: gst, nematic ratchet,  transition, turbulence, defect, error

# gst: extreme events in two-coupled chaotic oscillators.

This AA study << focuses on the emergence of extreme events in a system of diffusively and bidirectionally two coupled Rössler oscillators and unraveling the mechanism behind the genesis of extreme events. (AA) find the appearance of extreme events in three different observables: average velocity, synchronization error, and one transverse directional variable to the synchronization manifold. >>

<< The emergence of extreme events in average velocity variables happens due to the occasional in-phase synchronization. The on-off intermittency plays for the crucial role in the genesis of extreme events in the synchronization error dynamics and in the transverse directional variable to the synchronization manifold. The bubble transition of the chaotic attractor due to the on-off intermittency is illustrated for the transverse directional variable. >>

S. Sudharsan, Tapas Kumar Pal, et al. Extreme events in two-coupled chaotic oscillators. arXiv: 2409.15855v1 [nlin.CD]. Sep 24, 2024. 

https://arxiv.org/abs/2409.15855

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

Keywords: gst, transition, bubble transition, extreme events

# gst: weird nature: the generation of complex (frilly, flexible, and functional) wrinkling patterns by 'defects'

<< A ubiquitous motif in nature is the self-similar hierarchical buckling of a thin lamina near its margins. This is seen in leaves, flowers, fungi, corals and marine invertebrates. We investigate this morphology from the perspective of non-Euclidean plate theory. We identify a novel type of defect, a branch-point of the normal map, that allows for the generation of such complex wrinkling patterns in thin elastic hyperbolic surfaces, even in the absence of stretching. We argue that branch points are the natural defects in hyperbolic sheets, they carry a topological charge which gives them a degree of robustness, and they can influence the overall morphology of a hyperbolic surface without concentrating elastic energy. >>️

Kenneth K. Yamamoto, Toby L. Shearman, et al. Nature's forms are frilly, flexible, and functional. arXiv: 2103.10509v1. Mar 18, 2021.

https://arxiv.org/abs/2103.10509

Also

keyword 'error' | 'fuzzy' | 'noise'  in FonT 

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

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

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

keywords 'errore' | 'errori' in Notes (quasi-stochastic poetry)

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

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

# qubit: the flip-flop quantum processor, the begin

AA << introduce the flip-flop qubit, a combination of the electron-nuclear spin states of a phosphorus donor that can be controlled by microwave electric fields >>

<< to encode quantum information in the electron-nuclear spin states of 31P [phosphorus] donors in silicon, and to realize fast, high-fidelity, electrically driven universal quantum gates >>

<< a credible pathway to the construction of a large-scale quantum processor, where atomic-size spin qubits are integrated with silicon nanoelectronic devices, in a platform that does not require atomic-scale precision in the qubit placement [..] and, with realistic assumptions on noise and imperfections, are predicted to achieve error rates compatible with fault-tolerant quantum error correction >>

Guilherme Tosi, Fahd A. Mohiyaddin, et al. Silicon quantum processor with robust long-distance qubit couplings. Nature Comm 8, 2017; 450 Sept 06, 2017 doi: 10.1038/s41467-017-00378-x

https://www.nature.com/articles/s41467-017-00378-x

<< a new way to define a 'spin qubit' that uses both the electron and the nucleus of the atom. Crucially, this new qubit can be controlled using electric signals, instead of magnetic ones. Electric signals are significantly easier to distribute and localise within an electronic chip >>

Flip-flop qubits: Radical new quantum computing design invented. Sept 6, 2017

https://scienmag.com/flip-flop-qubits-radical-new-quantum-computing-design-invented/

Fiona MacDonald,  Mike McRae. Breaking: An Entirely New Type of Quantum Computing Has Been Invented. "It's amazing no one had thought of it before."  Sep 6, 2017

http://www.sciencealert.com/breaking-a-brand-new-type-of-qubit-has-been-unveiled-and-it-finally-makes-quantum-computers-scalable

also

# ai-bot: 352 predictions of when machines will make humans obsolete. Sep 2, 2017

http://flashontrack.blogspot.it/2017/09/ai-bot-352-predictions-of-when-machines.html

Bill Berry, Michael Stipe, Peter Buck, Michael Mills (R.E.M.).  "Begin The Begin". In: "Lifes Rich Pageant" (1986)

https://en.m.wikipedia.org/wiki/Begin_the_Begin

https://m.youtube.com/watch?v=7XaoF8bDMcM

# gst: apropos of uncertainty, notes on uncertainty, information, and classical dynamics.

<< Survival in this world is an adventure because we are so ignorant and everything around us seems so uncertain. In fact, it is hard to think of any realistic phenomenon that is completely free from one of the three kinds of uncertainty—deterministic (chaotic), stochastic, and quantum; more often than not, all of the three are present in various degrees. Thus, in order to gain any knowledge about any realistic system, one must understand how to characterize, quantify, and interpret these uncertainties. >>️

Sagar Chakraborty. Eclectic Notes on Uncertainty, Information, and Classical Dynamics. arXiv: 2404.13511v1 [physics.class-ph]. Apr 21, 2024.

https://arxiv.org/abs/2404.13511

Also: uncertainty, noise, error, in  https://www.inkgmr.net/kwrds.html 

Keywords: gst, information, uncertainty, ambiguity, noise, error 

# gst: like steering a marble through a tilting labyrinth, randomness seems to quickly deliver specific outcomes.

<< According to the infinite monkey theorem, a monkey randomly hitting the keys of a typewriter will eventually write something worth reading—but it might take a few trillion years of trying. For those lacking the patience to wait, (AA)  now show that randomness can deliver specific outcomes much more quickly.  Simulating a 2D nanocluster of a dozen particles, (they) determine the temperature at which thermal fluctuations can most quickly rearrange those particles into a predetermined shape. They find that this time can be dramatically cut by applying an appropriate macroscopic force to the particles. >>

<< The duo also simulated nanoclusters that were subject to a macroscopic force field, for example, metallic nanoparticles in an electric field. Like steering a marble through a tilting labyrinth, they found the optimal global force to apply at each iteration such that the nanocluster navigated the space of possible configurations several orders of magnitude more quickly. >>️️

Marric Stephens. Rearranging Nanoclusters Using Randomness. Physics 15, s83. Jun 22, 2022. 

https://physics.aps.org/articles/v15/s83

Francesco Boccardo, Olivier Pierre-Louis. Controlling the Shape of Small Clusters with and without Macroscopic Fields. Phys. Rev. Lett. 128, 256102. Jun 22, 2022.  

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.256102

Also

keyword 'random' in FonT:

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

keyword 'error' | 'fuzzy' | 'noise'  in FonT 

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

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

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

keywords 'errore' | 'errori' in Notes (quasi-stochastic poetry)

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

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

keywords 'jelly roll' in FonT

https://flashontrack.blogspot.com/search?q=jelly+roll

Keywords: gst, nano, nanocluster, fluctuations, randomness, noise

# gst: apropos of disorder & fluctuations

a 'synthetic disorder & fluctuations' from these two blogs ... 

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  

keyword 'error' | 'fuzzy' | 'noise'  in FonT

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

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

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

keywords 'errore' | 'errori' in Notes (quasi-stochastic poetry)

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

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

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

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

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

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  

keyword 'gst' (General Sistem Theory) in FonT 

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

# gst: controlled creation of point defects in 3D colloidal crystals

<< Crystal defects crucially influence the properties of crystalline materials and have been extensively studied. Even for the simplest type of defect—the point defect—however, basic properties such as their diffusive behavior, and their interactions, remain elusive on the atomic scale. >>️

Here AA << demonstrate in situ control over the creation of isolated point defects in a three-dimensional (3D) colloidal crystal allowing insight on a single-particle level. >>

AA << experimental model system provides a unique opportunity to shed light on the interplay between point defects, on the mechanisms of their diffusion, on their interactions, and on collective dynamics. >>️

Max P. M. Schelling, Janne-Mieke Meijer. Controlled creation of point defects in three-dimensional colloidal crystals. Phys. Rev. E 109, L062601. Jun 4, 2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.L062601

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

Keywords: gst, colloids, defect, error, transition

# game: inject irrationality into a game scenario; when a player will be their own worst enemy

<< in game theory, a game is defined as any type of scenario where there's an interaction between different decision-makers, or players, each of whom has well-defined preferences. >>

<< previous analyses assume the decision-makers always do what is best for them-they are fully rational-which is not always realistic. >>

<< So SFI Professor David Wolpert and economist Justin Grana, a former SFI postdoctoral scholar, wanted to inject some humanity into the players. They analyzed games with players who were subject to error, or "boundedly rational." >>

<< Our analysis shows that in many of these situations, a player will be their own worst enemy; >> David Wolpert.

Jenna Marshall. How much would you pay to change a game before playing it? Santa Fe Institute. Aug13, 2019.    https://m.phys.org/news/2019-08-game.html  

David Wolpert, Justin Grana. How Much Would You Pay to Change a Game before Playing It? Entropy 2019, 21, 686. doi: 10.3390/ e21070686. July 13, 2019.   https://www.mdpi.com/1099-4300/21/7/686  

# s-ai: handling imperfect information (from scratch), by Libratus

<< As the great Kenny Rogers once said, a good gambler has to know when to hold ’em and know when to fold ’em. At the Rivers Casino in Pittsburgh this week, a computer program called Libratus may finally prove that computers can do this better than any human card player >>

<< Libratus was created by Tuomas Sandholm, a professor in the computer science department at CMU, and his graduate student Noam Brown >>

<< Playing poker involves dealing with imperfect information, which makes the game very complex, and more like many real-world situations >>

<< Poker has been one of the hardest games for AI to crack (..)   There is no single optimal move, but instead an AI player has to randomize its actions so as to make opponents uncertain when it is bluffing >> Andrew Ng

Will Knight. Why Poker Is a Big Deal for Artificial Intelligence. Jan. 23, 2017

https://www.technologyreview.com/s/603385/why-poker-is-a-big-deal-for-artificial-intelligence/

<< Libratus, for one, did not use neural networks. Mainly, it relied on a form of AI known as reinforcement learning , a method of extreme trial-and-error. In essence, it played game after game against itself >>

<< By contrast [GO], Libratus learned from scratch.

Cade Metz. Inside Libratus, the Poker AI That Out-Bluffed the Best Humans. Feb.01, 2017 07:00 am

https://www.wired.com/2017/02/libratus/

more:

NoamBrown, Tuomas Sandholm. Safe and Nested Endgame Solving for Imperfect-Information Games.

http://www.cs.cmu.edu/~noamb/papers/17-AAAI-Refinement.pdf

# acad: Prometheus vs Pandora interplay

<< Some of the most important rules we need to discover are about how to use technology and, just as importantly, how not to use it. >>

<< The great institutional economist Clarence Ayres wrote about how technology becomes incorporated into our lives in a way that is roughly equivalent to the way tribal societies use totems to interact with each other. >>

<< Every inventor is both a Prometheus stealing fire from the gods, and a Pandora unwittingly releasing a swarm of potential evils on the world. The competition of ideas between hype and doomsaying allows us to discover helpful rules which deal with both. >>

<< Technology doesn't come with a ready-made rulebook for how to use it. We have to discover this in a process of trial, error and argument. And for this the doomsayer is just as vital as the visionary. >>

Brendan Markey-Towler. Doomsaying about new technology helps make it better. Jun 21, 2018.

https://theconversation.com/doomsaying-about-new-technology-helps-make-it-better-98623  

# s-gst: they take decisions in a way that is not necessarily uniform (jazzy? funky? fuzzy?)

AA << found that fate decision is not a unique programmed event, but the result of a very dynamic process composed of spontaneous fluctuation and selective stabilisation of alternative cellular states >>

<< The whole process is reminiscent of trial-and-error learning in which each cell explores—at its own rhythm and independently of cell division—different molecular possibilities (i.e. different genes turned on or off) before reaching a stable combination of active genes and the corresponding morphology >>

AA << observed that some cells seem to "hesitate" and change morphology many times before reaching a stable state >>

Which type of cell to become: Decision through indecision.
July 27, 2017

https://m.phys.org/news/2017-07-cell-decision-indecision.html

<< Individual cells take lineage commitment decisions in a way that is not necessarily uniform >>

AA << identifies a new category of cells with fluctuating phenotypic characteristics, demonstrating the complexity of the fate decision process >>

Alice Moussy, Jérémie Cosette, et al. Integrated time-lapse and single-cell transcription studies highlight the variable and dynamic nature of human hematopoietic cell fate commitment. PLoS Biol 15(7): e2001867 doi: 10.1371/journal.pbio.2001867

http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2001867

FonT

in pratica un lancio di dadi, ... quasi.

<< Amico, qualunque  cosa suonerai . . . >>

http://inkpi.blogspot.it/2007/01/2113-soniche-ramulo.html

# brain: learning on the fly (in D. melanogaster and mammals)

AA << have developed a new computational model that demonstrates a long sought after link between insect and mammalian learning (..)   Incorporating anatomical and functional data from recent experiments, Dr James Bennett and colleagues modelled how the anatomy and physiology of the fruit fly's brain can support learning according to the reward prediction error (RPE) hypothesis. >>️

<< The computational model indicates how dopamine neurons in an area of a fruit fly's brain, known as the mushroom body, can produce similar signals to dopamine neurons in mammals, and how these dopamine signals can reliably instruct learning. >>️

Learning on the fly. University of Sussex. May 7, 2021. 

https://www.sciencedaily.com/releases/2021/05/210507093941.htm

Bennett, J.E.M., Philippides, A.,  Nowotny, T. Learning with reinforcement prediction errors in a model of the Drosophila mushroom body. Nat Commun 12, 2569. doi: 10.1038/ s41467-021-22592-4. May 7,  2021. 

https://www.nature.com/articles/s41467-021-22592-4   

Also

(+) keyword 'melanogaster' in FonT

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

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

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

# gst: the generation of 'fuzzy' signals for fine skeletal muscle control

<< Minute differences in individual muscle cell contractions allow the entire muscle to flex with greater control and accuracy. Long dismissed as "noise" or error, experts now suspect that biological systems may have evolved to include unavoidable variation as a form of information in their communication channels. >>

Different responses in individual cells give muscles more control. University of Tokyo. Sep 01, 2020. 

https://phys.org/news/2020-09-responses-individual-cells-muscles.html   

Takumi Wada, Ken-ichi Hironaka, et al.  Single-Cell Information Analysis Reveals That Skeletal Muscles Incorporate Cell-to-Cell Variability as Information Not Noise.  Cell Rep. Vol 32, Issue 9, 108051.  doi: 10.1016/ j.celrep.2020.108051. Sep 01, 2020. 

https://www.cell.com/cell-reports/fulltext/S2211-1247(20)31036-6

Also

J. J. Collins and C. J. De Luca. Random Walking during Quiet Standing. Phys. Rev. Lett. 73, 764 – Aug 1, 1994.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.73.764