# gst: apropos of waves perturbed by weak turbulences

<< Wave phenomena are ubiquitous at all scales throughout the Universe, and where there are waves, there’s the potential for wave turbulence. Wave turbulence is the physical state that arises in a continuous medium when a large number of wave modes interact with each other randomly. >>

<< A specific case of wave turbulence in which weakly nonlinear waves propagate in an unbounded space is described by weak turbulence theory. Capturing the dynamics of this regime will be helpful to accurately model large fluid systems. >>

<< In a rotating fluid, the predicted wave spectrum for interacting weakly nonlinear inertial waves is perturbed by the formation of geostrophic modes—columnar vortices aligned with the rotation axis (..) (AA) successfully suppress geostrophic modes with the addition of two honeycomb-patterned plates, allowing them to confirm the predictions of weak turbulence theory. >>

Sergey Nazarenko. Verifying Weak Turbulence Theory.  Physics 13, 194. Dec 14, 2020. 

https://physics.aps.org/articles/v13/194

Eduardo Monsalve, Maxime Brunet, et al. Quantitative Experimental Observation of Weak Inertial-Wave Turbulence. Phys. Rev. Lett. 125, 254502. Dec 14, 2020.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.254502

# 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 

# gst: when a soliton juggles ('catches' and 'throws') droplets

<< Jugglers normally work with solid objects, but a research team has now demonstrated a system that juggles liquid drops. (AA)  have previously shown that liquid drops can bounce in place above the surface of the same liquid—or bounce while moving across the surface—if the container is continuously vibrated (..) In these past experiments, the surface was nearly flat, except for waves generated by the bouncing drop. In the new work by undergraduate student Camila Sandivari of the University of Chile and her colleagues, the vibrations cause the liquid surface to form a large standing wave that actively “catches” and “throws” the drop during each cycle of its oscillation. The trapping of the drop is similar in principle to other types of wave traps, such as laser-based optical tweezers, and the system could potentially lead to new types of traps for larger objects. >>

AA << placed water mixed with a dye and a surface-tension-reducing agent in a 20-cm-long, 2.6-cm-wide basin that supports an unusual type of surface wave when the basin is vibrated in a specific frequency range. In this wave, rather than a series of oscillating peaks and valleys, there is only a single standing wave peak, called a soliton. However, this peak doesn’t oscillate uniformly across the basin’s short dimension (the width). A peak appears at one of the long walls coincident with a valley at the opposite wall, and then the peak and the valley switch places moments later, keeping a relatively flat “node” line along the central long axis of the basin. >>

AA << used a pipette to place a few-millimeter-wide drop of the same fluid just above the oscillating soliton, close to one of the long walls, and found that drops could be juggled for up to 90 minutes. The team attributes this unusual stability in part to a property of the soliton: if the drop wanders off-center, the oscillating surface wave pulls it back toward its center, similar to the way the laser field in optical tweezers is able to stably hold a small particle at its center. >>

David Ehrenstein. Juggling Water Drops. Physics 16, 21. Feb 10, 2023. 

https://physics.aps.org/articles/v16/21

Also

keyword 'drop' | 'droplet' | 'droploids' in FonT

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keyword 'goccia' in Notes 

(quasi-stochastic poetry)

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keyword 'solitons' in FonT

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Keywords: gst, solitons, drop, droplet, droploids, goccia

# 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: solitary wave billiards

<<  In the present work (AA) introduce the concept of solitary wave billiards. I.e., instead of a point particle, (they) consider a solitary wave in an enclosed region and explore its collision with the boundaries and the resulting trajectories in cases which for particle billiards are known to be integrable and for cases that are known to be chaotic. A principal conclusion is that solitary wave billiards are generically found to be chaotic even in cases where the classical particle billiards are integrable. However, the degree of resulting chaoticity depends on the particle speed and on the properties of the potential. >>

J. Cuevas-Maraver, P.G. Kevrekidis, H. Zhang. Solitary wave billiards. arXiv: 2203.09489v1 [nlin.PS]. Mar 17, 2022. 

https://arxiv.org/abs/2203.09489

Also 

keyword 'chaos' | 'chaotic' in Font

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

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keyword | 'soliton' in FonT

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keywords: gst, waves, solitons, billiard, chaos 

# phys: the qu-wave of the natural antibiotic gramicidin

<< One of the great counterintuitive puzzles of quantum mechanics is wave-particle duality. This is the phenomenon in which objects behave both like particles and like waves. >>

AA << for the first time, have demonstrated quantum interference in molecules of gramicidin, a natural antibiotic made up of 15 amino acids. Their work paves the way for the study of the quantum properties of  biomolecules and sets the scene for experiments that exploit the quantum nature of enzymes, DNA, and perhaps one day simple life forms such as viruses. >>

A natural biomolecule has been measured acting like a quantum wave for the first time. Mit Tech Rew - Emerging Technology from the arXiv. Nov 9, 2019. 

https://www.technologyreview.com/s/614688/a-natural-biomolecule-has-been-measured-acting-in-a-quantum-wave-for-the-first-time/

Armin Shayeghi, Philipp Rieser, et al. Matter-wave interference of a native polypeptide. arXiv:1910.14538v1 [quant-ph]. Oct 31, 2019.

https://arxiv.org/abs/1910.14538

Also

keyword "quantum" in FonT

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

# gst: "diffusing wave paradox", synthetic microswimmers can mimic the behavior of Amoeba

<< Amoeba are unusual creatures that form when a dispersed population of cells spontaneously comes together and reorganizes itself into a multicellular macroscopic organism. To do this, a few leader cells emit chemical pulses that cause the other individual cells to move in the direction opposite to that of the traveling pulses (the "diffusing wave paradox," ), leading to the formation of dense clusters. >>

<< In experiments, the researchers used spherical particles that are half-coated by a carbon cap and placed in a viscous liquid. When illuminated by light, the particles propel themselves forward with the cap in front. >>

<< At low pulse speeds, the particles have enough time to reorient themselves, if needed, so that their caps are facing in the same direction as that of the traveling pulses. This orientation ensures that the particles travel in the same direction as the pulses. >>

<< At high pulse speeds, on the other hand, the pulses come too quickly for the particles to reorient themselves before the next one comes. This is because the speed of the particles' rotation is limited by the friction of the viscous liquid. So if the particles' caps are initially facing the oncoming pulses, the particles will move counter to the direction of the traveling pulses, resembling the behavior of amoeba in the diffusing wave paradox. >>

Lisa Zyga. Diffusing wave paradox may be used to design micro-robotics. Jun 12, 2019.

https://m.phys.org/news/2019-06-diffusing-paradox-micro-robotics.html

Celia Lozano, Clemens Bechinger. Diffusing wave paradox of phototactic particles in traveling light pulses. Nature Communications 10, Article number: 2495.  Jun 7, 2019.

https://www.nature.com/articles/s41467-019-10535-z

# s-gst: vortex knots in wave systems

<< Waves  surround  us  all  the  time:  sound waves in  the  noise  around  us, light  waves enabling  us  to see,  and  according  to  quantum  mechanics,  all  matter  has  a  wave  nature.  Most  of  these  waves, however,  do  not  resemble  the  regular  train  of  waves  at  the  shore  of  the  ocean—the  pattern  is much  more  chaotic.  Most  significantly,  the  whirls  and  eddies  form  lines  in  space  called  vortices. Along  these  lines,  the  wave  intensity  is  zero,  and  natural  wave  fields  -  light,  sound  and  quantum matter  -  are  filled  with  a  dense  tangle  of  these  null  filaments >>

Knots  in  chaotic  waves. July  29,  2016.

http://m.phys.org/news/2016-07-chaotic.html

Alexander J. Taylor & Mark R. Dennis. Vortex knots in tangled quantum eigenfunctions. Nature Communications. Published 29 Jul 2016 DOI: 10.1038/ncomms12346 OPEN

http://www.nature.com/ncomms/2016/160729/ncomms12346/full/ncomms12346.html

# gst: apropos of transitions, three distinct new families of long-wave instabilities and potential new pathways to turbulence.

AA << reveal three previously unknown instabilities, distinct from the well-known Kelvin-Helmholtz Instability (KHI) and Holmboe Wave Instability (HWI), in that they have longer wavelengths (..) and often slower growth rates. >>

<< The circumstances under which turbulence can persist in strongly stratified flows remains a fascinating debate within the community. [AA] demonstrated that weakly unstable (very) long waves may trigger turbulence and mixing after long periods of time, even under initially very strongly stratified conditions. >>

Lu Zhu, Amir Atoufi, Adrien Lefauve, Rich R. Kerswell, P. F. Linden. Long-wave instabilities of sloping stratified exchange flows. arXiv:2309.10056v1 [physics.flu-dyn]. Sep 18, 2023.

https://doi.org/10.48550/arXiv.2309.10056

Also: waves, instability, transition, turbulence, chaos, in https://www.inkgmr.net/kwrds.html

Keywords: gst, waves, instability, long-wave instability, transition, turbulence, chaos

# gst: collective patterns generated by capillary surfers.

<< Millimeter-sized “surfers” can self-propel across a vibrating liquid surface, interacting with other surfers to create collective patterns. >>

<< Self-propelled objects can move in mesmerizing patterns. The collective movements of groups of such objects typically occur in one of two flow regimes: the inertial regime—think swirling schools of fish in water—or the viscous regime—think swarming colonies of bacteria in mucus. Some self-propelled objects can travel in both flow regimes, a possibility that is less explored. >>️

AA << have studied the motion of a new system of self-propelled objects that move in this intermediate regime, finding that the objects organize into several distinct and tunable motion patterns. >>️️

<< Pairs of self-propelled surfers observed by the team move in one of seven different patterns (the video shows five). These include the “orbit,” where a pair of surfers rotate around a central point; the “tailgate,” where one surfer closely follows another, head to tail in a linear path; and the “jackknife,” where a pair of perpendicular surfers rotate stern to stern around their collision point. >>

<< When only one surfer was present, these mismatched amplitudes propelled the surfer in the direction of its bow. When there were two surfers close to each other, interactions among the waves caused the surfers to either repel each other so that they moved in opposite directions or to come together so that they collectively traced one of seven distinct patterns. >>️

️

Maggie Hudson. Synchronized Surfing of Self-Propelled Particles. Physics 16, s156. Nov 7, 2023. 

https://physics.aps.org/articles/v16/s156

Ian Ho, Giuseppe Pucci, Anand U. Oza, Daniel M. Harris. Capillary surfers: Wave-driven particles at a vibrating fluid interface. Phys. Rev. Fluids 8, L112001. Nov 7, 2023.

https://link.aps.org/doi/10.1103/PhysRevFluids.8.L112001

Anand U. Oza, Giuseppe Pucci, Ian Ho, Daniel M. Harris. Theoretical modeling of capillary surfer interactions on a vibrating fluid bath. Phys. Rev. Fluids 8, 114001. Nov 7, 2023.

https://link.aps.org/doi/10.1103/PhysRevFluids.8.114001

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

Keywords: gst, waves, wave-wave, capillary waves, particles, self-propelled particles, fluid-particle interactions, wave-particle interactions

# soc-eu: Bavarian Greens could be the second party (18% by exit polls)

<< Now, multiple surveys show the Greens polling at 15-17 percent nationally, catching up with or even overtaking the SPD. >>

Zia Weise. The rise and rise of Bavaria’s Greens. Oct 12, 2018.

https://www.politico.eu/article/greens-bavaria-election-germany-the-rise-and-rise-of-bavarias-greens/

<< The Green wave: Glance casually at the election results in Bavaria, in Luxembourg, in Belgium’s communes, and you’ll find a Green wave engulfing the center-left of the political spectrum. Look a bit closer, and you’ll see the traditional political camps - the EPP and Social Democracy - fighting for survival. Mark this day in your calendars as a potential turning point for Europe. >>

Florian Eder. Brussels Playbook. Oct 15, 2018

https://www.politico.eu/newsletter/brussels-playbook/politico-brussels-playbook-presented-by-banco-santander-green-wave-bavarian-earthquake-brexit-crunch/

<< The polls said the Greens were making major gains to secure second place with up to 19 percent of the vote. >>

The Latest: Exit Polls: Top Party Losing Bavaria Majority.  The Associated Press. Oct 14, 2018

https://www.nytimes.com/aponline/2018/10/14/world/europe/ap-eu-germany-bavaria-election-the-latest.html

# gst: chemical waves exhibit fascinating patterns

<< Waves are known in many very different forms; as water waves, light waves or sound waves. But here we are dealing with something quite different - chemical waves >>

<< Typically, one imagines a chemical reaction like this: from specific initial reactants one obtains specific final products. But it does not need to be as simple as that. Self-sustaining oscillations may occur, i.e. periodic changes between two different states >>

<< On a polycrystalline surface, there are then different regions in which the cyclical process occurs at different frequencies. It is precisely this effect that creates those fascinating wave patterns. When a chemical wave moves across the surface and passes from the edge of one grain of crystal to another, it speeds up or slows down, similar to light passing from the air to water.  This changes the complex spiral wave structures according to the particular orientation of the grain surface >>

Vienna University of Technology. Chemical waves guide to catalysts of the future. Feb 20, 2018.

https://m.phys.org/news/2018-02-chemical-catalysts-future.html

Yuri Suchorski, Martin Datler, et al. Visualizing catalyst heterogeneity by a multifrequential oscillating reaction. Nature Communication. 2018; 9 (600). doi: 10.1038/s41467-018-03007-3. Feb 9,  2018.

https://www.nature.com/articles/s41467-018-03007-3

# 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: apropos of 'large deviations', the instanton, to trace rogue waves

<< Strong evidence is given that the rogue waves observed in the tank are hydrodynamic instantons, that is, saddle point configurations of the action associated with the stochastic model of the wave system. (..) these hydrodynamic instantons are complex spatiotemporal wave field configurations which can be defined using the mathematical framework of large deviation theory and calculated via tailored numerical methods. These results indicate that the instantons describe equally well rogue waves created by simple linear superposition (in weakly nonlinear conditions) or by nonlinear focusing (in strongly nonlinear conditions), paving the way for the development of a unified explanation to rogue wave formation. >>

Giovanni Dematteis, Tobias Grafke, et al. Experimental Evidence of Hydrodynamic Instantons: The Universal Route to Rogue Waves. Phys. Rev. X 9, 041057. Dec 18, 2019.

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.9.041057

Stefano Trillo, Amin Chabchoub. Viewpoint: A Unifying Framework for Describing Rogue Waves. Physics 12, 146. Dec18, 2019.

https://physics.aps.org/articles/v12/146

# life: oops! aprops of tsunami wave hazards, exposure to other 'Fukushima Daiichi Nuclear Power Plant' accidents appear to exist ...

<< A major tsunami in the northern Arabian Sea could severely impact the coastlines of India and Pakistan, which are studded with sensitive installations including several nuclear plants, >>

<< Atomic power stations functioning along the Arabian Sea include Tarapur (1,400 megawatts) in India's Maharashtra state, Kaiga (being expanded to 2,200 megawatts) in Karnataka state and Karachi in Pakistan (also being expanded to 2,200 megawatts). A mega nuclear power plant coming up at Jaitapur, Maharashtra will generate 9,900 megawatts, while another project at Mithi Virdi in Gujarat may be shelved because of public opposition. >>

<< Nuclear power plants are located along coasts because their enormous cooling needs can be taken care of easily and cheaply by making using abundant seawater. >>

Nuclear plants in Arabian Sea face tsunami risk. SciDev.Net. Sep 21, 2020.

https://phys.org/news/2020-09-nuclear-arabian-sea-tsunami.html

Rajendran, C.P., Heidarzadeh, et al. The Orphan Tsunami of 1524 on the Konkan Coast, Western India, and Its Implications. Pure Appl. Geophys. doi: 10.1007/ s00024-020-02575-0. Sep 7, 2020. 

https://link.springer.com/article/10.1007/s00024-020-02575-0

<< The earthquake had also generated a 14 m high tsunami that arrived shortly afterwards and swept over the plant's seawall and then flooded the lower parts of reactors 1–4. This caused the failure of the emergency generators and loss of power to the circulating pumps.(..) The resultant loss of reactor core cooling led to three nuclear meltdowns, three hydrogen explosions, and the release of radioactive contamination in Units 1, 2 and 3 between 12 and 15 March. >>

Fukushima Daiichi nuclear disaster.  Last edited Sep 25, 2020 by Dougsim.

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

Also

2157 - il pino di takata matsubara. Notes. Apr 01, 2011. (quasi-stochastic poetry)

https://inkpi.blogspot.com/2011/04/2157-il-pino-di-takata-matsubara.html

Also

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

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Also

keyword 'wave' in Font

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# brain: lizard, an ancient dreamer (2)

<< Reptiles have a brain area previously suspected to play a role in mammalian higher cognitive processes, and establish its role in controlling brain dynamics in sleep. >>

<< The fact that we find a claustrum homolog in reptiles suggests that the claustrum is an ancient structure, likely present in the brains of the common vertebrate ancestor of reptiles and mammals, (..) While our results have not answered the question as to whether the claustrum plays a role in consciousness or higher cognitive functions, they indicate that it may play an important role in the control of brain states (such as in sleep), due to ascending input from the mid- and hindbrain, to its widespread projections to the forebrain and to its role in sharp-wave generation during slow-wave sleep, >> Gilles Laurent

Hidden away: An enigmatic mammalian brain area revealed in reptiles. Max Planck Society.  Feb 13, 2020

https://m.phys.org/news/2020-02-hidden-enigmatic-mammalian-brain-area.html

Hiroaki Norimoto, Lorenz A. Fenk, et al. A claustrum in reptiles and its role in slow-wave sleep. Nature volume 578, pages 413–418. Feb 12, 2020

https://www.nature.com/articles/s41586-020-1993-6

Also

keyword 'lizard' in FonT

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

# gst; apropos of hair that can be combed, some perturbation fields, along the event horizon of extreme black holes, seem to evolve in time indefinitely

 <<  black holes can be fully characterized by only three physical quantities: their mass, spin and charge. Since they have no additional "hairy" attributes to distinguish them, black holes are said to have "no hair"—Black holes of the same mass, spin, and charge are exactly identical to each other. >> 

AA << discovered that a special kind of black hole violates black hole uniqueness, the so-called "no hair" theorem. Specifically, the team studied extremal black holes—holes that are "saturated" with the maximum charge or spin they can possibly carry. They found that there is a quantity that can be constructed from the spacetime curvature at the black hole horizon that is conserved, and measurable by a distant observer. Since this quantity depends on how the black hole was formed, and not just on the three classical attributes, it violates black hole uniqueness. This quantity constitutes "gravitational hair" and potentially measurable by recent and upcoming gravitational wave observatories like LIGO and LISA. >>

<< even though external perturbations of extreme black holes decay as they do also for regular black holes, along the event horizon certain perturbation fields evolve in time indefinitely. >>

<< The uniqueness theorems assume time independence. But the Aretakis phenomenon explicitly violates time independence along the event horizon. This is the loophole through which the hair can pop out and be combed at a great distance by a gravitational wave observatory, >> Lior Burko.

Extreme black holes have hair that can be combed. Theiss Research. Jan 26, 2021.

https://phys.org/news/2021-01-extreme-black-holes-hair.html

Lior M. Burko, Gaurav Khanna, Subir Sabharwal. Scalar and gravitational hair for extreme Kerr black holes. Phys. Rev. D 103, L021502. Jan 26, 2021.

https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.L021502  

# gst: contactless manipulation of droplets levitating in an acoustic wave

<< A unique, versatile, and material-independent approach to manipulate contactlessly and merge two chemically distinct droplets suspended in an acoustic levitator is reported. Large-amplitude axial oscillations are induced in the top droplet by low-frequency amplitude modulation of the ultrasonic carrier wave, which causes the top sample to merge with the sample in the pressure minimum below. The levitator is enclosed within a pressure-compatible process chamber to enable control of the environmental conditions. The merging technique permits precise control of the substances affecting the chemical reactions, the sample temperature, the volumes of the liquid reactants down to the picoliter range, and the mixing locations in space and time. >>

Stephen J. Brotton, Ralf I. Kaiser. 

Controlled Chemistry via Contactless Manipulation and Merging of Droplets in an Acoustic Levitator. Anal. Chem. 2020, 92, 12, 8371–8377. doi: 10.1021/ acs.analchem.0c00929. Jun 1, 2020. 

https://pubs.acs.org/doi/10.1021/acs.analchem.0c00929#

Levitating droplets allow scientists to perform 'touchless' chemical reactions.  American Chemical Society. Jun 24, 2020.

https://phys.org/news/2020-06-levitating-droplets-scientists-touchless-chemical.html  

# chem: more on the weirdness of water, "T" and "non-T" Tetrahedral arrangements

<< the unusual properties of liquid water, if compared with other liquids, has puzzled us for centuries because the basic structure of liquid water has remained unclear and has continued to be a matter of serious debate. >>

AA << show that there are two overlapped peaks hidden in the apparent “first diffraction peak” of the structure factor. One of them (ordinary peak) corresponds to the neighboring O–O [Oxygen-Oxygen bond] distance as in ordinary liquids, and the other (anomalous peak) corresponds to a longer distance. >>

the << anomalous peak arises from the most extended period of density wave associated with a tetrahedral water structure and is to be identified as the so-called first sharp diffraction peak >>

<< In contrast, the ordinary peak arises from the density wave characteristic of local structures lacking tetrahedral symmetry. This finding unambiguously proves the coexistence of two types of local structures in liquid water. >>

Rui Shi, Hajime Tanaka. Direct Evidence in the Scattering Function for the Coexistence of Two Types of Local Structures in Liquid Water. J. Am. Chem. Soc. doi: 10.1021/ jacs.9b11211. Jan 21, 2020. 

https://pubs.acs.org/doi/10.1021/jacs.9b11211#

Water, water everywhere—and it's weirder than you think. University of Tokyo. Feb 4, 2020.

https://m.phys.org/news/2020-02-everywhereand-weirder.html

# rmx-s-phys: wave's complex exceptional points

<< When  waves  are  able  to  absorb  or  release  energy,  so-called  "exceptional  points"  occur,  around which  the  waves  show  quite  peculiar  behaviour >>

<< Exceptional  points  occur,  when  the  shape  and  the absorption  of  a  system  can  be  tuned  in  such  a  way  that  two  different  waves  can  meet  at  one specific  complex  frequency >>

<< At  this  exceptional  point  the  waves  not  only  share the  same  frequency  and  absorption  rate,  but  also  their  spatial  structure  is  the  same.  One  may thus  really  interpret  this  as  two  wave  states  merging  into  a  single  one  at  the  exceptional  point. >>

The  exception  and  its  rules. 'Exceptional  points'  give  rise  to  counterintuitive  physical  effects. Vienna University of Technology. 27 Jul 2016.

http://www.eurekalert.org/pub_releases/2016-07/vuot-tea072016.php

Jorg  Doppler,  Alexei  A.  Mailybaev, et al.  Dynamically  encircling  an  exceptional  point  for asymmetric  mode  switching. Nature   (2016)   doi:10.1038/nature18605.  Published  online  25  July  2016

http://dx.doi.org/10.1038/nature18605