# gst: a slow motion can triggers strong, fast-slip (many miles away)

<< At a glacier near the South Pole, earth scientists have found evidence of a quiet, slow-motion fault slip that triggers strong, fast-slip earthquakes many miles away,  >>

<< During an earthquake, a fast slip happens when energy builds up underground and is released quickly along a fault. Blocks of earth rapidly slide against one another. However, at an Antarctic glacier called Whillans Ice Plain, (they) show that "slow slips" precede dozens of large magnitude 7 earthquakes. >>

<< We found that there is almost always a precursory 'slow slip' before an earthquake, >> Grace Barcheck.

<< these slow-slip precursors- occurring as far as 20 miles away from the epicenter- are directly involved in starting the earthquake. >>

<< These slow slips are remarkably common, (..) and they migrate toward where the fast earthquake slip starts. >>

<< Within a period of two months in 2014, the group captured 75 earthquakes at the bottom of the Antarctic glacier. Data from GPS stations indicated that 73- or 96% - of the 75 earthquakes showed a period of precursory slow motion. >>

Blaine Friedlander. Slow motion precursors give earthquakes the fast slip. Cornell University. Feb 16, 2021.

️

https://phys.org/news/2021-02-motion-precursors-earthquakes-fast.html

G. Barcheck, E. Brodsky, et al. Migratory earthquake precursors are dominant on an ice stream fault. Science Advances. Vol. 7, no. 6, eabd0105. doi: 10.1126/ sciadv.abd0105. Feb 5, 2021.

https://advances.sciencemag.org/content/7/6/eabd0105  

# gst: continuous, (not intermittent, perpetual) tremors and slips ...

<< Applying deep learning to seismic data has revealed tremor and slip occur at all times—before and after known large-scale slow-slip earthquakes—rather than intermittently in discrete bursts, as previously believed. Even more surprisingly, the machine learning generalizes to other tectonic environments, including the San Andreas Fault. >>

Machine learning reveals earth tremor and slip occur continuously, not intermittently. Los Alamos National Laboratory.  Feb 27, 2020.

https://m.phys.org/news/2020-02-machine-reveals-earth-tremor-intermittently.html

<< Slow earthquakes cyclically load fault zones and have been observed preceding major earthquakes on continental faults as well as subduction zones. Slow earthquakes and associated tremor are common to most subduction zones, taking place downdip from the neighboring locked zone where megathrust earthquakes occur. In the clearest cases, tremor is observed in discrete bursts that are identified from multiple seismic stations. By training a convolutional neural network to recognize known tremor on a single station in Cascadia, we detect weak tremor preceding and following known larger slow earthquakes, the detection rate of these weak tremors approximates the slow slip rate at all times, and the same model is able to recognize tremor from different tectonic environments with no further training. >>

Bertrand Rouet-Leduc, Claudia Hulbert, et al. Probing Slow Earthquakes With Deep Learning. Geophysical Research Letters. Volume 47, Issue 4. doi: 10.1029/2019GL085870. Jan 23, 2020.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL085870

# gst: slow dynamics of a interacting mobile impurity (in a bath of localized particles)

AA << investigate dynamics of a single mobile impurity immersed in a bath of Anderson localized particles and focus on the regime of relatively strong disorder and interactions. In that regime, the dynamics of the system is particularly slow, suggesting, at short times, an occurrence of many-body localization. Considering longer time scales, (AA) show that the latter is a transient effect and that, eventually, the impurity spreads sub-diffusively and induces a gradual delocalization of the Anderson insulator. The phenomenology of the system in the considered regime of slow dynamics includes a sub-diffusive growth of mean square displacement of the impurity, power-law decay of density correlation functions of the Anderson insulator and a power-law growth of entanglement entropy in the system. (AA) observe a similar regime of slow dynamics also when the disorder in the system is replaced by a sufficiently strong quasi-periodic potential. >>

Piotr Sierant, Titas Chanda, Maciej Lewenstein, Jakub Zakrzewski. Slow dynamics of a mobile impurity interacting with an Anderson insulator. arXiv: 2212.07107v1 [cond-mat.dis-nn]. Dec 14, 2022. 

https://arxiv.org/abs/2212.07107

Also

keyword 'particle' | 'quasiparticle' in FonT

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

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

keyword 'particelle' in Notes

(quasi-stochastic poetry)

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

Keywords: gst, particles, impurity, disorder, sub-diffusive growth, transition, entanglement entropy

# s-age-behav: meditation vs physiology: the tide is tu(r)ning ...

<< a team led by a Nobel Prize-winning biochemist [Elizabeth H. Blackburn] is engaged in serious studies hinting that meditation might slow aging and lengthen life >>

<< “Ten years ago, if you'd told me that I would be seriously thinking about meditation, I would have said one of us is loco,” Blackburn told the New York Times in 2007 >>

<< The tide is now turning >>

Jo Marchant. Can Meditation Really Slow Aging? What the Latest Science Shows.

http://www.rd.com/health/wellness/meditation-slow-aging/

more:

https://www.ncbi.nlm.nih.gov/m/pubmed/?term=Blackburn+meditation+telomeres

https://www.ncbi.nlm.nih.gov/m/pubmed/?term=meditation+telomeres

# s-brain-evol: lizard, an ancient dreamer

<< Lizards  might  snooze  like  humans  do. Sleeping  lizards  appear  to share  distinctive  brain  activity  patterns  with  sleeping  birds  and mammals (..)  If  true,  the  results  suggest  that  human  sleep patterns  evolved  by  around  300  million  years  ago  in  a  common  ancestor  of  birds,  mammals  and reptiles. >>

Sarah  Schwartz. Dragons  sleep  like  mammals  and  birds. Proof  of  reptiles’  slow-wave  and  REM  cycle  could  alter  understanding  of  slumber’s evolution. 2:19pm,  April  28, 2016

https://www.sciencenews.org/article/dragons-sleep-mammals-and-birds

<< Sleep  has  been  described  in  animals  ranging  from  worms  to  humans.  Yet  the electrophysiological  characteristics  of  brain  sleep,  such  as  slow-wave  (SW)  and  rapid  eye movement  (REM)  activities,  are  thought  to  be  restricted  to  mammals  and  birds.  Recording from  the  brain  of  a  lizard,  the  Australian  dragon  Pogona  vitticeps,  we  identified  SW  and REM sleep  patterns,  thus  pushing  back  the  probable  evolution  of  these  dynamics  at  least  to the  emergence  of  amniotes.  The  SW  and  REM  sleep  patterns  that  we  observed  in  lizards oscillated  continuously  for  6  to  10  hours  with  a  period  of  ~80  seconds.  >>

Mark  Shein-Idelson ,  Janie  M.  Ondracek, et al. Slow  waves,  sharp  waves,  ripples,  and  REM  in  sleeping dragons. Science 29  Apr  2016: Vol.  352,  Issue  6285,  pp.  590-595 DOI:  10.1126/science.aaf3621

http://science.sciencemag.org/content/352/6285/590

# lang: we pronounce words more slowly compared with verbs and sometimes pause

AA << study naturalistic speech from linguistically and culturally diverse populations from around the world >>

AA <<  show a robust tendency for slower speech before nouns as compared with verbs >>

Frank Seifart, Jan Strunk, et al.  Nouns slow down speech across structurally and culturally diverse languages. PNAS. doi: 10.1073/pnas.1800708115. May 14, 2018.

http://www.pnas.org/content/pnas/early/2018/05/09/1800708115/F1.large.jpg

http://www.pnas.org/content/early/2018/05/09/1800708115

<< English is peculiar (..) It can never be representative of human language in general >> Frank Seifart

<< In the years to come, as society grows more complex, the number of nouns available to us may grow exponentially. The diversity of its speakers, not so much >>

Alan Burdick. Why Nouns Slow Us Down, and Why Linguistics Might Be in a Bubble.  May 15, 2018.

https://www.newyorker.com/elements/lab-notes/why-nouns-slow-us-down-and-why-linguistics-might-be-in-a-bubble

# game: chaotic effects of crosstalk injection in social dilemmas

<< In the theory of repeated games, it is a tacit assumption that the various games that a person plays simultaneously have no effect on each other. [AA] introduce a general framework that allows us to analyze “crosstalk” between a player’s concurrent games. In the presence of crosstalk, the action a person experiences in one game can alter the person’s decision in another. >>

Johannes G. Reiter, Christian Hilbe, et al. Crosstalk in concurrent repeated games impedes direct reciprocity and requires stronger levels of forgiveness. Nature Communications 2018; 9 (555). doi: 10.1038/s41467-017-02721-8. Feb 7, 2018.

https://www.nature.com/articles/s41467-017-02721-8  

Researchers develop the first model to capture crosstalk in social dilemmas. Institute of Science and Technology,  Austria. Feb 8, 2018.

https://m.phys.org/news/2018-02-capture-crosstalk-social-dilemmas.html

FonT

percio' si usano "ambiguita'", "pettegolezzo", "fake news" per direzionare, disorientare,  colpevolizzare, isolare individui, gruppi, moltitudini ...

Also

# n-soc: fake news, by slow or/and fast catalysis, everyday, everywhere, in all ages.

https://flashontrack.blogspot.it/2017/02/n-soc-fake-news-by-slow-orand-fast.html

Also

<< Il ruolo sociale del pettegolezzo e' immenso. [..] Il pettegolezzo e' una inquisizione continua e reciproca, uno spionaggio e una sorveglianza di tutti da parte di tutti, a tutte le ore del giorno e della notte. >>

Tarde, Gabriel. Ecrits de psychologie sociale. Cit. Prigogine, Ilya. La Nuova Alleanza. Milano: Longanesi & C., 1979,  pp.147-149. Trad. Morchio, Renzo.

# s-ageing: the long (and slow) life of Greenland shark (Somniosus microcephalus) ...

<< Greenland  sharks  live  at  least  as  long  as 400  years,  and  they  reach  sexual  maturity at  the  age  of  about  150,  a  new  study reports.  The  results  place  Greenland sharks  as  the  longest-lived  vertebrates  on Earth.  The  Greenland  shark  (Somniosus microcephalus)  is  widely  distributed across  the  North  Atlantic,  with  adults reaching  lengths  of  400  to  500  centimeters (13  to  16  feet).  The  biology  of  the Greenland  shark  is  poorly  understood,  yet their  extremely  slow  growth  rates,  at  about 1  cm per  year,  hint  that  these  fish  benefit from  exceptional  longevity. >>

AAAS. Winner  of  the  longest-lived  vertebrate award  goes  to... Public release 11-Aug-2016

http://www.eurekalert.org/pub_releases/2016-08/aaft-wot080816.php

Julius  Nielsen, Rasmus B. Hedeholm, et al.  Eye  lens  radiocarbon  reveals  centuries  of  longevity  in  the  Greenland  shark  (Somniosus microcephalus). Science. 12  Aug  2016: Vol.  353,  Issue  6300,  pp.  702-704 DOI:  10.1126/science.aaf1703.

http://dx.doi.org/10.1126/science.aaf1703

# life: apropos of fake news, creation of misinformation, and how misinformation can spread via person-to-person communication.

<< Numerical facts play a prominent role in public discourse, but individuals often provide incorrect estimates of policy-relevant numerical quantities >>

Jason C Coronel, Shannon Poulsen, Matthew D Sweitzer.  Investigating the generation and spread of numerical misinformation: A combined eye movement monitoring and social transmission approach. Human Communication Research, hqz012, doi: 10.1093/hcr/hqz012. Dec 5, 2019

https://academic.oup.com/hcr/advance-article-abstract/doi/10.1093/hcr/hqz012/5652186

<< If you're looking for who's responsible for all the misinformation out there, you might want to take a peek in the mirror. >>

Jennifer Smola. Facts are misremembered to fit personal biases, study finds.  The Columbus Dispatch (Columbus, Ohio). Dec 26, 2019.

https://phys.org/news/2019-12-facts-misremembered-personal-biases.html

Also

fake news, by slow or/and fast catalysis, everyday, everywhere, in all ages. Feb 20, 2017.  

https://flashontrack.blogspot.com/2017/02/n-soc-fake-news-by-slow-orand-fast.html

<< qui non e' impossibile immaginare una entita' di intelligenza artificiale (AI) che, in modalita' autonoma, intenda utilizzare "le immagini" di uno scenario in transizione di questo tipo come modello base di prima approx per l'analisi del comportamento e le previsioni all'interno di un sistema costituito da entita' altre ... ad es. all'interno di un  contesto culturale umano; >>

Anomalous formation of molecules after vapor deposition.  Dec 31, 2015.

https://flashontrack.blogspot.com/2015/12/rmx-s-gst-anomalous-formation-of.html

<< Il ruolo sociale del pettegolezzo e' immenso. [..] Il pettegolezzo e' una inquisizione continua e reciproca, uno spionaggio e una sorveglianza di tutti da parte di tutti, a tutte le ore del giorno e della notte. >>

Tarde, Gabriel. Ecrits de psychologie sociale. Cit. Prigogine, Ilya. La Nuova Alleanza. Milano: Longanesi & C., 1979,  pp.147-149. Trad. Morchio, Renzo.

keyword "fake" in FonT

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

# gst: the role of surface tension during the collapse of a viscous bubble

<< The rupture and collapse of viscous bubbles are widespread in nature and in industrial applications. The phenomenon is accompanied by elastic sheets that develop radial wrinkles. While the weight of the film appeared to play a dominant role during film collapse and wrinkling instability, in this work, gravity appeared to play a surprisingly negligible role. Based on fluid mechanics of the phenomena, Oratis et al. showed surface tension to be the driving factor during collapse to initiate dynamic buckling instability and wrinkling behavior, accompanied with the breakdown of curved viscous and viscoelastic films. >>

Thamarasee Jeewandara. Ripple effects after slow-motion bubble collapse. Aug 17, 2020.

https://phys.org/news/2020-08-ripple-effects-slow-motion-collapse.html   

Alexandros T. Oratis, John W. M. Bush, et al. A new wrinkle on liquid sheets: Turning the mechanism of viscous bubble collapse upside down. Science. Vol. 369, Issue 6504, pp. 685-688. doi: 10.1126/ science.aba0593. Aug 7, 2020

https://science.sciencemag.org/content/369/6504/685

# s-brain: hacking inside (slow gamma) rhythms

<< Brain cells share different kinds of information with one another using a variety of different brain waves, analogous to the way radio stations broadcast on different frequencies. >>

<< one of these frequencies allows us to play back memories — or envision future activities — in fast forward. >>

<< fast gamma rhythms encode memories about things that are happening right now; these waves come rapidly one after another as the brain processes high-resolution information in real time. The scientists learned that slow gamma rhythms — used to retrieve memories of the past, as well as imagine and plan for the future — store more information on their longer waves, contributing to the fast-forward effect as the mind processes many data points with each wave. >>

<< The finding has implications for medicine as well as for criminal justice and other areas where memory reliability can be at issue. >>

https://scienmag.com/scientists-discover-how-we-play-memories-in-fast-forward/

Chenguang Zheng, Laura Lee Colgin. Beta and Gamma Rhythms Go with the Flow. Open Archive. Neuron , Volume 85 , Issue 2 , 236 - 237. DOI: http://dx.doi.org/10.1016/j.neuron.2014.12.067

http://www.cell.com/neuron/abstract/S0896-6273(14)01176-3

# gst: influence of disorder on the spreading and entanglement properties of coined quantum walks.

AA << investigate the influence of disorder on the spreading and entanglement properties of coined quantum walks. Specifically, (AA) consider quantum walks on the line and explore the effects of quenched disorder in the coin operations. (They) find that coin disorder alters the usual ballistic transport properties of coined quantum walks considerably and yields an extremely slow dynamics with strong evidence for localization behavior. (They) investigate this slow dynamics by comparing different properties of the walker occupation probability with the standard Hadamard walk. (They) find that the walker distribution, and a number of properties associated with it, are significantly altered by the coin disorder. Special focus is given to the influence of coin disorder on entanglement properties. (AA) observe that generically, coin disorder decreases the coin-walker entanglement. The behavior of the entanglement properties further supports the premise that coin disorder induces localization in coined quantum walks. >>

Louie Hong Yao, Sascha Wald. Coined Quantum Walks on the Line: Disorder, Entanglement and Localization. arXiv: 2303.15978v1 [quant-ph]. doi: 10.48550/ arXiv.2303.15978. 28 Mar 28, 2023.

https://arxiv.org/abs/2303.15978

Also

Voli a casaccio. Notes. Oct 01, 2006. 

(quasi-stochastic poetry)

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

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 'walk' | 'walking' in FonT

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

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

keyword 'passo lieve' | 'walk' | 'walking' in Notes

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=passo+lieve

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

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

Keywords: gst, disorder, quantum physics, walk, walking, coined quantum walks

# behav: a great white shark at rest

<< Great white sharks are known for racing past the Mid-Atlantic states to get someplace else, so experts pay attention in rare cases when one not only stops, but stays put.

That's happening now along the Virginia-North Carolina border with a 10-foot, 3-inch male tracked by OCEARCH.

"It's interesting watching white shark Shaw since unlike other sharks on the Tracker, he has been hanging out off the Virginia coast for over a month," OCEARCH posted Tuesday on Facebook. >>

Mark Price. Experts puzzled as 10-foot great white shark stays a month in one spot off East Coast.  Dec 10, 2019.

https://m.phys.org/news/2019-12-experts-puzzled-foot-great-white.html

Ocearch. Dec 4, 2019

https://m.facebook.com/OCEARCH/posts/10162443074005167

Also

The long (and slow) life of Greenland shark (Somniosus microcephalus). Aug 16, 2016. 

https://flashontrack.blogspot.com/2016/08/s-ageing-long-and-slow-life-of.html

# gst: when science meets poetry, an image of three-dimensional stepped cracks (bistability, and their transition to simple cracks)

<< Slow cracks may be simple, with no internal structure. The leading edge of a simple crack, the crack front, forms a single fracture plane in its wake. Slow cracks may also develop segmented crack fronts, each segment propagating along a separate fracture plane. These planes merge at locations that form steps along fracture surfaces. Steps are not stationary, but instead propagate within a crack front. Real-time measurements of crack front structure and energy flux reveal that step dynamics significantly increase energy dissipation and drastically alter crack dynamics. Simple and stepped cracks are each stable. By extending the use of energy balance to include 3D crack front structure, (AA) find that, while energy balance is obeyed, it is insufficient to select the energetically favorable crack growth mode. Transitions from stepped cracks to simple cracks occur only when their in-plane front lengths become equal and a perturbation momentarily changes step topology. Such 3D crack dynamics challenge our traditional understanding of fracture. >>

Meng Wang, Mokhtar Adda-Bedia, Jay Fineberg. Dynamics of three-dimensional stepped cracks, bistability, and their transition to simple cracks. Phys. Rev. Research 5, L012001. Jan 9, 2023. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.L012001

Also

keyword 'crack' in FonT

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

keyword 'rottura' | 'crepa' | 'frattura' | 'rugosa' in Notes

(quasi-stochastic poetry)

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

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

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

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

keywords 'meets poetry' in FonT

https://flashontrack.blogspot.com/search?q=meets+poetry

Keywords:  gst, transitions, dynamical phase transitions, crack, cracking,   fracture, roughness

# behav: large-eared bats adopting slow-flight feeding strategies

AA << compare quantitative aerodynamic measures of flight efficiency of two bat species, one large-eared (Plecotus auritus) and one small-eared (Glossophaga soricina), flying freely in a wind tunnel >>

AA << find that the body drag of both species is higher than previously assumed and that the large-eared species has a higher body drag coefficient, but also produces relatively more ear/body lift than the small-eared species >>

<< The relatively higher power of the large-eared species results in lower optimal flight speeds and [AA] findings support the notion of a trade-off between the acoustic benefits of large external ears and aerodynamic performance. The result of this trade-off would be the eco-morphological correlation in bat flight, with large-eared bats generally adopting slow-flight feeding strategies >>

Jonas Hakansson, Lasse Jakobsen, et al. Body lift, drag and power are relatively higher in large-eared than in small-eared bat species. 2017; 14 (135): 4099. doi: 10.1098/rsif.2017.0455. Oct 25, 2017.

http://rsif.royalsocietypublishing.org/content/14/135/20170455

The pros and cons of large ears. Nov 10, 2017

http://www.lunduniversity.lu.se/article/the-pros-and-cons-of-large-ears

https://www.sciencedaily.com/releases/2017/11/171110084634.htm

# 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: rearrangements of a jammed 2-D emulsion (during slow compression).

<< As amorphous materials get jammed, both geometric and dynamic heterogeneity are observed. (AA)  investigate the correlation between the local geometric heterogeneity and local rearrangements in a slowly compressed bidisperse quasi-two-dimensional emulsion system. The compression is driven by evaporation of the continuous phase. >>

<< droplets in heterogeneous local regions are more likely to have local rearrangements. These rearrangements are generally T1 events where two droplets converge toward a void, and two droplets move away from the void to make room for the converging droplets. Thus, the presence of the voids tends to orient the T1 events. >>️

<< The presence of a correlation between the structural quantities and the rearrangement dynamics remains qualitatively unchanged over the entire range of packing fractions observed. >>️

Xin Du, Eric R. Weeks. Rearrangements during slow compression of a jammed  two-dimensional emulsion. Phys. Rev. E 109, 034605. Mar 20,  2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.034605

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

Keywords: drops, droplets, droploids 

# brain: arterial pressure pulsations could modulate neuronal activity.

<< Spontaneous slow oscillations have been described in the rat olfactory bulb local field potential, even in the absence of respiration. What is the origin of these oscillations? >>

AA << discovered a subpopulation of neurons within the olfactory bulb that can directly sense cardiovascular pressure pulsations (..). The modulation of their excitability is transduced by mechanosensitive ion channels. >>

<< Thus, there exists a fast pathway for the interoception of heartbeat whereby arterial pressure pulsations within the brain modulate neuronal activity. >> Peter Stern. ️

Luna Jammal Salameh, Sebastian H. Bitzenhofer, et al. Blood pressure pulsations modulate central neuronal activity via mechanosensitive ion channels. Science. Vol 383, Issue 6682. Feb 2, 2024. 

https://www.science.org/doi/10.1126/science.adk8511

img: https://www.science.org/cms/10.1126/science.adk8511/asset/76a1eaf8-61d3-4233-bc2a-be2276f367cd/assets/images/large/science.adk8511-fa.jpg

Also: brain, pnei, soliton, in https://www.inkgmr.net/kwrds.html  

Keywords: brain, pnei, olfactory bulb, spontaneous slow oscillations, wave, soliton

# gst: emergent organization and polarization due to active fluctuations.

AA << introduce and study a model of active Brownian motion with multiplicative noise describing fluctuations in the self-propulsion or activity. (They) find that the standard picture of density accumulation in slow regions is qualitatively modified by active fluctuations, as stationary density profiles are generally not determined only by the mean self-propulsion speed landscape. As a result, activity gradients generically correlate the particle self-propulsion speed and orientation, leading to emergent polarization at interfaces pointing either towards dense or dilute regions depending on the amount of noise in the system.  >>

️

Benoit Mahault, Prakhar Godara, Ramin Golestanian. Emergent organization and polarization due to active fluctuations. Phys. Rev. Research 5, L022012. April 12, 2023. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.L022012

Also: 'particle', 'fluctuations', 'noise', 'self-assembly' in https://www.inkgmr.net/kwrds.html

Keywords: gst, particle, organization, polarization, fluctuations, noise, self-propulsion, self-assembly 

# gst: predict the wetting of the wedge; why do the teapots always drip?

<<  The "teapot effect" has been threatening spotless white tablecloths for ages: if a liquid is poured out of a teapot too slowly, then the flow of liquid sometimes does not detach itself from the teapot, finding its way into the cup, but dribbles down at the outside of the teapot. >>

<< This phenomenon has been studied scientifically for decades—now a research team at TU Wien has succeeded in describing the "teapot effect" completely and in detail with an elaborate theoretical analysis and numerous experiments: An interplay of different forces keeps a tiny amount of liquid directly at the edge, and this is sufficient to redirect the flow of liquid under certain conditions. >>

<< Although this is a very common and seemingly simple effect, it is remarkably difficult to explain it exactly within the framework of fluid mechanics,  (..) We have now succeeded for the first time in providing a complete theoretical explanation of why this drop forms and why the underside of the edge always remains wetted, >>  Bernhard Scheichl.

<< The sharp edge on the underside of the teapot beak plays the most important role: a drop forms, the area directly below the edge always remains wet. The size of this drop depends on the speed at which the liquid flows out of the teapot. If the speed is lower than a critical threshold, this drop can direct the entire flow around the edge and dribbles down on the outside wall of the teapot. >>

<< The mathematics behind it is complicated—it is an interplay of inertia, viscous and capillary forces. The inertial force ensures that the fluid tends to maintain its original direction, while the capillary forces slow the fluid down right at the beak. The interaction of these forces is the basis of the teapot effect. However, the capillary forces ensure that the effect only starts at a very specific contact angle between the wall and the liquid surface. The smaller this angle is or the more hydrophilic (i.e. wettable) the material of the teapot is, the more the detachment of the liquid from the teapot is slowed down. >>

<< Interestingly, the strength of gravity in relation to the other forces that occur does not play a decisive role. Gravity merely determines the direction in which the jet is directed, but its strength is not decisive for the teapot effect. The teapot effect would therefore also be observed when drinking tea on a moon base, but not on a space station with no gravity at all. >>️

Why teapots always drip. Vienna University of Technology. Nov 08, 2021

https://phys.org/news/2021-11-teapots.html

Scheichl, B., Bowles, R., & Pasias, G. (2021). Developed liquid film passing a smoothed and wedge-shaped trailing edge: Small-scale analysis and the ‘teapot effect’ at large Reynolds numbers. Journal of Fluid Mechanics, 926, A25. doi: 10.1017/jfm.2021.612. Sep 8, 2021. 

http://dx.doi.org/10.1017/jfm.2021.612

keywords: gst, teapot effect, interfacial flows, thin films, boundary layers, Reynolds number, viscosity, viscous–inviscid interaction