# gst: when a continuous attractor could survive seemingly destructive bifurcations

<< Continuous attractors offer a unique class of solutions for storing continuous-valued variables in recurrent system states for indefinitely long time intervals. Unfortunately, continuous attractors suffer from severe structural instability in general--they are destroyed by most infinitesimal changes of the dynamical law that defines them. >>️

AA << build on the persistent manifold theory to explain the commonalities between bifurcations from and approximations of continuous attractors. Fast-slow decomposition analysis uncovers the persistent manifold that survives the seemingly destructive bifurcation. Moreover, recurrent neural networks trained on analog memory tasks display approximate continuous attractors with predicted slow manifold structures. >>️

<< continuous attractors are functionally robust and remain useful as a universal analogy for understanding analog memory. >>

Ábel Ságodi, Guillermo Martín-Sánchez, Piotr Sokół, Il Memming Park. Back to the Continuous Attractor. arXiv: 2408.00109v1 [q-bio.NC]. Jul 31, 2024. 

https://arxiv.org/abs/2408.00109

Also: attractor, analogy, brain, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, attractor, continuous attractor, analogy, brain

# gst: sudden noise-induced expansions beyond the onset of a steady symmetry-breaking bifurcation.

AA << consider fluid flows (..) subject to a steady symmetry-breaking bifurcation and forced by a weak noise acting on a slow timescale. >>

The validity of their proposed model << is tested on the flow past a sudden expansion for a given Reynolds number and different noise amplitudes. At a very low numerical cost, the statistics obtained from the amplitude equation accurately reproduce those of long-time direct numerical simulations. >>

Yves-Marie Ducimetière, Edouard Boujo, François Gallaire. Noise-induced transitions past the onset of a steady symmetry-breaking bifurcation: The case of the sudden expansion. Phys. Rev. Fluids 9, 053905. May 3, 2024. 

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.053905

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

Keywords: gst, transition, noise

# 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: evolution of survivors compared to discrete vs continuous noise

<< Environmental variations can significantly influence how populations compete for resources, and hence shape their evolution. Here, (AA) study population dynamics subject to a fluctuating environment modeled by a varying carrying capacity changing continuously in time according to either binary random switches, or by being driven by a noise of continuous range. >>

<< the slow strain fixation probability can be greatly enhanced for a continuously varying environment compared to binary switches, even when the first two moments of the carrying capacity coincide. >>️

Ami Taitelbaum, Robert West, et al. Evolutionary dynamics in a varying environment: Continuous versus discrete noise. Phys. Rev. Research 5, L022004. April 4, 2023. 

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.L022004

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

Keywords: gst, evolution, noise, discrete vs continuous noise

# 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: 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

# 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

# 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

# gst: apropos of transitions, disordered systems mimic genetic evolution.

<< A bacterial genome’s evolution under changing drug concentrations displays effects of memory formation and mimics how disordered solids respond to external forces. >>️

AA << simulate the effect on adaptation of an environment that is constantly changing. Using a model that describes how slow-moving disordered systems respond to external forces, (they) find that microbe evolution in changing drug concentrations exhibits hysteresis and memory formation. They use analytical methods and numerical simulations to connect these statistical physics concepts to bacterial drug resistance. >>️

AA << find that this behavior mimics that of disordered systems driven by external forces, such as ferromagnetic materials subjected to magnetic fields or amorphous materials subjected to a shearing force. They say that while their approach focuses on the evolution of drug resistance, the framework can be adapted to other problems in evolutionary biology that involve changing environmental parameters. >>

️

Rachel Berkowitz. Disordered Systems Mimic Genetic Evolution. Physics 15, s118. Sep 20, 2022. 

https://physics.aps.org/articles/v15/s118

Suman G. Das, Joachim Krug, Muhittin Mungan. Driven Disordered Systems Approach to Biological Evolution in Changing Environments. Phys. Rev. X 12, 031040. Sep 20, 2022.

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.12.031040

Also

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

Keywords: gst, disorder, disordered systems, evolution, genetic evolution 

# 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 

# evol: ancient photosynthesis could be as old as life itself

<< the earliest bacteria had the tools to perform a crucial step in photosynthesis,  (..) The finding also challenges expectations for how life might have evolved on other planets. >>️

<< Photosystem II show patterns of evolution that are usually only attributed to the oldest known enzymes, which were crucial for life itself to evolve >> Tanai Cardona.️

<< enzymes capable of performing the key process in oxygenic photosynthesis -- splitting water into hydrogen and oxygen -- could actually have been present in some of the earliest bacteria. The earliest evidence for life on Earth is over 3.4 billion years old and some studies have suggested that the earliest life could well be older than 4.0 billion years old.  Like the evolution of the eye, the first version of oxygenic photosynthesis may have been very simple and inefficient; as the earliest eyes sensed only light, the earliest photosynthesis may have been very inefficient and slow. (..) that oxygen production was present at all so early on means in other environments, such as on other planets, the transition to complex life could have taken much less time. >>️

Photosynthesis could be as old as life itself. Imperial College London. Mar 24, 2021. 

https://www.sciencedaily.com/releases/2021/03/210324142839.htm

Thomas Olivera, Patricia Sanchez-Baracaldo, et al. Time-resolved comparative molecular evolution of oxygenic photosynthesis.Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2021; 1862 (6): 148400. doi: 10.1016/ j.bbabio.2021.148400. Jun 1,  2021.

https://www.sciencedirect.com/science/article/pii/S0005272821000335

Also

Lewis M. Ward, Patrick M. Shih. Granick revisited: Synthesizing evolutionary and ecological evidence for the late origin of bacteriochlorophyll via ghost  lineages and horizontal gene transfer. PLoS ONE 16(1): e0239248. doi:10.1371/journal.pone.0239248. 

Jan 28, 2021. 

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0239248

# gst: an atomic imaging of a (slow) crack

AA << successfully imaged the snapping of individual atomic bonds in a one-atom-thick sheet of rhenium disulfide ( ReS2) using scanning transmission electron microscopy. (STEM) >>

<< Because of its unusual chemistry, Re forms a 2D lattice with "lanes" that guide cracks, allowing the cracks to propagate with ease. The heavy element also efficiently deflects electrons, providing the signal needed to gain clear images. The study is a remarkable example of how a specific material can provide insight into the universal behavior of matter. >>

<< Because of its strong scattering, ReS2 provides an ideal target for STEM. (Interestingly, tungsten, the periodic-table neighbor of Re, has just one fewer proton and is routinely used in electron microscopy to stain viruses and bacterial flagella.)  >>

<< By measuring the deformation of the lattice around the crack, the team showed that the tearing stresses were concentrated around the crack tip. The stresses then decayed as the inverse square root of the distance from the tip, a finding that matches predictions for macroscopic materials. Using these measurements, the team defined a stress intensity threshold for cracks to propagate. >>

<< The images taken by Huang and colleagues used seconds-long exposure times, meaning they could only follow the propagation of the slowest crack (those that moved at a few angstroms per second). There is much interest in how faster cracks behave, as these cracks are subject to instabilities, meaning they can deviate from a straight line or form branches, for example. To observe faster cracks, future experiments could use reduced exposure times. >>

Itamar Kolvin. Atomic Imaging of Cracks. Physics 13, 193. Dec 9, 2020. 

https://physics.aps.org/articles/v13/193

Lingli Huang, Fangyuan Zheng, et al. In Situ Scanning Transmission Electron Microscopy Observations of Fracture at the Atomic Scale. Phys. Rev. Lett. 125, 246102. Dec 9, 2020.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.246102

Also

(+)  the intriguing dynamics of a crack. Nov 7, 2017. 

https://flashontrack.blogspot.com/2017/11/gst-intriguing-dynamics-of-crack.html

(+) multiple cracks, simultaneously ... Oct 23, 2016.

https://flashontrack.blogspot.com/2016/10/s-gst-multiple-cracks-simultaneously.html

(+) onda criptica. May 22, 2005 (quasi-stochastic poetry)

https://inkpi.blogspot.com/2005/05/1641b-onda-criptica.html

(+) keyword "fracture" in FonT

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

# gst: apropos of 'transitions', slow dynamics of complex connected networks can control the rate of demixing

<< A space- spanning network structure is a basic morphology in phase separation of soft and biomatter, alongside a droplet one. Despite its fundamental and industrial importance, the physical principle underlying such network- forming phase separation remains elusive. >>

AA << find that phase- separation dynamics is controlled by mechanical relaxation of the network- forming dense phase, whose limiting process is permeation flow of the solvent for colloidal suspensions and heat transport for pure fluids. This universal coarsening law would contribute to the fundamental physical understanding of network-forming phase separation. >>

Michio Tateno, Hajime Tanaka. Power-law coarsening in network-forming phase separation governed by mechanical relaxation. Nat Commun 12, 912. doi: 10.1038/  s41467-020-20734-8. Feb 10,  2021.

https://www.nature.com/articles/s41467-020-20734-8

️

Discovery of a new law of phase separation. University of Tokyo. Feb 10, 2021. 

https://phys.org/news/2021-02-discovery-law-phase.html

Also

keyword 'transition' in FonT

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

keyword 'transition' | 'transizion*' in Notes (quasi-stochastic poetry)

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

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

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

# 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  

# life: apropos of unsubstantiated belief (e.g. paranormal belief, anomalistic psychology, ...) why so many people believe in 'ghosts'.

<< Unlikely as it might seem in the cold light of day, ghosts and hauntings are a mainstream area of belief. Recent studies by YouGov in the UK and the USA show that between 30% and 50% of the population says they believe in ghosts. Belief in ghosts also appears to be global, with most (if not all) cultures around the world having some widely accepted kind of ghosts. >> 

<< The existence of a ghost as an incorporeal (bodyless) soul or spirit of a dead person or animal is contrary to the laws of nature as we understand them, so it seems there is something here that calls for explanation. We can look at the worlds of literature, philosophy and anthropology for some of the reasons why people are so keen to believe. >> 

<< Looking at how the brain works, the experience of hallucinations is a lot more common than many people realise. The SPR (Society for Psychical Research), founded in 1882, collected thousands of verified first-hand reports of visual or auditory hallucinations (..)   https://psi-encyclopedia.spr.ac.uk/articles/ghosts-and-apparitions-psi-research-overview#footnote52_nux8rmw   (..) Another source of hallucinations is the phenomenon of sleep paralysis, (..) >> 

<< According to the Dutch philosopher Baruch Spinoza, belief comes quickly and naturally, whereas scepticism is slow and unnatural. In a study of neural activity, Harris and colleagues discovered that believing a statement requires less effort than disbelieving it. >>

<<  Given these multiple reasons for us to believe in ghosts, it seems that the belief is likely to be with us for many years to come. >> 

Anna Stone. ‘I see dead people’: why so many of us believe in ghosts. 

Oct 30, 2020. 

https://theconversation.com/i-see-dead-people-why-so-many-of-us-believe-in-ghosts-148886

Also

keyword 'paranormal belief' in PubMed

https://pubmed.ncbi.nlm.nih.gov/?term=paranormal+belief

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

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

# life: the 'built-in float' of an ancient marine predator

<< About 240 million years ago, when reptiles ruled the ocean, a small lizard-like predator floated near the bottom of the edges in shallow water, picking off prey with fang-like teeth. >>

<< Our analysis of two well-preserved skeletons reveals a reptile with a broad, pachyostotic body (denser boned) and a very short, flattened tail. A long tail can be used to flick through the water, generating thrust, but the new species we've identified was probably better suited to hanging out near the bottom in shallow sea, using its short, flattened tail for balance, like an underwater float, allowing it to preserve energy while searching for prey, >> Qing-Hua Shang.

<< Perhaps this small, slow-swimming marine reptile had to be vigilante for large predators as it floated in the shallows, as well as being a predator itself, >> Xiao-Chun Wu.

Taylor & Francis. Ancient marine predator had a built-in float. Oct 28, 2020. 

https://phys.org/news/2020-10-ancient-marine-predator-built-in.html

Qing-Hua Shang, Xiao-Chun Wu, Chun Li. A New Ladinian Nothosauroid (Sauropterygia) from Fuyuan, Yunnan Province, China. Journal of Vertebrate Paleontology. doi: 10.1080/ 02724634.2020.1789651. Oct 29, 2020.

https://www.tandfonline.com/doi/10.1080/02724634.2020.1789651  

# gst: observing the crystallization process in a droplet

<< Crystallization is the assembly of atoms or molecules into highly ordered solid crystals, which occurs in natural, biological, and artificial systems. However, crystallization in confined spaces, such as the formation of the protein shell of a virus, is poorly understood. Researchers are trying to control the structure of the final crystal formed in a confined space to obtain crystals with desired properties, which requires thorough knowledge of the crystallization process. >>

AA << used a droplet of a colloid—a dispersion of liquid particles in another liquid, like milk—as a model for single atoms or molecules in a sphere. Unlike single atoms or molecules, which are too small to easily observe, the colloid particles were large enough to visualize using a microscope. This allowed the researchers to track the ordering of single particles in real time during crystallization. >>

<< We visualized the organization process of colloid particles in numerous droplets under different conditions to provide a picture of the crystallization process in a sphere, >> Peng Tan

<< Based on their observations, the team proposed that the crystallization process involved three stages: initial ordering on the surface "skin" of the droplet, nucleation and growth in the core of the droplet, and then slow ripening of the whole structure. First, a skin consisting of a single layer of ordered colloid particles rapidly formed on the droplet surface. Next, crystallization occurred in the core of the droplet, far from the crystallized skin. The competition between crystallization in these two regions controlled the structure of the final crystal. The researchers found that the "soft" (long-range) interactions between the negatively charged colloid particles affected their organization and the resulting crystal structure. These soft interactions are dominated by kinetics, that is, the interactions that form the fastest, rather than those that use the least energy to give the thermodynamically stable structure, illustrating that kinetics plays an important role in crystallization in a confined space. It was already known that thermodynamics contributes strongly to the final structure of crystals. >>

Having a ball: Crystallization in a sphere. University of Tokyo. Sep 21, 2020.

https://phys.org/news/2020-09-ball-crystallization-sphere.html

Chen Y., Yao Z., et al. Morphology selection kinetics of crystallization in a sphere. Nat. Phys. doi: 10.1038/ s41567-020-0991-9. Sep 21, 2020.

https://www.nature.com/articles/s41567-020-0991-9

Also

Control of material crystallization by agitation. Osaka University. Jun 08, 2017.

https://phys.org/news/2017-06-material-crystallization-agitation.html

keyword 'drop' or 'droplet' in FonT

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

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

# 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

# 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