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lunedì 22 marzo 2021

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

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

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


Also

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




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







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sabato 20 marzo 2021

# gst: apropos of transitions among granular entities, the behavior of silicone-coated sand mixtures (the 'magic sand')

<< Sand is a fascinating material. It can flow and be poured like a liquid, but retains many of the properties of solids, clogging pipes or forming sand dunes. (..) Grains interact via simple, Newtonian mechanics, but because so many particles are interacting at once, there is an emergent complexity of flow behavior that cannot yet be explained by simple equations. Scientists are thus not only looking for better theoretical models to explain granular behavior, but convenient "model systems" that can be handled and tuned in the lab to give insights into how the microscopic structure of granular materials gives rise to their macroscopic properties. >>️️

<< A team (..) has studied the properties of mixtures of silicone-coated "magic sand," a popular kids' toy, and normal sand. Silicone-coated sand particles were found to interact only with each other and not with other sand particles. The team discovered that adding silicone-coated sand beyond a certain threshold leads to an abrupt change in clustering and rigidity, a potential way to tune the flow of granular materials for industry.>>️

<< Using three independent methods involving sieving, measuring density and forming stable mounds of sand, they found that the mechanical properties of the mixture changes drastically when the fraction of magic sand to normal sand exceeds 20%. This agreed with findings from percolation theory, which governs how connections between particles span space without any breakages, letting the sand mixture behave in a significantly more solid-like way and bear its own weight. This behavior is known for polymer gels, and helps unify theoretical approaches applied to completely different materials. The team's mixtures also exhibits mechanical properties that can be easily modified. Importantly, the method provides a new, convenient, accurate and informative way to explore granular physics, >>️
️
'Magic sand' might help us understand the physics of granular matter. Tokyo Metropolitan University. Mar 08, 2021.

️
Marie Tani, Honoka Fujio, Rei Kurita. Transition Behavior in Silicone-coated Sand Mixtures. Journal of the Physical Society of Japan. 90 (3): 033801. doi: 10.7566/ JPSJ.90.033801.


Also

keyword 'grain' in FonT

keyword 'sand' in FonT

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

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

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



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mercoledì 17 marzo 2021

# phys: trace the birth and evolution of a quasiparticle entity

<< The idea of quasiparticles was first introduced in the 1930s by physicist Lev Landau, who was trying to gain a better understanding of complex quantum systems. >>

<< Over the past decades, physicists worldwide have been trying to gain a better understanding of non-equilibrium dynamics in quantum many-body systems. Some studies investigated what are known as quasiparticles, disturbances or entities in physical systems that exhibit behavior similar to that of particles. >>

In this study AA << observed three distinct regimes of impurity evolution marked by dynamic transitions. These regimes then link initial few-body and later many-body physical dynamics. >>

Ingrid Fadelli. Observing the birth of a quasiparticle. Mar 11, 2021.


<<  These results offer a systematic picture of polaron formation from weak to strong impurity interactions. They reveal three distinct regimes of evolution with dynamical transitions that provide a link between few-body processes and many-body dynamics. Our measurements reveal universal dynamical behaviour in interacting many-body systems and demonstrate new pathways to study non-equilibrium quantum phenomena. >>

Magnus G. Skou, Thomas G. Skov, et al. Non-equilibrium quantum dynamics and formation of the Bose polaron. 
Nat. Phys. (2021). doi: 10.1038/ s41567-021-01184-5. Feb 25, 2021.


"three distinct regimes"  




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lunedì 15 marzo 2021

# 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. 


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.


Also

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


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


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


(+) keyword "fracture" in FonT







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giovedì 11 marzo 2021

# life: even a slime mold takes smart decisions about the future (Physarum polycephalum)

<< The slime mold Physarum polycephalum has been puzzling researchers for many decades. Existing at the crossroads between the kingdoms of animals, plants and fungi, this unique organism provides insight into the early evolutionary history of eukaryotes. Its body is a giant single cell made up of interconnected tubes that form intricate networks. This single amoeba-like cell may stretch several centimeters or even meters, featuring as the largest cell on earth in the Guinness Book of World Records. >>

<< The striking abilities of the slime mold to solve complex problems such as finding the shortest path through a maze earned it the attribute "intelligent," intrigued the research community and kindled questions about decision making on the most basic levels of life. >> 

<<  The decision-making ability of Physarum is especially fascinating given that its tubular network constantly undergoes fast reorganization—growing and disintegrating its tubes—while completely lacking an organizing center. The researchers discovered that the organism weaves memories of food encounters directly into the architecture of the network-like body and uses the stored information when making future decisions. >>

Researchers find a single-celled slime mold with no nervous system that remembers food locations. Max Planck Society. Feb 23, 2021.  


Mirna Kramar, Karen Alim. Encoding memory in tube diameter hierarchy of living flow network. PNAS. 118 (10).  e2007815118. doi: 10.1073/ pnas.2007815118








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sabato 6 marzo 2021

# gst: the dynamics of a collective bubble (in a foam) that collapse in a droplet

<< Foams have unique properties that distinguish them from ordinary liquids and gases, and are ubiquitously observed in nature, both in biological systems and industrial products. (..) understanding how bubbles in a foam collapse is an important aspect for product longevity and tailoring physical properties. >>

<< Once a crack appears near the border and a collapse front is formed, (AA) find that the curvature of the front reverses as it migrates, followed by the emergence and emission of droplets. >>

<<  It is particularly interesting to note how the shape of the front changes as it migrates. >>

Naoya Yanagisawa, Marie Tani, Rei Kurita. Dynamics and mechanism of liquid film collapse in a foam. Soft Matter 17, 1738-45. doi: 10.1039/ D0SM02153A. Feb 17, 2021.


<< An initial crack in a film creates a RVPB (released vertical plateau border). A second crack event in the film causes a "collapse front" to be formed which sweeps up the RVPB before its shape begins to flatten and invert, finally leaving a droplet. >>

When foams collapse (and when they don't). Tokyo Metropolitan University. Mar 01, 2021. 




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venerdì 5 marzo 2021

# behav: a viral marketing generated by low levels of advertising

<< What they discovered refutes Gladwell's (Malcolm Gladwell) concept that network position is always paramount. They found that in instances where there is even a small amount of advertising—even when it is just a quarter of a percent as strong as word-of-mouth—there's virtually no difference between the influence of the person at the center of a network and those further out on the string. >> 

 << It's not that word-of-mouth doesn't matter—it's that nobody is particularly important for the word-of-mouth process, (..) What we saw is that when advertising doesn't exist, when advertising is exactly zero, it looks like whoever is Mr. Popular, whoever has the most central connections, really matters. And in that scenario, if you start with that person at the center of the network, like the leader of an organization or company, rather than the intern, then whatever you're selling gets an uptick. >> Gabriel Rossman. 

Jessica Wolf. Forget what you think you know about viral marketing, study suggests. University of California, Los Angeles. Feb 25, 2021.


Gabriel Rossman,  Jacob C. Fisher. Network hubs cease to be influential in the presence of low levels of advertising. PNAS. 118 (7) e2013391118. doi: 10.1073/ pnas.2013391118. Feb 16, 2021. 


FonT

this could also occur in the generation of fake news ...

keyword "fake" in FonT




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