# gst: apropos of swirling granular media, a geometric frustration; will these entities turn left or right?

<< Granular material in a swirled container exhibits a curious transition as the number of particles is increased: At low densities, the particle cluster rotates in the same direction as the swirling motion of the container, while at high densities it rotates in the opposite direction.  >>

AA << show that the transition to counterrotation is friction dependent. At high particle densities, frictional effects result in geometric frustration, which prevents particles from cooperatively rolling and spinning. Consequently, the particle cluster rolls like a rigid body with no-slip conditions on the container wall, which necessarily counterrotates around its own axis. Numerical simulations verify that both wall-disk friction and disk-disk friction are critical for inducing counterrotation. >>

Lisa M. Lee, John Paul Ryan, et al. Geometric frustration induces the transition between rotation and counterrotation in swirled granular media. Phys. Rev. E 100, 012903. July 8, 2019.     https://journals.aps.org/pre/abstract/10.1103/PhysRevE.100.012903  

Leah Burrows. Solving the pancake problem. Harvard University. Aug 30, 2019.    https://m.phys.org/news/2019-08-pancake-problem.html  

# game: exploitation; a theoretical scenario in which victims (chaotically?) will cooperate

<< A new analysis of the famous game-theory puzzle finds that even when the players seem equal, one can learn to profit at the other’s expense-and the victim will cooperate. >>

Prisoner’s dilemma shows exploitation is a basic property of human society. Emerging Technology from the arXiv. May 30, 2019.

https://www.technologyreview.com/s/613585/prisoners-dilemma-shows-how-exploitation-is-a-basic-property-of-human-society/  

Yuma Fujimoto, Kunihiko Kaneko.  Emergence of Exploitation as Symmetry Breaking in Iterated Prisoner's Dilemma. arXiv: 1905.06602v1 [math.OC] May 16, 2019.

https://arxiv.org/abs/1905.06602  

# geo gst: even small flank failures can cause large tsunamis

<< Volcanogenic tsunamis are one of the deadliest volcanic phenomena. >>

<< Small flank failures causing large tsunamis represent a vastly underappreciated geohazards-current tsunami monitoring systems do not monitor for this kind of volcanic activity, instead focusing on large earthquakes or proxies related to unusual increases in magma intrusion.  >>

<< This collapse was captured in unprecedented detail by satellite remote sensing, providing an opportunity to understand the collapse of the volcano (Anak Krakatau volcano,  Indonesia) in a way that has not previously been possible at any volcanic island in the world. >>

Reconstructing the Anak Krakatau flank collapse that caused the December 2018 Indonesian tsunami. Geological Society of America. Aug 30, 2019.   https://m.phys.org/news/2019-08-reconstructing-anak-krakatau-flank-collapse.html   

<< the volume of material initially lost from the volcano flank failure (..) was relatively small (~0.1 km3) compared to the overall changes observed during the entire eruption, but it was nonetheless able to generate rapid tsunami waves with devastating impacts. The flank failure also changed the eruption style and the upper volcanic plumbing system, with the subsequent explosive eruptions destroying the summit and then partially rebuilding the lost flank.  >>

Rebecca Williams, Pete Rowley, Matthew C. Garthwaite. Reconstructing the Anak Krakatau flank collapse that caused the December 2018 Indonesian tsunami. Geology. doi.org/10.1130/G46517.1. Aug 30, 2019.    https://pubs.geoscienceworld.org/gsa/geology/article-abstract/573356/reconstructing-the-anak-krakatau-flank-collapse

# bot: here you can imagine a scenery where tiny bots jump & wing-flapping

AA << have recently designed two insect-scale microbots, one that jumps and another that flaps its artificial wings. These robot designs, (..) mimic real biological behaviors observed in insects. >>

Ingrid Fadelli. New designs for jumping and wing-flapping microrobots. Phys.org. Aug 28, 2019.    https://m.techxplore.com/news/2019-08-wing-flapping-microrobots.html 

Palak Bhushan, Claire Tomlin. An Insect-scale Untethered Laser-powered Jumping Microrobot.  arXiv:1908.03282v1 [cs.RO]  Aug 8,  2019.    https://arxiv.org/abs/1908.03282  

Palak Bhushan, Claire Tomlin. Design of the first sub-milligram flapping wing aerial vehicle.  arXiv:1908.03203v1 [cs.RO] Aug 9, 2019.   https://arxiv.org/abs/1908.03203  

# gst: the creation of giant bubbles is underappreciated in sci res

<< In the pantheon of scientific achievement, the creation of giant soap bubbles is sadly underappreciated. >>

<< "How are such large films created, and how do they remain stable?" ask Frazier (Stephen Frazier) and co. >>

The chemistry behind how you make a record-breaking giant soap bubble.
The art of creating giant bubbles is more mysterious than it seems, but researchers are at last teasing apart the chemistry of thin soapy films. Emerging Technology from the arXiv.  Aug 24, 2019.  
https://www.technologyreview.com/s/614181/the-chemistry-behind-how-you-make-a-record-breaking-giant-soap-bubble/      

https://twitter.com/techreview/status/1166167505246871552

Stephen Frazier, Xinyi Jiang, Justin C. Burton. How to make a giant bubble.
arXiv:1908.00537v1 [physics.flu-dyn] Aug 1, 2019. 

https://arxiv.org/abs/1908.00537

FonT

a proposito di generica "creation of giant bubbles", una entita' AI, anche di "media forza", opportunamente orientata per le pulsioni sperimentali, ci giochera' alla grande, io penso ...

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

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

# gst: the hypothesis to optimize multiplicative noise to enhance a signal-to-noise ratio

AA << study simple integrate-and-fire type models with multiplicative noise and consider the transmission of a weak and slow signal, >>

<< The specific question of interest is whether and how the state-dependence of the noise can be optimized with respect to information transmission >>

<< also in a biophysically more relevant situation, multiplicative noise can enhance the signal-to-noise ratio (..) results shed light on a so far unexplored aspect of stochastic signal transmission in neural systems. >>

Jonathan Bauermann Benjamin Lindner. Multiplicative noise is beneficial for the transmission of sensory signals in simple neuron models. Biosystems. Volume 178, Apr 2019, Pages 25-31. doi: 10.1016/ j.biosystems.2019.02.002

https://www.sciencedirect.com/science/article/pii/S0303264718303861

# gst: active drops: from steady to chaotic self-propulsion

<< Individual chemically active drops suspended in a surfactant solution were observed to self-propel spontaneously with straight, helical, or chaotic trajectories. (..) strong advection (e.g., large droplet size) may destabilize a steadily self-propelling drop; once destabilized, the droplet spontaneously stops and a symmetric extensile flow emerges. If advection is strengthened even further in comparison with molecular diffusion, the droplet may perform chaotic oscillations. >>

Matvey Morozov, Sebastien Michelin. Nonlinear dynamics of a chemically-active drop: From steady to chaotic self-propulsion. J. Chem. Phys. 150, 044110 (2019). doi: 10.1063/1.5080539. Jan 31, 2019.  https://aip.scitation.org/doi/10.1063/1.5080539