# gst: a floating vortex of fluff, the flight of the dandelion

<< A fluff-topped dandelion seed can float through the air for more than a kilometer before it drifts to the ground. In experiments last year, researchers revealed that the white filaments in the fluff-known collectively as a pappus-create a ring-shaped wake behind the seed that is associated with low pressure and acts to keep it aloft. >>

AA << have theoretically modeled the airflow around the pappus, reproducing the experimentally measured wake and showing that it provides the seed with steady flight capabilities. >>

Katherine Wright. Dandelion Fluff Perfected for Flight. July 2, 2019

https://physics.aps.org/synopsis-for/10.1103/PhysRevFluids.4.071901

Ledda PG, Siconolfi L, et al. Flow dynamics of a dandelion pappus: A linear stability approach. Phys. Rev. Fluids 4, 071901(R) July 2, 2019.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.4.071901

# game: inside an irregular 'rock-paper-scissors' game; 'uneveness nomads' will survive, probably ...

AA << study a class of the stochastic May-Leonard models, with three species dominating each other in a cyclic nonhierarchical way, according to the rock-paper-scissors game. (They) introduce an unevenness in the system, by considering that one of the species is weaker because of a lower selection probability. >>

To << investigate the coexistence probability (..) the surviving species depends on the level of unevenness of the model and the mobility of individuals. >>

Menezes J., Moura B., Pereira TA. Uneven rock-paper-scissors models: Patterns and coexistence. EPL -  Europhysics Letters, Volume 126, Number 1. May 22, 2019.

https://iopscience.iop.org/article/10.1209/0295-5075/126/18003/meta   

Lisa Zyga. The rock-paper-scissors game and coexistence. Phys.org.
Jul 4, 2019

https://m.phys.org/news/2019-07-rock-paper-scissors-game-coexistence.html   

# acad: apropos of pulsating, nomadic entities; to generate and manage 'theories and vagrant thoughts', by Isaac

<< Presumably, the process of creativity, whatever it is, is essentially the same in all its branches and varieties, so that the evolution of a new art form, a new gadget, a new scientific principle, all involve common factors. We are most interested in the “creation” of a new scientific principle or a new application of an old one, but we can be general here. >>

Isaac Asimov Asks, "How Do People Get New Ideas?". A 1959 Essay by Isaac Asimov on Creativity. Oct 20, 2014.

https://www.technologyreview.com/s/531911/isaac-asimov-asks-how-do-people-get-new-ideas/amp/

https://twitter.com/techreview/status/1147256914016964608

# phys: optical vortex to probe magnetism in matter

<< A light "corkscrew" is sensitive to the local magnetic field direction, so it can be used to probe magnetism in a material. >>

<< Circularly polarized light can act as a powerful probe of magnetism in matter. By measuring differences in the transmission of light beams polarized in different directions as they pass through a material, physicists can unravel atomic-level details of the material’s magnetic properties. >>

Synopsis: Optical Vortices Can Probe Magnetism. Jun 12, 2019.

https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.122.237401

A. A. Sirenko, P. Marsik, et al. Terahertz Vortex Beam as a Spectroscopic Probe of Magnetic Excitations. Phys. Rev. Lett. 122, 237401. Jun 12, 2019.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.237401

# brain: short-term exercise enhances brain function

<< Exercise is cheap, and you don't necessarily need a fancy gym membership or have to run 10 miles a day, >> Gary Westbrook

AA << designed a study in mice that specifically measured the brain's response to single bouts of exercise in otherwise sedentary mice that were placed for short periods on running wheels. The mice ran a few kilometers in two hours. >>

<< short-term bursts of exercise- the human equivalent of a weekly game of pickup basketball, or 4,000 steps- promoted an increase in synapses in the hippocampus. Scientists made the key discovery by analyzing genes that were increased in single neurons activated during exercise. >>

<< One particular gene stood out: Mtss1L. This gene had been largely ignored in prior studies in the brain. >>

Study reveals a short bout of exercise enhances brain function. Oregon Health & Science University.  Jul 3, 2019.

https://m.medicalxpress.com/news/2019-07-reveals-short-bout-brain-function.html   

AA << results link short-term effects of exercise to activity-dependent expression of Mtss1L, which propose as a novel effector of activity- dependent rearrangement of synapses. >>

Christina Chatzi, Yingyu Zhang, et al.  Exercise-induced enhancement of synaptic function triggered by the inverse BAR protein, Mtss1L.  eLife 2019; 8: e45920. doi: 10.7554/eLife.45920. Jun 24, 2019

https://elifesciences.org/articles/45920 

# cells: liver tissue as a 'liquid-crystal' structure

<< analysis of the spatial organization of cell polarity revealed that hepatocytes are not randomly oriented but follow a long-range liquid crystal order. >>

New modeling technique discovers surprising 'liquid-crystal' organization of liver tissue. Max Planck Society.  Jul 3, 2019.

https://m.medicalxpress.com/news/2019-07-technique-liquid-crystal-liver-tissue.html   

Hernan Morales-Navarrete, Hidenori Nonaka, et al.  Liquid-crystal organization of liver tissue. eLife. doi: 10.7554/eLife.44860. Jun 17, 2019.

https://elifesciences.org/articles/44860

# gst: when two like-charged spherical metal nanoparticles with unequal charges counterintuitively will attract one another.

<< When it comes to electric charge, there is one overriding theme: opposites attract, and like charges repel. But in a new study, physicists have made the surprising discovery that two spherical like-charged metal nanoparticles with unequal charges can attract one another in a dilute electrolyte solution. The reason, in short, is that the more strongly charged nanoparticle polarizes the metal core of the weakly charged nanoparticle, which alters the interaction between the nanoparticles. >>

<< Our paper elucidates a very counterintuitive behavior which was previously thought to be impossible, >>  Yan Levin.

Lisa Zyga. A counterintuitive case in which like charges attract. Phys.org. Jul 2, 2019.

https://m.phys.org/news/2019-07-counterintuitive-case.html   

Alexandre P. dos Santos, Yan Levin. Like-Charge Attraction between Metal Nanoparticles in a 1∶ 1 Electrolyte Solution.  Phys. Rev. Lett. 122, 248005. June 21, 2019.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.248005