# gst: how small particles could reshape an asteroid

<< In January 2019, NASA's OSIRIS-REx spacecraft was orbiting asteroid Bennu when the spacecraft's cameras caught something unexpected: Thousands of tiny bits of material, some just the size of marbles, began to bounce off the surface of the asteroid—like a game of ping-pong in space. Since then, many such particle ejection events have been observed at Bennu's surface. >>

AA have been studying << asteroids for a long time, and no one had ever seen this phenomenon before—these little particles getting shot off of the surface  (..) such seemingly small occurrences may add up over time—perhaps even helping to give the asteroid its telltale shape, which is often compared to a spinning top. >>

<< basic orbital calculations suggest that all of these particles should do one of two things: Jump off the surface and fall right back down or escape from Bennu's gravity and never come back. >>

<< When particles eventually land on Bennu's surface, many appear to disproportionately fall near its equator where the asteroid has a distinct bulge. As a result, these events could be reshaping the asteroid over thousands or millions of years by moving mass from its north and south to its middle. >>

Daniel Strain. How small particles could reshape Bennu and other asteroids. University of Colorado at Boulder. Sep 9, 2020.

https://phys.org/news/2020-09-small-particles-reshape-bennu-asteroids.html 

McMahon Jay W, Scheeres Daniel J, et al. Dynamical Evolution of Simulated Particles Ejected From Asteroid Bennu. J Geophys Res: Planets. 125 (8). doi: 10.1029/ 2019JE006229. May 18, 2020.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JE006229 

Scheeres Daniel J, McMahon Jay W, et al. Particle Ejection Contributions to the Rotational Acceleration and Orbit Evolution of Asteroid (101955) Bennu. 

J Geophys Res: Planets. 125 (3). doi: 10.1029/ 2019JE006284. March 11, 2020. 

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE006284

# biophys: to sense 'fever' in tiny bio-entities (worms C. elegans)

<< a reliable, precise, microscope-based thermometer using quantum technology (..) measures the temperature for microscopic animals. The technology detects temperature-dependent properties of quantum spins in fluorescent nanodiamonds. >>

<< Quantum sensing is a technology that exploits the ultimate sensitivity of fragile quantum systems to the surrounding environment. High-contrast MRIs (Magnetic Resonance Imaging) are examples of quantum spins in fluorescent diamonds and are some of the most advanced quantum systems working at the forefront of real-world applications. Applications of this technique to thermal biology were introduced seven years ago to quantify temperatures inside cultured cells. However, they had yet to be applied to dynamic biological systems where heat and temperature are more actively involved in biological processes. >>

Get diamonds, take temperature: Quantum thermometer using nanodiamonds senses a 'fever' in tiny worms C. elegans. Osaka City University. Sep 11, 2020. 

https://phys.org/news/2020-09-diamonds-temperature-quantum-thermometer-nanodiamonds.html  

The technique << demonstrates the submicrometer localization of temperature information in living animals and direct identification of their pharmacological thermogenesis, which may allow for quantification of their biological activities based on temperature. >>

Masazumi Fujiwara, Simo Sun, et al. Real-time nanodiamond thermometry probing in vivo thermogenic responses. Science Advances. Vol. 6, no. 37, eaba9636. doi: 10.1126/ sciadv.aba9636. Sep 11, 2020.

https://advances.sciencemag.org/content/6/37/eaba9636    

# gst: near a critical point, switching between exploitation and exploration, to approach life with Lévy's (chaotic) walk

<< Lévy walks are common biological movements. However, the functional advantages of Lévy walks emerging near a critical point are poorly understood. >>

AA << showed that there could be functional advantages associated with Lévy walks emerging near a critical point, including a large dynamic range to stimuli and highly flexible switching between exploitation and exploration. >>

Masato S. Abe. Functional advantages of Lévy walks emerging near a critical point. PNAS.  doi: 10.1073/ pnas.2001548117.  Sep 14, 2020.

https://www.pnas.org/content/early/2020/09/11/2001548117

Chaotic 'Lévy walks' are a good strategy for animals. Riken. Sep 17, 2020.

https://phys.org/news/2020-09-chaotic-lvy-good-strategy-animals.html   

Also

Lévy flight hypothesis, not only for predation ...  Nov 22, 2015.

https://flashontrack.blogspot.com/2015/11/s-gst-levy-flight-hypothesis-not-only.html

keyword 'Lévy' in FonT

https://flashontrack.blogspot.com/search?q=L%C3%A9vy&m=1

# gst: assembling colloidal spheres into rods of several lengths to walk above a pattern.

<< Detailed control over the motion of colloidal particles is relevant in many applications in colloidal science such as lab-on-a-chip devices. Here, (AA) use an external magnetic field to assemble paramagnetic colloidal spheres into colloidal rods of several lengths. The rods reside above a square magnetic pattern and are transported via modulation of the direction of the external magnetic field. >>

<< The rods behave like bipeds walking above the pattern. Depending on their length, the bipeds perform topologically distinct classes of protected walks. >>

<< Using such loops, (they) induce the collision of reactant bipeds, their polymerization addition reaction to larger bipeds, the separation of product bipeds from the educts, the sorting of different product bipeds, and also the parallel writing of a word consisting of several letters. >>

Mahla Mirzaee-Kakhki, Adrian Ernst, et al. Simultaneous polydirectional transport of colloidal bipeds. Nat Commun 11, 4670. doi: 10.1038/ s41467-020-18467-9. Sep 16, 2020.

https://www.nature.com/articles/s41467-020-18467-9

Controlled dynamics of colloidal rods. 

Bayreuth University. Sep 16, 2020. 

https://phys.org/news/2020-09-dynamics-colloidal-rods.html

# gst: the dance (swimming and sinking behavior) of pelagic snails

<< Swimming and sinking behavior by pelagic snails is poorly studied but is important in their ecology, predator-prey interactions, and vertical distributions. >>

AA << focused on how the shell shape, body geometry, and body size affect their swimming behavior from a fluid mechanics perspective. In addition, ZooScan image analysis and metabarcoding of archived vertically stratified MOCNESS samples were used to relate swimming behaviors to night time and daytime vertical distributions. While different large scale swimming patterns were observed, all species exhibited small scale sawtooth swimming trajectories caused by reciprocal appendage flapping. Thecosome swimming and sinking behavior corresponded strongly with shell morphology and size, with the tiny coiled shell pteropods swimming and sinking the slowest, the large globular shelled pteropods swimming and sinking the fastest, and the medium-sized elongated shell pteropods swimming and sinking at intermediate speeds. However, the coiled shell species had the highest normalized swimming and sinking speeds, reaching swimming speeds of up to 45 body lengths s–1. The sinking trajectories of the coiled and elongated shell pteropods were nearly vertical, but globular shell pteropods use their hydrofoil-like shell to glide downwards at approximately 20° from the vertical, thus retarding their sinking rate. The swimming Reynolds number (Re) increased from the coiled shell species [Re ∼ O(10)] to the elongated shell species [Re ∼ O(100)] and again for the globular shell species [Re ∼ O(1000)], suggesting that more recent lineages increased in size and altered shell morphology to access greater lift-to-drag ratios available at higher Re. Swimming speed does not correlate with the vertical extent of migration, emphasizing that other factors, likely including light, temperature, and predator and prey fields, influence this ecologically important trait. Size does play a role in structuring the vertical habitat, with larger individuals tending to live deeper in the water column, while within a species, larger individuals have deeper migrations. >>

Ferhat Karakas, Jordan Wingate, et al. Swimming and Sinking Behavior of Warm Water Pelagic Snails. Front. Mar. Sci. doi: 10.3389/ fmars.2020.556239. Sep 7, 2020. 

https://www.frontiersin.org/articles/10.3389/fmars.2020.556239/full    

<< And it's stunning to think that these sea butterflies are using the same fluid dynamics principles to fly through water that insects use to fly through air, >> David Murphy.

Poetry in motion: Engineers analyze the fluid physics of movement in marine snails. Frontiers. Sep 07, 2020

https://phys.org/news/2020-09-poetry-motion-fluid-physics-movement.html   

Also

<< Snails usually lumber along on their single fleshy foot; but not sea butterflies (Limacina helicina). These tiny marine molluscs gently flit around their Arctic water homes propelled by fleshy wings that protrude out of the shell opening. >>

These << snails swim using the same technique as flying insects, beating their wings in a figure-of-eight pattern,>>

Bizarre snail that swims like a flying insect. The Company of Biologists. Feb 17, 2016. 

https://phys.org/news/2016-02-bizarre-snail-insect.html   

David W. Murphy, Deepak Adhikari, et al. Underwater flight by the planktonic sea butterfly. Journal of Experimental Biology. 2016 219: 535-543. doi: 10.1242/jeb.129205. Feb 17, 2016.

https://jeb.biologists.org/content/219/4/535

# gst: to reach detectability of a weak signal, they add background noise

<< In contrast to most sensors, for which noise is a problem that should be suppressed, (AA) found that adding just the right amount of background noise can actually increase a signal too weak for sensing by normal sensors, to a level that can reach detectability. >>

Walt Mills. To make a better sensor, just add noise. Pennsylvania State University. Sep 03, 2020. 

https://phys.org/news/2020-09-sensor-noise.html   

<< In this article, (AA) adopt a radical approach for next generation ultra-low-power sensor design by embracing the evolutionary success of animals with extraordinary sensory information processing capabilities that allow them to survive in extreme and resource constrained environments. Stochastic resonance (SR) is one of those astounding phenomena, where noise, which is considered detrimental for electronic circuits and communication systems, plays a constructive role in the detection of weak signals. >>

Akhil Dodda, Aaryan Oberoi, et al. 

Stochastic resonance in MoS2 photodetector. Nat Commun 11, 4406 (2020). doi: 10.1038/ s41467-020-18195-0. Sep 2, 2020.

https://www.nature.com/articles/s41467-020-18195-0   

Also 

keyword 'noise' in FonT

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

Also 

plus ambiguity and noise. Notes. Jul 06, 2007  (quasi-stochastic poetry)

https://inkpi.blogspot.com/2007/07/2136-plus-ambiguity-and-noise.html

# blues; New Moon Jelly Roll Freedom Rockers. Vol. 1 (Stony Plain). Sep 4, 2020.

<< In 2007, while rolling through the American night in a ramshackle retirement home vehicle badly disguised as a tour bus, blues legend Charlie Musselwhite and North Mississippi Allstars' guitarist Luther Dickinson engaged in conversation. The younger man related Alvin Youngblood Hart's philosophical desire to live as a "freedom rocker." The wily elder bluesman listened to his words, then looked out the window and knowingly pointed at the rising moon. He replied: "New Moon Freedom Rockers." Back in Mississippi at the Zebra Ranch studio, Musselwhite and Cody and Luther Dickinson joined forces with their dad, roots rock legend Jim Dickinson (who promptly added the words "Jelly Roll" to the band's name), Alvin Hart, and Jimbo Mathus, with NMA bassist Chris Chew and Paul Taylor as guests. They circled chairs, placed mikes, and hit "record." Afterwards, the session tapes were archived. They sat in the vault until Jim Dickinson passed in 2009, and they became apocryphal. Stony Plain's Holger Peterson contacted Luther and Cody about releasing them. >>

<< Here's to hoping there's enough left over for a second volume. >> 

Thom Jurek. AllMusic Review. Sep 4, 2020. 

https://www.allmusic.com/album/new-moon-jelly-roll-freedom-rockers-vol-1-mw0003403214

https://www.youtube.com/channel/UCmlTKgY9YawHtVpwtOv5Z7Q

Also 

keyword 'Jelly Roll' in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=jelly+roll

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

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

keyword 'Jelly Roll' in FonT

https://flashontrack.blogspot.com/search?q=jelly+roll