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venerdì 19 febbraio 2021

# life: to eat each other's wings within mating pairs (among wood-feeding cockroaches Salganea taiwanensis)

 << The behavior of eating their mates or a part of their mate's body has been studied in sexual cannibalism or nuptial feeding. In these behaviors, only one sex eats the other unilaterally. Within mating pairs of a wood‐feeding cockroach (Salganea taiwanensis), males and females eat the mate's wings each other, which is the first “mutual” case in these behaviors. Because the evolution of sexual cannibalism and nuptial feeding has been explained based on unilaterality, this mutual eating should have a new significance of reproduction. >> 

Haruka Osaki, Eiiti Kasuya. Mutual wing-eating between female and male within mating pairs in wood‐feeding cockroach. doi: 10.1111/eth.13133. Jan 25, 2021.


Bob Yirka. Wood-eating cockroach couples take turns eating each other's wings after mating. Feb 15, 2021.


Also

the beetle Carabaeus lamarcki, dancer and sky analyzer. May 14, 2016.


2022 - si risvegliano stercorari. Notes. June 17, 2006. (quasi-stochastic poetry)


keyword 'cockroach' in FonT







martedì 9 febbraio 2021

# zoo; apropos of extreme dwarf entities, the nano-chameleon (Brookesia nana)

<< An international team, (..) has discovered a minuscule new species of chameleon.  (..) They have named the new species Brookesia nana. >>

 << At a body length of just 13.5 mm and a total length of just 22 mm including the tail, the male nano-chameleon is the smallest known male of all 'higher vertebrates' >> Frank Glaw.

<< Unfortunately, the habitat of the Nano-Chameleon is under heavy pressure from deforestation, but the area has recently been designated as a protected area, and hopefully that will enable this tiny new chameleon to survive, >> Oliver Hawlitschek.

Meet the nano-chameleon, a new contender for the title of world's smallest reptile. Staatliche Naturwissenschaftliche Sammlungen Bayerns. Feb 01, 2021. 


Glaw, F., Kohler, J., Hawlitschek, O. et al. Extreme miniaturization of a new amniote vertebrate and insights into the evolution of genital size in chameleons. Sci Rep 11, 2522. doi: 10.1038/ s41598-020-80955-1. Jan 28,  2021.



lunedì 8 febbraio 2021

# gst; apropos of hair that can be combed, some perturbation fields, along the event horizon of extreme black holes, seem to evolve in time indefinitely

 <<  black holes can be fully characterized by only three physical quantities: their mass, spin and charge. Since they have no additional "hairy" attributes to distinguish them, black holes are said to have "no hair"—Black holes of the same mass, spin, and charge are exactly identical to each other. >> 

AA << discovered that a special kind of black hole violates black hole uniqueness, the so-called "no hair" theorem. Specifically, the team studied extremal black holes—holes that are "saturated" with the maximum charge or spin they can possibly carry. They found that there is a quantity that can be constructed from the spacetime curvature at the black hole horizon that is conserved, and measurable by a distant observer. Since this quantity depends on how the black hole was formed, and not just on the three classical attributes, it violates black hole uniqueness. This quantity constitutes "gravitational hair" and potentially measurable by recent and upcoming gravitational wave observatories like LIGO and LISA. >>

<< even though external perturbations of extreme black holes decay as they do also for regular black holes, along the event horizon certain perturbation fields evolve in time indefinitely. >>

<< The uniqueness theorems assume time independence. But the Aretakis phenomenon explicitly violates time independence along the event horizon. This is the loophole through which the hair can pop out and be combed at a great distance by a gravitational wave observatory, >> Lior Burko.

Extreme black holes have hair that can be combed. Theiss Research. Jan 26, 2021.


Lior M. Burko, Gaurav Khanna, Subir Sabharwal. Scalar and gravitational hair for extreme Kerr black holes. Phys. Rev. D 103, L021502. Jan 26, 2021.



sabato 6 febbraio 2021

# gst: doubling phonons by subtraction of one of them (in an optical whispering-gallery microresonator)

 << What happens now when you add or subtract a single phonon? At first thought, you may expect this would simply change the average to n + 1 or n - 1, respectively, however the actual outcome defies this intuition. Indeed, quite counterintuitively, when you subtract a single phonon, the average number of phonons actually goes up to 2n.  This surprising result where the mean number of quanta doubles has been observed for all-optical photon-subtraction experiments and is observed for the first time outside of optics here. >>

<< One way to think of the experiment is to imagine a claw machine that you often see in video arcades, except that you can't see how many toys there are inside the machine. Before you agree to play, you've been told that on average there are n toys inside but the exact number changes randomly each time you play. Then, immediately after a successful grab with the claw, the average number of toys actually goes up to 2n, >> Michael Vanner. 

Adding or subtracting single quanta of sound.  Imperial College London. Jan 25, 2021. 


G. Enzian, J. J. Price, et al. Single-Phonon Addition and Subtraction to a Mechanical Thermal State. Phys. Rev. Lett. 126, 033601. Jan 21, 2021.



sabato 30 gennaio 2021

# gst: movers and shaker, the dynamics of granular matter

 << Granular materials are disordered systems often found in a far-from-equilibrium state. >> 

 << You can think of it like a beaker filled with loose sand, (..) At first there are big holes between the grains. So initially, it's easy for a grain to shift position by falling into an empty space. But as these spaces start to get smaller, it becomes less likely that a grain can fall through one. As the taps continue, it takes increasingly cooperative events to create the space necessary for more compaction. >> Stefan Boettcher. 

<< Previous research has shown a similar statistical pattern for the behavior of amorphous solids that don't form ordered crystals when moving from a liquid to a solid state, such as glass and many polymers. >> 

Carol Clark. Movers and shakers: New evidence for a unifying theory of granular materials. Emory University. Jan 08, 2021. 


Paula A. Gago, Stefan Boettcher. 
Universal features of annealing and aging in compaction of granular piles. 
PNAS. 117 (52) 33072-33076. doi: 10.1073/ pnas.2012757117. Dec 14, 2020. 




venerdì 29 gennaio 2021

# gst: expanding 'bubbles' of distortion in the nano lattice of a material, a glimpse of polarons

 << Polarons are fleeting distortions in a material's atomic lattice that form around a moving electron in a few trillionths of a second, then quickly disappear. As ephemeral as they are, they affect a material's behavior, >> 

 << When you put a charge into a material by hitting it with light, like what happens in a solar cell, electrons are liberated, and those free electrons start to move around the material, (..) Soon they are surrounded and engulfed by a sort of bubble of local distortion—the polaron—that travels along with them, (..)  Some people have argued that this 'bubble' protects electrons from scattering off defects in the material, and helps explain why they travel so efficiently to the solar cell's contact to flow out as electricity. >> Burak Guzelturk.

<< The hybrid perovskite lattice structure is flexible and soft—like a strange combination of a solid and a liquid at the same time, (..) and this is what allows polarons to form and grow. >> Aaron Lindenberg.

Glennda Chui. First glimpse of polarons forming in a promising next-gen energy material. SLAC National Accelerator Laboratory. Jan 04, 2021.


Burak Guzelturk, Thomas Winkler, et al.  Visualization of dynamic polaronic strain fields in hybrid lead halide perovskites. Nat. Mater. doi: 10.1038/ s41563-020-00865-5. 04 Jan 4, 2021.



mercoledì 27 gennaio 2021

# gst: apropos of 'strange' transitions to self-assemble into an egg; the coordinated elastic behavior to swirl in a vortex (D. melanogaster)

 << At the end of its first week of development, a striking change occurs in a fruit-fly egg cell. The cell’s internal fluid motion transitions from a disordered mix of small-scale flows to a single vortex that encompasses the entire cell. >> 

 << Given the fluid’s incompressibility, those forces can give rise to what the researchers call a  "swirling" instability, and the flow switches to a cell-spanning rotation. The threshold of molecular motor activity for the transition depends on the buckling of individual microtubules, which are treated as elastic rods. >> 

A Vortex in an Egg Cell. Physics 14, s1. Jan 13, 2021.  


David B. Stein, Gabriele De Canio, et al. Swirling Instability of the Microtubule Cytoskeleton. Phys. Rev. Lett. 126, 028103.  doi: 10.1103/ PhysRevLett.126.028103. Jan 13, 2021.