# gst: when turbulence is driven by a strongly compressive guide

<< it is not fully understood how shocks drive turbulence, in particular whether shock driving is a more solenoidal (rotational, divergence-free) or a more compressive (potential, curl-free) mode of driving turbulence. >>️

<< Here, (AA) use hydrodynamical simulations of a shock inducing turbulent motions in a structured, multi-phase medium. >>️

<< Using simulations in which a shock is driven into a multi-phase medium with structures of different sizes and Γ<1, (AA) find b∼1 for all cases, showing that shock-driven turbulence is consistent with strongly compressive driving. >>️

Saee Dhawalikar, Christoph Federrath,  et al. The driving mode of shock-driven turbulence. arXiv:2205.14417v1 [astro-ph.GA]. May 28, 2022. 

https://arxiv.org/abs/2205.14417

Also

keywords 'turbulence' in FonT

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

keywords 'turbolento' in Notes 

(quasi-stochastic poetry)

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

keyword 'waves' in FonT

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

keyword 'onda' in Notes 

(quasi-stochastic poetry)

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

keyword 'instability' | 'instabilities' in FonT

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

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

keyword 'instabile' in Notes 

(quasi-stochastic poetry)

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

Keywords: gst, turbulence, instability, waves, shock waves

# behav: cognitive maps to get out of trouble, a jumping behaviour could be a goal-directed behaviour (in guppies, Poecilia reticulata).

<< Spatial cognitive abilities allow individuals to remember the location of food patches, predator hide-outs, or shelters. Animals typically incorporate learnt spatial information or use external environmental cues to navigate their surroundings. A spectacular example of how some fishes move is through aerial jumping. >>️

<< what information such re-orientation behaviour during jumping is based on remains enigmatic. Here (AA) combine a lab and field experiment to test if guppies (Poecilia reticulata) incorporate learnt spatial information and external environmental cues (visual and auditory) to determine where to jump. >>

AA << show that in unfamiliar entrapments guppies direct their jumps by combining visual and auditory cues, while in familiar entrapments they use a cognitive map. (..) jumping behaviour is a goal-directed behaviour, guided by different sources of information and involving important spatial cognitive skills. >>️️

Hannah de Waele, Catarina Vila Pouca, et al. Jumping out of trouble: Evidence for a cognitive map in guppies (Poecilia reticulata).  bioRxiv. doi: 10.1101/ 2022.03.30.486400. Mar 30, 2022.

https://www.biorxiv.org/content/10.1101/2022.03.30.486400v1

Also

Voli a casaccio. Notes (quasi-stochastic poetry). Oct 01, 2006. 

https://inkpi.blogspot.com/2006/10/2066-voli-casaccio.html

the flexible mental maps of flies. FonT. Nov 21, 2019. 

https://flashontrack.blogspot.com/2019/11/brain-flexible-mental-maps-of-flies.html

Keyword: behav, cognition, jumping behaviour, aerial jumping

# gst: perform statistics of rare events in stochastic processes by defining stochastic bridges from fixed start and end points.

<< The numerical quantification of the statistics of rare events in stochastic processes is a challenging computational problem. (AA) present a sampling method that constructs an ensemble of stochastic trajectories that are constrained to have fixed start and end points (so-called stochastic bridges). (AA) then show that by carefully choosing a set of such bridges and assigning an appropriate statistical weight to each bridge, one can focus more processing power on the rare events of a target stochastic process while faithfully preserving the statistics of these rare trajectories. >>

Javier Aguilar, Joseph W. Baron, et al. 

Sampling rare trajectories using stochastic bridges. Phys. Rev. E 105, 064138. Jun 30, 2022.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.105.064138

Keywords: stochasticity, stochastic processes, stochastic bridges, large deviations, rare trajectories, rare event statistics.

# life: sull'improvviso risveglio da sonni fanciulli ...

Risvegliati improvvisamente, bruscamente, irreversibilmente da sonni fanciulli, fantasmatici, campati in aria, dal petroliere guerriero Mr Vlad ( Vladimir Vladimirovic Putin   https://it.m.wikipedia.org/wiki/Vladimir_Putin ) ecco qui qualche assolutamente ipotetica macro conseguenza (a,b,c) a cascata per l'Europa (Italia inclusa) che accompagnerebbe l'Europa graziosamente fino al prossimo secolo,  e forse anche oltre; forse chissà quante decine se non centinaia di generazioni potrebbero esserne loro malgrado coinvolte.

(a) 

Un ruolo di possibile mediatore della Russia tra Occidente e Oriente, tra Europa e Cina si è evaporato, dissolto, dopo le in.credibili  performance del guerriero dalle latte rugginose Mr Vlad, fautore di approccio eugenetico arcaico.

In sintesi:  Ti accucci meco? Vivrai (i.e. sopravviverai, forse). Non ti accucci? Sarai svuotato, duplicato, cancellato, terminato, fisicamente terminato; Te medesimo, la Famiglia, l'eventuali tuoi Amici, Compari di merenda e Ospiti di casa (gatto, cane, canarini in gabbietta, senza escludere i topi del solaio e della cantina). E' solo questione di tempo ... 

Qui la strategia di Mr Vlad sembra superare quella più sociale, benevola, compassionevole (se così si può dire) dell'altrettanto arcaico approccio metodologico Abanese diretto verso il colpevole di indicibile SAC Sgarro-Al-Clan (Codice Kanun o Kanuni, detto anche Canone di Leke Dukagjini, graziosamente riprodotto in qualche sua parte anche altrove, perfino in contesti insospettabili).

In sintesi:  hai sgarrato il Codice perciò sei colpevole; stai confinato tra le mura domestiche e vivrai; esci e verrai immediatamente terminato. Solo in qualche particolare caso potrai uscire e sopravvivere se e solo se accompagnato dalla femmina.

(b) 

Indipendentemente dalla afferenza alla NATO, all'ONU, etc, alle politiche di governo locale, gli Stati dell'Europa (Russia compresa), per la propria sopravvivenza giornaliera, pagheranno  Royalties a Cina per l'uso di qualsivoglia tech. Per capirsi: sarà indispensabile pagare Royalties alla Cina anche per servirsi di hitech-WC pei giornalieri fisiologici indispensabili pissiolamenti. 

A margine: si potrebbe ipotizzare la diffusione, timida e via via sempre più veloce, a progressione autocatalitica, di immagini di Mr Richard Nixon ( Potus  1969-1974 ) ( https://it.m.wikipedia.org/wiki/Richard_Nixon ) ( https://it.m.wikipedia.org/wiki/Comunicato_di_Shanghai ) che potrebbe essere indicato dal Gov Cinese come "Nixon, vero autentico indimenticabile amico occidentale della nazione" 

(c) 

Chi saranno gli esattori? I Cinesi no, non penso proprio; probabilmente l'incarico di riscuotere le giornaliere ricche Royalties verrà conferito dalla Cina a Stati e Popoli dell'Africa sub-Sahariana.  Questo approccio esprimerebbe componenti legali difficilmente contestabili e se ben giocato rifletterebbe perfino componenti etiche, di giustizia sociale.

Ovviamente (a,b,c) è un sunto di  ipotetico vaticinio, perciò assolutamente generico, soggettivo, allo stato indimostrabile.  

Codice Kanun. Vers. 14 Set 2021 14:30

by Andrys8. 

 https://it.m.wikipedia.org/wiki/Kanun

Eugenetica 

 https://it.m.wikipedia.org/wiki/Eugenetica  

Anche

keyword 'naked' in FonT

(qui una incredibile convergenza)

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

Anche

Immagini #CTZ, cicliche fantasmatiche pervasive visioni ricorrenti. FonT. Jun 29,  2019.

https://flashontrack.blogspot.com/2019/06/brain-immagini-ctz-cicliche.html

JARexit: the ironic probabilistic upshot of the itinerant, escaping IR77, Promobot. FonT. Jun 25, 2016.

https://flashontrack.blogspot.com/2016/06/s-bot-jarexit-ironic-probabilistic.html

PS: l'immagine senz'altro suggestiva "Risvegliati improvvisamente, bruscamente, irreversibilmente da sonni fanciulli, fantasmatici, campati in aria," meriterebbe una Nota poetica, quasistocastica perfino ( https://inkpi.blogspot.com ), ma mi astengo. 

Keywords: life, War, Vladimir Putin, Russia, Ucraina, Ukraine, Cina, China, Europa, Europe, vaticinio, forecast

# astro: eight new echoing black hole binaries (in Milky Way)

<< Scattered across our Milky Way galaxy are tens of millions of black holes—immensely strong gravitational wells of spacetime, from which infalling matter, and even light, can never escape. Black holes are dark by definition, except on the rare occasions when they feed. As a black hole pulls in gas and dust from an orbiting star, it can give off spectacular bursts of X-ray light that bounce and echo off the inspiraling gas, briefly illuminating a black hole's extreme surroundings. >>

<< In a study appearing (..) in the The Astrophysical Journal, (AA) report (..) eight new echoing black hole binaries in our galaxy. Previously, only two such systems in the Milky Way were known to emit X-ray echoes. >>️

 << Kara (Erin Kara) and her colleagues are using X-ray echoes to map a black hole's vicinity, much the way that bats use sound echoes to navigate their surroundings. (..)  As a side project, Kara is working with MIT education and music scholars, Kyle Keane and Ian Condry, to convert the emission from a typical X-ray echo into audible sound waves. >>️️

Jennifer Chu. Search reveals eight new sources of black hole echoes. MIT.  May 2, 2022. 

https://phys.org/news/2022-05-reveals-sources-black-hole-echoes.html

https://youtu.be/iIeIag2Ji8k

Jingyi Wang, Erin Kara, et al. The NICER "Reverberation Machine": A Systematic Study of Time Lags in Black Hole X-Ray Binaries. ApJ. 930, 18. May 2, 2022. 

https://iopscience.iop.org/article/10.3847/1538-4357/ac6262

Also

keyword 'black hole' in FonT

https://flashontrack.blogspot.com/search?q=black+hole

keyword 'waves' in FonT

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

keyword 'onda' in Notes 

(quasi-stochastic poetry)

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

Keywords: astro, black hole, echoes, waves

# gst: non-trivial behaviors of a rotating (physical) double pendulum

<< The double pendulum, a simple system of classical mechanics, is widely studied as an example of, and testbed for, chaotic dynamics. In 2016, Maiti et al. studied a generalization of the simple double pendulum with equal point-masses at equal lengths, to a rotating double pendulum, fixed to a coordinate system uniformly rotating about the vertical. In this paper, (AA) study a considerable generalization of the double pendulum, constructed from physical pendula, and ask what equilibrium configurations exist for the system across a comparatively large parameter space, as well as what bifurcations occur in those equilibria. >>️

<< the non-trivial bifurcation (AA) have found (..), may actually be rightly understood as three additional bifurcations: there is a narrow region, approximately the ‘crease’ of the surface in Fig. 5, within which a vertical line (..) intersects the surface three times; (..). Thus three non-trival bifurcations would be expected in the corresponding bifurcations plots. >>️

Jonathan Tot, Robert H. Lewis. On the Equilibria and Bifurcations of a Rotating Double Pendulum. arXiv:2204.12437v2 [math.DS]. May 7, 2022. 

https://arxiv.org/abs/2204.12437

Also

keyword 'pendulum' in FonT

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

keyword 'pendolo' | 'pendola' in Notes

(quasi-stochastic poetry)

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

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

Keywords: gst, pendulum, double pendulum, behavior, chaos 

# gst: even tight-binding billiards could exhibit chaotic behaviors

<< Recent works have established universal entanglement properties and demonstrated validity of single-particle eigenstate thermalization in quantum-chaotic quadratic Hamiltonians. However, a common property of all quantum-chaotic quadratic Hamiltonians studied in this context so far is the presence of random terms that act as a source of disorder. >>

AA << introduce tight-binding billiards in two dimensions, which are described by non-interacting spinless fermions on a disorder-free square lattice subject to curved open boundaries. >>

They <<  show that many properties of tight-binding billiards match those of quantum-chaotic quadratic Hamiltonians (..) these properties indeed appear to be consistent with the emergence of quantum chaos in tight-binding billiards. This statement nevertheless needs to be taken with some care since there exist a sub-extensive (in lattice volume) set of single-particle eigenstates that are degenerate in the middle of the spectrum at zero energy (i.e., zero modes), for which the agreement with RMT (random matrix theory) predictions may not be established. >>

Iris Ulcakar, Lev Vidmar. Tight-binding billiards. arXiv:2206.07078v1 [cond-mat.stat-mech]. Jun 14, 2022. 

https://arxiv.org/abs/2206.07078

Also

keyword 'billiard' in FonT

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

keyword 'chaos' | 'chaotic' in Font

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

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

keyword 'caos' | 'caotico' in Notes (quasi-stochastic poetry)

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

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

keywords: gst, billiard, chaos, chaotic behavior