# gst: apropos of vibrating pivots, driving a damped coplanar double pendulum.

AA << present results of linear and nonlinear motions of a parametrically driven coplanar double pendulum with velocity-dependent damping. The equations of motion of a damped double pendulum of unequal masses with its pivot vibrated vertically are different from those obtained under gravity modulation. 

Linear stability analysis shows that tongue-shaped marginal stability curves divide the plane of driving parameters into multiple regions of subharmonic and harmonic instabilities. The instability zones for one normal mode overlap with those for the other. 

The double pendulum may oscillate or rotate about its pivot harmonically or subharmonically. The limit cycles corresponding to the normal mode oscillations of a double pendulum of equal masses are squeezed into a line in its configuration space. 

For unequal masses, two marginal curves for subharmonic instabilities merge to form a double-well shaped curve in the presence of damping, which is qualitatively new. The pendulum shows driving amplitude sensitive multi-period complex oscillations for driving parameters near the extrema of the merged instability zones and boundaries of the overlapping zones. 

For larger driving amplitude, the pendulum shows subharmonic, harmonic or chaotic rotations. >>

️

Rebeka Sarkar, Krishna Kumar, Sugata Pratik Khastgir. Parametrically driven damped coplanar double pendulum. arXiv:2208.03292v1 [physics.class-ph]. Aug 2, 2022. 

https://arxiv.org/abs/2208.03292

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, instability, chaos, chaotic rotations

# gst: apropos of transitions, evaporating binary microdroplets with phase segregation

<< Phase segregation triggered by selective evaporation can emerge in multicomponent systems, leading to complex physiochemical hydrodynamics. Recently, Li et al. (2018) and Kim & Stone (2018) reported a segregative behavior (i.e., demixing) in an evaporating binary droplet. In this work, by means of experiments and theoretical analysis, (AA) investigate the flow dynamics after the occurrence of the phase segregation. >>

<< First, (AA) experimentally reveal the overall physiochemical hydrodynamics of the evaporation process, including the segregative behavior and the resulting flow structure close to the substrate. By quantifying the evolution of the radial flow, (they) identify three successive life stages of the evaporation process. >>

<< At Stage I, a radially outward flow is observed. It is driven by the Marangoni effect. At the transition to Stage II, the radial flow partially reverses, starting from the contact line. This flow breaks the axial symmetry and remarkably is driven by the segregation itself. Finally at Stage III, the flow decays as the evaporation gradually ceases. At this stage the segregation has grown to the entire droplet, and the flow is again controlled by the Marangoni effect. The resulting Marangoni flow homogenizes the distribution of the entrapped volatile water over the whole droplet. >>️

Yaxing Li, Pengyu Lv, et al. Physiochemical hydrodynamics of the phase segregation in an evaporating binary microdroplet.arXiv:2208.07861v1 [physics.flu-dyn]  Aug 16, 2022.

https://arxiv.org/abs/2208.07861

Marangoni effect. 

https://en.m.wikipedia.org/wiki/Marangoni_effect   

https://youtu.be/vGb6t5Gfq6s   

Also

keyword 'drop' | 'droplet' in FonT

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

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

Keywords: gst, droplet, transition, evaporation, phase transition, phase segregation, Marangoni flow

# gst: size, location and shape of interfacial nanobubbles can be tuned by nanostructures.

<< the nucleation mechanism of spontaneously generated NBs (nanobubbles) at solid-liquid interfaces of immersed nanostructured hydrophobic surfaces is studied. Depending on the size and density of the surface nanostructures, NBs with different size and density were reproducibly and deterministically obtained. >>️

moreover, << air entrapment experiments on a porous PS (coated polystyrene) surface covered with irregular nanopores show that also the shape of NBs can also be tuned by surface nanostructures, due to their pinning effect. It is thus feasible to tune NB size, position, and even morphology by varying surface nanostructures. >>️

Yuliang Wang, Xiaolai Li, et al. Entrapment of Interfacial Nanobubbles on Nano Structured Surfaces. arXiv:2208.08181v1 [physics.flu-dyn]. Aug 17, 2022.

https://arxiv.org/abs/2208.08181

Also

keyword "bubble" in FonT

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

Keywords: gst, nano, bubble, tune, pinning effect️

# life; the hypothesis of early treatment (at home) of the virus sars-cov-2

Figure 1 - Proposed maladaptive hyperinflammatory response to SARS-CoV-2 infection (Perico N, Cortinovis M, Suter F, Remuzzi G. (2022))

<< A few observational studies have tested NSAIDs [non-steroidal anti-inflammatory drugs] (especially  relatively selective COX-2 inhibitors), often as part of multipharmacological protocols, for early outpatient treatment of COVID-19. The findings from these studies are promising and point to a crucial role of NSAIDs for the at-home management of people with initial COVID-19 symptoms. >>

<< Celecoxib, ibuprofen, and nimesulide should be avoided in children younger than 12 years, whereas aspirin should be taken only under prescription and at the dose recommended by the family doctor. >>️

️

Norberto Perico, Monica Cortinovis, Fredy Suter, Giuseppe Remuzzi. Home as the new frontier for the treatment of COVID-19: the case for anti-inflammatory agents. The Lancet Infectious Diseases. doi: 10.1016/ S1473-3099(22)00433-9. Aug 25, 2022. 

https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(22)00433-9/fulltext

FonT

therefore the deadly infection by sars-cov-2 that has generated so much suffering,  pain, and dead everywhere it is recently hypothesized that it could easily be treated at home (an early treatment) with some success.

Also

keywords 'covid-19' and 'NSAIDs' in PubMed

https://pubmed.ncbi.nlm.nih.gov/?term=covid-19+NSAIDs&filter=datesearch.y_1

Also

aproposito di '1or2achoos' (da Wuhan (?)) ... FonT. Jul 13  2022.

https://flashontrack.blogspot.com/2022/07/life-aproposito-di-1or2achoos-da-wuhan.html

Keywords: virus, coronavirus,  sarscov2, 2019ncov, covid19, 1or2achoos

# gst: vortex solitons in twisted circular waveguide arrays.

AA << address the formation of topological states in twisted circular waveguide arrays and find that twisting leads to important differences of the fundamental properties of new vortex solitons with opposite topological charges that arise in the nonlinear regime. >>️

They << find that such system features the rare property that clockwise and counter-clockwise vortex states are nonequivalent. >>️

Liangwei Dong, Yaroslav V. Kartashov, et al. Vortex solitons in twisted circular waveguide arrays. arXiv:2208.05049v1 [physics.optics]. Aug 9, 2022.

https://arxiv.org/abs/2208.05049

Also

keyword 'solitons' in Font

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

keyword 'vortex' in FonT

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

keyword 'vortice' in Notes

 (quasi-stochastic poetry)

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

Keywords: gst, solitons, vortex,  clockwise vortex, counter-clockwise vortex, waves

# art: pictures of the floating world, a guide to making shadow puppets

<< Hiroshige (Utagawa Hiroshige) lived in the 19th century, the end of the classical period of ukiyo-e, the art of woodblock-printed “pictures of the floating world.” In that time he became one of the form’s last masters, having cultivated not just a high level of artistic skill but a formidable productivity. In total, Hiroshige produced more than 8,000 works. >>️

<< But his mastery encompassed more than the urban and rural landscapes of his homeland, as evidenced by this much humbler project: a set of omocha-e, or instructional pictures for children, explaining how to make shadow puppets. >>️

Hiroshige, Master of Japanese Woodblock Prints, Creates a Guide to Making Shadow Puppets for Children (1842). Art, History. Jul 6th, 2021. 

https://www.openculture.com/2021/07/hiroshige-shadow-puppets.html  

Utagawa Hiroshige. Art Institute of Chicago. 

https://www.artic.edu/artists/34946/utagawa-hiroshige

Also

keyword 'fluttuante' in Notes

(quasi-stochastic poetry)

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

keyword 'floating' in FonT

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

keyword 'onda' in Notes 

(quasi-stochastic poetry)

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

keyword 'waves' in FonT

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

Keywords: arts, puppets, shadow puppets, floating worlds, waves

# gst: rare transitions in noisy net scenarios

AA << study small white noise perturbations of planar dynamical systems with heteroclinic networks in the limit of vanishing noise. (They)  show that the probabilities of transitions between various cells that the network tessellates the plane into decay as powers of the noise magnitude. (They) show that the most likely scenario for the realization of these rare transition events involves spending atypically long times in the neighborhoods of certain saddle points of the network. >>️

Yuri Bakhtin, Hong-Bin Chen, Zsolt Pajor-Gyulai. Rare transitions in noisy heteroclinic networks. arXiv: 2205.00326v1 [math.PR]. Apr 30, 2022.    https://arxiv.org/abs/2205.00326

Also

keyword 'noise'  in FonT 

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

keyword 'rumore'  in Notes

(quasi-stochastic poetry)

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

Keywords: gst, transitions, networks, heteroclinic networks, noise