# gst: droplets scoot like caterpillars.

<< From swells in an ocean to ripples in a puddle, the shearing effect of wind blowing over a liquid is visible at all scales. This shear determines the interactions between Earth’s atmosphere and its surface water and, researchers now explain, the movement of liquid droplets that crawl up and down the window of a moving car in the rain. In a series of experiments, (AA) show that airflow triggers surface waves that cause such droplets to crawl like caterpillars before they break apart. >>️

<< At first, the airflow across the droplet’s surface caused the droplet to extend into an oval shape. The droplet also began to tilt, with the liquid piling up at the droplet’s downwind edge. When the drag force exerted by the airflow overcame the capillary force between the glycerin and the glass, the droplet began to slide and to stretch out even more. Surface waves then developed on the elongated droplet and traveled toward its leading edge. The waves induced a stable caterpillar-like motion, with the droplet stretching and contracting along its length. Eventually, beyond a threshold length that depended on the droplet’s volume, the caterpillar was no longer able to withstand the shearing force and broke into several droplets. >>️

AA << say that the behavior follows the same pattern as that of an elongated droplet sliding along an incline. >>

️

Rachel Berkowitz. Droplets Scoot Like Caterpillars. Physics 16, s110. Sep 1, 2023.

https://physics.aps.org/articles/v16/s110  

A. Chahine, J. Sebilleau, R. Mathis, D. Legendre. Caterpillar like motion of droplet in a shear flow. Phys. Rev. Fluids 8, 093601. Sep 1, 2023.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.093601

Also: drop, bubble, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drop, droplet, droploid, bubble, transition

# brain: arterial pressure pulsations could modulate neuronal activity.

<< Spontaneous slow oscillations have been described in the rat olfactory bulb local field potential, even in the absence of respiration. What is the origin of these oscillations? >>

AA << discovered a subpopulation of neurons within the olfactory bulb that can directly sense cardiovascular pressure pulsations (..). The modulation of their excitability is transduced by mechanosensitive ion channels. >>

<< Thus, there exists a fast pathway for the interoception of heartbeat whereby arterial pressure pulsations within the brain modulate neuronal activity. >> Peter Stern. ️

Luna Jammal Salameh, Sebastian H. Bitzenhofer, et al. Blood pressure pulsations modulate central neuronal activity via mechanosensitive ion channels. Science. Vol 383, Issue 6682. Feb 2, 2024. 

https://www.science.org/doi/10.1126/science.adk8511

img: https://www.science.org/cms/10.1126/science.adk8511/asset/76a1eaf8-61d3-4233-bc2a-be2276f367cd/assets/images/large/science.adk8511-fa.jpg

Also: brain, pnei, soliton, in https://www.inkgmr.net/kwrds.html  

Keywords: brain, pnei, olfactory bulb, spontaneous slow oscillations, wave, soliton

# life: mimesis, ambiguity, noise, when an entity is master of disguise.

<< At every stage in their lives, from egg to adult, leaf and stick insects prove to be prey that can trick their predators. >>️

Allie Yang. These insects are masters of disguise—even before hatching. nationalgeographic.com. Oct 17, 2023.

https://www.nationalgeographic.com/animals/article/phasmids-stick-leaf-insects-eggs-camouflouge

Also: mimesis, in Notes (quasi-stochastic poetry)

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

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

Also: noise, metamorphosis, in https://www.inkgmr.net/kwrds.html

Keywords: mimesis, disguise, ambiguity, noise, metamorphosis, two-faced Janus

# gst: feedback systems with switches that actuate after a preset delay.

AA << study the dynamics of a piecewise-linear second-order delay differential equation that is representative of feedback systems with relays (switches) that actuate after a fixed delay. The system under study exhibits strong multirhythmicity, the coexistence of many stable periodic solutions for the same values of the parameters. >>

AA << are able to show that slowly oscillating solutions are always stable if they exist. (They) also demonstrate the coexistence of stable periodic solutions with quasiperiodic solutions. >>

Lucas Illing, Pierce Ryan, Andreas Amann. ️Dynamics of a time-delayed relay system. Phys. Rev. E 109, 014223. Jan 23, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.014223

Keywords: gst, feedback, relay, switch

# gst: transitions in disordered medium.

AA << study computationally the dynamics of forced, Brownian particles through a disordered system. As the concentration of mobile particles and/or fixed obstacles increase, (AA) characterize the different regimes of flow and address how clogging develops. >>️

AA << show that clogging is preceded by a wide region of anomalous transport, characterized by a power law decay of intermittent bursts. (..) this abnormal flow region is characterized by a coexistence between mobile and arrested particles, and their relative populations change smoothly as clogging is approached. >>

️

Sergi G. Leyva, Ignacio Pagonabarraga. Clogging transition and anomalous transport in driven suspensions in a disordered medium. Phys. Rev. E 109, 014618. Jan 31, 2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.014618

img:  https://twitter.com/PhysRevE/status/1753068208586711072   

Also: transition, particle, disorder, in https://www.inkgmr.net/kwrds.html

Keywords: gst, transition, particle, disorder

# life: a new exception within the FDA Cures Act Informed Consent, the intriguing concept of 'Minimal Risk Clinical Investigations'.

<< The Food and Drug Administration (FDA, the Agency, or we) is issuing a final rule to amend its regulations to implement a provision of the 21st Century Cures Act (Cures Act). This final rule allows an exception from the requirement to obtain informed consent when a clinical investigation poses no more than minimal risk to the human subject and includes appropriate safeguards to protect the rights, safety, and welfare of human subjects. The final rule permits an institutional review board (IRB) to waive or alter certain informed consent elements or to waive the requirement to obtain informed consent, under limited conditions, for certain FDA-regulated minimal risk clinical investigations. >>️

Institutional Review Board Waiver or Alteration of Informed Consent for Minimal Risk Clinical Investigations. A Rule by the Food and Drug Administration on 12/21/2023. federalregister.gov 

https://www.federalregister.gov/documents/2023/12/21/2023-27935/institutional-review-board-waiver-or-alteration-of-informed-consent-for-minimal-risk-clinical

FonT:  'Minimal Risk Clinical Investigations (MRCI)': here are intriguing both (i) the scientific formalization of the operational methods decided (case by case) by the FDA about MRCI and (ii) the possible strategies - if at least one exists - for avoiding the 'multitude of unaware' from this type of interception.

Also: Are you ready for all this?, in https://www.inkgmr.net/kwrds.html

Also: evitare (avoid), in Notes (quasi-stochastic poetry)  https://inkpi.blogspot.com/search?q=evitare

Also: avoid, in FonT https://flashontrack.blogspot.com/search?q=avoid

Also: Robert F. Kennedy's opinion on the issue https://twitter.com/RobertKennedyJr/status/1752126207821271080  

Keywords: life, FDA, informed consent, risk, minimal risk, minimal risk clinical investigations, avoidance, 1or2achoos, are you ready

# gst: analogy between quasi-2D and 3D liquid drops.

<< Liquid drops are everywhere around us and important in numerous technological applications. Here, (AA) demonstrate a quasi-two-dimensional (Q2D) analogy to the regular, often close to axisymmetric, three-dimensional (3D) drops. >>️

<< The Q2D drops are created by confining liquids between vertical walls, leading to formation of low aspect ratio capillary bridges that are deformed by gravity. When stationary, the Q2D drops adopt projected shapes that are analogous to 3D sessile drops, ranging from circular drops to puddles. >>️

<< When moving, the Q2D drops exhibit capillary and fluid mechanical behaviours analogous to 3D drops, including impacts and sliding on pseudo-surfaces. The Q2D drops also exhibit considerably more complex phenomena such as levitation, instabilities and pattern formation when subjected to external electric, magnetic and flow fields -- all seen also in regular 3D drops. >>️

<< 3D-Q2D analogy suggests that the diverse and often complicated phenomena observed in 3D drops can be studied in the Q2D geometry, >>

️

Tytti Kärki, Into Pääkkönen, et al. Quasi-Two-Dimensional Drops. arXiv: 2401.11845v1 [physics.flu-dyn]. Jan 22, 2024.

https://arxiv.org/abs/2401.11845

Also: drop, analogy, in https://www.inkgmr.net/kwrds.html

Keywords: gst, drop, droplet, droploid, analogy