# life: hypothetical 'subtle variations' about three ancient neuro-cognitive models, the nomadic explorer, the nomadic owner, the farmer.

<< Prehistoric humans underwent three major migration events across Eurasia, influencing the genetic diversity of present-day Europe. These include the arrival of hunter-gatherers approximately 45,000 years ago, the expansion of Neolithic farmers from the Middle East around 11,000 years ago, and the rise of animal husbandry when steppe pastoralists migrated from the Pontic Steppe approximately 5,000 years ago. Each of these events represents a crucial period in human history that has shaped the genetic diversity observed in present-day Europe, although specific genetic and demographic details remain poorly characterized. >>️

Michael Attwaters. Ancient migration and the modern genome. Nat Rev Genet 25, 162. Feb 5, 2024. 

https://www.nature.com/articles/s41576-024-00702-4

Also: nomad, ctz entity, in https://www.inkgmr.net/kwrds.html

Keywords: life, hunter-gatherers, pastoralists, farmers

# life: it’s time to admit that ...

<< For too long, scientists have been content in espousing the lazy metaphor of living systems operating simply like machines, (..) Yet, it’s important to be open about the complexity of biology — including what we don’t know — because public understanding affects policy, health care and trust in science.  “So long as we insist that cells are computers and genes are their code,” writes Ball, life might as well be “sprinkled with invisible magic”. But, reality “is far more interesting and wonderful”, as he explains in this must-read user’s guide for biologists and non-biologists alike. >>️

Denis Noble. It’s time to admit that genes are not the blueprint for life. Nature. 626, 254-255 (2024). Feb 5,  2024. 

https://www.nature.com/articles/d41586-024-00327-x

Philip Ball. How Life Works: A User’s Guide to the New Biology. Pan Macmillan (2024). 

https://www.panmacmillan.com/authors/philip-ball/42387

Also: disorder, disorder & fluctuation, in https://www.inkgmr.net/kwrds.html  

Keywords: life, disorder, fluctuations

FonT: this point of view, published in the 70s-80s, would have made a damned impression. 

# 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