# brain: the 'loosely balanced state' of cerebral cortex

<< Many studies have shown that the excitation and inhibition received by cortical neurons remain roughly balanced across many conditions. A key question for understanding the dynamical regime of cortex is the nature of this balancing. (..) loose balance, but not tight balance, can yield many nonlinear population behaviors seen in sensory cortical neurons, allow the presence of correlated variability, and yield decrease of that variability with increasing external stimulus drive as observed across multiple cortical areas. >>  

<< at least sensory, and perhaps all of, cortex operates in a regime in which the inhibition and excitation neurons receive are loosely balanced. This along with the supralinear input/output function of individual neurons and simple assumptions on connectivity explains a large set of cortical response properties. A key outstanding question is the computational function or functions of this loosely balanced state and the response properties it creates >>

Yashar Ahmadian, Kenneth D. Miller.  What is the dynamical regime of cerebral cortex?  arXiv:1908.10101v2 [q-bio.NC] Aug 28, 2019.   

https://arxiv.org/abs/1908.10101  

# gst: fingerprints of reality (2): the stormquake

AA << find that during large storms such as hurricanes and Nor'easters the interaction of long‐period ocean waves with shallow seafloor features located near the edge of continental shelves, known as ocean banks, excites coherent transcontinental Rayleigh wave packets in the 20 to 50 s period band. These "stormquakes" migrate coincident with the storms, but are effectively spatiotemporally focused seismic point sources with equivalent earthquake magnitudes that can be greater than 3.5. >>

Wenyuan Fan, Jeffrey J. McGuire, et al. Stormquakes. Geophysical Research Letters. Oct 14, 2019.    https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL084217  

Strong storms generating earthquake-like seismic activity. Florida State University. Oct 15, 2019.    https://m.phys.org/news/2019-10-strong-storms-earthquake-like-seismic.html 

Also  

fingerprints of reality: water drops that vibrate, flames that oscillate, and viscous fluids that form rivulets ...

FonT.  Dec 9, 2018.    https://flashontrack.blogspot.com/2018/12/gst-fingerprints-of-reality-water-drops.html   

# gst: counterintuitively, even complex processes can be hidden inside flat power spectra

<< Power spectral densities are a common, convenient, and powerful way to analyze signals. So much so that they are now broadly deployed across the sciences and engineering - from quantum physics to cosmology, and from crystallography to neuroscience to speech recognition. The features they reveal not only identify prominent signal-frequencies but also hint at mechanisms that generate correlation and lead to resonance. Despite their near-centuries-long run of successes in signal analysis, here (AA) show that flat power spectra can be generated by highly complex processes, effectively hiding all inherent structure in complex signals.  >>

P. M. Riechers, J. P. Crutchfield.  Fraudulent White Noise: Flat power spectra belie arbitrarily complex processes.   arXiv:1908.11405v1 [cond-mat.stat-mech] Aug 29, 2019.   https://arxiv.org/abs/1908.11405

# ai: the future where machines will test hypotheses on their own

<< Brian Nord imagines a future where machines test hypotheses on their own  (..) Nord has begun applying AI to problems in astronomy, such as identifying unusual astronomical objects known as gravitational lenses. (..)  He spoke to Physics about his recent projects and how he thinks AI, also known as machine learning, will change the way researchers do science. >>

Sophia Chen. Paving A Path for AI in Physics Research.  Physics 12, 108. Oct 3, 2019.    https://physics.aps.org/articles/v12/108  

Also

oops! artificial intelligence will kill self-employment. Oct 4, 2019.   https://flashontrack.blogspot.com/2019/10/ai-life-oops-artificial-intelligence.html

keyword "ai" in FonT:     https://flashontrack.blogspot.com/search?q=ai

# gst: chaotic dynamics modulate complex systems, even in the presence of extrinsic and intrinsic noise

AA << find that chaotic dynamics modulates gene expression and up-regulates certain families of low-affinity genes, even in the presence of extrinsic and intrinsic noise. Furthermore, this leads to an increase in the production of protein complexes and the efficiency of their assembly. Finally, (AA) show how chaotic dynamics creates a heterogeneous population of cell states, and describe how this can be beneficial in multi-toxic environments. >>

Mathias L. Heltberg, Sandeep Krishna, Mogens H. Jensen. On chaotic dynamics in transcription factors and the associated effects in differential gene regulation.  Nature Comm. volume 10, Article number: 71 Jan 8, 2019.   https://www.nature.com/articles/s41467-018-07932-1  

<< Chaos in bodily regulation can optimize our immune system according to a recent discovery made by researchers at the University of Copenhagen's Niels Bohr Institute. The discovery may prove to be of great significance for avoiding serious diseases such as cancer and diabetes.  >>

Chaos in the body tunes up your immune system. Niels Bohr Institute.
Jan 16, 2019.   https://m.medicalxpress.com/news/2019-01-chaos-body-tunes-immune.html

Also

'l'immaginifico "tracciante ... che svagola nella macina ...'    in:  2149 - onda di predazione (to knock seals off the ice). Notes. Dec 17, 2007.    https://inkpi.blogspot.com/2007/12/2149-onda-di-predazione-to-knock-seals.html

Also

never boring with chaos and tit-for-tat theories. F.on.T. Jun 12, 2016.  https://flashontrack.blogspot.com/2016/06/s-gst-never-boring-with-chaos-and-tit.html

# gst: exploring the lifespan of a liquid droplet

<< Current theories state that the droplet's diameter-squared decreases in proportion to time (classical law); however, this period only accounts for a small portion of the drop's evolution. As the diameter approaches the unobservable micro- and nano-scale, molecular dynamics have to be used as virtual experiments and these show a crossover to a new behaviour, with the diameter now reducing in proportion to time (nano-scale law). >>

<< It is fascinating that intuition based on everyday observations are a hindrance when attempting to understand nanoscale flows, so that, as in this research, one has to lean on theory to enlighten us. >>  James Sprittles.

The lifespan of an evaporating liquid drop. University of Warwick. Oct 10, 2019.     https://m.phys.org/news/2019-10-lifespan-evaporating-liquid.html

Rana A.S., Lockerby D.A., Sprittles J.E.  Lifetime of a Nanodroplet: Kinetic Effects and Regime Transitions. Phys. Rev. Lett. 123, 154501 Oct 9, 2019.     https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.154501   

# gst: retooling viruses

<< New research reveals that the way viruses were perceived in terms of their architecture will need to be retooled, because they are actually structured in many more patterns than previously understood. The findings could have significant impact on how they are classified, our understanding of how they form, evolve and infect hosts, and strategies to identify ways to design vaccines to target them. >>

Why viruses like Herpes and Zika will need to be reclassified, and its biotech impact. San Diego State University. Sep 27, 2019.    https://www.eurekalert.org/pub_releases/2019-09/sdsu-wvl092519.php  

<<  improved imaging techniques have revealed increasing numbers of viral outliers >>

<< The polyhedral layouts describing the quasiequivalent capsid structures in CK-theory (Caspar, D. L. & Klug, A. theory) also occur in other areas of science, (..) The conceptual framework for the classification of icosahedral and octahedral polyhedral layouts presented here is therefore of interest for a wide range of scientific disciplines beyond virology. >>

Reidun Twarock, Antoni Luque.  Structural puzzles in virology solved with an overarching icosahedral design principle. Nature Comm. volume 10, Article number: 4414 Sep 27, 2019.   https://www.nature.com/articles/s41467-019-12367-3