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lunedì 10 maggio 2021

# brain: learning on the fly (in D. melanogaster and mammals)

AA << have developed a new computational model that demonstrates a long sought after link between insect and mammalian learning (..)   Incorporating anatomical and functional data from recent experiments, Dr James Bennett and colleagues modelled how the anatomy and physiology of the fruit fly's brain can support learning according to the reward prediction error (RPE) hypothesis. >>️

<< The computational model indicates how dopamine neurons in an area of a fruit fly's brain, known as the mushroom body, can produce similar signals to dopamine neurons in mammals, and how these dopamine signals can reliably instruct learning. >>️

Learning on the fly. University of Sussex. May 7, 2021. 


Bennett, J.E.M., Philippides, A.,  Nowotny, T. Learning with reinforcement prediction errors in a model of the Drosophila mushroom body. Nat Commun 12, 2569. doi: 10.1038/ s41467-021-22592-4. May 7,  2021. 


Also

(+) keyword 'melanogaster' in FonT


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





sabato 8 maggio 2021

# gst: apropos of bubbles, the life of a surface bubble.

<< Who has never observed at the surface of a puddle under the rain one bubble that bursts instantly and another one that stays for more than 10 s?  >>️

<< Once a bubble has reached an interface, it adopts a static shape that is governed by the balance between the surface tension and buoyancy effects.  >>

<< To sum-up, (AA) have presented the state of the art concerning the prediction of the lifetime of surface bubbles. In general, the bubble unstability is linked to two facts: (i) the bubble cap is constituted by a thin film, whose thickness decreases along time due to both drainage and evaporation and (ii) this thin film is unstable and eventually bursts. (AA) have shown that the current understanding is that two different behaviors exist depending on whether the film thins until its thickness reaches a few hundreds of nanometers or bursts at higher thicknesses. In the first case, determinist models that describe the thinning of the film down to a rupture thickness of the order of tenth to hundreds of nanometers perform correctely to calculate the bubbles lifetime. In the second case, the presence of a fatal impurity within the film and its propension to break it being a more random process, lifetime distributions are much more spread and only stochastic models may capture the physical mechanism(s) at play. The scenario depends on whether or not surfactants are present to stabilise the thick film. >>

<< In absence of surfactants, the distribution of lifetimes is given by a Weibull distribution. The bursting mechanism available in the literature involves the diffusion of impurities in the film, which cause the film rupture. Film thinning due to evaporation is likely to be rather negligible in such experiments since its impact is small on thick films. >>

<< In presence of surfactants, the film is expected to thin until its thickness reaches a few tens of nanometers. The prediction of the bubble lifetime thus depends on our ability to predict the thinning rate of the film. It is fixed by the evaporation and the drainage. For tiny bubbles, no stable thin film appears and the evaporation is negligible. The lifetime is fixed by the approach velocity of the bubble to the bath. For bigger bubbles, evaporation and drainage must be taken into account. The evaporation is a constant rate, which depends on external conditions such as atmospheric humidity, on the diffusion/convection ratio and on the chemical potential of the solution. It has been shown that an accurate description of the evaporation rates necessitates to take into account the natural convection. >>

<< The drainage mechanism depends on the viscosity of the solution, on the bubble size and on the surfactants used to stabilise the interfaces. (AA) have identified three main mechanisms. For viscous bubbles, the cap is axisymmetric and the thickness decreases continuously from the bottom to the top of the bubble. The drainage is then expected to be exponential with time. In presence of surfactants, a pinch is expected to appear in the vicinity of the meniscus, which slows down the drainage. The destabilization of this pinch may lead to marginal regeneration, that in turn can affect the drainage. >>

<< Several references show that the drainage and evaporation rates are sufficient to predict the average lifetime of the surfaces bubbles in these different cases. >>

<< Many questions remain open and deserve to be addressed in a near future and (AA) try to list some of them below.
The mechanism at the origin of the eventual bursting of the film, whether they are thick (micrometers) or thin (tens of nanometers) is mostly unknown.
The marginal regeneration phenomenon, the dynamics of the pinch, the origin of its destabilisation and its contribution to drainage are under current investigation.
The impact of the chosen surfactants on bubble drainage and evaporation is crucial but remains an open question.
There is still a lack of data concerning the distributions observed. Additionally, there is no theoretical prediction of the distribution in the presence of surfactants stabilising the interface. >>️

Jonas Miguet, Florence Rouyer,  Emmanuelle Rio. The Life of a Surface Bubble. Molecules. 26(5): 1317.
doi: 10.3390/ molecules26051317. Mar 1,  2021. 


Also

keyword "bubble" in FonT




mercoledì 5 maggio 2021

# gst: when and how a levitating droplet sings (as a pipe)

<< Sprinkle water onto a very hot pan, and you may notice that the droplets evaporate surprisingly slowly. They stick around because of what’s called the Leidenfrost effect—a thin layer of vapor forms between the droplets and the hot surface, insulating them from the heat, and keeping them from boiling off immediately. (..) droplets of water in this Leidenfrost regime emit periodic sounds, or beats.  >>️

<< While emitting sounds, the droplets oscillated as pulsing stars whose points moved radially in and out. (..) this vapor-layer frequency matched the period of the beats, and (AA) therefore concluded that vapor escaping from beneath the droplet was responsible for producing the periodic sounds. >>️

<< the frequency of the sounds made by a droplet depended on the droplet’s size—following the model of an organ pipe, whose tone depends on the velocity of sound and the length of the pipe. This implies that the sound production mechanism in a Leidenfrost droplet is similar to that of a wind instrument. >>
Erika K. Carlson. The Sounds of Levitating Water Droplets. Physics 13, s148. Nov 19, 2020.


Tanu Singla,  Marco Rivera. Sounds of Leidenfrost drops. Phys. Rev. Fluids 5, 113604. doi: 10.1103/ PhysRevFluids.5.113604. Nov 19, 2020.



sabato 1 maggio 2021

# life: I'm sorry, but this image has no predictive value

this image has no predictive value;  the Bot (relatively omniscient) will indicate the direction;  the Human (mumble grumble) will not be able to do other than walk it ... you bet, it's just a matter of time, relatively short time ... Are You Ready?

the image from  https://twitter.com/LDO_CTIO   (screenshot taken on Feb 25th, 2021 09:55 CET)

keyword 'ai' | 'bot' in FonT



keyword 'ia' | 'ai' | 'robota' in Notes (quasi- stochastic poetry)




venerdì 30 aprile 2021

# gst: immediate 'shot', the three second time window in art, music, poems and language processing

<< Is there a universal time constant for poetic lines when people read them aloud or recite them by heart? Turner and Pöppel (1988) collected over 20 types of poetry, varying from East to West and from modern societies to indigenous cultures, and found a constant of ~3 s for the duration of poetic lines. >>️

<< This observation indicates a production– perception synchrony of ~3 s, which means that we not only tend to recite poems  (and speech in a more general sense; discussed later) with a 3-s pattern but also appreciate poems aesthetically within the same temporal frame. This temporal preference for a 3-s pattern and not a 1-s or a 10-s pattern, which linguistically would be possible, indicates presumably a profound evolutionary basis. The temporal modulation effect of the 3-s window on aesthetic appreciation may also motivate to look for other concepts and phenomena of the cognitive and neural basis of aesthetic perception in general and in detail, as has been partly already done for decision processes, the visual arts, and music (Avram et al., 2013; Bao et al., 2016; Bao et al., 2017; Park et al., 2014; Park et al., 2015; Pöppel, 1989a). >>

Xinchi Yu, Yan Bao. The three second time window in poems and language processing in general: Complementarity of discrete timing and temporal continuity.  PsyCh Journal. Vol 9, Issue 4 p. 429-443. doi: 10.1002/ pchj.390. Aug 26, 2020. 


<< the composer Peter Michael Hamel  (..) decided to compose a string quartet, which he called The Time Frame. This time window (the three second time window), which is an anthropological universal, provides an operative basis for effortless communication, empathic relationships to others, and it is the brain's way to integrate continuity and simultaneity of what is experienced in a complementary mode. >>️

Peter Michael Hamel. Through the self to music: The self as the creative origin for composing in time frames. Psych J. 10(2):249-253. doi: 10.1002/ pchj.446. Apr 12, 2021


Also 

Ramificata tinnula (di carmina fluitantia). Notes (quasi-stochastic poetry). Jun 09, 2005.


Elettrico Charlie (Seven come eleven). 
Notes (quasi-stochastic poetry). Feb 01, 2007. 


Il pseudomotore di Shostakovich. Notes (quasi-stochastic poetry). Nov 15, 2006. 


keyword 'jazz' in Notes (quasi-stochastic poetry)


FonT 

Queste considerazioni di Xinchi Yu e  Yan Bao potrebbero anche indicare una sorta di predisposizione neurofisiologica individuale all' 'immediato Satori' ... 









martedì 27 aprile 2021

# life: Occam's razor revisited, miss opportunities to improve through subtraction

<< A new study explains why people rarely look at a situation, object or idea that needs improving -- in all kinds of contexts -- and think to remove something as a solution. Instead, we almost always add some element, whether it helps or not. >>️

<< It happens in engineering design, which is my main interest, (..) But it also happens in writing, cooking and everything else -- just think about your own work and you will see it. The first thing that comes to our minds is, what can we add to make it better. Our paper shows we do this to our detriment, even when the only right answer is to subtract. Even with financial incentive, we still don't think to take away. >> Leidy Klotz.️

Why our brains miss opportunities to improve through subtraction. University of Virginia School of Engineering and Applied Science. Apr 7, 2021. 


Adams GS, Converse BA, et al. People systematically overlook subtractive changes. Nature 592, 258–261. doi: 10.1038/ s41586-021-03380-y. Apr 7,  2021.


Also

keyword 'occam' in FonT


keyword 'occam' in Notes (quasi-stochastic poetry)






sabato 24 aprile 2021

# gst: increase transport with disorder

<< Overcoming the detrimental effect of disorder at the nanoscale is very hard since disorder induces localization and an exponential suppression of transport efficiency. (AA) unveil novel and robust quantum transport regimes achievable in nanosystems by exploiting long-range hopping. (They) demonstrate that in a 1D disordered nanostructure in the presence of long-range hopping, transport efficiency, after decreasing exponentially with disorder at first, is then enhanced by disorder  [disorder-enhanced transport regime] until, counterintuitively, it reaches a disorder-independent transport regime, persisting over several orders of disorder magnitude in realistic systems. >>️

Nahum C. Chávez, Francesco Mattiotti, et al. Disorder-Enhanced and Disorder-Independent Transport with Long-Range Hopping: Application to Molecular Chains in Optical Cavities. Phys. Rev. Lett. 126, 153201. Apr 12,  2021.


Horacio M. Pastawski. Driving Transport with High Disorder. Physics 14, 57. Apr 12, 2021. 



keyword 'disordine' in Notes (quasi-stochastic poetry)