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giovedì 7 novembre 2019

# gst: multiple singularities by optical vortices (a 30y review)

<< Vortices are common phenomena that widely exist in nature, from quantum vortices in liquid nitrogen to ocean circulation and typhoon vortices and even spiral galaxies in the Milky Way. Vortices also exist in optics, the concept of which was first proposed by theoretical physicist Pierre Coullet and colleagues [Opt. Commun. 73, 403 (1989)] thirty years ago. Hitherto, owing to their amazing structures, optical vortices have engendered tremendous advanced applications such as optical tweezers, quantum entanglement, and nonlinear optics, throughout every branch of modern optics. >>

Commemorating 30 years of optical vortices: A comprehensive review. 
Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences. Nov 4, 2019.

https://m.phys.org/news/2019-11-commemorating-years-optical-vortices-comprehensive.html

Yijie Shen, Xuejiao Wang, et al. Optical vortices 30 years on: OAM manipulation from topological charge to multiple singularities. Light: Science & Applications volume 8, Article number: 90. Oct 2, 2019.

https://www.nature.com/articles/s41377-019-0194-2


mercoledì 6 novembre 2019

# behav: 'run and tumble' behavior (among bacteria)

<< Bacteria in groundwater move in surprising ways. They can passively ride flowing groundwater, or they can actively move on their own in what scientists call "run and tumble" behavior.  >>

AA << noted a distinct run (movement in one direction) followed by a tumble (a sudden, random change in direction). By calculating the length and timing of these movements, they could develop a simple Continuous Time Random Walk (CTRW) model to predict how the bacteria would move. When compared to current models for bacterial remediation, the CTRW model was better at predicting bacterial transport in many circumstances. The CTRW model is the first step in developing and testing new reactive transport models that incorporate bacterial transport behavior.  >>

Rishi Parashar. Calculating 'run and tumble' behavior of bacteria in groundwater. Environmental Molecular Sciences Laboratory. Oct 31, 2019. 

https://m.phys.org/news/2019-10-behavior-bacteria-groundwater.html  

Xueke Yang, Rishi Parashar, et al. On Modeling Ensemble Transport of Metal Reducing Motile Bacteria. Scientific Reports volume 9, Article number: 14638. Oct 10, 2019. 

https://www.nature.com/articles/s41598-019-51271-0

martedì 5 novembre 2019

# behav: adaptive synchronizations; the tendency to anticipate during auditory rhythms

<< Dancing and playing music require people to coordinate actions with auditory rhythms. In laboratory perception-action coordination tasks, people are asked to synchronize taps with a metronome. When synchronizing with a metronome, people tend to anticipate stimulus onsets, tapping slightly before the stimulus. The anticipation tendency increases with longer stimulus periods of up to 3500ms, but is less pronounced in trained individuals like musicians compared to non-musicians.  >>

Iran R. Roman, Auriel Washburn, et al.  Delayed feedback embedded in perception-action coordination cycles results in anticipation behavior during synchronized rhythmic action: A dynamical systems approach. PLoS Comput Biol 15(10): e1007371. doi: 10.1371/journal.pcbi.1007371. Oct 31, 2019.

https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1007371

Delayed neural communication may underlie anticipatory behaviors. Public Library of Science. Oct 31, 2019.

https://m.phys.org/news/2019-10-neural-underlie-anticipatory-behaviors.html

sabato 2 novembre 2019

# evol: apropos of our origin, the KhoeSan trunk of the human tree

<< Where was the evolutionary birthplace of modern humans? The East African Great Rift Valley has long been the favoured contender – until today. (AA) new research has used DNA to trace humanity’s earliest footsteps to a prehistoric wetland called Makgadikgadi-Okavango, south of the Great Zambezi River. >>

<< KhoeSan have the most diverse mitogenomes of anyone on Earth, which suggests their DNA most closely resembles that of our shared common ancestors. If we all sit on branches of the human family tree, then KhoeSan are the tree's trunk. >>

Vanessa Hayes. Humanity’s birthplace: why everyone alive today can call northern Botswana home. University of Sydney. Oct 28, 2019.

https://theconversation.com/humanitys-birthplace-why-everyone-alive-today-can-call-northern-botswana-home-125814

Eva K. F. Chan, Axel Timmermann, et al.  Human origins in a southern African palaeo-wetland and first migrations. Nature (2019) doi:10.1038/s41586-019-1714-1. Oct 28, 2019.

https://www.nature.com/articles/s41586-019-1714-1    


giovedì 31 ottobre 2019

# gst: spontaneous spin-sliding of volatile drops

<< When a volatile solvent droplet is deposited on a freely floating swellable sheet, it can spontaneously become lobed, asymmetric, and either spin, slide or move via a combination of the two.  This process of symmetry-breaking is a consequence of the solvent droplet swelling the membrane and its inhomogeneous evaporation from the membrane, coupled with the hydrodynamics within the droplet. By tuning the membrane thickness and the droplet size, (AA) find a critical threshold that determines the transition from a quiescent spherical cap state to a self-piloted motile state.>>

Aditi Chakrabarti, Gary P. T. Choi, L. Mahadevan. Spontaneous spin-sliding of volatile drops on swelling sheets. arXiv:1910.07064v1 [cond-mat.soft]  Oct 15, 2019. 

https://arxiv.org/abs/1910.07064   

mercoledì 30 ottobre 2019

# gst: the three-body problem approach using deep neural networks

AA << show that an ensemble of solutions obtained using an arbitrarily precise numerical integrator can be used to train a deep artificial neural network (..) that, over a bounded time interval, provides accurate solutions at fixed computational cost and up to 100 million times faster than a state-of-the-art solver. >>

Philip G. Breen, Christopher N. Foley,  et al. Newton vs the machine: solving the chaotic three-body problem using deep neural networks. arXiv: 1910.07291v1 [astro-ph.GA] Oct 16, 2019

https://arxiv.org/abs/1910.07291

A neural net solves the three-body problem 100 million times faster. By Emerging Technology from the arXiv. 
Oct 26, 2019. 

https://www.technologyreview.com/s/614597/a-neural-net-solves-the-three-body-problem-100-million-times-faster/

Also

keyword "three" in FonT    

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

keyword "three" in Notes      

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


lunedì 28 ottobre 2019

# brain: to test schizophrenia in human hair.

<< MPST gene expression (which leads to hydrogen sulphide production) was higher in postmortem brains from people with schizophrenia than in those from unaffected people. MPST protein levels in these brains also correlated well with the severity of premortem symptoms.  >>

AA << examined hair follicles from more than 150 people with schizophrenia and found that expression of MPST mRNA was much higher than people without schizophrenia. Even though the results were not perfect-indicating that sulfide stress does not account for all cases of schizophrenia-MPST levels in hair could be a good biomarker for schizophrenia before other symptoms appear. >>

<< Nobody has ever thought about a causal link between hydrogen sulfide and schizophrenia, (..) Once we discovered this, we had to figure out how it happens and if these findings in mice would hold true for people with schizophrenia. >> Takeo Toshikawa.

Biomarker for schizophrenia can be detected in human hair. Riken. Oct 28, 2019.

https://medicalxpress.com/news/2019-10-biomarker-schizophrenia-human-hair.html

Masayuki Ide, Tetsuo Ohnishi, et al. 
Excess hydrogen sulfide and polysulfides production underlies a schizophrenia pathophysiology. EMBO Mol Med (2019) e10695. doi: 10.15252/emmm.201910695. Oct 28, 2019.

https://www.embopress.org/doi/full/10.15252/emmm.201910695