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Visualizzazione dei post in ordine di pertinenza per la query knots. Ordina per data Mostra tutti i post
Visualizzazione dei post in ordine di pertinenza per la query knots. Ordina per data Mostra tutti i post

sabato 25 maggio 2024

# gst: exotic geometries, a Janus trefoil knot, which rotates as it swims forwards.


AA << present an asymptotic theory for solving the dynamics of slender autophoretic loops and knots. >>️

They << elucidate the behavior of many exotic active particle geometries, such as a bumpy uniformly active torus that spins and a Janus trefoil knot, which rotates as it swims forwards. >>️

Panayiota Katsamba, Matthew D. Butler, et al. Slender phoretic loops and knots. Phys. Rev. Fluids 9, 054201. May 10, 2024. 

Also: keywords janus, knots, particle, in FonT





Keywords: janus, loops & knots, particles


mercoledì 20 gennaio 2016

# s-phys: knotted solitary waves: the begin

<< a team of physicists (..) has found a way to create knotted solitary waves, or knot solitons, in a quantum-mechanical field >>

<< Knots are defined mathematically as closed curves in 3D space. A knot soliton consists of an infinite number of rings, each linked with all of the others to generate a toroidal structure >>

<< This is the beginning of the story of quantum knots >>

http://www.sci-news.com/physics/physicists-create-quantum-knots-03569.html

D. S. Hall, M. W. Ray, et al. Tying quantum knots. Nature Physics (2016) doi:10.1038/nphys3624

http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3624.html

venerdì 11 maggio 2018

# gst: the dance of complex knots (in DNA), from mobile to jammed states

AA << show for the first time experimentally that knots can go from a mobile to a jammed state by varying an applied strain rate, and that this jamming is reversible >>

Alexander R. Klotz, Beatrice W. Soh, and Patrick S. Doyle. Motion of Knots in DNA Stretched by Elongational Fields.  Phys. Rev. Lett. 120, 188003. May 3, 2018.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.188003

Anne Trafton. Chemical engineers discover how to control knots that form in DNA molecules. Massachusetts Institute of Technology. May 3, 2018.

https://m.phys.org/news/2018-05-chemical-dna-molecules.html

sabato 6 ottobre 2018

# gst: periodic oscillations of flexible knots

AA << study the dynamics of knotted deformable closed chains sedimenting in a viscous fluid. (..) trefoil and other torus knots often attain a remarkably regular horizontal toroidal structure while sedimenting, with a number of intertwined loops, oscillating periodically around each other. (..) this motion (..) is accompanied by a very slow rotation around the vertical symmetry axis. (..) this oscillating mode of the dynamics can spontaneously form even when starting from a qualitatively different initial configuration. (..) the oscillating modes are usually present as transients or final stages of the evolution, depending on chain aspect ratio and flexibility, and the number of loops. >>

Magdalena Gruziel, Krishnan Thyagarajan, et al. Periodic Motion of Sedimenting Flexible Knots. Phys. Rev. Lett. 121, 127801 Sep 18,  2018. doi: 10.1103/PhysRevLett.121.127801.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.127801

The periodic motion of flexible knots, and the connection to DNA. University of Warsaw. Sep 26, 2018.

https://m.phys.org/news/2018-09-periodic-motion-flexible-dna.html

lunedì 21 agosto 2023

# gst: neural networks know their knots.


<< The use of neural networks in physics is booming. Recently, the tool has helped researchers uncover everything from new magnetic materials (..) to ways to reduce noise in electron beams produced at synchrotrons (..) Seeking their own neural network success, (AA) wondered if the tool could classify knots, a computationally challenging problem. >>

They << applied two different neural networks to the problem—a recurrent neural network (RNN) and a feed-forward neural network (FFNN). >>

<< The RNN achieved 99% accuracy >>
 
Katherine Wright. Neural Networks Know Their Knots. Physics 13, s19. Feb 11, 2020.


Olafs Vandans, Kaiyuan Yang, et al. Identifying knot types of polymer conformations by machine learning. Phys. Rev. E 101, 022502. Feb 11, 2020.

Also: network, neuro, in: https://www.inkgmr.net/kwrds.html

Keywords: gst, network, neural network, knots


lunedì 25 gennaio 2021

# gst: apropos of the structure of natural codes, a RNA folding knot (origami-style) dance

 << Every second, a myriad of shapeless strands of RNA fold, origami-style, into intricate structures inside living cells. Now, for the first time, researchers can watch a data-driven video of this folding as RNA molecules are made by the cellular machinery. >> 

<< as the RNA strand grows, it twists, forming knot-like structures. But as more RNA building blocks are added to the strand, the knots unravel, allowing the molecule’s structure to emerge. >> 

Ground-breaking films show RNA’s complex curves take shape. Experimental data and predictive algorithms combine to reveal the essential biomolecule’s shape-shifting.
Nature. Jan 19, 2021. 


AA << model the folding of an RNA called SRP, an ancient RNA found in all kingdoms of life. The molecule is well-known for its signature hairpin shape. When watching the videos, the researchers discovered that the molecule ties itself into a knot and unties itself very quickly. Then it suddenly flips into the correct hairpin-like structure using an elegant folding pathway called toehold mediated strand displacement. >>

<< To the best of our knowledge, this has never been seen in nature, (..) We think the RNA has evolved to untie itself from knots because if knots persist, it can render the RNA nonfunctional. The structure is so essential to life that it had to evolve to find a way to get out of a knot. >> Julius Lucks. 

Amanda Morris. New Videos Show RNA as it's Never Been Seen. First-ever data-driven movies illuminate RNA's mysterious folding process.  McCormick School of Engineering. Jan 15, 2021.



Angela M Yu, Paul M. Gasper, et al. Computationally reconstructing cotranscriptional RNA folding from experimental data reveals rearrangement of non-native folding intermediates. Molecular Cell. doi: 10.1016/ j.molcel.2020.12.017
Jan 15, 2021. 




sabato 30 luglio 2016

# s-gst: vortex knots in wave systems

<< Waves  surround  us  all  the  time:  sound waves in  the  noise  around  us, light  waves enabling  us  to see,  and  according  to  quantum  mechanics,  all  matter  has  a  wave  nature.  Most  of  these  waves, however,  do  not  resemble  the  regular  train  of  waves  at  the  shore  of  the  ocean—the  pattern  is much  more  chaotic.  Most  significantly,  the  whirls  and  eddies  form  lines  in  space  called  vortices. Along  these  lines,  the  wave  intensity  is  zero,  and  natural  wave  fields  -  light,  sound  and  quantum matter  -  are  filled  with  a  dense  tangle  of  these  null  filaments >>

Knots  in  chaotic  waves. July  29,  2016.

http://m.phys.org/news/2016-07-chaotic.html

Alexander J. Taylor & Mark R. Dennis. Vortex knots in tangled quantum eigenfunctions. Nature Communications. Published 29 Jul 2016 DOI: 10.1038/ncomms12346 OPEN

http://www.nature.com/ncomms/2016/160729/ncomms12346/full/ncomms12346.html

martedì 3 maggio 2016

# s-gst: measuring energy levels inside transitional dis-order(s)

<< Vortex  filaments  in  classical  and  quantum  fluids and  DNA  macromolecules,   magnetic  flux  tubesphase  defectspolymers may interact  and  recombine  through reconnection of  neighboring strandsDetails  of  the  process  depend  on specific  local  mechanisms  that  may differ  from  case  to case,  but  certain  qualitative  features  —  such  as  the  preservation  of  the  original  strand  orientation after recombination — are generic and common to all systems. >>

<< The  study of  these  processes  is  clearly of  great  importancebecause  the  change  of  topology is often  accompanied  bychange  in energyentropy and  function. >>

<< (..) HOMFLYPT  polynomial recently  introduced  for  fluid  knots (..) providespowerful  tool to  measure  topological  complexity of  various  physical  systems. >>

Liu,  X.,  Ricca,  R.  L.  Knots  cascade  detected  by  a  monotonically decreasing  sequence  of  values.  Sci.  Rep.6,  24118;  doi:  10.1038/srep24118  (2016).

http://www.nature.com/articles/srep24118

Quanta  energia è  nascosta  nel  caos? Bicocca, Milano,  2  maggio  2016

http://www.unimib.it/open/news/Quanta-energia-e-nascosta-nel-caos-Ce-lo-dice-il-polinomio-targato-Bicocca-Beijing-UTech/4936093294137195314

sabato 30 maggio 2020

# gst: apropos of unexpected Hopfion tangles

<< a certain geometrical structure of knots, which scientists call a Hopfion, manifests itself in unexpected corners of the universe, ranging from particle physics, to biology, to cosmology. >>

<< In a recent theoretical study, (..) (AA) discovered the presence of the Hopfion structure in nano-sized particles of ferroelectrics. >>

<< The Hopfion is a very abstract mathematical concept, (..) but the structure shows up in hydrodynamics, electrodynamics and even in the packing of DNA and RNA molecules in biological systems and viruses. >> Valerii Vinokur

<< When we visualized the polarization, we saw the Hopfion structure emerge, (..) We thought, wow, there is a whole world inside of these nanoparticles. >> Igor Luk'yanchuck.

Savannah Mitchem. Novel insight reveals topological tangle in unexpected corner of the universe. Argonne National Laboratory. May 26, 2020.


Luk’yanchuk I., Tikhonov Y., et al. Hopfions emerge in ferroelectrics
 Nat Commun 11, 2433. doi: 10.1038/ s41467-020-16258-w. May 15, 2020.


sabato 23 settembre 2017

# chem: strange transitions: tying a crystal into a knot

<< Single crystals are typically brittle, inelastic materials. Such mechanical responses limit their use in practical applications, particularly in flexible electronics and optical devices >>

AA << describe single crystals of a well-known coordination compound—copper(II) acetylacetonate—that are flexible enough to be reversibly tied into a knot >>

Anna Worthy, Arnaud Grosjean, et al. Atomic resolution of structural changes in elastic crystals of copper(II) acetylacetonate. Nature Chemistry. doi: 10.1038/nchem.2848. Aug 28, 2017

http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.2848.html

<< crystals exhibit traditional characteristics of not only hard matter, but soft matter like nylon >> John McMurtrie

<< Under strain the molecules in the crystal reversibly rotate and reorganise to allow the compression and expansion required for elasticity and still maintain the integrity of the crystal structure >> Jack Clegg

Bendable crystals tie current thinking in knots. Aug 29, 2017.

https://m.phys.org/news/2017-08-bendable-crystals-current.html

venerdì 4 dicembre 2015

# s-astrophys: a large-scale distribution of matter, with filaments and knots ...

<< Matter known as ordinary, which makes up everything we know, corresponds to only 5% of the Universe. >>

<<  (..) the majority of the missing ordinary matter is found in the form of a very hot gas associated with intergalactic filaments >>

http://www.alphagalileo.org/ViewItem.aspx?ItemId=158939&CultureCode=en

Dominique Eckert, Mathilde Jauzac, et al. Warm–hot baryons comprise 5–10 per cent of filaments in the cosmic web. Nature, 2015; 528 (7580): 105 DOI: 10.1038/nature16058

http://www.nature.com/nature/journal/v528/n7580/full/nature16058.html