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(138) Production(s) de l'année 2020


Revisiting the Askey–Wilson algebra with the universal R matrix of Uq(su(2))
Auteur(s): Crampé N., Gaboriaud Julien, Vinet Luc, Zaimi Meri
(Article) Publié:
Journal Of Physics A: Mathematical And Theoretical, vol. 53 p.05LT01 (2020)
Texte intégral en Openaccess :
Ref HAL: hal02890142_v1
Ref Arxiv: 1908.04806
DOI: 10.1088/17518121/ab604e
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: A description of the embedding of a centrally extended Askey–Wilson algebra, AW(3), in Uq(sl2) 3 is given in terms of the universal Rmatrix of Uq(sl2). The generators of the centralizer of Uq(sl2) in its threefold tensor product are naturally expressed through conjugations of Casimir elements with R. They are seen as the images of the generators of AW(3) under the embedding map by showing that they obey the AW(3) relations. This is achieved by introducing a natural coaction also constructed with the help of the Rmatrix.



Bannai–Ito algebras and the universal Rmatrix of osp(12)
Auteur(s): Crampé N., Vinet Luc, Zaimi Meri
(Article) Publié:
Letters In Mathematical Physics, vol. 110 p.10431055 (2020)
Texte intégral en Openaccess :
Ref HAL: hal02890130_v1
Ref Arxiv: 1909.06426
DOI: 10.1007/s1100501901249w
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: The BannaiIto algebra BI(n) is viewed as the centralizer of the action of osp(12) in the nfold tensor product of the universal algebra of this Lie superalgebra. The generators of this centralizer are constructed with the help of the universal Rmatrix of osp(12). The specific structure of the osp(12) embeddings to which the centralizing elements are attached as Casimir elements is explained. With the generators defined, the structure relations of BI(n) are derived from those of BI(3) by repeated action of the coproduct and using properties of the Rmatrix and of the generators of the symmetric group Sn.
Commentaires: 10 pages, 15 ref.



Formation and positioning of intracellular macromolecular assemblies: application to bacterial DNA segregation
Auteur(s): Walter J.C.
(Séminaires)
Laboratoire Charles Coulomb (Montpellier, FR), 20200624 Texte intégral en Openaccess :
Résumé: ** This HDR defense will exceptionally take place online due to the current UM rules  please contact me and I will send you the link for the visioconference ** Biology offers new systems for Physics, namely proteins and molecular motors in interaction with biopolymers like DNA and messenger RNA. This field is at the interface between active matter, polymer physics, and physics of colloids. Interestingly, cells also need to increase locally concentrations of proteins in a phase transitionlike mechanism to realize vital function like cell division, DNA repair, DNA segregation etc.
During this HDR defense, I will offer a physical perspective of intracellular phase transition with the example of bacterial DNA segregation. I will also discuss the motion of ribosomes along messenger RNA, an example of unidimensional inhomogeneous transport giving rise to different dynamical regimes.



Racah problems for the oscillator algebra and sl(n), and multivariate Krawtchouk polynomials
Auteur(s): Crampé N., Vinet Luc, van de Vijver Wouter
(Article) Publié:
Annales Henri Poincaré, vol. p. (2020)
Texte intégral en Openaccess :



Biaxial extensional viscous dissipation in sheets expansion formed by impact of drops of Newtonian and nonNewtonian fluids
Auteur(s): Louhichi A., Charles C.A., Phou T., Vlassopoulos Dimitris, Ramos L., Ligoure C.
(Article) Publié:
Physical Review Fluids, vol. 5 p.053602 (2020)
Texte intégral en Openaccess :
Ref HAL: hal02884674_v1
DOI: 10.1103/PhysRevFluids.5.053602
WoS: WOS:000530638500002
Exporter : BibTex  endNote
Résumé: We investigate freely expanding liquid sheets made of either simple Newtonian fluids or solutions of high molecular watersoluble polymer chains. A sheet is produced by the impact of a drop on a quartz plate covered with a thin layer of liquid nitrogen that suppresses shear viscous dissipation thanks to an inverse Leidenfrost effect. The sheet expands radially until reaching a maximum diameter and subsequently recedes. Experiments indicate the presence of two expansion regimes: the capillary regime, where the maximum expansion is controlled by surface tension forces and does not depend on the viscosity, and the viscous regime, where the expansion is reduced with increasing viscosity. In the viscous regime, the sheet expansion for polymeric samples is strongly enhanced as compared to that of Newtonian samples with comparable zeroshear viscosity. We show that data for Newtonian and nonNewtonian fluids collapse on a unique master curve where the maximum expansion factor is plotted against the relevant effective \textit{biaxial extensional} Ohnesorge number that depends on fluid density, surface tension and the biaxial extensional viscosity. For Newtonian fluids, this biaxial extensional viscosity is six times the shear viscosity. By contrast, for the nonNewtonian fluids, a characteristic \textit{Weissenberg number}dependent biaxial extensional viscosity is identified, which is in quantitative agreement with experimental and theoretical results reported in the literature for biaxial extensional flows of polymeric liquids.



Boron nitride for excitonics, nano photonics, and quantum technologies
Auteur(s): Gil B., Cassabois G., Cusco R., Fugallo Giorgia, Artus Lluis
(Article) Publié:
Nanophotonics, vol. p.2025 (2020)
Texte intégral en Openaccess :
Ref HAL: hal02884600_v1
DOI: 10.1515/nanoph20200225
Exporter : BibTex  endNote
Résumé: We review the recent progress regarding the physics and applications of boron nitride bulk crystals and its epitaxial layers in various fields. First, we high light its importance from optoelectronics side, for simple devices operating in the deep ultraviolet, in view of sanitary applications. Emphasis will be directed towards the unusually strong efficiency of the exciton–phonon coupling in this indirect band gap semiconductor. Sec ond, we shift towards nanophotonics, for the manage ment of hypermagnification and of medical imaging. Here, advantage is taken of the efficient coupling of the electromagnetic field with some of its phonons, those interacting with light at 12 and 6 μm in vacuum. Third, we present the different defects that are currently studied for their propensity to behave as single photon emitters, in the perspective to help them becoming challengers of the NV centres in diamond or of the double vacancy in silicon carbide in the field of modern and developing quantum technologies.



Strong Reduction in Amplitude of the Interfacial Segmental Dynamics in Polymer Nanocomposites
Auteur(s): Popov Ivan, Carroll Bobby, Bocharova Vera, Genix A.C., Cheng Shiwang, Khamzin Airat, Kisliuk Alexander, Sokolov Alexei p.
(Article) Publié:
Macromolecules, vol. 53 p.41264135 (2020)
Ref HAL: hal02880945_v1
DOI: 10.1021/acs.macromol.0c00496
WoS: WOS:000537677300050
Exporter : BibTex  endNote
Résumé: Despite the wide use of polymer nanocomposites (PNCs)in various applications, our understanding of the microscopic parameterscontrolling their macroscopic properties remains limited. In this study, weexamine the dielectric strength of segmental dynamics, ΔεIL(T) in theinterfacial polymer layer surrounding the nanoparticles in PNCs. Thepresented analysis reveals a significant drop in ΔεIL(T) and its anomaloustemperature dependence in the polymer layer adsorbed to nanoparticles.The drop in ΔεIL(T) was observed in all samples regardless of whethersegmental relaxation time in the interfacial layer was slower or faster thanin the bulk polymer, excluding interpretation of the “dead” layer. Weascribe the observed decrease in the dielectric strength to the restrictedamplitude of segmental relaxation in the interfacial/adsorbed layer. Ourresults provide a new perspective on discussion of dynamics in theinterfacial layer in PNCs and thin polymer films, demonstrating that notonly segmental relaxation time but also its amplitude can be strongly affected by the interface.
