Search results for "BIF"
showing 10 items of 539 documents
Vibrating soliton pairs in a mode-locked laser cavity
2006
International audience; We show numerically the existence of vibrating soliton pairs that are consistent with observations performed with a passively mode-locked fiber laser. These vibrating pairs are new types of multisoliton complexes that exist in the vicinity of the phase-locked soliton pairs discovered a few years ago [Opt. Lett. 27, 966 (2002)]. The pairs are found numerically with a laser propagation model that includes nonlinear dissipation and cavity periodicity, and they can appear following a Hopf-type bifurcation when a cavity parameter is tuned.
Bifurcations and multiple-period soliton pulsations in a passively mode-locked fiber laser
2004
The multiple-period pulsations of the soliton parameters in a passively mode-locked fiber laser were discussed numerically and experimentally. It was found that the pulse acquired a periodic evolution that was not related to the round-trip time and consisted of many round trips. The macroperiodicity existed independently or in combination with other periodicity such as period doubling, tripling etc. Analysis shows that the new periods in the soliton modulation appear at bifurcation point related to certain points related to certain values of the cavity parameters.
Asymmetric balance in symmetry breaking
2020
Spontaneous symmetry breaking is central to our understanding of physics and explains many natural phenomena, from cosmic scales to subatomic particles. Its use for applications requires devices with a high level of symmetry, but engineered systems are always imperfect. Surprisingly, the impact of such imperfections has barely been studied, and restricted to a single asymmetry. Here, we experimentally study spontaneous symmetry breaking with two controllable asymmetries. We remarkably find that features typical of spontaneous symmetry breaking, while destroyed by one asymmetry, can be restored by introducing a second asymmetry. In essence, asymmetries are found to balance each other. Our st…
Organization of Quantum Bifurcations: Crossover of Rovibrational Bands in Spherical Top Molecules
1989
Qualitative changes in the rotational structure of a finite particle quantum system are studied. The crossover phenomenon is explained from the point of view of consecutive quantum bifurcations. The generic organization of bifurcations is related to the stratification of the space of dynamical variables imposed by the invariance group of the Hamiltonian.
Polymerizable ring-shaped molecules containing aspartic acid: synthesis and free radical polymerization of a macrocycle derived from (N'-methacryloyl…
1999
A novel polymerizable macrocycle, 6, was prepared using high dilution techniques. Starting from N-(N'-methacryloyl-11-aminoundecanoyl)-L-aspartic acid dimethyl ester (2), N-(N'methacryloyl-11-aminoundecanoyl)-α,β-bis( 4,9-dioxadodecane-1,12-diamine)-L-aspartic acid amide (4) was obtained via amino-lysis with the bifunctional amine 4,9-dioxadodecane-1,12-diamine (3) in high excess. Addition of the free amino groups to toluene-2,4-diisocyanate (5) under high dilution provided macrocycle 6. The existence and purity of 6 were confirmed by mass spectrometry, NMR and IR spectroscopy, and HPLC. The methacrylic function was used to build up oligomers by free radical polymerization, using AIBN as an…
Elastomeric Organosilicon Micronetworks
1997
Trifunctional methyltrimethoxysilane and bifunctional dimethyldimethoxysilane monomers were cocondensed in water in the presence of surfactant. Strictly spherical micronetworks of narrow size distribution were obtained for particle sizes 10 nm < R < 30 nm. By special “endcapping” reactions all reactive SiOH groups were removed quantitatively, and the resulting micronetworks become soluble in common organic solvents like toluene, THF, or chloroform. For contents of trifunctional monomer larger than 50 mol % the particles do not swell irrespective of the choice of the solvent, whereas for lower mole fractions of trimethoxysilane an increasing swelling ratio is observed. Below 2.5 mol % trifun…
Blenders near polynomial product maps of $\mathbb C^2$
2021
In this paper we show that if $p$ is a polynomial which bifurcates then the product map $(z,w)\mapsto(p(z),q(w))$ can be approximated by polynomial skew products possessing special dynamical objets called blenders. Moreover, these objets can be chosen to be of two types : repelling or saddle. As a consequence, such product map belongs to the closure of the interior of two different sets : the bifurcation locus of $H_d(\mathbb P^2)$ and the set of endomorphisms having an attracting set of non-empty interior. In an independent part, we use perturbations of H\'enon maps to obtain examples of attracting sets with repelling points and also of quasi-attractors which are not attracting sets.
Bifurcation phenomena for the positive solutions of semilinear elliptic problems with mixed boundary conditions
2016
We consider a parametric semilinear elliptic equation with a Cara-theodory reaction which exhibits competing nonlinearities. It is "concave" (sub-linear) near the origin and "convex" (superlinear) or linear near $+\infty$. Using variational methods based on the critical point theory, coupled with suitable truncation and comparison techniques, we prove a bifurcation-type theorem, describing the set of positive solutions as the parameter varies.
A hybrid catalyst for decontamination of organic pollutants based on a bifunctional dicopper(II) complex anchored over niobium oxyhydroxide
2017
Abstract This article describes the preparation and characterization of a hybrid oxidation catalyst for decontamination of organic pollutants which involves a bifunctional dicopper(II) complex and the niobium(V) oxyhydroxide as the active species, the later one being also a solid support. The pH range for the existence of the active species was determined by potentiometric and UV–vis spectroscopy at 25 °C and 0.15 M NaCl in a H 2 O/EtOH (70:30 v/v) solvent mixture containing copper(II) and the ligand N , N -2,2′-ethylenediphenylenebis(oxamic acid) (H 4 L). As far as the hybrid material is concerned, FTIR, FT-Raman, TEM and SEM images, surface area and TG/DTA analyses showed the occurrence o…
Peroxisomal and mitochondrial status of two murine oligodendrocytic cell lines (158N, 158JP): potential models for the study of peroxisomal disorders…
2009
International audience; In some neurodegenerative disorders (leukodystrophies) characterized by myelin alterations, the defect of peroxisomal functions on myelin-producing cells (oligodendrocytes) are poorly understood. The development of in vitro models is fundamental to understanding the physiopathogenesis of these diseases. We characterized two immortalized murine oligodendrocyte cell lines: a normal (158N) and a jimpy (158JP) cell line mutated for the proteolipid protein PLP/DM20. Fluorescence microscopy, flow cytometry, and western blotting analysis allow to identify major myelin proteins (PLP colocalizing with mitochondria; myelin basic protein), oligodendrocyte (CNPase and myelin oli…