1,893 research outputs found
Angular Pseudomomentum Theory for the Generalized Nonlinear Schr\"{o}dinger Equation in Discrete Rotational Symmetry Media
We develop a complete mathematical theory for the symmetrical solutions of
the generalized nonlinear Schr\"odinger equation based on the new concept of
angular pseudomomentum. We consider the symmetric solitons of a generalized
nonlinear Schr\"odinger equation with a nonlinearity depending on the modulus
of the field. We provide a rigorous proof of a set of mathematical results
justifying that these solitons can be classified according to the irreducible
representations of a discrete group. Then we extend this theory to
non-stationary solutions and study the relationship between angular momentum
and pseudomomentum. We illustrate these theoretical results with numerical
examples. Finally, we explore the possibilities of the generalization of the
previous framework to the quantum limit.Comment: 18 pages; submitted to Physica
A topological charge selection rule for phase singularities
We present an study of the dynamics and decay pattern of phase singularities
due to the action of a system with a discrete rotational symmetry of finite
order. A topological charge conservation rule is identified. The role played by
the underlying symmetry is emphasized. An effective model describing the short
range dynamics of the vortex clusters has been designed. A method to engineer
any desired configuration of clusters of phase singularities is proposed. Its
flexibility to create and control clusters of vortices is discussed.Comment: 4 pages, 3 figure
Nonequilibrium quantum dynamics of partial symmetry breaking for ultracold bosons in an optical lattice ring trap
A vortex in a Bose-Einstein condensate on a ring undergoes quantum dynamics
in response to a quantum quench in terms of partial symmetry breaking from a
uniform lattice to a biperiodic one. Neither the current, a macroscopic
measure, nor fidelity, a microscopic measure, exhibit critical behavior.
Instead, the symmetry memory succeeds in identifying the point at which the
system begins to forget its initial symmetry state. We further identify a
symmetry energy difference in the low lying excited states which trends with
the symmetry memory
Vorticity cutoff in nonlinear photonic crystals
Using group theory arguments, we demonstrate that, unlike in homogeneous
media, no symmetric vortices of arbitrary order can be generated in
two-dimensional (2D) nonlinear systems possessing a discrete-point symmetry.
The only condition needed is that the non-linearity term exclusively depends on
the modulus of the field. In the particular case of 2D periodic systems, such
as nonlinear photonic crystals or Bose-Einstein condensates in periodic
potentials, it is shown that the realization of discrete symmetry forbids the
existence of symmetric vortex solutions with vorticity higher than two.Comment: 4 pages, 5 figures; minor changes in address and reference
Análisis competencial de una tarea de modelización abierta
Según diversos autores, las actividades dirigidas al desarrollo conjunto de las competencias matemáticas deben relacionarse con la realidad y los procesos de modelización matemática. El objetivo del presente trabajo es describir, a partir de la producción de un grupo de alumnos de tercer curso de ESO, las competencias que los alumnos han de poner en juego para resolver una tarea genuina y completa de modelización y que formarían parte de la propia competencia en Modelizació
Vortex transmutation
Using group theory arguments and numerical simulations, we demonstrate the
possibility of changing the vorticity or topological charge of an individual
vortex by means of the action of a system possessing a discrete rotational
symmetry of finite order. We establish on theoretical grounds a "transmutation
pass rule'' determining the conditions for this phenomenon to occur and
numerically analize it in the context of two-dimensional optical lattices or,
equivalently, in that of Bose-Einstein condensates in periodic potentials.Comment: 4 pages, 4 figure
On the construction of a geometric invariant measuring the deviation from Kerr data
This article contains a detailed and rigorous proof of the construction of a
geometric invariant for initial data sets for the Einstein vacuum field
equations. This geometric invariant vanishes if and only if the initial data
set corresponds to data for the Kerr spacetime, and thus, it characterises this
type of data. The construction presented is valid for boosted and non-boosted
initial data sets which are, in a sense, asymptotically Schwarzschildean. As a
preliminary step to the construction of the geometric invariant, an analysis of
a characterisation of the Kerr spacetime in terms of Killing spinors is carried
out. A space spinor split of the (spacetime) Killing spinor equation is
performed, to obtain a set of three conditions ensuring the existence of a
Killing spinor of the development of the initial data set. In order to
construct the geometric invariant, we introduce the notion of approximate
Killing spinors. These spinors are symmetric valence 2 spinors intrinsic to the
initial hypersurface and satisfy a certain second order elliptic equation
---the approximate Killing spinor equation. This equation arises as the
Euler-Lagrange equation of a non-negative integral functional. This functional
constitutes part of our geometric invariant ---however, the whole functional
does not come from a variational principle. The asymptotic behaviour of
solutions to the approximate Killing spinor equation is studied and an
existence theorem is presented.Comment: 36 pages. Updated references. Technical details correcte
Teacher s management of the modeling activity in the classroom at secondary level
[EN] the introduction of modeling in the secondary level
demands the reconsideration about the teaching
methodology that promotes and stimulates this
activity in classroom. In this paper we present a
classroom experience carried out in ninth grade.
We analyze the work dynamic and the role of
debate and interventions of the teacher in the
process of solving the modeling tasks.[ES] La introducción de la modelización en secundaria
requiere un replanteamiento de la metodología de
enseñanza que promueva y posibilite la actividad
modelizadora de nuestros alumnos. En el presente
artículo, a través de una experiencia de aula llevada
a cabo en tercero de secundaria, analizamos la
dinámica de trabajo y el papel del debate y las
intervenciones del profesor en el proceso de
resolución de las tareas de modelización.Gallart-Palau, C.; Ferrando Palomares, I.; García-Raffi, LM. (2015). El profesor ante la actividad modelizadora en el aula de secundaria. Suma. (79):9-16. http://hdl.handle.net/10251/99867S9167
Large-Size Star-Shaped Conjugated (Fused) Triphthalocyaninehexaazatriphenylene
Star-shaped triphthalocyaninehexaazatriphenylene 1 was synthesized via condensation between a new building block 1,2-diaminophthalocyanine and cyclohexanehexaone. Compound 1 represents the largest star-shaped phthalocyanine-fused hexaazatriphenylene reported so far. This largely expanded phthalocyanine shows good solubility and has a strong tendency to aggregate in both solution and on surface, indicating its potential as active component in organic electronic devices.This research was financially supported by the Spanish Ministry of Economy and Competitiveness (Mineco) of Spain [CTQ2014-55798-R, CTQ2015-71936-REDT, CTQ2013-40480-R and “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496)], Generalitat Valenciana (Prometeo 2012/010), the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) and by ERC StG 2012-306826 e-GAMES. A. C. acknowledges the Materials Science PhD program of UAB.Peer reviewe
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