27 research outputs found
Symmetry, winding number and topological charge of vortex solitons in discrete-symmetry media
We determine the functional behavior near the discrete rotational symmetry
axis of discrete vortices of the nonlinear Schr\"odinger equation. We show that
these solutions present a central phase singularity whose charge is restricted
by symmetry arguments. Consequently, we demonstrate that the existence of
high-charged discrete vortices is related to the presence of other off-axis
phase singularities, whose positions and charges are also restricted by
symmetry arguments. To illustrate our theoretical results, we offer two
numerical examples of high-charged discrete vortices in photonic crystal fibers
showing hexagonal discrete rotational invariance.Comment: 6 pages, 2 figure
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
Forward-backward equations for nonlinear propagation in axially-invariant optical systems
We present a novel general framework to deal with forward and backward
components of the electromagnetic field in axially-invariant nonlinear optical
systems, which include those having any type of linear or nonlinear transverse
inhomogeneities. With a minimum amount of approximations, we obtain a system of
two first-order equations for forward and backward components explicitly
showing the nonlinear couplings among them. The modal approach used allows for
an effective reduction of the dimensionality of the original problem from 3+1
(three spatial dimensions plus one time dimension) to 1+1 (one spatial
dimension plus one frequency dimension). The new equations can be written in a
spinor Dirac-like form, out of which conserved quantities can be calculated in
an elegant manner. Finally, these new equations inherently incorporate
spatio-temporal couplings, so that they can be easily particularized to deal
with purely temporal or purely spatial effects. Nonlinear forward pulse
propagation and non-paraxial evolution of spatial structures are analyzed as
examples.Comment: 11 page
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
Photonic Nambu-Goldstone bosons
We predict the existence of a Nambu-Goldstone excitation in the propagation of light in nonlinear
periodic lattices. We use methods of condensed matter physics that emphasize the peculiarities
stemming from the interplay between the nonlinearity and the lattice periodicity. By means of
nonlinear Bloch and Wannier functions we provide an explicit construction of the effective free
energy of the system, valid for long-range, or, equivalently, low-energy excitations around Bloch
solutions. Using then Landau mean field theory for phase transitions we determine the possible
stable ground states of the optical system and their stability conditions. Low energy excitations
above a stable ground state are fully controlled by the U(1) phase of the optical field, which appear
as a Nambu-Goldstone boson, analogous to those predicted in condenser matter and particle physics
systems. We support these results by numerical simulations both for spatially periodic and finite
nonlinear Bloch wave solutions. We demonstrate how finite-sized nonlinear Bloch light structures
embedded in a linear periodic lattice act as tunable metawaveguides for the phase Nambu-Goldstone waves.Ciencias Experimentale
Suppression Trial through an Integrated Vector Management of Aedes albopictus (Skuse) Based on the Sterile Insect Technique in a Non-Isolated Area in Spain
In recent years, Aedes albopictus (Skuse, 1984) has expanded its distribution globally due to its high ecological plasticity. This expansion has increased the population’s susceptibility to contracting diseases such as dengue, Zika, and chikungunya, among others, which are transmitted by this mosquito species. In the absence of effective control methods, the application of the sterile insect technique (SIT) is proposed as part of an integrated vector management (IVM) program. From 2007 to 2020, this strategy has been tested in a non-isolated mosquito population urban area of 45 ha, representative of the municipalities of the Valencian region (Spain). The population levels of adult females and eggs collected in the traps have been reduced by 70–80% compared to the control area, demonstrating its efficacy in reducing mosquito populations. This work analyzes the impact of the migration of the wild mosquito population from the peri-urban area to the urban core.This research was funded by La Conselleria de Agricultura, Desarrollo Rural, Emergencia Climática of the Valencian region (Spain).Ciencias Experimentale
Vortex solitons in photonic crystal fibers
We demonstrate the existence of vortex soliton solutions in photonic crystal
fibers. We analyze the role played by the photonic crystal fiber defect in the
generation of optical vortices. An analytical prediction for the angular
dependence of the amplitude and phase of the vortex solution based on group
theory is also provided. Furthermore, all the analysis is performed in the
non-paraxial regime.Comment: 4 pages, 4 figure
Pressure Point Thresholds and ME/CFS Comorbidity as Indicators of Patient’s Response to Manual Physiotherapy in Fibromyalgia
Current pharmacological treatments of Fibromyalgia (FM) are merely symptom palliative,
as clinical trials have so far failed to provide overall benefits without associated harms. Polypharmacy
often leads to patient’s health deterioration and chronic drug use to an eventual lack of patient’s
response. Emerging evidence supports that physiotherapy treatments based on mechanical triggers
improve FM symptoms and therefore could be used for therapeutic purposes by themselves or in
combination with current pharmacological treatments, as part of integrative medicine programs.
However, a paucity of studies rigorously and systematically evaluating this possibility exists.
This study uses scores from validated standardized questionnaires, algometer pressure point threshold
(PPT) readings and responses from a custom self-developed questionnaire to determine the impact of
a pressure-controlled custom manual protocol on FM hyperalgesia/allodynia, fatigue and patient’s
quality of life. The results show that patient’s baseline sensitivity to pain inversely correlates with
treatment response in FM. Moreover, post-stratification analysis unexpectedly reveals that patients
presenting comorbid ME/CFS do not seem to respond to the applied therapy as those presenting FM
only. Therefore, pre-treatment PPTs and ME/CFS comorbidity may serve as indicators to predict
patient’s response to physiotherapy programs based on mechanical triggers. Further exploration of
these findings is granted. In addition, the study of gene expression profiles in the blood collection
generated by this study should help unveil the molecular mechanisms behind patient’s differential
response to manual therapy.Medicin
Tutorización virtual con BigBlueButton para la docencia de la estadística en el ámbito de la prevención de lesiones deportivas
El objetivo de este trabajo es valorar el efecto del uso de la herramienta
de comunicación síncrona BigBlueButton como recurso para realizar una
revisión de conceptos básicos de Estadística a través de sesiones de
tutoría online. De esta manera se pretende evitar dedicar demasiado
tiempo al repaso de nociones estudiados en otros cursos y paliar el
hecho de disponer de unas horas muy ajustadas para impartir un temario
amplio, y con el que no están familiarizados la mayor parte del alumnado.Ciencias Experimentale