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

A software system to teach economics to secondary school and first year engineering students

[EN] In this paper, we present a graphical user interface which has been devised to teach the basic concepts of economics in secondary schools and first year engineering courses. The application allows students to vary certain parameters and visually observe the effect on the supply and demand curves. The system has been developed in Matlab and employed in a secondary school in Spain. The first results are presented.[ES] Presentamos una interfaz gráfica desarrollada mediante Matlab diseñada para complementar el aprendizaje de los conceptos básicos de economía en Bachillerato, grado superior de ciclos formativos y cursos universitarios de introducción a la economía. La aplicación informática permite que los estudiantes varíen los parámetros de los que dependen las curvas de oferta y demanda, y visualicen el efecto sobre el equilibrio de mercado de estas variaciones. Se presentan los resultados de una primera experiencia de aplicación del programa en enseñanza secundaria en España.García-March, M.; Zacarés, M.; Isidro, J.; Monreal, L.; López-Javier, C.; Arevalillo-Herráez, M. (2009). A software system to teach economics to secondary school and first year engineering students. Modelling in Science Education and Learning. 2:105-113. doi:10.4995/msel.2009.3126SWORD105113

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

Photonic Nambu-Goldstone bosons

We study numerically the spatial dynamics of light in periodic square lattices in the presence of a Kerr term, emphasizing the peculiarities stemming from the nonlinearity. We find that, under rather general circumstances, the phase pattern of the stable ground state depends on the character of the nonlinearity: the phase is spatially uniform if it is defocusing whereas in the focusing case, it presents a chessboard pattern, with a difference of π between neighboring sites. We show that the lowest-lying perturbative excitations can be described as perturbations of the phase and that finite-sized structures can act as tunable metawaveguides for them. The tuning is made by varying the intensity of the light that, because of the nonlinearity, affects the dynamics of the phase fluctuations. We interpret the results using methods of condensed-matter physics, based on an effective description of the optical system. This interpretation sheds light on the phenomena, facilitating the understanding of individual systems and leading to a framework for relating different problems with the same symmetry. In this context, we show that the perturbative excitations of the phase are Nambu-Goldstone bosons of a spontaneously broken U(1) symmetry

Fracturas de radio distal. ¿Progresa el desplazamiento entre la segunda y la sexta semana?.

Las fracturas de radio distal son las más frecuentes en nuestra especialidad. El tratamiento conservador con inmovilización, basado en una serie de parámetros radiológicos, sigue siendo el más utilizado hoy en día. El objetivo de nuestro estudio ha sido evaluar el desplazamiento secundario de estas fracturas entre la segunda y sexta semana de evolución. Para ello hemos evaluado las fracturas de radio distal tratadas de forma conservadora en nuestro Servicio, durante el año 2016. De un total de 53 fracturas de muñeca tratadas de forma conservadora, un 49% de los casos presentó algún tipo de desplazamiento, si bien la mayor parte de estos tuvieron lugar antes de la segunda semana. Nuestros resultados fueron similares a los revisados en la literatura, en cuanto a datos demográficos y tasa de desplazamiento. Por lo que recomendamos intercalar algunos controles radiográficos semanales en aquellas fracturas que presenten desde el inicio algún parámetro de inestabilidad

Estudio de las lesiones en el judo

Judo is a martial art whose origins come from jujutsu, created in 1882 by the master Jigoro Kano, who proposed a method that was based on techniques that could be applied in real combat, as well as practiced with the partner without risk of injury .The objective of the present study is to assess the prevalence, type and distribution of the injuries suffered. Check whether sex or sports performance influences the appearance of injuries, determine which technique intervenes more frequently, assess whether they occur mostly in training or competition, and analyze how they act.This is a descriptive crosssectional observational study, in which four clubs were asked to participate, in which they had to answer an anonymous survey.Regarding the results, a total of 652 injuries were registered, in 63 men and 38 women. The most commonly injured body regions were the upper limbs 254 (38.95 %%). Contusions and sprains were the most frequent injuries and the most frequently associated technique was Seoi Nage. The number of injuries was higher during the competition if we take into account time. Most of the injuries (74.1%) were of slight characteristics, with a sports rest of less than a week and only 38.95% forced the judoka to interrupt the sport.After the study carried out, we can conclude that the results obtained are comparable to the bibliography, confirming the stated objective

Measurement invariance of the short version of the problematic mobile phone use questionnaire (PMPUQ-SV) across eight languages

The prevalence of mobile phone use across the world has increased greatly over the past two decades. Problematic Mobile Phone Use (PMPU) has been studied in relation to public health and comprises various behaviours, including dangerous, prohibited, and dependent use. These types of problematic mobile phone behaviours are typically assessed with the short version of the Problematic Mobile Phone Use Questionnaire (PMPUQ-SV). However, to date, no study has ever examined the degree to which the PMPU scale assesses the same construct across different languages. The aims of the present study were to (i) determine an optimal factor structure for the PMPUQ-SV among university populations using eight versions of the scale (i.e., French, German, Hungarian, English, Finnish, Italian, Polish, and Spanish); and (ii) simultaneously examine the measurement invariance (MI) of the PMPUQ-SV across all languages. The whole study sample comprised 3038 participants. Descriptive statistics, correlations, and Cronbach's alpha coefficients were extracted from the demographic and PMPUQ-SV items. Individual and multigroup confirmatory factor analyses alongside MI analyses were conducted. Results showed a similar pattern of PMPU across the translated scales. A three-factor model of the PMPUQ-SV fitted the data well and presented with good psychometric properties. Six languages were validated independently, and five were compared via measurement invariance for future cross-cultural comparisons. The present paper contributes to the assessment of problematic mobile phone use because it is the first study to provide a cross-cultural psychometric analysis of the PMPUQ-SV