Particle velocity controls phase transitions in contagion dynamics

Interactions often require the proximity between particles. The movement of particles, thus, drives the change of the neighbors which are located in their proximity, leading to a sequence of interactions. In pathogenic contagion, infections occur through proximal interactions, but at the same time the movement facilitates the co-location of different strains. We analyze how the particle velocity impacts on the phase transitions on the contagion process of both a single infection and two cooperative infections. First, we identify an optimal velocity (close to half of the interaction range normalized by the recovery time) associated with the largest epidemic threshold, such that decreasing the velocity below the optimal value leads to larger outbreaks. Second, in the cooperative case, the system displays a continuous transition for low velocities, which becomes discontinuous for velocities of the order of three times the optimal velocity. Finally, we describe these characteristic regimes and explain the mechanisms driving the dynamics.Comment: 9 pages, 5 figures, 12 supplementary figure

Scaling in the structure of directory trees in a computer cluster

We describe the topological structure and the underlying organization principles of the directories created by users of a computer cluster when storing his/her own files. We analyze degree distributions, average distance between files, distribution of communities and allometric scaling exponents of the directory trees. We find that users create trees with a broad, scale-free degree distribution. The structure of the directories is well captured by a growth model with a single parameter. The degree distribution of the different trees has a non-universal exponent associated with different values of the parameter of the model. However, the distribution of community sizes has a universal exponent analytically obtained from our model.Comment: refined data analysis and modeling, completely reorganized version, 4 pages, 2 figure

Diseño e implantación de un sistema de apoyo a las decisiones basado en el modelo de transporte.

Se presenta el diseño y la implantación del SPT (Sistema de Producción y Transporte), un sistema de apoyo a las decisiones (DSS) basado en el modelo de transporte. Fue construido para una empresa argentina de cemento que abastece a sus clientes desde varias plantas industriales y está estructurado sobre el Optimat, un software comercial. Se lo utiliza con éxito en la planificación operativa y en la decisión de las políticas empresariales, tanto estratégicas como tácticas. El proyecto da gran importancia a los problemas del cambio organizacional. Se describen los pasos seguidos en el diseño e implantación del SPT: (1) Comprensión del problema; (2) Formulación de un modelo; (3) Obtención de los datos; (4) Entrada de los datos al modelo; (5) Resolución del modelo; y (6) Implantación de la solución. Durante la descripción de estos pasos se examinan tres problemas: (a) El modelo de transporte; (b) El software de computación para resolver problemas de escala práctica; y (c) Los problemas organizacionales vinculados con el uso de los modelos matemáticos. El modelo de transporte clásico se amplía con la introducción de variables de eficiencia productiva de las plantas, dando lugar a un sistema más general, de producción y transporte. El SPT se implementa con un software para modelos generales de red. Por lo tanto, no sólo permite obtener los resultados operativos para el problema del transporte clásico, sino que sienta las bases para realizar experimentos de políticas alternativas de producción y transporte. Entre estas aplicaciones estratégicas y tácticas se cuentan: cambios en la capacidad productiva y en la eficiencia de las plantas, determinación de las áreas de influencia de cada planta, impacto de demandas esporádicas grandes sobre el sistema general, impacto de la eliminación de un mercado completo, estudio de medios de transporte alternativos, impacto de los transbordos, y estudios de localización de nuevas plantas. Es posible la extensión del SPT, utilizando sistemas de información geográfica (GIS), para facilitar el manejo de los datos, la interpretación de los resultados y la toma de decisiones. Los apéndices muestran la resolución de un prototipo y presentan los archivos maestros y resultados generales del SPT.

Coupling between COVID-19 and seasonal influenza leads to synchronization of their dynamics

Interactions between COVID-19 and other pathogens may change their dynamics. Specifically, this may hinder the modelling of empirical data when the symptoms of both infections are hard to distinguish. We introduce a model coupling the dynamics of COVID-19 and seasonal influenza, simulating cooperation, competition and asymmetric interactions. We find that the coupling synchronizes both infections, with a strong influence on the dynamics of influenza, reducing its time extent to a half

Percolation-based precursors of transitions in extended systems

Abrupt transitions are ubiquitous in the dynamics of complex systems. Finding precursors, i.e. early indicators of their arrival, is fundamental in many areas of science ranging from electrical engineering to climate. However, obtaining warnings of an approaching transition well in advance remains an elusive task. Here we show that a functional network, constructed from spatial correlations of the system’s time series, experiences a percolation transition way before the actual system reaches a bifurcation point due to the collective phenomena leading to the global change. Concepts from percolation theory are then used to introduce early warning precursors that anticipate the system’s tipping point. We illustrate the generality and versatility of our percolation-based framework with model systems experiencing different types of bifurcations and with Sea Surface Temperature time series associated to El Niño phenomenon.V.R.-M. was supported by the European Commission Marie-Curie ITN program (FP7-320 PEOPLE-2011-ITN) through the LINC project (Grant no. 289447). We also acknowledge support from FEDER and Spanish Ministry of Economy and Competitiveness (MINECO) through the project INTENSE@COSYP (FIS2012-30634) and from the European Commission through project LASAGNE (FP7-ICT- 318132). J.J.R. acknowledges funding from the Ramón y Cajal program of MINECO.EUR 1,165 APC fee funded by the EC FP7 Post-Grant Open Access PilotPeer reviewe

Temporary Language Adaptation Classrooms: One of the Great Unknowns for Future Primary School teachers

El presente estudio pretende indagar en la opinión sobre la formación universitaria recibida por los futuros maestros de educación primaria en relación con la atención al alumnado inmigrante en las escuelas y, particularmente, con las aulas temporales de adaptación lingüística (ATAL) andaluzas. Se discuten los datos arrojados del análisis de un cuestionario formado por diez ítems, que combinaron tanto preguntas de índole cuantitativa como cualitativa, al que respondieron 54 estudiantes del último curso del Grado en Educación Primaria de la Universidad de Almería (España). Según los resultados, al acabar la carrera, las estrategias y el aprendizaje adquirido se muestran insuficientes de acuerdo con la naturaleza multicultural que presenta la mayoría de los centros educativos españoles, mientras que se aprecia gran interés por cursar estudios de posgrado sobre enseñanza del español como segunda lengua. En conclusión, con el propósito de lograr una integración auténtica del alumnado inmigrante, se reivindica una conexión efectiva entre la formación académica de grado y la realidad multicultural y multilingüe de las aulas en la sociedad española actual.The present study aims to look into the opinion of prospective primary school teachers about their training for assisting migrant students. Special attention is drawn to their views on the linguistic adaptation temporary classes (ATAL) in Andalusia. The data obtained from the analysis of a questionnaire are discussed. This questionnaire consists of ten items, which combined both quantitative and qualitative questions, and was completed by 54 students in the last year of the Degree in Primary Education at University of Almería (Spain). According to the results, upon completion of training, the knowledge and strategies developed appear to be insufficient for the multicultural nature of most Spanish schools. At the same time, respondents show a great interest in postgraduate courses on teaching Spanish as a second language. In conclusion, in order to achieve the integration of migrant students, a more effective connection between teacher training programs and the multicultural and multilingual reality of Spanish schools nowadays is needed

Risk of Coinfection Outbreaks in Temporal Networks: A Case Study of a Hospital Contact Network

We study the spreading of cooperative infections in an empirical temporal network of contacts between people, including health care workers and patients, in a hospital. The system exhibits a phase transition leading to one or several endemic branches, depending on the connectivity pattern and the temporal correlations. There are two endemic branches in the original setting and the non-cooperative case. However, the cooperative interaction between infections reinforces the upper branch, leading to a smaller epidemic threshold and a higher probability for having a big outbreak. We show the microscopic mechanisms leading to these differences, characterize three different risks, and use the influenza features as an example for this dynamics.DFG, 345463468, Interacting Dynamics on Networks, Applications to Epidemiology (idonate

Classroom communication skills: the need to fill a gap in the training of teachers of Spanish as a foreign language

This paper sets out the necessity of examining the communication skills of teachers of Spanish as a foreign language as conducted in other socio-educative contexts. According to this objective, the paper begins with a review of theoretical efforts that have been made during recent years referring to research methodology (such as instruments), and to their main results. This leads to a discussion of the training needs that teachers of Spanish as a foreign language presently face for the development of their communication s kills in the classroom and, in general terms, the paper discusses the different types of ideas and strategies that must be considered during teachers’ instruction. Finally, this brief proposal expects to be the seed of future research projects that impact positively on the improvement of teachers’ communication competence, whereby the ideas discussed here are taken as a nuclear component in the frame of future teaching competence