Seasonal dynamic factor analysis and bootstrap inference : application to electricity market forecasting

Year-ahead forecasting of electricity prices is an important issue in the current context of electricity markets. Nevertheless, only one-day-ahead forecasting is commonly tackled up in previous published works. Moreover, methodology developed for the short-term does not work properly for long-term forecasting. In this paper we provide a seasonal extension of the Non-Stationary Dynamic Factor Analysis, to deal with the interesting problem (both from the economic and engineering point of view) of long term forecasting of electricity prices. Seasonal Dynamic Factor Analysis (SeaDFA) allows to deal with dimensionality reduction in vectors of time series, in such a way that extracts common and specific components. Furthermore, common factors are able to capture not only regular dynamics (stationary or not) but also seasonal one, by means of common factors following a multiplicative seasonal VARIMA(p,d,q)×(P,D,Q)s model. Besides, a bootstrap procedure is proposed to be able to make inference on all the parameters involved in the model. A bootstrap scheme developed for forecasting includes uncertainty due to parameter estimation, allowing to enhance the coverage of forecast confidence intervals. Concerning the innovative and challenging application provided, bootstrap procedure developed allows to calculate not only point forecasts but also forecasting intervals for electricity prices

A quantification of the evolution of bilateral trade flows once bilateral RTAs are implemented

En este trabajo se estudia cómo 103 acuerdos comerciales regionales (ACR) bilaterales influyen en la evolución de los flujos comerciales bilaterales a lo largo del tiempo. El análisis de flujos comerciales trimestrales desde el segundo trimestre de 1982 hasta el cuarto trimestre de 2018 muestra diferencias dinámicas entre ACR y entre socios comerciales. Los resultados revelan que los países se benefician de forma desigual de los ACR bilaterales. La tendencia global positiva observada desde los años noventa, así como el impacto negativo de la crisis de 2008, se capta mediante un análisis factorial, de manera que se pueda estudiar específicamente el efecto asimétrico de los ACR bilaterales. De media, los ACR bilaterales promueven un aumento del 10 % en los flujos comerciales bilaterales por encima del comportamiento medio, pero se encuentran diferencias, dado que los acuerdos de alcance parcial (AAP) tienden a fomentar el comercio bilateral más que los acuerdos de libre comercio (ALC) (un 21 % respecto a un 9 %). Sin embargo, los AAP concentran sus efectos en los primeros cuatro trimestres tras la entrada en vigor de los acuerdos, mientras que los ALC tienen efectos más duraderos. Gracias al análisis de clústeres, el presente análisis permite una clasificación de los flujos comerciales bilaterales en grupos homogéneos en función del impacto dinámico que tienen los ACR sobre estos. Se explora así la heterogeneidad existente entre clústeres. Asimismo, los resultados muestran una diferencia relacionada con la crisis de 2008: en general, el impacto en el comercio bilateral de los acuerdos en vigor desde antes de 2008 es positivo (30 %), mientras que este es negativo para aquellos acuerdos en vigor desde 2008 (–9 %). Esto muestra que los ACR desempeñan un papel heterogéneo como mecanismo suavizador del ciclo económico. Finalmente, existe evidencia del efecto anticipación: para más de la mitad de los flujos comerciales analizados, el efecto de los ACR bilaterales se detecta antes de la entrada en vigor de estos.In this paper we study how 103 bilateral Regional Trade Agreements (RTAs) shape bilateral trade flows over time. The analysis of quarterly trade flows from 1982 Q4 to 2018 Q4 shows dynamic differences between RTAs and among trading partners. Results show that countries benefit unevenly from bilateral RTAs. The positive global trade trend since the 1990s and the negative effect of the 2008 economic crisis are captured by a factor analysis that allows us to study specifically how trade agreements affect bilateral trade asymmetrically. On average, RTAs lead to a 10% increase in bilateral trade flows above the mean trend, but disparities are found since Partial Scope Agreements (PSAs) tend to boost bilateral trade more than Free Trade Agreements (FTAs) (21% compared to 9%). However, most of the effects of PSAs occur during the first four quarters after the agreements come into force, whereas FTAs have effects over a longer period. The current study uses cluster analysis to classify bilateral trade flows into homogeneous groups according to the dynamic impact that RTAs have on them. This allows the heterogeneity between clusters to be explored. Moreover, the results show a difference relating to the economic crisis starting in 2008: in general, the impact on bilateral trade of agreements in force before 2008 is positive (30%), while it is negative for agreements signed after 2008 (-9%). This indicates that RTAs play a heterogeneous role as a cycle smoothing mechanism. Finally, there is evidence of an anticipation effect: we find that for more than half of the bilateral trade flows studied, the effect of the bilateral RTA is detected before it comes into force

Epidemiología de candidemias y utilidad de métodos rápidos de diagnóstico

Tesis doctoral inédita, leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Medicina Preventiva y Salud Pública. Fecha de lectura: 19 de Noviembre de 201

Eficacia del diclofenaco tópico vs. nepafenaco tópico en la reducción del dolor durante la fotocoagulación panretiniana

ResumenPropósitoComparar la eficacia del diclofenaco tópico 0.1% vs. nepafenaco tópico en reducir el dolor asociado a la fotocoagulación panretiniana con láser argón.Material y métodosEnsayo clínico aleatorizado doble enmascarado, 132 pacientes (183 ojos) con diagnóstico de retinopatía diabética proliferativa tratados con fotocoagulación panretiniana. Aleatorización en 2 grupos: diclofenaco y nepafenaco tópicos. Se aplicaron 2 dosis de los analgésicos tópicos previas a la fotocoagulación panretiniana, se evaluó el dolor inmediatamente y 15min después. Se analizó nivel de dolor, efectos adversos y síntomas asociados al finalizar la fotocoagulación retiniana.ResultadosLa mediana de la edad para ambos grupos fue de 55 años, relación H:M de 1:1.4. El nivel de dolor inmediato fue de 35.5 (RIC 14-72) para el nepafenaco y de 45 (RIC 14-70) para el diclofenaco (p=0.48). A los 15min fue de 30 (RIC 4-50) para el nepafenaco y de 20 (RIC 2-50) para el diclofenaco (p=0.48). No hubo diferencias significativas en síntomas asociados entre los grupos ni efectos adversos en la superficie ocular.ConclusionesEl tratamiento previo con nepafenaco y diclofenaco tópicos es igualmente eficaz y seguro para reducir el dolor asociado a la fotocoagulación panretiniana en pacientes con retinopatía diabética proliferativa.AbstractPurposeTo compare the efficacy of topical diclofenac 0.1% vs topical nepafenac in reducing pain associated to argon laser retinal photocoagulationMaterial and methodsDouble blinded, randomized clinical trial. One hundred thirty two patients with diagnosis of proliferative diabetic retinopathy treated with retinal photocoagulation. Randomization in to 2 groups: topical diclofenac and nepafenac. Before retinal photocoagulation 2 doses of topical non-steroidal anti-inflammatory drugs were applied, pain was assessed immediately and 15minutes after. Level of pain, adverse effects and associated symptoms at the end of retinal photocoagulation were analyzed.ResultsThe median for age in both groups was 55 years, M:F ratio of 1:1.4. The immediate level of pain was 35.5 (ICR 14-72) for nepafenac and 45 (ICR 14-70) for diclofenac (P=.48). At 15minutes the pain level was 30 (ICR 4-50) for nepafenac and 20 (ICR 2-50) for diclofenac. There was no difference in associated symptoms or adverse effects among groups.ConclusionsThe preventive treatment with topical nepafenac and diclofenac is equally effective and safe for reducing the pain associated with retinal photocoagulation in patients with proliferative diabetic retinopathy

Cambios en la discapacidad de las personas mayores entre 1999 y 2008 en España

Utilizando los microdatos de las encuestas de discapacidad del INE, este trabajo analiza cómo ha cambiado la prevalencia total y según categorías de la discapacidad de las personas mayores en España, entre 1999 y 2008, y cómo lo hace en los distintos grupos de edad. Se observa un aumento de la prevalencia entre ambos años, pero una mejora respecto a lo esperado. Esta mejora relativa no es homogénea: se ha reducido mucho la prevalencia de discapacidad instrumental (la más frecuente), y ello en todas las edades, pero ha aumentado la prevalencia en la categoría más severa de actividades básicas y especialmente entre las personas muy mayores.Peer reviewe

Mixed models for short-run forecasting of electricity prices: Application for the Spanish market

Short-run forecasting of electricity prices has become necessary for power generation unit schedule, since it is the basis of every profit maximization strategy. In this article a new and very easy method to compute accurate forecasts for electricity prices using mixed models is proposed. The main idea is to develop an efficient tool for one-step-ahead forecasting in the future, combining several prediction methods for which forecasting performance has been checked and compared for a span of several years. Also as a novelty, the 24 hourly time series has been modelled separately, instead of the complete time series of the prices. This allows one to take advantage of the homogeneity of these 24 time series. The purpose of this paper is to select the model that leads to smaller prediction errors and to obtain the appropriate length of time to use for forecasting. These results have been obtained by means of a computational experiment. A mixed model which combines the advantages of the two new models discussed is proposed. Some numerical results for the Spanish market are shown, but this new methodology can be applied to other electricity markets as wel

Personal Learning Environments: State of Situation in the School of Education at the University of Malaga

Este artículo está basado en un estudio realizado con el objetivo de conocer el papel que los entornos personales de aprendizaje (PLE) juegan en la formación del alumnado de la Facultad de Ciencias de la Educación de la Universidad de Málaga. Se ha estudiado cuáles son las aplicaciones y herramientas que más emplea el alumnado en su aprendizaje no formal. Se puede concluir que, en general, el alumnado no utiliza efectivamente los medios de los que disponen y los que lo hacen no asocian el empleo de los PLE con usos académicos.This article is based on a study aimed to know the role that personal learning environments (PLE) play in the training of students of the School of Education at the University of Malaga. The applications and tools that most students use in non-formal learning are studied. In conclusion, students do not effectively use the available media and do not associate the use of personal learning environments PLE with academic uses

Continuous-wave semiconductor disk laser emitting at 224 nm via intracavity frequency tripling

We present frequency tripling of a tunable continuous-wave red AlGaInP semiconductor disk laser. From a fundamental beam at 674 nm, output power up to ~100 μW and laser tunability over 1.8 nm are reported

Tunable, CW laser emission at 225 nm via intracavity frequency tripling in a semiconductor disk laser

Numerous applications would benefit from a compact laser source with tunable, continuous-wave emission in the deep ultraviolet (wavelengths <250nm); however, very few laser sources have been demonstrated with direct emission in this spectral region and options are generally limited to pulsed, fixed wavelength sources or complex and impractical setups for nonlinear frequency mixing of the emission of several infrared lasers in various external enhancement cavities. Here we propose an all-solid-state, continuous-wave, tunable laser with emission between 224 nm and 226 nm via intracavity frequency tripling in an AlGaInP-based semiconductor disk laser (SDL). Output power up to 78 µW is achieved in CW operation, with a tuning range over 350 cm-1. AlGaInP-based SDLs may be designed to emit anywhere between ~640 – 690 nm such that wavelengths between 213 nm and 230 nm may be targeted for specific applications using a similar set-up. An in-depth study of the nonlinear conversion has been carried out to understand the limitations of the set-up, namely large walk-off angles for phase-matching in the nonlinear crystals, and the potential for increasing the output power to several milli-Watts. This is, to the authors' knowledge, the first implementation of intracavity frequency tripling in a visible SDL and the shortest wavelength emitted from an SDL system

Social learning network. Digital networks in university education

Las redes sociales ofrecen grandes posibilidades de comunicación e interacción social en los nuevos ciudadanos del siglo XXI, pero lo hacen con propiedades y funcionalidades muy distintas. Desde la formación universitaria podemos recoger algunas de estas características para fortalecer la actividad de aprendizaje a través de una mejor o mayor comunicación. Pero no todas las redes son iguales ni todas sirven para el entorno educativo. Elementos referidos a la seguridad, la privacidad o el control de la actividad de los usuarios son fundamentales a la hora de plantearnos su integración como una herramienta académica formal. Las redes sociales de carácter vertical son una excelente herramienta de enseñanza-aprendizaje para las instituciones de educación superior, y veremos que algunas universidades ya las están poniendo en uso en sus planes de formación e investigación. En estas líneas presentaremos algunas de las ventajas que ofrecen en su integración formal a la vez que adelantaremos las dificultades que debemos salvar para alinear la actividad con la red y nuestros objetivos docentes.Social networks offer great potential for communication and social interaction in the new citizens of the XXI century, but social networks do it with different properties and functionalities. From university we can incorporate some of these features to strengthen the learning activity through a better communication. But not all networks are equal and not all networks can be used in educational environment. Items like security, privacy or activity control are fundamental to their integration as a formal academic tool. The vertical social networks are a great tool for teaching and learning in higher education institutions, and many universities use it for training and research programs. We will present some of the advantages they offer in formal training. At the same time we will advance the difficulties to align the social network activity with our teaching objectives