Portfolio choice and the effects of liquidity

This paper shows how to introduce liquidity into the well known mean-variance framework of portfolio selection. Either by estimating mean-variance liquidity constrained frontiers or directly estimating optimal portfolios for alternative levels of risk aversion and preference for liquidity, we obtain strong effects of liquidity on optimal portfolio selection. In particular, portfolio performance, measured by the Sharpe ratio relative to the tangency portfolio, varies significantly with liquidity. Moreover, although mean-variance performance becomes clearly worse, the levels of liquidity on optimal portfolios obtained when there is a positive preference for liquidity are much lower than on those optimal portfolios where investors show no sign of preference for liquidity.Liquidity, mean-variance frontiers, performance, portfolio selection

Efficiency in the management of urban water services. What have we learned after four decades of research?

The analysis of efficiency in the management of urban water services offers valuable information both for the managers of this service and for public bodies in order to introduce improvements in business practices and in the design of public policies. Since the pioneering study carried out by Ford and Wardford (1969), there have been many attempts to follow this line of research. Due to the importance of the subject and the volume of publications in this field, we believe it is necessary to provide a balance of the work carried out over the last four decades. In this overview, we look at the main questions which have arisen over this period, we provide a synthesis of the results obtained and, finally, we point out some challenges for future research.Water utilities; Efficiency; Firm behaviour; Water

Tourism and productivity: Case study of the hotel and catering industry in the Andalusian region

The object of this paper is to analyse the situation and evolution of the productivity of the tourism industry in the Andalusian region, and more specifically of the hotel and catering branch, relating it to the organisational structure of its businesses. First of all, the issue of the definition and limitation of the concept of productivity applied to the services sector is addressed, as traditionally this concept is focused on manufacturing, and the different ways of measuring and the analysis methods are reviewed. Then, using the accounting information provided by the Balances Centre of Andalusia (CBA), the general features of the organisational structure of the hotel and catering industry in de Andalusian region, stratifying the samples by the size of the companies and examining the medium size of the Andalusian hotel and catering businesses. Once the organisational structure of the sector is analysed, it is related to the state and evolution of its productivity, using a simple ratio between the brute added value and the personnel expenses, and completing this analysis with a relative efficiency index, the Baldwin efficiency index, with which the technical efficiency of each company is compared to the mass of most efficient companies. As a result of this research it is observed that the productivity indexes increase as web as the size of the companies and during the considered period, especially in the case of the medium sized and large companies. Nevertheless, these productivity increases are less relevant than the increase of employment, especially in case of smaller companies.

Simulación de oleaje para el estudio de vulnerabilidad de obras marítimas

La R.O.M. 0.0 establece que en las verificaciones de las obras marítimas de más relevancia se calculará la probabilidad de fallo de la estructura. Dentro de este contexto es becesaria una metodología que genere las acciones a considerar de forma aleatori

Relative efficiency within a tax administration: The effects of result improvement

Neste trabalho, aborda-se a análise da administração tributária espanhola mediante a avaliação da eficiência relativa de cada um dos escritórios territoriais que a integram, empregando, para isso, a análise envolvente de dados de forma bietápica, com uma orientação output. Neste estudo, analisaram-se 47 escritórios territoriais considerando três inputs: 1) os gastos correntes em bens e serviços; 2) o número de declarações gerenciadas pelos dois principais impostos diretos e 3) o número de efetivos que presta seus serviços. Como output, os Ingressos por Atos de Liquidação. A análise demonstra que uma atuação eficiente dos escritórios territoriais poderia ter aumentado em 21,6% os resultados da gestão dessa Administração.This paper analyses the Spanish tax administration, evaluating the relative efficiency of each of the regional offices that are its constituent parts via output-oriented two-stage data envelopment analysis. In the study, a total of 47 regional offices were analysed, considering three inputs: 1) current expenditure in goods and services; 2) number of tax returns processed in terms of the two main direct taxes; and, 3) personnel numbers. Revenue resulting from tax assessments was considered as output. The analysis shows that the efficient action of regional offices might have increased by 21.6% the results of the management of this administration.A través de este trabajo se ha abordado el análisis de la administración tributaria española mediante la evaluación de la eficiencia relativa de cada una de las oficinas territoriales que la integran, empleando para ello el análisis envolvente de datos de forma bietápica, con una orientación output. En el estudio se han analizado 47 oficinas territoriales, considerando tres inputs: 1) los gastos corrientes en bienes y servicios; 2) el número de declaraciones gestionadas por los dos principales impuestos directos; y 3) el número de efectivos que presta sus servicios. Como output los Ingresos por Actos de Liquidación. El análisis pone de manifiesto que una actuación eficiente de las oficinas territoriales podría haber incrementado un 21.6% los resultados de la gestión de esta Administración

Grado de autocompasión en deportistas de alto rendimiento lesionados

It has been observed how self-compassion improves adaptive coping, well-being and reduces anxiety in situations of stress. The present study tried to see if there were significant differences in the level of self-compassion in high-performance athletes with or without injury at different times of the season. With a sample composed of 79 athletes from different disciplines, it was carried out through the Scale of Self-compassion SCS in Spanish, summarized from 12 articles (García-Campayo, Navarro, Andrés, Mortero, López and Piva, 2014). The results collected in this research were not conclusive or significant, so it would be advisable for future studies with a larger sample, in contexts of sports injury and with a psychological intervention of the environment.  Se ha observado como la autocompasión mejora el afrontamiento adaptativo, bienestar y reduce la ansiedad en situaciones de estrés. El presente estudio trató de ver si existían diferencias significativas en el nivel de autocompasión en deportistas de alto rendimiento con o sin lesión en momentos diferentes de la temporada. Con una muestra compuesta de 79 deportistas de diferentes disciplinas, se llevo a cabo a través de la Escala de Autocompasión SCS en español resumida de 12 items (Garcia-Campayo, Navarro, Andrés, Mortero, López, & Piva, 2014),. Los resultados recogidos en esta investigación no fueron concluyentes ni significativos, por lo que se recomendaría efectuar estudios futuros similares con una mayor muestra,  en contextos de lesión deportiva y con una intervención psicológica de por medio

On the effective deployment of current machine translation technology

Machine translation is a fundamental technology that is gaining more importance each day in our multilingual society. Companies and particulars are turning their attention to machine translation since it dramatically cuts down their expenses on translation and interpreting. However, the output of current machine translation systems is still far from the quality of translations generated by human experts. The overall goal of this thesis is to narrow down this quality gap by developing new methodologies and tools that improve the broader and more efficient deployment of machine translation technology. We start by proposing a new technique to improve the quality of the translations generated by fully-automatic machine translation systems. The key insight of our approach is that different translation systems, implementing different approaches and technologies, can exhibit different strengths and limitations. Therefore, a proper combination of the outputs of such different systems has the potential to produce translations of improved quality. We present minimum Bayes¿ risk system combination, an automatic approach that detects the best parts of the candidate translations and combines them to generate a consensus translation that is optimal with respect to a particular performance metric. We thoroughly describe the formalization of our approach as a weighted ensemble of probability distributions and provide efficient algorithms to obtain the optimal consensus translation according to the widespread BLEU score. Empirical results show that the proposed approach is indeed able to generate statistically better translations than the provided candidates. Compared to other state-of-the-art systems combination methods, our approach reports similar performance not requiring any additional data but the candidate translations. Then, we focus our attention on how to improve the utility of automatic translations for the end-user of the system. Since automatic translations are not perfect, a desirable feature of machine translation systems is the ability to predict at run-time the quality of the generated translations. Quality estimation is usually addressed as a regression problem where a quality score is predicted from a set of features that represents the translation. However, although the concept of translation quality is intuitively clear, there is no consensus on which are the features that actually account for it. As a consequence, quality estimation systems for machine translation have to utilize a large number of weak features to predict translation quality. This involves several learning problems related to feature collinearity and ambiguity, and due to the ¿curse¿ of dimensionality. We address these challenges by adopting a two-step training methodology. First, a dimensionality reduction method computes, from the original features, the reduced set of features that better explains translation quality. Then, a prediction model is built from this reduced set to finally predict the quality score. We study various reduction methods previously used in the literature and propose two new ones based on statistical multivariate analysis techniques. More specifically, the proposed dimensionality reduction methods are based on partial least squares regression. The results of a thorough experimentation show that the quality estimation systems estimated following the proposed two-step methodology obtain better prediction accuracy that systems estimated using all the original features. Moreover, one of the proposed dimensionality reduction methods obtained the best prediction accuracy with only a fraction of the original features. This feature reduction ratio is important because it implies a dramatic reduction of the operating times of the quality estimation system. An alternative use of current machine translation systems is to embed them within an interactive editing environment where the system and a human expert collaborate to generate error-free translations. This interactive machine translation approach have shown to reduce supervision effort of the user in comparison to the conventional decoupled post-edition approach. However, interactive machine translation considers the translation system as a passive agent in the interaction process. In other words, the system only suggests translations to the user, who then makes the necessary supervision decisions. As a result, the user is bound to exhaustively supervise every suggested translation. This passive approach ensures error-free translations but it also demands a large amount of supervision effort from the user. Finally, we study different techniques to improve the productivity of current interactive machine translation systems. Specifically, we focus on the development of alternative approaches where the system becomes an active agent in the interaction process. We propose two different active approaches. On the one hand, we describe an active interaction approach where the system informs the user about the reliability of the suggested translations. The hope is that this information may help the user to locate translation errors thus improving the overall translation productivity. We propose different scores to measure translation reliability at the word and sentence levels and study the influence of such information in the productivity of an interactive machine translation system. Empirical results show that the proposed active interaction protocol is able to achieve a large reduction in supervision effort while still generating translations of very high quality. On the other hand, we study an active learning framework for interactive machine translation. In this case, the system is not only able to inform the user of which suggested translations should be supervised, but it is also able to learn from the user-supervised translations to improve its future suggestions. We develop a value-of-information criterion to select which automatic translations undergo user supervision. However, given its high computational complexity, in practice we study different selection strategies that approximate this optimal criterion. Results of a large scale experimentation show that the proposed active learning framework is able to obtain better compromises between the quality of the generated translations and the human effort required to obtain them. Moreover, in comparison to a conventional interactive machine translation system, our proposal obtained translations of twice the quality with the same supervision effort.González Rubio, J. (2014). On the effective deployment of current machine translation technology [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/37888TESI

Síntesis y ensamblaje de nanoestructuras plasmónicas de oro uniformes para aplicaciones en biomedicina

Tesis de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Química Física I, leída el 30-06-2017Se espera de la nanociencia y la nanotecnología que hagan frente a muchos de los retos que amenazan nuestro futuro, desde el almacenamiento de energía hasta la cura de enfermedades. En este contexto, las nanopartículas de oro se encuentran entre los sistemas que están a la cabeza de esta lucha, ofreciendo una combinación única de propiedades ópticas modulables (resonancias plasmónicas superficiales localizadas, LSPRs) y alta estabilidad química con reactividad controlable. Entre la gran variedad de campos de aplicación cubiertos por las nanopartículas de oro, su uso en la detección, el diagnóstico y el tratamiento de enfermedades humanas pueden ser de las que produzcan un mayor impacto en la sociedad. En esta tesis titulada "Síntesis y Ensamblaje de Nanoestructuras Plasmónicas de Oro Uniformes para Aplicaciones en Biomedicina", hemos trabajado en el desarrollo de enfoques novedosos para la síntesis de nanoestructuras plasmónicas que puedan utilizarse para el diagnóstico y tratamiento de diversas enfermedades humanas. Específicamente, los aspectos fundamentales en ella tratados son la síntesis de nanopartículas de oro con propiedades ópticas específicas y su subsiguiente funcionalización y/o auto-ensamblaje, con el objetivo de explotarlas para estudiar y detectar el proceso de amiloidogénesis, así como su aplicación en terapia fototérmica. Una de las principales innovaciones de este trabajo es la implementación de los láseres pulsados como herramientas valiosas para controlar algunos de los aspectos anteriormente mencionados. Como primera estrategia se han sintetizado nanoesferas de oro con elevada monodispersidad y se han auto-ensamblado sobre sustratos usando plantillas piramidales, mediante funcionalización con polietilenglicol tiolado y en presencia de pequeñas concentraciones de un surfactante catiónico. Siguiendo con el concepto de síntesis y funcionalización racionales, se fabricaron nanovarillas de oro y se estabilizaron con el modelo prionoide RepA-WH1. Este enfoque nos permitió inducir la formación de oligómeros amiloides, especies tóxicas que juegan un papel clave en la etiología de una serie de devastadoras enfermedades humanas degenerativas. Además, aprovechamos la sensibilidad de las LSPR y las propiedades de las nanopartículas plasmónicas para incrementar la señal Raman de moléculas (SERS) para monitorizarlo. En una segunda aproximación, aprovechamos la fuerte interacción de las nanopartículas plasmónicas con pulsos láser de femtosegundos para el auto-ensamblaje de nanopartículas de oro anisótropas, así como para su uso en terapia fototérmica...Depto. de Química FísicaFac. de Ciencias QuímicasTRUEunpu

Comparing Protonolysis and Transmetalation Reactions: Microcalorimetric Studies of C–AuI Bonds in [AuRL] Complexes

Producción CientíficaThe protonolysis of C–Au bonds in [AuRL] organometallic complexes has been studied by calorimetry for twelve R groups. The experimental data have been combined with DFT calculations to obtain Bond Dissociation Energy values (BDE). The C–Au BDE values show a good correlation with the corresponding isolobal C–H BDE values. The heat released in the protonolysis of [AuRL] has also been measured for R = Ph and L = P(OPh)3, PPh3, PMe3, PCy3, and IPr, and these values strongly depend on the trans influence of L because of the mutual destabilization of the L–Au and Au–C bonds. The enthalpy of the transmetalation reactions [AuR(PPh3)] + SnIBu3 → [AuI(PPh3)] + SnRBu3 for seven R groups have been measured and compared with the corresponding [AuR(PPh3)] protonolysis.Ministerio de Economía, Industria y Competitividad (Project CTQ2016-80913-P)Junta de Castilla y León (Project VA 051P17