The Optimality of the Common Fisheries Policy: the Northern Stock of Hake

We evaluate the management of the Northern Stock of Hake during 1986-2001. A stochastic bioeconomic model is calibrated to match the main features of this fishing ground. We show how catches, biomass stock and profits would have been if the optimal Common Fisheries Policy (CFP) consistent with the target biomass implied by the Fischler’s Recovery Plan had been implemented. The main finding are: i) an optimal CFP would have generated profits of more than 667 millions euros, ii) if side-payments are allowed (implemented by ITQ’s, for example) these profits increase 26%.

A factor model of seasonality in stock returns

Published as an article in: The Quarterly Review of Economics and Finance, 2004, vol. 44, issue 2, pages 224-236.

Factores determinantes de la integración de la variable medio ambiente en los planteamientos de la economía de la empresa y el marketing

[ES] Actualmente las empresas se enfrentan a un nuevo reto: la integración de los aspectos medioambientales en la gestión y toma de decisiones empresariales. Varios han sido los factores desencadenantes, que han inducido a la Economía de la Empresa y al Marketing a introducir la variable medio ambiente en sus planteamientos, en aras a conformar una base teórica sistematizada que permita abordar con éxito las necesidades medioambientales de la clientela y de la sociedad. En este trabajo se analizan los factores que han contribuido a incrementar la importancia de la variable medio ambiente en la empresa, así como las causas que, en su día, motivaron su exclusión.

Activation of violaxanthin cycle in darkness is a common response to different abiotic stresses : a case study in Pelvetia canaliculata

Background: In the violaxanthin (V) cycle, V is de-epoxidized to zeaxanthin (Z) when strong light or light combined with other stressors lead to an overexcitation of photosystems. However, plants can also suffer stress in darkness and recent reports have shown that dehydration triggers V-de-epoxidation in the absence of light. In this study, we used the highly stress-tolerant brown alga Pelvetia canaliculata as a model organism, due to its lack of lutein and its non-photochemical quenching independent of the transthylakoidal-ΔpH, to study the triggering of the V-cycle in darkness induced by abiotic stressors. Results: We have shown that besides desiccation, other factors such as immersion, anoxia and high temperature also induced V-de-epoxidation in darkness. This process was reversible once the treatments had ceased (with the exception of heat, which caused lethal damage). Irrespective of the stressor applied, the resulting de-epoxidised xanthophylls correlated with a decrease in Fv/Fm, suggesting a common function in the down-regulation of photosynthetical efficiency. The implication of the redox-state of the plastoquinone-pool and of the differential activity of V-cycle enzymes on V-de-epoxidation in darkness was also examined. Current results suggest that both violaxanthin de-epoxidase (VDE) and zeaxanthin-epoxidase (ZE) have a basal constitutive activity even in darkness, being ZE inhibited under stress. This inhibition leads to Z accumulation. Conclusion: This study demonstrates that V-cycle activity is triggered by several abiotic stressors even when they occur in an absolute absence of light, leading to a decrease in Fv/Fm. This finding provides new insights into an understanding of the regulation mechanism of the V-cycle and of its ecophysiological roles.

El compromiso como variable mediadora para la predicción de las futuras intenciones de consumo en los servicios. Una aproximación empírica a los consumidores de artes escénicas en España

[ES] El presente trabajo de investigación trata de arrojar luz sobre las relaciones entre las variables Satisfacción, Compromiso, Confianza y Futuras Intenciones de compra. Con este fin, se propone un Modelo de Gestión de las Relaciones con Clientes de Servicios en el que se observa que la variable más importante en la consecución de resultados positivos en lo que respecta a intenciones de asistencia futura de los consumidores es el Compromiso.

Factores explicativos de la intención de emprender en la mujer. Aspectos diferenciales en la población universitaria según la variable género

El objetivo del presente trabajo de investigación es arrojar luz sobre los factores que explican la menor intencionalidad en la población femenina para involucrarse en procesos de creación de empresas. Para ello, se ha desarrollado un modelo de ecuaciones estructurales que identifica un conjunto de variables que permiten explicar la intención de emprender en la población potencialmente emprendedora. La validación del modelo se ha realizado mediante una encuesta realizada a 1222 estudiantes de 12 titulaciones diferentes de la Universidad de Málaga. La aplicación del modelo a las poblaciones masculina y femenina ha permitido apreciar diferencias significativas en los patrones de comportamiento en función del género, identificando un proceso más complejo y necesitado de apoyo externo en la población femenina con respecto a la masculina.

Use of generalised additive models to categorise continuous variables in clinical prediction

13 P.

Robust speed control for a variable speed wind turbine

Modern wind turbines are designed in order to work in variable speed opera-tions. To perform this task, these turbines are provided with adjustable speed generators, like the double feed induction generator (DFIG). One of the main advantages of adjustable speed generators is improving the system efficiency compared with _xed speed generators, because turbine speed can be adjusted as a function of wind speed in order to maximize the output power. However, this system requires a suitable speed controller in order to track the optimal reference speed of the wind turbine. In this work, a sliding mode control for variable speed wind turbines is proposed. The proposed design also uses the vector oriented control theory in order to simplify the DFIG dynamical equations. The stability analysis of the proposed controller has been carried out under wind variations and pa-rameter uncertainties using the Lyapunov stability theory. Finally, the simulated results show on the one hand that the proposed controller provides a high-performance dynamic behavior, and on the other hand that this scheme is robust with respect to parameter uncertainties and wind speed variations, which usually appear in real systems.

Adaptive variable structure control law for a variable speed wind turbine

Presentado en el 13th WSEAS International Conference on Automatic Control, Modelling and Simulation, ACMOS'11

Sliding mode control law for a variable speedwind turbine

Modern wind turbines are designed in order to work in variable speed operations. To perform this task, wind turbines are provided with adjustable speed generators, like the double feed induction generator. One of the main advantage of adjustable speed generators is improving the system efficiency compared to fixed speed generators, because turbine speed can be adjusted as a function of wind speed in order to maximize the output power. However this system requires a suitable speed controller in order to track the optimal reference speed of the wind turbine. In this work, a sliding mode control for variable speed wind turbines is proposed. An integral sliding surface is used, because the integral term avoids the use of the acceleration signal, which reduces the high frequency components in the sliding variable. The proposed design also uses the vector oriented control theory in order to simplify the generator dynamical equations. The stability analysis of the proposed controller has been carried out under wind variations and parameter uncertainties by using the Lyapunov stability theory. Finally simulated results show, on the one hand that the proposed controller provides a high-performance dynamic behavior, and on the other hand that this scheme is robust with respect to parameter uncertainties and wind speed variations, that usually appear in real systems.

Sliding mode control strategy for variable speed wind turbines

EFTA 2009

Variable structure control for maximum wind power extraction

EuroPES 2009

A common axiom for classical division rules for claims problems

In this paper we introduce a new axiom, denoted claims separability, that is satisfied by several classical division rules defined for claims problems. We characterize axiomatically the entire family of division rules that satisfy this new axiom. In addition, employing claims separability, we characterize the minimal overlap rule, given by O'Neill (1982), Piniles rule and the rules in the TAL-family, introduced by Moreno-Ternero and Villar (2006), which includes the uniform gains rule, the uniform losses rule and the Talmud rule.

Common Fixed Points of Generalized Rational Type Cocyclic Mappings in Multiplicative Metric Spaces

The aim of this paper is to present fixed point result of mappings satisfying a generalized rational contractive condition in the setup of multiplicative metric spaces. As an application, we obtain a common fixed point of a pair of weakly compatible mappings. Some common fixed point results of pair of rational contractive types mappings involved in cocyclic representation of a nonempty subset of a multiplicative metric space are also obtained. Some examples are presented to support the results proved herein. Our results generalize and extend various results in the existing literature.

Undertreatment of human immunodeficiency virus in psychiatric inpatients: a cross-sectional study of seroprevalence and associated factors

Background: The aims of this study were to evaluate the prevalence of HIV and its associated demographic and clinical factors among psychiatric inpatients of a general hospital. Methods: This was a single-center, observational, cross-sectional study that included patients consecutively admitted to our unit aged 16 years or older and with no relevant cognitive problems. The patients were evaluated using a semistructured interview and an appropriate test for HIV infection. Results: Of the 637 patients who were screened, 546 (86%) who consented to participate were included in the analyses. Twenty-five (4.6%, 95% confidence interval [CI] 3.0-6.8) patients were HIV-positive. The prevalence was higher among patients with substance misuse (17.4%, 95% CI 9.7-28.8). All except one of the 25 patients knew of their seropositive condition prior to participation in the study. Only 14 (56%) of the 25 seropositive patients had previously received pharmacological treatment for their infection. According to the multiple logistic regression analysis, the likelihood of HIV infection was lower in patients with higher levels of education and higher among patients who were single, had history of intravenous drug use, and had an HIV-positive partner, particularly if they did not use condoms. Among the patients with HIV infection, 18 (72%) had a history of suicide attempts compared with 181 (34.7%) of the patients without HIV infection (relative risk 2.1, 95% CI 1.6-2.7; P<0.001). Conclusion: HIV infection is highly prevalent in patients admitted to a psychiatric unit, especially those with a diagnosis of substance misuse. Seropositive patients show very poor treatment adherence. The risk of suicide seems to be very high in this population. Implementing interventions to reduce the suicide risk and improve adherence to antiretroviral therapy and psychotropic medications seems crucial.