Quaternary glacial evolution in the Central Cantabrian Mountains (Northern Spain)

Peer reviewedPostprin

Outliers in Binary Choice Models

This paper focuses on the problem of outliers in binary choice models. It is show that identifying outliers as observation with a residual close to one in absolute value might be misleading and outlier detection procedures should rely on influence measures on the fit. Two scalar measures are derived to evaluate the influence of each observation as well as the influence of a group of observations on i) the vector of estimated parameters and ii) the vector of estimated probabilities. Also, the method proposed by Peña and Yohai (1995) to treat the problem of masking in linear models has been generalized to the case of binary choice models. A small Monte Carlo study analyzes the performance of a11 measures and an empirical application presents a diagnostic strategy for detection of outliers

A generalized least squares estimation method for VARMA models. (Revised edition).

In this paper a new generalized least squares procedure for estimating VARMA models is proposed. This method differs from existing ones in explicitly considering the stochastic structure of the approximation error that arises when lagged innovations are replaced with lagged residuals obtained from a long VAR. Simulation results indicate that this method improves the accuracy of estimates with small and moderate sample sizes, and increases the frequency of identifying small nonzero parameters, with respect to both Double Regression and exact maximum likelihood estimation procedures

Local characterization of the optical properties of annealed Au films on glass substrates

We present scanning near field microscopy and local spectroscopic characterisation of gold nanoparticles fabricated on glass sodalime cover slides. The nanoislands are fabricated by the thermal annealing of gold thin films. Results are presented for samples annealed at 300 °C, 400 °C, and 500 °C. We study the spectral dependence of the transmittance at the nanoscale level with respect to the nanoislands size, shape, and interparticle distance employing a Scanning Near-field Optical Microscopy

Observaciones anómalas en modelos de variable dependiente cualitativa

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Económicas y Empresariales, Departamento de Fundamentos del Análisis Económico II (Economía Cuantitativa), leída el 14-09-1993En este trabajo se estudian los problemas que aparecen en los modelos de variable dependiente cualitativa cuando, entre la muestra, se encuentra una proporción de observaciones generadas por un proceso estocástico distinto que para el resto. Se demuestra que la consecuencia de la presencia de datos anómalos es la inconsistencia del estimador máximo- verosímil. Por otro lado, se cuestiona el tratamiento dado en la literatura a este problema, derivando estadísticos de influencia adecuados a modelos de elección cualitativa. Todos los resultados teóricos desarrollados se ilustran tanto con experimentos de Montecarlo, como con aplicaciones a datos realesDepto. de Análisis Económico y Economía CuantitativaFac. de Ciencias Económicas y EmpresarialesTRUEpu

Observaciones anómalas en modelos de variable dependiente cualitativa

En este trabajo se estudian los problemas que aparecen en los modelos de variable dependiente cualitativa cuando, entre la muestra, se encuentra una proporción de observaciones generadas por un proceso estocástico distinto que para el resto. Se demuestra que la consecuencia de la presencia de datos anómalos es la inconsistencia del estimador máximo- verosímil. Por otro lado, se cuestiona el tratamiento dado en la literatura a este problema, derivando estadísticos de influencia adecuados a modelos de elección cualitativa. Todos los resultados teóricos desarrollados se ilustran tanto con experimentos de Montecarlo, como con aplicaciones a datos reale

The Internationalisation of the Spanish food industry: The home market effect and European market integration

The objective of this study was to analyse, from a long-term perspective, the factors determining the process of the internationalisation of the Spanish agrifood industry. The paper concentrates on the empirical verification of the existence of a home market effect in the food and drink industries in Spain and on the effects on trade flows of integration into the European Union. With this aim in mind, we took into account the latest contributions to the estimation of the gravity equation for a sample of export flows from 13 agrifood subsectors between 1970 and 2012, with a destination of 175 markets. From the results of the study the existence of the “home market effect” stands out as the determining factor of the increasing process of internationalisation in the majority of the subsectors of the food industry. On this point, the presence of this effect is remarkable in the most dynamic industries, where the process of restructuring caused by the development of the internal market was more intense. Furthermore, the influence of the process of European integration has been shown by the literature to be a very important factor. Our results qualify in part the results of previous studies, since the positive effect appeared later than expected. The positive effects did not appear until the completion of the process of transition by the dismantling of the barriers established in the treaty of accession to the European Union

HD Diesel engine equipped with a bottoming Rankine cycle as a waste heat recovery system. Part 2: Evaluation of alternative solutions

A theoretical investigation has been performed on the feasibility of introducing a waste heat recovery (WHR) system in a two-stage turbocharged HDD engine. The WHR is attained by introducing a Rankine cycle, which uses an organic substance or directly water as a working fluid depending on energetic performance considerations. A previous research was carried out to evaluate the maximum potential of this WHR concept, a conventional layout was used for coupling the Rankine cycle to the thermal engine. The objective of the present research is to broad the scope of the previous analysis by considering new alternative solutions for the problems related to the coupling between the WHR Rankine cycle and the thermal engine. These solutions are based on adapting one of the turbochargers by removing its turbine and trying to recover the energy by the Rankine cycle. Finally, the turbine of the Rankine cycle supplies the recovered energy directly to the compressor of this turbocharger. Thus, in these layouts the coupling is simpler as it involves only two turbomachines, which are supposed to share a similar rotating speed. From the results of the global energy balance, these alternative layouts produce slight benefits in fuel consumption but in all cases these benefits are lower compared to those attained with conventional layouts. © 2011 Published by Elsevier Ltd. All rights reserved.This work was partially funded by "Programa de Apoyo a la Investigacion y Desarrollo de la Universidad Politecnica de Valencia".Serrano Cruz, JR.; Dolz Ruiz, V.; Novella Rosa, R.; García Martínez, A. (2012). HD Diesel engine equipped with a bottoming Rankine cycle as a waste heat recovery system. Part 2: Evaluation of alternative solutions. Applied Thermal Engineering. 36:279-287. doi:10.1016/j.applthermaleng.2011.10.024S2792873

Optimization and validation of a new microbial inhibition test for the detection of antimicrobial residues in living animals intended for human consumption

Even though antibiotics are necessary in livestock production, they can be harmful not only due to their toxicity, but also in view of their contribution to the emergence of antimicrobial resistance. Screening tests based on microbial growth inhibition appeared to be useful tools to prevent its entry into the food chain. They have nevertheless been traditionally carried out post mortem, leading to great economical loss and harm to the environment in case a positive sample is found. Hence, the objective was to evaluate the use of a screening test as an ante mortem alternative for the detection of antibiotic residues in meat: thus, Explorer®-Blood test was optimized and validated. After adapting the procedure for matrix preparation, the assay parameters were assessed from 344 antibiotic-free blood serum samples. Limits of Detection (LoDs) were defined by spiking blood serum with several of the most common antimicrobials used in veterinary practice. LoDs were similar to those obtained for meat and were at or below the maximum residue limits set by EU legislation for muscle. Analyses of in vivo injected samples, previously characterized by LC-MS/MS, demonstrated the method’s accuracy and proved that Explorer®-Blood can be considered a suitable alternative to conventional post mortem screening methods