Polymorphic phase boundary in piezoelectric oxides

The design of phase boundaries has now become a consolidated strategy to improve the functional properties of piezoelectric oxides because of the unique properties that may be obtained in their vicinity. In particular, polymorphic phase boundaries (PPBs) have attracted significant interest in recent years because they represent a significant breakthrough in terms of enhanced piezoelectric activity of lead-free piezoelectric oxides. PPBs are temperature-driven phase transitions where both intrinsic and extrinsic contributions maximize, thereby enhancing the macroscopic properties of piezoelectric materials. This tutorial discusses potassium–sodium–niobate-based systems as model materials to reveal some of the most relevant advances in the design of PPBs through compositional modifications. We focus on how PPBs can be modulated by engineered doping and also discuss the direct relation between PPBs and the enhancement of piezoelectric activity. Finally, we briefly describe the main experimental techniques for detecting PPBs.Postprint (author's final draft

Enhanced free space detection in multiple lanes based on single CNN with scene identification

Many systems for autonomous vehicles' navigation rely on lane detection. Traditional algorithms usually estimate only the position of the lanes on the road, but an autonomous control system may also need to know if a lane marking can be crossed or not, and what portion of space inside the lane is free from obstacles, to make safer control decisions. On the other hand, free space detection algorithms only detect navigable areas, without information about lanes. State-of-the-art algorithms use CNNs for both tasks, with significant consumption of computing resources. We propose a novel approach that estimates the free space inside each lane, with a single CNN. Additionally, adding only a small requirement concerning GPU RAM, we infer the road type, that will be useful for path planning. To achieve this result, we train a multi-task CNN. Then, we further elaborate the output of the network, to extract polygons that can be effectively used in navigation control. Finally, we provide a computationally efficient implementation, based on ROS, that can be executed in real time. Our code and trained models are available online.Comment: Will appear in the 2019 IEEE Intelligent Vehicles Symposium (IV 2019

Análisis de la relación entre la estrategia de diversificación y el desempeño de la empresa: el rol del ciclo económico

[EN] The relationship between corporate strategies and firm performance has been one of the key debates in the discipline of Strategic Management. There are studies that analyse the moderating role that certain variables may play in that relationship. These variables tend to refer to aspects within the firm or, at the very least, within the competitive environment in which a firm operates. Nevertheless, the empirical evidence on the part the general environment plays from an economic perspective is much less common, and focuses on large corporations and on periods of economic growth. Accordingly, using a panel of 1,828 Spanish manufacturing firms of different sizes, an analysis is conducted of the differences in Return On Assets (ROA), Growth in Sales (GS) and Labor Productivity (LP) between specialised firms, those with related diversification, and those with unrelated diversification, between 2002 and 2011, in which there was a period of growth alternated with another one of economic recession. Although some superiority is noted of related diversification and specialisation over unrelated diversification, the differences between strategies are less significant in periods of economic recession, and vary according to the dimension of performance considered. These results reveal the need to consider the economic cycle as a contingent factor that affects the impact corporate strategies have on firm performance.[ES] La relación entre las estrategias corporativas y el desempeño empresarial ha sido uno de los debates centrales en la disciplina de la dirección estratégica. Diversos estudios analizan el rol moderador que juegan diversas variables en esta relación. Dichas variables tienden a referirse a aspectos internos de la empresa o, si acaso, a aspectos del entorno competitivo en el que la empresa opera. Sin embargo, es más escasa la evidencia empírica sobre el rol que desempeña el entorno general y suele enfocarse en grandes empresas y en períodos de crecimiento económico. En consecuencia, utilizando un panel de 1.828 empresas manufactureras españolas de diferentes tamaños, se realiza un análisis de las diferencias de rentabilidad sobre activos, crecimiento de ventas y productividad laboral entre empresas especializadas, con diversificación relacionada y con diversificación no relacionada, entre los años 2002 y 2011, en los cuales hubo un período de crecimiento alternado con otro de recesión económica. Aunque se destaca cierta superioridad de la diversificación relacionada y la especialización sobre la diversificación no relacionada, las diferencias entre estrategias son menos significativas en los períodos de recesión económica y varían de acuerdo a la dimensión de desempeño considerada. Estos resultados revelan la necesidad de considerar el ciclo económico como un factor contingente que afecta el impacto que las estrategias corporativas tienen sobre el desempeño de la empresa.This paper has been supported by Project ECO2015-67434-R of Spanish Ministry of Economy and Competitiveness (Spain) and for the Excellent Research Group “Strategor” of URJC-Bank of Santander

Temporary help agencies and occupational mobility

This paper focuses upon the effect of Temporary Help Agencies (THAs) on occupational mobility through a comparison of the job-to-job upgrading chances of THA and non-THA workers. A screening approach to the role of these labor "brokers" suggests that agency workers can expect greater upgrading chances between two different occupations. Results obtained from a sample of Spanish workers show that working through these intermediaries allows workers in intermediate occupational levels to avoid occupational demotions more easily than non-THA ones. Moreover, THAs improve the probability for high-skilled workers of achieving a permanent contract. The empirical analysis demonstrates that the existence of self-selection is an important explanation for increased occupational mobility among THA workers in Spain

The nineties in Spain: too much flexibility in the youth labour market?

This paper examines movements into and out of employment in the Spanish youth labour market throughout the nineties. We analyze how differences in personal and economic circumstances influence such movements. In addition, we consider the importance of duration dependence in determining them. Our main findings are that: (i) Very young workers, women and those with lower qualification levels are more likely to be affected by high labour turnover; (ii) The existence of unobserved heterogeneity has important consequences in the unemployment hazard rate; (iii) In the 90's, employment hazard rates were substantially affected by the extensive use of fixed-term contracts, although the 1997 labour market reform seems to have reduced this hazard rate; (iv) The intervention of temporary help agencies has a positive impact on the likelihood of leaving unemployment, although only for short-term unemployed individuals; at the same time, however, the employment hazard rate is substantially higher within these agencies

The economic determinants of conditional conservatism.

We study the economic determinants of conditional conservatism. Consistent with prior literature, we find that contracting induces only conditional conservatism and litigation induces both conditional and unconditional conservatism. We extend prior evidence by Qiang (2007) by showing that taxation and regulation induce not only unconditional conservatism, but conditional conservatism as well. We show that in certain scenarios taxation and regulation create incentives to shift income from periods with high taxation pressure and high public scrutiny to periods with lower taxation pressure and lower public scrutiny. These income shifting strategies are implemented by recognising current economic losses that, given managerial incentives to report aggressively, would not have been recognized otherwise, or by delaying the recognition of current economic gains that would have been recognized had circumstances been different.Conservatism; Contracting; Taxation; Political costs; Litigation risk;