Renfe’s contribution to Spain’s economic growth between 1950 and 2000: sn initial estimation

The purpose of the article is to make a first appraisal of the contribution of the railway of Iberian gauge (Renfe) to the economic development experienced by the Spanish society throughout the second half of the 20th century. The text examine in the first place the benefits obtained by the different economic segments as a result of the rail-specific demand, and then proceeds to evaluate it in order to obtain its relative weight within the national economy. In the second section the same process is applied to the forward linkages, or effects on the economy of the availability of a more efficient transportation system.Economic History; Public Railway; RENFE; Railway History.

Nonlinear stability of mKdV breathers

Breather solutions of the modified Korteweg-de Vries equation are shown to be globally stable in a natural H^2 topology. Our proof introduces a new Lyapunov functional, at the H^2 level, which allows to describe the dynamics of small perturbations, including oscillations induced by the periodicity of the solution, as well as a direct control of the corresponding instability modes. In particular, degenerate directions are controlled using low-regularity conservation laws.Comment: 24 pp., submitte

Dynamics of complex-valued modified KdV solitons with applications to the stability of breathers

We study the long-time dynamics of complex-valued modified Korteweg-de Vries (mKdV) solitons, which are recognized because they blow-up in finite time. We establish stability properties at the H^1 level of regularity, uniformly away from each blow-up point. These new properties are used to prove that mKdV breathers are H^1 stable, improving our previous result, where we only proved H^2 stability. The main new ingredient of the proof is the use of a B\"acklund transformation which links the behavior of breathers, complex-valued solitons and small real-valued solutions of the mKdV equation. We also prove that negative energy breathers are asymptotically stable. Since we do not use any method relying on the Inverse Scattering Transformation, our proof works even under rough perturbations, provided a corresponding local well-posedness theory is available.Comment: 45 pages, we thank Yvan Martel for pointing us a gap in the previous version of this pape

Almost sharp nonlinear scattering in one-dimensional Born-Infeld equations arising in nonlinear Electrodynamics

We study decay of small solutions of the Born-Infeld equation in 1+1 dimensions, a quasilinear scalar field equation modeling nonlinear electromagnetism, as well as branes in String theory and minimal surfaces in Minkowski space-times. From the work of Whitham, it is well-known that there is no decay because of arbitrary solutions traveling to the speed of light just as linear wave equation. However, even if there is no global decay in 1+1 dimensions, we are able to show that all globally small $H^{s+1}\times H^s$, $s>\frac12$ solutions do decay to the zero background state in space, inside a strictly proper subset of the light cone. We prove this result by constructing a Virial identity related to a momentum law, in the spirit of works \cite{KMM,KMM1}, as well as a Lyapunov functional that controls the $\dot H^1 \times L^2$ energy.Comment: 12 pages; This is version 2. Some typos corrected and sections organized differently for ease readin

Feature-driven improvement of renewable energy forecasting and trading

M. A. Muñoz, J. M. Morales, and S. Pineda, Feature-driven Improvement of Renewable Energy Forecasting and Trading, IEEE Transactions on Power Systems, 2020.Inspired from recent insights into the common ground of machine learning, optimization and decision-making, this paper proposes an easy-to-implement, but effective procedure to enhance both the quality of renewable energy forecasts and the competitive edge of renewable energy producers in electricity markets with a dual-price settlement of imbalances. The quality and economic gains brought by the proposed procedure essentially stem from the utilization of valuable predictors (also known as features) in a data-driven newsvendor model that renders a computationally inexpensive linear program. We illustrate the proposed procedure and numerically assess its benefits on a realistic case study that considers the aggregate wind power production in the Danish DK1 bidding zone as the variable to be predicted and traded. Within this context, our procedure leverages, among others, spatial information in the form of wind power forecasts issued by transmission system operators (TSO) in surrounding bidding zones and publicly available in online platforms. We show that our method is able to improve the quality of the wind power forecast issued by the Danish TSO by several percentage points (when measured in terms of the mean absolute or the root mean square error) and to significantly reduce the balancing costs incurred by the wind power producer.European Research Council (ERC) under the EU Horizon 2020 research and innovation programme (grant agreement No. 755705) Spanish Ministry of Economy, Industry, and Competitiveness through project ENE2017-83775-P

Working career progress in the tourism industry : temp-to perm transitions in Spain

In this article, we analyze the dynamics of temporary workers’ transitions into permanent contracts for workers related to the tourism industry. For this purpose, we use an administrative retrospective dataset from Spanish Social security records. Results show that while individuals with a weaker attachment to the tourism industry achieve open-ended contracts sooner than in most other industries, on the contrary, it takes more time to those with a greater attachment to the tourism industry to exit from the temporary status. In addition, we find that for workers substantially engaged in the tourism industry, it takes more time to reach an open-ended contract when they have held between six and ten contracts in the past (as opposed to holding only one previous contract). On the contrary, for individuals with a weaker attachment to the tourism industry, holding between two and ten previous contracts implies a quicker exit from temporality

Long-term effects of involuntary job separations on labour careers

In this article, we analyse whether involuntary job separations present long-term effects upon individuals' careers, and the magnitude of such effects. For this purpose, the impact of involuntary job separations on three measures of occupational prestige is examined, using the British Household Panel Survey. Involuntary job separations are found to show a negative effect upon those occupational prestige scales. In particular, when additional involuntary job separations are suffered, this negative impact is persistent and cumulative. Moreover, this observed decrease in prestige levels is enhanced by the length of job separations. Our results help to explain why displaced workers suffer persistent earnings losses compared to non-displaced workers along their work-life history

Career breaks of women due to family reasons: a long-term perspective using retrospective data

In this article, we analyse whether family-related quits present long-term effects upon women's careers, and the magnitude of such effects. For this purpose, the impact of family-related breaks in the first ten years of their labour careers on three measures of occupational prestige is examined, using the British Household Panel Survey. Women who are intermittently attached to the labour market are found to work, on average, in occupations associated to significantly lower prestige levels. In particular, additional family-related interruptions have a negative impact that becomes persistent and cumulative. Moreover, the observed decrease in prestige levels is enhanced by the length of job separations

Breaks in women's careers due to family reasons: a long-term perspective

We analyse whether family-related quits present long-term effects upon women s careers, which are summarized in three measures of occupational prestige. There is an association between intermittent attachment to the labour market and being engaged in occupations with lower prestige levels. In causal terms, we find that women choose jobs with lower occupational prestige anticipating future family-related quits. The database consists of the retrospective information of the British Household Panel Surve