Optical Supersymmetry in the Time Domain

Originally emerged within the context of string and quantum field theory, and later fruitfully extrapolated to photonics, the algebraic transformations of quantum-mechanical supersymmetry were conceived in the space realm. Here, we introduce a paradigm shift, demonstrating that Maxwell's equations also possess an underlying supersymmetry in the time domain. As a result, we obtain a simple analytic relation between the scattering coefficients of a large variety of time-varying optical systems and uncover a wide new class of reflectionless, three dimensional, all-dielectric, isotropic, omnidirectional, polarization-independent, non-complex media. Temporal supersymmetry is also shown to arise in dispersive media supporting temporal bound states, which allows engineering their momentum spectra and dispersive properties. These unprecedented features define a promising design platform for free-space and integrated photonics, enabling the creation of a number of novel reconfigurable reflectionless devices, such as frequency-selective, polarization-independent and omnidirectional invisible materials, compact frequency-independent phase shifters, broadband isolators, and versatile pulse-shape transformers

Can ecosystem properties be fully translated into service values? an economic valuation of aquatic plant services

Ecological Applications 21. 5 (2011): 3083-3103 copyright by the Ecological Society of AmericaWe carried out an integrated analysis of ecosystem services in the Doñana social-ecological system (southwestern Spain), from the providers (different aquatic plant functional groups) to the beneficiaries (different stakeholders living in or visiting the area). We explored the ecosystem services supplied by aquatic plants by linking these services to different plant functional traits, identifying relevant ecosystem services and then working our way backward to ecosystem properties and the functional traits underpinning them. We started from 15 ecosystem services associated with aquatic systems (freshwater marshes, salt marshes, ponds on aeolian sheets, temporal coastal ponds, and estuaries) and related them to plant traits (directly or indirectly through intermediate ecosystem properties). We gathered information from the literature on the functional traits of 144 plants occurring in the aquatic ecosystems of Doñana. We analyzed the species×trait matrix with multivariate classification and ordination techniques and obtained seven functional groups with different potentials for delivering ecosystem services. A survey was then administered to 477 stakeholders to analyze, through the use of a contingent valuation exercise, how the ecosystem services provided by the different functional groups were valued. We identified connections between individual plant traits, ecosystem processes, and ecosystem services, but a mismatch appeared between the functional groups and the economic values placed on them by the beneficiaries. We found that contingent valuation applied to ecosystem services tended to ignore the ecosystem properties and biodiversity underpinning them. Our results cast doubts over the suitability of the economic valuation framework of ecosystem services to capture the full value of biodiversity and ecosystems to peopleThis research was partially supported by a grant from the Madrid Regional Government of Education, which was co-funded by the Social European Fund (F.S.E.), the Spanish Ministry of Education and Science (Project CGL2006- 14121/BOS), and the Spanish Ministry of the Environment and Rural and Marine Affairs through project 018/2009. S. Díaz acknowledges support from FONCyT and CONICET (Argentina) and IAI (CRN 2015, supported by US NSF GEO- 0452325

Patterns of Fluctuation of Employment in the European Union: National Cycles and Effects of Tertiarization

The paper has two aims. First, to study the possible relationships existing between cyclical fluctuations of employment by countries in the EU and the EU as a whole. And, second, to analyse the effects produced by the intense and increasing growth of employment in service industries in such fluctuations. In short, a first aim is to analyse the fact that cyclical movements of employment by countries (EU context)show some diffenreces and, on the second objective is to explore if the increasing presence of services in the employment structure has or not important consequences on employment fluctuations at national level. The first part of the paper analyses the cyclical fluctuations of employment in each of the EU countries, as a basis to set up the differences btw. countries and to establish the European cycle of employment. The second part is focused on the study of the apparent relationship existing between national fluctuations of employment and the structural changes as an explaining factor. Finally, the paper also analyses if there is or not a process of convergence (progressive adjustment) between the European countries and if they tend to adjust themselves to the more general trends observed. The lack of a European data-base on employment fluctuations at regional level (quarterly) impedes actually to extend the analysis to this level. Nevertheless, a case-study on a country and its regions will be included to test the differences/coincidences compared to the paper's general conclusions.

Sectorial structure, qualitative characteristics and guidelines of labour mobility in the European Union.

In the context of the process of construction of a single labour market in the Economic Union, one of the greatest problems is the existence of certain levels of structural unemployment. From this point of view, the imbalance between the qualification characteristics of work supply and demand as well as the determining factors of geographical mobility among jobs become a relevant explication factor. The aim of the paper will be to carry out a comparative analysis of some of the most important characteristics of employment in European countries. For this, how different employed population groups are distributed by sectors of activity and labour occupations will be analysed, how these structures have been modified over time, and the patterns of labour mobility that interconnect activities and occupations in the framework of labour mobility, in order to see whether these evolutions are leading to an assimilation of labour characteristics in the countries, or not. Keywords: labour mobility, employment, service sector, European Union. JEL-Code: J62, L80, F02

Does tertiarization explain differences in labour market behaviour?: A cross national approach refering to European Union

There are ever more works which identify the service sector as the principal protagonist in the creation of employment in western economies, with respect to the recent past and in the near future. At the same time, agreement exists regarding the profound transformations that work characteristics are undergoing, a processs which can be finally expressed as an increment in what we could call "work flexibility". With reference to the previous questions, in the European Union very varied disparities can be found. Whilst employment in Ireland and in Spain increased noticeably between 1994 and 2000, (37 and 23% respectively), in Austria the increase was only 0.9% and in Germany 3%. On the other hand, we can also find great differences in labour behviour in terms of flexibility and rigidity. The thesis which we endeavour to prove in the work is double: In what measure do the services ( and their internal composition) explain both the processes of employment creation and the increment of job flexibility observed in the EU? In what measure do the differences in tertiarization (and their internal composition) in the EU countries explain the heterogeneity observed in both employment creation and increased job dynamics? For this, and by means of the data of the "European Household Panel", the paper will have the following scheme: a) In first place, the behaviour of job markets in the European Union countries will be revised (employment creation, the presence of services and the processes of tertiarization). b) Then the internal composition of the tertiary sector will be analyzed in each of these countries, checking the extent in which they are similar or different. c) Finally, using shift-share techniques the relation between tertiarization, processes of employment creation and work flexibility (through indicators of labour mobility) will be analyzed, in relation to the EU and to each of the member countries.

Artisans and Social Change: The Madrid Tanners in the Seventeenth Century

Esta investigación analiza los recursos y medios que desarrollaron los curtidores madrileños para enfrentarse al contexto social y económico que existió en el siglo XVII. El matrimonio y la maestría fueron los dos pivotes sobre los que gravitó una estrategia colectiva que tenía por objetivo mantener un relativo control sobre la renovación del oficio, para lo cual resultaba fundamental la consecución de una organización jerárquica y cohesionada en el oficio. Este estudio introduce el análisis de la red social de los curtidores como parte esencial de las distintas prácticas económicas, sociales y culturales que desplegaron los curtidores para lograr sus fines.This research analizes the resources and means developed by the tanners in Madrid in order to cope with the economic and social context during the Seventeenth Century. Marriage and mastery were the two pillars of a collective strategy aimed to keep a relative control over the trade renewal. To achieve this, it was fundamental a hierarchical and cohesive organization of the trade. This research introduces the analysis of the tanners social net as an essential part of the different economic, social and cultural working practice developed by them in order to achieve their aims tanners

Sectoral structure, qualification characteristics and patterns of labour mobility

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Service Industries Journal on 1/07/2007, available online at:http://www.tandfonline.com/10.1080/02642060701346607The paper has two main objectives. First, to investigate whether workers show significant differences in labour opportunities. Second, to test the hypothesis that tertiarisation has important effects explaining it. The hypotheses are: (1) tertiarisation has relevant effects on the structure of labour demand by skills; (2) the labour opportunities of workers can be influenced by the skills developed in their previous jobs and their concordance between sectoral changes. From a methodological point of view, the approach implies a study of labour transition data of workers, sectoral change and its qualification implications. In order to research the previous argument, the authors analyse labour mobility within European countries. Therefore, data used in the paper come from the European Community Household Panel (ECHP). All descriptive analyses have been carried out and the results from dynamic logit panel data model suggest that the relation of workers to tertiarisation and its implications approximated by their previous labour situation (sector and skill) are significant, explaining differences observed in labour transitions and its characteristics

Highly skilled immigration and its impact on the labour market in Europe

La inmigración de alta cualificación reviste actualmente una creciente importancia y, dadas sus características específicas y su posible posición estratégica en los procesos de trabajo, el estudio de sus efectos resulta especialmente relevante. Este artículo analiza el impacto laboral que tiene la presencia de población inmigrante con estudios superiores sobre las oportunidades laborales de los trabajadores nativos en una selección de países europeos que poseen una mayor población inmigrante de este tipo. Tras describir sus características más relevantes, se realizan distintas estimaciones econométricas para establecer cuál es el efecto laboral inducido por este colectivo. Los resultados apuntan a un efecto negativo, pero de carácter muy moderado, sobre la tasa de empleo de los nacionales para los países de España, Alemania, Francia y Suiza, e incluso un ligerísimo efecto positivo en el caso de Italia y Reino Unido. Highly skilled immigration is currently growing significantly and, given its specific features and possible strategic position in labour processes, the study of its effects is particularly important. This article analyses the labour impact of the presence of an immigrant population with higher education on the job opportunities of national workers in a selection of European countries that possess a large immigrant population of this type. After describing their most significant characteristics, various econometric estimates are used to establish the labour effect exerted by this group. The results indicate an effect that is negative, but only moderately, on the employment rates of the nationals of Spain, Germany,France and Switzerland, and even a slightly positive effect in the cases of Italy and the United Kingdom. DOI: doi.org/10.24241/AnuarioCIDOBInmi.2017.15