Social security and the search behaviour of workers approaching retirement

This paper explores the links between unemployment, retirement and their associated public insurance programs. It is a contribution to a growing body of literature focused on a better understanding of the labor behavior of advanced—age workers, which has gained importance as the pension crisis looms. The analysis combines the development of a new theoretical model and a detailed exploration of the empirical regularities using the Spanish Muestra Continua de Vidas Laborales (MCVL) dataset. The model is a extension of the standard search model, designed to reproduce the non—stationary environment faced by workers approaching retirement and to explore the interaction of unemployment benefits and retirement pensions. Via calibrated simulations we show that the basic empirical reemployment and retirement patterns can be rationalized as the optimal responses to both the labor market conditions and the institutional incentives. Generous Unemployment Benefits (for durations of up to two years) together with very significant early retirement penalties, make optimal to stay unemployed without searching for large groups of unemployed workers. This moral hazard problem can he substantially alleviated through institutional reform. Setting the early retirement penalties according to the age when the individual withdraws from the labor force (rather than when he/she claims the pension for the first time) seems particularly beneficial. It increases the labor supply, reduces the financial cost for the social security system and generate enough extra resources to compensate for the welfare loss of those unemployed directly hit by the reform.Unemployment search, job benefit, retirement

Spinor calculus on 5-dimensional spacetimes

Penrose's spinor calculus of 4-dimensional Lorentzian geometry is extended to the case of 5-dimensional Lorentzian geometry. Such fruitful ideas in Penrose's spinor calculus as the spin covariant derivative, the curvature spinors or the definition of the spin coefficients on a spin frame can be carried over to the spinor calculus in 5-dimensional Lorentzian geometry. The algebraic and differential properties of the curvature spinors are studied in detail and as an application we extend the well-known 4-dimensional Newman-Penrose formalism to a 5-dimensional spacetime.Comment: Convention mismatch and minor typos fixed. To appear in Journal of Mathematical Physic

Materiales funcionales: de compuestos inorgánicos a polímeros de coordinación

Peer reviewe

A comment on "Intergenerational equity: sup, inf, lim sup, and lim inf"

We reexamine the analysis of Chambers (Social Choice and Welfare, 2009), that produces a characterization of a family of social welfare functions in the context of intergenerational equity: namely, those that coincide with either the sup, inf, lim sup, or lim inf rule. Reinforcement, ordinal covariance, and monotonicity jointly identify such class of rules. We show that the addition of a suitable axiom to this three properties permits to characterize each particular rule. A discussion of the respective distinctive properties is provided.Social welfare function; Intergenerational equity; Lim sup ; Lim inf

Rational choice by two sequential criteria

This paper contributes to the theory of rational choice under multiple criteria. We perform a preliminary study of the properties of decision made by the sequential application of rational choices. This is then used to obtain a characterization of set-valued choice functions that are rational by two sequential criteria, which follows the approach initiated by Manzini and Mariotti (Amer. Econ. Rev., 2007) for single-valued choice functions. Uniqueness is not guaranteed but our proof is constructive and an explicit solution is provided in terms of approximation choice functions.Choice function; rational choice; compound function.

Why College? Making the Decision

A four year college degree may be one of the largest investments a person can make in their lifetime in terms of the time, effort, and money. Making this personal investment may be life-changing, which is why it is so important that one take the decision making process to attend college seriously. This study sought to investigate how and why students decide to pursue an undergraduate college degree. Undergraduate students were surveyed with a series of questions in hopes of acquiring a better understanding of what factors they take into account in their decision making process. The hypothesis was that students do not engage in a comprehensive college decision making process as they should. Results indicated that most students believe to have dedicated an appropriate amount of time and effort investigating their options and making the decision to pursue a college degree. Implications of this study suggest that most students are satisfied with their decision to attend college; however, a low percentage of the undergraduate students surveyed considered alternatives to attending college right after graduating high school. Further and refined research studies are proposed

Theory of phase spectroscopy in bimodal atomic force microscopy

We develop a theoretical formalism to escribe bimodal atomic force microscopy (AFM) experiments. The theory relates observables such as amplitudes and phase shifts to physical properties of the tip-surface interaction. The theory is compatible with point-mass and continuous models of the cantilever-tip system. We explain the ability of the bimodal AFM to map compositional variations under the influence of very small conservative forces. This is achieved by representing the dependence of the phase shift or amplitude of one eigenmode with respect to the amplitude or phase shift of the other mode. The agreement obtained between the theory and the numerical simulations validates the theoretical formalism.This work was financially supported by the European Commission (FORCETOOL Contract No. NMP4-CT-2004-013684), Ministerio de Educación y Ciencia (Contract No. MAT2006-03833), and Comunidad de Madrid. We do thank stimulating discussions with N. F. Martinez and E. T. Herruzo.Peer reviewe

Distribución vertical de la macrofauna en sedimentos contaminados del interior del puerto de Ceuta

Se ha estudiado la distribución vertical de la macrofauna y su relación con las variables fisicoquímicas de los sedimentos contaminados del puerto de Ceuta. La obtención de las muestras se llevó a cabo mediante buceo con escafandra autónoma y empleando instrumentos de muestreo tipo core (10 cm × 17 cm × 35 cm), diferenciándose las siguientes profundidades en la columna de sedimento: 0-2 cm, 2-5 cm, 5-10 cm y más de 10 cm. Los crustáceos Pariambus typicus Kröyer, 1844; Apseudes latreilli Milne-Edwards, 1820; Corophium runcicorne Della Valle, 1893; C. sextonae Crawford, 1937; el molusco Parvicardium exiguum (Gmelin, 1791) y los poliquetos Pseudomalacoceros tridentata (Southern, 1914) y Exogone verrugera Cleparede, 1868 se localizaron en los dos primeros centímetros de sedimento, mientras que el molusco Loripes lacteus (L., 1758) y los poliquetos Platynereis dumerilii Audouin y Milne-Edwards, 1833; Cirratulus cirratus (Muller, 1776) y Cirriformia tentaculata (Montagu, 1808) dominaron en los niveles más profundos, observándose el incremento en el tamaño de los individuos con el aumento de la profundidad. Los análisis multivariantes reflejaron que el porcentaje de pelitas, la materia orgánica total y, especialmente, la relación lípidos malténicos/lípidos asfalténicos, fueron los principales factores condicionantes de la distribución vertical de las especies en el sedimento.Vertical distribution of the macrofauna in polluted sediments from the harbour of Ceuta Vertical distribution of the macrofauna and its relationship with physico-chemical parameters were studied in polluted sediments from the harbour of Ceuta. The samples were collected with cores (10 cm × 17 cm × 35 cm) by scuba divers. The following depths in the sediment column were included in the study: 0-2 cm, 2- 5 cm, 5-10 cm and more than 10 cm. The crustaceans Pariambus typicus Kröyer, 1844; Apseudes latreilli Milne-Edwards, 1820; Corophium runcicorne Della Valle, 1893; C. sextonae Crawford, 1937; the mollusc Parvicardium exiguum (Gmelin, 1791), and the polychaetes Pseudomalacoceros tridentata (Southern, 1914) and Exogone verrugera Cleparede, 1868 were found in the first 2 cm of the sediment, whereas the mollusc Loripes lacteus (L., 1758) and the polychaetes Platynereis dumerilii Audouin & Milne Edwards, 1833; Cirratulus cirratus (Muller, 1776) and Cirriformia tentaculata (Montagu, 1808) were dominant in deeper strata, and size increased with depth. A multivariate analysis showed that the percentage of silt and clays, the total organic matter, and especially, the maltenes/asphaltenes ratio, were the main factors affecting species’ vertical distribution

Metodos analiticos para suelos acidos y plantas

La cuantificacion analitica de suelos y tejidos vegetales es un instrumento efectivo para interpretar la existencia de deficiencias o excesos de minerales. El uso adecuado de esta informacion influye significativamente en las recomendaciones de fertilizantes. Sin embargo, debe admitirse que existe conflicto en las fases de cuantificacion, interpretacion y recomendacion debido a la alta variabilidad existente en estas fases. Generalmente, la variabilidad es la consecuencia de la diversidad de metodos analiticos empleados y de los criterios tecnicos adoptados en la interpretacion y en la recomendacion de fertilizantes en las areas tropicales. Resulta utopico tratar de uniformizar las tres fases para todos los suelos existentes en los paises de America Tropical, asi como para todo tejido vegetal. Sin embargo, resulta bastante desventajoso que suelos con propiedades quimicas comparables en America Tropical tengan una variabilidad en las fases mencionadas y principalmente en la cuantificacion analitica. En consecuencia, el proposito de este manual es describir metodos estandarizados de procedimientos analiticos para suelos acidos y tejido vegetal con el fin de satisfacer por los menos tres objetivos: (1) enterar a investigadores de suelos en America Tropical de la metodologia analitica para suelos acidos y tejido vegetal; (2) incrementar entre instituciones nacionales e internacionales el intercambio de metodos empleados en America Tropical y (3) hacer del analisis de suelos y plantas una parte dinamica de la investigacion en los tropicos. (RA