The role of unions in an endogenous growth model with human capital

In this paper we study the relationship between unions and growth in a two-sector overlapping generations model with altruism and human capital. This relationship depends on the interaction between the technology in the sector that produces human capital, the degree of unionization of the economy and the operativeness of the bequest motive.endogenous growth, unions, altruism, human capital

Lente oftalmológica terapéutica y profiláctica para ojos pseudo-afáquicos y/o en proceso de neurodegeneración

Lente oftalmológica terapéutica y profiláctica para ojos pseudo-afáquicos y/o en proceso de neurodegeneración. El objeto de la invención es una lente oftalmológica para ojos pseudo-afáquicos y/o con degeneración macular y retiniana, caracterizada por ser resultante de la aplicación de un filtro con pigmentación amarilla sobre una lente oftalmológica común, con el fin de protegerlos de las longitudes de onda corta del espectro visible (inferiores a 500 nm). Esta invención elude las dificultades y riesgos de las técnicas existentes para dotar de esta protección a los ojos operados de cataratas y mejorar la de aquéllos en procesos neurodegenerativos, lográndolo con la simple aplicación de una lente oftálmica. La invención consta de la combinación de una lente oftálmica común y un filtro de pigmentación amarilla que absorbe las longitudes de onda corta de 350/500 nm, ambos adecuados para su utilización en humanos

Life cycle assessment of drinking water: comparing conventional water treatment, reverse osmosis and mineral water in glass and plastic bottles

This study evaluated the environmental impacts caused by drinking water consumption in Barcelona (Spain) using the Life Cycle Assessment (LCA) methodology. Five different scenarios were compared: 1) tap water from conventional drinking water treatment; 2) tap water from conventional drinking water treatment with reverse osmosis at the water treatment plant; 3) tap water from conventional drinking water treatment with domestic reverse osmosis; 4) mineral water in plastic bottles, and 5) mineral water in glass bottles. The functional unit was 1 m3 of water. The water treatment plant considered in scenarios 1, 2 and 3, treats around 5 m3 s-1 of surface water. The water bottling plants considered in scenarios 4 and 5 have a production capacity of 200 m3 of bottled water per day. The LCA was performed with the software SimaPro®, using the CML 2 baseline method. The results showed how tap water consumption was the most favourable alternative, while bottled water presented the worst results due to the higher raw materials and energy inputs required for bottles manufacturing, especially in the case of glass bottles. The impacts generated by domestic reverse osmosis were between 10 and 24% higher than tap water alternative depending on the impact category. It was due to the higher electricity consumption. Reverse osmosis at the water treatment plant showed impacts nearly twice as high as domestic reverse osmosis systems scenario, mainly because of the higher energy inputs. Water treated by domestic reverse osmosis equipment was the most environmentally friendly solution for the improvement of tap water organoleptic characteristics. An economic analysis showed that this solution was between 8 and 19 times cheaper than bottled water.Peer ReviewedPostprint (author's final draft

Mirage Torsion

Z_NxZ_M orbifold models admit the introduction of a discrete torsion phase. We find that models with discrete torsion have an alternative description in terms of torsionless models. More specifically, discrete torsion can be 'gauged away' by changing the shifts by lattice vectors. Similarly, a large class of the so-called generalized discrete torsion phases can be traded for changing the background fields (Wilson lines) by lattice vectors. We further observe that certain models with generalized discrete torsion are equivalent to torsionless models with the same gauge embedding but based on different compactification lattices. We also present a method of classifying heterotic Z_NxZ_M orbifolds.Comment: 26 pages, 3 figures, v2: matches version published in JHE

Near-field EM wave scattering from random self-affine fractal metal surfaces: spectral dependence of local field enhancements and their statistics in connection with SERS

By means of rigorous numerical simulation calculations based on the Green's theorem integral equation formulation, we study the near EM field in the vicinity of very rough, one-dimensional self-affine fractal surfaces of Ag, Au, and Cu (for both vacuum and water propagating media) illuminated by a p polarized field. Strongly localized enhanced optical excitations (hot spots) are found, with electric field intensity enhancements of close to 4 orders of magnitude the incident one, and widths below a tenth of the incoming wavelength. These effects are produced by roughness-induced surface-plasmon polariton excitation. We study the characteristics of these optical excitations as well as other properties of the surface electromagnetic field, such as its statistics (probability density function, average and fluctuations), and their dependence on the excitation spectrum (in the visible and near infrared). Our study is relevant to the use of such self-affine fractals as surface-enhanced Raman scattering substrates, where large local and average field enhancements are desired.Comment: REVTeX 3.1, 11 pages with 10 EPS figures (epsf macro

Partidos políticos: vida interna y desarrollo electoral en el Estado de México (1993-2006)

El propósito principal del presente artículo es analizar la adaptación de los partidos políticos en el contexto mexiquense entre los años 1993-2006. Los partidos políticos como organizaciones responden a intereses complejos, mismos que se expresan también de forma polifacética. En los últimos años estos organismos políticos se han adaptado al mercado, abandonado la ideología e introducido a la competencia electoral, lo cual lleva a sus líderes a tomar decisiones en un contexto de elección racional. La tipología a la que responden ahora es a la de partido profesional, catch-all o cartel, dejando atrás la respuesta a los cleavages sociales o a la ideología que otrora identificaba a los partidos.El propósito principal del presente artículo es analizar la adaptación de los partidos políticos en el contexto mexiquense entre los años 1993-2006. Los partidos políticos como organizaciones responden a intereses complejos, mismos que se expresan también de forma polifacética. En los últimos años estos organismos políticos se han adaptado al mercado, abandonado la ideología e introducido a la competencia electoral, lo cual lleva a sus líderes a tomar decisiones en un contexto de elección racional. La tipología a la que responden ahora es a la de partido profesional, catch-all o cartel, dejando atrás la respuesta a los cleavages sociales o a la ideología que otrora identificaba a los partidos

Uso metodológico de las tablas de contingencia en la ciencia política

Este trabajo presenta la importancia que tienen las tablas de contingencia como herramienta metodológica en la construcción de la Ciencia Política. Se expone que a partir de una tabla de contingencia se puede explorar relaciones que apoyen la explicación de una relación entre variables de estudio o de investigación. Se ofrecen algunos ejemplos que ilustran el uso de la tabla para arrancar de ahí una explicación que se apoye en la teoría. Asimismo se hace un repaso rápido a los coeficientes de asociación que se basan en la tabla de contingencia.Este trabajo presenta la importancia que tienen las tablas de contingencia como herramienta metodológica en la construcción de la Ciencia Política. Se expone que a partir de una tabla de contingencia se puede explorar relaciones que apoyen la explicación de una relación entre variables de estudio o de investigación. Se ofrecen algunos ejemplos que ilustran el uso de la tabla para arrancar de ahí una explicación que se apoye en la teoría. Asimismo se hace un repaso rápido a los coeficientes de asociación que se basan en la tabla de contingencia

Note on the space group selection rule for closed strings on orbifolds

It is well-known that the space group selection rule constrains the interactions of closed strings on orbifolds. For some examples, this rule has been described by an effective Abelian symmetry that combines with a permutation symmetry to a non-Abelian flavor symmetry like $D_4$ or $\Delta(54)$. However, the general case of the effective Abelian symmetries was not yet fully understood. In this work, we formalize the computation of the Abelian symmetry that results from the space group selection rule by imposing two conditions only: (i) well-defined discrete charges and (ii) their conservation. The resulting symmetry, which we call the space group flavor symmetry $D_S$, is uniquely specified by the Abelianization of the space group. For all Abelian orbifolds with $N=1$ supersymmetry we compute $D_S$ and identify new cases, for example, where $D_S$ contains a $Z_2$ dark matter-parity with charges 0 and 1 for massless and massive strings, respectively.Comment: 28 pages, 1 tabl