Light trapping within the grooves of 1D diffraction gratings under monochromatic and sunlight illumination

The Rayleigh-Modal method is used to calculate the electromagnetic field within the grooves of a perfectly conducting, rectangular-shaped 1D diffraction grating. An \emph{enhancement coefficient} ($\eta$) is introduced in order to quantify such an energy concentration. Accordingly, $\eta >$1 means that the amount of electromagnetic energy present within the grooves is larger than that one will have, over the same volume, if the diffraction grating is replaced by a perfectly reflecting mirror. The results in this paper show that $\eta$ can be as large as several decades at certain, often narrow, ranges of wavelengths. However, it reduces to approximately 20% under sunlight illumination. In this latter case, such values are achieved when the \textit{optical spacing} between the grooves $dn$ is greater than 500 nm, where $d$ is the groove spacing and $n$ is the refractive index of the substance within the grooves. For $dn$ smaller than 500 nm the enhancement coefficient turns negligibly small.Comment: This paper contains 11 pages and 4 figures, and will be published elsewher

Dynamic regimes of hydrodynamically coupled self-propelling particles

We analyze the collective dynamics of self-propelling particles (spps) which move at small Reynolds numbers including the hydrodynamic coupling to the suspending solvent through numerical simulations. The velocity distribution functions show marked deviations from Gaussian behavior at short times, and the mean-square displacement at long times shows a transition from diffusive to ballistic motion for appropriate driving mechanism at low concentrations. We discuss the structures the spps form at long times and how they correlate to their dynamic behavior.Comment: 7 pages, 4 figure

Uns i altres en la cartografia de la narrativa breu medieval

Revision of a representative sample of short narrative in prose in order to detect, in the medieval cultural system, evidence of difference or diversity; likewise, the ways to portray the other one and to position literarily in front of it are revised. And all that without considering if this other one was a Christian neighbour or a stranger, either in a cultural or spiritual way

The Spanish economic Miracle: a disaggregated approach to productivity growth, 1958-1975

En este trabajo se analizan las fuentes del crecimiento español durante 1958-1975 desde una perspectiva sectorial, siguiendo una metodología similar a la desarrollada por Jorgenson, Gollop y Fraumeni (1987). Para ello se mide la contribución de los inputs intermedios, el capital, el trabajo y la productividad total de los factores al crecimiento del output total para 25 ramas productivas. Los resultados atribuyen más de la mitad del crecimiento del output al crecimiento de la Productividad Total de los Factores. Este crecimiento de la productividad fue de alcance general aunque no estuvo uniformemente repartido y se apoyó en una potente contribución de algunas industrias manufactureras compartida con avances significativos en los transportes y en las comunicaciones.This paper exploits sectorial growth accounting methodology in a similar way to Jorgenson, Gollop and Fraumeni (1987) in order to provide additional insight into the sources of Spanish economic growth. We measure the contribution of intermediate inputs, capital, labour and total factor productivity to the increase in total output for 25 productive branches. We also analyse sectorial contributions to overall productivity growth and discuss the role of pioneering sectors in the whole transformation. The findings presented attribute more than fifty per cent of output growth to improvement in TFP. This productivity growth was unevenly distributed and was fuelled by some potent manufacturing industries together with advances in transportation and communications.The Spanish Ministry of Education (Grant SEC 2002-01595) supports this research

Disaggregated productivity growth and technological progress in the interpretation of Spanish economic growth, 1958-1975

Spanish economic records in terms of GDP growth and convergence to European levels in the sixties, provide an excellent opportunity to look at a central question underlying in the interpretation of any process of economic growth. The relevance of industrial specific technological progress is confronted to a general and multifaceted productivity change coming from a variety of sectors and causes. This paper exploits sectoral growth accounting methodology in two different ways in order to answer this crucial question revisited recently by historiography with reference to British Industrial Revolution and to Information and Telecommunications Technologies. First, we calculate TFP growth following the Kendrick approach (1961) and using four input-output tables corresponding to 1958, 1962, 1970 and 1975 disaggregated at 25 productive branches. And Second, we examine the impact of electricity and electric machinery and equipment as a General Purpose Technology (GPT) in Spanish economic growt

La ciudad en la isla: Ciutat de Mallorques

En muchas ocasiones isla y ciudad han representado literariamente el significado del círculo como contenedor del elemento mágico o como microcosmos emblemático del ser humano; pero donde cabría esperar una correspondencia de orden concéntrico plausible entre la isla y, en su centro, la ciudad, por el contrario parece desvelarse comúnmente un conflicto de competencias. La literaturización que de dicho motivo documenta la literatura catalana en las Islas Baleares al oponer Mallorca-isla y Ciutat-urbe, permite recorrer la configuración de un sistema espacial en el que fuerzas y protagonismos opuestos marcan el rumbo de sus usuarios en un prioritario triunfo final del geologismo insular sobre el orgullo urbanita