Camp d'Aprenentatge de la Vall de Boí. 'Campo de Aprendizaje del Valle de Boí'.

Los campos de aprendizaje son servicios educativos que ofrecen a los chicos y chicas la posibilidad de estar en un entorno singular en Cataluña. Se facilita el contacto con ecosistemas poco alterados por el ser humano. Posibilitan que el material de origen natural que se utiliza en las actividades sea recogido por los alumnos.

Tecnoloxías da información e a comunicación (TIC) : bo uso, mal uso e abuso : riscos e beneficios para a saúde biopsicosocial. 'Tecnologías de la información y comunicación (TIC) : buen uso, mal uso y abuso : riesgos y beneficios para la salud biopsicosocial'.

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Elaboration and optimization of (Y,Er)Al(3)(BO(3))(4) glassy planar waveguides through the sol-gel process

In this work, a sol-gel route was used to prepare Y(0.9)Er(0.1)Al(3)(BO(3))(4) glassy thin films by spin-coating technique looking for the preparation and optimization of planar waveguides for integrated optics. The films were deposited on silica and silicon substrates using stable sols synthesized by the sol-gel process. Deposits with thicknesses ranging between 520 and 720 nm were prepared by a multi-layer process involving heat treatments at different temperatures from glass transition to the film crystallization and using heating rates of 2 degrees C/min. The structural characterization of the layers was performed by using grazing incidence X-ray diffraction and Raman spectroscopy as a function of the heat treatment. Microstructural evolution in terms of annealing temperatures was followed by high resolution scanning electron microscopy and atomic force microscopy. Optical transmission spectra were used to determine the refractive index and the film thicknesses through the envelope method. The optical and guiding properties of the films were studied by m-line spectroscopy. The best films were monomode with 620 nm thickness and a refractive index around 1.664 at 980 nm wavelength. They showed good waveguiding properties with high light-coupling efficiency and low propagation loss at 632.8 and 1550 nm of about 0.88 dB/cm. (C) 2009 Elsevier B.V. All rights reserved.

Er:YAl(3)(BO(3))(4) glassy thin films from polymeric precursor and sol-gel methods: Waveguides for integrated optics

This paper presents the characterization of single-mode waveguides for 980 and 1550 nm wavelengths. High quality planar waveguide structure was fabricated from Y(1-x)Er(x)Al(3)(BO(3))(4) multilayer thin films with x = 0.02, 0.05, 0.1, 0.3, and 0.5, prepared through the polymeric precursor and sol-gel methods using spin-coating. The propagation losses of the planar waveguides varying from 0.63 to 0.88 dB/cm were measured at 632.8 and 1550 nm. The photoluminescence spectra and radiative lifetimes of the Er(3+) (4)I(13/2) energy level were measured in waveguiding geometry. For most samples the photoluminescence decay was single exponential with lifetimes in between 640 mu s and 200 mu s, depending on the erbium concentration and synthesis method. These results indicate that Er doped YAl(3)(BO(3))(4) compounds are promising for low loss waveguides. (C) 2009 Elsevier B.V. All fights reserved.

Thermal and structural investigation of Er:YAl(3)(BO(3))(4) nanocrystalline powders

Pure Er:YAB (Er:YAl(3)(BO(3))(4)) nanometer-sized crystalline powder was produced from low cost chemical route, the polymeric precursor method. The initial homogeneous solutions were heat treated from 200 to 700A degrees C under oxygen atmosphere and the unique crystalline phase was synthesized at around 1150A degrees C. The thermal treatments and the initial stoichiometry play a very important role on the Er:YAB preparation. The thermal events of amorphous precursor resins and the crystallization process up to phase formation were investigated.

Synthesis optimization, structural evolution and optical properties of Y(0.9)Er(0.1)Al(3)(BO(3))(4) nanopowders obtained by soft chemistry methods

This paper describes the structural evolution of Y(0.9)Er(0.1)Al(3)(BO(3))(4) nanopowders using two soft chemistry routes, the sol-gel and the polymeric precursor methods. Differential scanning calorimetry, differential thermal analyses, thermogravimetric analyses, X-ray diffraction, Fourier-transform infrared, and Raman spectroscopy techniques have been used to study the chemical reactions between 700 and 1200 degrees C temperature range. From both methods the Y(0.9)Er(0.1)Al(3)(BO(3))(4) (Er:YAB) solid solution was obtained almost pure when the powdered samples were heat treated at 1150 degrees C. Based on the results, a schematic phase formation diagram of Er:YAB crystalline solid solution was proposed for powders from each method. The Er:YAB solid solution could be optimized by adding a small amount of boron oxide in excess to the Er:YAB nominal composition. The nanoparticles are obtained around 210 nm. Photoluminescence emission spectrum of the Er:YAB nanocrystalline powders was measured on the infrared region and the Stark components of the (4)I(13/2) and (4)I(15/2) levels were determined. Finally, for the first time the Raman spectrum of Y(0.9)Er(0.1)Al(3)(BO(3))(4) crystalline phase is also presented. (C) 2008 Elsevier Masson SAS. All rights reserved.

Vilhelm Ekelund och det litterära fältet 1897-1949

Vilhelm Ekelunds och det litterära fältet 1897-1949 [Vilhelm Ekelund and the literary field 1897-1949] The theoretical background of this study is Pierre Bourdieu’s sociological approach to literature. I use his theory concerning the importance of cultural (and other forms of symbolic) capital for the individual artist – and his description of the literary field as a place characterized by continuous conflict between different categories of participants. In the article, I argue that as a young poet, Ekelund held a position in the field that was with the intellectual group as opposed to the group of commercial authors – and among the young avant-garde as opposed to among the consecrated and well-established writers. However, this position changed somewhat during the years Ekelund spent in exile (1908-1921), and it continued to change after his return to Sweden. His reputation as a thoroughly intellectual writer was accentuated and, as time passed, he himself became a consecrated artist with certain privileges – e.g. grants and awards – to defend.

Vilhelm Ekelund och den fransk-italienska kultursfären : Några nedslag i de tidiga prosaverken - från Antikt ideal (1909) till Attiskt i fågelperspektiv (1919)

Vilhelm Ekelund och den fransk-italienska kultursfären: Några nedslag i de tidiga prosaverken – från Antikt ideal (1909) till Attiskt i fågelperspektiv (1919). (Vilhelm Ekelund and the French and Italian cultural heritage: A study of his early prose – from Antikt ideal (1909) to Attiskt i fågelperspektiv (1919)). The Swedish poet, essayist and aphorist Vilhelm Ekelund was not only influenced by German literature and philosophy, he also wrote extensive literary criticism on the subject of Romance language authors. This article discusses Ekelund’s relationship to some of the most influential French and Italian writers – as it can be seen in his work during the period 1909-1919. This relationship was ambiguous: he paid homage to French authors such as Montaigne, Montesquieu, Stendhal and Comte – as well as to the Italian poet and philosopher Leopardi – but he also severely criticized such distinguished writers as Baudelaire, Rousseau and Maupassant. One conclusion of this article is that the authors praised by Ekelund all venerate the Greek and Roman cultural heritage, whereas the despised novelists and poets were, in his opinion, either too “modern” or too “feminine” – both highly pejorative adjectives in the author’s terminology. It is also noted that Ekelund’s most ferocious attacks date from the first part of the decade, before he entered a more harmonic period with the works Metron (1918) and Attiskt i fågelperspektiv (1919).

Descentralización fiscal: el caso de la municipalidad de Concepción, región del Bío-Bío, Chile

Incluye Bibliografía

Chile: elaboración de un modelo de equilibrio general computable y su aplicación a la región del Bío Bío

Incluye Bibliografía

Chile: building a computable general equilibrium model with an application to the Bío Bío region

Includes bibliography

Efectos contextuales y fecundidad marital: un modelo de niveles múltiples de la paridez en la región del Bío-Bío, Chile

Incluye Bibliografía

Efectos de las clínicas de planificación familiar en el uso de anticonceptivos en las zonas rurales de Bio-Bío, Chile: un análisis multiniveles

Incluye Bibliografía