Participatory Action Research experiences in Andalusia. Linking science and day-to-day life. Role of public policies

Andalucia holds 54% of the certified organic Spanish area, and 30% of the total amount of operators (MAGRAMA, 2013). From 2004 up to 2007, the regional government implemented, through the Organic Action Plans (Plan Andaluz de Agricultura Ecológica) specific public policies for research and knowledge transfer based on Participatory Action Research methodology (CAP, 2007). This article aims to focus on this methodology potential as a means to enhance stakeholders and civil society participation and engagement in the knowledge transfer activities

Uprolides N, O and P from the Panamanian Octocoral Eunicea succinea.

Three new diterpenes, uprolide N (1), uprolide O (2), uprolide P (3) and a known one, dolabellane (4), were isolated from the CH₂Cl₂-MeOH extract of the gorgonian octocoral Eunicea succinea, collected from Bocas del Toro, on the Caribbean coast of Panama. Their structures were determined using spectroscopic analyses, including 1D and 2D NMR and high-resolution mass spectrometry (HRMS) together with molecular modeling studies. Compounds 1-3 displayed anti-inflammatory properties by inhibiting production of Tumor Necrosis Factor (TNF) and Interleukin (IL)-6 induced by lipopolysaccharide (LPS) in murine macrophages

Instability of wormholes supported by a ghost scalar field. II. Nonlinear evolution

We analyze the nonlinear evolution of spherically symmetric wormhole solutions coupled to a massless ghost scalar field using numerical methods. In a previous article we have shown that static wormholes with these properties are unstable with respect to linear perturbations. Here we show that depending on the initial perturbation the wormholes either expand or decay to a Schwarzschild black hole. We estimate the time scale of the expanding solutions and the ones collapsing to a black hole and show that they are consistent in the regime of small perturbations with those predicted from perturbation theory. In the collapsing case, we also present a systematic study of the final black hole horizon and discuss the possibility for a luminous signal to travel from one universe to the other and back before the black hole forms. In the expanding case, the wormholes seem to undergo an exponential expansion, at least during the run time of our simulations.Comment: 16 pages, 15 figures, minor modifications, to appear in Classical and Quantum Gravit

Gas sensor based on room temperature optical properties of Surface QDs

Self-organized InGaAs QDs are intensively studied for optoelectronic applications. Several approaches are in study to reach the emission wavelengths needed for these applications. The use of antimony (Sb) in either the capping layer or into the dots is one example. However, these studies are normally focused on buried QD (BQD) where there are still different controversial theories concerning the role of Sb. Ones suggest that Sb incorporates into the dot [1], while others support the hypothesis that the Sb occupies positions surrounding the dot [2] thus helping to keep their shape during the capping growth

The problem of drug trafficking in Honduras and its impact on the national security and defense of Central America

La investigación describe el efecto generado por el narcotráfico en Honduras como un problema para la seguridad y defensa nacional en Centroamérica en un periodo considerado entre 2015 al 2019. Se abordan las causas y consecuencias que lo promueven, la convergencia del problema y su incidencia; y se describen las limitaciones que enfrenta el Estado de Honduras para frenar esta problemática. Se retomó información académica de instituciones extranjeras referentes a toda Centroamérica, así como información expedida por autoridades gubernamentales de Honduras que, como se evidenció en el proceso de investigación, no han reparado en realizar investigaciones profundas y concretas sobre el impacto a la seguridad y defensa nacional. La metodología empleada es cualitativa debido a que contempla el análisis bibliográfico y emplea la correlación de categorías desde una perspectiva centroamericanaThe investigation describes the effect generated by drug trafficking in Honduras as a problem for national security and defense in Central America in a period considered from 2015 to 2019. Causes and consequences that promote it are addressed, the convergence of the problem and its incidence; and, the limitations faced by the State of Honduras to curb this problem are described. Academic information from foreign institutions referring to all of Central America was retaken, as well as information issued by Honduran government authorities that, as evidenced in the investigation process, have not paid attention to carrying out in-depth and concrete investigations on the impact on the national security and defense. The methodology used is qualitative because it contemplates the bibliographic analysis and uses the category correlation from a Central American perspectiv

Size, strain, and band offset engineering in GaAs(Sb)(N)-capped InAs quantum dots for 1.3 - 1.55 µm LEDs and LDs

The optical and structural properties of InAs/GaAs quantum dots (QD) are strongly modified through the use of a thin (~ 5 nm) GaAsSb(N) capping layer. In the case of GaAsSb-capped QDs, cross-sectional scanning tunnelling microscopy measurements show that the QD height can be controllably tuned through the Sb content up to ~ 14 % Sb. The increased QD height (together with the reduced strain) gives rise to a strong red shift and a large enhancement of the photoluminescence (PL) characteristics. This is due to improved carrier confinement and reduced sensitivity of the excitonic bandgap to QD size fluctuations within the ensemble. Moreover, the PL degradation with temperature is strongly reduced in the presence of Sb. Despite this, emission in the 1.5 !lm region with these structures is only achieved for high Sb contents and a type-II band alignment that degrades the PL. Adding small amounts of N to the GaAsSb capping layer allows to progressively reduce the QD-barrier conduction band offset. This different strategy to red shift the PL allows reaching 1.5 !lm with moderate Sb contents, keeping therefore a type-I alignment. Nevertheless, the PL emission is progressively degraded when the N content in the capping layer is increase

The influence of Ga composition of GaInAsN QDs on N incorporation.

Currently, dilute nitride III-N-As semiconductors, such as InGaAsN/GaAs quantum well material system, allow to develop very competitive lasers at long wavelength emission (1.3 µm). However, longer wavelengths, such as 1.55 µm, are very difficult to achieve without making worse the performance of the device. Alternatively, as it is well known, great efforts are being devoted to the study of dilute nitride III-N-As quantum dots (QDs) semiconductor [1]. Mainly, this is due to the attractive advantages that they show over other materials and structures: the strong reduction in the bandgap of the III-As semiconductor by adding even a few percent of nitrogen into them, and the interesting physical properties that the QDs offer to laser characteristics (e.g. low threshold current, etc

Near infrared high efficiency InAs/GaAsSb QDLEDs: band alignment and carrier recombination mechanisms

The development of high efficiency laser diodes (LD) and light emitting diodes (LED) covering the 1.0 to 1.55 μm region of the spectra using GaAs heteroepitaxy has been long pursued. Due to the lack of materials that can be grown lattice-macthed to GaAs with bandgaps in the 1.0 to 1.55 μm region, quantum wells (QW) or quantum dots (QD) need be used. The most successful approach with QWs has been to use InGaAs, but one needs to add another element, such as N, to be able to reach 1.3/1.5μm. Even though LDs have been successfully demonstrated with the QW approach, using N leads to problems with compositional homogeneity across the wafer, and limited efficiency due to strong non-radiative recombination. The alternative approach of using InAs QDs is an attractive option, but once again, to reach the longest wavelengths one needs very large QDs and control over the size distribution and band alignment. In this work we demonstrate InAs/GaAsSb QDLEDs with high efficiencies, emitting from 1.1 to 1.52 μm, and we analyze the band alignment and carrier loss mechanisms that result from the presence of Sb in the capping layer

Optimization of InGaAsN(Sb)/GaAs quantum dots for optical emission at 1.55 µm with low optical degradation

Low optical degradation in GaInAsN(Sb)/GaAs quantum dots (QDs) p–i–n structures emitting up to 1.55 μm is presented in this paper. We obtain emission at different energies by means of varying N content from 1 to 4%. The samples show a low photoluminescence (PL) intensity degradation of only 1 order of magnitude when they are compared with pure InGaAs QD structures, even for an emission wavelength as large as 1.55 μm. The optimization studies of these structures for emission at 1.55 μm are reported in this work. High surface density and homogeneity in the QD layers are achieved for 50% In content by rapid decrease in the growth temperature after the formation of the nanostructures. Besides, the effect of N and Sb incorporation in the redshift and PL intensity of the samples is studied by post-growth rapid thermal annealing treatments. As a general conclusion, we observe that the addition of Sb to QD with low N mole fraction is more efficient to reach 1.55 μm and high PL intensity than using high N incorporation in the QD. Also, the growth temperature is determined to be an important parameter to obtain good emission characteristics. Finally, we report room temperature PL emission of InGaAsN(Sb)/GaAs at 1.4 μm

Forest decline evaluation in Antarctic Beech Forests (Nothofagus antarctica) in Chilean Patagonia by using Landsat TM and ETM+

Antarctic beech forests (Nothofagus antarctica (G. Forst.) Oerst.) have shown a major decline process in the past few decades, together with an important lack of specific studies on this type of forest. The aim of this work was to create cartography of the surface of Antarctic beech forests and to evaluate decline levels in the XII Region of Chile. A study area was selected between the cities of Puerto Natales and Punta Arenas (latitudes 50º40’S to 52º40’S) and from latitudes 60º15’W to 74º15’W, where a random stratified sampling was carried out in 68 plots, in which the forest cover, mortality, height, normal diameter and regeneration were measured. Using two Landsat images (1986-2002), the study area was classified in terms of vegetation cover and forest mortality, by means of the normalized vegetation index (NDVI). The forests in this study area are characterized by their high density, and, in over half their surface (27,873 ha) they exhibit some degree of mortality, with 7,585 ha of forest completely affected. The distribution of the mortality in Antarctic beech on the period 1986-2002 showed an improvement on forests condition, which seems to corroborate the hypothesis of a change on perturbation pattern as the major reason for this forest decline process.Los bosques de ñirre (Nothofagus antarctica) han experimentado en las últimas décadas un importante proceso de mortalidad. El objetivo de este trabajo fue elaborar una cartografía de las masas de ñirre en función de la fracción de cabida cubierta del dosel arbóreo y el nivel de mortalidad en la XII Región de Chile. En una zona entre las ciudades de Puerto Natales y Punta Arenas (50º40’ - 52º40’ S y 69º15’ - 74º15’ O) se realizó un muestreo estratificado en 68 parcelas, donde se midieron: fracción de cabida cubierta, mortandad del arbolado, altura, diámetro normal (DAP) y regeneración. Mediante clasificación de dos imágenes Landsat TM (1986) y ETM+ (2002) se estudiaron el estado de las masas de ñirre y la evolución de la mortandad en un periodo de 16 años, utilizando el índice de vegetación normalizado (NDVI). En el año 2002 los bosques de ñirre se caracterizaban por una elevada fracción de cabida cubierta, tallas y diámetros medios, y una escasa regeneración. Más de la mitad de la superficie de estudio (casi 28.000 ha) presentaba algún grado de mortandad del arbolado, con 7.585 ha de bosques totalmente muertos. El patrón de mortandad, por comparación con el estado del arbolado en 1986, indicó una tendencia a mejorar el estado del arbolado en los últimos 16 años, lo cual parece confirmar la hipótesis de que los procesos de mortandad en esta especie no están asociados a un cambio en el patrón climático en la zona, sino más bien a la modificación del régimen de perturbaciones