Assessing biophysical limits to the economic development of remote islands : the case of Isabela in the Galapagos Archipelago

Altres ajuts: National Scholarship Program of the National Secretary of Higher Education, Science, Technology and Innovation (SENESCYT) of EcuadorIn assessing the sustainability of island tourism, the resident population size and yearly number of visitors are key factors. However, to assess the overall resource requirement and environmental impact on local ecosystems, we must also consider the metabolic rates and density of energy and material flows related to the activity of residents and tourists. We present here an innovative approach, the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM), with the aim of providing an integrated characterization of the metabolic pattern of island tourism. We use the tourism model implemented in the island Isabela in the Galapagos Archipelago as a case study. We show how MuSIASEM allows us to assess the overall requirement of resources and environmental services and the environmental impact for a given model of tourism. MuSIASEM employs a multi-level matrix to represent these characteristics in an integrated way, thus emphasizing the nexus between different biophysical factors

Morphological and compositional characterization of gold contained in ferricretes of a weathered profile (Minvoul greenstone belt, Gabon)

This study presents the quantification and morphological characterization of particles and nuggets of almost pure gold found in the iron duricrust of a weathering profile of the Archean greenstone belt of Minvoul (Republic of Gabon). The weathered profile on the area (Figure 1) was defined through pits and trenches and consists, from bottom to top, on saprolite, mottled clay zone, iron duricrust, pisolitic gravels and yellow latosol. The iron duricrust constitutes a hard continuous layer, which is concretionary and pisolitic and consists of cemented nodules of goethite, hematite and other iron oxides and hydroxides. Samples from this horizon contain abundant particles of gold. The study of morphology and microchemical composition of gold grains has been widely used as a tool for the understanding of the dissolution, dispersion and gold concentration processes in supergene environments, and for determining the primary or secondary origin of gold grains across the lateritic horizons (Webster and Mann, 1984; Butt and Hough, 2006). Moreover, the results obtained represent a contribution for the knowledge of the gold-potential of the Ntem complex greenstone belts where mineralization on bedrock remains unknown

Polycrystallization effects on the nanoscale electrical properties of high-k dielectrics

In this study, atomic force microscopy-related techniques have been used to investigate, at the nanoscale, how the polycrystallization of an Al₂O₃-based gate stack, after a thermal annealing process, affects the variability of its electrical properties. The impact of an electrical stress on the electrical conduction and the charge trapping of amorphous and polycrystalline Al₂O₃ layers have been also analyzed

Modelado de riesgos para el sistema vaca-cría del estado de Chihuahua utilizando indicadores socioeconómicos y ambientales

Los sistemas de producción de bovinos-carne se encuentran expuestos a una vulnerabilidad inminente por el sobre pastoreo, cambios en el uso de suelo y un manejo inadecuado del hato. El objetivo de esta investigación fue elaborar un modelo matemático integrado por indicadores ambientales y socioeconómicos de tres ecorregiones, que identifiquen factores y patrones de vulnerabilidad en la densidad ganadera (Dg) del sistema vaca-cría del estado de Chihuahua. La estimación mostró que el aumento de la Dg en una unidad animal en los predios ejidales eleva los costos de producción 0.0358 unidades porcentuales, al demandar un mayor consumo de materia vegetal e insumos. La diferencia en las unidades animal entre tipos de tenencia predial, al considerar un programa de capacitación técnico pecuario, disminuye entre las zonas, y mostró que la vulnerabilidad en los predios ejidales es inferior ante un evento de sequía. Se pretende que este trabajo genere información útil para analizar los posibles riesgos que afecten la rentabilidad económica, social y ambiental en las ecorregiones del estado de Chihuahua. ASTRACT Overgrazing, changes in land use and inadequate management that supports it exposes the cattle-beef systems to an imminent vulnerability. The aim of this research was to develop an integrated model of environmental and socioeconomic indicators of three ecoregions, identifying vulnerability factors and patterns of cow-calf system in the grasslands of the State of Chihuahua that affects the livestock density (LD). The estimation showed that the increasing of LD in the Ejido lands raises the production costs 0.0358 units, by demanding a higher materials and forage intake. The difference in animal units between farm types (considering a technical program of training livestock) decreases depending the areas, and shows that the Ejidos lands are less vulnerable in time of drought. This report will generate useful information for analyzing the potential economic, social and environmental risks in the ecoregions of the state of Chihuahua

El Distrito Minero más importante de Europa, la Faja Pirítica (SO Península Ibérica): nueva colección de muestras y nuevas herramientas para la docencia práctica en Recursos Minerales

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasFALSEsubmitte

MAYORISTAPE. APP

El proyecto se enfoca en cubrir la necesidad de dos segmentos de clientes que son interdependientes entre si según el modelo de negocio. El primero está conformado por los clientes mayoristas y el segundo por clientes del segmento de bodegas (canal tradicional). En este proyecto el cual se ha bautizado como MayoristaPe. se busca cubrir las necesidades de ambos segmentos a través del uso de la aplicación desde donde las bodegas podrán realizar y gestionar sus compras para abastecer sus comercios, y los mayoristas cuenten con la posibilidad incrementar sus ventas, publicar ofertas y generar valor para sus clientes, logrando crear eficiencia en tiempos y costos en sus comercios. Inicialmente MayoristaPe. se enfocará en la Ciudad de Lima y Callao, donde se ubican la mayor concentración de mercados mayoristas y bodegas, a futuro buscará ampliar a otros puntos estratégicos. Las fuentes de ingreso se generarán a través de un cobro de membresía mensual y/o a través de un porcentaje sobre las ventas, lo que dependerá del segmento en donde se encuentre cada uno.The project focuses on meeting the need of two customer segments that are interdependent with each other according to the business model. The first is made up of wholesale clients and the second by clients of the winery segment (traditional channel). In this project which has been baptized as MayoristaPe. It seeks to meet the needs of both segments through the use of the application from where wineries can make and manage their purchases to supply their stores, and wholesalers have the possibility to increase their sales, publish offers and generate value for their customers, managing to create time and cost efficiency in their businesses. Initially MayoristaPe. will focus on the City of Lima and Callao, where the largest concentration of wholesale markets and warehouses are located, in the future it will seek to expand to other strategic points. The sources of income will be generated through a monthly membership charge and / or through a percentage of sales, which will depend on the segment where each one is located.Trabajo de investigació

Gate current analysis of AlGaN/GaN on silicon heterojunction transistors at the nanoscale

The gate leakage current of AlGaN/GaN (on silicon)high electron mobility transistor(HEMT) is investigated at the micro and nanoscale. The gate current dependence (25-310 °C) on the temperature is used to identify the potential conduction mechanisms, as trap assisted tunneling or field emission. The conductive atomic force microscopy investigation of the HEMT surface has revealed some correlation between the topography and the leakage current, which is analyzed in detail. The effect of introducing a thin dielectric in the gate is also discussed in the micro and the nanoscale

Soil and Freshwater Bioassays to Assess Ecotoxicological Impact on Soils Affected by Mining Activities in the Iberian Pyrite Belt

This study aims to use geochemical, mineralogical, ecotoxicological and biological indicators for a comprehensive assessment of the ecological risks related to the mobility, ecotoxicity and bioavailability of potentially harmful elements in the Lousal mining district. Particularly, toxicity was evaluated using four assays: algae, cytotoxicity assays with HaCaT cell line (dermal), earthworms and Daphnia magna. The geochemical and mineralogical characterization of the studied area shows that the mine wastes underwent intense weathering processes, producing important contamination of the adjacent soils, which also led to the release and mobilization of PHEs into nearby water courses. Total PTE results indicate that the soils affected by mining activities were highly contaminated with As and Cu, while Zn and Pb content ranged from low to very high, depending on the analyzed samples. Cadmium levels were found to be very low in most of the soil samples. The test using Daphnia magna was the most sensitive bioassay, while the Eisenia foetida test was the least sensitive. Except for the LOS07 soil sample, the rest of the soils were classified as “High acute toxicity” and “Very high acute toxicity” for aquatic systems. The results in HACaT cells showed results similar to the ecotoxicological bioassays. The application of biotests, together with geochemical and mineralogical characterization, is a very useful tool to establish the degree of contamination and the environmental risk of potentially harmful elements