Coupled mantle dripping and lateral dragging controlling the lithosphere structure of the NW-Moroccan margin and the Atlas Mountains: A numerical experiment

Recent studies integrating gravity, geoid, surface heat flow, elevation and seismic data indicate a prominent lithospheric mantle thickening beneath the NW-Moroccan margin (LAB >200 km-depth) followed by thinning beneath the Atlas Domain (LAB about 80 km-depth). Such unusual configuration has been explained by the combination of mantle underthrusting due to oblique Africa-Eurasia convergence together with viscous dripping fed by asymmetric lateral mantle dragging, requiring a strong crust-mantle decoupling. In the present work we examine the physical conditions under which the proposed asymmetric mantle drip and drag mechanism can reproduce this lithospheric configuration. We also analyse the influence of varying the kinematic boundary conditions as well as the mantle viscosity and the initial lithosphere geometry. Results indicate that the proposed drip-drag mechanism is dynamically feasible and only requires a lateral variation of the lithospheric strength. The further evolution of the gravitational instability can become either in convective removal of the lithospheric mantle, mantle delamination, or subduction initiation. The model reproduces the main trends of the present-day lithospheric geometry across the NW-Moroccan margin and the Atlas Mountains, the characteristic time of the observed vertical movements, the amplitude and rates of uplift in the Atlas Mountains and offers an explanation to the Miocene to Pliocene volcanism. An abnormal constant tectonic subsidence rate in the margin is predicted. (C) 2013 Elsevier B.V. All rights reserved.Peer ReviewedPostprint (author's final draft

Registro isotópico de δ13 C y δ15 N de 12.000 años de antigüedad de Amboromena (Macizo de Andringitra, Madagascar)

[Abstract] Profiles of percent carbon, nitrogen and phosphorus, carbon/nitrogen (C/N) ratios, percent organic matter and carbonates, and stable carbon (δ13C) and nitrogen (δ15N) from a 176 cm core were used to reconstruct environments of deposition in the Amboromena basin (Madagascar)during last 12,000 yr BP. From these profiles three distinctively different stages in the basin evolution were apparent, which could have been result from the response to changes in the climatic conditions. Similar changes has been observed in other works about climate evolution in Madagascar and the African Tropics during the Late Quaternary

Diseño de un modelo de negocio para el incentivo del sector de transporte de mercancías terrestre en España

La necesidad de transportar mercancías de un punto a otro del mundo viene ligada a la humanidad desde tiempos immemoriables. Al ser una necesidad implícita para el intercambio de productos comerciales, el ser humano ha dedicado muchos años de su historia a buscar soluciones para facilitarse la tarea del transporte con inventos como los jarrones o botijos, la rueda, la máquina de vapor o cualquier vehículo que se le ocurra. En los tiempos actuales de hiperglobalización y capitalismo, el transporte de mercancías sigue siendo uno de los sectores más esenciales de la economía ya que es uno de los principales motores para la industria y el sector servicios. En España, un 95% del transporte de mercancías se hace por carretera; dejando el otro 5% para los transportes ferroviario, aéreo y marítimo. Según datos del Ministerio de Transportes, Movilidad y Agenda Urbana, en 2020 había en España un total de 380.392 vehículos repartidos en 105.192 empresas trabajando en el transporte de mercancías por carretera. Está claro que el transporte por carretera es una de las claves de la red del comercio español, pero, sin embargo, hay problemas encima de la mesa que no se planteaban hace algunas décadas. El marco post-pandemia, el cambio climático, el auge de posibles alternativas, el encarecimiento del combustible y la precariedad laboral son algunos de los problemas que hacen que el sector del transporte de mercancías en España sea poco atractivo para el trabajador y, por lo tanto, para los jóvenes. El problema principal es que la edad media de los conductores profesionales en Europa (ya no sólo en España) aumenta un año por cada año que pasa. Esto es así debido a que los jóvenes no tienen interés por acceder al negocio debido a la situación actual. Esta edad media, que ronda los 52 años, supondrá un marco de total incertidumbre cuando dentro de unos 10 años haya más trabajadores jubilados que nuevos entrando al sector. Este proyecto pretende analizar el sector del transporte por carretera en España para hallar sus fortalezas y debilidades. Desde ahí, se pretende crear un modelo de negocio atractivo basado en la mejora de las condiciones del trabajador para fomentar el interés de la población activa joven en el sector. De esta forma, se lograría reducir la tendencia negativa etaria del sector y sentaría unas bases para la consolidación futura del mismo en un marco lleno de cambios e incertidumbre

Indoor air quality in hospitality venues after the implementation of the Portuguese tobacco control law

Um estudo efectuado na cidade de Braga, em Fevereiro de 2008 (pouco tempo depois da entrada em vigor da lei n.º 37/2007 de 14 de Agosto de controlo do tabagismo), no sector da restauração e similares, revelou que há proprietários desses estabelecimentos que permitem que se fume no interior. Este facto levantou o problema de saber qual a concentração de nicotina (indicadora da poluição por fumo do tabaco) presente no ar nesses locais. Participantes e método: A qualidade do ar foi avaliada em Março de 2009, em 6 locais de restauração e similares, da cidade de Braga: 2 restaurantes com menos de 100 m 2 que permitem que se fume no interior; 2 cafés com menos de 100 m 2 (um café que permite que se fume no interior e outro que proíbe o consumo); um bar nocturno com menos de 100 m 2 para fumadores e uma discoteca com uma área para fumadores e outra para não fumadores, separadas por uma cortina de ar. A medição da fase de vapor de nicotina no ar foi feita por monitorização activa, através da utilização de monitores, segundo o método aplicado por Hammond 1. As partículas (PM 2,5) foram medidas com um medidor Side Pack. Resultados: A concentração média de nicotina presente no interior dos restaurantes e no café onde é permitido fumar foi de 6,29 mg/m 3, enquanto que no interior do café onde é proibido fumar foi de 1,1 μg/m 3. A concentração de nicotina no "bar" apresenta um valor bastante elevado (9,42 μg/m 3). Na discoteca, a concentração de nicotina é a mais elevada registada em espaços fechados (19,1 μg/m 3 na área em que é proibido fumar e 10,2 μg/m 3 na área para fumadores). Conclusões: Os resultados sugerem que em locais da hotelaria (restaurantes e similares), onde é permitido fumar, há uma elevada contaminação do ar por Fumo Ambiental do Tabaco, à qual estão particularmente expostos os trabalhadores. Mais estudos são necessários para clarificar a situação do consumo de tabaco no sector da restauração.(undefined

Analysis of the effect of clock drifts on frequency regulation and power sharing in inverter-based islanded microgrids

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Local hardware clocks in physically distributed computation devices hardly ever agree because clocks drift apart and the drift can be different for each device. This paper analyses the effect that local clock drifts have in the parallel operation of voltage source inverters (VSIs) in islanded microgrids (MG). The state-of-the-art control policies for frequency regulation and active power sharing in VSIs-based MGs are reviewed and selected prototype policies are then re-formulated in terms of clock drifts. Next, steady-state properties for these policies are analyzed. For each of the policies, analytical expressions are developed to provide an exact quantification of the impact that drifts have on frequency and active power equilibrium points. In addition, a closed-loop model that accommodates all the policies is derived, and the stability of the equilibrium points is characterized in terms of the clock drifts. Finally, the implementation of the analyzed policies in a laboratory MG provides experimental results that confirm the theoretical analysis.Peer ReviewedPostprint (author's final draft

Short-term response of chlorophyll a concentration due to intense wind and freshwater peak episodes in estuaries: The case of fangar Bay (Ebro Delta)

Estuaries and coastal bays are areas of large spatio-temporal variability in physical and biological variables due to environmental factors such as local wind, light availability, freshwater inputs or tides. This study focuses on the effect of strong wind events and freshwater peaks on short-term chlorophyll a (Chl a) concentration distribution in the small-scale and microtidal, Fangar Bay (Ebro Delta, northwestern Mediterranean). The hydrodynamics of this bay are primarily driven by local wind episodes modulated by stratification in the water column. Results based on field-campaign observations and Sentinel-2 images revealed that intense wind episodes from both NW (offshore) and NE-E (onshore) caused an increase in the concentration of surface Chl a. The mechanisms responsible were horizontal mixing and the bottom resuspension (also linked to the breakage of the stratification) that presumably resuspended Chl a containing biomass (i.e., micropyhtobentos) and/or incorporated nutrients into the water column. On the other hand, sea-breeze was not capable of breaking up the stratification, so the chlorophyll a concentration did not change significantly during these episodes. It was concluded that the mixing produced by the strong winds favoured an accumulation of Chl a concentration, while the stratification that causes a positive estuarine circulation reduced this accumulation. However, the spatial-temporal variability of the Chl a concentration in small-scale estuaries and coastal bays is quite complex due to the many factors involved and deserve further intensive field campaigns and additional numerical modelling efforts.Postprint (published version

Growth and characterization of CoO ultra thin films

In this report we present the growth process of the cobalt oxide system using reactive electron beam deposition. In that technique, a target of metallic cobalt is evaporated and its atoms are in-flight oxidized in an oxygen rich reactive atmosphere before reaching the surface of the substrate. With a trial and error procedure the deposition parameters have been optimized to obtain the correct stoichiometry and crystalline phase. The evaporation conditions to achieve the correct cobalt oxide salt rock structure, when evaporating over amorphous silicon nitride, are: 525 K of substrate temperature, 2.5·10-4 mbar of oxygen partial pressure and 1 Å/s of evaporation rate. Once the parameters were optimized a set of ultra thin film ranging from samples of 1 nm of nominal thickness to 20nm thick and bulk samples were grown. With the aim to characterize the samples and study their microstructure and morphology, X-ray diffraction, transmission electron microscopy, electron diffraction, energy dispersive X-ray spectroscopy and quasi-adiabatic nanocalorimetry techniques are utilised. The final results show a size dependent effect of the antiferromagnetic transition. Its Néel temperature becomes depressed as the size of the grains forming the layer decreases.Un profund estudi s'ha realitzat sobre el sistema d'òxid de cobalt. El coneixement de la seva microestructura ens permetrà establir la relació amb les propietats magnètiques. Les mostres són preparades mitjançant un evaporador de feix d'electrons seguint un procediment d'assaig i error. Un blanc de cobalt metàl·lic és evaporat i els àtoms són oxidats durant el seu desplaçament dins d'una atmosfera reactiva d'oxigen. Diverses mostres son estudiades amb gruixos que van de 1 fins 20 nm i mostres massives. Les tècniques emprades són difracció de raigs X i microscòpia electrònica de transmissió per a la caracterització morfològica i estructural i nanocalorimetría per a la caracterització magnètica

Radiolocalitzador per a uhf

L’objectiu d’aquest treball és el d’implementar un sistema portàtil basat en el retard del senyal mitjançant la commutació d’antenes, que operi en la banda de freqüències d’UHF, concretament a 433 Mhz. En el disseny s’ha considerat crear un sistema portàtil, sense limitacions de mobilitat, amb unes dimensions el més reduïdes millor (amb components elèctrics i electrònics estàndard i el més lleuger possible)

Exposición al humo ambiental de tabaco en locales de hostelería de Barcelona: medición de partículas respirables

ResumenObjetivoMedir la concentración de partículas respirables de tamaño igual o menor que 2,5μm (PM2,5) como marcador del humo ambiental de tabaco (HAT) en locales de hostelería de Barcelona 2 años después de la entrada en vigor de la Ley 28/2005.MétodosSe trata de un estudio descriptivo transversal. La población de estudio fueron 40 locales de la ciudad de Barcelona seleccionados por muestreo de ruta aleatoria con representación de los distintos tipos de regulación existentes tras la aplicación de la Ley (permitido fumar, prohibido fumar y locales con zonas para fumadores y no fumadores). El trabajo de campo se realizó entre octubre y diciembre de 2007. El HAT se cuantificó determinando las PM2,5 con un monitor con fotómetro láser (Side Pack AM 510 Personal Aerosol Monitor). Se realizaron mediciones iniciales de 5 minutos en el exterior del local y de 30 minutos en el interior. Además, se recogieron variables de tipo observacional relacionadas con las características del local y los signos de consumo tabaco.ResultadosLa concentración de PM2,5 en los locales donde se permite fumar es cinco veces más alta que en los que se ha prohibido (182μg/m3 y 34μg/m3, respectivamente), y supera la concentración establecida como perjudicial por la Environmental Protection Agency de Estados Unidos (35μg/m3). En aquellos locales en que se ha prohibido fumar, la concentración de PM2,5 no supera este estándar ni muestra diferencias significativas con la concentración en el exterior del local.ConclusionesDos años después de la entrada en vigor de la Ley de medidas sanitarias frente al tabaquismo, la exposición al HAT en los locales de hostelería donde se permitía fumar seguía siendo muy alta. Esto suponía un importante riesgo para la salud de los trabajadores de este sector.AbstractObjectivesTo quantify the concentration of respirable particles equal to or smaller than 2.5μm (PM2.5) as a marker of second-hand smoke (SHS) exposure in a sample of hospitality venues in Barcelona 2 years after the Spanish smoking law came into effect.MethodsWe performed a cross-sectional descriptive study from October to December 2007. The study population consisted of 40 hospitality venues in Barcelona selected by a random route sampling, with representation of the different types of smoking regulation included in the law (smoking allowed, smoking ban and venues with smoking areas). SHS levels were quantified by measuring PM2.5 concentrations, which were measured using a laser photometer (Side Pack AM 510 Personal Aerosol Monitor). The measurements were carried out for 5minutes outside the venue and for 30minutes inside the venue. In addition, observational variables related to the characteristics of the venue and signs of tobacco consumption were recorded.ResultsThe concentration of PM2.5 in venues where smoking was still allowed was five times higher than that in venues where smoking was banned (182μg/m3 and 34μg/m3, respectively) and exceeded the concentration established by the US Environmental Protection Agency (EPA) as harmful (35μg/m3). However, in venues where smoking was banned, the concentration was lower than the EPA standard and there were no significant differences with the outdoor PM2.5 concentration.ConclusionsTwo years after the introduction of the Spanish smoking law, SHS exposure in venues where smoking was allowed was q still very high, representing a significant health risk for hospitality workers

Performance evaluation of secondary control policies with respect to digital communications properties in inverter-based islanded microgrids

A key challenge for inverted-based microgrids working in islanded mode is to maintain their own frequency and voltage to a certain reference values while regulating the active and reactive power among distributed generators and loads. The implementation of frequency and voltage restoration control policies often requires the use of a digital communication network for real-time data exchange (tertiary control covers the coordi- nated operation of the microgrid and the host grid). Whenever a digital network is placed within the loop, the operation of the secondary control may be affected by the inherent properties of the communication technology. This paper analyses the effect that properties like transmission intervals and message dropouts have for four existing representative approaches to secondary control in a scalable islanded microgrid. The simulated results reveals pros and cons for each approach, and identifies threats that properly avoided or handled in advance can prevent failures that otherwise would occur. Selected experimental results on a low- scale laboratory microgrid corroborate the conclusions extracted from the simulation study.Peer ReviewedPostprint (author's final draft