681 research outputs found

    Macroeconomic drivers of baseline scenarios in dynamic CGE models: review and guidelines proposal

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    For dynamic computable general equilibrium (CGE) modeling, long-term baseline construction is key and depends on the applied methods and the sources of projections considered. For dynamic CGE models, baseline assumptions and base data are both important determinants of results. This paper reviews the assumptions made by 24 modeling teams on baseline macroeconomic drivers, understood as factor accumulation and gross domestic product (GDP) growth. We critically review the various methods, identifying state-of-the-art practices and propose simple guidelines, particularly focusing on consistency between data sources and models, which is intended to help dynamic CGE modelers build their own baselines

    Isotopic and magnetic provenance characterization of distal IRD in the Galicia Interior Basin (NW Iberia)

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    The sediments of the Galicia Interior Basin in NW Iberia Margin are of particular palaeoclimatic interest as they are located at the boundary where the climatic oscillations of the glacial interval were interrupted by extreme events such as Heinrich events. These events are well characterized in Northern North Atlantic areas, but little is known about their occurrence beyond the Ruddiman belt. This study presents a combined environmagnetic and geochemical approach to the provenance and characterization of distal ice-rafted detritus (IRD) that occurred during the last glacial period in core CI12PC3 from the Galicia Interior Basin. The last six Heinrich Layers were identified by their magneto-mineralogical and geochemical properties. Their Sr and Nd isotopic signatures indicated that the Laurentide Ice Sheet was the major source for HL1, HL2, HL4 and HL5. However, the European ice sheets also influenced the initial development stages of HL1, HL2, HL4. HL3, HL6 and partially HL1, HL2 and HL4 were influenced by more juvenile provinces, such as Iceland/Faroes sheets and/or by the Fram Strait/East Greenland nearby areas. Separate provenance analyses of the coarse and fine fractions in the studied Heinrich Layers also indicated that IRDs and glacial flour sources might not always be the same. Our results shed unequivocal evidence that Canadian-sourced distal IRD are preceded by European-sourced IRD, at least from the H4. In our view, LIS and EIS instabilities registered in the Iberian Margin respond to the same climate forcing at different velocities

    IRD characterization, provenance and age in the Galician Interior Basin

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    The Galician Interior Basin sediments have a particular palaeoclimatic interest, as they are located in the boundary where the climatic oscillations of the glacial interval were interrupted by extreme events such as Heinrich events (HE). The sedimentary expression of these events is characterized by the presence of distal Ice Rafted Detritus (IRD). IRD layers can be identified by the rapid increase in magnetic susceptibility values (κ) up to 400x10-6SI, from background values lower than 100x10-6 SI providing key information on climatically forced events and allowing a tighter chronostratigraphic control. However, the mixing of these materials with local/regional components may difficult their depiction, and also the occurrence of diagenetic processes that alter their original magnetic composition, to the point of under detection by standard magnetic analysis (susceptibility). The aim of this paper is the environmagnetic and geochemical characterization of these distal IRD occurring in the area and the study of their age and provenance related to the last six HE. In order to achieve these goals we measured their magnetic properties, their chemical and mineralogical composition and performed the analyses of Sr and Nd isotope ratios measured in the detrital fraction of one of the cores. This study explores the potential of magnetic properties as a tool to discriminate Heinrich layers provenance in base to differences in their magnetic mineralogy assemblages

    Magnetic properties contribution to the identification and provenance of marine sediments: distal IRD in the Galicia Interior Basin (NW Spain)

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    This paper discusses the advantages of using a combined environmagnetic and geochemical approach to the provenance and characterization of distal IRDs occurring during the Last Glacial Period in core CI12PC3 from the Galicia Interior Basin (GIB). Six Heinrich layers (HL1-6) have been identified in the area in base to the detection of distinct populations of exotic magnetic mineral assemblages alien to the local/regional sedimentation environment. Their extension has been determined by Ca/Sr and Si/Sr ratios and their provenance by 143Nd/144Nd and 87Sr/86Sr isotopic ratios and FORCs. The sedimentary expression of HL is characterized by the presence of distal Ice Rafted Detritus (IRD). Distal IRD magnetic signatures in the GIB consist of (i) an increase of one order of magnitude in the peak amplitude of magnetic susceptibility from background values, (ii) a general coarsening of the magnetic grain size in a mineral assemblage dominated by titano-magnetites, (iii) FORC distributions pushing towards the coarse MD or PSD component, and (iv) thermomagnetic curves depicting the occurrence of several magnetite phases. These four features are very different from the fine-grained biogenic magnetic assemblages characterized by the combination of lower MS and higher coercivity values that dominate the predominant mixtures of the non-interacting SSD and PSD components in the non-IRD influenced background sedimentation. Our results show that the last 70.000 yr of sedimentation in the GIB were controlled by the relative contribution of local detrital material derived from the Iberian Variscan Chain and IRD alien material from the iceberg melting during the Heinrich Events. They also show two main IRD provenance fields: Europe and Canada. And that the later is more important for for HL1, HL2, HL4 and HL5. FORCs analysis complemented the isotopic information and provided a very unique information, indicating that glacial flour may not always have the same provenance as IRD and that ice-melted derived suspended sediment has its own dynamics and may reach further and/or persists longer than IRD

    Composição isotópica de Nd na componente terrígena de sedimentos como marcador de eventos de Heinrich:estudo de um caso na margem continental NW Ibérica

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    The OMEX core KC 024-19 was studied aiming at to assess the influence of climate changes on the origin and transport of the sediments of the Galician continental slope, in the last 40 ka. The results show that sea level variation played a major role in the supply of the terrigenous sediments coming from the nearby continental areas, whose basement has a Variscan age. Additionally, coarse-grained clastic materials, corresponding to ice-rafted debris (IRD), were deposited through melting of icebergs during the Heinrich events (HE), in the last glaciation. The last four HE were identified in the core. The measured Nd isotope ratios reveal that there was a strong contribution of continental crustal sources significantly older than the Variscan basement for HE 1, 2 and 4. The most likely provenance of the coarse clasts deposited during these three events lie in NE America or Greenland, and the carrier icebergs should be fragments of the Laurentide Ice Sheet. In contrast, the HE 3 layer displays εNd values in the range of the compositions of the most common sediments in the core and, therefore, its IRD should have European source(s), which supports previous results obtained in other places of the European Atlantic margin.O core OMEX KC 024-19 foi estudado tendo em vista avaliar o papel das mudanças climáticas nos processos de transporte e nas fontes de sedimentos depositados no talude continental da Galiza, durante os últimos 40 ka. Os resultados obtidos, usando diferentes metodologias, apontam para uma grande influência das mudanças do nível do mar no fornecimento de sedimentos terrígenos a partir das áreas continentais próximas, cujo soco é de idade varisca. Para além disso, nos eventos de Heinrich (HE), ocorridos durante a última glaciação, foram recebidos nesta área materiais detríticos grosseiros transportados por icebergues em fusão (IRD). Foram identificados, neste core, os quatro últimos HE. As razões isotópicas de Nd revelam que durante os HE 1, 2 e 4 houve contribuição importante de fontes de crusta continental significativamente mais antiga do que a ibérica. A origem provável dos IRD desses três eventos estará no NE da América ou na Gronelândia, podendo os icebergues que os transportaram ter origem na LIS (Laurentide Ice Sheet). Já o HE 3, não se distingue, em termos de εNd, dos sedimentos mais comuns no core, pelo que os IRD correspondentes deverão ter origem europeia, o que corrobora resultados obtidos noutros locais da margem atlântica europeia

    Sedimentary climatic record in the Galician Internal Basin: sediment provenance, transport time and hydrodynamics over the last 60.000 years

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    The sediments of the Galician Interior Basin are influenced by the Atlantic Meridional Overturning Circulation (AMOC) and by their proximity to the Western Iberia continental landmass, and thus provide an adequate archive to study the peculiarities of the last glacial‐interglacial dynamics and the transition into present day conditions. The aim of this study has been to analyse the sedimentary expression of climatic processes and forcings derived from the relation between the last North Atlantic glacial cycle and the local regional components -including abrupt climate changes and local events- since the end of the last glacial period in this area. We have attempted to establish the rates and magnitudes of change of this system to understand its climate dynamics, processes and feedbacks, and hence its role on a local to sub‐regional scale from a palaeoclimatic proxies perspective. The inference of these climatic mechanisms encrypted in the deep-sea sedimentary record needs to constrain the spatial and temporal scales of the sedimentary processes involved, in particular the identification of source areas, pathways and transport, storage times and hydrodynamic conditions. In order to achieve these goals we have used a twofold approach; an initial effort to constrain the current sedimentary conditions to their associated local hydrography conditions by means of a mooring, which will be used to later infer the palaeoenvironmental conditions from sediment cores. The location of the mooring and the 5 coring locations has been based on the acquisition of new geophysical data: a precise 20 x 20 m bathymetry covering an area of 9860 km2 and 690 km of high-resolution seismic profiles distributed in 10 transects that allow to investigate the main sedimentary units in the region. The mooring comprised 2 sediment traps located at 500 and 1400 m below the sea surface. These depths are under the influence of the Eastern North Atlantic Central Water (ENACW) and Mediterranean Water (MW). The sediment traps also target sediments from the shelf and the upper slope. Sediments were collected monthly for a 9 month period, whilst hydrographic conditions such as current speed, salinity, oxygen and turbidity were continuously recorded in associated instruments at the same depths. Finally, a multidisciplinary study combining resolution scans, including geochemistry (ITRAX), physical properties (GEOTEK) and enviromagnetic properties (2G cryogenic magnetometer), has been constrained using a very robust geochronology framework. Further analyses comprised grain size distributions, S͞S, SEM, XRD, stable and high-precision radioactive isotopes. The area consists mostly of generally autochthonous hemipelagic and terrigenous muds and sandy to silty muds with high clay content, showing abundant bioturbation and early diagenesis. Allochthonous material of different provenances (characterized by 143Nd/144Nd and 87Sr/ 86Sr isotopic ratios) occurs interbedded within the hemipelagic sediments associated to Heinrich Stadials HS1 to HS6. The sediments also show significant changes in the vigour of bottom-currents (based on the S͞S proxy) both within and between the HS. The combination of these sedimentological, geochemical and geophysical data has provided a new insight into the role of current strength, circulation and sediment provenance changes in the area, and allowed to establish across vs. along margin transport balances in the sedimentary record of the Galician Internal basin over the last 60 Ky

    Pindo: proyecto de investigación en la práctica docente

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    El cambio en el paradigma educativo de los últimos años trae consigo la organización de espacios supranacionales de educación y exige una revisión profunda de las metodologías docentes. Los diversos escenarios que han ido surgiendo con la revolución tecnológica nos permiten alcanzar un consenso en la forma de evaluar las competencias que los estudiantes han de adquirir en los diferentes niveles educativos. Para que este cambio sea efectivo es necesaria una organización de los equipos profesionales que excede el ámbito local (departamentos) y nacional (colaboración interuniversitaria en un país). Por este motivo, los profesores que participamos en este estudio, junto con varias instituciones de educación superior europeas y latinoamericanas, hemos desarrollado una propuesta acorde con las nuevas necesidades educativas en la universidad. Dicha propuesta, con su motivación, los objetivos que se consideran y la metodología para alcanzarlos, se detallan a lo largo de este artículo, con la finalidad de generar un debate que logre mejorarla e involucrar a más universidades para que aporten nuevos puntos de vista

    El arte rupestre galaico: una reflexión crítica sobre el presente y una propuesta para el futuro

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    In the paper it is proposed a management standard for the Galician Rock Art having as basic idea the determination and evaluation of Heritage and, then, to work on it in order to a more effective protection and better social profitabily. General protective measures are considered and deep actions on the scientifically and socially most outstanding units are suggested.<br><br>En el artículo se pasa revista a los principales problemas de conservación que afectan a los grabados rupestres galaicos y se propone un Plan de Gestión de los mismos. La idea básica es que se determina un Patrimonio, se evalúa y se actúa sobre el mismo para obtener una protección más efectiva y una mayor rentabilización social. Se sugieren acciones profundas sobre conjuntos relevantes y significativos científica y socialmente

    El arte rupestre galaico: una reflexión crítica sobre el presente y una propuesta para el futuro

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    In the paper it is proposed a management standard for the Galician Rock Art having as basic idea the determination and evaluation of Heritage and, then, to work on it in order to a more effective protection and better social profitabily. General protective measures are considered and deep actions on the scientifically and socially most outstanding units are suggested.En el artículo se pasa revista a los principales problemas de conservación que afectan a los grabados rupestres galaicos y se propone un Plan de Gestión de los mismos. La idea básica es que se determina un Patrimonio, se evalúa y se actúa sobre el mismo para obtener una protección más efectiva y una mayor rentabilización social. Se sugieren acciones profundas sobre conjuntos relevantes y significativos científica y socialmente

    Effects of amphetamine on development of oral candidiasis in rats

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    [Abstract] Experiments were conducted to evaluate the effects of amphetamine (0.4 mg/kg of body weight/day) on the development of oral candidiasis in Sprague-Dawley rats. Animals were submitted to surgical hyposalivation in order to facilitate the establishment and persistence of Candida albicans infection. Treatment with drugs (placebo or amphetamine) was initiated 7 days before C. albicans inoculation and lasted until the end of the experiments, day 15 postinoculation. Establishment of C. albicans infection was evaluated by swabbing the inoculated oral cavity with a sterile cotton applicator on days 2 and 15 after inoculation, followed by plating on YEPD (yeast extract-peptone-dextrose) agar. Tissue injury was determined by the quantification of the number and type (normal or abnormal) of papillae on the dorsal tongue per microscopic field. A semiquan- titative scale was devised to assess the degree of colonization of the epithelium by fungal hyphae. Our results show that amphetamine exacerbates C. albicans infection of the tongues of rats. Significant increases in Candida counts, the percentage of the tongue’s surface covered with clinical lesions, the percentage of abnormal papillae, and the colonization of the epithelium by fungal hyphae were found in amphetamine-treated rats compared to those found in the rats injected with a placebo. The last two parameters increased in rats treated with the placebo compared to the parameters of the untreated control rats
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