Análise de proveniência das contas verdes dos Perdigões

A variscite é um mineral raro que oferece uma excelente opotunidade de estudo dos padrões de comércio e troca na Europa durante a Pré- História através da determinação da sua fonte de proveniência. No presente texto será discutida a proveniência das contas de colar verdes com base em análises de XRF e XRD, através das quais se criou uma identidade geoquímica passível de ser comparada com as das fontes de variscite conhecidasVariscite is a rare mineral that offers an excellent opportunity to study trade and exchange patterns in prehistoric Europe through proveniencing of source material. In this paper we discuss the provenance of Perdigões’ green beads by means of XRF and XRD analyses, thus creating a geochemical baseline that is compared with that of the known variscite source

Cuentas de variscita: producción, circulación y presencia en contextos funerarios del suroeste peninsular

En este trabajo, a partir del estudio de unos casos concretos, la problemática de la presencia de las cuentas de collar de piedras verdes en los contextos funerarios del megalitismo del Suroeste peninsular duante la Prehistoria reciente en relación con los centros productores y redes de cirulación. Para ello, hemos realizado una investigación arqueométrica (XRD, XRF) de cuentas de collar procedentes de varias construcciones megalíticas de dos áreas geográficas que poseen dataciones radiocarbónicas calibradas, Cuenca Media del río Guadiana y Andévalo oriental (Huelva), y que comparamos con las fuentes de aprovisionamiento y minas de variscita de Pico Centeno (Encinasola, Huelva). El resultado provisional másd estacable, en torno al que planteamos la discusión, es que durante el III milenio ANE en el Sur peninsular se emplearon diversas materias primas (variscita, moscovita, talco y clorita) para la manufactura de elementos de adorno y su inclusión en redes de circulación de "productos exóticos" de escala regional y suprarregional.This work is focused on the relationship between green beads and the production centres during Iberian Peninsula Late Prehistory. To perform this research we have conducted scientific analyses (XRD, XRF) of beads coming from different megalithic contexts: Guadiana river middle basin and Oriental Andévalo (Huelva), that have been compared with the mineral recovered during the suvery and excavation of Pico Centeno variscite mines (Encinasola, Huelva). These results are discussed on the context of prehistoric exchange

Provenancing variscite beads: Pico Centeno (Encinasola, Spain) outcrop case study

In this study we discuss the exploitation and exchange of variscite at Pico Centeno mining district during the Copper Age. X-ray fluorescence and diffraction (XRF and XRD, respectively) and Fourier transform infrared spectroscopy (FTIR) analyses of the mineral recovered at Pico Centeno mining district provides a baseline mineral signature, which was then compared to other Iberian sources and beads from SW Iberian megalithic tombs. We found that the concentrations of trace elements don not allow establishing provenance of the beads, as traditionally claimed. Instead we found that different proportions of phosphate species, which results in P/Al ratios higher than 1, arose during the genesis of the variscite deposits, modifying the concentrations of PO4 3–, H2PO4 – and HPO4 2–. Thus, the P/Al atomic ratio should be an indication of provenance as it is established during mineral genesis

Source characterization variscite of Pico Centeno (Encinasola, Huelva) and study of origin of the Southwest peninsular accounts

En este trabajo estudiamos la explotación e intercambio de variscita de Pico Centeno (Encinasola, Huelva). El análisis XRD y XRF del mineral recogido en Pico Centeno durante las prospecciones arqueológicas proporcionan una impronta físico-química para cada una de las sub-fuentes localizadas durante la prospección. Estas improntas serán comparadas con otras fuentes europeas y con 50 cuentas procedentes de 8 tumbas megalíticas de dos regiones diferentes para comprobar modelos de distribución y procedencia. El mineral recuperado durante las prospecciones de Pico Centeno es variscita, mientras que las cuentas resultaron ser deminerales diversos (moscovita, talco, clorita). A la hora de comprobar la procedencia a través de la composición química encontramos que la alta variabilidad natural de los elementos traza (tradicionalmente considerados indicadores del origen) no permiten establecer la procedencia de las cuentas. Contrariamente pensamos que diferentes proporciones de fosfatos resultado de la génesis de la roca y que resultan en un cociente P/Al diferente de 1, podría ser utilizado cómo indicador del origen. Cocientes P/Al mayores de 1 no han sido descritos para ninguna otra fuente en EuropaIn this paper we discuss the exploitation and exchange of variscite at Pico Centeno source. XRF and XRD analyses of the mineral recovered at Pico Centeno mining district during archaeological survey provides a baselinemineral signature for the source and sub-sources, which were then compared to other sources and to 50 green beads from8megalithic tombs fromtwo different regions, in order to test ‘provenance postulate’ and distribution models. Mineral sampled during survey at Pico Centeno mining district turned out to be pure variscite phases, while extremely varied for the studied green beads: variscite, muscovite, talc or chlorite.We found that the concentrations of trace elements don not allow us to establish the origin of the beads, as traditionally claimed, due to the strong natural variability onminor and trace elements of the sources. Instead we found that different proportions of phosphate species, which results in P/Al ratios higher than 1, arose during the genesis of the variscite deposits. Thus, the P/Al atomic ratio should be an indication of provenance as it is established during mineral genesis. This issue has not been addressed in any of the other studied sources where this ratio seems to be ≈

Plant Responses to Extreme Climatic Events: A Field Test of Resilience Capacity at the Southern Range Edge

The expected and already observed increment in frequency of extreme climatic events may result in severe vegetation shifts. However, stabilizing mechanisms promoting community resilience can buffer the lasting impact of extreme events. The present work analyzes the resilience of a Mediterranean mountain ecosystem after an extreme drought in 2005, examining shoot-growth and needle-length resistance and resilience of dominant tree and shrub species (Pinus sylvestris vs Juniperus communis, and P. nigra vs J. oxycedrus) in two contrasting altitudinal ranges. Recorded high vegetative-resilience values indicate great tolerance to extreme droughts for the dominant species of pine-juniper woodlands. Observed tolerance could act as a stabilizing mechanism in rear range edges, such as the Mediterranean basin, where extreme events are predicted to be more detrimental and recurrent. However, resistance and resilience components vary across species, sites, and ontogenetic states: adult Pinus showed higher growth resistance than did adult Juniperus; saplings displayed higher recovery rates than did conspecific adults; and P. nigra saplings displayed higher resilience than did P. sylvestris saplings where the two species coexist. P. nigra and J. oxycedrus saplings at high and low elevations, respectively, were the most resilient at all the locations studied. Under recurrent extreme droughts, these species-specific differences in resistance and resilience could promote changes in vegetation structure and composition, even in areas with high tolerance to dry conditions.This study was supported by Ministerio de Ciencia e Innovación (Spanish Government) Projects CGL2008-04794 and CGL2011-29910 to R.Z., and by grant FPU-MEC (AP2005-1561) to A. H

Exploring venlafaxine pharmacokinetic variability with a phenotyping approach, a multicentric french-swiss study (MARVEL study).

It is well known that the standard doses of a given drug may not have equivalent effects in all patients. To date, the management of depression remains mainly empirical and often poorly evaluated. The development of a personalized medicine in psychiatry may reduce treatment failure, intolerance or resistance, and hence the burden and costs of mood depressive disorders. The Geneva Cocktail Phenotypic approach presents several advantages including the "in vivo" measure of different cytochromes and transporter P-gp activities, their simultaneous determination in a single test, avoiding the influence of variability over time on phenotyping results, the administration of low dose substrates, a limited sampling strategy with an analytical method developed on DBS analysis. The goal of this project is to explore the relationship between the activity of drug-metabolizing enzymes (DME), assessed by a phenotypic approach, and the concentrations of Venlafaxine (VLX) + O-demethyl-venlafaxine (ODV), the efficacy and tolerance of VLX. This study is a multicentre prospective non-randomized open trial. Eligible patients present a major depressive episode, MADRS over or equal to 20, treatment with VLX regardless of the dose during at least 4 weeks. The Phenotype Visit includes VLX and ODV concentration measurement. Following the oral absorption of low doses of omeprazole, midazolam, dextromethorphan, and fexofenadine, drug metabolizing enzymes activity is assessed by specific metabolite/probe concentration ratios from a sample taken 2 h after cocktail administration for CYP2C19, CYP3A4, CYP2D6; and by the determination of the limited area under the curve from the capillary blood samples taken 2-3 and 6 h after cocktail administration for CYP2C19 and P-gp. Two follow-up visits will take place between 25 and 40 days and 50-70 days after inclusion. They include assessment of efficacy, tolerance and observance. Eleven french centres are involved in recruitment, expected to be completed within approximately 2 years with 205 patients. Metabolic ratios are determined in Geneva, Switzerland. By showing an association between drug metabolism and VLX concentrations, efficacy and tolerance, there is a hope that testing drug metabolism pathways with a phenotypical approach would help physicians in selecting and dosing antidepressants. The MARVEL study will provide an important contribution to increasing the knowledge of VLX variability and in optimizing the use of methods of personalized therapy in psychiatric settings. ClinicalTrials.gov NCT02590185 (10/27/2015). This study is currently recruiting participants

Highest drought sensitivity and lowest resistance to growth suppression are found in the range core of the tree Fagus sylvatica L. not the equatorial range edge

Biogeographical and ecological theory suggests that species distributions should be driven to higher altitudes and latitudes as global temperatures rise. Such changes occur as growth improves at the poleward edge of a species distribution and declines at the range edge in the opposite or equatorial direction, mirrored by changes in the establishment of new individuals. A substantial body of evidence demonstrates that such processes are underway for a wide variety of species. Case studies from populations at the equatorial range edge of a variety of woody species have led us to understand that widespread growth decline and distributional shifts are underway. However, in apparent contrast, other studies report high productivity and reproduction in some range edge populations. We sought to assess temporal trends in the growth of the widespread European beech tree (Fagus sylvatica) across its latitudinal range. We explored the stability of populations to major drought events and the implications for predicted widespread growth decline at its equatorial range edge. In contrast to expectations, we found greatest sensitivity and low resistance to drought in the core of the species range, while dry range edge populations showed particularly high resistance to drought and little evidence of drought-linked growth decline. We hypothesise that this high range-edge resistance to drought is driven primarily by local environmental factors that allow relict populations to persist despite regionally unfavourable climate. The persistence of such populations demonstrates that range edge decline is not ubiquitous and is likely to be driven by declining population density at the landscape scale rather than sudden and widespread range retraction

Forest and woodland replacement patterns following drought-related mortality

Forest vulnerability to drought is expected to increase under anthropogenic climate change, and drought-induced mortality and community dynamics following drought have major ecological and societal impacts. Here, we show that tree mortality concomitant with drought has led to short-term (mean 5 y, range 1 to 23 y after mortality) vegetation-type conversion in multiple biomes across the world (131 sites). Self-replacement of the dominant tree species was only prevalent in 21% of the examined cases and forests and woodlands shifted to nonwoody vegetation in 10% of them. The ultimate temporal persistence of such changes remains unknown but, given the key role of biological legacies in long-term ecological succession, this emerging picture of postdrought ecological trajectories highlights the potential for major ecosystem reorganization in the coming decades. Community changes were less pronounced under wetter postmortality conditions. Replacement was also influenced by management intensity, and postdrought shrub dominance was higher when pathogens acted as codrivers of tree mortality. Early change in community composition indicates that forests dominated by mesic species generally shifted toward more xeric communities, with replacing tree and shrub species exhibiting drier bioclimatic optima and distribution ranges. However, shifts toward more mesic communities also occurred and multiple pathways of forest replacement were observed for some species. Drought characteristics, species-specific environmental preferences, plant traits, and ecosystem legacies govern post drought species turnover and subsequent ecological trajectories, with potential far-reaching implications for forest biodiversity and ecosystem services.Peer reviewe