151 research outputs found

    Sodium metasomatism and magnesio-riebeckite mineralization in the Wilson Ridge pluton

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    The Wilson Ridge pluton contains a rare occurrence of hydrothermal sodic amphibole. hydrothermal amphibole occurs as fracture coatings, veinlets, dense stockwork-type networks, and diffusive alteration fronts. Electron microprobe analyses of the hydrothermal amphibole reveal a range of Na-rich compositions, most notably magnesio-riebeckite. Magnesio-riebeckite in the Wilson Ridge pluton formed by Na-metasomatism related to subsolidus hydrothermal alteration involving Na-rich fluids of meteoric origin. Whole-rock geochemistry of samples from zones of hydrothermal amphibole show enrichment of Na2O (\u3e9.6 wt. %) and depletion of K2O (0.15 wt. %) and CaO (2.4 wt. %) relative to unaltered host rock. Secondary fluid inclusions associated with zones of hydrothermal amphibole contain daughter crystals of halite and up to three other unknown crystals. Oxygen isotope studies suggest that granitoid rocks containing hydrothermal amphiboles have lower delta18O values (+3.68‰ to +6.97‰) than unaltered granitoid rocks (delta 18O values +6.04‰ to +9.23‰)

    Age at menopause and lung function: a Mendelian randomisation study

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    In observational studies, early menopause is associated with lower forced vital capacity (FVC) and a higher risk of spirometric restriction, but not airflow obstruction. It is, however, unclear if this association is causal. We therefore used a Mendelian randomisation (MR) approach, which is not affected by classical confounding, to assess the effect of age at natural menopause on lung function.We included 94\u200a742 naturally post-menopausal women from the UK Biobank and performed MR analyses on the effect of age at menopause on forced expiratory volume in 1\u2005s (FEV1), FVC, FEV1/FVC, spirometric restriction (FV

    Eureka and beyond: mining's impact on African urbanisation

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    This collection brings separate literatures on mining and urbanisation together at a time when both artisanal and large-scale mining are expanding in many African economies. While much has been written about contestation over land and mineral rights, the impact of mining on settlement, notably its catalytic and fluctuating effects on migration and urban growth, has been largely ignored. African nation-states’ urbanisation trends have shown considerable variation over the past half century. The current surge in ‘new’ mining countries and the slow-down in ‘old’ mining countries are generating some remarkable settlement patterns and welfare outcomes. Presently, the African continent is a laboratory of national mining experiences. This special issue on African mining and urbanisation encompasses a wide cross-section of country case studies: beginning with the historical experiences of mining in Southern Africa (South Africa, Zambia, Zimbabwe), followed by more recent mineralizing trends in comparatively new mineral-producing countries (Tanzania) and an established West African gold producer (Ghana), before turning to the influence of conflict minerals (Angola, the Democratic Republic of Congo and Sierra Leone)

    Déclaration sur l’approche par l’archéologie sociale du changement climatique

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    Manifiesto sobre Arqueología Social del Cambio Climático aprobado en la Cumbre SACC celebrada en Kiel. Aprobado y firmado el 6 de septiembre de 2021.[ES] El SACC es un grupo independiente, constituido en Kiel, de investigadores e investigadoras que trabajan sobre cambio climático. El objetivo de SACC es reunir científicos y científicas internacionales y representantes de importantes organizaciones internacionales de las áreas de arqueología, paleoecología y gestión del patrimonio para con el fin de discutir y evaluar la contribución de la investigación arqueológica y paleo-ecológica para comprender la interrelación entre el cambio social, el cultural, el ecológico y el climático. Pretendemos resaltar cómo la arqueología, a través del estudio de la conducta adaptativa en el pasado, es capaz de reforzar tanto la resiliencia socio-ecológica de nuestras sociedades, como su capacidad adaptativa ante el actual cambio climático. Además, pretendemos contribuir a la comprensión del impacto del cambio climático en los yacimientos y sitios arqueológicos y patrimoniales, así como en los paisajes culturales, los museos, las colecciones y archivos patrimoniales. SACC celebrará cumbres cada dos años y emitirá una declaración o manifiesto al término de cada una de ellas. S ACC está organizada por un comité interino presidido por las personas convocantes del SACC 1.[EN] SACC is an independent group of researchers working on climate change in the past constituted in Kiel. The aim of SACC is to bring together international scientists and representatives of important international organisations in the fields of archaeology, paleoecology and heritage management to discuss and evaluate the contribution of archaeological and paleo-ecological research to understand the link between social, cultural, ecological and climatic change; and to highlight how archaeology, through the study of past adaptive behaviour, is able to enhance socio-ecological resilience of societies as well as their adaptive capacity to current climate change; furthermore, to contribute to the understanding of the impact of climate change on archaeological and heritage sites as well as on cultural landscapes, museums, collections, and archives. SACC will hold its summit every second year with a declaration at the end of each summit. SACC is organized by a steering committee chaired by the SACC 1 organisers.[FR] Le SACC est un groupe indépendant de chercheurs travaillant sur le changement climatique dans le passé, qui s’est formé à Kiel. L’objectif du S ACC est de réunir des scientifiques internationaux et des représentants d’organisations internationales importantes dans les domaines de l’archéologie, de la paléoécologie et de la gestion du patrimoine. Il a pour objectif de discuter et d’évaluer la contribution de la recherche archéologique et paléo-écologique à la compréhension du lien entre les changements sociaux, culturels, écologiques et climatiques et de souligner comment l’archéologie, par l’étude du comportement adaptatif du passé, est capable d’améliorer la résilience socioécologique des sociétés ainsi que leur capacité d’adaptation au changement climatique actuel. En outre, il contribue à la compréhension de l’impact du changement climatique sur les sites archéologiques et patrimoniaux ainsi que sur les paysages culturels, les musées, les collections et les archives. Le SACC tiendra son conseil tous les deux ans avec une déclaration à la fin de chaque conseil. Il est organisé par un comité de pilotage présidé par les organisateurs de SACC 1.Peer reviewe

    Crop pests and predators exhibit inconsistent responses to surrounding landscape composition

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    The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies
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