288 research outputs found

    Tamarinier (Tamarindus indica)

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    Conservation and sustainable use of genetic resources of priority food tree species in sub-Saharan AfricaConservation et utilisation durable des ressources génétiques des espèces ligneuses alimentaires prioritaires de l'Afrique subsaharienneLa publicación de esta hoja divulgativa ha sido financiada con la acción complementaria nº AC-2008-00050-00-00, titulada "Publicación de hojas divulgativas: Uso y gestión sostenible y conservación de especies forestales para la alimentación (ELA) en Africa Subsahariana" solicitada por el Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), investigador responsable: Eduardo Notivo

    Non-invasive detection of animal nerve impulses with an atomic magnetometer operating near quantum limited sensitivity

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    Magnetic fields generated by human and animal organs, such as the heart, brain and nervous system carry information useful for biological and medical purposes. These magnetic fields are most commonly detected using cryogenically-cooled superconducting magnetometers. Here we present the frst detection of action potentials from an animal nerve using an optical atomic magnetometer. Using an optimal design we are able to achieve the sensitivity dominated by the quantum shot noise of light and quantum projection noise of atomic spins. Such sensitivity allows us to measure the nerve impulse with a miniature room-temperature sensor which is a critical advantage for biomedical applications. Positioning the sensor at a distance of a few millimeters from the nerve, corresponding to the distance between the skin and nerves in biological studies, we detect the magnetic field generated by an action potential of a frog sciatic nerve. From the magnetic field measurements we determine the activity of the nerve and the temporal shape of the nerve impulse. This work opens new ways towards implementing optical magnetometers as practical devices for medical diagnostics.Comment: Main text with figures, and methods and supplementary informatio

    Prunier d'Afrique (Sclerocarya birrea)

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    Conservation and sustainable use of genetic resources of priority food tree species in sub-Saharan AfricaConservation et utilisation durable des ressources génétiques des espèces ligneuses alimentaires prioritaires de l'Afrique subsaharienneLa publicación de esta hoja divulgativa ha sido financiada con la acción complementaria nº AC-2008-00050-00-00, titulada "Publicación de hojas divulgativas: Uso y gestión sostenible y conservación de especies forestales para la alimentación (ELA) en Africa Subsahariana" solicitada por el Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), investigador responsable: Eduardo Notivo

    Atomic-scale Interaction Dynamics in Few-layer Hexagonal Boron Nitride (h-BN)

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    Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7-August 11, 201

    Community exposure and vulnerability to water quality and availability: a case study in the mining-affected Pazña Municipality, Lake Poopó Basin, Bolivian Altiplano

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    This is the final version of the article. Available from Springer Verlag via the DOI in this record.Assessing water sources for drinking and irrigation along with community vulnerability, especially in developing and rural regions, is important for reducing risk posed by poor water quality and limited water availability and accessibility. We present a case study of rural mining-agricultural communities in the Lake Poopó Basin, one of the poorest regions on the Bolivian Altiplano. Here, relatively low rainfall, high evaporation, salinization and unregulated mining activity have contributed to environmental degradation and water issues, which is a situation facing many Altiplano communities. Social data from 72 households and chemical water quality data from 27 surface water and groundwater sites obtained between August 2013 and July 2014 were used to develop locally relevant vulnerability assessment methodologies and ratings with respect to water availability and quality, and Chemical Water Quality Hazard Ratings to assess water quality status. Levels of natural and mining-related contamination in many waters (CWQHR ≥ 6; 78% of assessed sites) mean that effective remediation would be challenging and require substantial investment. Although waters of fair to good chemical quality (CWQHR ≤ 5; 22% of assessed sites) do exist, treatment may still be required depending on use, and access issues remain problematic. There is a need to comply with water quality legislation, improve and maintain basic water supply and storage infrastructure, build and operate water and wastewater treatment plants, and adequately and safely contain and treat mine waste. This study serves as a framework that could be used elsewhere for assessing and mitigating water contamination and availability affecting vulnerable populations.This project was funded by the University College London (UCL) Institute for Risk and Disaster Reduction and the Catholic Agency for Overseas Development (CAFOD) under the initiative of water risk and its management in Bolivia’s Altiplano development strategy, which was led by Stephen Edwards. The Natural Environment Research Council Probability, Uncertainty and Risk in the Environment grant PA13-010 (risk visualisation and quantification for enhanced disaster risk reduction) to Stephen Edwards informed the approach to and outputs from the project

    Controlled Growth of a Line Defect in Graphene and Implications for Gate-Tunable Valley Filtering

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    Atomically precise tailoring of graphene can enable unusual transport pathways and new nanometer-scale functional devices. Here we describe a recipe for the controlled production of highly regular "5-5-8" line defects in graphene by means of simultaneous electron irradiation and Joule heating by applied electric current. High-resolution transmission electron microscopy reveals individual steps of the growth process. Extending earlier theoretical work suggesting valley-discriminating capabilities of a graphene 5-5-8 line defect, we perform first-principles calculations of transport and find a strong energy dependence of valley polarization of the charge carriers across the defect. These findings inspire us to propose a compact electrostatically gated "valley valve" device, a critical component for valleytronics

    Building the capacity of policy-makers and planners to strengthen mental health systems in low- and middle-income countries: a systematic review

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    Background Little is known about the interventions required to build the capacity of mental health policy-makers and planners in low- and middle-income countries (LMICs). We conducted a systematic review with the primary aim of identifying and synthesizing the evidence base for building the capacity of policy-makers and planners to strengthen mental health systems in LMICs. Methods We searched MEDLINE, Embase, PsycINFO, Web of Knowledge, Web of Science, Scopus, CINAHL, LILACS, ScieELO, Google Scholar and Cochrane databases for studies reporting evidence, experience or evaluation of capacity-building of policy-makers, service planners or managers in mental health system strengthening in LMICs. Reports in English, Spanish, Portuguese, French or German were included. Additional papers were identified by hand-searching references and contacting experts and key informants. Database searches yielded 2922 abstracts and 28 additional papers were identified. Following screening, 409 full papers were reviewed, of which 14 fulfilled inclusion criteria for the review. Data were extracted from all included papers and synthesized into a narrative review. Results Only a small number of mental health system-related capacity-building interventions for policy-makers and planners in LMICs were described. Most models of capacity-building combined brief training with longer term mentorship, dialogue and/or the establishment of networks of support. However, rigorous research and evaluation methods were largely absent, with studies being of low quality, limiting the potential to separate mental health system strengthening outcomes from the effects of associated contextual factors. Conclusions This review demonstrates the need for partnership approaches to building the capacity of mental health policy-makers and planners in LMICs, assessed rigorously against pre-specified conceptual frameworks and hypotheses, utilising longitudinal evaluation and mixed quantitative and qualitative approaches

    Perturbative evolution of particle orbits around Kerr black holes: time domain calculation

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    Treating the Teukolsky perturbation equation numerically as a 2+1 PDE and smearing the singularities in the particle source term by the use of narrow Gaussian distributions, we have been able to reproduce earlier results for equatorial circular orbits that were computed using the frequency domain formalism. A time domain prescription for a more general evolution of nearly geodesic orbits under the effects of radiation reaction is presented. This approach can be useful when tackling the more realistic problem of a stellar-mass black hole moving on a generic orbit around a supermassive black hole under the influence of radiation reaction forces.Comment: 8 pages, 5 figures, problems with references and double-printing fixe

    Moving magnetoencephalography towards real-world applications with a wearable system

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    Imaging human brain function with techniques such as magnetoencephalography1 (MEG) typically requires a subject to perform tasks whilst their head remains still within a restrictive scanner. This artificial environment makes the technique inaccessible to many people, and limits the experimental questions that can be addressed. For example, it has been difficult to apply neuroimaging to investigation of the neural substrates of cognitive development in babies and children, or in adult studies that require unconstrained head movement (e.g. spatial navigation). Here, we develop a new type of MEG system that can be worn like a helmet, allowing free and natural movement during scanning. This is possible due to the integration of new quantum sensors2,3 that do not rely on superconducting technology, with a novel system for nulling background magnetic fields. We demonstrate human electrophysiological measurement at millisecond resolution whilst subjects make natural movements, including head nodding, stretching, drinking and playing a ball game. Results compare well to the current state-of-the-art, even when subjects make large head movements. The system opens up new possibilities for scanning any subject or patient group, with myriad applications such as characterisation of the neurodevelopmental connectome, imaging subjects moving naturally in a virtual environment, and understanding the pathophysiology of movement disorders
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