414 research outputs found

    Ambitious partnership needed for reliable climate prediction.

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    Current global climate models struggle to represent precipitation and related extreme events, with serious implications for the physical evidence base to support climate actions. A leap to kilometre-scale models could overcome this shortcoming but requires collaboration on an unprecedented scale

    Fractionation of lead in soil by isotopic dilution and sequential extraction

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    ‘Reactivity’ or ‘lability’ of lead is difficult to measure using traditional methods. We investigated the use of isotopic dilution with 204Pb to determine metal reactivity in four soils historically contaminated with contrasting sources of Pb, including (i) petrol-derived Pb, (ii) Pb/Zn minespoil, (iii) long-term sewage sludge application and (iv) 19th century urban waste disposal; total soil Pb concentrations ranged from 217 to 13 600 mg kg–1. A post-spike equilibration period of 3 days and suspension in 5.0 × 10–4 M ethylenediaminetetraacetic acid provided reasonably robust conditions for measuring isotopically exchangeable Pb. However, in acidic organic soils a dilute Ca(NO3)2 electrolyte may be preferable to avoid mobilisation of ‘non-labile’ Pb. Results showed that the reactive pool of soil Pb can be a large proportion of the total soil lead content but varies with the original Pb source. A comparison of isotopic exchangeability with the results of a sequential extraction procedure showed that (isotopically) ‘non-labile’ Pb may be broadly equated with ‘residual’ Pb in organic soils. However, in mineral soils the ‘carbonate’ and ‘oxide-bound’ Pb fractions included non-labile forms of Pb. The individual isotopic signatures of labile and non-labile Pb pools suggested that, despite prolonged contact with soil, differences between the lability of the original contaminant and the native soil Pb may remain

    Spatial and temporal variations in Pb concentrations and isotopic composition in road dust, farmland soil and vegetation in proximity to roads since cessation of use of leaded petrol in the UK

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    Results are presented for a study of spatial distributions and temporal trends in concentrations of lead (Pb) from different sources in soil and vegetation of an arable farm in central Scotland in the decade since the use of leaded petrol was terminated. Isotopic analyses revealed that in all of the samples analysed, the Pb conformed to a binary mixture of petrol Pb and Pb from industrial or indigenous geological sources and that locally enhanced levels of petrol Pb were restricted to within 10 m of a motorway and 3 m of a minor road. Overall, the dominant source of Pb was historical emissions from nearby industrial areas. There was no discernible change in concentration or isotopic composition of Pb in surface soil or vegetation over the decade since the ban on the sale of leaded petrol. There was an order of magnitude decrease in Pb concentrations in road dust over the study period, but petrol Pb persisted at up to 43% of the total Pb concentration in 2010. Similar concentrations and spatial distributions of petrol Pb and non petrol Pb in vegetation in both 2001 and 2010, with enhanced concentrations near roads, suggested that redistribution of previously deposited material has operated continuously over that period, maintaining a transfer pathway of Pb into the biosphere. The results for vegetation and soil transects near minor roads provided evidence of a non petrol Pb source associated with roads/traffic, but surface soil samples from the vicinity of a motorway failed to show evidence of such a source

    Evidence Based Estimation of Macrodispersivity for Groundwater Transport Applications

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    The scope of this work is to discuss the proper choice of macrodispersion coefficients in modeling contaminant transport through the advection dispersion equation (ADE). It is common to model solute concentrations in transport by groundwater with the aid of the ADE. Spreading is quantified by macrodispersivity coefficients, which are much larger than the laboratory observed pore-scale dispersivities. In the frame of stochastic theory, longitudinal macrodispersivity is related to the hydraulic conductivity spatial variability via its statistical moments (mean, variance, integral scales), which are generally determined by geostatistical analysis of field measurements. In many cases, especially for preliminary assessment of contaminant spreading, these data are not available and ad hoc values are adopted by practitioners. The present study aims at recommending dispersivity values based on a thorough analysis of tens of field experiments. Aquifers are classified as of weak, medium, and high heterogeneity and for each class a range of macrodispersivity values is recommended. Much less data are available for the transverse macrodispersivities, which are significantly smaller than the longitudinal one. Nevertheless, a few realistic values based on field data, are recommended for applications. Transport models using macrodispersivities can predict mean concentrations, different from the local ones. They can be used for estimation of robust measures, like plumes spatial moments, longitudinal mass distribution and breakthrough curves at control planes

    The Social and Political Dimensions of the Ebola Response: Global Inequality, Climate Change, and Infectious Disease

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    The 2014 Ebola crisis has highlighted public-health vulnerabilities in Liberia, Sierra Leone, and Guinea – countries ravaged by extreme poverty, deforestation and mining-related disruption of livelihoods and ecosystems, and bloody civil wars in the cases of Liberia and Sierra Leone. Ebola’s emergence and impact are grounded in the legacy of colonialism and its creation of enduring inequalities within African nations and globally, via neoliberalism and the Washington Consensus. Recent experiences with new and emerging diseases such as SARS and various strains of HN influenzas have demonstrated the effectiveness of a coordinated local and global public health and education-oriented response to contain epidemics. To what extent is international assistance to fight Ebola strengthening local public health and medical capacity in a sustainable way, so that other emerging disease threats, which are accelerating with climate change, may be met successfully? This chapter considers the wide-ranging socio-political, medical, legal and environmental factors that have contributed to the rapid spread of Ebola, with particular emphasis on the politics of the global and public health response and the role of gender, social inequality, colonialism and racism as they relate to the mobilization and establishment of the public health infrastructure required to combat Ebola and other emerging diseases in times of climate change

    Assessment of the infectious diseases surveillance system of the Republic of Armenia: an example of surveillance in the Republics of the former Soviet Union

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    BACKGROUND: Before 1991, the infectious diseases surveillance systems (IDSS) of the former Soviet Union (FSU) were centrally planned in Moscow. The dissolution of the FSU resulted in economic stresses on public health infrastructure. At the request of seven FSU Ministries of Health, we performed assessments of the IDSS designed to guide reform. The assessment of the Armenian infectious diseases surveillance system (AIDSS) is presented here as a prototype. DISCUSSION: We performed qualitative assessments using the Centers for Disease Control and Prevention (CDC) guidelines for evaluating surveillance systems. Until 1996, the AIDSS collected aggregate and case-based data on 64 infectious diseases. It collected information on diseases of low pathogenicity (e.g., pediculosis) and those with no public health intervention (e.g., infectious mononucleosis). The specificity was poor because of the lack of case definitions. Most cases were investigated using a lengthy, non-disease-specific case-report form Armenian public health officials analyzed data descriptively and reported data upward from the local to national level, with little feedback. Information was not shared across vertical programs. Reform should focus on enhancing usefulness, efficiency, and effectiveness by reducing the quantity of data collected and revising reporting procedures and information types; improving the quality, analyses, and use of data at different levels; reducing system operations costs; and improving communications to reporting sources. These recommendations are generalizable to other FSU republics. SUMMARY: The AIDSS was complex and sensitive, yet costly and inefficient. The flexibility, representativeness, and timeliness were good because of a comprehensive health-care system and compulsory reporting. Some data were questionable and some had no utility

    Effectiveness and safety of dabigatran in Latin American patients with atrial fibrillation: two years follow up results from GLORIA-AF registry

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    Background: Real-world data from different regions are needed to support the external validity of controlled trials and assess the impact of new oral anticoagulants (NOAC) in clinical practice.Methods: "GLORIA-AF" is a large, ongoing, multicenter, global, prospective registry program in patients with newly diagnosed non-valvular atrial fibrillation (NVAF) at risk of stroke. Newly diagnosed patients with NVAF (within 4.5 months) and a CHA(2)DS(2)-VASc score >= 1 were consecutively enrolled. The study objective was to estimate the incidence rate of stroke and major bleeding after a two year follow up of patients on dabigatran that participated in the ``GLORIA-AF" study (Phase II) in Latin America.Results: Latin America included 378 eligible patients that received dabigatran in eight countries (Argentina, Brazil, Chile, Colombia, Ecuador, Mexico, Peru, and Venezuela): 56.3% were male; mean age was 70.3 +/- 10.8 years; 43.4% had paroxysmal AF; 36.0% persistent AF and 20.6% permanent AF. Mean CHA(2)DS(2)-VASc score was 3.2 +/- 1.4; mean HAS-BLED score was 1.2 +/- 0.8. Incidence rates for clinical events after 2-years of follow-up per 100 patient-years were as follows: stroke 0.33 (95% CI: 0.04-1.17), major bleeding 0.49 (95% CI: 0.10-1.42) and all-cause death 4.06 (95% CI: 2.63-6.00). Persistence with dabigatran at 6, 12 and 24 months was 91%, 86%, and 80%, respectively.Conclusion: These regional data shows the sustained safety and effectiveness of dabigatran over two years of follow-up, consistent with already available evidence. An increase in accessibility and incorporation of NOAC to anticoagulant treatment strategies could potentially have a positive impact on AF stroke prevention in Latin America. (C) 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Thrombosis and Hemostasi
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