375 research outputs found

    Bæredygtig energiudvikling

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    Policy Means for Sustainable Energy Scenarios

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    Consequences of global warming are appearing much faster than assumed just a few years ago and irreversible ”tipping points” are few years ahead (IPCC, 2007; Hansen et al., 2008; Kopp et al., 2009). Despite long and tedious preparations for COP15 in December 2009 the final result (Copenhagen Accord, 2009) lacked sufficient concrete commitments for reduction of greenhouse gases (GHGs) after 2012 when the Kyoto Protocol expires. Human activities in their present form are strongly dependent on the supply of energy. A dominant part of the global energy supply is based on fossil fuels and a dominant part of the climate change is due to emission of CO2 from the use of fossil fuels. For simplicity, this paper focuses on CO2 emission from fossil fuels, but CO2 from deforestation as well as methane (CH4), laughing gas (N2O) and a number of industrial greenhouse gases should be included in a more comprehensive analysis. The paper will focus mainly on non-technological strategies for mitigation of climate change addressing such questions as national and international equity, limits to growth, population policies, and alternative employment policies

    Effect of acute hypobaric hypoxia on the endothelial glycocalyx and digital reactive hyperemia in humans

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    Introduction: Hypoxia is associated with increased capillary permeability. This study tested whether acute hypobaric hypoxia involves degradation of the endothelial glycocalyx. Methods: We exposed 12 subjects to acute hypobaric hypoxia (equivalent to 4,500 m for 2-4 hours) and measured venous blood concentrations of biomarkers reflecting endothelial and glycocalyx degradation (catecholamines, syndecan-1, soluble CD40 ligand, protein C, soluble thrombomodulin, tissue-type plasminogen activators, histone-complexed DNA fragments and nitrite/nitrate). Endothelial function was assessed by the hyperemic response to brachial artery occlusion by peripheral arterial tonometry. Results: Compared with normoxic baseline levels, hypoxia increased concentrations of syndecan-1 from 22 (95% confidence interval: 17-27) to 25 (19-30) ng/ml (p < 0.02) and protein C from 76 (70-83) % to 81 (74-88) % (p < 0.02). Nitrite/nitrate decreased from 23 (18-27) μM at baseline to 19 (14-24) μM and 18 (14-21) μM in hypoxia and recovery, respectively (p < 0.05). Other biomarkers remained unchanged. The post-occlusion/pre-occlusion ratio (reactive hyperemia index, RHI) decreased from 1.80 (1.52–2.07) in normoxia to 1.62 (1.28–1.96) after 2 to 4 hours of hypobaric hypoxia and thereafter increased to 2.43 (1.99-2.86) during normoxic recovery (p < 0.01). Conclusions: The increase in syndecan-1 and protein C suggests that acute hypobaric hypoxia produces minor degree of glycocalyx degradation and overall cellular damage. After hypoxia RHI rebounded to higher than baseline levels suggesting improved endothelial functionality

    External effects in the utilisation of renewable energy

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