201 research outputs found

    Emerging energy geographies : scaling and spatial divergence in European electricity generation capacity

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    This paper presents an evaluation of the impact of the related EU internal energy market and renewable energy policies by exploring the (sustainable) energy transition in the EUropean electricity sector and drawing on the emerging literatures on energy geographies. We use evidence aggregated from plant-level data on installed electricity generation capacity in the EUropean electric utilities sector over the period 1990–2013 to demonstrate how the unintended interaction between EU policies on energy market liberalization and climate change have led to new renewable energy entrants and more widely dispersed ownership of total generation capacity. Our empirical results suggest that six energy geography concepts enable deeper insights into the spatiality of the EUropean energy transition. Specifically, we find that territoriality and scaling are key lenses for interpreting the differentiated change processes occurring at EUropean, subregional and national levels. The EUropean energy transition is unlikely to converge onto a single trajectory any time soon, but particularly subregional approaches are argued to offer policy-makers with more spatially cognizant and effective levers

    Competition for Light in a \u3ci\u3eLeucaena leucocephala / Chloris gayana\u3c/i\u3e Silvopastoral System

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    The spatial variation in the vigour of Leucaena (Leucaena leucocephala cv. Cunningham) trees growing together with Rhodesgrass (Chloris gayana cv. Katambora) in an alley cropping system made it possible to assess the competitive effect for light. The height and especially lateral development of trees had a strong influence on light interception by the canopy, with radiation in the intercrop area being 49% lower where the trees were more vigorous. There was a corresponding (43%) decrease in grass production. These findings indicate that future studies should also include aspects such as espacement of trees, pruning of trees in the growing season, choice of shade tolerant grasses and the competitive effect for water

    Use of sedation to relieve refractory symptoms in dying patients

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    Objectives. To document the use of sedation for refractory symptoms in patients admitted to an independent palliative care unit.Method. A prospective descriptive study.Setting. The 7-bed inpatient unit at Sungardens Hospice, Pretoria.Subjects. Patients who required sedation for refractory symptoms in addition to normal palliative care treatment between January and June 2002.Findings. Twenty of 100 consecutive patients admitted required sedation. All had advanced cancer. Their mean age was 68 years. Thirty-six per cent were men and 64% women.Indications. Agitated delirium was the most common reason (45%) for using sedation, followed by intractable vomiting due to inoperable malignant intestinal obstruction in 25% of patients. Three patients with persistent convulsions or myoclonic jerking and 2 patients with severe refractory dyspnoea required some sedation. Intractable pain was the main reason for sedation in only 1 patient.Survival. Mean survival following the start of sedation was 92 hours/3.8 days (range 6 - 369 hours/0.25 - 19.4 days). The combined mean survival recorded in 9 other studies was 57 hours/2.4 days (range 36 - 93.6 hours/1.5 - 3.9 days).Medication. The main drugs used for sedation were midazolam and haloperidol. The mean dosage for midazolam was 18.5 mg/24 hours (range 7.5 - 40 mg) and for haloperidol 8 mg/24 hours (range 5 - 10 mg). For pain relief the mean daily dose of parenteral morphine was 76 mg (range 15 - 260 mg).Conclusion. Use of sedation for the relief of refractory symptoms at Sungardens Hospice is in line with several studies reported in the international literature

    Ocean acidification affects the phyto-zoo plankton trophic transfer efficiency

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    The critical role played by copepods in ocean ecology and biogeochemistry warrants an understanding of how these animals may respond to ocean acidification (OA). Whilst an appreciation of the potential direct effects of OA, due to elevated pCO2, on copepods is improving, little is known about the indirect impacts acting via bottom-up (food quality) effects. We assessed, for the first time, the chronic effects of direct and/or indirect exposures to elevated pCO2 on the behaviour, vital rates, chemical and biochemical stoichiometry of the calanoid copepod Acartia tonsa. Bottom-up effects of elevated pCO2 caused species-specific biochemical changes to the phytoplanktonic feed, which adversely affected copepod population structure and decreased recruitment by 30%. The direct impact of elevated pCO2 caused gender-specific respiratory responses in A.tonsa adults, stimulating an enhanced respiration rate in males (> 2-fold), and a suppressed respiratory response in females when coupled with indirect elevated pCO2 exposures. Under the combined indirect+direct exposure, carbon trophic transfer efficiency from phytoplankton-to-zooplankton declined to < 50% of control populations, with a commensurate decrease in recruitment. For the first time an explicit role was demonstrated for biochemical stoichiometry in shaping copepod trophic dynamics. The altered biochemical composition of the CO2-exposed prey affected the biochemical stoichiometry of the copepods, which could have ramifications for production of higher tropic levels, notably fisheries. Our work indicates that the control of phytoplankton and the support of higher trophic levels involving copepods have clear potential to be adversely affected under future OA scenarios

    What goes in, must come out:combining scat-based molecular diet analysis and quantification of ingested microplastics in a marine top predator

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    Context: Microplastics (plastic particles &lt;5 mm in size) are highly available for ingestion by a wide range of organisms, either through direct consumption or indirectly, via trophic transfer, from prey to predator. The latter is a poorly understood, but potentially major, route of microplastic ingestion for marine top predators.Approach: We developed a novel and effective methodology pipeline to investigate dietary exposure of wild top predators (grey seals; Halichoerus grypus) to microplastics, by combining scat-based molecular techniques with a microplastic isolation method. We employed DNA metabarcoding, a rapid method of biodiversity assessment, to garner detailed information on prey composition from scats, and investigated the potential relationship between diet and microplastic burden.Results: Outcomes of the method development process and results of both diet composition from metabarcoding analysis and detection of microplastics are presented. Importantly, the pipeline performed well and initial results suggest the frequency of microplastics detected in seal scats may be related to the type of prey consumed. Conclusions: Our non-invasive, data rich approach maximises time and resource-efficiency, while minimising costs and sample volumes required for analysis. This pipeline could be used to underpin a much-needed increase in understanding of the relationship between diet composition and rates of microplastic ingestion in high trophic-level species.<br/

    Microplastic Ingestion by Zooplankton

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    Small plastic detritus, termed “microplastics”, are a widespread and ubiquitous contaminant of marine ecosystems across the globe. Ingestion of microplastics by marine biota, including mussels, worms, fish, and seabirds, has been widely reported, but despite their vital ecological role in marine food-webs, the impact of microplastics on zooplankton remains under-researched. Here, we show that microplastics are ingested by, and may impact upon, zooplankton. We used bioimaging techniques to document ingestion, egestion, and adherence of microplastics in a range of zooplankton common to the northeast Atlantic, and employed feeding rate studies to determine the impact of plastic detritus on algal ingestion rates in copepods. Using fluorescence and coherent anti-Stokes Raman scattering (CARS) microscopy we identified that thirteen zooplankton taxa had the capacity to ingest 1.7–30.6 μm polystyrene beads, with uptake varying by taxa, life-stage and bead-size. Post-ingestion, copepods egested faecal pellets laden with microplastics. We further observed microplastics adhered to the external carapace and appendages of exposed zooplankton. Exposure of the copepod Centropages typicus to natural assemblages of algae with and without microplastics showed that 7.3 μm microplastics (>4000 mL–1) significantly decreased algal feeding. Our findings imply that marine microplastic debris can negatively impact upon zooplankton function and health

    Integrating conventional microscopy and molecular analysis to analyse the abundance and distribution of four Calanus congeners in the North Atlantic

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    Analysis of the demographic structure of Calanus species in the North Atlantic presents particular difficulties due to the overlapping spatial distributions of four main congeneric species (Calanus finmarchicus, Calanus helgolandicus, Calanus glacialis and Calanus hyperboreus). These species have similar morphologies, making microscopic discrimination only possible between some of the species at late copepodite or adult stages. However, molecular techniques now offer the possibility of screening significant numbers of specimens and unambiguously identifying them to species, regardless of developmental stage. Unfortunately, the processing rate of specimens by molecular methods is still too low to offer a realistic alternative to microscopy for analysis of samples from large field surveys. Here, we outline and test an approach involving the use of molecular methodology in conjunction with conventional microscopy to assess the species assignment of developmental stage abundances of Calanus congeners. Our study has highlighted many important methodological issues. First, it cannot be assumed that the species composition is homogeneous across the development stages; applying proportional species composition of adults to morphologically undistinguishable earlier development stages can result in error. The second important conclusion is that prosome length may be a highly unreliable discriminator of C. finmarchicus and C. glaciali
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