1,720,960 research outputs found
The implications of the Paris Agreement on carbon dioxide removal (CDR) - techno-economics, potential, efficiency and permanence of CDR pathways
Get PDFTackling the many unprecedented changes observed in the climate requires immediate and deep mitigation efforts, including carbon dioxide removal (CDR). Despite the many different CDR methods proposed in the literature, it is still unclear how, where, and when carbon dioxide (CO2) removal will be deployed in a sustainable, feasible, and efficient manner. Owing to uncertainties about their CO2 removal and scale-up potentials, concerns about their environmental impacts and their competition for bio-geophysical resources, and their socio-economic challenges, the deployment of CDR at scales that are consistent with the Paris Agreement’s 1.5°C objectives is controversial. This thesis investigates the spatio-temporal deployment of portfolios of archetypal CDR technologies and practices — namely afforestation/reforestation, bioenergy with carbon capture and storage (BECCS), biochar, direct air capture of CO2 with storage (DACCS), and enhanced weathering (EW) —, and seeks to provide insights into their techno-economics, potential, efficiency and permanence. We find that the conditions under which CO2 is removed from the atmosphere in an efficient, timely, and permanent manner vary highly across the different CDR methods. Consequently, their roles and values, when deployed to deliver the Paris Agreement’s 1.5°C objectives, also vary with the region and time of deployment. Additionally, international/inter-regional cooperation is emphasised to deploy CDR most cost-efficiently and equitably — by allowing regions well-endowed with CDR potential to trade CDR surplus with regions for which delivering CDR is more difficult, or more costly. However, such cooperation needs to be implemented as immediately as possible to prevent from greater costs, carried mostly by future generations. Importantly, international/inter-regional markets for negative emissions trading are shown to be of important economic value, not only for beneficiaries of CDR, but also for providers. Finally, we find that time preference — the choice of time horizon for defining permanence — in CDR accounting methods impacts the portfolio of CDR methods deployed, with short-term methods favouring the deployment of temporary CDR methods, more affordable but also more liable to the risks of CO2 re-release/non-permanence, and with long-term methods favouring permanent CDR methods, less risky but more expensive.Open Acces
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
CO2 removal and 1.5 °C: what, when, where, and how?
Get PDFThe international community aims to limit global warming to 1.5 °C, but little progress has been made towards a global, cost-efficient, and fair climate mitigation plan to deploy carbon dioxide removal (CDR) at the Paris Agreement's scale. Here, we investigate how different CDR options—afforestation/reforestation (AR), bioenergy with carbon capture and storage (BECCS), and direct air carbon capture and storage (DACCS)—might be deployed to meet the Paris Agreement's CDR objectives. We find that international cooperation in climate mitigation policy is key for deploying the most cost-efficient CDR pathway—comprised of BECCS, mainly (74%), and AR (26%)—, allowing to take the most advantage of regional bio-geophysical resources and socio-economic factors, and time variations, and therefore minimising costs. Importantly, with international cooperation, the spatio-temporal evolution of the CDR pathway differs greatly from the regional allocation of the Paris Agreement's CDR objectives—based on responsibility for climate change, here used as a proxy for their socio-economically fair distribution. With limited, or no international cooperation, we find that the likelihood of delivering these CDR objectives decreases, as deploying CDR pathways becomes significantly more challenging and costly. Key domestic bio-geophysical resources include geological CO2 sinks, of which the absence or the current lack of identification undermines the feasibility of the Paris Agreement's CDR objectives, and land and biomass supply, of which the limited availability makes them more costly—particularly when leading to the deployment of DACCS. Moreover, we show that developing international/inter-regional cooperation policy instruments—such as an international market for negative emissions trading—can deliver, simultaneously, cost-efficient and equitable CDR at the Paris Agreement's scale, by incentivising participating nations to meet their share of the Paris Agreement's CDR objectives, whilst making up for the uneven distribution of CDR potentials across the world. Crucially, we conclude that international cooperation—cooperation policy instruments, but also robust institutions to monitor, verify and accredit their efficiency and equity—is imperative, as soon as possible, to preserve the feasibility and sustainability of future CDR pathways, and ensure that future generations do not bear the burden, increasingly costlier, of climate mitigation inaction
Investigating the BECCS resource nexus: delivering sustainable negative emissions
Get PDFBioenergy with carbon capture and storage (BECCS), and other negative emissions technologies (NETs), are integral to all scenarios consistent with meeting global climate ambitions. BECCS's ability to promptly remove CO2 from the atmosphere in a resource efficient manner, whilst being a net energy generator to the global economy, remains controversial. Given the large range of potential outcomes, it is crucial to understand how, if at all, this technology can be deployed in a way which minimises its impact on natural resources and ecosystems, while maximising both carbon removal and power generation. In this study, we present a series of thought experiments, using the Modelling and Optimisation of Negative Emissions Technologies (MONET) framework, to provide insight into the combinations of biomass feedstock, origin, land type, and transport route, to meet a given CO2 removal target. The optimal structure of an international BECCS supply chain was found to vary both quantitatively and qualitatively as the focus shifted from conserving water, land or biomass, to maximising energy generated, with the water use in particular increasing threefold in the land and biomass use minimisation scenario, as compared to the water minimisation scenario. In meeting regional targets, imported biomass was consistently chosen over indigenous biomass in the land and water minimisation scenarios, confirming the dominance of factors such as yield, electricity grid carbon intensity, and precipitation, over transport distance. A pareto-front analysis was performed and, in addition to highlighting the strong trade-offs between BECCS resource efficiency objectives, indicated the potential for tipping points. An analysis of the sensitivity to the availability of marginal land and agricultural residues showed that (1) the availability of agricultural residues had a great impact on BECCS land, and that (2) water use and land use change, two critical sustainability indicators for BECCS, were negatively correlated. Finally, we showed that maximising energy production increased water use and land use fivefold, and land use change by two orders of magnitude. It is therefore likely that an exclusive focus on energy generation and CO2 removal can result in negative consequences for the broader environment. In spite of these strong trade-offs however, it was found that BECCS could meet its electricity production objective without compromising estimated safe land use boundaries. Provided that the right choices are made along BECCS value chain, BECCS can be deployed in a way that both satisfies its resource efficiency and technical performance objectives
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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