1,721,021 research outputs found
14CO for assessing regional CO emissions and tracking the oxidative capacity of the atmosphere
No full textUnderstanding both regional and global carbon cycles is critical for managing urban pollution and mitigating climate change. Radiocarbon in atmospheric carbon monoxide (14CO), primarily produced in the upper atmosphere via cosmic rays, is a valuable but underutilised tracer of regional carbon monoxide (CO) sources and the oxidative capacity of the atmosphere.
This thesis develops novel techniques to utilise 14CO to trace regional CO emissions and global oxidative capacity. Combining regional emissions with an atmospheric dispersion model, we use 14CO to understand CO sources on a regional scale. By 14CO production schemes into a largescale atmospheric model, we investigate its capacity as a tracer species for the hydroxyl radical (OH).
Our regional simulations demonstrate that 14CO can distinguish different CO emissions estimates in the UK and EU. Different emissions schemes show distinct Δ14CO-CO relationships indicating different fuel sources. We outline a measurement campaign that could be used to corroborate the results of our simulation study. Additionally, we provide the measured values necessary to conduct a similar study worldwide.
Our global study incorporated the latest cosmogenic 14CO production model into a global atmospheric model to carry out the first multi-decadal simulations to fully evaluate its capacity to trace the hydroxyl radical (OH). We also integrate secondary production of 14CO into an atmospheric model for the first time, investigating the role they play in surface concentrations.
Our results confirm the utility of 14CO as a tracer on a variety of spatial and temporal scales. This thesis deepens our understanding of 14CO as a tool in atmospheric science, offering unique insights into regional CO emissions and advancing our understanding of OH. It highlights key gaps in our current understanding and proposes novel solutions to address them. These advances are crucial in combating atmospheric pollution and understanding and tackling future climate change
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
Using measurements and modelling of carbon isotopes for evaluating methane emissions and sources in the UK
No full textAtmospheric methane is an important greenhouse gas that is emitted from a diverse range of anthropogenic and natural sources. Quantifying and attributing methane emissions can provide information on the sources that are driving the increases in atmospheric methane concentrations and be used to guide mitigation policies. In this thesis, I use, develop and compare different approaches for attributing specific sources and quantifying emissions of methane in the UK. The work in this thesis uses carbon isotopes of methane and satellite observations of total methane columns (XCH4) from the TROPOSpheric Monitoring Instrument (TROPOMI) between 2018-2020.
Urban areas are hotspots of anthropogenic methane emissions, which are emitted from a number of different sources. I use in situ atmospheric methane and d13CH4 measurements made in central London to demonstrate that continuous measurements from a Picarro isotopic analyser can be used for methane source attribution of large pollution events. These measurements indicated a predominance of fossil methane in central London which was found to be underreported in the UK national emissions inventory. The utility of additional isotopic measurements of atmospheric D14CH4 is explored for the UK by developing a CH4-d13CH4-D14CH4
framework and using pseudo-data simulations. Pseudo-data indicate additional isotopic measurements of D14CH4 could improve the UK's methane source apportionment. A first analysis of TROPOMI methane measurements for the UK is also conducted. I conclude that TROPOMI XCH4 retrievals from 2018-2020 are not useful for informing on UK methane emissions and spatial variations due, in part, to the low data availability for the UK over this period.
My findings indicate that ground-based atmospheric measurements are more useful for constraining sector specific methane emissions and informing on regional differences than TROPOMI measurements for the UK. Whilst d13CH4 measurements are found to be valuable for source attribution, additional measurements of atmospheric D14CH4 could be used to improve the methane source constraint for the UK.Open Acces
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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