1,720,960 research outputs found
Fluxes of Methane and Carbon Dioxide from a Subarctic Lake:Seasonality and Significance Within the Landscape
No full textOngoing climate warming is expected to affect the carbon functioning of subarctic ecosystems.Lakes and wetlands, which are common ecosystems of the high northern latitudes, are of utmostinterest in this context because they exchange large amounts of the climate-forcing gasesmethane (CH4) and carbon dioxide (CO2) with the atmosphere. Yet uncertainties in themagnitude and drivers of these fluxes remain, partly due to a lack of direct observations coveringall seasons of the year, but also because of the diversity in measurement methods that often misscomponents of the transport processes. This prevents in particular accurate estimates of the totalemission of CH4 and CO2 from seasonally ice-covered lakes.This thesis aims to address these spatial and temporal issues to improve quantification andunderstanding of surface-atmosphere exchange of CH4 and CO2 by using the eddy covariancemethod. It is a direct, non-intrusive method which allows an integration of all transport pathwaysof the gases between the ecosystem and the atmosphere. The work took place in a peatlandcomplex of Subarctic Sweden where ecosystem functioning is affected by permafrost thaw. Thefocus was on a shallow lake, which was compared to a waterlogged fen within the samecatchment. These two types of ecosystems are commonly present in the subarctic regions andmay expand in poorly drained lowlands as part of ecosystem shifts induced by climate warming.Two and a half years of measurements revealed clear differences between fen and lake in term ofannual flux cycle. While rates of CH4 and CO2 exchange from the fen were highest during thegrowing season and likely controlled by plant processes, lake fluxes of both CH4 and CO2peaked during the short spring season upon lake ice disappearance and subsequent overturn. Thepresence of an ice lid in winter over the lake surface likely prevents gas exchange with theatmosphere and allows buildup of CH4 in the anoxic bottom. Although the contribution of winterand spring to annual emissions of CH4 and CO2 was significant for both ecosystems, springseason emissions were disproportionally important for the lake annual emissions compared to thelength of the period, as it turned the lake from a small summer CO2 sink into an annual source.Annual inter-annual variability was notable in the magnitude of the CH4 spring release and needsfurther investigation.The high temporal resolution of the flux measurements allowed identifying transport pathwaysof CH4 and CO2 between the lake and the atmosphere during spring and summer. Temperature ofthe surface sediments was a main driver of the seasonality in summer ebullition of CH4. A directlink between breakdown of thermal stratification at ice-out and the release of CH4 and CO2 wasestablished. These results underline the crucial importance of shoulder seasons in the annualcarbon emissions from seasonally frozen lakes.Overall, the lake was an important annual source of carbon to the atmosphere, partiallycompensating the higher, annual sink function of the fen. The lake in focus can be seen as atypical shallow postglacial lake with organic rich sediments, thus may be representative of manylakes across the lowlands of the Arctic and subarctic. Comparison with regional estimates ishowever currently limited by the rarity of ecosystem-scale measurements in northern lakes andthe variability of flux estimates across lake types. This work is a step towards a better assessmentof the importance of inland waters in such landscapes.The thesis also addresses challenges and methodological aspects of EC measurements in lakeenvironments, including flux uncertainty and gap filling of fluxes at the hourly scale
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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