1,720,953 research outputs found
Nitrogen fixation may provide a significant yet under quantified source of Nitrogen in the Great Lakes
No full textNitrogen fixation (NFix) is an important yet understudied microbial process in aquatic ecosystems and especially in the Laurentian Great Lakes (LGL). Early work suggested the contribution of NFix in the LGL is minimal to the nitrogen budget. However, recent work has shown during bloom events, NFix can help alleviate nitrogen limitations. Thus, we sought to revisit NFix in the LGL and comprehensively sample from near and offshore stations and with depth to understand the spatial variability of NFix.
Nitrogen fixation rates were quantified using an adapted acetylene reduction assay (Stewart et al. 1967; doi:doi:10.1073/pnas.58.5.2071). Water samples were collected from discrete depths (Table 1) using a CTD-rosette water sampler equipped with 12 - 8L Niskin bottles and outfitted with a Sea-Bird multi-parameter profiler (conductivity, temperature and depth). Two liters of water were collected in triplicate from each depth and concentrated onto a 0.22µm pore size MF- Millipore Membrane filter using a vacuum manifold at low pressures to minimize cell breakage. Given the vast difference in lake depths between lakes and even within lakes, at each sampling station we took three depths, a surface (5m) sample (constant at all stations), mid- water column (based on max station depth) and near-bottom water (5m from bottom) (SI Table 1). The mid-water collection did not necessarily coincide with the thermocline, if it was even present. In preliminary testing in Lake Superior, we determined that approximately 2L of water was necessary to capture enough biomass to quantify rates in oligotrophic waters. In areas of high biomass, such as Lake Erie, water was filtered until the filter was clogged, which were all below 1L. Filtrate volume was noted, and final nitrogen fixation values were corrected based on volume filtered. Following filtration, filters were transferred to 50mL serum vials, submerged in 25mL of filtrate (lake water) from the same depth it originated from, and capped with a Teflon stopper. Acetylene gas was generated shipboard prior to sampling by combing 1g calcium carbide (CaC2) and 100ml of deionized water in a side arm flask attached to a 1L Tedlar gas sampling bag (EnviroSupply & Service). Samples were spiked with 1mL of acetylene gas and incubated at near in situ conditions (temperature and light) in the lab for 24 hours. For deep samples, incubations were done in the dark. After 24 hours, the incubations were terminated using 5mL of trichloroacetic acid (TCA) and stored in the dark at 4°C until measurements could be made in the lab. Acetylene gas concentration (peak area integration) was measured using an Agilent 6890 Plus GC System equipped with a flame deionized detector (FID) and a GS-Carbon Plot column 100/120 mesh (Agilent 113-3122). The GC-FID parameters are as follows: the carrier gas He2 was set at a flow rate of 30cm/s, the oven temperature was held isothermally at 125°C for 3 minutes, with an a split injection of 1:20 at 250°C. Sample injection volumes were 100 µL taken from the headspace of the vial. The retention times for acetylene and ethylene were observed at 1.8 and 1.9 minutes, respectively. For each station and at each depth, the following series of blanks and controls were used: 1) kill standard, 2) acetylene + DI water 3) acetylene + filtrate. Peak area integrations were calculated at retention times 1.9, and a correction ratio of 1:4 of N2 fixed to ethylene formed were factored in to determine molar N2 fixation rates (nmol/L/day) (Peterson and Burris 1976; doi:10.1016/0003-2697(76)90187-1)
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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