1,720,953 research outputs found
Macroinvertebrates associated with seagrass at point-source pollutant inputs in the Knysna Estuary
Full text linkEstuaries are important ecosystems that provide many functions, including filtering nutrients and other contaminants from surrounding catchments before they reach the ocean. These services are provided by habitats such as seagrasses. Increasing anthropogenic pressures and development threaten the integrity of such coastal ecosystems. Nutrient enrichment or eutrophication affects seagrass habitats globally, causing ecosystem degradation and loss of ecological and economic value. Nutrient enrichment can induce various changes to both the floral and faunal communities within estuarine environments. These effects include the proliferation of opportunistic algae and shifts in macroinvertebrate community structure from sensitive to resilient taxa. The aim of this study was to investigate the drivers and responses of Zostera capensis and the macroinvertebrates dwelling within its rhizosphere, to nutrient pollution at the Knysna Estuary, South Africa. This was achieved by quantifying seagrass metrics, sediment characteristics and macroinvertebrate indices at six polluted sites (referred to as point-sources) along the Knysna Estuary. Sampling was carried out quarterly from May 2023 to January 2024. Direct indices of nutrient pollution were measured as nutrient concentrations (N and P) in seagrass tissue of above- and belowground biomass, the overlying water column as well as in epiphytic tissue. A nutrient gradient was determined across the point-sources. Sites sheltered from wave action were more nutrient enriched than exposed sites, reflecting their depositional nature. Bongani River (which is linked to a wastewater treatment works) was identified as the most polluted site, however, δ15N isotopic signatures in Z. capensis leaves were not consistently indicative of enrichment. This could be related to seasonal trade-offs of nutrient requirements or poorly primary treated wastewater resulting in depleted δ15N signals (mean of 1.76 ± 4.65 ‰). Featherbed, which is an exposed site, was the least polluted. Seagrass metrics did not increase in response to high nutrient concentrations but rather a decrease in above- and belowground biomass was observed. This could be linked to long-term enrichment with nutrient levels exceeding plant growth needs, leading to reduced growth from direct effects such as NH4 + growth suppressant, or secondary effects such as overgrowth from other primary producers or sediment anoxia. Nutrient storage (N and P) in Z. capensis above- and belowground biomass did not differ overall. Epiphyte biomass increased in response to high nutrient concentrations and demonstrated a high nutrient storage capacity, suggesting that epiphytes responded more rapidly to nutrient enrichment. The highest epiphyte biomass was recorded at Bongani (61.6 ± 28.87 mg m-2), while Featherbed had the lowest (21.71 ± 21.63 mg m-2) epiphyte biomass. Nutrient enrichment effected a change in site-specific community composition of macroinvertebrates associated with the rhizosphere sediment. The dominance of general pollution-tolerant groups such as clitellates and polychaetes and the low abundance of pollution-sensitive groups such as burrowing amphipods was observed at Bongani compared to other sites. The Benthic Opportunistic Annelids Amphipods (BO2A) index highlighted the poor ecological status of Bongani and the comparatively less polluted conditions at Featherbed. Regression modelling suggested that sediment characteristics such as redox was the dominant driver of macroinvertebrate responses (abundance, richness and diversity). A well oxygenated habitat is a crucial metabolic requirement forvfauna. A higher sediment redox potential indicating aerobic conditions reflected higher macroinvertebrate abundance and richness. The rhizosphere sediment was predominantlyvsilty (2.8 ± 1.29 μm). Sandier sediment was negatively related to species richness andvsediment with higher clay content was negatively related to polychaete abundance. Thesevresults suggested that indirect effects of increasing organic matter and nutrient loading linked to sediment type can increase oxygen consumption, lowering redox potential whichvcollectively negatively affects the benthic fauna.vDeteriorating water quality is becoming more prevalent in South Africa and worldwide.vMonitoring effluent flows and the effects it has on water resources is vital to combatvpollution. This study showed that different indicators of nutrient enrichment such asvseagrass, macroinvertebrates and epiphytes can be effectively used in studies investigating pollution impacts on coastal environments. Although seagrass habitats have been shown tovimprove water quality through storage and filtering capacity, efforts should steer towardsvreducing excess nutrient input received from catchments. This is especially true in sensitivevareas where seagrass is exposed to long-term nutrient enrichment. Many studies have experimentally tested enrichment effects across various timeframes. However, more in-situvinvestigations should be conducted to assess combined seagrass and macroinvertebratevresponses to eutrophic conditions. This is necessary to protect the ecological functionsvprovided by these components which are intrinsically linked.Thesis (MSc) -- Faculty of Science, Life, Earth, Environmental & Agricultural Sciences Cluster, 202
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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