1,720,953 research outputs found
Geohydrological modelling to determine cumulative impact on groundwater at the Letšeng Diamond Mine, Lesotho
No full textDissertation (M.Sc.(Geohydrology))--University of the Free State, 2023Letšeng diamond mine (LDM) uses the split-shell open-pit mining method. The method includes excavation from the surface to access the ore at depth. Material from excavation and that separated during diamond extraction form primary mine waste. Approximately 20 million tonnes of waste is produced as fine-grained waste deposited into Tailings Storage Facilities (TSF) and coarse-grained waste deposited onto Waste Rock Dumps (WRDs). The waste can contain toxic chemical substances that can seep into groundwater or flow into surface water, contaminating it. For this reason, the study aims to determine the cumulative impacts of mining on groundwater quality. To achieve this, groundwater modelling techniques were employed to simulate groundwater flow and groundwater travel times and travel paths for contaminant transport.
Geological, hydrological, hydrogeological and hydrochemical data were collected, analysed, and integrated to conceptualise the hydrogeology of LDM to provide a better understanding of the hydrogeological system. The conceptual model also indicated possible sources of contamination and their possible receptors incorporating the Source Pathway Receptor concept. This was achieved by collecting and analysing the water quality data. Mine water sampling results show that most constituents are within the acceptable limits, while nitrates and sulphates were elevated above limits at locations down gradient from the Old Slimes Dam, WRDs and Patiseng TSF suggesting these areas are potential on-site sources of contamination.
The conceptual model formed the basis of the groundwater model. Based on the prevailing hydrogeological conditions in the mining area, a groundwater flow model was developed using MODFLOW 6. Due to data limitations, instead of simulating the contaminant from the source to the receptor using transport modelling, particle tracking with MODPATH was used to simulate the pathway and travel time of contaminants in groundwater. Particle tracking results show that the simulated extent of contaminant movement is generally in line with the water quality sampling results, where sampling points beyond the mine lease areas show acceptable water quality as opposed to samples closer to potential sources which show elevated levels of contamination, suggesting contamination is mostly contained within the mine lease area. Similarly, MODPATH results indicate that most particles do not exceed the lease area, also indicating that contamination from potential sources is mostly limited within the mine lease area.
Over a five-year simulation period, there is very limited movement of contaminants, although some particles from the Old Slimes Dam are released into the Mothusi Dam, thus posing a risk on its quality. Based on these findings, the Dam was identified as the most sensitive receptor. Over a 10-year period, there is further movement of particles, and some start to move beyond the lease area as some boreholes start showing increased nitrate concentrations such as borehole L_WE_010 down-gradient from the WRD east, suggesting groundwater contamination from the WRD. Over 20 years, a maximum travel distance of 5 km from the eastern WRD is observed, however no sensitive receptor was reached. While the calculated extent of the cumulative migration from the Old Slimes Dam is contained on- site over the 20 years, there is potential impact on the quality of groundwater as some particles intercept the boreholes downstream of the Mothusi Dam, borehole L_WE_015 and borehole L_WE_016. More boreholes are also intercepted over the 20 years.
Over time, contaminants will migrate off-site into the weathered shallow layer through the streams therefore reaching some of the receptors in the surrounding environment, either by percolation or conveyed as surface contaminants into the weathered layer. Due to low hydraulic conductivity in the types of rocks in the area, the migration of contaminates is very slow and is mostly limited within the first layer. The results show that there is some seepage of contaminants from potential sources, mostly affecting surface water compared to groundwater. However, the groundwater modelling results also indicate that over long-term evaluations, mining activities at LDM have significant impacts on the groundwater quality, where contaminant particles from different sources are observed at monitoring boreholes suggesting groundwater contamination.
This study clarifies the slow but significant effects of mining operations on groundwater and surface water resources over time at Letšeng diamond mine. The results highlight the need for ongoing monitoring and mitigation measures to reduce cumulative effects on vulnerable receptors including the Khubelu, Qaqa Rivers and Mothusi Dam. The conclusion of this assessment emphasizes the critical need for ongoing environmental management within mining practices to protect the quality of nearby water resources. This is achieved by addressing the sources and pathways of contamination that have been identified, putting in place rigorous monitoring, and strengthening mitigation measures
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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