1,720,954 research outputs found
Integration of physicochemical assessment of water quality with remote sensing techniques for the Dikgathong Damin Botswana.
No full textWater quality has become a global concern due to ever increasing population and developmental activities that are polluting water resources. Botswana’s water resources are threatened by various pollution sources such as agricultural runoff, industrial and domestic effluents.This study was carried out to assess the water quality of Dikgathong Dam in Botswana using physicochemical analysis of water quality parameters and remote sensing techniques.The study first assessed landuse patternsbefore construction (2010) and after construction (2015) to establish dominant landuse inorder to select water quality parameters related to the principal landuse in the catchment. Images for 2010 and 2015 were acquired from Landsat and were classified using the supervised classification through the Maximum Likelihood algorithm. Results showed that forest and shrubs were the dominant landuse covering 73.7 % of the total area, followed by settlements (21.1 %) and agricultural fields (2.76 %).Chl_a, COD, EC, TP, TN, TSS, NO3 and NO2 were selected for testing and analysis based on their relationship with forest, settlements and agricultural fields.For assessment of water quality, ten points were sampled in the dam from 15th January to 07th April 2016. Temperature,pH, EC, COD, TDS, TSS, turbidity, chloride, nitrates, sodium, potassium, calcium, magnesium, sulphates, phosphates, total phosphorus, alkalinity, hardness and algae were tested and analysedaccording to standard methods. Only COD, turbidity and TSSexceededthe limits set by Environmental Protection Agency (EPA)surface water standards of 2001, making Dikgathong Dam slightly polluted.One way ANOVA showed significant variations (p<0.05) between water quality values in all sampling points only for NO3, SO4, pH, algae and Na. Five different groups of sites were identified from ten sites using cluster analysis.The principal component analysis identified ten parameters (COD, EC, turbidity, TSS, Ca, Mg, NO3, SO4, total hardness and alkalinity)based on similarities of water quality characteristics. The Water Utilities Corporation, which is responsible for the dam,can therefore monitor water quality at five points focusing mainly on ten parametersfound to be principal. This study also investigated the likelihood of integrating remote sensing and in-situ measurements to assess the water quality status of the dam. Quasi analytical algorithms andMODIS datawere used to quantify Chl_aand TSS concentrations in the dam. Values forChl_awerebetween 1.74and 24.4 mg/m3, whileTSS ranged from 2.34 mg/l to 59.2 mg/l. Based on chlorophyll concentrations thedam can be classified as both oligotrophic and mesotrophic as per the EPA 2001 standard.The QAA and MODIS can therefore be deployed as a mechanism for near real time monitoring of water quality in Botswana reservoirs.Spearman’s correlation was used to test whether satellite retrieved water quality parameters relate to in-situ measurements.Strong positive significant correlation was observed between chl_a and turbidity (r=0.794 and 0.830), TSS (r = 0.819 and 0.770), SO4 COD (r=0.781 and 0.769).), SO4 (r= 0.851 and 0.646) and alkalinity (r= 0.847). Moderate positive and non-significant relationship is observed for temp (r= 0.055), pH (r= 0.587), EC (r= 0.409), TDS (r=0.348), Na (r= 0.406) and Cl (r= 0.394).Strong positive and significant correlation was observed between remote sensing retrieved TSSand in-situ measured TSS (r= 0.733) andturbidity (r= 0.867).This study concludes that there is strong positive correlation between parameters retrieved through remote sensing and in-situ measurements and therefore can be used in monitoring and assessment of the water quality in the lake at any point in time.WaterNe
Integration of physicochemical assessment of water quality with remote sensing techniques for the Dikgathong Damin Botswana.
No full textWater quality has become a global concern due to ever increasing population and developmental activities that are polluting water resources. Botswana’s water resources are threatened by various pollution sources such as agricultural runoff, industrial and domestic effluents.This study was carried out to assess the water quality of Dikgathong Dam in Botswana using physicochemical analysis of water quality parameters and remote sensing techniques.The study first assessed landuse patternsbefore construction (2010) and after construction (2015) to establish dominant landuse inorder to select water quality parameters related to the principal landuse in the catchment. Images for 2010 and 2015 were acquired from Landsat and were classified using the supervised classification through the Maximum Likelihood algorithm. Results showed that forest and shrubs were the dominant landuse covering 73.7 % of the total area, followed by settlements (21.1 %) and agricultural fields (2.76 %).Chl_a, COD, EC, TP, TN, TSS, NO3 and NO2 were selected for testing and analysis based on their relationship with forest, settlements and agricultural fields.For assessment of water quality, ten points were sampled in the dam from 15th January to 07th April 2016. Temperature,pH, EC, COD, TDS, TSS, turbidity, chloride, nitrates, sodium, potassium, calcium, magnesium, sulphates, phosphates, total phosphorus, alkalinity, hardness and algae were tested and analysedaccording to standard methods. Only COD, turbidity and TSSexceededthe limits set by Environmental Protection Agency (EPA)surface water standards of 2001, making Dikgathong Dam slightly polluted.One way ANOVA showed significant variations (p<0.05) between water quality values in all sampling points only for NO3, SO4, pH, algae and Na. Five different groups of sites were identified from ten sites using cluster analysis.The principal component analysis identified ten parameters (COD, EC, turbidity, TSS, Ca, Mg, NO3, SO4, total hardness and alkalinity)based on similarities of water quality characteristics. The Water Utilities Corporation, which is responsible for the dam,can therefore monitor water quality at five points focusing mainly on ten parametersfound to be principal. This study also investigated the likelihood of integrating remote sensing and in-situ measurements to assess the water quality status of the dam. Quasi analytical algorithms andMODIS datawere used to quantify Chl_aand TSS concentrations in the dam. Values forChl_awerebetween 1.74and 24.4 mg/m3, whileTSS ranged from 2.34 mg/l to 59.2 mg/l. Based on chlorophyll concentrations thedam can be classified as both oligotrophic and mesotrophic as per the EPA 2001 standard.The QAA and MODIS can therefore be deployed as a mechanism for near real time monitoring of water quality in Botswana reservoirs.Spearman’s correlation was used to test whether satellite retrieved water quality parameters relate to in-situ measurements.Strong positive significant correlation was observed between chl_a and turbidity (r=0.794 and 0.830), TSS (r = 0.819 and 0.770), SO4 COD (r=0.781 and 0.769).), SO4 (r= 0.851 and 0.646) and alkalinity (r= 0.847). Moderate positive and non-significant relationship is observed for temp (r= 0.055), pH (r= 0.587), EC (r= 0.409), TDS (r=0.348), Na (r= 0.406) and Cl (r= 0.394).Strong positive and significant correlation was observed between remote sensing retrieved TSSand in-situ measured TSS (r= 0.733) andturbidity (r= 0.867).This study concludes that there is strong positive correlation between parameters retrieved through remote sensing and in-situ measurements and therefore can be used in monitoring and assessment of the water quality in the lake at any point in time.,WaterNe
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
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