1,720,955 research outputs found
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
Species and Sex Related Differences in Antioxidant Enzymes in Fish Collected From Umguza and Auchmacoy Wright Dams, Bulawayo, Zimbabwe.
No full textPresented in October 2002.,Agricultural and industrial activity results in the pollution of our environment by pesticides and metals usually causing deleterious effects on both humans and other animals in the environment. We are interested in the effects of pesticides and metals on non-human targets, such as fish, in the environment. Literature reports suggest that there are species and sex differences amongst fish in the metabolism of foreign compounds (xenobiotics) on the detoxifying enzymes of aquatic organisms. The aim of this study was to assess whether there are any species and sex differences in antioxidant enzyme activities of local fish. Catfish (Clarius gariepinus) and bream (Oreochromis mossambicus) collected from two dams, one polluted (Umguza) and one pristine (Auchmacoy Wright) in the Bulawayo area. Gills, liver and kidneys from captured (gill netted) fish were excised, homogenized and centrifuged to obtain S-9 fractions. The S-9 fraction was used to assay for activities of the antioxidant enzymes, catalase, glutathione peroxidase and DT- diaphorase. Significant sex-related differences in the activity of catalase in liver and gill but not in kidney of catfish collected from Umguza Dam were noted (Student t test, P< 0.05). No sex-related differences in catalase activity were observed in bream tissues collected from Umguza Dam. Catalase activity in female bream collected from Umguza Dam was/significantly higher when compared to female catfish catalase from the same dam. Glutathione peroxidase activity in catfish collected from Umguza Dam were Seen to be sex dependent in gill and liver but not in kidney (Student t test, P < 0.05) whilst species differences were noted only in liver, with higher activities in catfish. Umguza bream showed significant sex differences in glutathione peroxidase activity onfy in the gills. DT- diaphorase activity in catfish collected from Umguza Dam was shown to be sex dependent in gill and kidney but not in liver. In Umguza bream, DT-diaphorase activity was seen to be sex dependent only in gills. Species differences in DT-diaphorase activity were only seen when male catfish and male bream were compared. DT-diaphorase activity was shown to be significantly higher in male catfish compared to male bream but there were no differences in activity when female catfish were compared to female bream in all the tissues. For fish collected from Auchmacoy Wright Dam, significant differences in bream catalase activity was seen in all the three tissues studied. Species difference in catalase activity were noted in liver and gill but not in kidney. Significant sex differences in the activity of glutathione peroxidase were noted only in the kidneys of the bream. Species differences in glutathione peroxidase activity were noted only in the gills of female fish. No significant diffe.rences in DT-diaphorase activity either by sex or species were noted in all the tissues of fish collected from Auchmacoy Wright
Dam. Our data indicates that enzyme activity is species, sex and tissue dependent in fish and that enzyme activity is also affected by the presence of pollutants.,Biochemistry and Molecular Biology Society of Zimbabw
Esterase Activity of Two Aquatic Snail Species Helisoma Duryi And Lymnaea Natalensis
No full textA paper presented on Research Day on 27th October 2000, hosted by the Biochemistry and Molecular Biology Society of Zimbabwe.,Previous work has shown that inhibition of esterase activity is likely to be a useful parafrieter to develop as a biomarker of organophosphate pollutants. We have extended our preliminary study and have now tested for esterase activity with two new substrates (five in total) while measuring the esterase activity in a newly established colony of the aquatic snails Lymnaea natalensis and Helisoma duryi. Post mitochondrial fractions prepared from whole body homogenates were used to measure esterase activity with the following 5 substrates: p-nitrophenyl acetate ( PNPA), (-naphthyl acetate (ANA), phenyl acetate (pHA), carboxylic esterase activity and acetylthiocholine iodide (Ach!) and S-butyrylthiocholine iodide (BthI) cholinesterase activity. Our data shows that the carboxylic esterase (CbE) activity measured in our new stock of snails was decreased (depending on the substrate used a range from 30% to 50%) compared to values obtained previously. Since the cholinesterase (ChE) activity was measured for the first time in these two species a comparison could not be made. In general, the esterase activity was found to be slightly higher in H. duryi than in
L.natalensis. The reasons for the altered activity in the new snail colony is not clear but nutrient and climatic factors are likely to be responsible.,Biochemistry and Molecular Biology Society of Zimbabw
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
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