1,720,979 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Mutagenicity in surface waters : a comprehensive approach to unravel the role of aromatic amines
No full textSurface waters are under constant pressure of numerous chemicals causing a prominent threat for aquatic and human health. Mutagenicity is one of the most frequently observed adverse effects in aquatic environments. Although findings show that aromatic amines are major contributors, so far no individual mutagens were identified raising the question whether unknown individual chemicals or complex mixtures of aromatic amines may be regarded as drivers of this effect.This thesis aimed to develop and apply a comprehensive approach to unravel the surface water mutagenicity with a focus on aromatic amines which is one of the most important class of compounds due to their high production volumes, extensive use in daily life and many of them being known or suspected mutagens. In Chapter 2, a post-column and a pre-column derivatization method to label aromatic amines with liquid chromatography - high resolution mass spectrometry (LC-HRMS) were evaluated to facilitate the detection of aromatic amines in complex environmental matrices. Different derivatization reagents were utilized under various temperature and pH conditions and time constraints to optimize the method. Pre-column derivatization with 4-Fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was found to be the optimum approach yielding sufficient derivative signal intensities and derivatives showed common fragments of diagnostic value. The high reactivity of NBD-F resulted in the derivatization of not only primary and secondary aromatic amines but also thiols, aliphatic amines and nitrogen containing heterocyclic compounds. The developed method was successfully applied as a peak prioritization step to six mutagenic wastewater samples collected with Blue Rayon from the area Bitterfeld-Wolfen and several derivatives were confirmed by diagnostic neutral losses.The selected peaks with confirmed derivatives were subjected to a compound identification process in Chapter 3. Two complementary analytical methods namely hydrogen-deuterium exchange and ph-dependent LC retention were applied in order to facilitate candidate selection and identification of aromatic amines. As a result of the applied workflow, 14 amines were identified including two potent mutagenic aromatic amines 2,3- and 2,8-phenazinediamines that were found as major contributors to the detected mutagenicity of the wastewater samples. The dye industry in the area was found to be the possible source for the generation of diaminophenazines as a transformation product.In Chapter 4, a full EDA study was compiled to unravel the contribution of aromatic amines to the long term observed mutagenicity in River Rhine. The developed derivatization method was applied to active fractions which were selected based on the results of the diagnostic strain YG1024. In addition to the complementary LC methods, the candidate selection was supported by two prediction models namely nitrenium and TIMES model. Twenty one compounds from different classes were identified including two aromatic amines and three carboline alkaloids, one being the known co-mutagen norharman. Although none of the identified compounds showed any response individually or in mixtures without aromatic amines, the mixtures of aromatic amines with carbolines showed strong synergistic effects which were increased even more in the presence of other nonmutagenic nitrogen containing compounds. In the presented PhD thesis, a comprehensive approach was developed and applied combining biological, chemical and prediction tools in order to unveil the role of aromatic amines on the observed surface water mutagenicity. It is demonstrated that aromatic amines are key mutagens in surface waters either as individual mutagens or as drivers of mixture effects together with natural compounds. These findings point at the importance of monitoring aromatic amines and offer new insights to unravel surface water mutagenicity by considering synergistic effects of not only mutagens alone but also possible comutagens and nonmutagenic compounds
Atık biyolojik çamurların ozonla muamelesi ve sentetik organik kirleticilerin arıtılması.
No full textA novel ozone-assisted aerobic sludge digestion process to stabilize and decrease the amount of excess sludge produced during biological treatment is presented in this study. Excess sludge production is a well known burden for the treatment plants both legally and financially. Moreover, with the arise in the knowledge in recalcitrant compounds it is understood that it can act as a significant secondary pollutant. With the developed pulse ozonation method, waste activated sludge samples from Ankara Tatlar and other Wastewater Treatment Plants (WWTP) were ozonated for different periods in Erlenmeyer flasks once a day on each of four consecutive days. Flasks were continuously aerated between ozone applications on an orbital shaker. The MLVSS, MLSS, COD and OUR parameters were measured routinely during the course of four days of digestion in order to optimize the process. Also pH, CST(capillary suction time) and SVI (sludge volume index) were followed. As a result MLVSS reductions of up to 95% were achieved with an ozone dose of only 0.0056 kg O3/kg-initial MLSS, at the end of the fourth day. In another experimental set, ozone dose was increased on the last day in order to destroy the selected endocrine disrupting compounds, namely diltiazem, carbamazepine, butyl benzyl phthalate and acetaminophen and two natural hormones estrone and progesterone, which accumulated onto the sludge. Over 99% removal of these contaminants were achieved on the fourth day. The analyses were conducted by using LC(ESI) MS/MS after solid phase extraction (SPE). By this process it became possible to save on contact time, as well as achieving a bio-solids digestion far exceeding the standard aerobic process at the expense of a minimum of ozone dose with the additional micropollutants removal. The developed process is deemed superior over side-stream ozonation of activated sludge in that it does not cause any reduction in active biomass amount that should be maintained in the aeration tank.M.S. - Master of Scienc
Variations on the Author
No full text“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
No full textWe 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
No full textWe 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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