1,721,010 research outputs found
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
Bacteria & prophage distributions along an estuarine salinity gradient
No full textEstuaries are highly productive systems that contain complex aquatic microbial communities, with gradients of salinity and nutrients between the fresh water and marine environments. The estuarine bacterial community plays a very important role in processes such as nutrient cycling and primary production. There are many factors that cause stress on bacterial populations notably, fluctuating nutrients and salinities (due to tidal mixing) and predation from viruses. Both the salinity gradient and virus predation have shown to be major stresses and drivers of change in bacterial populations. This study has generated a taxonomically and genetically diverse culture collection of bacterial isolates which has enabled us to assess the distribution of bacteria and prophage across an estuarine salinity gradient. This study has shown that some estuarine bacteria have broad salinity tolerances and therefore are likely capable of being established across multiple zones in the estuarine environment, likely as a result of evolving certain osmoregulation strategies in response to the salt stress. This study has also found that 70% of the bacteria (genomically characterised in our study) are prophage carriers and are therefore under lysogenic stress, suggesting there are high proportions of prophage carriers in estuarine bacterial populations. We have examined the likely possibility that some of these phage have become inactivated and cryptic and highlighted the evolutionary importance of cryptic phage in relation to the phage-host arms race. Overall, this study has added valuable information to our understanding of factors that can influence the community structure and functioning of the microbiology of estuarine ecosystems
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Microbial nitrogen-cycling and cooperation in the terrestrial subsurface
No full textThe microbial nitrogen cycle is predicted to play a major role in nitrogen transformations in the terrestrial subsurface. The cycle comprises six distinct biological N-transformation processes, including ammonification, nitrogen fixation, nitrification, denitrification, anaerobic ammonium oxidation (anammox), and assimilation. The microorganisms that perform these processes can be sources and sinks of nitrate – a major anthropogenic contaminant of aquifers. Therefore, it is crucial that we understand how natural and anthropogenic driven variation in aquifers impacts the microbial communities and their functional contributions, including nitrogen removal. To determine the distribution and activity of nitrogen cycling microorganisms in aquifers, this thesis applied a variety of molecular approaches to groundwater samples collected across a range of aquifer lithologies and physicochemistries. Groundwater with varying nutrient and oxygen contents was sampled from 55 sites distributed over 860 km2 of New Zealand. Metagenomes and metatranscriptomes were analysed from a subset of oxic and dysoxic sandy-gravel aquifer sites, and genes/transcripts involved in major nitrogen-cycling pathways were quantified from 55 and 26 sites, respectively. Data indicate that non-assimilatory nitrogen-cycling (ammonia oxidation, nitrate, nitrite and nitric oxide reduction and denitrification) potential was prevalent regardless of site-specific physicochemistry, but pathway relative abundances differed. Anammox helps to drive N loss from aquatic systems, and is expected to be associated with low oxygen and carbon availability. While anammox-associated bacteria (class Brocadiae) diversity decreased with increasing dissolved oxygen in groundwater, Brocadiae 16S rRNA genes and hydrazine synthase (hydrazine synthase, hzsB) genes and transcripts, which are indicative of the anammox process, were detected across a wide range of bulk groundwater dissolved oxygen (DO) concentrations (0–10 mg/L). Distinct groups of these genomes dominated the anammox-associated community at dysoxic and oxic sites, further reflecting the influence of dissolved oxygen on Brocadiae composition. Anammox gene and transcript (hzsB) concentrations correlated significantly and positively with those involved in bacterial and archaeal aerobic ammonia oxidation (ammonia monooxygenase, amoA), which could represent a major source of nitrite for anammox. This trend was confirmed with metatranscriptomic data, which revealed the co-occurrence of aerobic (nitrification, including ammonia oxidation) and anaerobic (denitrification, nitrite-dependent anaerobic methane oxidation, and anammox) processes in dysoxic groundwater (0.3–1.1 mg/L bulk dissolved oxygen), indicating the availability of oxic-anoxic interfaces. Concurrent activity by ammonia oxidizers, anammox bacteria, and methanotrophic bacteria, indicates potential synergism and metabolic “hand-offs” through shared metabolic products (e.g. nitrite). In addition, the portion of complete versus incomplete denitrifiers was substantially higher under low oxygen conditions. Genes and transcripts encoding atypical Sec-dependant N2O reductases (NosZ) were the most common type, and although usually associated with incomplete denitrifiers, were found here to be also associated with complete denitrifiers. Nitrospirota species are usually regarded as key contributors to nitrification. Genomic and transcriptomic analysis indicates that a Nitrospirota species from groundwater-derived genus, 9FT-COMBO-42-15, has the capacity for versatile autotrophic sulfur and anaerobic nitrogen metabolism, including dissimilatory nitrate reduction to ammonium and complete denitrification coupled to sulfur oxidation. As the phylum comprises considerable uncharacterised diversity, the newly-recovered genome was analysed alongside sixty-seven other genomes spanning all nine Nitrospirota orders to determine the metabolic capacity for carbon fixation and nitrogen and sulfur cycling across the phylum. This analysis revealed that species belonging to Nitrospirota comprise three clades that have distinct environmental niches and metabolic attributes, largely influenced by oxygen availability. This thesis provides insights into factors influencing nitrogen-transformations in groundwater, such as oxygen availability across a diverse range of aquifer conditions. Data indicates anammox bacteria contribute to loss of fixed N across diverse anoxic-to-oxic aquifer conditions, and that this is likely supported by nitrite from aerobic ammonia oxidation. Moreover, the phylogenetic and genomic analysis of Nitrospirota species recently recovered from diverse groundwater environments, and other environments (such as subseafloor crustal fluid, alpine thermal spring water, sulfur rich hydrothermal vent sediments and soils), sheds light on the divergent metabolic capacities between well-characterised Nitrospirota (characterised predominantly by aerobic nitrifiers) compared with the widespread capacity for anaerobic nitrogen and sulfur metabolism among newly-defined families that lacked metabolic characterisation
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