1,721,013 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
Comparative Analysis of Flagellotropic Agrobacterium Phages
No full textThe planetary microbiome is dominated by bacteriophages, the viruses of bacteria. Bacteriophages utilize various means to infect their bacterial hosts, but all phages require receptors on the host surface. Flagellotropic bacteriophages involve an actively rotating bacterial flagellum to attach and initiate the infection process. Flagellotropic bacteriophages are poorly studied compared to their non-flagellotropic counterparts. It is important to research the relationship between these phages and their hosts to elucidate the mechanisms behind the attachment and infection process. It is imperative that we expand the knowledge on these mechanisms due to the increase in potential phage applications both medically and environmentally. This study investigates three flagellotropic phages and their bacterial hosts: Milano and host Agrobacterium tumefaciens str. C58, OLIVR4 and host Agrobacterium Biovar 1 str. ST15.13/040, and 7-7-1 and host Agrobacterium sp. H13-3.
Chapter 1 is a literature review. Chapter 2 discusses the identification of the bacterial lipopolysaccharide as a secondary receptor for bacteriophage Milano, and the cross infectivity of the three bacteriophages with the three host bacteria. We quantified infectivity of the three bacterial host strains with the three bacteriophages by performing Efficiency of Plating assays (EOPs) and observed interesting relationships between the phages and host strains. We were also able to further support the hypothesis that OLIVR4, a recently discovered Agrobacterium phage, is indeed flagellotropic by infecting a host mutant with non-rotating flagella with OLIVR4. Overall, this research will help expanding the knowledge of this special class of bacteriophages, opening the door for their further applications in medicine and environmental sciences.Master of ScienceBacteriophages, phages for short, are viruses that only infect bacteria. While phages can use many methods to infect their hosts, all of these methods require receptors- a structure that is produced by the bacterial host cell – for attachment. Phages that use the host flagellum, which is a helical filament that protrudes from the bacterial cell and facilitates movement, are referred to as flagellotropic phages. For these phages, an actively rotating bacterial flagellum is a requirement for infection, but there can be additional structures that aide in adhesion and infection. These additional structures are referred to as secondary receptors. Phages can be used to supplement or even replace antibiotic treatment, both medically and environmentally. As antibiotic resistance is a rising concern in the medical sector especially, phages are rising as a treatment option. One benefit of the use of phages is their high specificity, which enables them to kill only the target bacterium while leaving the rest of the microbiome intact.
In this work, we investigated three different flagellotropic phages—Milano, OLIVR4, and 7-7-1. First, we identified secondary receptors for Milano. We also studied how the three phages behaved when they were given the opportunity to infect different Agrobacterium species. Agrobacteria are known to cause Crown gall disease—a disease that results in tumor-like growths in plants. It is important to understand how these phages interact with their hosts to work towards potential therapeutics for this devastating plant disease
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Characterization of the thioredoxin system in Methanosarcina mazei
No full textThioredoxin (Trx) and thioredoxin reductase (TrxR) along with an electron donor form a thioredoxin system. Such systems are widely distributed among the organisms belonging to the three domains of life. It is one of the major disulfide reducing systems, which provides electrons to several enzymes, such as ribonucleotide reductase, methionine sulfoxide reductase and glutathione peroxidase to name a few. It also plays an important role in combating oxidative stress and redox regulation of metabolism. Trx is a small redox protein, about 12 kDa in size, with an active site motif of Cys-X-X-Cys. The reduction of the disulfide in Trx is catalyzed by TrxR. Two types of thioredoxin reductases are known, namely NADPH thioredoxin reductase (NTR) with NADPH as the electron donor and ferredoxin thioredxoin reductase (FTR) which depends on reduced ferredoxin as electron donor. Although NTR is widely distributed in the three domains of life, it is absent in some archaea, whereas FTRs are mostly found in plants, photosynthetic eukaryotes, cyanobacteria, and some archaea.
The thioredoxin system has been well studied in plants, mammals, and a few bacteria, but not much is known about the archaeal thioredoxin system. Our laboratory has been studying the thioredoxin systems of methanogenic archaea, and a major focus has been on Methanocaldococcus jannaschii, a deeply rooted archaeon that has two Trxs and one TrxR. My thesis research concerns the thioredoxin system of the late evolving members of the group which are exposed to oxygen more frequently than the deeply rooted members of the group, and have several Trxs and TrxRs. Methanosarcina mazei is one such organism, whose thioredoxin system is composed of one NTR, two FTRs, and five Trx homologs.
Characterization of the components of a thioredoxin system sets the basis to further explore its function. I have expressed in Escherichia coli and purified the five Trxs and three TrxRs of M. mazei. I have shown the disulfide reductase activities in MM_Trx1 and MM_Trx5 by their ability to reduce insulin with DTT as the electron donor, and that in MM_Trx3 through the reduction of DTNB by this protein with NADPH as the electron donor, and in the presence of NTR as the enzyme. MM_Trx3 was found to be the only M. mazei thioredoxin to accept electrons through the NTR, and to form a complete Trx - NTR system. The Trx - FTR systems are well studied in plants, and such a system is yet to be defined in archaea. I have proposed a mechanism of action for one of the FTRs. FTR2 harbors a rubredoxin domain, and this unit is the only rubredoxin in this organism. Superoxide reductase, an enzyme that reduces superoxide radical to hydrogen peroxide without forming oxygen, utilizes rubredoxin as the direct electron source and this enzyme is found in certain anaerobes, including Methanosarcina species. Thus, it is possible that FTR2 provides electrons via a Trx to the superoxide reductase of M. mazei. This activity will define FTR2 as a tool in combating oxidative stress in M. mazei.
In my thesis research I have laid a foundation to understand a complex thioredoxin system of M. mazei, to find the role of each Trx and TrxR, and to explore their involvement in oxidative stress and redox regulation.Master of Scienc
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