1,720,988 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
Function and targets of the Urm1/Uba4 conjugation machinery in <em>Drosophila melanogaster</em> [Elektronisk resurs]
No full textPosttranslational modification (PTM) of proteins is essential to maintain homeostasis and viability in all eukaryotic cells. Hence, besides the sequence and 3D folding of a polypeptide, modification by multiple types of PTMs, ranging from small molecular groups to entire protein modules, adds another layer of complexity to protein function and regulation. The ubiquitin-like modifiers (UBLs) are such a group of evolutionary conserved protein modifiers, which by covalently conjugating to target proteins can modulate the subcellular localization and activity of their targets. One example of such a UBL, is the Ubiquitin related modifier 1 (Urm1). Since its discovery in 2000, Urm1 has been depicted as a dual function protein, which besides acting as a PTM, in addition functions as a sulfur carrier during the thio-modification of a specific group of tRNAs. Due to this dual capacity, Urm1 is considered as the evolutionary ancestor of the entire UBL family. At present, it is well established that Urm1, with help of its dedicated E1 enzyme Uba4/MOCS3, conjugates to multiple target proteins (urmylation) and that Urm1 thus plays important roles in viability and the response against oxidative stress.The aim of this thesis has been to, for the first time, investigate the role of Urm1 and Uba4 in a multicellular organism, utilising a multidisciplinary approach that integrates Drosophila genetics with classical biochemical assays and proteomics. In Paper I, we first characterized the Drosophila orthologues of Urm1 (CG33276) and Uba4 (CG13090), verified that they interact physically as well as genetically, and that they together can induce urmylation in the fly. By subsequently generating an Urm1 null Drosophila mutant (Urm1n123), we established that Urm1 is essential for viability and that flies lacking Urm1 are resistant to oxidative stress. Providing a molecular explanation for this phenotype, we demonstrated an involvement of Urm1 in the regulation of JNK signaling, including the transcription of the cytoprotective genes Jafrac1 and gstD1. Besides the resistance to oxidative stress, we have moreover (Manuscript IV) made an in-depth investigation of another phenotype displayed by Urm1n123 mutants, an overgrowth of third instar larval neuromuscular junctions (NMJs), a phenotype which is shared also with mutants lacking Uba4 (Uba4n29).To increase the understanding of Urm1 in the fly, we next employed a proteomics-based approach to identify candidate Urm1 target proteins (Paper II). Using this strategy, we identified 79 Urm1-interacting proteins during three different stages of fly development. Of these, six was biochemically confirmed to interact covalently with Urm1, whereas one was found to be associated with Urm1 by non-covalent means. In Manuscript III, we additionally identified the virally encoded oncogene Tax as a target of Urm1, both in Drosophila tissues and mammalian cell lines. In this study, we established a strong correlation between Tax urmylation and subcellular localization, and that Urm1 promoted a cytoplasmic accumulation and enhanced signalling activity of Tax, with implications for a potential role of Urm1 in Tax-induced oncogenesis.Taken together, this thesis provides a basic understanding of the potential roles and targets of Urm1 in a multicellular organism. The four studies included cover different aspects of Urm1 function and clearly points towards a highly dynamic role of protein urmylation in fly development, as well as in adult life.</p
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
Microenvironment and tumors-nurturing relationship
No full textWhen exposed to adverse environmental conditions, cells degrade their own content to recycle cellular building blocks through a process called autophagy. A large body of literature has connected autophagy to cancer, but most studies up until now focused on its function in transformed cells. In her thesis, Nadja Katheder dissected the role of autophagy in a well-characterized neoplastic in vivo tumor model in Drosophila and demonstrates a novel non-cell-autonomous requirement of this process for tumor growth. Neighboring epithelial cells and distal tissues increase autophagy in the presence of a malignant tumor. Pharmacological autophagy inhibition reduces tumor growth and genetic ablation of autophagy in the microenvironment reveals a tumor-supportive role of this process in this specific cell population. Tumor cells are metabolically stressed and induce autophagy in their neighbors through a TNFa-JNK-IL-6 signaling cascade. Moreover, they are dependent on amino acid import to sustain their proliferation, which indicates a coupling of metabolism between these two cell populations. Finally, allografted growthimpaired tumors from autophagy-deficient donor animals resume growth in an autophagy-competent host. Together, the results described in this thesis highlight the tumor-promoting role of autophagy the microenvironment and show that cancer cells engage their epithelial neighbors as essential contributors aiding their own growth
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
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