1,720,996 research outputs found
Functional analysis of the purified Rad51 protein from Trichomonas vaginalis
No full textTrichomonas vagina/is is a parasitic protist that is responsible for the sexually transmitted disease Trichomoniasis. It has been observed in other parasitic protists (such as Giardia and Trypanosoma) that the variable surface proteins (proteins on the outside of the cell) can be modified, essentially hiding the parasite from the host immune system. While this has yet io be directly observed in Trichomonads, the cellular machinery required for this process appears to be present. One protein that could play an important role is the Rad51 recombinase. Rad51 is involved in repairing double strand DNA breaks that can occur by accident or on purpose during meiosis. In Trichomonas, it may be involved in recombining DNA to express new functional gene products not recognized by the host immune system. This project deals with characterizing the Rad51 homolog in Trichomonas vagina/is. We are performing protein purification and functional assays to demonstrate different activities normally found in Rad51 proteins, such as ATP hydrolyzing activity, strand exchange and D-loop formation
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
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
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Structural and Mechanistic Insights into a Specialized Secretion System Necessary for M. tuberculosis Virulence
Full text linkMycobacterium tuberculosis utilizes a specialized secretion system, known as Type VII Secretion (T7S) to translocate virulence factors into the host cell. T7S is absolutely necessary for virulence of M. tuberculosis, as well as other pathogens such as S. aureus. Intriguingly, T7S systems are broadly conserved amongst all Gram-positive bacteria, and likely play diverse roles in bacterial physiology. In this work, we focused on the two conserved components present in all T7S systems: the FtsK-like ATPase EccC and the WXG-100 substrate EsxB. We developed a biochemical model system to answer questions about the structure and molecular mechanisms of these two protein components, and confirm our results using genetics in M. tuberculosis. Using this system, we i) identified the substrate-binding pocket on EccC, ii) identified the non-canonical "signal sequence" on the EsxB substrate, iii) determined the molecular basis of substrate specificity, iv) solved the structure of the EccC ATPase both bound and unbound to signal sequence, as well as the EssC homolog from Geobacillus thermodenitrificans, v) determined a molecular mechanism of EccC autoinhibition, and vi) uncovered a mechanism by which substrates control activity of EccC through multimerization. Overall, this work generated the first biochemical model for T7S
Manually Powered Otoscope
No full textOne of the most basic medical diagnostic tools is the otoscope – the device used to examine the ear canal. Unfortunately, many doctors in remote and developing regions do not have easy, ready access to electricity or batteries, rendering them unable to use this tool. We have designed an otoscope that is powered completely by moderate shaking and which uses a low power, but very bright, LED. Our otoscope is also designed to withstand harsh environmental conditions, such as very high and very low temperatures as well as high degrees of humidity. We are going to be testing our otoscope under various conditions, such as humidity and moisture, to determine how effectively it will still run under these harsh conditions
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
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