1,720,962 research outputs found
Anpassung von Bakterien an zeitlich variable Antibiotikaumgebungen
No full textThe variability of the environment is a challenge for the flexibility of organisms. Temporal variation generates interesting optimization conflicts for evolution, which were investigated in this doctoral thesis for the example of the bacterium Pseudomonas aeruginosa and the sequential treatment with antibiotics. This bacterium has remarkable metabolic and genetic versatility. P. aeruginosa expresses a range of efflux pumps for cell detoxification. Increasingly, this characteristic is transforming into a medical threat because it can convey antibiotic resistance. The spread of antibiotic resistance is a growing global challenge. The investigations of this thesis, may contribute to the design of new treatment strategies that inhibit the emergence of resistance. This aim was achieved by integrating three principles from evolutionary ecology into drug treatments and testing them for their efficacy in delaying resistance evolution: genetic conflicts, physiological conflicts, and environmental stochasticity.Die Variabilität der Umwelt ist eine große Herausforderung für die Flexibilität der Lebewesen. Über lange Zeiträume entstehen interessante Optimierungskonflikte für die Evolution. Diese wurden im Rahmen dieser Doktorarbeit beispielhaft am Bakterium Pseudomonas aeruginosa und mit sequentieller Antibiotikabehandlung untersucht. Die Besonderheit dieses Bakteriums ist seine metabolische und genetische Vielseitigkeit. P. aeruginosa besitzt zahlreiche Pumpsysteme zur Entgiftung der Zelle. Zunehmend wird diese Eigenschaft zu einer medizinischen Bedrohung, da durch sie Antibiotikaresistenz vermittelt werden kann. Die Verbreitung von Antibiotikaresistenzen ist eine dringliche globale Herausforderung. Die Untersuchungen dieser Dissertation tragen dazu bei, neue Behandlungsmethoden zu entwickeln, mit denen die Entstehung weiterer Resistenzen gehemmt werden kann. Hierzu wurden Prinzipien der Evolutionsökologie in Antibiotikabehandlungen integriert und auf ihre Wirksamkeit in der Hemmung von Resistenzevolution erprobt: Genetische Konflikte, physiologische Konflikte und Stochastizität
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
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
Evolutionary ecology meets the antibiotic crisis: can we control pathogen adaptation through sequential therapy?
No full textThe spread of antibiotic resistance is a global challenge that is fueled by evolution and ecological processes. Therefore, the design of new sustainable therapy should take account of these underlying processes – as proposed within the field of evolutionary medicine, yet usually not receiving the necessary attention from national and international health agencies. We here put the spotlight on a currently neglected treatment strategy: sequential therapy. Changes among antibiotics generates fluctuating selection conditions that are in general difficult to counter by any organism. We argue that sequential treatment designs can be specifically optimized by exploiting evolutionary trade-offs, for example collateral sensitivity and/or inducible physiological constraints, such as negative hysteresis, where pre-exposure to one antibiotic induces temporary hyper-sensitivity to another antibiotic. Our commentary provides an overview of sequential treatment strategies and outlines steps towards their further optimization
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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