1,721,009 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
Grafting of thrombopoietin-mimetic peptides into cystine knot miniproteins yields high-affinity thrombopoietin antagonists and agonists
No full textThrombopoietin is the primary regulator of platelet production. We exploited two naturally occurring miniproteins of the inhibitor cystine knot family as stable and rigid scaffolds for the incorporation of peptide sequences that have been shown to act as high-affinity thrombopoietin antagonists. Several miniproteins that antagonistically block thrombopoietin-mediated receptor activation were identified using a microscale reporter assay. Covalent miniprotein dimerization yielded potent bivalent c-Mpl receptor agonists with EC50 values in the low nanomolar or picomolar range. One selected miniprotein-derived thrombopoietin agonist was almost as active as natural thrombopoietin with regard to stimulation of megakaryocyte colony formation from human bone marrow mononuclear cells, and elicited doubling of platelet counts in mice. Our data suggest that dimeric cystine knot miniproteins have considerable potential for the future development of small and stable receptor agonists. This approach may provide a promising strategy for pharmaceutical interference with other receptors activated by ligand-induced dimerization
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
Assembly and application of genome-scale metabolic models to study Streptomyces coelicolor and Prochlorococcus
Get PDFSummary:
Metabolism is the set of all chemical reactions responsible for the conversion of nutrients into the energy and cellular building blocks required for growth and cellular maintenance in a living organism. Because of our detailed knowledge of enzymes and the chemical reactions they catalyze, one can create a rather accurate representation of an organism’s metabolic network from the sequenced and annotated genome. However, in contrast to classical textbook depictions of individual metabolic pathways, these metabolic networks are often highly interconnected and can contain thousands of different reactions and metabolites. Due to this complexity, computational and mathematical algorithms are often required to predict the phenotypic outcome of genetic modifications or changes in the nutrient environment.
When a metabolic network is combined with a representation of growth, cellular maintenance requirements, and available nutrients, it is called a genome-scale metabolic model. In this work we assemble and apply genome-scale metabolic models to study two rather different organisms. The first organism, Streptomyces coelicolor, is a complex, soil-dwelling bacterium that is of great interest within drug discovery as a cell factory for production of novel biopharmaceuticals. Through two consecutive publications we merge and improve existing S. coelicolor models into a consensus model that is hosted in an open-source environment to encourage contributions from the Streptomyces research community. We then apply the developed model to explore and understand how one should proceed with strain development to create a mutant strain that is optimal for heterologous expression of biosynthetic gene clusters. Another contribution in this direction is our development of a computational pipeline that automatically reconstructs metabolic pathways encoded by biosynthetic gene clusters.
The second organism, Prochlorococcus, is the most abundant phototrophic marine bacterium, and thus a major player in the marine food web and global carbon fixation. We use random sampling and dynamic flux balance analysis to understand how its metabolism is affected by the day-night cycle and varying nutrient conditions, with a particular focus on glycogen allocation and release of organic compounds that become nutrients for marine heterotrophs. Furthermore, this study required method development extending the software COMETS to account for the periodicity of available daylight and light absorption. Together, this work contributes to an increased understanding of S. coelicolor and Prochlorococcus, in addition to updated and improved genome-scale metabolic models which are by themselves valuable tools in further research of these bacteria. Additionally, we have developed generic tools of great value for a broader audience, both towards drug development and for future studies of photosynthetic microbes.Sammendrag:
Næringsstoffer omdannes til byggeklosser og energi i en bakterie (eller celle) ved hjelp av en mengde kjemiske reaksjoner som til sammen utgjør bakteriens metabolisme. De kjemiske reaksjonene katalyseres av enzymer, og metabolismen til hver enkelt art defineres av genene i bakteriens arvemateriale, og hvilke enzymer genene koder for. Med utgangspunkt i arvematerialet kan man derfor skissere opp modeller av hver arts spesifikke metabolisme som man kan bruke til f.eks. å forutsi hvordan en bakterie vil oppføre seg i et gitt vekstmiljø.
I denne doktorgraden har jeg laget og anvendt metabolske modeller for å studere to ulike bakterier. Den første bakterien, Streptomyces coelicolor, tilhører en slekt som er opphavet til mange av antibiotikaene som brukes i dag. På grunn av den økende graden av antibiotikaresistente sykdomsfremkallende bakterier er det et akutt behov for å finne og produsere nye virkestoffer. Her kan S. coelicolor spille en viktig rolle ved å fungere som en mikrobiell fabrikk som kan uttrykke genmateriale overført fra andre bakterier som koder for produksjonen av nye virkestoffer. Ved å kombinere en metabolsk modell med eksperimentelle data har jeg undersøkt hvilke tiltak som kan optimalisere produksjon av nye virkestoffer i S. coelicolor.
Jeg har brukt en lignende fremgangsmåte for å forstå hvordan ulike miljøer påvirker Prochlrococcus' evne til å lagre eller skille ut organisk materiale. Som den mest tallrike fotosyntetiske bakterien i havet er Prochlorococcus en hjørnestein i den marine næringskjeden, og det organiske materialet den produserer er viktige næringsstoffer for andre bakterier som ikke har evnen til å gjøre fotosyntese. Ved å simulere tusenvis av ulike næringsmiljøer har vi identifisert hvilke faktorer som har størst innvirkning på denne bakteriens metabolisme.
Til sammen har dette arbeidet bidratt til utviklingen av kunnskap og modelleringsverktøy for to bakterier som er av stor interesse innenfor hvert sitt anvendelsesområde
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
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