1,721,129 research outputs found
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
Exploration of the biotechnological properties of microalgae derived from Reunion biodiversity
No full textLes microalgues représentent une source considérable de substances d’intérêt à vocation économique encore relativement peu exploitée sauf pour quelques espèces produites industriellement. La production locale et la valorisation de ces microorganismes photosynthétiques représentent une réelle opportunité de développement économique pour les régions insulaires tropicales comme l’île de La Réunion qui sont, de par leur nature, trop dépendantes d’importations et peu exportatrices de richesses, malgré leur situation dans une des zones les plus productives en matière de biomasse végétale. Cette thèse en contrat Cifre s’inscrit dans le cadre d’un partenariat entre l’entreprise locale Green Mascareignes Technologies et le Laboratoire ChemBioPro de l’Université de La Réunion. Les travaux ont consisté à étudier la production d’astaxanthine (un pigment xanthophylle rouge ayant de nombreuses applications commerciales en nutrition, santé, cosmétique, aquaculture, etc.) à partir de la culture de souches locales de microalgues isolées spécifiquement à partir d’échantillons d’eau douce prélevés au sein de la biodiversité réunionnaise. Ces souches ont été morphologiquement et génétiquement identifiées comme appartenant aux genres Haematococcus (2 souches) et Dysmorphococcus (9 souches). Elles ont été cultivées en laboratoire dans différents volumes, de l’erlenmeyer au photobioréacteur de 3 litres, en faisant varier les conditions de culture pour optimiser la croissance cellulaire puis stimuler l’accumulation cellulaire de caroténoïdes. L’analyse de ces pigments par chromatographie en couche mince haute performance (HPTLC), chromatographie liquide haute performance (HPLC) et chromatographie liquide couplée à la spectrométrie de masse (LC-MS) a permis d’en préciser la nature et la teneur au sein des biomasses ainsi produites. Les souches d’Haematococcus ont présenté des profils pigmentaires similaires à ceux rapportés dans la littérature pour H. lacustris, l’espèce cultivée industriellement pour la production d’astaxanthine. Ils sont principalement composés d’astaxanthine, présente majoritairement sous forme de mono-esters mais aussi de di-esters et, dans une moindre mesure, non-estérifiée. La culture d’une de ces souches en photobioréacteur a permis de produire de la biomasse sèche enrichie en astaxanthine à des taux pouvant atteindre jusqu’à 3 g.L-1, et avec des productivités en biomasse et en astaxanthine de 0,02 g.L-1.j-1 et 0,25 mg.L-1.j-1, respectivement. Ces niveaux de productivité, bien qu’encore trop bas pour envisager un transfert industriel, sont toutefois encourageants pour une phase de domestication. Des préconisations ont été proposées afin de les améliorer et de permettre l’augmentation d’échelle. Les souches isolées de Dysmorphococcus, génétiquement différentes de l’espèce la plus étudiée du genre, à savoir D. globosus, pourraient être classifiées dans cinq espèces différentes. Toutes sont capables d’accumuler en réponse à des conditions de stress de l’astaxanthine et de la canthaxanthine, un autre caroténoïde d’intérêt commercial. La culture en photobioréacteur de deux de ces souches, morphologiquement et génétiquement différentes, a permis d’atteindre des niveaux de productivité en biomasse sèche supérieurs aux souches isolées d’Haematococcus, mais bien inférieurs concernant les caroténoïdes. Des études complémentaires sont nécessaires pour déterminer si elles peuvent représenter une source alternative de caroténoïdes d’intérêt potentiellement rentable économiquement.Microalgae represent a considerable source of economically valuable substances that remains relatively unexploited, except for a few industrially-produced species. The local production and valorization of such photosynthetic microorganisms would represent a real opportunity for the economic development of tropical island regions such as Reunion Island which are, by their nature, too dependent on imports and low exporters of wealth, despite their location in one of the most productive areas with respect to plant biomass. This “Cifre” thesis is part of a partnership between local company Green Mascareignes Technologies and the ChemBioPro Laboratory at the University of La Réunion. This work consisted in studying the production of astaxanthin (a red xanthophyll pigment with many commercial applications in nutrition, health, cosmetics, aquaculture, etc.) from the culture of local microalgae strains isolated specifically from freshwater samples collected from the Réunion's biodiversity. These strains were morphologically and genetically identified as belonging to Haematococcus (2 strains) and Dysmorphococcus genera (9 strains). They were grown in the laboratory at different volume scales, from Erlenmeyer flasks to 3-liter photobioreactors, varying the culture conditions to optimize cell growth and then stimulate cellular accumulation of carotenoids. Analysis of these pigments by high-performance thin-layer chromatography (HPTLC), high-performance liquid chromatography (HPLC) and liquid chromatography coupled with mass spectrometry (LC-MS) allowed to specify their nature and content within the biomasses. Haematococcus strains showed pigment profiles similar to those reported in the literature for H. lacustris, the species cultivated industrially for astaxanthin production. They were mainly composed of astaxanthin, present mostly in the form of monoesters but also diester and, to a lesser extent, non-esterified. The cultivation of one of these strains in photobioreactor allowed the production of astaxanthin-enriched dry biomass at rates of up to 3 g L-1, and with biomass and astaxanthin productivities of 0.02 g L-1 d-1 and 0.25 mg L-1 d-1, respectively. These productivity levels, while still too low for an industrial transfer to be considered, are nevertheless encouraging for a domestication phase. Recommendations were proposed to improve productivities and enable scale-up processing. The isolated Dysmorphococcus strains, genetically different from the most studied species of the genus, namely D. globosus, could be classified into five different species. All were able to accumulate, in response to stress conditions, astaxanthin and canthaxanthin, another carotenoid of commercial interest. The cultivation in photobioreactor of two morphologically and genetically different strains allowed to achieve higher levels of dry biomass productivity as compared to the isolated Haematococcus strains, but much lower with respect to carotenoids. Further studies will be necessary to determine whether they could represent a potentially economically viable alternative source of carotenoids of interest
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
Fungi and Fungal Metabolites for the Improvement of Human and Animal Nutrition and Health
No full textThe purpose of this book was not to provide a comprehensive overview of the vast arena of how fungi and fungal metabolites are able to improve human and animal nutrition and health; rather, we, as Guest Editors, wished to encourage authors working in this field to publish their most recent work in this rapidly growing journal in order for the large readership to appreciate the full potential of wonderful and beneficial fungi. Thus, this Special Issue welcomed scientific contributions on applications of fungi and fungal metabolites, such as bioactive fatty acids, pigments, polysaccharides, alkaloids, terpenoids, etc., with great potential in human and animal nutrition and health
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
Combinatorial biosynthesis of novel multi-hydroxy carotenoids in the red yeast xanthophyllomyces dendrorhous
No full textThe red yeast Xanthophyllomyces dendrorhous is an established platform for the synthesis of carotenoids. It was used for the generation of novel multi oxygenated carotenoid structures. This was achieved by a combinatorial approach starting with the selection of a β-carotene accumulating mutant, stepwise pathway engineering by integration of three microbial genes into the genome and finally the chemical reduction of the resulting 4,4’-diketo-nostoxanthin (2,3,2’,3’-tetrahydroxy-4,4’-diketo-β-carotene) and 4-keto-nostoxanthin (2,3,2’,3’-tetrahydroxy-4-monoketo-β-carotene). Both keto carotenoids and the resulting 4,4’-dihydroxy-nostoxanthin (2,3,4,2’,3’,4’-hexahydroxy-β-carotene) and 4-hydroxy-nostoxanthin (2,3,4,2’3’-pentahydroxy-β-carotene) were separated by high-performance liquid chromatography (HPLC) and analyzed by mass spectrometry. Their molecular masses and fragmentation patterns allowed the unequivocal identification of all four carotenoids
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