1,720,957 research outputs found
Investigating the lipid profile of animal-microbe symbioses
No full textLipids are important and understudied elements of host-bacteria interactions. Lipids play central roles in defining cellular membranes, they have a structural role but also influence the distribution and activity of transporters, enzymes and receptors. Aside of their functions in the membrane, they have important functions as signaling molecules, energy storages, coenzymes or toxins. In pathogenic interactions, lipids have been shown to participate to every stage of the interaction between the host and the bacteria. A few studies have focused on beneficial symbioses and we only start to discover the importance of lipids in those interactions. Much of the functional importance of the rich chemical diversity of lipids remains unknown. In this study, I aimed to describe the chemical landscape of deep-sea mussels living in close association with chemoautotrophic bacteria (Chapter I) and determine the identity, distribution and potential functions of a metabolite group specific to the association between deep-sea mussels and methane-oxidizing symbionts (Chapter II). This research was expanded to shallow water symbioses formed by gutless annelids and chemoautotrophic bacteria. The study of their sterol pool revealed a new phytosterol synthesis pathway specific to animals (Chapter III)
Compound-specific carbon isotopes of sitosterol and cholesterol in gutless marine annelids and associated seagrass and porewater
No full textThe data set contains compound-specific carbon isotope measurements of the lipid biomarkers sitosterol and cholesterol in the gutless annelids Olavius algarvensis and Olavius ilvae, which were collected from the sediment by scuba diving in the Bay of Sant' Andrea on the Island of Elba in Italy. Further, compound-specific carbon isotopes of sitosterol was measured for the seagrass plants Posidonia oceanica, which were collected at the seagrass meadows from the same site where the gutless annelids were collected. For Posidonia oceanica, leaves and rhizomes were measured separately for their compound-specific δ13C values . Finally, porewater samples were collected near the seagrass meadows and filtered porewater samples were measured for the compound-specific δ13C values of cholesterol and sitosterol as well.
Generally, sitosterol is known as lipid biomarker of plants, whereas cholesterol is produced by animals. In the studied gutless annelids, however, sitosterol is the most abundant sterol, accompanied by cholesterol. The aim was to find out if the gutless annelids aquire their sterols from the environment by passive diffusion, or if they can produce sitosterol de novo. The δ13C values of sitosterol in the gutless annelids was ranging from -38 to -36‰, whereas sitosterol in the seagrass and porewater was between -30 to -29‰ and -19 to -15‰, respectively. The difference in the isotope signature of the sitosterol in both Olavius species and their environment (Seagrass and Porewater) excludes, that the gutless annelids aquired their sterols form the environment. Instead, the gutless worms get all their nutrition from chemosynthetic bacterial symbionts, which is reflected by the bulk carbon isotopic composition of the worms (-31‰). The δ13C values of the cholesterol and sitosterol varies by 1 to 10‰ to bulk biomass in the gutless annelids. It is hypothesized, that the worms synthesize their sterols de novo, using carbon sources from their chemosynthetic symbionts
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
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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