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Lipid profiles of deep-sea organisms
No full textLipids are a group of biologically important compounds that may be used as indicators of relationships between an organism and its environment. Lipid class composition identifies types of storage lipid which can suggest a pelagic or benthic existence and may be used to measure the condition of an organism. Fatty acid composition may reflect trophic ecology. Lipid profiling has been used to elucidate elements of the ecology of organisms from Mid-Atlantic and Juan de Fuca Ridge hydrothermal vents and shrimp from below a permanent oxygen minimum zone. Lipid profiles of these organisms from extreme deep-sea environments are compared. Lipid profiles of adult Mid-Atlantic Ridge hydrothermal vent shrimp, Rimicaris exoculata. support a benthic existence and primarily chemoautotrophic bacterial nutrition. Postlarval alvinocarid shrimp lipid profiles suggest a pelagic life cycle stage with a reliance on phototrophically derived organic matter. This result supports previous molecular evidence that Rimicaris exoculata travels between hydrothermal vents on the Mid-Atlantic Ridge. The branchial area of Rimicaris exoculata has been reported to be colonised with bacteria and elevated levels of bacterial fatty acids are present in these tissues. Lipid analyses of the reproductive organs of Rimicaris exoculata reveal increases in triglycerides, sterols, phosphatidyl choline and the proportion of n-3 fatty acids with advancing reproductive maturity. Preliminary studies of the lipid profiles of the Mid-Atlantic vent shrimp Alvinocaris markensis support the hypothesis that it is a scavengerand contains a lower proportion of bacterially derived fatty acids.The lipid profiles of the deep-sea shrimp, Nematocarcinus gracilis, from the Indian Ocean, were consistent with a benthic lifestyle, opportunistic feeding and a reliance on phototrophically derived organic matter. Despite the presence of a permanent oxygen minimum zone above the habitat of the shrimp, Nematocarcinus gracilis contain low levels of highly unsaturated fatty acids, reflecting a reduction in the availability of labile organic matter with depth. The hydrothermal vent tube worm Ridgeia piscesae contains only low levels of storage lipid, reflecting an extreme reliance on endosymbiotic bacteria. Wax esters detected are thought to be stored in oocytes. The fatty acid profile of Ridgeia piscesae reveal mainly bacterial biomarker fatty acids, but some phototrophically derived fatty acids are also present. Adult Ridgeia piscesae have no gut, so the mechanism by which these fatty acids are assimilated is uncertain. Lipid profiles of the hydrothermal vent palm worm, Paralvinella palmiformis vary with the conditions of the different microenvironments in which specimens were found. Fatty acids reflect a mixed diet based mainly on chemoautotrophic bacteria, but with significant inputs of phototrophically derived organic matter, such as diatom debris. Phototrophically derived fatty acids were also detected in the hydrothermal vent clam Calyptogenapacifica. suggesting that the reduced filter-feeding ability of this species is used to supplement nutrition from endosymbiotic bacteria. Endosymbiont-bearing gill tissues contain the highest proportion of bacterial fatty acids and also high concentrations of triglycerides. The presence of triglycerides in gill tissues suggests that energy may be transferred from symbionts by hydrolysis of bacterial symbiont membrane lipids and their conversion to triglyceride. The lipid profiles presented in this work increase understanding of the life history strategies and ecology of the species studied. This thesis shows that even the most highly adapted hydrothermal vent organisms do not rely solely on a chemoautotrophic source of nutrition, but also appear to require phototrophically derived elements in their diet
Lipid composition of the hydrothermal vent clam Calyptogena pacifica (Mollusca: Bivalvia) as a trophic indicator
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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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