1,721,020 research outputs found
Autökologie von Crenarchaeoten und Bakterien in Meeressedimenten und Mikrobenmatten
No full textThe focus of this thesis was the autecology of the Miscellaneous Crenarchaeotal Group (MCG), a phylum-level clade of Archaea occurring mostly in marine sediments. Sequences of MCG 16S rRNA genes have been retrieved from a wide range of marine and terrestrial habitats, such as deep subsurface sediments, hydrothermal sediments, mud volcanoes, estuaries, hot springs and freshwater lake sediments. MCG members seem to have no general preferences for a particular temperature or salinity. So far, not a single member of the elusive MCG has been cultured. They show a high intragroup diversity with percent identity values of 16S rRNA as low as 77%. Since MCG sequences are frequent in sulfate-methane transition zones (SMTZ) of deep sea subsurface sediments, MCG were assumed to be the dominant archaeal population which might greatly contribute to biogeochemical cycles in the deep biosphere. However, quantitative data on the abundance and activity of MCG are still largely lacking. Therefore, in this doctoral thesis, a polyphasic approach was applied for the quantification and visualization of MCG in marine habitats using different molecular methods such as slot-blot hybridization, quantitative PCR and fluorescence in situ hybridization. MCG-specific oligonucleotide probes and primers were designed and used for the quantification. It was shown that in general the relative abundance of MCG strongly increased with depth. In methane-rich surface sediments MCG abundances were below 3% of total Archaea. In contrast, MCG constituted a major part of the archaeal community with 15-100% in subsurface SMTZ. My results provide the first quantitative data on the high abundance of MCG in deep subsurface sediments and are inline with a major role of MCG in biogeochemical cycling in these habitats. In this thesis, cells of MCG were visualized for the first time by CARD-FISH. The cell shape was coccoid and the cell diameter was 0.4-0.5 µm. Signals were weak, but still clearly detectable with CARD-FISH suggesting that MCG are not only abundant, but also active in subsurface sediments. The single cell identification protocol developed in this doctoral thesis will in the future facilitate further quantitative investigations of the autecology of MCG. Further experiments performed in the course of this doctoral thesis addressed the quantification and visualization of particular bacterial populations such as Chloroflexi and Aquificae in microbial mats and marine sediments
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
Sulfuriflexus mobilis gen. nov., sp nov., a sulfur-oxidizing bacterium isolated from a brackish lake sediment
Get PDFA chemolithotrophic sulfur-oxidizing bacterium, strain aks1(T), was isolated from sediment of a brackish lake in Japan. The cells were curved rod-shaped and Gram-stain-negative. The G+C content of the genomic DNA was 53 mol%. The major components in the cellular fatty acid profile were C-16:0 and summed feature 3 (C-16 (: 1)omega 7c and/or C-16 (: 1)omega 6c). As electron donor for chemolithoautotrophic growth, strain aks1(T) oxidized thiosulfate, sulfide, and elemental sulfur. The strain could utilize oxygen and nitrate as an electron acceptor for thiosulfate oxidation. Growth was observed at a temperature range of 5-34 degrees C, with optimum growth at 30-32 degrees C. Growth of the strain was observed at a pH range of 6.4-8.7. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain is related to members of the family Granulosicoccaceae within the order Chromatiales, with sequence similarities around 92%. On the basis of phylogenetic and phenotypic properties, strain aks1(T) represents a novel species of a new genus, for which the name Sulfuriflexus mobilis gen. nov., sp. nov. is proposed. The type strain of the type species is aks1(T) (=DSM 102939(T) =NBRC 111889(T))
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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