1,721,024 research outputs found
Use of microcosm experiments to investigate the genetic potential for methylotrophic methanogenesis in marine sediments
Get PDFWastewater treatment plants often use methanol to drive denitrification for nitrogen removal. This can lead to excess methanol reaching water bodies through the effluent discharge. This excess methanol can stimulate methylotrophic methanogenesis in marine sediments, potentially increasing methane production.The current thesis investigated the enrichment of microorganisms capable of methylotrophic methanogenesis in sediment samples from the Oslo fjord. Microcosms consisting of sediment material and synthetic seawater were enriched in four different ways. Enrichments were performed using methanol, nitrate and methanol and nitrate together as well as a control. The microcosms were monitored over time by measuring NO3-, NO2-, NH3/NH4+, pH and ORP every 2-3 days. Sediment samples were collected every 3-4 days and DNA was extracted. The extracted DNA was analysed using qPCR, 16S rRNA amplicon sequencing and shotgun metagenomic sequencing to investigate the inferred taxonomic composition and the genetic potential of the methylotrophic methanogens in the sediments.The results revealed a significant enrichment of methanogenic archaea within the family Methanosarcinaceae for samples amended with methanol after 17 and 21 days of incubation at ORPs higher than +50 mV. This was both observed using relative read counts from 16S rRNA amplicon analysis, as well as FAPROTAX analysis that inferred metabolic processes to the taxa identified from the 16S rRNA sequences.Investigation of the shotgun sequencing data revealed three MAGs that were taxonomically annotated as archaea belonging to the family Methanosarcinaceae. The genomic potential in each of these MAGs were investigated for presence of methanogenesis genes, and for completeness of the relevant pathways. Methyl reduction was revealed as the most probable methylotrophic pathway. The number of genes in each MAG that were related to methanogenesis from methanol varied, but all MAGs contained the genes mcrABG, mtaB and mtaC which convert methanol into methyl-CoM and further into methane. MtaA was identified in two of the three MAGs.The enrichment of Methanosarcinaceae occurred at higher ORP measurements than expected from literature. This is an interesting aspect of the results, that should be followed up in future research based on methylotrophic methanogenesis in 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
The Prevalence of Blp Bacteriocin Genes in Gut-Associated Streptococci
Get PDFBakteriocin-lignende peptider (Blp-er) er små antimikrobielle proteiner produsert av enkelte bakteriearter, inkludert medlemmer av Streptococcus-slekten. Selv om Blp-er har vært knyttet til mikrobielle konkurranseforhold og strukturering av mikrobielle samfunn, er deres utbredelse og mangfold i menneskets mikrobiomer fortsatt lite kartlagt. Denne oppgaven har som mål å undersøke forekomst, variasjon og mulige økologiske roller til Blp-gener hos Streptococcus-arter som finnes i menneskets tarm, ved hjelp av genomsøk og sekvensanalyse.
Et omfattende søk ble gjennomført ved bruk av profil skjulte Markov-modeller (pHMM-er) for å oppdage Blp-sekvenser i to store genomdatabaser: GTDB og humgut2. GTDB (Genome Taxonomy Database) inneholder høykvalitets referansegenomer, mens humgut2 hovedsakelig består av metagenom-baserte genomer (MAG-er) fra menneskets tarmmikrobiom. Et tredje datasett, HOMD (Human Oral Microbiome Database), ble brukt for å sammenligne Streptococcus-arter fra tarmen med de som primært finnes i munnhulen. Blp-positive sekvenser ble videre karakterisert basert på deres forutsagte fysikalsk-kjemiske egenskaper, og sammenlignet med kjente klasse II-bakteriociner, noe som indikerer funksjonelle likheter. Samforekomst mellom visse Blp-typer ble også observert, noe som kan tyde på koordinert funksjon eller regulering.
Resultatene viste at noen arter, som S. pneumoniae, S. pseudopneumoniae og S. dysgalactiae, konsekvent inneholdt flere Blp-gener, mens andre, som S. gordonii og S. sobrinus, ikke hadde noen påvisbare Blp-gener. Et markant skille i Blp-forekomst ble sett mellom munnhulen og tarmen hos arter som S. mitis og S. oralis, hvor det var en høy forekomst av Blp-gener i munnhulen. Disse funnene samsvarer med tidligere observasjoner av en uventet sammenheng mellom Blp-rikdom og stammediversitet i spedbarns tarmmikrobiom.
Samlet gir denne oppgaven ny innsikt i økologisk distribusjon og mulig funksjon av Blp-gener hos Streptococcus-arter knyttet til mennesker, og legger grunnlaget for videre studier av deres rolle i mikrobiomets stabilitet og mikrobielle interaksjoner
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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