1,720,969 research outputs found
The effect of organic load on the rearing water and biofilter biofilm microbiota across the freshwater and brackish water phases in RAS with Atlantic salmon (Salmo salar)
Full text linkOppdrett av Atlantisk laks opplever for tiden betydelig vekst innenfor landbaserte resirkulerende akvakultursystemer, spesielt for smoltproduksjon. Biofilteret i RAS spiller en avgjørende rolle i å opprettholde ideell vannkvalitet og fiskehelse gjennom aktiviteten til mikroorganismer. Imidlertid vet vi lite om hvordan biofilterfunksjonen og de mikrobielle samfunnene forbundet med RAS vann og biofilterbiofilm påvirkes av organisk belastning.
Denne avhandlingen hadde som mål å undersøke ferskvanns- og brakkvannsfasen i RAS for Atlantisk laks og effekten av høy organisk belastning på de mikrobielle samfunnene i biofilterbiofilm og oppdrettsvann. For å oppnå dette ble seks identiske RAS undersøkt, hvorav tre RAS ble drevet under forhold med høy organisk belastning og tre RAS ble drevet under forhold med lav organisk belastning. Daglige målinger av vannkvalitet, inkludert nitrogenholdige stoffer, ble utført. Deretter ble totalt 206 prøver fra biofilteret og RAS vannet analysert ved bruk av mikrobiell samfunnsanalyse ved Illumina-sekvensering av variable V3-V4 regioner av 16S rRNA-genampliconer, etterfulgt av databehandling og statistiske analyser.
Biofilterbiofilmen og suspendert vann mikrobiota viste betydelige forskjeller mellom RAS drevet med høy organisk belastning og RAS drevet med lav organisk belastning i brakkvannsfasen, noe som tyder på at organisk belastning spilte en rolle i utformingen av biofilmens mikrobiota. Generelt ble de dominerende ordener som karakteriserte den mikrobiell samfunnsstruktur i RAS vannprøvene klassifisert som Rhodobacterales, Flavobacteriales, Burkholderiales og Cytophagales. Den mikrobielle sammensetningen i biofilmbærere av både RAS operert med høy organisk belastning og RAS operert med lav organisk belastning var hovedsakelig preget av ordener Rhodobacterales, Flavobacteriales, Saprospirales og Burkholderiales. I tillegg utforsket denne studien forskjellene i mikrobiell sammensetning mellom 0,2 µm og 8 µm filtrerte vannprøver, og avslørte betydelige forskjeller i disse mikrobielle samfunnene i ferskvannsfasen. ASV-ene som bidro mest til disse ulikhetene ble klassifisert som Lacihabitans, Comamonadaceae og Rhodobacterace.
Ytterligere forskning på dette feltet vil øke vår forståelse av de intrikate sammenhengene mellom organisk belastning, mikrobielle samfunn og ytelsen til RAS i produksjon av Atlantisk laks.Atlantic salmon aquaculture is experiencing significant growth in land-based recirculating aquaculture systems (RAS), particularly for smolt production. The biofilter within RAS plays a crucial role in maintaining ideal water quality and fish health through the activities of microorganisms. However, it is not well understood how biofilter function and the microbial communities associated with RAS water and biofilter biofilm are influenced by organic load.
This thesis aimed to investigate the freshwater and brackish water phase of Atlantic salmon RAS and the effect of high organic load on the microbial communities in the biofilter biofilm and rearing water. To address this aim, six identical RAS were examined, with three RAS operated with high organic load and three RAS operated with low organic load. Daily measurements of water quality, including nitrogenous substances, were conducted. Subsequently, a total of 206 samples from the biofilter and RAS water were subjected to microbial community analysis by Illumina sequencing of the variable V3-V4 regions of the 16S rRNA gene amplicons, followed by data processing and statistical analyses.
The biofilter biofilm and water-suspended microbiota differed significantly between the RAS operated at high organic load and the RAS operated at low organic load during the brackish water phase, indicating that the organic load played a role in shaping the biofilm microbiota. In general, the dominant orders characterizing the microbial community composition in the RAS water samples were Rhodobacterales, Flavobacteriales, Burkholderiales and Cytophagales. The microbial community composition in biofilm carriers of both the RAS operated at high organic load and the RAS operated at low organic load was mainly characterized by the orders Rhodobacterales, Flavobacteriales, Saprospirales and Burkholderiales. Additionally, this study explored the differences in microbial compositions between 0.2 µm and 8 µm filtered water samples, revealing significant distinctions in these microbial communities’ freshwater phase. Notably, the amplicon sequence variants (ASV) contributing the most to these dissimilarities were classified as Lacihabitans, Comamonadaceae and Rhodobacteraceae.
Further research in this field will enhance our understanding of the intricate relationships between organic load, microbial communities, and the performance of RAS in Atlantic salmon production
The ejaculate microbiota in an avian hybrid system across allo- and sympatry
No full textIn sexually reproducing taxa, normal sperm function is critical for successful reproduction, and pathogenic bacteria can prevent this. Thus, understanding the role of bacteria in ejaculates can have significant implications for ecology and evolution. Although a few studies have investigated the human ejaculate microbiota, the amount of culture-independent research on other species is limited. By utilizing high-throughput sequencing of 16S rRNA gene amplicons, significant advances can be made in the knowledge of diverse bacterial communities. This study describes and compares the ejaculate microbiota of the house sparrow (Passer domesticus), Spanish sparrow (P. hispaniolensis) and Italian sparrow (P. italiae). These species constitute a hybrid species system in which the Italian sparrow originated through hybridization between the house and Spanish sparrow, and occur in both allo- and sympatry throughout Europe. I found the composition and structure of the sparrow ejaculate microbiota to be highly variable between individuals, and this obscured any species-specific signal. Individuals at different locations did however trend towards being different. I detected a wide range of bacteria belonging to 36 phylum-level classifications, of which Bacteroidetes and Proteobacteria were the most abundant. At the genus level, I found Flavobacterium to dominate the avian ejaculate microbiota. Notably, a considerable variety of bacteria classified to unculturable candidate phyla were detected. Overall, I found large overlap with taxa commonly found in the avian gastrointestinal tract and human ejaculate, as well as with previous culture-based studies on avian ejaculate. A wide range of potential pathogens likely to detriment host health or sperm function were detected. It is likely that these cause similar selective pressures on the mating systems in the three species, as no species-specific microbiota is detected. This study presents a significant advance in knowledge on the composition and structure of the avian ejaculate microbiota
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
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
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
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