1,720,957 research outputs found
Nascent nitrifying community response to monochloramine exposure in drinking water
No full textNitrifiers autochthonous to drinking water distribution systems (DWDS) were enriched in separate ammonia-oxidizing Archaea (AOA), ammonia-oxidizing Bacteria (AOB) and nitrite-oxidizing Bacteria (NOB) enrichment cultures. A strategy was developed to selectively enrich AOA from DWDS biofilms containing both AOA and AOB, while new primers were designed to improve the quantification of the amoA and nxrB gene copies of AOA/AOB and NOB, respectively, using quantitative PCR and droplet digital PCR. Over several years, individual cultures containing AOA, AOB and NOB were enriched to 51.6 %, 71.2 % and 73.5 %, respectively. The nitrifiers were closely related to Nitrososphaera viennensis for AOA, Nitrosomonas oligotropha for AOB and Nitrospira moscoviensis for NOB. Under planktonic growth conditions, NOB were more resistant to monochloramine than AOA and AOB, and AOB were more resistant than AOA at lower monochloramine concentrations. Monochloramine also inactivated specific nitrifiers experimentally enriched in biofilms, but a small fraction of AOA or AOB cells persisted, likely due to the low concentration of free ammonia in the chloraminated bulk water. The persistence of AOA and AOB in the nitrifying biofilms after continuous exposure to monochloramine could be due to monochloramine cometabolism, where intracellular monochloramine was degraded by ammonia monooxygenase while also performing ammonia oxidation. This study is the first to address the effect of monochloramine on NOB and the regrowth potential of all three types of nitrifiers under planktonic conditions. By directly comparing monochloramine resistance under planktonic and biofilm conditions in the absence of other nitrifier groups fundamental insights were obtained on their respective roles in DWDS.Doctor of Philosoph
The role of ELKS isoforms in leptin and NF-κB signaling.
No full textObesity had been linked to a state of constant low-grade systemic inflammation, and
a series of metabolic disorders, like insulin insensitivity and leptin resistance. The
origin of the state of low-grade inflammation was tied to various adipocyte-secreted
adipokines, including leptin and TNF-α. One of the pathways of TNF-α signaling
leads to the activation of IKKβ/NF-κB signaling, of which the protein, ELKS, was
suspected to be involved. ELKS was hypothesized to be recruited in proximity to the
leptin receptor, upon consistent induction by low doses of TNF-α, and affect the
signaling pathway of the leptin receptor. ELKS was found to contribute to the
inhibition of POMC promoter activity, the downstream target of leptin signaling, but
did not affect the phosphorylation of STAT3, the secondary messenger of leptin
receptor. ELKS’ interaction with IKKβ was confirmed, affirming the hypothesis of
ELKS being co-recruited along with IKKβ. ELKS’ interaction with STAT3 was also
observed, suggesting the role of physical interaction in the inhibition of STAT3
downstream activities. Although the observations reported might not be sufficiently
conclusive, this study should receive further investigation to better illustrate ELKS’
role in leptin resistance, in the environment of low-grade inflammation.Bachelor of Science in Biological Science
Nitrifying niche differentiation in biofilms from full-scale chloraminated drinking water distribution system
No full textTropical conditions favor the auto-decomposition of monochloramine (MCA) leading to disinfectant decay and free ammonia in drinking water distribution systems (DWDS); thus, they promote the growth of nitrifiers and the development of biofilms on the inner-pipe surface. Biofilms can adversely impact the provision of safe and biologically stable water. Moreover, there is a general lack of understanding of the role of microbial communities in DWDS in regions with warm temperatures and no distinct seasons. Here, we report a survey on biofilms from full-scale monochloraminated DWDS in a highly urbanised metropolis using next generation sequencing tools. The monitoring campaign consisted of sampling biofilms and bulk waters from 21 in-service pipes. We characterized the microbial community with emphasis on nitrifying bacteria and archaea using 16S rRNA gene amplicon sequencing and potential nitrification activity. Samples grouped into two clusters, characterized by their low (Cluster LD) and high (Cluster HD) α-diversity. Both clusters harbour microorganisms related to nitrification: i) Nitrosomonas (24.9?68.8%), an ammonia oxidising bacterium (AOB) that dominated Cluster LD, and ii) a co-aggregation of genus Nitrospira (9.8?32.5%), a nitrite oxidising bacterium (NOB), and Thaumarchaeota (1.4?10.9%), chemolithotrophic ammonia oxidising (AOA) archaea that were among the most abundant OTUs in Cluster HD. Activity tests performed with fresh biofilm samples confirmed that these two clusters represent distinctive biofilm niches performing different stages of the nitrification process. Cluster LD correlated with a high concentration of MCA, which caused dysbiosis and resulted in high unevenness of the cluster. In cluster HD, with higher biomass, chemical reactions involving nitrite increased the MCA demand, releasing ammonia and allowing more bacteria to grow, like AOA and NOB. From this study, we conclude that an MCA residual gradient along the DWDS drives and shapes the microbial community assembly and should be considered when designing effective disinfection strategiesFil: Cruz, Mercedes Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Nanyang Technological University; SingapurFil: Woo, Yissue. Nanyang Technological University; SingapurFil: Fleming, Hans Curt. Nanyang Technological University; SingapurFil: Wuertz, Stefan. Nanyang Technological University; Singapu
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
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