1,722,226 research outputs found
Development of molecular analytical methods for in situ detection of marine organisms using microfluidic biological sensor technologies
No full textHealthy seas are crucial for the protection of public health and to maximise the economic benefit from the use of the ocean for food production (including from aquaculture), resources, pharmaceuticals, and tourism. Sporadic occurrences of marine harmful algal blooms (HABs), however, can bring calamity to both the health and economic well-being of communities and businesses. In particular, toxigenic blooms can lead to significant harm to marine species and ecosystems, as well as human health and maritime industries. Pseudo-nitzschia is a genus of marine microalgae, belonging to the diatom group, which have been identified as a significant risk to human health and a contributor to ecological degradation from HABs. This is due to the production of domoic acid, a potent neurotoxin that is toxic to marine organisms and mammals. Early detection of domoic acid-producing blooms is necessary to minimise exposure. However, existing methods for discerning Pseudo-nitzschia abundance and the associated risks are long and protracted, labour-intensive and expensive. Pseudo-nitzschia blooms. Subsequently, a suite of novel isothermal assays targeting the dabD gene of Pseudo-nitzschia spp., which is linked to toxin biosynthesis, were designed utilising the LAMP and RPA chemistries. The LAMP assay outperformed the RPA assay in sensitivity and specificity, and its potential use for statutory algal surveillance was demonstrated by measuring Pseudo-nitzschia DNA in seawater samples collected over six months from a known HAB hotspot. To support the potential integration of the novel assays with fieldable instrumentation, a novel ‘Vitrification’ technique was developed for the simple and fast preservation and dry storage of complete reaction mixtures. The ‘shelf-life’ of the preserved reactions was at least six months at room temperature and represents a host of improvements upon existing methods. There were no significant differences in quantification performance between the dry-preserved reagents and freshly prepared reactions that relied on cold- chain-dependent, wet reagents. Finally, a new LOC system referred to as "LAMPTRON" was designed and fabricated from scratch, and developed for real-time detection and quantification of P. multistriata cells in a semi-autonomous fashion. LAMPTRON demonstrates a proof-of-concept for integrating automated DNA extraction with fully preserved DNA analysis, enabling the sensitive detection of toxigenic P. multistriata in a comparable timeframe to the leading commercial systems. These advances offer a faster, more sensitive, and simplified molecular analysis compared to existing statutory surveillance methods, which rely on costly reagents, sophisticated equipment, highly skilled personnel, and centralised laboratories. The ability to detect and quantify Pseudo-nitzschia cells using LOC technology could be modified towards a plethora of microbiological and eDNA targets for the surveillance and early warning of biohazards in aquatic environments. Implementing an early warning system using the state of the art in analytical methods will improve response times, improve accuracy and reduce cost; ultimately this will mitigate risk. Molecular analytical techniques, particularly those based on nucleic acid (DNA or RNA) sequence amplification, are widely adopted in food and water quality assessment, public health protection, and environmental monitoring. These methods can be coupled with portable or deployable instrumentation to provide high integrity, laboratory-quality or better metrology in resource-limited settings. In particular, microfluidic 'lab-on-a-chip' (LOC) technology is at the forefront of de-centralised nucleic acid testing and offers advantages such as reduced reagent and energy consumption, ease of use, rapidity, and stability, all while maintaining high levels of specificity, sensitivity, and precision. Automation of these systems makes analysis possible for non-specialist end-users, increasing their scope of application. This study was undertaken to explore new methods and technology for nucleic acid-based detection of Pseudo-nitzschia towards the provision of an integrated early warning system. It began with the design and testing of novel qPCR-based assay for Pseudo-nitzschia spp. detection and quantification. Then, the assay was combined with a reverse transcription step to investigate RNA-based (gene expression) responses in nutrient-depleted P. multistriata cells to the addition of essential nutrients phosphate, nitrate, and silicate. Nutrient availability was found to significantly influence domoic acid production, highlighting the relationship between nutrient availability and the toxic threat posed by Pseudo-nitzschia blooms. Subsequently, a suite of novel isothermal assays targeting the dabD gene of Pseudo-nitzschia spp., which is linked to toxin biosynthesis, were designed utilising the LAMP and RPA chemistries. The LAMP assay outperformed the RPA assay in sensitivity and specificity, and its potential use for statutory algal surveillance was demonstrated by measuring Pseudo-nitzschia DNA in seawater samples collected over six months from a known HAB hotspot. To support the potential integration of the novel assays with fieldable instrumentation, a novel ‘Vitrification’ technique was developed for the simple and fast preservation and dry storage of complete reaction mixtures. The ‘shelf-life’ of the preserved reactions was at least six months at room temperature and represents a host of improvements upon existing methods. There were no significant differences in quantification performance between the dry-preserved reagents and freshly prepared reactions that relied on cold- chain-dependent, wet reagents. Finally, a new LOC system referred to as "LAMPTRON" was designed and fabricated from scratch, and developed for real-time detection and quantification of P. multistriata cells in a semi-autonomous fashion. LAMPTRON demonstrates a proof-of-concept for integrating automated DNA extraction with fully preserved DNA analysis, enabling the sensitive detection of toxigenic P. multistriata in a comparable timeframe to the leading commercial systems. These advances offer a faster, more sensitive, and simplified molecular analysis compared to existing statutory surveillance methods, which rely on costly reagents, sophisticated equipment, highly skilled personnel, and centralised laboratories. The ability to detect and quantify Pseudo-nitzschia cells using LOC technology could be modified towards a plethora of microbiological and eDNA targets for the surveillance and early warning of biohazards in aquatic environments. <br/
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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