1,720,960 research outputs found
The impact of an Archimedes screw hydropower turbine on fish migration in a lowland river
No full textThere has been an increase in the abundance of small hydropower (< 10 MW) installations. These tend to be ‘run-of-river’, thereby reducing or averting the need for impoundment and water storage, and so are considered to have lower environmental impact. The Archimedes screw turbine (AST) has been described as ‘fish friendly’ based on magnitude of observed first order impacts, i.e. low rates of direct damage and mortality due to blade strike. However, potential second order effects, such as altered fish behaviour prior to or after passage, and
consequences for long-term survival and fitness, have been largely ignored. This two-year study employed acoustic and Passive Integrated Transponder (PIT) telemetry and dual frequency imaging sonar to investigate the influence of an AST and associated fish passes (Larinier super-active baffle pass and upstream eel ladders) on the movement patterns and behaviour of five species of potadromous fish and European eel (Anguilla anguilla). Seaward-migrating adult (silver) eels successfully descended the AST, but under high flows most individuals
took an alternative route via an overshot weir which resulted in faster passage rates. There was no immediate silver eel mortality as a result of passage through the turbine and no effect on subsequent migration behaviour through the lower freshwater catchment and estuary. Some eels were delayed at the complex and exhibited frequent rejection and milling on their approach to the AST and fish passes. Upstream passage rate (%) at the Larinier pass varied among species with highest for dace (81%) and the lowest for roach (10%). Fish that aggregated up- and downstream of the AST rapidly dispersed on turbine start-up. Although ASTs can be considered a potential downstream passage route for both eels and potadromous species, adult eels milled and rejected at the upstream entrance, while other fish exhibited startle response on turbine start-up. Potential delay
to seaward migration of silver eel and the energetic costs of observed behaviours should be considered during future impact assessments, particularly where there is no alternative migration route or there are multiple such facilities in a watercourse
Movement patterns of seaward migrating European eel (Anguilla Anguilla) at a complex of riverine barriers: implications for conservation
Full text linkRiver infrastructure such as weirs and hydropower stations commonly present migrating fish with multiple potential passage routes. Knowledge of the cues fish use to navigate such environments is required to protect migrants from hazardous areas and guide them towards safe passage; however, this is currently lacking for many species. Employing high-resolution positioning telemetry, this study examined movements of downstream migrating adult European eel, Anguilla anguilla, as they encountered a complex of water control structures in one location on the River Stour, southern England. The distribution of eels across five potential routes of passage differed from that predicted based on proportion of discharge alone. Certain routes were consistently avoided, even when the majority of flow passed through them. Passage distribution was partially explained by avoidance in the vicinity of a floating debris boom. Movement paths were nonrandomly distributed across the forebay and eels moved predominantly within a zone 2–4 m from the channel walls. Understanding of avoidance and structure oriented movementation exhibited by eels will help advance effective guidance and downstream passage solutions for adult
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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