1,720,979 research outputs found
The engineering in beaver dams
No full textBefore their near extinction, beavers populated the smaller rivers in Eurasia and North America. Beavers are called ‘ecosystem engineers’, since their dam building activities dramatically change the character of river (flow characteristics, groundwater and morphology), river habitats and ecosystems. The largest dam currently in existence has a length of 850 m, raising the question of the engineering required for such large structures. A research programme was initiated at Southampton University to assess the engineering importance, and characteristics of beaver dams. It was found that the dams are built in rivers of up to 45 m width. They modify the flow duration curves, increasing ground water retention, reducing the gradient and sediment transport, trapping sediment and improving ecosystems. Model tests were conducted to investigate the strength and permeability of beaver dams. It was found that beavers employ interesting construction techniques, creating semi-permeable dams able to withstand flow volumes of up to 1.34 m3/s per meter width for a 1.4 m high dam. Beaver dam technology may allow to create novel, nature based solutions for ecosystem redevelopment and river renaturalisation
Not so rare snakes: a revision of theGeophis sieboldigroup (Colubridae: Dipsadinae) in lower Central America and Colombia
No full textFigure 9. Comparison of variation in total segmental counts in four population samples of the Geophis brachycephalus complex.Published as part of Savage, Jay M. & Watling, James I., 2008, Not so rare snakes: a revision of the Geophis sieboldi group (Colubridae: Dipsadinae) in lower Central America and Colombia, pp. 561-599 in Zoological Journal of the Linnean Society 153 (3) on page 576, DOI: 10.1111/j.1096-3642.2008.00400.x, http://zenodo.org/record/544614
Geophis nigroalbus Boulenger 1908
No full textGEOPHIS NIGROALBUS BOULENGER, 1908 Geophis nigroalbus Boulenger, 1908: 552 (Type locality: Colombia: Valle del Cauca: Pavas, 3°41′N, 76°35′W, 1350 m; Holotype BMNH 1946.1.6.50, a juvenile male); Restrepo & Wright, 1987: 195; Myers, 2003: 33, figs 15–17. Diagnostics: Distinguished from other species in the Geophis brachycephalus complex by the following combination of characters: (1) ventrals 134–143.5 ± 3.8–149 in males, 141–148.0 ± 5.2–157 in females; subcaudals 42–46.3 ± 2.1–51 in males, 37–41.3 ± 2.8–46 in females; total segmentals 180–190.0 ± 3.6– 197 in males, 181–189.3 ± 7.5–203 in females; (2) upper surfaces of body and tail uniform black; (3) hemipenis slightly bilobed with a long, slender capitulum about 3 times length of truncus (Myers, 2003). Distribution: Tropical premontane wet forest sites in the Cordillera Occidental of Colombia, 1350–1680 m (Fig. 16).Published as part of Savage, Jay M. & Watling, James I., 2008, Not so rare snakes: a revision of the Geophis sieboldi group (Colubridae: Dipsadinae) in lower Central America and Colombia, pp. 561-599 in Zoological Journal of the Linnean Society 153 (3) on page 584, DOI: 10.1111/j.1096-3642.2008.00400.x, http://zenodo.org/record/544614
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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