1,721,045 research outputs found
Increased hydraulic roughness in alluvial rivers created by sand-mining sculpted bed features
No full textAlluvial bedforms are a first order control on flow resistance, water levels and rate of sediment transport. Their morphologies are a direct reflection of the hydraulic and sedimentological conditions under which they are formed. Studies of natural dunes in large river systems have shown that low angled dunes are dominant, characterized by reduced flow resistance and limited recirculation of flow in their lee-slopes. However, increasingly, alluvial rivers are influenced by human activities, such as sand extraction, that directly impact the morphologies of river beds and bedforms. Here, we present a comparison of the morphologies of natural and anthropogenically influenced bedforms observed through multibeam echo sounder surveys on the Mekong River in Cambodia. We show that anthropogenic bedforms have higher amplitudes (μ = 2.8 m, σ = 1.0 m), steeper leeside angles (μ = 20.6°, σ = 5.8°) and shorter wavelengths (μ = 100.1 m, σ = 87.9 m) compared to natural dunes (amplitude: μ = 1.79 m σ = 0.86 m, leeside angle: μ = 11.8° σ = 5.7°, wavelength: μ = 117.0 m, σ = 89.1 m). Our data suggests that the form roughness of anthropogenic bedforms is higher (median ksf = 1.23) than natural bedforms found in sections of the Mekong unaffected by mining (median ksf = 0.49). As a result, flow patterns subsequently force suspended load over bedforms, meaning sediment is unable to infill mining pits. Anthropogenic bedforms may represent a significant and previously under-represented control of flow and sediment transport in alluvial river systems
Assessing social vulnerability to riverbank erosion across the Vietnamese Mekong Delta
No full textClimate change and trans-boundary development in the major deltas of the world, including the Vietnamese Mekong Delta have exacerbated environmental risks. Land subsidence, riverbed sand mining, and intensive groundwater extraction have all contributed to lower channel bed levels, resulting in riverbank erosion and the loss of assets and livelihoods for local residents. This study investigated the drivers, and classified the social vulnerability of local communities affected by riverbank erosion along two main branches in the Vietnamese Mekong. Direct interviews were conducted with 218 erosion-affected households along the Mekong and Bassac rivers in Dong Thap and An Giang provinces in order to create a social vulnerability index. More than 70% of the total surveyed households belonged to the highly, moderately, or low vulnerability groups, suggesting a range of affected communities within the sample, some of whom had the ability to cope with its short-term impacts. However, the estimated social vulnerability index revealed significant geographical heterogeneity, with communities along the Mekong branch being more vulnerable than those along the Bassac. The recommendations from our investigations include the establishment of community awareness programmes, as well as policy changes that ensure and support local residents’ livelihoods adaptation. Stakeholder participation and enhanced community engagement was found to be the most important tools available in terms of aiding local people cope with the complex impacts of riverbank erosion
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
Mid to late Holocene geomorphological and sedimentological evolution of the fluvial-tidal zone: Lower Columbia River, WA/OR, USA
No full textDispelling 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
- …
