1,720,956 research outputs found
Dataset in support of the thesis 'Morphological evolution of wave-influenced deltas: Empirical and model analyses'
No full textAnalysis of numerical modelling results
Model image and analysis</span
Morphological evolution of wave-influenced deltas: Empirical and model analyses
No full textRiver deltas are dynamic geomorphological features known for their immense natural resource potentials; they are hotspots of population concentration and form some of the most biodiverse environments when in pristine form. However, they also comprise some of the most vulnerable coastal environments, heavily threatened by anthropogenic activity and climatic changes. In response to current threats, some deltas are experiencing large-scale coastline retreat, flooding, saline intrusion, and depletion of the wetland ecosystems. Dealing with these threats requires an improved understanding of the dynamic interplay between multiple processes that govern delta evolution as well as deltas’ response to external disturbances. In this thesis, I aimed to deepen insight into the dynamic changes in coastal delta morphology in response to changes in key boundary conditions, specifically fluvial discharge, and waves. The thesis has focused on four research questions, using the Niger deltas as a case study: (i) What are the contemporary trends in the natural and anthropogenic factors governing river delta dynamics? (ii) What changes can we observe in the shoreline mobility of the Niger delta in recent decades? (iii) What has been the trends in recent fluvial discharge and wave regimes along the Niger delta, and might these trends be associated with the observed morphological changes? (iv) Is it possible to identify the relative efficacy of river flow vs waves in dictating delta evolution under changing climatic conditions with numerical simulation? The review of the dynamics and sustainability of river deltas established the importance of sediment supply and distribution as well as the impact of contemporary anthropogenic-induced processes and ongoing climatic changes on deltaic morphological evolution. The study also revealed that recent decadal shoreline dynamics along the Niger delta lacked any entrenched spatial and temporal patterns, leading to the suggestion that current anthropogenic impact on the delta is moderate. The effect of natural process dynamics on deltaic shoreline mobility could not be directly inferred notwithstanding the recent increasing trends in both fluvial inputs and wave energy intensity into the Niger delta. The novel numerical model developed in this thesis elucidated how the dynamic coupling between ocean waves and fluvial processes informs the longshore sediment flux, progradation, aggradation, and patterns of channel migration in coastal delta settings. Overall, this thesis has made significant advances in the understanding of morphological evolution of deltas significantly influenced by fluvial and marine processes at yearly to decadal timescales
Spatial and temporal variations in shoreline changes of the Niger Delta during 1986–2019
No full textThe purpose of this study was to analyse the shoreline movement of the Niger delta, specifically focusing on the spatial pattern of the delta’s shoreline behaviour during 1986–2019. We employed satellite data of medium spatial resolution (20–30 m) to delimit the delta shorelines representing specific time in order to determine the rates of the delta shoreline migration. Our results show that the delta shoreline has changed nearly in equal proportion between erosion (50.3%) and accretion (49.7%), at mean (maximum) rates of 3.9 m/yr. (26 m/yr.) of erosion, and 4.0 m/yr.(27 m/yr.) of accretion. Further analysis indicates that the highest shoreline migration is seaward (>200 m) though the ratio of the shoreline distance in recession (54%) exceeds that which is in accretion. Our analysis did not reveal any entrenched spatial pattern of shoreline behaviour but rather highlights a random occurrence of hotspots in both shoreline erosion and accretion over spaceand time. We have also showed that by applying the statistical mean-removed shoreline approach, the overall trend of a delta shoreline movement can be vividly discriminated. In conclusion, since the Niger delta shoreline dynamics is most intense at the delta river mouths, we suggest this is likely due to the interaction between waves and river discharge in these locations.<br/
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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