1,720,957 research outputs found
Composition and Textural Characteristics of Turonian Ezeaku Formation: Implication for Depositional Environment
Get PDFThe depositional environment of the Ezeaku Sandstone outcropping as Amasiri Sandstone in Afikpo Basin in the southeastern part of the Benue Trough was studied using the composition and textural characteristics of the Sandstone. Samples were collected from the Ibii, Ozara-Ukwu, Akpoha, Amasiri-Akpoeze ridges for petrographic and chemical analyses. The results show that the sandstones are feldspathic arenites with matric content less than 15%. Quartz is the most ubiquitous mineral with micro fractures; also, grain margins and surfaces are corroded and altered by calcite. Euhedral quartz overgrowth is seen with dust rim. The grains are angular to sub rounded, elongate grains were also common. Sorting is poor. Plagioclase and alkaline feldspars were observed, they have a modal composition of about 10 – 12%. Rock fragments were not common in the Ezeaku Formation. The grains were seen to be cemented mainly by calcite cement, silica cement also occur as quartz overgrowth and microcrystalline aggregates. Clay minerals and iron oxides are seen coating grains. The sandstone is compositionally and texturally sub mature. The chemical analysis shows the depletion of silica as a result of calcite replacement in the calcareous sandstone and concretions. Al2O3 value is high and it ranges from 9.766% to 23.55%. The sandstone is richer in K2O than in N2O, which is typical of arkoses. The results show that the Amasiri Sandstone was deposited in a shallow marine environment under humid conditions that allowed the segregation of calcite minerals into concretions within the Sandstone. Keywords: Petrography, Calcareous sandstone, Calcareous concretions, Diagenesis, Paragenetic sequence, Sandstone composition, Plate Tectonic
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
GIS & Remote Sensing Based Morphometric Parameters and Topographic Changes of the Lower Orashi River in Niger Delta
No full textIn watershed hydrology, the morphometric features of a river basin are vital to examine the lower Orashi River basin morphological and hydrological aspects, as well as its flood potential, based on their morphometric characteristics using remotely sensed SRTM data that was analyzed with ArcGIS software. The areal, linear, and relief aspects of the Orashi River basin were examined as morphometric parameters. The lower Orashi river basin, according to the findings, has a total size of 625.61 km2 and a perimeter of 307.98 km, with a 5th order river network based on Strahler categorization and a dendritic drainage pattern. Because of low drainage density, the drainage texture is very fine, the relief is low, and the slope is very low. Bifurcation ratio, circularity ratio, drainage density aspect ratio, form factor, and stream frequency values indicate that the basin is less elongated and would produce surface runoff for a longer period, while topographic changes show that the river is decreasing with depth in the land area at about the same elevation as a result of sand deposited due to lack of maintenance by dredging, which implies that the basin is morphometrically elevated and sensitive to erosion and flooding. To understand geohydrological features and to plan and manage watersheds, morphometric analysis based on geographic information systems and remote sensing techniques is beneficial
Petrography of Ajali Sandstone in Ayogwiri – Fugar – Orame Area of Western Anambra Basin: Implication for Diagenetic and Depositional History.
Get PDFThe friability of the Ajali Sandstone was studied with photomicrographs of thin sections made from samples collected from the Formation in Ayogwiri, Fugar and Orame in the Western Anambra Basin in order to understand its diagenetic and depositional implications. This study shows that the Ajali Sandstone is a quartz arenite consisting of subangular to subrounded grains of quartz which were either monocrystalline or polycrystalline. Diagenetic fabrics of compaction, dissolution, alteration and corrosion were common features. Straition marks, fracture lines, some of which show filling, stress zonation were major compaction fabrics in the Sandstone. Authigenic quartz formed from the dissolution and recrystallization of quartz grains as well as quartz overgrowth occur. Reaction rims around grain margins indicating severe alteration and corrosion were seen growing from grain margins inward, leaving the Sandstone, which may have been indurated with little or no cementing material. Thus leading to the friability of the Sandstone and it’s susceptibility to erosion. Keywords: Petrography, Diagenesis, Authigenesis, Decementation, Cementation, Dissolution, Alteration, Corrosion
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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