1,720,959 research outputs found
Fracture Evolution in the Niobrara Chalks of the Castle Rock Area, west-central Kansas
No full textCastle Rock is a predominantly north-south exposure of the Cretaceous age of Niobrara Chalks. At this location, multiple structural features are visible for analysis and interpretation, including normal faults, veins (opening fracture with mineralization), and joints (unmineralized opening fracture), from which a history of deformation can be constructed. In the middle of the continent, such deformations are uncommon and faults can suggest a potential seismic risk. The faults cut through both the lower and upper chalk units, are filled with calcite slickensides, and are oriented mostly east-west, but with significant variability. All faults were normal faults, which are associated with local extension. Vertical fault offsets varied from centimeters to meters. Two joint sets were mapped in the study area: longitudinal joints striking SE-NW, and cross joints striking SW-NE. A cross cutting relationship suggests that joints are more recent than faults. The veins are predominantly found in the lower part of the exposed stratigraphy, are typically dish/bowl shaped in cross section with sub-horizontal bases, and have a preferred orientation. We conclude that there were at least three distinct periods of deformation each forming the different types of fractures. The different episodes of deformations and orientations may be due to changes in the stress field associated with North American plate tectonics. There is also a possibility that fracturing occurred during sediment burial and due to compaction, de-watering and mineralogical changes. The veins may be due to modern weathering and topography
NUMERICAL MODELING OF THE EFFECTS OF LAND USE CHANGE AND IRRIGATION ON STREAMFLOW DEPLETION OF FRENCHMAN CREEK, NEBRASKA
Get PDFA three-dimensional Control Volume Finite Difference-based numerical groundwater flow model was constructed to assess the effects of agricultural irrigation and land use change on streamflow depletion. The study area is Frenchman Creek basin located in southwestern corner of the State of Nebraska, USA. This area was subject to an increased proliferation of groundwater abstraction for agricultural purposes since industrial revolution. It has also been subject to land use change from native rangeland to dry and irrigated cropland. The groundwater flow model was spatially discretized using Voronoi cells in unstructured grid built with the USGS MODFLOW-6. Temporal discretization defined 151 time steps with varying lengths and organized in 76 non-growing season time steps alternating with 75 growing season time steps and covering a period of 75 years. Results show that the combined application of irrigation and land use change over the study area consumed up to 98% of a portion of groundwater that would overwise discharge under the influence of ambient groundwater flow as baseflow to Frenchman Creek. A run of the model in base conditions, which consists of maintaining land use and irrigation constant from early stage, shows that anthropogenic activities curtailed the amount of groundwater discharge to evapotranspiration. The study also shows the advantage of using un-structurally discretized numerical model over previously developed analytical model by Traylor and Zlotnik in accounting for aquifer heterogeneity as well as spatial and temporal changes in transmissivity.
Advisor: Vitaly A Zlotni
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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