1,720,964 research outputs found
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
Quantifying River Change from Historical Maps: Hydromorphological Metrics for Freshwater Ecosystem Management
No full textThe landscape changes observed in freshwater ecosystems are far greater than the most affected terrestrial ecosystems. In light of this, historical landscape changes have increasingly been incorporated into efforts of river restoration and conservation as they form a foundation on which river modifications have built.
In order to incorporate historical landscape changes, the information from historic sources need to be extracted, quantified, and analyzed in terms of freshwater ecosystem management. Historical maps form a unique information source to study landscape changes and, in conjunction with machine learning and GIScience techniques, the multi-temporal depth of landscape changes embedded in historical maps can be unlocked. Through an overarching project known as “HistoRiCH: Historical river change,” hydrological and hydromorphological features, such as rivers or wetlands, are extracted from Switzerland’s historic Siegfried and old National Map for further analysis. This thesis develops and applies ecologically relevant metrics from these extracted features with the goal to quantify the structures and functions of selected freshwater ecosystems in context of further application for effective management. The conducted research is thus driven by four core questions pertaining to the quantitative metrics developed and applied to capture the environments’ structure and function, the geoprocessing workflow developed and tested for optimal information gain, the data quality and uncertainty issues that arise, and lastly the implications made in terms of freshwater ecosystem management. Methodologically, this thesis contributes by developing and applying various ecologically relevant metrics through geoprocessing techniques. These metrics are derived using Python-based scripts in Jupyter Notebooks and by use of Geographic Information Systems (GIS). Spatial-temporal analyses quantify riverine environments at selected locations. Given the inherent noisiness and challenges of historical maps, data quality and uncertainty are meticulously considered throughout the metric derivation process.
The main contribution of this thesis consists in the conceptualization, development, implementation, and evaluation of ecological metrics that quantify historic freshwater environments. First, ecologically relevant metrics are dismantled and novel adaptations to metrics are conceptualized. Second, a detailed, small-scale, method to measure river channel width is developed as a static metric, followed by the development of a complex multi-temporal metric decomposing pixel evolution vectors under consideration of model-inherent uncertainty. Further methods were developed to quantify surface hydrological connectivity of ten Swiss river catchments. The presented methods were tested and evaluated at ecohydrologically-relevant sites, such as the hydropower-regulated Sarine river. The developed scripts and tools for metric derivation are designed to be applicable to other sights and other data inputs within the field of GIScience, allowing them to be used further in studies of historical landscape changes and their subsequent application for river restoration and conservation. The thesis further contributes to the knowledge of utilizing historical maps for spatio-temporal analysis. Additionally, the thesis contributes to the fields of geographic information science and ecohydrology. The concepts and methods proposed in this thesis can be extended in various ways, especially in further characterization of past landscapes and their changes. The results found throughout the papers further underline the human modifications and alterations affecting riverine environments and results can directly benefit river re-naturalization efforts in Switzerland along some of the most impacted rivers.
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An investigation of the fidelity of records of past carbon dioxide variations in Greenland ice cores
Get PDFIce core records provide us a way to investigate past climate and look in detail at past atmospheric conditions. With, on average, higher CO2 concentrations in the Greenland record, the focus of this project was on the potential mechanisms responsible for the higher CO2 concentrations in the Greenland ice core record. Contamination in the ice is believed to be due to oxidation and dissolution processes, however, our results show no significant connection between the chemical processes in the ice and the higher CO2 concentrations
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
From Change Detection to Change Analytics: Decomposing Multi-Temporal Pixel Evolution Vectors (Short Paper)
Get PDFChange detection is a well-established process of detaining spatial and temporal changes of entities between two or more timesteps. Current advancements in digital map processing offer vast new sources of multitemporal geodata. As the temporal aspect gains complexity, the dismantling of detected changes on a pixel-based scale becomes a costly undertaking. In efforts to establish and preserve the evolution of detected changes in long time series, this paper presents a method that allows the decomposition of pixel evolution vectors into three dimensions of change, described as directed change, change variability, and change magnitude. The three dimensions of change compile to complex change analytics per individual pixels and offer a multi-faceted analysis of landscape changes on an ordinal scale. Finally, the integration of class confidence from learned uncertainty estimates illustrates the avenue to include uncertainty into the here presented change analytics, and the three dimensions of change are visualized in complex change maps
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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