1,720,983 research outputs found
Variational problems and partial differential equations on implicit surfaces: The framework and examples in image processing and pattern formation
No full textBertalmio, Marcelo; Cheng, Li-Tien; Osher, Stanley; Guillermo, Sapiro. (2000). Variational problems and partial differential equations on implicit surfaces: The framework and examples in image processing and pattern formation. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/3470
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Efficient Grid-Based Algorithms for Visibility Problem in Level Set Framework
Full text linkThis research explores the static visibility problem, focusing on identifying visible regions in environments with fixed obstacles and a stationary viewpoint. The problem is formulated as the determination of visibility boundaries within the level set framework. To address this, a novel grid-based algorithm is introduced, designed to improve computational efficiency while maintaining high accuracy. This method integrates phase flow techniques, enables localized computations near the visibility interface with the growing method, and further reduces the computational burden associated with high-resolution grids with tube structures. Additionally, a new Heaviside function approximation, inspired by advanced Delta function methodologies, is proposed. This approach is conjectured to have second-order accuracy in calculating the volume of visibility regions. All accuracy and computational workload considerations are verified through numerical experiments
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Fast and Efficient Numerical Methods in Level-Set Variational Implicit Solvent Model
Full text linkThe level-set method (LS) is a widely-used and powerful tool for capturing moving interfaces under complex dynamics in fields ranging from two-phase flow to image segmentation. It has recently been successfully applied, in the Variational Implicit Solvent Model (VISM), to find the “shape” of a biomolecule, the interface separating the solute atoms of a biomolecule from the surrounding solvent. In the introduces fast and efficient numerical methods for the application of the level-set method to VISM (LS-VISM), and can be boiled down to two major contributions. The first of these involves the implementation and analysis of a more discrete binary level-set method in LS-VISM that replaces traditional continuous level-set functions with binary ones, and traditional partial differential equation solvers with discrete “flips” that minimize the free energy of the system. This results in vast improvements in speed, with runtime decreasing from hours to seconds, which ultimately allowed for its application in Monte Carlo simulations of the protein binding process. The second contribution in my thesis involves the construction and analysis of the Compact Coupling Interface Method (CCIM), a finite difference method for elliptic interface problems with interfacial jump conditions. This method is able to robustly and accurately calculate values of not only the solution but its derivative as well, which ultimately allows for the accurate handling of electrostatic contributions of the solute and solvent in LS-VISM, which take this form as linearized Poisson-Boltzmann equations with discontinuous dielectric constants across the interface
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
Dispelling 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
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