1,720,967 research outputs found
Belousov-zhabotinskii Oscillations In A Batch Reactor
No full textThe oscillations of the Belousov-Zhabotinskii reaction in a batch reactor vanish due to the consumption of the main reactants, i.e. bromate and malonic acid. This behavior has been analyzed first using the classical Oregonator model, where reactant concentrations are kept constant, and then introducing a modified model, in which the reactant concentration is allowed to vary according to the stoichiometry of the considered set of chemical reactions. Two different routes to the extinction of oscillations have been found, depending on whether the Oregonator exhibits a subcritical or a supercritical Hopf bifurcation. These theoretical findings are consistent with the experimental observations, that indicate that the disappearance of the oscillations takes place in two rather different ways: either suddenly after a series of practically undamped oscillations or through very slowly damped oscillations
Bifurcation-analysis of the Oregonator Model In the 3-d Space Bromate Malonic-acid Stoichiometric Coefficient
No full textBy considering the classical Oregonator model, the effect of the main reactants, i.e., bromate and malonic acid, on the behavior of the Belousov-Zhabotinskii system is studied. This analysis is a prerequisite for the understanding of the occurrence and disappearance of oscillations in batch reactors. A parametric analysis of the Oregonator in the three-dimensional space spanned by the bromate concentration, the malonic acid concentration, and the stoichiometric coefficient f is performed. Through asymptotic stability analysis the Hopf bifurcation set in the parameter space is determined analytically, whereas its character is defined through normal form analysis. In this study the most plausible values of the kinetic parameters, namely the ''Lo'' values proposed by Tyson (Tyson, J. J. In Oscillations and Traveling Waves in Chemical Systems; Field, R. J., Burger, M., Eds.; Wiley-Interscience: New York, 1985), are used. The system may exhibit both sub- and supercritical Hopf bifurcations, and near the latter the phenomenon of canard explosion has been observed. The results obtained with the ''Hi'' values are also reported for a comparison with previous studies in the literature
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
- …
