1,721,133 research outputs found
Positive eigenvectors and simple nonlinear maps
Full text linkFor linear operators L,T and nonlinear maps P, we describe classes of simple maps F = I −PT, F = L−P between Banach and Hilbert spaces, for which no point has more than two preimages. The classes encompass known examples (homeomorphisms, global folds) and the weaker, geometric, hypotheses suggest new ones. The operator L may be the Laplacian with various boundary conditions, as in the original Ambrosetti-Prodi the- orem, or the operators associated with the quantum harmonic oscillator, the hydrogen atom, a spectral fractional Laplacian, elliptic operators in non-divergent form. The maps P include the Nemitskii map P(u) = f(u) but may be non-local, even non-variational. For self-adjoint operators L, we employ familiar results on the nondegeneracy of the ground state. On Banach spaces, we use a variation of the Krein-Rutman theorem
Removal of xenobiotics in a two phase sequencing batch reactor: kinetics and modelling
No full textThe objectives of the paper are to verify the potentialities of a sequential two phase partitioning bioreactor in degrading xenobiotics and to evaluate the kinetic parameters for modelling the system. The target compound investigated was the 4-nitrophenol. Preliminary tests were carried out to define the solvent most appropriate for the compound. Among the three investigated solvents 1-undecanol, 2-undecanon and oleyl alcohol, the 2-undecanon was chosen because of the higher partition coefficient of 30 and the negligible formation of emulsions. Moreover, the tested solvent showed satisfactory "biocompatibility" characteristics for the biomass with minor effects on the intrinsic kinetics. Parallel batch kinetic tests were then performed with the conventional one phase and the two phase systems. In the two phase system the biomass is exposed for all the time to 4NP concentrations that are significantly lower if compared to the conventional system and, for the highest concentration (450 mg/l) in the two phase system a reduction of the reaction time is observed depending on the biomass concentration. Kinetic parameters were also evaluated in both cases by fitting of the experimental data with a modified form of the Haldane equation
Cusps and a converse to the Ambrosetti-Prodi Theorem
No full textBy the Ambrosetti-Prodi theorem, the map F(u) = \Delta u - f (u) between appropriate functional spaces is a global fold. Among the hypotheses, the convexity of the function f is required. We show in two different ways that convexity is indeed necessary. If f is not convex, there is a point with at least four preimages under F. Even more, F generically admits cusps among its critical points. We present a larger class of nonlinearities f for which the critical set of F has cusps. The results are true for Dirichlet, Neumann and periodic boundary conditions, among others
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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