1,720,967 research outputs found
On a model for the evolution of morphogens in growing tissue III: θ
No full textA model for the regulation of growth and patterning in developing tissues by diffusing morphogens is analyzed. The well-posedness of the underlying systems of nonlinear PDEs is proved. The transformation of the underlying system to an equation with very fast diffusion is the key tool in the analysis
On a Dirichlet problem in bounded domains with singular nonlinearity
No full textIn this paper we prove the existence and regularity of positive solutions of the homogeneous Dirichlet problem
−∆u = g(x, u) in Ω, u = 0 on ∂ Ω,
where g(x, u) can be singular as u
→ 0+ and 0 ≤ g(x, u) ≤ φ0 (x) up or 0 ≤ g(x, u) ≤ φ0 (x)(1 + 1/u^p ), with φ_0∈ L^m(Ω), 1≤ m. There are no assumptions on the monotonicity of g(x, ·) and the existence of super- or sub-solutions
On the summability of weak solutions for a singular Dirichlet problem in bounded domains
No full textIn this paper we prove the existence of positive weak solutions for the homogeneous Dirichlet problem associated to the equation
\begin{equation*}
-\Delta u=f(x,u)+\lambda h(x,u),\quad \text{in } \Omega,
\end{equation*}
where
can be singular as
and can diverge as
We assume that
with
and
with
We do not have any monotonicity assumption on and
Moreover, we do not assume the existence of any super or sub solution
On a singular limit as for a model for the evolution of morphogens in a growing tissue
No full textThis paper is devoted to the singular limit of a model for the regulation of growth and patterning in developing tissues by diffusing morphogens. The model is governed by a system of nonlinear PDEs. The arguments are based on energy estimates and a change of variable that reduces the system into a nonlinear PDE with singular diffusion
Long time behavior of a model for the evolution of morphogens in a growing tissue II: θ
Full text linkWe consider a model for the regulation of growth and patterning in developing tissues by diffusing morphogens expressed in terms of a system of nonlinear PDEs. Transforming such a system in an equation with singular diffusion we analyze its long time behavior
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
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