1,720,979 research outputs found
Homogenization of forward-backward parabolic equations
No full textWe study the homogenization of the equation R(\eps^{-1}x){\partial u_{\eps} \over\partial t}-\Delta u_{\eps} = f where is a periodic function which may vanish or change sign, with appropriate initial/final conditions. The main tool is a compactness result for sequences of functions which have bounded norms in the spaces associated to the problems
Analytic semigroups generated in L^1 by second order elliptic operators via duality methods
No full textHeat semigroup and functions of bounded variation on Riemannian manifolds
No full textLet M be a connected Riemannian manifold with Ricci curvature
bounded from below and such that the volume of the geodesic balls of centre x and fixed radius r > 0 have a volume bounded away from 0 uniformly with respect to x, and let T(t) be the heat semigroup on M. We show that the total variation of the gradient
of a function u in L^1 equals the limit of the L^1 norm of T(t)u as t goes to 0. In particular, this limit is finite if and only if u is a function of bounded variation
On a characterisation of perimeters in R\sp N via heat semigroup
No full textIl presente lavoro e' il riassunto di un lavoro precedente degli autori stessi ed e' il riassunto presentato in forma di poster al convegno ``The Renato Caccioppoli Centenary Conference'', tenutosi a Napoli (ITALIA) dal 23--25 settembre 2004.
Viene presentata la relazione per tempi piccoli tra la teoria dei semigruppi e la teoria dei perimetri utilizzando un funzionale di tipo diffusione
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
Homogenization of changing-type evolution equations
No full textIn this paper we study the homogenization of the linear equation R(ε(-1)x) &PARTIAL; u(ε)/&PARTIAL; t - div(a(ε(-1)x) (.) &DEL; u(ε)) = f, with appropriate initial/final conditions, where R is a measurable bounded periodic function and a is a bounded uniformly elliptic matrix, whose coefficients a(ij) are measurable periodic functions. Since we admit that R may vanish and change sign, the usual compactness of the solutions in L-2 may not hold if the mean value of R is zero
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
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