1,721,002 research outputs found
Blow-up in non homogeneous Lie groups and rectifiability,
No full textIn this paper we extend the De Giorgi notion of rectifiability of surfaces in non homogeneous Lie groups. This notion and the principal properties of Cacciopoli sets had already been proved in homogeneous Lie group, using a blow-up method, with respect to the natural dilations. In non homogeneous Lie groups no dilations are defined, so that we need to apply a freezing method, locally approximating the non homogeneous structure, with an homogeneous one
Constant mean curvature graphs on exterior domains of the hyperbolic plane
No full textWe prove an existence result for non rotational constant mean curvature ends in H2 ×R, where H2 is the hyperbolic real plane. The value of the curvature is h ∈ (0, 12). We use Schauder theory and a continuity method for solution of the prescribed mean curvature equation of exterior domains of H2. We also prove a fine property of the asymptotic behavior of the rotational ends introduced by Sa Earp and Toubiana
Uniform Estimates of the fundamental solution for a family of hypoelliptic operators
No full textIn this paper we are concerned with a family of elliptic operators L-epsilon represented as sum of square vector fields, whose limit is an Hormander type operator L. It is well known that each operator L_epsilon
admits a fundamental solution. Here we establish a priori estimates uniform in epsilon of the fundamental solution, using a generalization
of the freezing and lifting technique of Rothschild and Stein. As
a consequence we deduce some a priori estimates uniform in epsilon,
for solutions of the approximated equation. These
estimates can be used in particular while studying regularity of
viscosity solutions of nonlinear equations represented in terms of
vector fields
Geometric Methods in PDE's: a conference on the occasion of the 65th birthday of Ermanno Lanconelli
No full textThe scope of this conference has been to celebrate the 65th birthday of Ermanno Lanconelli and to bring together italian and foreign Mathematicians to promote the discussion in the areas of research where Ermanno Lanconelli has been particularly active:- Second order linear and nonlinear partial differential equations with non-negative characteristic form- Geometric problems related to the underlying algebraic, geometrical or topological structure- Application to complex geometry and CR manifoldsThese fields are the objects of active research and development, and possess a remarkable degree of interrelation in their pure and applied aspects. In particular they find natural applications in mathematical finance, in the description of the visual cortex and in image processing
Implicit function theorem in Carnot-Caratheodory spaces
No full textIn this paper we study the notion of regular surface in non homogeneous Lie groups. In
particular we prove an implicitly function theorem and prove the
regularity of the function implicitly defined. Indeed the
implicit function theorem had already been proved in homogeneous
Lie groups by [FSS], while the regularity problem of the function
implicitly defined was still open even in the simplest Lie group
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
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
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