1,720,995 research outputs found
Poliedri: non solo geometria
No full textTema del congresso: "I dintorni dell'insegnamento della matematica: percorsi, strumenti, aspetti motivazionali, atteggiamenti. Il caso della geometria
Variational models for phase separation
No full textThe paper deals with the asymptotic behaviour of a family of integral functionals in the framework of phase separation. In order to obtain a selection criterion for the minima of the usual double-well, non-convex free energy involving the phase-variable u, we add a gradient term in a new variable v which is related to u through the L2-distance between u and v, weighted by a coefficient α. We prove that the limit is a minimal area model with a surface tension of non-local form. The well-known Modica-Mortola constant can be recovered in this setting as a limit case when α tends to infinity
Non-local approximation of free discontinuity functionals with linear growth: the one dimensional case
No full textWe approximate, in the sense of Gamma-convergence, one-dimensional free-discontinuity functionals with linear growth in the gradient by means of a sequence of non-local integral functionals depending on the averages of the gradient on small intervals
Variational evolution of one dimensional Lennard-Jones systems
No full textWe analyze Lennard-Jones systems from the standpoint of variational principles beyond the static framework. In a one-dimensional setting
such systems have already been shown to be equivalent to energies of Fracture Mechanics. Here we show that this equivalence can also be given in dynamical terms using the notion of minimizing movements
NON LOCAL APPROXIMATION OF FREE DISCONTINUITY PROBLEMS WITH LINEAR GROWTH
No full textWe approximate, in the sense of
Gamma-convergence, free-discontinuity functionals with linear
growth in the gradient by a sequence of non-local integral
functionals depending on the average of the gradients on small
balls. The result extends to higher dimension what we already proved in
the one-dimensional case
Poliedri: non solo geometria.
No full textLe attività descritte si propongono di avvicinare gli studenti a un tema, la geometria dello spazio, che è poco sviluppato nella programmazione didattica, nonostante il carattere “concreto” che sembra vantare a confronto di altri settori della matematica. Si evidenzia l'opportunità offerta dalla tematica per attivare utili collegamenti interdisciplinari a differenti livelli di profondità.
Si espongono i contenuti principali presi a riferimento nella progettazione e nello svolgimento del laboratorio, si descrivono alcuni aspetti rilevanti della loro implementazione didattica, si descrivono gli esiti che sono parsi maggiormente significativi. Si conclude con alcune note sulla modalità adottata nella collaborazione con gli insegnanti delle classi del Liceo Scientifico “N. Copernico” in cui si è svolta l’esperienza di laboratorio, nell'ambito del progetto "Lauree scientifiche" sviluppato a Pavia
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
Variational evolution of discrete one-dimensional second-order functionals
Full text linkA variational scheme of evolution (minimizing movements) is applied to a sequence of discrete functionals converging, as the mesh size tends to zero, to the prototypical second-order functional with free-discontinuities. At fixed mesh size, a discrete evolution can be defined, depending on a (small) time parameter. We study the limit problem when both the mesh size and the time step tend to zero. The method provides a function which matches the expected evolution of the free-discontinuity limit functional. From a mechanical point of view, the model can be interpreted as the evolution from a non-equilibrium state, of a rod with possible crease discontinuities and fracture
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
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