1,721,195 research outputs found
Graphical evolution of the Arnold web: From order to chaos
No full textWe represent graphically the evolution of the set of resonances of a quasi-integrable dynamical system, the so-called Arnold web, whose structure is crucial for the stability properties of the system. The basis of our representation is the use of an original numerical method, whose definition is directly related to the dynamics of orbits, and the careful choice of a model system. We also show the transition from the Nekhoroshev stability regime to the Chirikov diffusive one, which is a generic nontrivial phenomenon occurring in many physical processes, such as slow chaotic transport in the asteroid belt and beam-beam interaction
Quel filo spinato che divide Lega e Chiesa
No full textSul tema dell'immigrazione Lega e Chiesa di Papa Bergoglio hanno posizioni molto distanti. La Lega si propone, anche nell'uso della simbologia, come " partito cristiano" ma la Chiesa di Francesco misura concretamente questa autorappresentazione sull'atteggiamento verso i migranti, negando che possa dirsi cristiano chi persegue politiche di esclusione
Diffusion in Hamiltonian quasi-integrable systems
No full textThe characterization of diffusion of orbits in Hamiltonian quasi-
integrable systems is a relevant topic in dynamics. For quasi-integrable Hamiltonian systems a possible model for global diffusion, valid for perturbation larger than
a critical value, was given by Chirikov; while for smaller perturbation the Nekhoroshev theorem leave the possibility of exponentially slow diffusion along a peculiar
the Arnold’s web. We have studied this problem using a numerical approach. The
aim of this chapter is to give the state of the art concerning the detection of slow
Arnold’s diffusion in quasi-integrable Hamiltonian systems
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
The Fast Lyapunov Indicator: detection of the Arnold web for Hamiltonian systems and symplectic mappings with 3 degrees of freedom
No full textThe contribution describes some applications of the Fast Lyapunov Indicator to Hamiltonian Dynamics
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
Numerical studies of hyperbolic manifolds supporting diffusion in symplectic mappings
No full textDiffusion in generic quasi integrable systems at small values of the perturbing parameters has been a very studied subject since the pioneering work of Arnold. For moderate values of the perturbing parameter a different kind of diffusion occurs, the so called Chirikov diffusion, since the Chirikov’s papers [....]. The two underlying mechanisms are different, the first has an analytic demonstration only on specific models, the second is based on an heuristic argument. Even if the relation between chaos and diffusion is far to be completely understood, a key role is played by the topology of hyperbolic manifolds related to the resonances. Different methods can be found in the literature for the detection of hyperbolic manifolds, at least for two dimensional systems. For higher dimensional ones some sophisticated methods have been recently developed (for a review see [....]). In this paper we review some of these methods and an easy tool of detection of invariant manifolds that we have developed based on the Fast Lyapunov Indicator. The relation between the topology of hyperbolic manifolds and diffusion is discussed in the framework of Arnold diffusion
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