Gradient flows of interacting Laguerre cells as discrete porous media flows

We study a class of discrete models in which a collection of particles evolves in time following the gradient flow of an energy depending on the cell areas of an associated Laguerre (i.e. a weighted Voronoi) tessellation. We consider the high number of cell limit of such systems and, using a modulated energy argument, we prove convergence towards smooth solutions of nonlinear diffusion PDEs of porous medium type

Self-Stabilizing Repeated Balls-into-Bins

We study the following synchronous process that we call "repeated balls-into-bins". The process is started by assigning $n$ balls to $n$ bins in an arbitrary way. In every subsequent round, from each non-empty bin one ball is chosen according to some fixed strategy (random, FIFO, etc), and re-assigned to one of the $n$ bins uniformly at random. We define a configuration "legitimate" if its maximum load is $\mathcal{O}(\log n)$. We prove that, starting from any configuration, the process will converge to a legitimate configuration in linear time and then it will only take on legitimate configurations over a period of length bounded by any polynomial in $n$, with high probability (w.h.p.). This implies that the process is self-stabilizing and that every ball traverses all bins in $\mathcal{O}(n \log^2 n)$ rounds, w.h.p

Studio di fattibilità di una variante della SRT222 all'abitato di Greve in Chianti

Lo studio nasce dall’esigenza di risolvere la situazione di congestionamento e di disagio creata dal traffico, in particolare da quello pesante, attualmente transitante sulla SRT222, che attraversa l’intero abitato di Greve in Chianti. Lo studio della fattibilità tecnica della Variante è accompagnato da un’analisi approfondita dell’impatto dell’infrastruttura sul territorio sotto l’aspetto ambientale, economico e sociale, condotta con metodologie basate sull’integrazione delle tecniche di Analisi MultiCriteri (AMC) con i Sistemi Informativi Geografici (GIS). Il processo decisionale di valutazione, strutturato attraverso l’Analisi Gerarchica (AHP), conduce all’individuazione del corridoio infrastrutturale di minimo impatto attraverso la zonizzazione dei livelli di sensibilità del territorio, desunti dall’individuazione dei criteri e degli attributi di valutazione, spazialmente rappresentati mediante mappe geografiche georeferenziate e ricomposti in maniera pesata sulla base delle preferenze dei decisori. All’interno del corridoio viene quindi definito e geometricamente caratterizzato un tracciato ottimale con l’obiettivo, oltre che della minimizzazione dei costi di realizzazione, del rispetto delle prescrizioni normative sul dimensionamento geometrico e funzionale della strada e delle intersezioni, indicate dal DM 05/11/2001, essenziali per garantire un adeguato livello di comfort e sicurezza per gli utenti che utilizzeranno la nuova infrastruttura. Lo studio quindi, oltre a proporre una soluzione progettuale per la fattispecie di Greve, definisce e perfeziona una metodologia di supporto alle decisioni finalizzata ad integrare le modalità progettuali in ambito stradale con le crescenti esigenze di compatibilità ambientale, con benefici in termini di trasparenza, partecipazione, tempo e costi

The web will kill them all: new media, digital utopia, and political struggle in the Italian 5-Star Movement

This article examines the role of discourses about new media technology and the web in the rise of the 5-Star Movement (Movimento 5 Stelle, or M5S) in Italy. Founded by comedian and activist Beppe Grillo and web entrepreneur Gianroberto Casaleggio in 2009, this movement succeeded in becoming the second largest party at the 2013 national elections in Italy. This article aims to discuss how elements of digital utopia and web-centric discourses have been inserted into the movement’s political message, and how the construction of the web as a myth has shaped the movement’s discourse and political practice. The 5-Star Movement is compared and contrasted with other social and political movements in western countries which have displayed a similar emphasis on new media, such as the Occupy movement, the Indignados movement, and the Pirate Parties in Sweden and Germany. By adopting and mutating cyber-utopian discourses from the so-called Californian ideology, the movement symbolically identifies itself with the web. The traditional political establishment is associated with “old” media (television, radio, and the printed press), and represented as a “walking dead,” doomed to be superseded and buried by a web-based direct democracy

A mixed finite element discretization of dynamical optimal transport

In this paper we introduce a new class of finite element discretizations of the quadratic optimal transport problem based on its dynamical formulation. These generalize to the finite element setting the finite difference scheme proposed by Papadakis et al. [SIAM J Imaging Sci, 7(1):212--238,2014]. We solve the discrete problem using a proximal-splitting approach and we show how to modify this in the presence of regularization terms which are relevant for imaging applications

Are CMEs capable of producing Moreton waves? A case study: The 2006 December 6 event

Considering the chromosphere and a stratified corona, we examine, by performing 2D compressible magnetohydrodynamics simulations, the capability of a coronal mass ejection (CME) scenario to drive a Moreton wave. We find that given a typical flux rope (FR) magnetic configuration, in initial pseudo-equilibrium, the larger the magnetic field and the lighter (and hotter) the FR, the larger the amplitude and the speed of the chromospheric disturbance, which eventually becomes aMoreton wave.We present arguments to explain why Moreton waves are much rarer than CME occurrences. In the frame of the present model, we explicitly exclude the action of flares that could be associated with the CME. Analysing the Mach number, we find that only fast magnetosonic shock waves will be able to produce Moreton events. In these cases an overexpansion of the FR is always present and it is the main factor responsible for the Moreton generation. Finally, we show that this scenario can account for the Moreton wave of the 2006 December 6 event (Francile et al. 2013).Fil: Krause, Gustavo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados En Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias exactas Físicas y Naturales. Instituto de Estudios Avanzados En Ingeniería y Tecnología; ArgentinaFil: Cécere, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Zurbriggen, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Costa, Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Francile, Carlos Natale. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Informática. Observatorio Astronómico Félix Aguilar; ArgentinaFil: Elaskar, Sergio Amado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados En Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias exactas Físicas y Naturales. Instituto de Estudios Avanzados En Ingeniería y Tecnología; Argentin