1,721,151 research outputs found
Remarks on the Interpolation Method
Full text linkWe discuss a generalization of the classic condition of validity of the interpolation method for the density of quenched free energy of mean field spin glasses. The condition is written just in terms of the L2 metric structure of the Gaussian random variables. As an example of application we deduce the existence of the thermodynamic limit for a GREM model with infinite branches for which the classic conditions of validity fail. We underline the dependence of the density of quenched free energy just on the metric structure and discuss the models from a metric viewpoint
Bbs invariant measures with independent soliton components
Full text linkThe Box-Ball System (BBS) is a one-dimensional cellular automaton in the configuration space {0, 1}Z introduced by Takahashi and Satsuma [8], who identified conserved quantities called solitons. Ferrari, Nguyen, Rolla and Wang [4] map a configuration to a family of soliton components, indexed by the soliton sizes k = 1. Building over this decomposition, we give an explicit construction of a large family of invariant measures for the BBS that are also shift invariant, including Ising-like Markov and Bernoulli product measures. The construction is based on the concatenation of iid excursions of the associated walk trajectory. Each excursion has the property that the law of its k component given the larger components is product of a finite number of geometric distributions with a parameter depending on k. As a consequence, the law of each component of the resulting ball configuration is product of identically distributed geometric random variables, and the components are independent. This last property implies invariance for BBS, as shown by [4]
On the Equivalence and Optimality of Transformations of Diffusive Systems
No full textIn this paper we introduce, inspired by Clausius and developing the ideas of [11], the concept of equivalence of transformations in non equilibrium theory of diffusive systems within the framework of macroscopic fluctuation theory. Besides providing a new proof of a formula derived in [3, 4], which is the basis of the equivalence, we show that equivalent quasistatic transformations can be distinguished in finite terms, by the renormalized work introduced in [1, 2, 3-4]. This allows us to tackle the problem of determining the optimal quasistatic transformation among the equivalent ones
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
Dati amministrativi per le statistiche ufficiali sulle migrazioni
No full textDa tempo l’Istat ha avviato sull’archivio dei permessi di soggiorno uno studio per la valorizzazione delle informazioni raccolte in chiave “longitudinale” attraverso l’applicazione di tecniche di record-linkage. In questo contributo vengono presentati alcuni primi risultati per mettere in luce alcune peculiari potenzialità di analisi sottese all’utilizzo di dati che consentono di seguire nel tempo gli individui, cioè le unità statistiche oggetto della rilevazione. In particolare, l’attenzione si è focalizzata sul fenomeno della mobilità interna degli stranieri non comunitari, argomento che è stato già approfondito in letteratura, ma solitamente attraverso l’utilizzo di dati aggregati e con indicatori tradizionali di tipo trasversale
Averaging and large deviation principles for fully--coupled piecewise deterministic Markov processes and applications to molecular motors
No full textDynamical Phase Transitions for Flows on Finite Graphs
Full text linkWe study the time-averaged flow in a model of particles that randomly hop on a finite directed graph. In the limit as the number of particles and the time window go to infinity but the graph remains finite, the large-deviation rate functional of the average flow is given by a variational formulation involving paths of the density and flow. We give sufficient conditions under which the large deviations of a given time averaged flow is determined by paths that are constant in time. We then consider a class of models on a discrete ring for which it is possible to show that a better strategy is obtained producing a time-dependent path. This phenomenon, called a dynamical phase transition, is known to occur for some particle systems in the hydrodynamic scaling limit, which is thus extended to the setting of a finite graph
Country Report Italy
No full textObiettivo del Rapporto era fornire un quadro aggiornato e dettagliato sul sistema statistico italiano, puntando l'attenzione su disponibilità, accessibilità e qualità dei dati individuali sull'immigrazione e sulla popolazione immigrata, distintamente per tipologia delle fonti (censimenti, registri, rilevazioni continue degli eventi, indagini campionarie, altro) e per specifiche aree tematiche (popolazione e caratteristiche demografiche; flussi migratori e caratteristiche dei migranti; permessi di soggiorno e regolarizzazioni; cambiamenti di cittadinanza; richiedenti asilo e rifugiati; migrazioni irregolari, controlli ed espulsioni; dimensioni dell'integrazione, della discriminazione e della diversità)
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