200,891 research outputs found
Individual Contacts, Collective Patterns. Prato 1975-97, a story of interactions.
No full textThis article presents an agent-based model (ABM) of an Italian textile district where thousands of small firms specialize in particular phases of fabrics production. It is an empirical model because it reconstructs the communications between firms when they arrange production chains. In their turn, production chains reflect into the pattern of road traffic in the geographical areas where the district extends. It is a methodological model because it aims to show that ABMs can be used to reconstruct a web of movements in geographical space. ABMs are proposed as a tool for Hägerstrand’s “time-geography”.Industrial districts, Industrial clusters, Agent-based models, Prato
Strong Uniqueness for Stochastic Evolution Equations with Unbounded Measurable Drift Term
No full textWe consider stochastic evolution equations in Hilbert spaces with merely measurable and locally bounded drift term B and cylindrical Wiener noise. We prove pathwise (hence strong) uniqueness in the class of global solutions. This paper extends our previous paper (Da Prato et al. in Ann Probab 41:3306–3344, 2013) which generalized Veretennikov’s fundamental result to infinite dimensions assuming boundedness of the drift term. As in Da Prato et al. (Ann Probab 41:3306–3344, 2013), pathwise uniqueness holds for a large class, but not for every initial condition. We also include an application of our result to prove existence of strong solutions when the drift B is assumed only to be measurable and bounded and grow more than linearly
Will Industrial Districts Exploit B2B? A local experience and a general assessment.
No full textWhat are the prospects of B2B electronic commerce when production is carried out by a number of small firms specialized in single production phases? Prato, Italy, is home to thousands of textile firms as well as the locus of an early and innovative experience of a local Internet in the mid-1980s. This experience suggests that, since they fear to be imatated by their geographical proximates, geographically clustered firms may lag behind in the exploitation of information and communication technologies. Analysis of today's web sites of Pratese firms confiorms this intuition. A similar analysis of web sites is carried out for producers of fabrics worldwide. Contrary to Europe, in Asian countries geographically clustered firms exhibit little fear of information leakages. Differences in the organization of production may explain this puzzle.ICT, e-commerce, B2B, Textile Industry, Industrial Clusters, Industrial Districts, Prato.
La teoria delle fallacie argomentative di Jeremy Bentham
No full textThe paper aims to investigate the mechanisms of incorrect and
misleading reasoning with particular reference to the argumentative fallacies theory conceived by Bentham in his Book of fallacies (1824). Bentham tried to introduce into parliamentary debates, which often concern questions concerning law and ethics, discussion procedures capable of allowing the reasoning to remain adherent to the facts it intends to describe, without using irrelevant and contradictory arguments on which deceptive propaganda is based
A Bregman inexact linesearch-based forward-backward algorithm for nonsmooth nonconvex optimization
No full textIn this paper, we present a forward–backward linesearch–based algorithm suited for the minimization of the sum of a smooth (possibly nonconvex) function and a convex (possibly nonsmooth) term. Such algorithm first computes inexactly the proximal operator with respect to a given Bregman distance, and then ensures a sufficient decrease condition by performing a linesearch along the descent direction. The proposed approach can be seen as an instance of the more general class of descent methods presented in [1], however, unlike in [1], we do not assume the strong convexity of the Bregman distance used in the proximal evaluation. We prove that each limit point of the iterates sequence is stationary, we show how to compute an approximate proximal–gradient point with respect to a Bregman distance and, finally, we report the good numerical performance of the algorithm on a large scale image restoration problem. [1] S. Bonettini, I. Loris, F. Porta, and M. Prato 2016, Variable metric inexact line-search-based methods for nonsmooth optimization, SIAM J. Optim. 26(2), 891–921
Strong uniqueness for stochastic evolution equations in Hilbert spaces perturbed by a bounded measurable drift
No full textDa Prato G, Flandoli F, Priola E, Röckner M. Strong uniqueness for stochastic evolution equations in Hilbert spaces perturbed by a bounded measurable drift. The Annals Of Probability. 2013;41(5):3306-3344.We prove pathwise (hence strong) uniqueness of solutions to stochastic evolution equations in Hilbert spaces with merely measurable bounded drift and cylindrical Wiener noise, thus generalizing Veretennikov's fundamental result on R-d to infinite dimensions. Because Sobolev regularity results implying continuity or smoothness of functions do not hold on infinite-dimensional spaces, we employ methods and results developed in the study of Malliavin-Sobolev spaces in infinite dimensions. The price we pay is that we can prove uniqueness for a large class, but not for every initial distribution. Such restriction, however, is common in infinite dimensions
The Chinese in Prato and the Current Outlook on the Chinese-Italian Experience
No full textThis chapter was co-authored by Gabi Dei Ottati (who wrote the sections at pp. 39-45) and Daniele Brigadoi Cologna (sections at pp. 29-39; 45-47), who examined how Chinese migration to Prato articulates with contemporary trends in Chinese entrepreneurship in Italy (especially in the older established Chinese communities in Milan). As the Chinese-Italian experience reaches well into its fifth generation - Chinese migration history in Italy is at least ninety years old - the authors argue that stereotyped perceptions of Chinese within Italian society go ever more against the grain of the manifold new realities of economic, social, cultural and political interaction between Chinese and Italians. The chapter considers, in particular, the key historical features of the Chinese community in Prato as an exemplary case of the development of industrial districts in Italy. It examines the changes in Prato during the latest two decades, including the extraordinary growth of the Chinese pronto moda business. Using demographic and ethnographic data, the authors suggest that Chinese migration to Italy may have peaked in the mid-2000s, and they illustrate how there has been a change in business and social interaction practices as the result of a trend away from the manufacturing and restaurant sectors to the services Sector. Thus what used to be a rather segregated community of ethnic entrepreneurs is now flourishing in all sorts of different business denominations in the services sector, recruiting the Italian-speaking, largely Italian-born second generation to deal both with their Italian customers as well as those who belong to other immigrant groups, ushering in a new perspective of cultural and political empowerment for many Chinese-Italians, whose claims of social and formal citizenship are gaining momentum
Absolutely continuous solutions for continuity equations in Hilbert spaces
No full textDa Prato G, Flandoli F, Röckner M. Absolutely continuous solutions for continuity equations in Hilbert spaces. Journal de Mathématiques Pures et Appliquées. 2019;128:42-86.We prove existence of solutions to continuity equations in a separable Hilbert space. We look for solutions which are absolutely continuous with respect to a reference measure gamma which is Fomin-differentiable with exponentially integrable partial logarithmic derivatives. We describe a class of examples to which our result applies and for which we can prove also uniqueness. Finally, we consider the case where gamma is the invariant measure of a reaction-diffusion equation and prove uniqueness of solutions in this case. We exploit that the gradient operator D-x is closable with respect to L-p(H, gamma) and a recent formula for the commutator DxPt - PtDx where P-t is the transition semigroup corresponding to the reaction-diffusion equation, [10]. We stress that P-t is not necessarily symmetric in this case. This uniqueness result is an extension to such gamma of that in [12] where gamma was the Gaussian invariant measure of a suitable Ornstein-Uhlenbeck process. (C) 2019 Elsevier Masson SAS. All rights reserved
Introduction: Beyond Multiculturalism. Anthropology at the Intersections Between the Local, the National and the Global
No full textNonnegative image reconstruction from sparse Fourier data: a new deconvolution algorithm
No full textThis paper deals with image restoration problems where the data are nonuniform samples of the Fourier transform of the unknown object. We study the inverse problem in both semidiscrete and fully discrete formulations, and our analysis leads to an optimization problem involving the minimization of the data discrepancy under nonnegativity constraints. In particular we show that such problem is equivalent to a deconvolution problem in the image space. We propose a practical algorithm, based on the gradient projection method, to compute a regularized solution in the discrete case. The key point in our deconvolution-based approach is that the Fast Fourier Transform can be employed in the algorithm implementation without the need of preprocessing the data. A numerical experimentation on simulated and real datafrom the NASA RHESSI mission is also performed
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