IMT Institutional Repository: No conditions. Results ordered -Date Deposited. 2024-03-29T01:13:01ZEPrintshttp://eprints.imtlucca.it/images/logowhite.pnghttp://eprints.imtlucca.it/2018-03-23T12:09:23Z2018-03-23T12:09:23Zhttp://eprints.imtlucca.it/id/eprint/4060This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40602018-03-23T12:09:23ZLaw no. 1089 of 1 June 1939. The Origin and Consequences of Italian Legislation on the Protection of the National Cultural Heritage in the Twentieth CenturyThe author seeks to set out a criticism of the alleged innovations brought about by the 1939 Italian law on the “Protection of objects of artistic or historical value”. The law came in those years during which Fascist authorities struggled to keep on national soil a great deal of cultural property, which belonged to those who were trying to flee Italy following the harshening of persecutory regulations. Yet, scores of valuable public and private works of art had been reaching Nazi top brass following the Italian government’s own initiative. This eventually hindered the legitimacy of part of the cultural restitutions granted to Italy by the Allied military authorities after 1945.Francesca Coccolofrancesca.coccolo@imtlucca.it2018-03-09T13:47:11Z2018-03-09T13:47:11Zhttp://eprints.imtlucca.it/id/eprint/4040This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40402018-03-09T13:47:11ZCovariance structure behind breaking of ensemble equivalence in random graphsFor a random graph subject to a topological constraint, the microcanonical ensemble requires the constraint to be met by every realisation of the graph (`hard constraint'), while the canonical ensemble requires the constraint to be met only on average (`soft constraint'). It is known that breaking of ensemble equivalence may occur when the size of the random graph tends to infinity, signalled by a non-zero specific relative entropy of the two ensembles. In this paper we analyse a formula for the relative entropy of generic random discrete structures recently put forward by Squartini and Garlaschelli. We consider the case of random graphs with given degree sequence (configuration model) and show that this formula correctly predicts that the specific relative entropy in the dense regime is determined by the matrix of canonical covariances of the constraints. The formula also correctly predicts that an extra correction term is required in the sparse regime and the ultra-dense regime. We further show that the different expressions correspond to the degrees in the canonical ensemble being asymptotically Gaussian in the dense regime and asymptotically Poisson in the sparse and the ultra-dense regime, as we found in earlier work. In general, we show that the degrees follow a multivariate version of the Poisson- Binomial distribution in the canonical ensemble.Diego Garlaschellidiego.garlaschelli@imtlucca.itFrank den HollanderAndrea Roccaverde2018-03-09T13:45:20Z2018-03-09T13:45:20Zhttp://eprints.imtlucca.it/id/eprint/4039This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40392018-03-09T13:45:20ZEnhanced Gravity Model of trade: reconciling macroeconomic and network modelsThe structure of the International Trade Network (ITN), whose nodes and links represent world countries and their trade relations respectively, affects key economic processes worldwide, including globalization, economic integration, industrial production, and the propagation of shocks and instabilities. Characterizing the ITN via a simple yet accurate model is an open problem. The traditional Gravity Model successfully reproduces the volume of trade between connected countries, using macroeconomic properties such as GDP, geographic distance, and possibly other factors. However, it predicts a network with complete or homogeneous topology, thus failing to reproduce the highly heterogeneous structure of the ITN. On the other hand, recent maximum-entropy network models successfully reproduce the complex topology of the ITN, but provide no information about trade volumes. Here we integrate these two currently incompatible approaches via the introduction of an Enhanced Gravity Model (EGM) of trade. The EGM is the simplest model combining the Gravity Model with the network approach within a maximum-entropy framework. Via a unified and principled mechanism that is transparent enough to be generalized to any economic network, the EGM provides a new econometric framework wherein trade probabilities and trade volumes can be separately controlled by any combination of dyadic and country-specific macroeconomic variables. The model successfully reproduces both the global topology and the local link weights of the ITN, parsimoniously reconciling the conflicting approaches. It also indicates that the probability that any two countries trade a certain volume should follow a geometric or exponential distribution with an additional point mass at zero volume.Assaf AlmogRhys BirdDiego Garlaschellidiego.garlaschelli@imtlucca.it2018-03-09T13:43:01Z2018-03-09T13:43:01Zhttp://eprints.imtlucca.it/id/eprint/4038This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40382018-03-09T13:43:01ZEnhanced capital-asset pricing model for the reconstruction of bipartite financial networksReconstructing patterns of interconnections from partial information is one of the most important issues in the statistical physics of complex networks. A paramount example is provided by financial networks. In fact, the spreading and amplification of financial distress in capital markets are strongly affected by the interconnections among financial institutions. Yet, while the aggregate balance sheets of institutions are publicly disclosed, information on single positions is mostly confidential and, as such, unavailable. Standard approaches to reconstruct the network of financial interconnection produce unrealistically dense topologies, leading to a biased estimation of systemic risk. Moreover, reconstruction techniques are generally designed for monopartite networks of bilateral exposures between financial institutions, thus failing in reproducing bipartite networks of security holdings (e.g., investment portfolios). Here we propose a reconstruction method based on constrained entropy maximization, tailored for bipartite financial networks. Such a procedure enhances the traditional capital-asset pricing model (CAPM) and allows us to reproduce the correct topology of the network. We test this enhanced CAPM (ECAPM) method on a dataset, collected by the European Central Bank, of detailed security holdings of European institutional sectors over a period of six years (2009–2015). Our approach outperforms the traditional CAPM and the recently proposed maximum-entropy CAPM both in reproducing the network topology and in estimating systemic risk due to fire sales spillovers. In general, ECAPM can be applied to the whole class of weighted bipartite networks described by the fitness model.Tiziano Squartinitiziano.squartini@imtlucca.itAssaf AlmogGuido Caldarelliguido.caldarelli@imtlucca.itIman van LelyveldDiego Garlaschellidiego.garlaschelli@imtlucca.itGiulio Ciminigiulio.cimini@imtlucca.it2018-03-09T13:39:09Z2018-03-09T13:39:09Zhttp://eprints.imtlucca.it/id/eprint/4036This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40362018-03-09T13:39:09ZIrreducible network backbones: unbiased graph filtering via maximum entropyNetworks provide an informative, yet non-redundant description of complex systems only if links represent truly dyadic relationships that cannot be directly traced back to node-specific properties such as size, importance, or coordinates in some embedding space. In any real-world network, some links may be reducible, and others irreducible, to such local properties. This dichotomy persists despite the steady increase in data availability and resolution, which actually determines an even stronger need for filtering techniques aimed at discerning essential links from non-essential ones. Here we introduce a rigorous method that, for any desired level of statistical significance, outputs the network backbone that is irreducible to the local properties of nodes, i.e. their degrees and strengths. Unlike previous approaches, our method employs an exact maximum-entropy formulation guaranteeing that the filtered network encodes only the links that cannot be inferred from local information. Extensive empirical analysis confirms that this approach uncovers essential backbones that are otherwise hidden amidst many redundant relationships and inaccessible to other methods. For instance, we retrieve the hub-and-spoke skeleton of the US airport network and many specialised patterns of international trade. Being irreducible to local transportation and economic constraints of supply and demand, these backbones single out genuinely higher-order wiring principles.Valerio GemmettoAlessio CardilloDiego Garlaschellidiego.garlaschelli@imtlucca.it2018-03-09T13:37:21Z2018-03-09T13:37:21Zhttp://eprints.imtlucca.it/id/eprint/4035This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40352018-03-09T13:37:21ZMaximum-Entropy Networks: pattern detection, network reconstruction, and graph combinatoricsThis book is an introduction to maximum-entropy models of random graphs with given topological properties and their applications. Its original contribution is the reformulation of many seemingly different problems in the study of both real networks and graph theory within the unified framework of maximum entropy. Particular emphasis is put on the detection of structural patterns in real networks, on the reconstruction of the properties of networks from partial information, and on the enumeration and sampling of graphs with given properties. After a first introductory chapter explaining the motivation, focus, aim and message of the book, chapter 2 introduces the formal construction of maximum-entropy ensembles of graphs with local topological constraints. Chapter 3 focuses on the problem of pattern detection in real networks and provides a powerful way to disentangle nontrivial higher-order structural features from those that can be traced back to simpler local constraints. Chapter 4 focuses on the problem of network reconstruction and introduces various advanced techniques to reliably infer the topology of a network from partial local information. Chapter 5 is devoted to the reformulation of certain “hard” combinatorial operations, such as the enumeration and unbiased sampling of graphs with given constraints, within a “softened” maximum-entropy framework. A final chapter offers various overarching remarks and take-home messages.By requiring no prior knowledge of network theory, the book targets a broad audience ranging from PhD students approaching these topics for the first time to senior researchers interested in the application of advanced network techniques to their field.Tiziano Squartinitiziano.squartini@imtlucca.itDiego Garlaschellidiego.garlaschelli@imtlucca.it2018-03-09T13:30:20Z2018-03-09T13:30:20Zhttp://eprints.imtlucca.it/id/eprint/4033This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40332018-03-09T13:30:20ZReconnecting statistical physics and combinatorics beyond ensemble equivalenceIn statistical physics, the challenging combinatorial enumeration of the configurations of a system subject to hard constraints (microcanonical ensemble) is mapped to a mathematically easier calculation where the constraints are softened (canonical ensemble). However, the mapping is exact only when the size of the system is infinite and if the property of ensemble equivalence (EE), i.e. the asymptotic identity of canonical and microcanonical large deviations, holds. For finite systems, or when EE breaks down, statistical physics is currently believed to provide no answer to the combinatorial problem. In contrast with this expectation, here we establish exact relationships connecting conjugate ensembles in full generality, even for finite system size and when EE does not hold. We also show that in the thermodynamic limit the ensembles are directly related through the matrix of canonical (co)variances of the constraints, plus a correction term that survives only if this matrix has an infinite number of finite eigenvalues. These new relationships restore the possibility of enumerating microcanonical configurations via canonical probabilities, thus reconnecting statistical physics and combinatorics in realms where they were believed to be no longer in mutual correspondence.Tiziano Squartinitiziano.squartini@imtlucca.itDiego Garlaschellidiego.garlaschelli@imtlucca.it2018-03-09T13:27:37Z2018-03-09T13:27:37Zhttp://eprints.imtlucca.it/id/eprint/4032This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40322018-03-09T13:27:37ZReconstruction of multiplex networks with correlated layersThe characterization of various properties of real-world systems requires the knowledge of the underlying network of connections among the system's components. Unfortunately, in many situations the complete topology of this network is empirically inaccessible, and one has to resort to probabilistic techniques to infer it from limited information. While network reconstruction methods have reached some degree of maturity in the case of single-layer networks (where nodes can be connected only by one type of links), the problem is practically unexplored in the case of multiplex networks, where several interdependent layers, each with a different type of links, coexist. Even the most advanced network reconstruction techniques, if applied to each layer separately, fail in replicating the observed inter-layer dependencies making up the whole coupled multiplex. Here we develop a methodology to reconstruct a class of correlated multiplexes which includes the World Trade Multiplex as a specific example we study in detail. Our method starts from any reconstruction model that successfully reproduces some desired marginal properties, including node strengths and/or node degrees, of each layer separately. It then introduces the minimal dependency structure required to replicate an additional set of higher-order properties that quantify the portion of each node's degree and each node's strength that is shared and/or reciprocated across pairs of layers. These properties are found to provide empirically robust measures of inter-layer coupling. Our method allows joint multi-layer connection probabilities to be reliably reconstructed from marginal ones, effectively bridging the gap between single-layer properties and truly multiplex information.Valerio GemmettoDiego Garlaschelli2018-03-09T13:25:14Z2018-03-09T13:25:14Zhttp://eprints.imtlucca.it/id/eprint/4030This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40302018-03-09T13:25:14ZScienceWISE: Topic Modeling over Scientific Literature NetworksWe provide an up-to-date view on the knowledge management system ScienceWISE (SW) and address issues related to the automatic assignment of articles to research topics. So far, SW has been proven to be an effective platform for managing large volumes of technical articles by means of ontological concept-based browsing. However, as the publication of research articles accelerates, the expressivity and the richness of the SW ontology turns into a double-edged sword: a more fine-grained characterization of articles is possible, but at the cost of introducing more spurious relations among them. In this context, the challenge of continuously recommending relevant articles to users lies in tackling a network partitioning problem, where nodes represent articles and co-occurring concepts create edges between them. In this paper, we discuss the three research directions we have taken for solving this issue: i) the identification of generic concepts to reinforce inter-article similarities; ii) the adoption of a bipartite network representation to improve scalability; iii) the design of a clustering algorithm to identify concepts for cross-disciplinary articles and obtain fine-grained topics for all articles.Andrea MartiniArtem LutovValerio GemmettoAndrii MagalichAlessio CardilloAlex ConstantinVasyl PalchykovMourad KhayatiPhilippe Cudre-MaurouxAlexey BoyarskyOleg RuchayskiyDiego Garlaschellidiego.garlaschelli@imtlucca.itPaolo De De RiosKarl Aberer2018-03-09T13:22:21Z2018-03-09T13:22:25Zhttp://eprints.imtlucca.it/id/eprint/4028This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/40282018-03-09T13:22:21ZSigns of universality in the structure of cultureUnderstanding the dynamics of opinions, preferences and of culture as whole requires more use of empirical data than has been done so far. It is clear that an important role in driving this dynamics is played by social influence, which is the essential ingredient of many quantitative models. Such models require that all traits are fixed when specifying the “initial cultural state”. Typically, this initial state is randomly generated, from a uniform distribution over the set of possible combinations of traits. However, recent work has shown that the outcome of social influence dynamics strongly depends on the nature of the initial state. If the latter is sampled from empirical data instead of being generated in a uniformly random way, a higher level of cultural diversity is found after long-term dynamics, for the same level of propensity towards collective behavior in the short-term. Moreover, if the initial state is randomized by shuffling the empirical traits among people, the level of long-term cultural diversity is in-between those obtained for the empirical and uniformly random counterparts. The current study repeats the analysis for multiple empirical data sets, showing that the results are remarkably similar, although the matrix of correlations between cultural variables clearly differs across data sets. This points towards robust structural properties inherent in empirical cultural states, possibly due to universal laws governing the dynamics of culture in the real world. The results also suggest that this dynamics might be characterized by criticality and involve mechanisms beyond social influence.Alexandru-Ionut BabeanuLeandros TalmanDiego Garlaschellidiego.garlaschelli@imtlucca.it2018-03-09T13:18:32Z2018-03-09T13:18:32Zhttp://eprints.imtlucca.it/id/eprint/3999This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39992018-03-09T13:18:32ZSynchronization of phase oscillators on the hierarchical latticeSynchronization of neurons forming a network with a hierarchical structure is essential for the brain to be able to function optimally. In this paper we study synchronization of phase oscillators on the most basic example of such a network, namely, the hierarchical lattice. Each oscillator has a natural frequency, drawn independently from a common probability distribution. In addition, pairs of oscillators interact with each other at a strength that depends on their hierarchical distance, modulated by a sequence of interaction parameters. We look at block averages of the oscillators on successive hierarchical scales, which we think of as block communities. Also these block communities are given a natural frequency, drawn independently from a common probability distribution that depends on their hierarchical scale. In the limit as the number of oscillators per community tends to infinity, referred to as the hierarchical mean-field limit, we find a separation of time scales, i.e., each block community behaves like a single oscillator evolving on its own time scale. We show that the evolution of the block communities is given by a renormalized mean-field noisy Kuramoto equation, with a synchronization level that depends on the hierarchical scale of the block community. We identify three universality classes for the synchronization levels on successive hierarchical scales, with explicit characterizations in terms of the sequence of interaction parameters and the sequence of natural frequency probability distributions. We show that disorder reduces synchronization when the natural frequency probability distributions are symmetric and unimodal, with the reduction gradually vanishing as the hierarchical scale goes up.Diego Garlaschellidiego.garlaschelli@imtlucca.itFrank den HollanderJanusz MeylahnBenthen Zeegers2018-03-09T13:15:51Z2018-03-09T13:15:52Zhttp://eprints.imtlucca.it/id/eprint/3998This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39982018-03-09T13:15:51ZThe double role of GDP in shaping the structure of the International Trade NetworkThe International Trade Network (ITN) is the network formed by trade relationships between world countries. The complex structure of the ITN impacts important economic processes such as globalization, competitiveness, and the propagation of instabilities. Modeling the structure of the ITN in terms of simple macroeconomic quantities is therefore of paramount importance. While traditional macroeconomics has mainly used the Gravity Model to characterize the magnitude of trade volumes, modern network theory has predominantly focused on modeling the topology of the ITN. Combining these two complementary approaches is still an open problem. Here we review these approaches and emphasize the double role played by GDP in empirically determining both the existence and the volume of trade linkages. Moreover, we discuss a unified model that exploits these patterns and uses only the GDP as the relevant macroeconomic factor for reproducing both the topology and the link weights of the ITN.Assaf AlmogTiziano Squartinitiziano.squartini@imtlucca.itDiego Garlaschellidiego.garlaschelli@imtlucca.it2018-03-09T13:13:21Z2018-03-09T13:13:21Zhttp://eprints.imtlucca.it/id/eprint/3997This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39972018-03-09T13:13:21ZUncovering functional brain signature via random matrix theoryThe brain is organized in a modular way, serving multiple functionalities. This multiplicity requires that both positive (e.g. excitatory, phase-coherent) and negative (e.g. inhibitory, phase-opposing) interactions take place across brain modules. Unfortunately, most methods to detect modules from time series either neglect or convert to positive any measured negative correlation. This may leave a significant part of the sign-dependent functional structure undetected. Here we present a novel method, based on random matrix theory, for the identification of sign-dependent modules in the brain. Our method filters out the joint effects of local (unit-specific) noise and global (system-wide) dependencies that empirically obfuscate such structure. The method is guaranteed to identify an optimally contrasted functional `signature', i.e. a partition into modules that are positively correlated internally and negatively correlated across. The method is purely data-driven, does not use any arbitrary threshold or network projection, and outputs only statistically significant structure. In measurements of neuronal gene expression in the biological clock of mice, the method systematically uncovers two otherwise undetectable, negatively correlated modules whose relative size and mutual interaction strength are found to depend on photoperiod. The neurons alternating between the two modules define a candidate region of functional plasticity for circadian modulation.Assaf AlmogOri RoethlerRenate BuijinkStephan MichelJohanna H MeijerJos H T RohlingDiego Garlaschellidiego.garlaschelli@imtlucca.it2018-02-26T14:21:42Z2018-02-26T14:21:42Zhttp://eprints.imtlucca.it/id/eprint/3915This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39152018-02-26T14:21:42ZCollective Memories, Propaganda and Authoritarian Political SupportTo what extent does the degree of authoritarian political support depend on collective memories of a past experience with democracy? And how costly is it for a dictator to manipulate such memories with the help of propaganda? In this paper, we develop a political economy model with endogenous reference points, where a dictator strategically recalls traumatic collective memories of past political instability with the help of propaganda, to convince the population that an autocratic status quo is superior to a potential democratic alternative. In our
model, both the optimal level of propaganda and collective memories are jointly determined. We show how the marginal benefit of propaganda is positively correlated both with the amount of rent distribution within the elite, and the intensity of a past traumatic experience with democracy. We illustrate our theoretical findings
with case-studies of two authoritarian regimes that were preceded by periods of political instability—the Russian Federation under Vladimir Putin, and Chile under Augusto Pinochet. We then also provide cross-country empirical evidence in support of our argument.Alessandro Belmonteabelmonte.phd@gmail.comMichael Rochlitz2018-02-16T12:48:31Z2018-02-16T12:48:31Zhttp://eprints.imtlucca.it/id/eprint/3909This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39092018-02-16T12:48:31ZValorizzazione e gestioneLorenzo Casinilorenzo.casini@imtlucca.it2018-02-15T11:09:29Z2018-02-15T11:09:29Zhttp://eprints.imtlucca.it/id/eprint/3907This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39072018-02-15T11:09:29ZDiritto del patrimonio culturaleIl volume, realizzato dai componenti della direzione della rivista «Aedon», offre un quadro completo e aggiornato dei dati normativi concernenti l'attività e l'organizzazione delle istituzioni pubbliche e dei privati in tema di patrimonio culturale. Fornisce inoltre una ricostruzione critica del contesto e dei presupposti che hanno accompagnato il sorgere e il consolidamento del sistema dei beni culturali e paesaggistici nel nostro Paese. Uno strumento di formazione per gli studenti e al tempo stesso di consultazione e aggiornamento per quanti operano professionalmente nel settoreCarla BarbatiLorenzo Casinilorenzo.casini@imtlucca.itMarco CammelliGiuseppe PiperataGirolamo Sciullo2018-02-15T10:59:31Z2018-02-15T10:59:31Zhttp://eprints.imtlucca.it/id/eprint/3905This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39052018-02-15T10:59:31ZTrasformazioni dello Stato e riforme nel settore dei beni culturaliThe article moves from Paolo Leon's works in order to illustrate the features and objectives of the 2014 reform of the Italian Ministry of Cultural Heritage and Tourism. It is focused on three issues: the establishment of state museums, the reform of Ministry's field offices (soprintendenze), and the investment in human resources. These reformative actions give evidence of the high significance and modernity of Paolo Leon's scientific and cultural legacy.Lorenzo Casinilorenzo.casini@imtlucca.it2018-02-15T10:52:15Z2018-02-15T10:52:15Zhttp://eprints.imtlucca.it/id/eprint/3904This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39042018-02-15T10:52:15Z"Il nastro dei sogni"? Il diritto (pubblico) del cinema e dell'audiovisivoThe article examines the new Italian regulation of cinema and audio-visual designed by Act No. 220/2016. The first part illustrates the main features of the new system, which has been implemented by over 20 decrees adopted during the last 12 months. Changes are numerous and regard several issues, such as financial resources, tax incentives, extraordinary measures, and the institutional asset. The second part focuses on the three legislative decrees adopted in December 2017, which completed the reform process. These decrees have significantly innovated the field of protection of minors, jobs regulation, and promotion of European and Italian audio-visual works. The reform, therefore, draws an ambitious design, which can offer an important contribution to the development of a dedicated field of study and research, the public law of cinema and audio-visual.Lorenzo Casinilorenzo.casini@imtlucca.it2018-02-15T10:49:38Z2018-02-15T10:49:38Zhttp://eprints.imtlucca.it/id/eprint/3903This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39032018-02-15T10:49:38Z"Learning by experience"? La riforma del ministero dei Beni e delle Attività culturali e del TurismoThe article examines the reform of the Italian Ministry for Culture and Tourism started in 2014 and its main developments. The first part deals with the history, design and objectives of such administrative reform. The second part explains what kind of leverages made possible to start and to implement the reform process. The third and final part focuses on how the reform could represent a case study from a dual perspective: on the one hand, it displays all the traditional features - and political and bureaucratic behaviours - which one can find in every administrative reform; on the other hand, the reform has produced significant innovation in cultural property law, and in administrative law more generally, under several aspects: regulation, finance, personnel, public and private relationships. Due to its complexity and variety, therefore, cultural property law may become an "atelier" for whoever decides to study administrative law.Lorenzo Casinilorenzo.casini@imtlucca.it2018-02-15T10:47:17Z2018-02-15T10:47:17Zhttp://eprints.imtlucca.it/id/eprint/3902This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/39022018-02-15T10:47:17ZQuale futuro per il diritto globale del patrimonio culturale?Lorenzo Casinilorenzo.casini@imtlucca.it2018-02-02T11:21:19Z2018-02-02T11:21:19Zhttp://eprints.imtlucca.it/id/eprint/3858This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38582018-02-02T11:21:19ZTax morale, aversion to ethnic diversity, and decentralizationThis paper analyzes theoretically and empirically the relationship between individuals' aversion to ethnic diversity, the degree of fiscal and political decentralization, and tax morale. We present a model showing how higher degrees of individuals' aversion to ethnic diversity may reduce tax morale and why this effects may be smaller in decentralized political and fiscal systems. We test these results by using individual data from the World Value Survey and several measures of decentralization. Our estimates robustly confirm that higher degrees of individuals' aversion to ethnic diversity are associated to lower tax morale and that this correlation is smaller or null in decentralized systems.Alessandro Belmontealessandro.belmonte@imtlucca.itRoberto Dell'AnnoDésirée Teobaldelli2018-01-24T10:27:09Z2018-01-24T10:27:09Zhttp://eprints.imtlucca.it/id/eprint/3871This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38712018-01-24T10:27:09ZSocial coordination with locally observable typesIn this paper we study the typical dilemma of social coordination between a risk-dominant convention and a payoff-dominant convention. In particular, we consider a model where a population of agents play a coordination game over time, choosing both the action and the network of agents with whom to interact. The main modeling novelties with respect to the existing literature are: (1) Agents come in two distinct types, (2) the interaction with a different type is costly, and (3) an agent’s type is unobservable prior to interaction. We show that when the cost of interacting with a different type is small with respect to the payoff of coordination, the payoff-dominant convention is the only stochastically stable convention; instead, when the cost of interacting with a different type is large, the only stochastically stable conventions are those where all agents of one type play the payoff-dominant action and all agents of the other type play the risk-dominant action.Ennio Bilanciniennio.bilancini@imtlucca.itLeonardo Boncinelli2017-12-28T11:09:29Z2017-12-28T11:09:29Zhttp://eprints.imtlucca.it/id/eprint/3853This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38532017-12-28T11:09:29ZWhere Gibrat meets Zipf: scale and scope of French firmsThe proper characterization of the size distribution and growth of firms represents an important issue in economics and business. We use the Maximum Entropy approach to assess the plausibility of the assumption that firm size follows Lognormal or Pareto distributions, which underlies most recent works on the subject. A comprehensive dataset covering the universe of French firms allows us to draw two major conclusions. First, the Pareto hypothesis for the whole distribution should be rejected. Second, by discriminating across firms based on the number of products sold and markets served, we find that, within the class of multi-product companies active in multiple markets, the distribution converges to a Zipf’s law. Conversely, Lognormal distribution is a good benchmark for small single-product firms. The size distribution of firms largely depends on firms’ diversification patterns.Marco BeeMassimo Riccabonimassimo.riccaboni@imtlucca.itStefano Schiavo2017-12-28T11:06:06Z2017-12-28T11:06:06Zhttp://eprints.imtlucca.it/id/eprint/3852This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38522017-12-28T11:06:06ZThe indirect effects of foreign direct investment on trade: A network perspectiveThe relationship between international trade and foreign direct investment (FDI) is one of the main features of globalisation. In this paper, we investigate the effects of FDI on trade from a network perspective, since FDI takes not only direct but also indirect channels from origin to destination countries because of firms’ incentive to reduce tax burden, to minimise coordination costs and to break barriers to market entry. We use a unique data set of international corporate control as a measure of stock FDI to construct a corporate control network (CCN), where the nodes are the countries and the edges are the corporate control relationships. Network measures, as the shortest path length and the communicability, are then computed on the CCN to capture the indirect channel of FDI. Empirically, we find that corporate control has a positive effect on trade both directly and indirectly. The result is robust with different specifications and estimation strategies. Hence, our paper provides strong empirical evidence of the indirect effects of FDI on trade. Moreover, we identify a number of interplaying factors such as regional trade agreements and the region of Asia. We also find that the indirect effects are more pronounced for the manufacturing sector than for primary sectors such as oil extraction and agriculture.Rodolfo MetuliniMassimo Riccabonimassimo.riccaboni@imtlucca.itPaolo SgrignoliZhen Zhu2017-11-29T09:28:46Z2017-11-29T09:28:46Zhttp://eprints.imtlucca.it/id/eprint/3842This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38422017-11-29T09:28:46ZDoes corporate control matter to financial volatility?In our contribution we study how the ownership channel affects the stock price volatility
of listed stock markets. In particular, we study how a linkage between a parent company and
its affiliates may drive differences in stock price volatility, within and across countries. We
exploit a worldwide dataset of stock-exchange listed firms, controlling for several financial
dimensions, to assess whether business groups matter to financial volatility. The answer is
positive and does not depend on the definition of volatility used. Our results contribute to
the corporate finance literature by defining the role of multinational corporate control in
financial markets, and to the financial stability literature by assessing corporate control as
an undiscovered channel of transmission for financial shocks.Laura Gianfagnalaura.gianfagna@imtlucca.itArmando Rungiarmando.rungi@imtlucca.it2017-11-28T08:58:51Z2017-11-28T08:58:51Zhttp://eprints.imtlucca.it/id/eprint/3833This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38332017-11-28T08:58:51ZThe Organization of Global Supply NetworksIn this contribution, we introduce a network approach for the organization of global
production across national borders, beyond the sequential industry-level metrics proposed
in the previous literature. First, we show and argue that several characteristics of
global production processes would be lost in the analysis when assuming that they could
be proxied as linear sequences. Hence, we propose an index that assesses the relevance
of any input for the target output, including its role as an input of inputs. Thereafter,
we exploit an own-built firm-level dataset of about 20,489 U.S. parent companies integrating
more than 154,000 affiliates worldwide. Results show that the technological
relevance of an input in a directed supply network is also a good predictor for: i) the
probability that an input industry is actually integrated within a firm boundary; ii) the
number of affiliates that are controlled by the parent company and active in that input
industry.Loredana Fattoriniloredana.fattorini@imtlucca.itArmando Rungiarmando.rungi@imtlucca.itZhen Zhuzhen.zhu@imtlucca.it2017-11-21T13:20:48Z2018-01-12T12:40:18Zhttp://eprints.imtlucca.it/id/eprint/3830This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38302017-11-21T13:20:48ZPost-Yugoslavia. New Cultural and Political Perspectives, edited by Dino Abazović and Mitja VelikonjaMateja Sincicmateja.sincic@imtlucca.it2017-11-13T15:58:37Z2017-11-13T15:58:37Zhttp://eprints.imtlucca.it/id/eprint/3827This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38272017-11-13T15:58:37ZOn Economic Complexity and the Fitness of NationsComplex economic systems can often be described by a network, with nodes representing economic entities and edges their interdependencies, while network centrality is often a good indicator of importance. Recent publications have implemented a nonlinear iterative Fitness-Complexity (FC) algorithm to measure centrality in a bipartite trade network, which aims to represent the ‘Fitness’ of national economies as well as the ‘Complexity’ of the products being traded. In this paper, we discuss this methodological approach and conclude that further work is needed to identify stable and reliable measures of fitness and complexity. We provide theoretical and numerical evidence for the intrinsic instability in the nonlinear definition of the FC algorithm. We perform an in-depth evaluation of the algorithm’s rankings in two real world networks at the country level: the global trade network, and the patent network in different technological domains. In both networks, we find evidence of the instabilities predicted theoretically, and show that ‘complex’ products or patents tend often to be those that countries rarely produce, rather than those that are intrinsically more difficult to produce.Greg MorrisonSergey V. BuldyrevMichele ImbrunoOmar Alonso Doria ArrietaArmando Rungiarmando.rungi@imtlucca.itMassimo Riccabonimassimo.riccaboni@imtlucca.itFabio Pammolli2017-10-31T08:48:20Z2017-10-31T08:48:20Zhttp://eprints.imtlucca.it/id/eprint/3726This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37262017-10-31T08:48:20ZGlobal Value Chains Participation and Productivity Gains for North African FirmsThe emergence of global value chains (GVCs) has provided some firms the opportunity to internationalize by specializing in the production of specific inputs or tasks along the chain, with a direct impact on a country’s competitiveness. China, for instance, managed to enter low value added phases in GVCs to rapidly become a major player in world trade. Against this background, this paper asks whether North Africa, given its favourable geographic position in the Mediterranean and proximity to Europe, can grab similar opportunities. In particular, it analyzes the GVCs participation of North African firms and its implications for productivity. Since the coordination of vertically fragmented production processes increasingly relies on an adequate level of quality and reliability, especially when the inputs from several stages and locations must come together in a specific way, we identify firms involved in GVCs as traders with internationally recognized quality certification. Using a propensity score matching diff-in-diff method, the paper finds that firms that enter GVCs both perform better ex ante and show additional productivity gains ex post. Results suggest that policies designed to support certifications and compliance with international standards and to increase trust between firms in different countries, represent an important tool for linking developing countries to global production networks, with possible positive consequences on their economic development and growth.Davide Del Pretedavide.delprete@imtlucca.itGiorgia GiovannettiEnrico Marvasi2017-10-09T08:10:10Z2017-10-09T08:10:10Zhttp://eprints.imtlucca.it/id/eprint/3822This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38222017-10-09T08:10:10Z“Nessun dorma": International Strategies for Italian Opera HouseItalian Opera is a form of cultural expression that enjoyed significant international exposure in the past centuries and that still today is a major contributor of the global industry of opera performances. Yet, no comprehensive model is available to address international strategies of opera houses and cultural organisations in general. The paper addresses this gap, providing a framework to classify international activities in opera houses and then applying the model to four prominent Italian Opera Houses: Torino, Venezia, Firenze, Roma. Results highlights both the need for the industry to address the issue of the global presence of Italian opera houses from a business, artistic and cultural standpoint, and the conditions to be met for cultural organisations willing to strengthen their international presence.Silvia Giordanosilvia.giordano@imtlucca.itPaola DubiniAlberto Monti2017-09-28T15:25:17Z2017-09-28T15:25:17Zhttp://eprints.imtlucca.it/id/eprint/3815This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/38152017-09-28T15:25:17Z« Le thème est l’authenticité ». Une analyse de Carla Lonzi à travers le processus d’écriture de Vai pure. Dialogo con Pietro ConsagraPremières lignes
« La force de l’homme se trouve dans son identification avec la culture, la nôtre dans son refus. » Ainsi s’exprime Carla Lonzi en 1970, dans le Manifesto di Rivolta Femminile, écrit inaugural d’un des premiers et des plus influents groupes du néo-féminisme italien (fondé par Carla Lonzi, Carla Accardi et Elvira Banotti), développant de façon si irrévocable, lapidaire et « flamboyante » sa propre critique féministe touchant la politique, la société italienne et ses institutions, mais aussi la culture, l'histoire et la philosophie occidentales
Plan de l'article:
Adesso vai pure
L’enregistrement
L’écriture de Vai pure comme écriture métonymique
Réflexions conclusivesLinda Bertellilinda.bertelli@imtlucca.itMarta Equi Pierazzinimarta.equipierazzini@imtlucca.it2017-09-12T10:57:17Z2017-09-12T11:01:33Zhttp://eprints.imtlucca.it/id/eprint/3783This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37832017-09-12T10:57:17ZA Detailed Analysis of the Private/Independent Theatre Scene in IstanbulYesim Tonga Uriarteyesim.tonga@imtlucca.it2017-09-04T10:27:25Z2017-09-19T14:44:51Zhttp://eprints.imtlucca.it/id/eprint/3768This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37682017-09-04T10:27:25ZOrganizing the Global Value Chain: A firm-level testIn this paper, we study the organization of Global Value Chains on a sample of about 4,000 manufacturing parent companies integrating more than 90,000 affiliates in 150 countries. Assuming a technological sequence of production stages, a recent property rights framework (Antràs and Chor, 2013; Alfaro et al., 2015) predicts that vertical integration decisions are crucially based on both the position of a supplier along the chain and on the relative size of demand elasticities faced by the final-good producer and the supplier. In line with this, we find that if final demand is sufficiently elastic (inelastic), downstream parents, i.e. final-good producers, integrate production stages that are more proximate to (far from) final demand. However, this result is not valid in the case of midstream parents, i.e. producers of intermediate inputs that can integrate either backward or forward along the chain. We document that these companies are at least as common as are downstream parents, but the existing theory neglects them. In these cases, we find that demand elasticities do not play a significant role in integration choices. Interestingly, both midstream and downstream parents tend to integrate affiliates that are more proximate in segments of a supply chain, probably due to technological complementarities in adjacent industries.Davide Del Pretedavide.delprete@imtlucca.itArmando Rungiarmando.rungi@imtlucca.it2017-09-04T09:15:17Z2017-09-04T09:20:20Zhttp://eprints.imtlucca.it/id/eprint/3767This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37672017-09-04T09:15:17ZGlobal ownership and corporate control networksIn this contribution, at first, we introduce a basic network framework to study pyramidal structures and wedges between ownership and control of companies. Then, we apply it to a dataset of
53.5 million of companies operating in 208 countries. Among others, we detect a strong concentra-
tion of corporate power, as less than 1% of parent companies collect more than 100 subsidiaries, but
they are responsible for more than 50% of global sales. Therefore, we show that the role of indirect
control, i.e., through middlemen subsidiaries, is relevant in 15% of domestic and 54% of foreign
subsidiaries. Among foreign companies, cases emerge of blurring nationality, when control paths
cross more than one national border, in the presence of multiple passports (19.1%), indirectly for-
eign (24.5%), and round-tripping subsidiaries (1.33%). Finally, we relate indirect control strategies
to country indicators of the institutional environment. We find that pyramidal structures arise less
likely in the presence of good financial and contractual institutions in the parent's country, as these
foster more transparent forms of corporate governance. Instead, parent companies choose indirect
control through countries of subsidiaries that have better financial institutions, possibly because it
is easier to coordinate decisions from remote. Finally, we find that offshore financial centers are
preferred jurisdictions for middlemen subsidiaries, probably due to a lower taxation and a lack of
financial disclosure.Armando Rungiarmando.rungi@imtlucca.itGreg MorrisonFabio Pammolli2017-08-07T10:21:11Z2017-08-07T10:31:16Zhttp://eprints.imtlucca.it/id/eprint/3762This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37622017-08-07T10:21:11ZInferring monopartite projections of bipartite networks: an entropy-based approachBipartite networks are currently regarded as providing a major insight into the organization of many real-world systems, unveiling the mechanisms driving the interactions occurring between distinct groups of nodes. One of the most important issues encountered when modeling bipartite networks is devising a way to obtain a (monopartite) projection on the layer of interest, which preserves as much as possible the information encoded into the original bipartite structure. In the present paper we propose an algorithm to obtain statistically-validated projections of bipartite networks, according to which any two nodes sharing a statistically-significant number of neighbors are linked. Since assessing the statistical significance of nodes similarity requires a proper statistical benchmark, here we consider a set of four null models, defined within the exponential random graph framework. Our algorithm outputs a matrix of link-specific p -values, from which a validated projection is straightforwardly obtainable, upon running a multiple hypothesis testing procedure. Finally, we test our method on an economic network (i.e. the countries-products World Trade Web representation) and a social network (i.e. MovieLens, collecting the users’ ratings of a list of movies). In both cases non-trivial communities are detected: while projecting the World Trade Web on the countries layer reveals modules of similarly-industrialized nations, projecting it on the products layer allows communities characterized by an increasing level of complexity to be detected; in the second case, projecting MovieLens on the films layer allows clusters of movies whose affinity cannot be fully accounted for by genre similarity to be individuated.Fabio Saraccofabio.saracco@imtlucca.itMika J. Strakamika.straka@imtlucca.itRiccardo Di ClementeAndrea GabrielliGuido Caldarelliguido.caldarelli@imtlucca.itTiziano Squartinitiziano.squartini@imtlucca.it2017-08-04T11:32:46Z2017-08-04T11:32:46Zhttp://eprints.imtlucca.it/id/eprint/3757This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37572017-08-04T11:32:46ZMapping social dynamics on Facebook: The Brexit debateAbstract Nowadays users get informed and shape their opinion through social media. However, the disintermediated access to contents does not guarantee quality of information. Selective exposure and confirmation bias, indeed, have been shown to play a pivotal role in content consumption and information spreading. Users tend to select information adhering (and reinforcing) their worldview and to ignore dissenting information. This pattern elicits the formation of polarized groups – i.e., echo chambers – where the interaction with like-minded people might even reinforce polarization. In this work we address news consumption around Brexit in {UK} on Facebook. In particular, we perform a massive analysis on more than 1 million users interacting with Brexit related posts from the main news providers between January and July 2016. We show that consumption patterns elicit the emergence of two distinct communities of news outlets. Furthermore, to better characterize inner group dynamics, we introduce a new technique which combines automatic topic extraction and sentiment analysis. We compare how the same topics are presented on posts and the related emotional response on comments finding significant differences in both echo chambers and that polarization influences the perception of topics. Our results provide important insights about the determinants of polarization and evolution of core narratives on online debating.Michela Del Vicariomichela.delvicario@imtlucca.itFabiana Zollofabiana.zollo@imtlucca.itGuido Caldarelliguido.caldarelli@imtlucca.itAntonio ScalaWalter Quattrociocchiwalter.quattrociocchi@imtlucca.it2017-08-04T10:51:15Z2017-08-04T10:51:15Zhttp://eprints.imtlucca.it/id/eprint/3752This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37522017-08-04T10:51:15ZThe scientific impact of nations on scientific and technological developmentDetermining how scientific achievements influence the subsequent process of knowledge creation is a fundamental step in order to build a unified ecosystem for studying the dynamics of innovation and competitiveness. Yet, relying separately on data about scientific production on one side, through bibliometric indicators, and about technological advancements on the other side, through patents statistics, gives only a limited insight on the key interplay between science and technology which, as a matter of fact, move forward together within the innovation space. In this paper, using citation data of both scientific papers and patents, we quantify the direct impact of the scientific outputs of nations on further advancements in science and on the introduction of new technologies. Our analysis highlights the presence of geo-cultural clusters of nations with similar innovation system features, and unveils the heterogeneous coupled dynamics of scientific and technological success. This study represents a first step in the buildup of a comprehensive framework for knowledge creation and innovation.Aurelio PatelliGiulio Ciminigiulio.cimini@imtlucca.itEmanuele PuglieseAndrea Gabrielli2017-08-04T10:48:57Z2017-08-04T10:48:57Zhttp://eprints.imtlucca.it/id/eprint/3751This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37512017-08-04T10:48:57ZEssentiality, conservation, evolutionary pressure and codon bias in bacterial genesEssential genes constitute the core of genes which cannot be mutated too much nor lost along the adaptive evolutionary history of a species. Natural selection is expected to be stricter on essential genes and on conserved (highly shared) genes, than on genes that are either nonessential or peculiar to a single or a few species. In order to further assess this expectation, we study here how essentiality of a gene is connected with its degree of conservation among several unrelated bacterial species, each one characterised by its own codon usage bias. Confirming previous results on E- Coli, we show the existence of a universal exponential correlation between gene essentiality and conservation in bacteria. Moreover, we show that, within each bacterial genome, there are at least two groups of functionally distinct genes, characterised by different levels of conservation and codon bias: i) a core of essential genes, mainly related to cellular information processing; ii) a set of less conserved genes with prevalent functions related to metabolism. The genes in the first group are more retained among species, are subject to a relatively purifying conservative selection and display a more selected choice of synonymous codons.The core of essential genes is close to the minimal bacterial genome, which is in the focus of recent studies in synthetic biology, though we confirm that othologues of genes that are essential in one species are not necessarily essential in other species. We also list a set of highly shared genes, which could constitute a reservoir of targets for new anti-microbial drugs.Maddalena DiluccaGiulio Ciminigiulio.cimini@imtlucca.itAndrea Giansanti2017-08-04T10:42:24Z2017-08-04T10:42:24Zhttp://eprints.imtlucca.it/id/eprint/3750This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37502017-08-04T10:42:24ZUnfolding the innovation system for the development of countries: co-evolution of Science, Technology and ProductionWe show that the space in which scientific, technological and economic developments interplay with each other can be mathematically shaped using pioneering multilayer network and complexity techniques. We build the tri-layered network of human activities (scientific production, patenting, and industrial production) and study the interactions among them, also taking into account the possible time delays. Within this construction we can identify which capabilities and prerequisites are needed to be competitive in a given activity, and even measure how much time is needed to transform, for instance, the technological know-how into economic wealth and scientific innovation, being able to make predictions with a very long time horizon. Quite unexpectedly, we find empirical evidence that the naive knowledge flow from science, to patents, to products is not supported by data, being instead technology the best predictor for industrial and scientific production for the next decades.Emanuele PuglieseGiulio Ciminigiulio.cimini@imtlucca.itAurelio PatelliAndrea ZaccariaLuciano PietroneroAndrea Gabrielli2017-08-04T10:38:09Z2018-03-08T16:56:04Zhttp://eprints.imtlucca.it/id/eprint/3749This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37492017-08-04T10:38:09ZNetwork reconstruction via density samplingReconstructing weighted networks from partial information is necessary in many important circumstances, e.g. for a correct estimation of systemic risk. It has been shown that, in order to achieve an accurate reconstruction, it is crucial to reliably replicate the empirical degree sequence, which is however unknown in many realistic situations. More recently, it has been found that the knowledge of the degree sequence can be replaced by the knowledge of the strength sequence, which is typically accessible, complemented by that of the total number of links, thus considerably relaxing the observational requirements. Here we further relax these requirements and devise a procedure valid when even the the total number of links is unavailable. We assume that, apart from the heterogeneity induced by the degree sequence itself, the network is homogeneous, so that its (global) link density can be estimated by sampling subsets of nodes with representative density. We show that the best way of sampling nodes is the random selection scheme, any other procedure being biased towards unrealistically large, or small, link densities. We then introduce our core technique for reconstructing both the topology and the link weights of the unknown network in detail. When tested on real economic and financial data sets, our method achieves a remarkable accuracy and is very robust with respect to the sampled subsets, thus representing a reliable practical tool whenever the available topological information is restricted to small portions of nodes.Tiziano Squartinitiziano.squartini@imtlucca.itGiulio Ciminigiulio.cimini@imtlucca.itAndrea GabrielliDiego Garlaschellidiego.garlaschelli@imtlucca.it2017-08-04T07:29:15Z2017-08-04T07:29:15Zhttp://eprints.imtlucca.it/id/eprint/3737This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37372017-08-04T07:29:15ZWho's who in global value chains? A weighted
network approachThis paper represents global value chains (GVCs) as weighted networks of foreign value
added in exports, which allows for the identification of the specific roles of countries and
for the quantification of their relative importance over time. A major structural change
occurred in the beginning of the century as GVCs steadily turned into global networks,
amid an unprecedented growth of value-added flows and the rise of China as a major
player. First-order network metrics highlight the vital but also distinct roles of Germany,
the US, China and Japan in the international organisation of production. Germany is very relevant both as a user and as a supplier of foreign inputs, while the US acts mostly as a supplier of value added to other countries. Second-order properties of networks shed light on the complex architecture of GVCs, notably in terms of cyclical triangular relationships. Germany's GVCs mostly root in direct relationships, while Japanese ones typically involve more than two countries.João AmadorSónia CabralRossana Mastrandrearossana.mastrandrea@imtlucca.itFranco Ruzzenenti2017-08-03T07:18:17Z2017-08-03T07:18:17Zhttp://eprints.imtlucca.it/id/eprint/3732This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37322017-08-03T07:18:17ZOrganization and hierarchy of the human functional brain network lead to a chain-like coreThe brain is a paradigmatic example of a complex system: its functionality emerges as a global property of local mesoscopic and microscopic interactions. Complex network theory allows to elicit the functional architecture of the brain in terms of links (correlations) between nodes (grey matter regions) and to extract information out of the noise. Here we present the analysis of functional magnetic resonance imaging data from forty healthy humans at rest for the investigation of the basal scaffold of the functional brain network organization. We show how brain regions tend to coordinate by forming ahighly hierarchical chain-like structure of homogeneously clustered anatomical areas. A maximum spanning tree approach revealed the centrality of the occipital cortex and the peculiar aggregation of
cerebellar regions to form a closed core. We also report the hierarchy of network segregation and the level of clusters integration as a function of the connectivity strength between brain regions.Rossana Mastrandrearossana.mastrandrea@imtlucca.itAndrea GabrielliFabrizio PirasGianfranco SpallettaGuido Caldarelliguido.caldarelli@imtlucca.itTommaso Gili2017-07-17T09:56:03Z2017-07-18T09:29:07Zhttp://eprints.imtlucca.it/id/eprint/3721This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37212017-07-17T09:56:03ZFestivals, institutional maintenance and change: The case of the Lucca Comics & Games FestivalYesim Tonga Uriarteyesim.tonga@imtlucca.itRobert J. DeFilippiMassimo Riccabonimassimo.riccaboni@imtlucca.itMaria Luisa Catonimarialuisa.catoni@imtlucca.it2017-07-17T09:52:35Z2017-07-18T09:30:32Zhttp://eprints.imtlucca.it/id/eprint/3720This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37202017-07-17T09:52:35ZSpatial and sociomaterial interaction between an organized event and related informal practices: the case of temporary shops at Lucca Comics & GamesDania Marzodania.marzo@imtlucca.itYesim Tonga Uriarteyesim.tonga@imtlucca.itMaria Luisa Catonimarialuisa.catoni@imtlucca.it2017-07-17T09:10:36Z2017-07-17T09:10:36Zhttp://eprints.imtlucca.it/id/eprint/3719This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37192017-07-17T09:10:36ZSchool Infrastructure Spending and Educational Outcomes in Northern ItalyWe explore whether investment in public school infrastructure affects
students' achievement. We use data on extra funding to public
high schools after the 2012 Northern Italy earthquake and apply a
quasi-experimental design and an instrumental variable strategy. We find that spending on school infrastructure increases standardized test
scores in mathematics and Italian language, and the effect is stronger
for lower-achieving students and in mathematics. These results provide
evidence in favor of a positive impact of capital spending in improving
the learning environment and performances of high school
students.Alessandro Belmontealessandro.belmonte@imtlucca.itVincenzo BoveGiovanna D'Invernogiovanna.dinverno@imtlucca.itMarco Modica2017-05-24T08:50:13Z2017-05-24T08:50:13Zhttp://eprints.imtlucca.it/id/eprint/3703This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37032017-05-24T08:50:13ZGlobal value chains: New evidence for North AfricaAbstract This paper analyzes the participation and the position of North African countries in global value chains (GVCs). Exploiting the recently released Eora multiregional Input-Output tables, we describe regional and country {GVC} involvement. North African countries have not so far been able to fully integrate into international production networks. However, a large part of their (low) trade is due to value added related activities, mainly in the upstream phases, and the importance of foreign linkages has been increasing over time. We complement the Input-Output analysis with sectoral evidence from selected case studies and policy experiences. Overall, our results suggest that enhancing the {GVC} participation of North African countries has potential to substantially benefit local industries, countries and indeed the whole area. However, the ability to retain such benefits relies on specific local conditions, such as a favorable environment for foreign investments, and lower trade barriers, thus leaving room for policy intervention.Davide Del Pretedavide.delprete@imtlucca.itGiorgia GiovannettiEnrico Marvasi2017-05-08T12:57:15Z2017-05-08T12:57:15Zhttp://eprints.imtlucca.it/id/eprint/3701This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37012017-05-08T12:57:15ZNetworks of reinforced stochastic processes: Asymptotics for the empirical meansThis work deals with systems of interacting reinforced stochastic processes, where each process X^j = (X_{n,j})_n is located at a vertex j of a finite weighted direct graph, and it can be interpreted as the sequence of “actions” adopted by an agent j of the network. The interaction
among the evolving dynamics of these processes depends on the weighted adjacency matrix W associated to the underlying graph: indeed, the probability that an agent j chooses a certain action depends on its personal “inclination” Z_{n,j} and on the inclinations Z_{n,h} , with h not equal to j, of the other agents according to the elements of W.
Asymptotic results for the stochastic processes of the personal inclinations Z^j = (Z_{n,j})_n have
been subject of studies in recent papers (e.g. [2, 21]); while the asymptotic behavior of the stochastic
processes of the actions (X_{n,j})_n has never been studied yet. In this paper, we fill this gap by characterizing the asymptotic behavior of the empirical means N_{n,j} = \sum_{k=1}^n X_{k,j} /n, proving their almost sure synchronization and some central limit theorems in the sense of stable convergence. Moreover, we discuss some statistical applications of these convergence results concerning confidence intervals for the random limit toward which all the processes of the system converge and tools to
make inference on the matrix W.Giacomo Alettigiacomo.aletti@unimi.itIrene Crimaldiirene.crimaldi@imtlucca.itAndrea Ghigliettiandrea.ghiglietti@unimi.it2017-05-08T12:56:40Z2018-01-31T12:42:32Zhttp://eprints.imtlucca.it/id/eprint/3700This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/37002017-05-08T12:56:40ZModeling networks with a growing feature-structureWe present a new network model accounting for multidimensional assortativity. Each node is characterized by a number of features and the probability of a link between two nodes depends on common features. We do not fix a priori the total number of possible features. The bipartite network of the nodes and the features evolves according to a stochastic dynamics that depends on
three parameters that respectively regulate the preferential attachment in the transmission of the features to the nodes, the number of new features per node, and the power-law behavior of the total number of observed features.
Our model also takes into account a mechanism of triadic closure. We provide theoretical results and statistical estimators for the parameters of the model.
We validate our approach by means of simulations and an empirical analysis of a network of scientific collaborations.Irene Crimaldiirene.crimaldi@imtlucca.itMichela Del Vicariomichela.delvicario@imtlucca.itGreg Morrisongreg.morrison@imtlucca.itWalter Quattrociocchiwalter.quattrociocchi@imtlucca.itMassimo Riccabonimassimo.riccaboni@imtlucca.it2017-05-08T12:28:10Z2017-12-18T15:22:58Zhttp://eprints.imtlucca.it/id/eprint/3699This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36992017-05-08T12:28:10ZSynchronization of Reinforced Stochastic Processes with a Network-based InteractionRandomly evolving systems composed by elements which interact among each other have always been of great interest in several scientific fields. This work deals with the synchronization phenomenon, that could be roughly defined as the tendency of different components to adopt a common behavior. We continue the study of a model of interacting stochastic processes with reinforcement, that
recently has been introduced in [21]. Generally speaking, by reinforcement we mean any mechanism for which the probability that a given event occurs has an increasing dependence on the number of times that events of the same type occurred in the past. The particularity of systems of such interacting stochastic processes is that synchronization is induced along time by the reinforcement mechanism itself and does not require a large-scale limit. We focus on the relationship between the topology of the network of the interactions and the long-time synchronization phenomenon. After proving the almost sure synchronization, we provide some CLTs in the sense
of stable convergence that establish the convergence rates and the asymptotic distributions for both convergence to the common limit and synchronization. The obtained results lead to the construction of asymptotic confidence intervals for the limit random variable and of statistical tests to make inference on the topology of the network.Giacomo AlettiIrene Crimaldiirene.crimaldi@imtlucca.itAndrea Ghiglietti2017-04-03T09:39:32Z2017-08-28T15:31:01Zhttp://eprints.imtlucca.it/id/eprint/3683This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36832017-04-03T09:39:32ZAn extreme value analysis of the last century crises across industries in the U.S. economyAbstract The two large scale crises that hit the world economy in the last century, i.e. the Great Depression and the Great Recession, have similar outbreak and recovery patterns with respect to several macroeconomic variables. In particular, the largest depressions are likely to be accompanied by stock-market crashes. This study investigates the behavior of the U.S. stock market before, during and after deep downturns, focusing particularly on the tails of the return distribution. We develop two automatic procedures to identify multiple change-points in the tail of financial time series as well as in the co-crash and co-boom probabilities of different markets. We then apply our methodology to twelve time series representative of the sectors of the U.S. economy. We find that regime shifts in the lower tail of the distribution tend to co-occur before deep downturns. Our results contribute to a better understanding of the origin and systemic nature of large scale events to make policy interventions more timely and effective.Marco BeeMassimo Riccabonimassimo.riccaboni@imtlucca.itLuca Trapinluca.trapin@imtlucca.it2017-03-21T10:30:16Z2017-04-12T14:47:50Zhttp://eprints.imtlucca.it/id/eprint/3663This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36632017-03-21T10:30:16ZThe “Smile Curve”: where Value is Added along
Supply ChainsIn this paper we analyze where value is added along supply chains on a sample of more than 2
million of firms in the European Union. We detect a non-linear U-shaped relationship between the
value added generated by firms and their position on a productive sequence, for which tasks at the
top and at the bottom show higher value added. Our findings are in line with previous hypotheses
on the existence of a so-called 'smile curve', resumed by both business and economic studies and
discussed at length in international fora. Our results are robust to different empirical strategies for
flexible functional forms. As far as we know, ours is the first firm-level successful attempt to test
for value generation along supply chains. Further, we find empirical support for a phenomenon of
domestic retention of value added by MNEs, which may prefer keeping at home the tasks at higher
potential to safeguard present and future competitive advantages. By country, intermediate stages
of production are at higher value when performed by foreign as liates, whereas domestic producers
retain higher value at the very top and at the very bottom of the supply chain, organized either
as independent suppliers or as domestic affiliates. Although an economic theory is still missing
for explaining how and why value generation is non-linear along a typical technological sequence,
here we argue that a microfoundation with firm-level data is useful for understanding the growth
potential of countries' specialization patterns along different segments of supply chains.Armando Rungiarmando.rungi@imtlucca.itDavide Del Pretedavide.delprete@imtlucca.it2017-03-21T09:54:10Z2017-03-21T09:54:10Zhttp://eprints.imtlucca.it/id/eprint/3662This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36622017-03-21T09:54:10ZThe census of Enterprise Archives as an Opportunity for the Business. How to teach businessmen to boost their business through their archives, their own energy.Gemma Torregemma.torre@imtlucca.it2017-03-10T08:59:24Z2017-03-21T11:08:28Zhttp://eprints.imtlucca.it/id/eprint/3660This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36602017-03-10T08:59:24ZThe Indirect Effects of FDI on Trade: A Network PerspectiveThe relationship between international trade and foreign direct invest-
ment (FDI) is one of the main features of globalization. In this paper
we investigate the effects of FDI on trade from a network perspective,
since FDI takes not only direct but also indirect channels from origin to
destination countries because of firms' incentive to reduce tax burden,
to minimize coordination costs, and to break barriers to market entry.
We use a unique data set of international corporate control as a measure
of stock FDI to construct a corporate control network (CCN) where the
nodes are the countries and the edges are the corporate control relation-
ships. Based on the CCN, the network measures, i.e., the shortest path
length and the communicability, are computed to capture the indirect
channel of FDI. Empirically we find that corporate control has a positive
effect on trade both directly and indirectly. The result is robust with dif-
ferent specifications and estimation strategies. Hence, our paper provides
strong empirical evidence of the indirect effects of FDI on trade. More-
over, we identify a number of interplaying factors such as regional trade
agreements and the region of Asia. We also find that the indirect effects
are more pronounced for manufacturing sectors than for primary sectors
such as oil extraction and agriculture.Rodolfo MetuliniMassimo Riccabonimassimo.riccaboni@imtlucca.itPaolo Sgrignolipaolo.sgrignoli@alumni.imtlucca.itZhen Zhuzhen.zhu@imtlucca.it2017-02-16T09:32:22Z2017-03-21T11:00:55Zhttp://eprints.imtlucca.it/id/eprint/3653This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36532017-02-16T09:32:22ZAgriculture and Food Global Value Chains in Sub-Saharan Africa: Does bilateral trade policy impact on backward and forward participation?The most recent literature on international trade highlights the key role of global value chains (GVCs) in structural transformation, development and growth. The common perception is that Africa, unlike most Latin American and Asian countries, has neither been able to intercept the main changes in trade patterns nor enter massively into global production networks. This work provides some insight into this topic. Using the EORA Input-Output Tables, we analyze whether bilateral import tariffs and shifts in trade regimes associated with regional trade agreements affect the backward participation (i.e., the use of foreign inputs for exports) and forward participation (i.e., the use of domestic intermediates in third country exports) of the SSA countries’ agriculture and food GVCs. Our results show that, despite their low world trade shares, GVC participation in SSA economies is increasing over time, mainly upstream as suppliers of unprocessed inputs. Furthermore, we show that the value added demand for SSA agricultural products primarily originates from the EU and emerging countries rather than from regional partners. Finally, by making use of a “gravity-like” identification strategy, we also find evidence that bilateral trade protection significantly affects GVC backward and forward participation in agriculture and food. These results call for a refinement of trade policy priorities in SSA.Jean BalièDavide Del Pretedavide.delprete@imtlucca.itEmiliano MagriniPierluigi MontalbanoSilvia Nenci2017-01-31T10:17:27Z2017-03-21T11:05:23Zhttp://eprints.imtlucca.it/id/eprint/3650This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36502017-01-31T10:17:27ZVirtual Water Trade and Bilateral ConflictsIn light of growing water scarcity, virtual water, or the water embedded in key water-intensive commodities, has been an active area of debate among practitioners and academics alike. As of yet, however, there is no consensus on whether water scarcity affects conflict behavior and we still lack empirical research intending to account for the role of virtual water in affecting the odds of militarized disputes between states. Using quantitative methods and data on virtual water trade, we find that bilateral and multilateral trade openness reduce the probability of war between any given pair of country, which is consistent with the strategic role of this important commodity and the opportunity cost associated with the loss of trade gains. We also find that the substantive effect of virtual water trade is comparable to that of oil and gas, the archetypal natural resources, in determining interstate conflicts’ probability.Enrico De AngelisRodolfo MetuliniVincenzo BoveMassimo Riccabonimassimo.riccaboni@imtlucca.it2017-01-10T15:51:43Z2017-01-10T15:51:43Zhttp://eprints.imtlucca.it/id/eprint/3628This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36282017-01-10T15:51:43ZThe potential costs of Longevity Risk on Public Pensions. Evidence from Italian dataIn this article, we assess, through an empirical investigation based on Italian data, how
uncertainty regarding future mortality may affect public pension expenditure. Based
on a representative sample of Italian pensioners from 1985 to 2011, we find a consistent
underestimation of improvements seen in mortality and life expectancy when forecasts
are based on expectations. The pension expenditure estimated using realized mortality
rates is shown to be consistently higher than that obtained by using average forecasted
scenarios, produced with well-known stochastic mortality models. The paper highlights
the importance of considering the uncertainty regarding future pension benfits, i.e. of
evaluating and managing the longevity risk in public pension plans.Benedetta Frassibenedetta.frassi@imtlucca.itFabio PammolliLuca Regis2016-02-12T11:11:36Z2018-03-08T09:33:53Zhttp://eprints.imtlucca.it/id/eprint/3056This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/30562016-02-12T11:11:36ZKnowledge Spillovers through Networks of ScientistsIn this paper I directly test the hypothesis that interactions between inventors of different
firms drive knowledge spillovers. I construct a network of publicly traded companies
in which each link is a function of the relative proportion of two firms’ inventors who
have former patent collaborators in both organizations. I use this measure to weigh the
impact of R&D performed by each firm on the productivity and innovation outcomes
of its network linkages. An empirical concern is that the resulting estimates may reflect
unobserved, simultaneous determinants of firm performance, network connections and
external R&D. I address this problem with an innovative IV strategy, motivated by a
game-theoretic model of firm interaction. I instrument the R&D of one firm’s connections
with that of other firms that are sufficiently distant in network space. With the
resulting spillover estimates, I calculate that among firms connected to the network
the marginal social return of R&D amounts to approximately 112% of the marginal
private returnPaolo Zacchiapaolo.zacchia@imtlucca.it