Fractional Integration and Structural Breaks in U.S. Macro Dynamics

This paper identifies structural breaks in the post-World War II joint dynamics of U.S. inflation, unemployment and the short-term interest rate. We derive a structural break-date procedure which allows for long-memory behavior in all three series and perform the analysis for alternative data frequencies. Both long-memory and short-run coefficients are relevant for characterizing the changing patterns of U.S. macroeconomic dynamics. We provide an economic interpretation of those changes by examining the link between macroeconomic events and structural breaks.Fractional integration, structural breaks, multivariate analysis, inflation dynamics

Imperios en fragmentación: Occidente Romano y América Hispana. Estructuras convergentes y tiempos diferentes

El artículo analiza las semejanzas y divergencias entre ambos procesos históricos. El principal elemento común es la importancia de las ciudades y de sus élites urbanas en la Europa bajo imperial y en la América hispana virreinal. La principal diferencia radica en la duración del proceso de fragmentación: más de un siglo en la primera y apenas dos decenios en la segunda.The paper analyzes the similarities and the differences between the two historical processes. The main comun factor is the decisive rôle of the cities and their urban elites in the Later Roman Empire and in the Virreinal America. The main differency is the time lastings of both movements of political fragmentation: more than a century in the first one and near two decennies in the second one

Celtic Place- and Personal-names in Spain and the Socio-political Structure and Evolution of the Celtiberians

In this paper two Celtiberian place- and personal-names are examined: Moericus, the name of a Celtiberian war chief in the Second Punic War, and Complega, a town founded by Celtiberian mavericks and conquerd by praetor Fulvius Flaccus in 182 B.C. This indicates that two very important political and social institutions of the La Tène Celts are documented in Celtiberian Spain at an early date: the armed retinue that accompanied a chief with a name ended in –rix, and the armed mercenary bands that migrated long distances to conquer land and found new townships

Centrality anomalies in complex networks as a result of model over-simplification

Tremendous advances have been made in our understanding of the properties and evolution of complex networks. These advances were initially driven by information-poor empirical networks and theoretical analysis of unweighted and undirected graphs. Recently, information-rich empirical data complex networks supported the development of more sophisticated models that include edge directionality and weight properties, and multiple layers. Many studies still focus on unweighted undirected description of networks, prompting an essential question: how to identify when a model is simpler than it must be? Here, we argue that the presence of centrality anomalies in complex networks is a result of model over-simplification. Specifically, we investigate the well-known anomaly in betweenness centrality for transportation networks, according to which highly connected nodes are not necessarily the most central. Using a broad class of network models with weights and spatial constraints and four large data sets of transportation networks, we show that the unweighted projection of the structure of these networks can exhibit a significant fraction of anomalous nodes compared to a random null model. However, the weighted projection of these networks, compared with an appropriated null model, significantly reduces the fraction of anomalies observed, suggesting that centrality anomalies are a symptom of model over-simplification. Because lack of information-rich data is a common challenge when dealing with complex networks and can cause anomalies that misestimate the role of nodes in the system, we argue that sufficiently sophisticated models be used when anomalies are detected.Comment: 14 pages, including 9 figures. APS style. Accepted for publication in New Journal of Physic

Disenso religioso y hegemonía política.

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Presupuestos ideológicos de la actuación de Roma durante el proceso de la conquista de Hispania

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