5,655 research outputs found
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 artĂculo analiza las semejanzas y divergencias entre ambos procesos histĂłricos. El principal elemento comĂşn es la importancia de las ciudades y de sus Ă©lites urbanas en la Europa bajo imperial y en la AmĂ©rica hispana virreinal. La principal diferencia radica en la duraciĂłn del proceso de fragmentaciĂłn: 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 rĂ´le 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
Presupuestos ideolĂłgicos de la actuaciĂłn de Roma durante el proceso de la conquista de Hispania
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