Time filter

Source Type

De Domenico M.,Rovira i Virgili University | Sole-Ribalta A.,Rovira i Virgili University | Omodei E.,Rovira i Virgili University | Omodei E.,Ecole Normale Superieure de Paris | And 4 more authors.
Nature Communications | Year: 2015

The determination of the most central agents in complex networks is important because they are responsible for a faster propagation of information, epidemics, failures and congestion, among others. A challenging problem is to identify them in networked systems characterized by different types of interactions, forming interconnected multilayer networks. Here we describe a mathematical framework that allows us to calculate centrality in such networks and rank nodes accordingly, finding the ones that play the most central roles in the cohesion of the whole structure, bridging together different types of relations. These nodes are the most versatile in the multilayer network. We investigate empirical interconnected multilayer networks and show that the approaches based on aggregating - or neglecting - the multilayer structure lead to a wrong identification of the most versatile nodes, overestimating the importance of more marginal agents and demonstrating the power of versatility in predicting their role in diffusive and congestion processes. © 2015 Macmillan Publishers Limited. All rights reserved. Source

Granell C.,Rovira i Virgili University | Gomez S.,Rovira i Virgili University | Arenas A.,Rovira i Virgili University | Arenas A.,Institute Catala Of Paleoecologia Humana I Evolucio Social
Physical Review Letters | Year: 2013

We present the analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the information awareness to prevent its infection, on top of multiplex networks. This scenario is representative of an epidemic process spreading on a network of persistent real contacts, and a cyclic information awareness process diffusing in the network of virtual social contacts between the same individuals. The topology corresponds to a multiplex network where two diffusive processes are interacting affecting each other. The analysis using a microscopic Markov chain approach reveals the phase diagram of the incidence of the epidemics and allows us to capture the evolution of the epidemic threshold depending on the topological structure of the multiplex and the interrelation with the awareness process. Interestingly, the critical point for the onset of the epidemics has a critical value (metacritical point) defined by the awareness dynamics and the topology of the virtual network, from which the onset increases and the epidemics incidence decreases. © 2013 American Physical Society. Source

Hortola P.,Rovira i Virgili University | Hortola P.,Institute Catala Of Paleoecologia Humana I Evolucio Social
Microscopy and Microanalysis | Year: 2013

Studies of human bloodstains on nonbiological materials have been previously carried out using a high-vacuum scanning electron microscope (HV-SEM) in secondary-electron mode without any sample treatment. To assess whether biological substrates can affect the morphology of human erythrocytes in bloodstains, three fragments of different biological material (bone, shell, and wood) were smeared with peripheral human blood. Afterward, the bloodstains were directly examined in secondary-electron mode by an HV-SEM following a procedure initially standardized to be used in uncoated human bloodstains on stone. The obtained results suggest that HV-SEM is suitable for examining untreated bloodstains on biological substrate and that the morphology of erythrocytes in human bloodstains is not affected by the biological nature of the substrate. A cautionary issue regarding bloodstains on nondehydrated biological substrates is that the waiting time required for initiating the HV-SEM examination is by far higher than when using inorganic bloodstain substrates. © Microscopy Society of America 2013. Source

Radicchi F.,Indiana University | Radicchi F.,Rovira i Virgili University | Arenas A.,Rovira i Virgili University | Arenas A.,Institute Catala Of Paleoecologia Humana I Evolucio Social
Nature Physics | Year: 2013

Our world is linked by a complex mesh of networks through which information, people and goods flow. These networks are interdependent on each other, and present structural and dynamical features different from those observed in isolated networks. Although examples of such dissimilar properties are becoming more abundant - such as in diffusion, robustness and competition - it is not yet clear where these differences are rooted. Here we show that the process of building independent networks into an interconnected network of networks undergoes a structurally sharp transition as the interconnections are formed. Depending on the relative importance of inter- and intra- layer connections, we find that the entire interdependent system can be tuned between two regimes: in one regime, the various layers are structurally decoupled and they act as independent entities; in the other regime, network layers are indistinguishable and the whole system behaves as a single-level network. We analytically show that the transition between the two regimes is discontinuous even for finite-size networks. Thus, any real-world interconnected system is potentially at risk of abrupt changes in its structure, which may manifest new dynamical properties. © 2013 Macmillan Publishers Limited. Source

Blasco R.,Rovira i Virgili University | Blasco R.,Institute Catala Of Paleoecologia Humana I Evolucio Social | Fernandez Peris J.,Servei dInvestigacio Prehistorica SIP
Quaternary International | Year: 2012

The exploitation strategies of faunal resources have figured prominently in discussions of the timing and nature of the beginning of modern human behaviour. These strategies have focused on ability to make intensive use of seasonal resources, ability to hunt large or dangerous animals and capacity to exploit small prey, specifically fast-running and flying animals. On this basis, the systematic use of small animals for food at the pre-Upper Palaeolithic moments has been an important debate topic in recent decades. Occasional anthropogenic evidences concerning these animals dates back to the Plio-Pleistocene chronologies in Africa. Nevertheless, several authors state that the small animals began to be important in the human diet from at least the early Middle Palaeolithic in the Mediterranean Basin. From this perspective, this paper discusses the human use of small prey (rabbits, birds and tortoises) in the stratigraphical sequence of Bolomor Cave (Valencia, Spain). This site contains a sedimentary deposit composed of seventeen stratigraphical levels ranging from MIS 9 to MIS 5e (c. 350-100 ka). The evidence of anthropogenic processing of small prey is documented from the earliest moments of the site occupation (level XVII) in form of cutmarks, intentional breakage, human toothmarks, and burning patterns, depending on the archaeological level. The use of small animals, attached to the large game identified in the site, indicate generalist human behaviour based on a broad spectrum diet. In general, the aim of this study is to provide data on the subsistence strategies of the Middle Pleistocene hominids from Bolomor Cave and to contribute to the discussion topic related to the human consumption of small prey in early moments. © 2011 Elsevier Ltd and INQUA. Source

Discover hidden collaborations