During the last decades, it has become clear that systems formed by many interacting parts show emergent dynamical properties which are inherently related to the topology of the underlying pattern of connections among the constituent parts. Such systems, usually known as complex systems, are in general suitably described through their networks of contacts, that is, in terms of nodes (representing the system's components) and edges (standing for their interactions), which allows to catch their essential features in a simple and general representation. In recent years, increasing interest on this approach, thanks also to a favorable technological progress, led to the accumulation of an increasing amount of data. This situation has allowed the arising of new questions and, therefore, the diversification of the scientific work. Among them, we can point out three general issues that have been receiving a lot of interest: (i) is the available information always reliable and complete? (ii) how does a complex interaction pattern affect the emergence of collective behavior in complex systems? And (iii) which is the role of mobility within the framework of complex networks? This thesis has been developed along these three lines, which are strictly interrelated. We expand on three case-studies, each one of which deals with two the above mentioned macro-issues. We consider the issue of the incompleteness of the available information both in the case of natural (Chapter 2) and artificial (Chapter 3) networks. As a paradigmatic emergent behavior, we focus on the synchronization of coupled phase oscillators (Chapter 2 and Chapter 4), deeply investigating how different patterns of connections can affect the achievement of a globally coherent state. Finally, we include moving agents in two different frameworks, using them as explorers of unknown networks (Chapter 3) and considering them as interacting units able to establish connections with their neighbors (Chapter 4). In Chapter 2, we study the problem of the reconstruction of an unknown interaction network, whose nodes are Kuramoto oscillators. Our aim is to extract topological features of the connectivity pattern from purely dynamical measures, based on the fact that in a heterogeneous network the global dynamics is not only affected by the distribution of the natural frequencies but also by the location of the different values. The gathered topological information ranges from local features, such as the single node connectivity, to the hierarchical structure of functional clusters, and even to the entire adjacency matrix. In Chapter 4, instead, we present a model of integrate and fire oscillators that are moving agents, freely displacing on a plane. The phase of the oscillators evolves linearly in time and when it reaches a threshold value they fire at their neighbors. In this way, the interaction network is a dynamical object by itself since it is re-created at each time step by the motion of the units. Depending on the velocity of the motion, the average number of neighbors, the coupling strength and the size of the agents population, we identify different regimes. Moving agents are employed also in Chapter 3 where they play the role of explorers of unknown artificial networks, having the mission to recover information about their structures. We propose a model in which random walkers with previously assigned home nodes navigate through the network during a fixed amount of time. We consider that the exploration is successful if the walker gets the information gathered back home, otherwise, no data is retrieved. We show that there is an optimal solution to this problem in terms of the average information retrieved and the degree of the home nodes and design an adaptive strategy based on the behavior of the random walker. / Durante las últimas décadas, se ha empezado a poner de manifiesto que sistemas formados por muchos elementos en interacción pueden mostrar propiedades dinámicas emergentes relacionadas con la topología del patrón de conexiones entre las partes constituyentes. Estos sistemas, generalmente conocidos como sistemas complejos, en muchos casos pueden ser descritos a través de sus redes de contactos, es decir, en términos de nodos (que representan los componentes del sistema) y de enlaces (sus interacciones). De esta manera es posible capturar sus características esenciales en una representación simple y general. En esta última década, el creciente interés en este enfoque, gracias también a un progreso tecnológico favorable, ha llevado a la acumulación de una cantidad ingente de datos. Eso, a su vez, ha permitido el surgimiento de nuevas preguntas y, por lo tanto, la diversificación de la actividad científica. Entre ellas, podemos destacar tres cuestiones generales que son objeto de mucho interés: (i) ¿la información disponible es siempre fiable y completa? (ii) ¿cómo un patrón de interacción complejo puede afectar el surgimiento de comportamientos colectivos? Y (iii) ¿cual es el papel de la movilidad en el marco de las redes complejas? Esta tesis se ha desarrollado siguiendo estas tres líneas, que están íntimamente relacionadas entre sí. Hemos profundizado en tres casos de estudio, cada uno de los cuales se ocupa de dos de los macro-temas mencionados. Consideramos la cuestión del carácter incompleto de la información disponible tanto en el caso de redes naturales (Capítulo 2) como de redes artificiales (Capítulo 3). Nos centramos en la sincronización de los osciladores de fase acoplados (Capítulos 2 y 4) en cuanto comportamiento emergente paradigmático, investigando en profundidad cómo los diferentes patrones de conexión puedan afectar la consecución de un estado coherente a nivel global. Por último, analizamos el rol de la movilidad incluyendo agentes móviles en dos marcos diferentes. En un caso, los utilizamos como exploradores de redes desconocidas (Capítulo 3), mientras que en otro los consideramos como unidades que interaccionan y son capaces de establecer conexiones con sus vecinos (Capítulo 4).

La recollida d'emergències produïdes a l'espai públic permet estudiar la fragilitat de l'ordre públic i com s'empren estratègies per controlar i evitar situacions de crisi.El treball etnogràfic desenvolupat a Barcelona, Hospitalet de Llobregat i Lloret de Mar recollint aquest tipus d'emergències, i en els dos últims municipis esmentats concretament les emergències abordades per la policia, ha permès observar fins a quin punt les emergències crítiques mostren el risc de fractura, però igualment, l'esforç que els membres de la comunitat fan per que aquest no es trenqui, i així poder mantenir les seves legítimes expectatives envers l'assoliment de les fites de la seva quotidianitat.També, mitjançant el paper de la majoria davant l'emergència, que pot passar per ignorar-la, observar-la des de la distància, estudiar-la amb deteniment i recollir la possible informació que es desprengui del seu desenvolupament o participar-ne en considerar que cal activar xarxes socials de recolzament o solidaritat, es possible entendre fins a quin punt es fa palès que per la societat, com diu Isaac Joseph citant a Erving Goffman, és més important restablir l'ordre social, vehicle i via per poder continuar amb el que fem, que aturar o neutralitzar als contraventors. Es visibilitza també fins a quin punt, sabedors de la nostra major vulnerabilitat en l'arena social jugada en l'espai públic, per una part prenem mesures de defensa en forma de distàncies, fugides, canvis de ritme, observacions a distància, xarxes instantànies de solidaritat, i recollim experiències i informació sobre emergències per una altra, per tal que aquest bagatge ens ajudi en el moment en que nosaltres siguem subjectes actius de l'emergència.Tanmateix, és possible albirar a través de la resposta de la policia davant l'emergència, la intenció del Poder, que es fonamenta tant en mirar de garantir aquestes expectatives de "via expedita" social que les persones exigeixen dels responsables de la gestió social, com de minimitzar la poderosa evidència que la seguretat no es pot garantir, així com d'invisibilitzar fins a quin punt és de flexible i porós l'ordre social i, per tant, quant subjecte està el seu canvi a la voluntat i acció de cadascun dels membres de la comunitat.S'ha visibilitzat també com tot el que es relaciona amb l'emergència és ubicat apart per la societat, sense reconèixer que és una faceta més de la dimensió social, només que des de la vessant opaca i de la que se'n reclama una antropologia que s'hi dediqui. Ans al contrari, es demonitza tot el que s'hi relaciona, ja siguin autors d'emergències, com víctimes de les mateixes o els llocs on aquestes es produeixen i, també, a aquells qui hi estan en contacte, com la policia i els i les agents de policia. A més, aquests són estigmatitzats i ubicats per la majoria en el costat opac i són considerats font de risc, problemes i conflicte en mateixa o semblant mesura a l'emergència i els seus autors. / The collection of emergencies produced in the public space allows to study the fragility of the public order and how strategies are used to controlling and avoiding situations of crisis.The ethnographic work developed picking up this type of emergencies, specially the emergencies approached by the police, has allowed to observe how much the critical emergencies show the risk of fracture, but equally, the effort that the members of the community make for this does not break, and like this to be able to sustain their legitimate expectations towards the attainment of the milestones of their everyday life.Also, through the role of the majority in the face of the emergency, the basic strategies are build around our survival possibilities in the public space, between the rest of the people who wants different thinks in different ways, making possible to understand until which point for the society, how Isaac Joseph quoting in Erving Goffman says, it is more important to reinstate the social order, vehicle and way to be able to continue with what we make, that to halt or to neutralize to the contraveners. However, it is possible to see through the answer of the police in the face of the emergency, the intention of the Power, that founds so much in trying to guarantee these expectations of freedom in our everyday life that the persons require of the responsibles for the social management, as of minimizing the powerful evidence that not even the security is garantible, as well as keep out of sight how much is flexible and porous the social order and, therefore, how much subject its change is on the will and share of each of the members of the community.The research shows also like all what correlates with the emergency is placed aside by the society, without recognizing that a facet is from the social dimension more, if only from the opaque aspect and of the one who an anthropology claims from herself dedicates to it. The fact is that society puts in the same dark hole all what correlates with it, they are already authors of emergencies, like victims of the same ones, or the places where these are produced and, also, to those who they are in touch, like the Police and the police officers.