Coupling Human Mobility and Social Ties

Studies using massive, passively data collected from communication technologies have revealed many ubiquitous aspects of social networks, helping us understand and model social media, information diffusion, and organizational dynamics. More recently, these data have come tagged with geographic information, enabling studies of human mobility patterns and the science of cities. We combine these two pursuits and uncover reproducible mobility patterns amongst social contacts. First, we introduce measures of mobility similarity and predictability and measure them for populations of users in three large urban areas. We find individuals' visitations patterns are far more similar to and predictable by social contacts than strangers and that these measures are positively correlated with tie strength. Unsupervised clustering of hourly variations in mobility similarity identifies three categories of social ties and suggests geography is an important feature to contextualize social relationships. We find that the composition of a user's ego network in terms of the type of contacts they keep is correlated with mobility behavior. Finally, we extend a popular mobility model to include movement choices based on social contacts and compare it's ability to reproduce empirical measurements with two additional models of mobility

Footbridge over the Sant Adria Marina in Barcelona, Spain

This paper presents a description of a continuous truss footbridge comprising two spans, one of 140 m and the other 50 m. The bridge crosses the Sant Adria Marina, close to Barcelona. The width of the deck is 6 m and the depth of the two trusses, which form the bridge, range between 6 and 10 m. Main innovations are the use of recycled aggregates for concrete in the approach slab deck, the use of silica fume concrete for the pavement which performs well from the strength, durability and aesthetic points of view and the formal exploration of irregular longitudinal layouts in truss bridges. This formal exploration resulted in the creation of an internal space extremely pleasant for people and avoiding any tunnel sensation. Moreover, the absence of dynamic loads and the light live load allowed the trusses to be designed without using gusset plates.Peer Reviewe