Human behavioural patterns : A reality mining study

Mobile phone communication is a source of information for studying human behavioural patterns. A mobile phone can collect information of its usage, communication events and data captured by integrated sensors, and this information has been used for studying mobility, epidemics, health and depression, and information diffusion. Particularly, the call detail records have been used to study different social features, like the network structure, people's sleeping patterns, and response to natural disasters. They provides useful insights about the behaviour of the people involved in the calls. This dissertation is based on four research articles in which a huge data set containing call details records of around 3 million users over a 12-month period in 2007 is analysed, to study the dynamics of the human daily resting periods and human social focus over the life course. Each day, the calling activity of the mobile phone users follows two different circadian rhythms, each one synchronised to a different clock. On one hand there is the clock of social time, marked by social activities of the daily routine, in which the working and schooling times, opening times of offices, etc, set a specific social schedule to follow. On the other hand, some human physiological processes, like the human sleep-wake cycle, follow a natural 24h cycle, entrained to a biological clock. The calling pattern shows the struggle of living between these two clocks. It follows a specific schedule (it peaks and decreases twice each day, showing a strong dependence on social time). The location and size of the peaks of activity change over the year, by expanding during the summer and shrinking during the winter, thus indicating a seasonal dependence. Moreover, people living in the same time zone but at different locations, are found to start (or cease) their activity at different times, with a difference given by their local sun transit times, thus people living eastward in the time zone have earlier schedules than those living westward. The emotional closeness between users and their contacted alters can be determined based on their communication pattern. The level of interaction between a mobile phone user and the alters in his/her egocentric network is different, having a dominant interaction with the romantic partner. The features of the ego-centric network and the social focus invested on alters depends on the age and gender of the user, showing clear changes as the users go through different life course stages. Younger people contact more alters and more frequently but this changes noticeably as the egos cross the parenthood stage, in such a way that when egos reach old age, the size of the egocentric network has considerably decreased and it is mainly populated by alters younger then the ego. At the grand-parenting age, an important gender difference appears, when females (probably crossing menopause) show a strong change in social focus towards their daughters, who are in the reproductive stage, whereas males remain focused mainly on their romantic partners, providing supporting arguments for the grand-mothering hypothesis

Influence spreading model in analysing ego-centric social networks

| openaire: EC/H2020/871042/EU//SoBigData-PlusPlusIn an earlier study one of us had developed a model of influence spreading for analysing human behaviour and interaction with others in a social network. Here we apply this model and corresponding influence centrality measures to real data of mobile phone call detail records. From this we get structures of human ego-centric networks and use a simple model, based on the number of phone calls, to describe the strengths of social relationships. To analyse 48,000 egos in their ego-centric networks we define normalised out-centrality and in-centrality influence measures, by dividing with out-degree and in-degree, respectively. With these and the betweenness centrality measures, we analyse the influence spreading in the ego-centric networks under different scenarios of link strengths between individuals reflecting the network structure being either interaction or connectivity oriented. The model reveals characteristics of social behaviour that are not obvious from the data analysis of raw empirical data or from theresults of standard centrality measures. A transition is discovered in behaviour from young to older age groups for both genders and in both normalised out-centrality and in-centrality as well as betweenness centrality results.Peer reviewe

Parallel numerical simulation of two-phase flow model in porous media using distributed and shared memory architectures

En este trabajo se estudia un modelo de flujo bifásico (agua-aceite) en un medio poroso homogéneo considerando un desplazamiento inmiscible e incompresible. Este modelo se resuelve numéricamente usando el Método de Volumen Finito (FVM) y se comparan cuatro esquemas numéricos para la aproximación de los flujos en las caras de los volúmenes discretos. Se describe brevemente cómo obtener los modelos matemático y computacional aplicando la formulación axiomática y programación genérica. También, implementa dos estrategias de paralelización para reducir el tiempo de ejecución. Se utilizan arquitecturas de memoria distribuida (clusters de CPUs) y memoria compartida (Tar-jetas gráficas GPUs). Finalmente se realiza una comparación del desempeño de estas dos arquitecturas junto con un análisis de los cuatro esquemas numéricos para un patrón de flujo de inyección de agua, con un pozo inyector y cuatro pozos productores (five-spot pattern). doi: https://doi.org/10.1016/S0016-7169(14)71490-

Human-agent coordination in a group formation game

| openaire: EC/H2020/662725/EU//IBSEN | openaire: EC/H2020/654024/EU//SoBigData | openaire: EC/H2020/871042/EU//SoBigData-PlusPlusCoordination and cooperation between humans and autonomous agents in cooperative games raise interesting questions on human decision making and behaviour changes. Here we report our findings from a group formation game in a small-world network of different mixes of human and agent players, aiming to achieve connected clusters of the same colour by swapping places with neighbouring players using non-overlapping information. In the experiments the human players are incentivized by rewarding to prioritize their own cluster while the model of agents’ decision making is derived from our previous experiment of purely cooperative game between human players. The experiments were performed by grouping the players in three different setups to investigate the overall effect of having cooperative autonomous agents within teams. We observe that the human subjects adjust to autonomous agents by being less risk averse, while keeping the overall performance efficient by splitting the behaviour into selfish and cooperative actions performed during the rounds of the game. Moreover, results from two hybrid human-agent setups suggest that the group composition affects the evolution of clusters. Our findings indicate that in purely or lesser cooperative settings, providing more control to humans could help in maximizing the overall performance of hybrid systems.Peer reviewe

Dynamics of hierarchical weighted networks of Van der Pol oscillators

We investigate the dynamics of regular fractal-like networks of hierarchically coupled van der Pol oscillators. The hierarchy is imposed in terms of the coupling strengths or link weights. We study the low frequency modes, as well as frequency and phase synchronization, in the network by a process of repeated coarse-graining of oscillator units. At any given stage of this process, we sum over the signals from the oscillator units of a clique to obtain a new oscillating unit. The frequencies and the phases for the coarse-grained oscillators are found to progressively synchronize with the number of coarse-graining steps. Furthermore, the characteristic frequency is found to decrease and finally stabilize to a value that can be tuned via the parameters of the system. We compare our numerical results with those of an approximate analytic solution and find good qualitative agreement. Our study on this idealized model shows how oscillations with a precise frequency can be obtained in systems with heterogeneous couplings. It also demonstrates the effect of imposing a hierarchy in terms of link weights instead of one that is solely topological, where the connectivity between oscillators would be the determining factor, as is usually the case. Many oscillatory signaling processes in nature are multi-scale, where the characteristic macro-scale frequency of the signal is an emergent property of the coupling of oscillators of different frequencies acting on the micro-scale. Here, we show, using a combination of numerical simulations and analytical investigations, how oscillations of a precise frequency can be obtained from a fractal network of oscillators when the coupling is heterogeneous. Our results on various hierarchically coupled networks shed light on how the frequencies synchronize and the phases become locked at various scales. Our model also shows how the concept of hierarchy can be realized when studying synchronization in weighted networks