http://hdl.handle.net/10016/5861 Wed, 22 May 2013 17:54:13 GMT 2013-05-22T17:54:13Z http://hdl.handle.net/10016/16942 Title: The predictability of consumer visitation patterns Author(s): Krumme, Coco; Llorente, Alejandro; Cebrián, Manuel; Pentland, Alex; Moro, Esteban Abstract: We consider hundreds of thousands of individual economic transactions to ask: how predictable are consumers in their merchant visitation patterns? Our results suggest that, in the long-run, much of our seemingly elective activity is actually highly predictable. Notwithstanding a wide range of individual preferences, shoppers share regularities in how they visit merchant locations over time. Yet while aggregate behavior is largely predictable, the interleaving of shopping events introduces important stochastic elements at short time scales. These short- and long-scale patterns suggest a theoretical upper bound on predictability, and describe the accuracy of a Markov model in predicting a person's next location. We incorporate population-level transition probabilities in the predictive models, and find that in many cases these improve accuracy. While our results point to the elusiveness of precise predictions about where a person will go next, they suggest the existence, at large time-scales, of regularities across the population. Wed, 17 Apr 2013 22:00:00 GMT http://hdl.handle.net/10016/16942 2013-04-17T22:00:00Z http://hdl.handle.net/10016/16052 Title: Universality of cauliflower-like fronts: from nanoscale thin films to macroscopic plants Author(s): Castro, Mario; Cuerno, Rodolfo; Nicoli, Matteo; Vázquez, Luis; Buijnsters, Josephus G. Abstract: Chemical vapor deposition (CVD) is a widely used technique to grow solid materials with accurate control of layer thickness and composition. Under mass-transport-limited conditions, the surface of thin films thus produced grows in an unstable fashion, developing a typical motif that resembles the familiar surface of a cauliflower plant. Through experiments on CVD production of amorphous hydrogenated carbon films leading to cauliflower-like fronts, we provide a quantitative assessment of a continuum description of CVD interface growth. As a result, we identify non-locality, non-conservation and randomness as the main general mechanisms controlling the formation of these ubiquitous shapes.We also show that the surfaces of actual cauliflower plants and combustion fronts obey the same scaling laws, proving the validity of the theory over seven orders of magnitude in length scales. Thus, a theoretical justification is provided, which had remained elusive so far, for the remarkable similarity between the textures of surfaces found for systems that differ widely in physical nature and typical scales. Sun, 30 Sep 2012 22:00:00 GMT http://hdl.handle.net/10016/16052 2012-09-30T22:00:00Z http://hdl.handle.net/10016/15338 Title: Evolutionary game theory: Temporal and spatial effects beyond replicator dynamics Author(s): Roca, Carlos P.; Cuesta, José A.; Sánchez, Angel Abstract: Evolutionary game dynamics is one of the most fruitful frameworks for studying evolution in different disciplines, from Biology to Economics. Within this context, the approach of choice for many researchers is the so-called replicator equation, that describes mathematically the idea that those individuals performing better have more offspring and thus their frequency in the population grows. While very many interesting results have been obtained with this equation in the three decades elapsed since it was first proposed, it is important to realize the limits of its applicability. One particularly relevant issue in this respect is that of non-meanfield effects, that may arise from temporal fluctuations or from spatial correlations, both neglected in the replicator equation. This review discusses these temporal and spatial effects focusing on the non-trivial modifications they induce when compared to the outcome of replicator dynamics. Alongside this question, the hypothesis of linearity and its relation to the choice of the rule for strategy update is also analyzed. The discussion is presented in terms of the emergence of cooperation, as one of the current key problems in Biology and in other disciplines. Mon, 30 Nov 2009 23:00:00 GMT http://hdl.handle.net/10016/15338 2009-11-30T23:00:00Z http://hdl.handle.net/10016/15330 Title: Nonlinear wave propagation in disordered media Author(s): Sánchez, Angel Abstract: We briefly review the state-of-the-art of research on nonlinear wave propagation in disordered media. The paper is intended to provide the non-specialist reader with a flavor of this active field of physics. Firstly, a general introduction to the subject is made. We describe the basic models and the ways to study disorder in connection with them. Secondly, analytical and numerical techniques suitable for this purpose are outlined. We summarize their features and comment on their respective advantages, drawbacks and applicability conditions. Thirdly, the Nonlinear Klein-Gordon and Schrbdinger equations are chosen as specific examples. We collect a number of results that are representative of the phenomena arising from the competition between nonlinearity and disorder. The review is concluded with some remarks on open questions, main current trends and possible further developments. Sat, 09 Nov 1991 23:00:00 GMT http://hdl.handle.net/10016/15330 1991-11-09T23:00:00Z