Grupo Interdisciplinar de Sistemas Complejos (GISC)http://hdl.handle.net/10016/58602014-04-20T21:00:18Z2014-04-20T21:00:18ZPattern-wavelength coarsening from topological dynamics in silicon nanofoamsCastro, MCuerno, RodolfoGarcía-Hernández, M. M.Vazquez Burgos, Luishttp://hdl.handle.net/10016/186052014-04-08T11:26:17Z2014-03-07T00:00:00ZPattern-wavelength coarsening from topological dynamics in silicon nanofoams
Castro, M; Cuerno, Rodolfo; García-Hernández, M. M.; Vazquez Burgos, Luis
We report the experimental observation of a submicron cellular structure on the surface of silicon targets eroded by an ion plasma. Analysis by atomic force microscopy allows us to assess the time evolution and show that the system can be described quantitatively by the convective Cahn-Hilliard equation, found in the study of domain coarsening for a large class of driven systems. The space-filling trait of the ensuing pattern relates it to evolving foams. Through this connection, we are actually able to derive the coarsening law for the pattern wavelength from the nontrivial topological dynamics of the cellular structure. Thus, the study of the topological properties of patterns in nonvariational spatially extended systems emerges as complementary to morphological approaches to their challenging coarsening properties.
2014-03-07T00:00:00ZThe predictability of consumer visitation patternsKrumme, CocoLlorente, AlejandroCebrián, ManuelPentland, AlexMoro, Estebanhttp://hdl.handle.net/10016/169422013-10-01T00:01:57Z2013-04-18T00:00:00ZThe predictability of consumer visitation patterns
Krumme, Coco; Llorente, Alejandro; Cebrián, Manuel; Pentland, Alex; Moro, Esteban
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.
2013-04-18T00:00:00ZUniversality of cauliflower-like fronts: from nanoscale thin films to macroscopic plantsCastro, MarioCuerno, RodolfoNicoli, MatteoVázquez, LuisBuijnsters, Josephus G.http://hdl.handle.net/10016/160522014-04-08T11:26:17Z2012-10-01T00:00:00ZUniversality of cauliflower-like fronts: from nanoscale thin films to macroscopic plants
Castro, Mario; Cuerno, Rodolfo; Nicoli, Matteo; Vázquez, Luis; Buijnsters, Josephus G.
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.
2012-10-01T00:00:00ZEvolutionary game theory: Temporal and spatial effects beyond replicator dynamicsRoca, Carlos P.Cuesta, José A.Sánchez, Angelhttp://hdl.handle.net/10016/153382014-04-08T11:26:17Z2009-12-01T00:00:00ZEvolutionary game theory: Temporal and spatial effects beyond replicator dynamics
Roca, Carlos P.; Cuesta, José A.; Sánchez, Angel
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.
2009-12-01T00:00:00Z