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Buenos Aires, Argentina

Caram L.F.,Laboratorio Of Redes Y Sistemas Moviles | Caiafa C.F.,CONICET | Ausloos M.,University of Leicester | Ausloos M.,Group for Research on Applications of Physics in economics and Sociology GRAPES | And 2 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics

A multiagent based model for a system of cooperative agents aiming at growth is proposed. This is based on a set of generalized Verhulst-Lotka-Volterra differential equations. In this study, strong cooperation is allowed among agents having similar sizes, and weak cooperation if agents have markedly different "sizes", thus establishing a peer-to-peer modulated interaction scheme. A rigorous analysis of the stable configurations is presented first examining the fixed points of the system, next determining their stability as a function of the model parameters. It is found that the agents are self-organizing into clusters. Furthermore, it is demonstrated that, depending on parameter values, multiple stable configurations can coexist. It occurs that only one of them always emerges with probability close to one, because its associated attractor dominates over the rest. This is shown through numerical integrations and simulations, after analytic developments. In contrast to the competitive case, agents are able to increase their capacity beyond the no-interaction case limit. In other words, when some collaborative partnership among a relatively small number of partners takes place, all agents act in good faith prioritizing the common good, when receiving a mutual benefit allowing them to surpass their capacity. © 2015 American Physical Society. ©2015 American Physical Society. Source

Olivares F.,National University of La Plata | Plastino A.,National University of La Plata | Plastino A.,CONICET | Rosso O.A.,Federal University of Alagoas | And 2 more authors.
Physics Letters, Section A: General, Atomic and Solid State Physics

At issue here is the distinction between noise and chaos. They are different phenomena but sometimes produce results that resemble each other. From a numerical viewpoint, in particular, subtle differences that exist between them are often difficult to discern. We present here a conceptual scheme, based on Information Theory, that successfully distinguishes between these two regimes. The idea is to look for the location of the pertinent signal on a special plane, called the information-one, whose axes are entropic-like measures. Using these quantifiers (one local, the other global), the contrast between the two dynamical regimes becomes apparent. © 2012 Elsevier B.V. Source

Olaiz N.,Laboratorio Of Sistemas Complejos | Maglietti F.,Laboratorio Of Sistemas Complejos | Suarez C.,Laboratorio Of Sistemas Complejos | Molina F.V.,University of Buenos Aires | And 3 more authors.
Electrochimica Acta

We have recently shown that in the classical electrochemical treatment (EChT) of tumors, i.e., the passage of a direct electric current through two electrodes inserted locally in the tumor tissue, from an initial uniform condition two pH fronts evolve, expanding towards each other, inducing extreme pH changes and tumor destruction, mainly by necrosis. Here we extend these results introducing a oneprobe two-electrode device (OPTED) containing the cathode and the anode very close to each other (1 mm). Experiments show that upon application of the OPTED-EChT, two half-spherical pH fronts, one basic and the other acid (from cathode and anode, respectively), expand towards the periphery configuring a distorted full sphere. Tracking of the pH front advance reveals a time scaling close to t1/2, signature of a diffusion-controlled process. An analytic model presented allows the estimation of the time needed for total tumor destruction with a minimum compromise of healthy tissue. Main advantages of the OPTED are the insertion of one applicator rather than two or more (thus minimizing tissue intrusion, for instance, in the nervous system), the ability to reach tumors beyond capabilities of conventional surgery and the minimization of electric current circulation through the treated organ. We propose here this new design which could have significant implications in EChT optimal operative conditions, in particular, in the way in which the evolving pH spherical fronts can cover and destroy a cancer cell spherical casket. © 2010 Elsevier Ltd. All rights reserved. Source

Olaiz N.,Laboratorio Of Sistemas Complejos | Suarez C.,Laboratorio Of Sistemas Complejos | Risk M.,Laboratorio Of Sistemas Complejos | Molina F.,University of Buenos Aires | Marshall G.,University of Manchester
Electrochemistry Communications

Electrochemical reactions in the electrochemical treatment of tumors (EChT) induce extreme pH changes and, consequently, protein electrodenaturation fronts intimately related to tumor destruction. Here we introduce a new in vitro EChT collagen-macronutrient gel (CMG) model to study protein electrodenaturation fronts as a mean of assessing EChT effectiveness. Our CMG model shows that from an initial uniform condition two electrodenaturation fronts evolve expanding towards each other until collision. Moreover, electrodenaturation front tracking reveals that the front grows under a diffusion-controlled regime. Based on this evidence it is possible, in principle, to predict the time needed for tumor destruction without compromising healthy tissue. These results are consistent with those previously obtained with in vivo and in vitro EChT modeling. In contrast to previous simpler in vitro models, our CMG model represents a better structural and chemical approximation to a real tissue thus providing a better tool for validation of new in silico EChT models aimed at a more accurate prediction of tissue destruction level. © 2009 Elsevier B.V. All rights reserved. Source

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