1,720,978 research outputs found
On the emergence of Zipf ’s law in music
No full textZipf's law is found when the vocabulary of long written texts is ranked according to the frequency of word occurrences, establishing a power-law decay for the frequency vs rank relation. This law is a robust statistical property observed even in ancient untranslated languages. Interestingly, this law seems to be also manifested in music records when several metrics – functioning as words in written texts – are used. Even though music can be regarded as a language, finding an accurate equivalent of the concept of words in music is difficult because it lacks a functional semantic. This raises the question of which is the appropriate choice of Zipfian units in music, which is extensive to other contexts where this law can emerge. In particular, this is still an open question in written texts, where several alternatives have been proposed as Zipfian units besides the canonical use of words. Seeking to validate a natural election of Zipfian units in music, in this work we find that Zipf's law emerges when a combination of chords and notes are chosen as Zipfian units. Our results are grounded on a consistent analysis of the statistical properties of music and texts, complemented with theoretical considerations that combine different reference models, including a simple model inspired in the Lempel–Ziv compression algorithm that we have devised to explain the emergence of Zipf's law as the consequence of languages evolving into more efficient forms of communication.Fil: Perotti, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Billoni, Orlando Vito. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin
A disorder induced mechanism for positive exchange bias fields
No full textWe propose a mechanism to explain the phenomenon of positive exchange bias on magnetic bilayered systems. The mechanism is based on the formation of a domain wall at a disordered interface during field cooling, which induces a symmetry breaking of the antiferromagnet, without relying on any ad hoc assumption about the coupling between the ferromagnetic (FM) and antiferromagnetic (AFM) layers. The domain wall is a result of the disorder at the interface between FM and AFM, which reduces the effective anisotropy in the region. We show that the proposed mechanism explains several known experimental facts within a single theoretical framework. This result is supported by Monte Carlo simulations on a microscopic Heisenberg model, by micromagnetic calculations at zero temperature, and by mean-field analysis of an effective Ising-like phenomenological model.Fil: Billoni, Orlando Vito. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Física "Enrique Gaviola"; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Tamarit, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Física "Enrique Gaviola"; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Cannas, Sergio Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Física "Enrique Gaviola"; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin
Scaling of percolation transitions on Erdös-Rényi networks under centrality-based attacks
Full text linkThe study of network robustness focuses on the way the overall functionality of a network is affected as some of its constituent parts fail. Failures can occur at random or be part of an intentional attack and, in general, networks behave differently against different removal strategies. Although much effort has been put on this topic, there is no unified framework to study the problem. While random failures have been mostly studied under percolation theory, targeted attacks have been recently restated in terms of network dismantling. In this work, we link these two approaches by performing a finite-size scaling analysis to four dismantling strategies over Erdös-Rényi networks: initial and recalculated high degree removal and initial and recalculated high betweenness removal. We find that the critical exponents associated with the initial attacks are consistent with the ones corresponding to random percolation. For recalculated high degree, the exponents seem to deviate from mean field, but the evidence is not conclusive. Finally, recalculated betweenness produces a very abrupt transition with a hump in the cluster size distribution near the critical point, resembling some explosive percolation processes.Fil: Almeira, Nahuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Billoni, Orlando Vito. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Perotti, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin
Stochastic model for football's collective dynamics
No full textIn this paper, we study collective interaction dynamics emerging in the game of football (soccer). To do so, we surveyed a database containing body-sensor traces measured during three professional football matches, where we observed statistical patterns that we used to propose a stochastic model for the players' motion in the field. The model, which is based on linear interactions, captures to a good approximation the spatiotemporal dynamics of a football team. Our theoretical framework, therefore, can be an effective analytical tool to uncover the underlying cooperative mechanisms behind the complexity of football plays. Moreover, we showed that it can provide handy theoretical support for coaches to evaluate teams' and players' performances in both training sessions and competitive scenarios.Fil: Chacoma, Andrés Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Almeira, Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Perotti, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Billoni, Orlando Vito. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin
Modeling ball possession dynamics in the game of football
Full text linkIn this paper, we study interaction dynamics in the game of football-soccer in the context of ball possession intervals. To do so, we analyze a database comprising one season of the five major football leagues of Europe. Using this input, we developed a stochastic model based on three agents: two teammates and one defender. Despite its simplicity, the model is able to capture, in good approximation, the statistical behavior of possession times, pass lengths, and number of passes performed. In the last section, we show that the model's dynamics can be mapped into a Wiener process with drift and an absorbing barrier.Fil: Chacoma, Andrés Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Almeira, Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Perotti, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Billoni, Orlando Vito. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin
Model for phonetic changes driven by social interactions
Full text linkWe propose a stochastic model to study phonetic changes as an evolutionary process driven by social interactions between two groups of individuals with different phonological systems. Particularly, we focus on the changes in the place of articulation, inspired by the drift/φ/→/h/observed in some words of Latin root in the Castilian language. In the model, each agent is characterized by a variable of three states, representing the place of articulation used during speech production. In this frame, we propose stochastic rules of interactions among agents which lead to phonetic imitation and consequently to changes in the articulation place. Based on this, we mathematically formalize the model as a problem of population dynamics, derive the equations of evolution in the mean-field approximation, and study the emergence of three nontrivial global states, which can be linked to the pattern of phonetic changes observed in the language of Castile and in other Romance languages.Fil: Chacoma, Andrés Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Almeira, Nahuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Perotti, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Billoni, Orlando Vito. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin
Universal and nonuniversal neural dynamics on small world connectomes: A finite-size scaling analysis
Full text linkEvidence of critical dynamics has been found recently in both experiments and models of large-scale brain dynamics. The understanding of the nature and features of such a critical regime is hampered by the relatively small size of the available connectome, which prevents, among other things, the determination of its associated universality class. To circumvent that, here we study a neural model defined on a class of small-world networks that share some topological features with the human connectome. We find that varying the topological parameters can give rise to a scale-invariant behavior either belonging to the mean-field percolation universality class or having nonuniversal critical exponents. In addition, we find certain regions of the topological parameter space where the system presents a discontinuous, i.e., noncritical, dynamical phase transition into a percolated state. Overall, these results shed light on the interplay of dynamical and topological roots of the complex brain dynamics.Fil: Zarepour Nasir Abadi, Mahdi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Perotti, Juan Ignacio. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Billoni, Orlando Vito. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Chialvo, Dante Renato. Universidad Nacional de San Martín; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cannas, Sergio Alejandro. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin
Procesos de memoria en sistemas con distribuciones de Zipf-Pareto
Full text linkTesis (Doctor en Física)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2018.Estudios recientes realizados en una base de datos de Ajedrez cronológicamente ordenada, han mostrado que la distribución de popularidades de líneas de juego de Ajedrez se ajusta a una ley de Zipf. La ley de Zipf es común a muchos sistemas y es usualmente observada en conjunto con efectos de memoria tales como correlaciones de largo alcance y burstiness.
Sin embargo los modelos existentes que estudian estos fenómenos no dan cuenta simultáneamente con la ley de Zipf y los efectos de memoria. En este trabajo de tesis, mediante una variante del modelo de crecimiento preferencial de Yule-Simon, introducido por Cattuto et al., se provee una explicación de la aparición simultanea de la ley de Zipf y los efectos de memoria en forma de correlaciones de largo alcance en la base de datos de
Ajedrez. Se encuentra que el modelo de Cattuto et al. es capaz de reproducir ambos fenómenos, la ley de Zipf y las correlaciones de largo alcance, incluyendo además los efectos de tamaño del exponente de Hurst de las correspondientes series temporales. Más aún, se encuentra burstiness en la actividad de los grupos de jugadores más activos, aunque la actividad agregada del conjunto completo de jugadores presenta una distribución de tiempos entre eventos sin burstiness. Dado que el modelo de Cattuto et al. no es capaz de producir series temporales con comportamiento ’bursty ’, se realiza una modificación al núcleo de memoria que permite lograr una dinámica bursty. Introduciendo un núcleo de memoria finito, se mantiene el comportamiento de ley de potencia en la distribución de popularidades y, al mismo tiempo se obtienen series temporales que presentan burstiness como consecuencia de una transición de fase, en la cual, en el estado crítico, la
dinámica está dominada por las fluctuaciones.Recent works studying a chronologically sorted chess database have shown that the popularity distribution of opening lines in the game of chess follow a Zipf law. Zipf law is common to many systems and is usually observed together with memory effects, such as long-range correlations and burstiness. Nevertheless, existing models that study these phenomena do not account for the Zipf’s law and memory effects simultaneously. In this thesis, using a variant of the Yule-Simon preferential growth model, introduced by Cattuto et al., we provide an explanation of the simultaneous emergence of Zipf’s law and memory effects in the form of long-range correlations in the chess database. We find that Cattuto’s model is able to reproduce both phenomena, Zipf’s law and the long-range correlations., including the size effects displayed by the Hurst exponent of the corresponding time series. Furthermore, we find burstiness in the activity of the most active players, although the aggregated activity of all players in the database presents an interevent time distribution without burstiness. Since Cattuto’s model is not able to generate times series with a bursty behavior, we made a modification to the memory kernel that allows a bursty dynamics. By introducing a finite memory kernel, we keep the power-law behavior in the popularity distribution and, at the same time, we obtain time series that present burstiness as a consequence of a phase transition in which, at the critical point, the dynamic is ruled by fluctuations
Comunidades y robustez en redes complejas reales y sintéticas
Full text linkTesis (Doctor en Física)--Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación, 2022.Fil: Almeira, Nahuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.El estudio de las redes complejas, sistemas cuya estructura está regida por una compleja red de interacciones, es un área activa de investigación multidisciplinaria. Este campo ha recibido un gran impulso en los últimos años debido a la disponibilidad de una cantidad masiva de datos y a la existencia de recursos computacionales que permiten llevar a cabo los análisis estadísticos requeridos. Redes complejas extensas pueden encontrarse en una gran cantidad de sistemas naturales y artificiales, tales como sistemas físicos, biológicos, sociales, infraestructuras tecnológicas, etc. El aporte de la física a esta temática viene de la mano de la mecánica estadística, cuyas herramientas han facilitado el estudio de la estructura, la dinámica y la evolución de las redes complejas, brindando un marco teórico adecuado para el estudio cualitativo y cuantitativo de estos sistemas. La caracterización estadística de la estructura de las redes complejas se aborda desde diversos enfoques. Entre ellos hay dos que se destacan por la información que aportan y por las implicancias prácticas que ofrecen. Por una parte, la caracterización de estructuras modulares o comunidades es importante para entender la funcionalidad de las redes. Por otra parte, el estudio de la resiliencia de las redes ante fallas o ataques dirigidos es de gran utilidad para comprender cómo pueden generarse redes con un funcionamiento robusto. Curiosamente, estos dos conceptos –la existencia de comunidades y robustez de las redes– están íntimamente relacionados, y su estudio presenta grandes desafíos, dada la complejidad de los cálculos y análisis necesarios para su abordaje. En esta tesis estudiamos la existencia de comunidades en redes de jugadores de ajedrez utilizando la base de datos de partidas más extensa disponible, en su momento, en el mundo. Realizamos una caracterización general de las mismas y observamos una fuerte correlación entre las comunidades y el nivel de juego de los jugadores. En lo que respecta a las fallas y/o ataques analizamos redes sintéticas, tales como grafos de Erdös-Rényi y redes planares de Delaunay. Caracterizamos la robustez de las mismas mediante el estudio de transiciones de percolación, utilizando las herramientas de análisis de los fenómenos críticos y extensas simulaciones numéricas. Observamos que las transiciones varían de manera cualitativa de acuerdo con el tipo de red y con la estrategia de ataque empleada. En particular, observamos que algunos ataques generan transiciones similares a las encontradas en procesos de percolación explosiva.The study of complex networks, systems whose structure is governed by a complex interaction network, is an active multidisciplinary field of research in which physics has had a prevailing role. This field has received great impulse during the last years because of the availability of a massive amount of data and the existence of computational resources that allow to perform the required statistical analysis. Extensive complex networks can be found in a large variety of natural and artificial systems, such as physical, biological, and social systems, technological infrastructures, etc. Given the importance of these systems, investigations exploring the structure, dynamics and evolution of complex networks has raised the interest of the physics community, as tools coming from statistical mechanics, as well as from other fields of physics, are fundamental and have a direct application in the analysis and comprehension of such systems. The statistical characterization of the structure of complex networks is addressed from different approaches. Among them there are two that stand because of the information they give and because of the practical applications they allow. On one side, the characterization of modular structures or communities is important to understand the functionality of networks. On the other side, the study of the resiliency of networks against failures or targeted attacks gives relevant information on how to develop robust networks. Interestingly, these two concepts --the existence of communities and the robustness of networks-- are closely related, and their study presents big challenges, given the complexity of the calculations and analysis required to address them. In this thesis we studied the existence of communities in networks of chess players using the largest available database, at the moment, on the world. We performed a general characterization of the networks, observing a strong correlation between communities and player skill level. In terms of failures and targeted attacks, we studied synthetic random networks, such as Erdös-Rényi graphs and Delaunay triangulations. We characterized their robustness through the study of percolation transitions, using tools from critical phenomena and extensive numerical simulations. We observed that the transitions vary in a qualitative manner depending on the type of network and the attack strategy. In particular, we found that certain attacks generate transitions similar to those encountered in processes of explosive percolation.Fil: Almeira, Nahuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina
compounds using Monte Carlo simulations
No full textThe magnetization reversal (MR) of the layered Ni4−x Znx Nb2 O9 ferrimagnetic compounds,with x = 0, 0.25, 0.50 and 0.75, is studied in this work using Monte Carlo (MC) simulations andmean field (MF) calculations. First, we analyze the parent compound to set the parameters ofour simulations; testing together MC simulations, MF calculations, and MR experimentsreported by Bolletta et al (2022 J. Appl. Phys. 132 153901). Then using two differentapproaches we fit the MR curves of the series of compounds finding a quite good agreementbetween MC simulations and the experiments. According to these results, Zn substitutionschange the relative contribution to the magnetization of the different layers. Here we presenttwo possible hypotheses to explain this effect; one involving a heterogeneous distribution ofZn2+ among the layers, and the other related to distortions of the NiO6 octahedra.Fil: Rufeil Fiori, Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Bolleta, Juan P.. Universite de Caen Basse Normandie; FranciaFil: Martin, Christine. Universite de Caen Basse Normandie; FranciaFil: Maignan, Antoine. Universite de Caen Basse Normandie; FranciaFil: Billoni, Orlando Vito. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentin
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