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Complex systems in the spotlight: next steps after the 2021 Nobel Prize in Physics
Ginestra Bianconi, Alex Arenas, Jacob D. Biamonte, Lincoln D Carr, Byungnam Kahng, János Kertész, Jürgen Kurths, Linyuan Lü, Cristina Masoller, Adilson E Motter, Matjaž Perc, 2023, predgovor, uvodnik, spremna beseda

Opis: The 2021 Nobel Prize in Physics recognized the fundamental role of complex systems in the natural sciences. In order to celebrate this milestone, this editorial presents the point of view of the editorial board of JPhys Complexity on the achievements, challenges, and future prospects of the field. To distinguish the voice and the opinion of each editor, this editorial consists of a series of editor perspectives and reflections on few selected themes. A comprehensive and multi-faceted view of the field of complexity science emerges. We hope and trust that this open discussion will be of inspiration for future research on complex systems.
Ključne besede: Nobel prize, complex systems, physics
Objavljeno v DKUM: 30.05.2024; Ogledov: 60; Prenosov: 4
.pdf Celotno besedilo (4,36 MB)
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Science, human awareness and environmental attitudes
Boris Aberšek, 2022, drugi znanstveni članki

Opis: The environment is a system, a complex system, which we are unable to comprehend, let alone truly understand, with the help of simplified models that we, humans, are able to process. Our human understanding of the complexity of a grain of sand simply isn’t enough to construe and adapt the universe! This would require time and knowledge, which we do not have today, and which we will not have for a long time. So, everything is in interpretation. Let us start our stories with some basic truths. The main premise is, that man doesn't need an outside enemy, he's the greatest threat to himself. But he's not just a threat to himself, he's a threat also to everything around him. No living thing on earth destroys it more than it takes for its existence, except for human.
Ključne besede: complex systems, human awareness, environmental attitudes, energy production
Objavljeno v DKUM: 08.08.2023; Ogledov: 373; Prenosov: 28
.pdf Celotno besedilo (123,83 KB)
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Second-order free-riding on antisocial punishment restores the effectiveness of prosocial punishment
Attila Szolnoki, Matjaž Perc, 2017, izvirni znanstveni članek

Opis: Economic experiments have shown that punishment can increase public goods game contributions over time. However, the effectiveness of punishment is challenged by second-order free-riding and antisocial punishment. The latter implies that noncooperators punish cooperators, while the former implies unwillingness to shoulder the cost of punishment. Here, we extend the theory of cooperation in the spatial public goods game by considering four competing strategies, which are traditional cooperators and defectors, as well as cooperators who punish defectors and defectors who punish cooperators. We show that if the synergistic effects are high enough to sustain cooperation based on network reciprocity alone, antisocial punishment does not deter public cooperation. Conversely, if synergistic effects are low and punishment is actively needed to sustain cooperation, antisocial punishment does is viable, but only if the cost-to-fine ratio is low. If the costs are relatively high, cooperation again dominates as a result of spatial pattern formation. Counterintuitively, defectors who do not punish cooperators, and are thus effectively second-order free-riding on antisocial punishment, form an active layer around punishing cooperators, which protects them against defectors that punish cooperators. A stable three-strategy phase that is sustained by the spontaneous emergence of cyclic dominance is also possible via the same route. The microscopic mechanism behind the reported evolutionary outcomes can be explained by the comparison of invasion rates that determine the stability of subsystem solutions. Our results reveal an unlikely evolutionary escape from adverse effects of antisocial punishment, and they provide a rationale for why second-order free-riding is not always an impediment to the evolutionary stability of punishment.
Ključne besede: complex systems, interdisciplinary physics, punishment, cooperation
Objavljeno v DKUM: 13.11.2017; Ogledov: 1025; Prenosov: 433
.pdf Celotno besedilo (1,15 MB)
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Inheritance patterns in citation networks reveal scientific memes
Tobias Kuhn, Matjaž Perc, Dirk Helbing, 2014, izvirni znanstveni članek

Opis: Memes are the cultural equivalent of genes that spread across human culture by means of imitation. What makes a meme and what distinguishes it from other forms of information, however, is still poorly understood. Our analysis of memes in the scientific literature reveals that they are governed by a surprisingly simple relationship between frequency of occurrence and the degree to which they propagate along the citation graph. We propose a simple formalization of this pattern and validate it with data from close to 50 million publication records from the Web of Science, PubMed Central, and the American Physical Society. Evaluations relying on human annotators, citation network randomizations, and comparisons with several alternative approaches confirm that our formula is accurate and effective, without a dependence on linguistic or ontological knowledge and without the application of arbitrary thresholds or filters.
Ključne besede: memes, inheritance, genes, network science, complex systems
Objavljeno v DKUM: 03.08.2017; Ogledov: 1488; Prenosov: 428
.pdf Celotno besedilo (2,85 MB)
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Quantifying soil complexity using network models of soil porous structure
Marko Samec, A. Santiago, J. P. Cardenas, R. M. Benito, A. M. Tarquis, Sacha Jon Mooney, Dean Korošak, 2013, izvirni znanstveni članek

Opis: This paper describes an investigation into the properties of spatially embedded complex networks representing the porous architecture of soil systems. We suggest an approach to quantify the complexity of soil pore structure based on the node-node link correlation properties of the networks. We show that the complexity depends on the strength of spatial embedding of the network and that this is related to the transition from a non-compact to compact phase of the network.
Ključne besede: soil complexity, soil pore networks, complex systems
Objavljeno v DKUM: 21.07.2017; Ogledov: 1425; Prenosov: 328
.pdf Celotno besedilo (3,85 MB)
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Fluctuating excitability : a mechanism for self-sustained information flow in excitable arrays
Matjaž Perc, 2007, izvirni znanstveni članek

Opis: We show that the fluctuating excitability of FitzHugh-Nagumo neurons, constituting a diffusively coupled excitable array, can induce phase slips that lead to a symmetry break yielding a preferred spreading direction of excitatory events, thus enabling persistent self-sustained and self-organized information flow in a periodic array long after a localized stimulus perturbation has sized. Possible oscillation frequencies of the information-carrying signal are expressed analytically, and necessary conditions for the phenomenon are derived. Our results suggest that cellular diversity in neural tissue is crucial for maintaining self-sustained and organized activity in the brain even in the absence of immediate stimuli, thus facilitating continuous evolution of its mechanisms for information retrieval and storage.
Ključne besede: physics, complex systems, dynamical systems, flexibility, chaos, chaotic systems, oscillations, perturbation
Objavljeno v DKUM: 07.06.2012; Ogledov: 2230; Prenosov: 96
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Spatial coherence resonance in neuronal media with discrete local dynamics
Matjaž Perc, 2006, izvirni znanstveni članek

Opis: We study effects of spatiotemporal additive noise on the spatial dynamics of excitable neuronal media that is locally modelled by a two-dimensional map. We focus on the ability of noise to enhance a particular spatial frequency of the media in a resonant manner. We show that there exists an optimal noise intensity for which the inherent spatial periodicity of the media is resonantly pronounced, thus marking the existence of spatial coherence resonance in the studied system. Additionally, results are discussed in view of their possible biological importance.
Ključne besede: physics, complex systems, dynamical systems, noise, spatial dynamics, chaos, chaotic systems, chaos control, resonance
Objavljeno v DKUM: 07.06.2012; Ogledov: 2407; Prenosov: 105
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Effects of small-world connectivity on noise-induced temporal and spatial order in neural media
Matjaž Perc, 2006, izvirni znanstveni članek

Opis: We present an overview of possible effects of small-world connectivity on noise-induced temporal and spatial order in a two-dimensional network of excitable neural media with FitzHugh-Nagumo local dynamics. Small-world networks are characterized by a given fraction of so-called long-range couplings or shortcut links that connect distant units of the system, while all other units are coupled in a diffusive-like manner. Interestingly, already a small fraction of these long-range couplings can have wide-ranging effects on the temporal as well as spatial noise-induced dynamics of the system. Here we present two main effects. First, we show that the temporal order, characterized by the autocorrelation of a firing-rate function, can be greatly enhanced by the introduction of small-world connectivity, whereby the effect increases with the increasing fraction of introduced shortcut links. Second, we show that the introduction of long-range couplings induces disorderof otherwise ordered, spiral-wave-like, noise-induced patterns that can be observed by exclusive diffusive connectivity of spatial units. Thereby, already a small fraction of shortcut links is sufficient to destroy coherent pattern formation in the media. Although the two results seem contradictive, we provide an explanation considering the inherent scale-free nature of small-world networks, which on one hand, facilitates signal transduction and thus temporal order in the system, whilst on the other hand, disrupts the internal spatial scale of the media thereby hindering the existence of coherent wave-like patterns. Additionally, the importance of spatially versus temporally ordered neural network functioning is discussed.
Ključne besede: physics, complex systems, dynamical systems, noise, chaos, chaotic systems, chaos control, resonance
Objavljeno v DKUM: 07.06.2012; Ogledov: 1965; Prenosov: 85
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