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1.
Collective dynamics of swarmalators with higher-order interactions
Md Sayeed Anwar, Gourab Kumar Sar, Matjaž Perc, Dibakar Ghosh, 2024, izvirni znanstveni članek

Opis: Higher-order interactions shape collective dynamics, but how they affect transitions between different states in swarmalator systems is yet to be determined. To that effect, we here study an analytically tractable swarmalator model that incorporates both pairwise and higher-order interactions, resulting in four distinct collective states: async, phase wave, mixed, and sync states. We show that even a minute fraction of higher-order interactions induces abrupt transitions from the async state to the phase wave and the sync state. We also show that higher-order interactions facilitate an abrupt transition from the phase wave to the sync state bypassing the intermediate mixed state. Moreover, elevated levels of higher-order interactions can sustain the presence of phase wave and sync state, even when pairwise interactions lean towards repulsion. The insights gained from these findings unveil self-organizing processes that hold the potential to explain sudden transitions between various collective states in numerous real-world systems.
Ključne besede: collective dynamics, nonlinear oscillator, higher-order interactions, complex network, statistical physics
Objavljeno v DKUM: 07.05.2025; Ogledov: 0; Prenosov: 0
.pdf Celotno besedilo (2,75 MB)
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2.
Discrete memristive Hindmarsh-Rose neural model with fractional-order differences
Fatemeh Parastesh, Karthikeyan Rajagopal, Sajad Jafari, Matjaž Perc, 2025, izvirni znanstveni članek

Opis: Discrete systems can offer advantages over continuous ones in certain contexts, particularly in terms of simplicity and reduced computational costs, though this may vary depending on the specific application and requirements. Recently, there has been growing interest in using fractional differences to enhance discrete models' flexibility and incorporate memory effects. This paper examines the dynamics of the discrete memristive Hindmarsh-Rose model by integrating fractional-order differences. Our results highlight the complex dynamics of the fractional-order model, revealing that chaotic firing depends on both the fractional-order and magnetic strength. Notably, certain magnetic strengths induce a transition from periodic firing in the integer-order model to chaotic behavior in the fractional-order model. Additionally, we explore the dynamics of two coupled discrete systems, finding that electrical coupling leads to the synchronization of chaotic dynamics, while chemical coupling ultimately results in a quiescent state.
Ključne besede: memristive Hindmarsh-Rose model, discrete systems, fractional-order differences
Objavljeno v DKUM: 06.05.2025; Ogledov: 0; Prenosov: 0
.pdf Celotno besedilo (7,00 MB)
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3.
Structural roles and gender disparities in corruption networks
Arthur A. B. Pessa, Alvaro F. Martins, Mônica V. Prates, Sebastián Gonçalves, Cristina Masoller, Matjaž Perc, Haroldo V. Ribeiro, 2025, izvirni znanstveni članek

Opis: Criminal activities are predominantly due to males, with females exhibiting a significantly lower involvement, especially in serious offenses. This pattern extends to organized crime, where females are often perceived as less tolerant to illegal practices. However, the roles of males and females within corruption networks are less understood. Here, we analyze data from political scandals in Brazil and Spain to shed light on gender differences in corruption networks. Our findings reveal that females constitute 10% and 20% of all agents in the Brazilian and Spanish corruption networks, respectively, with these proportions remaining stable over time and across different scandal sizes. Despite this disparity in representation, centrality measures are comparable between genders, except among highly central individuals, for which males are further overrepresented. Additionally, gender has no significant impact on network resilience, whether through random dismantling or targeted attacks on the largest component. Males are more likely to be involved in multiple scandals than females, and scandals predominantly involving females are rare, though these differences are explained by a null network model in which gender is randomly assigned while maintaining gender proportions. Our results further reveal that the underrepresentation of females partially explains gender homophily in network associations, although in the Spanish network, male-to-male connections exceed expectations derived from a null model.
Ključne besede: gender disparity, corruption network, political scandal, social physics, social physics
Objavljeno v DKUM: 25.04.2025; Ogledov: 0; Prenosov: 0
.pdf Celotno besedilo (3,50 MB)
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4.
5.
Two-by-two ordinal patterns in art paintings
Mateus M. Tarozo, Arthur A. B. Pessa, Luciano Zunino, Osvaldo A. Rosso, Matjaž Perc, Haroldo V. Ribeiro, 2025, izvirni znanstveni članek

Opis: Quantitative analysis of visual arts has recently expanded to encompass a more extensive array of artworks due to the availability of large-scale digitized art collections. Consistent with formal analyses by art historians, many of these studies highlight the significance of encoding spatial structures within artworks to enhance our understanding of visual arts. However, defining universally applicable, interpretable, and sufficiently simple units that capture the essence of paintings and their artistic styles remains challenging. Here, we examine ordering patterns in pixel intensities within two-by-two partitions of images from nearly 140,000 paintings created over the past 1,000 years. These patterns, categorized into 11 types based on arguments of continuity and symmetry, are both universally applicable and detailed enough to correlate with low-level visual features of paintings. We uncover a universal distribution of these patterns, with consistent prevalence within groups, yet modulated across groups by a nontrivial interplay between pattern smoothness and the likelihood of identical pixel intensities. This finding provides a standardized metric for comparing paintings and styles, further establishing a scale to measure deviations from the average prevalence. Our research also shows that these simple patterns carry valuable information for identifying painting styles, though styles generally exhibit considerable variability in the prevalence of ordinal patterns. Moreover, shifts in the prevalence of these patterns reveal a trend in which artworks increasingly diverge from the average incidence over time; however, this evolution is neither smooth nor uniform, with substantial variability in pattern prevalence, particularly after the 1930s.
Ključne besede: spatial patterns, complexity, esthetic measure, art history, social physics
Objavljeno v DKUM: 01.04.2025; Ogledov: 0; Prenosov: 3
.pdf Celotno besedilo (9,19 MB)
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6.
Processed food intake assortativity in the personal networks of older adults
Marian-Gabriel Hâncean, Jürgen Lerner, Matjaž Perc, José Luis Molina González, Marius Geanta, Iulian Oană, Bianca-Elena Mihǎilǎ, 2025, izvirni znanstveni članek

Opis: Existing research indicates that dietary habits spread through social networks, yet the impact on populations in Eastern Europe, particularly in rural areas, is less understood. We examine the influence of personal networks on the consumption of high-salt processed foods among individuals in rural Romania, with a specific focus on older adults. Using a personal network analysis, we analyze data from 83 participants of varying ages and their social contacts through multi-level regression models. The inclusion of participants across a wider age range allows us to capture the broader dynamics of social networks, reflecting the intergenerational nature of rural communities. Our findings reveal assortativity in dietary habits, indicating that individuals cluster with others who share similar food consumption patterns. Our results underscore the need for public health interventions that account for the influence of social networks on dietary behavior, as addressing high salt intake and its associated health risks may require considering the broader social context beyond older adults. The study contributes to understanding the social determinants of dietary behaviors and highlights the role of personal networks in shaping food choices in vulnerable populations.
Ključne besede: processed food, older adults, social networks, assortativity, Romania, Eastern Europe
Objavljeno v DKUM: 31.03.2025; Ogledov: 0; Prenosov: 3
.pdf Celotno besedilo (1,64 MB)
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Using interdisciplinary techniques for digital reconstruction of anti-Turkish fortification watchtower
Rok Kamnik, Saša Djura Jelenko, Matjaž P. Nekrep, Marko Jaušovec, 2022, izvirni znanstveni članek

Opis: Modern heritage protection goes beyond the mere protection of individual buildings and objects. Modern technologies and techniques of field data capture and visual (3D) presentations are increasingly penetrating this field and are becoming more and more essential and necessary for archives, cadastres, and users and visitors of museums, exhibitions, collections, and archaeological parks. In the area between Kotlje and Ravne na Koroškem, Slovenia, in 1476–1477, 9 to 10 anti-Turkish fortifications, called Turške Šance, reportedly were erected. The remains were left to decay slowly. This paper highlights the possibility of applying interdisciplinary data capture and 3D visualization techniques that are used in the fields of civil engineering and architecture for digital reconstruction of the anti-Turkish fortification as a case study in order to present them in the most contemporary way and emphasize them on a local, regional, national, and international level. Unfortunately, similar remains elsewhere in Europe are primarily ignored (with some notable exceptions). The digital reconstruction of anti-Turkish watchtowers therefore represented an extended reconstruction to revive that part of the historical heritage of Slovenia using the proposed techniques.
Ključne besede: anti-Turkish fortification, 3D visualization, watchtower, tschartake, moats, trench, mund, čardak, Çardak, digital archaeology
Objavljeno v DKUM: 12.03.2025; Ogledov: 0; Prenosov: 8
.pdf Celotno besedilo (5,66 MB)
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9.
Local and global stimuli in reinforcement learning
Danyang Jia, Hao Guo, Zhao Song, Lei Shi, Xinyang Deng, Matjaž Perc, Zhen Wang, 2021, izvirni znanstveni članek

Opis: In efforts to resolve social dilemmas, reinforcement learning is an alternative to imitation and exploration in evolutionary game theory. While imitation and exploration rely on the performance of neighbors, in reinforcement learning individuals alter their strategies based on their own performance in the past. For example, according to the Bush-Mosteller model of reinforcement learning, an individual's strategy choice is driven by whether the received payoff satisfies a preset aspiration or not. Stimuli also play a key role in reinforcement learning in that they can determine whether a strategy should be kept or not. Here we use the Monte Carlo method to study pattern formation and phase transitions towards cooperation in social dilemmas that are driven by reinforcement learning. We distinguish local and global players according to the source of the stimulus they experience. While global players receive their stimuli from the whole neighborhood, local players focus solely on individual performance. We show that global players play a decisive role in ensuring cooperation, while local players fail in this regard, although both types of players show properties of "moody cooperators". In particular, global players evoke stronger conditional cooperation in their neighborhoods based on direct reciprocity, which is rooted in the emerging spatial patterns and stronger interfaces around cooperative clusters.
Ključne besede: evolutionary game theory, cooperation, learning, social physics
Objavljeno v DKUM: 03.03.2025; Ogledov: 0; Prenosov: 1
.pdf Celotno besedilo (5,68 MB)
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10.
The self-organizing impact of averaged payoffs on the evolution of cooperation
Attila Szolnoki, Matjaž Perc, 2021, izvirni znanstveni članek

Opis: According to the fundamental principle of evolutionary game theory, the more successful strategy in a population should spread. Hence, during a strategy imitation process a player compares its payoff value to the payoff value held by a competing strategy. But this information is not always accurate. To avoid ambiguity a learner may therefore decide to collect a more reliable statistics by averaging the payoff values of its opponents in the neighborhood, and makes a decision afterwards. This simple alteration of the standard microscopic protocol significantly improves the cooperation level in a population. Furthermore, the positive impact can be strengthened by increasing the role of the environment and the size of the evaluation circle. The mechanism that explains this improvement is based on a self-organizing process which reveals the detrimental consequence of defector aggregation that remains partly hidden during face-to-face comparisons. Notably, the reported phenomenon is not limited to lattice populations but remains valid also for systems described by irregular interaction networks.
Ključne besede: evolutionary game theory, cooperation, learning, social physics
Objavljeno v DKUM: 03.03.2025; Ogledov: 0; Prenosov: 2
.pdf Celotno besedilo (2,21 MB)
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