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Université de Fribourg

Scaling behaviour and memory in heart rate of healthy human

Cai, Shi-Min ; Peng, Hu ; Yang, Hui-Jie ; Zhou, Tao ; Zhou, Pei-Ling ; Wang, Bing-Hong

In: Chinese Physics Letters, 2007, vol. 24, no. 10, p. 3002

We investigate a set of complex heart rate time series from healthy human in different behaviour states with the detrended fluctuation analysis and diffusion entropy (DE) method. It is proposed that the scaling properties are influenced by behaviour states. The memory detected by DE exhibits an approximately same pattern after a detrending procedure. Both of them demonstrate the long-range strong...

Université de Fribourg

Scale invariance of human electroencephalogram signals in sleep

Cai, Shi-Min ; Jiang, Zhao-Hui ; Zhou, Tao ; Zhou, Pei-Ling ; Yang, Hui-Jie ; Wang, Bing-Hong

In: Physical Review E, 2007, vol. 76, p. 061903

In this paper, we investigate the dynamical properties of electroencephalogram (EEG) signals of humans in sleep. By using a modified random walk method, we demonstrate that scale-invariance is embedded in EEG signals after a detrending procedure is applied. Furthermore, we study the dynamical evolution of the probability density function (PDF) of the detrended EEG signals by nonextensive...

Université de Fribourg

Scaling and memory in recurrence intervals of Internet traffic

Cai, Shi-Min ; Fu, Zhong-Qian ; Zhou, Tao ; Gu, Jun ; Zhou, Pei-Ling

In: Europhysics Letters, 2009, vol. 87, p. 68001

By studying the statistics of recurrence intervals, τ, between volatilities of Internet traffic rate changes exceeding a certain threshold q, we find that the probability distribution functions, Pq(τ), for both byte and packet flows, show scaling property as $P_{q}(\tau)=\frac{1}{\overline{\tau}}f(\frac{\tau}{\overline{\tau}})$. The scaling functions for both byte and packet flows obey the...

Université de Fribourg

Identifying influential nodes in large-scale directed networks: the role of clustering

Chen, Duan Bing ; Gao, Hui ; Lü, Linyuan ; Zhou, Tao

In: PLoS ONE, 2013, vol. 8, no. 10, p. e77455

Identifying influential nodes in very large-scale directed networks is a big challenge relevant to disparate applications, such as accelerating information propagation, controlling rumors and diseases, designing search engines, and understanding hierarchical organization of social and biological networks. Known methods range from node centralities, such as degree, closeness and betweenness, to...

Université de Fribourg

Heterogeneity, quality, and reputation in an adaptive recommendation model

Cimini, Giulio ; Medo, Matúš ; Zhou, Tao ; Wei, Dong ; Zhang, Yi-Cheng

In: The European Physical Journal B - Condensed Matter and Complex Systems, 2011, vol. 80, no. 2, p. 201-208

Recommender systems help people cope with the problem of information overload. A recently proposed adaptive news recommender model [M. Medo, Y.-C. Zhang, T. Zhou, Europhys. Lett. 88, 38005 (2009)] is based on epidemic-like spreading of news in a social network. By means of agent-based simulations we study a “good get richer” feature of the model and determine which attributes are necessary...

Université de Fribourg

Enhancing topology adaptation in information-sharing social networks

Cimini, Giulio ; Chen, Duanbing ; Medo, Matúš ; Lü, Linyuan ; Zhang, Yi-Cheng ; Zhou, Tao

In: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 2012, vol. 85, no. 4, p. 046108

The advent of the Internet and World Wide Web has led to unprecedent growth of the information available. People usually face the information overload by following a limited number of sources which best fit their interests. It has thus become important to address issues like who gets followed and how to allow people to discover new and better information sources. In this paper we conduct an...

Université de Fribourg

How altruism works: An evolutionary model of supply networks

Ge, Zehui ; Zhang, Zi-Ke ; Lü, Linyuan ; Zhou, Tao ; Xi, Ning

In: Physica A: Statistical Mechanics and its Applications, 2012, vol. 391, no. 3, p. 647–655

Recently, supply networks have attracted increasing attention from the scientific community. However, it lacks serious consideration of social preference in Supply Chain Management. In this paper, we develop an evolutionary decision-making model to characterize the effects of suppliers’ altruism in supply networks, and find that the performances of both suppliers and supply chains are improved...

Université de Fribourg

Onset of cooperation between layered networks

Gu, Chang-Gui ; Zou, Sheng-Rong ; Xu, Xiu-Lian ; Qu, Yan-Qing ; Jiang, Yu-Mei ; He, Da Ren ; Liu, Hong-Kun ; Zhou, Tao

In: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 2011, vol. 84, no. 2, p. 026101

Functionalities of a variety of complex systems involve cooperations among multiple components; for example, a transportation system provides convenient transfers among airlines, railways, roads, and shipping lines. A layered model with interacting networks can facilitate the description and analysis of such systems. In this paper we propose a model of traffic dynamics and reveal a transition at...

Université de Fribourg

Opinion spreading with mobility on scale-free networks

Guo, Qiang ; Liu, Jian-Guo ; Wang, Bing-Hong ; Zhou, Tao ; Chen, Xing-Wen ; Yao, Yu-Hua

In: Chinese Physics Letters, 2008, vol. 25, no. 2, p. 773-775

A continuum opinion dynamic model is presented based on two rules. The first one considers the mobilities of the individuals, the second one supposes that the individuals update their opinions independently. The results of the model indicate that the bounded confidence ∈c, separating consensus and incoherent states, of a scale-free network is much smaller than the one of a...

Université de Fribourg

Modeling human dynamics with adaptive interest

Han, Xiao-Pu ; Zhou, Tao ; Wang, Bing-Hong

In: New Journal of Physics, 2008, vol. 10, p. 073010

Increasing recent empirical evidence indicates the extensive existence of heavy tails in the inter-event time distributions of various human behaviors. Based on the queuing theory, the Barabási model and its variations suggest the highest-priority-first protocol to be a potential origin of those heavy tails. However, some human activity patterns, also displaying heavy-tailed temporal statistics,...