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Université de Fribourg

Computational network biology: Data, models, and applications

Liu, Chuang ; Ma, Yifang ; Zhao, Jing ; Nussinov, Ruth ; Zhang, Yi-Cheng ; Cheng, Feixiong ; Zhang, Zi-Ke

In: Physics Reports, 2020, vol. 846, p. 1–66

Biological entities are involved in intricate and complex interactions, in which uncovering the biological information from the network concepts are of great significance. Benefiting from the advances of network science and high-throughput biomedical technologies, studying the biological systems from network biology has attracted much attention in recent years, and networks have long been...

Université de Fribourg

Predicting financial extremes based on weighted visual graph of major stock indices

Chen, Dong-Rui ; Liu, Chuang ; Zhang, Yi-Cheng ; Zhang, Zi-Ke

In: Complexity, 2019, vol. 2019, p. 1–17

Understanding and predicting extreme turning points in the financial market, such as financial bubbles and crashes, has attracted much attention in recent years. Experimental observations of the superexponential increase of prices before crashes indicate the predictability of financial extremes. In this study, we aim to forecast extreme events in the stock market using 19-year time-series...

Consortium of Swiss Academic Libraries

Tag-Aware Recommender Systems: A State-of-the-Art Survey

Zhang, Zi-Ke ; Zhou, Tao ; Zhang, Yi-Cheng

In: Journal of Computer Science and Technology, 2011, vol. 26, no. 5, p. 767-777

Consortium of Swiss Academic Libraries

Empirical analysis on a keyword-based semantic system

Zhang, Zi-Ke ; Lü, Linyuan ; Liu, Jian-Guo ; Zhou, Tao

In: The European Physical Journal B, 2008, vol. 66, no. 4, p. 557-561

Université de Fribourg

Cultural evolution: the case of babies’ first names

Xi, Ning ; Zhang, Zi-Ke ; Zhang, Yi-Cheng ; Ge, Zehui ; She, Li ; Zhang, Kui

In: Physica A: Statistical Mechanics and its Applications, 2014, vol. 406, p. 139–144

In social sciences, there is currently rare consensus on the underlying mechanism for cultural evolution, partially due to lack of suitable data. The evolution of first names of newborn babies offers a remarkable example for such researches. In this paper, we employ the historical data on baby names from the United States to investigate the evolutionary process of culture, in particular focusing...

Université de Fribourg

Website-oriented recommendation based on heat spreading and tag-aware collaborative filtering

Zhang, Zi-Ke ; Yu, Lu ; Fang, Kuan ; You, Zhi-Qiang ; Liu, Chuang ; Liu, Hao ; Yan, Xiao-Yong

In: Physica A: Statistical Mechanics and its Applications, 2014, vol. 399, p. 82–88

Recently, Recommender Systems has been widely applied in helping users find potentially interesting items from the era of big data. However, most of researches on this topic have focused on estimating the direct relationships between users and items, neglecting other available information. In this paper, we discuss about mining webs with information extracted from search and browser logs of...

Université de Fribourg

Positive periodic solutions of an epidemic model with seasonality

Sun, Gui-Quan ; Bai, Zhenguo ; Zhang, Zi-Ke ; Zhou, Tao ; Jin, Zhen

In: The Scientific World Journal, 2013, vol. 2013, p. -

An SEI autonomous model with logistic growth rate and its corresponding nonautonomous model are investigated. For the autonomous case, we give the attractive regions of equilibria and perform some numerical simulations. Basic demographic reproduction Rd number is obtained. Moreover, only the basic reproduction number R0 cannot ensure the existence of the positive equilibrium, which needs...

Université de Fribourg

An evolving model of online bipartite networks

Zhang, Chu-Xu ; Zhang, Zi-Ke ; Liu, Chuang

In: Physica A: Statistical Mechanics and its Applications, 2013, vol. 392, no. 23, p. 6100–6106

Understanding the structure and evolution of online bipartite networks is a significant task since they play a crucial role in various e-commerce services nowadays. Recently, various attempts have been tried to propose different models, resulting in either power-law or exponential degree distributions. However, many empirical results show that the user degree distribution actually follows a...

Université de Fribourg

Spatial dynamics of a vegetation model in an arid flat environment

Sun, Gui-Quan ; Li, Li ; Zhang, Zi-Ke

In: Nonlinear Dynamics, 2013, vol. 73, no. 4, p. 2207–2219

Self-organized vegetation patterns in space were found in arid and semi-arid areas. In this paper, we modelled a vegetation model in an arid flat environment using reaction-diffusion form and investigated the pattern formation. By using Hopf and Turing bifurcation theory, we obtain Turing region in parameters space. It is found that there are different types of stationary patterns including...

Université de Fribourg

Deviation of Zipf’s and Heaps’ laws in human languages with limited dictionary sizes

Lü, Linyuan ; Zhang, Zi-Ke ; Zhou, Tao

In: Scientific Reports, 2013, vol. 3, p. -

Zipf's law on word frequency and Heaps' law on the growth of distinct words are observed in Indo-European language family, but it does not hold for languages like Chinese, Japanese and Korean. These languages consist of characters, and are of very limited dictionary sizes. Extensive experiments show that: (i) The character frequency distribution follows a power law with exponent close to one, at...