226 citations · 678 across the 20 of their papers we have counts for
6 papers · 1 filter
Risk evaluation with enhaced covariance matrix
Krzysztof Urbanowicz, Peter Richmond, Janusz A. Holyst
We propose a route for the evaluation of risk based on a transformation of the covariance matrix. The approach uses a `potential' or `objective' function. This allows us to rescale…
Networks of companies and branches in Poland
Anna M. Chmiel, Julian Sienkiewicz, Krzysztof Suchecki +1
In this study we consider relations between companies in Poland taking into account common branches they belong to. It is clear that companies belonging to the same branch compete…
How random is your heart beat?
K. Urbanowicz, J. J. Zebrowski, R. Baranowski +1
We measure the content of random uncorrelated noise in heart rate variability using a general method of noise level estimation using a coarse grained entropy. We show that usually…
Log-periodic oscillations due to discrete effects in complex networks
Julian Sienkiewicz, Piotr Fronczak, Janusz A. Holyst
We show that discretization of internode distribution in complex networks affects internode distances l_ij calculated as a function of degrees (k_i k_j) and an average path length…
Ferromagnetic fluid as a model of social impact
Piotr Fronczak, Agata Fronczak, Janusz A. Hołyst
The paper proposes a new model of spin dynamics which can be treated as a model of sociological coupling between individuals. Our approach takes into account two different human fe…
Ising model on two connected Barabasi-Albert networks
Krzysztof Suchecki, Janusz A. Holyst
We investigate analytically the behavior of Ising model on two connected Barabasi-Albert networks. Depending on relative ordering of both networks there are two possible phases cor…