Institute of Biophysics, Center for Physiological Medicine, Medical University of Graz, Harrachgasse 21/IV, 8010, Graz, Austria.
Institute of Bioengineering, Aachen University of Applied Sciences, Heinrich-Mußmann-Straße 1, 52428, Jülich, Germany.
Sci Rep. 2017 May 26;7(1):2464. doi: 10.1038/s41598-017-02665-5.
Physiological processes are regulated by nonlinear dynamical systems. Various nonlinear measures have frequently been used for characterizing the complexity of fractal time signals to detect system features that cannot be derived from linear analyses. We analysed human balance dynamics ranging from simple standing to balancing on one foot with closed eyes to study the inherent methodological problems when applying fractal dimension analysis to real-world signals. Higuchi dimension was used as an example. Choice of measurement and analysis parameters has a distinct influence on the computed dimension. Noise increases the fractional dimension which may be misinterpreted as a higher complexity of the signal. Publications without specifying the parameter setting, or without analysing the noise-sensitivity are not comparable to findings of others and therefore of limited scientific value.
生理过程受非线性动力系统调控。各种非线性方法常用于描述分形时间信号的复杂性，以检测线性分析无法得出的系统特征。我们分析了人体平衡动力学，范围从简单站立到闭眼单脚站立，以研究在实际信号中应用分形维数分析时所固有的方法学问题。以 Higuchi 维数为例，测量和分析参数的选择对计算出的维度有明显影响。噪声会增加分数维度，这可能被误解为信号的复杂性更高。没有指定参数设置的出版物，或没有分析噪声敏感性的出版物，与其他人的发现不可比，因此科学价值有限。
