tailieunhanh - báo cáo hóa học: " Fractional Langevin model of gait variability"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Fractional Langevin model of gait variability | Journal of NeuroEngineering and Rehabilitation BioMed Central Research Fractional Langevin model of gait variability Bruce J West 1 and Miroslaw Latka2 Open Access Address Mathematical and Informational Sciences Directorate US Army Research Office . Box 12211 Research Triangle Park NC 27709 USA and 2Physics Department Wroclaw University of Technology Wybrzeze Wyspianskiego 27 50-370 Wroclaw Poland Email Bruce J West - Miroslaw Latka - mlatka@ Corresponding author Published 02 August 2005 Received 12 April 2005 Journal of NeuroEngineering and Rehabilitation 2005 2 24 doi 186 1743-0003-2-24 Accepted 02 August 2005 This article is available from http content 2 1 24 2005 West and Latka licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract The stride interval in healthy human gait fluctuates from step to step in a random manner and scaling of the interstride interval time series motivated previous investigators to conclude that this time series is fractal. Early studies suggested that gait is a monofractal process but more recent work indicates the time series is weakly multifractal. Herein we present additional evidence for the weakly multifractal nature of gait. We use the stride interval time series obtained from ten healthy adults walking at a normal relaxed pace for approximately fifteen minutes each as our data set. A fractional Langevin equation is constructed to model the underlying motor control system in which the order of the fractional derivative is itself a stochastic quantity. Using this model we find the fractal dimension for each of the ten data sets to be in agreement with earlier analyses. However with the present model we are able to draw