Comparing postural stability analyses to differentiate fallers and non-fallers ESM 6984: Frontiers in Dynamical Systems Final presentation Sponsor: Dr. Lockhart Team Members: Khaled Adjerid, Peter Fino, Mohammad Habibi, Ahmad Rezaei Fall risk assessment The injuries due to fall and slip pose serious problems to human life. Risk worsens with age Hip fractures and slips 15,400 American deaths $43.8 billion annually Technical approach How can we assess fall risk in the elderly? Walking and balance is complex Multiple mechanisms involved in slip and fall

Most assessment focused on age Prediction of fall is still a big challenge in human factor science. What data do we actually have? 60 second postural stability COP data Eyes open Eyes closed 41 fallers and 78 non-fallers Fallers categorized by one or more falls in past 12 months Average age: 76.3 7.4 Time Series Analysis Several methods have been developed for complexity and recurrence measures in time series: Shannon entropy (ShanEn) State Entropies

Renyi entropy (RenyEn) Approximate entropy (ApEn) Sample entropy (SaEn) Multiscale entropy (MSE) Composite multiscale entropy (CompMSE) Recurrence quantification analysis (RQAEn) Detrended fluctuation analysis (DFA) Sequence Entropies Input parameters were based of those used in throughout the literature for similar studies Complexity Method Acronym Type of Entropy Input Parameters

Index Renyi Entropy RenyEn State - =2,M Shannon Entropy ShanEn State - = 1, M Approximate Entropy ApEn Sequence - r = 0.2 std, m = 3 Sample Entropy SaEn Sequence -

r = 0.2 std, m =3 r = 0.2 std, m = 3, = 1, Multi-Scale Entropy MSE Sequence Slope and Area ,10 Composite Multi-scale r = 0.2 std, m = 3, = 1, CompMSE Sequence Slope and Area Entropy ,10 Recurrence Quantification m = 8, T = 6, RQAEn Analysis Entropy Sequence 0.30*meanmean =

vs nonfallers SaEn CompMSE MSE RQAEn Conclusion ShaEn could not detect eyes open and eyes close. SampEn, MSE and CompMSE could detect fallers and non-fallers. We showed increase in complexity among fallers Costa et al 2007 showed decrease in complexity among fallers Ramdani et al 2013 found a difference between fallers and nonfallers using RQAEn. We used radius and angle but previous studies used x and y coordinates. Previous studies had limited sample size (14 fallers) while in our

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