Advisor Information
Vivien Marmelat
Location
Dr. C.C. and Mabel L. Criss Library
Presentation Type
Poster
Start Date
3-3-2017 9:00 AM
End Date
3-3-2017 10:15 AM
Abstract
Human Daily Motor Activity (DMA) is characterized by complex temporal fluctuations and scale invariance. DMA is estimated from a time series composed of continuous amounts of activity recorded with the Actigraph GT9X monitor. The purpose of this study was to measure the complex temporal fluctuations in several young healthy adults over a 7-day period. After six months there was a follow-up of another 7-day period. Future collections will involve healthy older adults and adults with Parkinson’s disease. For the first phase of this study, 24 healthy young adults wore the monitor on their non-dominant hand for seven straight days. For the second phase, 19 healthy young adults did the same. The data was sampled at 100 Hz and the Vector Magnitude was obtained every fifteen seconds. The Detrended Fluctuation Analysis (DFA) was used to estimate the scale invariance over an active 9 AM – 9 PM period. The DFA computes the average size of fluctuations (F) for every window size n between 10 and N/4, where N is the length of the time series. All zero numbers reflect periods where it was non-active and were taken out before the DFA was used. The slope of F(n) gives us the scaling exponent α. The reliability of the exponent α was tested using Intra-class correlations (ICC) Cronbach’s alpha. We found for the first phase that ICC Cronbach α1 = .7006 and the second phase ICC Cronbach α2 = .82. This suggests a high reliability in the DFA-alpha values estimated from the DMA.
Between-day reliability activity fluctuations in young adults at baseline and 6-months follow-up
Dr. C.C. and Mabel L. Criss Library
Human Daily Motor Activity (DMA) is characterized by complex temporal fluctuations and scale invariance. DMA is estimated from a time series composed of continuous amounts of activity recorded with the Actigraph GT9X monitor. The purpose of this study was to measure the complex temporal fluctuations in several young healthy adults over a 7-day period. After six months there was a follow-up of another 7-day period. Future collections will involve healthy older adults and adults with Parkinson’s disease. For the first phase of this study, 24 healthy young adults wore the monitor on their non-dominant hand for seven straight days. For the second phase, 19 healthy young adults did the same. The data was sampled at 100 Hz and the Vector Magnitude was obtained every fifteen seconds. The Detrended Fluctuation Analysis (DFA) was used to estimate the scale invariance over an active 9 AM – 9 PM period. The DFA computes the average size of fluctuations (F) for every window size n between 10 and N/4, where N is the length of the time series. All zero numbers reflect periods where it was non-active and were taken out before the DFA was used. The slope of F(n) gives us the scaling exponent α. The reliability of the exponent α was tested using Intra-class correlations (ICC) Cronbach’s alpha. We found for the first phase that ICC Cronbach α1 = .7006 and the second phase ICC Cronbach α2 = .82. This suggests a high reliability in the DFA-alpha values estimated from the DMA.