scholarly journals Sample Entropy, Univariate, and Multivariate Multi-Scale Entropy in Comparison with Classical Postural Sway Parameters in Young Healthy Adults

2017 ◽  
Vol 11 ◽  
Author(s):  
Clint Hansen ◽  
Qin Wei ◽  
Jiann-Shing Shieh ◽  
Paul Fourcade ◽  
Brice Isableu ◽  
...  
Keyword(s):  
Postural Sway ◽  
Sample Entropy ◽  
Healthy Adults ◽  
Multi Scale

scholarly journals Inertial Sensor Reliability and Validity for Static and Dynamic Balance in Healthy Adults: A Systematic Review

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5167
Author(s):  
Nicky Baker ◽  
Claire Gough ◽  
Susan J. Gordon
Keyword(s):  
Systematic Review ◽  
Discriminant Validity ◽  
Inertial Sensors ◽  
Postural Sway ◽  
Inertial Sensor ◽  
Dynamic Balance ◽  
Healthy Adults ◽  
Gait Velocity ◽  
Time Data ◽  
Targeted Interventions

Compared to laboratory equipment inertial sensors are inexpensive and portable, permitting the measurement of postural sway and balance to be conducted in any setting. This systematic review investigated the inter-sensor and test-retest reliability, and concurrent and discriminant validity to measure static and dynamic balance in healthy adults. Medline, PubMed, Embase, Scopus, CINAHL, and Web of Science were searched to January 2021. Nineteen studies met the inclusion criteria. Meta-analysis was possible for reliability studies only and it was found that inertial sensors are reliable to measure static standing eyes open. A synthesis of the included studies shows moderate to good reliability for dynamic balance. Concurrent validity is moderate for both static and dynamic balance. Sensors discriminate old from young adults by amplitude of mediolateral sway, gait velocity, step length, and turn speed. Fallers are discriminated from non-fallers by sensor measures during walking, stepping, and sit to stand. The accuracy of discrimination is unable to be determined conclusively. Using inertial sensors to measure postural sway in healthy adults provides real-time data collected in the natural environment and enables discrimination between fallers and non-fallers. The ability of inertial sensors to identify differences in postural sway components related to altered performance in clinical tests can inform targeted interventions for the prevention of falls and near falls.

scholarly journals The Systematic Bias of Entropy Calculation in the Multi-Scale Entropy Algorithm

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 659
Author(s):  
Jue Lu ◽  
Ze Wang
Keyword(s):  
Time Series ◽  
Standard Deviation ◽  
Coarse Graining ◽  
Sample Entropy ◽  
Systematic Bias ◽  
Original Time Series ◽  
Multi Scale ◽  
Calculation Results ◽  
Surrogate Measure ◽  
Original Time

Entropy indicates irregularity or randomness of a dynamic system. Over the decades, entropy calculated at different scales of the system through subsampling or coarse graining has been used as a surrogate measure of system complexity. One popular multi-scale entropy analysis is the multi-scale sample entropy (MSE), which calculates entropy through the sample entropy (SampEn) formula at each time scale. SampEn is defined by the “logarithmic likelihood” that a small section (within a window of a length m) of the data “matches” with other sections will still “match” the others if the section window length increases by one. “Match” is defined by a threshold of r times standard deviation of the entire time series. A problem of current MSE algorithm is that SampEn calculations at different scales are based on the same matching threshold defined by the original time series but data standard deviation actually changes with the subsampling scales. Using a fixed threshold will automatically introduce systematic bias to the calculation results. The purpose of this paper is to mathematically present this systematic bias and to provide methods for correcting it. Our work will help the large MSE user community avoiding introducing the bias to their multi-scale SampEn calculation results.

Intrinsic Mode Entropy Analysis of Tube-Wall Pressure Fluctuation Signals in the Kenics Static Mixer

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Hui-Bo Meng ◽  
Zhi-Qiang Liu ◽  
Yan-Fang Yu ◽  
Qiang Xiong ◽  
Jian-Hua Wu
Keyword(s):  
Pressure Fluctuation ◽  
Tube Wall ◽  
Sample Entropy ◽  
Wall Pressure ◽  
High Frequency Component ◽  
Static Mixer ◽  
Flow Rates ◽  
Multi Scale ◽  
Wall Pressure Fluctuation ◽  
Macro Scale

The multi-scale nonlinear hydrodynamics in Kenics Static Mixer (KSM) with 100 mm in diameter and 2 in aspect ratio was investigated in this work. The time series of tube-wall pressure fluctuation signals were measured at different flow rates ranged of 100~600 L•h-1 and at different axial positions in the range of 420~580 mm away from the cross-section of mixer inlet. It is difficult for composite signals to make an effective analysis by Sample Entropy (SampEn) based on a single scale. The complexity of tube-wall pressure fluctuation signals in a Kenics static mixer was investigated using Intrinsic Mode Entropy (IMEn) based on Sample Entropy algorithm and Empirical Mode Decomposition (EMD) method. Data sampling length and tolerance are optimized based on intrinsic mode entropy. Results of multi-scale analysis of pressure fluctuations indicated that the Sample entropy reaches maximum in the first scale and progressively decreases according to increase of the decomposed order. It is clear that the movement of high frequency component of the pressure signal is the most complicated and is rich in randomness. With the decomposition scales increasing, the complexity of signal decreases and approaches periodic motion eventually. The intrinsic mode entropy of the tube wall pressure signals in KSM has similar development tendencies in different flow rates. Besides, as the flow rates increased, the macro-scale vortexes play a more and more important role and guide the system to develop toward the stable state.

STRUCTURAL DAMAGE DETECTION BY MULTI-SCALE CROSS-SAMPLE ENTROPY

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Jui-Chang Liang ◽  
Ming-Jing Wang ◽  
Tzu-Kang Lin
Keyword(s):  
Structural Damage ◽  
Damage Index ◽  
Steel Structure ◽  
Vibration Signal ◽  
Sample Entropy ◽  
Ambient Vibration ◽  
Multi Scale ◽  
Damage Location ◽  
Damage Condition ◽  
Accuracy Rates

This study proposes a structural health monitoring (SHM) system based on multi-scale entropy (MSE) and multi-scale cross-sample entropy (MSCE). By measuring the ambient vibration signal from a structure, the damage condition can be rapidly evaluated via a MSE analysis. The damage location can then be detected by analyzing the signals of different floors under the same damage condition via a MSCE analysis. Moreover, a damage index is proposed to efficiently quantify the SHM process. A numerical simulation of a four-story steel structure is used to verify that the damage location and condition can be detected by the proposed SHM algorithm, and the location can be efficiently quantified by the damage index. Based on the results, the damage condition can be correctly assessed, and accuracy rates of 60% and 86% for the damage location can be achieved using the MSCE and damage index methods, respectively.

Manual and Cognitive Dual Tasks Contribute to Fall-Risk Differentiation in Posturography Measures

2016 ◽  
Vol 32 (6) ◽  
pp. 541-547 ◽  
Author(s):  
Renee Beach Sample ◽  
Kurt Jackson ◽  
Allison L. Kinney ◽  
Wiebke S. Diestelkamp ◽  
Senia Smoot Reinert ◽  
...  
Keyword(s):  
Older Adults ◽  
Dual Task ◽  
Postural Sway ◽  
Cognitive Task ◽  
Sample Entropy ◽  
Scaling Exponent ◽  
Confidence Ellipse ◽  
Nonlinear Analyses ◽  
Severe Injuries ◽  
Manual Task

Falls occur in 33% of older adults each year, some leading to moderate to severe injuries. To reduce falls and fall-related injuries, it is important to identify individuals with subtle risk factors elevating their likelihood of falling. The objective of this study was to determine how postural sway measures differed between fallers and nonfallers under standard and dual-task conditions. Quietstanding posturography measures were collected from 150 older adults during standard, cognitive, manual, and cognitive+manual tasks, and analyzed through traditional and nonlinear analyses. Of the traditional measures, M/L sway range and 95% confidence ellipse sway area showed statistically significant differences in all 4 test conditions between fallers and nonfallers. Although the manual dual task showed the most stable balance, effect sizes demonstrated larger differences between fallers and nonfallers. Nonlinear analysis revealed M/L sample entropy and M/L α-scaling exponent differentiating between fallers and nonfallers, with the cognitive task demonstrating larger differences. Based on the results, it is recommended to: (1) apply M/L sway range and 95% confidence ellipse area, (2) use the manual task to differentiate between fallers and nonfallers when using traditional analyses, and (3) use the cognitive task and M/L alpha and M/L sample entropy when using nonlinear analyses.

scholarly journals 8B45 A Statistical Classification of Upright Postural Sway in Healthy Adults and Patients with Parkinson's Disease

2012 ◽  
Vol 2012.24 (0) ◽  
pp. _8B45-1_-_8B45-2_
Author(s):  
Tomohisa YAMAMOTO ◽  
Charles E. SMITH ◽  
Yasuyuki SUZUKI ◽  
Takao TANAHASHI ◽  
Takayuki ENDO ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Postural Sway ◽  
Healthy Adults ◽  
Statistical Classification

scholarly journals Visual Fixations and Motion Sensitivity: Protocol for an Exploratory Study (Preprint)

2019 ◽  
Author(s):  
Shikha Chaudhary ◽  
Nicola Saywell ◽  
Arun Kumar ◽  
Denise Taylor
Keyword(s):  
New Zealand ◽  
Postural Sway ◽  
Force Plate ◽  
Ethics Committees ◽  
Healthy Adults ◽  
Eye Tracker ◽  
Shopping Malls ◽  
Motion Sensitivity ◽  
Clinical Trials Registry ◽  
Visual Fixations

BACKGROUND Motion sensitivity after vestibular disorders is associated with symptoms of nausea, dizziness, and imbalance in busy environments. Dizziness and imbalance are reported in places such as supermarkets and shopping malls which have unstable visual backgrounds; however, the mechanism of motion sensitivity is poorly understood. OBJECTIVE The main aim of this exploratory observational study is to investigate visual fixations and postural sway in response to increasingly complex visual environments in healthy adults and adults with motion sensitivity. METHODS A total of 20 healthy adults and 20 adults with motion sensitivity will be recruited for this study. Visual fixations, postural sway, and body kinematics will be measured with a mobile eye tracker device, force plate, and 3D motion capture system, respectively. Participants will be exposed to experimental tasks requiring visual fixation on letters, projected on a range of backgrounds on a large screen during quiet stance. Descriptive statistics (mean and standard deviation) will be calculated for each of the variables. One-way independent-measures analyses of variance will be performed to investigate the differences between groups for all variables. RESULTS Data collection was started in May 2019 and was completed by February 2020. It was approved by Health and Disability Ethics Committees, Ministry of Health, New Zealand on November 2, 2018 (Ethics ref: 18/CEN/193). We are currently processing the data and will begin data analysis in July 2020. We expect the results to be available for publication by the end of 2020. The trial was funded by the Neurology Special Interest Group, Physiotherapy New Zealand, and the Eisdell Moore Centre in November 2018. CONCLUSIONS This study will provide a detailed investigation of visual fixations in response to increasingly complex visual environments. Investigating characteristics of visual fixations in healthy adults and those with motion sensitivity will provide insight into this disabling condition and may inform the development of new intervention strategies which explicitly cater to the needs of this population. CLINICALTRIAL Australian New Zealand Clinical Trials Registry, ACTRN12619000254190; https://tinyurl.com/yxbn7nks INTERNATIONAL REGISTERED REPORT PRR1-10.2196/16805

Differences in postural sway among healthy adults are associated with the ability to perform steady contractions with leg muscles

2020 ◽  
Vol 238 (2) ◽  
pp. 487-497 ◽  
Author(s):  
Leah A. Davis ◽  
Stephen P. Allen ◽  
Landon D. Hamilton ◽  
Alena M. Grabowski ◽  
Roger M. Enoka
Keyword(s):  
Postural Sway ◽  
Healthy Adults ◽  
Leg Muscles
Sign in / Sign up

Export Citation Format

Share Document