scholarly journals Effect of sampling frequency on fractal fluctuations during treadmill walking

PLoS ONE ◽  
2019 ◽  
Vol 14 (11) ◽  
pp. e0218908 ◽  
Author(s):  
Vivien Marmelat ◽  
Austin Duncan ◽  
Shane Meltz
Keyword(s):  
Sampling Frequency ◽  
Treadmill Walking ◽  
Fractal Fluctuations

scholarly journals Effect of sampling frequency on fractal fluctuations during treadmill walking

2019 ◽  
Author(s):  
Vivien Marmelat ◽  
Austin Duncan ◽  
Shane Meltz
Keyword(s):  
Motion Capture ◽  
Event Detection ◽  
Temporal Dynamics ◽  
Intraclass Correlation ◽  
Sampling Frequency ◽  
Treadmill Walking ◽  
Fluctuation Analysis ◽  
Detection Accuracy ◽  
Gait Dynamics ◽  
Fractal Analyses

AbstractThe temporal dynamics of stride-to-stride fluctuations in steady-state walking reveal important information about locomotor control and can be quantified using so-called fractal analyses, notably the detrended fluctuation analysis (DFA). Gait dynamics are often collected during treadmill walking using 3-D motion capture to identify gait events from kinematic data. The sampling frequency of motion capture systems may impact the precision of event detection and consequently impact the quantification of stride-to-stride variability. This study aimed i) to determine if collecting multiple walking trials with different sampling frequency affects DFA values of spatiotemporal parameters during treadmill walking, and ii) to determine the reliability of DFA values across downsampled conditions. Seventeen healthy young adults walked on a treadmill while their gait dynamics was captured using different sampling frequency (60, 120 and 240 Hz) in each condition. We also compared data from the highest sampling frequency to downsampled versions of itself. We applied DFA to the following time series: step length, time and speed, and stride length, time and speed. Reliability between experimental conditions and between downsampled conditions were measured with 1) intraclass correlation estimates and their 95% confident intervals, calculated based on a single-measurement, absolute-agreement, two-way mixed-effects model (ICC 3,1), and 2) Bland-Altman bias and limits of agreement. Both analyses revealed a poor reliability of DFA results between conditions using different sampling frequencies, but a relatively good reliability between original and downsampled spatiotemporal variables. Collectively, our results suggest that using sampling frequencies of 120 Hz or 240 Hz provide similar results, but that using 60 Hz may alter DFA values. We recommend that gait kinematics should be collected at around 120 Hz, which provides a compromise between event detection accuracy and processing time.

The effects of mindfulness and music on affective responses to self-paced treadmill walking.

2020 ◽  
Vol 9 (4) ◽  
pp. 571-584
Author(s):  
Anne E. Cox ◽  
Sarah Ullrich-French ◽  
Elaine A. Hargreaves ◽  
Amanda K. McMahon
Keyword(s):  
Affective Responses ◽  
Treadmill Walking

ADRENOCORTICAL RESPONSE TO NON-EXHAUSTIVE MUSCULAR EXERCISE

1972 ◽  
Vol 70 (1) ◽  
pp. 73-80 ◽  
Author(s):  
L. W. Raymond ◽  
J. Sode ◽  
J. R. Tucci
Keyword(s):  
Treadmill Exercise ◽  
Serum Cortisol ◽  
Treadmill Walking ◽  
Exhaustive Exercise ◽  
Muscular Exercise ◽  
Adrenocortical Response ◽  
Exercise Tachycardia ◽  
Before And After

ABSTRACT Treadmill walking produced a prompt reduction in serum cortisol in 10 of 12 healthy military men. In contrast, two subjects, with pre-exercise tachycardia and apprehension, showed an increase in serum cortisol with treadmill exercise. In each group, the changes produced by exercise were still evident 30 and 60 minutes after the 30-minute treadmill walk. Urine collected before and after exercise contained similar amounts of 11-hydroxy- and 17-hydroxycorticosteroid material. These results may be explained by an increase in cortisol utilization during exercise and/or by a change in its distribution. The data indicate that in the absence of psychic factors, non-exhaustive exercise is not associated with pituitary adrenocortical activation.

FORMULATION AND SOLUTION OF OPTIMIZATION PROBLEM REDUNDANCY SYSTEM COMPRISING SITUATION CENTER

2019 ◽  
pp. 44-50
Author(s):  
A.V. Alekseev
Keyword(s):  
Analytical Model ◽  
Quality Indicators ◽  
Significant Influence ◽  
Optimization Problem ◽  
Sampling Theorem ◽  
Sampling Frequency ◽  
Generalized Sampling ◽  
Optimal Value ◽  
Situation Center ◽  
Situation Centers

The analysis of the concept, properties and features of heterogeneous redundancy in modern complex ergatic systems, including those included in the situation centers (SC). On the basis of the qualimetric paradigm, the generalized analytical model of quality and optimization of quality by private, group, summary and aggregated quality indicators is justified. Practical ways of realization of the model and methods of optimization of the objects which are a part of SC and them as a whole at the expense of reduction of structural, functional and other types of redundancy under the obligatory condition of non-reduction of the required value of quality are given. On the example of the generalized sampling theorem when choosing the optimal value of the sampling frequency of the real bandpass signal, the criticality and significant influence on the redundancy of data in their further processing in the SC is shown.

Determination of trace concentrations of copper by FIA-FAAS after preconcentration on chelating sorbents

1989 ◽  
Vol 54 (7) ◽  
pp. 1785-1794 ◽  
Author(s):  
Vlastimil Kubáň ◽  
Josef Komárek ◽  
Zbyněk Zdráhal
Keyword(s):  
Sampling Frequency ◽  
Copper Determination ◽  
Flow Rates ◽  
Sample Injection ◽  
Injection Flow ◽  
Chelating Sorbents ◽  
Set Up ◽  
Trace Concentrations ◽  
Better Than

A FIA-FAAS apparatus containing a six-channel sorption equipment with five 3 x 26 mm microcolumns packed with Spheron Oxin 1 000, Ostsorb Oxin and Ostsorb DTTA was set up. Combined with sorption from 0.002M acetate buffer at pH 4.2 and desorption with 2M-HCl, copper can be determined at concentrations up to 100, 150 and 200 μg l-1, respectively. For sample and eluent flow rates of 5.0 and 4.0 ml min-1, respectively, and a sample injection time of 5 min, the limit of copper determination is LQ = 0.3 μg l-1, repeatability sr is better than 2% and recovery is R = 100 ± 2%. The enrichment factor is on the order of 102 and is a linear function of time (volume) of sample injection up to 5 min and of the sample injection flow rate up to 11 ml min-1 for Spheron Oxin 1 000 and Ostsorb DTTA. For times of sorption of 60 and 300 s, the sampling frequency is 70 and 35 samples/h, respectively. The parameters of the FIA-FAAS determination (acetylene-air flame) are comparable to or better than those achieved by ETA AAS. The method was applied to the determination of traces of copper in high-purity water.

The Energy Response of Calorimeters

2018 ◽  
Author(s):  
Richard Wigmans
Keyword(s):  
Sampling Frequency ◽  
Integration Time ◽  
Signal Integration ◽  
Energy Response ◽  
Absorption Process ◽  
Active Materials ◽  
Unit Energy ◽  
Sampling Fraction ◽  
Signal Integration Time ◽  
Calorimeter Response

This chapter deals with the signals produced by particles that are being absorbed in a calorimeter. The calorimeter response is defined as the average signal produced per unit energy deposited in this absorption process, for example in terms of picoCoulombs per GeV. Defined in this way, a linear calorimeter has a constant response. Typically, the response of the calorimeter depends on the type of particle absorbed in it. Also, most calorimeters are non-linear for hadronic shower detection. This is the essence of the so-called non-compensation problem, which has in practice major consequences for the performance of calorimeters. The origins of this problem, and its possible solutions are described. The roles of the sampling fraction, the sampling frequency, the signal integration time and the choice of the absorber and active materials are examined in detail. Important parameters, such as the e/mip and e/h values, are defined and methods to determine their value are described.

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