Frequency and displacement amplitude relations for normal hand tremor

1976 ◽  
Vol 40 (1) ◽  
pp. 44-54 ◽  
Author(s):  
R. N. Stiles
Keyword(s):  
Spectral Analysis ◽  
Small Amplitude ◽  
Continuous Extension ◽  
Normal Subjects ◽  
Displacement Amplitude ◽  
Modulation Amplitude ◽  
Mean Square ◽  
Hand Tremor ◽  
Normal Hand ◽  
Tremor Frequency

Spectral analysis of hand tremor records obtained from normal subjects during continuous extension of the hand for 15–45 min revealed that the root-mean-square (rms) displacement amplitude of the tremor increased from control levels of about 30 mum to levels on the order of 100–1,000 times control. Associated with this increase in the displacement was a systematic decrease in the hand tremor frequency from control values of 8–9 Hz to values of 4–6 Hz. Spectral analysis of demodulated extensor EMG records indicated a consistent relation between EMG modulation amplitude at the tremor frequency and the tremor displacement amplitude for tremor records with rms displacement above about 100 mum. No consistent relation was found between these two variables for tremor records with displacements below 100 mum. Consideration of both mechanical and neural reflex effects indicated that a viscoelastic-mass mechanism primarily determined the small-amplitude (less than 100 mum) tremors, while the large displacement tremors may have involved both mechanical and neural feed back factors.

Involuntary ankle oscillations from normal subjects

1977 ◽  
Vol 233 (1) ◽  
pp. R8-R14
Author(s):  
R. N. Stiles ◽  
R. R. Rietz
Keyword(s):  
Spectral Analysis ◽  
Root Mean Square ◽  
Power Function ◽  
Normal Subjects ◽  
Displacement Amplitude ◽  
Mean Square ◽  
Hand Tremor ◽  
Negative Relation ◽  
Tremor Frequency

Spectral analysis of ankle tremor records obtained from normal seated subjects during continuous elevation of the heel for 10-45 min revealed that the root-mean-square (rms) displacement amplitude of the tremor increased from minimum values of about 4 micronm to values as large as 4,000 micronm. Associated with this increase in the displacement amplitude was a systematic decrease in the tremor frequency from values of 7-8 Hz to values of 5-6 Hz. Spectral analysis of demodulated soleus EMG records indicated that the rms value of this EMG (calculated at the tremor frequency) and the rms displacement of the tremor are related by a power function, with the rms value of the EMG increasing over a range of about 4-40 micronV as the tremor displacement increased from about 4 to 4,000 micronm. The negative relation between frequency and rms displacement amplitude values for postural ankle tremor was similar to that found previously for postural hand tremor.

A mechanical-reflex oscillator hypothesis for parkinsonian hand tremor

1976 ◽  
Vol 40 (6) ◽  
pp. 990-998 ◽  
Author(s):  
R. N. Stiles ◽  
R. S. Pozos
Keyword(s):  
Spectral Analysis ◽  
Steady State ◽  
Root Mean Square ◽  
Fold Increase ◽  
Normal Subjects ◽  
Single Frequency ◽  
Mean Square ◽  
Hand Tremor ◽  
S Period ◽  
Rms Amplitude

Spectral analysis was performed on postural hand tremor records obtained from 22 parkinsonian subjects. Of these 22 subjects, 18 had postural hand tremor that occurred primarily at a single frequency during any one 16-s period. In general, this tremor occurred at different steady-state frequencies (each calculated over 16 s) between about 4 Hz and 8–9 Hz. This frequency decreased approximately 1 Hz for each 10-fold increase in displacement amplitude (root-mean-square, rms, amplitude determined at 16 cm from the wrist), decreasing from 8–9 Hz at about 30 mum to 3.75–4.0 Hz at about 30,000 mum. The major finding was that the frequency of parkinsonian hand tremor was nearly the same as that for hand tremor from normal subjects when these frequenceis were compared at similar rms displacement levels. This comparison, plus a comparison between other aspects of these two kinds of tremor, indicate that the mechanism for parkinsonian hand tremor is similar to that for large-displacement (greater than 100 mum) hand tremor of normal subjects, i.e., a mechanical-reflex oscillator mechanism.

Acceleration time series resulting from repetitive extension-flexion of the hand

1975 ◽  
Vol 38 (1) ◽  
pp. 101-107 ◽  
Author(s):  
R. N. Stiles
Keyword(s):  
Frequency Band ◽  
Normal Subjects ◽  
Peak Frequency ◽  
Hand Tremor ◽  
Low Frequencies ◽  
Frequency Bands ◽  
Normal Hand ◽  
The Subject ◽  
The Time Domain ◽  
Oscillation Frequencies

Power, or variance, spectra of acceleration records obtained from normal subjects during extension-flexion oscillations of a hand at frequencies between 0.5–5.0 Hz generally contained two or three frequency bands. Partial separation of these oscillations in the time domain was obtained using the method of digital filtering (smoothing). In general, the peak frequency of the lowest frequency band occurred at, or nearly at, the frequency that the subject attempted to maintain during a 16-s digitization period. Consideration of absolute frequencies and the effect of mass on frequency indicated that one of the higher frequency bands was the result of normal hand tremor. For low frequencies of voluntary oscillation (0.5–1.25 Hz), a second, higher frequency band occurred with a peak frequency (3.0–4.25 Hz) within the range (3–6 Hz) usually reported for abnormal hand tremor. For voluntary oscillation frequencies above about 1.5 Hz, this second, higher frequency oscillation generally occurred at twice the frequency of the voluntary oscillation.

The Relationship of Root Mean Square Value of Electromyography and Isometric Torque of Quadriceps in Normal Subjects

2016 ◽  
Vol 26 (1) ◽  
pp. 58
Author(s):  
Qiurong XIE ◽  
Zheng JIANG ◽  
Qinglu LUO ◽  
Jie LIANG ◽  
Xiaoling WANG ◽  
...  
Keyword(s):  
Root Mean Square ◽  
Normal Subjects ◽  
Mean Square ◽  
Isometric Torque ◽  
Relationship Of ◽  
The Relationship

Some further studies about generalised spectral norms

2021 ◽  
Vol 63 (6) ◽  
pp. 362-369
Author(s):  
K Karioja ◽  
E Juuso ◽  
J Nissilä
Keyword(s):  
Spectral Analysis ◽  
Root Mean Square ◽  
Automatic Monitoring ◽  
Vibration Monitoring ◽  
Spectral Information ◽  
Measured Signal ◽  
Mean Square ◽  
Automatic Monitoring System ◽  
Special Cases ◽  
Peak Value

Spectral analysis is a very common tool in vibration monitoring. While useful in machine diagnostics, spectral analysis can be rather time consuming. Tasks that require an extensive amount of time are often considered too expensive, especially in modern industry. To achieve an automatic monitoring system of some kind, different features, such as the root mean square (RMS) or the peak value of signals, are often monitored. These are special cases of generalised norms, which can be effective tools to determine whether a signal has shown some kind of change and how notable the change is when compared to a previously measured signal, for example. However, no spectral information is obtained in this way and the question regarding the frequency in the signal at which the change has occurred remains unanswered. Generalised spectral norms are a frequency-domain application of these norms and, as presented in this paper, provide a suitable way to perform automatic monitoring regarding the spectral information, for example.

Structural Characterization of Composition-Modulated ZnSel-xTex Epitaxial Films

1995 ◽  
Vol 417 ◽  
Author(s):  
S. P. Ahrenkiel ◽  
M. H. Bode ◽  
M. M. Al-Jassim ◽  
H. Luo ◽  
S. H. Xin ◽  
...  
Keyword(s):  
Cross Sections ◽  
Small Amplitude ◽  
Molecular Beam ◽  
Growth Direction ◽  
Epitaxial Films ◽  
Modulation Amplitude ◽  
Transmission Electron ◽  
Short Period ◽  
Strain Modulation

AbstractWe examine the microstructure of short-period (14–31 Å) composition modulations in epitaxial ZnSel-xTex ([email protected]) films grown by molecular-beam epitaxy (MBE) on vicinal (001) GaAs. Transmission electron microscope (TEM) images of cross-sections reveal highly-periodic contrast along the growth direction throughout the full thicknesses of the films (over 2 μm) that corresponds to a nearly sinusoidal variation between Se- and Te-rich compositions. Growth of ZnSe1-xTex at 285°C on substrates tilted 4° toward [1111 maximizes the strength and regularity of the modulation. Using dynamical electron-diffraction simulations, we estimate a modulation amplitude of [email protected](7) in a sample showing strong modulation. We assume a small amplitude of strain modulation to fit the experimental data.

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