scholarly journals Studies of the sensibility to low frequency whole-body longitudinal vibration in man

1989 ◽  
Vol 25 (Supplement) ◽  
pp. 220-221 ◽  
Author(s):  
M. Uchikune ◽  
Y. Yoshida
Keyword(s):  
Longitudinal Vibration ◽  
Low Frequency ◽  
Whole Body

Torsional vestibulo-ocular reflex during whole-body oscillation in the upright and the supine position: II. Responses in patients after vestibular neuritis

2004 ◽  
Vol 14 (4) ◽  
pp. 353-359
Author(s):  
A. Schmid-Priscoveanu ◽  
A.A. Kori ◽  
D. Straumann
Keyword(s):  
Supine Position ◽  
Semicircular Canal ◽  
Low Frequency ◽  
Phase Changes ◽  
Vestibular Neuritis ◽  
Whole Body ◽  
Healthy Human ◽  
Phase Lead ◽  
Ocular Reflex ◽  
Vestibulo Ocular Reflex

In a recent study we demonstrated that otolith input modifies the torsional angular vestibulo-ocular reflex (torVOR) of healthy human subjects: Compared to turntable oscillations in supine position, oscillations in upright position increased the gain of torVOR by 0.1 and cancelled the phase lead originating from low-frequency semicircular canal signals. We asked whether these otolith-related changes of torVOR are still present in patients after vestibular neuritis (VN). Eight patients were sinusoidally oscillated about their naso-occipital axis in supine (canal-only stimulation) and upright (canal-and-otolith stimulation) position. Three-dimensional eye movements were recorded with dual search coils. The patients showed similar otolith-related gain and phase changes of the torVOR as healthy subjects: the gain increased by about 0.1 (p < 0.05) and the low-frequency phase lead from semicircular canal signals was abolished. These results indicate that otolith function after VN is still sufficient to interact with semicircular canal signals to optimize torsional gaze stabilization when the head is upright.

scholarly journals Spiral Sound Wave Transducer Based on the Longitudinal Vibration

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3674 ◽  
Author(s):  
Wei Lu ◽  
Yu Lan ◽  
Rongzhen Guo ◽  
Qicheng Zhang ◽  
Shichang Li ◽  
...  
Keyword(s):  
Sound Wave ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Sound Field ◽  
Field Measurements ◽  
Sound Waves ◽  
Underwater Sound ◽  
Three Dimensional Finite Element ◽  
Wave Transducer

A spiral sound wave transducer comprised of longitudinal vibrating elements has been proposed. This transducer was made from eight uniform radial distributed longitudinal vibrating elements, which could effectively generate low frequency underwater acoustic spiral waves. We discuss the production theory of spiral sound waves, which could be synthesized by two orthogonal acoustic dipoles with a phase difference of 90 degrees. The excitation voltage distribution of the transducer for emitting a spiral sound wave and the measurement method for the transducer is given. Three-dimensional finite element modeling (FEM)of the transducer was established for simulating the vibration modes and the acoustic characteristics of the transducers. Further, we fabricated a spiral sound wave transducer based on our design and simulations. It was found that the resonance frequency of the transducer was 10.8 kHz and that the transmitting voltage resonance was 140.5 dB. The underwater sound field measurements demonstrate that our designed transducer based on the longitudinal elements could successfully generate spiral sound waves.

Non-Linear Dynamic Magneto Electric Effects in Ferromagnetic-Ferroelectric Layered Composites

2013 ◽  
Author(s):  
Satenik Harutyunyan ◽  
Davresh Hasanyan
Keyword(s):  
Vibration Frequency ◽  
Strain Distribution ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Structure Design ◽  
Experimental Results ◽  
Physical Parameters ◽  
Wide Range ◽  
Non Linear

A non-linear theoretical model including bending and longitudinal vibration effects was developed for predicting the magneto electric (ME) effects in a laminate bar composite structure consisting of magnetostrictive and piezoelectric multi-layers. If the magnitude of the applied field increases, the deflection rapidly increases and the difference between experimental results and linear predictions becomes large. However, the nonlinear predictions based on the present model well agree with the experimental results within a wide range of applied electric field. The results of the analysis are believed to be useful for materials selection and actuator structure design of actuator in actuator fabrication. It is shown that the problem for bars of symmetrical structure is not divided into a plane problem and a bending problem. A way of simplifying the solution of the problem is found by an asymptotic method. After solving the problem for a laminated bar, formula that enable one to change from one-dimensional required quantities to three dimensional quantities are obtained. The derived analytical expression for ME coefficients depend on vibration frequency and other geometrical and physical parameters of laminated composites. Parametric studies are presented to evaluate the influences of material properties and geometries on strain distribution and the ME coefficient. Analytical expressions indicate that the vibration frequency strongly influences the strain distribution in the laminates, and that these effects strongly influence the ME coefficients. It is shown that for certain values of vibration frequency (resonance frequency), the ME coefficient becomes infinity; as a particular case, low frequency ME coefficient were derived as well.

Optimal frequency of whole body vibration training for improving balance and physical performance in the older people with chronic stroke: A randomized controlled trial

2021 ◽  
pp. 026921552110505
Author(s):  
Ning Wei ◽  
Mengying Cai
Keyword(s):  
Older People ◽  
Physical Performance ◽  
High Frequency ◽  
Low Frequency ◽  
Chronic Stroke ◽  
Whole Body ◽  
Timed Up And Go ◽  
Stand Test ◽  
Sit To Stand ◽  
Frequency Group

Objective To explore the optimal frequency of whole-body vibration training for improving the balance and physical performance in older people with chronic stroke. Design a single-blind randomized controlled trial. Setting Two rehabilitation units in the Wuhan Brain Hospital in China. Participants A total of 78 seniors with chronic stroke. Interventions Low-frequency group (13 Hz), high-frequency group (26 Hz), and zero-frequency group (Standing on the vibration platform with 0 Hz) for 10 sessions of side-alternating WBV training. Main measures The timed-up-and-go test, five-repetition sit-to-stand test, 10-metre walking test, and Berg balance scale were assessed pre- and post-intervention. Results Significant time × group interaction effects in five-repetition sit-to-stand test (p = 0.014) and timed-up-and-go test at self-preferred speed (p = 0.028) were observed. The high-frequency group outperformed the zero-frequency group in both five-repetition sit-to-stand test (p = 0.039) and timed-up-and-go test at self-preferred speed (p = 0.024) after 10-sessions training. The low-frequency group displayed only a significant improvement in five-repetition sit-to-stand test after training (p = 0.028). No significant within- or between-group changes were observed in the Berg balance scale and walking speed (p > 0.05). No significant group-difference were found between low-frequency and high-frequency groups. No adverse events were reported during study. Conclusions Compared with 13 Hz, 26 Hz had no more benefits on balance and physical performance in older people with chronic stroke.

Cardiac autonomic function during hypothermia and its measurement repeatability

2019 ◽  
Vol 44 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Gary J. Hodges ◽  
Steven A.H. Ferguson ◽  
Stephen S. Cheung
Keyword(s):  
Heart Rate ◽  
Rectal Temperature ◽  
Mild Hypothermia ◽  
Core Body Temperature ◽  
Intraclass Correlation ◽  
Low Frequency ◽  
Whole Body ◽  
Body Cooling ◽  
Mean Square Difference ◽  
Whole Body Cooling

This study examined the effect of mild hypothermia (a 0.5 °C decrease in rectal temperature) on heart rate variability (HRV), with the identical hypothermia protocol performed twice and compared using intraclass correlation coefficient (r) analysis to study the repeatability. Twelve healthy males each completed 1 neutral (23 °C) and 2 cold (0 °C) trials. In the neutral trial, participants sat quietly for 30 min. In the cold trials, baseline data were obtained from a 5-min sample following 30 min of quiet sitting at 23 °C, followed by passive exposure to 0 °C; hypothermic measures were taken from a 5-min period immediately prior to rectal temperature decreasing by 0.5 °C. HRV was obtained from a 3-lead electrocardiogram. There were no differences (all p > 0.05) in baseline measures between the neutral and the 2 cold trials, suggesting no precooling anxiety related to the cold trials. Heart rate, together with HRV measures (i.e., root mean square difference of successive normal RR intervals, triangular interpolation of NN interval histogram, low-frequency oscillations (LF), and high-frequency oscillations (HF)), increased (all p < 0.05) with mild hypothermia and showed excellent reliability between the 2 cold trials (all r ≥ 0.81). In contrast, the LF/HF ratio decreased (p < 0.05) and had only fair reliability between the 2 cold trials (r = 0.551). In general, hypothermia led to increases in heart rate, together with most measures of HRV. Although it was counterintuitive that both sympathetic and vagal influences would increase simultaneously, these changes likely reflected increased stress from whole-body cooling, together with marked cardiovascular strain and sympathetic nervous system activity from shivering to defend core body temperature. An important methodological consideration for future studies is the consistent and repeatable HRV responses to hypothermia.

Cardiovascular responses to low‐frequency whole‐body acceleration

1981 ◽  
Vol 70 (S1) ◽  
pp. S36-S36
Author(s):  
C. Knapp ◽  
J. Evans ◽  
D. Randall ◽  
J. Marquis ◽  
A. Bhattacharya
Keyword(s):  
Low Frequency ◽  
Cardiovascular Responses ◽  
Whole Body ◽  
Body Acceleration

scholarly journals Effect of Low-Frequency Vibration on Muscle Response under Different Neurointact Conditions

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Chaofei Zhang ◽  
Wenjun Wang ◽  
Dennis Anderson ◽  
Sishu Guan ◽  
Guofa Li ◽  
...  
Keyword(s):  
Stretch Reflex ◽  
Muscle Force ◽  
Low Frequency ◽  
Quantitative Relationship ◽  
Length Change ◽  
Whole Body ◽  
Sprague Dawley ◽  
Nonlinear Hysteresis ◽  
Low Frequency Vibration ◽  
Gastrocnemius Muscles

Stretch reflex is an important factor that influences the biomechanical response of the human body under whole-body vibration. However, there is a lack of quantitative evaluation at lower frequencies. Thus, the aim of this study was to investigate the effects of vibration on the stretch reflex and, in particular, to explore the quantitative relationship between dynamic muscle responses and low-frequency vibrations. The gastrocnemius muscle of 45 Sprague-Dawley rats was dissected. Sinusoidal vibrations of five discrete frequencies (2~16 Hz) with peak-to-peak amplitudes of 1 mm were applied to the gastrocnemius muscles with 2 mm or 3 mm prelengthening. Variables including dynamic muscle force, vibration acceleration, and displacement were recorded in two conditions, with and without the stretch reflex. Results showed that the dynamic muscle forces decreased by 20% on average for the 2 mm prelengthening group after the stretch reflex was blocked and by 24% for the 3 mm prelengthening group. Statistical analysis indicated that the amplitude of dynamic muscle force in the “with stretch reflex” condition was significantly larger than that in the “without stretch reflex” condition (p<0.001). The tension-length curve was found to be a nonlinear hysteresis loop that changed with frequency. The phase difference between the dynamic muscle force and the length change was affected significantly by vibration frequency (p<0.01), and the minimum frequency was 4–8 Hz. Experimental results of this study could benefit musculoskeletal model by providing a theoretical support to build a stretch reflex model for low-frequency vibration.

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