Study of stabilometry during standing upright in patients with spinocerebellar degeneration: Appearance and significance of the dominant peak-frequency of 3Hz in body sway

It has been demonstrated many times that the posture of infants is affected by movement of the visual environment. However, in previous studies, measurements taken with infants less than 10 to 12 months of age have always been recorded with the infants in a sitting position. An experiment is reported in which the postural reactions to a sinusoidal movement of the visual environment were recorded in infants 7 months of age and older standing with support. Fifty subjects divided into five groups (mean age 7.15 to 48.6 months) participated in the experiment. The groups differed in age and motor ability. Movement of the visual environment was achieved by means of a floorless room that could be moved sinusoidally in the anteroposterior axis. The subjects had to stand holding a horizontal bar fixed to a force-measurement platform. For each subject, measurements were made during four 60 s intervals: two with movement of the room and two with the room stationary. For all groups, reactions in the anteroposterior axis were stronger than in the lateral axis and this was true for both stimulus conditions. Comparison of the differences between the movement and stationary conditions in the anteroposterior axis, as a function of age, shows that the youngest infants seemed paradoxically to give stronger reactions when the room was stationary than when it was moving; the inverse was true for older infants and this difference increased with age. An analysis of the data with fast Fourier transforms reveals that the majority of subjects showed a pattern of postural reactions where the dominant (peak) frequency was identical to the peak frequency of room movement. The results of the present experiment lead to the conclusion that young infants react posturally to movements of their visual environment as soon as they are able to stand without help. Also, the best synchronization is found in infants that have just learned to stand without help. These results confirm that ‘visual proprioception’ assumes a leading role in the learning of a new stance.

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Multiphase Sloshing and Interfacial Wave Interaction With a Baffle and a Submersed Block

Journal of Fluids Engineering ◽

10.1115/1.4041988 ◽

2019 ◽

Vol 141 (7) ◽

Cited By ~ 8

Author(s):

Obai Kargbo ◽

Mi-An Xue ◽

Jinhai Zheng

Keyword(s):

Free Surface ◽

Interfacial Layer ◽

Fluid Velocity ◽

Wave Interaction ◽

Peak Frequency ◽

Arbitrary Lagrangian Eulerian ◽

Interfacial Wave ◽

Arbitrary Lagrangian Eulerian Method ◽

Fluid Layers ◽

Dominant Peak

A numerical model of a rectangular tank containing a layered liquid is modeled for studying layered sloshing wave. The Arbitrary Lagrangian Eulerian method is used to track the development for both the interfacial and free surface of the fluid domain. A series of cases are simulated for baffled and unbaffled sloshing with various excitation frequencies and various baffle configurations. A case containing a submerged block is also simulated to observe the interfacial wave interaction with the block structure and to observe how the position and size of the block affect the interfacial wave in a fluid. Velocity screenshots are analyzed for observing the velocity distribution in the layers and to observe the behavior of the interfacial layer for baffled and unbaffled tank cases. A fast Fourier transform spectral analysis of the layered liquid sloshing time series for both the interfacial layer and free surface layer is presented to observe the energy in the fluid layers as well as to observe the dominant peak frequency for both the layers.

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Contribution of Vision to the Stabilization of Body Sway in Patients with Spinocerebellar Degeneration

Acta Oto-Laryngologica ◽

10.3109/00016489309128135 ◽

1993 ◽

Vol 113 (sup504) ◽

pp. 117-119 ◽

Cited By ~ 3

Author(s):

Naoki Ohashi ◽

Hajime Nakagawa ◽

Masatsugu Asai

Keyword(s):

Body Sway ◽

Spinocerebellar Degeneration

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Wake-Body Interaction Noise Simulated by the Coupling Method Using CFD and BEM

Vortex Dynamics Theories and Applications ◽

10.5772/intechopen.92783 ◽

2020 ◽

Author(s):

Masaaki Mori

Keyword(s):

Heat Exchanger ◽

Vortex Shedding ◽

Peak Frequency ◽

Flow Patterns ◽

Coupling Method ◽

Sound Generation ◽

Engineering Applications ◽

Rotating Blades ◽

Body Interaction ◽

Dominant Peak

In many engineering applications, obstacles often appear in the wake of obstacles. Vortices shed from an upstream obstacle interact with downstream obstacle and generate noise, for example blades in a turbomachinery, tubes in a heat exchanger, rotating blades like a helicopter and wind turbine and so on. This phenomenon is called wake-body interaction or body-vortex interaction (BVI). The rod-airfoil and airfoil-airfoil configurations are typical models for the wake-body interaction. A rod and an airfoil are immersed upstream of the airfoil. In this chapter, we review the noise mechanism generated by the wake-body interaction and show the numerical results obtained by the coupling method using commercial CFD and acoustic BEM codes. The results show that depending on the spacing between the rod or airfoil and the airfoil, the flow patterns and noise radiation vary. With small spacing, the vortex shedding from the upstream obstacle is suppressed and it results in the suppression of the sound generation. With large spacing, the shear layer or the vortices shed from the upstream obstacle impinge on the downstream obstacle and it results in the large sound generation. The dominant peak frequency of the generated sound varies with increase in the spacing between the two obstacles.

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ANALYSIS OF LATERAL BALANCE IN RESPONSE TO PERTURBATION BY SURFACE TILTS IN YOUNG AND ELDERLY ADULTS

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519418400092 ◽

2018 ◽

Vol 18 (07) ◽

pp. 1840009 ◽

Cited By ~ 1

Author(s):

YU-RI KWON ◽

YOON-HYEOK CHOI ◽

GWANG-MOON EOM ◽

JUNGHYUK KO ◽

JI-WON KIM

Keyword(s):

Center Of Pressure ◽

Frontal Plane ◽

The Elderly ◽

Peak Frequency ◽

Young Group ◽

Body Sway ◽

Elderly Adults ◽

Mean Velocity ◽

The Mean ◽

Balance Strategy

It is important to assess lateral balance because falls to the side frequently occur and lead to hip fracture in elderly adults. The aim of this study was to investigate lateral balance in response to lateral tilting perturbation in young and elderly adults. Fifty healthy subjects (28 young and 22 elderly) participated in this study. They were instructed to maintain postural balance against right-down and left-down perturbations. As outcome measures, the mean distance, mean velocity and peak frequency were derived from the center of pressure (COP) data in the frontal plane (medio-lateral). Independent [Formula: see text]-tests were performed to compare the elderly with the young. The elderly group exhibited a greater COP mean distance and faster mean velocity compared to the young group in right-down perturbation ([Formula: see text]). The COP peak frequency of the elderly was higher than that of the young in both right- and left-down perturbations ([Formula: see text]). These results suggest that the elderly have a dynamic lateral balance strategy with greater and faster body sway and with more frequent adjustments of the COP in response to lateral perturbation. This study will contribute to the understanding of lateral balance strategy in the elderly for the prevention and intervention of falls.

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Attenuation and Prediction of the Ground Vibrations Induced by High-Speed Trains Running Over Bridge

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455421500760 ◽

2021 ◽

pp. 2150076

Author(s):

Yunshi Zhang ◽

Yu Lou ◽

Nan Zhang ◽

Yanmei Cao ◽

Liu Chen

Keyword(s):

High Speed ◽

Free Field ◽

Prediction Method ◽

Ground Vibration ◽

Peak Frequency ◽

Vibration Acceleration ◽

Periodic Loading ◽

Frequency Domains ◽

High Speed Trains ◽

Dominant Peak

This paper aims to study the transfer laws of vibration signals in the free field near a high-speed train line by conducting a field test. The characteristics of ground vibration acceleration were analyzed in the time and frequency domains, and a prediction method in the frequency domain was proposed. The results show: (1) there is a vibration amplification area away from the bottom of the pier under the influence of high-speed trains running over the bridge due to the fluctuation attenuation of the vibration waves; (2) the dominant peak frequency points in the frequency spectrum of the acceleration can be regarded as the resonance frequency induced by periodic loading; and (3) the soil vibration can be effectively predicted by the proposed method with a strong capability to defend the interference of environmental vibrations according to the comparison between the predicted value and the experimental data.

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Wake-body interaction Noise Simulations by Coupling CFD and BEM

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-3067 ◽

2021 ◽

Vol 263 (1) ◽

pp. 5360-5371

Author(s):

Masaaki Mori

Keyword(s):

Heat Exchanger ◽

Vortex Shedding ◽

Peak Frequency ◽

Vortex Interaction ◽

Sound Generation ◽

Rotating Blades ◽

Body Interaction ◽

Noise Radiation ◽

Dominant Peak ◽

Small Spacing

In many engineering applications, the wake-body interaction or body-vortex interaction (BVI) occurs. In the wake-body interaction, vortices shed from an upstream obstacle interact with downstream obstacle and generate noise, for example blades in a turbomachinery, tubes in a heat exchanger, rotating blades like a helicopter and wind turbine and so on. The rod-airfoil and airfoil-airfoil configurations are typical models for the wake-body interaction. A rod and an airfoil are immersed upstream of the airfoil. In this paper, we reviewed the noise mechanism generated by the wake-body interaction and show the numerical results obtained by the coupling method using commercial CFD and acoustic BEM codes. The results shows that depending on the spacing between the rod or airfoil and the airfoil, the flow patterns and noise radiation vary. With small spacing, the vortex shedding from the upstream obstacle is suppressed and it results in the suppression of the sound generation. With large spacing, the shear layer or the vortices shed from the upstream obstacle impinge on the downstream obstacle and it results in the large sound generation. The dominant peak frequency of the generated sound varies with increasing of the spacing between the two obstacles.

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