Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “VIBRATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources
PubMed2002

Hand muscle weakness in long-term vibration exposure.

Hand muscle strength was compared between workers regularly exposed to hand-held vibrating tools (n=81) and a non-exposed control group (n=45). Maximal voluntary strengths of hand grip, thumb pinch, thumb palmar abduction and index and little finger abduction were measured. The exposed workers had significantly weaker extrinsic (7%, P<0.01) and intrinsic (19%, P<0.0001) muscles than the controls. Reduced vibration perception was noted in nine vibration-exposed workers who presented with symptoms of hand muscle weakness (P<0.01). Cold intolerance following vibration exposure was found to precede sensorineural and vasospastic symptoms. We therefore postulate that cold intolerance may be a valuable marker for early detection of the adverse effects of vibration. This study emphasizes the need for tests of intrinsic muscle strength in order to evaluate the impairment of hand function observed in vibration-exposed workers.

Adult↗
PubMed2005

Variational calculation of vibrational linear and nonlinear optical properties.

A variational approach for reliably calculating vibrational linear and nonlinear optical properties of molecules with large electrical and/or mechanical anharmonicity is introduced. This approach utilizes a self-consistent solution of the vibrational Schrodinger equation for the complete field-dependent potential-energy surface and, then, adds higher-level vibrational correlation corrections as desired. An initial application is made to static properties for three molecules of widely varying anharmonicity using the lowest-level vibrational correlation treatment (i.e., vibrational Møller-Plesset perturbation theory). Our results indicate when the conventional Bishop-Kirtman perturbation method can be expected to break down and when high-level vibrational correlation methods are likely to be required. Future improvements and extensions are discussed.

Algorithms↗
PubMed2006

Self-trapping of the N-H vibrational mode in alpha-helical polypeptides.

Recent calculations on the formation of self-trapped amide group vibrational states in alpha-helical polypeptides [J. Chem. Phys. 124, 134907 (2006)] are extended to the amide N-H normal mode vibrations. First, the adiabatic N-H vibrational single- and two-exciton states are examined by treating the longitudinal chain coordinates as parameters. Then, in using the multiconfiguration time-dependent Hartree method coupled exciton-chain vibrational quantum dynamics are accounted for. Based on the respective exciton-chain vibrational wave function propagation the infrared transient absorption related to a sequential pump-probe experiment is calculated. The modulation of local amide vibrational energies by the longitudinal chain coordinates is found to have a pronounced effect on the broadening of absorption lines. Moreover, the ultrafast exciton transfer in the system is studied in order to characterize the dynamics of the self-trapped single-exciton states on a time scale below 10 ps.

Computer Simulation↗
PubMed2000

Imposed vibration influences perceived tactile smoothness.

According to the duplex theory of tactile texture perception, detection of cutaneous vibrations produced when the exploring finger moves across a surface contributes importantly to the perception of fine textures. If this is true, a vibrating surface should feel different from a stationary one. To test this prediction, experiments were conducted in which subjects examined two identical surfaces, one of which was surreptitiously made to vibrate, and judged which of the two was smoother. In experiment 1, the vibrating surface was less and less often judged smoother as the amplitude of (150 Hz) vibration increased. The effect was comparable in subjects who realized the surface was vibrating and those who did not. Experiment 2 showed that different frequencies (150-400 Hz) were equally effective in eliciting the effect when equated in sensation level (dB SL). The results suggest that vibrotaction contributes to texture perception, and that, at least within the Pacinian channel, it does so by means of an intensity code.

Adolescent↗
PubMed1994

Absorption of vibration energy in the human hand and arm.

A possible basis for the risk assessment for hand-transmitted vibration may be to determine the amount of energy absorbed in the human hand and arm. In the present study, the mechanical energy absorption in the hand-arm system was measured within the frequency range of 4 to 1000 Hz. The study was carried out on ten healthy subjects during exposure to sinusoidal vibration. The influence of various experimental conditions, such as vibration direction (Xh, Yh, Zh), grip force (25-75 N), vibration level (8-45 mm/srms), and hand-arm posture were studied. The outcome shows that the energy absorption in the human hand and arm depended mainly on the frequency and direction of the vibration stimulus. Higher vibration levels, as well as firmer handgrips, resulted in higher absorption of energy. Varying hand-arm postures had only a small influence on the amount of absorbed energy, while the constitution of the hand and arm affected the energy absorption to a larger extent.

Arm↗
PubMed1994

Transmission of roll and pitch seat vibration to the head.

A series of experiments has investigated the transmission of roll and pitch seat vibration to the heads of seated subjects. Head motion was measured in all six axes using a light-weight bite-bar while seated subjects were exposed to random motion at frequencies of up to 5 Hz at 1.0 rad.s -2 r.m.s. Subjects sat on a rigid flat seat in two body postures: 'back-on' (back in contact with backrest) and 'back-off' (no backrest contact). The influence of the position of the centre of rotation was also investigated. Motion at the head occurred mostly in the lateral, roll and yaw axes during exposure to roll seat vibration and in the fore-and-aft, vertical and pitch axes during exposure to pitch seat vibration. A reduction in the magnitude of head motion occurred when the subjects sat in a 'back-off' posture compared with a 'back-on' posture. Varying the position of the centre of rotation along the lateral axis during roll seat vibration affected vertical and pitch head motion: least head motion occurred when the centre of rotation was in line with the subject's mid-sagittal plane. Varying the position of the centre of rotation along the vertical axis during roll seat vibration affected head motion in the mid-coronal plane: roll head motion decreased as the position of the centre of rotation was raised from below the seat surface to above the seat surface. Varying the centre of rotation (along the fore-and-aft and vertical axes) during pitch seat vibration altered head motion in the mid-sagittal plane.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Vibration analysis of the temporomandibular joints with degenerative joint disease.

The surface vibrations of 42 temporomandibular joints (TMJ) with degenerative joint disease (DJD) and/or perforation of the disk were evaluated using electrovibratography and compared to the surface vibrations of 83 joints with normal TMJ imagings and 61 joints with meniscal displacement without reduction. Through the frequency spectrum analysis, TMJs with DJD showed higher vibration energy above 350-450 Hz and TMJs with perforation showed higher vibration energy between 100-150 and 300-450 Hz. The presence of perforation did not seem to affect the characteristic of vibrations when TMJs were associated with DJD. A threshold was set for the total vibration energy as described in our previous report and used as a parameter in order to separate patients with internal derangement from a pool of TMJ dysfunction patients (diagnostic specificity = 75%, diagnostic sensitivity = 80.2%). Using this criteria, the following were correctly identified as internal derangement and/or DJD: a) 100% of the TMJs with meniscal displacement without reduction associated with DJD; b) 87.0% of the TMJs with meniscal displacement without reduction associated with perforation; c) 88.9% of the TMJs with meniscal displacement without reduction associated with DJD and perforation; and d) 100% of the TMJs with perforation.

Adolescent↗
PubMed2001

Wavelet transforms of TM joint vibrations: a feature extraction tool for detecting reducing displaced disks.

The objective of this study was to determine if wavelet transforms (WTs) of vibrations recorded from temporomandibular joints (TMJs) with reducing displaced disks could be visually separated from WTs of vibrations recorded from normal TM joints by blinded observers. From a continuous series of 124 diagnosed TMD patients, 28 were confirmed with at least one reducing displaced disk. Vibrations were recorded from each affected joint, together with incisal point movements, using BioPAK (BioResearch, Inc., Milwaukee, WI) during opening, closing, and lateral excursions. Identical recordings were taken from 28 patients who were determined to have normal "nondisplacing, nondisplaced" joints. A 3x7 Biorthogonal Spline Wavelet Transform was used to create three-dimensional time-frequency graphs of the vibration events for each subject. Printed copies of the graphs were then shown sequentially to seven blinded observers who were asked to separate them into two groups without any knowledge of their significance. Each observer was independently able to separate the two groups without committing more than one error. We conclude that the vibrations generated by reducing displaced disks are sufficiently different from the vibrations of normal joints to be separable by visual inspection of their respective wavelet transforms.

Humans↗
PubMed1985

Assessment of hand vibration exposure on an assembly line.

This paper describes a study undertaken to evaluate and control vibration exposure associated with pneumatic screwdrivers used in an electrical appliance assembly plant. The study was motivated by management's concern about reports of cumulative trauma disorders in the upper extremities of workers who used pneumatic screwdrivers. Vibration exposure from power hand tools on an assembly line is difficult to predict due to highly variable conditions and techniques used between operators. Vibration exposure was measured using observation samples of tool vibration obtained on the assembly line for individual assembly tasks. Typical tool one-third octave band acceleration spectra estimated from laboratory measurements were used in conjunction with the measured exposure times to compare workers' risk of exposure to the hazards associated with operating vibrating hand tools. Characteristic vibration produced by the tools during phases of operation were separated and analyzed individually to identify and control the source.

Hand↗
PubMed1996

Adjusting the evaluation limit for broad-band whole-body vibration.

The vibration levels of 87 axes in 29 conventional vehicles were measured, recorded, and analyzed. The mean deviation of the overall frequency-weighted vibration levels (Lw) and the greatest single one-third octave band frequency-weighted vibration levels (Lwi-max) in corresponding axes were statistically calculated. The results showed that the vehicle vibrations were broad-band vibrations. The mean deviation of Lw - Lwi-max is 6 dB. This article suggests a 6 dB value as an appropriate adjustment value for evaluating broad-band whole-body vibrations of vehicles when using the most sensitive limits given in International Organization for Standardization document 2631/1.

Acceleration↗
PubMed2003

Lasting amelioration of spatial neglect by treatment with neck muscle vibration even without concurrent training.

OBJECTIVE: It has been shown recently that neck muscle vibration in combination with an exploration training leads to lasting amelioration of spatial neglect. The present study evaluated whether vibration of the left posterior neck muscles alone has the potential to induce lasting reduction in spatial neglect. DESIGN: A multiple baseline design was used to control for spontaneous recovery or uncontrolled change caused by external events. PATIENTS: Six patients with spatial neglect following right hemisphere stroke. METHODS: Daily vibration treatment of the left posterior neck muscles for 20 minutes on 10 consecutive days. During vibration, patients did not perform any specific activities. RESULTS: We observed significant amelioration of spatial neglect after terminating the vibration therapy. The improvement was found to be stable at follow-up testing about 1.4 years later. CONCLUSION: Vibration of the left posterior neck muscles is a useful, non-invasive tool supplementing the established methods of spatial neglect treatment. It does not necessarily require the patient's co-operation, which is an important advantage especially in the early phases of rehabilitation.

Activities of Daily Living↗
PubMed2004

MoViES: molecular vibrations evaluation server for analysis of fluctuational dynamics of proteins and nucleic acids.

Analysis of vibrational motions and thermal fluctuational dynamics is a widely used approach for studying structural, dynamic and functional properties of proteins and nucleic acids. Development of a freely accessible web server for computation of vibrational and thermal fluctuational dynamics of biomolecules is thus useful for facilitating the relevant studies. We have developed a computer program for computing vibrational normal modes and thermal fluctuational properties of proteins and nucleic acids and applied it in several studies. In our program, vibrational normal modes are computed by using modified AMBER molecular mechanics force fields, and thermal fluctuational properties are computed by means of a self-consistent harmonic approximation method. A web version of our program, MoViES (Molecular Vibrations Evaluation Server), was set up to facilitate the use of our program to study vibrational dynamics of proteins and nucleic acids. This software was tested on selected proteins, which show that the computed normal modes and thermal fluctuational bond disruption probabilities are consistent with experimental findings and other normal mode computations. MoViES can be accessed at http://ang.cz3.nus.edu.sg/cgi-bin/prog/norm.pl.

Computational Biology↗
PubMed1989

A review of 132 consecutive patients referred for assessment of vibration white finger.

One hundred and thirty-two subjects were referred to the Institute of Occupational Health in Birmingham over a 2 year period for assessment as to whether they met the criteria for Prescribed Disease A11 (vibration white finger). A standardized questionnaire and checklist was used, and each patient with vibration white finger was staged according to the Taylor and Pelmear (1975) classification. One hundred and sixteen subjects (88 per cent) had a clinical picture consistent with a diagnosis of vibration white finger, of which 10 did not meet the DHSS criteria for prescription. For these 116 subjects, the mean age at initial occupational exposure to vibration was 27 years. The mean age when symptoms began was 40 years. Numbness was the most common symptom accompanying the periodic blanching. More claimants reported symptoms affecting their hobbies and social life than affecting their work. The main job activities that exposed these claimants to vibration were pedestal grinding, pneumatic chipping/grinding, and hand grinding. Different systems available for staging vibration white finger have inherent limitations, but a scheme that uses standardized objective tests will make the diagnosis and assessment less reliant on subjective symptoms alone.

Humans↗
PubMed1991

Ultrastructural changes in the dorsal root ganglion associated with whole body vibration.

Morphological changes were identified in dorsal root ganglion (DRG) neurons of rabbits exposed to whole body vibration. Light- and electron-microscopic analysis were carried out in six vibrated and four control animals. Analysis by light microscopy revealed DRG cells ranging from less than 20 mu to greater than 80 mu in diameter, with much less variation in nuclear diameter. Vibration had no effect on either cell or nuclear dimensions. There was no evidence of acute cellular injury in the vibrated specimens either on light or EM evaluation. However, mitochondria were increased 42% and lysosomes 33% in the vibrated specimens compared to controls. The incidence of nuclear membrane clefts was 2.70 per nucleus in control specimens and 3.74 per nucleus in vibrated specimens, an increase of 39%. These clefts were associated with numerous metabolic organelles, suggesting a relationship to cellular metabolism and, possibly, protein synthesis.

Animals↗
PubMed1996

Chest vibration redistributes intra-airway CO2 during tracheal insufflation in ventilatory failure.

OBJECTIVE: To determine if high-frequency external chest wall vibration added to low flow intratracheal fresh gas insufflation alters the intra-airway CO2 distribution and the resistance to CO2 transport from the lungs. DESIGN: Prospective study. SETTING: Experimental laboratory. SUBJECTS: Six adult anesthesized and paralyzed mongrel dogs (mean weight 24.3+/- 4.4 kg). INTERVENTIONS: Dogs were ventilated by three methods: a) intermittent positive pressure ventilation; b) intermittent positive pressure ventilation with tracheal insufflation of fresh gas (FIO2 of 0.4) flowing at 0.15 L/kg/min through a catheter positioned at the carina; and c) intermittent positive pressure ventilation with tracheal insufflation and with external high-frequency chest wall vibration of the dependent hemithorax. MEASUREMENTS AND MAIN RESULTS: We measured arterial blood gas values as an index of global gas exchange, and intrapulmonary airway CO2 concentrations as an index of local gas exchange. Intra-airway CO2 concentrations along the axis of the airways were measured via a sampling catheter. Airway axial concentration profiles were constructed and resistances to gas transport were calculated from the measured data. Vibration increased intraluminal CO2 concentrations from 1.1% to 2.5% mouthward of the insufflation catheter tip. Peak resistance to CO2 transport decreased by 65% during vibration relative to the insufflation-only value. Vibration displaced peak transport resistance from second- to fourth-generation airways. CONCLUSIONS: Global gas exchange improves during ventilation by chest wall vibration with low flow insufflation. Local gas exchange in the central airways is also improved due to increased intraluminal mixing and CO2 elimination. This ventilation technique may confer therapeutic advantages over conventional mechanical ventilation in the treatment of ventilatory failure.

Airway Resistance↗
PubMed1990

Bone vibrator placement and the cancellation technique.

An issue in the measurement of bone conduction sensitivity is the placement of the bone vibrator. The effect of bone vibrator position on the amplitude and phase of the received signal was investigated using a cancellation technique. This technique involves cancelling the signal delivered by the bone vibrator with a signal delivered acoustically via an earphone. At cancellation, the acoustic signal is equal in amplitude but opposite in phase to the bone-conducted signal. Results showed that the amplitude of the received signal did not vary significantly with bone vibrator position close to the center of the forehead whereas the phase of the received signal was critically dependent on bone vibrator position. Substantial intersubject differences were observed in the variation of phase with bone vibrator position. The precision of measurement using the cancellation technique was found to be high.

Acoustics↗
PubMed2002

Treatment of chronic lower back pain with lumbar extension and whole-body vibration exercise: a randomized controlled trial.

STUDY DESIGN: A randomized controlled trial with a 6-month follow-up period was conducted. OBJECTIVE: To compare lumbar extension exercise and whole-body vibration exercise for chronic lower back pain. SUMMARY OF BACKGROUND DATA: Chronic lower back pain involves muscular as well as connective and neural systems. Different types of physiotherapy are applied for its treatment. Industrial vibration is regarded as a risk factor. Recently, vibration exercise has been developed as a new type of physiotherapy. It is thought to activate muscles via reflexes. METHODS: In this study, 60 patients with chronic lower back pain devoid of "specific" spine diseases, who had a mean age of 51.7 years and a pain history of 13.1 years, practiced either isodynamic lumbar extension or vibration exercise for 3 months. Outcome measures were lumbar extension torque, pain sensation (visual analog scale), and pain-related disability (pain disability index). RESULTS: A significant and comparable reduction in pain sensation and pain-related disability was observed in both groups. Lumbar extension torque increased significantly in the vibration exercise group (30.1 Nm/kg), but significantly more in the lumbar extension group (+59.2 Nm/kg; SEM 10.2; P < 0.05). No correlation was found between gain in lumbar torque and pain relief or pain-related disability (P > 0.2). CONCLUSIONS: The current data indicate that poor lumbar muscle force probably is not the exclusive cause of chronic lower back pain. Different types of exercise therapy tend to yield comparable results. Interestingly, well-controlled vibration may be the cure rather than the cause of lower back pain.

Chronic Disease↗
PubMed2003

Whole-body vibration during manual wheelchair propulsion with selected seat cushions and back supports.

Although the exposure to whole-body vibrations (WBV) has been shown to be detrimental to seated humans, the effects of wheelchairs and seating systems on the transmission of vibration to an individual have not been thoroughly examined. The purpose of this study was to determine if the selected wheelchair seat cushions and back supports minimize the transmission of vibrations. Thirty-two wheelchair users traversed an activities of daily living course three times using 16 randomly selected seating systems as well as their own. Vibrations were measured using triaxial accelerometers at the seat and participant's head. The weighted fore-to-aft (Tx), vertical (Tz), and resultant (Tr) transmissibility based on the vibrational-dose-value (VDV) were used to determine if differences existed among the four seat cushions and back supports. The obstacles that seem to have the largest effect on the transmission of WBV are the single event shocks and the repeated event shocks. Comparisons between the individuals own seating system and the tested seating systems suggest that the individuals are not using the most appropriate seating system in terms of the reduction of vibration transmission.

Acceleration↗