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PubMed1987

Ergonomics and the effects of vibration in hand-intensive work.

Along with ergonomic factors, such as forceful and repeated exertion and certain postures, vibration has been cited as a factor of chronic nerve and tendon disorders such as carpal tunnel syndrome and tendinitis. The arguments for the contribution of vibration come from epidemiologic studies, clinical case analyses, and studies of short-term effects. It is well established that vibration stimulates muscle contraction, which is called the tonic vibration reflex. It is also known that vibration reduces tactility and that tactility affects the amount of force exerted to hold or manipulate a given object. For localized vibration exposure of the hand and arm to occur, the hand must grip a vibrating object. Vibration may increase the risk of chronic tendon and nerve disorders by increasing the force exerted in repetitive manual tasks. This close relationship between force and vibration, and difficulties in measuring force and vibration in manual work, makes it very difficult to determine their relative contributions in epidemiologic and clinical studies.

Carpal Tunnel Syndrome↗
PubMed1986

Chipping hammer vibration.

An investigation was carried out to determine the factors influencing the vibration of chipping hammers and to find ways of reducing the vibration at the operator's hand. It showed that substantially higher vibration levels are produced at the chisel of a chipping hammer than at its handle. Typical weighted values for the two areas were 24 and 8 m/s2, respectively. This finding agrees with medical observations showing that invariably the hand holding the chisel exhibits the more severe symptoms of vibration-induced white finger. A sleeve which fits onto the chisel was developed which can effect a reduction in vibration of up to 66%. A prototype hammer was developed incorporating an isolating material which reduced the weighted vibration value from 7 to 3 m/s2. Vibration isolating gloves were tested and resulted in an additional reduction in vibration of up to 63% when used with the chisel sleeve. A unique mounting device using rubber isolators was designed which protects the accelerometer from very intense high-frequency vibration but allows accurate measurement of chisel vibration in the frequency range of interest.

Equipment Design↗
PubMed2002

Frequency dependence of hand-arm vibration on palmar sweating response.

OBJECTIVES: This study attempted to elucidate the effects of hand-arm vibration frequency on palmar sweating response. METHODS: Palmar sweating was measured before and during vibration exposure on the right palm of six healthy men. The left hand was exposed for 3 minutes to the following root mean square (rms) acceleration magnitudes and frequencies of vibration: 5 m/s2 at 31.5 Hz, 10 m/s2 at 63 Hz, 20 m/s2 at 125 Hz, 40 m/s2 at 250 Hz, and 50 m/s2 at 315 Hz. According to international standard ISO 5349, these vibration levels generate the same frequency-weighted acceleration magnitude of 2.5 m/s2 rms. A control condition consisted of grasping a handle without vibration. As the index of the activated central nervous system, plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) was measured before and immediately after each vibration exposure. RESULTS: Each condition of vibration induced a palmar sweating response. Among the six vibration conditions, vibration of 125 Hz and 63 Hz caused large palmar sweating responses compared with those of 315 Hz andthe control condition. Plasma MHPG did not increase significantly after either vibrationexposure. CONCLUSIONS: The palmar sweating response to vibration with the same frequency-weightedacceleration magnitude suggested dependency on frequency. The study suggests that the somatosympathetic reflex is associated with different palmar sweating responses.

Adult↗
PubMed1975

The relative sensitivity of Renshaw cells to orthodromic group Ia volleys caused by static stretch and vibrations of extensor muscles.

1. Activity of Renshaw cells monosynaptically excited by ventral root stimulation and disynaptically excited by electric stimulation of the group Ia afferents in the gastrocnemius-soleus (GS) nerve, was recorded in precollicular decerebrate cats. The response of these units to prolonged vibration applied longitudinally to the deefferented GS muscle was then compared with that elicited by static stretch of the homonymous muscle, for comparable frequencies of discharge of the group Ia afferents. 2. Small-amplitude vibration of the GS muscle at 200/sec for one second produced a sudden increase in the discharge rate of Renshaw cells, which gradually decreased within the first 100 msec of vibration to reach steady albeit lower level than that obtained during the first part of vibration. The response of the Renshaw cells during the first 100 msec of vibration (phasic response) and that elicited during the last 500 msec of vibration (tonic response) were evaluated for different frequencies of sinusoidal stretch. The mean increase in the firing frequency per imp./sec in the Ia afferents was also calculated using the total one-second period. 3. The response of Renshaw cells to muscle vibration increased with the frequency of vibration and, over the value of 10/sec, appeared to be linearly related to the frequency of the input, at least up to the frequency of 150/sec. Since vibration was of sufficient amplitude to produce driving of all the primary endings of muscle spindles, the responses were expressed as mean increases in the discharge rate of Renshaw cells per average impulse/sec in the Ia afferents. The discharge of the Renshaw cell increased on the average by 2.90 and 1.08 imp./sec per each imp./sec in the Ia afferents during the phasic and the tonic component of the response respectively, while the response calculated during the whole period of vibration corresponded on the average to 1.45 imp./sec per each imp./sec in the Ia afferents. 4. The Renshaw cells tested above responded also with increasing frequencies of discharge to increasing levels of static extension of the GS muscle. In particular the discharge frequency of Renshaw cells was on the average linearly related to muscle extension, at least for values ranging from 0 to 8 mm. The mean increase in discharge rate as a function of the static extension corresponded on the average to 0.89 imp./sec/mm. Since the discharge rate of the primary endings of muscle spindles recorded from the deefferented GS muscle increased by 2.62 imp./sec/mm, it appears that the mean increase in the discharge rate of Renshaw cells as a function of static extension corresponded to 0.34 imp./sec per each imp./sec in the Ia afferents.

Action Potentials↗
PubMed2004

Microleakage and sealant penetration using a vibrating probe.

PURPOSE: To evaluate the effect of a vibrating probe on sealant penetration into pits and fissures. METHODS: Thirty-six extracted human third molars were used. The occlusal surface of each molar was cleaned with a rubber cup and pumice slurry. Scotchbond Etchant (35% phosphoric acid gel) was applied to the occlusal fissures of each molar for 20 seconds. Fissures were then sealed as follows: Group 1: Concise Light Cured White Sealant was applied without vibration; Group 2: same as in Group 1 but with vibration; Group 3: Single Bond Adhesive was applied, then Concise Light Cured White Sealant was applied without vibration; Group 4: same as in Group 3, but sealant was applied with vibration; Group 5: Concise Light Cured White Sealant was applied without vibration, then Z-100 composite was burnished over the sealant and light-cured; Group 6: same as in Group 5, but sealant was applied with vibration. Microvibe vibrating probe was used for sealant vibration. After 24-hour immersion in 2% basic fuchsin dye solution, specimens were sectioned, and dye and sealant penetration were scored using a stereomicroscope and color slides. Selected sectioned samples were observed under the SEM. RESULTS: No statistically significant differences between the groups were observed for either dye or sealant penetration scores. In all groups, sealant penetration was more influenced by the shape, depth and residual debris of fissures than by the use of a vibrating probe.

Acid Etching, Dental↗
PubMed1989

[Changes in the thermographic picture of hands of healthy persons after vibrations of 125 Hz].

The author investigated the effects of vibration, 125 Hz, on blood supply of hands in 43 healthy students. The temperature of fingers was followed by thermovision camera, the source of vibrations was a specially constructed vibration simulator which enabled to change vibration frequency. Thermographic recordings were made before the vibrations, immediately after the vibrations, 30 and 60 min. after the vibrations, respectively. Maximum temperature changes were always observed 60 min. after the vibrations. The temperature gradient 3-5 degrees C between the back of the palm and the fingers was demonstrated 60 min. after the vibrations in five healthy students (11%), although there was not any temperature gradient before the vibrations there. The negative finding lasted even in repeated examinations, the positive one was sometimes of different nature.

Body Temperature↗
PubMedDate not supplied

Effect of local vibration on ventilatory response to hypercapnia in normal subjects.

We studied the effects of local high frequency mechanical vibration on ventilatory (VE) and occlusion pressure (P0.1) responses to CO2 rebreathing in twelve normal subjects. Three kinds of vibration procedures were employed: a) sustained vibration over the tendon of the quadriceps femoris near the knee, b) sustained vibration of the right 2nd or 3rd parasternal intercostal spaces and c) 'in-phase' chest wall vibration applied during inspiration on the right 2nd or 3rd parasternal intercostal spaces and during expiration on the right 9th or 10th intercostal spaces anterior to the midaxillary line. The slopes of VE response to hypercapnia (delta VE/delta PETCO2) were 2.05 +/- 0.26 (mean +/- SE), 2.48 +/- 0.24, 2.82 +/- 0.32 and 3.35 +/- 0.38 l.min-1/mmHg in the control state, during tendon vibration of quadriceps femoris, sustained chest wall vibration and 'in-phase' chest wall vibration, respectively. This sequential increase in slopes was significant compared to the control values. The effect of vibration on the P0.1 response to hypercapnia was similar to that of VE. We conclude that local mechanical vibration facilitates responsiveness to hypercapnia.

Adult↗
PubMed2004

Vibrational center-ligand couplings in transition metal complexes.

The mode-tracking principle [J. Chem. Phys. 2003, 118, 1634] for the direct quantum chemical calculation of preselected, characteristic molecular vibrations makes vibrational analyses of very large molecules feasible. This is demonstrated here for the [(Ph(3)PAu)(6)C](2+) complex, in which 18 phenyl groups in the ligand sphere are explicitly taken into account. We are aiming at the motion of the endohedral carbon atom, which is in an extraordinary bonding situation because it is surrounded by an octahedral core of gold atoms in this cluster. Secondary effects of the full ligand sphere on the vibrations of the [Au(6)C] core embedded in [(R(3)PAu)(6)C](2+) clusters are investigated. For this purpose, local vibrations of the octahedral core are generated, and their long-range couplings with the phosphine ligand sphere become visible in the mode-tracking iterations. The exact normal modes of these characteristic vibrations of the cluster are then obtained after convergence of the mode-tracking refinement. This protocol allows us to assess the coupling of the outer ligand sphere with the inner core of the cluster in terms of changes of the vibrational frequencies and of the collective motions of the atomic nuclei. The vibrational frequencies of the octahedral [Au(6)C] core split due to symmetry breaking in the C(1)-symmetric [(Ph(3)PAu)(6)C](2+) cluster. Our study demonstrates how effects of the periphery of a large molecule on local vibrations can be quantified. Furthermore, we predict the first set of characteristic vibrational frequencies obtained with first-principles methods for this gold cluster, whose vibrational spectra have not yet been recorded experimentally.

Journal Article↗
PubMed1999

Head and Tail Deformations, Torsional Coriolis Coupling, and E(1d)-E(2d) Vibrational Mixing in Ethane-Like Molecules.

The mechanism of torsional Coriolis interaction of E(1d) and E(2d) vibrational modes in ethane-like molecules is investigated, and it is shown that this coupling can drastically affect the torsional splitting in the degenerate vibrational states. A basic point of our treatment is that the sets of coordinates of head and tail which combine with the + sign to generate E(1d) normal coordinates are in general different from those which combine with the - sign to generate E(2d) normal coordinates. It is shown that the zeta(gamma) torsional Coriolis coefficients calculated by the usual methods of normal mode analysis are related to the vibrational angular momenta within head and tail referred to the internal rotor axis systems. With knowledge of the L and L(-1) matrices it is possible to transform these coefficients for reference to the molecule-fixed frame. It is peculiar that torsional Coriolis matrix elements occur between E(1d) and E(2d) vibrational components with the same x or y orientation in the molecule-fixed frame. The matrix elements of the torsional Coriolis operator and other operators responsible for the end-to-end coupling are determined, and a method for calculating vibration-torsion energies, and then torsional splittings, in degenerate vibrational states is outlined. Detailed calculations require a global model, involving all the degenerate vibrational basis states in a complex mechanism of interactions, but it is shown that useful information can be obtained by means of simplified models. Our semiempirical rule that degenerate vibrational states with a large negative value of the diagonal vibration-rotation Coriolis coefficient are likely to deviate much from the behavior of E(1d) or E(2d) vibrational states, with a sensible decrease of the torsional splittings, is confirmed. Copyright 1999 Academic Press.

Journal Article↗
PubMed2005

Vibrationally resolved rate coefficients and branching fractions in the dissociative recombination of O2+.

We have studied the dissociative recombination of the first three vibrational levels of O(2) (+) in its electronic ground X (2)Pi(g) state. Absolute rate coefficients, cross sections, quantum yields and branching fractions have been determined in a merged-beam experiment in the heavy-ion storage ring, CRYRING, employing fragment imaging for the reaction dynamics. We present the absolute total rate coefficients as function of collision energies up to 0.4 eV for five different vibrational populations of the ion beam, as well as the partial (vibrationally resolved) rate coefficients and the branching fractions near 0 eV collision energy for the vibrational levels v=0, 1, and 2. The vibrational populations used were produced in a modified electron impact ion source, which has been calibrated using Cs-O(2)(+) dissociative charge transfer reactions. The measurements indicate that at low collision energies, the total rate coefficient is weakly dependent on the vibrational excitation. The calculated thermal rate coefficient at 300 K decreases upon vibrational excitation. The partial rate coefficients as well as the partial branching fractions are found to be strongly dependent on the vibrational level. The partial rate coefficient is the fastest for v=0 and goes down by a factor of two or more for v=1 and 2. The O((1)S) quantum yield, linked to the green airglow, increases strongly upon increasing vibrational level. The effects of the dissociative recombination reactions and super elastic collisions on the vibrational populations are discussed.

Journal Article↗
PubMed2003

Basic study on vibrations during tooth preparations caused by high-speed drilling and Er:YAG laser irradiation.

BACKGROUND AND OBJECTIVES: An Er:YAG laser effectively removes dental hard substance, and causes less pain during tooth preparations than high-speed drilling. This laser was introduced to eliminate the noise, vibration, pressure, and heat associated with the high-speed drilling. However, the difference in tooth vibration caused by the Er:YAG laser and the high-speed drill is unclear. Therefore, the aim of this study was to evaluate tooth vibration obtained with the Er:YAG laser and high-speed drill. STUDY DESIGN/MATERIALS AND METHODS: Each of the five extracted permanent upper first premolars were built up in a plaster box. In this study, a silicone impression material was selected to simulate periodontal tissue. The vibration speed was measured by using a laser Doppler vibrometer. RESULTS: The Er:YAG laser irradiation energy was 50, 100, 145, 199, 300, and 350 mJ. As irradiation energy increased, vibration of the tooth also rose; a high-correlation coefficient was observed between them. We found that only a small amount of the tooth vibration occurred with the Er:YAG laser preparations. The mean vibration speed and standard deviation with the laser were 166 +/- 28 microm/second when the output energy was 145 mJ, whereas those with the high-speed drill were 65 +/- 48 mm/second. The frequency characteristic approached 230 Hz and 5 kHz, respectively. CONCLUSIONS: These results show that the high-speed drilling causes greater tooth vibration and has a frequency spectrum near the high sensitivity of hearing compared to the Er:YAG laser. This suggests a potential factor in provoking pain and displeasure during tooth preparation. Future study to examine the relationship of pain and amount of tooth vibration will be planned.

Dental Instruments↗
PubMed2005

Neuropathological changes in vibration injury: an experimental study.

Vibration syndrome, a clinical condition arising from chronic use of vibrating tools, is associated with a spectrum of neurovascular symptoms. To date, only its vascular pathology has been extensively studied; we sought to determine what direct neurologic injury, if any, is caused by vibration. Hindlimbs of anesthetized rats were affixed to a vibrating platform 4 h a day for 7 days. Study animals were vibrated with set parameters for frequency, acceleration, velocity, and amplitude; control animals were not vibrated. On day 7, nerves were studied by light and electron microscopy. While light microscopy showed minimal histologic differences between vibrated (n=12) and control (n=12) nerves, electron microscopic changes were dramatic. Splitting of the myelin sheath and axonal damage (e.g., myelin balls and "finger ring") were consistently seen in both myelinated and nonmyelinated axons. Despite relatively short vibration, definite pathology was demonstrated, suggesting that vibration syndrome has a direct neurologic component.

Animals↗
PubMed2005

Vibration-induced disruption of retrograde axoplasmic transport in peripheral nerve.

Hand-arm vibration syndrome (HAVS) results from excessive exposure to hand-transmitted vibration. Whether the peripheral nerve damage characteristic of HAVS is a direct result of vibration or is secondary to vascular insufficiency remains unclear. The purpose of this study was to explore the effect of vibration exposure on axoplasmic transport in peripheral nerves and soleus motor neurons. Sciatic nerves and motor neurons from rats following two 5-h periods of vibration exposure demonstrated disruption in retrograde transport compared to normal. After 10 days of vibration (5 h/day), axoplasmic transport failed to recover within 24-48 h in most rats. This study demonstrates that disrupted axoplasmic transport is an early consequence of short-term vibration exposure. The effects of vibration on axoplasmic transport also appear to be cumulative. This study provides a new biological way to evaluate measures to prevent early vibration injury.

Animals↗
PubMed2005

Nifedipine pretreatment reduces vibration-induced vascular damage.

A rat-tail vibration model of hand-arm vibration was employed to test whether preemptive administration of nifedipine (5 mg/kg) to block vasoconstriction prevents vibration-induced arterial damage. The tails of vibrated and nifedipine-pretreated vibrated Sprague-Dawley rats were exposed continuously to 4 h of 60-HZ vibration at 49 m/s(2) rms. In nonvibrated anesthetized rats, the ventral tail arteries were bathed for 15 min in situ in 1 mM epinephrine or 1 mM norepinephrine to induce structural changes indicative of intense vasoconstriction. Arteries were processed for light and electron microscopy 45 min after treatment. Compared to sham control, 4-h vibration significantly (P < 0.01) reduced lumen size, generated endothelial disruption (7.0 +/- 2.6%), elevated nuclear factor of activated T cells c3 (NFATc3) expression in endothelial and smooth muscle cells, and increased smooth muscle cell vacuolization. The findings demonstrate that blockage of vibration-induced vasoconstriction with nifedipine prevents acute vascular damage. Smooth muscle and endothelial cells structurally altered by vasoconstriction are rendered susceptible to damage by vibration.

Animals↗
PubMed1984

Single and joint actions of noise and sinusoidal whole body vibration on TTS2 values and low frequency upright posture sway in men.

In the present study the changes in the TTS2 values and body upright posture sway were examined after exposure of subjects (n = 10) to stable broadband (white) noise (90 dB) alone, to sinusoidal vibration alone [directed vertically at the whole body (Z axis)], and to simultaneous exposure combinations of noise and vibrations of the same type. The frequency of the vibration was 5 Hz, but its acceleration was either 2.12 or 2.44 m/s2. There were six exposure combinations, and subsequently 60 tests were carried out in an exposure chamber. One test consisted of a control period of 30 min, of three consecutive exposure periods of 16 min each and of a recovery period of 15 min. After the three exposure combinations which included noise, half of the subjects were exposed to vibration during the recovery period. Apart from indicating an increase in the temporary hearing threshold, the results showed that simultaneous exposure to noise and vibration increases the instability of the body upright posture. The TTS2 values at the 4 and 6 kHz frequencies increased considerably more rapidly when the subjects were exposed simultaneously to noise and vibration than when exposed to noise alone. Without exception, the TTS2 values increased most during the first exposure period. It was noteworthy that exposure to vibration during the recovery period accelerated the recursion of the TTS2 values, especially in cases where the subjects had been exposed to noise alone. The variance of the body sway amplitudes and the standard deviation increased within the frequency range 0.063-2.000 Hz owing to noise alone and simultaneous noise and vibration. In the directions X and Y, within the frequency ranges 0.063-0.100 Hz and 0.100-0.600 Hz, the means of the maximum amplitudes of body sway increased especially in connection with those tests in which the subjects had been simultaneously exposed to noise and vibration.

Adult↗
PubMed1994

Prevalence of Raynaud's phenomenon in different groups of workers operating hand-held vibrating tools.

In eight groups of subjects operating various hand-held vibrating tools and aged from 30 to 59 years, the prevalence rates of vibration-induced white finger (VWF) and numbness, pain, or stiffness in the upper and lower extremities were investigated. Hand-transmitted vibration levels (HTVLs) were measured on the back of the hand, by means of unidirectional (x-axis) vibration dosimeters, and the frequency-weighted acceleration levels [(Lh,w)eq,t] were determined as the vibration levels. The prevalence rates of VWF and numbness of the hands in these subjects were compared to the prevalence rates of Raynaud's phenomenon (RP) and numbness of the hands in 1027 males and 1301 females not occupationally exposed to vibration (age range: 30-59 years). It was observed that in subjects exposed to HTVLs of between 1.1 and 2.5 m/s2, the prevalence of VWF was between 0.0% and 4.8%. The prevalence of VWF reached 9.6% in a group of workers exposed to HTVLs of 2.7-5.1 m/s2. The latter group showed a significant difference (P < 0.05) in the prevalence of VWF compared to the 2.7% prevalence of RP in male subjects of the general population. The prevalence of VWF in female subjects exposed to vibration (4.3%) was not significantly different from the prevalence of RP in females of the general population (3.4%). The prevalence rates of numbness of the hands were in the range of 6.5%-30.4% in the exposed groups and in the range of 13.4%-29.5% in the general population. Among the subjective symptoms, only VWF showed a significant positive correlation with HTVLs (R2 = 0.5, P < 0.05). It was concluded that in decisions concerning quantitative recommendations for vibration exposure, the prevalence of VWF should be employed. With a view to decreasing the risk of developing VWF, estimated vibration safety values for 4 h and 2 h daily exposures are discussed.

Adult↗
PubMed1993

Quantitative measurements of vibration threshold in healthy adults and acrylamide workers.

The early detection of impaired vibration sensation is necessary in order to monitor the adverse effects in workers occupationally exposed to neurotoxic chemicals such as acrylamide. The conventional neurological examination which assesses vibration sensation by utilizing a tuning fork is relatively insensitive for this purpose. In the present study, the Vibration II, a new device for the quantitative measurement of vibration thresholds, was used in 105 healthy Chinese adults. A new testing procedure combining the "two-alternative forced-choice procedure" and the "yes-or-no method-of-limits procedure" showed good reliability and was less time consuming. The results indicate that significant differences in the vibration threshold of index fingers and great toes were found neither between males and females, nor between the left and the right side. However, there was an age-dependent increase in vibration threshold in nonexposed healthy subjects. The vibration thresholds of 41 workers exposed to acrylamide detected by the Vibration II were significantly higher than those of the healthy adults in the same age group. The quantitative measurement of vibration threshold seems to be potentially useful for screening peripheral nerve dysfunction in field studies.

Acrylamide↗
PubMed2000

The mechanism of a human reaction to vibration stress by palmar sweating in relation to autonomic nerve tone.

OBJECTIVES: To clarify the mechanism of a human reaction to vibration stress by palmar sweating in relation to the autonomic nerve tone. METHODS: The autonomic nerve tone was divided into four types by using digital photoelectroplethysmography (PTG) with auditory stimuli: normal (N), hyperreactive (I and D), and hyporeactive (P) types. Palmar sweating and digital PTG were simultaneously measured on the right palm and middle finger, respectively, in 20 healthy men. The left hand gripping the handle with a grasp strength of 49 N was exposed to vibration at a frequency of 125 Hz and acceleration magnitudes of 0 m/s2 (as a control), 30 m/s2, or 50 m/s2 for 3 min. The volume of palmar sweating was recorded before, during, and 30 min after vibration load. Three kinds of drugs related to the autonomic nervous system were orally administered to the subjects. Then 80 min after administration, the experiments were repeated. RESULTS: Of 20 subjects, 17 showed normal autonomic nerve tone (N type), and 3 hyperreactive (I type). The palmar sweating reaction to vibration in I-type subjects was greater and lasted longer than that in N-type subjects. Vibration with an acceleration of 50 m/s2 produced the greatest reaction which was about 7 times larger than that at 0 m/s2 and 2.5 times that at 30 m/s2 (P < 0.01). Sulpiride decreased palmar sweating during vibration, while prazosin and scopolamine inhibited it. CONCLUSIONS: The palmar sweating reaction to vibration stress was related to the background level of the autonomic nerve tone. The sweating volume was in direct proportion to the acceleration magnitude of vibration. The reaction of palmar sweating to vibration stress may be mediated through both the adrenergic and cholinergic fibers of the autonomic nervous system.

Adrenergic alpha-Agonists↗