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By Kristine M. Krajnak

Occupational exposure to hand-arm vibration through the use of powered hand tools can result in reductions in tactile sensitivity, grip strength and manual dexterity. In fact, even acute exposures to vibration cause shifts in vibrotactile thresholds in exposed fingers (2,4,5). Although reductions in tactile sensitivity after acute vibration exposures are transient, cellular changes associated with this shift in sensitivity could lead to the more permanent reductions in tactile sensitivity that are a common symptom of hand-arm vibration syndrome (HAVS). Methods Animals. Male Sprague Dawley rats (6 weeks of age) were used for all experiments. Animals were housed in AAALAC accredited facilities, and all procedures were approved by the NIOSH Animal Care and Use Committee and were in compliance with the CDC guideline for care and use of laboratory animals. Vibration exposures were performed by restraining rats in a Broome-style restrainer, and securing their tails to the vibration platform using 6 mm wide straps that were placed over the tail every 3 cm. Restraint control animals were treated in an identical manner except that the tail platform was set on isolation blocks instead of a shaker. Tail temperature and current perception thresholds (CPTs). Rats were exposed to 4 h of tail vibration (125 Hz, 49 m/s2), or restraint. Tail temperature was collected prior to and immediately following the exposure using an infra-red camera. Sensory neuron function was assessed by measuring CPTs with a Neurometer (Neurotron, Baltimore, MD). Transcutaneous nerve stimulation was applied to the C10 region of the tail. Three frequencies were used to test specific fiber types (5 Hz – C, 250 Hz - Ad, and 2000 Hz – Aß). The intensity of the stimulus was automatically increased in small increments until the rat flicked its tail. Tests at each frequency were repeated until the animals displayed 2 responses that were within 2 CPT (or 0.02 mA) of each other (2-4 tests/animal). CPT tests were performed prior to the exposure, immediately following the exposure, and 24 h after the exposure. Data Analyses. Temperatures were analyzed using a one-way ANOVA with animal as a random variable. ANCOVAS were used to analyze the CPTs at each frequency. Temperature at the time of the CPT test was used as a covariate, and animal was used as a random variable Results Tail temperatures declined between pre and post exposure (F(1,25) = 62.85, p < 0.001; mean ± sem pre 25.96°C ± 0.42, post 20.71°C ± 0.77), but were back to baseline levels by 24 h after the exposure in both groups of rats. The ANCOVAs demonstrated that exposure to a single bout of vibration did not alter sensitivity of C (5Hz) or Ad (250 Hz) fibers to stimulation.

Jan 6, 2006

In 2005, a total of 739 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). These mines (e.g., potash, gypsum, salt) comprised 5.0% of all operations. ? Mines producing common clay comprised 26.9% (n=199) of all nonmetal mining operations. ? Nonmetal mining operations were located in all states and territories except Alaska, Delaware, Hawaii, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands.

Jan 1, 2008

The coal-bearing areas of Kansas cover approximately 18,800 square miles (23 percent of the state&apos;s total area). Coal in Kansas ranges from lignite to high volatile bituminous, located principally in the south-eastern part of the state. Kansas reserves are estimated to be 987,500,000 tons, approximately 0.2 percent of U.S. reserves. Coal beds generally occur in thin seams up to five feet thick. The overburden-to-coal stripping ratios in Kansas are among the highest in the nation, typically 20 to 1, with some ratios up to 35 to 1. The first commercial coal mining operation in Kansas opened in 1865 at Fort Scott in Bourbon County. As in other states, coal production in Kansas increased during the industrial revolution, and then fell as industry converted to alternative fuels. Production peaked in 1916 and 1917, with annual production of 7,250,000 tons. Coal production today is by surface mining methods. The Kansas regulatory program was approved April 14, 1982; the Abandoned Mine Land Program was approved February 1, 1982; and the emergency program authority was approved January 10,1989.

Jan 1, 1992

By Yagesh N. Bhambhani, Rammohan V. Maikala

Landstrom et al. (1985) suggested the possibility of cortical activation during exposure to WBV, however, it is not known how cerebral physiology (oxygenation and blood volume) responds in healthy women during different vibration frequencies. This study examined the role of backrest support and handgrip work on cerebral oxygenation and blood volume responses, during exposure to seated WBV. Methods Fourteen women (age: 23.9 ± 3.5 years) were randomly exposed to three frequencies of WBV (3, 4.5 and 6 Hz at approximately 0.9gr.m.s in the vertical direction) on a customized vibrating base (Advanced Therapy Products, Inc., USA) in a seated posture on three separate days. On the first day, the subjects completed an aerobic fitness test until volitional exhaustion on an arm cranking ergometer (Cybex, MET 300, USA). Each WBV session lasted 30 min (6 min baseline without WBV, 8 min WBV ‘with’ or ‘without’ backrest support, and 4 min recovery from WBV, 8 min WBV with ‘opposite’ backrest condition, and 4 min recovery following WBV). During 8 min WBV exposure ‘with’ and ‘without’ backrest support, subjects performed maximal voluntary rhythmic handgrip contractions with their right hand for 1 min using a dynamometer. To obtain regional oxygenation and blood volume responses, a NIRS sensor (MicroRunman, NIM, Inc., PA, USA) was placed on the anterior right frontal lobe just below the hair and close to fronto-temporalis region (Maikala et al. 2005). Results Baseline oxygenation and blood volume values were recorded during recovery from each WBV session of ‘with’ and ‘without’ backrest support. The physiological change in oxygenation and blood volume during each frequency (3, 4.5, and 6 Hz) for both backrest (‘with’ and ‘without’ a backrest) and workload (WBV only and WBV combined with rhythmic handgrip contractions) was calculated as the difference between the maximum values identified for each WBV condition of backrest and workload and baseline values (Maikala et al. 2005). Three-way analysis of covariance with repeated measures (frequency, backrest, and workload) with a fully crossed design was used to evaluate the differences in the oxygenation and blood volume responses (measured in optical density [od] units). Peak oxygen uptake during

Jan 6, 2006

The concept of isokinetic measurement of strength was originally related by Hislop and Perrine.(1)Characteristics of an isokinetic exertion are constant velocity throughout a predetermined range of motion. Strictly speaking, a means of speed control, and not a load in the usual sense, is applied in isokinetic exertions.(1)However, load and resistance are definitely present in this technique. In this case, the load is a result of the energy absorption process performed by the device to keep the exertion speed constant. The device prevents energy from being dissipated through acceleration in isokinetic exercise. The energy is instead converted into a resistive force, which varies in relation to the efficiency of the skeletal muscle. Since the speed of motion is held constant in isokinetic exercise, the resistance experienced during a contraction is equivalent to the force applied throughout the range of motion. For this reason, the technique of isokinetic exercise has sometimes been referred to as accommodating resistance exercise. This type of exercise allows the muscle to contract at its maximum capability a tall points throughout the range of motion. At the extremes of the range of motion of a joint, the muscle has the least mechanical advantage, and the resistance offered by the machine is correspondingly lower. Similarly, as the muscle reaches its optimal mechanical advantage, the resistance of the machine increases proportionally. It must be understood, however, that while isokinetic devices control the speed of the exertion, this does not assure a constant speed of muscle contraction. The speed of isokinetic contractions is constant during individual exertions; however, it is also possible to compare muscular performance over a wide range of isokinetic velocities. Increasing the isokinetic speed of contraction will place increasing demands on Type II muscle fibers (fast twitch and fast oxidative glycolytic). Workplace Assessment It is clear that isometric strength testing cannot substitute for dynamic strength assessment when examining highly dynamic occupational job demands. As most industrial work tasks contain a significant dynamic component, analysis of isokinetic strength capabilities appears to offer some advantage to isometric testing in this regard. However, it must be recognized that isokinetic devices are not entirely realistic compared with free dynamic lifting in which subjects may use rapid acceleration to gain a weight-lifting advantage.

Jan 1, 1998

By M. A. Trevits

During the time period from 1990-2007, 1601 reportable fires occurred in the U.S. mining industry (an average of 89 fires per year). The leading causes of U.S. mine fires were flame cutting and welding operations, frictional heating and ignitions, electrical shorts, mobile equipment malfunctions, and spontaneous combustion. The fact that mine fires continue to occur with an alarming regularity reinforces the importance of recognizing and eliminating the potential hazards and the overall need for improved fire control and suppression technology to ensure the best possible outcome during a mine fire. The National Institute for Occupational Safety and Health (NIOSH) is conducting an evolving comprehensive program of research that is addressing mine fire prevention, detection, management and suppression. This paper presents a summary of recent research accomplishments and provides an overview of the next phase of the NIOSH mine fire research program.

Jan 1, 2008

By R. H. Grau, S. B. Robertson, J. Dolgos, T. P. Mucho

The National Institute for Occupational Safety and Health (NIOSH) has developed a computer program called the Air Quantity Estimator (AQE). The purpose of the program is to provide a starting point for estimating the air quantity needed to dilute diesel particulate matter (DPM) in an underground large opening mine, albeit taking into account various input assumptions. The AQE estimates the total air quantity needed to dilute DPM emissions that enter the main airstream of the mine to current statutory levels. It helps operators pinpoint vehicles that are high DPM contributors. In addition, it allows the user to make “what if” scenarios by varying the input parameters to achieve the most efficient and practical ventilation system. The AQE is a stand-alone software program that does not require any type of spreadsheet software. Engine data must be known or estimated with some accuracy and assumptions must be made in order to limit the variability of the program output. Program calculations and two case studies, for validation purposes, are included in this report. It should be noted that the program does not ensure adequate face ventilation and personal exposure compliance.

Most laboratory sealant studies were carried out in 2.0 inch I.D. Plexiglas tubes of 9.0 inches height containing 4.0 to 4.5 inches reconstructed soil from an 0-8 or 8-16 inch soil horizon at the Lanse site. (When soil was used from the Kato site, the top soil horizon was approximately 0-4 inches. The 4-8 inch horizon was somewhat comparable to the Lanse 8-16 inch horizon.) A 20 mesh Saran or steel screen was placed over the rubber stopper with a bottom drain to a 100 ml measuring cylinder. In some earlier experiments a 1/2 inch bed of 1/4 inch pea-gravel was then added, but in later experiments this was eliminated as it showed no particular utility. Field soil samples collected by a shovel were stored in sealed containers and sieved through a 4 mesh screen just before use. (Moisture content was typically about 25% for A horizon soil and about 20% for B horizon soil.) The sieved soil minus roots was then added in increments of about 1 1/4 inches. Compaction was effected by dropping a weighted ramrod (1-7/8 inches O.D,) five times from a height of two inches. If about twenty tamps were used or if the soil columns were rapped vigorously while water-logged, compaction was high with no detectable percolation. Freezing such samples would then usually cause very slow percolation, e.g. 1-2 ml/day. Using this as a standard procedure, percolation flows were usually stablized after two to three days to rates of about 100 to 200 ml/hour. Percolate was recycled carefully to minimize disturbance of the soil surface. When percolation flows were about 100 to 200 ml/hour, various additives (sealants) were introduced to the moist column in two to three increments to maintain a slight head. Additive concentrations were usually 2-1/2% with some at 5% in earlier experiments. Typical use of 40 ml of 2-1/2% additive corresponds to 4400 lbs/acre. When no more additive was present as supernatent liquid, water washes of about 15 ml were then used several times followed by special additives as needed. More water washes were then used to maintain a head of about 1/2 inch. Percolate was collected in 100 ml cylinders to measure percolation rates in ml/hr. Turbid percolate was evaporated to determine amount of eluted latex. Percolate was sometimes checked for pH by Pan-pH Indicator Paper9,10 reading in 0.5 units. Surface tension measurements were sometimes made by a DuNouy tensiometer10 in experiments using a surfactant for pretreatment.

Jan 1, 1972

By Bernadette C. Michalski

THE RAPID GROWTH of the small Albanian mineral industry in the 1950&apos;s began to taper off by 1961 and slackened sharply in 1963. The abandonment of Soviet and East European technical assistance programs in mid-1961 greatly affected Albania&apos;s mineral development, since four-fifths of all technical aid personnel were engaged in mineral activities. Chinese assistance apparently has not been able to fill the void. Overall mineral production increases during 1961-63 averaged 1 percent per year in value, as compared with 3 percent in 1959 and 5 percent in 1960. Although by world standards Albanian mineral output, except for chromite, is insignificant, it is vital to the country&apos;s domestic economy. The mineral industry generated about 14 percent of the gross industrial product in 1962 and employed a notable share of the industrial labor force. In recent years, mineral products have provided about three-fifths of the country&apos;s exports by value. Chromite and iron-nickel ores together constituted from one-fourth to one-third of the total export value. In 1963, total trade turnover increased 12 percent over 1962.

Jan 1, 1964

Several primary ingot producers have introduced price changes for July. Howmet Aluminum Corp., Revere Copper and Brass, Inc. and the Anaconda Co, will increase late-July prices of 99.5 percent unalloyed aluminum ingot by 3 cents to 56 cents per pound, Prior to this, Kaiser Aluminum and Chemical Corp. had advanced June ingot values by 4 cents to 57 cents and Consolidated Aluminum Corp., 4.5 cents to 57.5 cents. Domestic merchants held June quotes at a range nearing 50-50.8 cents per pound. ANTIMONY Although NL Industries, since April of this year, stopped publishing prices for RMM and Lone Star antimony grade, values of domestically-refined antimony in alloy are being made available to industry, The current price of this material is $1.75 per pound of antimony contained in alloy, New York dealer-marketed metal was available in June at $1 -13-$1 .20 per pound. Important industrial uses of antimony are for flame retardants, storage batteries, chemicals, pigments, rubber, plastics, glass, ceramics and machinery.

Jan 1, 1978

By S. H. Ash

The Pennsylvania anthracite region is composed of four fields, namely, the Northern, Eastern Middle, Western Middle, and Southern. It is in the eastern part of Pennsylvania and is shown on figure 1. The anthracite industry is confronted with a crucial problem of inundation by water impounded in underground pools in many mines and by infiltration of water from streams and pools on the surface (3). The deposits of anthracite in the United States are limited virtually to Pennsylvania, and the difficulties of this industry have been commonly considered as a State problem rather than a national one (1, 4, 6, 7). Anthracite was discovered in Pennsylvania in 1762, and the first mining company was formed in 1793. It was not until 1812 that anthracite began to receive recognition in the Philadelphia market as a domestic fuel, and by 1838 the annual production was nearly 1 million net tons. Since anthracite mining began, mine water has become progressively more difficult and costly to handle because of the extraction of anthracite both underground and along the outcrops of the beds, until at the present time mine drainage is a major anthracite-mining problem. Mine water is handled at the anthracite mines as follows: (a) by pumping, (b) by drainage tunnels, (c) by combination of pumping and drainage tunnels, and (d) by water hoists (hoisting water by means of large buckets) (4, 5,6, 7). This paper covers removal of the water from mines by means of pumping plants. Pumping is indispensable in the production of anthracite (5). The cost of pumping mine water has increased progressively since anthracite mining began. Some collieries have been forced to discontinue mining because of the high cost of pumping.

Jan 1, 1950

By E. Robert Ruhlman

["Phosphate rock" is a broad term applied to natural deposits of minerals valued chiefly for their phosphorus content. More specifically, phosphate rock may be defined as a natural rock containing one or more phosphate minerals, usually calcium phosphate, of sufficient purity and in sufficient quantity to permit its use directly, or after beneficiation, in the manufacture of phosphorus-bearing products. The grade or quality of phosphate rock is expressed either in terms of its phosphorus oxide (P20S) content or the equivalent in tricalcium phosphate (Ca3(P04)2). The trade name for tricalcium phosphate is bone phosphate of lime (B. P. L.).]

Jan 1, 1958

By J. D. Davis

"Introduction.Sixty years ago, M. Berthelot found that ethylene could be selectively absorbed from gaseous mixtures by concentrated sulphuric acid, and that the compound formed by the chemical union of the gas and acid was readily decomposed by heating with water, yielding ethyl alcohol. Only within the last few years has there been any attempt to make use of this discovery technically.Bury*, working in England at the Skinningrove Iron Works and on a commercial scale, developed a technical method for converting, the ethylene of coke-oven as into alcohol. With a gas containing less than 3 per cent of ethylene, he obtained a yield of 1.6 gallons of alcohol per ton of coal carbonized.De Loisy** perfected a technical method for treatment of coke-oven as for alcohol. Evidently this work was carried out on a semi-commercial scale. His method is based on the use of catalytic agents for hastening the absorption of ethylene by sulphuric acid. He uses part of the spent acid for drying the gases and pact for the manufacture of ammonium sulphate. Excess acid is reconcentrated by waste heat. Others have worked on the problem, but so far there has been no large recovery of ethylene from coke-oven gases. The chief difficulty seems to lie in the low efficiency (about 50% of methods and tae relatively low concentrations of ethylene in the gases treated. Gas from Trent amalgam*** contains much larger percantages of ethylene than does coke-oven gas, as Will presently be shown, and if it should ever prove practIcal to treat industrial ;as for alcohol, this gas would offer attractive possibilities,* Bury, Ernest, Ethylene as Alcohol from Coke-Oven Gas: Gas Journal' Vol. 148, D. 30, 1919, pp. 718.** DC Loisy, M.E., Sur un procede' industrial de fabrication syntlotique de l'alcool et de l'ether a partir des gaz de distillation de la houil Comp Rend, vol. 170, Jan. 1920, p. 50-3.*** A paste consisting of approximately part oil such as that obtained as for cleaning coal. See Perrott. in cleaning coal, Chem 3 parts finely pulvarized coal and 1 final product in the Trent, process StJ, and Kinney, S.P. The use of oil Vol. 35 August 3, 1921, p, 183.. & Met."

Nov 1, 1922

By Naoki Hosoya, Setsuo Maeda

This paper addresses establishment of an experimental system for measuring biodynamic response (BR) of hand-arm system at the NIIH in Japan. BR measurement system at the NIIH is nearly equivalent to NIOSH installed system. The feasibility of the system is examined through the apparent mass (AM) measurement of the empty handle and a set of calibration masses. Apparatus The grip force was measured by using the handle shown in Fig. 1. The handle has two force sensors (KISTLER, 9212) and one accelerometer (PCB, 356A12). A low-pass filter with 5 Hz cut-off frequency was used to the grip force from measured force signal. Figure 2 shows BR measurement system in this study. The push or pull force at the handle was measured by using the force plate (KISTLER, 9286AA). The grip force and the push / pull force were displayed on a monitor. The shaker (IMV, VE-100S) is used to vibrate the hand-arm system along the forearm axis (Zh direction) (ISO 10068, 1998; ISO 5349-1, 2001). In most situations force actions for operating tools are expressed by grip, push, pull and combined these actions. These actions can be simulated in the test system. AM was obtained by performing H1 estimator in the PULSETM system (B&K, 3109) and it is denoted at the one-third octave band center frequencies. [ ] Methods In order to investigate the reliability of the system, AM measurement of the handle was performed. It is assumed that the handle is rigid in the upper limit of adoptive frequency range in this study. This assumption is validated in AM measurement of the empty handle. A pseudo-random vibration in the frequency range of 10 to 1,250 Hz was used and its amplitude is 1.0 (m/s2)2/Hz with a flat power spectral density (PSD) in the experiment. Measured AM includes the mass effect of the measuring cap in a subject experiment. Compensated apparent mass AMc(?) is obtained by Eq. (1) 1-2.

Jan 6, 2006

By E. V. Cilento, K. A. DiGregorio, R. C. Lantz

Pulmonary inflammation is accompanied by increased microvascular permeability and leakage of plasma into alveolar spaces. Serum has been shown to affect superoxide (O2-) production from pulmonary alveolar macrophages (PAM) in vitro, and in some cases serum has been shown to be necessary for stimulation of PAM. An electro-optical method was used to measure O2- production from single PAM by measuring the reduction of nitroblue tetrazolium (NBT) to a diformazan precipitate (NBTH2) from videorecorded images of individual cells. PAM were stimulated by their initial attachment to culture dishes independent of serum. The addition of 2% serum to the culture medium increased NBTH2 production during attachment, whereas concentrations of 5 and 10% serum had no additional effect. In contrast, PAM incubated for 2 hrs could not be stimulated by phorbol myristate acetate (PMA) or zymosan particles to produce O2- unless serum was present during the incubation and/or stimulation; however, NBTH production was similar in all cases of serum addition. Also2, serum alone did not stimulate adherent PAM indicating that serum is necessary but not sufficient for stimulation of attached. PAM. These results suggest that changes in microcirculatory permeability may have a pronounced effect on superoxide production by PAM and that serum may help regulate or condition these cells during inflammation of the lung. (Supported by USBOM Gll35142.)

Jan 1, 1988

By L. Nahai

COAL, salt, lapis lazuli, and construction materials such as lime, gypsum, slate and stone were the only mineral commodities produced in Afghanistan during 1963. Beryl has been produced sporadically. Small deposits of chromite and lead-zinc are known but remained unexploited because there were no domestic markets for the two commodities and transportation costs from Afghanistan to world markets were too high. Oil fields of sufficient magnitude to justify exploitation have not been discovered, but known natural gas reserves are substantial and have potential significance. There is evidence of large high-grade iron ore resources, but these are in an unfavorable location. The contribution of the mineral industry to the economy was small, although precise figures are not available. The reported value of mineral production in 1963 (excluding barite) was 181.6 million afghanis (about US$4 million). Employment in the industry, including cement plants and quarries, was estimated to be no more than about 2,000.

Jan 1, 1964

In the interest of safety in underground coal mining, the Bureau of Mines recommends: 1. That doors used to control ventilation (a) Shall be installed in pairs to form air locks, (b) Shall be self-closing, (c) Shall not have latches or other devices for holding them open, (d) Shall be constructed and maintained to prevent excessive air leakage through or around them, (e) Shall be fire resistant. 2. That wherever practicable the use of doors shall be limited to development openings. The Mine Safety Board is of the opinion that the best practice in coal-mine ventilation makes use of a split system employing overcasts or undercasts with doors limited as far as feasible to development openings. The distance between air-lock doors on haulageways should be sufficient to accommodate a trip or train of maximum length. Where auxiliary doors are installed to control ventilation during emergencies, they should be so placed that they can be utilized readily in case of damage to the air-lock doors.

Jan 1, 1938

By Joseph Gersic

The U.S. Bureau of Mines assessed mineral resources of the BLM Malheur-Jordan Resource Areas (MJRAs) in southeastern Oregon in 1993 and 1994. The study relied heavily on acquiring and analyzing existing data. In order to efficiently handle and analyze a large quantity of data, a minerals information management program, informally called MINFO, was developed as a frontend for three databases created to store basic information gathered during the minerals resource assessment. The MINFO program will also provide the BLM with a method of tracking and updating minerals information in the future because program modules in MINFO allow the addition of new data and the correction of errors, creation of print files, transfer of data to other database formats, exportation of data to other software packages, and creation of AutoCAD script files to be used in conjunction with AutoCAD to produce maps. The report specifically identifies significant past and present mineral exploration and development activities and possible areas of future mineral exploration and development. These areas are informally designated as areas of development interest or ADIs. The report contains a scenario of what mineral development might reasonably occur in the foreseeable future if the BLM does not substantially change its present resource management plan, and it shows the possible socioeconomic impacts of that development. The uncertainty of the political and economic situation makes it extremely challenging for the USBM to accurately predict a reasonably foreseeable development scenario. The reasonably foreseeable development (RFD) scenario developed by the USBM for the BLM indicates short-term RFD of minerals should have a negligible socioeconomic impact, and longer-term RFD of minerals should have a slight socioeconomic impact on the MJRAs. The mining industry is facing a rapidly changing business and regulatory environment in Oregon. Several signal changes have occurred recently, including State regulations that require significant bonding prior to the startup of "chemical process" mining, an initiative by a special interest group to stop all chemical process gold mining within the State, and an opinion by the Oregon Attorney General (AG) banning all forms of placer mining without exemption. In the AG opinion, not even gold panning is allowed, and the prohibition applies to mining claims on Federal lands. The State legislature may amend the statute to allow small scale placer mining to occur, as was allowed under an AG opinion issued in 1982. These and other changes occurring at the local, State, and National levels are making it more challenging for the mining industry to operate in the United States. Several epithermal gold properties in the MJRAs attracted the mining industry&apos;s interest. Only the Grassy Mountain Project of Newmont Grassy Mountain Corporation may be developed in the next few years. It is probable that at least two other properties will be developed if Grassy Mountain is successful. Mining companies are waiting to see the effect recently promulgated State mining regulations and more stringent proposed regulations, particularly bonding regulations, may have on Grassy Mountain. Resources of bentonite, diatomite, and zeolite are abundant. The almost Ubiquitous stone, sand and gravel, and semiprecious gemstone resources also were examined. Little environmental or socioeconomic impact is expected from reasonably foreseeable development of these mineral resources.

Jan 1, 1994

By Danny Riley, Brian Curry, Sandya Govindaraju, James Bain

Hand arm vibration syndrome (HAVS) affects industrial workers exposed to long term hand-transmitted vibration from powered-tools. Peripheral neuropathy is a major component of the symptom complex of HAVS. Long term exposure to vibration causes myelin damage in peripheral nerves and reduces nerve conduction velocities in rats1. This study addresses the effects of acute vibration at constant acceleration of 49 m/s2 on myelinated fibers in peripheral nerves in Sprague-Dawley male rats using the ‘rat-tail vibration model,’ which simulates hand-transmitted vibration2. Methods Male Sprague-Dawley rats (~300 g) were assigned to vibration groups: 1 hr continuous vibration at 60 Hz; 4 hr continuous exposure at frequencies of 30, 60, 120 or 800 Hz; immediate and 24 hr following a 4-hr cumulative exposure of continuous and intermittent vibration at 60 Hz. Unanesthetized rats were restrained in cages on a nonvibrating platform with their tails placed on a vibrating stage accelerated by a B&K motor type 4809 and vibrated. Intermittent vibration was delivered in bouts of 10 min vibration alternating with 5 min rest periods repeated over 6 hr. Sham controls were restrained without vibration. After vibration exposure, the rats were anaesthetized, and the ventral nerve trunks from the proximal tail segment 7 were fixed in glutaraldehyde, embedded in epon-araldite and sectioned at 0.5 µm thickness and stained with toludine-blue for morphological quantitative analysis. The total number of myelinated axons in each cross-section of the nerve was counted using the Image J software. Myelin damage was identified by focal increase in area and intensity of toludine-blue staining and unraveling of the myelin sheath. Statistical analysis for comparing sham and the different vibration groups was done using Dunnett’s test. Animal treatment and all surgical procedures were approved by the institutional review board and compiled with the Laboratory Animal Welfare Act. Results The rats tolerated continuous vibration very well and exhibited no behavioral signs of stress. When exposed to intermittent vibration, there was increased vocalization, a startle reflex at the beginning of each bout of vibration, deposition of porphyrin around the eyes and transient hypersensitivity to touch.

Jan 6, 2006

By P. -E. Boileau, P. Marcotte, Y. Aldien, S. Rakheja

A number of biodynamic models of the hand-arm system have evolved on the basis of measured driving-point mechanical impedance (DPMI) responses to facilitate analyses of the coupled hand-tool system [1]. The parameter identifications in such models are based upon minimization of an error function of the model and the target impedance data, which may not yield a unique solution. Consequently, a number of model structures and parameter sets could be realized that would equally satisfy the target curve. Moreover, the vast majority of the reported models exhibit acute deficiencies due to excessive static deflections of model masses, presence of a low frequency mode and very light masses in the order of 1.2- 4.8 grams. The models also do not characterize the dependency of the biodynamic responses on many factors, namely the hand forces, hand-arm posture and vibration intensity. This study aims at development of a hand-arm biodynamic model with considerations of the hand forces, and both the DPMI and power absorption measures, to enhance the uniqueness of the model. Methods Two different model structures are chosen for identifying the model parameters on the basis of measured DPMI and absorbed power characteristics of the hand-arm system under zh-axis vibration over a range of hand-grip and push forces. Owing to the strong influence of the hand-handle coupling forces, the models were initially derived for fixed hand forces, namely 30 N grip and 50 N push forces, as suggested in the ISO 10068 standard [2]. The equations of motion for the model are formulated and solved to compute both the DPMI and absorbed power responses. A constrained minimization function comprising weighted errors of both the DPMI and absorbed power is formulated and solved to identify the parameters. Alternate functions corresponding to different combinations of hand forces are then applied to identify hand-force dependent model parameters. Variations in the model parameters are investigated as functions of the grip, push and coupling forces through linear regression analysis. Regression-based models are formulated for deriving the hand-handle forces dependent model parameters. The validity of the model is also examined under selected combinations of hand forces. [ ]

Jan 6, 2006