Stabilisation times after transitions to standing from different working postures.

Transitioning to standing after maintaining working postures may result in imbalance and could elicit a fall. The objective of this study was to quantify the magnitude of imbalance using a stabilisation time metric. Forty-five male participants completed three replications of conditions created by one of four working postures (bent at waist, squat, forward kneel, reclined kneel) and three durations within posture.

New species in the Sitalcina sura species group (Opiliones, Laniatores, Phalangodidae), with evidence for a biogeographic link between California desert canyons and Arizona sky islands.

The western United States is home to numerous narrowly endemic harvestman taxa (Arachnida, Opiliones), including members of the genus Sitalcina Banks, 1911. Sitalcina is comprised of three species groups, including the monospecific Sitalcina californica and Sitalcina lobata groups, and the Sitalcina sura group with eight described species. All species in the Sitalcina sura group have very small geographic distributions, with group members distributed like disjunct "beads on a string" from Monterey south to southern California and southeast to the sky-island mountain ranges of southern Arizona.

Investigating gait adjustments and body sway while walking across wooden scaffold boards.

The flexible wooden boards are still being used on the scaffolds at some construction worksites in China. We examined if the board dimension, acclimation phase and construction work experience influence workers' walking strategies on these boards. Among the 40 construction workers recruited, half of them had more than 1 year of construction work experience.

Factors affecting time-to-contact calculations during quiet standing.

Time-to-contact (TtC) is an alternative measure of postural stability to center of pressure (CoP) velocity. TtC is based on both spatial and temporal aspects of CoP displacement, definition of the boundary shape, and quantity of minima analyzed. Three boundary shapes and three minima selection methods were used to compute TtC during bipedal quiet standing.

Methodological considerations of existing techniques for determining stabilization times following a multi-planar transition.

Postural stabilization is required following perturbations or after transitioning to standing. The current research evaluated two available algorithms that utilize within-trial data to quantify standing following multi-planar transitions. Forty-five participants began each trial by assuming a static forward kneeling posture that ended with an auditory signal prompting transition to standing.

Assessment of differenced center of pressure time series improves detection of age-related changes in postural coordination.

Center of Pressure (CoP) time series exhibit non-stationarity. Most CoP analyses assume a stationary signal, which could lead to measurement inaccuracy. Despite this, few researchers have reported the incidence of CoP non-stationarity or employed procedures to mitigate non-stationarity prior to time-series analysis.

Balance control during lateral load transfers over a slippery surface.

Few studies have measured balance control during manual material handling, and even fewer with environmental cofactors. This study examined the effect of different surface frictions during a stationary manual material handling task. Thirty-six healthy participants completed 180° lateral transfer tasks of a load over high- and low-friction surfaces (μ = 0.

Effects of common working postures on balance control during the stabilisation phase of transitioning to standing.

Standing after maintaining working postures may result in imbalance and could elicit a fall. The objective of this study was to assess the magnitude of this imbalance. Forty-five male participants completed three replications of conditions created by four static postures and three durations within posture.

The effect of load weight on balance control during lateral box transfers.

Few studies have endeavoured to measure balance control during manual material handling. This study examined the effects of load weight during a stationary manual material handling task. In total, 36 healthy participants completed 180° lateral transfer tasks of a loaded (5% of body weight) and an unloaded box.

Effects of simulated occupational task parameters on balance.

The effects of single-handed load holding, length of the base of support, and standing surface condition (narrow and wide construction beams) on balance were investigated in twenty-three healthy men between the ages of 18 and 55 years old. Balance during quiet standing was evaluated from postural sway measurements derived from center of pressure (COP) displacement. These measurements included the range or maximal displacement of the COP in the anteroposterior (AP) and mediolateral (ML) directions, the elliptical area, and mean sway velocity.

The anatomy of a slip: Kinetic and kinematic characteristics of slip and non-slip matched trials.

To improve understanding of slip propagation mechanisms, one could compare features of early stance phase during slips and non-slips. This study investigated the similarities and differences in kinematics and utilized COF of paired trials, defined as a matched pair of slip and non-slip trials produced by the same participant walking on the same floor condition at the same walking speed condition. Twenty-two participants produced 47 matched trial pairs while walking at 1.

Estimation of forces exerted by the fingers using standardised surface electromyography from the forearm.

Determination and integration of human force capabilities and requirements is an essential component of ergonomic evaluation. With regard to hand-intensive tasks, direct force measurements can be cumbersome and intrusive. Here, the use of surface electromyography (EMG) was evaluated.

Rearward movement of the heel at heel strike.

This paper describes the observation of rearward movement (RM) of the heel following heel strike occurring during normal gait. Thirty-one participants recruited as part of a larger study on slip kinematics walked the length of an 8-m runway at a speed of 1.5 m/s.

Association of subjective ratings of slipperiness to heel displacement following contact with the floor.

Falls precipitated by slipping are listed among the leading causes of occupational injuries. Several factors may influence the risk of slips and falls, including perception of surface conditions. The current research examined the relationship between perceptions of slipperiness and slip distance at heel strike.

The use of a heel-mounted accelerometer as an adjunct measure of slip distance.

A human-centered measure of floor slipperiness could be useful as an adjunct to conventional tribologic measures. This paper reports on the development and evaluation of a measure of slip distance based on variables derived from the signal of a heel-mounted accelerometer. Twenty-one participants walked on a laboratory runway under several surface slipperiness conditions at three walking speeds during a protocol designed to produce a wide range of slip distances at heel strike.

Measurement and prediction of single and multi-digit finger strength.

Hand and finger strength has direct application in the design of human-machine interfaces involving the whole hand or single digits. Limited finger strength data is available, however, particularly for practical situations such as pinching and poking. A study was conducted in which strength in a variety of couplings was collected from 100 participants, in order to enhance and supplement the existing literature.