RESUMEN

With the goal of facilitating the creation of relaxing sound environments in stressful places, such as offices, we examined differences in the heart rate fluctuations of men and women induced by different sounds. Twenty-three healthy students (13 males and 10 females) aged between 18 and 23 listened to seven different sounds while we collected electrocardiogram data. We extracted the high frequency component (HF) and low frequency component (LF) of the signals using the wavelet method, and calculated LF/HF. We found no statistically significant differences between males and females in the frequency distribution of a no change group, increased group, and decreased group for any sound. However, certain sounds had somewhat similar patterns for men and women for all three groups. Additionally, the pairs of experimental sounds with highly similar effects on individuals were different for men and women.

Asunto(s)

RESUMEN

This study analyzed the perceived attention represented by "gazing" points of cyclists to expose a latent accidental factor hidden in cyclist behaviour. Eleven elderly people and 23 young people equipped with an eye camera participated in the study. From the camera images, the objects viewed by the cyclists were analyzed. A main road and a community road were used in the experiment. The objects viewed by the cyclists were categorized into nine items that would be indirectly related to the cause of bicycle traffic accidents: gates and porches, parking lots, signals, alleys, other bicycles on the road, pedestrians, signs and painted symbols on the road, schoolyards and houses, and other items. The results of the study indicated that many elderly cyclists always confirmed their safety at alley intersections along both main and community roads, whereas many young people were not so dutiful. The results for unsafe gazing behavior such as looking at a schoolyard or house while cycling were the same for the two groups in that most individuals did not look away from the road while cycling along the main and community roads. Dissimilar results, especially those for alley intersections, resulted from young people not paying due attention to objects, suggesting that such gazing behaviour could be strongly related to traffic accidents involving a bicycle.

Asunto(s)

RESUMEN

The aim of this study is to recommend revisions, based on empirical data, to the current curb ramp standards for keeping bicyclists safe. Four types of curb ramps were tested: (1) concrete with a 50 mm edge height, (2) concrete reinforced by a metal plate with a 50 mm edge height, (3) plastic with a 20 mm edge height, and (4) recycled rubber with a 10 mm edge height. Twenty subjects aged 20-60 years ascended the curbs on a bicycle under various conditions. The angles of approach were 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees and 90 degrees. Experiments were executed under both wet and dry conditions. We found that when approaching from an angle of 45 degrees or more, all subjects could ascend all ramps under both conditions. From a 15 degrees approach under wet conditions, no subjects ascended the concrete ramps. Some could not ascend at a 15 degrees approach on the concrete ramps in dry conditions, and some could not ascend from a 30 degrees approach on the reinforced concrete ramp in wet conditions. Bicyclists riding on roadways cannot easily ascend a curb ramp with a 50 mm edge, even in dry conditions. We thus recommend that curb ramp edge heights be lower than 50 mm. Keywords: friction coefficient; approach angle

Asunto(s)

RESUMEN

The purpose of this research is to examine the ways bicycles swerve off sidewalks onto roads under various conditions. Seven students, five males and two females participated in an experiment on a road with a 100-cm wide sidewalk. Footage of each participant on a bicycle evading obstacles such as a utility pole and pedestrian were taken with a video camera, while a front-wheel view of the path taken by the bicycle was recorded simultaneously with a digital camera. Twelve experimental conditions were used for each participant, consisting of all the combinations of (1) three obstacle types, (2) the side (left or right) to which the bicycle went to avoid the obstacle, and (3) two weather conditions. Based on the two recorded scenes, the path was then analyzed from the viewpoint of how the bicycle swerved to avoid hitting the obstacle. We found that the conditions of riding a bicycle with an umbrella caused a larger swerve to avoid the obstacle than those conditions when the rider did not have an umbrella. In particular, the condition in which the obstacle was a pedestrian who also had an umbrella caused the largest swerve. Furthermore, the distance required to become aligned with the sidewalk when the obstacle was a pedestrian walking toward the cyclist was longer than that for other obstacles. The swerve width data showed interesting results, including a tendency for swerve width to be wider when the obstacle was a utility pole compared with other obstacles.

Asunto(s)

RESUMEN

The purpose of this study was to identify the effect of bus passengers' positions on their fear of danger when a bus stopped suddenly. A temporary bus running course with one bus stop was set up on the campus of the Tokyo University of Agriculture and Technology (TUAT). The bus ran the course 14 times with the bus stopping twice during the course, once at the bus stop and again just after re-starting from the bus stop. The driver was asked to brake more strongly than usual when stopping. Sixteen students (15 males and 1 female) between the ages of 18 and 21 years participated. In turn, all participants were asked to take 14 different postures in the bus. Participants were also asked to report their level of fear on a rating scale each time the bus stopped. The study showed that (1) passengers' fear of danger at the first sudden stop was typically higher than that at the second stop, (2) standing passengers who held hand straps experienced more fear than those who held fixed safety devices, (3) bus passengers sitting on the centre of the rear seat had a great risk of injury if the bus stopped suddenly, and (4) when passengers faced the window and stood transversely with respect to from the moving direction of the bus and the bus stopped suddenly, passengers' fear of danger was affected by the side of the bus on which they stood as well as which hand they used to grasp a safety device.

Asunto(s)

RESUMEN

The purpose of this study was to investigate the effective use of stanchions and handrails in buses. We constructed experimental equipment resembling bus stanchions and handrails and examined the grip and hold strength exerted when used. The total number of subjects was 80: 30 elderly and 19 young males, and 22 elderly and 9 young females. The experimental equipment comprised four parts: a handle part to imitate safety devices in buses such as stanchions, handrails, and straps, which was pulled by a winch at a constant speed; and a load cell wired with an analyzing processor, which output the strength exerted. The handle part was designed to measure grip and hold strengths against pulling forces in three directions, that is, forward, in the direction of the back of the hand, and in the direction of the palm. The subjects were asked to grasp the handle part against a pulling force. The maximum grip and hold strengths were recorded and analyzed. The strengths when pulled forward were the largest independent of the sex and age of the subjects. The results indicate that standing bus passengers should grip the fixtures, such as a stanchion, with their right hand when they are standing on the right side in a bus facing the windows.

Asunto(s)

RESUMEN

Postural responses to challenging situations were studied in older adults as they stood on a foam surface. The experiment was designed to assess the relative contributions made by visual and somatosensory information to the correction of postural sway. Twenty-four subjects, aged 56-83, stood for 20 s on a 1) firm or 2) foam surface with 1) the eyes open or 2) the eyes closed. Centre-of-pressure trajectories under the subjects' feet were measured by using a force platform. A repeated-measure two-way MANCOVA (two surfaces vs. two vision conditions) showed a significant main effect for the surface, but not for the vision. No covariate effect for age was found. Anterior-posterior sway increased in the subjects who were merely standing on the foam surface independent of the vision condition. Medial-lateral sway dramatically increased if the subjects stood on the foam surface with their eyes closed, but not if they stood with their eyes open. These results indicate that older adults rely more on visual information to correct mediolateral postural sway. It appears that the deterioration in visual acuity that occurs with aging may increase the risk of sideway falls, particularly in challenging situations, e.g., when standing on irregular or soft surfaces.

Asunto(s)

RESUMEN

We investigated the relationships between the ability to maintain balance in an upright stance and center-of-pressure (COP) dynamic properties in young adults. Included in this study were 10 healthy male subjects in each of two groups with respect to balance ability. Balance ability was evaluated according to the length of time a subject stood on one leg with his eyes closed. The means and ranges of this one-leg balancing time were 17.9 s (3-43 s) and 118.3 s (103-120 s) for the off-balance and balance groups, respectively. The time-varying displacements of the COP under a subject's feet during quiet two-leg (normal) standing were measured by an instrumented force platform. Each subject was tested in both the eyes-open and eyes-closed conditions. The COP trajectories were analyzed as fractional Brownian motions according to the procedure of 'stabilogram-diffusion analysis', proposed by Collins and De Luca (1993). The extracted parameters were the effective diffusion coefficients (D) for the short-term (less than about 1.0 s) and long-term intervals, respectively, as well as the Hurst exponents (H) for the short-term and long-term intervals, and some critical-point coordinates (i.e., critical mean square displacements and critical time intervals). The off-balance group showed significantly higher values for short-term D, short-term H, and critical mean square displacements than the balance group. No significant differences between the groups were found in the long-term D and H or in the critical time intervals. That is, for the off-balance subjects, an increase in the stochastic activity and positively correlated (persistent) behavior of the postural sway during shorter timescales may cause postural instability. These results suggest that the difference in balance ability for young adults is related to the open-loop (i.e., short-term) control mechanisms but not to the corrective feedback (i.e., long-term) mechanisms used to maintain balance in an upright stance.

Asunto(s)

RESUMEN

Longitudinal secular changes of height and estimated leg length (ELL) or subischial leg length of Japanese boys and girls were investigated using data published in "The Statistical Report of the School Health Survey" of the Ministry of Education, Science, Sports and Culture, Japan. A significant trend towards greater relative leg length (long-leggedness) among Japanese children and youth has occurred during the period of about four decades covered by this study. After showing a strikingly consistent trend at all age levels between 6 and 17 years and a dramatic trend during the birth-year age period 1943-1963, the relative growth in leg length has been rapidly slowing or has stopped in both sexes. The relative growth of ELL seemed to be fixed after 11 years in boys and 9 years in girls. Maximum increment ages (MIA), both in height and ELL, were used as estimates of the timing of maximum growth during the adolescent spurt. Regression analysis was used to demonstrate the overall trend patterns of MIA in height and ELL. After removing autocorrelation effects, MIA for height is accelerated by 0.03 year in both sexes, while the MIA in ELL is accelerated by 0.03 year in boys and 0.01 year in girls. Thus, MIA in ELL in girls is occurring earlier but to a smaller extent than in boys. The average maturity difference between boys and girls is 2.07 years in height, but 2.83 years in lower extremity length. Am. J. Hum. Biol. 12:405-416, 2000. Copyright 2000 Wiley-Liss, Inc.