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Biomedical subjects

D I Miller

Publications and source records attributed to D I Miller.

At least 19 recordsLinked to original sources
PubMed2000

An evaluation of the ergonomics of three computer keyboards.

The influence of keyboard design on hand position, typing productivity and keyboard preference was evaluated by comparing two segmented alternative designs with the linear standard keyboard. The FIXED alternative keyboard featured a split angle of 12 degrees and a moderate lateral inclination angle of 10 degrees. The adjustable OPEN alternative keyboard was used with a 15 degrees split setting, which resulted in a marked 42 degrees of demiboard lateral inclination. Sixteen typists, who completed 10 h of training on both alternative keyboards, were videotaped while typing set texts on all three keyboards. Forearm and wrist angles based on three-dimensional video analyses were significantly different (p<0.05) among the three designs tested. Both alternative keyboards placed the forearm and wrist closer to neutral positions than did the standard keyboard. While the OPEN keyboard reduced pronation, it simultaneously increased radial deviation. The FIXED keyboard kept the forearm in moderate pronation and the wrist closer to neutral. More time was spent in neutral and moderate ranges of wrist motion when subjects typed on the FIXED compared with the other two designs. With respect to the standard keyboard, typing productivity was reduced by 10% on the FIXED and 20% on the OPEN designs. No significant difference in preference was found between the standard and FIXED keyboards, both of which were preferred over the OPEN. It was concluded that, of the three keyboards evaluated, the FIXED design incorporated moderate changes to the standard keyboard. These changes promoted a more natural hand position while typing thereby reducing the potential for cumulative trauma disorders of the wrist. In addition, the FIXED design preserved a reasonable level of productivity and was well accepted by users.

Adult↗
PubMed1998

Springboard oscillation during hurdle flight.

The relative influences of board-tip rebound and fulcrum setting upon vertical board-tip oscillation during hurdle flight were investigated to gain insight into the mechanism by which highly skilled divers are able to make effective contact with the springboard. Data were collected on running dives executed by 3-m finalists at the 1995 World Diving Cup (men), the 1996 Olympic Games (women) and the 1996 US Junior Olympics (boys and girls). Analysis of the vertical board-tip patterns of motion during hurdle flight revealed substantial deviations from a regular damped oscillation, particularly during the first excursion above the horizontal. The latter was characterized by two peaks, the first resulting from upward momentum and the second due to the board's colliding with the fulcrum. A regression analysis of the senior divers' data indicated that 83.7% of the variance in hurdle flight time could be accounted for by the maximum height reached by the board-tip and only 3.6% by fulcrum setting. We conclude that, among senior divers, rebound of the springboard was the dominant factor influencing the length of time required for the board to complete its characteristic 2.25 and 2.50 cycles before take-off.

Biomechanical Phenomena↗
PubMed1991

Female DUI offenders: a comparison to male counterparts and an examination of the effects of intervention on women's recidivism rates.

Female DUI offenders who participated in a controlled, random assignment DUI intervention study, the Mississippi DUI Probation Follow-Up Project, were compared to their male counterparts on demographic, drinker status and recidivism variables. In comparison to men, women in the project were less likely to be married, more likely to be between 30 and 50 years of age, less likely to have less than a 9th grade education, less likely to be screened as a high-problem-risk drinker, less likely to have prior DUI and public drunkenness arrests and less likely to recidivate. The effects of short-term rehabilitation, 1 year's probation and administration of the Life Activities Inventory-Current Status Questionnaire (LAI-CSQ) on the long-term recidivism rates of women were examined. The analysis for screened low-problem-risk women was inconclusive due to lack of statistical power. However, the repeated administration of the LAI-CSQ was detrimental for screened high-problem-risk women and tended to be detrimental for women with fewer than 12 years of education. Implications for intervening with female DUIs are discussed.

Accidents, Traffic↗
PubMed1990

Development of control-of-outcome scales and self-efficacy scales for women in four life roles.

Scales to measure control-of-outcome expectancies and self-efficacy expectancies based on social comparisons were developed for adult females in the four life roles of occupation, parenting, marriage, and economic management. Internal consistency and construct validity of the scales were examined in two studies. Internal consistency estimates of six of the eight scales exceeded .70. A factor analysis within each role supported the distinction between control-of-outcome expectancies and self-efficacy expectancies. Construct validity was supported by finding the hypothesized relations between the developed scales and standard measures of self-esteem, depression,and locus of control. As hypothesized, the developed scales accounted for unique portions of the variance in role-specific coping orientation and role stress. Specifically, control-of-outcome expectancies predicted active or passive coping orientation in the personal roles of parenting and marriage. It was concluded that the developed scales might have utility for understanding coping and experienced stress in various life roles.

Adult↗
PubMed1987

Resultant lower extremity joint moments in below-knee amputees during running stance.

Resultant flexion/extension lower extremity joint moments of four below-knee amputees running between 2.5 and 5.7 m s-1 were computed during stance on their intact and prosthetic limbs. All subjects wore patellar tendon-bearing prostheses with either a SACH or Greissinger foot component. During stance on the prosthesis, the resultant hip extensor moment on the amputated side was greater in magnitude and duration than its counterpart on the intact limb during its corresponding stance period. Since the artificial foot was planted on the ground, such a moment may help control knee flexion and promote knee extension of the residual limb. For the three subjects whose knees continued to flex at the beginning of stance, there was a dominant extensor moment about the knee joint during stance on the prosthesis. By contrast, for the fourth subject whose knee remained straight or hyperextended throughout stance on the prosthesis, a flexor moment was dominant.

Adult↗
PubMed1987

Ground reaction forces in running: a reexamination.

Ground reaction force (GRF) data were collected on twenty adult males during running stance to establish normative standards to aid in assessment of the gait of atypical runners. Subjects ran between 30 and 40 trials across a Kistler 0.6 X 0.9 m force platform at self-selected speeds ranging from 2.5 to 5.5 m s-1. Best fit polynomials for a given descriptor variable were constructed for each subject and the polynomials were evaluated as a function of running speed. Predicted means and standard deviations (based on the polynomials) were calculated and multivariate analyses of variance were performed. The descriptor variables: impact peak, loading rate, thrust maximum, decay rate, average vertical GRF, change in vertical velocity, braking impulse, propulsive impulse and stance time were determined to be running speed dependent (p less than 0.001). Specific patterns associated with the breaking component of the antero-posterior GRF of heel-strikers included single, double and multiple peaks. Three dimensional graphic displays showed that, despite considerable group variability in medial-lateral GRF-time histories, consistency was evident in the patterns of individuals across speeds. Individual right-left asymmetries were clearly shown in these displays.

Adult↗
PubMed1984

Body segment contributions to height achieved during the flight a springboard dive.

The way in which athletes achieve the necessary height to accomplish the rotational requirements of springboard dives was investigated by focusing upon the take-offs of dives from the forward and reverse groups. Films of eight women in the 3-m final of the 1982 Canadian championship and of five men practicing for the 1979 Fort Lauderdale Invitational Meet provided data for the analysis. The vertical acceleration of the diver's center of gravity was expressed relative to that of the metatarsals, which represented the point on the board directly beneath the feet. The divers were only able to accelerate upward relative to the metatarsals for approximately the first half of springboard depression. This period of positive relative acceleration was considered to be a key factor in effective deflection of the springboard. The lower extremities were responsible for about three-quarters of the diver's vertical acceleration during this period. Two-thirds of their contribution was attributed to their role in accelerating the large mass of the trunk upward. The upper extremities accounted for about 10% of the diver's vertical acceleration during the initial half of springboard depression. Their acceleration-time patterns clearly fell into three classifications depending upon whether their upward acceleration relative to the shoulders preceded, coincided with, or followed initial contact with the board for the take-off.

Biomechanical Phenomena↗
PubMed1982

Below-knee amputee running gait.

The running ability of ten unilateral below-knee amputees was examined by analyzing the temporal and length characteristics of their running strides and the angular displacement patterns of their intact and prosthetic limbs. Six of the individuals tested were able to run and in several cases their locomotor patterns were similar to those of non-amputees. The running gait of three of the amputee runners, however, did contain one particular undesirable element namely an excessively straight residual knee during at least a portion of support on the prosthesis. Although several explanations could be postulated to account for this tendency, we believe that it could be eliminated with training and possible prosthetic modification. Results of the study, while attesting to the fact that many lower extremity amputees can run, also suggested directions in which research efforts can and are being focused to facilitate their running performance.

Adult↗
PubMed1979

Body contact swimming rescues--what are the risks?

A survey of 482 lifeguards and Water Safety Instructors revealed that at least one-half had performed body contact swimming rescues (BCRs). Over two-thirds of these BCRs occurred when the lifesaver was relatively inexperienced in actual water rescues of any kind although virtually all rescuers had received formal lifesaving training. The victim tried to grasp the rescuer in 26 per cent of the BCRs which took place in swimming pools and 39 per cent of those occurring in lakes. Most of these attempts were made during the approach and were predominantly from the front, around the rescuer's head and neck or wrists and arms. Since the majority of victims were younger and smaller than their rescuers and got into difficulty less than 3 m from safety, only a small proportion of the grasps were perceived as endangering the lifesaver. Consequently, the victim was often permitted to retain the hold while being rescued. Grasps which were reported to be threatening tended to be applied by individuals of equal or larger physical size than the rescuer and usually occurred at distances exceeding 3 m from safety.

Adolescent↗
PubMed1979

Modelling in biomechanics: an overview.

The state of the art in biomechanical modelling is reviewed with specific reference being made to physical and mathematical idealizations of the human body and its segments. Scale models and anthropomorphic dummies which fall within the physical category are discussed briefly. Mathematical models which are much more prevalent and virtually synonymous with computer simulation models are then considered in two major classifications: deformable element and rigid body representations. The former include lumped parameter, discrete parameter, finite element and continuum models and are commonly used to represent the vertebral column. Examples of rigid body models of the total body response and inertial parameter variety are outlined. Finally, topics relating directly to the construction of sport and locomotion models are discussed. These include considerations for developing a static or dynamic model, utilizing Newtonian or Lagrangian equations of motion, and dealing with indeterminate systems.

Anthropometry↗
PubMed1975

Prediction of segmental parameters using the Hanavan human body model.

The Hanavan mathematical model of the human body was updated utilizing Clauser et al.'s multi-step weight distribution regression equations. The influence of these equations upon the predicted segment weights, specific gravities and principal moments of inertia of 30 adult male athletes was compared to that of Barter's regression equations employed in the original model. Both methods resulted in descrepancies between actual body weight and the predicted sum of the segment weights with Barter's equations consistently underestimating total body weight by an average of 2.03% and Clauser et al.'s overestimating it by 4.59%. Proportional distribution of the discrepancies produced corrected segment weights which were used in the Hanavan model. Clauser et al.'s equations predicted heavier trunks and thighs, and lighter heads, upper arms, forearms and hands with these differences being reflected in the specific gravities and principal moments of intertia. While it was not possible to establish the definite superiority of Clauser et al.'s equations in the prediction of body segment parameters, it is suggested from inferential evidence that they be used in subsequent biomechanical investigations of adult male athletes which involve the Hanavan model. It is also recommended that continued efforts be made to refine the Hanavan human body model.

Anthropometry↗