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Mountaineers and rock climbers use a belay device to increase tension in the rope that links the belayer to a falling climber—this rope slows and finally stops the fall. With a manual (passive) belay device the belayer can hold a force of several kN although he/she applies a hand force of only 0.2–0.35 kN on the rope; i.e. the device increases the hand force by a factor between 5 and 10. This investigation provides dynamic measurements of force amplification by various manual belay devices when used on a range of both wet and dry climbing ropes and it examines the source of force amplification in these devices. The force amplification is found to be due to a combination of friction and distortion of the rope as it traverses around tight corners within the device. In modern devices, the tension amplification due to distortion exceeds that due to friction.

Electronic personal health records (PHRs) have the potential to both make health information more accessible to patients and function as a decision-support system for patients managing chronic conditions. Age-related changes in cognition may make traditional strategies of integrating and understanding existing (i.e., paper-based) health information more difficult for older adults. The centralized and integrated nature of health information, as well as the long-term tracking capabilities present in many PHRs, may be especially beneficial for older patients' management of health. However, older adults tend to be late adopters of technology and may be hesitant to adopt a PHR if the benefits are not made clear (perceived usefulness). Toward the design of a useful PHR, a needs analysis was conducted to determine how people currently manage their health information, what they perceive as useful, and to identify any unmet needs. This paper describes two qualitative studies examining the health information needs of both younger and older adults. The first study used a 2-week diary methodology to examine everyday health questions or concerns, while the second study examined maintenance of health information and perceptions of PHRs through the use of a three-part interview. User's perceptions of the usefulness of PHRs are provided as recommendations for the design of e-health technology, especially those targeted for older adult healthcare consumers. The results suggest that both older and younger adults would deem a PHR useful if it provides memory support in the form of reminders, provides tools to aid in comprehension of one's health concerns, is interactive and provides automatic functions, and is highly accessible to authorized users, yet one's information is kept secure and private.

Effective communication influences the overall health of the patient. Older adults may be at a disadvantage during communication exchange due to age-related declines in cognitive abilities, sensati...

Impact damage to composite plates is significantly reduced by replacing some of the high-strength fibres with more ductile glass or synthetic fibres. Hybrid composites reduce impact damage by distributing more widely the deformations and strain in the contact region. This investigation focussed only on hybrid textile composites with individual tows composed of either carbon or glass which are braided together in a twill textile. At a similar level of impact energy, low and high-speed impact tests resulted in different failure mechanisms dominated, respectively, by quasi-static and flexural wave deformations. The damage severity was evaluated in terms of damage area (C-scan) and absorbed energy.

Axisymmetric and non-axisymmetric modes of vibration of circular sandwich panels are investigated by applying first-order shear theory (Mindlin-Reissner Plate). Solutions are obtained for boundary conditions with free, simply supported, and clamped edges. Numerical finite element method (FEM) simulation using ABAQUS is applied to validate the analytical modeling. Both analytical and numerical calculations are compared with experimental measurements of the first few modes of vibration; the frequency differences are less than 4%.

Technological advancements have become widespread, and their implementation into products of everyday use is accelerating. Technology has the potential to improve the lives of older adults by increasing their safety, security, and independence in daily life. However, too often older adults' capabilities and limitations are not considered in the design of current and future technologies. In 1990, the National Research Council identified the importance of human factors in the design of technology for an aging population. The goal of this chapter is to review research on aging and technology since that report to determine the contributions of human factors research to issues of aging and technology design. In this chapter we address the extent to which older adults use new technologies, factors to consider in the adoption of technology (e.g., attitudes), the influence of technology design on older adults' performance (e.g., design of input devices), and ways to optimize training for older adults in using new technologies (e.g., age-specific instructional designs). We then review emerging areas of research that may direct the focus of human factors research in the next decade. These areas of research include ubiquitous computing (e.g., home monitoring systems), health care technologies (e.g., telehealth), robotics (e.g., Nursebot), and automated systems (e.g., cruise control). Finally, we consider opportunities and challenges to human factors research as the field continues to address the questions of optimizing technology for older adult users.

Telemedicine systems have been found to increase access to patient care and decrease healthcare costs. However, the widespread adoption and use of telemedicine technologies has been low. The purpose of the present study was to evaluate an existing store-and-forward teledermatology system used by the U.S. military. The human factors issues that emerge in the evaluation of a telemedicine system include user characteristics (e.g., motivation to use the telemedicine system), macro-organizational issues (e.g., workload distribution, communication between team members), and technology issues (e.g., comfort using digital cameras or the World Wide Web). Users of the teledermatology system completed a questionnaire and an interview session. The detailed data from the structured interviews provided insight into the nature of these macro-organizational, user characteristics, and technology issues. The goal of this project was to illustrate how human factors methods can be used to understand the factors that contribute to the success or failure of this system, identify issues/potential problems, and provide recommendations for the current system and guidance for the design of future systems.

The purpose of this study is to understand the communication problems that older adults may encounter when interacting with their health care professionals. In particular, we are interested in the types of communication problems older adults have experienced such as memory, comprehension, and sensory issues. A structured interview consisting of two parts was designed to gather this information. The first part focuses on the specific communication problems participants may have had. The second part of the study involves six scenarios in which a fictitious patient has a communication problem with a health care professional. The goal of the scenarios is to determine the types of strategies, if any, participants recommend using when faced with communication problems with their health care professional. The findings from this study will be used to identify and categorize problems and strategies to inform design solutions to remedy these communication problems.

The U.S. military has initiated several telemedicine programs ranging from teledermatology to telemental health. Several advantages of telemedicine programs have been documented including increased patient satisfaction and decreased healthcare costs. However, not all telemedicine programs in the military have been successful (i.e., widely used). This analysis used multiple methods to identify the human factors issues involved in using a teledermatology system. The methods included task analyses, decision-action diagrams, and a questionnaire distributed to subject matter experts (SMEs). In a progressive fashion, each method contributed to development of the next method. Task analyses guided the development of decision-action diagrams. Decision-action diagrams identified critical human factors issues within the system and led to the development of questionnaire items specifically targeting those areas (e.g., workload, errors). The results from this assessment demonstrate how multiple methods can be used to analyze a system, identify human factors issues, and suggest interventions.

The bounce of a hollow spherical ball from a hard flat surface results in large deformations of the thin-walled shell; these deformations increase the internal stresses in the shell near a knuckle of bending and also increase the internal gas pressure inside the shell. This paper calculates the deformation and consequent contact forces that repel the ball from the surface, and compares the results with both a finite element analysis and experimental data. A table tennis ball is considered as an example of a thin-walled elastic shell. Since for an elastic ball there are no energy losses due to inelastic material behaviour, the analysis assumes that all energy losses are due to either friction in the contact area or impulsive forces arising from the instantaneous rate-of-change of momentum in the knuckle. In practice, the table tennis ball shows energy losses that increase with increasing impact speed; these losses substantially exceed the losses taken into account by the elastic shell analysis.

Summary Aims Gestational diabetes mellitus (GDM) is associated with adverse maternal and fetal outcome. Screening for GDM is therefore recommended but the best screening method remains controversial. This prospective, randomized study compared a risk factor-based screening programme with a universally based one. Methods Subjects were randomized at booking to one of two groups: the risk factor group had a 3-h 100-g oral glucose tolerance test (OGTT) at 32 weeks if any risk factor for GDM was present; the universal group had a 50-g glucose challenge test performed and if their plasma glucose at 1 h was ≥ 7.8 mmol/l, a formal 3-h 100-g OGTT was then performed. Results Universal screening detected a prevalence of GDM of 2.7%, significantly more than the 1.45% detected in the risk factor screened group (P

The number of older adults is increasing, and telemedicine has the potential to improve their access to health care. Telemedicine systems have been shown to benefit older adults by increasing peer support interactions, providing health-care access to older adults in rural communities, reducing the cost of health care, increasing exercise, reducing pain and depression, and, perhaps most important, improving functional independence. However, older adults may have different needs from other users when interacting with telemedicine systems, because of age-related changes in perceptual, motor and cognitive abilities. The design of telemedicine technologies should, therefore, capitalize on older adults' strengths while minimizing their weaknesses. The field of human factors has much to offer in optimizing interactions between older adults and telemedicine technologies. Future research should take advantage of human factors methodologies to best design telemedicine technologies for an older population.

Urinary tract fistulas are a relatively uncommon but important complication of gynaecological surgery. Between 1980 and 1995 we identified 17 patients who developed a urinary tract fistula after gynaecological surgery. Seven of the patients had surgery performed for neoplastic disease but none of these patients received adjuvant radiotherapy before the formation of the fistula. There were 12 vesicovaginal fistulas and five ureteric fistulas. Four of the vesicovaginal fistulas were repaired by the vaginal approach and five vesicovaginal fistulas were repaired by the abdominal route. Three vesicovaginal fistulas were treated by catheterisation alone. Two of the 17 patients took medicolegal action. Early recognition and repair of urinary tract fistulas is recommended. Repair of vesicovaginal fistulas by the vaginal approach is advised. The litigious nature of this distressing condition is lessened when early primary closure is successful.

The benefits of telemedicine systems within the U.S. military have been widely recognized. However, a number of telemedicine systems have encountered resistance and have failed to be adopted and widely used. The purpose of the present project was to use a human factors analysis to characterize the facilitators and impediments to the use of a teledermatology system. More specifically, the goal was to investigate areas such as training, workload distribution, and communication between team members because these topics can be broadly classified as human factors issues. Across different sites, structured interviews were administered to three user groups within the system (i.e., consult managers, primary care managers who are comparable to civilian primary care physicians, and dermatologists). All three user groups reported that system support, speed, personal benefits, and increased education and experience were facilitators to system use; impediments were usability problems and insufficient training. However, each user group also identified unique facilitators and impediments. For example, users at the referring site (consult managers and primary care managers) focused on workload distribution among team members and the importance of onsite support as facilitators. In contrast, key facilitators for physicians (primary care and dermatologists) were effective communication, professional benefits, and increased quality of patient care. Human factors issues are critical for successful telemedicine systems and user issues may vary across user groups. The method reported herein provides guidance for development of new telemedicine systems and evaluation of existing telemedicine systems to increase adoption and usage.

rupture of the unscarred uterus. The principal difference between the three countries is in the aetiology of the uterine rupture. In Syria 50% of ruptures occurred in a scarred uterus and 50% occurred in an unscarred uterus associated with trauma or spontaneously. In Nigeria 75% occurred in association with a previous section scar and 25% had traumatic factors or were unexplained apart from parity. In Sudan 35% ruptures occurred in a scarred uterus and 65% occurred in an unscarred uterus. These differences may be explained by the availability of medical services or distance from hospital services. In contrast, the results from Ireland, published in the Journal in 1993, one-third of cases occurred in the unscarred uterus and two-thirds occurred in the scarred uterus. There were no maternal deaths but the perinatal mortality rate was 45%. These ® gures would suggest that social and medical improvements in developing countries will signi® cantly improve survival in mothers with ruptured uterus and reduce the perinatal loss by 50%.

We performed a prospective randomised study on one hundred primigravid women who required oxytocin to augment labour, comparing dextrose infusion with normal saline. After delivery, the 45 patients whose oxytocin was infused in dextrose had significantly lower serum sodium levels in both mother and baby compared to the 48 patients who had their oxytocin administered in normal saline. This was particularly evident in those cases where epidural analgesia was employed.

The field of human factors strives to optimise the performance, efficiency, and safety of human-machine systems by obtaining a clear understanding of the cognitive, perceptual and motor capabilities and limitations of users and their environment (both the physical environment and organisational climate). Thus, it is a science expressly devoted to many critical components of telemedicine systems. For example, telemedicine system users interact with potentially unfamiliar technology (e.g. digital cameras), individuals (e.g. doctors and patients), and information (e.g. technical instructions for a referring physician). In addition to these issues that users face on a regular basis, organisational issues exist, such as the management and overseeing of the system and the designation of various user roles within the system. Human factors researchers and practitioners employ multiple methods to evaluate psychological, macroergonomic, and usability issues that face users, as well as to provide design recommendations to improve system efficiency. These methods include task analysis, qualitative research methods (e.g. interviews and surveys), usability analysis, and quantitative research methods (e.g. questionnaires and experimental research). If telemedicine systems are to be successful and widely adopted, human factors evaluations and interventions must play a critical role in their development and continued improvement.

The transient motion of a simply supported, rigid-plastic beam in response to uniformly distributed pressure pulses of arbitrary shape is considered. The objective is to determine the pulse shape that will maximize the residual deflection at the center of the beam subject to certain load constraints. Results for two constraints are determined. When a specified impulse is applied to the beam an impulsive load causes the largest deflection. When a specified amount of work is done on the beam the deflection is maximized by limiting the maximum pressure so only the static collapse deformation mode occurs. This result is independent of pulse shape. These conclusions are supported by comparisons of the deformation due to triangular, exponentially decreasing and double rectangular pressure pulses.

The transient motion of a simply supported, rigid-plastic beam in response to a uniformly distributed pressure pulse of arbitrary shape is determined. The beam is subject to an axial force in addition to the transverse pressure. This axial force is a parameter that can approximate constraint forces resulting from deformation of beams with fixed or elastically restrained ends. The pulse shape that maximizes deflection at the center of the beam is determined for a specified applied impulse. When a transverse pressure applies a limited amount of impulse to the beam, an impulsive load causes the largest deformation. Axial force decreases the deformation but has no effect on the most efficient pulse shape.

This report is concerned with the application of general purpose finite element structural analysis programs to warhead design work. The capabilities of a number of linear and nonlinear programs including NASTRAN, SAP IV, ADINA, and HONDO are described. These programs are used to solve a number of impact-type problems ranging in complexity from a simple one dimensional rod to a conical steel warhead filled with explosive. The results are compared on the basis of accuracy, time and cost, ease of learning, and ease of use. (Author)

Impact bending of rotating fan blades is theoretically analyzed by the use of simplified beam models. The blade material is idealized as either rigid-perfectly-plastic or linear elastic. The rigid-perfectly-plastic model gives three modes of deformation; a single plastic hinge mode, two hinges mode and three hinges mode, depending on the impact condition. The centrifugal force due to the fan rotation makes the hinges travel along the beam and decrease the transverse deflection of the beam. The linear elastic model gives a simple wave propagation solution. The centrifugal force decreases the deflection amplitude and lowers the wave propagation velocity.

Keeping track of health information may be burdensome for older adults who may be more likely to have health concerns and questions than other age groups. The management of their health information may be aided by web-based health information management tools (e.g., personal health records). However, it is currently not known what kinds of health information potential users seek and need or want to manage. The current study examined the health information needs of both older and younger adults, to better understand how e-health technology can aid health information management. Seventeen younger and twenty-four older adults kept a health diary for a two-week period, making one entry for each health concern or question they had and how they solved it.