bluuebunny/crossref_metadata_2025 huggingface dataset:
Readiness for Medicaid Managed Care Reform Initiatives: A Profile of Rural Family Physicians
Authors: James Paul A. , Cowan Timothy M. , Bliss Mary K. , Graham Robin P. , Rosenthal Thomas C.
Published: April 2008

Abstract: Medicaid managed care is now an important factor in the financing of rural health care delivery. The participation of rural family physicians in Medicaid managed care is vital for the rural poor to access health services. This study examined 855 family physicians practicing in non metropolitan counties across the United States to determine their readiness to participate in Medicaid managed care. Physicians were asked about their experience with prepaid programs and the factors that would influence their participation in such a program. A shortage of health care providers and low reimbursement rates were most frequently cited as barriers to successful implementation. Physicians who had participated in prepaid programs in the past but were no longer participating had the most negative opinions about the potential for Medicaid managed care programs to enhance care for the poor in their communities. Overall, physicians reported potential for the program to improve access and quality of care, but they also expressed reservations about the financial and administrative effects on their practices. These results reveal that negative attitudes were associated with prepaid programs that failed to meet expectations, but physicians also expressed an optimism about the potential to serve the poor within a managed care model.
The Distribution of Rural Female Generalist Physicians in the United States
Authors: Doescher Mark P. , Ellsbury Kathleen E. , Hart L. Gary
Published: April 2008

Abstract: Female physicians are underrepresented in rural areas. What impact might the increasing proportion of women in medicine have on the rural physician shortage? To begin addressing this question, we present data describing the geographic distribution of female physicians in the United States. We examine the geographic distribution of all active U.S. allopathic physicians recorded in the October 1996 update of the American Medical Association Physician Masterfile. Percentages and numbers of female physicians by professional activity, specialty type, and geographic location are reported. Findings reveal there were fewer than 7,000 female allopathic physicians practicing in rural America in 1996. The proportion of generalist female physicians who practice in rural settings was significantly lower than the proportion who practice in urban locations. Although members of the most recent 10‐year medical school graduation cohort of female generalist physicians were slightly more likely to practice in rural areas than members of earlier cohorts, female physicians remained significantly underrepresented in rural areas. States varied dramatically in rural female generalist underrepresentation. Should female generalists continue to be underrepresented in rural locations, the rural physician shortage will not be resolved quickly. Effective strategies to improve rural female physician placement and retention need to be identified and implemented to improve rural access to physician care.
The Effectiveness of a Rural Nursing Center in Improving Health Care Access in a Three‐County Area
Authors: Anderko Laura , Robertson Julie Fisher , Uscian Mary M.
Published: April 2008

Abstract:The purpose of this article is to describe an innovative nurse‐managed health center that has been effective in improving access to primary health care for residents of a Midwestern three‐county rural area. Penchansky and Thomas's (1981) framework for evaluating health care access was used to analyze client satisfaction and utilization data. Findings clearly indicate success in improving access. Client satisfaction surveys consistently show a high level of satisfaction across all framework dimensions, including overall satisfaction with the health care received. Utilization data indicate a steady increase in the number of clients served, especially those who are uninsured or underinsured. This article demonstrates that key dimensions of access can be effectively measured using the Penchansky and Thomas framework and concludes with recommendations for enhancing the model.
Quality Oversight: Why Are Rural Hospitals Less Likely to be JCAHO Accredited?
Authors: Brasure Michelle , Stensland Jeffrey , Wellever Anthony
Published: April 2008

Abstract: There is a large rural‐urban disparity in the proportion of hospitals that are accredited by the Joint Commission on the Accreditation of Health Care Organizations (JCAHO). Several factors can influence whether a hospital participates in the accreditation process. A few of those factors include the hospital's size, case mix and ownership. However, even after controlling for many of these factors, hospitals in the most rural locations are less likely to be accredited by the JCAHO than urban hospitals. A survey was conducted to explore why rural hospitals are not participating in the accreditation process. Survey results show that the largest factor contributing to rural hospital deterrence to seeking accreditation is cost. Without accreditation by the JCAHO and compliance with their movement into performance measurement, quality monitoring of rural hospitals will fall further behind that of urban hospitals. Policy initiatives that make accreditation more financially feasible should be considered.
Using Telemedicine to Avoid Transfer of Rural Emergency Department Patients
Authors: Hicks Lanis L. , Boles Keith E. , Hudson Stanton T. , Madsen Richard W. , Kling Barry , Tracy Joe , Mitchell Joyce A. , Webb Weldon
Published: April 2008

ABSTRACT: Access to emergency treatment in rural areas can often mean the difference between life and death. Telemedicine technologies have the potential of providing earlier diagnosis and intervention, of saving lives and of avoiding unnecessary transfers from rural hospital emergency departments to urban hospitals. This study examined the hypothetical impact of telemedicine services on patients served by the emergency departments of two rural Missouri liospitals and the potential financial impact on the affected hospitals. Of the 246 patients transferred to the hub hospital from the two facilities during 1996, 161 medical records (65.4 percent) were analyzed. Using a conservative approach, only 12 of these cases were identified as potentially avoidable transfers with the use of telemedicine. Of these 12, 5 were admitted to the hub hospital after transfer. In addition to this conservative estimate of avoidable transfers based on current availability of resources in the rural hospitals, two more aggressive scenarios were developed, based on an assumption of increased service availability in the rural hospitals. Economic multipliers were used to estimate the financial impacts on communities in each scenario. This evaluation study demonstrates the potential value of telemedicine use in rural emergency departments to patients, rural hospitals and rural communities.
Impact of a Rural Domestic Violence Prevention Campaign
Authors: Gadomski Anne M. , Tripp Maria , Wolff Debra A. , Lewis Carol , Jenkins Paul
Published: April 2008

ABSTRACT: Domestic violence is a prevalent health problem that in rural areas is further complicated by limited services, social isolation and the lack of privacy. Little is known about the impact of public health education on awareness, attitudes and behavior of the general public regarding domestic violence. This study sought to measure change in societal attitudes and behavioral intention in response to a seven‐month public health education campaign targeting domestic violence in a rural county. From October 1998 to April 1999, the campaign used radio advertisements, posters, mailings to libraries and clergy, printed media articles, printed advertisements and health facility modifications. A random‐digit‐dialing telephone survey was used to evaluate attitudinal and behavioral changes in the intervention and comparison counties before and after the campaign. The response rates for the pre‐ (n=378) and postcampaign (n =633) surveys were 73 percent and 65 percent, respectively. Statistically significant increases in slogan and advertising recognition occurred in the intervention county (P=0.03), particularly among men recalling the campaign slogan (P =0.006). In a vignette regarding actions to be taken if the neighbor next door was abusing a partner, significant increases occurred in the intervention county in the percentage of respondents who thought that most people would talk to the victim (P=0.04), consult with friends (P =0.002) or talk to a doctor (P =0.004). Domestic violence agency hotline calls in the intervention county doubled following the campaign. Local public health education campaigns in a rural setting may be a valuable adjunct to national efforts, especially in reaching men.
Not Raising a “Bubble Kid”: Farm Parents'Attitudes and Practices Regarding the Employment, Training and Supervision of Their Children
Authors: Neufeld Steven , Wright Sue Marie , Gaut Jolene
Published: April 2008

This article explores farm parentś attitudes and practices regarding the employment, training and supervision of their children among a sample of 24 farm couples from southeastern Washington state. The goal was to gain a greater understanding of parental attitudes and practices in order to devise appropriate and meaningful efforts to improve the safety of children and adolescents involved in farm work. Demographic data regarding the farm families and their farm safety practices were collected through a short questionnaire, and parental attitudes and practices regarding the employment, training and supervision of their children were explored through open‐ended, semi‐structured interviews. The results suggest that farm parents have developed a logical and consistent set of beliefs and attitudes regarding the employment, training, and supervision of their children that is based in part on the belief that farm work is highly beneficial to their childreńs development. Safety interventions to reduce childhood farm injuries will have to acknowledge farm work as important and beneficial for children in order to maintain legitimacy and credibility. Nevertheless, because farm parentś practices regarding their childrenńs employment reflect cultural beliefs and values regarding children and child‐rearing, some recommended safety guidelines will be difficult to implement.
Distribution of Services and Supports for People With Traumatic Brain Injury in Ruraland Urban Missouri
Authors: Johnstone Brick , Nossaman Larry D. , Schopp Laura H. , Holmquist Lori , Rupright S. Jon
Published: April 2008

New paradigms of disability suggest that many variables interact to influence the community functioning of people with traumatic brain injury (TBI), including injury severity and social, psychological, and environmental factors. Unfortunately, the majority of TBI outcome research to date has primarily focused on injury severity variables (e.g., neuroradiologic findings, loss of consciousness, posttraumatic amnesia) to the exclusion of environmental variables. Limited environmental resources such as rehabilitation professionals, facilities, and services may be significant barriers that affect outcome for people with TBI, particularly for those in rural areas. Using data from Missouri, where 32% of the population lives in rural counties, this study researched the availability of rehabilitation resources for individuals with TBI, with an emphasis on differences between rural and urban areas. Data indicated that there is a scàrcity of rehabilitation professionals (i.e., physiatrists, mental health providers, rehabilitation therapists), facilities (i.e., hospitals offering comprehensive rehabilitation therapies), and services (i.e., support groups) in rural areas of the study state. The results suggest that (1) future rehabilitation researchers need to evaluate the impact of accessibility to rehabilitation services and resources on the outcome of people with TBI and (2) TBI health policy administrators need to consider how to increase rehabilitation resources for people with TBI in rural areas, including the use of rural‐based training programs, rural debt‐forgiveness training programs, and telehealth systems.
Rural Long‐term Care: What Do We Need to Know to Improve Policy and Programs?
Authors: Coburn Andrew F.
Published: April 2008

This article examines what is known and what we need to know about rural long‐term care populations and the formal and informal service systems that support their long‐term care needs. The article provides a framework for identifying some of the critical policy and research questions concerning the financing and delivery of rural long‐term care that merit the attention of health services researchers and policymakers. It documents differences in the demographic and health characteristics of the rural and urban elderly and in the availability, organization, and use of health and long‐term care services in rural areas that have significant implications for long‐term care policy and programs. With this background in mind, the author discusses specific topics and questions relevant to long‐term care policy and program improvements for rural communities and people: (a) the changing role of the rural nursing home; (b) residential care alternatives in rural areas; (c) health personnel and rural long‐term care; (d) the quality of rural long‐term care; (e) innovations in long‐term care financing and service delivery; (f), use of technology in rural long‐term care; and (g) the effects of Medicaid and Medicare policy changes on the rural long‐term care system.
Medicaid Managed Behavioral Health in Rural Areas
Authors: Lambert David , Gale John , Bird Donna , Hartley David
Published: April 2008

Abstract: As of 2000, 21 states had implemented Medicaid managed behavioral health (MMBH) programs for a significant portion of their rural population. It is not clear how MMBH programs may work in rural areas since they are primarily designed to control mental health utilization. In rural areas the challenge is often to enhance service delivery, not to reduce it. MMBH programs may also affect important features of rural delivery systems, including access to care and coordination of primary care and specialty mental health providers. This article describes the implementation of MMBH programs in rural areas based on an inventory of states implementing MMBH programs in rural counties conducted between June 1999 and June 2000. The experience of MMBH programs in rural areas is also described based on case studies conducted in six states. All 21 states included the general Medicaid population (Temporary Assistance for Needy Families); 17 states included special Medicaid populations (adults with serious and persistent mental illness and children with serious emotional disturbances). Slightly less than half the states integrated (carved‐in) behavioral health with physical health services in serving the general Medicaid population; only one state integrated these services for the special Medicaid population. Access to mental health care in rural areas had generally not been restricted. MMBH had little impact on the linkage between primary care and mental health. Local Managed Behavioral Health Organizations, formed by public sector entities and providers, played an increasingly important role in the evolution of MMBH.
Health Care Needs of the Growing Latino Population in Rural America: Focus Group Findings in One Midwestern State
Authors: Blewett Lynn A. , Smaida Sally A. , Fuentes Claudia , Zuehlke Ellie Ulrich
Published: April 2008

Abstract: Latinos represent nearly 13% of the U. S. population, surpassing African‐Americans as the nation's largest racial/ethnic group. Many rural midwestern communities are seeing unprecedented growth in their Latino populations, creating new challenges and pressures for health and social service providers. This study is based on four focus groups conducted in three rural communities to examine concerns with health care services and access to care. Focus group analysis found several key barriers to health care access, including cost of health care services and frustration with the complexity of the U. S. health care system, as well as language and cultural issues that adversely affect patient‐provider relationships. In addition, a number of impediments related to employer‐sponsored health coverage were identified, including prohibitive premium costs as well as concerns about occupational injuries and access to care during work hours. The growth of the Latino population in the rural Midwest will require changes in existing health and social service systems to serve as a bridge to new systems in this country. We recommend several policy options including premium subsidies for lowwage jobs, community‐based enrollment specialists for public programs, and continued research and data collection to monitor change and progress.
Risk Factors for Animal‐related Injury Among lowa Large‐livestock Farmers: A Case‐control Study Nested in the Agricultural Health Study
Authors: Sprince Nancy L. , Park Hyesook , Zwerling Craig , Lynch Charles F. , Whitten Paul S. , Thu Kendall , Burmeister Leon F. , Gillette Patricia P. , Alavanja Michael C. R.
Published: April 2008

Abstract: Context: Although farmers are at risk for injuries from contact with large livestock, few previous studies have examined risk factors for animal‐related injuries. Purpose: This case‐control study, nested in the Agricultural Health Study, aimed to assess risk factors for animal‐related injury among lowa large‐livestock farmers. Methods: A screener questionnaire sent to 6999 farmers identified 116 farmers with large livestock who had an animal‐related injury requiring medical advice/treatment in the previous year. Several possible risk factors for injury were assessed by comparing these farmers with 342 farmers who had livestock but were not injured in the previous year. Findings: A multiple logistic regression analysis showed significant associations between animal‐related injury and the use of a hearing aid (odds ratio [OR] = 5.4 [95% CI, 1.6 to 18.0]), doctor‐diagnosed arthritis or rheumatism (OR = 3.0 [95% CI, 1.7 to 5.2]), education beyond high school (OR = 1.8 [95% CI, 1.1 to 2.8]), and a younger age. Farmers engaged in off‐farm work were less likely to sustain animal‐related injuries (OR = 0.4 [95% CI, 0.2 to 0.8]). Conclusions: This is the first study to show associations between animal‐related injury and a younger age, hearing difficulties, and doctor‐diagnosed arthritis. Hearing loss and arthritis, which are more common among farmers than among other workers, may be particularly important risk factors to address in future preventive studies.
Economic Burden of Agricultural Machinery Injuries in Ontario, 1985 to 1996
Authors: Locker Alison R. , Dorland John L. , Hartling Lisa , Pickett William
Published: April 2008

Abstract: Context: Agricultural injuries are an important and understudied category of occupational injuries

Purpose: This study estimated the economic burden of agricultural machinery injuries that occurred in Ontario, Canada's largest province, between 1985 and 1996

Methods: Conventional methodology for estimating economic burden, as embodied in a computer program previously developed for this purpose, was applied to hospitalized, nonhospitalized, and fatal agricultural machinery injuries

Findings: The total economic burden of these injuries over the 12‐year study period was estimated to be £228.1 million, or £19.0 million annually (1995 Canadian dollars, 3.0% discount rate). By extrapolation, the economic burden of all farm injuries in Canada is estimated to be between £200 and £300 million annually

Conclusions: Costing information about agricultural injuries provides support for the prioritization and development of injury‐control initiatives
Rural‐Urban Differences in Ductal Carcinoma in Situ as a Proxy for Mammography Use Over Time
Authors: Schootman Mario , Kinman Edward , Farria Dione
Published: April 2008

Abstract: Context: With emphasis on increasing use of mammography, the rate of ductal carcinoma in situ (DCIS) of the breast has increased dramatically in the United States starting in the; early 1980s. It is unclear if rural and urban women have experienced similar increases. Purpose: To describe differences in incidence of DCIS between rural and urban women 50 to 69 years of age over time. This may be a proxy indicator of mammography use for the early detection of breast cancer. Methods: The study population consisted of women 50 to 69 years of age who were diagnosed with DCIS during 1973–1997 and resided in Iowa, Utah, or New Mexico. Data from the Surveillance, Epidemiology, and End Results (SEER) programs in these states were used in the analysis. Location of the woman's residence was classified into urban when she lived in a county considered a Metropolitan Statistical Area, while she was considered rural if she resided elsewhere at the time of her diagnosis. Findings: Increases in rates were different between rural (annual percentage change [APC]: 15.1) and urban women (APC: 34.4). During the 1990s among urban women, the rate of DCIS was still increasing (APC: 3.8), while there was no increase among rural women (APC: 0.2). Differences between rural and urban women within these 3 states were also identified. Conclusions: The data suggest differences in utilization of mammography between both populations; the increase was lower and started later for rural women. Possible reasons for such differences over time are discussed.
Use of Program Logic Models in the Southern Rural Access Program Evaluation
Authors: Pathman Donald , Thaker Samruddhi , Ricketts Thomas C. , Albright Jennifer B.
Published: April 2008

Abstract: The Southern Rural Access Program (SRAP) evaluation team used program logic models to clarify grantees' activities, objectives, and timelines. This information was used to benchmark data from grantees' progress reports to assess the program's successes. This article presents a brief background on the use of program logic models‐essentially charts or diagrams specifying a program's planned activities, objectives, and goals–for evaluating and managing a program. It discusses the structure of the logic models chosen for the SRAP and how the model concept was introduced to the grantees to promote acceptance and use of the models. The article describes how the models helped clarify the program's objectives and helped lead agencies plan and manage the many program initiatives and subcontractors in their states. Models also provided a framework for grantees to report their progress to the National Program Ofice and evaluators and promoted the evaluators' visibility and acceptance by the grantees. Program logics, however, increased grantees' reporting requirements and demanded substantial time of the evaluators. Program logic models, on balance, proved their merit in the SRAP through their contributions to its management and evaluation and by providing a better understanding of the program's initiatives, successes, and potential impact
A Community Development Approach to Rural Recruitment
Authors: Shannon C. Ken
Published: April 2008

Abstract:Programs designed to empower rural communities for health care provider recruitment have usually focused on the health care sector without aggressively addressing broader community development issues. The Recruitable Community Project (RCP) in West Virginia includes community education on recruiting and also assessments of and recommendations to rural communities on broad‐based community development, aiming to enhance communities' recruiting potential. The project provides multidisciplinary university‐based planning assistance programs for small communities, involving collaborative community visits. The project also uses a project manager as a “community encourager” who participates in community education and in the formulation of sustained community recruiting efforts. From August 1999 through August 2001, 7 underserved rural communities completed the RCP organizational processes and hosted planning assistance teams. Members of community recruitment boards gave high marks to the RCP process, its planning assistance teams, and its usefulness in establishing community ties to state and academic agencies. Since working with the RCP, the 7 communities have recruited 27 providers, success possibly stimulated by their RCP involvement (data current as of September 2002). This model of community training and development to empower rural communities to better recruit health professionals shows early promise. This model could be broadened to include more collaboration of community development and health science disciplines programs for recruitment and retention efforts
Getting From Here to There: Evaluating West Virginia's Rural Nonemergency Medical Transportation Program
Authors: Bellamy Gail R. , Stone Kendall , Richardson Sally K. , Goldsteen Raymond L.
Published: April 2008

Abstract:With funding from the 21st Century Challenge Fund, the West Virginia Rural Health Access Program created Transportation for Health. a demonstration project for rural nonemergency medical transportation. The project was implemented in 3 sites around the state, building on existing transportation systems–specifically, a multicounty transit authority, a joint senior center/transit system, and a senior services center. An evaluation of the project was undertaken to answer 3 major questions: (1) Did the project reach the population of people who need transportation assistance? (2) Are users of the transportation project satisfied with the service? (3) Is the program sustainable? Preliminary results from survey data indicate that the answers to questions 1 and 2 are affirmative. A break‐even analysis of all 3 sites begins to identify programmatic and policy issues that challenge the likelihood of financial sustainability, including salary expenses, unreimbursed mileage, and reliance on Medicaid reimbursement
Lessons Learned in Phase I of the Southern Rural Access Program
Authors: Beachler Michael , Holloman Curtis , Pathman Donald E.
Published: April 2008

Abstract: The Robert Wood Johnson Foundation's Southern Rural Access Program has been an important investment of philanthropic funds to augment resources and improve health care access in underserved rural communities. The program's first phase has taught important lessons about building capacity in rural health care. This article uses a variety of data to document the program's major accomplishments and most significant challenges to date. The program's revolving loan fund efforts are promising. The program has also played a catalytic role in stimulating rural health network development in the South and has helped stimulate partnerships with Southern philanthropies and multiple local, state, and federal agencies. Challenges have included the broad geographic and programmatic focus of the initiative as well as changing and often difficult state policy environments. Additional challenges include maintaining interagency coordination over time and managing staff and lead agency turnover. Overall, the experience suggests that a concentrated regional approach has merit
Scuffing Performance of a Hard Coating Under EHL Conditions at
Sliding Speeds up to 16m∕s and Contact Pressures up
to 2.0GPa
Authors: Snidle R. W. , Dhulipalla A. K. , Evans H. P. , Cooper C. V.
Published: April 2008

Scuffing experiments were conducted using 76mm diameter disks both with and without a metal-containing, carbon-based hard coating. The operating conditions in the experiments were severe with sliding speeds up to 16m∕s and maximum Hertzian contact pressures up to 2.0GPa. The disks were of alloy steel, which was case carburized and hardened followed by axial grinding. Four different surface conditions were investigated as follows: ground/uncoated, ground/coated, superfinished/uncoated, and superfinished/coated. Experiments were also carried out in which ground/coated disks were run against ground/uncoated disks. The results of the experiments show that the addition of the hard coating to the ground disks significantly improved both their scuffing resistance and frictional behavior, but the coating was less effective in producing an improvement in the durability and friction of the superfinished disks.
Numerical Analysis of Thermoelastohydrodynamic Behavior of Elastomer
Radial Lip Seals
Authors: Maoui A. , Hajjam M. , Bonneau D.
Published: April 2008

This work is a numerical analysis of the thermal effect on the elastohydrodynamic behavior of elastomer radial lip seals. Two thermal approaches are considered, a local approach that determines the distribution of temperature in the contact zone and a simplified global approach that considers a mean temperature of fluid film. In addition, the thermoelastic behavior of the lip surface is taken into account with a relationship between Young’s modulus and the mean temperature of the lip surface. It is shown that the local temperature of the contact zone increases sensitively according to the shaft speed. Moreover, all operating characteristics such as film thickness and power loss are significantly influenced by the local temperature effect.
Study of the Effect of Type (Cu, Ti and Cu, Mo) Electrospark Coatings on Friction in Pin-on-Disk Testing
Authors: Bogdan Antoszewski , Emil Evin , Jaromír Audy
Published: April 2008

Recent advances in the commercial exploitation of electrospark coatings have focused on improving surface roughness by depositing Ti, Mo, V, or W over an interlayer of Cu, Sn, Pb, or Cd on the top of a tool steel material. This paper presents results of a systematic pin-on-disk experimental study of different type bilayer coatings (Cu–Sn/bronze, bottom layer; Ti and Mo, top layer) deposited on a Type 45 steel. The results are discussed in terms of friction coefficients obtained under different dry-friction conditions (speeds ranging from 0.3m∕sto0.8m∕s, and pressures ranging from 10Nto40N). An additional focus is on scuffling resistance of faces in friction, microhardness and surface roughness of coated items, and the competitive advantage of using advanced surface coatings.
The Shear-Thinning Elastohydrodynamic Film Thickness of a Two-Component Mixture
Authors: Liu Yuchuan , Wang Q. Jane , Krupka Ivan , Hartl Martin , Bair Scott
Published: April 2008

Lubricant base oils are often blends of different molecular weight cuts to arrive at a specified ambient pressure viscosity and, to improve the temperature-viscosity behavior or to simply increase the viscosity, viscosity-modifying polymer additives are often added to the base oil. This paper investigates the effect of mixture rheology on elastohydrodynamic lubrication (EHL) film thickness using EHL contact measurements and a full numerical analysis for three synthetic lubricants including two single-component lubricants PAO650 and PAO100 and a mixture of these. The pressure and shear dependences of the viscosity of these lubricants were measured with high-pressure viscometers; viscosities were not adjusted to fit experiment. The point contact film thicknesses for these lubricants in pure rolling were measured using a thin-film colorimetric interferometry apparatus. Numerical simulations based on the measured rheology show very good agreement with the measurements of film thickness while the Newtonian prediction is up to twice the measurement. These results validate the use of realistic shear-thinning and pressure-viscosity models, which originate from viscosity measurements. It is conceivable that simulation may provide a means to “engineer” lubricants with the optimum balance of film thickness and friction through intelligent mixing of components.
Control of a Passive Mobility Assist Robot
Authors: Ryu Ji-Chul , Pathak Kaustubh , Agrawal Sunil K.
Published: April 2008

In this paper, a control methodology for a mobility assist robot is presented. There are various types of robots that can help persons with disabilities. Among these, mobile robots can help to guide a subject from one place to the other. Broadly, the mobile guidance robots can be classified into active and passive types. From a user’s safety point of view, passive mobility assist robots are more desirable than the active robots. In this paper, a two-wheeled differentially driven mobile robot with a castor wheel is considered the assistive robot. The robot is made to have passive mobility characteristics by a specific choice of control law, which creates damperlike resistive forces on the wheels. The paper describes the dynamic model, the suggested control laws to achieve the passive behavior, and proof of concept experiments on a mobile robot at the University of Delaware. From a starting position, the assistive device guides the user to the goal in two phases. In the first phase, the user is guided to reach a goal position while pushing the robot through a handle attached to it. At the end of this first phase, the robot may not have the desired orientation. In the second phase, it is assumed that the user does not apply any further pushing force while the robot corrects the heading angle. A control algorithm is suggested for each phase. In the second phase, the desired heading angle is achieved at the cost of deviations from the final position. This excursion from the goal position is minimized by the controller. This control scheme is first verified in computer simulation. Then, it is implemented on a laboratory system that simulates a person pushing the robot, and the experimental results are presented.
Determining the Fatigue Life of Dental Implants
Authors: Ilieş Horea T. , Flanagan Dennis , McCullough Paul T. , McQuoid Scott
Published: April 2008

Dental implants are used to retain and support fixed and removable dental prostheses. In many clinical situations, local bone morphology requires dental implants that have a diameter that is significantly smaller than the typical implant diameters. In these cases, the fatigue life of the smaller diameter implants becomes a critical therapeutic parameter. However, this fatigue life depends on the implant itself, on the physical properties of the bone, as well as on other morphological characteristics that are patient dependent. In other words, this fatigue life varies greatly with each newly placed implant, but the capability to predict the fatigue life of dental implants does not exist today. In this paper, we present the first steps towards establishing such a methodology. We develop a finite element based fatigue model for rigidly mounted dental implants, and correlate its results with both analytical predictions as well as physical measurements. This implies that such a model can be used as a valid predictor of fatigue life of dental implants themselves, and can be used as a valuable implant design tool. Furthermore, we present the design of a cost effective device to measure the fatigue life of dental implants that can be either rigidly or bone mounted (in vitro). This device was used to measure the fatigue life of an initial sample of nine dental implants, and we show that the results predicted by the finite element model correlated well with our initial experimental results.
The Diabetic Foot Load Monitor: A Portable Device for Real-Time Subject-Specific Measurements of Deep Plantar Tissue Stresses During Gait
Authors: Atlas Eran , Yizhar Ziva , Gefen Amit
Published: April 2008

Elevated stresses in deep plantar tissue of diabetic neuropathic patients were associated with an increased risk for foot ulceration, but only interfacial foot pressures are currently measured to evaluate susceptibility to ulcers. The goals of this study were to develop a real-time patient-specific plantar tissue stress monitor based on the Hertz contact theory. The biomechanical model for stress calculations considers the heel and metatarsal head pads, where most ulcers occur. For calculating stress concentrations around the bone-pad interface, plantar tissue is idealized as elastic and incompressible semi-infinite bulk (with properties measured by indentation), which is penetrated by a rigid sphere with the bone’s radius of curvature (from X-ray). Hertz’s theory is used to solve the bone-pad mechanical interactions, after introducing correction coefficients to consider large deformations. Foot-shoe forces are measured to solve and display the principal compressive, tensile, and von Mises plantar tissue stresses in real time. Our system can be miniaturized in a handheld computer, allowing plantar stress monitoring in the patient’s natural environment. Small groups of healthy subjects (N=6) and diabetic patients (N=3) participated in an evaluation study in which the differences between free walking and treadmill walking were examined. We also compared gait on a flat surface to gait on an ascending/descending slope of 3.5deg and when ascending/descending stairs. Peak internal compression stress was about threefold greater than the interface pressure at the calcaneus region. Subjects who were inexperience in treadmill walking displayed high gait-cycle variability in the internal stresses as well as poor foot loading. There was no statistical difference between gait on a flat surface and gait when ascending/descending a slope. Internal stresses under the calcaneus during gait on a flat surface, however, were significantly higher than when ascending/descending stairs. We conclude that the present stress monitor is a promising tool for real-time patient-specific evaluation of deep tissue stresses, providing valuable information in the effort to protect diabetic patients from foot ulceration. Clinical studies are now underway to identify which stress parameters can distinguish between diabetic and normal subjects; these parameters may be used for establishing injury threshold criteria.
A Patient-Mounted, Telerobotic Tool for CT-Guided Percutaneous Interventions
Authors: Walsh Conor J. , Hanumara Nevan C. , Slocum Alexander H. , Shepard Jo-Anne , Gupta Rajiv
Published: April 2008

This paper describes Robopsy, an economical, patient-mounted, telerobotic, needle guidance and insertion system, that enables faster, more accurate targeting during CT-guided biopsies and other percutaneous interventions. The current state of the art imaging technology facilitates precise location of sites within the body; however, there is no mechanical equivalent to then facilitate precise targeting. The lightweight, disposable actuator unit, which affixes directly to the patient, is composed primarily of inexpensive, injection molded, radiolucent, plastic parts that snap together, whereas the four micromotors and control electronics are retained and reused. By attaching to a patient, via an adhesive pad and optional strap points, the device moves passively with patient motion and is thus inherently safe. The device’s mechanism tilts the needle to a two degree-of-freedom compound angle, toward the patient’s head or feet (in and out of the scanner bore) and left or right with respect to the CT slice, via two motor-actuated concentric, crossed, and partially nested hoops. A carriage rides in the hoops and interfaces with the needle via a two degree-of-freedom friction drive that both grips the needle and inserts it. This is accomplished by two rubber rollers, one passive and one driven, that grip the needle via a rack and pinion drive. Gripping is doctor controlled; thus when not actively being manipulated, the needle is released and allowed to oscillate within a defined region so as to minimize tissue laceration due to the patient breathing. Compared to many other small robots intended for medical applications, Robopsy is an order of magnitude less costly and lighter while offering appropriate functionality to improve patient care and procedural efficiency. This demonstrates the feasibility of developing cost-effective disposable medical robots, which could enable their more widespread application.
Two-dimensional poroelastic acoustical foam shape design for absorption coefficient maximization by topology optimization method
Authors: Lee Joong Seok , Kim Yoon Young , Kim Jung Soo , Kang Yeon June
Published: April 2008

Optimal shape design of a two-dimensional poroelastic acoustical foam is formulated as a topology optimization problem. For a poroelastic acoustical system consisting of an air region and a poroelastic foam region, two different physical regions are continuously changed in an iterative design process. To automatically account for the moving interfaces between two regions, we propose a new unified model to analyze the whole poroelastic acoustical foam system with one set of governing equations; Biot’s equations are modified with a material property interpolation from a topology optimization method. With the unified analysis model, we carry out two-dimensional optimal shape design of a poroelastic acoustical foam by a gradient-based topology optimization setting. The specific objective is the maximization of the absorption coefficient in low and middle ranges of frequencies with different amounts of a poroelastic material. The performances of the obtained shapes are compared with those of well-known wedge shapes, and the improvement of absorption is physically interpreted.
Comodulation detection differences in children and adults
Authors: Hall Joseph W. , Buss Emily , Grose John H.
Published: April 2008

This study investigated comodulation detection differences (CDD) in children (ages 4.8–10.1years) and adults. The signal was 30-Hz wide band of noise centered on 2kHz, and the masker consisted of six 30-Hz wide bands of noise spanning center frequencies from 870to4160Hz. The envelopes of the masking bands were always comodulated, and the envelope of the signal was either comodulated or random with respect to the masker. In some conditions, the maskers were gated on prior to the signal in order to minimize effects related to perceptual fusion of the signal and masker. CDD was computed as the difference between signal detection thresholds in conditions where all bands were comodulated and conditions where the envelope of the signal was random with respect to the envelopes of the maskers. Values of CDD were generally small in children compared to adults. In contrast, masking release related to masker/signal onset asynchrony was comparable across age groups. The small CDDs in children are discussed in terms of sensitivity to comodulation as a perceptual fusion cue and informational masking associated with the detection of a signal in a complex background, an effect that is ameliorated by asynchronous onset.
Negative dispersion in bone: The role of interference in measurements of the apparent phase velocity of two temporally overlapping signals
Authors: Bauer Adam Q. , Marutyan Karen R. , Holland Mark R. , Miller James G.
Published: April 2008

In this study the attenuation coefficient and dispersion (frequency dependence of phase velocity) are measured using a phase sensitive (piezoelectric) receiver in a phantom in which two temporally overlapping signals are detected, analogous to the fast and slow waves typically found in measurements of cancellous bone. The phantom consisted of a flat and parallel Plexiglas™ plate into which a step discontinuity was milled. The phase velocity and attenuation coefficient of the plate were measured using both broadband and narrowband data and were calculated using standard magnitude and phase spectroscopy techniques. The observed frequency dependence of the phase velocity and attenuation coefficient exhibit significant changes in their frequency dependences as the interrogating ultrasonic field is translated across the step discontinuity of the plate. Negative dispersion is observed at specific spatial locations of the plate at which the attenuation coefficient rises linearly with frequency, a behavior analogous to that of bone measurements reported in the literature. For all sites investigated, broadband and narrowband data (3–7MHz) demonstrate excellent consistency. Evidence suggests that the interference between the two signals simultaneously reaching the phase sensitive piezoelectric receiver is responsible for this negative dispersion.
Acoustics of marine sediment under compaction: Binary grain-size model and viscoelastic extension of Biot’s theory
Authors: Leurer Klaus C. , Brown Colin
Published: April 2008

This paper presents a model of acoustic wave propagation in unconsolidated marine sediment, including compaction, using a concept of a simplified sediment structure, modeled as a binary grain-size sphere pack. Compressional- and shear-wave velocities and attenuation follow from a combination of Biot’s model, used as the general framework, and two viscoelastic extensions resulting in complex grain and frame moduli, respectively. An effective-grain model accounts for the viscoelasticity arising from local fluid flow in expandable clay minerals in clay-bearing sediments. A viscoelastic-contact model describes local fluid flow at the grain contacts. Porosity, density, and the structural Biot parameters (permeability, pore size, structure factor) as a function of pressure follow from the binary model, so that the remaining input parameters to the acoustic model consist solely of the mass fractions and the known mechanical properties of each constituent (e.g., carbonates, sand, clay, and expandable clay) of the sediment, effective pressure, or depth, and the environmental parameters (water depth, salinity, temperature). Velocity and attenuation as a function of pressure from the model are in good agreement with data on coarse- and fine-grained unconsolidated marine sediments.
Pulse-rate discrimination by cochlear-implant and normal-hearing listeners with and without binaural cues
Authors: Carlyon Robert P. , Long Christopher J. , Deeks John M.
Published: April 2008

Experiment 1 measured rate discrimination of electric pulse trains by bilateral cochlear implant (CI) users, for standard rates of 100, 200, and 300pps. In the diotic condition the pulses were presented simultaneously to the two ears. Consistent with previous results with unilateral stimulation, performance deteriorated at higher standard rates. In the signal interval of each trial in the dichotic condition, the standard rate was presented to the left ear and the (higher) signal rate was presented to the right ear; the non-signal intervals were the same as in the diotic condition. Performance in the dichotic condition was better for some listeners than in the diotic condition for standard rates of 100 and 200pps, but not at 300pps. It is concluded that the deterioration in rate discrimination observed for CI users at high rates cannot be alleviated by the introduction of a binaural cue, and is unlikely to be limited solely by central pitch processes. Experiment 2 performed an analogous experiment in which 300-pps acoustic pulse trains were bandpass filtered (3900–5400Hz) and presented in a noise background to normal-hearing listeners. Unlike the results of experiment 1, performance was superior in the dichotic than in the diotic condition.
The decay of pitch memory during rehearsal
Authors: Kaernbach Christian , Schlemmer Kathrin
Published: April 2008

The present study investigates the decay of pitch memory over time. In a delayed pitch comparison paradigm, participants had to memorize the pitch of a Shepard tone, with silent, overt, or without any rehearsal. During overt rehearsal, recordings of the rehearsing were effectuated. Performance was best for silent rehearsal and worst for overt rehearsal. The differences, although partially significant, were not marked. The voice pitch during overt rehearsal was compatible with a random walk model, providing a possible explanation of why rehearsal does not improve the retention of the pitch trace.