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At least 253 records · Page 14Linked to original sources
PubMed1995

Obstacles to donor eye procurement and their solutions at the University of Iowa.

Shortages in transplantable corneas are common, yet little appears in the medical literature about patterns of tissue donation and factors affecting procurement. We have analyzed data on eye donations and taken measures to improve procurement rates based on our findings. Fifty consecutive Cardiovascular Intensive Care Unit (CVICU) deaths were reviewed to compare the number of transplant-eligible donors to the amount of tissue received. An anonymous survey of 250 house staff and nurses was undertaken to identify obstacles to donor eye procurement. Although 12 of 50 potential donors in the CVICU met transplant eligibility criteria, only 1 became a donor. A required request policy notwithstanding, the most common reason for nonprocurement was failure to make a request. According to the survey, the most significant impediments to making the request were (a) not thinking to ask, (b) unfamiliarity with eligibility criteria, (c) unfamiliarity with enucleation procedures, (d) feeling that someone else should make the request, and (e) reluctance to impose on a grieving family. Very few cited religious reasons or being too busy. Education based on the specific concerns listed in the survey was undertaken. During the 12 months after this initiative, the number of transplantable corneas donated from our facility doubled, as compared with the same period in 1992. Despite required request laws and regulations, failure to request tissue donation is common in our facility and may be common elsewhere. Systematic analysis of obstacles to donor eye procurement and their solutions may help to improve our country's performance in this area.

Corneal Transplantation↗
PubMed2006

Access to adequate nutrition is a major potential obstacle to antiretroviral adherence among HIV-infected individuals in Rwanda.

Despite the massive expansion of antiretroviral drugs in Africa, little is known about the resulting changes in sexual behavior or obstacles to antiretroviral therapy (ART) adherence. Our evaluation of Rwandan adults on ART found no increase in risky sexual behaviors, but an obstacle to ART initiation and adherence for 76% of patients was a fear of developing too much appetite without enough to eat. Access to adequate nutrition may be a major determinant for long-term adherence to ART.

Adult↗
PubMed2003

Posttraumatic stress disorder, alcohol, and tribes: obstacles to research.

Based on research and clinical experiences on and off Indian reservations in California, Arizona, and New Mexico, the author shares his perspective on systemic obstacles to psychological research in Indian Country. Using those obstacles as a springboard, he maps the emergent epistemological differences between western and native approaches to gathering knowledge and engendering change. The resulting discussion suggests different ways in which research can be conceptualized with Indian tribes.

Alcoholism↗
PubMed2006

Preventing end-stage renal disease: flexible strategies to overcome obstacles.

PURPOSE OF REVIEW: Renin-angiotensin system inhibition has demonstrated effectiveness in clinical studies in slowing the progression of chronic kidney disease. This review analyzes obstacles that have hindered the attainment of optimal results in the renal community, and the need for flexible strategies in overcoming these obstacles. RECENT FINDINGS: Despite the publication of the beneficial effects of renin-angiotensin system inhibitors, an epidemic of end-stage renal disease has developed in the United States. Underprescription of these medicines, and failure to reach goals for blood pressure and urinary protein loss have contributed to this epidemic. Solutions to these problems require flexible analysis that contrasts with the more linear, rigid approaches recently popularized in various disease-management guidelines. The application of renin-angiotensin inhibitors, in an individualized goal-oriented manner sensitive to patient variations, is discussed. A similar approach to hypertension, emphasizing assessment of individual hemodynamic parameters, is proposed. The elimination of rigid limitations to increases in serum potassium and serum creatinine is suggested as a means to enhance prescription of renin-angiotensin system inhibitors. SUMMARY: Optimal treatment of chronic kidney disease requires flexible approaches towards achieving the goals for systolic blood pressure and reduction of urinary protein loss.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2006

Flow of foam past an elliptical obstacle.

To investigate the link between discrete small-scale and continuous large scale mechanical properties of a foam, we observe its two-dimensional flow in a channel, around an elliptical obstacle. We measure the drag, lift, and torque acting on the ellipse versus the angle between its major axis and the flow direction. The drag increases with the spanwise dimension, in marked contrast with a square obstacle. The lift passes through a smooth extremum at an angle close to, but smaller than 45 degrees. The torque peaks at a significantly smaller angle 26 degrees. No existing model can reproduce the observed viscous, elastic, plastic behavior. We propose a microscopic visco-elasto-plastic model which agrees qualitatively with the data.

Journal Article↗
PubMed2006

Flexible ring polymers in an obstacle environment: Molecular theory of linear viscoelasticity.

We formulate a coarse-grained mean-field approach to study the dynamics of the flexible ring polymer in any given obstacle (gel or melt) environment. The similarity of the static structure of the ring polymer with that of the ideal randomly branched polymer is exploited in formulating the dynamical model using aspects of the pom-pom model for branched polymers. The topological constraints are handled via the tube model framework. Based on our formulation we obtain expressions for diffusion coefficient D, relaxation times tau, and dynamic structure factor g(k,t). Further, based on the framework we develop a molecular theory of linear viscoelasticity for ring polymers in a given obstacle environment and derive the expression for the relaxation modulus G(t). The predictions of the theoretical model are in agreement with previously proposed scaling arguments and in qualitative agreement with the available experimental results for the melt of rings.

Journal Article↗
PubMed2004

Physicians' perceptions of possibilities and obstacles prior to implementing a computerised drug prescribing support system.

Seeks to identify physicians' perceptions of possibilities and obstacles prior to implementing a computerised drug prescribing support system. Details a descriptive, qualitative study, with semi-structured individual interviews of 21 physicians in the Accident and Emergency Department of South Stockholm General Hospital. Identifies four descriptive categories for possibilities and obstacles. Concludes that gaining access to patient drug history enables physicians to carry out work in a professional way--a need the computerised prescription support system was not developed for and thus cannot fulfil. Alerts and producer-independent drug information are valuable in reducing workload. However, technical prerequisites form the base for a successful implementation. Time must be given to adapt to new ways of working.

Attitude of Health Personnel↗
PubMed1997

Clockwise and counter-clockwise circulation of wavefronts around an anatomical obstacle as one mechanism of two morphologies of sustained ventricular tachycardia in patients after a corrective operation of tetralogy of Fallot.

Two different monomorphic VTs were observed in two patients after a corrective operation for tetralogy of Fallot. The activation pattern of the wavefronts of the two VTs were different: in a counter-clockwise direction around the anatomical obstacle due to a ventriculotomy of the right ventricle in one VT; and in a clockwise direction around the same obstacle in the other VT. The different revolutions of the wavefronts could be the mechanism for the different morphologies of VT.

Adolescent↗
PubMed2004

Adaptations in bilateral mechanical power patterns during obstacle avoidance reveal distinct control strategies for limb elevation versus limb progression.

The present study investigated the adaptations of specific power bursts during the combined contexts of the proximity (lead vs. trail limb) and height of an obstruction in relation to limb elevation versus progression. Ten young, adult, male subjects walked at their natural speed during unobstructed walking and the bilateral avoidance of moderate and high obstacles. Hip flexor generation power was unaffected by obstacle height for the leading limb and always delayed for the trailing limb. The knee extensor absorption power burst at toe-off was also eliminated for the trailing limb and was found to reappear in mid-swing. Few differences were seen for ankle push-off power. The results suggest that the hip joint is dedicated to limb advancement only, while the knee joint is directly involved in limb elevation and the control of multiarticular effects.

Adaptation, Physiological↗
PubMedDate not supplied

Online practice guidelines: issues, obstacles, and future prospects.

The "guidelines movement" was formed to reduce variability in practice, control costs, and improve patient care outcomes. Yet the overall impact on practice and outcomes has been disappointing. Evidence demonstrates that the most effective method of stimulating awareness of and compliance with best practices is computer-generated reminders provided at the point of care. This paper reviews five steps along the path from the development of a guideline to its integration into practice and the subsequent evaluation of its impact on practice and outcomes. Issues arising at each step and obstacles to moving from one step to the next are described. Last, developments that could help overcome the obstacles are highlighted. These include 1) more rapid knowledge acquisition using data mining, 2) better accommodation to imprecise knowledge in clinical algorithms using fuzzy logic, 3) development of a shareable model for guideline representation and execution, and 4) more widespread availability of clinically robust information systems that support decision-making at the point of care.

Algorithms↗
PubMed2006

Molecular-dynamics simulations with explicit hydrodynamics II: on the collision of polymers with molecular obstacles.

We present a study of the dynamics of single polymers colliding with molecular obstacles using Molecular-dynamics simulations. In concert with these simulations we present a generalized polymer-obstacle collision model which is applicable to a number of collision scenarios. The work focusses on three specific problems: i) a polymer driven by an external force colliding with a fixed microscopic post; ii) a polymer driven by a (plug-like) fluid flow colliding with a fixed microscopic post; and iii) a polymer driven by an external force colliding with a free polymer. In all three cases, we present a study of the length-dependent dynamics of the polymers involved. The simulation results are compared with calculations based on our generalized collision model. The generalized model yields analytical results in the first two instances (cases i) and ii)), while in the polymer-polymer collision example (case iii)) we obtain a series solution for the system dynamics. For the case of a polymer-polymer collision we find that a distinct V-shaped state exists as seen in experimental systems, though normally associated with collisions with multiple polymers. We suggest that this V-shaped state occurs due to an effective hydrodynamic counter flow generated by a net translational motion of the two-chain system.

Adsorption↗
PubMed2006

Running interference: prospects and obstacles to using small interfering RNAs as small molecule drugs.

RNA interference (RNAi) is a well-conserved, ubiquitous, endogenous mechanism that uses small noncoding RNAs to silence gene expression. The endogenous small RNAs, called microRNAs, are processed from hairpin precursors and regulate important genes involved in cell death, differentiation, and development. RNAi also protects the genome from invading genetic elements, encoded by transposons and viruses. When small double-stranded RNAs, called small interfering (si)RNAs, are introduced into cells, they bind to the endogenous RNAi machinery to disrupt the expression of mRNAs containing complementary sequences with high specificity. Any disease-causing gene and any cell type or tissue can potentially be targeted. This technique has been rapidly utilized for gene-function analysis and drug-target discovery and validation. Harnessing RNAi also holds great promise for therapy, although introducing siRNAs into cells in vivo remains an important obstacle. Pilot siRNA clinical studies began just three years after the discovery that RNAi works in mammalian cells. This review discusses recent progress and obstacles to using siRNAs as small molecule drugs.

Animals↗
PubMed2002

Controlling the statistics of action: obstacle avoidance.

Task optimization in the presence of signal-dependent noise (TOPS) has been proposed as a general framework for planning goal-directed movements. Within this framework, the motor command is assumed to be corrupted by signal-dependent noise, which leads to a distribution of possible movements. A task can then be equated with optimizing some function of the statistics of this distribution. We found the optimal trajectory for obstacle avoidance by minimizing the mean-squared error at the end of the movement while keeping the probability of collision with the obstacle below a fixed limit. The optimal paths accurately predicted the empirical trajectories. This demonstrates that controlling the statistics of movements in the presence of signal-dependent noise may be a fundamental and unifying principle of goal-directed movements.

Avoidance Learning↗
PubMedDate not supplied

Transformational obstacles in special education.

Practitioners in the field of special education who embrace an alternative paradigm for understanding and educating students with learning problems often face the challenge of "job role dissonance" in the daily execution of their responsibilities. Such dissonance arises when their attempt to shift paradigms or simply restructure current practice is impeded by institutional obstacles. From an experiential perspective, the authors examine these obstacles and how they have affected the reframing of the field of learning disabilities. Specifically, they identify legal mandates, the systemic nature of schools, parents' belief systems, and time limitations of staff as impediments to a more healthy and viable service delivery to children. Finally, dissonance is proffered as a normal component of a true restructuring movement.

Education, Special↗
PubMed1984

'A Look at the Chief Complaints' revisited. Current obstacles and opportunities for decision analysis.

In 1979, Dr. William Schwartz wrote a "Sounding Board" article in the New England Journal of Medicine entitled: "Decision Analysis. A Look at the Chief Complaints". In it, he listed the major concerns of practicing physicians, academicians, and students about decision analysis. As an educator and an advocate of the technique, he then replied to each of these concerns and objections. Dr. Schwartz's article is an excellent and thoughtful discussion and one that we routinely recommend to our students to prepare them for real-world reactions to the zeal with which they often leave our classrooms. Now, more than four years later, I would like briefly to review the "chief complaints" outlined by Dr. Schwartz and to update them to 1984. My purpose is to consider the cognitive and practical obstacles to the dissemination of decision analysis, and to discuss alternative approaches to surmounting these obstacles. To do this, I have engaged four "consultants" from different fields.

Attitude of Health Personnel↗
PubMed2006

Opportunities and obstacles for good work in nursing.

Good work in nursing is work that is scientifically effective as well as morally and socially responsible. The purpose of this study was to examine variables that sustain good work among entering nurses (with one to five years of experience) and experienced professional nurses despite the obstacles they encounter. In addition to role models and mentors, entering and experienced nurses identified team work, cohesiveness and shared values as levers for good work. These nurses used prioritization, team building and contemplative practices to overcome obstacles. Entering professional nurses tended to avoid conflict in the work setting. Experienced nurses reported forming teams of decision makers who share similar values to resolve conflict. These findings have implications for nurse education and nursing practice. Reflection on the importance of values and virtue in sustaining good work is important. Entering professional nurses should be encouraged to seek positive role models and reflect on the lessons that can be learned from experienced exemplary nurses.

Adaptation, Psychological↗
PubMed2001

Overcoming truth telling as an obstacle to initiating safer sex: clients and health practitioners planning deception during HIV test counseling.

This article considers how deception, as a strategy for handling delicate interpersonal situations, is raised and responded to during HIV pretest counseling sessions. Two cases are presented in which clients (CLs) formulate extrarelational sexual encounters as potential obstacles to initiating safer sex practices with long-term relational partners (because reinitiating safer sex with such partners would entail admission of the extrarelational encounters). Close analysis of spoken interaction reveals that CLs display their resistance to initiating safer sex by animating, through hypothetical dialogue, their long-term partners' requests for explanation of the disruption in their usual intimate behaviors; health practitioners attempt to overcome this obstacle of "truth telling" by suggesting deception in its place. This study extends current understandings of the formulation and planning of deceptive messages in the course of actual health promotion interactions. The implications of this investigation suggest that deception may pose a viable, albeit controversial, option when promoting disease prevention behaviors, especially in delicate interpersonal interactions such as not wanting to admit an extrarelational affair.

Adolescent↗
PubMed2001

Egocentric information helps desert ants to navigate around familiar obstacles.

Homing ants have been shown to associate directional information with familiar landmarks. The sight of these local cues might either directly guide the path of the ant or it might activate a landmark-based vector that points towards the goal position. In either case, the ants define their courses within allocentric systems of reference. Here, we show that desert ants, Cataglyphis fortis, forced to run along a devious path can use egocentric information as well. The ants were trained to deviate from their straight homebound course by a wide inconspicuous barrier that was placed between the feeding and nesting sites. At a distant test area, the ants were confronted with an identical barrier rotated through 45 degrees. After passing the edge of the obstacle, the ants did not proceed in the trained direction, defined by the skylight compass, but rotated their courses to match the rotation of the barrier. Visual guidance could be excluded because, as soon as the ants turned around the end of the barrier, the visual cue it provided vanished from their field of view. Instead, the ants must have maintained a constant angle relative to their previous walking trajectory along the obstacle and, hence, must have determined their new vector course in an egocentric way.

Animals↗