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At least 163 records · Page 9Linked to original sources
PubMed2004

A framework for assessing risks to children from exposure to environmental agents.

In recent years there has been an increasing focus in environmental risk assessment on children as a potentially susceptible population. There also has been growing recognition of the need for a systematic approach for organizing, evaluating, and incorporating the available data on children's susceptibilities in risk assessments. In this article we present a conceptual framework for assessing risks to children from environmental exposures. The proposed framework builds on the problem formulation-->analysis-->risk characterization paradigm, identifying at each phase the questions and issues of particular importance for characterizing risks to the developing organism (from conception through organ maturation). The framework is presented and discussed from the complementary perspectives of toxicokinetics and toxicodynamics.

Child↗
PubMed1989

The significance of empathy in current hospital based practice.

This paper examines empathy as a practice component that is particularly significant in its relationship to self-determination in the discharge process in acute hospital settings. Empathy is also emphasized as an essential ingredient to a psychosocial assessment that leads to accurate problem formulation and preciseness in planning. Current theories on empathy are discussed in a literature review, while pertinent practice issues are presented in several case vignettes. Theory and practice confirm that empathic skills can develop on both sentient and cognitive levels over time. This development is enhanced by supervision that utilizes the worker's capacity for self-awareness.

Adult↗
PubMed2025

Algorithms to reconstruct past indels: The deletion-only parsimony problem.

Ancestral sequence reconstruction is an important task in bioinformatics, with applications ranging from protein engineering to the study of genome evolution. When sequences can only undergo substitutions, optimal reconstructions can be efficiently computed using well-known algorithms. However, accounting for indels in ancestral reconstructions is much harder. First, for biologically-relevant problem formulations, no polynomial-time exact algorithms are available. Second, multiple reconstructions are often equally parsimonious or likely, making it crucial to correctly display uncertainty in the results. Here, we consider a parsimony approach where only deletions are allowed, while addressing the aforementioned limitations. First, we describe an exact algorithm to obtain all the optimal solutions. The algorithm runs in polynomial time if only one solution is sought. Second, we show that all possible optimal reconstructions for a fixed node can be represented using a graph computable in polynomial time. While previous studies have proposed graph-based representations of ancestral reconstructions, this result is the first to offer a solid mathematical justification for this approach. Finally we provide arguments for the relevance of the deletion-only case for the general case.

Algorithms↗
PubMed1985

Does physicians' knowledge of costing related to clinical decision making change the consumption of resources despite unchanged medical standards?

The problem formulation of the present project was as expressed in the title, with a secondary approach that if a difference could be measured, its magnitude would have to be evaluated in relation to the total bed day price of the study period, amounting to DKR 3600. The investigation comprised a hidden and an open phase, each covering 2 months, April-May and September-October 1983. During the second phase all physicians of the department inserted prices in the case records for all clinical decisions, consumption of utensils, drugs, X-ray investigations, clinical-chemical analyses, clinical-physiological analyses, ultrasonographies, endoscopies, and visits by specialist consultants. The price setting was done from a price catalogue made for the study, in accordance with either existing prices or prices calculated for the present purpose. During the first hidden phase it was possible to calculate the total price of all clinical interventions by secondarily applying prices as in phase 2. In this manner it was possible to create a starting level representing a period in which none of the participants had any idea of the later health economy study. In both phases 293 patients entered, with an identical distribution of age, sex, admittance periods, and so forth. The total sum of registered interventions for phase 1 was DKR 612,839 and for phase 2, DKR 532,515, giving a reduction of approximately 13%, corresponding to total expenses per day within the subgroups mentioned of DKR 199 in phase 1 and DKR 176 in phase 2. These sums must be judged in relation to the bed day price for the study phases.(ABSTRACT TRUNCATED AT 250 WORDS)

Costs and Cost Analysis↗
PubMed2005

Challenges in systematic reviews: synthesis of topics related to the delivery, organization, and financing of health care.

Some important health policy topics, such as those related to the delivery, organization, and financing of health care, present substantial challenges to established methods for evidence synthesis. For example, such reviews may ask: What is the effect of for-profit versus not-for-profit delivery of care on patient outcomes? Or, which strategies are the most effective for promoting preventive care? This paper describes innovative methods for synthesizing evidence related to the delivery, organization, and financing of health care. We found 13 systematic reviews on these topics that described novel methodologic approaches. Several of these syntheses used 3 approaches: conceptual frameworks to inform problem formulation, systematic searches that included nontraditional literature sources, and hybrid synthesis methods that included simulations to address key gaps in the literature. As the primary literature on these topics expands, so will opportunities to develop additional novel methods for performing high-quality comprehensive syntheses.

Decision Support Techniques↗
PubMed2000

A cognitive task analysis for dental hygiene.

To be an effective assessment tool, a simulation-based examination must be able to evoke and interpret observable evidence about targeted knowledge, strategies, and skills in a manner that is logical and defensible. Dental Interactive Simulations Corporation's first assessment effort is the development of a scoring algorithm for a simulation-based dental hygiene initial licensure examination. The first phase in developing a scoring system is the completion of a cognitive task analysis (CTA) of the dental hygiene domain. In the first step of the CTA, a specifications map was generated to provide a framework of the tasks and knowledge that are important to the practice of dental hygiene. Using this framework, broad classes of behaviors that would tend to distinguish along the dental hygiene expert-novice continuum were identified. Nine paper-based cases were then designed with the expectation that the solutions of expert, competent, and novice dental hygienists would differ. Interviews were conducted with thirty-one dental hygiene students/practitioners to capture solutions to the paper-based cases. Transcripts of the interviews were analyzed to identify performance features that distinguish among the interviewees on the basis of their expertise. These features were more detailed and empirically grounded than the originating broad classes and better serve to ground the design of a scoring system. The resulting performance features were collapsed into nine major categories: 1) gathering and using information, 2) formulating problems and investigating hypotheses, 3) communication and language, 4) scripting behavior, 5) ethics, 6) patient assessment, 7) treatment planning, 8) treatment, and 9) evaluation. The results of the CTA provide critical information for defining the necessary elements of a simulation-based dental hygiene examination.

Algorithms↗
PubMed2000

[Shape optimization of the femoral component of hip prosthesis using the finite element method].

Aseptic loosening of implants in bone is the main reason of prosthesis failure. Stress distribution around the implant surface plays a major role in this process, which can be minimized by implant shape optimization. Numerical methods, particularly the finite element method, are an important tool in the analysis of stress distribution and design optimization. The paper presents the problem formulation for this method, illustrated by computational examples.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

Evidence-based dentistry: Part IV. Research design and levels of evidence.

Previous papers in this series on evidence-based dentistry have discussed the first 2 steps in seeking answers to clinical problems formulating a clear question and strategically searching for evidence. The next step, critical appraisal of the evidence, is made easier if one understands the basic concepts of clinical research design. The strongest design, especially for questions related to therapeutic or preventive interventions, is the randomized, controlled trial. Questions relating to diagnosis, prognosis and causation are often studied with observational, rather than experimental, research designs. The strongest study design should be used whenever possible. Rules have been established to grade research evidence. This paper, the fourth in the series, presents an overview of research methodology most commonly used in the dental literature.

Case-Control Studies↗
PubMed2004

Robust reasoning with agent-based modeling.

Agent-based modeling (ABM) is a powerful representational formalism that has wide utility for modeling nonlinear systems. For ABM to achieve its potential as a scientific tool, our ability to build models that embody our knowledge must be complemented by rigorous means for making inferences using such models. Due to nonlinearity, this rigor cannot in general be based solely on demonstrating that a model reliably predicts the outcomes of available physical measurements. In this paper we describe an alternative approach to robust reasoning based on the concept of ensembles of alternative models. Ensembles of models can be defined that plausibly span classes of systems including the system of interest. Research methodologies for searching and sampling from such ensembles can be used to support plausible conclusions about invariant properties of ensembles of ABMs and hence of the classes of systems they represent. Notable among these are approaches that implement a competition between ensembles of problem formulations or challenges and conclusions robust to these challenges. This approach is demonstrated using examples drawn from our research.

Journal Article↗
PubMedDate not supplied

[New differentiation markers of mouse liver epithelial cell lines].

We describe two new markers of mouse liver epithelial cells detected by monoclonal antibodies. Immunomorphological localization of antigens was performed using light and electron microscopy. Antigen G7 is a marker of cholangiocytes and oval cells. Antigen A6 is present in cholangiocytes and oval cells; moreover, it is expressed in normal liver in single hepatocytes adjacent to the portal vein, in preneoplastic liver, in newly formed hepatocytes, and in certain hepatocarcinomas. Thus, antigen A6 is a marker of cholangiocytes, oval cells and of certain stages of hepatocyte differentiation. We also detected phenotypic heterogeneity of Gehring cells in terms of antigen A6 content. We have formulated problem of the relationship between A6-negative Gehring cells and liver stem cells. Both marker antigens are species-specific but are not specific for the liver. Antigen A6 is simultaneously a differentiation marker of cells belonging to the erythroid series. It is expressed in erythroblasts of fetal liver and is absent in erythroblasts of the yolk sac and erythrocytes. The relationship between antigen A6 and blood group antigens is discussed.

Animals↗
PubMedDate not supplied

[Microbiological synthesis of tetrapyrrole compounds].

This paper reviews publications on the biosynthesis of functional tetrapyrroles by microorganisms. Emphasis is given to the structure of uroporphyrin III methylated derivatives termed corriphyrins and their involvement in the formation of two groups of tetrapyrrole pigments--corrinoids and siroheme. Current concepts concerning the final stages of the formation of the corrine ring and potential cobalt-free precursors of vitamin B12 are discussed. It is indicated that the data available may help elucidate evolutionary and biogenetic patterns in the emergence and interaction of tetrapyrrole compounds and formulate problems of practical importance.

Ascitic Fluid↗
PubMed1978

[An approximate solution to the integral equation by using non serial cuts (author's transl)].

The problem formulated and resolved by WICKSELL is reformulated for a new technique of quantitative cytology utilizing non-serial cuts instead of serial sectioning. With a technique borrowed from numerical analysis an approximate solution can be obtained. Theoretical results are in agreement with experimental results obtained using a mixture of red blood cells from humans and rats.

Animals↗
PubMed1978

Helping patients to follow their treatment plans.

The optometrist encounters patients who do not adhere or comply with his recommended treatment. This problem of non-adherence adversely affects both the optometrist and the patient. A general framework is presented which the optometrist can use to evaluate his effectiveness at improving adherence. This framework includes problem formulation, joint development of the treatment plan, extended responsibility, and systematic followup.

Humans↗
PubMed1993

Health center-supplier team approach to solving i.v. equipment problems.

A team approach to problem solving in which a health care center and a supplier worked together to improve product quality is described and a detailed example is provided. When the health care center began using a new supplier for i.v. solutions and equipment, the supplier's incomplete product line and recurrent functional problems with products led to dissatisfaction of staff members. The supplier suggested that the health care center and supplier form a quality action team. The team addressed eight product concerns by using a total quality management process. For each concern, the team defined the problem and formulated a problem statement, collected data and determined the contributing factors to the problem, developed an action plan for solving the problem, and executed the plan and monitored its impact. After the first meeting, the team met monthly to monitor progress and discuss new ways they could work together to improve product quality and reduce costs. The implementation of the action plans allowed the health care center to realize cost savings and increased staff members' satisfaction with the supplier's products. A quality action team, composed of representatives from a health care center and one of its suppliers, used a total quality management process to solve problems to the satisfaction of both sets of participants.

California↗
PubMed1996

A conceptual framework to assess the risks of human disease following exposure to pathogens. ILSI Risk Science Institute Pathogen Risk Assessment Working Group.

Currently, risk assessments of the potential human health effects associated with exposure to pathogens are utilizing the conceptual framework that was developed to assess risks associated with chemical exposures. However, the applicability of the chemical framework is problematic due to many issues that are unique to assessing risks associated with pathogens. These include, but are not limited to, an assessment of pathogen/host interactions, consideration of secondary spread, consideration of short- and long-term immunity, and an assessment of conditions that allow the microorganism to propagate. To address this concern, a working group was convened to develop a conceptual framework to assess the risks of human disease associated with exposure to pathogenic microorganisms. The framework that was developed consists of three phases: problem formulation, analysis (which includes characterization of exposure and human health effects), and risk characterization. The framework emphasizes the dynamic and iterative nature of the risk assessment process, and allows wide latitude for planning and conducting risk assessments in diverse situations, each based on the common principles discussed in the framework.

Disease↗
PubMed1997

Fighting tuberculosis in the 1990s: how effective is planning in policy making?

Planning is a common tool for addressing important health issues, especially urgent ones, and has been reintroduced recently in several federal, state, and local public health programs. This article presents a case study of planning and policy making concerning the reemergence of tuberculosis in urban areas, using Washington, D.C. and New York City as examples. Planning was unsuccessful in D.C. because it failed to acknowledge the important political and bureaucratic aspects of policy making. In New York City, on the other hand, planning played a central role in policy-making efforts, and the health department took a leadership role in building a consensus on the problem, formulating strategies, and overcoming implementation obstacles. This article concludes with several key considerations for making planning more effective in health policy-making.

Communicable Disease Control↗
PubMed2003

Comparison of potential- and activation-based formulations for the inverse problem of electrocardiology.

Two predominant source formulations for the inverse problem of electrocardiology currently exist. They involve the reconstruction of epicardial potentials or myocardial activation times from noninvasively recorded torso surface potentials. Each of these formulations have their advantages, however, they have not been systematically compared against each other. We present results from a simulation study which compared a number of epicardial potential (Tikhonov, Truncated singular value decomposition (TSVD), Greensite-Tikhonov and Greensite-TSVD), and a myocardial activation time formulation for the inverse problem of electrocardiology. A number of different methods were also used to determine the appropriate level of regularization (optimal, L-curve, zero-crossing, and composite residual and smoothing operator) to apply to each formulation. The simulation study was conducted using an anatomically based boundary element porcine model with a variety of cardiac sources. Varying levels of geometric error were introduced to the system and solutions were computed using each of the inverse algorithms. Results show that under pure Gaussian noise potential-based methods performed best at low noise levels while the activation-based method was less effected by higher noise levels. In the presence of correlated geometric error, the activation-based method out performed the potential methods, with the Greensite-Tikhonov method being the most favored potential-based method when using the L-curve or zero-crossing method to determine the regularization parameter.

Algorithms↗