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PubMed2000

External peer review in Europe: an overview from the ExPeRT Project. External Peer Review Techniques.

OBJECTIVE: This paper aims to evaluate the use and development of external peer review models and to identify where the main models are used in European Union member states and countries with reciprocal research agreements with the European Union. DESIGN: The ExPeRT (external peer review techniques) project research team conducted a series of fact-finding missions to all participating European nations. Study participants. I. Blomberg, Sweden; L. Bohigas, Spain; S. Cucic, The Netherlands; P. Morosini, Italy. The Project is led by C. Shaw, UK and is managed by C. Heaton, CASPE Research. RESULTS: We identified four main external peer review models aimed at measuring the quality of service management and delivery: health care accreditation, the International Organization for Standardization ISO 9000 standards, the European Foundation for Quality Management Excellence Model and visitatie, which is Dutch for 'visitation' or peer review-based schemes. DISCUSSION: ExPeRT has demonstrated that in principle, convergence of the four main models in order to gain from each model's key strengths is feasible. Whether convergence is practical, depends upon the willingness of governments, health service providers, health care quality professionals and organizations to come together and adopt the recommendations of the ExPeRT project.

Accreditation↗
PubMed2005

Comparison of deformable and elastic foundation finite element simulations for predicting knee replacement mechanics.

Rigid body total knee replacement (TKR) models with tibiofemoral contact based on elastic foundation (EF) theory utilize simple contact pressure-surface overclosure relationships to estimate joint mechanics, and require significantly less computational time than corresponding deformable finite element (FE) methods. However, potential differences in predicted kinematics between these representations are currently not well understood, and it is unclear if the estimates of contact area and pressure are acceptable. Therefore, the objectives of the current study were to develop rigid EF and deformable FE models of tibiofemoral contact, and to compare predicted kinematics and contact mechanics from both representations during gait loading conditions with three different implant designs. Linear and nonlinear contact pressure-surface overclosure relationships based on polyethylene material properties were developed using EF theory. All other variables being equal, rigid body FE models accurately estimated kinematics predicted by fully deformable FE models and required only 2% of the analysis time. As expected, the linear EF contact model sufficiently approximated trends for peak contact pressures, but overestimated the deformable results by up to 30%. The nonlinear EF contact model more accurately reproduced trends and magnitudes of the deformable analysis, with maximum differences of approximately 15% at the peak pressures during the gait cycle. All contact area predictions agreed in trend and magnitude. Using rigid models, edge-loading conditions resulted in substantial overestimation of peak pressure. Optimal nonlinear EF contact relationships were developed for specific TKR designs for use in parametric or repetitive analyses where computational time is paramount. The explicit FE analysis method utilized here provides a unique approach in that both rigid and deformable analyses can be run from the same input file, thus enabling simple selection of the most appropriate representation for the analysis of interest.

Arthroplasty, Replacement, Knee↗
PubMed2003

Near-infrared spectroscopic monitoring of a series of industrial batch processes using a bilinear grey model.

A good process understanding is the foundation for process optimization, process monitoring, end-point detection, and estimation of the end-product quality. Performing good process measurements and the construction of process models will contribute to a better process understanding. To improve the process knowledge it is common to build process models. These models are often based on first principles such as kinetic rates or mass balances. These types of models are also known as hard or white models. White models are characterized by being generally applicable but often having only a reasonable fit to real process data. Other commonly used types of models are empirical or black-box models such as regression and neural nets. Black-box models are characterized by having a good data fit but they lack a chemically meaningful model interpretation. Alternative models are grey models, which are combinations of white models and black models. The aim of a grey model is to combine the advantages of both black-box models and white models. In a qualitative case study of monitoring industrial batches using near-infrared (NIR) spectroscopy, it is shown that grey models are a good tool for detecting batch-to-batch variations and an excellent tool for process diagnosis compared to common spectroscopic monitoring tools.

Chemical Industry↗
PubMed2000

The suicidal mode: a cognitive-behavioral model of suicidality.

This article discusses the theoretical foundation and potential clinical application of the suicidal mode, a cognitive behavioral theory of suicidality. The model presented represents a specific elaboration of Beck's modal theory of psychopathology. In addition to discussing the fundamental requirements of a theory of suicidality, the theoretical assumptions of the suicidal mode are identified, its component parts defined, its inherent strengths emphasized, and its application in clinical settings detailed. Definition of a modal theory of suicidality represents the growing influence of cognitive-behavioral theory in efforts at psychotherapeutic integration in clinical suicidology.

Cognitive Behavioral Therapy↗
PubMed2000

Simulation-based medical planning for cardiovascular disease: visualization system foundations.

A technique for visualizing computational models along with volumetric imaging data in a real-time, interactive, simulation-based medical planning system for cardiovascular disease treatment is described. This technique involves an ordered rendering of faceted geometry and volumetric image data. We have developed a software system based on this image-fusion technique that is capable of capturing and representing the inherent anatomic constraints of an individual patient. Such constraints must be represented accurately in a medical planning system to ensure the validity of a potential procedure. A hypothetical clinical scenario is described for which vascular treatment plans were constructed pre-operatively without reference to the physical anatomic structure. These models were later embedded into patient-specific diagnostic MRA scans to establish the anatomic context for physiologic observations.

Algorithms↗
PubMed2006

Evolutionary model selection with a genetic algorithm: a case study using stem RNA.

The choice of a probabilistic model to describe sequence evolution can and should be justified. Underfitting the data through the use of overly simplistic models may miss out on interesting phenomena and lead to incorrect inferences. Overfitting the data with models that are too complex may ascribe biological meaning to statistical artifacts and result in falsely significant findings. We describe a likelihood-based approach for evolutionary model selection. The procedure employs a genetic algorithm (GA) to quickly explore a combinatorially large set of all possible time-reversible Markov models with a fixed number of substitution rates. When applied to stem RNA data subject to well-understood evolutionary forces, the models found by the GA 1) capture the expected overall rate patterns a priori; 2) fit the data better than the best available models based on a priori assumptions, suggesting subtle substitution patterns not previously recognized; 3) cannot be rejected in favor of the general reversible model, implying that the evolution of stem RNA sequences can be explained well with only a few substitution rate parameters; and 4) perform well on simulated data, both in terms of goodness of fit and the ability to estimate evolutionary rates. We also investigate the utility of several distance measures for comparing and contrasting inferred evolutionary models. Using widely available small computer clusters, our approach allows, for the first time, to evaluate the performance of existing RNA evolutionary models by comparing them with a large pool of candidate models and to validate common modeling assumptions. In addition, the new method provides the foundation for rigorous selection and comparison of substitution models for other types of sequence data.

Algorithms↗
PubMed1999

[The "Hersbruck Model". Application and integration of the DIN EN ISO 9001 quality norms with criteria of the European Foundation for Quality Management in a clinic].

The german health system has dramatically changed and still continues to do so. Modified aspects concerning economy, customer orientation, competition, quality assurance and quality management seem to be increasingly important. Appropriate response to this challenge demands a relevant adjustment of a quality "philosophy" within a hospital. The "Hersbruck Model" has proven to be a suitable approach: on the basis of a quality management system--established and certified according to DIN EN ISO 9001--it implements all components of the model of the European Foundation for Quality Management. The modern quality tools as Total Quality Management and continuous quality improvement allow a permanent increase of customer/patient satisfaction.

Europe↗
PubMed2003

Cornerstones to shape modeling for the 21st century: introducing the AKA-Glucose project.

In this paper, we have reflected on the historical development during the twentieth century of several major cornerstones on which the edifice of mathematical modeling in nutrition and the health sciences was built. When we consider the scope and magnitude of problems in nutrition and the health sciences that have been addressed and solved by mathematical modeling, we as a group can justifiably feel a certain amount of satisfaction. But we should not be complacent. So much more remains to be done. The increasing pace of developments in biology (e.g., the human genome project) places a whole new range of challenges before us. We can also reflect on the mathematical basis of modeling and consider that we enter the twenty-first century with a solid foundation on which to build bigger and better models. At the same time, we have at our disposal computers of immense power. At the start of the twentieth century, no one could have foreseen where we are today. In our lifetimes, computers have been developed from lumbering behemoths with the calculating ability of an abacus to the present day machines with calculating capabilitie that we are only beginning to appreciate. There is general consensus that developments in the field of computing will continue far into the twenty-first century. Therefore, w can confidently assert that developments in modeling will not be greatly limited by our present mathematical foundation or by the capabilities of computers. In this paper, we have mainly dwelt on three cornerstones: the model development environment model dissemination and database technologies data exchange and post-fitting analysis. We have focused on SAAM, WinSAAM, and AKA-Glucose as illustrating these cornerstones, while acknowledging that there are many other modeling programs that also represent them. However, a building usually has four cornerstones. If one cornerstone is missing, then there may be a structural weakness in the entire building. We contend that, at the start of the twenty-first century, the edifice of modeling is missing the important fourth cornerstone: a modeling community. As modelers, we should cease to bowl alone. Now is the time to make a new beginning, to give modeling some formality, structure, and direction. We should form a community of modelers as we move into the 21st century.

Computer Simulation↗
PubMed1980

Vector magnitude operation in color vision models: derivation from signal detection theory.

Using the theory of signal detection, we have derived an expression for the detectability of a visual stimulus in terms of the general zone theory of color and brightness vision. This derived relationship elicidates the theoretical foundation of the Guth vector model for color vision by showing that the nonlinear vector magnitude operation used by Guth may arise from the observer decision-making process. Testable predictions of stimulus detectability are generated by the derived expression.

Color Perception↗
PubMedDate not supplied

Opportunity cost: the impact of contextual risk factors on the cardiovascular health of low-income rural southern African American women.

Low-income rural southern African American women experience a high prevalence of morbidity and mortality from coronary heart disease (CHD) as well as other related cardiovascular (CV) diseases. Few models have taken into account the full impact of the contextual influences encountered on a daily basis by these women, and the effect of these influences on their CV health status. There are clearly demarcated examples of existing health disparities that occur in various ethnic/racial, underserved, and vulnerable populations. Yet, to date, there is no conceptual model that offers a plausible explanation as to why health disparities exist. Consequently, there is a lack of guidance as to where interventions should be focused for effective CV risk reduction. Because African American women continue to die at a disproportionately higher rate, and at earlier ages than do Caucasian women, it is imperative that new theoretical models capable of driving empirically based interventions be developed, tested, and implemented. One possible choice is the conceptual model proposed in this article. The model is based on the interrelationships between contextual risk factors, rational choice theory (RCT), and opportunity cost. Conceivably, this model may serve as a foundation to ground conceptual thought and drive theory-based interventions to reduce the health disparities in the CV health of low-income rural southern African American women. A model is presented in an attempt to provide guidance for advanced practice nurses who must struggle with addressing the critical need to reduce ethnic and race-associated CV health disparities.

Adaptation, Psychological↗
PubMed2000

Addicted to quality--winning the Dutch Quality Award based on the EFQM Model.

The Jellinek Center is a treatment service for prevention, care and cure of clients with addiction problems. Ten years ago the first quality improvement program was started. In 1994 the management team did the first formal self-assessment based on the European Foundation for Quality Management (EFQM) Model and three assessors from the "Instituut Nederlandse Kwaliteit" audited the Jellinek and delivered a feedback report which was used to make an elaborate two-year work-plan. Five projects to improve the quality of the Jellinek Center were identified and carried out. After two years, the work-plan was evaluated and the improvements assessed through a self-assessment conducted by the management team and an external audit team made up of six assessors. The findings of the self-assessment were presented to the Dutch jury for the EFQM Award and the Jellinek Center won the Dutch Quality Award. The Jellinek is not complacent, however, as it recognises that the next phase of the quality management journey is to carry out self-assessment in all teams, redesign the treatment processes and improve performance measurements.

Awards and Prizes↗
PubMed2006

A mathematical model for the kinetics of Methanobacterium bryantii M.o.H. considering hydrogen thresholds.

We develop a kinetic model that builds on the foundation of classic Monod kinetics, but incorporates new phenomena such as substrate thresholds and survival mode observed in experiments with the H2-oxidizing methanogen Methanobacterium bryantii M.o.H. We apply our model to the experimental data presented in our companion paper on H2 thresholds. The model accurately describes H2 consumption, CH4 generation, biomass growth, substrate thresholds, and survival state during batch experiments. Methane formation stops when its Gibbs free energy is equal zero, although this does not interrupt H2 oxidation. The thermodynamic threshold for H2 oxidation occurs when the free energy for oxidizing H2 and transferring electrons to biomass is no longer negative, at approximately 0.4 nM. This threshold is not controlled by the Gibbs free energy equation of methanogenesis from H2 + HCO3- as we show in our companion paper. Beyond this threshold, the microorganisms shift to a low-maintenance metabolism called "the survival state" in response to extended H2 starvation; adding the starvation response as another new feature of the kinetic model. A kinetic threshold (or S (min)), a natural feature of the Monod kinetics, is also captured by the model at H2 concentration of around approximately 2,400 nM. S (min) is the minimum substrate concentration to maintain steady-state biomass concentration. Our model will be useful for interpreting threshold results and designing new studies to understand thresholds and their ecological implications.

Computer Simulation↗
PubMed2002

Foundations of "new" social science: institutional legitimacy from philosophy, complexity science, postmodernism, and agent-based modeling.

Since the death of positivism in the 1970s, philosophers have turned their attention to scientific realism, evolutionary epistemology, and the Semantic Conception of Theories. Building on these trends, Campbellian Realism allows social scientists to accept real-world phenomena as criterion variables against which theories may be tested without denying the reality of individual interpretation and social construction. The Semantic Conception reduces the importance of axioms, but reaffirms the role of models and experiments. Philosophers now see models as "autonomous agents" that exert independent influence on the development of a science, in addition to theory and data. The inappropriate molding effects of math models on social behavior modeling are noted. Complexity science offers a "new" normal science epistemology focusing on order creation by self-organizing heterogeneous agents and agent-based models. The more responsible core of postmodernism builds on the idea that agents operate in a constantly changing web of interconnections among other agents. The connectionist agent-based models of complexity science draw on the same conception of social ontology as do postmodernists. These recent developments combine to provide foundations for a "new" social science centered on formal modeling not requiring the mathematical assumptions of agent homogeneity and equilibrium conditions. They give this "new" social science legitimacy in scientific circles that current social science approaches lack.

Journal Article↗
PubMed1990

Theoretical determination of force-length relations of intact human skeletal muscles using the cross-bridge model.

The purpose of this study was to determine force-length relations of selected human skeletal muscles, based on the theoretical foundations of the cross-bridge model and to calculate a strength curve for knee extension from these relations. Force-length relations were determined for the rectus femoris, vastus lateralis, vastus medialis, vastus intermedius and gastrocnemius muscles, using sarcomere/fiber length data form both legs of four cadavers and sarcomere geometry data reported in the literature. It appears that the two-joint muscles investigated in this study are not able to produce force throughout their full anatomical range of motion, whereas the one-joint muscles can. The strength curve for knee extension was determined as the sum of the force-length relations of the individual knee extensor muscles and showed good agreement with experimentally obtained knee extensor strength curves.

Aged↗
PubMed2006

Toward a comprehensive model of antisocial development: a dynamic systems approach.

The purpose of this article is to develop a preliminary comprehensive model of antisocial development based on dynamic systems principles. The model is built on the foundations of behavioral research on coercion theory. First, the authors focus on the principles of multistability, feedback, and nonlinear causality to reconceptualize real-time parent-child and peer processes. Second, they model the mechanisms by which these real-time processes give rise to negative developmental outcomes, which in turn feed back to determine real-time interactions. Third, they examine mechanisms of change and stability in early- and late-onset antisocial trajectories. Finally, novel clinical designs and predictions are introduced. The authors highlight new predictions and present studies that have tested aspects of the model

Adolescent↗
PubMed2005

[Study on application of Fourier transformation near-infrared spectroscopy analysis with support vector machine (SVM)].

Support Vector Machine (SVM) is a method for the research on identifying two types of problem. It is the latest branch in the statistics study theories, and the identification model has a strict mathematics foundation. In this paper, the basic principle and method of SVM are not only introduced, but also applied to chemometrics. One hundred and three rhubarb samples were used as experimental materials. The identification models were established with near-infrared spectroscopy and SVM training method with the intention of identifying whether the rhubarb samples are true or false. The thirty-three samples in training set were identified by the identifying models with the accurate rate of 100%, while seventy estimate samples had an accurate rate of 96.77%. The research result provided the method of identifying the traditional Chinese medicine rhubarb quickly. So, it shows the feasibility of establishing the models with near-infrared spectroscopy and SVM method to identify biological samples. This paper introduced the theme of SVM training method in order to beget the attention of the research members who deal with chemometrics.

Algorithms↗
PubMed2003

Navigating the road to implementation of the Health Insurance Portability and Accountability Act.

The Health Insurance Portability and Accountability Act of 1996 (HIPAA) has a profound impact on safety net providers. To help agencies afford expert consultation and provide the opportunity for collaboration, a regional health foundation has created the first model in the nation to bring together safety net providers to work toward implementation of the HIPAA.

Computer Communication Networks↗
PubMed1994

The RAETRAD model of radon generation and transport from soils into slab-on-grade houses.

Remediation planning and 222Rn-related construction zoning require knowledge of how close and strong 226Ra sources can be in different foundation soils under different groundwater conditions without excessively elevating indoor 222Rn levels. A two-dimensional numerical-analytical model was developed to simulate (a) 222Rn emanation, decay, and movement by diffusion and advection in soils around houses and in their understructures; and (b) 222Rn accumulation in a single-zone house. The model represents foundation soils and a house in elliptical-cylindrical geometry. 222Rn may diffuse through its floor slab or may enter via idealized cracks and openings. The model was validated with analytical calculations of two-dimensional air pressure fields and with one-dimensional calculations of 222Rn generation with diffusion and diffusion combined with advection. Agreement generally was within < 1% when finite-difference approximations were minimized. Benchmark comparisons with indoor 222Rn measurements in two test-cell structures under passive and depressurized conditions averaged within 11% of measured values, well within measurement uncertainty. The corresponding average bias was only 3%. Larger variations were observed when applying the model to 50 houses. In this application, a negative bias of nearly 50% was observed due to data gaps and to poorly-characterized floor slabs and crack distributions.

Diffusion↗