PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Models, Theoretical”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources
PubMed1997

Likelihood-ratio decision strategy for independent observations in the same-different task: an approximation to the detection-theoretic model.

An optimal decision strategy for deciding whether two things are the same or different is to adopt a likelihood-ratio criterion. The parametric equations for the receiver operating characteristic (ROC) based on the likelihood-ratio strategy when observations are independent are complicated; they require the numerical evaluation of a double integral. An approximation to the parametric equations for the likelihood-ratio strategy was developed. This approximation takes the form of a pair of equations that describe ROCs virtually indistinguishable from those of the full model.

Decision Making↗
PubMedDate not supplied

[Theoretical model of homopolymer chain adsorption on a homogenous surface].

On the basis of I. M. Lifshitz's theory the adsorption of the homopolymer on the homogenous surface is considered. It is shown that the attraction of monomers to the surface may lead not only to adsorption of the globule or coil but also to the emergence of a new peculiar phase--dislike globule without the fringe, all the monomers of which are stuck to the surface. A two-dimensional phase-diagram is plotted.

Adsorption↗
PubMedDate not supplied

Adequate peritoneal dialysis: theoretical model and patient treatment.

The objective of this study was to evaluate the relationship between adequate PD with sufficient weekly Kt/V (2.0) and Creatinine clearance (CCR) (60l) and necessary daily dialysate volume. This recommended parameter was the result of a recent multi-centre study (CANUSA). For this there were 40 patients in our hospital examined and compared in 1996, who carried out PD for at least 8 weeks and up to 6 years. These goals (CANUSA) are easily attainable in the early treatment of many individuals with a low body surface area (BSA). With higher BSA or missing RRF (Residual Renal Function) the daily dose of dialysis must be adjusted. We found it difficult to obtain the recommended parameters and tried to find a solution to this problem. The simplest method is to increase the volume or exchange rate. The most expensive method is to change from CAPD to APD with the possibility of higher volume or exchange rates. Selection of therapy must take into consideration: 1. patient preference, 2. body mass, 3. peritoneal transport rates, 4. ability to perform therapy, 5. cost of therapy and 6. risk of peritonitis. With this information in mind, an individual prescription can be formulated and matched to the appropriate modality of PD.

Body Surface Area↗
PubMed1999

A theoretical model for the study of active and passive smoking in military women: an at-risk population.

This paper presents a model designed for the study of active and passive smoking in military women with children. Some constructs have been adapted from a transtheoretical model of behavior change. Transtheoretical model constructs of relevance to this model include (1) stages of behavior change, (2) decisional balance, and (3) self-efficacy. Other model constructs include (1) personal and situational factors, (2) a mother's self-efficacy to reduce the child's smoke exposure, (3) a mother's expectation for the child's smoke exposure, (4) smoke avoidance, (5) nicotine dependence, and (6) social support for quitting smoking. The occurrence of health problems associated with smoking is the outcome variable. The results of a study under way at present may support the use of this model and may make data available to substantiate the need for behavior-specific interventions designed to prevent and reduce active and passive smoking among military personnel.

Adult↗
PubMed2000

Theoretical models of interactions between buspirone analogues and 5-HT1A and 5-HT2A serotonin receptor subtypes.

In present study the structure-selectivity relationship of buspirone and six of its analogues towards 5-HT1A and 5-HT2A serotonin receptors was investigated on molecular level. Molecular mechanics energy minimisation and advanced molecular dynamics (MD) simulations allowed us to perform a dynamic structural analysis of transmembrane helical domains of the human 5-HT1A and 5-HT2A receptors and investigate the ligand-induced changes of the entire structure of the ligand-receptor complex. The obtained results suggest, that helical and extracellular domains of both receptors have different topography of the putative binding sites and also different dynamical behaviour. The results of this study are consistent with experimental site-directed mutagenesis data and binding affinities of examined ligands towards both serotonin receptors.

Binding Sites↗
PubMed2002

Entropic elasticity in the generation of muscle force--a theoretical model.

A novel simplified structural model of sarcomeric force production in striate muscle is presented. Using some simple assumptions regarding the distribution of myosin spring lengths at different sliding velocities it is possible to derive a very simple expression showing the main components of the experimentally observed force-velocity relationship of muscle: nonlinearity during contraction (Hill, 1938), maximal force production during stretching equal to two times the isometric force (Katz, 1939), yielding at high stretching velocity, slightly concave force-extension relationship during sudden length changes (Ford et al., 1977; Lombardi & Piazzesi, 1990), accurate reproduction of the rate of ATP consumption (Shirakawa et al., 2000; He et al., 2000) and of the extra energy liberation rate (Hill, 1964a). Different assumptions regarding the force-length relationship of individual cross-bridges are explored [linear, power function and worm-like chain (WLC) model based], and it is shown that the best results are obtained if the individual myosin-spring forces are modelled using a WLC model, thus hinting that entropic elasticity could be the main source of force in myosin undergoing the conformational changes associated with the power stroke.

Animals↗
PubMed2002

[German-language reconstruction of the processes of behavior change according to the trans-theoretical model in participants of women's fun run].

OBJECTIVES: For the first time the German version of the key construct "processes of change" for exercise behaviour is presented. Specific aims were to find out whether 10 different processes of change can be ascertained and whether the processes of change are also organised into a higher level of order. METHODS: The data are part of a cross-sectional study. The participants were 1208 women of the fun run in Graz in 2000. Exploratory factor analysis and structural equation models were conducted to reconstruct the German version of the processes of change. RESULTS: 822 women (68%) returned the questionnaire. The variance, limited to a 10-factor-solution, was 67.6%. In comparison to the construct derived from the theory, subscales show a change of items. The fit-indices of the two hierarchical-factor model (NNFI = 0.92, CFI = 0.94) and of the three hierarchical-factor model (NNFI = 0.91, CFI = 0.94) show better overall fit than the one hierarchical-factor model (NNFI = 0.86, CFI = 0.89). CONCLUSIONS: According to the change of items between the subscales in comparison to the theory it is recommended to test the German version again in a population-based sample. The overall fit indices support the assumption that the 10 processes of change follow an hierarchical order.

Adult↗
PubMed1992

Disease, illness and health: theoretical models of the disablement process.

Handicap is the result of a process of disablement whose origin is a pathological condition (disease). According to some definitions of health (e.g., a state of complete physical, mental and social well-being), the classical biomedical concept is too restrictive to cover all the consequences of disease. New models have been proposed: the impairment-disability-handicap model presented by WHO, the situational handicap model, and the quality-of-life model. A unifying schema of the disablement process includes these concepts and provides a useful way of analysing the consequences of disease. Factors that modify the disablement process can be identified by their respective impacts, and provide operational guidelines for public health interventions.

Disability Evaluation↗
PubMed1992

Self-organisation of cognitive processes and psychosis. Development and test of a theoretical model.

The development of a theory of self-control of brain processes leads to a model of disturbance of integration of brain processes in psychotic persons. The theory is that the "novelty-familiarity relation" of the current state of the processed information normally dominates the current mode of information processing. In the second part of the study adults with schizophrenia in remission and children with infantile autism were tested as to the manner in which they used newly introduced elements. The psychotic persons took the different character of the new elements less into consideration. The difference from the normal control persons is significant.

Adolescent↗
PubMed1992

Occupational health nursing: a theoretical model.

Predictability must exist in occupational health nursing theory, as it does in other theory. Occupational health nursing can be examined within a simple, dynamic model, from which theory can be developed. Predictions of output can be derived from knowledge of input. Occupational health nursing is a vital component of the occupational health and safety team, the members of which collaborate to provide occupational health services to the aggregate of workers in the workplace. Delivery of occupational health services to workers is provided within a dynamic environment which can be analyzed as both internal and external. The elements of these environments determine the composition and characteristics of the occupational health services.

Humans↗