SEARCH · PubMed Health

Results for “Utility Theory”

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 811 records · Page 45Linked to original sources

PubMed2005

Neurofeedback in adolescents and adults with attention deficit hyperactivity disorder.

Neurofeedback is being utilized more commonly today in treating individuals who have attention deficit hyperactivity disorder (ADHD). Neurofeedback, which is based on theories that recognize the organic basis of ADHD, utilizes biofeedback to guide individuals to regulate their brain activity. Neurofeedback relies on research that has demonstrated that most individuals who have ADHD, as compared to matched peers, have excess slow wave activity and reduced fast wave activity. It provides immediate feedback to the individual about his or her brain wave activity in the form of a video game, whose action is influenced by the individual's meeting predetermined thresholds of brain activity. Over several sessions of using the video and auditory feedback, individuals reduce their slow wave activity and/or increase their fast wave activity. Individuals who complete a course of training sessions often show reduced primary ADHD symptoms. Research has shown that neurofeedback outcomes compare favorably to those of stimulant medication.

Adolescent↗

PubMed1989

Small-scale deceit: deception as a marker of two-, three-, and four-year-olds' early theories of mind.

This research report summarizes the results of a study into the abilities of 2-, 3-, and 4-year-old children to deceptively lead others into false beliefs, and is intended to help arbitrate a growing controversy as to when young persons first acquire some theory-like understanding of other minds. Utilizing a novel hide-and-seek board game as a context within which to observe children's spontaneous use of deceptive strategies, a total of 50 subjects between the ages of 2 1/2 and 5 were tested. In contrast to the competing findings of others, which are claimed to establish that children younger than approximately 4 suffer a cognitive deficit that wholly blocks them from the possibility of entertaining any sort of contrastive beliefs about beliefs, the results of this study show that even 2 1/2-year-olds are capable of already successfully employing a range of deceptive strategies that both trade upon an awareness of the possibility of false beliefs and presuppose some already operative theory of mind.

Attention↗

PubMed1999

Fundamentals of health risk assessment. Use, derivation, validity and limitations of safety indices.

We investigated the way results of human health risk assessments are used, and the theory used to describe those methods, sometimes called the "NAS paradigm." Contrary to a key tenet of that theory, current methods have strictly limited utility. The characterizations now considered standard, Safety Indices such as "Acceptable Daily Intake," "Reference Dose," and so on, usefully inform only decisions that require a choice between two policy alternatives (e.g., approve a food additive or not), decided solely on the basis of a finding of safety. Risk is characterized as the quotient of one of these Safety Indices divided by an estimate of exposure: a quotient greater than one implies that the situation may be considered safe. Such decisions are very widespread, both in the U.S. federal government and elsewhere. No current method is universal; different policies lead to different practices, for example, in California's "Proposition 65," where statutory provisions specify some practices. Further, an important kind of human health risk assessment is not recognized by this theory: this kind characterizes risk as likelihood of harm, given estimates of exposure consequent to various decision choices. Likelihood estimates are necessary whenever decision makers have many possible decision choices and must weigh more than two societal values, such as in EPA's implementation of "conventional air pollutants." These estimates can not be derived using current methods; different methods are needed. Our analysis suggests changes needed in both the theory and practice of human health risk assessment, and how what is done is depicted.

Air Pollutants↗

PubMedDate not supplied

Choosing and using theories in diabetes education research.

Diabetes educators use theories all the time, even if they are not aware of it. To teach, one must have some assumptions about how people learn and what constitutes effective teaching. The purpose of this article is to help diabetes educators interested in research and evaluation choose appropriate theories. The article will review the 4 purposes of theories, that is, description, explanation, prediction, and control, as well as the degree to which a theory has been articulated and elaborated. The importance of a theory's personal resonance, its explanatory power, and its utility will also be examined. The article will also review how to use 1 or more theories at each stage of a research or evaluation project.

Diabetes Mellitus↗

PubMed2005

The role of mentoring in developing African American nurse leaders.

The primary purpose of this study was to explore the role of mentoring in the development of African American nurses who have achieved leadership positions in baccalaureate and graduate nursing programs. This study also explored similar and dissimilar mentoring experiences in same-race versus cross-race mentoring relationships. The theoretical framework for this study was Levinson's adult developmental theory. A sequential mixed design was utilized. Forty-seven African American nurse leaders participated in Phase 1, and 10 of the 47 were interviewed in Phase 2. The findings showed that mentoring plays a role in the personal and professional development of African American nurse leaders in baccalaureate and graduate nursing programs. Moreover, the relevance of race varies in both same-race and cross-race mentoring relationships.

Adult↗

PubMed2003

Grounding a new information technology implementation framework in behavioral science: a systematic analysis of the literature on IT use.

Many interventions to improve the success of information technology (IT) implementations are grounded in behavioral science, using theories, and models to identify conditions and determinants of successful use. However, each model in the IT literature has evolved to address specific theoretical problems of particular disciplinary concerns, and each model has been tested and has evolved using, in most cases, a more or less restricted set of IT implementation procedures. Functionally, this limits the perspective for taking into account the multiple factors at the individual, group, and organizational levels that influence use behavior. While a rich body of literature has emerged, employing prominent models such as the Technology Adoption Model, Social-Cognitive Theory, and Diffusion of Innovation Theory, the complexity of defining a suitable multi-level intervention has largely been overlooked. A gap exists between the implementation of IT and the integration of theories and models that can be utilized to develop multi-level approaches to identify factors that impede usage behavior. We present a novel framework that is intended to guide synthesis of more than one theoretical perspective for the purpose of planning multi-level interventions to enhance IT use. This integrative framework is adapted from PRECEDE/PROCEDE, a conceptual framework used by health planners in hundreds of published studies to direct interventions that account for the multiple determinants of behavior. Since we claim that the literature on IT use behavior does not now include a multi-level approach, we undertook a systematic literature analysis to confirm this assertion. Our framework facilitated organizing this literature synthesis and our analysis was aimed at determining if the IT implementation approaches in the published literature were characterized by an approach that considered at least two levels of IT usage determinants. We found that while 61% of studies mentioned or referred to theory, none considered two or more levels. In other words, although the researchers employ behavioral theory, they omit two fundamental propositions: (1) IT usage is influenced by multiple factors and (2) interventions must be multi-dimensional. Our literature synthesis may provide additional insight into the reason for high failure rates associated with underutilized systems, and underscores the need to move beyond the current dominant approach that employs a single model to guide IT implementation plans that aim to address factors associated with IT acceptance and subsequent positive use behavior.

Attitude to Computers↗

PubMed2001

The Characterization of Microporous Activated Carbons Utilizing a Simple Adsorption Genetic Algorithm (SAGA).

The paper presents a new simple adsorption genetic algorithm (SAGA) which is based on the genetic theory of natural selection and rivalry. This algorithm is utilized to estimate the parameters of the Dubinin-Rhadushkevich equation. The obtained results are compared with these achieved from the classical optimization methods. The analysis of the error of fitting of the DR model to experimental data is discussed. It is shown that the proposed SAGA, contrary to the other methods, makes it possible to calculate the parameters of the DR equation not only very precisely but also very quickly. Copyright 2001 Academic Press.

Journal Article↗

PubMed2000

Coding in the noncoding DNA strand: A novel mechanism of gene evolution?

The question whether the noncoding DNA strand had or still has the capability for encoding functional polypeptides has been addressed in several articles. The theoretical background of the views advocating this idea arose from two groups of findings. One of them was based on various observations implying that the genetic code was adapted for double-strand coding. The other group of theories arose from the observation of gene-length overlapping open reading frames (O-ORFs) on the antisense DNA strand in a number of genes. In fact, the above theories, which I term selectionist, conceive a novel conception of gene evolution, proposing that new genes can be created by the utilization of antisense DNA strand. In contrast, neutralist theory claims that the O-ORFs are mere by-products of evolutionary processes acting to create special codon usage and base distribution patterns in the coding sequences.

Codon↗

PubMed2005

Motivation and burnout among top amateur rugby players.

INTRODUCTION: Self-determination theory has proven to be a useful theoretical explanation of the occurrence of ill-being on a variety of accounts. Self-determination theory may also provide a useful explanation of the occurrence of athlete burnout. To date, limited evidence exists to support links between motivation and burnout. PURPOSE: To examine relationships and potential causal directions among burnout and types of motivation differing in degree of self-determination. METHOD: Data were collected on burnout using the Athlete Burnout Questionnaire and Sport Motivation Scale from 392 top amateur male rugby players. Structural equation modeling procedures were employed to evaluate a measurement model and three conceptually grounded structural models. One conceptual model specified concomitant (noncausal) relationships between burnout and motivations varying in self-determination. The other conceptual models specified causal pathways between burnout and the three motivation variables considered in the investigation (i.e., intrinsic motivation, external regulation, and amotivation). RESULTS: Within the models, amotivation, the least self-determined type of motivation, had a large positive association with burnout. Externally regulated motivation had trivial and nonsignificant relationships with burnout. Self-determined forms of motivation (i.e., intrinsic motivation) exhibited significant negative associations with burnout. CONCLUSIONS: Overall the results support the potential utility of a self-determination theory explanation of burnout. As all models displayed reasonable and comparable fits, further research is required to establish the nature (concomitant vs directional causal vs reciprocal causal) of the relationship between burnout and motivation.

Adolescent↗

PubMed1999

Thermodynamic prediction of active ingredient loading in polymeric microparticles.

The growing use of microparticles as a controlled-delivery system for pharmaceutical and non-pharmaceutical active ingredients (AIs) has prompted a costly trial-and-error development of new and effective microparticle systems. In order to facilitate a more rational design and optimization of AI loadings in microparticles, we have developed a molecular-thermodynamic theory to predict the loading of liquid AIs in polymeric microparticles that are manufactured by a solvent evaporation process. This process involves the emulsification of a liquid polymer solution (consisting of polymer and AI dissolved in a volatile solvent) in an aqueous surfactant solution. The theory describes the equilibrium distribution of the AI between the aqueous phase and the dispersed polymeric droplets. The universal functional activity coefficient (UNIFAC) and UNIFAC-Free Volume (FV) group-contribution methods are utilized to model the nonidealities in the water and polymeric droplet phases, respectively. The inputs to the theory are: (i) the chemical structures, densities and total masses of the manufacturing ingredients, (ii) the manufacturing temperature and (iii) the glass transition temperature of the polymer. Since surfactant concentrations exceeding the critical micellar concentration (CMC) are often required in order to stabilize the dispersed polymeric droplets during the emulsion manufacturing process, the theory also accounts for AI solubilization in surfactant micelles present in the manufacturing solution. To test the AI loading predictions, we compare theoretical predictions of AI loadings in poly(lactic acid), poly(methyl methacrylate) and polystyrene microparticles to experimentally measured ones for five model AIs with varying degrees of hydrophobicity (benzyl alcohol, n-octanol, geraniol, farnesol and galaxolide). We also demonstrate how the developed theory can be utilized to screen polymers with respect to their abilities to load a given AI, as well as to provide guidelines for manufacturing microparticles having the desired AI loading.

Drug Delivery Systems↗

PubMed1977

Ionic permeability of K, Na, and Cl in crayfish nerve. Regulation by membrane fixed charges and pH.

Teorell's fixed charge theory for membrane ion permeability was utilized to calculate specific ionic permeabilities from measurements of membrane potential, conductance, and specific ionic transference numbers. The results were compared with the passive ionic conductances calculated from the branched equivalent circuit membrane model of Hodgkin Huxley. Ionic permeabilities for potassium, sodium, and chloride of crayfish (Procambarus clarkii) medial giant axons were examined over an external pH range from 3.8 to 11.4. Action potentials were obtained over this pH range. Failures occurred below pH 3.8 during protonation of membrane phospholipid phosphate and carboxyl, and above pH 11.4 from calcium precipitation. In general, chloride permeability increases with membrane protonation, while cation permeability decreases. At pH 7.0, PK = 1.33 X 10(-5), PCl = 1.49 X 10(-6), PNa = 1.92 X 10(-8) cm/s. PK: PCl: PNa = 693:78:1. PCl is zero above pH 10.6 and is opened predominately by protonation of epsilon-amino, and partially by tyrosine and sulfhydryl groups from pH 10.6 to 9. PK is activated in part by ionization of phospholipid phosphate and carboxyl around pH 4, then further by imidazole from pH 5 to 7, and then predominately from pH 7 to 9 by most probably phosphatidic acid. PNa permeability parallels that of potassium from pH 5 to 9.4. Below pH 5 and above pH 9.4, PNa increases while PK decreases. Evidence was obtained that these ions possibly share common passive permeable channels. The data best support the theory of Teorell, that membrane fixed charges regulate permiability and that essentially every membrane ionizable group appears involved in various amounts in ionic permeability control.

Action Potentials↗

PubMed2001

Time Preference for Health: A Test of Stationarity versus Decreasing Timing Aversion.

This paper provides a new and more robust test of the descriptive validity of the constant rate discounted utility model in medical decision analysis. The constant rate discounted utility model is compared with two competing theories, Harvey's (1986) proportional discounting model and Loewenstein and Prelec's (1992) hyperbolic discounting model. To compare the various intertemporal models, previous studies on intertemporal preferences for health assumed a specific parametric form of the utility function for life-years and no discounting within the time periods that health states are experienced. The present study avoids such confounding assumptions by focusing on the axiomatic structure of the discounting models. The present study further differs by using choices instead of matching to elicit intertemporal preferences. The experimental results provide support for decreasing timing aversion, the condition underlying the proportional and the hyperbolic discounting model, but they violate stationarity, the central condition of the constant rate discounted utility model. There is some ambiguity whether the violations of stationarity are primarily caused by an immediacy effect. The results confirm violations of stationarity in choice-based elicitations tasks, in contrast with the results from Ahlbrecht and Weber (1997) which supported stationarity in choices over monetary outcomes. Copyright 2001 Academic Press.

Journal Article↗

PubMed2005

Prediction of conformational characteristics and micellar solution properties of fluorocarbon surfactants.

A molecular-thermodynamic theory is developed to model the micellization of fluorocarbon surfactants in aqueous solutions, by combining a molecular model that evaluates the free energy of micellization of fluorocarbon surfactant micelles with a previously developed thermodynamic framework describing the free energy of the micellar solution. In the molecular model of micellization developed, a single-chain mean-field theory is combined with an appropriate rotational isomeric state model of fluorocarbon chains to describe the packing of the fluorocarbon surfactant tails inside the micelle core. Utilizing this single-chain mean-field theory, the packing free energies of fluorocarbon surfactants are evaluated and compared with those of their hydrocarbon analogues. We find that the greater rigidity of the fluorocarbon chain promotes its packing in micellar aggregates of low curvatures, such as bilayers. In addition, the mean-field approach is utilized to predict the average conformational characteristics (specifically, the bond order parameters) of fluorocarbon and hydrocarbon surfactant tails within the micelle core, and the predictions are found to agree well with the available experimental results. The electrostatic effects in fluorocarbon ionic surfactant micelles are modeled by allowing for counterion binding onto the charged micelle surface, which accounts explicitly for the effect of the counterion type on the micellar solution properties. In addition, a theoretical formulation is developed to evaluate the free energy of micellization and the size distribution of finite disklike micelles, which often form in the case of fluorocarbon surfactants. We find that, compared to their hydrocarbon analogues, fluorocarbon surfactants exhibit a greater tendency to form cylindrical or disklike micelles, as a result of their larger molecular volume as well as due to the greater conformational rigidity of the fluorocarbon tails. The molecular-thermodynamic theory developed is then applied to several ionic fluorocarbon surfactant-electrolyte systems, including perfluoroalkanoates and perfluorosulfonates with added LiCl or NH(4)Cl, and various micellar solution properties, including critical micelle concentrations (cmc's), optimal micelle shapes, and average micelle aggregation numbers, are predicted. The predicted micellar solution properties agree reasonably well with the available experimental results.

Journal Article↗

PubMed2001

Rerating capacity of a constructed wetland treatment system.

The 482-hectare (ha) City of Orlando (Florida) Easterly Wetlands (OEW) was designed to reduce nutrient concentrations in 0.90 m3/s of wastewater from the Iron Bridge Regional Water Reclamation Facility. Design influent nutrient concentrations were 6 mg/L total nitrogen (TN) and 0.75 mg/L total phosphorus (TP). Actual TN and TP concentrations have been less than design, averaging 2.6 mg/L and 0.29 mg/L, respectively from January 1988 through December 1999. If influent concentrations remain at these levels, the OEW may have the potential to treat significantly higher flows since less than 20% of the total area was utilized for nutrient reduction. To test this theory, a capacity study was performed for approximately nine months in 1997 and 1998. Simulated flows of approximately 1.26 m3/s, 1.66 m3/s, and 1.93 m3/s were tested. It was found that approximately 15% of the area was utilized for nutrient reduction during the 1.26 m3/s simulation, 35% in the 1.66 m3/s, and 1.93 m3/s simulations. Based on these testing results, an application was submitted to the state in early 2000 to increase the permitted capacity to 1.57 m3/s.

Biodegradation, Environmental↗

PubMed2002

Evaluation of a "loss-framed" minimal intervention to increase mammography utilization among medically un- and under-insured women.

This study was conducted because mammography is under-utilized, even though it is the most effective early detection screening device for breast cancer. A loss-framed telephonic message based on prospect theory was evaluated for the effects on mammography utilization among medically un- and under-insured women living in demographically similar rural counties in Florida. The sample consisted mostly of White women (approximately 89%) 50-64 years old. Experimental group participants received the loss-framed message telephonically and those in the comparison group received the "usual telephone procedure." Logistic regression analyses revealed that women who received the loss-framed message were six times more likely to obtain a mammogram (OR = 6.6, P < 0.0001). The impact of the loss-framed message persisted even after adjustment for initial versus re-screen mammogram effects. This in-reach, loss-framed, minimal intervention seems to have viability and may serve as an alternative or adjunct program for encouraging women to receive mammograms.

Attitude to Health↗

PubMed2000

Quantitation of intermolecular dipolar effects in NMR spectroscopy and high order MSE MR imaging.

An analytical expression for intermolecular dipolar effects was derived for the CRAZED sequence with an arbitrary flip angle of the second RF pulse and time-varying gradients. A combination of the demagnetizing field theory and product operator formalism was utilized in the derivation. It is demonstrated that the time-averaged, not instantaneous, orientation of the applied gradients determines the contributions of long-range intermolecular dipole effects. An imaging sequence to detect intermolecular dipolar effects was designed. The second- and third-order multiple spin echo (MSE) NMR signals of swine muscle were observed and were found to be in good agreement with the theoretical predictions. MSE images of a water phantom with nth orders (n = 2, - 3, - 4, and - 5) were also obtained, and their relative signal intensities and optimized TE values were elucidated and compared with the theoretical prediction.

Animals↗

PubMed2006

Risk factors associated with the transition from heroin sniffing to heroin injection: a street addict role perspective.

The purpose of this paper is to identify characteristics of heroin sniffers likely to shift to injection by evaluating the street addict role theory as an informing theoretical framework to explain transition from heroin sniffing to injection. A nested case-control research design was used to identify 142 heroin sniffers who never had injected a drug (controls) and 146 recently transitioned injection drug users (cases) from a larger study of 600 African-American, Hispanic, and non-Hispanic white men and women who were street recruited from multiple communities known for high drug use. Univariate and multivariate logistic regression analyses were conducted to test the proposed hypotheses derived from the street addict role theory. Our findings partially support the utility of the street addict role perspective as an explanatory framework for understanding the role played by sociocultural factors in the transition to injection. This perspective can help contextualize this HIV-related behavior within the high risk social environment of heroin users. The development of effective prevention strategies for this group should be guided by a comprehensive understanding of the social environment where HIV-related risk behaviors occur.

Administration, Inhalation↗

PubMed1985

Analysis and optimization of recombinant DNA joining reactions.

The statistical segment length of duplex DNA was determined in phage T4 ligase (poly(deoxyribonucleotide): poly(deoxyribonucleotide) ligase (AMP forming), EC 6.5.1.1) buffer (50 mM-Tris . HCl (pH 7.8), 20 mM-dithiothreitol, 10 mM-MgCl2, 1 mM-ATP) at 12 degrees C to be 1030(+/- 116) A. This result was obtained by electron microscopic examination of the molecular distributions generated by T4 ligase-mediated joining of EcoRI-cleaved pBR322 DNA. This value of the statistical segment length was utilized in an extension of the Jacobson-Stockmayer theory on the probability of intramolecular cyclization in order to optimize DNA joining reactions that are of great utility in recombinant DNA experiments. Five cloning systems were analyzed: circular plasmid vectors that had been linearized with one or two restriction endonucleases, circular plasmids that had been tailed with deoxyhomopolymers before joining, lambda-type cloning vectors and cosmids. The results are tabulated for convenient use in molecular cloning experiments.

Cloning, Molecular↗