A general theory of ATP synthesis and utilization.
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Adenosine Diphosphate↗
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Results for “Utility Theory”
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Changing unit culture: an interdisciplinary commitment to improve pain outcomes.
Patients discharged from The Methodist Hospital, Houston, TX, are contacted post discharge and asked to assess the care provided; specific questions are focused on pain management. Responses to these questions were initially unfavorable: only approximately 72.4% of patients were completely satisfied. An interdisciplinary team was developed on an acute-care unit at the hospital to individualize pain management through daily rounds and improvements in nursing assessment. Kurt Lewin's change theory was utilized to improve patient outcomes and to bolster staff commitment to control pain more effectively--as evidenced by improved patient satisfaction scores to a high of 86% only 3 months following implementation of this new interdisciplinary program.
Benchmarking↗
Elements in the immunoglobulin heavy-chain enhancer directly regulate simian virus 40 ori-dependent DNA replication.
In a previous study, we showed that the immunoglobulin heavy-chain (IgH) enhancer (IgHe) is near or in an initiation zone of chromosomal DNA replication, which is preferentially active in B cells (K. Ariizumi, Z. Wang, and P. W. Tucker, Proc. Natl. Acad. Sci. USA 90:3695-3699, 1993). This suggests the existence of a functional relationship between IgHe-mediated transcription and DNA replication. To test this theory, we utilized simian virus 40 (SV40) DNA replication as a model of chromosomal replication. IgHe or its operationally divisible domains (5'-En, core, and 3'-En) were introduced into SV40 minichromosomes (IgHe-SV40). Results of replication assays with IgHe-SV40 replicons indicated that the 5'-En and 3'-En activated or suppressed SV40 DNA replication regardless of the presence of SV40 enhancers or promoters in these replicons. The activity did not reside in IgHe core sequences. The results suggested that the 5'- and 3'-En regulated SV40 replication through direct interaction with the origin, not through suppression at the SV40 enhancer and/or promoter. In an effort to identify elements within the 5'-En motif that contributed to this effect, we found that the E site, but not microE5 and microE2 boxes, upregulated DNA replication. Our results provide another possible regulatory function for the 5'-En and 3'-En domains besides transcriptional suppression of IgHe.
Animals↗
Relationship between frequency and amplitude dependence in the lung: a nonlinear block-structured modeling approach.
During lung constriction, there is an increase in both the frequency and tidal volume (VT) dependences of lung tissue resistance (Rti) and elastance (Eti). This suggests that 1) significant alterations take place in the mechanisms contributing to both the linear and nonlinear characteristics of lung tissues; and 2) the frequency and VT dependences of Rti and Eti are coupled. We examined these issues for the case of sine wave and special pseudorandom inputs by utilizing the theory of nonlinear block-structured systems. Two basic model structures were considered: the Hammerstein and the Wiener structures. The Hammerstein structure is a cascade connection of a nonlinear zero-memory (N) system and a linear dynamic process (L). This structure predicts that frequency and VT dependences of Rti and Eti are decoupled. The Wiener structure is an inverse cascade of these two blocks (i.e., L-N) in which the frequency and VT dependences of Rti and Eti are coupled. These two structures were combined with a nonlinear airway compartment and fitted to measured airway opening and alveolar capsule pressure-flow time domain data in dogs before and after histamine-induced constriction. The best lung model was a linear airway compartment combined with a Wiener structure consisting of a constant-phase linear tissue impedance in cascade with a polynomial nonlinearity, suggesting that frequency and VT dependences of Rti and Eti are indeed coupled during control and constricted conditions. Moreover, histamine caused much larger changes in the linear tissue parameters than in the nonlinear coefficients.(ABSTRACT TRUNCATED AT 250 WORDS)
Air Pressure↗
Mechanisms of the puromycin-induced defects in the transglomerular passage of water and macromolecules.
To investigate the mechanism(s) of increased filtration of serum proteins after glomerular injury, polydisperse samples of uncharged [(3)H]dextran (D) or anionic [(3)H]dextran sulfate (DS) were infused into 14 control and 16 puromycin aminonucleoside- (PAN) treated Munich-Wistar rats. Fractional clearances of D or DS ranging in radius from 18 to 42A were determined in these rats, together with direct measurements of the forces governing the glomerular filtration rate of water. Whole kidney and single nephron glomerular filtration rates were approximately 40% lower in PAN-treated rats, relative to controls, due mainly to a marked reduction in the glomerular capillary ultrafiltration coefficient and, to a lesser extent, to a small reduction in glomerular plasma flow rate as well. In PAN-treated rats, as in normal controls, inulin was found to permeate the glomerular capillary wall without measurable restriction, and both D and DS were shown to be neither secreted nor reabsorbed. Fractional clearances of uncharged D were reduced after PAN administration, falling significantly for effective D radii from 22 to 38A. Utilizing a theory based on macromolecular transport through pores, these results indicate that in PAN-treated rats, effective pore radius is the same as in controls, approximately 44A. In PAN nephrosis, however, the ratio of total pore surface area/pore length, a measure of pore density, is reduced to approximately one-third that of control, due very likely to a reduction in filtration surface area. In contrast to the results with uncharged D, fractional clearances of DS were found to increase after PAN administration for all DS radii studied. These results with D and DS suggest that proteinuria in PAN nephrosis is due, not to an increase in effective pore radius or number of pores, but rather to a diminution of the electrostatic barrier function of the glomerular capillary wall, thereby allowing increased passage of polyanions such as DS and albumin.
Animals↗
Missing predictors in models of effect size.
Missing data occur frequently in meta-analysis. Reviewers inevitably face decisions about how to handle missing data, especially when predictors in a model of effect size are missing from some of the identified studies. Commonly used methods for missing data such as complete case analysis and mean substitution often yield biased estimates. This article briefly reviews the particular problems missing predictors cause in a meta-analysis, discusses the properties of commonly used missing data methods, and provides suggestions for ways to handle missing predictors when estimating effect size models. Maximum likelihood methods for multivariate normal data and multiple imputation hold the most promise for handling missing predictors in meta-analysis. These two model-based methods apply to a broad set of data situations, are based on sound statistical theory, and utilize all information available to obtain efficient estimators.
Data Interpretation, Statistical↗
A model for the HELLP syndrome: the maternal experience.
OBJECTIVE: To describe the experience of mothers whose pregnancies were complicated with HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets) and to determine if such experiences could be clustered by common themes from which a model could emerge. DESIGN: Retrospective, descriptive, qualitative study utilizing grounded theory analysis. SETTING: Participants were interviewed in their homes via telephone. Participants were from Kansas, Maine, Maryland, Michigan, Minnesota, Mississippi, South Carolina, Utah, and Wyoming, representing both urban and rural settings. PARTICIPANTS: Nine self-selected survivors of HELLP syndrome. RESULTS: The essential structure of the experience of HELLP syndrome can be expressed as a circle of no control and not knowing, which included the five themes of premonition, symptoms, betrayal, whirlwind, and loss. The pervading emotions expressed were fear (of death), frustration, anger, and guilt. HELLP syndrome represents a unique maternal experience that can be expressed in a model.
Adaptation, Psychological↗
Mechanisms of power within a community-based food security planning process.
A community food security movement has begun to address problems of hunger and food insecurity by utilizing a community-based approach. Although various models have been implemented, little empirical research has assessed how power operates within community-based food security initiatives. The purpose of this research was to determine how power influenced participation in decision-making, agenda setting, and the shaping of perceived needs within a community-based food security planning process, with particular reference to disenfranchised stakeholders. Power influenced participation in decision-making, agenda setting, and the shaping of perceived needs through managing 1) problem framing, 2) trust, 3) knowledge, and 4) consent. To overcome these mechanisms of power, practitioners need to address individual-, community-, and institutional-level barriers to participation in community-based food security planning processes. Practitioners and researchers can work with disenfranchised groups to determine which agents have the power to create desired changes by utilizing theory-based methods and strategies that focus on changing external determinants at multiple levels.
Adult↗
Examining the care of patients with peripheral venous cannulas.
The purpose of this study was to examine nursing issues in the care of patients with peripheral venous cannulas (PVCs) with particular focus on duration of cannulation in order to minimize risk of infection. A tentative practice model evolved from this study. The research approach used involved qualitative methods utilizing grounded theory. Data analysis produced one tentative core category, 'effectiveness'. This allowed for the development of a 12-dimensional model explaining the nursing function against four interrelated models: development; practice; organizational support; effectiveness. Related to these four models were key professional aspects of 'autonomy-control' and 'knowledge-practice'. Interpretative findings from the study were plotted against this model, giving a graphic representation and highlighting strengths and weaknesses of nursing practice. Aspects requiring improvement included: PVC care as a syllabus subject; nursing practice; autonomy and control issues; shared responsibility problems; documentation systems; goal setting; outcomes. The policy, nurses' knowledge of PVC care and identification of critical issues were considered satisfactory. The model incorporates 12 important dimensions associated with effective practice that can be applied to nursing at different levels - clinical practice, education, management - and to other disciplines, providing a framework for narrowing the theory-practice gap and improving patient care.
Catheterization, Peripheral↗
Role strain in hospice nursing.
This paper utilizes role theory to explore the nursing role at a northern California hospice which is licensed as a home health agency. The writers hypothesize that the special burdens of caring for dying patients, the numerous relationships assumed by the nurse, and the expanded nature of the rapidly developing hospice nursing role may contribute to role strain. Options for managing role strain are presented.
California↗
An ethnographic study of the social context of migrant health in the United States.
BACKGROUND: Migrant workers in the United States have extremely poor health. This paper aims to identify ways in which the social context of migrant farm workers affects their health and health care. METHODS AND FINDINGS: This qualitative study employs participant observation and interviews on farms and in clinics throughout 15 months of migration with a group of indigenous Triqui Mexicans in the western US and Mexico. Study participants include more than 130 farm workers and 30 clinicians. Data are analyzed utilizing grounded theory, accompanied by theories of structural violence, symbolic violence, and the clinical gaze. The study reveals that farm working and housing conditions are organized according to ethnicity and citizenship. This hierarchy determines health disparities, with undocumented indigenous Mexicans having the worst health. Yet, each group is understood to deserve its place in the hierarchy, migrant farm workers often being blamed for their own sicknesses. CONCLUSIONS: Structural racism and anti-immigrant practices determine the poor working conditions, living conditions, and health of migrant workers. Subtle racism serves to reduce awareness of this social context for all involved, including clinicians. The paper concludes with strategies toward improving migrant health in four areas: health disparities research, clinical interactions with migrant laborers, medical education, and policy making.
Agriculture↗
Mechanical behavior of lung parenchyma as a compressible continuum: a theoretical analysis.
The mechanical behavior of bronchial volume with respect to parenchymal properties, and to both the intrabronchial and pleural pressure, was investigated utilizing a theory of finite elasticity. Treating the lung parenchyma as a compressible continuum, we derived a simple strain-energy density function from pressure-volume curves of saline-filled lungs. On the basis of this function, large deformations of the fluid-filled excised dog lobe could be analyzed by numerical procedures. For the purpose of obtaining peribronchial stress, the lung was represented by a hollow thick-walled cylinder corresponding to an axial bronchus with surrounding parenchyma. In general, we found that the theoretical results corresponded well to previous experimental results, being able to predict quantitatively the stress and strain around the bronchus during collapse previously demonstrated by Nakamura et al. Peribronchial radial and circumferential stresses were shown to be concentrated at the bronchial wall, but dissipated rapidly within 1-2 bronchial radii away from the wall. We conclude that the magnitude of regional lung recoil around bronchi during collapse can be plausibly estimated by a theoretical analysis of total lung pressure-volume relationships.
Animals↗
The utility of Hayashi's quantification theory type 2 for the rapid assessment of the epidemiological survey in the developing countries--in a case of the vaccine coverage survey in Yunnan Province, China.
It is difficult to conduct the epidemiological survey with accurate statistical theory in the developing countries due to the problems especially emerged in the developing countries such as no availability of the accurate population data, limitation of the time for survey, geographical obstacle and financial problems. In the consideration of the health needs in those countries, results of the epidemiological survey should be reflected in the present health projects as rapidly as possible. The authors conducted the survey for the immunization coverage of oral poliomyelitis vaccine(OPV) in China by the questionnaire and interview. The data was analyzed by using the Hayashi's quantification theory type 2 and made clear about the relationship between the health behaviors for immunization among residents and several factors. It is considered that this theorem can provide the obvious numeral materials about multi-factorial cause effect relationship for the decision making and is useful for the rapid assessment or initial survey in the developing countries.
Chi-Square Distribution↗
Exact and resampling probability values for measures of categorical variation and consensus.
When analyzing categorical data, it is often important to assess the magnitude of variation, or consensus, among observations in unordered categories. Utilizing the theory of partitions, exact solutions for five commonly used measures of categorical variation are presented. When the number of partitions is very large, resampling methods provide close approximations to exact probability values.
Algorithms↗
Intent to breast-feed: the impact of attitudes, norms, parity, and experience.
OBJECTIVE: To examine the influence of breast-feeding attitudes, social norms, and prior experience on predicting breast-feeding intention utilizing the theories of reasoned action and planned behavior. METHODS: Low-income pregnant women (n = 963) completed a theory-based questionnaire. RESULTS: Attitudes were more predictive of breast-feeding intention than were norms, regardless of parity or prior behavior. Among multiparous women, amount of prior breast-feeding experience contributed independently to predicting breast-feeding intention and rendered norms insignificant. CONCLUSION: Results support the theories. Breast-feeding promotions targeting low-income women should emphasize enhancing women's personal breast-feeding attitudes, and, among primiparous women, promoting positive breast-feeding attitudes among their significant others.
Attitude to Health↗
Using popular education groups: can we develop a health promotions strategy for psychiatric consumers/survivors?
It is widely acknowledged that health derives from a myriad of factors including economics, education, housing, and social support (Sidell et al., 1997). In short, health care, although dominant in North America, represents only one approach to health. The paper suggests utilizing the theory of Paulo Freire (1971) concerning adult and popular education to support the empowerment of psychiatric consumers/survivors with regard to their health. The paper theorizes that, as psychiatric consumers are supported to 'own' their health through a process of mutual aid, they will be more able to become partners in managing not only their psychiatric illness but their health. The paper argues that it is incumbent upon traditional mental health services as well as community innovators to undertake these facilitative roles. More generally, the paper suggests that a health promotions/health determinants approach can be efficacious in improving the health of other high-risk/high-use health care groups, and that we must direct concerted efforts to reduce the marginalization experienced by so many of our citizens.
Health Education↗
GRASP-DNA: a web application to screen prokaryotic genomes for specific DNA-binding sites and repeat motifs.
The ability to control multiple genes at the transcriptional level often relies on the existence of short stretches of well-defined DNA sequences, to which regulatory proteins and transcription factors bind. In this article we present a freely accessible web-based application (GRASP-DNA), that can be used to screen prokaryotic genomes for putative DNA-binding sites of a particular transcription factor or DNA-binding molecule. This application utilizes existing theories, such as information and statistical-mechanical theories, for the calculation of positive weight matrices generated from block aligned binding sites. Using these position weight matrices entire prokaryotic genomes are screened to identify sites that display a high level of sequence similarity to existing binding sites. This application can be used in combination with high-throughput technologies for gene expression analysis and binding site characterization to assist in the elucidation of global regulatory networks.
Base Sequence↗
Empirical findings on socioeconomic determinants of fertility differentials in Costa Rica.
"This paper seeks to (1) identify socioeconomic variables that are expected to generate fertility differentials; (2) hypothesize the direction and magnitude of the effect of each variable by reference to a demand-for-children model; and (3) test empirically the model using evidence from Costa Rica. The estimates are obtained from a ten-percent systematic random sample of all Costa Rican individual-family households. There are 15,924 families in the sample...." The authors specifically seek "to capture the effects of changing relative prices and available income and time constraints on parental preferences for children. Least-squares estimates show statistically significant relationships between household fertility and opportunity cost of time, parental education, occurrence of an extended family, medical care, household sanitation, economic sector of employment, and household stock of nonhuman capital."
Americas↗