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Results for “Utility Theory”

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PubMed1994

The activity of porcine pancreatic phospholipase A2 in 20% alcohol/aqueous solvent, by experiment and electrostatics calculations.

The activity of porcine pancreatic phospholipase A2 (pla2), measured at pH 8, is reduced when methanol or ethanol is added to the aqueous solution. Finite difference electrostatics calculations were used to study the effect of modelling mixed solvents on the pKas of histidine 48 and the amino-terminal group, both of which influence the pH-dependence of catalysis. Calculations and experiment indicate that these pKa values cannot account for the activity reduction. Charge separation in the transition state is destabilized in 20% alcohol solvent relative to 100% aqueous solvent. The calculated values, which are combinations of stabilizing and destabilizing contributions, are in qualitative agreement with experiment. Saturating dielectric theory is used to model solvent water ordering in a high electric field, and water dielectric structure is assumed to dominate at the 20% alcohol level. The observed agreement demonstrates the utility of transition state stabilization theory and continuum solvent modelling. It is further suggested that electrostatic effects on kcat contribute to the pH-dependence of activity around pH 7, and to previously reported activity changes for charge mutants.

Amino Acid Sequence↗

PubMed2000

Free energy and information contents of conformons in proteins and DNA.

Sequence-specific conformational strains (SSCS) of biopolymers that carry free energy and genetic information have been called conformons, a term coined independently by two groups over two and a half decades ago [Green, D.E., Ji, S., 1972. The electromechanochemical model of mitochondrial structure and function. In: Schultz, J., Cameron, B.F. (Eds.), Molecular Basis of Electron Transport. Academic Press, New York, pp. 1-44; Volkenstein, M.V., 1972. The Conformon. J. Theor. Biol. 34, 193-195]. Conformons provide the molecular mechanisms necessary and sufficient to account for all biological processes in the living cell on the molecular level in principle--including the origin of life, enzymic catalysis, control of gene expression, oxidative phosphorylation, active transport, and muscle contraction. A clear example of SSCS is provided by SIDD (strain-induced duplex destabilization) in DNA recently reported by Benham [Benham, C.J., 1996a. Duplex destabilization in superhelical DNA is predicted to occur at specific transcriptional regulatory regions. J. Mol. Biol. 255, 425-434; Benham, C.J., 1996b. Computation of DNA structural variability--a new predictor of DNA regulatory regions. CABIOS 12(5), 375-381]. Experimental as well as theoretical evidence indicates that conformons in proteins carry 8-16 kcal/mol of free energy and 40-200 bits of information, while those in DNA contain 500-2500 kcal/mol of free energy and 200-600 bits of information. The similarities and differences between conformons and solitons have been analyzed on the basis of the generalized Franck-Condon principle [Ji, S., 1974a. A general theory of ATP synthesis and utilization. Ann. N.Y. Acad. Sci. 227, 211-226; Ji, S., 1974b. Energy and negentropy in enzymic catalysis. Ann. N.Y. Acad. Sci. 227, 419-437]. To illustrate a practical application, the conformon theory was applied to the molecular-clamp model of DNA gyrase proposed by Berger and Wang [Berger, J.M., Wang, J.C., 1996. Recent developments in DNA topoisomerases II structure and mechanism. Curr. Opin. Struct. Biol. 6(1), 84-90], leading to the proposal of an eight-step molecular mechanism for the action of the enzyme. Finally, a set of experimentally testable predictions has been formulated on the basis of the conformon theory.

Animals↗

PubMedDate not supplied

Child development and public policy: toward a dynamic systems perspective.

Little theoretical work exists that proposes general mechanisms for how public policies may influence child development. This article argues that dynamic systems theories may be useful in illuminating such processes, as well as highlighting gaps in current research at the intersection of public policy analysis and developmental science. A brief review of dynamic systems theories as they are currently utilized in other areas of developmental science is provided, as well as a statement of why they may help advance research in public policy and child development. Five principles of dynamic systems theories are presented and discussed using examples from research that address the question, "How do current antipoverty and welfare reform policies affect children?" Also presented are examples of hypotheses and research questions that each principle may generate for future work. The concluding section presents challenges that each principle poses for research methodology, and potential uses of the dynamic systems approach for developing and integrating policy and program initiatives.

Child↗

PubMed2002

Ethics and incentives: an evaluation and development of stakeholder theory in the health care industry.

This paper utilizes a qualitative case study of the health care industry and a recent legal case to demonstrate that stakeholder theory's focus on ethics, without recognition of the effects of incentives, severely limits the theory's ability to provide managerial direction and explain managerial behavior. While ethics provide a basis for stakeholder prioritization, incentives influence whether managerial action is consistent with that prioritization. Our health care examples highlight this and other limitations of stakeholder theory and demonstrate the explanatory and directive power added by the inclusion of the interactive effects of ethics and incentives in stakeholder ordering.

Administrative Personnel↗

PubMed1979

Mechanisms of increased maximum expiratory flow during HeO2 breathing in dogs.

We used the retrograde-catheter technique to investigate the effect of a helium-oxygen gas mixture (HeO2) on resistance to maximum expiratory flow (Vmax) in airways subsegments between alveoli and the equal pressure point (EPP), and between EPP and the flow-limiting segment (FLS). FLS were found at the same site in main-stem bronchi on both air and HeO2 in most dogs studied. Static elastic recoil pressure (Pel = 7 +/- 1 cmH2O) and the lateral pressure at FLS (Ptm' = 11 +/- cmH2O) were not different on the two gases, and delta Vmax averaged 33 +/- 12%. EPP were located on HeO2 in segmental bronchi (7 +/- 2 mm ID), and EPP on air were always located more downstream. There was no density dependence of resistance between alveoli and EPP on HeO2, and delta Vmax was due to the marked density dependence of the pressure losses of convective acceleration in the short airway segment between EPP HeO2 and FLS. Assuming that FLS is the "choke point," these findings are consistent with wave-speed theory of flow limitation modified to account for viscous pressure losses in peripheral airways. These results and conclusions question previous interpretations of delta Vmax as an index of peripheral airways obstruction, and demonstrate the utility of wave-speed theory in explaining complicated mechanisms of expiratory flow limitation.

Airway Resistance↗

PubMed1997

Rethinking assimilation theory for a new era of immigration.

"We argue that assimilation theory has not lost its utility for the study of contemporary immigration to the United States. In making our case, we review critically the canonical account of assimilation provided by Milton Gordon and others; we refer to Shibutani and Kwan's theory of ethnic stratification to suggest some directions to take in reformulating assimilation theory. We also examine some of the arguments frequently made to distinguish between the earlier mass immigration of Europeans and the immigration of the contemporary era and find them to be inconclusive. Finally, we sift through some of the evidence about the socioeconomic and residential assimilation of recent immigrant groups. Though the record is clearly mixed, we find evidence consistent with the view that assimilation is taking place, albeit unevenly."

Acculturation↗

PubMedDate not supplied

Triage of the autistic spectrum child utilizing the congruence of case management concepts and Orem's Nursing Theories.

The purpose of this project was to design and implement a case management framework for the benefit of children diagnosed with an autistic spectrum disorder (ASD). The process consisted of selecting two children exhibiting symptoms of an ASD and managing them across a continuum of care. Methodological structure was derived from case management standards of practice and Orem's Nursing Theories. Although some objectives sustained a slight delay because of variances, findings revealed successful outcomes based on progression toward measurable case management goals. The children were directed to appropriate school placements and habilitative therapies in an efficient manner. Their parents received support and education related to special needs children. The process yielded assurance that Orem's Nursing Theories and case management concepts articulate seamlessly within nursing care boundaries.

Autistic Disorder↗

PubMed1998

Implications of resource-ratio theory for oral microbial ecology.

The ability to compete for the limited nutrients available to the microorganisms of dental plaque is a strong ecological determinant of the structure of the subgingival ecosystem. This paper introduces a new concept from the field of ecology, resource-ratio theory, and applies it to the dynamics of microbial dental plaque with emphasis on the putative periodontal pathogens. Resource-ratio theory is a mechanistic theory of resource competition that utilizes pairs of growth-limiting nutrients in a stoichiometric fashion to predict zones of competitive dominance, exclusion, and coexistence for organisms competing for these resources. Once these resource pairs are identified for plaque organisms, resource-ratio theory may provide predictions of changes in the microbial community structure of plaque based on directional changes in their resource supply ratios.

Bacteria↗

PubMed1979

Biochemical evidence of cocarcinogenesis: tumor promoting agent enhances methylnitrosourea activation of rat guanylate cyclase activity.

The two-stage or cocarcinogenic hypothesis of carcinogenesis involves an initiator (carcinogen) and a promotor (cocarcinogen) being utilized in combination to produce more tumors than either would alone. This theory was tested at the cellular level utilizing Tumor Promoting Agent, 12-0-tetradecanoly-phorbol-13-acetate, (promotor) in combination with submaximal and maximal doses of methylnitrosourea (initiator). Tumor promoting agent, which can cause some tumors itself, was found to enhance the activity of guanylate cyclase (E.C.4.6.1.2.), an enzyme that has been associated with normal and abnormal growth. Tumor promoting agent when utilized in combination with submaximal stimulatory doses of methylnitrosourea had an additive effect on guanylate cyclase activity, but the agent had no further additive effect on guanylate cyclase activation when methylnitrosourea was utilized in maximal stimulatory doses. These results indicate a carcinogen acting alone without a promoter can maximally activate guanylate cyclase and would suggest that at the cellular level a promotor is not absolutely necessary for the changes observed morphologically in canerous cells. The promotor, however, did enhance the enzyme's activity when a submaximal dose of the carcinogen was used indicating that promoting agents, at least biochemically, appear capable of potentially contributing to the development of a cancerous cell.

Animals↗

PubMed2006

On the physical nature of mesophases of guanosine gels.

The unusual columnar aqueous mesophases of self-assembled guanosine stacks, such as 2'-deoxyguanosine 5'-monophosphate and 2'-deoxyguanosine 3'-monophosphate, are analyzed in terms of a general theory of azimuthal correlations between the charged helices. This theory considers forces, specific to the helical structure of each macromolecule, which depend on the azimuthal orientations of the molecules about their long axes. More specifically, in determining the magnitudes and decay lengths of these helix specific forces we utilize the Kornyshev-Leikin theory of electrostatic interaction between helical macromolecules and quantitatively fit experimental data. Together with explaining a number of the observed features of these mesophases, several new effects are predicted. Possible limitations and developments of our theoretical model are discussed, as well as new experiments to test the implications of the theory.

Deoxyguanine Nucleotides↗

PubMed2005

Loewald's approach to psychoanalytic theory.

The author suggests that part of the legacy of Hans Loewald is the nature of his approach to psychoanalytic theory. Loewald carefully considered and selectively utilized the work of theorists from a number of psychoanalytic schools of thought: id psychology, object relations theory, ego psychology, self psychology, and the interpersonal tradition. In addition, he helped pave the way for the current widespread interest in intersubjectivity, and also positioned himself in relation to those who embraced hermeneutics. Through all of this, he maintained a skeptical attitude, embodied in his belief in the complexity of the phenomena to be explored and his commitment to the perspective that psychoanalytic ideas should be open to revision.

Ego↗

PubMed1998

Applicability of the Kubelka-Munk theory for the evaluation of reflectance spectra demonstrated for haemoglobin-free perfused heart tissue.

Reflectance spectrometry is a useful tool for studying in vivo kinetic changes in the oxygen saturation of haemoglobin and myoglobin as well as the redox state of cytochromes. A method is given which allows the quantification of tissue reflectance spectra using multicomponent analysis. This method utilizes the Kubelka-Munk theory for modelling the measured tissue spectra. To test this approach, reflectance spectra of a haemoglobin-free perfused guinea pig heart were measured by a fast scanning spectrophotometer (100 spectra/s, spectral resolution 1.0 nm) and evaluated using the component absorbance spectra measured separately. A relative mean spectral residual error of 0.15% was achieved by least-squares fitting. Using statistical error propagation, oxygenation of myoglobin is obtained within a relative precision of 1%, and the redox state of cytochromes aa3 and c are determined simultaneously within a margin of 3%; the results for the redox-state of cytochrome b, however, are less precise. Special component error functions are presented to provide a reliability measure for the concentration prediction using this multicomponent assay. The consistency of the theory and the component absorptivity data is tested by regressing the actual concentrations obtained for each of the redox pair components during the various states of tissue oxygenation. A method is described for the recognition and reduction of systematic errors.

Animals↗

PubMed1991

Pain assessment in children: theoretical and empirical validity.

Valid assessment of pain in children is foundational for both the nursing practice and research domains, yet few validated methods of pain measurement are currently available for young children. This article describes an innovative research approach used in the development of photographic instruments to measure pain intensity in young African-American and Hispanic children. The instruments were designed to enable children to participate actively in their own care and to do so in ways that are congruent with their developmental and cultural heritage. Conceptualization of the instruments, methodological development, and validation processes grounded in Orem's Self-Care Deficit Theory of Nursing are described. The authors discuss the ways in which the gaps between nursing theory, research, and practice are narrowed when development of instruments to measure clinical nursing phenomena are grounded in nursing theory, validated through research and utilized in practice settings.

Black or African American↗

PubMed1980

Life satisfaction and activity theory: a multidimensional approach.

Life satisfaction is examined utilizing a multidimensional approach. Hypotheses were proposed and tested for each of the dimensions of LSIA (Life Satisfaction Index A) within an activity theory perspective. The results provide qualified support for the theory. Some dimensions; however, show a better fit than others. Lack of a more general confirmation proved to be due to problems with activity theory and its attendant measures rather than with the multidimensional approach. The patterns of relationships found across the dimensions provide further support for using a multidimensional analysis when dealing with LSIA.

Aged↗

PubMedDate not supplied

[Personal identity and multiple personality].

The present study analyses the internal organization of self concepts in a woman who meets the DSM III criteria of multiple personality disorder. The aim of this single case study, was to assess the personal identity of this patient, the degree of internal coherence and the hierarchical structure of the descriptions of self and others in the frame of cognitive theories of personality. After the clinical observation, the experimental procedure is presented. It consists in asking the patient to describe her different roles or alternated personalities (N = 12), as well as the target persons of her familial and social environment (N = 8) on the basis of a preestablished list of adjectives (extracted from the 16 P.F. Cattell sphere of personality). The factorial analysis of the contingency table: traits attributed x persons described shows a Guttman like hierarchical structure. Similarities and differences between the descriptions can be ordered on a unidimensional order, the multiple roles or personalities being no more complex nor simple than the target persons. The present results have been discussed in reference to cognitive theories of personality and their utility in studying personal identity and multiple personality.

Adult↗

PubMed1984

Family therapy with deaf persons: the systemic utilization of an interpreter.

This paper discusses the theory and practice of providing family therapy to families in which there are hearing parents and at least one Deaf child, particularly regarding the optimal utilization of an interpreter. The therapist must be knowledgeable about the psychosocial effects of deafness, the cultural aspects of deafness, and preferably be able to use American Sign Language and Signed English. The therapeutic benefit of utilizing an interpreter extends far beyond simply facilitating communication between each family member whose primary-language is either spoken English or Sign Language. The presence of an interpreter helps the therapist to modify family rules that deny the implications of deafness and prohibit the use of Sign Language, to modify the balance of power in the family, and to encourage participants to exhibit the ego defense mechanisms of projection and transference. The family therapist can utilize those subtle yet profound influences to therapeutic advantage.

Adaptation, Psychological↗

PubMedDate not supplied

Stages of change in physical exercise: a test of stage discrimination and nonlinearity.

OBJECTIVES: To investigate the utility of the protection motivation theory (PMT), social-cognitive theory (SCT) and transtheoretical model's (TTM) processes of change (POC) by (1) discriminating between TTM's stages with planned comparisons and (2) examining higher-ordered trends across stages. METHODS: 1582 individuals were included in the analyses that tested severity, vulnerability, response-efficacy, self-efficacy, POC, pros and cons, social and environmental support. RESULTS: The findings provide evidence for the utility of the PMT and TTM's POC for stage discrimination; stage discontinuity patterns are supported. CONCLUSIONS: Promotion of health behavior should target stage-specific variables, such as threat appraisals for early stage movements.

Adult↗

PubMed2003

A broad frequency range dielectric spectrometer for colloidal suspensions: cell design, calibration, and validation.

Electrode polarization complicates low-frequency measurements of the dielectric response of electrolyte solutions and colloidal suspensions. To deal with this longstanding problem, a new dielectric cell was developed along with a model based on the standard electrokinetic theory. The parallel plate cell utilizes a thin chamber that is easily filled and emptied; different chamber thicknesses are readily accommodated. The analytical form of the theoretical impedance model makes data analysis straightforward. Using standard electrolytes, the device and the theoretical model were tested over a wide range of frequencies for several electrolyte concentrations. Excellent agreement was found between the theory and the experimental data. The methodology developed to account for polarization effects exhibits a significant improvement over the conventional approaches and points up a deficiency in often-used equivalent circuit models.

Journal Article↗