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PubMed2002

Marital research in the 20th century and a research agenda for the 21st century.

In this article we review the advances made in the 20th century in studying marriages. Progress moved from a self-report, personality-based approach to the study of interaction in the 1950s, following the advent of general systems theory. This shift led, beginning in the 1970s, to the rapid development of marital research using a multimethod approach. The development of more sophisticated observational measures in the 1970s followed theorizing about family process that was begun in the decade of the 1950s. New techniques for observation, particularly the study of affect and the merging of synchronized data streams using observational and self-report perceptual data, and the use of sequential and time-series analyses produced new understandings of process and power. Research in the decades of the 1980s and 1990s witnessed the realization of many secular changes in the American family, including the changing role of women, social science's discovery of violence and incest in the family, the beginning of the study of cultural variation in marriages, the expansion of the measurement of marital outcomes to include longevity, health, and physiology (including the immune system), and the study of comorbidities that accompany marital distress. A research agenda for the 21st century is then described.

Affect↗

PubMed1999

Integration of non-linear cellular mechanisms regulating microvascular perfusion.

It is becoming increasingly evident that interactions between the different cell types present in the vessel wall and the physical forces that result from blood flow are highly complex. This short article will review evidence that irregular fluctuations in vascular resistance are generated by non-linearity in the control mechanisms intrinsic to the smooth muscle cell and can be classified as chaotic. Non-linear systems theory has provided insights into the mechanisms involved at the cellular level by allowing the identification of dominant control variables and the construction of one-dimensional iterative maps to model vascular dynamics. Experiments with novel peptide inhibitors of gap junctions have shown that the coordination of aggregate responses depends on direct intercellular communication. The sensitivity of chaotic trajectories to perturbation may nevertheless generate a high degree of variability in the response to pharmacological interventions and altered perfusion conditions.

Animals↗

PubMed1989

A semiparametric approach to physiological flow models.

By regarding sampled tissues in a physiological model as linear subsystems, the usual advantages of flow models are preserved while mitigating two of their disadvantages, (i) the need for assumptions regarding intratissue kinetics, and (ii) the need to simultaneously fit data from several tissues. To apply the linear systems approach, both arterial blood and (interesting) tissue drug concentrations must be measured. The body is modeled as having an arterial compartment (A) distributing drug to different linear subsystems (tissues), connected in a specific way by blood flow. The response (CA, with dimensions of concentration) of A is measured. Tissues receive input from A (and optionally from other tissues), and send output to the outside or to other parts of the body. The response (CT, total amount of drug in the tissue (T) divided by the volume of T) from the T-th one, for example, of such tissues is also observed. From linear systems theory, CT can be expressed as the convolution of CA with a disposition function, F(t) (with dimensions 1/time). The function F(t) depends on the (unknown) structure of T, but has certain other constant properties: The integral integral infinity0 F(t) dt is the steady state ratio of CT to CA, and the point F(0) is the clearance rate of drug from A to T divided by the volume of T. A formula for the clearance rate of drug from T to outside T can be derived. To estimate F(t) empirically, and thus mitigate disadvantage (i), we suggest that, first, a nonparametric (or parametric) function be fitted to CA data yielding predicted values, CA, and, second, the convolution integral of CA with F(t) be fitted to CT data using a deconvolution method. By so doing, each tissue's data are analyzed separately, thus mitigating disadvantage (ii). A method for system simulation is also proposed. The results of applying the approach to simulated data and to real thiopental data are reported.

Models, Biological↗

PubMed2006

Pathways, networks and choice in health care.

PURPOSE: The purpose of the paper is to present an alternative to the supply chain model of health care delivery that currently informs most thinking about the design of care processes. DESIGN/METHODOLOGY/APPROACH: The paper draws on arguments from systems theories and public administration, to generate an analysis of the nature of health care processes. It sets out a model of services characterised by treatment and care needs that vary over time, that are inherently uncertain, involve frequent assessment and re-assessment, and provide patients and service providers with choices about treatment and care. Evidence from an evaluation of intermediate care is used to illustrate the analysis. FINDINGS: The analysis suggests that both the supply chain and a more network-like model of health care processes can help us to understand health care processes. The two are complementary. RESEARCH LIMITATIONS/IMPLICATIONS: Largely conceptual in nature. The empirical evidence is taken from one study. The ideas are presented to stimulate thinking rather than to prove an argument. PRACTICAL IMPLICATIONS: The conceptualisation of care processes as network-like has implications for the way in which we think about the design and performance of health care systems. ORIGINALITY/VALUE: There have been few publications that seek to use both systems and network approaches to understand health care processes.

Delivery of Health Care, Integrated↗

PubMed2005

Validating task analysis for error identification: reliability and validity of a human error prediction technique.

This paper reports on the theoretical and empirical developments for an error prediction methodology called task analysis for error identification (TAFEI). Other researchers have noted the need for theoretically driven approaches that are able to provide practical utility in error prediction. Theoretical developments include the concept of "rewritable routines", which describe the loop between cognitive processing, action and devices states. This has been proposed as a way of unifying ideas from systems theory and cognitive psychology. The empirical research shows that TAFEI is superior to heuristic methods, which supports the idea that structured methods assist in error prediction. The validation study shows that TAFEI reaches acceptable levels in terms of test-retest reliability and concurrent validity. It is believed that the method has reached a level of maturity after 10 years of development work. This is demonstrated by the many uses to which the method has been put, including that of a design tool.

Adult↗

PubMed1978

A model for the evaluation of allied health education.

The variety and complexity of evaluation designs, procedures and philosophies has proved confusing for educators and health practitioners. Many evaluation models do not provide for the scope of information needed by allied health programs and are inflexible in regard to the information needs of individual programs. The model presented here is based on the principles of "Systems Theory," which provides a comprehensive framework for the study of educational programs. Input, process, product and environment components are proposed as a method to study all aspects of program operations. With clearly definable rules for the evaluator and program decision-makers, the faculty can adopt and change the course of the evaluation as they work through the planning, implementation and recycling stages of the model. Use of the model should help programs identify information needs and bring existing evaluation efforts together under a comprehensive umbrella.

Allied Health Personnel↗

PubMed2004

A new mobile robot control approach via fusion of control signals.

This paper proposes an alternative approach to address the problem of coordinating behaviors in mobile robot navigation: fusion of control signals. Such approach is based on a set of two decentralized information filters, which accomplish the data fusion involved. Besides these two fusion engines, control architectures designed according to this approach also embed a set of different controllers that generate reference signals for the robot linear and angular speeds. Such signals are delivered to the two decentralized information filters, which estimate suitable overall reference signals for the robot linear and angular speeds, respectively. Thus, the background for designing such control architectures is provided by the nonlinear systems theory, which makes this approach different from any other yet proposed. This background also allows checking control architectures designed according to the proposed approach for stability. Such analysis is carried out in the paper, and shows that the robot always reaches its final destination, in spite of either obstacles along its path or the environment layout. As an example, a control architecture is designed to guide a mobile robot in an experiment, whose results allows checking the good performance of the control architecture and validating the design approach proposed as well.

Algorithms↗

PubMed2006

An entropic characterization of protein interaction networks and cellular robustness.

The structure of molecular networks is believed to determine important aspects of their cellular function, such as the organismal resilience against random perturbations. Ultimately, however, cellular behaviour is determined by the dynamical processes, which are constrained by network topology. The present work is based on a fundamental relation from dynamical systems theory, which states that the macroscopic resilience of a steady state is correlated with the uncertainty in the underlying microscopic processes, a property that can be measured by entropy. Here, we use recent network data from large-scale protein interaction screens to characterize the diversity of possible pathways in terms of network entropy. This measure has its origin in statistical mechanics and amounts to a global characterization of both structural and dynamical resilience in terms of microscopic elements. We demonstrate how this approach can be used to rank network elements according to their contribution to network entropy and also investigate how this suggested ranking reflects on the functional data provided by gene knockouts and RNAi experiments in yeast and Caenorhabditis elegans. Our analysis shows that knockouts of proteins with large contribution to network entropy are preferentially lethal. This observation is robust with respect to several possible errors and biases in the experimental data. It underscores the significance of entropy as a fundamental invariant of the dynamical system, and as a measure of structural and dynamical properties of networks. Our analytical approach goes beyond the phenomenological studies of cellular robustness based on local network observables, such as connectivity. One of its principal achievements is to provide a rationale to study proxies of cellular resilience and rank proteins according to their importance within the global network context.

Computer Simulation↗

PubMedDate not supplied

[Conceptual model of interactive open system and the theory of goal attainment of Imogene King].

This work describes the Conceptual Model of Interactive Open Systems and the Theory of Goal Attainment by Imogene King by reflecting on the care process based on this proposal. It was accomplished as a result of the extensive study of King's theoretical structure and its application with patients. It was possible to observe that the theoretical structure supplies the necessary theoretical and conceptual framework which is necessary for humanized nursing care. Also, it remains updated and included in the current context of health care.

Goals↗

PubMed1997

Indecomposable continua in dynamical systems with noise: Fluid flow past an array of cylinders.

Standard dynamical systems theory is based on the study of invariant sets. However, when noise is added, there are no bounded invariant sets. Our goal is then to study the fractal structure that exists even with noise. The problem we investigate is fluid flow past an array of cylinders. We study a parameter range for which there is a periodic oscillation of the fluid, represented by vortices being shed past each cylinder. Since the motion is periodic in time, we can study a time-1 Poincare map. Then we add a small amount of noise, so that on each iteration the Poincare map is perturbed smoothly, but differently for each time cycle. Fix an x coordinate x(0) and an initial time t(0). We discuss when the set of initial points at a time t(0) whose trajectory (x(t),y(t)) is semibounded (i.e., x(t)>x(0) for all time) has a fractal structure called an indecomposable continuum. We believe that the indecomposable continuum will become a fundamental object in the study of dynamical systems with noise. (c) 1997 American Institute of Physics.

Journal Article↗

PubMed2005

Variability of target-controlled infusion is less than the variability after bolus injection.

BACKGROUND: Target-controlled infusion (TCI) drug delivery systems deliver intravenous drugs based on pharmacokinetic models. TCI devices administer a bolus, followed by exponentially declining infusions, to rapidly achieve and maintain pseudo-steady state drug concentrations in the plasma or at the site of drug effect. Many studies have documented the prediction accuracy of TCI devices. The authors' goal was to apply linear systems theory to characterize the relation between the variability in concentrations achieved with TCI devices and the variability in concentrations after intravenous bolus injection. METHODS: The authors developed a mathematical model of the variability of any arbitrary method of drug delivery, based on the variability with intravenous bolus injection or the variability with an arbitrary infusion regimen. They tested the model in a simulation of 1,000 patients receiving propofol by simple bolus injection, conventional infusion, or a TCI device. The authors then examined an experimental data set for the same behavior. RESULTS: The variability of any arbitrary infusion regimen, including TCI, is bounded by the variability after bolus injection. This is observed in the simulation and experimental data sets as well. CONCLUSION: TCI devices neither create nor eliminate biologic variability. For any drug described by linear pharmacokinetic models, no infusion regimen, including TCI, can have higher variability than that observed after bolus injection. The median performance of TCI devices should be reasonably close to the prediction of the device. However, the overall spread of the observations is an intrinsic property of the drug, not the TCI delivery system.

Animals↗

PubMed1992

Routine, ceremony, or drama: an exploratory field study of the primary care clinical encounter.

BACKGROUND: Practicing family physicians often find family systems theory and the biopsychosocial model attractive, but have difficulties applying them in a busy office practice. METHODS: Two family physicians in a four-person group practice were identified as "exemplars" at managing daily office practice. A collaborative, qualitative methodology was used to explore their strategy. A series of semistructured key informant interviews with the two physicians and the head nurse identified themes later clarified using ethnoscience interviewing techniques. The resultant clinical encounter typology and decision-making taxonomy were evaluated using participant observation and key informant review. The final results were compared with the literature on physician-patient relationships. RESULTS: Three clinical encounter types were identified. "Routines" were simple, single, and brief visits in which a contractual style and the biomedical model were used. "Ceremonies" were linked rituals that invoked a covenantal style. "Dramas" were a series of visits concerning situations of conflict and emotion and included psychosocial problems. The family was often convened for dramas. Determination of the presenting concern, the trigger for coming, the patient request, the illness prototype, and the type of communication allowed recognition of the clinical encounter type. CONCLUSIONS: Identifying a clinical encounter as a routine, ceremony, or drama may help family physicians integrate family systems concepts into their busy office practices. These findings have numerous implications for future research, clinical practice, and teaching.

Adult↗

PubMed2006

A semiotic framework for evolutionary and developmental biology.

This work aims at constructing a semiotic framework for an expanded evolutionary synthesis grounded on Peirce's universal categories and the six space/time/function relations [Taborsky, E., 2004. The nature of the sign as a WFF--a well-formed formula, SEED J. (Semiosis Evol. Energy Dev.) 4 (4), 5-14] that integrate the Lamarckian (internal/external) and Darwinian (individual/population) cuts. According to these guide lines, it is proposed an attempt to formalize developmental systems theory by using the notion of evolving developing agents (EDA) that provides an internalist model of a general transformative tendency driven by organism's need to cope with environmental uncertainty. Development and evolution are conceived as non-programmed open-ended processes of information increase where EDA reach a functional compromise between: (a) increments of phenotype's uniqueness (stability and specificity) and (b) anticipation to environmental changes. Accordingly, changes in mutual information content between the phenotype/environment drag subsequent changes in mutual information content between genotype/phenotype and genotype/environment at two interwoven scales: individual life cycle (ontogeny) and species time (phylogeny), respectively. Developmental terminal additions along with increment minimization of developmental steps must be positively selected.

Biological Evolution↗

PubMed1976

30. Common problems of current data systems for long-term care.

This article reviews the varied long-term care data systems now being developed in the United States in the framework of a matrix derived from systems analysis and systems theory. Some common problems that emerge are that incentives are coming largely from the societal level; feedback to the institutional and patient care levels is lacking; little attention is being given to the individual level of decision making at one end of the spectrum and the national policy level at the other; and ideas and procedures developed in the acute care setting are being transferred to services traditionally lower in resources and determined more often by levels of patient functioning than by disease. The dominant instrument that emerges in long-term care is the periodic assessment form, in contrast to a hospital discharge abstract or ambulatory care encounter form; however, the data requirements appear to be more voluminous than in the case of acute hospital care, although less manpower is available to respond.

Information Systems↗

PubMed2002

Facial Expressivity at 4 Months: A Context by Expression Analysis.

The specificity predicted by differential emotions theory (DET) for early facial expressions in response to 5 different eliciting situations was studied in a sample of 4-month-old infants (n = 150). Infants were videotaped during tickle, sour taste, jack-in-the-box, arm restraint, and masked-stranger situations and their expressions were coded second by second. Infants showed a variety of facial expressions in each situation; however, more infants exhibited positive (joy and surprise) than negative expressions (anger, disgust, fear, and sadness) across all situations except sour taste. Consistent with DET-predicted specificity, joy expressions were the most common in response to tickling, and were less common in response to other situations. Surprise expressions were the most common in response to the jack-in-the-box, as predicted, but also were the most common in response to the arm restraint and masked-stranger situations, indicating a lack of specificity. No evidence of predicted specificity was found for anger, disgust, fear, and sadness expressions. Evidence of individual differences in expressivity within situations, as well as stability in the pattern across situations, underscores the need to examine both child and contextual factors in studying emotional development. The results provide little support for the DET postulate of situational specificity and suggest that a synthesis of differential emotions and dynamic systems theories of emotional expression should be considered.

Journal Article↗

PubMedDate not supplied

Functional development of the CNS in pupils aged 7 to 19 years.

In pupils aged 7 to 19 years, the functioning of the central nervous system (CNS) improved by a factor of 3 during their development. The CNS functioning was quantified in the framework of the dynamical system theory of pattern formation by the value of coordination dynamics. A transient increase in the optimal rate of arm and leg movements was observed in the pupils within 8 and 14 years of age. This high-speed moving is interpreted as a mean how the immature CNS tries to improve its functioning with respect to coordination and symmetry. Moreover, in very young pupils a lack of continuous drive of the CNS was observed; in other words, the concentration upon a certain task was not continuous. Some pupils were able to concentrate for only approximately 10 s. It was difficult for young pupils to simultaneously concentrate on two different tasks like moving and speaking or moving and thinking. It is concluded that concentration problems observed in young pupils are due to their immature CNS.

Adolescent↗

PubMed2002

Clinical applicability of heart rate variability analysis by methods based on nonlinear dynamics.

Analysis of heart rate (HR) variability has become an important widely used method for assessing cardiac autonomic regulation. Conventionally, HR variability has been analyzed with time and frequency domain methods. Analysis of HR dynamics by methods based on nonlinear systems theory has opened a novel approach for studying the abnormalities in HR behavior. Recent studies have shown that these measures, particularly scaling analysis methods of HR dynamics, are altered among various patients populations with cardiovascular diseases, and they provide prognostic information. Altered long-term scaling properties of HR dynamics and more random short-term HR fluctuation has been observed, e.g., among patients with previous myocardial infarction, and these alterations have been shown to be associated with increased mortality rate. A relatively large body of data indicate that altered scaling properties of R-R intervals are physiologically deleterious. These findings support the notion that some nonlinear methods, such as scaling and complexity measures, give clinically valuable information for risk stratification among various patient populations. This article provides a review of our current knowledge of the usefulness of dynamical measures of HR fluctuation.

Autonomic Nervous System↗

PubMed2000

Biochemical systems analysis of genome-wide expression data.

MOTIVATION: Modern methods of genomics have produced an unprecedented amount of raw data. The interpretation and explanation of these data constitute a major, well-recognized challenge. RESULTS: Biochemical Systems Theory (BST) is the mathematical basis of a well-established methodological framework for analyzing networks of biochemical reactions. An existing BST model of yeast glycolysis is used here to explain and interpret the glycolytic gene expression pattern of heat shocked yeast. Our analysis demonstrates that the observed gene expression profile satisfies the primary goals of increased ATP, trehalose, and NADPH production, while maintaining intermediate metabolites at reasonable levels. Based on a systematic exploration of alternative, hypothetical expression profiles, we show that the observed profile outperforms other profiles. CONCLUSION: BST is a useful framework for combining DNA microarray data with enzymatic process information to yield new insights into metabolic pathway regulation. AVAILABILITY: All analyses were executed with the software PLAS(Copyright), which is freely available at http://correio.cc.fc.ul.pt/~aenf/plas.html for academic use. CONTACT: VoitEO@MUSC.edu

Computational Biology↗