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PubMed1995

Dynamical systems theory for music dynamics.

We show that, when music pieces are cast in the form of time series of pitch variations, the concepts and tools of dynamical systems theory can be applied to the analysis of temporal dynamics in music. (i) Phase space portraits are constructed from the time series wherefrom the dimensionality is evaluated as a measure of the global dynamics of each piece. (ii) Spectral analysis of the time series yields power spectra ( approximately f(-nu)) close to red noise (nu approximately 2) in the low frequency range. (iii) We define an information entropy which provides a measure of the local dynamics in the musical piece; the entropy can be interpreted as an evaluation of the degree of complexity in the music, but there is no evidence of an analytical relation between local and global dynamics. These findings are based on computations performed on eighty sequences sampled in the music literature from the 18th to the 20th century. (c) 1995 American Institute of Physics.

Journal Article↗
PubMed2001

Three-systems theory of human visual motion perception: review and update.

Lu and Sperling [Vision Res. 35, 2697 (1995)] proposed that human visual motion perception is served by three separate motion systems: a first-order system that responds to moving luminance patterns, a second-order system that responds to moving modulations of feature types-stimuli in which the expected luminance is the same everywhere but an area of higher contrast or of flicker moves, and a third-order system that computes the motion of marked locations in a "salience map," that is, a neural representation of visual space in which the locations of important visual features ("figure") are marked and "ground" is unmarked. Subsequently, there have been some strongly confirmatory reports: different gain-control mechanisms for first- and second-order motion, selective impairment of first- versus second- and/or third-order motion by different brain injuries, and the classification of new third-order motions, e.g., isoluminant chromatic motion. Various procedures have successfully discriminated between second- and third-order motion (when first-order motion is excluded): dual tasks, second-order reversed phi, motion competition, and selective adaptation. Meanwhile, eight apparent contradictions to the three-systems theory have been proposed. A review and reanalysis here of the new evidence, pro and con, resolves the challenges and yields a more clearly defined and significantly strengthened theory.

Contrast Sensitivity↗
PubMed2006

Flows of dioxins and furans in coastal food webs: inverse modeling, sensitivity analysis, and applications of linear system theory.

Rate constant bioaccumulation models are applied to simulate the flow of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the coastal marine food web of Frierfjorden, a contaminated fjord in southern Norway. We apply two different ways to parameterize the rate constants in the model, global sensitivity analysis of the models using Extended Fourier Amplitude Sensitivity Test (Extended FAST) method, as well as results from general linear system theory, in order to obtain a more thorough insight to the system's behavior and to the flow pathways of the PCDD/Fs. We calibrate our models against observed body concentrations of PCDD/Fs in the food web of Frierfjorden. Differences between the predictions from the two models (using the same forcing and parameter values) are of the same magnitude as their individual deviations from observations, and the models can be said to perform about equally well in our case. Sensitivity analysis indicates that the success or failure of the models in predicting the PCDD/F concentrations in the food web organisms highly depends on the adequate estimation of the truly dissolved concentrations in water and sediment pore water. We discuss the pros and cons of such models in understanding and estimating the present and future concentrations and bioaccumulation of persistent organic pollutants in aquatic food webs.

Animals↗
PubMed1989

[Systems theory reflections on the treatment of the acute and post-acute stage of schizophrenic psychoses].

Biological, psychical and social phenomena of acute and postacute phase of schizophrenic psychoses are differentiated according to systems theory. During the acute phase the therapeutical interventions aim to stabilize mainly the biological and psychical sphere, whereas for the post-acute phase the emphasis lays on the psychical and social phenomena. This phase-oriented coupling between the therapist, the patient and his/her social network promotes a successive restructuring by generating consensual spheres, which help the patient and his/her social net to find new ways for autonomous development.

Acute Disease↗
PubMed2006

Organisational design for health integrated delivery systems: theory and practice.

Integrated delivery systems (IDS) are worldwide emerging as the dominant organizational form in the healthcare sectors. This article, drawing from international comparisons, focuses on organizational design of IDS. The analysis derives from an extensive literature review, which shows over the last years a significant lack of works on design issues, and from a number of experiences in community care settings, which provide useful insights on changes taking place in governance and delivery of health services at the local level. The frameworks discussed depict the major options of reorganization that can be observed in local integrated health systems of industrialized countries.

Delivery of Health Care, Integrated↗
PubMed1996

Application of biochemical systems theory to metabolism in human red blood cells. Signal propagation and accuracy of representation.

Human erythrocytes are among the simplest of cells. Many of their enzymes have been characterized kinetically using steady-state methods in vitro, and several investigators have assembled this kinetic information into mathematical models of the integrated system. However, despite its relative simplicity, the integrated behavior of erythrocyte metabolism is still complex and not well understood. Errors will inevitably be encountered in any such model because of this complexity; thus, the construction of an integrative model must be considered an iterative process of assessment and refinement. In a previous study, we selected a recent model of erythrocyte metabolism as our starting point and took it through three stages of model assessment and refinement using systematic strategies provided by biochemical systems theory. At each stage deficiencies were diagnosed, putative remedies were identified, and modifications consistent with existing experimental evidence were incorporated into the working model. In this paper we address two issues: the propagation of biochemical signals within the metabolic network, and the accuracy of kinetic representation. The analysis of signal propagation reveals the importance of glutathione peroxidase, transaldolase, and the concentration of total glutathione in determining systemic behavior. It also reveals a highly amplified diversion of flux between the pathways of pentose phosphate and nucleotide metabolism. In determining the range of accurate representation based on alternative kinetic formalisms we discovered large discrepancies. These were identified with the behavior of the model represented within the Michaelis-Menten formalism. This model fails to exhibit a nominal steady state when the activity of glutathione peroxidase is decreased by as little as 9%. Our current understanding, as embodied in this working model, is in need of further refinement, and the results presented in this paper suggest areas of the model where such effort might profitably be concentrated.

Erythrocytes↗
PubMed1976

Shame and other anxieties associated with breast-feeding: a systems theory and psychodynamic approach.

It is easy to be over-simplistic about breast-feeding--what determines the choice of the breast; what causes rejection of breast-feeding as a feeding method; what determines success and what its failure? In fact, a bewildering range of factors, physical, psychological and sociological play a part. How can these be related to each other and ordered in general and for the individual? A general systems theory approach, in which the elements are envisaged as interacting dynamically, seems to offer a possible satisfactory explanatory model. Moving from social systems to the individual's intrapsychic system helps to understand the complexity of emotions aroused about the breast and breast-feeding. Shame and anxieties are seen to arise from the confluence of life history and current events. Intervention is necessary at many levels--societal, family and individual--if breast-feeding is to be re-established as the feeding method of first choice.

Adult↗
PubMed1997

Sensoristrain: an exploration of nursing interventions in the context of the Neuman systems theory.

Defining what nurses do and why has been the endeavour of many researchers, both academic and clinical. Nursing interventions are a fundamental component of nursing practice and a focus on accountability means that nurses must be able to justify their actions. The sensoristrain experience of intensive care patients is widely acknowledged in nursing literature, though without the use of the word 'sensoristrain'. The aim in this paper is to place patients, their experience and the role of nurses within the practical framework of a suitable nursing theory which will elucidate and guide everyday practice in preventing and alleviating the causes (stressors), symptoms (reactions) and emotional aftermatch. Nursing interventions appropriate for the three modalities of intervention elucidated by the Neuman systems theory have been outlined, paralleled by a discussion of how these could relate to the three dimensions of nursing care: comfort care; knowing the patient; and the therapeutic presence of the nurse. Nurses must use each opportunity to advance practice through emphasizing the value of nursing in today's cost-conscious health care climate. In order to do this, and to ensure nurses' continued presence at the bedside, clear articulation of the contribution of nursing interventions to improved patient outcomes is essential.

Critical Care↗
PubMed1978

Alcoholism and systems theory: building a better mousetrap.

A considerable body of research evidence has accumulated in the alcoholism field with respect to when persons who overly rely on alcohol modify their behavior and seek alternate ways of dealing with life. It is the purpose of this paper to identify a number of these factors and relate them to a theoretical perspective that, while not new, is of relatively recent vintage for alcoholism specialists. That perspective is General Behavior Systems Theory (GBST), and it will be contended that its basic postulates comprise a framework that is especially congruent with the findings related to when alcohol-dependent persons change. As such, it provides a set of ideas which offer more fruitful guidelines for assessment and intervention than those resulting from exclusive reliance on other extant models (see Siegler et al., 1968; Miller and Barlow, 1973), in particular, the traditional and predominant illness conception.

Alcoholism↗
PubMedDate not supplied

Dynamic systems theory approach to consciousness.

The review of the main existing approaches to consciousness in the literature indicates that consciousness is multileveled and that humans have an ability to experience a wide range of its various states. The common views of the main approaches to consciousness are identified and considered in a three-dimensional model of states of consciousness developed by Kokoszka. This model is then described and discussed using a mathematical terms of dynamic systems theory. Since mathematics is an accepted tool for the description of the physical world, the congruence of psychological and mathematical models is understood as a meaningful support to the psychological one. Connections of the models with artificial neural networks and some applications in psychology are considered.

Consciousness↗
PubMed1984

Confirmation of linear system theory prediction: Changes in Herrnstein's k as a function of changes in reinforcer magnitude.

Eight human subjects pressed a lever on a range of variable-interval schedules for 0.25 cent to 35.0 cent per reinforcement. Herrnstein's hyperbola described seven of the eight subjects' response-rate data well. For all subjects, the y-asymptote of the hyperbola increased with increasing reinforcer magnitude and its reciprocal was a linear function of the reciprocal of reinforcer magnitude. These results confirm predictions made by linear system theory; they contradict formal properties of Herrnstein's account and of six other mathematical accounts of single-alternative responding.

Journal Article↗
PubMed2001

Bridging the gap between developmental systems theory and evolutionary developmental biology.

Many scientists and philosophers of science are troubled by the relative isolation of developmental from evolutionary biology. Reconciling the science of development with the science of heredity preoccupied a minority of biologists for much of the twentieth century, but these efforts were not corporately successful. Mainly in the past fifteen years, however, these previously dispersed integrating programmes have been themselves synthesized and so reinvigorated. Two of these more recent synthesizing endeavours are evolutionary developmental biology (EDB, or "evo-devo") and developmental systems theory (DST). While the former is a bourgeoning and scientifically well-respected biological discipline, the same cannot be said of DST, which is virtually unknown among biologists. In this review, we provide overviews of DST and EDB, summarize their key tenets, examine how they relate to one another and to the study of epigenetics, and survey the impact that DST and EDB have had (and in future should have) on biological theory and practice.

Animals↗
PubMed2004

Functional systems theory and the probabilistic prediction of behavior.

This article addresses the role of probabilistic prediction in the systems organization of behavioral acts. The systems mechanisms predicting the required results of the behavioral acts of living beings in stable and changing conditions are discussed. It is suggested that in all these types of behavior, the parameters of results satisfying the leading needs, which constitute the aims of behavior, are strictly predicted. The author believes that probabilistic prediction is related only to the means, actions, and accompanying emotional states, as well as that possible ways of achieving results, i.e., not to the parameters but to the means of achieving the required results.

Behavior↗
PubMed2005

[Similarity system theory to evaluate similarity of chromatographic fingerprints of traditional Chinese medicine].

The similarity evaluation of the fingerprints is one of the most important problems in the quality control of the traditional Chinese medicine (TCM). Similarity measures used to evaluate the similarity of the common peaks in the chromatogram of TCM have been discussed. Comparative studies were carried out among correlation coefficient, cosine of the angle and an improved extent similarity method using simulated data and experimental data. Correlation coefficient and cosine of the angle are not sensitive to the differences of the data set. They are still not sensitive to the differences of the data even after normalization. According to the similarity system theory, an improved extent similarity method was proposed. The improved extent similarity is more sensitive to the differences of the data sets than correlation coefficient and cosine of the angle. And the character of the data sets needs not to be changed compared with log-transformation. The improved extent similarity can be used to evaluate the similarity of the chromatographic fingerprints of TCM.

Chemical Fractionation↗
PubMed1997

Analysis of tracer transit in rat brain after carotid artery and femoral vein administrations using linear system theory.

Determination of tissue perfusion rates by MRI bolus tracking methods relies on the central volume principle which states that tissue blood flow is given by the tissue blood volume divided by the mean tracer transit time (MTT). Accurate determination of the MTT requires knowledge of the arterial input function which in MRI experiments is usually not known, especially when using small animals. The problem of unknown arterial input can be circumvented in animal experiments by directly injecting the contrast agent into a feeding artery of the tissue of interest. In the present article the passage of magnetite nanoparticles through the rat cerebral cortex is analyzed after injection into the internal carotid artery. The results are discussed in the framework of linear system theory using a one-compartment model for brain tissue and by using the well characterized gamma-variate function to describe the tissue concentration profile of the contrast agent. The results obtained from the intra-arterial tracer administration experiments are then compared with the commonly used intra-venous injection of the contrast agent in order to estimate the contribution of the peripheral circulation to the MTT values in the latter case. The experiments were analyzed using a two-compartment model and the gamma-variate function. As an application perfusion rates in normal and ischemic cerebral cortex of hypertensive rats were estimated in a model of focal cerebral ischemia. The results indicate that peripheral circulation has a significant influence on the MTT values and thus on the perfusion rates, which cannot be neglected.

Animals↗