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Results for “Systems Theory”

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At least 433 records · Page 24Linked to original sources
PubMed1994

The tricarboxylic acid cycle in Dictyostelium discoideum. Two methods of analysis using the same data.

The results of using metabolic control theory versus biochemical systems theory to analyze a model of the tricarboxylic acid cycle in Dictyostelium are described. The two types of analysis give essentially the same results, except that smaller responses to perturbations are observed for the model analyzed by metabolic control theory. The basis for this difference is discussed.

Animals↗
PubMed1993

Adolescent suicide and families: an ecological approach.

Suicide is an issue of increasing concern for professionals who work with adolescents and their families. Over the past three decades, the rate of suicide has increased dramatically among 15- to 24-year-olds and is the third leading cause of death in this age group. Previous theoretical approaches to understanding adolescent suicide (i.e., Durkheim's sociological theory of suicide, social learning theory, psychological theory, and family systems theory) are reviewed, and the utilization of human ecological theory is proposed. Factors associated with adolescent suicide at the organism (individual), microsystem, mesosystem, exosystem, and macrosystem levels are examined. Finally, examples of prevention and intervention at each level are presented.

Adolescent↗
PubMed1977

Towards a definition of living systems: a theory of ecological support for behavior.

It is proposed that the Darwinian theoretical approach and account of living systems has not yet been clearly given. A first approximation to this is attempted, focussing on behavior in evolving environments. A theoretical terminology is defined emphasizing the mutuality of organism and environment and the existence of biologically theoretical entities.

Animals↗
PubMedDate not supplied

Biogerontologic theories.

Theories of age and aging engage a wide variety of phenomena and levels of explanation. There is a general consensus that aging is a complex process or set of processes, involving many "causal" inputs and manifold consequences. Two general theoretical orientations that explicitly address complexity are sketched here-the differential theory of quantitative genetics and systems theory. Among the suggestions derived are that it may be advantageous to consider aging to be hierarchically organized, with the corollary that subsystems of an organism can have different functional or biological ages, and that several or many indices will be required to provide an adequate characterization of a single individual. Aging probably proceeds by saltation rather than continuously. Uncertainty associated with bifurcations in complex systems, together with individual differences in timing and magnitude of step changes, may constitute fundamental limitations to the predictability across the full life trajectory. Genetic and environmental influences will differ from hierarchical subsystem to subsystem, and may differ within a subsystem across chronological age.

Aging↗
PubMed2004

Staff supervision in residential care.

Residential care workers must be offered opportunities for formalized and systematic supervision in individual and group formats to provide the highest possible level of care to children and adolescents whom they serve. Effective supervision with residential care staff should be open to exploring issues at all levels of their experience and in relation to each component of the broader organizational structure within which they work. Systems theory offers a useful lens through which to view supervising staff in residential treatment. Systems theory proposes that human behavior is shaped by interactional processes and internal factors. Although the development of the individual occurs within intrinsic cognitive and emotional spheres, it also is believed to be related to several other elements. These additional variables include the point at which the family and system function in their own life cycle, the historical and current emotional context, the current and changing structure of the system, narratives, and the cultural context. This article discussed how methods of training and supervision would be most effective if they were designed specifically for the developmental level of the participants. Some literature reviews have concluded that youth care workers, like all professionals, pass through developmental stages and progress through them in their work. To assist youth care workers in their jobs, supervisors must understand these stages and the ways in which they may be enacted in the workplace.

Adolescent↗
PubMed1997

Highest level automatisms in the nervous system: a theory of functional principles underlying the highest forms of brain function.

A concept that all hierarchical levels of the nervous system are built according to the same functional principles is proposed. Each level is responsible for a discrete type or set of automatisms, is a learning system, and contains two distinct functional subdivisions: (1) a controller, a subsystem providing a governing set of rules or commands-a control law-that directs the action of the recipient of these rules-the controlled object; and (2) a model, a subsystem that generates a model of object behavior, i.e. afferent information flow expected from the controlled object. A control system such as this receives two types of afferent signals-initiating and informational. The difference between these signals is that a control system minimizes initiating signals during the realization of an automatism, i.e. a control neural network utilizes informational signals to compute the proper output that minimizes the initiating input signal. A mismatch or error signal, a type of initiating signal, is responsible for learning. Both the control law and the model can be adjusted during learning. The learning process starts when the error signal increases and stops when it is minimized. A network hierarchy is structurally and functionally organized in such a way that a lower control system in the nervous system becomes the controlled object for a higher one. This hierarchy leads to a generalization of encoded functional parameters and, consequently, the working space for each higher level control system becomes more abstracted. This is the reason why each hierarchical level within the control nervous system uses detectors specific for feature of the controlled object and the environment that match the control needs in order to obtain information about the current state of the object in the environment. Movement of information toward higher hierarchical levels also is accompanied by an increase in the duration of initiating signals within each control system. The ability to store a long prehistory of preceding events is considered as the mechanism that necessitated the invention of more complex and more rapid forms of learning such as operant learning, and made possible more complex multistep computational algorithms that require memorization of the results of previous intermediate computations. The functions of the cerebellum, the limbic system and the cortico-basal ganglia-thalamocortical loops are analyzed to illustrate the utility and applicability of this theoretical concept. Basal ganglia-thalamocortical loops are described as modeling, predictive loops, and their dopaminergic innervation as an error distribution system.

Automatism↗
PubMed2006

High-order excitations in state-universal and state-specific multireference coupled cluster theories: model systems.

For the first time high-order excitations (n>2) have been studied in three multireference couple cluster (MRCC) theories built on the wave operator formalism: (1) the state-universal (SU) method of Jeziorski and Monkhorst (JM) (2) the state-specific Brillouin-Wigner (BW) coupled cluster method, and (3) the state-specific MRCC approach of Mukherjee (Mk). For the H4, P4, BeH(2), and H8 models, multireference coupled cluster wave functions, with complete excitations ranging from doubles to hextuples, have been computed with a new arbitrary-order string-based code. Comparison is then made to corresponding single-reference coupled cluster and full configuration interaction (FCI) results. For the ground states the BW and Mk methods are found, in general, to provide more accurate results than the SU approach at all levels of truncation of the cluster operator. The inclusion of connected triple excitations reduces the nonparallelism error in singles and doubles MRCC energies by a factor of 2-10. In the BeH(2) and H8 models, the inclusion of all quadruple excitations yields absolute energies within 1 kcal mol(-1) of the FCI limit. While the MRCC methods are very effective in multireference regions of the potential energy surfaces, they are outperformed by single-reference CC when one electronic configuration dominates.

Journal Article↗
PubMed2006

The developmental/emergent model of archetype, its implications and its application to shamanism.

This paper addresses the ongoing debate in the JAP to do with archetype theory and supports an emergent/developmental model which sees archetypal imagery as an emergent phenomenon arising out of neural bio-structures laid down in early infant life as a result of developmental experience. This model is supported by the current findings of those developmental biologists who adhere to Developmental Systems Theory. The themes of Developmental Systems Theory are examined and corroborative parallels are drawn with the model. A number of implications follows: the model has substantial explanatory power and leads to a new perspective on innatism; it implies an archetype-environment nexus; it collapses the nature-nurture debate in relation to archetype theory; it collapses the 'sacred heritage' approach to archetypes and it removes the conceptual division between the collective and personal unconscious. This developmental/emergent perspective is then applied to the shaman archetype, using ethnographic records of the Sakha (Yakut) Siberian tribe. The material supports the hypothesis that the shamanic complex is laid down in early infancy by a combination of events which cause emotional ruptures in the mother-infant dyad. Siberian shamanism is then understood to arise out of developmental experience and not from the constellation of an autochthonous archetype.

Humans↗
PubMed1981

A systems analysis of psychobiology and behavior therapy. Implications for behavioral medicine.

This article examines some basic principles of systems theory and applies them to the integration of psychobiology and behavior therapy in the evolution of behavioral medicine. Using the concepts of whole/part relationships, level and emergent property, and self-regulation and disregulation, it is proposed that all behavioral therapies involve psychobiological processes, and therefore, indirectly impinge on physical health. It is argued that the distinction between behavior and biology is one of level, and, therefore, behavioral therapies are ultimately biobehavioral therapies having biobehavioral consequences. It is proposed that contrary to traditional reductionistic logic, modern advances in biology are providing strong justification for the importance of including psychological methods in treating diseases manifested at the biological level. Various clinical examples are used to demonstrate how systems theory can be applied to differential diagnosis and treatment, computing cost/benefit ratios of different treatments, and conducting comprehensive clinical research and evaluation. Assessing the interaction of biological, psychological, and social treatment modalities becomes the hallmark of responsible patient care. Implications of the systems conception of behavioral medicine for collaboration among health care providers, the training of future clinicians in different disciplines, and policy decisions regarding the larger social consequences of health care are considered.

Behavior Therapy↗
PubMed1996

Applying nursing theory to the practice of nurse anesthesia.

With the current movement of anesthesia education into graduate programs, changes in curriculum are inevitable. These changes will include advanced nursing theory. How the issues of nursing theory apply to the practice of nurse anesthesia are examined. Applications of Betty Neuman's systems theory are used in specific examples of the anesthesia role. The profession of nurse anesthesia may benefit significantly from the contributions of nursing theory.

Education, Nursing, Graduate↗
PubMed2006

After the fall of the Berlin Wall: perceptions and consequences of stability and change among middle-aged and older East and West Germans.

OBJECTIVES: This study empirically tested the self-systems theory of subjective change in light of the rapid change after the fall of the Berlin Wall. The theory predicts that individuals have a tendency to perceive stability and that perceived stability exerts a strong positive effect on subjective well-being. We would expect perceptions of decline and, to a lesser extent, perceptions of improvement to be related to lower levels of subjective well-being. METHODS: Data were from respondents aged 40-85 years who participated in the German Aging Survey. We used measures of well-being and temporal comparisons during the past 10 years (1986-1996). RESULTS: West Germans reported more stability than East Germans, in particular in the public domain and in older age groups. Compared with perceptions of stability, perceptions of decline were related to less life satisfaction and more negative affect, and perceptions of growth to more negative affect. Temporal comparisons were unrelated to positive affect. DISCUSSION: Our findings both confirm and reject the self-systems theory of subjective change as it relates to the fall of the Berlin Wall. Studying temporal comparisons is important in understanding the effects of historical events and their timing within an individual life course.

Adaptation, Psychological↗
PubMed1977

Systems simulation: theory of monosynaptic transfer between neuron populations.

This paper presents a theory for the input-output transformation involved in diffuse monosynaptic activation in a neural tissue or organ system of one population of neurons by another. Main findings are: (1) highly diffuse monosynaptic linkages act very much like filters, selectively sensitive to synchronized clusters of action potentials among the fibers of the input population; (2) partially diffuse monosynaptic linkages are capable of effecting either an amplification or diminution of the number of pulses involved in a single synchronized cluster, depending on parameters of the system; and (3) partially diffuse and spatially organized monosynaptic linkages are capable of effecting a spatial inversion of fine-grained spatial patterns. Theoretical predictions are clarified by mathematical analysis and computer simulation.

Action Potentials↗
PubMedDate not supplied

Neuroendocrine-immune interactions: a theoretical approach to aging.

Among the systemic theories of aging, both a 'nervous-neuroendocrine' and an 'immune' hypothesis have been proposed. The discovery of the complex interactions working among the neuroendocrine and the immune systems suggests the revision of the systemic theories of aging, particularly in the light of the recent evidence that some age-associated alterations in the neuroendocrine and in the immune systems are mutually interdependent even at very old age, as revealed by the fact that experimental manipulation of one of the two systems modifies and sometimes restores the function of the other one. These findings clearly demonstrate that at least some of the age-related alterations of the nervous, neuroendocrine and immune networks are not per se intrinsic and irreversible and that the definition of the temporal priority in the age-related deterioration is rather is rather difficult to be assigned to one or other homeostatic apparatuses. As an alternative to pure, either 'neuroendocrine' or 'immune', theories of aging, it has been hypothesized that, due to the strict interactions existing among the nervous, neuroendocrine and immune systems during the whole life of the organism, it is the disruption of such interactions in old age which is responsible for most of the age-associated dysfunctions (Fabris, 1986). This theoretical approach is discussed in the light of a stochastic or single-cause oriented hypothesis of aging.

Journal Article↗