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At least 199 records · Page 11Linked to original sources
PubMed1991

Change or homeostasis? A systems theory approach to depression.

Looking at the onset of depressive states in linear terms, there is often a problem of distinguishing cause and effect: did the adverse life-events cause the depression, or did the depression cause the adverse life-events? If we abandon linear thinking and look at depression in systemic terms, the problem of cause and effect disappears, but it is replaced by another problem: is the patient/environment system characterized by homeostasis or change? Some depressed patients seem to be spiralling down towards disaster. Others seem to be stuck in a rut. In systems terms, can depression be at the same time an agent of change and an agent of stasis (or even homeostasis)? The paradox can be resolved if we postulate that the function of depression is to reconcile the individual to an involuntarily subordinate social role; depression which reconciles to a pre-existing subordinate position has static properties; depression which mediates a switch to a subordinate position from a previously dominant position has properties of systemic change.

Depressive Disorder↗
PubMed2006

Towards systemic theories in biological psychiatry.

Although still rather controversial, empirical data on the neurobiology of schizophrenia have reached a degree of complexity that makes it hard to obtain a coherent picture of the malfunctions of the brain in schizophrenia. Theoretical neuropsychiatry should therefore use the tools of theoretical sciences like cybernetics, informatics, computational neuroscience or systems science. The methodology of systems science permits the modeling of complex dynamic nonlinear systems. Such procedures might help us to understand brain functions and the disorders and actions of psychiatric drugs better.

Antipsychotic Agents↗
PubMed1979

Using systems theory to organize confusion.

This paper represents an initial step in applying to complex clinical situations the symbolic logic developed by G. Spencer Brown and elaborated by Francisco Varela. This way of modeling turns out to yield an interesting mixture of rigidity, ambiguity, and paradox, perhaps inevitable at our present level of understanding of systems containing feedback. Applying the Brown-Varela concepts seems a useful transitional step toweard the future use of more sophisticated quantitative models such as those of Powers and Forrester.

Adolescent↗
PubMed2006

Feed-back between geriatric syndromes: general system theory in geriatrics.

Geriatrics has described three entities: confusional syndrome, incontinente and gait disorders, calling them geriatric giants. Aging process also induces changes in renal physiology such as glomerular filtration rate reduction, and alteration in water and electrolytes handling. These ageing renal changes have been named as nephrogeriatric giants. These two groups of giants, geriatric and nephrogeriatric, can predispose and potentiate each other leading old people to fatal outcomes. These phenomenon of feed-back between these geriatric syndromes has its roots in the loss of complexity that the ageing process has. Complexity means that all the body systems work harmoniously. The process of senescence weakens this coordination among systems undermining complexity and making the old person frail.

Aged↗
PubMed2006

Systems-theory of psychosis--the relevance of "internal censorship".

The different aspects of the neurobiology of psychotic disorders are presently discussed under the perspective of Arvid Calssons neurochemical theory of mesolimbic/cortico-thalamic loops. In this regard the question as to whether--neuropsychologically--a "filter-defect" or a disturbance of "internal censorship" is causative for psychoses. This topic is discussed in the present paper.

Adult↗
PubMed2004

Systems theory and the ethics of human enhancement: a framework for NBIC convergence.

Representatives from government and the private sector recommend a major, cooperative initiative directed toward using NBIC (nano-, bio-, info-, and cogno-) technologies for human enhancement. By appropriately seeding the convergence of NBIC domains, they believe that the rate of development can be both accelerated and simultaneously channeled to avoid adverse risk and advance human good. However, to accomplish these goals, leaders of the convergence efforts identified as a major intellectual barrier the "development of a hierarchical architecture for integrating science across many scales, disciplines, and data modalities." Such a holistic framework requires a radical rethinking of the nature of science and engineering, and, beyond this, is also necessary for addressing their normative ethical and societal implications. In the first part of this essay, I consider the claim that a new view of science and engineering is needed. After reviewing the central features of a classical view of science, I consider aspects of the nano-revolution, showing why the classical conception is inappropriate and how a systems-oriented perspective is responsive to the character of this new science. I then consider how both science and engineering are transformed, calling into question older dichotomies between pure and applied domains. With the reworking of this distinction comes opportunities for rethinking the relation between science and the humanities more generally, which is necessary if we are to more appropriately address normative ethical aspects of the convergence initiative. After providing this groundwork for the needed hierarchical architecture, I consider a useful example of how a systems perspective might guide NBIC convergence. In the 1960s-1990s George Engel advocated a systems-theoretic model as an alternative to a more reductionistic "biomedical model" in medicine, and he did it for the exact same reasons as those advocated by the leaders of the NBIC convergence; namely, it embodies a more appropriate notion of science and enables one to address ethical aspects of medicine that were insufficiently addressed in the older model. By reviewing Engel's "biopsychosocial model" we can learn important lessons for developing the needed NBIC framework. I close by extending Engel's model so that it addresses all areas of enhancement envisioned as a part of NBIC convergence, and then identify areas where future research is still needed.

Biomedical Enhancement↗
PubMed2004

[Surface electromyography signal classification using gray system theory].

A new method based on gray correlation was introduced to improve the identification rate in artificial limb. The electromyography (EMG) signal was first transformed into time-frequency domain by wavelet transform. Singular value decomposition (SVD) was then used to extract feature vector from the wavelet coefficient for pattern recognition. The decision was made according to the maximum gray correlation coefficient. Compared with neural network recognition, this robust method has an almost equivalent recognition rate but much lower computation costs and less training samples.

Electromyography↗
PubMed1995

Non-equilibrium systems theory: some applications for gerontological nursing practice.

1. In terms of NEST, aging can be understood as a process of formative change toward increasing disorder and order in form, pattern, or structure. The person moves toward greater complexity through self-organization processes. 2. Over time, self-organization processes result in increasingly unique perceptions and behavior. As an older person becomes more unique, he or she becomes more different from other older persons. 3. Self-organization processes are an appropriate focus of concern for nursing when NEST is used as a practice framework. The nurse tries to understand older persons' behaviors as outcomes of self-organization processes (attempts to bring order out of disorder).

Adaptation, Psychological↗
PubMed1963

System theory and physiological processes. A physiologist looks at engineering.

Over the past centuries physiology has weathered a series of revolutions generated by the introduction of powerful tools and concepts from other disciplines, notably physics and chemistry. On each occasion such infusion of new ideas has enormously strengthened and enriched physiology. Today, the introduction of tools and concepts from engineering promises another revolution with another strengthening and enrichment. Among the things engineering has to offer are some that are close to the heart of physiology. These must be adapted and thoroughly integrated into the body of physiological concepts, attitudes, and operations. This goal presents a challenge which physiologists cannot afford to ignore. It calls for an "operation bootstrap" on the part of those of us long past our student days. It will entail a changing pattern of undergraduate preparation and graduate education for those who will become the physiologists of the coming generation. But a welcoming of the challenge and an encouragement of efforts to meet it will transform this opportunity, as others have been transformed, into another revolutionary advance in physiology.

Education, Graduate↗
PubMed2006

Systems theory of Smad signalling.

Transforming growth factor-beta (TGFbeta) signalling is an important regulator of cellular growth and differentiation. The principal intracellular mediators of TGFbeta signalling are the Smad proteins, which upon TGFbeta stimulation accumulate in the nucleus and regulate the transcription of target genes. To investigate the mechanisms of Smad nuclear accumulation, we developed a simple mathematical model of canonical Smad signalling. The model was built using both published data and our experimentally determined cellular Smad concentrations (isoforms 2, 3 and 4). We found in mink lung epithelial cells that Smad2 (8.5-12 x 10(4) molecules cell(-1)) was present in similar amounts to Smad4 (9.3-12 x 10(4) molecules cell(-1)), whereas both were in excess of Smad3 (1.1-2.0 x 10(4) molecules cell(-1)). Variation of the model parameters and statistical analysis showed that Smad nuclear accumulation is most sensitive to parameters affecting the rates of R-Smad phosphorylation and dephosphorylation and Smad complex formation/ dissociation in the nucleus. Deleting Smad4 from the model revealed that rate-limiting phospho-R-Smad dephosphorylation could be an important mechanism for Smad nuclear accumulation. Furthermore, we observed that binding factors constitutively localised to the nucleus do not efficiently mediate Smad nuclear accumulation, if dephosphorylation is rapid. We therefore conclude that an imbalance in the rates of R-Smad phosphorylation and dephosphorylation is likely an important mechanism of Smad nuclear accumulation during TGFbeta signalling.

Animals↗