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PubMed2001

Modelling home televisiting services using systems dynamic theory.

A quantitative model was developed to study the provision of a home televisiting service. Systems dynamic theory was used to describe the relationships between quality of care, accessibility and cost-effectiveness. Input information was gathered from the telemedicine literature, as well as from over 75 sessions of a televisiting service provided by the Severo Ochoa Hospital to 18 housebound patients from three different medical specialties. The model allowed the Severo Ochoa Hospital to estimate the equipment needed to support increased medical contacts for intensive cardiac and other patients.

Adult↗
PubMed1979

Synaptic function in the nervous system: a theory and its application.

The objective of this paper is to present a new theory of synaptic function in the nervous system. The basis for this theory is the experimental demonstration that a nerve impulse assumes five different forms as it advances through the synaptic region, and that five basic mathematical operations have been identified as being involved in the transformation of one form into another form. As a result of these data, the synaptic region is regarded as a functional unit where information coming to it is unpacked, processed, stored, and retrieved for transit to another synaptic region or effector site. The data also suggests that a nerve impulse is a bolus of energy, therefore, without substance; that it contains information coded in its shape or form; that it is precisely described mathematically. Furthermore, the data suggests synaptic regions process these nerve impulses by applying mathematical operations to them; that function in the synaptic region is highly stereotyped (programmed); that chemical substances are associated with the mathematical operations. The basic approach of this theory is to regard a significant portion of the nervous system as an 'interface' between the external universe and man himself. As an interface, the nervous system receives and processes information from both the external universe and man himself in a programmed manner. The interface functions by converting the information it receives into a bolus of energy, the nerve impulse, then processes the bolus by converting it into numbers or functions and applying mathematical operation to it.

Acetylcholine↗
PubMedDate not supplied

[Control of molecular transformations in polyenzyme systems: quantitative theory of the regulation of metabolism].

An attempt of a comprehensive treatment of the theory of metabolic control is presented. The introductory section giving an outline of the early development of the theory, is followed by definitions quantifying the control in the metabolic system. By means of the perturbation method the complete system of equations is obtained which allows one to express all the enzyme control coefficients ("global" coefficients) through the elasticity coefficients characterizing kinetic properties of individual enzymes ("local" coefficients) and through the steady-state values of metabolic fluxes and concentrations. It is shown how connectivity relations between global and local coefficients should be modified when conserved sums of intermediates are present in the system. A new theorem is derived, it allows one to express the global response of the system to any change in the external parameter (such as external effector concentration, or temperature, pH, ionic strength, ets.) through the control coefficients and local responses of individual reaction steps. Explicit formulas are derived for response coefficients of the fluxes and concentrations to changes in the conserved sums of intermediates, which express the values of these global coefficients through the control and elasticity coefficients of enzymes and steady-state pools. The results obtained comprise as a special case all the results published so far in the literature.

Kinetics↗
PubMed1994

Family therapy and the Igbo family system.

Theories and treatment modalities may differ in the degree to which they are applicable to different groups. This paper examines the applicability of Bowen's family therapy concepts to a culturally different family system, the Igbo of Southeastern Nigeria. The analyses point to the importance of understanding client value orientations in planning appropriate care.

Cultural Characteristics↗
PubMed2001

[A.A. Malinovskiĭ and significance of the system approach in gerontology].

A.A Malinovsky allocated 4 most important principles of the system theory: discreteness/rigidity of system, presence of feedback, occurrence of new properties at association of elements in system, a continuity and the maximal fitness in evolution. He believed that the essential factor determining life longevity of the individual are his species-specific characteristics. A.A. Malinovsky together with coworkers has revealed the attributes most connected to increase of terms of life: a high degree of the cephalization and the big sizes of a body. He also emphasized, that with an exit on a high intellectual level people have occupied especially position at which the biological factors influencing life longevity, began to lose paramount signification, value of long life has increased. The increase of life longevity has resulted in the important consequence--to increase of the number of diseases at late age. The diseases with hereditary predisposition have got the big weight. A.A. Malinovsky considered 4 basic levels of a condition of functions of an organism. The level of the maximal pressure--mobilization of all forces of an organism on type of "emergency alarm", promotes wear process of an organism and disorder of its separate functions. Damage of the weakest link translates an organism from a stable condition in pathological when the depression of one function reduces a level of others which in turn, even more can suppress the first, resulting in to a vicious circle (a positive feedback). A.A. Malinovsky has entered concept about increasing "disregulation" of the functions of an organism during ageing as to the main reason limiting human life. He assumed, that such rigid system (organism) which has strong link (subsystem), and other subsystems function approximately at one level has the greatest stability. It is possible, that presence of weakest links is connected to size of a genetic load. Our paper demonstrates the importance of A.A. Malinovsky system approach for such field of knowledge as gerontology.

Aging↗
PubMedDate not supplied

The family systems approach and pediatric nursing care.

The pediatric nurse is increasingly called upon to function as a family specialist, yet many nurses have assumed this role with little or no training in family systems theory. The family systems approach to pediatric nursing care maximizes family strengths. The nurse and family collaborate to identify important family needs and to match needs with resources. The primary goal is family empowerment. A basic understanding of the family systems approach to assessment and intervention can help pediatric nurses function more effectively in this role.

Adult↗
PubMed1998

Family systems and adolescent development: shared and nonshared risk and protective factors in nondivorced and remarried families.

The primary goal of this research is to increase the goodness-of-fit between the theoretical tenets of family systems theory and quantitative methods used to test systems hypotheses. A family systems perspective is applied to two specific research questions concerning family influences on adolescent development: To what extent are familial risk and protective factors for psychopathology and competence shared or not shared by siblings and are different family relationship patterns associated with optimal adolescent adjustment in nondivorced and remarried families? Multirater and multimethod data from a national sample of 516 nondivorced and remarried families from the Nonshared Environment and Adolescent Development (NEAD) project were examined using a combination of cluster, factor, and regression analyses. Results indicated that the effects of an individual relationship on adolescent adjustment is moderated by the larger network of relationships in which it is embedded. Evidence for nonshared familial processes in predicting adolescent psychopathology was also found but only in a subset of families, and the mechanisms of influence were neither main effects nor linear, as has been assumed by research to date. Results are discussed in light of family systems models of relationship influence on development. These results illustrate how family systems theory provides a specific example of contextualism as regards the development of psychopathology in adolescence.

Adaptation, Psychological↗
PubMed1999

GLLS for optimally sampled continuous dynamic system modeling: theory and algorithm.

The original generalized linear least squares (GLLS) algorithm was developed for non-uniformly sampled biomedical system parameter estimation using finely sampled instantaneous measurements (D. Feng, S.C. Huang, Z. Wang, D. Ho, An unbiased parametric imaging algorithm for non-uniformly sampled biomedical system parameter estimation, IEEE Trans. Med. Imag. 15 (1996) 512-518). This algorithm is particularly useful for image-wide generation of parametric images with positron emission tomography (PET), as it is computationally efficient and statistically reliable (D. Feng, D. Ho, Chen, K., L.C. Wu, J.K. Wang, R.S. Liu, S.H. Yeh, An evaluation of the algorithms for determining local cerebral metabolic rates of glucose using positron emission tomography dynamic data, IEEE Trans. Med. Imag. 14 (1995) 697-710). However, when dynamic PET image data are sampled according to the optimal image sampling schedule (OISS) to reduce memory and storage space (X. Li, D. Feng, K. Chen, Optimal image sampling schedule: A new effective way to reduce dynamic image storage space and functional image processing time, IEEE Trans. Med. Imag. 15 (1996) 710-718), only a few temporal image frames are recorded (e.g. only four images are recorded for the four parameter fluoro-deoxy-glucose (FDG) model). These image frames are recorded in terms of accumulated radio-activity counts and as a result, the direct application of GLLS is not reliable as instantaneous measurement samples can no longer be approximated by averaging of accumulated measurements over the sampling intervals. In this paper, we extend GLLS to OISS-GLLS which deals with the fewer accumulated measurement samples obtained from OISS dynamic systems. The theory and algorithm of this new technique are formulated and studied extensively. To investigate statistical reliability and computational efficiency of OISS-GLLS, a simulation study using dynamic PET data was performed. OISS-GLLS using 4-measurement samples was compared to the non-linear least squares (NLS) method using 22-measurement samples, GLLS using 22-measurement samples and OISS-NLS using 4-measurement samples. Results demonstrated that OISS-GLLS was able to achieve parameter estimates of equivalent accuracy and reliability in comparison to NLS or GLLS using finely sampled measurements (22-measurement samples), or OISS-NLS using optimally sampled measurements (4-measurement samples). Further more, as fewer measurement samples are used in OISS-GLLS, this algorithm is computationally faster than NLS or GLLS. Therefore, OISS-GLLS is well-suited for image-wide parameter estimation when PET image data are recorded according to the optimal image sampling schedule.

Algorithms↗
PubMed2005

Deleterious mutation in related species of the plant genus Amsinckia with contrasting mating systems.

Theory for the evolution of modifiers of the rate of mutation suggests that a lower rate of mutation may evolve after the breakdown of mechanisms that enforce outcrossing. Mutation accumulation (MA) experiments were conducted to compare deleterious mutation parameters in two closely related species of the plant genus Amsinckia, a group that exhibits wide variation in the mating system. One of the two species studied (A. douglasiana) is predominantly outcrossed in natural populations, where as the other species (A. gloriosa) is predominantly self-pollinated. Progeny assays of flower number per plant from generation 1 lines (control) and generation 11 lines (MA treatment) were conducted in both species. Dry weight measurements of progeny from the control and MA treatment in A. douglasiana also were made. Estimation of mutation parameters was conducted using maximum likelihood under the assumption of a gamma distribution of mutational effects. The two species exhibited similar rates and effects of deleterious mutation affecting flower number. Estimates of mutation rate for dry weight in A. douglasiana are close to those for flower number. Overall, the estimates of mutation parameters observed in these species are intermediate within the range reported for fitness components in other eukaryotes. The results are discussed within the context of evolutionary change in deleterious mutation accompanying mating system evolution and with respect to previous estimates of mutation parameters based on assays of inbreeding depression and the assumption of mutation-selection equilibrium.

Amsinckia↗
PubMed2004

Costs of resistance: genetic correlations and potential trade-offs in an insect immune system.

Theory predicts that natural selection will erode additive genetic variation in fitness-related traits. However, numerous studies have found considerable heritable variation in traits related to immune function, which should be closely linked to fitness. This could be due to trade-offs maintaining variation in these traits. We used the Egyptian cotton leafworm, Spodoptera littoralis, as a model system to examine the quantitative genetics of insect immune function. We estimated the heritabilities of several different measures of innate immunity and the genetic correlations between these immune traits and a number of life history traits. Our results provide the first evidence for a potential genetic trade-off within the insect immune system, with antibacterial activity (lysozyme-like) exhibiting a significant negative genetic correlation with haemocyte density, which itself is positively genetically correlated with both haemolymph phenoloxidase activity and cuticular melanization. We speculate on a potential trade-off between defence against parasites and predators, mediated by larval colour, and its role in maintaining genetic variation in traits under natural selection.

Analysis of Variance↗
PubMed1999

Quantitative tools for comparing animal communication systems: information theory applied to bottlenose dolphin whistle repertoires.

Comparative analysis of nonhuman animal communication systems and their complexity, particularly in comparison to human language, has been generally hampered by both a lack of sufficiently extensive data sets and appropriate analytic tools. Information theory measures provide an important quantitative tool for examining and comparing communication systems across species. In this paper we use the original application of information theory, that of statistical examination of a communication system's structure and organization. As an example of the utility of information theory to the analysis of animal communication systems, we applied a series of information theory statistics to a statistically categorized set of bottlenose dolphin Tursiops truncatus, whistle vocalizations. First, we use the first-order entropic relation in a Zipf-type diagram (Zipf 1949 Human Behavior and the Principle of Least Effort) to illustrate the application of temporal statistics as comparative indicators of repertoire complexity, and as possible predictive indicators of acquisition/learning in animal vocal repertoires. Second, we illustrate the need for more extensive temporal data sets when examining the higher entropic orders, indicative of higher levels of internal informational structure, of such vocalizations, which could begin to allow the statistical reconstruction of repertoire organization. Third, we propose using 'communication capacity' as a measure of the degree of temporal structure and complexity of statistical correlation, represented by the values of entropic order, as an objective tool for interspecies comparison of communication complexity. In doing so, we introduce a new comparative measure, the slope of Shannon entropies, and illustrate how it potentially can be used to compare the organizational complexity of vocal repertoires across a diversity of species. Finally, we illustrate the nature and predictive application of these higher-order entropies using a preliminary sample of dolphin whistle vocalizations. The purpose of this preliminary report is to re-examine the original application of information theory to the field of animal communication, illustrate its potential utility as a comparative tool for examining the internal informational structure of animal vocal repertoires and their development, and discuss its relationship to behavioural ecology and evolutionary theory. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1983

Analysis of the rate-limiting step in a ligand-cell receptor interaction: the immunoglobulin E system.

Theory predicts that the kinetics of simple interactions between a ligand and a receptor bound on the surface of a cell will be affected by the occupancy of receptors on the same cell. In a diffusion-limited reaction the effect will be on the rate of dissociation but not on the rate of association until the cell is virtually saturated with ligand. If the rate of reaction is not diffusion limited, then the opposite holds; i.e., the forward velocities will be proportional to the concentration of vacant receptors, but the reverse reactions will not be. We examined the kinetics of reaction between immunoglobulin E (IgE) and its receptor and clearly demonstrated that the reaction is not diffusion controlled. The substantial (congruent to 30-fold) increase in the forward rate constant observed for the reaction of IgE with solubilized receptors as opposed to cell-bound receptors is therefore not an artifact of calculation. Since the reverse rate constants show little difference, we postulate that the presence of other surface components (rather than conformational differences in the receptor) affects the reaction with the cells. As an aid to the analysis, the theory has been extended so that not only the rate constants but also the entire course of the reaction of ligand with cell receptors can be predicted for diffusion-limited vs. non-diffusion-limited interactions.

Animals↗
PubMed2002

Cross-polarization/magic angle spinning NMR to study glucose mobility in a model intermediate-moisture food system.

Theories for the chemical stability of foods cite the role of moisture content or water activity in reactant mobility, though mobility has been variously defined. One theory, based on plasticization by moisture, is limited by a lack of research directly linking the mobility of a matrix to the mobility and reactivity of small solute molecules in foods. A cross-polarization/magic angle spinning technique was developed to study glucose rotational mobility in the solid state over a range of water activities and in matrixes with different glass transition temperatures. Data analysis stressed the significance of separating molecular mobility from relaxation time. Results showed that, in a caseinate matrix, compared to a control, adding glycerol yielded the highest glucose mobility and lowest glass transition temperature (T(g)), while adding sorbitol also increased mobility and lowered T(g). Consequently, plasticization by either moisture or these humectants increases the mobility of small solute molecules such as glucose.

Chemical Phenomena↗
PubMed2003

Relapse as a nonlinear dynamic system: application to patients with alcohol use disorders.

Understanding the relapse process is one of the most important issues in addictive behaviors research. To date, most studies have taken a linear approach toward predicting relapse based on risk factors. Nonlinear dynamical systems theory can be used to describe processes that are not adequately modeled using a linear approach. In particular, the authors propose that catastrophe theory, a subset of nonlinear dynamical systems theory, can be used to describe the relapse process in addictive behaviors. Two small prospective studies using 6-month follow-ups of patients with alcohol use disorders (inpatient, n = 51; outpatient, n = 43) illustrate how cusp catastrophe theory may be used to predict relapse. Results from these preliminary studies indicate that a cusp catastrophe model has more predictive utility than traditional linear models.

Adult↗
PubMed2006

From vagueness in medical thought to the foundations of fuzzy reasoning in medical diagnosis.

OBJECTIVE: This article delineates a relatively unknown path in the history of medical philosophy and medical diagnosis. It is concerned with the phenomenon of vagueness in the physician's "style of thinking" and with the use of fuzzy sets, systems, and relations with a view to create a model of such reasoning when physicians make a diagnosis. It represents specific features of medical ways of thinking that were mentioned by the Polish physician and philosopher Ludwik Fleck in 1926. The paper links Lotfi Zadeh's work on system theory before the age of fuzzy sets with system-theory concepts in medical philosophy that were introduced by the philosopher Mario Bunge, and with the fuzzy-theoretical analysis of the notions of health, illness, and disease by the Iranian-German physician and philosopher Kazem Sadegh-Zadeh. MATERIAL: Some proposals to apply fuzzy sets in medicine were based on a suggestion made by Zadeh: symptoms and diseases are fuzzy in nature and fuzzy sets are feasible to represent these entity classes of medical knowledge. Yet other attempts to use fuzzy sets in medicine were self-contained. The use of this approach contributed to medical decision-making and the development of computer-assisted diagnosis in medicine. CONCLUSION: With regard to medical philosophy, decision-making, and diagnosis; the framework of fuzzy sets, systems, and relations is very useful to deal with the absence of sharp boundaries of the sets of symptoms, diagnoses, and phenomena of diseases. The foundations of reasoning and computer assistance in medicine were the result of a rapid accumulation of data from medical research. This explosion of knowledge in medicine gave rise to the speculation that computers could be used for the medical diagnosis. Medicine became, to a certain extent, a quantitative science. In the second half of the 20th century medical knowledge started to be stored in computer systems. To assist physicians in medical decision-making and patient care, medical expert systems using the theory of fuzzy sets and relations (such as the Viennese "fuzzy version" of the Computer-Assisted Diagnostic System, CADIAG, which was developed at the end of the 1970s) were constructed. The development of fuzzy relations in medicine and their application in computer-assisted diagnosis show that this fuzzy approach is a framework to deal with the "fuzzy mode of thinking" in medicine.

Diagnosis↗