Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CYBERNETICS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed1984

[On the concept of "information"].

The recent approaches of generalization of "information" beyond the classical field of communication theory are characterized by explication and by first suggestions of generalized information theories. A critical assessment of the two books "Information I" and "Information II" written by H. VOLZ are given to what extent they may contribute to this discussion. Especially, the new definition of an all-embracing notion of information given in these books is criticized because it seems not to be suited as basis for a generalized theory. In contrast to this, the idea of information as a measure of structural differences between probability distributions in a state space is proposed for mathematical description of specific biological properties in general. In this view, the one distribution is that of the physical possibilities and the other is that which is connected with the realizations by the biological system. The latter consists of the states which are optimal for the function of the biological system. They are selected from the set of physically possible states. As abstract mathematical quantity the statistical entropy of a random experiment is used. Finally it is indicated that this information-theoretical description may contribute to the understanding of the connections between physics, cybernetics, and biology.

Information Theory↗
PubMedDate not supplied

Blocking cybernosis in endocrine glands pathology.

The term cybernosis was proposed by Meerloo (1971) in order to designate the cybernetic functional disorders in senescence. Blocking cybernosis or bloking negative feedback is the term used for negative feedback perturbation in a neuro-endocrine subsystem caused by factors dwelling inside or outside it. Using the hypothalamo-hypophyso-adrenocortical subsystem as a model, the author shows that due to an excessive and anarchic secretion of corticoids by a tumor developed in the adrenocortical, the hypothalamo-hypophyseal control centers are blocked. A similar blockade occurs after longterm administration of high doses of a steroid, similar or identical to the natural corticoid hormone, which retro-acts like the latter. In the first case we deal with tumoral blocking cybernosis, in the second, with an iatrogenic one. As in both cases the subsystems are turned off without structural desorganization, the term blockade is more appropriate than that of disorder which implies the existence of a certain functional disability. Tumoral blocking cybernoses were seen by us in thyroid toxic adenoma, corticosteroid secreting adenomas and ovarian tumors; iatrogenic cybernoses occur in the long-term corticosteroid therapy in dermatoses, hirsutism, etc. Blocking cybernoses, both tumoral and iatrogenic, require great caution in their correction. Sudden removal of the blockade is followed by severe disorders producing collapse and coma with their implicit risk.

Biofeedback, Psychology↗
PubMed1983

[Comparison of 4 methods of evaluating protein quality in vegetable sources].

This study compares the practical value of the following methods: protein efficiency ratio (PER), blood urea concentration in rats (BUC), relative nutritive value (RNV), and predicted protein value (PPV) to evaluate the protein quality of 41 diets of plant origin. Results demonstrated low correlations between PER and RNV (r = 0.66), PER and PPV (r = 0.53), RNV and PPV (r = 0.54), whereas there was a high negative correlation between PER and BUC (r = -0.89). These different procedures can be useful and valid for distinct and well-defined objectives, but the evaluation of results must be made in accordance with the purpose of the experiment. In assessing the protein quality of foodstuffs, it is therefore recommended that mathematical computer models be developed which take into account the cybernetic system of the amino acid metabolism. This would definitely reduce the actual need of expensive long-term biological assays.

Amino Acids↗
PubMed1984

[Accommodation in strabismus].

This paper describes clinical observations of optico-sensori-motor symptomatology prior to and during treatment for strabismus. These findings were compared with theoretical data of the binocular visual function. We consider that binocular function has the structure and the working of a "set" in cybernetic sense. In this psycho-physiological set, the accommodative system constitutes a "sub-set". The classification of accommodative disturbances as "pure or impure" and "typical or atypical" arises from the fact that a rebuilding of the visual function has occurred. Thus in "pure" accommodative strabismus the disturbances of accommodation results from "peripheral" accommodation and is easily reversible. In this situation ocular deviation has been perfectly corrected for and binocular vision normally built up since there is enough compensation of the whole optical correction. In "impure" accommodative strabismus the perturbation of accommodation affects the whole accommodation system and also the sensorial motor system. Thus there is a restructuring of the optico-sensori-motor set that is more or less reversible due to a variety of factors. From these investigations we conclude: every strabismus is accommodative in the sens that in every strabismus there is a disturbance of accommodative mechanism. Furthermore, we oppose believers of "all sensorial" and "all motor" mechanisms. Considering that strabismus is a disturbance of optico-sensori-motor binocularity, nothing can be only "accommodative", only "sensorial" and only "motor". From this it follows that treatment should not be only "motor", only "accommodative" or only "sensorial".

Accommodation, Ocular↗
PubMed1980

[Growth hormone: mode of action on different varieties of cartilage (author's transl)].

1) The growth of epiphyseal cartilages of long bones, of spheno-occipital synchondrosis of the cranial base, of the cartilage of the nasal septum, of lateral cartilaginous masses of the ethmoid, of cartilage between body and greater wings of the sphenoid (all stemming from the primary cartilaginous skeleton of the organism), is subject to general extrinsic factors and, more specifically, to the growth hormone (STH) and somatomedin. In this case, orthopedic devices can alterate the direction but not the amount of growth. 2) The growth of condylar, coronoid and angular cartilages of the mandible, of the cartilage of the midpalatal suture, and of the cartilage in some cranial sutures (all of secondary formation during phylogenesis and ontogenesis) is subject to local extrinsic factors as well as to growth hormone and somatomedin. In this case, appropriate orthopedic devices may modulate both the direction and the amount of growth. 3) Our cybernetic models attempt to account for the mechanisms of facial growth. By intensifying the forward growth of the nasal septum cartilage, the STH and somatomedin stimulate the forward growth of the upper jaw, i.e. the forward positioning of the superior dental arch (the position of which is the "constantly changing reference input" of the servosystem). The "operation of confrontation" between the position of the upper and lower occlusal surfaces (the position of the lower dental arch is the "controlled variable" of the servosystem) gives then rise to a "deviation signal" (originating from detectors of occlusal adjustment) whose "reduction" is made possible by a supplementary postural activity of the lateral pterygoid muscle resulting, extemporaneously, in an appropriate forward positioning of the mandible and, with time, in a supplementary growth of the condylar cartilage. By intensifying the outward growth of lateral cartilaginous masses of the ethmoid and of the cartilage between the body and greater wings of the sphenoid, the STH and somatomedin bring about a lateralization of both the left and right sides of the upper jaw and, in this way, stimulate the growth of the secondary cartilage of the midpalatal suture.

Animals↗
PubMedDate not supplied

[Criticism of the current theories concerning the formation of the immunological repertory].

Application of the probability calculus to the variational structure of the immunoglobulins leads to demonstrate the impossibility of the random production of the repertory's antibodies. Physical and Cybernetic considerations lead, instead, to demonstrate the necessary existence of aspecific recognition of the antigen, i.e. of the antigen's activity. Application of the theory of stochastic convergence, at last, leads to demonstrate that, if there would be a connection between this aspecific recognition and the antibody's production, the latter would be possible. This connection, as a consequence, must exist.

Antibody Formation↗
PubMed1982

[The modelling of growth processes].

Hitherto developed presentation of processes of growth will be tested in this paper. For this end a previous explained cybernetical structure is developed to a model of an analog-computer. In this way it is possible to simulate the growth function of the embryofetal curve of the length' increase of man and the curve of the mass' increase of rat. It turns out a very good correspondence between the measured and the simulated curves. There is given an algorithm to simulate every curve of growth of the examined type. Some remarks of the origin of the explained ideas will round this paper.

Animals↗
PubMed1982

A report on the AANA Manpower Study--Part I.

Future reports to be released by the Center for Cybernetic Studies will present the occupational structure of the nurse anesthetist and will combine demographic data with a task analysis of the profession. This report has selected some variables of interest and analyzed them. Most important, however, is the intended flexibility that this data based information system should offer. For example, human resource modeling will forecast the number of nurse anesthetists who remain in or leave a given region. This modeling capability could aid schools of anesthesia in their curriculum planning by showing which tasks are predominant in a given location. It could also aid members by providing pertinent employment information. Future reports will present a scenario to exemplify how a data based information system can derive a series of human resource models. The purpose of such an exercise is to develop for the AANA the planning methods some of the larger corporations are already utilizing. The difference, of course, is that these planning methods could be used by the professional association of nurse anesthetists for the advantage of its members. This article has presented a short review of the Manpower Study. We welcome your ideas and suggestions to aid us in making future analyses of this information.

Anesthesiology↗
PubMed1980

Correlation technique and its application in the His bundle electrocardiogram.

In literature, the HBE has been displayed by application of the averaging method. In this paper, correlation analysis technique was used and the body-surface HBE was displayed in a special-purpose electronic computer. The correlation coefficients of the P-A, A-H, H-V intervals and the H-wave width of both methods are almost equivalent and one can be substituted by the other. Compared with the averaging method, the S/N ratio of the correlation method is greater and the residual noise is nearly absent. Furthermore, the effects of the integrating time T and delay time delta tau on the S/N ratio, the measuring resolution and the analytical time have been studied. Correlation analysis technique is a method based on the cybernetic and information theory. With this technique, by using correlation function, the dependence (auto-correlation function) of the value at one instant upon that of the other during the same random process, or the interdependence between sets of data from 2 random processes can be described. Up to the present, there has been no report on the activities of the ventricular conductive system with the S/N ratio smaller than 1, detected on the body surface by correlation analysis technique[1 - 3]. However, using this technique, the author successfully detected the body surface HBE with a special-purpose mini-computer in 1977.

Bundle of His↗
PubMedDate not supplied

[Life experiences and differential aspects of the social relations of the aged in facilities for the aged. Empirical findings from 3 Hamburg facilities].

In the beginning it is illustrated that there is a number of problems in the different fields of open care and work with institutionalized old people which could be better solved or reduced by an integrative approach. It is the goal of this report to make evident that there are wrong attitudes towards living in institutions which are - besides other barriers - hindering for the realization of such an integrative approach. After a view over the organization-structure and the supply offered by the institutions, the average-home-inhabitants are presented - from a cybernetical point of view - as "open systems" who take part in an exchange of "input" and "output" and who are able to realize more or less wide life experiences. There are significant differences between the institutions with regard to the conception and the organization-structure of the homes. The social contacts-distinguished between different patterns of contact, contact partners and inside/outside-orientation of the social contacts - are analysed and presented in their differential relations to the life satisfaction measures. The relative close correlation between different patterns of collective contacts and the measures of life satisfaction are especially interesting, because from these findings practical consequences for the organization of home-life and for the counseling of old people in the choice between the alternative offers of help can be deducted.

Aged↗
PubMed1978

[Fundamental problems of ageing (author's transl)].

Issuing from the second theorem of thermodynamics a cybernetical schema and a corresponding system of differential equations are proposed, describing dehydration and diminishing metabolism rate of the aging cell. With respect to the organism as a whole, there results the well known vitality formula of Beier, but with an altered expression for F(t).

Aging↗
PubMed1978

[Voice and vibration sensations in the speech forming organs: clinical and theoretical aspects of rare symptoms specific for schizophrenia].

When studying 750 psychiatric in-patients with psychoses of various diagnostic groups, the symptoms of voice sensations and vibration feelings could only be found among patients with paranoid schizophrenia. In addition, these symptoms were located exclusively in body areas that are involved in the peripheral motor production of voice and speech (areas of head, throat, thorax). In 11 of 15 such cases that could be identified, the sensations of voices and vibrations occurred simultaneously and in identical body parts; in the remaining 4 cases only voices without vibration sensations were reported. Therefore these symptoms can be considered as highly specific for schizophrenia. According to the terminology of Bleuler these two symptoms are because of their rareness to be taken as accessoric symptoms; according to the terminology of Kurt Schneider they have the value of first rank symptoms because of their highly diagnostic specifity for schizophrenia. The pathogenesis of these symptoms is on the one hand discussed under the perspective of language development and the changing function of language for behaviour control; on the other hand, the pathogenesis of these symptoms is discussed from the viewpoint of cybernetic, or neurophysiological-neuroanatomical foundation of speech production and speech control. Both models of explanation have in common that the ideational component of speech is noticed as acustic halluzinations and the motor proprioceptive part of speech is noticed as sensation of vibrations, both in a typically schiphrenic manner, i.e. dissociated and ego-alienated.

Adult↗
PubMed1995

Radiogenic responses of normal cells induced by fractionated irradiation--a simulation study. Part II. Late responses.

AIM: Based on controlled theory, a computed simulation model has been constructed which describes the time course of slowly responding normal cells after irradiation exposure. Subsequently, different clinical irradiation schemes are compared in regard to their delayed radiogenic responses referred to as late effects in radiological terminology. METHOD: A cybernetic model of a parenchymal tissue consisting of dominantly resting functional cells has been developed and transferred into a computer model. The radiation effects are considered by characteristic cell parameters as well as by the linear-quadratic model. RESULTS: Three kinds of tissue (brain and lung parenchyma of the mouse, liver parenchyma of rat) have been irradiated in the model according to standard-, super-, hyperfractionation and a single high dose per week. The simulation studies indicate that the late reaction of brain parenchyma to hyperfractionation (3 x 1.5 Gy per day) and of lung parenchyma tissue with regard to all fractionation schemes applied is particularly severe. In contrast to these observations the behavior of liver parenchyma is not unique: If Dtotal amounts to 60 Gy there is no evidence for compensation of radiation damages, but if Dtotal is restricted to 30 Gy the corresponding evidence can be expected for all schemes. In the case of a high single dose of 6 Gy a reduction of the recovery time from 1 week to 2...2 days yields also an indication of a severe damage, even if Dtotal amounts only to 30 Gy. CONCLUSIONS: A comparison of the simulation results basing to the survival of cell numbers with clinical experience and practice shows that the clinical reality can qualitatively be represented by the model. This opens the door for connecting side effects to normal tissue with the corresponding tumor efficacy (discussed in previous papers). The model is open to further refinement and to discussions referring to the phenomenon of late effects.

Animals↗
PubMedDate not supplied

[Medical stimulators for biological feedback].

The fact that a physiological function generally unconsciously controlled can be self-regulated was demonstrated as long as 20 years ago. The biological feedback (BF) is the back return of information to a man or an animal on the function of their viscera and systems. BF is a process that through audible or visual signals transmits long-term routine information on physiological reactions and parameters, such as blood pressure and skin temperature, which are uncontrollable by an individual's consciousness and generally recorded by noninvasive techniques. Biological controlling techniques and procedures are used for the treatment and rehabilitation of a wide range of diseases and nosological entities -- from migraine to AIDS and cancer mainly in the USA, less in Western Europe, and incomparably little in the CIS countries. The Novosibirsk Institute of Medical and Biological Cybernetics, Siberian Branch of the Russian Academy of Medical Sciences is working at biological controlling problems, by making researches, investigations, clinical studies and developments of stimulators for BF.

Equipment and Supplies↗
PubMed1995

Radiogenic responses of normal tissue induced by fractionated irradiation--a simulation study. I. Acute effects.

AIM: Based on control theory, the attempt is made in this paper to construct a computer model which describes the time course of fast proliferating normal tissue after irradiation treatment. Subsequently, different clinical irradiation schemes are compared in regard to their radiogenic acute effects. MATERIAL AND METHODS: A cybernetic model of a cell renewal system consisting of stem-, transit- and functional cells has been developed and transferred into a computer model. The radiation effects are considered by characteristic cell parameters as well as by the linear-quadratic model. RESULTS: Three kinds of tissue (thick epidermis of man, thin epidermis of the mouse and jejunum of the mouse) have been irradiated in the model in accordance with different clinical irradiation schemes (standard-, super-, hyperfractionation and a single high dose per week). The simulation studies demonstrate that the acute reaction of normal tissue to hyperfractionation (3 times 1.5 Gy per day) is particularly severe. Furthermore, the radiation damage of the jejunum and of the thin epidermis of the mouse depends on the specific irradiation scheme and is only partially compensated. CONCLUSION: A comparison of the simulation results with clinical experience (and practice) demonstrates that the clinical reality can in quality be successfully represented by the model. This opens the door for connecting the side effects of irradiation to normal tissue with the corresponding tumor effectiveness (see our previous papers about irradiation of tumor spheroids.

Animals↗
PubMed1994

[Possibilities for quantitative gait analysis in evaluation of prosthesis fit].

Nowadays, the fitting of a lower-limb prosthesis is done mainly on an empirical basis. The main aim of the present study was to provide objective data and presentations to support the subjective data. With the aid of a cybernetic statement, the process of fitting a prosthesis to a human subject was developed as a self-optimizing control cycle. Using this systematic scheme, the walking trial was identified as the process element of this control cycle in which the fitting proper took place. Starting with this systematic scheme, the characteristics of defined changes to the system human-prosthesis during walking were measured with the aid of a specially configured gait analysis system. For the estimation of the characteristics of the measured walking trial, a three stage parameter system based initially only on the angle, velocity and acceleration curves at the knee joint was developed. On the basis of pattern recognition routines, the parameter system permits a very high level of identification of the measurements. The identification of poor fittings not covered by the pattern recognition system is not yet satisfactory. However, with the incorporation of additional gait parameters, it will be possible to further improve the description of the gait, enabling better recognition of disturbances in the human-prosthesis system.

Artificial Limbs↗
PubMed1993

[Misdiagnosis of psychosomatic disorders].

Considering the frequency with which the diagnosis 'psychosomatic illness' is established, it is puzzling how little attention has been paid to its differential diagnosis. The reason for this may be found not only in the difficulties with which that diagnosis is made but also in the doctor's view of the world and his or her understanding of illness in general. If the doctor only believes in what can be measured and weighed as being real, all symptoms for which no identifiable cause can be found must be considered as imaginary and 'all in the patient's head'. Most contemporary theories about the origin of psychosomatic illness are based on Freud's speculations, established at the beginning of this century. The are deeply rooted in the mechanistic, reductionistic and monocausalitic theories typical for his time. They suggested that the metamorphosis from thought-processes to somatic symptoms begin with a rather mysterious 'jump', taking place in the unconscious of the patient and thus remaining unknown to him. Today we know that all illness has a multifactorial basis and does not develop in a straight line but as a cybernetic loop. Psychosocial factors play as much a role as biological ones. Diagnosis by exclusion (no clear physical findings) or through dualistic thinking (the cause must be either psychological or physical) are, after inadequate knowledge of somatic or psychological medicine, the most common source of the erroneous diagnosis of psychosomatic illnesses. To avoid this, a psychosomatic perspective is needed, an outlook which is based on a holistic understanding of man in health and sickness.(ABSTRACT TRUNCATED AT 250 WORDS)

Attitude of Health Personnel↗
PubMed1993

[2 years results of implantation of diffractive multifocal intraocular lenses].

In an ongoing prospective study, we investigated 52 eyes of 40 patients 2 years (range: 22-26 months) after implantation of a diffractive multifocal intraocular lens (3M, type 815LE). The distance visual acuity averaged 0.48 without correction and 0.83 with best correction. The mean refraction (spherical equivalent) amounted to -1.2 D (compared to only -0.32 D 3 months postoperatively). The corrected distance acuity was > or = 1.0 in 40% and > or = 0.5 in 100% of the eyes. A near visual acuity of Nieden 1-3 was achieved in 70.3% without correction, in 75% with distance correction only, and in 100% with additional near addition. Compared to our results 3 months after multifocal lens implantation, the uncorrected distance acuity decreased and the uncorrected near acuity increased 2 years postoperatively both phenomena being attributable to the postoperative minus-shift in refraction. The other acuity values were unchanged in comparison with the 3-month results. Measured with the Ginsburg test, contrast sensitivity at low and medium spatial frequencies improved significantly compared to the 3-month results. An improvement in contrast sensitivity since the early postoperative phase was also found using the Pelli Robson contrast sensitivity chart and--in tendency--using the Regan contrast charts. Hypothetically, these findings may be traced back to a retinal or central nervous cybernetic adaptation mechanism to the implanted multifocal optic.

Aged↗