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Results for “Systems Analysis”

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At least 55 records · Page 3Linked to original sources
PubMed1976

System analysis of heart rate control in man.

The dynamic property of the heart rate response to exercise was determined and expressed in the frequency domain to establish a method of examining cardiovascular control function. The response of heart rate to a stimulus was measured at 5-s intervals in nine healthy young volunteers. The stimulus consisted of several runs of two-step exercise practiced in semirandom sequence for 19 min. The weight function of the system was estimated from autocorrelation function of the input signal and cross-correlation function between the input and output signals. The weight function was transformed into a transfer function and its Bode plot diagram was drawn. From the diagram, four dynamic parameters were determined. These parameters are as follows: K is a constant showing the theoretical steady-state increment of heart rate, and T1, T2, T3 are time constants. The values obtained in the present experiment with the healthy young males were: K 46.0 +/- 14.6 beats, T1, 2.12 +/- 0.44, T2, 1.12 +/- 0.16, and T3 0.70 +/- 0.07 min.

Adult↗
PubMed1977

[Separation and fluorimetric determination of adrenaline and noradrenaline. Combination of a high-pressure liquid chromatograph with an automatic analysis system].

The possibilities for a high-pressure liquid chromatographic analysis combined with automatic fluorimetric detection of the catecholamines adrenaline and noradrenaline are described. The optimal conditions are given for a fast separation by ion exchange and reversed-phase chromatography, and for the sensitive fluorimetric determination of adrenaline by the trihydroxyindole technique when a high excess of noradrenaline is present.

Autoanalysis↗
PubMed1979

Application of linear system analysis to the horizontal vestibulo-ocular reflex of the alert rhesus monkey using pseudorandom binary sequence and single frequency sinusoidal stimulation.

Horizontal eye movements of the alert rhesus monkey resulting from both pseudorandom binary sequence (PRBS) and single frequency sinusoidal rotational stimulation were analyzed using a PDP 11/40 computer in order to generate gain, phase, and coherence estimates at discrete frequencies between 0.008 and 1.28 Hz. A computer simulation of vestibular induced eye movements was used to validate our analysis procedures and to determine the effects of digital noise. Frequency domain transfer functions derived from gain and phase estimates revealed that the responses to PRBS stimulation and to single frequency sinusoids were not appreciably different. PRBS testing was accomplished in approximately one third the time required for sinusoidal testing and yielded highly reproducible data. We conclude that PRBS stimulation is a reliable and efficient method for assessing linear system parameters of the horizontal vestibulo-ocular reflex. PRBS testing may be particularly advantageous in studies of vestibulo-oculomotor plasticity in which rapid assessment of alterations in system dynamics is essential.

Animals↗
PubMed1978

Characterization of increased synthesis of acute phase proteins from plasma concentration measurements: a system analysis of the ideal situation with use of computer simulation.

A method for characterizing the secretion of acute phase proteins in vivo from serial plasma concentration measurements is presented. By using a simple two-compartment model it was found that descriptive parameters could be derived from the time course of the increased plasma concentration of the protein. It was assumed that the secretion of an acute phase protein is adequately described by: (i) the start time t1; (ii) the end time t2; (iii) the magnitude of increased flux of the protein from synthetic sites to the extracellular space, described by a turnover index, S. The influence of sampling interval and analytical precision on the reliability of the estimated parameter values was investigated in the ideal situation by using computer simulation. It was found that informative estimates of the secretion rate of an acute phase protein could be obtained provided a fairly high analytical precision with a coefficient of variation less than or equal to 0.01 and using a sampling interval between 0.5--2 h.

Adrenocorticotropic Hormone↗
PubMed1977

A systems analysis of the impact of physician extenders on medical cost and manpower requirements.

This paper presents a descriptive narrative of a mathematical manpower model and the results of an analysis of the effect physician extenders have on medical costs and manpower requirements. The model is extensively developed, through the use of a new medical classification system in the area of delegation of specific task areas and patient visits to physician extenders. Additionally the models incorporate a complete cost structure for a group practice. Field trials in seven HMOs indicate that the models accurately represent the actual system and can be used effectively as planning aids. Results are presented that analyze the use of physician extenders from the following viewpoints: minimum cost solution for adult medicine, pediatrics and obstetrics/gynecology (OB/GYN); maximum physician extender use; effect of physician extender salary on minimum cost utilization; level of independence exercised; size of clinic and regional manpower planning; and a case study of HMO planning. The type of results presented include cost analysis, manpower analysis, and the types of patient visits best delegated to physician extenders (PE).

Adult↗
PubMed1978

The oscillating peroxidase-oxidase reaction in an open system. Analysis of the reaction mechanism.

1. The oscillations in the peroxidase-oxidase reaction in an open system with NADH as the hydrogen donor are caused by the reaction starting and stopping at critical concentrations of the substrates O2 and NADH. The existence of such critical concentrations is typical of branched chain reactions. 2. The critical concentrations of O2 and NADH that determine the initiation of the reaction are mutually dependent. 3. The branching reactions that determine these critical concentrations involve compounds I and II. 4. Superoxide may be involved in the branching reactions by reacting with NADH and ferriperoxidase. At pH 5.1 the rate constant for the latter reaction is determined as 1.5 . 10(5) M-1 . s-1, whereas for the former reaction only an upper limit for the rate constant of 3.5 . 10(4) M-1 . s-1 could be estimated. These relatively low rate constants suggest that alternative branching reactions may also be involved.

Kinetics↗
PubMed1979

Implementing a computer-based electro-oculographic analysis system.

Electro-oculographic recordings of caloric-induced nystagmus were conducted in a number of normal and disordered subjects. On the basis of the results, implementation of a clinical measuring system is considered; this is based on the interbeat interval, selected in view of its favourable sensitivity and stability. Two stages of processing are involved; first, the determination of the interbeat intervals, second the analysis. The first stage has been implemented off-line on a general purpose computer and also, in on-line mode, by special purpose electronics. The second stage requires computer analysis. We have used the rank magnitude sequences of interbeat intervals as the basis of the analysis.

Adult↗
PubMed1978

An interactive data management and analysis system for clinical investigators.

An interactive minicomputer-based system has been developed that enables the clinical research investigator to personally explore and analyze his research data and, as a consequence of these explorations, to acquire more information. This system, which does not require extensive training or computer programming, enables the investigator to describe his data interactively in his own terms, enter data values while having them checked for validity, store time-oriented patient data in a carefully controlled on-line data base, retrieve data by patient, variable, and time, create subsets of patients with common characteristics, perform statistical analyses, and produce tables and graphs. It also permits data to be transferred to and from other computers. The system is well accepted and is being used by a variety of medical specialists at the three clinical research centers where it is operational. Reported benefits include less elapsed and nonproductive time, more thorough analysis of more data, greater and earlier insight into the meaning of research data, and increased publishable results.

Computers↗
PubMed1976

[System analysis of the multi-oscillatory functional order in the circadian and ultradian frequency range and its monitoring value for load effects, exemplified by a varying light-dark regimen in the intensive rearing of sheep].

As part of the experiments to influence the annual rhythmicity of sexual reproduction, various artificial light-dark regimens were tested for their systemic effects. From the polygraphic registration of several functions, such as food ingestion, rumination, movement, cardiac and respiratory rhythm were obtained biorhythmometric system-analytic parameters of the multi-oscillatory functional order. Under well-balanced light-dark conditions (LD 13.5:10.5), a high intra- and interparametric degree of functional coupling of 80% is obtained, while under extreme conditions (LD 22:2) this value amounts to 39%, which is equivalent to a disorganized time structure and disturbed neuro-vegetative multi-oscillatory functional order. The significance of these or analogously contrived studies on environmental problems under human social conditions is pointed out.

Animals↗
PubMed1979

A versatile physiological data analysis system using an Intel 8080 microprocessor.

A microprocessor based physiological data processor has been realised. The system controls the data flow from physiological experiments and performs on-line mean and variance calculations with an output in graphical form. The analyser accepts one data point every 0.5 ms and has a capacity of 128 records each containing 800 data points. Post stimulus histogram and interval histogram analysis programs have also been written and implemented.

Computers↗