A mathematical model of the dose-effect relationship of levodopa, one of the most common drugs in the symptomatic therapy of Parkinson's disease, is derived with the aid of a visual tracking-based method which all...
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A mathematical model of the dose-effect relationship of levodopa, one of the most common drugs in the symptomatic therapy of Parkinson's disease, is derived with the aid of a visual tracking-based method which allows the measurement of some Parkinsonian symptoms quantitatively and objectively. This third order non-linear model is used to optimize the dosage regimen for each patient individually with respect to an objective function which includes the symptoms dynamically and the total amount of levodopa which is to be administered. Encouraging clinical results of this approach to therapy optimization are presented. The advantages and drawbacks of this approach are discussed and further research directions are indicated.
A finite state model referenced control method for hybrid orthosis (HO) is introduced. A specific application of a finite state control system for crutch assisted reciprocal stepping using a novel HO is described. Thi...
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A finite state model referenced control method for hybrid orthosis (HO) is introduced. A specific application of a finite state control system for crutch assisted reciprocal stepping using a novel HO is described. This system was based on an instrumented supracondlylar knee ankle foot mechanical brace. The HO system has been used, in the laboratory, by a small number of subjects with spinal cord injuries. The HO has enabled these patients to remain upright for extended periods of time by avoiding muscle fatigue due to overstimulation of the extensors of the legs.
Administration of gaseous anesthesia using a closed circuit is cheaper and ecologically safer than the traditional semi-closed circuit. However, gas concentrations are more difficult to control. This paper proposes an...
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Administration of gaseous anesthesia using a closed circuit is cheaper and ecologically safer than the traditional semi-closed circuit. However, gas concentrations are more difficult to control. This paper proposes an adaptive bilinear controller for the automatic control of a closed circuit anesthesia system. Alveolar anesthetic gas concentration, alveolar oxygen concentration and circuit volume are controlled using a liquid anesthetic (Halothane), oxygen and nitrous oxide. Oxygen consumption, nitrous oxide uptake and Halothane uptake are estimated by a least-squares parameter estimator. Derivation of the model used, results from simulations and results from preliminary tests on dogs are presented.
Purpose of this paper was to obtain a low-order identification-oriented model of the systemic vascular bed, with a future view to beat-to-beat monitoring and control applications. To this aim reduced models of the sys...
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Purpose of this paper was to obtain a low-order identification-oriented model of the systemic vascular bed, with a future view to beat-to-beat monitoring and control applications. To this aim reduced models of the systemic bed were compared on the basis of Akaike Information Criterion (AIC), combined with parameter estimation accuracy and physical interpretability. These criteria have been applied to systemic pressure data generated by a cardiovascular simulator, implemented using a Computer Aided Design of control System (CADCS) package. The results obtained show that only simple models can be accurately estimated, when signals with a limited frequency spectrum such as the physiological ones are used.
A hydromechanical circulatory model consisting of a direct drive piston pump, driving mechanism and circulating tubings has been constracted for the aim of helping in cardiovascular studies. This paper describes the p...
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A hydromechanical circulatory model consisting of a direct drive piston pump, driving mechanism and circulating tubings has been constracted for the aim of helping in cardiovascular studies. This paper describes the pump control mechanism in such a circulatory model. The pump is driven by a microcomputer controlled stepper motor to obtain a desirable pulsatile flow-rate contour in the proximal aorta of the model. Because stepping linearity of the motor is high enough, no feedback is required in the model. Since a direct drive piston pump is used in the model, the pump can be taken as a volume source, and the displacement versus time contour of the piston of the pump defines the shape of the flow-rate contour. Thus, the desired pulsatile flow-rate contour is obtained by controlling the movement of the piston by means of a microcomputer.
The authors have developed a theoretical model for surface charge evolution in specific in vivo systems, based upon ion migration occuring at the interface between tears and ocular therapeutic membranes. Gibbs-Donnan ...
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The authors have developed a theoretical model for surface charge evolution in specific in vivo systems, based upon ion migration occuring at the interface between tears and ocular therapeutic membranes. Gibbs-Donnan Theory allows the prediction of net ion movement and calculation of trans-membrane potential differences, interpretable as surface charge. Two generalized algebraic equations are presented which calculate potential differences across membranes under specific parameters of tear ionic strength, ionic strength of membrane-impregnated compounds, and number of elapsed blinks. Computer-generated data for a model (Na-fluorescein-impregnated membrane) reveals that a plateau surface charge is attained after 5-6 blinks for any loading concentration less than physiologic (140 mM).
The pattern of the activatory inputs that control the spontaneous in vitro contraction of the rat uterine horn is investigated. A mathematical model is used in this study. The model gives the time course of intralumin...
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The pattern of the activatory inputs that control the spontaneous in vitro contraction of the rat uterine horn is investigated. A mathematical model is used in this study. The model gives the time course of intraluminal pressure, longitudinal force, and wall morphology, when the mechanical parameters and the activatory inputs of the two muscular layers of the wall are assigned. The mechanical parameters of the smooth muscle tissue are deduced from the measured force-length and the force-velocity data of the myometrial tissue. The possibility of determining uniquely, from the experimental data of pressure and force, the parameters that characterize the model input is investigated. The results of the estimation of these parameters from a set of experimental data is presented.
For drugs whose margin of safety is narrow, precise dosage regimes are important, coupled with useful pharmacokinetic models, good serum level monitoring, and good procedures to analyze the data and reconstruct the pa...
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For drugs whose margin of safety is narrow, precise dosage regimes are important, coupled with useful pharmacokinetic models, good serum level monitoring, and good procedures to analyze the data and reconstruct the past model behavior for careful comparison with the patient's clinical behavior over the entire past therapeutic history. In this way, truly individualized therapeutic goals (usually serum levels) can be chosen, and intelligent methods used to compute the new dosage regimen, after which the entire scenario recycles again. This report will review both pharmacokinetic and nonpharmacokinetic factors which play significant roles in this process.
In this paper some aspects of unidentifiable compartmental systems are considered. In particular a broad class of unidentifiable models is investigated, and the fundamental role of the number of excretions in unidenti...
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In this paper some aspects of unidentifiable compartmental systems are considered. In particular a broad class of unidentifiable models is investigated, and the fundamental role of the number of excretions in unidentifiability is stressed. The class considered here is that of unidentifiable systems that become identifiable if the number of excretions is suitably reduced. The peculiarity of this class enables us to construct parameter bounds by exploiting the properties of an associated system with no excretions. The relations employed are those stated by L. D'Angio which express the transfer constant by means of cycles and loops.
This paper deals with the identification of the model represented by a diabetic patient in order to control the fluctuation of the glyceamia rate in relation with the flow of injected of insulin and glucose. In the id...
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This paper deals with the identification of the model represented by a diabetic patient in order to control the fluctuation of the glyceamia rate in relation with the flow of injected of insulin and glucose. In the identification step we first look for a numerical model which represents a relation between the inputs: the glucose and the insulin and the output: the glyceamia blood rate. The model is chosen to be a multi-input single output ARMA model which is easy to handle and fits to a many identification algorithms. The structure determination is based upon the evaluation of various norm such as the estimation error variance norm, the total correlation coefficient and the multiple correlation coefficients. The combination of these various norms and the parameter estimates convergence enables the selection of the model, which has a low residual error and low parameter estimation error.
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