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doi: 10.1177/003754977502500403pmid: N/A
Biological cells, healthy or malignant, perform in most respects similar activities:(a) They proliferate by growing and maturing and, after reaching a certain level of maturation, they divide into daughter cells.(b) They differentiate by changing irreversibly to new types of cells.(c) They compete by participating in ecological struggles with other cells that share the same ecological niche. Through the principle of com petitive exclusion, slower-dividing cells may be eradicated from a mixture of cells.This paper presents a mathematical model of the above processes and describes a computer simulation which includes the effects of chemotherapy or radiation therapy on a system consisting of healthy and malig nant cells. The simulation develops qualitatively and quantitively the kinetic properties during treat ment of the mixture of the two types of cells in tissues and shows how the favorable protocols for treatment can be found. Such knowledge can, among other things, be used to devise good strategies for the treatment of cancer by radiation or chemotherapy and to increase the efficiency of research in their use.The example described is a simplified one in which only two types of cells are considered, but the simu lation model can be applied to much more complex and realistic situations.
doi: 10.1177/003754977502500405pmid: N/A
MINISIM is a general-purpose interactive digital simulation program which is written in FORTRAN and is suitable for both interactive and batch use. The program currently utilizes a fixed-step 4th-order Runge-Kutta integration algorithm. The program has proved to be suitable as a replacement for an analog computer in both teaching and research activities. OPTSIM is an extension of MINISIM that permits optimizing simulated systems automatically while making use of the MINISIM integration routines. The same problem-description subroutine (SUBROUTINE EQUATN) may be used with either MINISIM or OPTSIM.Detailed examples are given of the simulation and optimization of a control system and also of the solution of a two-point boundary-value optimization problem.
doi: 10.1177/003754977502500409pmid: N/A
This paper reports on the exploration and use of a sim ulation of the human menstrual cycle published in the July 1972 (Vol. 35, No. 1) issue of The Journal of Clinical Endo crinology & Metabolism by R. J. Bogumil, M. Ferin, J. Rootenberg, L. Speroff, and R. L. Vande Wiele. The simula tion appears to duplicate well the cyclic hormonal fluc tuations of a normally ovulating woman. But when asked to duplicate the results of giving a woman exogenous es tradiol, the simulation produces results which are in dis agreement with other published research data. Extrapo lation from the reported simulation beyond the normal undisturbed cycle produced results that do not agree with published physiological data, suggesting that the model needs further refinement. However, simulations run using the model indicate the possibility of stopping the menstrual cycle by a properly timed application of the hor mone estradiol (E2).
doi: 10.1177/003754977502500406pmid: N/A
This paper presents a modification to the functional simulation technique which allows the user to perform simulations of systems at increasing levels of detail by making only minimal changes in the description of the system. Functional simulation is easy to imple ment because the functional simulation model defines all the system control parameters necessary for simu lation. The investigator designing the simulation need not be concerned with implied parameters. To extend the technique of functional simulation to multilevel functional simulation (MLFS) requires only a small amount of additional program, but it provides a significant increase in capability.
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