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Biomedical subjects

J Peil

Publications and source records attributed to J Peil.

At least 73 records · Page 4Linked to original sources
PubMed1977

[Biomathematical procedure for quantitative oscillation analysis].

In the first part of the paper oscillating phenomena are discussed which one can observe on different levels in anorganic and organic systems. This discussion will be performed from physical, biorhythmic, control, and general system theoretical point of view. Especially biorhythmic phenomena are taken into account by the stated classification scheme. In the second part four numerical procedures for biomathematical analysis of biorhythmic oscillations are explained. The analysis is understood as determination of the number of harmonic suboscillations which set up the whole process, and calculating the values of frequency, amplitude, and phase of these suboscillations. To perform the mentioned four numerical procedures computer programs are available which are written in ALGOL.

Animals↗
PubMed1977

[Biostatical and biomathematical evaluation of morphometric data--illustrated on the example of the relationship between axon diameter and thickness of the myelin sheat. I. 1st data evaluation step: empiric regression].

Application of the biostatistical procedure of empirical regression on a first data processing stage is demonstrated by examples from morphometrical research concerning the connection between axon caliber and thickness of myelin sheat of nerve fibers. This mathematical kind of describing connections between continuous random variables offers advantages which are discussed under the aspects of information compressing, of automatic data processing, and of providing objective basis for the process of data handling and decision making of further evaluations.

Animals↗
PubMed1977

[Quantitative analytical registration of body-length growth in man].

Measured values concerning the body hight growth process of male human beings, and reaching from praenatal to adult state are taken from anthropometric literature. After a discussion of the mathematical tools for description (differential equation, analytical function), and of the problems connected with subdividing the whole growth period in subsequent periods the results of numerical adjustments of growth functions to measured courses of these subperiods are presented. The obtained goodness of fit is excellent so that for the purpose of formal quantitative description of the whole growth process a set of mathematical functions is available. Each of these expressions is effective only in the time interval of the corresponding growth subperiod. This set of mathematical functions will provide a objective basis for further investigations, especially for comparisons between populations, and for a mathematical analysis of acceleration phenomena in development. In the last part of the paper a mathematical-phenomenological model for the growth process is sketched. The main features of this model consist in a subdividing of the whole process in growth parts with a biological meaning, and in a mathematical description of these parts which are mutually independent but superposing one with another. Therefore the number of growth parts and also of mathematical terms are determined by biological (theoretical or phenomenological) arguments. Now each of these calculated function terms is valid for the whole time intervals in which the body hight growth process performs. The entirety of all these terms gives a seamless steady description of the changes of the growth variable in time.

Adolescent↗
PubMed1977

[Numerical procedure for the decomposition of biorhythmic processes into harmonic oscillating components].

A numerical procedure for decomposition of time series into inherent periodic nonstochastic components in form of harmonic oscillations will be explained. It is supposed that the rhythmic process is built up by these harmonic oscillating components and by a stochastic component. The procedure is a combination of Harmonic Analyses for intervals with different numbers of measured values with a significance test elaborated by R.A. Fisher for the greatest component in the spectrum. The parameter values of the harmonic oscillating components are elevated by the procedure, and the partial oscillations will be successively eliminated from the time series. The revelant application of Harmonic Analysis in any form on the one hand and of power spectra on the other will be discussed. Hints for an efficient combination of several numerical procedures are given for a decomposition of biorhythmic processes in harmonic oscillating components, and for the statistical significance of the decomposition.

Animals↗
PubMed1977

[Biomathematical evaluation of morphometric data--presented illustrated on the example of the relationship between axon diameter and thickness of the myelin sheath. II. Nonlinear approximations].

After the process of measuring morphometrical characteristics performing empirical regressions as a first stage of data processing is treated in the foregoing part I of the paper. The morphometrical datas have to characterize a functional relationship between two variables X and Y, in the cases in question this is the connection between axon caliber and thickness of myelin sheat of nerve fibres. Based on the results of empirical regression the second data processing stage consists in performing nonlinear approximations of the measured courses by a suitable chosen mathematical function. For this purpose the generalized logistic function is chosen for a quantitative and qualitative description of the connection between axon caliber and myelin sheat thickness. The numerical procedure and the various possibilities of the ALGOL-program for performing the approximation task are sketched. The results of this second data processing stage are discussed under the aspects of information compressing, of automatic data processing, and of providing an objective basis for the further process of evaluation and interpretation.

Anthropometry↗
PubMed1976

[An ALGOL program for correlation and concordance analysis].

An ALGOL-program ready for use for correlation analysis and rank correlation methods is presented with a description of the program and explanations on choice of program parameters and concerning the input data arrangement. For all pair combinations of variables one can calculate BRAVAIS correlation coefficient, the Z-transformation and a test statistic, the ranks will be determined, for all combinations the SPEARMANS rank correlation coefficient can be evaluated, and a analysis of concordance can be performed. Every of these statistical procedures is explained. The general biometric task in connection with morphometric research leading to an analysis of concordance resp. correlation is briefly discussed.

Biology↗
PubMed1976

[Quantitative description of growth processes in man as a basis for the objective comparison of sex-specific data for various body measurements].

To compare growth processes of feminine human beings with such one of masculine we have taken as realizations of the growth characteristic the morphological height of face (distance between nasion and gnathion), length of nose (distance between nasion and subnasale) and body length of two spatially and temporally different populations. Measured values of these characteristics for different ages of individuals provide the basis for mathematical evaluation. The parameters of the following three types of mathematical functions were adjusted to the measured time course of the growth characteristics: Gompertz' function, inverse tangent and the generalized logistic growth function. The principal possibilities are explained which a mathematical expression can offer for qualitative and quantitative description of dynamical processes. The results of fitting the 3 competitive function types to the course of the measured values are given and several quantitative conclusions are demonstrated arising from comparisons of corresponding growth processes of feminine and masculine human beings.

Anthropometry↗
PubMed1975

[(An algorithm for determining values of parameters of the Gompertz growth function)].

In the literature some attempts were made to analyse and to construct models for biological growth processes and to describe the quantitative aspects of a growth characteristic's changes in time using the Gompertz' function y=aexp(-exp(b--ct)). In this paper differential equations are derived having the Gompertz' function as solution. The goodness of fit after adjusting a chosen analytical expression to the courses of measured values is able to give hints at the reliability of that expression as a true model. This possibility of verification was hardly practiced in past because of lacking in proper numerical procedures for performing the nonlinear regression. An ALGOL program for iterative adjusting the parameters of the GOMPERTZ' function (with or without a constant term) to measured values is given in an appendix of the present paper. Starting values for the nonlinear parameters b and c will be evaluated by Internal Least Squares using one of the derived differential equations. For this algorithm an ALGOL program is given in the appendix too. The growth of human embryo serves as an example to demonstrate the numerical procedures and related programs for evaluating the starting values of the parameters and for their iterative improvement until reaching a minimum for the remainding variance between calculated and measured courses.

Computers↗