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  • 1
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    Bulletin of mathematical biology 34 (1972), S. i 
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    Bulletin of mathematical biology 34 (1972), S. 53-63 
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    Notes: Abstract A stochastic model is developed for a compartment with a single time-dependent input, and generalized to include inputs from several sources. With the number of particles of a given molecular species in the compartment as the random variable, the mean, variance and third central moment of this variable are calculated from its generating function, and compared with previous results. The behavior of the calculated moments is discussed, and the possibility of applying the model to chemical and biological systems is considered.
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  • 3
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    Bulletin of mathematical biology 34 (1972), S. 439-441 
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    Notes: Abstract It is shown that from the definition of organismic sets (Rashevsky,Organismic Sets. Some Reflections on the Nature of Life and Society, Holland, Michigan, Mathematical Biology, Inc. and Grosse Pointe, Michigan, J. M. Richards Laboratory) a complete sensory deprivation of an organismic set of ordern=2 should result in malfunctioning of the set. A generalization to higher order sets is suggested.
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    Bulletin of mathematical biology 34 (1972), S. 431-438 
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    Notes: Abstract Optimality in branching structure of the vascular tree was studied. Analysis on its physiological roles as the duct system for blood supply to the capillaries predicted that the vascular tree should be constructed with minimum volume under restriction of determinant pressure, flow and location at the origin and the terminals. Mathematical derivations of this conditional extremum problem yielded some equations expressing the relations between the radii of the branches and their branching angles, which provided numerical solutions for branching points of bi- and poli-terminal minimum volume trees. Comparison of the peritoneal vascular tree in a dog with the minimum volume one computed under the same restrictive conditions showed good agreement in their branching structure.
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    Bulletin of mathematical biology 34 (1972), S. 443-456 
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    Notes: Abstract In order to determine the kinetics of passage of a substance through an organ containing a tangle of vessels, we study the response of a tube to various inflows (perfusion, brief injection, ...). The introduction of the catabolic terms and of the spatial dependence between bulk concentration and surface concentration allows one to account for the difference of arteriovenous concentrations observed experimentally for many metabolites. The relationships between the physico-chemical parameters of the organ and the operational parameters of the model demonstrate the importance of the transit time through the considered vessels. If one considers the different pathways as independent, the introduction of the transit time distribution for an inert substance enables one to compute the response of the organ analytically or by recurrence, using convolution. The parameters of the model can be obtained by the moments method.
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    Bulletin of mathematical biology 34 (1972), S. 457-466 
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    Notes: Abstract The solution of the diffusion equation in the gas phase of the human lung is very difficult because of the structure of the bronchial tree. It is shown by means of physical arguments, how one can reduce the diffusion equation to a simple one-dimensional form. The solution is then obtained by a stochastic simulation, which is easily realized on a digital computer.
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    Bulletin of mathematical biology 34 (1972), S. 467-481 
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    Notes: Abstract A new mathematical model of the oscillatory behavior of the respiratory center has been developed based upon published records of neuronal activity during respiration in the pons and medulla. In contrast with a previous model, four, rather than two, networks are assumed to interact in the respiratory center so as to produce the respiratory oscillation. A mathematical description of this interaction, in the form of a set of four first-order, nonlinear, coupled differential equations, is derived; the behavior of the solutions of this system is studied qualitatively, and expressions for the durations of the inspiratory and expiratory phases are obtained in terms of some parameters. It is found that central and chemical influences drive the medullar neurons to a position somewhere between saturation and full cutoff, and the pontine neurons deeply into cutoff. The control of the duration of the different phases by these chemical and central means is discussed. In order to effect a decrease in the magnitude of the various times, the neurons have to be driven towards operating points of higher central facilitation.
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    Bulletin of mathematical biology 34 (1972), S. 483-502 
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    Notes: Abstract In vivo control of calcium is analysed under the assumption that hormonal influences via plasma levels of parathormone and calcitonin are of prime (but not absolutely dominating) importance. A brief review concerning the physiological significance of body calcium and the mode of action of these two hormones is presented as an introduction to the basic philosophy of the study. A theoretical quasi-linear lumped-parameter model is developed to describe variations in ionic calcium, parathormone and calcitonin plasma concentrations to specific input stimuli. Formal evaluation of the system response requires the determination of ten constants, together with quantitation of ingested calcium entry into the plasma compartment which isindependent of hormonal influences. Values for various parameters are deduced from published data and experimental procedures are outlined to facilitate determination of the remaining unknowns. It is suggested that the proposed model should prove useful for investigations concerning general hormonal actions on calcium homeostatic mechanisms in both normal and diseased states, with particular reference to calcitonin.
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  • 9
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    Bulletin of mathematical biology 34 (1972), S. 521-532 
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    Notes: Abstract Ann species predator-prey chain is analyzed to determine what oscillations occur in population sizes. It is found that only the populations of the first and second species in the chain must necessarily oscillate around the point of equilibrium if they do not come to equilibrium. The other species may or may not oscillate.
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  • 10
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    Notes: Abstract Sangren and Sheppard developed a mathematical model for first-order processes taking place in the regional circulation, applicable—for example—to tracer studies of potassium transport. It permits calculation of specific activity at any point along a “tube of flow” or in the cuff of tissue surrounding it as a function of time following a spike injection of tracer. In efforts to relate to the exchange a rate curves obtained within vivo counters pointed at the region of interest, we developed a compartment-system model of the process. In investigating the properties of the Sangren and Sheppard model integrated over an entire circulatory bed, as thein vivo counter would see it, we found that when the distribution of transit times of the “tubes of flow” can be approximated by an exponential sum, the solution reduces to that of the compartment system model. This results in an important simplification in the calculation, and insight into the assumptions underlying the two different models. A curve-fitting computer program for the compartment model has been written and applied to double-isotope studies of potassium transport in the hind leg of the dog.
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    Bulletin of mathematical biology 34 (1972), S. 547-558 
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    Notes: Abstract Two chemicals,A andB, are allowed to diffuse together and a reaction described by $$A + B\mathop \rightleftharpoons \limits_{K_{ - 1} }^{K_1 } C$$ is allowed to proceed. This system is described mathematically by a system of partial differential equations. A numerical procedure is presented to find the rate constants ofK 1 andK −1. A systematic analysis of the effects of errors is also presented.
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  • 12
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    Bulletin of mathematical biology 34 (1972), S. 533-546 
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    Notes: Abstract Equations are developed to describe the energy expenditure of the human heart. As well as the external potential and kinetic energy terms, general consideration is given to other possible avenues of energy consumption. Emphasis is placed upon using mathematical variables which are readily available for experimental verification. The errors involved in assuming that mean values for the physiological parameters give reasonable estimations for the external mechanical performance are examined, and a theoretical estimation for the discrepancy in the kinetic component is presented. Logical extension of the mathematical derivation leads to a determination of cardiac external mechanical efficiency and clearly demonstrates the significance of the ventricular pressure-volume loop in this context. Finally, experimental procedures are suggested to clarify further some of the conclusions reached through the theoretical analysis.
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    Bulletin of mathematical biology 34 (1972), S. 559-563 
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    Notes: Abstract The question is discussed as to the reason why some animal societies, such as bees or ants, are sexually differentiated, that is, onlysome of its members are exhibiting reproducing activities. It is indicated that human society may be on its way to such a sexual differentiation which may eventually come.
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  • 14
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    Bulletin of mathematical biology 34 (1972), S. 565-565 
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  • 15
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    Bulletin of mathematical biology 34 (1972), S. 567-567 
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    Bulletin of mathematical biology 34 (1972), S. 173-204 
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    Notes: Abstract As a further attempt to determine the stresses and strains of the individual myocardial fibers, the heart muscle is considered as an orthotropic material. A theory is presented which leads to the expression of the equilibrium conditions for the left ventricle in the form of three simultaneous differential equations. Solution of these equations would give the changes in shape of the left ventricle throughout the cardiac cycle, and, in addition, the stresses and strains of the individual myocardial fibers. It is pointed out, however, that meaningful solutions of the equations cannot be obtained at the present time because of difficulties in experimental determination of certain parameters.
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    Bulletin of mathematical biology 34 (1972), S. 213-222 
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    Notes: Abstract This paper compares two previously published neural models for epilepsies (Bull. Math. Biophysics,33, 539–553, 1971;34, 71–78, 1972). The second model is developed in more detail and an attempt is made to bring it more in line with established neurological findings. The question of classification of some epilepsies is briefly discussed.
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    Bulletin of mathematical biology 34 (1972), S. 223-230 
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    Notes: Abstract A formal mathematical model is proposed for a spontaneously repetitively firing neuron. It is based on the assumption that an excitatory and inhibitory substance, possibly different from those involved in synaptic transmissions, is formed in the soma of everynormal neuron. Furthermore, the decay of the substances is ascribed to their combination with some other substances, present in healthy individuals. A generalized two factor system of differential equations is used. It is shown that when the normally present substances are absent, possibly due to genetic defects so that the decay constants become zero, the equations lead to undamped sinusoidal solutions of the difference between excitatory and inhibitory factors, thus producing a trulyspontaneous repetitive discharge, in the absence of external currents or other stimulation. It is suggested that convulsants may act by destroying the substances present in healthy individuals. It is further suggested that by administering to epileptics those substances, which are present in normal healthy persons, perhaps by using brain extracts fromhealthy higher animals which sometimes suffer from epilepsy, an actual cure rather than symptomatic treatment by anticonvulsants may be obtained.
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    Bulletin of mathematical biology 34 (1972), S. 277-291 
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    Notes: Abstract The general kinetic behavior of a multicompartment system is shown to depend upon certain general structural features, including its connectivity, whether it is open, and whether it contains cyclic pathways. Structural influences are clarified by putting the system matrix in a certain form. For systems not strongly connected, a distinction is drawn between partially and completely open systems. Necessary and sufficient conditions are given for non-singularity of the system matrix and for asymptotic stability of the system. Sufficient conditions are given for non-overshooting and monotonic transitions. A system is demonstrated whose solution may contain a prolonged series of damped oscillations; but the oscillations are very slow and small; and it seems unlikely that oscillations could be detected experimentally in any biological system.
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    Bulletin of mathematical biology 34 (1972), S. 243-275 
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    Notes: Abstract It is shown how the fundamental laws of chemical kinetics for either open or closed systems with an arbitrarily large number of reactants can be represented as a system of Riccati-like differential equations. Through the use of a concise tensor notation, it is shown when and how the differential system is exactly reducible to linear form, a reduction without approximation that parallels the well-known similar reduction of a single simle Riccati equation. An example is worked out to show how open kinetics can lead to oscillatory chemical concentrations of the Change-Higgins type. The biologically central problem of great chemical speciation is discussed from the viewpoint of Gibbs ensemble theory within the linearized kinetics and, approximately, within the starting nonlinear kinetics where it is shown roughly how to estimate, from an overall temperature-like parameter characterizing the whole system, mean chemical levels and mean frequencies of oscillation, and where a gross oscillation of the total mass is estimated in terms of an anharmonic oscillator whose general structure is fixed from the structure of the chemical kinetic laws.
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    Bulletin of mathematical biology 34 (1972), S. 293-296 
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    Notes: Abstract A closed chain of compartments in which there is unidirectional transport between adjacent members can exhibit damped oscillations. For a system ofn equivalent compartments, the value ofn which gives the greatest difference between the first maximum and first minimum isn=11, the difference being 1.57%. The greatest difference between the first maximum value and the steady state value is 4% and is obtained whenn=25. The results are illustrated graphically forn equal to 5, 10, 25 and 100.
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    Bulletin of mathematical biology 34 (1972), S. 297-304 
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    Notes: Abstract This paper is a concrete approach to the problem of the number of the sexes. We try to imagine—on the example of three sexes—the mechanisms which would have to accompany a reproduction with several sexes. We have limited our study to the monohybridism, dihybridism and determinism of the sex.
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    Bulletin of mathematical biology 34 (1972), S. 325-335 
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    Notes: Abstract An analysis of the effect of cilia on fluid transport in tubules is presented. The applicability of the results for the flow rates observed in the ductus efferentes of the male tract is discussed.
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    Bulletin of mathematical biology 34 (1972), S. 305-324 
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    Notes: Abstract The dipole models for steady-state currents in excitable membranes of Arndt, Bond and Roper and of Hamel and Zimmerman are compared by fitting the equations to the data of Gilbert and Ehrenstein. The more complex Hammel and Zimmerman model does not fit the data as well as does the simpler Arndt, Bond and Reper model. When fitting the data, the Hammel and Zimmerman current equation reduces to the Arndt, Bond and Roper current equation because of the values assumed by the parameters. An interpretation is given for the parameter values obtained with the Arndt, Bond and Roper model.
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    Bulletin of mathematical biology 34 (1972), S. 337-341 
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    Notes: Abstract It is shown that, under rather general conditions, it is possible to formally decompose the dynamics of ann-dimensional dynamical system into a number of non-interacting subsystems. It is shown that these decompositions are in general not simply related to the kinds of observational procedures in terms of which the original state variables of the system are defined. Some consequences of this construction for reductionism in biology are discussed.
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    Bulletin of mathematical biology 34 (1972), S. 343-353 
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    Notes: Abstract For a certain class of physical machines, termed “structure-determined,” the problem of self-reproduction can be reduced to the problem of serial message reproduction. Serial message reproduction however presupposes a sort of “open system” constraint. This leads to the principle of pseudo, or exogenously standardized, respectively, self-reproduction. It seems to be consistent with both chemical and biological self-reproduction. It thus may reflect a general principle of biological design. The proposed principle is a physico chemical analog to Robert Rosen's abstract relational self-reproduction constraint.
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    Bulletin of mathematical biology 34 (1972), S. 355-377 
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    Notes: Abstract Equations are derived describing potentials due to an active muscle fiber in an infinite medium in terms of two surface integrals—one of the propagated action potential and the other of the membrane current density, both integrals being taken over the surface of the muscle. These equations are incorporated into an equivalent cardiac current generator in which the left ventricle (i.e. the current source) is represented by a three-dimensional wedge and the thorax (i.e. the volume conductor), by a homogeneous circular cylinder. Since this current generator expresses the body surface potentials in terms of the membrane current density and the membrane potential at any point on the surface of the electrically active muscle fiber, the calculated ECG can be correlated with theactual sources within the heart. This equivalent cardiac generator possesses many of the physical and physiological properties of cardiac muscle. The equations were evaluated numerically on a digital computer. The results indicate that equivalent cardiac current generators of this type can yield clinically significant results and that further research is necessary to investigate their properties fully.
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    Bulletin of mathematical biology 34 (1972), S. 413-418 
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    Notes: Abstract Analytical solutions are presented for transient heat conduction in biological media. General boundary conditions and internal sources varied in both spatial and time variables are considered, thus, solutions for many special cases can be obtained with ease from the general solutions presented in this analysis.
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    Bulletin of mathematical biology 34 (1972), S. 393-412 
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    Notes: Abstract Two mathematical models of pulmonary single breath gas washout (one analytic, one numerical) are developed and their predictions compared with experimental data on human subjects. Weibel's 23 generation symmetric anatomical model is used as a guide to bronchial tree geometry. Experimental plots of nitrogen concentration versus volume expired, dead space versus breath holding time, and dead space versus tidal volume are compared with plots predicted by the models. Agreement is good. A plot of nitrogen concentration in the airways as predicted by the numerical model at different times during inhalation and exhalation of a single breath of oxygen is shown. Model predictions for changes in dead space with changes in washout gas and expiratory flow rate are discussed. Use of the analytic model for obtaining average values of the path length from mouth to alveoli in a given subject is discussed. To the extent of their agreement with experiment, the models provide a sound physical basis for the correlation of airway structure and function.
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    Bulletin of mathematical biology 34 (1972), S. 429-429 
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    Bulletin of mathematical biology 34 (1972), S. 419-427 
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    Notes: Abstract The Roginsky-Zeldovich (or Elovich) equation, which is −dx/dt=m exp (nx) (x=substrate concentration,t=time,m andn=constants), describes the kinetics of various biological electron and ion transport processes, and has been derived from the concept of charge transport across an activation energy barrier at an interface between dissimilar phases, driven by a difference in redox or ion potentials, with the simplifying assumptions that charge carrier concentration is constant, backward current across the interface is zero, and diffusion of substrate is fast. If charge carrier concentration is proportional to substrate concentration, then the kinetic equation is −dx/dt=mx exp (nx). If backward current is not zero, then −dx/dt=m 1 exp (n 1x) −m 2 exp (n 2 x), wherem 1,m 2,n 1 andn 2 are constants. Kinetic equations for interfacial charge transport in the presence of a significant substrate diffusion potential are also derived.
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    Bulletin of mathematical biology 34 (1972), S. 1-12 
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    Notes: Abstract A method is described for estimating cell-cycle parameters from experimental fraction-of-labeled-mitoses measurements. The method is closely related to that of J. C. Barrett (1970) but is based on the analysis of Brockwell and Trucco (1970) which takes into account population growth in the calculation of theoreticalFLM-functions. Several sets of experimental data are analyzed, among them the data for the Marshall tumor considered by Barrett. It is found that population growth has a small but nevertheless detectable effect on the estimates of the cell parameters.
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    Bulletin of mathematical biology 34 (1972), S. 33-44 
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    Notes: Abstract The radioactivity disappearance curves of glucose-6-14C albumin-I131 after a single injection of tracer into a human subject have been determined in detail, particularly at early time intervals. The curves, expressed as sums of exponentials, have been analyzed as the infinite sum of convolutions of single passage time densities. The resultant transfer time distribution of a single circulatory pass allows examination of all delays in the system no matter how long they take. The structural detail evident by this means and the long mean time of a single pass of glucose (〉5 min) supports the thesis that factors other than rapid and uniform diffusion play a role in the extravascular movements of glucose molecules.
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    Bulletin of mathematical biology 34 (1972), S. 13-31 
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    Notes: Abstract A bisexual multiple branching process is studied. Consider a population with respect to three genotypes in both the female and male populations and let $$X(n) = \left\langle {X_1 (n), X_2 (n), X_3 (n)} \right\rangle and Y(n) = \left\langle {Y_1 (n), Y_2 (n), Y_3 (n)} \right\rangle$$ be random vectors giving the number of females and males (respectively) of each genotype in generationn. The mating of females and males is accommodated in the model withZ ij (n) representing the number of females of theith genotype mated with a male of thejth genotype in generationn. The mating system is such that a female may be mated to only one male but a male may be mated with more than one female. By arranging the nine random variablesZ ij (n),i, j=1, 2, 3, in a 1×9, vectorZ(n) it is shown that under certain conditions there is a positive constant ϱ such that when ϱ〉1 the vectorsZ n /ρn,X n /ρn andY n /ρn converge almost surely asn→∞ to random vectors with fixed directions. The paper is divided into four sections. In section 1 the model is described in detail and its potential applications to population genetics are discussed. In section 2, the generating function of the transition probabilities of theZ-process are derived. Section3 is devoted to the study of the limiting behavior of the first and second moments of theZ-process, and in section4 the results of section3 are utilized to study the behavior of the random vectorsZ(n),X(n) andY(n) asn→∞.
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    Bulletin of mathematical biology 34 (1972), S. 45-52 
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    Notes: Abstract Herein we show that the voltage-clamp current density at zero time calculated from electrodiffusion equations is linear in the clamping voltage for a simple membrane (no charge structure) and for a membrae with fixed charges. Such membranes are nonexcitable. Excitable membranes can be represented by a homogeneous membrane with dipole layers at the surface. In this case the initial current density will be linear in the clamping voltage if a critical field for a dipole layer reorientation is not passed through in changing from holding to clamping potential. Otherwise, deviation from nonlinearity may occur. This is in agreement with experimental data for the squid giant axon.
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    Bulletin of mathematical biology 34 (1972), S. 65-69 
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    Notes: Abstract By generalizing a previous paper on periodicities in the endocrine system (Bull. Math. Biophysics,30, 735–749, 1968), it is shown that nonperiodic, sporadic oscillations in the system are also possible. A procedure of describing the feedback mechanism between the endocrine system and the central nervous system is suggested. It is shown that the combined system: endocrine—CNS, also may show sporadic fluctuations.
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    Bulletin of mathematical biology 34 (1972), S. 79-86 
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    Notes: Abstract This paper deals with a mathematical attempt to determine the wall shear during normal flow of blood in the ascending and the descending thoracic aorta. A simple model is used, but the results obtained are in agreement with published experimental results for the descending thoracic aorta. It is suggested that the degree of fluctuation in the pressure gradient at a given station is the major factor in determining the level of wall shear at that point.
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    Bulletin of mathematical biology 34 (1972), S. 71-78 
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    Notes: Abstract A neural model based on a generalization of a model proposed in 1938 in the first edition of the author'sMathematical Biophysics (Chicago: Univ. of Chicago Press) is described. It possesses the property that due to some endogenous or exogenous stimulus, which may be of random nature, a pathway may suddenly begin to fire spontaneously. This spontaneous firing may either gradually spread over other pathways and eventually cease, or it may remain localized within one or a few pathways and then cease. Which of the two types of events occurs depends on the values of a number of parameters. The case of spreading reminds one of Jacksonian epilepsy.
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    Bulletin of mathematical biology 34 (1972), S. 93-102 
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    Notes: Abstract The diffusion equation is solved for a membrane-bounded sphere situated in an infinite medium with different diffusion properties. The formal solution is obtained through Laplace transformation in the time variable. It is not possible to find a closed form solution in terms of analytical functions, and therefore a numerical inversion technique is applied to obtain the final solution. The application on a biological problem is discussed.
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    Bulletin of mathematical biology 34 (1972), S. 87-92 
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    Notes: Abstract It is shown that the individual rate constants can be determined for the composite chemical system: $$A + B_i \rightleftarrows C_i ; i = 1...N$$ with only measurements of the unbound species,A(t), required. The dissociation rate constants can be determined by direct analysis of a single steady state tracer study. The association constants then follow from the analysis of stable equilibrium determinations reported earlier (Hart, 1965). An approximate solution when tracer methods are in-applicable is also given.
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    Bulletin of mathematical biology 34 (1972), S. 103-112 
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    Notes: Abstract Certain arrangements of enzymatic (bimolecular) subsystems lead to characteristic threshold-type response. Two simple cases of such systems are studied here in terms of steady state behavior and explicit relationships between system and curve parameters. It is found that the curvature of the threshold curve is directly related to the equivalent Michaelis constant and, in the case of saturated threshold curve, the slope of the curve at the idealized threshold is limited by the ratio of saturation to threshold. This slope may be appreciably increased up to a stepwise response at the threshold if a multisubstrate complex of the enzyme is the only species which affects the enzyme mediated transport.
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    Bulletin of mathematical biology 34 (1972), S. 113-148 
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    Notes: Abstract Many experimental studies have indicated that the intraocular pressure is subject to mediation by adrenergic mechanisms affecting both the rate of formation of the aqueous humor and the resistance of the pathway through which the aqueous humor flows out of the eye. Thus, for example, the role of adrenergic drugs in glaucoma therapy is well known. How the mediation is accomplished has not been clarified in detail. Several possible mechanisms have been suggested, and all may indeed be involved. The present study is concerned with the basis and mathematical formulation of one of them and the consequences with respect to aqueous dynamics. The analysis leads to expressions for the aqueous outflow resistance and the formation rate, as well as other quantities of interest. The theoretical behavior is shown to compare favorably with the results of infusion studies and various other experiments, and to provide a unified picture of much of the pressure-flow behavior of both the living and the dead eye.
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    Bulletin of mathematical biology 34 (1972), S. 149-150 
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    Bulletin of mathematical biology 34 (1972), S. 151-172 
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    Notes: Abstract Following Wei's suggestion that nerve stimulation and conduction properties are due to dipole layers at the two membrane surfaces (Wei, 1969), we have done steady-state electro-diffusion calculations in the constant field approximation for a simple double-dipole-layer model. We are thereby able to quantitatively fit the recent potassium iso-osmotic rectification curves of Gilbert and Ehrenstein for the squid giant axon membrane. For the squid axon membrane in a natural ion environment, only the outside dipole layer is present in the fit to the data.
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    Bulletin of mathematical biology 34 (1972), S. 205-211 
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    Notes: Abstract In this paper the left ventricle of the heart was considered as a shell of varying thickness. The first and second fundamental forms of the middle surface, of the shell, as well as Euler's theorem were used for deriving expressions giving the length and curvature of the individual myocardial fibers. Recent anatomical studies have shown that the myocardial fibers in the middle of the left ventricular wall follow a course nearly parallel to the horizontal plane (Streeteret al., 1969). In previous papers (Voukydis 1969, 1970) a mathematical description of the curvature and length of the individual myocardial fibers was presented. Unfortunately, both the curvature and the length formulas contained the cotangent of the fiber helix angle, which approaches infinity as the fiber assumes a course parallel to the horizontal plane. Consequently, these two formulas cannot be used for fibers nearly parallel to the horizontal plane. The present paper will give an alternative way for calculating the length and curvature of the individual myocardial fibers, based on the fundamental forms of surface and on Euler's theorem.
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    Bulletin of mathematical biology 34 (1972), S. 231-242 
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    Notes: Abstract It is pointed out that the successes obtained in the mathematical biology of the central nervous system are based mostly on a number of more or less complicated neuronic circuit models, each inventedad hoc for the purpose of explaining a given phenomenon. The individual models remain disconnected from each other, however, and the unity of the CNS is not apparent. (Rashevsky,Mathematical Biophysics, 3rd Edition, Vol. II, 1960. New York, Dover Publications, Inc.) Some “field theories” of the CNS, as for example that of Griffith (Bull. Math. Biophysics,25, 111–120, 1963;27, 187–195, 1965), give more expression to this unity but lose in the explanation of specific phenomena. The present paper starts with the picture thatevery neuron in the brain isdirectly or indirectly affected to some extent byevery other neuron. This leads to a system of equations with a very large number of variables. Such a system can be replaced in the limiting case by an integral equation of the first kind. At least two specific results can be obtained with this approach and suggestions for further improvement are made.
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    Bulletin of mathematical biology 34 (1972), S. 379-392 
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    Notes: Abstract Pressure-volume and volume-dimensions relationships, obtained from excised dog left ventricles were used for calculating the stresses acting along the longitudinal axis of the individual myocardial fibers. The calculations were based on a set of empirical and theoretical equations. The pressure-volume relationship as well as the volume-dimensions relationships for the excised left ventricle were expressed in the form of empirical equations; the fiber orientation was written as a function of the fiber location within the left ventricular wall; finally, the fiber stress was determined by means of theoretically derived formulas. Simultaneous solutions for the fibers of a meridian cut through the left ventricular myocardial shell were obtained by means of a digital computer and presented in the form of diagrams. The results showed that at low degrees of distension of the left ventricle there are two zones of higher stresses at the equatorial area, one near the epicardium and one near the endocardium. As the distension proceeds under the effect of progressively increasing intraventricular pressure, these two zones become less well defined, whereas a new zone of higher stresses appears near the apex. At high degrees of distension, the ventricle assumes a more spherical shape and the equatorial zones of higher stresses are replaced by zones of lower stresses. Increase in the myocardial mass results in appearance of the equatorial lower stress zones at lower degrees of distension.
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    Mathematical programming 2 (1972), S. 130-132 
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    Mathematical programming 2 (1972), S. 133-165 
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    Notes: Abstract An algorithm for minimization of functions of many variables, subject possibly to linear constraints on the variables, is described. In it a subproblem is solved in which a quadratic approximation is made to the object function and minimized over a region in which the approximation is valid. A strategy for deciding when this region should be expanded or contracted is given. The quadratic approximation involves estimating the hessian of the object function by a matrix which is updated at each iteration by a formula recently reported by Powell [6]. This formula enables convergence of the algorithm from any feasible point to be proved. Use of such an approximation, as against using exact second derivatives, also enables a reduction of about 60% to be made in the number of operations to solve the subproblem. Numerical evidence is reported showing that the algorithm is efficient in the number of function evaluations required to solve well known test problems.
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    Mathematical programming 3 (1972), S. 178-192 
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    Notes: Abstract We study quasi-convex and pseudo-convex quadratic functions on solid convex sets. This generalizes Martos' results in [12] and [13] by using Koecher's results in [8].
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    Mathematical programming 3 (1972), S. 157-177 
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    Notes: Abstract A partitioning algorithm for solving the general minimum cost multicommodity flow problem for directed graphs is presented in the framework of a network flow method and the dual simplex method. A working basis which is considerably smaller than the number of capacitated arcs in the given network is employed and a set of simple secondary constraints is periodically examined. Some computational aspects and preliminary experimental results are discussed.
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    Mathematical programming 3 (1972), S. 396-396 
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    Mathematical programming 3 (1972), S. 1-22 
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    Notes: Abstract Given a point to set mapf on a simplex with certain conditions, an algorithm for computing fixed points is described. The algorithm operates by following the fixed point as an initially affine function is deformed towardsf.
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    Computing 10 (1972), S. 23-31 
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    Description / Table of Contents: Abstract Rounding errors which are inevitably made during the evaluation of a function by a computer lead to the problem of calculating zeros of an approximately computed function. We describe some methods generating simultaneously lower and upper bounds for zeros including all round-off errors automatically. A comparison with running error analysis [19] is given.
    Notes: Zusammenfassung Betrachtet wird die Aufgabe der Nullstelleneingrenzung von nur näherungsweise berechenbaren Funktionen. Dazu werden Verfahren verwendet, welche sowohl die unvermeidlichen Rundungsfehler als auch Ungenauigkeiten in den Ausgangsdaten automatisch miterfassen. Nach einer Beschreibung der zugrundeliegenden Methoden wird ein Vergleich mit anderen bekannten Vorgehensweisen, insbesondere mit running error analysis [19], gezogen.
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    Computing 10 (1972), S. 107-109 
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    Description / Table of Contents: Abstract Given a graph by a node-node-matrix. One finds the distanced ij of two nodesP i andP j by using binary operations between the rows of the node-node-matrix.
    Notes: Zusammenfassung Ein Graph sei gegeben durch seine Knoten-Knoten-Matrix. Den Abstandd ij von zwei KnotenP i undP j des Graphen bestimmt man mit Hilfe von binären Verknüpfungen der Zeilen der Knoten-Knoten-Matrix.
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    Computing 10 (1972), S. 97-106 
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    Description / Table of Contents: Zusammenfassung Der Effekt der Rundungsfehler in einem algebraischen Prozeß wird oft mit einer sogenannten Rückwärtsanalyse untersucht. Wir wollen hier die Möglichkeit untersuchen, diese Analyse auf einem Computer auszuführen. Wir beginnen mit einer genauen Definition eines stabilen Algorithmus, oder aber eines Algorithmus der relativ unempfindlich auf Rundungsfehler reagiert.
    Notes: Abstract The effect of rounding errors on an algebraic process is often investigated by means of a so-called backward analysis. In this paper we will discuss the possibility of performing such an analysis on a computer. We begin with a precise definition of a stable algorithm, i.e., an algorithm which is relatively insensitive to rounding errors.
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    Computing 10 (1972), S. 137-152 
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    Computing 10 (1972), S. 167-175 
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    Description / Table of Contents: Abstract When solving linear equations with elimination methods, pivotal strategies are used to improve numerical precision. In this paper some new pivotal strategies are suggested and compared with known strategies by means of numerical experiments.
    Notes: Zusammenfassung Bei der Lösung linearer Gleichungssysteme mit Eliminationsmethoden verwendet man Pivot-Strategien zur Steigerung der numerischen Genauigkeit. In dieser Arbeit werden einige neue Pivot-Strategien vorgeschlagen und mit bekannten Strategien an Hand numerischer Experimente verglichen.
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    Computing 10 (1972), S. 189-190 
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    Description / Table of Contents: Abstract A coherence is pointed out between a general spline-approximation and the dynamic programming. In this way it is possible to construct a numerical method for the solution of complicated approximation problems. For instance eachLp-approximation including the Tschebyscheff-approximation problem may be solved regarding inequality constraints between the element parameters of the spline function and varying the generally fixed spline knots. Moreover it is possible to treat more general problems arising from optimisation calculations during the design of roads.
    Notes: Zusammenfassung Es wird ein Zusammenhang hergestellt zwischen einer verallgemeinerten Spline-Approximation und der dynamischen Optimierung. Dadurch ist es möglich, ein numerisches Verfahren zur Lösung von komplizierten Approximationsaufgaben anzugeben. Beispielsweise läßt sich damit jedeLp-Approximation einschließlich der Tschebyscheff-Approximation numerisch behandeln unter Berücksichtigung von Ungleichungsnebenbedingungen zwischen den Elementparametern der Spline-Funktion und unter Freigabe der üblicherweise festgehaltenen Spline-Knoten. Darüber hinaus lassen sich dadurch allgemeinere Aufgaben lösen, die bei Optimierungsberechnungen während der Entwurfsbearbeitung von Straßen auftreten können.
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    Computing 10 (1972), S. 83-95 
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    Description / Table of Contents: Abstract As well known, Gauss-quadrature formulas are constructed by integration of suitably choosen Hermitian interpolating polynomials. At first, a general linear interpolating operator and its error-term are given. Integrating this operator, one yields quadrature formulas containing some first derivatives of the integrand-function. By the requirement, that the weights of these derivatives should vanish all together, we get general quadrature formulas of Gauss-type. For some special basic functions of the interpolating operator, vanishing of the weights of the derivatives is necessary for minimization of the quadrature error. The general Gauss-quadratures may be determinated algebraically if sufficiently many fix-elements of the interpolating operator are known. As special cases one has, besides the known usual Gauss-quadratures and Wilf's quadrature procedure, a very surprising result.
    Notes: Zusammenfassung Die Gaußschen Quadraturformeln erhält man bekanntlich durch Integration geeignet gewählter Hermitescher Interpolationspolynome. Zunächst wird hier ein allgemeiner linearer Interpolationsoperator mit Restglied angegeben. Durch Integration dieses Operators erhält man Quadraturformeln die neben Funktionswerten auch Werte der 1. Ableitung des Integranden enthalten. Fordert man, daß die Gewichte dieser Ableitungswerte sämtlich verschwinden, so erhält man allgemeine Gaußsche Quadraturformeln. Bei speziellen Arten von Basisfunktionen des Interpolationsoperators ist das Verschwinden der Gewichte der Ableitungswerte notwendig für die Minimierung des Quadraturrestes. Die allgemeinen Gaußschen Quadraturformeln lassen sich bei Kenntnis von hinreichend vielen Fixelementen des Interpolations-operators auch algebraisch herleiten. Als Sonderfälle erhält man neben der bekannten gewöhnlichen Gauß-Quadratur das Wilfsche Quadraturverfahren, ein sehr überraschendes Ergebnis.
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    Computing 10 (1972), S. 121-136 
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    Description / Table of Contents: Abstract In Part I is shown, how to decompose a connected graph into triply connected components in a canonical manner and how to compute a standard form of an arbitrary graph from standard forms of triply connected graphs. Hence, in part II a method is given, which allows to construct a standard form of triply connected planar graphs. Besides that, an ALGOL-program is presented which realizes both this method and a planarity criterium.
    Notes: Zusammenfassung In Teil I wird gezeigt, wie ein zusammenhängender Graph in kanonischer Weise in dreifach-zusammenhängende Komponenten zerlegt werden kann, und wie man aus Normalformen dreifach-zusammenhängender Graphen Normalformen beliebiger Graphen erhält. In Teil II wird dann eine Methode zur Gewinnung von Normalformen dreifach-zusammenhängender Graphen dargestellt. Außerdem wird ein ALGOL-Programm angegeben, das diese Methode sowie ein Planaritätskriterium realisiert.
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    Computing 10 (1972), S. 231-244 
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    Description / Table of Contents: Abstract In this paper an intervalanalytic generalization of the theorem ofPrager-Oettli is used to characterize the solution-set of an, n-system of linear equations with interval coefficients as union of convex polyhedra with special properties. Then it is shown how to deduce from the theorem ofPrager-Oettli a nearly optimaln-interval contained in the solution-set. On the other hand the problem of finding with reasonable expense sharpn-intervals containing the solution-set is solved only for special cases. Some results on this problem are discussed; a numerical example shows the importance of criteria, under which sharpn-intervals can be computed with reasonable effort.
    Notes: Zusammenfassung In der vorliegenden Arbeit wird mit Hilfe einer intervallanalytischen Verallgemeinerung des Satzes vonPrager-Oettli die Lösungsmenge von Intervallgleichungssystemen als Vereinigung von konvexen Polyedern mit speziellen Eigenschaften charakterisiert. Anschließend wird gezeigt, wie sich aus dem Satz vonPrager-Oettli brauchbare Innenabschätzungen der Lösungsmenge ableiten lassen. Dagegen ist das Problem, möglichst scharfe Außenabschätzungen mit vertretbarem Aufwand zu bestimmen, vorerst nur unter gewissen Voraussetzungen gelöst. Einige Ergebnisse zu diesem Problem werden diskutiert; ein numerisches Beispiel verdeutlicht die Bedeutung von Kriterien, unter denen scharfe Außenabschätzungen mit vertretbarem Aufwand berechnet werden können.
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    Computing 10 (1972), S. 271-283 
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    Description / Table of Contents: Abstract Floyd developed a matrix algorithm to find all shortest paths in a network. If we modify the algebraic structure of the network the same algorithm can be applied to large number of other problems. A general theory for these algorithms is developed and applied to numerous problems.
    Notes: Zusammenfassung Floyd entwickelte einen Matrixalgorithmus zur Bestimmung der Längen aller kürzesten Wege in einem Netzwerk. In der vorliegenden Arbeit wird gezeigt, daß, falls man den Begriff des Netzwerkes etwas verallgemeinert, sich mit Hilfe des gleichen Verfahrens eine Fülle von grundverschiedenen Problemen lösen läßt. Es wird eine entsprechende Theorie entwickelt und an Beispielen erläutert.
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    Computing 10 (1972), S. 317-333 
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    Description / Table of Contents: Abstract The paper describes an automatic drawing algorithm permitting every planar graph to be displayed with straight lines in the plane, if the cyclic order of the adjacent vertices for every vertex of the graph is found out by a topological algorithm for planarity. In this connection also a sufficient condition is proved for the uniqueness of the above mentioned cyclic order in every drawing without crossings.
    Notes: Zusammenfassung Es wird ein automatischer Zeichenalgorithmus beschrieben, der es gestattet, jeden planaren Graphen geradlinig in die Ebene abzubilden, wenn die zyklische Reihenfolge der Nachbarknoten nach einem topologischen Planarisierungsalgorithmus für jeden Knoten des Graphen bekannt ist. In diesem Zusammenhang wird auch eine hinreichende Bedingung dafür angegeben, daß die oben erwähnte zyklische Reihenfolge in einer kreuzungsfreien Zeichung des Graphen durch diesen eindeutig bestimmt ist.
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    Computing 10 (1972), S. 335-351 
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    Description / Table of Contents: Zusammenfassung Verteilt man geometrische Objekte in zufälliger Lage im Raum oder in der Ebene, so bilden sich durch Überlappen sogenannteKlumpen. In der vorliegenden Arbeit wird die asymptotische Verteilung der Anzahl von Klumpen gegebener Größe und topologischer Struktur innerhalb des folgenden Modells untersucht: Sindx 1, ...,x n Punkte im ℝ n und istU=-U⊂ℝ eine symmetrische Menge, dannüberlappen sich die Punktex i undx j , oder besser, sie bilden eineU-Koinzidenz, genau dann, wennx i −x j ∈U gilt. Wir ordnen den Punktenx 1, ...,x n undU den sogenanntenKoinzidenzgraphen G(x 1, ...,x n ;U)≔≔({1, ...,n}, {[i, j]:1≤i〈j≤n, x i −x j ∈U}) zu und fragen nach der AnzahlL(x 1, ...,x n ;U, H) zusammenhängender Komponenten vonG(...), die zu einem festen GraphenH isomorph sind. In der vorliegenden Arbeit wird die asymptotische Verteilung vonL(...) unter verschiedenen Voraussetzungen über die Verteilung der Punktex 1, ...,x n sowie die Größe vonU untersucht. In Abhängigkeit von diesen Voraussetzungen ist die asymptotische Verteilung vonL(...) entweder eine Normal- oder eine Poisson-Verteilung.
    Notes: Abstract When objects are scattered at random in the plane or in space, some of them overlap to form clumps. It is the object of the present paper to study the asymptotic distribution of the number of clumps of given size and topological structure generated within the following model: Ifx 1, ...,x n are points in ℝ n andU=-U⊂ℝ n is a symmetric set, then the pointsx i andx j are said tooverlap or rather to form aU-coincidence, ifx i −x j ∈U. Adjoining tox 1, ...,x n andU, the graphG(x 1, ...,x n ;U)≔({1, ..., n}, {[i, j]:1≤i〈j≤n;x i −x j ∈U}), the so calledcoincidence-graph, we ask for the number of connected components of this graph isomorphic to a given graphH and call this numberL9x 1, ...x n ;U, H). In the paper, the asymptotic distribution ofL(...) under various assumptions about the distribution of the pointsx 1, ...,x n and the size ofU is studied. Depending on these assumptions, we prove that the asymptotic distribution ofL(...) is either Poisson or normal.
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    Meteorology and atmospheric physics 21 (1972), S. 247-272 
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    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Die Arbeit befaßt sich mit einer Untersuchung der atmosphärisch-elektrischen Zustände und Vorgänge in 700 bis 3000 m Höhe während Niederschlages verschiedenster Arten. Die Beziehung zwischen Potentialgradient (Feldstärke)E oder Spitzenentladungsstromi po und NiederschlagsstromdichteI pr läßt sich durch Regressionsgerade darstellen, deren Charakter bei gleichmäßigem Niederschlag unabhängig ist von der Art des Niederschlages und von der Höhe. Die Niederschlagsrate spielt nur eine nebensächliche Rolle und bestimmt nicht den Charakter der oben genannten Beziehungen. Bei gleichmäßigem Niederschlag sind Polarität vonE,I pr undi po durch den Aggregatzustand des Niederschlages bestimmt. Bei Schneefall sindE,i po positiv,I pr negativ. In Regen gelten umgekehrte Vorzeichen. Der Vorzeichenwechsel erfolgt, wenn Schneepartikel im freien Fall schmelzen, was im Mittel bei +1,1°C erfolgt. Der bekannte Spiegelbildeffekt gilt als Regel, nicht jedoch als exaktes Gesetz. Eine Reihe von Beobachtungen über Abweichungen von der strengen Spiegelung der Werte weist darauf hin, daß die Theorie nicht gelten kann, welche darauf beruht, daß primär hohe Werte vonE Spitzenentladungen auslösen, die ihrerseits Ionen erzeugen, welche durch Niederschlag eingefangen werden, so daßE undI pr spiegelbildlich verlaufen. Vielmehr werden durch niederschlags-elektrische Prozesse primärE und sekundäri po beeinflußt. Die Ladung an Wolkenunterseiten ist — außer beim Gewitter — für niederschlags-elektrische Vorgänge ohne Belang. Im Niederschlag wird das Verhalten der luftelektrischen Größen durch die niederschlags-physikalischen Vorgänge in der allernächsten Umgebung vom Beobachtungspunkt bestimmt. Die oben genannten Polaritäten der luftelektrischen Größen während Niederschlages gelten nur für gleichmäßigen Niederschlag. Nimmt die atmosphärische Stabilität unter einen gewissen Schwellenwert ab, so treten Polaritätswechsel der atmosphärisch-elektrischen Größen auf, die nichts mit dem Aggregatzustand und auch nichts mit der elektrischen Ladung an der Wolkenunterseite (außer im Gewitter) zu tun haben. Die Häufigkeit der Polaritätswechsel läßt sich als Funktion der Austausch-Intensität über der Station darstellen. Diese Beziehung kann für praktische Zwecke der Bestimmung des Turbulenzgrades verwendet werden.
    Notes: Summary This paper is concerned with a study of the atmospheric electrical conditions and processes at 700 up to 3000 m a. s. l. during precipitations of the most varied kind. The relation between potential gradientE or, respectively, point discharge currenti po , and precipitation current densityI pr may be represented by regression lines whose character during steady precipitations is independent of the kind of precipitation or altitude a. s. l. The precipitation rate plays only a subordinate part and does not control the character of the above mentioned relations. During steady precipitations the polarities ofE,I pr andi po are determined by the physical state of the precipitations. During snowfall,E andi po are positive,I pr is negative; during rainfall, the opposite signs apply. The sign reversal takes place when snow particles melt in free fall, which, as an average, takes place at +1.1° C. The well-known mirror image effect applies as a rule rather than an exact law. A number of observations regarding deviations from the strict mirroring of the values indicate that the theory cannot be valid which claims that high primary values ofE would trigger point discharges which, in turn, generate ions that are captured by precipitation, with the result thatE andI pr proceed in a mirror-inverted manner. The truth is that by processes of precipitation electricity,E is primarily influenced, andi po secondarily. The charge on cloud bases, except in thunderstorms, is irrelevant to precipitation electrical processes. In precipitation, the behavior of the atmospheric electrical quantities is governed by the precipitation physical processes in the most immediate vicinity of the observation site. The above mentioned polarities of the atmospheric electric quantities during precipitation are applicable only to steady precipitations. If the atmospheric stability is decreased below a certain threshold value, polarity changes of the atmospheric electrical quantities will occur which have nothing to do with the physical state nor with the electric charge on the cloud base (except in thunderstorms). The frequency of the polarity changes may be presented as a function of the exchange intensity above the station. This relation may be used for practical purposes of determining the degree of turbulence.
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    Meteorology and atmospheric physics 21 (1972), S. 299-306 
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    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Die Ladungsübertragung infolge von Zusammenstoß und nachfolgender Trennung von Wassertropfen, die in einem elektrischen Felde fallen, ist untersucht worden. Die übertragene Ladungq wurde, gemessen bei Werten der FeldstärkeE, des Tropfenradiusr, des RadienverhältnissesR/r, der Zusammenstoß-GeschwindigkeitV und dem Winkel Θ in den Bereichen von 0,5 bis 80 kV/m fürE, 200 bis 600 μm fürr, 1,0 bis 3,0 fürR/r, 0,5 bis 3 m/sec fürV und 0 bis 90° für Θ. Θ bedeutet den Winkel zwischen der Feldrichtung und der Verbindungslinie der Tropfenmittelpunkte im Augenblick der Trennung. Zwei gleich große Ströme von Tropfen wurden aus hypodermischen Kanülen ausgestoßen (durch Beeinflussung des Wasserstromes durch diese). Diese Ströme wurden dann zum Zusammenstoßen gebracht in einem Raum, in der durch zwei Elektroden ein elektriches Feld aufrechterhalten wurde. Die einzelnen Tropfen stießen vorübergehend zusammen, bewegten sich dann umeinander und trennten sich wieder, wonach jeder der beiden Ströme in einem isolierten Gefäß aufgefangen wurde, welches zur Ladungsmessung mit einem Elektrometer verbunden war. Die gemessenen Ladungen waren im allgemeinen in guter Übereinstimmung mit den aus der Gleichungq = 1,1 · 10-10 γ1 E r 2 Cos Θ berechneten, worin γ1 eine Funktion vonR/r darstellt. Aufgrund dieser Gleichung, der Marshall-Palmerschen Tropfengrößen-Verteilungsfunktion und annehmbarer Werte für die Trennungswahrscheinlichkeit zusammenstoßender Tropfen durchgeführte Berechnungen zeigten, daß Zusammenstöße zwischen Regentropfen in elektrifizierten Wolken zu einer Zerstörung des bestehenden Feldes kräftig beitragen.
    Notes: Summary Studies have been made of the charge transfer resulting from the collision and separation of water drops falling in an electric field. The charge transferq was measured for values of field strengthE, impact velocityV, drop radiiR, r, radius ratioR/r, and angle Θ ranging from 0.5 to 80 kV/m, 0.5 to 3 m·sec−1, 200 to 600 μ, 1.0 to 3.0 and 0 to 90 degrees respectively, where Θ is the angle between the field and the line of centres of the drops at the moment of separation. Two uniformly sized drop-streams were ejected from hypodermic needles by modulating the flow of water through them and then collided between a pair of electrodes across which a potential difference existed. The drops coalesced temporarily, swung around each other and separated, each resulting stream being collected in a vessel connected to an electrometer in order to measure the charge. The measured values ofq were generally in good agreement with theoretical values derived from the equationq = 1.1 · 10-10 γ1 E r 2 Cos Θ, where γ1 is a function ofR/r. Calculations based on this equation, the Marshall-Palmer drop-size distribution and established values of separation probabilities of colliding drops showed that collisions between raindrops within electrified clouds will act powerfully to dissipate the existing fields.
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    Meteorology and atmospheric physics 21 (1972), S. 329-338 
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    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Bekanntlich wird die Messung luftelektrischer Elemente durch Wind beeinflußt, und Tage mit starkem Wind werden gewöhnlich als luftelektrisch gestört bezeichnet, wobei eine Grenze bei 6 m/sec gesetzt wird. Der Einfluß horizontaler Winde auf das luftelektrische Feld ist zwar durch die Änderungen der Raumladungsdichte erklärbar; es wird hier aber gezeigt, daß der beobachtete Einfluß auf den luftelektrischen Vertikalstrom nicht vollständig durch Änderungen der örtlichen Leitfähigkeit und des Feldes erklärt werden kann. Das Vorhandensein eines vertikalen Advektionsstromes von der Größe ɛ0χ e υ x (∂E z /∂ x ) wird dargelegt, und es wird durch Berechnung gezeigt, daß er dann bedeutsam ist, wenn große Raumladungsdichten durch den Wind horizontal bewegt werden (zum Beispiel bei Staubstürmen und beim Auftreten von Spitzenentladungen). Da dieser vertikale Advektionsstrom zu υ x (∂E z /∂ x ) proportional ist, wird empfohlen, anstelle des üblichenv x diesen Parameter als Kriterium zur Bestimmung der Windstörung bei luftelektrischen Schönwettermessungen zu verwenden.
    Notes: Summary The measured values of electrical parameters of the atmosphere are known to be affected by wind, and days with strong winds (v x 〉6 m s−1) are normally classified as electrically disturbed. While the effect of horizontal wind on the electric field is readily explained in terms of changes in the spacecharge density, it is shown from electrodynamical considerations that the observed effect on the air-earth current cannot always be attributed solely to changes in the local conductivity and electric field. The existence of a vertical current of advection of magnitude ɛ0χ e υ x (∂E z /∂x) is revealed, and shown by calculations to be important (for instance during dust-storms and pointdischarge) when large space-charge concentrations are advected by wind. Since the current of advection is proportional tov x (∂E z /∂x), it is suggested that this parameter rather thanv x be used as a criterion for deciding wind-disturbed measurements of routine fair-weather atmospheric electric parameters.
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    Meteorology and atmospheric physics 21 (1972), S. 399-412 
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    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Zur Bestimmung der spezifischen Ozonzerstörungsrate der Meeresoberfläche wurden Profilmessungen zwischen 1 m und 20 m Höhe über der offenen See durchgeführt. Der Gradient der Ozonkonzentration erwies sich in den Grenzen der Meßgenauigkeit als unabhängig von der Horizontal-Windgeschwindigkeit. Im Geschwindigkeitsintervall 1 m/sec bis 10 m/sec ergab sich für stabile Schichtung ein mittlerer Gradient von (0,23±0,12) γ/m, für instabile Schichtung (0,09±0,018) γ/m bei einer angenommenen Ozonkonzentration von 100 γ in 25 m Höhe. Im betrachteten Windgeschwindigkeitsintervall sind somit der vertikale Ozonfluß und die spezifische Ozonzerstörungsrate der Meeresoberfläche proportional zur Windgeschwindigkeit. Für die Ozonzerstörungsrateq gilt als Zusammenhang mit der mittleren Windgeschwindigkeit $$\bar u_{10} $$ in 10 m Höhe $$q = (1,7 \pm 0,6)10^{ - 5} \cdot \bar u_{10} [cm/\sec ]$$ Oberhalb 30 m Höhe ergaben Ballonsondierungen ein konstantes Mischungsverhältnis von Ozon und Luft.
    Notes: Summary The specific ozone destruction rate at the ocean surface was estimated from profile measurements between 1 m and 20 m height above the open sea. The ozone concentration gradient turned out to be independent of the horizontal wind velocity within the instrumental error range. Within the velocity interval of 1 m/sec to 10 m/sec a mean gradient of (0.23±0.12) γ/m for stable stratification and of (0.09±0.018) γ/m for unstable stratification were obtained. Both values base upon an assumed ozone concentration of 100 γ at 25 m altitude. Thus, the vertical flux of ozone and the specific ozone destruction rate of the ocean surface are proportional with the wind velocity. Between the specific ozone destruction rateq and the average wind velocity $$\bar u_{10} $$ at 10 m height the relation $$q = (1.7 \pm 0.6)10^{ - 5} \cdot \bar u_{10} [cm/\sec ]$$ holds. Above 30 m height the results of balloon soundings indicate the mixing ratio ozone/air to be constant with altitude.
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    Meteorology and atmospheric physics 21 (1972), S. 353-372 
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    Topics: Geography , Physics
    Description / Table of Contents: Summary Daily global cloud observations effectuated by means of the meteorological sattelites ESSA 3 and 5 in the year 1967 which made possible the global observation of terrestrial weather phenomena are the base of this paper. The author primarily treats vortex structures which led to the formation of cloud spirals. In 1967, over the entire globe 405 vortices with spiral structure appeared, 180 of them over the northern hemisphere and 225 over the southern hemisphere. The source regions were the North-Atlantic and North-Pacific on the northern hemisphere, on the southern hemisphere the source regions formed a broad belt encircling the entire globe. The paths of the vortices are directed mainly to north-east over the northern hemisphere, but to east-south-east over the southern hemisphere. The source regions of the vortex structures in one series are often cloud bands with a length of 5000 to 10000 km. They begin near the equator and cross the oceans. These bands are quasi-stationary, often have a life-time of 3 to 5 days, and show a strong bundling over certain areas of the earth. Above all, four bundles emerge building up the shape of a “fish-bone”. Over the Atlantic one bundle extends from the tropical Central-America in north-eastward direction to the middle North-Atlantic, the counter-bundle from the tropical regions of the Amazon to the south-east, crossing Brazil, to the South-Atlantic. Over the Pacific Ocean one finds similar long cloud-bundles extending from the equator in north-eastern and south-eastern direction. These four bundles direct one's attention to certain regions of the earth, which might be of great importance for the air exchange between the hemispheres. These are especially two regions: one of them is situated at the transition region from the North-American to the South-American, the second one in the equatorial region between Southeast-Asia and Australia.
    Notes: Zusammenfassung Dieser Arbeit liegen tägliche globale Wolkenbeobachtungen der meteorologischen Satelliten ESSA 3 und 5 des Jahres 1967 zugrunde [1], die eine Totalbetrachtung irdischer Wettervorgänge ermöglichen. In der vorliegenden Untersuchung wurden vor allem Wirbelstrukturen behandelt, die zur Bildung von Wolkenspiralen geführt haben. Im Jahre 1967 traten auf der ganzen Erde 405 Wirbel mit Spiralstruktur auf, davon 180 auf der Nordhemisphäre und 225 auf der Südhemisphäre. Als Quellenherde traten auf der Nordhemisphäre Nordatlantik und Nordpazifik hervor, auf der Südhemisphäre ergab sich eine Anordnung der Quellgebiete in Form eines breiten Gürtels, der um den Globus herumläuft. Die Wirbelbahnen verlaufen auf der Nordhemisphäre überwiegend in nordöstlicher, auf der Südhemisphäre in ostsüdöstlicher Richtung. Die Ursprungsgebiete der Wirbelstrukturen in einer Serie sind häufig Wolkenbänder mit einer Länge von 5000 bis 10000 Kilometern. Sie entspringen in der Nähe des Äquators und verlaufen quer über die Meere. Diese Bänder, die quasistationär sind und häufig eine Lebensdauer von drei bis fünf Tagen haben, zeigen über bestimmten Gebieten des Globus eine starke Bündelung. Vor allem treten vier Bündel hervor, die ein „Fischgrätenmuster” bilden. Über dem Atlantik verläuft ein Bündel vom tropischen Mittelamerika nach Nordosten bis zum mittleren Nordatlantik, das „Gegenbündel” von den tropischen Gebieten des Amazonenstromes nach Südosten über Brasilien zum Südatlantik. Über dem Pazifischen Ozean lassen sich ganz ähnliche, vom Äquator nordost- bzw. südostwärts verlaufende Bündel von Langen Wolkenbändern finden. Die vier Bündel weisen auf ganz bestimmte Regionen der Erde hin, die beim Luftaustausch zwischen den Hemisphären von großer Bedeutung sein dürften. Es sind dies besonders zwei Regionen: die erste liegt an der Übergangsstelle vom nordamerikanischen zum südamerikanischen Kontinent, die zweite in der äquatorialen Region zwischen Südostasien und Australien.
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    Monatshefte für Mathematik 75 (1972), S. 289-290 
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    Monatshefte für Mathematik 75 (1972), S. 291-295 
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    Monatshefte für Mathematik 75 (1972), S. 296-302 
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    Monatshefte für Mathematik 75 (1972), S. 303-315 
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    Monatshefte für Mathematik 75 (1972), S. 316-319 
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    Monatshefte für Mathematik 75 (1972), S. 320-323 
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    Monatshefte für Mathematik 75 (1972), S. 324-332 
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    Monatshefte für Mathematik 75 (1972), S. 333-337 
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    Monatshefte für Mathematik 75 (1972), S. 338-340 
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    Monatshefte für Mathematik 75 (1972), S. 341-345 
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    Monatshefte für Mathematik 75 (1972), S. 346-362 
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    Monatshefte für Mathematik 75 (1972), S. 363-384 
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    Monatshefte für Mathematik 76 (1972), S. 1-20 
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    Monatshefte für Mathematik 76 (1972), S. 21-30 
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    Monatshefte für Mathematik 76 (1972), S. 31-42 
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    Monatshefte für Mathematik 76 (1972), S. 43-54 
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    Monatshefte für Mathematik 76 (1972), S. 55-65 
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    Monatshefte für Mathematik 76 (1972), S. 66-77 
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    Monatshefte für Mathematik 76 (1972), S. 97-108 
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    Monatshefte für Mathematik 76 (1972), S. 78-96 
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    Monatshefte für Mathematik 76 (1972), S. 109-111 
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    Monatshefte für Mathematik 76 (1972), S. 112-117 
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    Monatshefte für Mathematik 76 (1972), S. 118-120 
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    Monatshefte für Mathematik 76 (1972), S. 121-123 
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    Monatshefte für Mathematik 76 (1972), S. 124-129 
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    Monatshefte für Mathematik 76 (1972), S. 130-134 
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    Monatshefte für Mathematik 76 (1972), S. 135-137 
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    Monatshefte für Mathematik 76 (1972), S. 138-142 
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    Monatshefte für Mathematik 76 (1972), S. 143-153 
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