Showing papers in "Journal of Theoretical Biology in 1969"

TL;DR: The hypothesis that contemporary organisms are also randomly constructed molecular automata is examined by modeling the gene as a binary (on-off) device and studying the behavior of large, randomly constructed nets of these binary “genes”.

TL;DR: These concepts provide a unifying framework within which a wide variety of patterns formed from fields may be discussed, and give new meaning to classical concepts such as induction, dominance and field.

TL;DR: In this paper, a mathematical description of component enzymatic reactions is developed as a first step toward a method of analysis for biochemical systems, which serves to emphasize the particular nonlinearities encountered in these components.

TL;DR: The determinant method, based on the determinant of the covariance matrix of the capture points, is introduced and it is shown that this method, under specified assumptions, is free from both forms of bias.

TL;DR: A power-law approximation technique based on the non-linear nature of these reactions is presented, which is considerably greater than in the linear case, while the effort necessary to obtain steady-state solutions is about the same.

TL;DR: A model developed in the present paper is one in which the map arises from wave-like propagation of activity from localized clocks or pacemakers, and has a high informational capacity and is readily applied to the discussion of particular developmental phenomena.

TL;DR: In the light of the suggested hypothesis it is possible to explain the mechanism of tumour transformation, produced by oncogenic DNA-containing viruses and by some other factors.

TL;DR: In this paper, a discussion of physico-chemical laws gives the following conclusions (1) The viscosity of polymeric contrast agents could be kept at a minimum if the axial ratio of the contrast medium molecule is kept as close to one as possible.

TL;DR: Some neurophysiological and biochemical predictions concerning transmitter production and release which are suggested by psychological postulates are made, suggesting that nerve cells are capable of learning as ‘chemical dipoles’.

TL;DR: The authors presented a number of distributions, some derivable from explicit mechanisms and others not, which approach the log-normal distribution or its integral, and stressed the variety of circumstances that lead to the log normal distribution or approximations to it.

TL;DR: It is shown that under strong coupling the oscillators oscillate at only a fraction of the frequency that each one of them would oscillate if they were not interconnected, suggesting a possible mechanism for obtaining 24-hour periods from biochemical oscillators whose period is only a few minutes.

TL;DR: The behaviour of this theoretical model of vesicular transport across an ideal endothelial cell is analyzed in terms of the theory of Brownian motion in the presence of an absorbing barrier, by computer simulation, and it is shown that if cytoplasmic viscosity is assumed to be in the vicinity of 800 cp, the vesicle transit times for this ideal cell can be reconciled.

TL;DR: The possibility that orientation is based, in part, on the detection of some chemical substance originating at Ascension Island, and the potential advantage of having the hatchlings imprinted by the taste or odor of the waters near their birthplace is considered.

TL;DR: Values of the stem cell percentage and total cell number, as calculated from the model, and experimentally observed in developing colonies, are in satisfactory agreement, provided the chain of differentiating erythroblasts is expanded.

TL;DR: A mathematical method is given for calculating the upper limit of possible DNA homology between any set of two bacteria, which depends on three parameters: the mean nucleotide composition, the molecular weight and the compositional nucleotide distribution of chromosomal DNA.

TL;DR: No evidence was found which was inconsistent with the “bulk-liquid” hypothesis but the variation of the composition of the membranes with temperature made the system undesirably complicated and in consequence no rigorous test of the hypothesis was possible.

TL;DR: Charge distributions calculated for these three-dimensional molecules suggest that opposing resonance and electrostatic repulsions can contribute to the high free energies of hydrolysis of the polyphosphates near pH 7.5.

TL;DR: The applicability of Goldman's constant field assumption is examined by constructing an asymptotic solution of the Nernst-Planck-Poisson equations, valid as a certain dimensionless parameter α −2 approaches zero.

TL;DR: The conclusions of Ulyott that klinokinetic behavior in the presence of sensory adaptation can cause a directional displacement of an organism along a gradient of stimulus intensity were confirmed.

TL;DR: The mechanism leading to oscillations of respiration rate in Klebsiella aerogenes in continuous culture is described qualitatively and the mathematical model for electrochemical oscillations is applicable in the present case.

TL;DR: The Boyle-Van't Hoff relation is here derived via classical thermodynamics, assuming that the chemical potential of water is equal across a membrane permeable to water only.

TL;DR: It is shown that forced convection usually ruptures the membrane before the boundary layers become insignificant, and the true lipid membrane permeability has been calculated from the diffusion of tritiated water in known linear velocity fields in the aqueous phases.

TL;DR: It is believed that terms measuring this prior information should be added and it is shown that when this is done the resulting expressions are essentially equivalent.

TL;DR: A velocity response curve is proposed in which the speeding up or slowing down would occur only during certain hours of competency in the circadian cycle, the rate of change being concomitant with the differing degree or response to light at various times during those competent hours, and the absolute light intensity.

TL;DR: A new technique for estimating energy fluxes in food webs is developed, based upon the probability of predator-prey interactions, by utilizing a parameter for weighting prey preference, which offers a more utilitarian approach to quantifying energy flow in complex ecosystems.

TL;DR: The formal characteristics of a colour pattern of complex appearance on a molluscan shell were studied by developing a computer program which produces an acceptable simulation of it, and it is shown that the formal rules of the program can be given a plausible physiological interpretation.

TL;DR: It is proved that this automata-theoretical model investigated for the development of filamentous organisms is capable of simulating any given Turing machine and is general enough to realize any effective procedure.

TL;DR: The stability properties and conditions for which sustained oscillations are possible for a non-linear feedback system of this type are mapped and a necessary condition for sustained concentration oscillations resulting from small perturbations of the steady state is derived from a closure rule.

TL;DR: It seems probable that Rhizobium was originally a free-living soil organism with the ability to produce nitrogenase, and this enzyme was the source of the nodular nitrogen enzyme, and the two partners became dependent on their symbiosis for the production of nitrogenase.