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In the era of scientific management and increasing rigor in the social sciences, there has been wide appeal in the idea that a simple geometric model could provide predictive and prescriptive information on the growth and design of social and economic organizations. And in the recent years that have seen the development of organic and open system theories of organizational behavior, the idea of biological geometries and related biological notions such as "homeostatic equilibrium" have been increasingly used by the social scientists to construct their models. The new behavioral scientists and organizational theorists have been particularly attracted to this course by the chance to legitimize their activity since it leads readily to quantification. Increasingly, attempts are being made to find empirical data which will support analogies to phenomena well established in the biological sciences. In the rush to become quantitative--and thus scientific--leaps of fancy have been taken to explain data generated from all kinds of economic, social, and political organizations. In this paper, the writer reappraises some attempts to fit empirical data derived from organizational statistics to biological and geometric models. The purpose is not so much to compare one analogy with another, as it is to suggest there is a lack of evidence for these biological or geometric analogies. [ABSTRACT FROM AUTHOR]

It is suggested that a useful component of a fertility simulation would be proportions of females sterile by age. Data on this phenomenon are rather limited, but they indicate that proportional sterility may not easily be described by a simple function. We propose that rates of becoming sterile may be adequately described by an exponential function utilizing proper parameter values. Such exponential-model rates form the basis for computation of a fecundity decrement table presented in this paper. Sterility proportions from the table are compared to some empirical data. [ABSTRACT FROM AUTHOR]

The duration of time between two successive births or between marriage and first birth is an indicator of the level of fertility of a couple. Potter and Parker (1964) and Singh (1961, 1967) have suggested the Type I Geometric as a distribution appropriate Or representing the length of interval to first conception leading to a live birth. Potter and Parker estimated the parameters of this distribution with the help of the first two moments. Majumdar and Sheps (1970) pointed out the limitations of these moment estimates and gave a method to Obtain maximum likelihood estimates, based on formulas which are too involved for solution without the help of a computer. Singh proposed a continuous probability distribution based on another set of assumptions for the above situation. He outlined a method to obtain best asymptotically normal estimates of the parameters. These estimates are obtained after several iterations starting from any set of consistent estimates. The objective of this paper is to show that it is relatively easier to obtain maximum likelihood estimates of the parameters of the continuous model, which describes the data on duration to first conception as well as does the discrete model. Simple expressions for the moment and maximum likelihood estimates with the corresponding covariance matrices are obtained. Application is made to three sets of data. [ABSTRACT FROM AUTHOR]

The partition of alkali cations and anions between an aqueous and an immiscible organic phase has been studied in the absence and presence of neutral and carboxylic ionophores of the valinomycin and nigericin types, respectively. Cation extraction into the organic phase was augmented considerably by the ionophores, and a cation specificity of K≧Rb>Cs≫Na was found for all the neutral ionophores tested. Evidence is given that the actual values of ion specificity are a function of the solvent polarity, especially for valinomycin where an inversion of the K/Rb specificity was observed. The ionophores examined have the following rank order of effectiveness for K extraction into a standard organic phase consisting of 70% toluene-30% n-butanol: valinomycin>18-crown-6≫trinactin>enniatin B≈dinactin>monactin>nonactin. The ion affinity and selectivity data thus obtained have been compared with data previously reported. In a toluene-butanol solvent, extraction of cations in the absence of ionophores occurs as ion pairs. On the other hand, the neutral ionophores extract the cations by the mechanism of complexation, with the lipophilic anions coextracted as free gegenionic species at lower ionophore complex concentrations. When the concentration of extracted cations exceeds 1×10 m, ion pairing between the ionophore complex and the anion occurs, and this tendency increases with increasing concentration and decreasing polarity of the organic phase. Anion pairing with the complexed cations is much less than for the free cations and this effect appears to be due to the larger distance of closest approach of the anion for the complexed cation. [ABSTRACT FROM AUTHOR]

The turnover numbers of the ionophores valinomycin, the macrolide actins, enniatin B and dicyclohexyl 18-crown-6 for translocation of cations through the mitochondrial membrane have been compared quantitatively. The rank order of decreasing maximum turnover number for K transport calculated on the basis of the ionophore concentration within the membrane is trinactin>dinactin∼monactin∼ valinomycin>nonactin>18-crown-6>enniatin B. The strength of binding of the ionophores to the mitochondria has the following rank order: valinomycin>macrolide actins>enniatin B>18-crown-6. A rough proportionality was observed between the transport rate of K, Rb, Cs or Na with a given ionophore and the heterogeneous complexation constant of the corresponding ionophore-cation pair in two-phase extraction experiments. However, the proportionality constants between transport and the heterogeneous complexation constant differ between the ionophores. These comparisons indicate that valinomycin and enniatin B transport cations about 10 times slower than would be expected from their two-phase complexation behavior, using the complexation and transport reactions of the macrolide actins as a basis for comparison. Transport with 18-crown-6 was about 1,000 times slower than predicted. These observations are discussed in terms of partitioning of the ionophores between various regions of the mitochondrial membrane. The data are discussed in terms of a carrier model involving hydrophilic complexes on the membrane surface in addition to hydrophobic complexes which cross the membrane. [ABSTRACT FROM AUTHOR]

The present studies demonstrate that extracellular cations alter ouabain binding by intact human erythrocytes and that this alteration reflects a change in the apparent affinity but not the capacity for ouabain binding. Monovalent cations exert their effect at a single site (the 'monovalent cation site') and each monovalent cation can inhibit competitively the effect of other monovalent cations. Sodium, lithium, and cesium increase while potassium and rubidium decrease the apparent affinity with which ouabain is bound. Divalent cations exert their effect at a single site (the 'divalent cation site') which is functionally distinct from the site at which monovalent cations act and show mutual competitive inhibition. Each divalent cation studied increases the apparent affinity with which oubain binds to the erythrocyte membrane. Magnesium and calcium, but not barium, can also alter the effect of monovalent cations on ouabain binding. To interpret our findings we have proposed that the erythrocyte membrane has a 'receptor complex' composed of a monovalent cation site, a divalent cation site and a glycoside-binding site. The number and type of cations occupying the cation sites determine the affinity of the glycoside-binding site for ouabain. [ABSTRACT FROM AUTHOR]

The operation of a seven-compartment model is described with respect to flows of Na within and across this system, simulating published results obtained on frog skin. The seven compartments represent: one outside and one inside solution compartment; the subcorneal space; the first reacting cell layer (1. RCL); the remaining cell compartment; the non-, or slowly exchangeable Na compartment; the extracellular space. Assuming reasonable volumes for the epidermal compartments and further chosing, by trial and error, appropriate rate constants, a set of seven simultaneous linear differential equations was solved by the application of the Continuous System Modeling Program (CSMP), using an IBM 1130 computer. Initial conditions for influx, backflux and net flux were taken which correspond to [Na]; [Na]=115 mm. Print-out data were obtained at 0.5-min intervals for 30 min, when steady states were obtained in 13 models studied, varying certain k's thus simulating actions of chemical agents (hormones; drugs). Simulation was achieved with regard to rate of influx, backflux and net flux, steady-state time (30 min), and electrical potentials. In addition, this approach gave detailed information on Na pool sizes and their variations with changes in k's. These results are compared to published data on frog skin and good agreement between operation of skin epidermis and model was found. [ABSTRACT FROM AUTHOR]

Cortical blood flow and epidural intracranial pressure have been measured in the two supratentorial compartments of the intracranial space in experimental baboons during the acute expansion of a parieto-occipital epidural balloon. Differential pressures between the two halves of the supratentorial space have been found, and these have been associated with evidence that flow has fallen more quickly in the hemisphere most compressed. The evidence points to a more rapid exhaustion of the autoregulatory capacity in the hemisphere subjected to greater compression, a fall in perfusion pressure to below critical autoregulatory levels occurring slightly before that in the opposite hemisphere, and the establishment of a differential flow pattern for a short time during a critical phase of compression. The displacements induced by inflation of the parieto-occipital balloon have been described. [ABSTRACT FROM AUTHOR]

A technique of block surface-staining and serial cinematography was modified to review serial sections of normal and dystrophic muscle from the Bar Harbor 129 Re strain of mice as a preliminary study of fibre splitting in dystrophic muscle. Using this technique, muscle fibres were reconstructed for up to 1·5 mm of their length without difficulty. Split fibres were identified only when the actual separation of fibres was observed. Splitting was seen to be a significant cause of the variations in fibre diameter and was at times responsible for the formation of groups of small atrophic fibres which resembled those seen in denervation atrophy. Complex multiple splitting and recombination of daughter and parent fibres was also observed and reconstructed to scale. These results may have considerable significance for the interpretation of physiological data on both human and murine dystrophic muscle. [ABSTRACT FROM AUTHOR]

The article presents a human research model used to study factors affecting the prevention and production of gingivitis. A study is discussed which attempted to produce gingivitis using only dental plaque. Techniques used to assess the teeth and gingival tissues of test subjects prior to experimentation are reviewed.

The article evaluates the nutritional and dietary factors that modify animal dental caries. The author suggests that research done with animal models to study the caries potential of human foods may not be entirely accurate, since it can often misrepresent the factors involved. These factors include microorganisms and dietary needs.

Since the lethal factors in most bacterial infections have not been defined, the role of metabolic alterations was investigated. Bacteremia was produced in rabbits by infection with Diplococcus pneumoniae, and the animals were grouped by severity of the disease as determined by progressive increments in the level of bacteremia, concentration of lactate in whole blood, and change in body temperature. Adenosine triphosphate and adenosine diphosphate in blood, liver, heart, and skeletal muscle were normal. Hepatic glycogen was variably decreased, and 45% of the animals were hypoglycemic despite normal hepatic glucogenesis. Concentrations of lactate in heart and liver increased. In-vitro oxidation of glucose, acetate, and pyruvate decreased in liver only. Glycolysis was normal in liver, heart, and muscle, but it was markedly increased in the lung. Hepatic synthesis of the triglyceride from acetate increased markedly. Hepatic microsomal protein synthesis apparently was normal, but amino acids in plasma, liver and skeletal muscle were increased. Complex multifaceted alterations in metabolism occurred. It is doubtful that anyone of these could be responsible for death, but the role played by these changes as a whole is unknown. [ABSTRACT FROM PUBLISHER]

Examines the central thesis in John Dewey's social philosophy. Application of the methods of science to social problems; Difference between the logic of scientific experimentation and social action; Consequence of Dewey's reliance on a biological model.

Conduction velocity of autonomic unmyelinated fibres has been measured in the cervical sympathetic trunk of normal rats, and in rats intoxicated by acrylamide or by isoniazid. The mean maximal conduction velocity in nerves from normal rats is 2·0 m/sec. There is no significant reduction in velocity of the unmyelinated fibres in nerves from intoxicated rats, although histological studies of the sural nerve confirmed severe degeneration of myelinated fibres in the same animals. It is shown that the amplitude of the compound nerve action potential is proportional to the resistance between the recording electrodes. If this is taken into account, there is no reduction in the amplitude of the monophasic action potential of unmyelinated fibres recorded from the cervical sympathetic trunk of intoxicated rats. The amplitude of the A component of the sural nerve compound action potential is markedly reduced in rats intoxicated by acrylamide or by isoniazid, but there is no significant reduction in the amplitude of the C component in the same nerve. It is concluded that in the rat an insignificant number of unmyelinated fibres of autonomic or dorsal root origin are affected in the neuropathy produced by acrylamide or isoniazid. The relevance of these findings to human neuropathies is discussed. [ABSTRACT FROM AUTHOR]

Electrophysiological studies were performed on frog and guinea-pig peripheral nerves to determine the effect of temperature on conduction at the site of pressure and demyelinating lesions. An increased susceptibility to thermally-induced conduction blockade has been demonstrated. In pressure-injured frog and guinea-pig nerves, conduction blocks occur at temperatures approximately 6°C lower than in normal nerves. A similar phenomenon occurs in guinea-pig demyelinated nerve (experimental allergic neuritis) and in some cases at temperatures around 15°C lower than in controls. It is suggested that these effects are the result of a critical lowering by temperature of an already markedly depressed conduction safety factor. In support of this, it has been shown that calcium ion depletion, which would be expected to increase the conduction safety factor by lowering the threshold for excitation, counteracts the increased thermal sensitivity of frog pressure-injured nerve. These findings are discussed in relation to well-known temperature effects in multiple sclerosis. They add support to an earlier proposed hypothesis that the changes in signs and symptoms with a change of body temperature in multiple sclerosis may be caused by an effect of temperature on axonal conduction. [ABSTRACT FROM AUTHOR]