Showing papers by "University of North Carolina at Chapel Hill published in 1969"
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01 Dec 1969TL;DR: The concepts of power analysis are discussed in this paper, where Chi-square Tests for Goodness of Fit and Contingency Tables, t-Test for Means, and Sign Test are used.
Abstract: Contents: Prefaces. The Concepts of Power Analysis. The t-Test for Means. The Significance of a Product Moment rs (subscript s). Differences Between Correlation Coefficients. The Test That a Proportion is .50 and the Sign Test. Differences Between Proportions. Chi-Square Tests for Goodness of Fit and Contingency Tables. The Analysis of Variance and Covariance. Multiple Regression and Correlation Analysis. Set Correlation and Multivariate Methods. Some Issues in Power Analysis. Computational Procedures.
115,069 citations
334 citations
TL;DR: In this article, it is conjectured that the Petersen graph does not have a Tait coloring, and the conjecture is shown to be equivalent to a combinatorial assertion involving cyclically ordered arrays of n objects each belonging to one of three distinguishable classes.
246 citations
TL;DR: A fixation procedure for electron microscopy is described which includes a simultaneous glutaraldehyde-OsO4 fixation followed by postosmication which was found to have considerable advantages in preserving structures of plant and animal cells.
Abstract: A fixation procedure for electron microscopy is described which includes a simultaneous glutaraldehyde-OsO4 fixation followed by postosmication. This procedure was found to have considerable advantages in preserving structures of plant and animal cells.
233 citations
TL;DR: Evidence was provided that the basis for the spontaneous EMG bursts may be related to somatic responses elsewhere in the body, such as postural adjustments, and to be directly correlated with reaction time.
Abstract: Four experiments are reported, all of which are concerned with evaluating in human Ss the relationship between the deceleration of heart rate, observed to anticipate both aversive and non-aversive stimuli, and several aspects of somatic-motor activity. In a simple reaction time task, a decrease in spontaneous bursts of EMG activity and both respiration amplitude and frequency were found to be concomitant with the deceleration of heart rate during the foreperiod and to be directly correlated with reaction time. The decrease in anticipatory somatic activity to an aversive stimulus was found in a second experiment to extend to spontaneous eye movements and blinks, which also had a marked concomitance with the anticipatory deceleration of heart rate. However, experimentally imposed somatic activity, i.e. continuous finger tapping, increased in intensity around the time the UCS was expected. A third experiment provided additional evidence that the anticipatory cardiac deceleration to aversive stimuli was not mediated significantly by respiratory maneuvers. Finally, evidence was provided that the basis for the spontaneous EMG bursts may be related to somatic responses elsewhere in the body, such as postural adjustments.
193 citations
TL;DR: Decalcification at the mantle-shell interface in Mercenaria tnercenaria was studied through the changes in the chemical composition of the extrapallial fluid, and by the measurement of Ca45-deposition and solution, indicating that succinic acid produced by the anaerobic metabolism of the clam was neutralized by the dissolution of previously deposited shell.
Abstract: Decalcification at the mantle-shell interface in Mercenaria tnercenaria was studied through the changes in the chemical composition of the extrapallial fluid, and by the measurement of Ca45-deposition and solution. Measurements of O2-tension demonstrated that the clam was anaerobic soon after the valves were closed. Measurements of calcium, carbon dioxide, and hydrogen ion concentration showed that all of these components of the extrapallial fluid increase with increasing time of closure. These measurements, and measurements of calcium and succinic acid in the tissues and fluids of the clam, indicated thatsuccinic acid produced by the anaerobic metabolism of the clam was neutralized by the dissolution of previously deposited shell.
171 citations
TL;DR: In this paper, it was shown that surface diffusion plays an essential role in the growth process and that the observed shapes of spirals and habits of crystals described in terms of the morphological theory of Hartman and Perdok can be explained on the basis of the surface diffusion model of Burton, Cabrera and Frank.
151 citations
TL;DR: Variability in response locus decreased to a low value during training in which each response produced reinforcement, and increased when fixed intervals, variable intervals, random intervals, or extinction were scheduled.
Abstract: The effect of several reinforcement schedules on the variability in topography of a pigeon's key-peck response was determined. The measure of topography was the location of a key peck within a 10-in. wide by 0.75-in. high response key. Food reinforcement was presented from a magazine located below the center of the response key. Variability in response locus decreased to a low value during training in which each response produced reinforcement. Variability increased when fixed intervals, variable intervals, random intervals, or extinction were scheduled.
148 citations
TL;DR: In this article, the Born cross sections for ionization by proton impact of K- and L-shells and of individual L-subshells in atoms are presented for a wide range of proton energies above a few tenths of an MeV.
137 citations
TL;DR: In this paper, subjects were tested in groups of nine for the presence of the positively valued trait of intellectual flexibility (Pos conditions) or the negatively valued traits of intellectual rigidity (Neg conditions), and the subjects were either told the approximate range of the group's test scores (R conditions), or they were not told the range (NR conditions).
134 citations
TL;DR: The observation that virulent M. pneumoniae produced tissue damage more effectively than did an attenuated strain suggest that this experimental model may be useful for the analysis of factors contributing to organism pathogenicity.
Abstract: SummaryThe applicability of organ culture systems to the study of mycoplasma infections is illustrated by the experiments described. Tracheal organ culture provided a controllable environment for analysis of the interaction between M. pneumoniae and the natural target cell of this pathogen, the ciliated respiratory epithelium. Mycoplasma pneumoniae produced distinct cytopathology in this system that was not seen with other human mycoplasmas tested. In addition, virulent M. pneumoniae produced tissue damage more effectively than did an attenuated strain. The observations suggest that this experimental model may be useful for the analysis of factors contributing to organism pathogenicity.
TL;DR: The derivation of infectious avirulent strains may make possible their use as live vaccines against M. pneumoniae disease and enables understanding of one stage in the pathogenic sequence and provides a convenient marker for avirulence.
Abstract: Homologous pairs of virulent and attenuated or avirulent Mycoplasma pneumoniae strains were derived and compared in an effort to elucidate the mechanisms of virulence. These related strains were found to vary in growth, glycolysis, protein electrophoretic patterns, peroxide formation, morphology, and cytadsorption. Variations in the last two characteristics closely correlated with avirulence. This enables understanding of one stage in the pathogenic sequence and provides a convenient marker for avirulence. The derivation of infectious avirulent strains may make possible their use as live vaccines against M. pneumoniae disease.
TL;DR: In this article, an alternative pathway for five-coordinate complexes to undergo oxidative additions is through prior dissociation of a ligand to form a more reactive fourcoordinate complex.
Abstract: Publisher Summary The rapid development of organo-transition-metal chemistry over the past decade has been dominated by considerations of bonding and structure. The reactions of such organo-metallic compounds have been discussed to a lesser extent and usually in the context of a particular metal or ligand. The apparent parallel between oxidative addition of covalent molecules to unsaturated d complexes and chemisorption of these molecules to the latent valences on transition metal surfaces may be significant. Several organic reactions that are homogeneously catalyzed by unsaturated d8 complexes involve oxidative addition FS a key step in the mechanism. An alternative pathway for five-coordinate complexes to undergo oxidative additions is through prior dissociation of a ligand to form a more reactive four-coordinate complex. Labilization of a ligand may be brought about by heating or irradiating a five-coordinate complex. The tendency for d complexes to undergo oxidative additions depends markedly on the nature of the central metal ion and the ligands attached to it.
TL;DR: In this article, the use of a changeover delay between crossover eye movements and reinforcement had the effect of changing the pattern of scanning from fixating four dials in succession or in a Z-shaped pattern to scanning vertically the dials on either side with fewer crossovers.
Abstract: Human macrosaccadic eye movements to two areas of a four-dial display were conditioned by concurrent variable-interval schedules of signals. Reinforcers (signals) were delivered to the two right-hand dials on one schedule and to the two left-hand dials on another, independent schedule. The use of a changeover delay between crossover eye movements and reinforcement had the effect of changing the pattern of scanning from fixating four dials in succession or in a Z-shaped pattern to scanning vertically the dials on either side with fewer crossovers. In the presence of a changeover delay, subjects matched relative eye-movement rates and relative reinforcement rates on each schedule. Rate of crossover eye movements, with a changeover delay in effect, was also inversely related to the difference in reinforcements arranged by the concurrent schedules. The results suggest that for stimuli whose critical components are arranged spatially, conditioned eye movements play an important part in selective stimulus control.
TL;DR: The conclusion is that those mitochondria that do not undergo change in ultrastructure have impairment of electron transport, and that those that do become orthodox have increased membrane lability and undergo degeneration.
Abstract: Mitochondria isolated from kidneys of lead-intoxicated rats have been shown to have decreased oxidative and phosphorylative abilities. The purpose of this study was to determine whether these abnormal mitochondria would undergo ultrastructural transformation during controlled respiration in the absence of phosphate acceptor (State IV), as previously demonstrated for normal liver mitochondria. It was first shown that normal rat kidney mitochondria transforms from a condensed ultrastructural conformation to an orthodox conformation after 5 min of State IV respiration with pyruvate-malate substrate. Reversal to a condensed conformation follows stimulation of respiration with adenosine diphosphate (ADP). A large portion of kidney mitochondria from lead-poisoned rats do not change from condensed to orthodox conformation during State IV respiration. Other mitochondria do transform to the orthodox form but they rapidly degenerate. State IV respiration decreases as these few orthodox mitochondria disintegrate. The conclusion is that those mitochondria that do not undergo change in ultrastructure have impairment of electron transport, and that those that do become orthodox have increased membrane lability and undergo degeneration.
TL;DR: Comparison of cytadsorptive activity and peroxide formation by measurement of hemadsorption and hemolysis revealed variations between heterologous strains, but no differences consistently related to virulence.
Abstract: SummaryA study of the relationship between virulence, peroxide formation, and cytadsorption in M. pneumoniae was undertaken. Two pairs of homologous virulent and attenuated strains were derived by passage of parent strains in animals and artificial media. Comparison of their cytadsorptive activity and peroxide formation by measurement of hemadsorption and hemolysis revealed variations between heterologous strains, but no differences consistently related to virulence. The existence of additional mediators of virulence is suggested.
TL;DR: In this paper, a queueing system consisting of two queues, each with single servers (independent negative exponential service time distributions) and correlated bivariate Poisson input, is discussed, and the joint stationary probabilities for the respective numbers of customers in the two queues in equilibrium are found in the case where we have finite waiting rooms of different sizes for each individual queue.
Abstract: SUMMARY A queueing system consisting of two queues, each with single servers (independent negative exponential service time distributions) and correlated bivariate Poisson input, is discussed. Thejoint stationary probabilities for the respective numbers of customers in the two queues in equilibrium are found in the case where we have finite waiting rooms of different sizes for each individual queue. For the model where the waiting-room capacities are unlimited, we derive a functional relationship for the joint probability generating function of the equilibrium probabilities. A survey of published research on queues in parallel is also presented.
TL;DR: The rank over GF(p) of the incidence matrix of points and hyperplanes in the finite projective geometry PG(t, pn) is shown to be equal to p 6 ⩾ 2 + p 3 2 − p 5 2 − ∑ j = 7 n p i as discussed by the authors.
TL;DR: The importance of these findings for bacterial taxonomy and for a more complete understanding of the regulation of pyrimidine biosynthesis as it occurs in bacteria, fungi, plants, and animals is briefly considered.
TL;DR: In this article, the statistical analysis of completely randomized split-plot experiments is discussed from the point of view of the underlying multivariate model, where the data matrix has the appearance of a set of mixed models, each one of which corresponds to a particular treatment.
Abstract: The statistical analysis of completely randomized “split-plot” experiments is discussed from the point of view of the underlying multivariate model. In doing this, first certain well-known aspects of the parametric case are reviewed; however, attention is primarily directed toward the development of appropriate non-parametric procedures. The general structure of “split-plot” experiments involves N randomly chosen subjects to whom treatments have been assigned according to a completely randomized design and from each of whom is obtained an observation vector, the components of which represent the responses of the subject to each one of several conditions. Hence, the data matrix has the appearance of a set of mixed models, each one of which corresponds to a particular treatment. The different conditions correspond to the “split plot” treatments in agricultural experiments while the different treatments correspond to the “whole plot” treatments. Alternatively, such designs may be interpreted simply ...
TL;DR: Some fungi, chiefly host specific ones, have a limited distribution, while omnivorous species are found in mangroves throughout the tropics and sub-tropics, most mangrove fungi are warm water species.
Abstract: Lists of all marine and terrestrial fungi described from mangrove plants are compiled and relations between these fungi and mangrove forest plants ( Avicennia, Hibiscus, Pluchea, Rhizophora ) are described. Marine ascomycetes, basidiomycetes and deuteromycetes occur on submerged parts of roots (proproots, pneumatophores), stems and branches. Six of thirty-one species appear to be host specific. Most frequent marine species are Lulworthia sp., Metasphaeria australiensis and ‘ Phoma ’ sp. The majority of the forty-four terrestrial fungi described from mangrove trees are parasites on living leaves. High contents of tannin do not protect mangrove plants from decomposition by marine fungi and wood boring animals (shipworms and isopods). Submerged bark and wood of mangroves are deteriorated by higher marine fungi. Wood destruction is of the ‘soft rot’ type. Fewer kinds of fungi occur on bark than on wood; Mycosphaerella pneumatophorae (in Avicennia ) and Keissleriella blepharospora (in Rhizophora ) are exclusively corticolous. Some fungi develop within calcareous layers of shipworm tubes in mangrove roots or branches. Rhizophora forms adventitious roots above injured and fungus-infested root tips. There is a zonation of fungi and other organisms along vertical roots, stems, or branches of mangrove trees. Submerged parts are inhabited by marine fungi, algae, balanids, worms, shipworms, and gribbles. Several species of fungi are usually found together on the submerged part of one root, but no distinct pattern of vertical distribution among the species is evident. Growth of marine and terrestrial fungi overlaps at the high tide line. Organisms above the water include ascomycetes, deuteromycetes, basidiomycetes, and lichens. Horizontal distribution of fungi in a Hawaiian mangrove swamp along a transect from salt to fresh water is described. Marine fungi are absent in the freshwater part. Thus, host specific K. blepharospora occurs only on Rhizophora plants in salt water. Dispersal and geographical distribution of mangrove fungi are discussed. Knowledge of occurrence of marine fungi in the eastern mangrove is almost absent. Some fungi, chiefly host specific ones, have a limited distribution, while omnivorous species are found in mangroves throughout the tropics and sub-tropics. Most mangrove fungi are warm water species.
TL;DR: Key-pressing responses in the cat were maintained under conditions in which brief electric shock was first postponed by responses, then periodically presented independently of responses, and finally produced by responses on a fixed-interval schedule of 15 min (FI 15-min).
Abstract: Key-pressing responses in the cat were maintained under conditions in which brief electric shock was first postponed by responses (avoidance), then periodically presented independently of responses, and finally produced by responses on a fixed-interval schedule of 15 min (FI 15-min). A steady rate of responding occurred under shock avoidance and under response-independent shock; positively accelerated responding was engendered by the FI 15-min schedule. A second experiment studied responding under second-order schedules composed of three FI 5-min components. Responding was suppressed when a stimulus was presented briefly at completion of each FI 5-min component and a shock followed the brief stimulus at completion of the third component. Responding was maintained when each of the first two components was completed either with or without presentation of a brief stimulus and a shock alone was presented at completion of the third FI 5-min component.
TL;DR: A calcium salt given by stomach tube in modest amounts produced hypercalcemia in acutely thyroidectomized fasted rats, whereas in rats with intact thyroid glands the same dose of calcium had little or no detectable effect, presumably because of release of thyrocalcitonin.
Abstract: A calcium salt given by stomach tube in modest amounts, such as might be ingested in a normal meal, produced hypercalcemia in acutely thyroidectomized fasted rats, whereas in rats with intact thyroid glands the same dose of calcium had little or no detectable effect, presumably because of release of thyrocalcitonin. Thyrocalcitonin apparently protects against hypercalcemia during feeding after deprivation.
TL;DR: The cationic, antibacterial proteins of polymorphonuclear leukocytes are associated with a unique subcellular particle that is separable through zonal density gradient centrifugation from acidosphatase-containing particles as well as from particles that contain alkaline phosphatase and lysozyme.
Abstract: The cationic, antibacterial proteins of polymorphonuclear leukocytes are associated with a unique subcellular particle that is separable through zonal density gradient centrifugation from acid phosphatase-containing particles as well as from particles that contain alkaline phosphatase and lysozyme. Normal macrophages, macrophages stimulated by bacillus Calmette-Guerin, and liver cells lack this particle and the associated group of cationic proteins. Particles physically and biochemically similar to slower sedimenting enzyme-rich particles of polymorphonuclear leukocytes are shared by all the tlhree cell types.