Showing papers by "University of Queensland published in 1982"
TL;DR: In this article, a series of experiments were carried out with great care to produce accurate, comparable results in which the relatively small changes in the flow past a circular cylinder associated with varying blockage ratios can be clearly distinguished.
Abstract: Results are presented of a series of experiments which were carried out with great care to produce accurate, comparable results in which the relatively small changes in the flow past a circular cylinder associated with varying blockage ratios can be clearly distinguished. The experiments cover a range of blockage from 2 to 16% and of aspect ratios from 4 to 10. End plates were fitted to the cylinders in all experiments. For blockage ratios less than 6y0, it is shown that the effects of blockage on pressure distribution and the drag coefficient arc small and that the Strouhal number is unaffected by blockage. For blockage ratios in the range 6-lSyo, there is considerable distortion of the flow due to blockage and the effects are complex. The pressure distribution is of a different form and the Strouhal number changes.However, conflicting influences result in a blocked drag coefficient which is not verydifferent from that at no blockage. Reduction in aspect ratio has effects on dragcoefficient and on base pressure coefficient which are similar to those associated with increase in blockage ratio.It is concluded that blockage correction procedures based on the momentum method and on the image method are unsatisfactory in their prediction of the unblocked drag coefficient but the momentum method predicts the unblocked base pressure coefficient quite well.
369 citations
TL;DR: In this article, an extended review of Giroux's work is presented, with a focus on the cultural politics of education and the process of schooling in the United States, and an extended version of Giroux's essay is presented.
Abstract: (1982). IDEOLOGY, CULTURE AND THE PROCESS OF SCHOOLING: AN EXTENDED REVIEW OF HENRY GIROUX. Discourse: Studies in the Cultural Politics of Education: Vol. 3, No. 1, pp. 66-78.
369 citations
TL;DR: An understanding of the role of carbon dioxide, and particularly of its inhibitory effects on enzyme action and membrane function, is required if the observed global inhibition of yeasts and other fermentation systems is to be partitioned to its appropriate causes.
315 citations
TL;DR: In this paper, several popular hypotheses about what, precisely, is wrong with schizophrenic speech and language have been evaluated, ranging from assertions that schizophrenics have peculiar word association hierarchies to the notion that schizophrenia is suffering from an intermittent form of aphasia.
Abstract: Among the many peculiarities of schizophrenics perhaps the most obvious is their tendency to say odd things. Indeed, for most clinicians, the hallmark of schizophrenia is “thought disorder” (which is usually defined tautologically as incoherent speech). Decades of clinical observations, experimental research, and linguistic analyses have produced many hypotheses about what, precisely, is wrong with schizophrenic speech and language. These hypotheses range from assertions that schizophrenics have peculiar word association hierarchies to the notion that schizophrenics are suffering from an intermittent form of aphasia. In this article, several popular hypotheses (and the observations on which they are based) are critically assessed. Work in the area turns out to be flawed by errors in experimental method, faulty observations, tautological reasoning, and theoretical models that ignore the complexities of both speech and language. This does not mean that schizophrenics are indistinguishable from nonschizophrenics. They are clearly deviant in many situations. Their problem, however, appears to be in processing information and in selective attention, not in language itself.
210 citations
TL;DR: Hamster spermatozoa that enter the ampulla appear to be ready to undergo the acrosome reaction, and complete it while they are passing through the cumulus or shortly before, or after, contacting the surface of the zona pellucida.
Abstract: Little is known about the timing of the mammalian sperm acrosome reaction during fertilization in vivo. To study this problem, female hamsters were inseminated at about the time of ovulation, and the contents of the ampullary regions of their oviducts were subsequently examined at various intervals. No living spermatozoa were recovered from ampullae earlier than 4 hr after insemination. The first appearance of living spermatozoa coincided closely with the first appearance of fertilized eggs in the same oviduct. The total numbers of living spermatozoa did not start to exceed the number of eggs in the same ampulla, until after 50% or more of the eggs had been fertilized. Hamster spermatozoa are highly efficient at making contact with eggs, and the fertilizing spermatozoon probably spends no more than 2½ –5½ min in penetrating the cumulus oophorus. Spermatozoa that enter the ampulla appear to be ready to undergo the acrosome reaction, and complete it while they are passing through the cumulus or shortly before, or after, contacting the surface of the zona pellucida.
176 citations
TL;DR: The cognitive development of children whose mothers had been included in the first Auckland trials of betamethasone therapy in premature labor were studied and Calculations of statistical power showed that important differences were unlikely to have been missed.
Abstract: The cognitive development of children whose mothers had been included in the first Auckland trials of betamethasone therapy in premature labor were studied. An earlier study of these children used psychometric tests during the fifth year of life. In the present study tests were given during the seventh year of life (the second year of school) to 250 (82.2%) of 304 surviving children. Of the 250 children, 139 were in the group whose mothers had received betamethasone and 111 were in the control group. Further tests of cognitive development were made, together with assessment of the children9s progress in school. Again, on the majority of measures there were no significant differences between children whose mothers had received betamethasone and the children in the control group. Calculations of statistical power showed that important differences were unlikely to have been missed.
173 citations
TL;DR: It is established that helpers-contribute significantly to their indirect fitness by controlling for variables that are potentially correlated with both reproductive success and unit size.
Abstract: Experimental removal of helpers from a communal bird population decreased the reproductive success of the reduced units. By controlling for variables that are potentially correlated with both reproductive success and unit size, this experiment establishes that helpers-contribute significantly to their indirect fitness.
172 citations
TL;DR: Diet composition changes little with size of crab although within broad taxonomic groups e.g. the Gastropoda, prey species change with sizeOf crab, diet did not vary seasonally for juvenile P. pelagicus in intertidal areas.
148 citations
137 citations
TL;DR: In this paper, an exploratory synthesis of primordial and mobilizationist approaches to ethnic phenomena is presented, with a focus on the identification of the root causes of ethnic phenomena and their evolution.
Abstract: (1982). An exploratory synthesis of primordial and mobilizationist approaches to ethnic phenomena. Ethnic and Racial Studies: Vol. 5, No. 4, pp. 395-420.
135 citations
TL;DR: It is shown that the problem is log space complete for deterministic polynomial time, so the maximum flow problem probably has no algorithm which needs only O(logk n) storage space for any constant k.
01 Jan 1982
TL;DR: Increased knowledge of tick feeding behavior and sensory physiology should aid in the development of lures—compounds and strategies that interfere with normal feeding—to restrain pest ticks from damaging human interests.
Abstract: Publisher Summary This chapter discusses the sensory basis of tick feeding behavior. It discusses tick behavior, sensory structure, and electrophysiology. Feeding is a vital part of the life of all ticks; it is the cause of the damage they do to their hosts, and the means by which disease organisms are transmitted. Interference with proper feeding may be a possible strategy for tick control, and ticks may be particularly accessible to control methods during their feeding phase. Once engaged, ticks use their tarsal and palpal receptors to explore the stimuli that emanate from host predilection sites. Work on the ultrastructure and electrophysiology of tick sensory receptors has reached the stage where specific information on the response characteristics of individual neurons is required. There is an urgent need to pinpoint the neurons that respond to shadows, visual images, infrared, sound vibrations, touch, movement, tastes, odors, and temperature changes. Increased knowledge of tick feeding behavior and sensory physiology should aid in the development of lures—compounds and strategies that interfere with normal feeding—to restrain pest ticks from damaging human interests.
TL;DR: In this article, information seeking in south-east Queensland aboriginal society is studied, where information seeking is based on the notion of "you gotta know how to talk". But the authors focus on the information seeking process.
Abstract: (1982). You Gotta know how to talk …: Information seeking in south‐east Queensland aboriginal society. Australian Journal of Linguistics: Vol. 2, No. 1, pp. 61-82.
TL;DR: Hyperactivation is a capacitation‐associated phenomenon that has now been reported for one or more species from seven orders of eutherian mammals and may well be a universal aspect of the prefertilization behavior of mammalian spermatozoa and is probably of advantage to the fertilizing spermatozoon within the oviduct.
Abstract: The contents of the oviducts of ewes were recovered by flushing with small volumes of culture medium, 22½–24¼ hr after mating. The ampulla was flushed separately from the uterotubal junction and isthmus. Among the motile spermatozoa recovered, a proportion exhibited “hyperactivated” motility, also known as “activated”, or “whiplash” motility. This was characterized by increased flexion of the neck, increased amplitude of the flagellar waves, and marked asymmetry of beat. Two types of hyperactivation appeared: in the first, spermatozoa swam in a repetitive, nonprogressive circling pattern and appeared to have intact acrosome caps; in the second, the spermatozoa showed a propensity to stick to glass by the equatorial segment and most had modified or missing acrosome caps. The proportions of motile spermatozoa exhibiting hyperactivation were greatest in the ampullae, as were the proportions with modified or absent acrosomes. Hyperactivation is a capacitation‐associated phenomenon that has now been reported for one or more species from seven orders of eutherian mammals. It may well be a universal aspect of the prefertilization behavior of mammalian spermatozoa and is probably of advantage to the fertilizing spermatozoon within the oviduct.
TL;DR: It is demonstrated that the recording of uterine electromyograms provides a precise and sensitive method for the study of the early changes that lead to labor and delivery.
TL;DR: In this paper, the effects of two parent training procedures in programming for generalization of parent and child behaviors to extra training settings were examined, and the results showed that the parent training resulted in generalized changes in parent behavior in both training and nontraining settings.
TL;DR: This paper examines the optimal burn-In time to achieve a trade-off between the reduction in the warranty cost and the increase in the manufacturing cost (as burn-in can be viewed as a part of the manufacturing process).
Abstract: For products with an initially high failure rate, burn-in can be used to reduce the warranty cost. This paper examines the optimal burn-in time to achieve a trade-off between the reduction in the warranty cost and the increase in the manufacturing cost (as burn-in can be viewed as a part of the manufacturing process). Conditions for burn-in to be beneficial are derived for various warranty policies. A numerical example is presented.
TL;DR: In this paper, the development of peck orders in mixed sex groups of domestic chickens was observed to determine how linearity occurred, based on threats, head-pecks and submission, dominance relationships emerged in a virtual peck right form.
TL;DR: In this article, the known relationship of speed, gait and body size (derived mainly from mammals) was used to determine the gaits and theoretical maximum speeds of dinosaurs. But the relationship was not extended to include the body size of the animals, and it was concluded that smaller bipedal dinosaurs were capable of running at speeds up to 35 or 40 km/h.
TL;DR: Differences in bacterial populations in sediments from the surface aerobic layer and the anaerobic zone were highly significant and support predictions of these proportions made from muramic acid measurements and direct counting with fluorescence microscopy.
Abstract: Bacteria in sediments from the surface aerobic layer (0-1 cm) and a deeper anaerobic layer (20-21 cm) of a seagrass bed were examined in section by transmission electron microscopy. Bacteria with a Gram-negative ultrastructure made up 90% of bacteria in the surface layer, and Gram-positive bacteria comprised 10%. In the anaerobic zone, Gram-negative bacteria comprised 70% and Gram-positive bacteria 30% of the bacterial population. These differences were highly significant and support predictions of these proportions made from muramic acid measurements and direct counting with fluorescence microscopy. Most cells were enveloped in extracellular slime layers or envelopes, some with considerable structural complexity. The trophic value to animals of these envelopes is discussed. A unique organism with spines was observed.
TL;DR: Production of the pregnancy-specific protein early pregnancy factor (EPF) was monitored by the rosette inhibition test in a group of 13 nulliparous women and a high incidence of early embryonic loss is suggested.
01 Jan 1982
TL;DR: The presented review will demonstrate that the enzyme phosphofructokinase plays no role in the mechanism of the Pasteur effect and that there exists no glucose repression on biomass formation in bacteria under aerobic conditions.
Abstract: In the past 10 years there have been rapid developments in the elucidation of the mechanisms of the Pasteur (or oxygen) and the Crabtree (or glucose repression of the respiratory chain) Effects in bacterial systems, which convincingly exhibit the difference between the regulatory mechanisms in yeast and bacteria. The presented review will demonstrate that the enzyme phosphofructokinase plays no role in the mechanism of the Pasteur effect and that there exists no glucose repression on biomass formation in bacteria under aerobic conditions. Endproduct formation is caused aerobically and anaerobically by an oversupply of NADHP2, whereas biomass correlates to energy supply. This development indicates very strongly that the mechanism of the Pasteur effect may be reflected solely in the change of glucose uptake rates and must therefore be sought at the cell membrane. In regard to the Crabtree Effect, the question arises whether there exists such a mechanism in bacteria. The variability of the bacterial electron transport systems, the lack of cytochrome a as terminal oxidase together with bioenergetic investigations indicate that the Crabtree effect may give cause for an alteration but not for a cessation of respiratory activity.
TL;DR: This study reviews the negative patient stereotypes reported by 2421 Victorian and Michigan (U.S.A.) doctors and finds the characteristics of patients so stereotyped to be remarkably consistent.
TL;DR: In this article, a method of analysis for the consilidation of a linear elastic soil due to the cutting of a long and deep circular tunnel is presented, where solutions have been obtained for the time dependent displacements and stress changes occurring in the soil surrounding the tunnel opening.
TL;DR: In this article, a Rayleigh distillation model was used to model trace element abundance patterns in the Tertiary volcanic province of S. Queensland. But the results of the analysis showed that only the Minerva Hills trachytic lavas and a Glass House comendite, have not been modified by assimilation processes.
Abstract: The magmas of the Tertiary volcanic province of S. Queensland are chemically bimodal, and occur in numerous volcanic centres, at least three representing original shield volcanoes. The mafic lavas are dominantly hawaiites and tholeiitic andesites, whereas the silicic magmas comprise mainly trachytes, rhyolites, and comendites.The silicic rocks exhibit variable trace element abundance patterns. There is a progressive depletion of Sr, Ba, V, Mg, Ni, Cr, Mn, and P, through the trachytes to the rhyolites and comendites while the behaviour of Zr, Nb, LREE, Y and Zn is very variable. Rb, Th, and to a lesser extent Pb exhibit a more regular behaviour, becoming most generally concentrated in the comendites and rhyolites. These trace element patterns are modelled by application of the Rayleigh distillation model, using partition coefficients based on analysed phenocrysts from the S. Queensland silicic lavas. Trace mineral phases, namely zircon, chevkinite, and allanite, are shown to be important in the probable control of LREE, Zr, and Th abundances, while Nb and Zn are probably controlled during fractionation by magnetite. Trace element data for the hawaiites and tholeiitic andesites also indicate extensive although variable levels of fractional crystallization of these magmas.The Sr and O isotopic compositions of the mafic lavas, trachytes, comendites and rhyolites are as follows: initial 87Sr/86Sr ratios; 0.70357-0.70456, 0.70432-0.70589, 0.70495-0.70917, and 0.70708-0.70863 respectively. δ18O range between 5.6-7.0 (mafic lavas), 4.9-8.7 (trachytes), 5.0-7.6 (comendites) and 8.1-10.4 per mil (rhyolites). Pb isotopic compositions are variable, showing a variation of 6.7 per cent for 206Pb/204Pb ratios through the range of volcanic compositions. The rhyolites exhibit a much greater divergence in their O, Sr, and Pb isotopic compositions compared with those of associated mafic lavas, than is found in the trachytes and comendites. Within the silicic volcanics, positive correlations exist between δ18O and initial Sr ratios, and between Pb isotopic compositions and initial Sr ratios (with one group of trachytes providing a noteworthy exception). These correlations are not so clearly defined for the mafic lavas, although these do exhibit positive correlations between differentiation index, δ18O, and initial Sr isotope ratios.The development of the silicic magmas, excepting two groups, is interpreted in terms of a model in which assimilation and fractional crystallization occur concurrently, involving a basalt or hawaiite magma component and a crustal component (modelled on the analysed Carboniferous basement greywackes outeropping in the region); the data indicate, however, that differentiation continued in isotopically closed systems (i. e. isolated from the wallrocks). The highly depleted Sr and Ba abundances of the rhyolites and comendites suggest that contamination did not occur after differentiation had ceased. The rhyolites have the highest isotopic input of the crustal components and are interpreted as crustal anatectic melts, produced locally within the crust in response to basalt/hawaiite magma intrusion, whereas most of the trachytes and comendites are interpreted as primarily the differentiated products from original mafic parental magmas, with variable assimilation of crustal wallrock components. The isotopic data suggest that only the Minerva Hills trachytic lavas, and a Glass House comendite, have not been significantly modified by wallrock assimilation processes. The erpted mafic magmas were also evidently modified by isotopic crustal wallrock interactions, which independent petrological data suggest has occurred at intermediate to lower crustal depths.
TL;DR: In the presence of avidin, progress curves for the pyruvate carboxylase reaction show a marked decrease in the rate of reaction over a period of several minutes, in agreement with a model in which there is slow equilibration between free enzyme and the enzyme-avidin complex.
Abstract: In the presence of avidin, progress curves for the pyruvate carboxylase (EC 6.4.1.1) reaction show a marked decrease in the rate of reaction over a period of several minutes. These curves are quantitatively described by an equation in which the rate of catalysis by the enzyme undergoes a firstorder decay from a high initial velocity to a final velocity which is close to zero. The initial velocity of the reaction is independent of avidin concentration while the decay constant increases linearly with increasing concentrations of avidin. These findings are in agreement with a model in which there is slow equilibration between free enzyme and the enzyme-avidin complex. Alternative models involving slow isomerization of the free enzyme or of an enzyme-avidin complex are not consistent with the data. From the slope of the decay constant vs. avidin concentration plot, the rate constant for formation of the enzyme-avidin complex was calculated to be (1.42 ± 0.09) X 105 M-1 s-1 for the enzyme isolated from chicken liver. The intercept of this plot, which is equal to the rate constant for dissociation of the enzyme-avidin complex, was not well-defined by the data but was estimated to be less than 2 X 10-3 s-1. In view of this uncertainty, an alternative procedure was used to obtain a more reliable value. This procedure involved following the regeneration of enzymic activity upon incubation of the enzyme-avidin complex with biotin and yielded a value of (1.45 ± 0.13) X 10-5 s-1 for the dissociation rate constant. The enzyme-avidin complex undergoes a reaction which renders the inhibition of the enzyme irreversible and which occurs at a rate that is 5 times greater than the rate of dissociation of the avidin from the enzyme. This observation accounts for the widely held view that avidin inhibition is irreversible.
01 Jan 1982
TL;DR: ADP and AMP show differential effects, whereas all other above mentioned compounds do not inhibit, and regulatory mechanisms for sucrose, glucose and fructose metabolism are discussed.
Abstract: Glucokinase (EC 2.7.1.2) exhibits two pH optima (pH 7.0 and 8.2), gives hyperbolic saturation curves and reacts equally with ATP, UTP, GTP, ITP and CTP. Inhibition occurs with high concentrations of these nucleotides and in addition with ADP, AMP and glucose 6-phosphate. No inhibition was observed with sucrose, glucose, fructose (11 mM), ethanol (542 mM), mannose, ribose, galactose, deoxy-glucose, lactose and gluconate and no reaction except with glucose.
TL;DR: It may be unnecessary to invoke differential hemispheric specialisation in order to account for visual lateral asymmetries and verbal ability differences in laterality may not reflect neuroanatomical differences but merely cognitive capacity.
Abstract: The notion that visual laterality patterns may be attributable to attentional allocation rather than hemispheric specialisation was examined in three experiments. In Experiment I, high verbal ability subjects were found to be less lateralised on a letter name match task than low verbals. In Experiment II, stimulus probability was shown to affect laterality patterns for name but not for physical matches. Again, low verbals were affected more than highs. Experiment III produced results identical to those of Experiment II although, in the latter experiment, visual fields were defined vertically rather than horizontally from the midline. Together, these results support the following generalisations: (1) visual asymmetries have their locus in a post-perceptual information processing stage; (2) visual asymmetries may be altered by manipulating stimulus probability; (3) verbal ability differences in laterality may not reflect neuroanatomical differences but merely cognitive capacity and (4) it may be unnecessary...