Showing papers by "University of Queensland published in 1977"
TL;DR: In this article, a thermal model with thermodynamic principles and relevant equations of state is tabulated, consistent as far as possible with the parameterised earth model of Dziewonski et al. and with thermodynamics principles.
303 citations
TL;DR: In this article, a complete overlap of major and trace element chemistry (including TiO2) was observed between the Kermadec-TVZ tholeiites and basaltic andesites, and the ocean floor tholeite of the Lau Basin.
246 citations
TL;DR: The results of this investigation suggest that the early pregnancy factor may be necessary for the continued viability of the early embryo.
208 citations
TL;DR: Measurements of the inelastic light scattering (Brillouin) spectra of collagen from rat rail tendon are described from which elastic moduli of the tropocollagen molecule are obtained and an estimate of hydrogen bond force constants are reported.
Abstract: BIOLOGICAL fibres make a suitable subject for the development of the science of biomaterials. The amino-acid sequence of the collagen molecule is known1,2, and has been used to account for the self-assembly of collagen into native fibrils1 and polymorphic forms3, the pattern of bands due to positive staining in electron micrographs4 and the low-angle meridional X-ray diffraction pattern5. The collagen structure to amino acid resolution in axial projection is thus completely understood. Here we relate this structural picture to the mechanical properties (and since we are dealing with a biological fibre, these are also the biological properties) of the fibres. This can be done by investigating the vibrational and other motions of the molecular assembly in collagen. The force constants of hydrogen bonds in some polypeptides have been estimated on the basis of models6 but no experimental measure of their magnitude has been reported. We describe measurements of the inelastic light scattering (Brillouin) spectra of collagen from rat rail tendon from which we obtain elastic moduli of the tropocollagen molecule and an estimate of hydrogen bond force constants. We have also studied effects of hydration on the spectra to obtain information about the association of water with collagen in the native state. For comparison we have made preliminary measurements on molluscan ‘catch’ muscle in which the polypeptide conformation is different from collagen.
205 citations
TL;DR: Comparison with scarcer populations in more structurally complex woodland, where the species is less able to eliminate others, suggests that the advantage gained by the interspecific aggression pertains to food resources, because the species forages more in a wider range of feeding zones in areas where possible competitors have been ousted.
Abstract: Dow, D. D. 1977. Indiscriminate interspecific aggression leading to almost sole occupancy of space by a single species of bird. Emu 77: 115–121.Noisy Miners Manorina melanocephala, Australian honey...
143 citations
TL;DR: In this paper, the phenomenon of size spreading of a narrow crystal-size distribution due to fluctuations in growth velocity was modeled using an effective numb and growth diffusivities of the order of 100μm2/min were calculated for sugar crystals grown from pure syrups and result in typical growth Peclet num.
130 citations
TL;DR: In this article, a strong correlation was obtained between bruise volume and energy absorbed for both impact and slow compression of Granny Smith apples, and it was shown that energy absorbed during compression is a good predictor of bruising and is a useful parameter in evaluating handling and packing systems.
Abstract: A strong correlation was obtained between bruise volume and energy absorbed for both impact and slow compression of Granny Smith apples. Apple tissue was more easily bruised by slow compression than by impact. For the same amount of energy, bruise volumes were approximately 40% higher under slow compression.
There was no correlation between the stiffness (force/deflection) of apple flesh and bruise volume. It is unlikely that the theories of failure based on the theory of elasticity will prove useful in predicting the extent of bruising. The application of elastic theory to bruise initiation was not studied in this paper.
A simple model was formulated to explain the behaviour of apples under compression. Apple tissue was likened to an orderly arrangement of liquid-filled, spherical cells bounded by viscoelastic membranes with air-filled interstitials. It is postulated that on initial compression the cells are deformed into ellipsoids under a stress distribution similar to that found in an elastic sphere. Further compression would then result in cell wall fracture, i.e., cell bursting in regions of high shearing stress. Distortion and bursting of cells explains the energy dissipative mechanism.
The work showed that energy absorbed during compression is a good predictor of bruising and is, thus, a useful parameter in evaluating handling and packing systems.
129 citations
TL;DR: In this paper, the authors used observations of cloud to cloud ground lightning flashes in thunderstorms to obtain empirical relationships between this ratio (z), latitude (λ), and annual thunder-days (T).
Abstract: Observations of the ratio of cloud to cloud-ground lightning flashes in thunderstorms have been reviewed, and used to obtain empirical relationships between this ratio (z), latitude (λ) and annual thunder-days (T). The 29 observations, covering a latitude range 69°N to 37°S, gave a mean value of z of 3.35. The empirical relationship proposed between z and λ is z(λ) = 4.16 + 2.16 cos3λ, 0 ≤ λ ≤ 60°. From 26 pairs of values of z and T, covering the range 5 to 81 thunderdays per year, the proposed relationship is z(T) = 1.0 + 0.063T, 10 ≤ T ≤ 84 z = 6.3, T > 84. Information on z for high latitudes is sparse. It is probable that z lies between 1 and 2 for λ > 60° and T < 10. The existence of a relationship between z and T is attributed to the fact that both are related to latitude. The relationship between z and λ probably depends on the variation of freezing level height with latitude, and a possible relationship between z and freezing level height is examined. Where both λ and T are known, the prop...
127 citations
TL;DR: It is concluded that the production of neurogenic oedema involves both sensory nerves and mast cells in rats.
Abstract: Concentration-related dye leakage produced by intracutaneous injections of irritants was measured in rats by an Evans blue technique. 2 In rats pretreated with a total dose of 50 mg capasaicin over 4 days, the response to capsaicin, formalin, HCl, KCl, prostaglandin E1, bradykinin and bradykinin with prostglandin E1 (10(-6) M) were greatly reduced, the responses to histamine and 5-hydroxytryptamine were slightly reduced and those to adenosine 5'-triphosphate (ATP) and compound 48/80 were unaffected. 3 Pretreatment with intracutaneous injections of compound 48/80 (0.5 mug, 24 and 48 h previously) recuded the responses to ATP, compound 48/80, HCl, KCl, prostaglandin E1, and bradykinin but did not affect those to histamine, 5-hydroxytryptamine or bradykinin with prostaglandin E1 (10(-6) M). 4 Responses to capsaicin and formalin produced spotted blueing extending over a large area and were suppressed by compound 48/80 in the smaller pretreated area only. Capsaicin responses were reduced with larger doses of compound 48/80 (total dose 15 mug). 5 It is concluded that the production of neurogenic oedema involves both sensory nerves and mast cells.
116 citations
TL;DR: The activity produced by intra‐arterial bradykinin and prostaglandin E1 was investigated in multifibre strands dissected from the saphenous nerves of anaesthetized rats.
Abstract: 1The activity produced by intra‐arterial bradykinin and prostaglandin E was investigated in multifibre strands dissected from the saphenous nerves of anaesthetized rats. 2Bradykinin (0.5‐10 μg) alone produced little activity in nerve strands but produced considerable activity following a 10 min infusion, but not a single injection, of prostaglandin E (5‐100 ng). 3Prostaglandin E alone produced a few large height spikes but following several injections of bradykinin smaller height spikes were also produced by prostaglandin E. 4It was concluded that the presence of a low concentration of prostaglandin E is required for bradykinin to manifest its action and that bradykinin and prostaglandin E are mutually potentiating in their effects on afferent nerve terminals. 1977 British Pharmacological Society
106 citations
TL;DR: In this article, the results suggest metabolic involvement in the uptake and long distance transport of solenium supplied as selenite, despite lower Se concentrations in the xylem exudate than in the external solution.
Abstract: Selenate and selenite transport through tomato root systems were followed for periods up to 4 h after removal of the plant tops, using Se as a tracer.With selenate, Se concentrations in the xylem exudate were 6 to 13 times higher than in the external solution, and chromatographic analysis showed that the selenium was transported as inorganic selenate (SeO42-).With selenite, Se concentrations in the exudate were always lower than in the external solution. Analyses of exudate samples showed that negligible amounts of selenium were transported as inorganic selenite (HSeO3-except at very high external selenite concentrations (500 μM), when up to 7 per cent was transported as selenite. Most of the selenium transport in selenite-fed plants was as selenate or as an unknown selenium compound, the relative proportions of these two forms varying both with time and with external selenite concentration. Addition of a 5-fold excess of sulphate over selenite had no detectable effect on the concentrations of selenate in the exudate, but caused substantial decreases in the maximum concentrations of both total selenium (c. 47 per cent decrease) and the unknown selenium compound (c. 69 per cent decrease). Addition of a 5-fold excess of sulphite decreased the concentration of the unknown (c. 39 per cent) but caused a large (2.7-fold) increase in the maximum total selenium concentration in the exudate and a 7.9-fold increase in the maximum concentration of selenate. The results suggest metabolic involvement in the uptake and long distance transport of solenium supplied as selenite, despite lower Se concentrations in the xylem exudate than in the external solution. An attempt is made to incorporate the new and existing information into a selenium transport model.
01 Jan 1977
TL;DR: A survey of thermodynamic relationships between materials within the Earth can be found in this article, with a focus on some recent developments which have direct bearing on the thermal and mechanical states of the Earth's mantle and core.
Abstract: New fundamental thermodynamic relationships of complete generality and absolute rigour of derivation are not to be expected, because the subject has such a secure and complete basis in classical physics. There is, however, still scope for original, fundamental work based on recognised assumptions and approximations which may be obviously acceptable in particular situations. Clarification of relationships between thermodynamic parameters for materials within the Earth is particularly important because there is so little possibility of measuring them individually. This survey first summarises the established relationships in a very condensed form and then concentrates on some recent developments which have direct bearing on the thermal and mechanical states of the Earth's mantle and core. Considerable use is made of the thermodynamic Gruneisen parameter, which is a dimensionless quantity of order unity for almost all materials, solid, liquid and gaseous, and is directly related to the pressure dependences of elastic constants. This allows its value to be estimated for the different regions of the Earth from seismological data. The thermodynamic (heat engine) efficiency of convection in a homogeneous medium, driving tectonic activity or the geomagnetic dynamo, is found to be the ideal (Carnot) efficiency corresponding to adiabatic temperature differences between the heat source and sink, within the assumption that the thermal expansion coefficient is not strongly temperature dependent. The use of this conclusion to infer tectonic stresses is indicated. The thermodynamic basis for Lindemann's melting law is restated and the reasons for supposing it to be valid for materials at megabar pressures reaffirmed. Application to the inner core boundary gives a ‘fixed point’ on the Earth's temperature profile. Use of thermodynamic relationships in the interpretation of shock wave compressions is indicated.
TL;DR: A survey of 123 species of fishes from southeastern Queensland during 1975 revealed in 47 species nine distinct larval types of ascaridoid nematodes: Anisakis Type I, Terranova Types I and II, Contracaecum types I and I, and Thynnascaris Types I, II, III and IV.
TL;DR: In this article, the authors used elliptical hysteresis loops in basalt and granite samples subjected to sinusoidal strains of order 10−6 and this is strong evidence that attenuation does become a linear phenomenon at low strain amplitudes.
Abstract: LINEAR theories of attenuation of acoustic or seismic waves in media, such as rocks, which are characterised by constant or nearly constant Q factors (fractional energy loss per cycle equals 2π/Q) imply velocity dispersion and, therefore, frequency dependence of elasticity The effect is small, corresponding to a change of order 1 % over the period range of seismological interest (1 s to 1 h), and is consequently difficult to observe However, it leads to an internal inconsistency in the development of earth models by inversion of free oscillation data and to discrepancies between these models and body wave data1–3 It is a matter of considerable geophysical interest to resolve the problem Validity of the linearity assumption has been questioned4 but we are now observing elliptical hysteresis loops in basalt and granite samples subjected to sinusoidal strains of order 10−6 and this is strong evidence that attenuation does become a linear phenomenon at low strain amplitudes But whether or not perfect linearity applies, a direct demonstration of body wave dispersion is the most satisfying indication that earth model studies need revision
TL;DR: The findings from an investigation to evaluate the intra-family dynamics that occurred with 111 cases of childhood drowning and near-drowning in the City of Brisbane in 1971-1975 found that parents volunteered the information that they drank more, experienced sleep disorders and nightmares, and reported significant anxiety states.
Abstract: This study reports the findings from an investigation to evaluate the intra-family dynamics that occurred with 111 cases of childhood drowning and near-drowning in the City of Brisbane in 1971-1975...
TL;DR: Using segregation and transfer analyses, it is demonstrated that a plasmid or plasmids is involved in 2,4-D degradation, indicating that bacteria have evolved which can degrade many different pesticides and may have an important role in this evolution.
Abstract: ACCORDING to the UN Food and Agricultural Organisation production year book of 1974, 27×106 kg of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) were consumed in 1973, making this the most extensively used of all pesticides. One desirable characteristic of 2,4-D, apart from its efficacy as a herbicide, is its lack of persistence in the environment1, due to degradation by a variety of microorganisms. We have argued that in view of the isolation of plasmids encoding the degradation of naturally occurring aliphatic and aromatic compounds2, there exists a class of plasmids which specifically encode the degradation of many man-made derivatives of these compounds, in this instance 2,4-D. Using segregation and transfer analyses we have demonstrated that a plasmid or plasmids is involved in 2,4-D degradation. Clearly bacteria have evolved which can degrade many different pesticides; our results indicate that plasmids may have an important role in this evolution.
TL;DR: It has been established that, in the presence of constant drug doses, plasma levels of phenytoin, phenobarbitone and certain other anticonvulsants tend to fall during pregnancy and rise again during the puerperium.
Abstract: During pregnancy a number of continuously changing circumstances exist which might be expected to modify the relation between plasma drug levels and drug dosage. Alimentary tract motility may be decreased, the distribution of many drugs may be altered, glomerular filtration rale is greater and biotransformation capacity may be changed as pregnancy advances. However, relatively little has been published on the monitoring of plasma drug levels during pregnancy.
TL;DR: The pattern of tooth plate formation in the Queensland lungfish is consistent with illustrations published by Semon and Greil but the inferred developmental processes are different, and the results for the Zahnreihe hypothesis of Edmund and for the phylogeny of Dipnoi are discussed.
TL;DR: Phytohemagglutinin stimulated human lymphocytes exhibit a 20 fold increase in DNA repair synthesis following ionizing radiation damage compared to the level of repair in unstimulated cells.
Abstract: Phytohemagglutinin stimulated human lymphocytes exhibit a 20 fold increase in DNA repair synthesis following ionizing radiation damage compared to the level of repair in unstimulated cells. The peak of repair synthesis coincides with that for DNA replication. Stimulated lymphocytes provide a relatively simple assay for ionizing radiation repair defects.
TL;DR: This article describes the problem of implementation of moni to r -based systems and discusses some (inadequate) solutions; its aim is to solicit better solutions from workers in the field.
Abstract: The concept o f a moni tor has been developed by }bare [1] and Brincb-Hansen [2, 3, 4] i n to a powerful and u se fu l too l for b u i l d i n g w e l l s t r u c t u r e d and r e l i a b l e ope ra t ing systems. Some expe r i ence of the author in c o n s t r u c t i n g moni to r -based systems [5, 6] has h i g h ] i g h t e d a problem of implementa t ion which does not seem to have been e x p l i c i t l y addressed in the literature. This article describes the problem mld discusses some (inadequate) solutions; its aim is to solicit better solutions from workers in the field.
TL;DR: Increased iron stores were reflected in increased serum-ferritin concentrations in subjects as young as 14 years in whom the liver-iron concentration was twice the normal upper limit and before there was any evidence of architectural damage to the liver.
TL;DR: A model for changes in energy balance and body weight is described which can be written as an iterative computer program and it is suggested that the differences in response which have been observed in over-eating experiments result from inter-individual differences in this ratio.
Abstract: SummaryA model for changes in energy balance and body weight is described which can be written as an iterative computer program. Medium and long-term changes in body weight resulting from random daily fluctuations in energy balance are quantitatively predicted. Body weight varies periodically about a mean value to to the extent of ± 1 kg over a span of a few weeks. Long-term weight stabilization is the result of a dynamic equilibrium between energy intake and output which depends on activity and tissue metabolism. A lean : fat tissue deposition ratio defines the metabolic type of individual. This ratio, which is constant for each individual, governs the proportions in which these tissues are both deposited and mobilized. In the model, the ratio has an important effect on the magnitude and composition of the weight gains resulting from over-eating. It is suggested that the differences in response which have been observed in over-eating experiments result from inter-individual differences in this ratio.
TL;DR: Increasing the tempo of “drownproofing” and of teaching children to swim will help, but the expected reduction in deaths and near‐deaths from this strategy alone cannot yet be assessed.
Abstract: The data from the Brisban Drowning Study have been analysed in this article to provide guidelines for preventive strategies. The separate causal links comprising the drowning chain have been identified, and quantitative scores have been assigned to the three identifiable groups of causative factors--environmental, parent-related and victim-related. The identifiable causes of child drowning are absence of a safety barrier or fence around the water hazard, non-supervision of a child, a parental "vulnerable period", an inadequate safety barrier, and tempting objects in or on the water. Effective environmental control can be achieved only through legislation. The complementary role of a public educational thrust in discussed. Increasing the tempo of "drownproofing* and of teaching children to swim will help, but the expected reduction in deaths and near-deaths from this strategy alone cannot yet be assessed. Compulsory first aid training for pool owners is required. Costs of implementing a total drowning preventive programme are presented.
TL;DR: In this paper, experimental observations on the Al-Al3Ti and Cd-Cd3Ag peritectic systems are discussed in relation to transformation rates, and an approximate diffusion analysis permits prediction of the rate of growth of the per-itectic envelope by diffusion through the envelope.
TL;DR: In this article, the linear discriminant function (LDF) is estimated using all n 1 + n 2 + M observations under the assumption that M is small relative to n 1 and n 2.
Abstract: Estimation of the linear discriminant function L is considered in the case where there are n 1 and n 2 observations from the populations II1 and II2 and M unclassified observations. Estimates of L using all n 1 + n 2 + M observations are proposed and evaluated in terms of the expected error rate under the assumption that M is small relative to n 1 and n 2. By appropriately weighting the sample means of the unclassified observations, an estimate of L is given which dominates the usual estimate based on just the n 1 + n 2 classified observations.
TL;DR: This paper found that profit and dividend changes were positively correlated, and were associated with significant share price changes, after abstracting from market effects, when profit and revenue reports gave conflicting signals, share prices tended to decline.
Abstract: Australian companies typically announce profit figures and dividend payouts at the same time. During the 60's and early 70's, profit and dividend changes were positively correlated, and were associated with significant share price changes, after abstracting from market effects. When profit and dividend reports gave conflicting signals, share prices tended to decline.
TL;DR: The selection of N. dubius for increased infectivity in Q mice enhanced its immunogenicity in this and other mouse strains possibly because of increased genetic homogenicityIn the selected populations.
TL;DR: In this paper, the controllability of discrete-time linear systems with positive control is studied and necessary and sufficient conditions are given to test this property for a single-input system.
Abstract: In this paper we study the controllability of discrete-time linear systems with positive controls. Necessary and sufficient conditions are given to test this property for a single-input system.