Showing papers by "University of Western Australia published in 1990"
TL;DR: To examine the hypothesis that sleep apnoea is a risk factor for ischaemic heart disease, overnight polysomnography was performed in 101 unselected male survivors of acute myocardial infarction aged less than 66 yr and in 53 male subjects of similar age without evidence of ischaemia heart disease.
946 citations
TL;DR: 3- and 4-year-old children do understand that looking leads to knowing, and that their difficulty in the Wimmer et al. study was mainly with the form of the question that they were asked.
Abstract: 3 experiments were conducted to investigate the claim made by Wimmer, Hogrefe, and Perner that 3-4-year-old children do not understand that people gain knowledge about something by looking at it. The first experiment involved a simple forced-choice procedure in which children had to judge which of 2 assistants knew what was inside a box when one of the assistants had looked inside and the other had lifted it up. In this experiment, the children did realize that the assistant who had looked in the box knew its contents. The second experiment followed the Wimmer et al. procedure, but with a simpler question form. The children were just asked to state whether someone knew what was in the box. Again, the children were able to work out that a person who had looked in a box knew what was inside it. In the third experiment, a direct comparison was made between the simpler question and the more complex, double-barreled question asked by Wimmer et al. The children found the more complex question considerably harder. The results of these experiments suggest that, in contrast to the claims made by Wimmer et al., 3- and 4-year-old children do understand that looking leads to knowing, and that their difficulty in the Wimmer et al. study was mainly with the form of the question that they were asked.
391 citations
TL;DR: The genetic basis of the control of acute splenic MCMV infection was studied after intraperitoneal inoculation of the virus and an autosomal dominant non-H-2 gene that regulates splenic virus replication was identified.
Abstract: The genetic basis of the control of acute splenic MCMV infection was studied after intraperitoneal inoculation of the virus. Classical Mendelian analyses using C57BL/6 (resistant) and BALB/c (susceptible) parental strains disclosed an autosomal dominant non-H-2 gene that regulates splenic virus replication. The probable location of this gene, to which we have assigned the symbol Cmv-1, is on chromosome 6 as defined by the strain distribution pattern of splenic MCMV replication in CXB recombinant inbred mice. Although there is a similar hierarchy of resistance to MCMV and HSV-1 with respect to the C57BL and BALB genetic backgrounds, the strain distribution pattern of HSV-1 replication in recombinant inbred mice suggests that Cmv-1 is not involved in restricting the spread of this virus. This is the first clear identification of a non-H-2 gene regulating the magnitude of MCMV infection. Elucidation of the function of this gene may be a fundamental step towards understanding the control of systemic CMV infection.
315 citations
TL;DR: In this paper, the authors evaluated organizational performance as a function of perceived self-efficacy, task complexity, assigned and self-set goals, and analytic strategies in managerial decision-making in a stimulated organization.
298 citations
TL;DR: Diversity of CF rate-intensity functions has functional implications for both frequency and intensity coding at high sound pressures in the mammalian auditory system.
277 citations
Journal Article•
TL;DR: The mechanism of injury and the signs and symptoms associated with initial injury to the anterior cruciate ligament were investigated in 23 subjects and it showed that 70% of subjects had injured their anterior cruiser ligament at footstrike during noncontact situations.
Abstract: The mechanism of injury and the signs and symptoms associated with initial injury to the anterior cruciate ligament were investigated in 23 subjects. The subjects had injured only their anterior cruciate ligament with no other clinically definable laxity to other major ligamentous structures. The results showed that 70% of subjects had injured their anterior cruciate ligament at footstrike during noncontact situations. In 53% of these subjects the mechanism of injury was internal rotation of the tibia with the knee in slight flexion. A shifting sensation occurring between the tibia and femur was noted by 61% of subjects, while 30% recalled a crack or popping sound at the time of injury. Only 17% of subjects could continue in sports activity immediately following the injury, all with difficulty.
276 citations
TL;DR: Comparison of rate-intensity functions at characteristic frequency and at a tail-frequency show that the rate- intensity functions are identical at low firing rates and that the sloping-saturation and straight types deviate from the standard function only at higher firing rates.
230 citations
TL;DR: In this article, the formation of horizontal temperature gradients in the surface waters of a sidearm of a small water supply reservoir at a time during summer when radiative heating and vertical stratification of the reservoir waters were both quite strong.
Abstract: We present observations of the diurnal formation of horizontal temperature gradients in the surface waters of a sidearm of a small water supply reservoir at a time during summer when radiative heating and vertical stratification of the reservoir’s waters were both quite strong. Our measurements show that because the closed end of the sidearm was relatively shallow, daytime heating and nighttime cooling created larger temperature changes there than in the body of the lake, resulting in large horizontal temperature gradients that drove strongly sheared, horizontal exchanges. Because of more vigorous turbulent mixing during cooling, cooling-driven flows were slower and of greater vertical extent than were heating-driven flows. The overall flow exhibited inertia in that it was not in phase with the daily heating cycle. Averaged over the daily cycle, there appeared to be a net residual flow, with surface waters flowing out and metalimnetic waters flowing in. This thermally driven flow, the “thermal siphon,” greatly enhanced the rate of horizontal exchange between the sidearm and the body of the reservoir such that the time required to replace water in the sidearm when the siphon is operating is substantially less than estimates with conventional formulae based on horizontal turbulent diffusion.
220 citations
TL;DR: The uptake of transferrin and iron by the brain, liver and femurs was investigated in rats using 125I-59Fe-transferrin (Tf), and 131I-albumin, indicating that the changes in the brain were specific for that organ.
216 citations
TL;DR: The relationship between root extension and transport of O2 from shoots to roots via the gas spaces was examined and it was found that Oxygen transport to roots grown continuously in acrated solutions was considerably less than for roots raised in stagnant solutions; this difference was greater for seminal than for nodal roots.
Abstract: The present paper describes the effects of growth of roots of wheat (Triticum aestivum cv. Gamenya) in hypoxic nutrient solutions on acrenchyma formation and O2 movement from shoots to roots. Two types of roots were investigated: (1) seminal roots of 4–7-d-old seedlings, and (2) seminal and nodal roots of 10–28-d-old plants. Gas-filled porosity of seminal and nodal roots increased from 3 to 12% and from 5–7 to 11–15%, respectively, when the roots emerged in stagnant or N2-flushed solutions (0.003 mol m −3 O2) compared with growth in continuously acrated solutions (0.26 mol m −3 O2). However, neither root type increased in porosity when they were longer than 100–200 mm at the start of the exposure to these stagnant or N2-flushed treatments. A vernier microscope and cylindrical platinum-electrode were used to examine the relationship between root extension and transport of O2 from shoots to roots via the gas spaces. Measurements were made when the roots were in an anoxic medium and were dependent solely on O2 supplied from the shoots. For seminal roots of 5–7-d-old seedlings raised in stagnant solutions (90–100 mm), internal O2 transport was sufficient to support a rate of root elongation in the O2-free medium of between 0.03 and 0.17 mm h−1. When the O2 pressure around the shoots was increased from 20 to 100 kPa O2, the O2 concentrations at the walls of the expanding zone (2–7 mm from the tip) of these roots increased from 0.006 mol m−3 to between 0.04 and 0.26 mol m−3, and the rate of root extension increased five-fold. Oxygen transport to roots grown continuously in acrated solutions was considerably less than for roots raised in stagnant solutions; this difference was greater for seminal than for nodal roots. When the acrated seminal roots were longer than 100 mm and transferred to an O2-free root medium, O2 concentration became zero at the root tip causing elongation to cease. After 24 h of anoxia, none of these roots were able to resume elongation following a return to acrated solutions.
212 citations
TL;DR: The data suggest that spastic cerebral palsy is associated with poor intrauterine growth in infants of more than 33 weeks' gestation, but no important causal mechanism has yet been identified.
TL;DR: Evidence suggests that some drugs, food-derived mutagens and other xenobiotics can be metabolized by gut flora and/or gut wall enzymes to reactive species which may cause tumors.
TL;DR: In this article, the reduction of cupric oxide to pure copper metal by a variety of metallic reducing agents was studied, and the powders were examined by X-ray diffractometry and electron microscopy.
Abstract: The occurrence of simple solid-state displacement reactions during mechanical alloying has been investigated. The reduction of cupric oxide to pure copper metal by a variety of metallic reducing agents was studied, and the powders were examined by X-ray diffractometry and electron microscopy. When milled with a liquid process control agent, the reaction progressed gradually with time, whereas an unstable combustion reaction occurred when no such control agent was employed. A minimum adiabatic temperature of 1300 K is necessary for combustion to occur in these systems. The reaction enthalpy is an important factor in determining the precombustion period. The as-milled powders consisted of finely divided, nanometer-sized crystallites with an extremely high defect density. It is proposed that the increased reactivity of the system arises through the unique conditions prevailing during mechanical alloying.
TL;DR: Two in vitro fertilization sperm preparation protocols using pentoxifylline (long and short exposure before insemination) were studied in 57 couples with male factor infertility and 17 healthy infants have now delivered and pregnancy wastage is not increased.
TL;DR: The role of the transferrin homologue, melanotransferrin, in iron metabolism has been studied using the human melanoma cell line, SK-MEL-28, which expresses this antigen in high concentrations, and a membrane-bound, pronase-sensitive, temperature-dependent, iron-binding component was identified.
TL;DR: The basilar membrane nonlinearity is examined and a semi-quantitative explanation for it in terms of previous models and an analogue model is provided and the shapes of the neural rate-intensity functions are quantified and shown to be consistent with the low-threshold data of Geisler et al. (1985).
TL;DR: In this paper, a comparison of numerical and experimental results for transient two-dimensional natural convection initiated by instantaneously heating and cooling the opposing vertical walls of a square cavity containing a stationary and isothermal fluid is presented.
Abstract: Comparisons of numerical and experimental results for transient two-dimensional natural convection initiated by instantaneously heating and cooling the opposing vertical walls of a square cavity containing a stationary and isothermal fluid are presented. The good comparisons indicate that the simulation is capturing the important features of the flow. Several features are identified and discussed in detail; in particular, the presence of travelling wave instabilities on the vertical-wall boundary layers and horizontal intrusions, the existence of a rapid flow divergence in the region of the outflow of the intrusions, and the presence of cavity-scale oscillations, caused by the interaction of the intrusions with the opposing vertical boundary layer. The utilization of both numerical and experimental investigations has allowed a more complete exploitation of the available resources than would have been possible had each been conducted separately.
TL;DR: A computational algorithm is devised for solving a class of functional inequality constrained optimization problems, based on a penalty function, for which a numerical example is solved.
TL;DR: In this article, the authors investigated factors influencing the development of two-way shape memory behavior in NiTi and found that the magnitude of the twoway memory was dependent on whether the training procedure involves the formation of stress induced martensite or reorientation, the number of training cycles, the training stress and prior heat treatment.
Abstract: Factors influencing the development of two-way shape memory behaviour in NiTi have been investigated. The magnitude of the two-way memory is found to depend on whether the training procedure involves the formation of stress induced martensite or martensite reorientation, the number of training cycles, the training stress and prior heat treatment. The development of optimal two-way shape memory strains is associated with training conditions in which a full one-way transformation strain is achieved under conditions of minimum stress and permanent strain.
TL;DR: A new surgical principle which can safely result in the formation of an artificial neo‐ligament, and induce the adhesion of tissues is described, and was proven by retropubic implantation of Mersilene tapes in female dogs.
Abstract: A new surgical principle which can safely result in the formation of an artificial neo-ligament, and induce the adhesion of tissues is described. Under certain conditions, an implanted Mersilene tape may act as a template, provoking a controlled linear deposition of collagen which remained unchanged, even after removal of the tape. This was proven by retropubic implantation of Mersilene tapes in female dogs, in the position of the pubo-urethral ligament. The procedure relies on the normally negative aspects of wound healing for its effect, such as foreign body reaction, bacterial colonization, and continued tissue breakdown and regeneration.
TL;DR: It is found that the total variance in allelic frequency among three populations separated by approximately 4 km at Rottnest Island, Western Australia is as large as that among five additional samples collected over a distance of 1 300 km along the Western Australian coast.
Abstract: Enzyme polymorphisms in the sea urchinEchinometra mathaei were examined to test the relative influences of population turnover and patchiness in recruitment on genetic heterogeneity. We found that the total variance in allelic frequency among three populations separated by approximately 4 km at Rottnest Island, Western Australia (collected in February 1985) is as large as that among five additional samples collected over a distance of 1 300 km along the Western Australian coast in August 1987. This suggests that the forces causing genetic differentiation act on a local scale and occur in a single generation. A comparison of sites with different histories of recruitment indicates that the observed genetic differences among age groups are the result of prerecruitment effects, and that differences among sites reflect their individual histories of recruitment.
TL;DR: Immunoperoxidase staining of tissue sections for class II major histocompatibility complex Ia antigen reveals a virtually contiguous network of Ia-positive dendritic cells (DC) within the epithelium, which suggests a major role for the intra-epithelial DC in allergic and infectious disease in the respiratory tract.
Abstract: This study utilises a simple technique to section airway epithelium in a plane parallel to the basement membrane, thus providing a unique plan view of the intra-epithelial cell populations. Immunopero
TL;DR: Results of some experiments are reported that show that the positive effects of nutrient donation on female reproduction for one species of spermatophylax producing tettigoniid can be realized within 24 to 48 h.
Abstract: A recent debate has centred on the importance of paternal investment for the origin and maintenance of nuptial feeding in insects. Some authors have argued that the rates of nutrient incorporation are likely to be too slow to allow a male to fertilize the eggs that he helps to produce and cannot be considered as paternal investment. Here I report the results of some experiments that show that the positive effects of nutrient donation on female reproduction for one species of spermatophylax producing tettigoniid can be realized within 24 to 48 h. Furthermore, mating was found to induce a refractory period in the female that was longer than the time taken for the incorporation of nutrients and oviposition. Thus, the nurturant male is likely to fertilize the eggs even if last-male sperm precedence is high. The cost of spermatophylax production was manifest as a 5-day recovery period between matings. Thus males and their donations are likely to be limited resources for females resulting in a reversal of the typical sex roles.
TL;DR: If these models are analogous to human disease, then each clinical entity within this apparently heterogeneous group of clinical posterior uveitis syndromes may represent one aspect of a general organ-specific uveoretinal response to autoantigens.
Abstract: Uveitis is a term which encompasses many clinical syndromes which would appear to be discrete entities. Both clinically and experimentally, the separation of uveitis affecting only the anterior segment from that affecting the posterior segment has a sound pathogenetic basis. However, clear distinctions among the various forms of endogenous posterior uveitis are more difficult to maintain in the light of evidence from experimental models of autoimmune uveitis (EAU). EAU can be induced by a variety of retinal antigens and each antigen has been shown to induce somewhat different forms of EAU, depending on such factors as dose of antigen, species and strains of animal model, and the type(s) of adjuvant used. However, within each model a similar spectrum of uveoretinal responses can be induced by each antigen suggesting that the pathogenetic mechanisms are probably similar also. In addition, if these models are analogous to human disease, then each clinical entity within this apparently heterogeneous group of ...
TL;DR: Evidence that female sexual motivation decreased when environmental resources were plentiful and that only females of low nutritional status continued to mate supports the hypothesis that females continue to mate to compensate for low resource availability and that male parental investment may be important only in poor quality habitats.
Abstract: Male tettigoniids donate nutrients to females at mating in the form of a spermatophylax. Male-donated nutrients function as paternal investment leading to a reversal in the sex roles of males and females. Reversal in the behavioral sex roles of a zaphrochiline tettigoniid was found to be directly related to the current availability of food resources in the environment. When resource availability was low, females were less fecund and males had lower and more variable accessory gland weights (the spermatophylax producing gland) than when resource availability was high. When resources were scarce, larger individuals had a reproductive advantage having more eggs or heavier accessory glands. All individuals were equally fecund or had equal accessory gland weights when resources were plentiful. During low resource availability males that had a spermatophylax to offer were choosy of their mates, and females were competitive. When resources were plentiful, males were less discriminative and females showed signs of discrimination. There was evidence that female sexual motivation decreased when environmental resources were plentiful (as indicated by mating frequency) and that only females of low nutritional status continued to mate. When resources were scarce, females achieved fecundities equivalent to those achieved during high resource availability through spermatophylax consumption. These data support the hypothesis that females continue to mate to compensate for low resource availability and that male parental investment may be important only in poor quality habitats. When resources are plentiful females do not need to remate. Thus resource availability may directly influence the number of sexually active males and females (operational sex ratio) and the form of sexual selection.
TL;DR: In this paper, the authors made use of government-led reductions in the amount of welfare benefits paid to unemployed Australian youths to investigate the possible psychological impact of reduced income during unemployment.
Abstract: Studies investigating the causes of poor psychological health during unemployment have tended to neglect the role played by financial hardship. This study made use of government-led reductions in the amount of welfare benefits paid to unemployed Australian youths to investigate the possible psychological impact of reduced income during unemployment. Samples of 161 and 201 unemployed youths were obtained before and after the changes were made, respectively. Although respondents in the latter sample received less money from welfare benefits, their overall level of income did not differ from that of the first sample. Analyses showed that respondents reported a range of weekly incomes, from a variety of sources. Correlational analyses on the combined samples showed that the subjective level of financial strain experienced, but not the actual amount of income received, was independently associated with psychological well-being. Lower incomes were not associated with a greater commitment to obtaining a job or a lower level of structured time use, though higher levels of financial strain were associated with both. It is suggested that financial strain mediates the effect of low incomes on psychological health, activity levels, and commitment to obtaining employment.
TL;DR: The role of dominant groups in constructing established beliefs and practices, and their own roles in that process and their potential power to reconstruct such beliefs and practice is recognized by subordinate groups as mentioned in this paper.
Abstract: Collective reflection by subordinate groups leads to recognition not only of the roles of dominant groups in constructing established beliefs and practices, but also of their own roles in that process and of their own potential power to reconstruct such beliefs and practices. (Livingstone, 1987, p. 8)
TL;DR: A product form equilibrium distribution is derived for a class of queueing networks in either discrete or continuous time, in which multiple customers arrive simultaneously and batches of customers complete service simultaneously.
Abstract: A product form equilibrium distribution is derived for a class of queueing networks in either discrete or continuous time, in which multiple customers arrive simultaneously and batches of customers complete service simultaneously.
TL;DR: The results suggest that iron is involved in symbiotic N2 fixation through effects on both nodule initiation and nodule function, and that the symbiosis has a higher iron requirement than that needed for host plant growth.
Abstract: SUMMARY
The effects of iron concentration in solution on nodulation and symbiotic N2 fixation in lupins (Lupinus angustifolius L. ev. Yandee) were studied in solution culture in the glasshouse by comparing plants supplied with NH4NO3 with those reliant on N2 fixation.
At very low iron supply, adding NH4NO2 did not increase shoot growth. Under moderate iron deficiency, where plants were pale green, adding NH4NO3 increased shoot growth, implying that moderate iron deficiency was, operationally, nitrogen deficiency. Higher iron concentrations in solution were required for maximum growth of plants reliant on symbiotic N2 fixation than for those supplied with NH4NO3
Iron deficiency depressed nodule initiation earlier than host plant growth, resulting in decreased nodule number and mass. Alleviating iron deficiency enhanced leghaemoglobin production in nodules and increased nitrogen concentrations in the shoots. Iron concentration in the youngest fully expanded leaves provided a good indication of the severity of iron deficiency-caused chlorosis.
The results suggest that iron is involved in symbiotic N2 fixation through effects on both nodule initiation and nodule function, and that the symbiosis has a higher iron requirement than that needed for host plant growth.