Showing papers by "University of Western Australia published in 1982"

Chaotic genetic patchiness in an intertidal limpet, Siphonaria sp.

Abstract: Variation of 4 polymorphic enzymes was studied for 2 yr (1978 and 1979) in an undescribed species of Siphonaria, a pulmonate limpet, from a rocky shore at Rottnest Island, Western Australia. Depending on the locus, significant genetic differences were found among sites along 50 m of shore, between high and low portions of the shore within sites, between adults and recruits, and between recruits in the 2 yr. This genetic heterogeneity does not follow a simple, consistent pattern, but forms a shifting, ephemeral genetic patchiness best described as chaotic. This patchiness may result from temporal variation of numbers and genotypes of recruits, which leads to the proposal that planktonic dispersal, although causing uniformity on a large scale, can give rise to fine-scale genetic patchiness.

Picture Quality Prediction Based on a Visual Model

Abstract: Distortion measures are developed for the purpose of predicting the subjective quality of moving monochrome television pictures. The need for such measures is particularly recognized in the area of digital picture coding. Subjectively relevant distortion measures that mirror viewers' assessments of picture quality would make the task of designing and optimizing coding schemes considerably easier. The distortion measures are based on a spatiotemporal model of threshold vision that incorporates the filtering and masking processes. The visual filtering is carried out by parallel excitation and inhibition paths, each of which is separately linear but which combine in a nonlinear way to take account of the adaptation with background luminance. The masking is in the form of a point-by-point weighting of the filtered error based on the amount of spatial and temporal activity in the immediate surround. The processed error averaged over the picture is then used as a prediction of picture quality. Three Classes of distortion measure are considered: 1) the raw error measures that have been used in the past; 2) the filtered error measures where the filtering properties of vision are taken into account; and 3) the masked error measures where the masking processes are also included. It is shown that the filtered error measures are better predictors of picture quality than the raw error measures. The masked error measures lead to further improvements but only if local rather than global averaging procedures are used. It is postulated that this is because viewers tend to base their quality ratings on critical areas rather than on the whole picture.

An Extension of the Rasch Model for Ratings Providing Both Location and Dispersion Parameters.

Abstract: An elaboration of a psychometric model for rated data, which belongs to the class of Rasch models, is shown to provide a model with two parameters, one characterising location and one characterising dispersion The later parameter, derived from the idea of a unit of scale, is also shown to reflect the shape of rating distributions, ranging from unimodal, through uniform, and then to U-shaped distributions A brief case is made that when a rating distribution is treated as a random error distribution, then the distribution should be unimodal

Reducing the influence of environmental main-effects on pattern analysis of plant breeding environments

Abstract: In plant breeding yield trials the environmental range often exceeds the genotypic range. In such instances environmental main-effects (mean yields) may confound characterization of selection environments, as the general productivity of an environment may be unrelated to tendencies in the relative performance (ranking) of genetic material grown in that environment.

Direct evidence that inflammatory multinucleate giant cells form by fusion

Abstract: Multinucleate giant cells (MGC) are believed to be formed by fusion of macrophages. In a chimaeric mouse composed of two histoincompatible strains each homozygous for one of the two isoenzymic forms of glucose-6-phosphate isomerase it was found that hybrid enzyme was produced in MGC-rich leucocytic exudates. This hybrid can only occur if nuclei of the two different strains reside within a common syncytial cytoplasm, demonstrating unequivocally that macrophage fusion occurred between cells of the two strains. Since the two strains were histoincompatible it appears that no strain specific recognition is necessary for fusion to occur.

Treatment of strongyloidiasis with thiabendazole: an analysis of toxicity and effectiveness

Abstract: The effects of therapy with thiabendazole were investigated in 43 men who had been infected with Strongyloides stercoralis for 35 years. Side effects of drug treatment were frequent and sometimes severe; nausea was the most common symptom. Six months later, approximately one third of patients had persistent diarrhoea, recurrent urticaria or considered that their general health had not improved. Parasites were found in 7% of persons six months after treatment. Blood eosinophil counts fell dramatically but the falls in serum IgE levels and serum Strongyloides antibody titres were less marked. Assessment of response to treatment is difficult because of the insensitivity of parasitological techniques and the ability of this parasite to replicate. It is concluded that thiabendazole cannot always be relied upon to eradicate infection.

Ion Concentration and Carbohydrate Status of the Elongating Leaf Tissue 4Hordeum vulgare Growing at High External NaCl I. RELATIONSHIP BETWEEN SOLUTE CONCENTRATION AND GROWTH

Abstract: Seedlings of a salt tolerant barley variety, cv 'Beecher', were grown for 5 d between '0' mM and 180 mM external NaCl (NaClext). The rate of leaf elongation and shoot dry weight decreased as the NaCl increased from '0'-180 mM. CI" and (Na+ + K+) concentrations accounted for about 50% of the osmotic pressure of the elongating tissues at all NaClext. The increase in (Na+ + K+) concentration with increasing NaClext was attributable to decreases in the elongation rate and not to increases in net ion uptake. However, there were large increases in CI" uptake between '0' mM and 40 mM NaCl, and even above 40 mM NaCl not more than two-thirds of the increases in CI" concentration of the elongating leaf tissues could be attributed to reduced elongation. Thus, the rate of net Cl~ uptake increased appreciably with increasing NaClext. Nevertheless, the overall results indicate that most of the osmotic adjustment of elongating leaf tissues was probably a result of reduced growth. These data, together with those presented in the following paper, are consistent with the hypothesis that this salt tolerant variety of Hordeum vulgare is reduced in growth at high NaCl by water deficit in the elongating leaf tissues. Following an increase in NaClext, the rates of CI" and Na+ uptake into the elongating zone were about 2-4 times the rates into the mature leaves, indicating that a substantial proportion of ions entering the elongating tissue was derived from the phloem rather than the xylem. This raises the possibility that the water deficit in the elongating tissue could be due to an insufficient supply of ions by the phloem. Nevertheless, the evidence indicates that the water deficit in the elongating tissue is due to saturation of ion uptake by individual cells, rather than to a limited input to the tissue as a whole.

Adverse effects of drugs on muscle.

Abstract: A variety of drugs used in clinical practice may cause myopathy or interfere with neuromuscular transmission. The precise incidence of such disorders is not known, but it is almost certainly higher than is generally suspected. An important aspect of drug-induced muscular disorders is their reversibility if the offending agent is withdrawn, whereas failure to do so may lead to unnecessary morbidity. The study of drug effects on muscle provides a means of investigating the pathological reactions of muscle, and of producing experimental models of naturally occurring myopathies. Drug-induced myopathies may result from a direct toxic effect, which may be local when the drug is injected into a muscle or more diffuse when the drug is taken systemically, or may be secondary to electrolyte disturbances, muscle compression, ischaemia, neural activation or to the development of an immunological reaction directed against muscle. Repeated injections of antibiotics or drugs of addiction may lead to severe muscle fibrosis and contractures. A variety of drugs may cause an acute or subacute painful necrotising myopathy which may be associated with myoglobinuria, at times leading to acute renal failure. Clofibrate and epsilon aminocaproic acid are the drugs most frequently implicated, but a similar syndrome may occur in alcoholics and heroin addicts. Certain hypocholesterolaemic agents may induce myotonia by altering the sterol composition of the muscle cell membrane, while certain drugs including beta-adrenergic blockers and agonists, succinylcholine and diuretics may exacerbate or unmask pre-existing myotonia. In the syndrome of malignant hyperpyrexia, halothane, succinylcholine and various other agents may induce a potentially fatal state of muscular rigidity and hypermetabolism in susceptible individuals as a result of a defect in the calcium transport function of the sarcoplasmic reticulum and possibly of other cellular membranes. In corticosteroid myopathy, which is the most common form of drug-induced myopathy, there is selective atrophy of type 2 muscle fibres and the primary metabolic effect is an inhibition of RNA and protein synthesis, although protein degradation is also increased. Chloroquine and a number of related drugs with amphiphilic cationic properties may induce lysosomal storage myopathy, which may be associated with cardiomyopathy and with a more widespread form of lipidosis.

Effect of Phosphorus Deficiency and Water Deficit on Phosphatase Activities from Wheat Leaves

Abstract: Wheat was sown in a phosphorus (P) deficient soil. Plants at low levels of applied P had lower growth rates and lower concentrations of phosphate in the shoots than plants grown with ‘high P’. Activities of both insoluble and soluble phosphatase increased with P deficiency in the mature leaves. Soluble phosphatase activities increased 2.5–3.0 fold as the concentration of phosphate in the leaves fell from 0.4% to 0.1% dry weight This increase was not a consequence of reduced growth, as severe nitrogen deficiency had no effect on phosphatase activity. Soluble phosphatase activities were higher in young than in mature leaves, and also increased 3–4 fold with severe water deficit. However these increases in activity were not accompanied by low concentrations of phosphate. Moreover, soluble phosphatase activities in mature leaves of plants grown under conditions of water deficit rapidly decreased after rewatering. In contrast, the high soluble phosphatase activities in mature leaves of P deficient wheat persisted for up to 12 d after the resupply of P to adequate levels.

The mesothelium: Its fibrinolytic properties

Abstract: We have investigated the fibrinolytic properties of the mesothelium by developing a test system in which standard tissue samples can be assessed in a comparative and semi-quantitative manner. The problem whether plasminogen activators were generated by the mesothelium itself or were transported from a subserosal site was also studied. A standard system was developed by using a uniform gelatin disc to obtain a monolayer imprint of mesothelium and subsequently incorporating several of these samples on a fibrin plate. Pure cultures of mesothelial cells were able to induce fibrinolysis.

Polymorphism for direction of coil in Partula suturalis: Behavioural isolation and positive frequency dependent selection

Abstract: Partula suturalis is unusual among snails in being polymorphic for direction of shell coiling. Polymorphic populations of P. suturalis occur in narrow clines between areas of monomorphic dextral or sinistral populations. The distribution of dextral populations coincides with the distribution of the sinistral species P. mooreana, P. tohiveana and P. Olympia suggesting character displacement for reproductive isolation. Chirality affects courtship behaviour, and no-choice mating experiments show that pairs with opposite coil mate only 20 per cent as frequently as do pairs with the same coil. Fewer young are produced by these mixed pairs. Fertilities of dextral and sinistral P. suturalis are the same in a population composed of equal frequencies of the two morphs. However, among wild-caught snails from a population in which sinistrals occur at low frequency, the rare morph produces fewer young than the common morph. The effects of chirality on behavioural isolation result in selection against the rare morph, accounting for the rarity of polymorphic populations. Such positive frequency dependent selection is capable of maintaining the stability of hybrid zones.

Laterality effects in visual information processing: Hemispheric specialisation or the orienting of attention?

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...

Housing Consumption Over the Family Life Cycle: an Empirical Analysis

Abstract: The family life cycle has long been an important element in the analysis of household consumption and earnings patterns Housing studies have, however, given surprisingly little attention to the concept Using a sample of recent house purchasers from Perth, Western Australia, this paper analyses the pattern of housing consumption and location over the family life cycle, together with the financial position of the household The results indicate that marriage-partnering and initial schooling are the significant stages Contrary to some recent work, we find clear evidence of reduced space consumption once child rearing is completed and for the presence of income constraints within life cycle stages Wealth and income are found to be more important in explaining housing consumption than the family life cycle concept

Pharmacological responses of human and porcine lung parenchyma, bronchus and pulmonary artery.

Abstract: 1 Responses of preparations of human and porcine isolated bronchus and pulmonary artery to carbachol (CCh), methacholine, histamine, 5-hydroxytryptamine (5-HT), (-)-noradrenaline (NA), (-)adrenaline (Adr) and (+/-)-isoprenaline (Iso) were compared with responses to the same agonists in isolated lung parenchyma strips. 2 All preparations from both human and porcine lung contracted in response to histamine and all, except preparations of porcine pulmonary artery, contracted in response to CCh. Human and porcine pulmonary artery and parenchyma strip contracted in response to NA while bronchial preparations invariably relaxed. Iso caused relaxation of human and porcine bronchus and parenchyma strip. Although 5-HT was completely inactive in tissues isolated from pig lung, this amine was a powerful spasmogen in human pulmonary artery, relaxed human bronchus and caused variable responses in human parenchyma. 3 Results indicate that the pharmacological characteristics of human and porcine parenchyma strips may be explained in terms of responses of vascular or airways smooth muscle.

Relative size of Aristotle's lantern in Echinometra mathaei occuring at different densities

Abstract: Like species of sea urchins in Zanzibar and Oregon (USA), Echinometra mathaei (de Blainville) at Rottnest Island, Western Australia, displays variation in the size of Aristotle's lantern relative to the maximum diameter of the test. This variation was associated with local variations in density of urchins at each of two sites in each of two years (1980 and 1981); this association with density was consistent with the proposal that relatively larger lanterns are a response to decreased food availability. Furthermore, variation of relative lantern size associated with local density was similar in magnitude to the variation displayed between sites and between years. This temporal variation demonstrated the plasticity of the relative lantern size over periods as short as 12 mo. Further experimental studies are required before relative length of lanterns can be used as estimates of food availability.

Inter-genotype aggression in the solitary sea anemone Actinia tenebrosa

Abstract: Acrorhagial fighting occurs between some pairs of adult Actinia tenebrosa, and such fighting almost always results in the locomotory withdrawal of the loser. Adults are also able to attack and kill juvenile conspecifics in laboratory conditions. In laboratory trials, 58 of 89 pairs of adults responded aggressively when placed in contact. Conflicts developed disproportionately often when adults were genotypically different, as judged by electrophoretic examination of 5 polymorphic enzymes, or when adults were markedly different in weight. Neither the sexual maturity nor presence of brooded juveniles affected the probability that conflicts would develop between adults. Weight did not affect the outcome of the conflicts. Presentation of apparently asexually produced juveniles to adults revealed that both the recognition and effector phases of the acrorhagial response are triggered by genotypic dissimilarity and not by size dissimilarity per se. Acrorhagial responses were initiated only on contact with juveniles from other adults. Localised release of asexually-produced brooded juveniles contributes substantially to recruitment within established populations of A. tenebrosa. Aggressive interactions between genotypes thus seem likely to play an important role in intra-specific competition for recruitment space.

Language and orthography as irrelevant features in colour-word and picture-word stroop interference

Abstract: Based on evidence that Chinese yields more interference than English, Biederman and Tsao (1979) have suggested that the processes involved in reading Chinese are more similar to those involved in colour naming than are the processes involved in reading English. In three experiments conducted to evaluate the empirical foundation for this hypothesis it was found that: (1) Chinese yielded less interference than English (and French) in between-subjects comparisons involving Chinese-English bilinguals and English monolinguals or English-French bilinguals; (2) Chinese print did not yield more interference than English print in within-subjects comparisons involving the orthogonal combination of print language (Chinese or English) and naming language (Chinese or English) among Chinese–English bilinguals; and (3) compared with syntactic category, both language and orthography were relatively impotent variables in the object naming version of the Stroop task.