Showing papers by "University of Western Australia published in 1987"

Cereal–Legume Intercropping Systems

Abstract: Publisher Summary This chapter describes the various aspects of cereal-legume intercropping systems Intercropping is the growing of two or more crop species simultaneously in the same field during a growing season The intercropping of legumes with cereals offers scope for developing energy-efficient and sustainable agriculture The main types of intercropping include mixed intercropping, row intercropping, and strip intercropping Crop combinations differ with geographical location and there may be intercropping of tree crops, intercropping of tree and field crops, or intercropping of field crops Combinations of crops are determined primarily by the length of the growing season and the adaptation of crops to particular environments Different indices have been suggested for evaluating productivity and efficiency per unit area of land of cereal-legume intercrop systems These include comparisons of absolute yields, protein yields, caloric equivalent, and in economic terms, gross returns from intercrops and sole crops Differences in competitive ability affect the relative performance of component crops and thus the land equivalent ratio values of different cereal-legume intercrop systems It is found that phosphorus is a major nutrient that determines the production potential of most grain legumes usually intercropped with cereals

Failure of familial Alzheimer's disease to segregate with the A4-amyloid gene in several European families.

Abstract: The gene coding for the amyloid protein, a component of neuritic plaques found in brain tissue from patients with Alzheimer's disease, has been localized to chromosome 21, and neighbouring polymorphic DNA markers segregate with Alzheimer's disease in several large families. These data, and the association of Alzheimer's disease with Down's syndrome, suggest that overproduction of the amyloid protein, or production of an abnormal variant of the protein, may be the underlying pathological change causing Alzheimer's disease. We have identified a restriction fragment length polymorphism of the A4-amyloid gene, and find recombinants in two Alzheimer's disease families between Alzheimer's disease and the A4-amyloid locus. This demonstrates that the gene for plaque core A4-amyloid cannot be the locus of a defect causing Alzheimer's disease in these families. These data indicate that alterations in the plaque core amyloid gene cannot explain the molecular pathology for all cases of Alzheimer's disease.

Resource depletion by active suspension feeders on tidal fiats: Influence of local density and tidal elevation1

Abstract: Sampling at two elevations from a tidal flat on the Shark Bay (Western Australia) shoreline at Monkey Mia revealed abundant suspension-feeding bivalves of numerous (> 17) species. Their total density increased by 3 x up the tidal elevation gradient from the subtidal margin of the flat to intertidal sites -97 cm higher. Factorial field experiments were used to test the effect of site (tidal elevation), local bivalve density, and their interaction on growth and survivorship of three species of suspension-feeding bivalves. Survivorship was high and did not vary significantly with site or local density. Individual growth was generally lower at higher density for both AnomaZocardia squamosus and Circe lenticularis, but growth of CaZZista impar never responded significantly to local density. Site effects on individual growth were far stronger than density effects and operated on all three species: growth at the intertidal site was substantially lower than at the subtidal site. The intensity of the site effect on individual growth about doubled from the first (February-June) to the second (June-December) experimental interval, probably because average daily exposure to air also doubled. Despite the success of tidal exposure in explaining seasonal variation in growth differences between sites, at a given season clams at the intertidal site grew substantially less than predicted from duration of aerial exposure and density. We hypothesize that density effects estimated locally within 1 -m2 areas fail to assess the full magnitude of food depletion that occurs over broader scales and that suspension feeders low on the flat deplete suspended foods in incoming tidal flows before they ever reach clams at higher elevations.

Implementing Packaged Software

Abstract: This paper presents a model of the implementationprocess for dedicated packages and describes a researchproject to test the model undertaken with the cooperation ofa major computer vendor. Data were collected from 78individuals in 18 firms using the package and from thepackage vendor. The results of the study offer some supportfor the model along with suggestions for packageimplementation for both the customer and package vendor.

Porous-surfaced metallic implants for orthopedic applications.

Abstract: Following the transplantation of bone marrow cells to extra-osseous sites, bone formation occurs in those sites. This osteogenic potential of bone marrow cells might be utilized for filling defects in bone if they could be transported on porous ceramic materials. Before such an approach becomes feasible, it is important to know what happens to the cells in the presence of the ceramics that might be used. In order to investigate the interaction between bone marrow cells and ceramics, in vitro, a system for culturing bone marrow cells on ceramic materials has been developed. Bone marrow cells adhered well to the surface of calcium hydroxyapatite and tricalcium phosphate ceramics, and this was followed by the formation of fibrous tissue on and within the ceramics. These ceramics were compatible with bone marrow cells even in culture conditions in which there was a large surface area of ceramic interfacing with cells. The results support the proposal that calcium hydroxyapatite and tricalcium phosphate are appropriate as bone replacement materials. In contrast, calcium aluminate had an adverse effect on bone marrow cells when there was a high proportion of ceramic to culture medium. However, this effect was not present if the proportion of ceramic to culture medium was low. Therefore, a large amount of biodegradable porous calcium aluminate ceramic should not be used as an alternative to autogeneous bone grafting.

Singular-value decomposition and embedding dimension

Abstract: Data from dynamical experiments are often studied with use of results due to Shaw et al. and to Takens, which generate points in a space of relatively high dimension by embedding measurements which are typically one dimensional. A number of questions arise from this, the most obvious being how should one choose the dimension of the embedding space. In this paper we show that a method which seems promising at first sight, estimating the rank of the matrix of embedded data, is unfortunately not useful in general. Previous encouraging results have almost certainly been due to numerical problems which can, in part, be avoided by a careful application of singular-value decomposition. We show that this process does not give useful dynamical information, though it is often useful in noise control.

The Wage Effect of the Occupational Segregation of Women in Britain

Abstract: Married females earn around 60 percent of the male rate of pay. Part of this wage difference der ives from inequality of pay within occupations and part derives from the different occupational distributions of the male and female workf orces. This paper merges models of occupational attainment and gender wage distributions. It shows that the gender wage difference derives largely from wage differences within occupations. The effect of fema le nonparticipation in the paid workforce is found to be an important aspect of occupational attainment as well as of pay differences with in occupations. Copyright 1987 by Royal Economic Society.

Effects of vesicular-arbuscular mycorrhiza on the availability of iron phosphates to plants

Abstract: The effect of inoculation with a mycorrhizal fungus on the growth of subterranean clover and of ryegrass was measured using three sources of phosphorus with different solubilities. These were (in order of decreasing solubility): potassium dihydrogen phosphate, colloidal iron phosphate and crystalline iron phosphate. Mycorrhizal infection increased growth more for subterranean clover than for ryegrass for all sources of phosphorus. For both species the greatest benefit from mycorrhizal inoculation was obtained with the least soluble source of iron phosphate. It is suggested that the mycorrhizas were able to explore the soil more thoroughly and hence were able to locate and use the point sources of phosphorus in the insoluble iron phosphates.

Initiation and duration of muscle precursor replication after mild and severe injury to skeletal muscle of mice. An autoradiographic study.

Abstract: We test the proposal (McGeachie and Grounds 1985) that myogenesis following severe (crush) injury is prolonged compared with minor (cut) injury. Forty-four mice were injured with a cut and a crush lesion on different legs, and tritiated thymidine was injected at various times after injury (0 to 120 h), samples of regenerated muscle were taken 9d after injury and autoradiography was used to determine the initiation of muscle precursor replication, and duration of proliferation after the two different injuries.

Effect of solar ultra-violet radiation on the kelp Ecklonia radiata

Abstract: During spring and summer, 1982–1986, experiments were carried out near Marmion Reef, Western Australia In summer, nearly 30% of the surface solar ultraviolet radiation (280 to 400 nm) penetrates offshore waters to 5 m depth Experimental removal of the mature Ecklonia radiata kelp canopy in summer results in tissue damage, photopigment destruction, reduced growth, and low survivorship of subcanopy kelp sporophytes These effects do not occur with canopy removal in winter Laboratory experiments revealed that the UV component of radiation, rather than intense photosynthetically active radiation, was responsible for the inhibition of growth and photodamage UV radiation probably affects survival of the settlement stages of E radiata sporophytes, thus excluding them from otherwise suitable substrata in shallow waters UV radiation is implicated in the reduction of canopy productivity in summer

Measurement of the milk intake of breast-fed infants.

Abstract: Infant test weighing and maternal test weighing are two independent methods for determining milk intake by the breast-fed infant. The sources of error in both these test weighing methods were examined with particular emphasis on the importance of evaluating and correcting for evaporative water loss (EWL). EWL ranged from 3 to 94% of the mother's change in weight after a single breast feed and from 3 to 55% of the infant's change in weight after a single breast feed. Correcting for EWL during a breast feed involved determining the time between the pre- and postfed weighings and measuring the rate of EWL after breast feeding. Significant correlations (p less than 0.001) were found between milk volume intake measured by test weighing the mother and correcting for maternal EWL, and milk volume intake measured by test weighing the infant and correcting for infant EWL. An improved method for measuring 24-h milk intakes by maternal test weighing using a sensitive electronic balance and correcting for EWL is described. The milk intakes, corrected for EWL, ranged from 690-1,041 g/24 h. If no correction for EWL was made then the average overestimate of milk intake by maternal test weighing was 14 +/- 6%.

Data Requirements for Reliable Estimation of Correlation Dimensions

Abstract: It is not always possible to resolve the dimension of an attractor from a finite data set. The number of data points required depends on the structure of the attractor, the distribution of points on the attractor, and the precision of the data. If the chaotic component of a system’s behaviour is sufficiently small relative to its large scale motion, and if orbits seldom visit the region of the attractor with small scale fractal structure, any method will fail to resolve the attractor’s dimension. It is simple to construct abstract mathematical examples that present this behaviour. However, while these limitations should be explicity recognised, it should also be noted that a growing body of empirical experience suggests that experimentally encountered physical and biological systems do not invariably display these behaviours. It is possible to estimate reliably the dimension of these attractors with comparatively small data sets.

The Measurement of Inflation: A Stochastic Approach

Abstract: The stochastic approach to index number theory views each commodity price change as an independent observation on the underlying rate of inflation so that inflation can be estimated by averaging over all the prices. This article extends the approach by (a) allowing for sustained changes in relative prices, (b) showing the link with Divisia index numbers, and (c) deriving standard errors for the inflation estimates. The results are illustrated with Australian data.

A review of the bruininks‐oseretsky test of motor proficiency

Abstract: Summary. The Bruininks-Oseretsky Test of Motor Proficiency was examined in an effort to establish its credibility as one of the most widely used tests of motor development in children. The presentation of the test is excellent. However, doubts are expressed about the item development, standardisation, reliability, validity, and grouping of tests into fine and gross motor skills. Changes to the manual are recommended that should facilitate more appropriate interpretations of test results. Without these changes, the use of the test for the assessment of most children remains highly questionable.

A Practical Introduction to Denotational Semantics

Abstract: From the Publisher: Numerous exercises in Pascal encourage the student to write and test definitions in this introduction to denotational semantics and its applications to programming languages.

Phagocytosis of necrotic muscle in muscle isografts is influenced by the strain, age, and sex of host mice

Abstract: In grafts of skeletal muscle the implanted muscle becomes necrotic, is phagocytosed and replaced by new muscle cells. This study investigates the hypothesis that removal (phagocytosis) of necrotic implanted muscle is impaired in grafts made into old Swiss mice. Isografts (154) of minced muscle were made between young (20 day) and old (140 day) mice of the strains Swiss, AKR, BALBc, C3H and C57BL. Grafts were examined histologically after 7 days. A relationship between impaired phagocytosis and increasing host age was confirmed for male Swiss mice but was not seen with female Swiss mice or the other four strains. The proposal that ageing of bone marrow was responsible for diminished phagocytosis in old Swiss mice was investigated by replacing the marrow of 33 lethally irradiated male Swiss mice with marrow cells from mice of different ages (20 and 140 day), before isografting minced muscle. The results clearly show that macrophage stem cell function is unimpaired with age. Testosterone levels might account for the impaired phagocytosis seen in many sexually mature male Swiss mice. Support for this proposal came from experiments in which 15 mice were castrated before implanting muscle isografts. This study shows that genetic factors rather than the age of mice influenced phagocytosis and muscle formation in grafts.

Archaean strike-slip faulting and related ensialic basins: evidence from the Pilbara Block, Australia

Abstract: Archaean sedimentary and volcanic successions in the Lalla Rookh Basin and c. 2950 Ma old Whim Creek Belt in the Pilbara Block, Western Australia, were deposited in basins with roughly the same configuration as their present outcrop. Basins were fault-bounded and developed in an ensialic setting, overlying older (3500 to 3300 Ma old); deformed and metamorphosed supracrustal rocks and granitoids. The basin margin faults are now part of a pattern of strike–slip faults which were active during the later stages of regional batholith emplacement. In both cases, structural patterns and style of basin filling are similar to younger basins related to strike–slip faulting. The Lalla Rookh Basin was dominated by coarse clastic sedimentation, comprising alluvial–fan, braided–stream, fan–delta and lacustrine facies. The Whim Creek Belt contains bimodal volcanics and clastic sediments, which comprise alluvial, subaqueous fanglomerate, submarine-fan and basinal facies. Regional strike–slip faulting and the development of the Lalla Rookh Basin and Whim Creek Belt, in response to externally imposed deformation, records an important step in the cratonization of the Pilbara Block. Late Archaean sedimentary basins, dominated by coarse clastic facies and situated adjacent to major strike–slip faults, in other cratons may have a similar origin.

The role of soil pH in the dissolution of phosphate rock fertilizers

Abstract: The influence of soil pH on the dissolution of phosphate rock fertilizers was investigated in laboratory experiments with reactive North Carolina phosphate rock (PR) in a lateritic soil adjusted to several pH values. Increased soil pH resulted in decreased dissolution as estimated by the increase in exchangeable calcium (ΔCa) method. The extent of PR dissolution was related to soil pH by an equation of the form Log ΔCa = a–b pH, and it increased with contact period and rate of PR application. Increased plant available P, as estimated by NaHCO3 soluble-P (ΔBicP) was about one third of the P dissolved from PR. ΔBicP was related to soil pH by an equation of the form Log ΔBic P = c–d pH. Dissolution of PR in soil can be considered as a simple chemical reaction between apatite and hydrogen ions supplied by soil constituents.

Cross-orientation inhibition in cat is GABA mediated.

Abstract: Visual evoked potentials (VEPs) were recorded from cat cortex (area 17) before, during and after application of the GABA blocker bicuculline (iontophoretic or topical). The stimuli comprised a test sinusoidal grating, and a mask grating oriented either parallel or orthogonal to the test. Both test and mask alternated in contrast at different temporal frequencies. VEPs were averaged in synchrony with the test contrast reversal, so the mask did not contribute directly to the averaged VEP response. Before application of bicuculline, both parallel and orthogonal masks attenuated the amplitude of VEPs and changed the phase response, but in different ways. Orthogonal masks lowered the slope of the contrast response curve without affecting extrapolated threshold, while parallel masks caused the curve to shift to the right. Orthogonal masks increased the phase advance, while parallel masks eliminated it. During application of bicuculline, neither parallel nor the orthogonal masks attenuated VEP amplitudes. The results suggest that although the mechanisms for the action of parallel and orthogonal masks are clearly distinct, both are mediated by the GABA-ergic inhibitory system. Given this evidence, measurement of VEP contrast response curves may provide a simple non-invasive technique for monitoring visual inhibition in humans.