Showing papers by "University of Adelaide published in 1986"

Learning styles and approaches: implications for medical education.

Abstract: This paper reviews the recent literature on learning styles and approaches to learning. It identifies two separate streams of research, one originating from mainstream cognitive and psychometric psychology and one from research undertaken within the everyday learning environment. The latter is dealt with in greater detail as it seems to have more immediate practical relevance. A simple model of the teaching-learning process is presented showing how students learn in different ways which are partly attributable to their preferred learning style and partly to the context in which the learning takes place. Three basic approaches have been identified: surface, deep and strategic, each resulting in a different learning outcome. The most desirable and successful is the deep approach. The way in which the teaching and the policies of the department and school influence the students' approach to learning are reviewed in some detail. A consideration of these characteristics in medical schools suggested that many may hinder rather than assist in the development of the desired approach. The work reviewed here suggests that the remedy will require not only substantial changes in the teaching, curriculum and, particularly, assessment, but also a new strategy based on identifying and assisting individual students whose approaches to study are not those expected of a competent university-educated doctor.

The approaches to learning of students in a traditional and in an innovative problem‐based medical school

Abstract: The way in which students approach their learning is dependent on a variety of factors including the characteristics of the departments and teaching to which they are exposed. These factors appear to influence whether the students adopt a surface, deep or strategic approach. In order to explore further the relationship between educational context and approach to learning, a comparison was made between students attending a traditional medical school and those attending a problem-based medical school. The results showed marked differences, with the problem-based school being higher on deep approach and lower on surface approach than the traditional school. This study provides one of the first pieces of evidence of a difference between students in the two types of medical school which can be directly attributed to the educational environment. Students in the problem-based school appear to have an approach to learning which more closely approximates the aims of most medical schools. The results provide support for the philosophies and strategies of the problem-based schools.

Input of carbon to soil from wheat plants

Abstract: The growth of wheat plants and the distribution of labelled photosynthate from pulse-labelling with 14CO2 were measured periodically during the growing season in the field. During early growth there was approximately the same proportion of photosynthate translocated below ground and retained in the shoots. Of the 14C below ground about a half was respired and a quarter each was in the soil and roots. This distribution changed exponentially during growth with an increasing proportion of 14C remaining in the shoots and a corresponding decreasing proportion being translated below ground, which was only a few percent by flowering. From this information the total input of carbon to the soil from the crop was calculated to be 1305 kg Cha−1. Comparison of these estimates with those from previous experiments suggest that differences do occur due to the stage of growth of the plant, the environmental conditions, soil type and microbial activity.

Feather Keratin: Composition, Structure and Biogenesis

Abstract: The proteins of feather become soluble when they are treated with a combination of a disulphide bond-breaking reagent and a protein denaturant. The disulphide bonds of feather keratin have been cleaved by reduction with alkaline thioglycollate (Goddard and Michaelis 1934; Harrap and Woods 1964a), by sulphitolysis (Woodin 1954; Harrap and Woods 1964a) and by oxidation (Harrap and Woods 1964 a). Although detergents (Ward et al. 1946) and dissociating agents such as guanidine and urea have been tested (Jones and Mecham 1943), the customary practice is to extract into 8 M urea at pH 9.8 in the presence of either 0.1 M sodium thioglycollate (Harrap and Woods 1967) or 0.1 M β-mercaptoethanol (Kemp and Rogers 1972) and to convert the proteins to their S-carboxymethyl (SCM) derivatives by reaction with sodium iodoacetate.

Gastric and oesophageal emptying in insulin-dependent diabetes mellitus

Abstract: Gastric emptying of a digestible solid and liquid meal and oesophageal emptying of a solid bolus were measured with scintigraphic techniques in 45 randomly selected insulin-dependent diabetics and in 22 control subjects. In the diabetics, the relationships between oesophageal emptying, gastric emptying, age, duration of diabetes mellitus, upper gastrointestinal symptoms, glycaemic control and the complications, autonomic neuropathy, peripheral neuropathy and retinopathy were examined. The lag period before solid food left the stomach was not significantly different in diabetics compared with control subjects, but the percentage retention of solid food at 100 min was greater (P 15 mmol/l during the gastric emptying test and the lag period for solid emptying correlated with both the glycosylated haemoglobin and mean plasma glucose concentrations.

Stress and acute respiratory infection

Abstract: To examine the relationship between stress and upper respiratory tract infection, 235 adults aged 14-57 years, from 94 families affiliated with three suburban family physicians in Adelaide, South Australia, participated in a six-month prospective study. High and low stress groups were identified by median splits of data collected from the Life Events Inventory, the Daily Hassles Scale, and the General Health Questionnaire, which were administered both before and during the six months of respiratory diary data collection. Using intra-study stress data, the high stress group experienced significantly more episodes (mean of 2.71 vs. 1.56, p less than 0.0005) and symptom days (mean of 29.43 vs. 15.42, p = 0.005) of respiratory illness. The two groups were almost identical with respect to age, sex, occupational status, smoking, passive smoking, exposure to air pollution, family size, and proneness to acute respiratory infection in childhood. In a multivariate model with total respiratory episodes as the dependent variable, 21% of the variance was explained, and two stress variables accounted for 9% of the explained variance. Significant, but less strong relationships were also identified between intra-study stress variables and clinically "definite" episodes and symptom days in both clinically definite and total respiratory episodes. Pre-study measures of stress emphasized chronic stresses and were less strongly related to measures of respiratory illness than those collected during the study. However, significantly more episodes (mean of 2.50 vs. 1.75, p less than 0.02) and symptom days (mean of 28.00 vs. 17.06, p less than 0.03) were experienced in the high stress group. In the multivariate analyses, pre-study stress remained significantly associated with total respiratory episodes and symptom days in total and "definite" respiratory episodes. In all of the multivariate analyses performed, sex (female) and age also appeared as important correlates of respiratory illness.

Measurement of phosphorus in the soil microbial biomass:A modified procedure for field soils

Abstract: A range of gaseous, liquid and vapour biocides was tested in combination with seven extradants for their ability to release P from soil microorganisms in situ . The biocides tested were chloroform, ethanol, propan-1-ol, hexan-1-ol, β-propiolactone, formaldehyde, glutaraldehyde, ethylene oxide and methyl bromide. The extradants tested were 0.5 M NaHCO 3 (pH 8.5), 0.1 M NaHCO 3 (pH 8.5), 50 mM NaOH, 10 mM CaCl 2 , 50 m m H 2 SO 4 , 30 m m NH 4 F + 0.1 m HC1, and an anion exchange resin in the bicarbonate form suspended in distilled water. An incubation technique using 32 P ensured that only microbial P was measured. Chloroform and hexanol were the most effective biocides: the latter is preferred because of its less hazardous nature. The best extradant was 0.5 M NaHCO 3 (pH 8.5). Mixed populations of soil organisms were used for calibration, and the K p factors obtained with hexanol and 0.5 m NaHCO 3 (pH 8.5) were 0.33, 0.40 and 0.57 for the three soils studied. Since microflora differ from soil to soil, as do the amounts and form of P released, calibration is necessary for each soil. Incubation is not recommended as a prior treatment for samples used to measure biomass P: the soils should be treated with hexanol or extracted immediately after sampling to avoid quantitative or qualitative changes in the biota or biomass. Errors associated with the inclusion of roots in the sample can be minimized by removing the bulk of the roots before fumigation.

Development of a new piosphere in arid chenopod shrubland grazed by sheep. 2. Changes to the vegetation

Abstract: The initial development of a piosphere created by stocking a new watering trough with ca. 200 sheep at a near-pristine site in arid chenopod shrubland near Whyalla, South Australia, was studied. The following variables were monitored for up to 8 years using fenced plots as controls:shrub mortality; forage biomass and defoliation of the dominant shrubs and short-lived grasses; linear dimensions of Rhagodia ulicina; the density of short-lived species; and the invasion of exotics. Patterns in these variables were looked for which reflected the attenuation of stocking pressure with distance from water; that is, ‘piosphere patterns’. Piosphere patterns were detected for many variables. Those with values increasing towards the trough were mortality of the main forage shrub Atriplex vesicaria. the density of three short-lived taxa, viz. the bassias (Sclerolaena obliquicuspis, S. patenticuspis. Maireana sclerolaenoides), Tetragonia tetragonoides, and annual Zygophyllum spp. (Z. crenatum. Z. ovatum), and growth of short-lived grass species when sheep stocking pressure was low. Variables with values decreasing towards the trough were grass biomass, percentage of A. vesicaria individuals in flower, the percentage foliation of A. vesicaria and of the forage shrub Maireana sedifolia, and shrub forage biomass of A. vesicaria and M. sedifolia. The rate at which these patterns were registered varied. After only 3 months, a piosphere pattern was evident for grass biomass. Marrubium vulgare, an introduced weed, invaded the trough site within the first 6 months. Almost no A. vesicaria shrubs had died after 2 years, but after 8 years there was a marked piosphere pattern in their mortality. The piosphere patterns in forage biomass and defoliation of A. vesicaria and M. sedifolia became more pronounced with time. Some variables did not exhibit a piosphere pattern, such as the dimensions of the shrub R. ulicina and the densities of successive cohorts of the forb Erodium spp., even though there was an overall effect of grazing in reducing their values. There was no mortality of two dominant shrubs, M. sedifolia and R. ulicina, during the first 8 years.

Maximum axial and radial growth pressures of plant roots

Abstract: The axial root growth force exerted by seedlings of pea (Pisum sativum cv. Greenfeast), cotton (Gossypium hirsutum cv. Sicot 3) and sunflower (Helianthus annuus cv. Hysun) was measured. Effects of different seedling age and different batches of seeds on axial root growth pressure were investigated.

Molecular cloning of the cDNA for androgen‐dependent sperm‐coating glycoproteins secreted by the rat epididymis

Abstract: cDNA clones coding for two closely related androgen-dependent sperm-coating glycoproteins secreted by the rat epididymis were selected by screening an epididymal cDNA library constructed in λgt 11 with affinity-purified antibody directed against the glycoproteins. The largest clone of 956 nucleotides provided coding information for a protein of 246 amino acids of which the first 19 residues comprise a putative signal peptide sequence which when cleaved would produce a mature protein of 227 residues and a molecular mass of 26 kDa. Confirmation of the identity of the clone was provided by a match between the amino acid sequence predicted from the cDNA sequence and the actual amino acid sequence determined for a tryptic peptide fragment of one of the pure glycoproteins. It is probable that the primary amino acid sequence of the two glycoproteins is identical. Northern blot and slot-blot analysis revealed that the mRNA for the glycoproteins is approximately 1250 nucleotides long and that the concentration of the mRNA in the epididymis is androgen-dependent. The glycoproteins and their mRNAs were unique to the epididymis as determined by Western and Northern blots, respectively, since signals were absent from skin, brain, liver, kidney, heart, skeletal muscle and testis. Cross-reacting proteins of slightly smaller apparent molecular mass were detected in extracts of mouse and guinea-pig epididymis, but not rabbit or bull epididymis. Comparison with existing protein data bases revealed that the epididymal glycoproteins display significant sequence homology with yeast carboxypeptidase Y.

The pharmacologic and toxicological properties of zinc oxide-eugenol

Abstract: An explanation of the therapeutic effects of zinc oxide-eugenol when placed in contact with intact or carious dentin, and the toxic effects of zinc oxide-eugenol when placed in contact with soft tissue or tissue cultures is presented to allow for the rational, safe, and effective use of the material.

Rapid immunoperoxidase staining of lymphocyte antigens using microwave irradiation.

Abstract: The innovative application of microwave irradiation in the immunoperoxidase staining of a wide range of labile lymphocyte antigens is described. Fifteen second irradiation at 320 watts produced excellent adherence of the frozen sections to the glass slides without loss of surface antigen staining. This brief procedure eliminated the need for much longer periods of freeze drying or drying at 4 degrees C. Microwave irradiation was also used to accelerate the incubation of the primary antibody. Thirty seconds of irradiation at 320 watts produced specific antigen staining of an intensity which was as good as that obtained with much longer durations of incubations at room temperature. Cytomorphologic preservation was also good and background staining was minimal.

Effects of photon irradiance on the growth of shoots and roots, on the rate of initiation of mycorrhizal infection and on the growth of infection units in Trifolium subterraneum L.

Abstract: SUMMARY The effects of photon irradiance on the growth of young plants (up to three weeks old) of Trifolium subterraneum L. and on the development of mycorrhizal root systems were studied with plants grown in a soil/sand mixture inoculated with Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe. Total plant growth was lower when photon irradiance was 100 μmol m−2 s−1, compared with 450 μmol m−2 s−1. Fresh weight of shoots was unaffected, but the fresh weight/dry weight ratio was increased at the lower irradiance in shoots, but not in roots. The main effect of decreased irradiance on the growth of the root system was a reduction in the numbers of first- and second-order lateral roots initiated. The average rate of extension of axial and lateral roots was only slightly reduced. The fraction of the root length infected was lower at the lower irradiance, particularly in the first two weeks. Development of infection was analyzed in terms of the role of formation of mycorrhizal entry-points (A) and the average rate of growth of infection units (B). Reduction in the fraction of the root length infected was found to be due to a reduction in A. B was remarkably constant at the two irradiances and in the different root subsystems. Thus both roots and infection units respond by making fewer units of unaltered rate of growth.

Impact ejecta horizon within late precambrian shales, adelaide geosyncline, South australia.

Abstract: A solitary layer of shattered crustal rock fragments has been traced over a distance of 260 kilometers within folded 600-million-year-old Precambrian marine shales of the Adelaide Geosyncline, South Australia. The fragments consist entirely of acid to intermediate volcanics (approximately 1575 million years old) displaying shattered mineral grains, shock lamellae in quartz, and small shatter cones. Fragments reach 30 centimeters in diameter and show evidence of vertical fall emplacement. Available evidence points to derivation of the rock fragments from a distant hypervelocity impact into the Gawler Range Volcanics at Lake Acraman, approximately 300 kilometers west of the Adelaide Geosyncline.

Model experiments on the behaviour of roots at the interface between a tilled seed-bed and a compacted sub-soil

Abstract: When elongating seminal roots of developing plants reach the base of a tilled seedbed, they often encounter a layer of dense, strong untilled soil. At this interface, they may be deflected horizontally and instead of penetrating the sub-soil, they may form a horizontal mat of roots at the base of the seed-bed. If this occurs, the plants are unable to absorb the reserves of water in the sub-soil, and are very sensitive to short periods of drought.

Periodontal disease in ancient populations.

Abstract: Recent clinical and anthropological findings indicate that the conventional concept of the pathogenesis of periodontal disease requires review. The periodontal lesion has been defined as a generalised horizontal loss of crestal bone resulting from host immune and inflammatory responses triggered by the action of commensal bacteria, and the extension of gingivitis into the deeper periodontium to become periodontitis has been assumed to occur slowly but steadily over many years. Anthropological and clinical investigations reveal that the widespread loss of crestal tissue is relatively unusual and that lesions of the alveolus are commonly localised and severe. Longitudinal studies have shown that the disease progresses in bursts and is stable in both the gingivitis and periodontal modes in between the burst activity. The findings of the present study demonstrate that generalised horizontal periodontitis has been unusual and has not been responsible for tooth loss. Other factors responsible for deficient alveolar margins in dry bones have been overlooked in most studies, leading to overassessment of the incidence of periodontal disease in postmortem materials; the same assumptions have led to overassessment of periodontal disease in clinical studies and practice.

Effect of electron–photon cascading on the observed energy spectra of extragalactic sources of ultra-high-energy γ-rays

Abstract: On a effectue une simulation de Monte Carlo pour etudier la propagation des rayons γ sur de grandes distances afin de determiner les consequences relatives aux spectres observes pour les sources extragalactiques. On discute des implications de ces resultats pour les observations futures

Replication of in vitro constructed viroid mutants: location of the pathogenicity-modulating domain of citrus exocortis viroid.

Abstract: Sequence variants from field isolates of citrus exocortis viroid (CEV) that cause either mild or severe symptoms on tomato plants have previously been classified into two groups, A and B. These groups differ primarily in two domains, PL and PR, of the proposed native structure. Infectivity studies with full-length cDNA clones of variants from each class have now directly confirmed the original correlation between Class A sequences and the severe phenotype and between Class B sequences and the mild phenotype. Direct evidence for this correlation could only be obtained by using individual sequence variants since field isolates of CEV have been shown to contain a mixture of RNA species. The construction and infectivity of chimaeric cDNA clones derived from mild and severe sequence variants of CEV has demonstrated that novel, infectious viroid molecules can be generated in vitro, and that PL is the pathogenicity-modulating domain. The role of the PR domain is not known but infectivity experiments with one chimaeric cDNA clone suggest that it may influence the efficiency of the infection or replication process of the viroid in the plant.

Effects of mycorrhizal infection on plant growth, nitrogen and phosphorus nutrition in glasshouse-grown allium cepal.

Abstract: SUMMARY Growth and rates of uptake of nitrogen and phosphorus (inflow) in Allium cepa L. were measured in three experiments. Effects of mycorrhizal infection (Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe) and N and P fertilization were investigated. The experiments were carried out in a naturally-lit glasshouse, so that seasonal variations in solar radiation influenced experimental results. In all experiments, a large positive growth response to mycorrhizal infection was observed when soil P was low. However, at high soil P smaller growth responses to infection were observed, as expected. Infection was associated with increased inflow of P, at all levels of soil P, even when non-mycorrhizal plants grew as well as or better than mycorrhizal plants. Lower P inflow was observed when infection was low and also at low irradiance in both mycorrhizal and non-mycorrhizal plants. The results show that mycorrhizal fungi increase the rate at which P is absorbed from soil, even under conditions which precluded a positive growth response to infection. In plants grown in spring and summer (two experiments), mycorrhizal infection was also associated with increased N inflow. N inflows in both mycorrhizal and non-mycorrhizal plants were lower in a third experiment in late winter and mycorrhizal infection had little or no effect on N inflow in this experiment. Increased N supply increased the inflow of N, concentrations of N in plant tissues and plant growth except in plants that were severely P limited, and there was no evidence that mycorrhizal infection alleviated N stress in low N plants. The results are discussed in relation to the environmental factors limiting plant growth, in particular nutrient uptake via and carbohydrate use by the fungal symbiont.