Showing papers by "University of Adelaide published in 1979"
TL;DR: In this article, a strong correlation exists between percent TiO 2 (proportional to amount of melting) and Al 2 O 3 /TiO 2, CaO/TiO2 ratios of these close to primary MORB, indicating a progressive release of Al and Ca from the mantle source.
693 citations
TL;DR: In this article, soil samples were fractionated by sedimentation in water and by flotation in heavy liquids to separate complexed and uncomplexed organic and inorganic components, and organic matter was concentrated in low density fractions in all separates.
263 citations
TL;DR: Aluminum-substituted hematites (Fez-xAlxO3) were synthesized from Fe-A1 coprecipitates at pH 5.5, 7.0, and in 10 -1, 10-2, and 10 -2 M KOH at 700C as mentioned in this paper.
Abstract: Aluminum-substituted hematites (Fez-xAlxO3) were synthesized from Fe-A1 coprecipitates at pH 5.5, 7.0, and in 10 -1, 10 -2, and 10 -2 M KOH at 700C. As little as 1 mole % AI suppressed goethite completely at pH 7 whereas in KOH higher AI concentrations were necessary. AI substitution as determined chemically and by XRD line shift was related to AI addition up to a maximum of 16-17 mole %. The relationship between the crystallographic ao parameter and AI sub- stitution deviated from the Vegard rule. At low substitution crystallinity of the hematites was improved whereas higher substitution impeded crystal growth in the crystallographic z-direction as indicated by differential XRD line broadening. At still higher AI addition crystal growth was strongly retarded. The initial AI-Fe coprecipitate behaved differently from a mechanical mixture of the respective "'hydroxides" and was, therefore, considered an aluminous ferrihydrite.
246 citations
TL;DR: In this paper, a method was devised for the extraction and measurement of adenosine 5'-triphosphate (ATP) in soil that minimizes sorption of ATP on the soil colloids.
Abstract: A method was devised for the extraction and measurement of adenosine 5'-triphosphate (ATP) in soil that minimizes sorption of ATP on the soil colloids. Soil was ultrasonified for 1 min with a solution containing trichloracetic acid (0.5 m). disodium hydrogen orthophosphate (0.25 m) and paraquat dichloride (0.1 m). The ATP content of the filtered extract was determined without further treatment in a scintillation spectrometer by the firefly luciferin-luciferase system. Recovery of added ATP was greater using the extratant containing trichloracetic acid, orthophosphate and paraquat than with trichloracetic acid alone or with a sulphuric acid extradant. Recoveries of added ATP ranged from 45% to 84% in thirteen different soils; ATP contents from 0.64 to 9.03 μg g−1 soil.
244 citations
TL;DR: By substituting mid-grey bars for the black bars in one region of a black-white grid, and for the white bars in another region, an apparent difference in the lightness of the grey bars in the two regions is produced.
Abstract: By substituting mid-grey bars for the black bars in one region of a black-white grid, and for the white bars in another region, an apparent difference in the lightness of the grey bars in the two regions is produced. The grey bars alternating with the white bars look much lighter than those alternating with the black bars (figure 1). The effect is stronger at higher spatial frequencies; the illusion is enhanced by observing figure 1 from a distance of a few meters. However, this illusion, unlike the assimilation effect investigated by Helson and others (e.g., Helson 1963), does not disappear at low spatial frequencies; the new illusion is still present when figure 1 is observed from a distance of only a few centimeters.
226 citations
TL;DR: In this article, a linear relationship between ATP content and biomass C content was found in a heterogeneous group of 11 soils, and the relationship between biomass C and ATP was found to be linear.
Abstract: In a heterogeneous group of 11 soils there was a linear relationship (r = 0.98) between ATP content and biomass C content, as measured by the fumigation technique. Biomass can be calculated from the ATP content using the relationship Biomass C in soil = 120 (ATP content of soil).
When a soil was fumigated and then incubated for 10 days, both biomass C and ATP fell to about one-fifth their initial values. Both biomass C and ATP increased in a soil incubated for 10 days with glucose, the relative increase in ATP being slightly greater than that in biomass.
168 citations
TL;DR: Diversity of honeyeaters is probably maintained by an interaction of two types of competition, exploitation and interference, whereas the smaller species can use poorer sources of nectar because their energy requirements are less (exploitation).
Abstract: Many species of honeyeaters and other nectar-feeding birds occur in most habitats in South Australia. They frequently feed on nectar of the same species of plants. A succession of species of plants provide nectar for birds throughout the year. Nectar is most abundant in winter and early spring and least abundant in summer and autumn. There is more nectar per flower and more flowers in winter and spring. Nectar is often depleted by honeyeaters, and sometimes other visitors (silvereyes, lorikeets and insects) between December and May. It is at times reduced to a level at which it is uneconomical for some species to exploit. There are seasonal movements of honeyeaters into areas of abundant nectar and out of these areas when nectar becomes scarce. Breeding coincides with peak abundance of nectar.
Diversity of honeyeaters is probably maintained by an interaction of two types of competition, exploitation and interference. The larger species use the richest sources of nectar and aggressively exclude the smaller species (interference) whereas the smaller species can use poorer sources of nectar because their energy requirements are less (exploitation).
130 citations
TL;DR: In this paper, a numerical method is presented for the computation of two-dimensional periodic progressive surface waves propagating under the combined influence of gravity and surface tension, where the dynamic boundary equation is used in its exact nonlinear form.
Abstract: A numerical method is presented for the computation of two-dimensional periodic progressive surface waves propagating under the combined influence of gravity and surface tension. The dynamic boundary equation is used in its exact nonlinear form. The procedure involves a boundary-integral formulation coupled with a Newtonian iteration. Solutions of high accuracy can be achieved over much of the range of wavelengths and heights including limiting waves. A number of different continuous families of solutions have been produced, all of which ultimately exhibit closed bubbles at their troughs. The so-called critical wavelengths are less important than have been previously assumed; the number of possible wave forms does increase with increasing wavelength, however.
122 citations
TL;DR: In all test situations candidates’ scores were significantly higher in the objective tests than in the free‐response tests, and the cueing effect of the options was thought to be the main factor responsible for the difference in performance.
Abstract: Summary
This paper reports a study which compared the performance of different groups of students and doctors on identical and equivalent tests set in an objective-type format and in a free-response format. The tests were designed to ensure that the content was relevant to clinical practice at the hospital intern level. In all test situations candidates’ scores were significantly higher in the objective tests than in the free-response tests. This difference was greater for the more junior and less competent students than for the more competent doctors. The cueing effect of the options was thought to be the main factor responsible for the difference in performance.
The results of a questionnaire survey demonstrated that students were aware of the deficiencies in multiple-choice tests. A large majority of the students believed that the free-response tests gave a more accurate assessment of their clinical ability.
It was found that in these tests, aimed at measuring aspects of clinical competence, multiple-choice questions appeared to overestimate the candidate's ability to an extent that made them less suitable than free-response questions for this purpose. It was also found that free-response tests, of the type used in this study, provide a suitable alternative to multiple-choice tests for use in the written section of clinical examinations. It was concluded that the written component of the final examination in the medical course should have a preponderance of free-response items over multiple-choice items.
107 citations
TL;DR: A review of the Australian Tertiary geohistory record is based on planktonic foraminiferal biostratigraphy and its evidence for recognizing four sequences with intervening hiatuses, regression or non-identification as discussed by the authors.
96 citations
TL;DR: In this article, Ferrihydrite was transformed to goethite and/or hematite at various temperatures, (OH), and IAl, and a straight line was obtained for all preparations independent of (OH).
Abstract: Ferrihydrite was transformed to goethite and/or hematite at various temperatures, (OH), and IAl). Increasing temperature and (AI) favored hematite, increasing (OH) favored goethite. A given (AI) induces hematite more effectively at lower (OH). AI substitution in goethites increased linearly with log(All, but was independent of temperature. At a givea (All, substitution increased with decreasing (OH). In a plot of AI/Fe in the goethite against (AI)/(Fe(OH)C) in solution a straight line was obtained for all preparations independent of (OH).
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TL;DR: A decision-theoretic model of the decision to adopt a process innovation is developed and used to derive a simple result for the time lag from a decision maker's first knowledge of the innovation to his first use of it.
TL;DR: Evidence is presented that Avirulent transconjugants which produced agrocin 84 varied in their effectiveness as biological control gents, probably due to variation in rate of growth of the different strains in the inoculation sites.
Abstract: The role of the bacteriocin, agrocin 84, in the biological control. of crown gall was investigated by constructing new bacteriocinogenic strains. A small plasmid which codes for the ability to produce agrocin 84 has been identified and transferred to recipient strains by conjugation. Two donor strains were used; the avirulent strain 84 and the virulent strain 398. Agrocin production and virulence in the latter strain have been separated by genetic manipulation and avirulent, agrocin producing derivatives have been produced. Avirulent transconjugants which produced agrocin 84 varied in their effectiveness as biological control gents. Evidence is presented that this was probably due to variation in rate of growth of the different strains in the inoculation sites.
TL;DR: Establishment of vesicular-arbuscular mycorrhizal fungi in plant roots involves a pre-infection phase of propagule germination, hyphal growth and appressorium formation, followed by growth of the fungus within theRoot, with best development at 16°C for both host Rhizobium combinations in non-sterile and autoclaved soil.
Abstract: Establishment of vesicular-arbuscular mycorrhizal fungi in plant roots involves a pre-infection phase of propagule germination, hyphal growth and appressorium formation, followed by growth of the fungus within the root. The effect of soil temperature on the pre-infection stage was examined by counting the numbers of fungal “entry-points” on the main roots of Medicago truncatula and Trifolium subterraneum, grown at soil temperatures of 12°, 16°, 20° and 25°C for periods up to 12 days. Increased root temperature was positively associated with increased numbers of “entry-points”. This effect was more marked between 12° and 16°C than at higher temperatures, as shown by comparing plants at the same stage of development (emergence of spade leaf) and by calculating the results as entry points per cm root. The first root nodules appeared sooner at higher temperatures (20° and 25°), but subsequent development of nodules (measured as nodule number and aggregate volume of nodules per plant, up to 21 days) was best at 16°C for both host Rhizobium combinations in non-sterile and autoclaved soil. There was no evidence that competition between mycorrhizal fungi and Rhizobium for infection sites occurred. A method of obtaining numbers of infective propagules of vesicular-arbuscular mycorrhizal fungi in soil is described.
TL;DR: Comparisons of the two RNAs by hybridization analysis using 32P-labelled complementary DNA probes indicate that they have partial nucleotide sequence homology, and it is suggested that the difference in their primary structure is reflected in their biological properties.
TL;DR: A viroid has been purified from avocado leaves infected by sunblotch disease and designated the avocado sunblots viroid, a covalently closed circular RNA molecule with a molecular weight lower than that of chrysanthemum stunt viroid and citrus exocortis viroid while hybridization analysis with 32P-labeled complementary DNA indicated that it is a single RNA species.
TL;DR: The structural evidence reported here shows that a 5′-phosphoryl linkage from the ‘fraudulent’ nucleoside core 9-(3′-deoxy-β-D-threo-pentofuranosyl) adenine6 to the amide group of D-thReo-2,3-dihydroxy-4-methylpentanamide is required for antibiotic activity, but bacteriocin-like specificity is conferred by
Abstract: AGROCIN 84 (Fig. 1(1)) is the active factor1 in the biological control of crown gall, a plant cancer induced by certain strains of Agrobacterium. Growth inhibition by agrocin 84 has been correlated with pathogenicity2–5 and the presence of a nopaline (N2-(1,3-dicarboxypropylarginine)) tumour-inducing plasmid3–5. Characterisation of agrocin 84 as a disubstituted adenine nucleotide6 has been reported and a proposed7 peptide structure has been retracted8. What are those salient features of agrocin 84 that determine its remarkable bacteriocin-like specificity towards cancer-inducing strains of Agrobacterium? The structural evidence reported here shows that a 5′-phosphoryl linkage from the ‘fraudulent’ nucleoside core 9-(3′-deoxy-β-D-threo-pentofuranosyl) adenine6 to the amide group of D-threo-2,3-dihydroxy-4-methylpentanamide (Fig. 1(6)) is required for antibiotic activity, but bacteriocin-like specificity is conferred by a D-glucofuranosyloxyphosphoryl substituent at N6 of adenine. Agrocin 84 seems to be the harbinger of a series of highly specific nucleotide bacteriocins, which behave as molecular ‘Trojan horses’.
TL;DR: A method is described whereby hydroxylamine produced during the oxidation of ammonia by Nitrosomonas is isolated directly as an oxime and stable isotopes are employed to show that ‘sNH&l is oxidised to “NH,OH and that the oxygen of hydroXYlamine is derived from ‘802 and not from HzlsO.
TL;DR: Although males and females of two strains, C3H/HeJand CBA/H were equally susceptible to a primary infection, the females developed better resistance than the male mice following two oral administrations of third stage larvae.
Abstract: Infection by the intestinal nematode parasite Nematospiroides dubius was studied in seven different inbred mouse strains. Although there was some minor variation in the susceptibility of the different strains to a primary infection there were marked differences in their ability to develop resistance to infection following repeated exposure to infective larvae. The strains of mice which developed the best resistance also expelled adult worms arising from the previous infections. The adult worms resulting from a primary infection were slowly eliminated in two inbred strains studied whereas no loss occurred from outbred LACA mice. Although males and females of two strains, C3H/HeJ and CBA/H were equally susceptible to a primary infection, the females developed better resistance than the male mice following two oral administrations of third stage larvae. Infected mice of every strain and both sexes contained high levels of IgG1 in the serum.
TL;DR: Evidence is presented that the IgG1 antibodies are not only haemolytic in the presence of C, but that they apparently account for more than half of the SRBC-specific, C-fixing IgG antibodies in the serum of the immunised animals.
Abstract: Four IgG isotypes (IgG1, IgG2a, IgG2b, IgG3) have been distinguished in the mouse1–3. The similarity of the physico-chemical properties of the different isotypes has to a large extent prevented their purification from serum and this has complicated functional studies on IgG antibodies in sera from infected or immunised mice1,2,4. The availability of immunoglobulin-secreting plasmacytomas5, however, has made the production of isotype-specific antisera possible; the use of these antisera has shown immunoglobulin of each isotype to exist in sera from normal animals3,5,6. IgG1 antibodies, partially separated from IgG2 by electrophoresis in agar, have been reported2 to be incapable of sensitising sheep red blood cells (SRBC), passively coated with antigen, for lysis by complement (C) although the antibodies agglutinated the cells and also mediated passive cutaneous anaphylactic (PCA) reactions in the mouse. The IgG2 antibodies, which mediated PCA reactions in the guinea pig but not in the mouse, lysed the antigen-coated SRBC in the presence of mouse C. It seems on the basis of this single report that mouse IgG1 has been widely accepted6–8 to be a ‘non-C-fixing’ class of immunoglobulin—one which, on association with antigen, is unable to activate C. We have now purified IgG1 from the serum of mice immunised with SRBC and in this report present evidence that the IgG1 antibodies are not only haemolytic in the presence of C, but that they apparently account for more than half of the SRBC-specific, C-fixing IgG antibodies in the serum of the immunised animals.
TL;DR: In this article, it was shown that when averaged in 1000 year intervals, the archaeomagnetic intensity data for the past 5000 years can be interpreted in terms of a change in the intensity of the dipole field.
TL;DR: It appears that the IBQ may be successfully utilized as a screening instrument in General Practice populations to identify patients manifesting abnormal illness behaviour.
TL;DR: In this paper, a zircon study has been made on eleven samples of igneous rocks from the Saudi Arabian Craton, and a narrow time range of 660 to 665 million years was indicated for ages of widely separated and compositionally different intrusive bodies all to the east of the An Nimas Bathylith.
Abstract: A zircon study has been made on eleven samples of igneous rocks from the Saudi Arabian Craton. Ages of sized and magnetic fractions of zircon concentrates show variable degrees of discordance which seem to result from a very young disturbance that produces linear arrays in the Concordia plot. Model age calculations based on a statistically and geologically reasonable lower intercept produce very consistent internal relationships. The Pan African Orogeny, considered to be responsible for loss of radiogenic argon and strontium from minerals of many rocks, does not appear to have affected the zircon data, even though uplift had exposed the rocks of the Arabian Shield at that time. Tonalite, granodiorite, and crosscutting leucoadamellite bodies in the southern part of the An Nimas Bathylith yield ages in the time range 820−760 Ma. A narrow time range of 660 to 665 million years was indicated for ages of widely separated and compositionally different intrusive bodies all to the east of the An Nimas Bathylith. This work suggests that the younger end of the age spectrum established from regional K-Ar and Rb-Sr measurements may be underestimated, and that magmatic activity could be more episodic than previously assumed.
TL;DR: The successful serial cultivation of cervical epithelium, HCE, depends upon the presence of a non‐dividing fibroblast feeder layer which provides both attachment and growth factors for epithelial cells.
Abstract: Diploid cells derived from the portio surface of the cervix uteri of adult women can be grown in culture, from single cells. Ultrastructurally the colonies of growing cells show the features of stratified squamous epithelium and exhibit some of the differentiated characteristics of this epithelium in vivo. The successful serial cultivation of cervical epithelial cells, HCE, depends upon the presence of a non-dividing fibroblast feeder layer which provides both attachment and growth factors for epithelial cells. Lethally irradiated Wi-38, cervical fibroblasts or mouse fibroblast lines are all effective in promoting HCE colony formation and growth. Hydrocortisone and epidermal growth factor increase HCE colony size in the presence of a feeder cell layer. Culture lifetime was studied in five strains and ranged from 20-38 population doublings, with cells from older patients exhibiting a shorter culture life-time.
TL;DR: The method involves the in vitro labeling of proteins by reductive methylation using formaldehyde and high specific activity [3H]potassium borohydride and allows the analysis and molecular weight estimation of submicrogram quantities of protein.
TL;DR: In this article, the reaction of [Ru(C:CHPh)(PPh 3 ) 2 (η-C 5 H 5 )] + with MeOH, aqueous HBF 4 or O 2 afford complexes containing disubstituted vinylidene ligands.
TL;DR: Carnarvon's scheme for a South African Confederation in the 1870s owed much more than has been generally recognized to influences emanating from Natal as mentioned in this paper, where Theophilus Shepstone, Natal's Secretary for Native Affairs, used all the resources at his disposal to smooth the way for migrant labour.
Abstract: Lord Carnarvon's scheme for a South African Confederation in the 1870s owed much more than has been generally recognized to influences emanating from Natal. Large employers of African labour recognized in the 1860s that the local population could not provide a cheap stable workforce and that immigrant workers from the African interior would be increasingly important to the prosperity of the colony. Theophilus Shepstone, Natal's Secretary for Native Affairs, used all the resources at his disposal to smooth the way for migrant labour. The development of diamond mining in Griqualand West and, to a lesser extent, gold mining in the Lydenburg district of the Transvaal diverted large numbers of African workers away from Natal and set off a frantic search for new sources of labour which underscored the importance of Mocambique and Central Africa as reservoirs of black labour. While planters, traders and officials in Natal worked to keep labour supply routes open between the Transvaal and Portuguese territory, officials in Griqualand West were recommending annexation of territories along the ‘missionary road’ in order to stop Transvaal Afrikaners from blocking labour supply routes from Central Africa. The revival of an active British campaign against the East African slave trade opened another potential source of African labour which Shepstone's former border agent Frederic Elton tried to divert to Natal while serving first as an assistant to Sir Bartle Frere and John Kirk in Zanzibar, and later as British Consul in Mocambique.Shepstone arrived in London at a crucial point in the development of Carnarvon's thinking on southern African affairs and impressed him with his lucid analysis of the interrelation of African administration, economic development and labour supply. Carnarvon's plans for confederation reflected the advice which he was continously receiving from Shepstone and Elton. Their argument for confederation emphasized the essentially unitary nature of the developing southern African economy.
TL;DR: Using accurate binary diffusion coefficients obtained over a temperature range of 275 to 323 K, together with some excellent second virial coefficients in the literature, (m, 6, 8) potential parameters have been obtained for the systems He-Ne, He-Ar, H-Ar and H-Xe.
Abstract: Using accurate binary diffusion coefficients obtained over a temperature range of 275 to 323 K, together with some excellent second virial coefficients in the literature, ( m , 6, 8) potential parameters have been obtained for the systems He-Ne, He-Ar, He-Kr, He-Xe, Ne-Ar, Ne-Kr, Ne-Xe, Ar-Kr and Ar-Xe. These parameters accurately predict all the precise binary transport properties which have been reported for these systems, some over a range of 1400 K. The present analysis indicates that these mixtures are not conformal with any one of the assumed ( m , 6, 8) group of potentials.
TL;DR: In this article, the linearized problem of water-wave reflexion by a thin barrier of arbitrary permeability is considered with the restriction that the flow be two-dimensional, and a representative range of solutions are obtained numerically for both finite and infinite depth problems.
Abstract: The linearized problem of water-wave reflexion by a thin barrier of arbitrary permeability is considered with the restriction that the flow be two-dimensional. The formulation includes the special case of transmission through one or more gaps in an otherwise impermeable barrier. The general problem is reduced to a set of integral equations using standard techniques. These equations are then solved using a special decomposition of the finite depth source potential which allows accurate solutions to be obtained economically. A representative range of solutions is obtained numerically for both finite and infinite depth problems.
TL;DR: At high infusion rates the cholestatic effects of the bile salts were revealed and the relative toxicity of thebile salts was seen to be TDC>TCDC >TC.
Abstract: In rats, at low infusion rates taurocholate (TC), taurochenodeoxycholate (TCDC) and taurodeoxycholate (TCD) each produced an increase in bile flow of 20-50%. However, at high infusion rates (5-20 mumoles min-1kg-1) the cholestatic effects of the bile salts were revealed and the relative toxicity of the bile salts was seen to be TDC greater than TCDC greater than TC.