Showing papers by "Griffith University published in 1986"

Pleistocene occupation in the south-east Queensland coastal region

Abstract: An open site at Wallen Wallen Creek, North Stradbroke Island has revealed a deep (≥2.5 m) stratified archaeological deposit which yielded radiocarbon dates of Pleistocene age. These results are the first evidence of Pleistocene human occupation in south-east Queensland, and the first evidence of Pleistocene occupation of the Australian east coast, north of the Sydney region. The deposit suggests a continuous occupation throughout the Pleistocene, with a dramatic increase in occupation intensity during the late Holocene. Evidence for the continuous occupation of the nearcoastal zone during the Pleistocene makes this site unique in the archaeological record of east-coast Australia.

[Ba$_x$Cs$_y$][(Ti,Al)$^{3+}_{2x + y}$Ti$^{4+}_{8 - 2x - y}$]O$_{16}$ Synroc-Type Hollandites. I. Phase Chemistry

Abstract: A series of \[Ba$\_x$Cs$\_y$\]\[(Ti,Al)$^{3+}\_{2x+y}$Ti$^{4+}\_{8-2x-y}$\]O$\_{16}$ hollandites, synthesized at 1250 $^\circ$C and coexisting with 'reduced' rutile, demonstrates complete solid solution between barium and caesium endmembers, and simultaneously between Ti$^{3+}$ and Al$^{3+}$. The presence or absence of rutile has only a minor effect on stoichiometry. For barium endmember hollandites (y = 0) the stoichiometry (i.e. tunnel site occupancy) ranges from 1.08 $\leqslant$ x $\leqslant$ 1.14, whilst for caesium endmember hollandites (x = 0) 1.32 $\leqslant$ y $\leqslant$ 1.51. Neither x nor y correlates with the nature and proportions of trivalent species. An appropriate stoichiometry for the aluminous barium end-member is confirmed as Ba$\_{1.14}$Al$\_{2.29}$Ti$\_{5.71}$O$\_{16}$. The composition BaO. Al$\_2$O$\_3$. 5TiO$\_2$ yields this same hollandite, and not the supposed phase 'BaAl$\_2$Ti$\_5$O$\_{14}$'. The phase 'BaAl$\_2$Ti$\_4$O$\_{12}$' does not exist, while the composition BaO. Al$\_2$O$\_3$.4TiO$\_2$ crystallizes to an assemblage containing the hollandite mentioned above. Reinterpretation of published X-ray diffraction data substantiate these conclusions and are consistent with a 5c supercell for hollandite. Superlattice ordering in \[Ba$\_x$Cs$\_y$\] \[(Ti,Al)$^{3+}\_{2x+y}$Ti$^{4+}\_{8-2x-y}$\]O$\_{16}$ hollandites may be commensurate or incommensurate, with typical multiplicity values (m) and tunnel-site occupancies (x+y) correlating with increasing caesium content per formula unit throughout the series. Barium end-members and barium-rich hollandites, with Cs$^+ \leqslant$ 0.33 and tunnel-site occupancies of 1.03-1.15 display 4.5 $\leqslant$ m $\leqslant$ 5.0. Intermediate hollandites with 0.40 $\leqslant$ Cs$^+ \leqslant$ 0.70 and tunnel-site occupancies ranging from 1.14 to 1.23 possess superstructures with 5.5 $\leqslant$ m $\leqslant$ 5.7, whereas caesium endmembers and caesium-rich hollandites have tunnel-site occupancies between 1.12 and 1.51 and 5.9 $\leqslant$ m $\leqslant$ 6.3. For barium or caesium endmembers, multiplicities fail to correlate with tunnel-site occupancies, but do increase with increasing percentages of molar Al$^{3+}$/(Al$^{3+}$ + Ti$^{3+}$) in the structure. Superlattice periodicity is considerably more sensitive to changes in the barium-caesium content of tunnel sites than to variation in the nature of the trivalent species. Long-range superlattice order is determined not so much by the tunnel cations as by the trivalent species. With more than about one Al$^{3+}$ per formula unit, one-dimensional (uncorrelated) ordering is suppressed, and three-dimensional order occurs almost exclusively. Hollandite superstructures, and thus their stoichiometries, are determined both by mutual repulsion between large cations within individual tunnels, and intertunnel interaction between large cations. The ceramic high-level nuclear waste form, Synroc, contains a titanate hollandite belonging to the above series. It has been suggested that the capacity of Synroc to immobilize caesium may be impaired if caesium and barium are not incorporated solely in hollandite, but are partitioned between hollandite and additional titanate phases or hollandite-related structures. No such phase has been encountered in the synthesis of the above hollandite series or in Synroc, prepared according to current specifications, because the trivalent species are present in sufficient abundance to allow the incorporation of all barium and caesium in hollandite. Consequently two-component titanates (for example Cs$\_2$Ti$\_6$O$\_{13}$ or Ba$\_2$Ti$\_9$O$\_{20}$), do not appear in the phase assemblage. Moreover, the trivalent species do not comprise Al$^{3+}$ alone but also include some Ti$^{3+}$, which promotes more favourable structural modifications and kinetics. Furthermore, the phase assemblage includes 'reduced' rutile, which effectively prohibits crystallization of two-component titanates with \[Ba,Cs]/[Ti] ratios higher than that in hollandite, and also three-component [Ba,Cs\] \[Ti,Al\]$^{3+}$-titanates other than hollandite. When these three criteria are satisfied, the appearance of additional, potentially undesirable phases in the Synroc mineralogy is suppressed, and all barium, caesium (and rubidium) may be successfully immobilized in hollandite.

Evidence for predation as a factor in determining shell color frequencies in a mangrove snail littorina sp. (prosobranchia: littorinidae).

Abstract: It was hypothesized that in Littorina populations living on Avicennia marina in Moreton Bay, Queensland, yellow shelled individuals are at a selective advantage over other shell colors and that this advantage is due to differential selection by predators. Yellow shelled individuals were more likely to be recaptured than others, indicating a higher survival rate of yellows. When predation was restricted on ten mangrove trees, the apparent advantage of yellow shells was removed. After 18 months, the relative frequency of yellow shelled individuals was significantly lower on experimental trees than on control trees. A combi- nation of selection for crypsis and for the less common morph is suggested as the mechanism maintaining the high levels of variation in this species.

On the multiplicity of the enzyme catalase in mammalian liver.

Abstract: The literature on the complex multiplicity of mammlian catalase and the nature of the epigenetic modifications undergone by this enzyme has been reviewed, along with relevant comment on the subcellular localization and biological role of the enzyme. The epigenetic causations of multiplicity are established as being multifactorial and include oxidoreductive conversions of sulphydryl groups, the covalent attachment of carbohydrate, and partial proteolysis of the enzyme. Each of these epigenetic transformations may give rise to sets of multiple forms, and overlaps between these separate sets may give rise to extremely complex multiplicity patterns. It is concluded that any interpretation of catalase multiplicity which places emphasis on a single epigenetic causation is not compatible with the scope and variety of the available data on this enzyme. Instead, a holistic approach is urged — one giving due emphasis to the multiple causation of catalase multiplicity, and the interrelationships of these causations in the cellular situation. Rather than viewing the multiplicity of this enzyme as merely a series of interesting chemical modifications, emphasis is directed towards the fact that catalase heterogeneity povides a sensitive indication of the functional variations which occur within separate compartments of the subcellular structure, and hence becomes an essential element in any satisfactory understanding of the role of this enzyme in cellular processes.

Rates of ammonium turnover and the role of amino-acid deamination in seagrass (Zostera capricorni) beds of Moreton Bay, Australia

Abstract: Samples of sediments from Australian seagrass (Zostera capricorni Aschers.) beds were taken in June to August 1983 (for15N experiments) and November 1982 to January 1983 (14N experiments). The ammonium pool turned-over every 0.4 to 0.8 d, as determined with a15N isotope-dilution technique. The ammonium pool in subtidal bare areas turned-over two to three times more slowly than in adjacent seagrass beds. Gross rates ofin situ ammonium regeneration equalled those of utilization, and ranged from 0.04 to 0.35 μmol cm-3 d-1, or from 50 to 490 mg N m-2 d-1 over the upper 10 cm of the sediment. The potential rate of glycine utilization, measured with a large excess of glycine added to anaerobic incubations, ranged from 0.21 to 0.39μmol cm-3 d-1, butin situ rates were probably much lower. Between 35 and 65% of added15N-glycine was deaminated over 12 h, and the remainder was most likely assimilated by microbes. Evidence for the seagrasses taking up glycine was equivocal, owing to the rapid deamination of the amino acid and the likelihood that they assimilated the labelled ammonium produced from the glycine.

Distribution of the immature stages of Aedes vigilax on a coastal salt-marsh in south-east Queensland

Abstract: The distribution of eggs and larvae of Aedes vigilax was studied on part of a coastal salt-marsh in south-east Queensland. At the macro-scale (8 ha area), the largest numbers of larvae hatched were from samples taken in areas with relatively low open vegetation adjacent to drainage channels. Such areas are likely to be suitable for egg conditioning and hatching and are also accessible to adult mosquitoes. At the micro-scale (the environs of two small pools), most hatching occurred in narrow bands at specific elevations from the pool bottom but the relationship with vegetation was variable. Failure to hatch larvae from samples taken at the start of, or during, the cooler months was thought to be associated with egg diapause. At the macro-scale whilst the marsh was flooded, most larvae were found in two habitat types: the tall dense Sporobolus virginicus in relatively elevated locations and in depressions dominated by Sarcocornia quinqueflora. At the meso-scale (on a 1.4 ha grid) the distribution of larvae was found to be further related to water movement. Most larvae were in areas of slower water movement and appeared also to be redistributed by tides.

Problem definition and thesis writing

Abstract: The purpose of this paper is to present some innovative solutions to major problems experienced by coursework postgraduate students. The paper focusses on two key problem areas: the definition of the research problem, and the planning and writing of the first draft of the thesis. It is argued that one approach which can assist the student to overcome these problems is the workshop; research skills can be developed through the practical guidance, group-support, discussion and reflection which occur in the workshop context. The authors' experiences in conducting postgraduate workshops at Griffith University are discussed, and student evaluation of the workshops presented.

Intergranular Films and Pore Surfaces in Synroc C: Structure, Composition, and Dissolution Characteristics

Abstract: Structure et composition chimique des films intergranulaires, points triples et microvides dans le synroc C (ceramique de titanate utilisee pour la solidification des dechets hautement radioactifs). Correlations entre les caracteristiques microstructurelles et les phenomenes de lixiviation a court terme

Classification of reflectance on colour infrared aerial photographs and sub-tropical salt-marsh vegetation types

Abstract: Large-scale colour infrared aerial photographs were obtained for part of a tropical coastal salt-marsh in south-east Queensland, Australia. Print reflectances were classified using a numerical divisive hierarchical procedure and related to field data. Vegetation characteristics such as species, size, dry weight and density were significantly associated with each spectral class al the general (macro) and at the detailed (micro) scales. At the macro scale there were four vegetation types: pure stands of tall Sporobolus virginicus; medium-tall Sporobolus dominant but with some Sarcocornia quinqueftora; a mixed type; and finally a type dominated by Sarcocornia. At the micro scale vegetation types were further differentiated by size and dry weight of the two dominant species.

Scientific Method And The Rhetoric of Science In Britain, 1830–1917

Abstract: The Tribune of October 1945 carried a contribution from George Orwell entitled ‘What is Science’? While noting that this question could be answered by referring to the body of knowledge about the natural world, Orwell perceived that science had also come to denote a ‘method of thought’. Alluding to the contemporary debate about curriculum content, he suggested that the demand for more science education involved ‘the claim that if one has been scientifically trained one’s approach to all subjects will be more intelligent than if one had no such training.1 At this point, Orwell identified an important theme in the public rhetoric of science — the appeal to what Beatrice Webb called the ‘cult of the scientific method’.2 This phenomenon was enshrined in Karl Pearson’s Grammar of Science, published in 1892, in which he declared that the ‘scientific habit of mind’, apart from the intellectual triumphs it had accomplished since the seventeenth century, was now called upon to play a vital historical role in a period of rapid social and political change.

Nitrate metabolism in sediments from seagrass zostera capricorni beds of moreton bay australia

Abstract: The fate of nitrate in sediments from seagrass (Zostera capricorni Aschers.) beds of Moreton Bay on the subtropical eastern coast of Queensland, Australia, was investigated. Added nitrate was metabolised at rates of 0.4 to 3.4 μg N cm-3 d-1 when sediments were incubated under anaerobic conditions with a large excess of nitrate. The potential rate of nitrate utilization was as rapid in sediments from subtidal bare areas as from adjacent seagrass beds. Ammonium was produced rapidly from15N-nitrate by microbial action in all the subtidal sediments examined. After 12 h of incubation, 13 to 28% of the15N initially added as labelled nitrate was detected as labelled ammonium in the sediments. Denitrification, although not measured directly, appeared to be a relatively minor fate of nitrate. Benthic microbes took up large amounts of15N but only after a delay of 6 h; this pattern could have been due to induction and synthesis of the enzymes necessary for nitrate uptake, and the assimilation of labelled ammonium. Under field conditions, assimilation by seagrasses and denitrification by bacteria were probably not significant sinks for nitrate in comparison with uptake by benthic microbes and dissimilatory reduction to ammonium.

Catch rate and emergence of male and female spanner crabs (Ranina ranina) in Australia

Abstract: Catches of the spanner crab, Ranina ranina (Linnaeus, 1788), in southern Queensland, Australia in 1982 and 1983 showed a seasonal cycle, with peak catches from August to September. In most catches, males outnumbered females. Catches of both male and female spanner crabs declined in November and December, when a high proportion of females caught were ovigerous. Fish, echinoderms and polychaetes were the main food items. Closed-circuit time-lapse video recording was used to study the emergence behaviour of R. ranina in a 6 m-diameter tank. Spanner crabs in this tank were buried most of the time, emerging on average for only 1.7 h d-1. They emerged mainly between 16.00 and 24.00 hrs and, less often, between 01.00 and 15.00 hrs. Males remained emerged significantly longer than females. The duration of emergence of the females peaked before the spawning season, becoming shorter during the period when they were ovigerous. Temperature and emergence were negatively correlated. It is concluded that reproductive behaviour has a strong influence on catch composition of spanner crabs.

[Ba$_x$ Cs$_y$] [(Ti,Al)$^{3+}_{2x+y}$ Ti$^{4+}_{8-2x-y}$] O$_{16}$ Synroc-Type Hollandites II. Structural Chemistry

Abstract: High-resolution transmission electron microscopy and selected-area electron diffraction show that all phases of the general formula \[Ba$\_x$Cs$\_y$\] \[(Al, Ti)$^{3+}\_{2x+y}$ Ti$^{4+}\_{8-2x-y}$\]O$\_{16}$, 1.08 $\leqslant$ x+y $\leqslant$ 1.51 have the hollandite-type substructure. These hollandites display commensurate and incommensurate superlattices owing to the ordered insertion of large cations (Ba$^{2+}$, Cs$^+$) into the (2, 2) tunnel interstices of the octahedral (Al, Ti) O$\_6$ framework. Multiplicity (m) of a supercell is defined as d$\_{\mathrm{supercell}}$ divided by d$\_{002}$ for the subcell. Ordering may be one-dimensional, in which case the cation sequences between (2, 2) channels are independent, three-dimensional with lateral correlation between tunnels, or a combination of both. One-dimensional superstructures yield commensurate multiplicities of 4 in all phases except an aluminous caesium hollandite where m = 6. Three-dimensional superstructures are both incommensurate and commensurate, with 4.5$\_0$ $\leqslant m \leqslant$ 6.5$\_9$. Multiplicities correlate directly with caesium content per formula unit, establishing a maximum in caesium-rich hollandites. Among barium ($y$ = 0) and caesium endmembers, ($x$ = 0) multiplicities increase modestly with increasing Al$^{3+}$: (Al + Ti)$^{3+}$ content. Superstructure dimensionality is largely determined by the nature and proportions of the trivalent species, rather than the tunnel cations; one-dimensional order is commonplace in hollandites rich in trivalent titanium but rare in aluminous hollandites. High-resolution electron microscopy supports the interpretation of incommensurate superstructures as fine-scale intergrowths of commensurate microdomains with $m$ = 4, 5, 6 or 7. For aluminous hollandites, rare examples of structural modifications involving tunnels of different cross-sectional dimensions may be found, i.e. T(2, $n$), 1 $\leqslant n \leqslant$ 3 intergrowths. As all specimens are sensitive to the electron beam, prolonged irradiation at high electron fluxes can initiate the transformation of single-crystal hollandite to single-crystal rutile. A mechanism for this transformation is proposed, whereby the hollandite crystals initially adjust their multiplicity to six. Growth fronts on {101}$\_{\mathrm{holl}}$ subsequently propagate through the crystals consuming hollandite and leaving rutile: the structure of the interface between the phases is believed to contain components of rutile possessing antiphase boundaries. In this reconstructive transformation, \[100] of the newly formed rutile invariably lies almost parallel to [110] of the original hollandite. Less severe electron irradiation or argon ion beam milling causes crystals to twin polysynthetically. The superlattice properties of [Ba$\_x$ Cs$\_y$\] \[(Ti, Al)$^{3+}\_{2x+y}$ Ti$^{4+}\_{8-2x-y}$\] O$\_{16}$ hollandites are integrated with those of other hollandites to identify and evaluate the factors responsible for the stoichiometries and preferred superstructures of hollandites in general. These factors include electrostatic repulsion between large cations in the same tunnel, interaction between cations in neighbouring tunnels, the shielding capacity of the octahedral framework, and kinetic effects.

Genetic marker patterns and endogenous mammary tumor virus genes in inbred mouse strains of Japan.

Abstract: In order to establish the genetic relatedness of the inbred mouse strains kept in Nara, genetic marker patterns were determined in conjunction with a study on endogenous mammary tumor viral genes in these strains. Isoenzyme patterns combined with patterns of other genetic markers, show that the unrelatedness between various inbred strains of the dd stock is as high or even higher as between strains of known different origin and geneology. Based on endogenous viral gene patterns the dd stock derived mice can be subdivided into three group, DDD, DDN, DDO, KF and DD/Tbr. The DD/Tbr and its foster-nursed substrain (DD/Tbrf) have the lowest number of endogenous viral genes, i.e. two, while the other strains carry 4-6 such genes. The SLN and SHN strains, derived from a Swiss stock, have a similar pattern of viral genes different that of all other strains studied, also strains of Swiss origin from other sources, such as the NFS and the GR.

Aliphatic hydrocarbons in Great Barrier Reef organisms and environment

Abstract: This investigation was undertaken to assess the chemical nature, occurrence, and possible origin of petroleum hydrocarbons in the Great Barrier Reef ecosystem Aliphatic hydrocarbons in surface sediments, water, and a suite of seven species from widely separated coral reefs in the Great Barrier Reef area were analysed by gas chromatography, and by gas chromatography coupled with mass spectrometry The hydrocarbons found were substantially of biogenic origin The major components were n-pentadecane, n-heptadecane, pristane and mono-alkenes based on heptadecane, and were believed to originate from benthic algae and phytoplankton There was no evidence to suggest that lipid content had any influence on hydrocarbon content Hydrocarbons from the organisms and sediments have characteristic composition patterns which would be altered by the presence of petroleum hydrocarbons An unresolved complex mixture, usually considered indicative of petroleum contamination, was found in greater than trace amounts only in Holothuria (sea cucumber) and Acropora (coral) from the Capricorn Group, and in some sediment samples from the Capricorn Group and Lizard Island area