Showing papers by "Australian National University published in 1986"

Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins

Abstract: The graywackes of Paleozoic turbidite sequences of eastern Australia show a large variation in their trace element characteristics, which reflect distinct provenance types and tectonic settings for various suites. The tectonic settings recognised are oceanic island arc, continental island arc, active continental margin, and passive margins. Immobile trace elements, e.g. La, Ce, Nd, Th, Zr, Nb, Y, Sc and Co are very useful in tectonic setting discrimination. In general, there is a systematic increase in light rare earth elements (La, Ce, Nd), Th, Nb and the Ba/Sr, Rb/Sr, La/Y and Ni/Co ratios and a decrease in V, Sc and the Ba/Rb, K/Th and K/U ratios in graywackes from oceanic island arc to continental island arc to active continental margin to passive margin settings. On the basis of graywacke geochemistry, the optimum discrimination of the tectonic settings of sedimentary basins is achieved by La-Th, La-Th-Sc, Ti/Zr-La/Sc, La/Y-Sc/Cr, Th-Sc-Zr/10 and Th-Co-Zr/10 plots. The analysed oceanic island arc graywackes are characterised by extremely low abundances of La, Th, U, Zr, Nb; low Th/U and high La/Sc, La/Th, Ti/Zr, Zr/Th ratios. The studied graywackes of the continental island arc type setting are characterised by increased abundances of La, Th, U, Zr and Nb, and can be identified by the La-Th-Sc and La/Sc versus Ti/Zr plots. Active continental margin and passive margin graywackes are discriminated by the Th-Sc-Zr/10 and Th-Co-Zr/10 plots and associated parameters (e.g. Th/Zr, Th/Sc). The most important characteristic of the analysed passive margin type graywackes is the increased abundance of Zr, high Zr/Th and lower Ba, Rb, Sr and Ti/Zr ratio compared to the active continental margin graywackes.

Econometric models based on count data. Comparisons and applications of some estimators and tests

Abstract: This paper deals with specification, estimation and tests of single equation reduced form type equations in which the dependent variable takes only non-negative integer values. Beginning with Poisson and compound Poisson models, which involve strong assumptions, a variety of possible stochastic models and their implications are discussed. A number of estimators and their properties are considered in the light of uncertainty about the data generation process. The paper also considers the role of tests in sequential revision of the model specification beginr ing with the Poisson case and provides a detailed application of the estimators and tests to a model of the number of doctor consultations.

Oxygen isotopes and sea level

Abstract: From the time that detailed oxygen isotope records derived from foraminifera living in the constant-temperature environment of the abyssal ocean became available, there has been a discrepancy between the ice volume record that these records imply, and that derived from the altitude of dated coral terraces around the world. Here, we re-examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system.

The Theory of Externalities, Public Goods, and Club Goods

Abstract: This book presents a theoretical treatment of externalities (i.e. uncompensated interdependencies), public goods, and club goods. The new edition updates and expands the discussion of externalities and their implications, coverage of asymmetric information, underlying game-theoretic formulations, and intuitive and graphical presentations. Aimed at well-prepared undergraduates and graduate students making a serious foray into this branch of economics, the analysis should also interest professional economists wishing to survey recent advances in the field. No other single source for the range of materials explored is currently available. Topics investigated include Nash equilibrium, Lindahl equilibria, club theory, preference-revelation mechanism, Pigouvian taxes, the commons, Coase Theorem, and static and repeated games. The authors use mathematical techniques only as much as necessary to pursue the economic argument. They develop key principles of public economics that are useful for subfields such as public choice, labor economics, economic growth, international economics, environmental and natural resource economics, and industrial organization.

An algorithm for the location of transition states

Abstract: An algorithm for locating transition states designed for use in the ab initio program package GAUSSIAN 82 is presented. It is capable of locating transition states even if started in the wrong region of the energy surface, and, by incorporating the ideas on hessian mode following due to Cerjan and Miller, can locate transition states for alternative rearrangement/dissociation reactions from the same initial starting point. It can also be used to locate minima.

The mass of an asymptotically flat manifold

Abstract: We show that the mass of an asymptotically flat n-manifold is a geometric invariant. The proof is based on harmonic coordinates and, to develop a suitable existence theory, results about elliptic operators with rough coefficients on weighted Sobolev spaces are summarised. Some relations between the mass, scalar curvature and harmonic maps are described and the positive mass theorem for n-dimensional spin manifolds is proved.

Turbulent entrainment: the development of the entrainment assumption, and its application to geophysical flows

Abstract: The entrainment assumption, relating the inflow velocity to the local mean velocity of a turbulent flow, has been used successfully to describe natural phenomena over a wide range of scales. Its first application was to plumes rising in stably stratified surroundings, and it has been extended to inclined plumes (gravity currents) and related problems by adding the effect of buoyancy forces, which inhibit mixing across a density interface. More recently, the influence of viscosity differences between a turbulent flow and its surroundings has been studied. This paper surveys the background theory and the laboratory experiments that have been used to understand and quantify each of these phenomena, and discusses their applications in the atmosphere, the ocean and various geological contexts.

Flavones induce expression of nodulation genes in Rhizobium

Abstract: To successfully establish nitrogen-fixing root nodules in a legume plant, a Rhizobium requires at least six plasmid-borne genes (designated nodABCDEF) (Djordjevic et al 1985a; Djordjevic et al 1985b), which are arranged in three separate operons (nodABC, nodD and nodFE) (Torok et al 1984; Rossen et al 1985b). Only one nodulation gene, nodD, is expressed by Rhizobium in culture and its gene product, together with substances secreted by the host plant, induces expression of genes in nodABC and nodFE (Innes et al 1985; Rossen et al 1985b). Lac fusions to presently undefined nod genes, located in regions II and IV of the 14 kb nodulation fragment of R. trifolii, also respond to substances in plant exudate (Innes et al 1985). It is therefore likely that these regions, too, are under control of the nodD product. We report here that the inducing activity of washings of undamaged clover roots is due to flavones, and that several structurally related compounds have similar activities.

Measurement of the viscosity of liquids in very thin films

Abstract: A method is described for directly measuring the viscosity of liquids in thin films between two surfaces. The results show that the viscosities of tetradecane and water between two mica surfaces are within about 10% of their bulk values in films as thin as 50 A or less, and that the “plane of slip” is within a few Angstroms of each interface (i.e., that at most one layer of molecules is immobilized at each surface). These conclusions are not changed in the presence of electric double-layer overlap forces and solvation (i.e., structural or hydration) forces. We further conclude that solvent structuring at surfaces does not necessarily affect the liquid viscosity.

Two Stage and Related Estimators and Their Applications

Abstract: This paper aims to provide a unified treatment of the properties of two stage estimators. General conditions are set forth for consistency, efficiency and correct inferences. Applications of the general theorems are made to models with expectations and diagnostic tests. The general approach frequently enables much simpler derivation of existing results, and provides a number of new ones.

Robust model reference adaptive control

Abstract: We propose a new model reference adaptive control algorithm and show that it provides the robust stability of the resulting closed-loop adaptive control system with respect to unmodeled plant uncertainties. The robustness is achieved by using a relative error signal in combination with a dead zone and a projection in the adaptive law. The extra a priori information needed to design the adaptive law, are bounds on the plant parameters and an exponential bound on the impulse response of the inverse plant transfer function.

High frequencies of alpha-thalassaemia are the result of natural selection by malaria.

Abstract: The frequency of alpha+-thalassaemia, but not other unlinked DNA polymorphisms, exhibits an altitude- and latitude-dependent correlation with malaria endemicity throughout Melanesia, supporting the hypothesis that protection against this parasitic disease is the major factor responsible for the high frequencies of haemoglobinopathies in many parts of the world.

Jack Hills, evidence of more very old detrital zircons in Western Australia

Abstract: The age of the Earth's oldest crustal minerals sets a time-limit on the earliest preservation of buoyant solid crust. The oldest mineral ages reported so far are ∼4,180 Myr for detrital zircons from quartzites at Mount Narryer1, in the Yilgarn Block, Western Australia. The oldest-known intact rocks, as distinct from individual minerals, are substantially younger; they formed ∼3,813-Myr ago2 in the Isua supracrustal belt, West Greenland. We report here a further occurrence of old detrital zircons, again identified using the ion-microprobe SHRIMP3, in conglomerate from the Jack Hills Metasedimentary Belt4,5 (26°11′ S, 116°58′ E), ∼60km north-east of Narryer. This discovery is important for several reasons. First, one zircon registers the exceptionally old age of 4,276±6 Myr, which is, moreover, a minimum estimate for its original age; 16 other grains may have the same age or may be slightly younger. Second, the new occurrence considerably extends the area over which the old Narryer suite is known, thus amplifying its geological significance. Third, the frequency of old zircons in the Jack Hills occurrence is 12%, about five times higher than at Narryer, which suggests that the intact ∼4,180 Myr-old rocks, if they still exist, might be closer, and facilitates future comparison of the SHRIMP data with conventional analyses of these grains. (Recent conventional U–Pb work6 on other zircons from the same Narryer concentrate confirmed the younger ages but failed to observe any at ∼4,180 Myr, probably because of their low abundance7). The likelihood that zircon would dissolve in magmas undersaturated in zirconium8 argues against its survival in long-term contact with such magmas during the disaggregation and subduction of crust. Consequently, the existence of zircon in the Jack Hills area from ∼4,300 Myr ago implies that this part of the crust has been preserved, since then, from recirculation in the mantle through plate-tectonics or any other mechanism.

Fringe-pattern analysis using a 2-D Fourier transform

Abstract: A refinement of the Fourier transform fringe-pattern analysis technique which uses a 2-D Fourier transform is described. The 2-D transform permits better separation of the desired information components from unwanted components than a 1-D transform. The accuracy of the technique when applied to real data recorded by a system with a nonlinear response function is investigated. This leads to simple techniques for optimizing an interferogram for analysis by these Fourier transform methods and to an estimate of the error in the retrieved fringe shifts. This estimate is tested on simulated data and found to be reliable.

The immune response to influenza infection.

Abstract: The purpose of this article is to review the nature of the immune response to influenza virus both in hosts which experience natural infection, particularly man, and in hosts which are experimentally infected, particularly mice, Until recently, an article on this topic may well have contained only a rather superficial account of the properties of the virion with hardly a mention of the replication process. However, the past few years have seen great advances in two almost separate developments. On the one hand, detailed information is now available on the viral genome and the expression of viral proteins: there are complete amino acid sequences and X-ray crystallographic analysis of the two surface glycoproteins, the hemagglutinin and the neuraminidase; we have a greater understanding of the roles of gene reassortment and mutation in the generation of antigenic shift and drift, and of the mechanism of viral replication and assembly. On the other hand, and although there are still very significant gaps, there has been a great increase in our knowledge of the different classes of lymphocytes, particularly T cells, and to a lesser extent of other cell types involved in the immune response to this virus. Significant correlations in the case of human studies and the findings from cell transfer studies in experimental systems have made possible the allocation of particular roles to different cell types.

40 Ar/ 39 Ar dating of white micas from an Alpine high-pressure metamorphic belt on Naxos (Greece): the resetting of the argon isotopic system

Abstract: Overprinting of white micas from high pressure, low to medium temperature (M 1) metamorphic assemblages in pelitic schists on Naxos during subsequent thermal dome (M 2) metamorphism ranges from minor in the southeast of the island to complete recrystallization in the amphibolite facies rocks near the migmatites in the centre of the dome. The original (M 1) minerals are phengites (Si4+=6.7–7.0) and the overprinting minerals are muscovites (Si4+=6.0–6.45). 40Ar/39Ar step heating analyses of white mica separates from rocks in the area where phengite and muscovite occur together yield complex age spectra, characterized by low apparent ages in the first and the last stages of gas release and high apparent ages in between. These upward-convex age spectra are shown to be caused by mixing of two generations of micas, each of which has a different age spectrum and argon release pattern. Seemingly good plateaus in some age spectra from white micas of the area must be interpreted as providing meaningless intermediate ages. Further, the upward-convex age spectra have been used to trace the isotopic signature of phengites toward increasing M 2 metamorphic grade, and suggest that as long as phengites can be observed in the rocks upward-convex age spectra occur. On Naxos, crystallization of muscovite at the expense of phengite appears to be the main mechanism of resetting argon isotopic ages in white micas. However, there is also good evidence for argon loss by volume diffusion from phengites. Simple diffusion calculations suggest that the M 2 metamorphism was caused by a shortlived heat source.

Regulation of the Soybean-Rhizobium Nodule Symbiosis by Shoot and Root Factors

Abstract: The availability of soybean mutants with altered symbiotic properties allowed an investigation of the shoot or root control of the relevant phenotype. By means of grafts between these mutants and wild-type plants (cultivar Bragg and Williams), we demonstrated that supernodulation as well as hypernodulation (nitrate tolerance in nodulation and lack of autoregulation) is shoot controlled in two mutants (nts382 and nts1116) belonging most likely to two separate complementation groups. The supernodulation phenotype was expressed on roots of the parent cultivar Bragg as well as the roots of cultivar Williams. Likewise it was shown that non-nodulation (resistance to Bradyrhizobium) is root controlled in mutant nod49. The shoot control of nodule initiation is epistatically suppressed by the non-nodulation, root-expressed mutation. These findings suggest that different plant organs can influence the expression of the nodulation phenotype.

Four zircon ages from one rock: the history of a 3930 Ma-old granulite from Mount Sones, Enderby Land, Antarctica

Abstract: Ion microprobe U-Th-Pb analyses of zircons from a granulite-grade orthogneiss from Mount Sones, Enderby Land, Antarctica, record the ages of four principal events in the history of the gneiss, three of which already have been recognized through previous isotopic dating of other samples. The structure of the zircons indicates at least four different stages of growth. The several zircon ages were obtained by grouping the analyses according to the stage they represented in the observed “stratigraphic succession” of growth and thereby defining separate U-Pb discordance patterns for each stage. The stratigraphically oldest zircon (rare discrete cores) is indistinguishable in age from the most common, euhedrally zoned zircon. Both crystallized when the tonalitic precursor of the orthogneiss was emplaced into the crust 3927±10 Ma ago, making the orthogneiss currently the oldest known terrestrial rock. The outer parts of most grains and some whole grains recrystallized at 2948±31/−17 Ma, during or immediately after possibly ∼100 Ma of high granulite grade metamorphism. The recrystallized zircon was isotopically disturbed by tectonism associated with reactivation of the southern margin of the Napier Complex at ∼1000 Ma. In the intervening time, at 2479±23 Ma, the cores and zoned zircon suffered a major isotopic disturbance involving movement of radiogenic Pb which left most of the crystals with radiogenic Pb deficiencies, but produced local radiogenic Pb excesses in others. A new generation of zircon, characterized by very high Th/U and low U, grew at that time. That event — deformation and possibly a minor rise in temperature — produced widespread perturbations of other isotopic systems throughout the Napier Complex.

A 40,000 year-old human occupation site at Huon Peninsula, Papua New Guinea

Abstract: The geographical position of the island of New Guinea suggests that it may have been an early staging post in the Pleistocene settlement of Australia from the Indonesia–Indochina region. Previous data have not supported this, as archaeological sites 35,000 to 40,000 years old occur in southern Australia1,2, whereas the earliest previously known in Papua New Guinea is 26,000 years old3–5. We now report evidence that the north coast of Papua New Guinea was occupied at least 40,000 years ago. Sahuland, which is the greater land area of Australia and New Guinea plus their connecting continental shelf exposed as land when Pleistocene sea levels were lower than now6,7, was occupied by humans in several widely separated areas at that time. A distinctive ‘waisted axe’ culture appears to have existed in New Guinea and probably in Australia in the Late Pleistocene, but antecedents are not yet known from east and southeast Asia. There is evidence for hafting of these tools at a date which is earlier than known elsewhere in the world.

Interactions between water—stable hydrophobic Langmuir—Blodgett monolayers on mica

Abstract: A Langmuir-Blodgett technique was used for depositing monolayers of dimethyldioctadecylammonium ions on molecularly smooth muscovite mica surfaces. Direct measurements of the interaction between such surfaces were performed with the surface force apparatus of Israelachvili. A long—range attractive force considerably stronger than the expected van der Waals force was observed. Studies on the salt dependence of this force indicate that it does not have an electrostatic origin. Instead the present results support the view that perturbations of the dynamic association of water molecules outside a hydrophobic surface are propagated several nanometers.

Human Emotions: Universal or Culture-Specific?

Abstract: The search for “fundamental human emotions” has been seriously impeded by the absence of a culture-independent semantic metalanguage. The author proposes a metalanguage based on a postulated set of universal semantic primitives, and shows how language-specific meanings of emotion terms can be captured and how rigorous cross-cultural comparisons of emotion terms can be achieved.

Infiltration‐excess caused by Stemflow in a cyclone‐prone tropical rainforest

Abstract: Tropical rainforest canopy trees that have large projected areas of upwardly inclined branches are capable of funnelling large volumes of rainwater down their trunks. During periods of prolonged heavy rainfall on Mount Bellenden Ker in northeast Queensland, Australia, stemflow volumes were found to be as much as two orders of magnitude greater than the volume of incident rainfall expected in a rain gauge occupying an area equal to the trunk basal area. Stemflow totals ranging from 6000 to 70000 litres were generated by individual trees from 7800 mm of rainfall over two successive wet seasons. The combination of high intensity rainfall and the funnelling effect results in significant quantities of infiltration-excess at the ground surface. Stemflow fluxes as high as 31.4 cm3 min−1 per cm2 of basal area (i.e. the equivalent of 314 mm min−1) were recorded when rainfall intensity was only 2 mm min−1. The mean infiltration capacity of the topsoil was determined to be 6.2 mm min−1. The areas over which the stemflow would have had to spread in order to infiltrate were computed to be as much as 3 m2 around the bases of individual canopy trees. Approximations of the distances that the infiltration-excess would have travelled away from the tree bases were calculated by assuming that the infiltration area either expands radially outward in the form of an annulus or extends straight downslope from the tree base.

Dissipative quantum and classical Liouville mechanics of the anharmonic oscillator.

Abstract: We present a solution for the dynamics of an anharmonic oscillator coupled to a zero-temperature heat bath. Comparison of observable properties in a classical and quantum description uses true joint phase-space probability densities. The time evolution of the density in the quantum case is rapidly "reduced" to that given in the classical description. The rate of reduction is proportional to the product of the damping rate and the oscillator's initial energy. Quite rapidly, typical quantum recurrence effects are destroyed and the classical "whorl" structure restored. We point out the close similarity with rapid destruction of quantum coherence through dissipation.