Showing papers by "James Cook University published in 1980"

Mean and fluctuating internal pressures induced by wind

Abstract: Mean and fluctuating pressures inside buildings, induced by wind, have been investigated using boundary layer wind tunnel and computer simulation techniques. Mean and r.m.s. fluctuating internal pressure coefficients were both found to be monotonic functions of the ratio of windward to leeward opening areas. The case of a single windward opening was treated as a damped Helmholtz resonator. Inertia effects were found to produce resonance amplification in the response of the internal pressure to turbulent external pressures and to a step change in external pressure. However, these effects are unlikely to be of much practical significance except for the case of a sudden large opening occurring in a relatively rigid building. For correct scaling of fluctuating internal pressures, wind tunnel testing should be tested at full scale wind velocities. However, it is shown that similarity can be maintained at lower wind tunnel velocities, by distorting the internal volume by a factor equal to the square of the velocity ratio.

Performance of adaptive estimation algorithms in dependent random environments

Abstract: We consider the convergence properties of certain algorithms arising in stochastic, discrete-time, adaptive estimation problems and operating in random environments of engineering significance. We demonstrate that the algorithms operating under ideal conditions are describable by homogeneous time-varying linear difference equations with dependent random coefficients, while in practical use, these equations are altered only through the addition of a driving term, accounting for time variation of system parameters, measurement noise, and system undermodeling. We present the concept of almost sure exponential convergence of the homogeneous difference equations as an a priori testable robustness property guaranteeing satisfactory performance in practice. For the three particular algorithms discussed, we present very mild conditions for the satisfaction of this property, and thus explain much of their observed behavior.

Lyapunov techniques for the exponential stability of linear difference equations with random coefficients

Abstract: We consider an approach to studying the exponential stability of linear difference equations with random coefficients through the use of Lyapunov stability techniques. The equations we study are of a form familiar from adaptive estimation algorithms, which motivates the examination. It is necessary to define the almost sure exponential convergence of a random process, and then to derive sufficient conditions on the coefficients of the difference equations to ensure the almost sure exponential convergence of the state. We consider, in particular, two very reasonable types of random coefficients-ergodic and stationary and φ-mixing and nonstationary-which would appear to encompass many engineering situations. An example of the power of the theory is given, where it is applied to a common adaptive filtering algorithm to derive mild conditions for exponential convergence with dependent random inputs.

Sodium as an Essential Micronutrient Element for Plants and its Possible Role in Metabolism

Abstract: Publisher Summary This chapter describes the effects of sodium on plants. These plants include those angiosperms having the C4 dicarboxylic photosynthetic pathway and some members of the Cyanophyta. It discusses the effect of sodium on growth and metabolism of these species at concentration of 0.1 mol m–3 and below that supports the optimum growth in these species. The chapter describes a brief history of the understanding of sodium as a nutrient element for plants. The methods for obtaining sodium-free conditions are also discussed along with its known physiological effects. The chapter concludes with tentative schemes, which are proposed to explain sodium's involvement in plant metabolism. Sodium is also shown to be essential for some blue–green algae, including Anabaena cylindric; and for C4 species in the families, Gramineae, Cyperaceae, Amaranthaceae, Chenopodiaceae, and Portulacaceae. It is noted that the signs of sodium deficiency are similar in all species for which it is essential. Leaves become chlorotic and in severe cases the margins and tips become necrotic.

The unusual metal status of the dugong Dugon dugon

Abstract: Using atomic absorption spectroscopy, exceptionally high concentrations of iron (778 to 82,363 μg g+1 dry weight) and zinc (219 to 4,183 μg g+1 dry weight) were detected in the livers of Dugong dugon (Muller) from north Queensland compared with reported values for other marine mammals from other areas of the world Levels of copper (91 to 608 μg g+1 dry weight), cadmium (<01 to 59 μg g+1 dry weight), cobalt (05 to 72 μg g+1 dry weight) and silver (02 to 39 μg g+1 dry weight) in the liver, and cadmium (02 to 209 μg g+1 dry weight) in the kidney were also relatively high in several samples, whilst concentrations of nickel, lead and chromium were consistently below the limits of detection in all tissues Manganese concentrations, in all tissues examined, were generally comparable with those reported from other marine mammals Tissue concentrations of a number of metals varied with the age of the dugong Levels of iron, zinc, cadmium and cobalt in the liver zinc and cadmium in the kidney, and iron in the muscle were significantly positively correlated with age Copper and manganese in both liver and kidney were negatively correlated with age Large deposits of the iron-rich pigment, haemosiderin, the quantity of which also tended to increase with age, was a conspicuous feature of the livers of all the post-natal dugongs examined histologically It seems unlikely that the unusual metal status of the dugong reflects anthropogenic activities, since many individuals were collected in remote areas far from major sites of urbanization and industrialization Seagrasses, the major food of dugongs, were collected from various north Queensland dugong habitat-areas and analysed Very high concentrations of iron but low levels of copper were detected The significance of such dietary imbalances and their possible influence on the metal status of the dugong were therefore considered

Nematocyst inhibition in chironex fleckeri

Abstract: Laboratory tests indicate that methylated spirits, widely espoused as a first‐aid treatment for jellyfish stings, causes massive discharge of nematocysts in living tentacles of the box‐jellyfish, Chironex fleckeri. This action, together with demonstrated hazards of flammability and intoxication, casts doubt on this substance as a treatment for Chironex stings. In an attempt to find a substitute which will be effective in inactivating unfired nematocysts in the tentacles adhering to sting victims, a number of substances were tested in the laboratory. Weak solutions of acetic acid, as well as commercial vinegar, were found to inactivate the penetrating nematocysts of Chironex rapidly and completely. Most other substances tested proved less effective, and some actually stimulated the firing of nematocysts.

Hydrology and fish diversity of a North Queensland tropical stream

Abstract: The diversity and distribution of fish and the hydrology of the Black-Alice River System, North Queensland, are described from a 2-year study (September 1972 to August 1974). Most physico-chemical parameters measured exhibited seasonal patterns which are influenced by rainfall and discharge. A total of forty-one species of fishes belonging to four groups: freshwater tolerant, saltwater tolerant, diadromous and sporadic, were recorded during the study. The diversity of fish species decreased with increasing distance from the mouth of the system. Fluctuations in total diversity (H') were due to variations in ‘species richness’ (D) rather than to equitability (E). The ability of the fish community to ‘recover’ its diversity and longitudinal distribution after a flood of above-average magnitude is demonstrated.

A correction to the Poole and Atkins Secchi disc/light-attenuation formula

Abstract: Re-examination of the original and subsequent data from Secchi disc studies leads to a revised constant in the light attenuation formula applicable to general field-work.In theory, the depth at which a Secchi disc disappears from an observer's sight, Ds, is inversely proportional to the sum of attenuation coefficients for diffuse and collimated photopic light (Tyler, 1968). By definition, photopic light is measured by a sensor with the same spectral response curve as the normal human eye. In practice, the usefulness of the theoretical equation is restricted. More commonly, a simple empirically derived formula is used to estimate the attenuation coefficient for diffuse downwelling light, k, directly from Ds. Poole & Atkins (1929), in their pioneering work on light penetration in the sea, derived the relationship k × Ds – 17 for water in the English Channel. This formula is used extensively by workers who are unable to measure k directly and it is given regularly in oceanography and marine biology texts. More recently, a number of investigators have proposed alternative equations relating k to Ds in different regional seas (Table 1). However, Idso & Gilbert (1974) have fitted data of some of these authors, together with measurements of their own, to the original Poole and Atkins formula with good correlation. They suggest that k × Ds = 1.7 is a universal approximation for all natural waters. In view of the continuing importance of the Secchi disc as a measure of underwater light for primary production calculations and other studies, a universal formula is certainly desirable. However, re-examination of the Poole & Atkins measurements has revealed an error in the method of calculation of k.

Structure and function of the third maxillipeds of the banana prawn Penaeus merguiensis

Abstract: The functions of the third maxilliped of Penaeus merguiensis de Man are described. It has a 6-segmented endopodite which is used in feeding, grooming and possible pheromone reception. In feeding, large pieces of food are gripped by the stout spines on inner borders of the ischia which hold them to the mouth so that particles can be torn off and ingested. All the distal segments have long setae used in grooming chelate pereiopods and the antennules. In mature males there is a tuft of about 300 slender setae at the end of the propus, but its function remains obscure.

An adaptive d-step ahead predictor based on least squares

Abstract: This paper examines the asymptotic properties of a least squares algorithm for adaptively calculating a d -step ahead prediction of a time series. It is shown that, with probability one, the sample mean-square difference between time recursive prediction and the optimal linear prediction converges to zero. Relatively weak assumptions are required regarding the underlying model of the time series.

Phycomycosis of the horse caused by Basidiobolus haptosporus.

Abstract: A case of subcutaneous phycomycosis of a horse from which Basidiobolus haptosporu was isolated is described. Although some clinical signs were similar to the disease caused by Hyphomyces destruens, the gross and microscopic pathology were different in several respects. Main characteristics of the histopathology were the narrow eosinophilic sleeve around wide, frequently septate hyphae scattered throughout the affected tissue and found commonly at the advancing border of the lesion. A retrospective study of 63 cases of phycomycosis diagnosed at this laboratory since 1970 indicated a further 11 cases with similar histological features. The significance of this finding for the epidemiology and pathogenesis of equine dermal granulomas is discussed.

Fine structure of the optic cusion in the asteroid Nepanthia belcheri

Abstract: The optic cushion of Nepanthia belcheri (Perrier) is a prominent pigmented sense organ situated on the oral surface below the terminal tentacle. The distal region contains up to 170 optic cups, whilst proximally are numerous pyriform glandular cells traversed by supporting fibres. The outer margin of the optic cup is formed by alternating pigmented and photoreceptor cells. The pigmented cells contain numerous densely staining granules of scarlet pigment. The distal ends of the photoreceptors are elaborated into many long microvilli regularly arranged about a modified cilium. There is a clear circumciliary space delimiting the cilium from the microvilli.

Epidemiology of bovine anaplasmosis in beef calves in northern Queensland.

Abstract: Natural infection of calves with Anaplasma marginale was studied in two endemic areas of tropical north Queensland. Infection, assessed by a micro-complement fixation test, occurred throughout the year but was most frequent just after the summer wet season. Infection was clinically inapparent. Calves vaccinated with A. centrale did not show improved growth rate when compared with non-vaccinated calves. The complement fixation test was shown to be most effective in the detection of recent infections.

Elastic scattering of 152Eu γrays by Pb

Abstract: Differential cross sections for the elastic scattering of 344, 779, 964, 1086, 1112 and 1408 keV 152Eu gamma rays by Pb have been measured for nine scattering angles ranging from 3 degrees to 45 degrees and are compared with theoretical cross sections for Rayleigh plus nuclear Thomson scattering. For low momentum transfers the experimental results are in best agreement with theoretical cross sections computed using the Hartree-Fock form factor Rayleigh scattering amplitudes tabulated by Hubbell et al. (1975) but at all energies the experimental cross sections drop significantly below theoretical cross sections computed using Hartree-Fock form factor, relativistic point-Coulomb form factor, Kissel-Pratt and Johnson-Cheng 'exact', or Brown Rayleigh amplitudes for scattering angles above about 20 degrees . Inclusion of Delbruck scattering using the amplitudes of Papatzacos and Mork (1975) at 1408 keV reduces the disagreement between experimental and theoretical cross sections at that energy.

The Vaiont Slope Failure

Abstract: The Vaiont Slope Failure The paper discusses the Vaiont Slope Failure as an example of sequential failure involving a third order failure mechanism. Laboratory evidence obtained with sand models is presented in support of the argument and from this arises the concept of dilatant zones which allow formerly tightly packed rock zones to dilate and permit block rotation and shearing to contribute to a considerable reduction in strength. Field measurements of movement vectors originally made by Muller also provide evidence in support of the mechanism. Using the author's clastic analysis, together with possible pore pressure changes on the initiating failure surface, it is shown that on backanalysis values of tanφ′ required according to Muller in the range 0.7 to 0.8, can be obtained. An important phenomenon observed in the Vaiont slide was the rate at which the material moved into the valley. It is suggested that the energy liberated by the strain-softening characteristics of the material involved played a major role, but it is also considered that, once initiated, pore water pressure increase on the failure surface analogous to the phenomenon of aquaplaning in vehicle skidding on wet pavements may also have contributed to the rate of movement.

The genus Polychromophilus (Haemoproteidae, parasite of Microchiroptera).

Abstract: Le genre Palychromophilus est constitue par deux ensembles d’especes tres differents que les auteurs ont groupes dans 2 sous-genres : a ) le sous-genre Polychromophilus , avec pour espece type P. (P. ) melanipherus Dionisi 1899, telle qu’elle a ete redefinie par Garnham (1973) : la morphologie des gametocytes est de type « malariae » ; b ) le sous- genre Bloccala, avec pour espece type P. (B. ) murinus Dionisi 1898 ; la morphologie des gametocytes est proche de celle des Hemoproteidae d’Oiseaux.Des Polychromophilus de Miniopteres d’Europe, d’Afrique et d’Australie ont ete etudies et decrits, en particulier 2 especes nouvelles africaines : P. (P. ) corradettii chez Miniopterus inflatus au Gabon et P. (P. ) adami chez Miniopterus m. minor au Congo- Brazzaville. Des formes de multiplication tissulaire nombreuses et variees ont ete trouvees, mais les infections etant generalement mixtes, il n’est pas possible de rattacher avec certitude les differents schizontes observes a un sous-genre determine. Cependant, les auteurs proposent une interpretation s’inspirant des affinites phyletiques des parasites. Ainsi sont classes : a ) dans le sous-genre Polychromophilus (gametocytes de type « malariae »), les schizontes tissulaires de grande taille, siegeant dans une cellule hote tres hypertrophiee entouree par une capsule et dont les noyaux sont, chez les stades âges, complexes et granuleux ; b ) au sous-genre Bioccala (gametocytes de type « oiseau »), les schizontes de petite taille (type Mer et Goldblum). De meme, la sporogonie observee chez les Nycteribies par divers auteurs serait celle du sous-genre Bioccala .

The land, the explorers and the aborigines

Abstract: (1980). The land, the explorers and the aborigines. Historical Studies: Vol. 19, No. 75, pp. 213-226.

Observations on behavior, emergence and reproduction of the marine midges Pontomyia (Diptera: Chironomidae)

Abstract: Pontomyia is a genus of tiny flightless marine midges, with 4 described species, found on tropical or subtropical sea shores of the western Pacific Ocean. They are rarely noticed because of their small size (about 1.5 mm) and ephemeral adult life (1 to 3 h). They usually occur in association with seagrasses and seaweeds on which the larvae feed. The oar-like wings of adult males propel them over the water surface, but do not enable them to fly. Adult females are not only wingless but virtually legless. Emergence of the adults in the field may occur either during the day or at night. In a laboratory aquarium population of P. cottoni Womersley, maintained for about 18 months in a 12 h light-12 h dark cycle, males began to emerge at the end of the light period, whereas females emerged only after the onset of darkness. Field observations suggest that emergence times are probably influenced also by tides.

A comparative study of experimental anaplasmosis in Bos indicus and Bos taurus cattle.

Abstract: Comparative studies were carried out on the susceptibility of 8 Bos taurus and 10 predominantly Bos indicus cross cows aged 48 months to Anaplasma marginale infection. Measurements were carried out on bodyweight, parasitaemia, haematological factors, humoral antibody response and serum transaminase levels. Except for minor differences in reaction Bos indicus and Bos taurus animals were equally susceptible to infecton with the strain of A. marginale employed. Such differences observed were not significant.