Showing papers by "James Cook University published in 1991"

Corporate social disclosure: A note on a test of agency theory

Abstract: This study was undertaken to use agency theory to test for a relationship between environment-related disclosure and the oil industry. A review of social disclosure in 1984 annual reports of 131 leading UK companies indicated that a positive relationship existed between the oil industry and environment-related disclosure. This result was found to be consistent with agency theory which dictates that social information is disclosed to increase the welfare of management. There is evidence of a renewed interest in the social performance of companies. Consequently, corporate social disclosure provides a fertile area for research. Agency theory can be used for developing and testing hypotheses to explain corporate social disclosure.

Metamorphism in Archaean greenstone belts: calculated fluid compositions and implications for gold mineralization

Abstract: An inescapable consequence of the metamorphism of greenstone belt sequences is the release of a large volume of metamorphic fluid of low salinity with chemical characteristics controlled by the mineral assemblages involved in the devolatilization reactions. For mafic and ultramafic sequences, the composition of fluids released at upper greenschist to lower amphibolite facies conditions for the necessary relatively hot geotherm corresponds to those inferred for greenstone gold deposits (XCO2= 0.2–0.3). This result follows from the calculation of mineral equilibria in the model system CaO–MgO–FeO–Al2O3–SiO2–H2O–CO2, using a new, expanded, internally consistent dataset. Greenstone metamorphism cannot have involved much crustal over-thickening, because very shallow levels of greenstone belts are preserved. Such orogeny can be accounted for if compressive deformation of the crust is accompanied by thinning of the mantle lithosphere. In this case, the observed metamorphism, which was contemporaneous with deformation, is of the low-P high-T type. For this type of metamorphism, the metamorphic peak should have occurred earlier at deeper levels in the crust; i.e. the piezothermal array should be of the ‘deeper-earlier’type. However, at shallow crustal levels, the piezothermal array is likely to have been of ‘deeper-later’type, as a consequence of erosion. Thus, while the lower crust reached maximum temperatures, and partially melted to produce the observed granites, mid-crustal levels were releasing fluids prograde into shallow crustal levels that were already retrograde. We propose that these fluids are responsible for the gold mineralization. Thus, the contemporaneity of igneous activity and gold mineralization is a natural consequence of the thermal evolution, and does not mean that the mineralization has to be a consequence of igneous processes. Upward migration of metamorphic fluid, via appropriate structurally controlled pathways, will bring the fluid into contact with mineral assemblages that have equilibrated with a fluid with significantly lower XCO2. These assemblages are therefore grossly out of equilibrium with the fluid. In the case of infiltrated metabasic rocks, intense carbonation and sulphidation is predicted. If, as seems reasonable, gold is mobilized by the fluid generated by devolatilization, then the combination of processes proposed, most of which are an inevitable consequence of the metamorphism, leads to the formation of greenstone gold deposits predominantly from metamorphic fluids.

Effects of sedimentation on settlement of Acropora millepora

Abstract: Sedimentation is assumed to affect communities of reef-building corals by inhibiting larval settlement, however there has been no quantitative evidence to support this supposition. The effects of varying rates of sedimentation (0.5 to 325 mg cm-2d-1) on settlement rates of Acropora millepora larvae were examined experimentally, in aquaria. Settlement and juvenile orientation onto conditioned cut coral plates were recorded after two days. Higher sedimentation rates reduced the number of larvae settling on uppersurfaces, but total numbers of settled larvae were not significantly affected by sedimentary regime. While total settlement was unaffected by sediment under the confined experimental conditions, it is likely to be reduced under field conditions, since accumulation of sediment on upward-facing surfaces will greatly reduce the overall amount of suitable substratum available.

Tourist satisfaction: A guided “cultural” tour in north queensland

Abstract: The principal aim of this research was to determine factors responsible for tourists' satisfaction with 1-day guided tours of an aboriginal and islander community in North Queensland. Requirements of the tour guide and expectations of cultural interaction were compared with overall satisfaction. The degree to which these expectations were met determined tourists' satisfaction with the tour as a whole. Of particular importance were the ability of the tour guide to (a) provide an interesting commentary, (b) interact with the tour group, and (c) ensure the smooth running of the tour. Visitor evaluations of cultural enrichment and interaction with the local people were also important These results were interpreted within the tourist-environmental “fit” theory.

Influence of tidally induced fronts and Langmuir circulations on distribution and movements of presettlement fishes around a coral reef

Abstract: The slicks of tidally induced fronts and Langmuir circulations were studied near Bowden Reef, Great Barrier Reef, in December 1987. There were two components to the study: (1) a description of physical oceanography adjacent to the reef; (2) sampling for planktonic organisms, designs being stratified according to hydrology. Tidal fronts extended 1 to 2 km from the reef outside the lagoon. Fish of a variety of developmental forms and zooplankton were most abundant in slicks of fronts. Sixteen to 81% of fish that were captured were presettlement reef-fishes. There was an unclear relationship between the presence of slicks of Langmuir circulations and abundance of fish in the lagoon. This relationship was largely because well developed atherinids and recently hatched pomacentrids showed no predictable relationship with the presence of windrows. Jellyfish,Aurelia aurita, were found in extremely high concentrations in the slicks of Langmuir circulations; small carangids were associated with jellyfish. Movements of fronts were influenced by the tide and wind. In some conditions we observed fronts to change position as the tide reversed direction. Fronts that were orientated offshore (1 to 2 km), were observed to rotate and align with the reef. Because of a “halo” of oceanographic features such as tidal fronts, the reef may be a larger target for presettlement fishes than its topography would suggest. It is argued that some organisms are advected into slicks, while others respond to high concentrations of zooplanktonic food and remain in slicks. Localised oceanographic features may also affect the settlement patterns of fishes on reefs.

Episodic metamorphic reactions during orogenesis: the control of deformation partitioning on reaction sites and reaction duration

Abstract: Textural ‘unconformities’or truncations are common in porphyroblasts with complex inclusion trails. They reflect cycles of successive foliations that develop against competent porphyroblasts during orogenesis and are preserved by successive growth increments. Their truncational character results from shear and dissolution along a particular foliation generating a differentiated crenulation cleavage. The increment of porphyroblast growth that follows a textural ‘unconformity’may or may not mark a significant compositional change, depending on the amount of movement of the rock through P–T space between cleavage-forming events. Although historically interpreted to result from a significant metamorphic hiatus, most textural unconformities indicate that the reactions involved in the formation of these minerals are episodic during continuous prograde metamorphism, starting and stopping as a function of the stage of crenulation of the matrix foliation and the pattern of deformation partitioning. Such episodic reaction behaviour can only occur for multivariant reactions, or successive but different univariant reactions. The reason why garnet is the most common porphyroblast to exhibit evidence for episodic reactions is probably the fact that it grows by multivariant reactions over a much wider P–T range than most other common porphyroblast phases. Porphyroblast growth is micrometasomatic. It is episodic because a significant reduction of strain occurs within domains of progressive shortening each time continuous progressive shearing domains form on their margins. This stops microfracture development across the progressive shortening domains, thereby preventing rapid access and interaction of fluid, ions and complexes with porphyroblast boundaries. Shifting patterns of deformation partitioning and resulting small-scale juxtaposition of different compositional layers spreads the duration and location of multivariant reactions and causes differential timing of porphyroblast growth along a particular stratigraphic horizon. It may also locally preserve metastable metamorphic assemblages. In regionally metamorphosing/deforming pelites, near-simultaneous cessation of porphyroblast growth on all rims, once continuous differentiated progressive shearing domains have formed nearby, precludes fluid recirculation as a significant process for removal of material during cleavage development. Alternatively, diffusion of simple molecules and dissociated ions along actively shearing and micro-gaped phyllosilicates, with recomplexing in fluid-filled microfractures, readily explains the control of deformation partitioning on reaction site and reaction duration.

Chemically mediated interactions between the red alga Plocamium hamatum (Rhodophyta) and the octocoral Sinularia cruciata (Alcyonacea)

Abstract: Interactions between the red algaPlocamium hamatum J. Agardh (Rhodophyta) and other benthic organisms including the alcyonacean soft coralSinularia cruciata (Tixier-Durivault) were investigated on an inshore fringing reef environment in whichP. hamatum was the dominant large fleshy alga. Field observations of sessile reef organisms including octocorals and sponges living in close proximity toP. hamatum revealed that varying degrees of tissue necrosis were suffered by the invertebrates when in physical contact with the alga. In order to establish whether the chemical constituents of the alga, especially chloromertensene, played a role in this necrosis, manipulative field experiments were carried out in the Pelorus Channel, Palm Island group (18°34′S; 146°29′E), North Queensland, Australia, in November and December 1988. The first experiment involved the relocation of healthy plants and soft corals into contact and non-contact situations on a mesh grid. In all cases of contact betweenP. hamatum andS. cruciata, the soft coral suffered tissue necrosis (n=6,p=0.0022). The second experiment had the same design, but involved the use of artificial “plants” both uncoated and coated with natural levels of chloromertensene, in contact withS. cruciata. In all cases of contact with coated treatments, necrosis was observed inS. cruciata (n=4,p=0.025). In cases where uncoated artificial fronds were placed in contact with soft corals,S. cruciata showed minor abrasion effects, but no appreciable necrosis. Coated treatments were not fouled by epiphytes during the experiment and were not consumed by predators. Uncoated treatments were rapidly reduced in size by predation and any remaining material was biofouled. These experiments thus demonstrated that the deleterious effects observed in soft corals in the field were caused by contact with the algaP. hamatum, that these effects were indeed chemically mediated by chloromertensene, and that physical contact without chemical intervention caused no such deleterious effects. This is the first experimental evidence which conclusively demonstrates allelopathy between an alga and other marine organisms and identifies the compound responsible for the observed allelopathic effects.

Clinical and pathological findings of Babesia infection in dogs.

Abstract: The clinical and pathological findings of Babesia infection in 32 dogs in northern Australia are presented. Eleven different breed types were represented from 6 localities in north Queensland and one locality in northern Western Australia. Twenty three (72%) were males. Babesia-infected dogs were grouped by the degree of haematological disturbance and clinical severity: Acute babesiosis (25/32), all pups with severe haemolytic anaemia; subclinical carriers (5/32) with non-specific malaise, characterised haematologically by a normal erythrogram but marked leucopenia; chronic anaemia, observed in 2 adult dogs. Pups were azotaemic (serum urea greater than 6.6 mmol/l) and had elevated serum bilirubin levels (20.8 to 48.5 mmol/l). Total serum protein was usually within the normal range. Pups that died were also hypoglycaemic and severely hyperkalaemic (K+ greater than 10 mmol/l). Low parasitaemias in routine blood smears complicated diagnosis but smears made from ear or toe capillaries, or after haematocrit concentration, greatly enhanced finding parasitised cells. At necropsy, pallor and jaundice were the most consistent observations. Haemoglobinuric nephrosis, an active reticulo-endothelial system and capillaries packed with large numbers of infected erythrocytes were the main histopathological findings. A combination of imidocarb dipropionate at 5 mg/kg body weight, given intramuscularly, with fluid therapy and blood transfusion was the most successful treatment.

Reading Positions and Practices in the Classroom

Abstract: This article examines the classroom construction of “readings” in school literacy and literature programs. Reviewing contemporary theories and definitions of literacy, it argues for the cultural and historical specificity of reading and writing as families of social practices. School texts and classroom events construct selective traditions of particular versions and displays of reading. An agenda for the reconstruction of school reading as discourse critique is outlined.

Evaluation of the genus Listonella and reassignment of Listonella damsela (Love et al.) MacDonell and Colwell to the genus Photobacterium as Photobacterium damsela comb. nov. with an emended description

Abstract: The genus Listonella, which was recently described on the basis of 5S rRNA sequence data, was found to be of dubious value on the basis of the results of a comparison of a number of taxonomic studies involving members of the Vibrionaceae. The available data suggest that 5S rRNA sequences may be of limited taxonomic use at the intra- and intergeneric levels, at least for apparently recently evolved groups, such as the Vibrionaceae. In this light, we assessed the generic assignment of the species Listonella damsela. Phenotypic characterization of 12 strains of bacteria assigned to L. damsela, including type strain ATCC 33539, revealed a strong resemblance to members of the genus Photobacterium. All of the strains conformed to major characteristics common to all known Photobacterium species. The characteristics of these organisms included the absence of a flagellar sheath and accumulation of poly-beta-hydroxybutyrate during growth on glucose coupled with the inability to utilize DL-beta-hydroxybutyrate as a sole carbon source. On the basis of the phenotypic data, we propose that L. damsela should be reassigned to the genus Photobacterium as Photobacterium damsela comb. nov.

Observations on the anatomy, behaviour, reproduction and life cycle of the cubozoan Carybdea sivickisi

Abstract: Substantial numbers of the very small carybdeid jellyfish, Carybdea sivickisi, have been observed feeding actively by divers in the vicinity of fringing coral reefs. During the day specimens were seen in close association with the substrate and with sessile macroalgae. They appeared able to adhere to substrates by contact with an area on the aboral surface of the bell. Individuals maintained in the laboratory showed the same adhering ability. The adhesive organs correspond to 4 areas of raised secretory epithelium on the aboral surface.

Distributional ecology and behaviour of the early life stages of the box-jellyfish Chironex fleckeri

Abstract: Laboratory observations on reared life stages of Chironex fleckeri (Cubozoa: Chirodropidae) have been combined with field sampling and observations to outline the life cycle of the species and the spatial and temporal distribution of populations in Queensland, Australia. A seasonal alternation of polypoid and medusoid generations from winter to summer respectively is accompanied by a shift in preferred habitat from tidal estuaries to the open eulittoral zone. The system appears to be constrained by predictable fluctuations in the suitability of the alternate habitats to their resident generations. Observations on behaviour, feeding, physiological tolerances, and sexual and asexual reproduction provide insights into the adaptiveness of this pattern.

Lack of avoidance of phenolic-rich brown algae by tropical herbivorous fishes

Abstract: High levels of polyphloroglucinol phenolics in marine brown algae are usually interpreted as a defensive response to herbivory. However, tropical brown algae generally contain very low levels of phenolics, even though herbivory in many tropical systems (e.g. coral reefs) is intense. This apparent paradox would be explained if polyphenolics did not deter tropical herbivores, in which case selection by herbivores for high levels of phenolics in tropical algae would be weak. To examine this hypothesis, in February 1989 we presented mixed assemblages of herbivorous fishes on the Great Barrier Reef with tropical, phenolic-poor brown algae (primarilySargassum spp.) and closely related (conspecifics in one instance) phenolic-rich temperate species. Different species of brown algae were eaten at very different rates, but these differences were not correlated with variation in the phenolic levels among the plants. TLC and NMR analyses showed no evidence of other, non-polar, metabolites in these algae, with the exception of the temperate speciesHomoeostrichus sinclairii. Thus, variation in non-polar metabolites also did not explain the differences in susceptibility to herbivores among these algae. We conclude that the herbivorous fishes studied here were not deterred by phenolic-rich algae, which suggests that levels of phenolics in many tropical algae may generally be low due to their ineffectiveness as defences. However, alternative explanations for the pattern are possible, and these are discussed.

Nitrate toxicity to Penaeus monodon protozoea

Abstract: Increased levels of nitrate occur in natural waters due to pollution, and in aquaculture systems from nitrification and addition of microalgal cultures for feeding. Static bioassays showed that significant mortality of larvalPenaeus monodon (Fabricius) occurred within 40 h at nitrate concentrations as low as 1 mg NO 3 - l−1. Sublethal effects of this concentration resulted in changes to ganglionic neuropiles and muscles. At higher concentrations (10 and 100 mg NO 3 - l−1), additional tissues were affected including the hypodermis, midgut and proventriculus. This is the first report of toxicity to a marine organism of nitrate at concentrations normally present in enclosed seawater and mariculture systems. The results are discussed in terms of management of culture systems and of natural marine ecosystems containing elevated levels of nitrate.

Continental-shelf progradation by sediment-drift accretion

Abstract: Multi-channel seismic profiles from the Canterbury Basin on the eastern margin of the South Island of New Zealand reveal the importance of current activity in shaping a Neogene shelf sediment prism. The shelf prism prograded across a broad, near-horizontal platform in water depths of 1,000 to 1,750 m. The platform was formed above a condensed section of late Eocene to late Oligocene limestones which overlie Cretaceous to Paleogene rift-fill and transgressive sediments. The Neogene sediment prism contains sediment drifts which are as much as 25 km long and 15 km wide and extend up to 1,600 m (uncompacted) vertically. Individual drifts migrated westward and can be traced between dip profiles, revealing that the long axes of most are subparallel to the present coastline and shelf-edge. Channel-like features at the landward edges of the drifts correspond to residual space left between the landward-prograding off-shelf sediment drift and the adjacent shelf foreslope. Erosion or slow deposition characterized the foreslope. Progradation of the shelf was by the accretion of successive sediment drifts. Before ca. 11.5 Ma (= Pink Horizon), the shelf-edge-parallel drifts were distributed across the central part of the basin, whereas subsequently they were concentrated to the northeast. The seismic architecture of the Neogene sediment prism results from the interplay of an abundant western sediment source and an offshore boundary current system. Present-day ocean circulation involves northward flow along the east coast of the South Island. The basin may have been subjected to a middle Miocene to late Pliocene phase of intensified flow, caused by local topographic enhancement and/or global paleoceanographic events. Current activity has played a crucial role in the sedimentary evolution of the Canterbury Basin Neogene shelf prism.

Archaeology and geomorphology of the Vanimo Coast, Papua New Guinea: preliminary results

Abstract: We report here excavations at two near-coastal rockshelters near Vanimo, West Sepik Province. Preliminary results include late Pleistocene occupation and mid-Holocene ceramics and pigs, along with a continuing, wide-ranging but marine-oriented economy. The archaeological sites are integrated into a tectonic uplift history for the region in which a number of coral terraces have been identified.

Geological controls on seismic sequence resolution

Abstract: A seismic sequence analysis of the Canterbury basin, eastern South Island of New Zealand, has illustrated the roles of subsidence, sediment supply, and current activity as controls on sequence resolution and architecture during basin evolution. The rates of sediment supply and subsidence determine the background depositional regime (transgressive or regressive),and effectively determine the frequency response of the continental margin sedimentary section to input signals with a broad range of frequencies, including eustasy. A regressive (progradational) depositional regime and minimal current erosion favor the preservation of high-frequency sequences, particularly at fourth-order level. Under less favorable conditions, the record of sequences is incomplete or ambiguous. Such frequency response characteristics must be considered when inverting sequence records to derive the frequency of the input cyclicity, and when making global comparisons of regional sequence stratigraphic studies. Clastic basins with simple subsidence histories and uniform or increasing rates of sediment supply develop from a transgressive phase, characterized by ramplike major sequence boundaries, to a mature, progradational shelf phase with clinoform sequences and optimum sequence resolution. The mature phase constitutes the preferred setting for sequence stratigraphic analyses.

Wave attenuation on an offshore coral reef

Abstract: The wave climate along the northeastern tropical coastline of Australia is controlled by The Great Barrier Reef (GBR). However, the processes by which the GBR attenuates and transforms waves are little understood. As the first part of an on-going study of the interaction between waves and coral reefs, a field experiment was conducted to study the processes that occur as waves break on an offshore reef and proceed across the reef flat into the lagoon. Eighteen wave, water level, and current measuring instruments were deployed and data for a wide range of tide and wave conditions were collected. Preliminary results for wave attenuation are presented. Results for wave attenuation across the reef show that wave heights on the reef flat and in its lagoon are controlled by the depth of water over the windward reef flat. As the waves travel across the reef flat, the ratio of significant wave height to water depth reduces to a value of 0.40, and the ratio of maximum wave height to water depth reduces to a value of 0.6 to 0.8. In the deeper water in the middle of the reef lagoon both the ratios of significant wave height to the depth over the reef flat and maximum wave height to the depth over the reef flat remain in the above ranges. However, at the mid-lagoon position these results are less general as wave heights inside a lagoon are also dependant on wind speed, direction, and fetch length inside the lagoon.

Studies of the pathology of velogenic Newcastle disease: Virus infection in non‐immune and immune birds

Abstract: The pathology of velogenic viscerotropic Newcastle disease virus infection was compared in 7-and 20-week-old groups of non-immune birds and birds with two levels of immunity as determined by the haemagglutinin inhibition test. In non-immune birds the bursa at 7 and 20 weeks was the only lymphoreticular organ to show sustained reticular and lymphoid cell reactions until death took place. Caecal tonsil and spleen were extensively necrotized on day 4 after contact exposure, and similar changes occurred in lung and proventriculus. There was evidence of lymphoid recovery in birds which survived for 18 days. In immune birds the spleen showed two main responses. The first, acute reticular cell response around the ellipsoids indicated that renewed exposure to antigen was often associated with localized cell degeneration. The second, immunological, reaction was rapid formation of germinal centres which occurred somewhat earlier in 20-week-old birds (4-5 days). Especially from the second week, reticular (dendritic) cell and lymphoid hyperplasia occurred diffusely in the bursal medulla of both age groups although marked atrophy and cellular depletion, probably of physiological origin, was a feature of 20-week-old birds with high antibody levels. In the gastro-intestinal tract, germinal centre formation was most marked in the caecal tonsils at 20 weeks. With the Indonesian ITA strain of ND virus, degenerative and inflammatory changes in the brain were mild in all groups up to day 18 irrespective of immune status.

An unusual symbiont from the gut of surgeonfishes may be the largest known prokaryote.

Abstract: Symbionts first reported from the gut of a Red Sea surgeonfish, Acanthurus nigrofuscus (family Acanthuridae), were subsequently described as Epulopiscium fishelsoni. The taxonomic position of this very large (up to 576 microns in length) microorganism has previously been designated in the literature as either uncertain or eukaryotic. We suggest that similar symbionts from Great Barrier Reef surgeonfish may be prokaryotes, which together with E. fishelsoni from the Red Sea may represent the largest known forms of this cell type. Features identifying the symbionts as prokaryotes include the presence of bacterial-type flagella and a bacterial nucleoid and the absence of a nucleus or any other membrane-bound organelle.

kappa-Opioid antagonist improves cellular bioenergetics and recovery after traumatic brain injury.

Abstract: Treatment with opioid receptor antagonists improves outcome after experimental brain trauma, although the mechanisms underlying the protective actions of these compounds remain speculative. We have proposed that endogenous opioids contribute to the pathophysiology of traumatic brain injury through actions at kappa-opioid receptors, possibly by affecting cellular bioenergetic state. In the present study, the effects of the kappa-selective opioid-receptor antagonist nor-binaltorphimine (nor-BNI) were examined after fluid percussion brain injury in rats. Metabolic changes were evaluated by 31P magnetic resonance spectroscopy; the same animals were subsequently followed over 2 wk to evaluate neurological recovery. Nor-BNI, administered intravenously as a 10 or 20 mg/kg bolus at 30 min after injury, significantly improved neurological outcome at 2 wk posttrauma compared with controls. Animals treated with nor-BNI showed significantly greater recovery of intracellular free magnesium concentrations and cytosolic phosphorylation potentials during the first 4 h after injury compared with saline-treated controls. The improvement in cytosolic phosphorylation potential was significantly correlated to neurological outcome. These data support the hypothesis that kappa-opioid receptors mediate pathophysiological changes after traumatic brain injury and that the beneficial effects of opioid-receptor antagonist may result from improvement of posttraumatic cellular bioenergetics.

Tourism impact and community perception: An equity-social representational perspective

Abstract: The reactions of host communities to the tourism industry have usually been explained with stage or step models. Additionally, much current research provides purely descriptive information and presents data on community attitudes to tourism in terms of a demographic segmentation approach. A new perspective is offered here which may be termed an equity-social representational account of community attitudes to tourism. This approach argues that community attitudes to tourism usually follow an equity function, but that certain tourism developments or events trigger widely held social representations of tourism which can modify the responses one might expect from only considering equity based factors. Data from a sample of 507 Cairns residents were used to support the equity-social representation model of community attitudes to tourism. Community groups selected on the basis of their equity scores (perceived costs and benefits from tourism) were shown to differ in their perception of the value of tou...

Work stress among long‐distance coach drivers: A survey and correlational study

Abstract: This paper presents findings from an Australian survey of work conditions, coping behaviors and stress among 93 long-distance coach drivers. A tripartite model of coach driver stress is presented. The model proposes that the impacts of job demands (e.g. driving hours) on work-related stress outcomes (e.g. doctor visits) are mediated by a set of maladaptive coping behaviors and responses (e.g. stimulant use, speeding). Correlational analyses of the survey data provided general support for the model. Results suggested that long driving hours provide the single best predictor of maladaptive behaviors such as stimulant use and sleep disturbance among the drivers. The maladaptive behaviors, in turn, consistently predicted stress outcomes such as doctor visits and symptom reports. Direct correlations between job demands and stress outcomes were also consistent with the model, but the correlations were of a lower magnitude. The data suggests that stimulant use and sleep disturbance may be important mediators in the link between job demands and stress outcomes for long-distance coach drivers. Path modelling with larger samples is recommended for future research along the present lines. Implications for work practices within the long-distance transport industry are briefly considered.