Showing papers by "James Cook University published in 1992"

A Benefit-based Segmentation of a Nonresident Summer Travel Market:

Abstract: This study examined the feasibility of segmenting a nonresident tourist market on the basis of vacation benefits sought. Six distinct benefit-based market segments were found using factor and cluster analysis procedures. The resulting segments were compared on the basis of specific dependent variables organized under the following framework: travel party leader characteristics, travel party composition, trip planning and trip characteris tics, and post-trip evaluation. Finally, marketing strategy implications were addressed. The following evaluation criteria were used in target market selection: profitability, accessibility, and reachability. Benefit-based market segmentation studies were found to be a viable means of determining vacation market segments. The importance of the develop ment of objective and quantifiable means of evaluating market segments is stressed.

The evolutionary ecology of corals.

Abstract: Corals display a wide range of complex life histories. The evolutionary consequences of factors such as clonality, indeterminate growth, asexual reproduction coupled with various (sexual) breeding systems, different levels of gene flow, and strongly overlapping generations have only just begun to be explored. We identify a series of problems and areas for new research that may be resolved b y the application of novel theoretical approaches (including nonequilibrium population genetic models and demographic models incorporating modular processes such as colony fission and polyp mortality), greater in situ experimentation, long-term monitoring of population dynamics and the use of new genetic techniques.

Porphyroblast inclusion-trail orientation data : Eppure non son girate!

Abstract: Extensive examination of large numbers of spatially orientated thin sections of orientated samples from orogens of all ages around the world has demonstrated that porphyroblasts do not rotate relative to geographical coordinates during highly non-coaxial ductile deformation of the matrix subsequent to their growth. This has been demonstrated for all tectonic environments so far investigated. The work also has provided new insights and data on metamorphic, structural and tectonic processes including: (1) the intimate control of deformation partitioning on metamorphic reactions; (2) solutions to the lack of correlation between lineations that indicate the direction of movement within thrusts and shear zones, and relative plate motion; and (3) a possible technique for determining the direction of relative plate motion that caused orogenesis in ancient orogens.

Distribution and accumulation of ultraviolet-radiation-absorbing compounds in leaves of tropical mangroves

Abstract: Ultraviolet (UV)-absorbing phenolic compounds that have been shown to be protective against the damaging: effects of UV-B radiation (Tevini et al., 1991, Photochem. Photobiol. 53, 329-333) were found in the leaf epidermis of tropical mangrove tree species. These UV-absorbing phenolic compounds and leaf succulence function as selective filters, removing short and energetic wavelengths. A field survey showed that the concentration of UV-absorbing compounds varied between species, between sites that would be experiencing similar levels of UV radiation, and between sun and shade leaves. Sun leaves have greater contents of phenolic compounds than shade leaves, and more saline sites have plants with greater levels in their leaves than less saline sites. In addition, increases in leaf nitrogen contents and quantum yields did not correlate with increasing levels of UV-absorbing compounds. It was concluded from these results that although UV-absorbing compounds form a UV-screen in the epidermis of mangrove leaves, UV radiation may not be the only factor influencing the accumulation of phenolic compounds, thus an experiment which altered the level of UV radiation incident on mangrove species was done. Near ambient levels of UVA and UV-B radiation resulted in a greater content of UV-absorbing compounds in Bruguiera parviflora (Roxb.) Wight and Arn. ex Griff., but did not result in increases in B. gymnorrhiza (L.) Lamk or Rhizophora apiculata Blume. Total chlorophyll contents were lower in R. apiculata when it was grown under near-ambient levels of UV radiation than when it was grown under conditions of UV-A and UV-B depletion, but no differences were observed between the UV radiation treatments in the other two species. There was no difference in leaf morphology, carotenoid/chlorophyll ratios, or chlorophyll a/b ratios between UV treatments, although these varied among species; B. parviflora had the highest carotenoid/chlorophyll ratio and R. apiculata had the lowest. Thus it is proposed that differences in species response tu UV radiation may be influenced by their ability to dissipate excess visible solar radiation.

Use of fibrous diets by small herbivores: How far can the rules be ‘bent’?

Abstract: Allometric considerations suggest that small mammals should be unable to eat highly fibrous diets. A combination of the selective and more rapid passage of fibrous material through the gut, together with changes in gut capacity when energy requirements increase, may allow small mammals to escape these allometric constraints. Recent evidence that birds can absorb essential amino acids from the caecum (which has hitherto been considered insignificant in mammals) suggests that birds and mammals have evolved very different ways to be a herbivore.

Effects of feeding history on the growth characteristics of a reef fish at settlement

Abstract: A feeding experiment was conducted on the pelagic stages of the tropical goatfish Upeneus tragula (family Mullidae) to examine how food quantity affects growth characteristics and potential success at settlement. Pelagic goatfish were collected from aggregation rafts 3 nautical miles west of Lizard Island on the northern Great Barrier Reef during December 1990. Three tanks in each of four feeding regimes were stocked with 25 pelagic goatfish between 20 and 23 mm standard length (SL). The four feeding regimes were: fed ad lib. (fed): fed once per day (f1pd); starved every second day (stld); starved for 3 d and re-fed (st3d). Fishes were fed 36 to 48 h old Artemia sp. nauplii (Ocean Star strain). Fish were removed from tanks when they underwent metamorphosis, changed pigmentation and settled to the bottom of the tanks. Morphology, muscle development, time taken to settle and biochemical condition were examined. Growth attributes of the treated fish were compared to fish which settled within 24 h of capture (field). All attributes examined were significantly influenced by the feeding treatments. Fish within the fed and st3d treatments were significantly larger and heavier than fish in the less well-fed treatments (f1pd, st1d). Similarly, concentrations of total lipid, carbohydrate and protein in the settled fish were significantly higher in the fed and st3d treatments compared with the st1d and f1pd treatments. For all these morphological and biochemical attributes the st1d and f1pd fish did not significantly differ from the field fishes, but did differ from the fed and st3d fishes. Water content was significantly higher in the f1pd, st1d and field fishes compared with the fed and st3d fish. Furthermore, the average time taken to settle followed the pattern: fed (14d)

Synthesis of polypyridyl complexes of ruthenium(II) containing three different bidentate ligands

Abstract: A general synthetic method has been developed for the synthesis of heteroleptic tris(polypyridyl) complexes of ruthenium(II), [Ru(pp)(pp[prime])(pp[double prime])][sup 2+]. This method opens new avenues for the preparation of molecular assemblies and for the systematic variation of excited-state properties. For example, the results of a study on the ground- and excited-state properties of a series of these complexes reveal a strategy for the preparation of black chromophores which will absorb light strongly throughout the visible region of the spectrum.

Proterozoic low‐pressure/high‐temperature metamorphism and an anticlockwise P–T–t path for the Hazeldene area, Mount Isa Inlier, Queensland, Australia

Abstract: In the Hazeldene area, situated in the Mount Isa Inlier, Queensland, the metamorphic grade changes from chlorite zone, through biotite and cordierite zones, to sillimanite/K-feldspar zone. Microstructural studies of rocks near the sillimanite isograd demonstrate that cordierite grew early during the development of a steep foliation (S2), was replaced by biotite, andalusite and sillimanite at the metamorphic peak late in S2, and in turn by kyanite + chlorite adjacent to localized small post-D2 shear zones. Although the anticlockwise P–T–t path is well defined, the precise P–T conditions are uncertain because of problems with experimental and thermodynamic data. The best estimate for the metamorphic peak for rocks close to the sillimanite isograd is around 600° C at 4 kbar. The metamorphism has been dated at 1544 Ma, and was synchronous with a major crustal shortening event. Because proposed extensional events occurred more than 60 Ma earlier, their contribution to the peak metamorphic thermal perturbation would have been insignificant. The syn-metamorphic Mica Creek Pegmatites, the abundance of high heat-producing elements in the nearby pre-D2 Sybella Granite, and advective heat by fluids which caused considerable metasomatism in the Hazeldene area, may have each contributed to the thermal budget. However, the metamorphic thermal gradient may be 80°C km-1 or higher, strongly suggesting a local magmatic control. As none are known in the area, such syn-metamorphic plutons would have to lie beneath the exposed high-grade rocks.

Estimates of the abundance of the crown-of-throns starfish Acanthaster planci in outbreaking and non-outbreaking populations on reefs within the Great Barrier Reef

Abstract: Criteria used to define outbreaking and non-outbreaking populations of Acanthaster planci are described. Estimates of starfish density were derived for these population types from a series of intensive underwater surveys and from calibrated manta-tow surveys of 334 reefs within the Great Barrier Reef, from January to October 1987. By comparison of these data, density differences were identified between the two populations. Both the mean density and total numbers of non-cryptic crown-of-thorns starfish in outbreaking populations are at least one order of magnitude greater than that in non-outbreaking populations. Non-outbreaking populations may comprise up to 1500 starfish km-2, an order of magnitude less than some previous estimates for reefs within the Great Barrier Reef. Densities of ≳1500 starfish km-2 indicate that an individual reef may be experiencing an outbreak. This density is equivalent to an average of 0.22 starfish per 2 min manta tow over the whole reef. Approximately 90% of reefs classified as out-breaking on the Great Barrier Reef had densities of >1500 starfish km-2, while about 96.5% of reefs classified as non-outbreaking had densities below this level.

Buckling of Pressurized Axisymmetrically Imperfect Cylinders under Axial Loads

Abstract: It has long been recognized that the strength of a thin, axially compressed, unstiffened cylinder is governed by bifurcation into a nonsymmetric displacement mode, that the strength is acutely sensitive to very small geometric imperfections of the surface, and that internal pressure increases the strength markedly. In many practical applications, axially compressed cylinders are simultaneously subject to internal pressure, so the problem is a common one. Despite many theoretical and experimental studies, the strength gains due to internal pressure cannot yet be defined with confidence, and a match between laboratory testing, field imperfection measurement, theoretical bifurcation prediction, and allowable design strength has not yet been achieved. The conservatism of current designs is thus still in doubt. This paper addresses the problem of elastic unstiffened thin cylinders with axisymmetric imperfections, as some field measurements indicate that these imperfections are common in civil engineering struc...

Antarctic ice volume and contribution to sea-level fall at 20,000 yr BP from raised beaches

Abstract: THE contribution of the Antarctic ice sheets to global sea-level fall at the Last Glacial Maximum (LGM) depends largely on how the extent and thickness of peripheral ice changed. Model studies1–3 suggest that there was widespread thickening (from 500 m to more than 1,000 m) of the ice-sheet margins, sufficient to induce a drop in sea level of at least 25 m. Geological evidence4,5, on the other hand, indicates only limited ice expansion and a sea-level fall of just 8 m. Here we use recent data on the altitudes and ages of raised beaches from the Ross embayment and East Antarctica to investigate the timing and extent of Antarctic deglaciation. These indicate that the ice margin during the LGM was thinner and less extensive than has been formerly thought, and that its contribution to the drop in sea level was only 0.5–2.5 m. Deglaciation was well advanced by 10 kyr BP and was complete by 6 kyr BP. These findings imply either that sea level during the LGM fell less than present estimates suggest, or that an ice volume considerably greater than currently accepted must have been present in the Northern Hemisphere.

Microstructural analysis of the classical spiral garnet porphyroblasts of south‐east Vermont: evidence for non‐rotation

Abstract: New data strongly suggest that the classical spiral garnet porphyroblasts of south-east Vermont, USA, generally did not rotate, relative to geographical coordinates, throughout several stages of non-coaxial ductile deformation. The continuity of inclusion trails (Si) in these porphyroblasts is commonly disrupted by planar to weakly arcuate discontinuities, consisting of truncations and differentiation zones where quartz–graphite Si bend sharply into more graphitic Si. Discontinuous, tight microfold hinges with relatively straight axial planes are also present. These microstructures form part of a complete morphological gradation between near-orthogonally arranged, discontinuous inclusion segments and smoothly curving, continuous Si spirals. Some 2700 pitch measurements of well-developed inclusion discontinuities and discontinuous microfold axial planes were taken from several hundred vertically orientated thin sections of various strike, from specimens collected at 28 different locations around the Chester and Athens domes. The results indicate that the discontinuities have predominantly subvertical and subhorizontal orientations, irrespective of variations in the external foliation attitude, macrostructural geometry and apparent porphyroblast-matrix rotation angles. Combined with evidence for textural zoning, this supports the recent hypothesis that porphyroblasts grow incrementally during successive cycles of subvertical and subhorizontal crenulation cleavage development. Less common inclined discontinuities are interpreted as resulting from deflection of anastomosing matrix foliations around obliquely orientated crystal faces prior to inclusion. Most of the idioblastic garnet porphyroblasts have a preferred crystallographic orientation. Dimensionally elongate idioblasts also have a preferred shape orientation, with long axes orientated normal to the mica folia, within which epitaxial nucleation occurred. Truncations and differentiation zones result from the formation of differentiated crenulation cleavage seams against porphyroblast margins, in association with progressive and selective strain-induced dissolution of matrix minerals and locally also the porphyroblast margin. Non-rotation of porphyroblasts, relative to geographical coordinates, suggests that deformation at the microscale is heterogeneous and discontinuous in the presence of undeformed, relatively large and rigid heterogeneities, which cause the progressive shearing (rotational) component of deformation to partition around them. The spiral garnet porphyroblasts therefore preserve the most complete record of the complex, polyphase tectonic and metamorphic history experienced in this area, most of which was destroyed in the matrix by progressive foliation rotation and reactivation, together with recrystallization.

The impact of tropical cyclones on the archaeological record : an Australian example

Abstract: This paper describes the impact of two recent tropical cyclones on the coast and archaeological record at Upstart Bay, North Queensland. Resurveys of Upstart Bay following cyclone 'Charlie' in 1988 and cyclone 'Aivu' in 1989 indicate that considerable damage and even total destruction of late Holocene shell middens has occurred as a direct result of the destructive winds and storm surges associated with these cyclones. Of a total of 93 archaeological sites recorded at Upstart Bay during baseline studies in 1987, more than 50% have now been destroyed. This research raises questions about the effect of cyclones on site preservation throughout prehistory and their likely impact in the future under 'greenhouse' conditions. This study has important implications for the future management of cultural resources in the coastal zone.

Autumn and winter daily precipitation areas in Wales, 1982-1983 to 1986-1987

Abstract: Daily precipitation data from 121 sites for five autumn-winter seasons (September to January, 1982–1983 to 1986–1987) have been analysed to determine discrete precipitation areas within Wales, using S-mode principal components (PCA) and cluster analyses. Using unrotated PCA, much of the variation in daily precipitation is explained by the first five PCs, representing an accumulated variance of 75.7 per cent. The first four PCs appear to relate respectively to: altitude (60.8 per cent of the total variance explained), an exposure effect relative to north or north-east winds (6.0 per cent), a ‘westerly exposure’ effect (4.2 per cent) and an ‘easterly exposure’ effect (2.9 per cent). The fifth PC, with high scores only over Ynys Mǒn and Gwent, could not be attributed to any particular influence. Oblique rotation produced a better simple structure, enhanced the apparent importance of exposure to wind from the main compass directions, but lessened that of altitude. Three methods of clustering PCs were subsequently tried on the Oblimin solution: centroid, median and Ward. The precipitation areas produced by each were broadly similar, and the boundaries between them often coincided with clear topographic units, influenced by exposure and shelter effects. The Ward technique yielded the areas best defined in terms of topography and exposure, and best satisfied criteria determined by the nature of the data themselves.

Do smoothly curving, spiral-shaped inclusion trails signify porphyroblast rotation?

Abstract: Smoothly curving, spiral-shaped inclusion trails may form in porphyroblasts during the overprinting of near-orthogonal foliations in schists that are relatively quartz rich and, in general, graphite poor. The smooth curvature results from the combined effects of (1) the protection from progressive shearing provided by projecting crystal faces and (2) greater competency and generally wider zones of progressive shearing in these rock types than in ones that are less quartz rich and more graphtic. Therefore, lack of truncations or abrupt changes in compositional zoning profiles and the presence of smoothly curving, spiral-shaped inclusion trails do not necessarily signify that the porphyroblast containing them rotated as it grew. This has considerable significance for shear-sense determinations in deformed and metamorphosed rocks.

Preschooler's Use of Microcomputers and Input Devices

Abstract: This study measured the efficiency of use by preschoolers of common input devices including the keyboard, the joystick and the mouse. It also investigated their preferred input device in a free pla...

Intake and digestion in swamp buffaloes and cattle. 2. The comparative response to urea supplements in animals fed tropical grasses

Abstract: Swamp buffaloes (Bubalus bubalis) and crossbred cattle (B. indicus x B. taurus) were offered two forages in two experiments. In Expt 1, four animals of each species were offered mature Rhodes grass hay (Chloris gayana) with a mineral supplement or with a supplement of minerals and urea (17·6 gN/d). In Expt 2, another group of four buffaloes and four cattle were offered mature spear grass hay( Heteropogon contortus) with mineral supplementation at intervals of 3 h. Four levels of urea (0, 5, 21 and 97 g/day) and 35S-sulphate were continuously infused in four periods.Rhodes grass was consumed in greater amounts by cattle, whereas buffaloes ate more spear grass. Urea supplements increased intake of Rhodes grass by 12% in buffaloes and 22% in cattle, and of spear grass by 34% in buffaloes and 41 % in cattle. Digestibility of cell wall constituents and acid-detergent fibre of spear grass was lower (P < 0·05) in buffaloes than in cattle (417 v. 499; 471 v. 560 g/kg respectively). In Expt 2, dry matter digestibility progressively increased (P < 0·05) from 364 to 408 g/kg with increased urea infusion. Rumen dry matter pool increased by 11–21 % on infusion of 97 g urea/day, compared with no urea. Digestion of ground forages incubated in situ in the rumen was depressed below rumen ammonia levels of 30–60 mg N/l, while digestion of cotton thread was depressed below 60–80 mg N/l (Expt 1) or 150–200 mg N/l (Expt 2).Patterns of N content in cotton thread suggested that more microbes attached in buffaloes and there was subsequently faster detachment than in cattle, particularly with increased urea infusion.

The Story So Far: gender, literacy and social regulation

Abstract: This article examines ways in which language practices in the classroom — particularly those involved with the reading and writing of stories — are gendered literacy practices. It argues that stories are closely identified with structuring the meanings by which a culture lives, and that popular and familiar stories rely upon dominant versions of femininity and masculinity to be understood or ‘read’. The article suggests that story genres are ‘gendered’ in the way in which they organise sequences of events, in the discursive fields from which they draw, and in the character‐traiting paradigms they prefer. The claim is made that when children write stories they enter into a form of social regulation implicit in the cultural conventions of popular narrative forms. Story‐writing is seen to be a social, ideological activity which often masquerades as personal expression. The article argues that the gendered nature of classroom literacy practices will be more obviously recognised if classroom language ...

Sedimentology of 40 000 year Milankovitch‐controlled cyclothems from central Hawke's Bay, New Zealand

Abstract: Cyclothemic sedimentary rocks of the Plio-Pleistocene Petane Group outcrop extensively in the Tangoio block of central Hawke's Bay, New Zealand. They are products of inner to mid-shelf sedimentation and were deposited during glacio-eustatic sea level fluctuations along the western margin of a shallow, pericontinental seaway located in a forearc setting. The succession consists of five laterally continuous cyclothems, each containing a fine grained interval of silt and a coarse grained interval of siliciclastic sand ± gravel or limestone. Five sedimentary facies assemblages comprising 20 separate facies have been recognized. Coarse grained intervals of cyclothems were deposited mostly during relative sea level lowstands and contain up to four facies assemblages: (1) a non-marine assemblage (with three component facies, representing braided river and overbank environments); (2) an estuarine assemblage (with three component facies, representing tidal flat and mud-dominated estuarine environments); (3) a siliciclastic shoreline assemblage (with six component facies, representing greywacke pebble beach, shoreface and inner shelf environments); and (4) a carbonate shelf assemblage (with four component facies, representing tide-dominated, inshore and shallow marine environments). Fine grained intervals of cyclothems were deposited during sea level highstands when the Tangoio area was generally experiencing mid-shelf sedimentation. This produced an offshore assemblage consisting of four component facies. The distribution of facies assemblages during relative sea level lowstands was dependent upon proximity to the shoreline, the type and rate of sediment supply to the basin, and shelf hydrodynamics. Carbonate shelf facies dominate coarse grained intervals in Cyclothems 3–5, but siliciclastic shoreline and non-marine facies dominate in Cyclothems 1 and 2. The abrupt change from siliciclastic to carbonate sedimentation during relative sea level lowstand deposition is thought to have been induced by rapidly falling interglacial to glacial sea level accentuated by regional tectonic shoaling. This caused most of the terrigenous sediment supply to bypass the Tangoio area. Consequently, carbonate sediment accumulated in inshore and shallow marine settings. Facies assemblages rarely show lateral interdigitation, but are vertically stratified over the entire Tangoio block. Facies successions in each cyclothem preserve a record of relative sea level change during deposition of the Petane Group and are consistent with a Plio-Pleistocene sea level change in eastern New Zealand of c. 75–150 m, i.e. approximately the magnitude suggested for Late Quaternary glacio-eustatic sea level changes.

Understorey light environments in a north-east Australian rain forest before and after a tropical cyclone

Abstract: This paper describes estimates of canopy openness and associated light availability in the understorey of a north-east Australian rain forest before and immediately after a tropical cyclone. On the basis of 20 hemispherical (fisheye) canopy photographs it was shown that direct, diffuse and total site factors increased significantly as a result of the slight-to-moderate canopy disturbance caused by the cyclone. In the understorey, median total site factors ranged from 2.5–3.4% before the cyclone and from 6.0–8.6% after the cyclone, representing a 2- to 3-fold increase in potential light availability. Following the cyclone, mean relative gap frequencies increased substantially at all altitudes but particularly at canopy positions more than 70° above the horizon. Cyclone-induced canopy disturbance not only reduced the complexity of the understorey light regime but may have also increased the seasonal variability of light within the understorey of the forest during the interval of canopy recovery. The implications of these results for the ecophysiology of understorey tree seedlings and saplings at several temporal scales are discussed.

Citizenship, Education and Postmodernity

Abstract: This paper explores the significance for citizenship education of claims that Western society is undergoing a major cultural reorientation, known by its protagonists as postmodernism, which is said to have wide‐ranging implications for knowledge, morality, politics and individual identities. In particular, the posited changes raise doubts about the future of citizenship, and the discussion reviews two responses to these questions: Heater's optimistic proposal for a return to the classical ideal, and Wexler's pessimistic assessment of the prospects for citizenship in a society dominated by television and the consumption of images. A third perspective is suggested, based on the expansion of the idea of citizenship from civil, political and welfare entitlements to greater participation in the cultural and economic dimensions of everyday life. It is argued that such a concept can inform a comprehensive and coherent approach to citizenship, and a successful curriculum in citizenship education.

Terpenes in sponge cell-membranes - cell-separation and membrane fractionation studies with the tropical marine sponge amphimedon-sp

Abstract: The differing sponge and symbiotic microbial cell types in the tropical marine spongeAmphimedon sp. were fractionated according to density, investigated by electron microscopy, and analyzed by high-performance liquid chromatography and nuclear magnetic resonance for the presence of the terpene metabolite diisocyanoadociane (1) and Δ5,7-sterols (2–7). A sample of whole sponge was dissected into superficial ectosome and deeper choanosome. The superficial tissue was found to be enriched in sterol relative to choanosome; however, extracts from both tissues contained terpene. Dissociation of whole sponge followed by Ficoll density gradient fractionation showed that there are two chemically distinct types of sponge cells inAmphimedon sp.—small non-nucleolated cells of low density contain terpene 1 together with sterols, while larger nucleolated cells contain significant levels of terpene, but only traces of sterol. Membrane fractionation studies were undertaken to establish whether the terpene components were located specifically in the cell membranes of these two cell types. A membrane vesicle pellet spun down at 100,000×g from small sponge cells contained sterols, but only traces of terpene, whereas the membrane vesicle preparation from heavier cells contained both terpenes and sterols. Subsequently, the presence of terpenes together with sterols was demonstrated in a membrane vesicle preparation of purity >90% prepared from bacteria-free sponge cells. These results provide the first experimental evidence that terpenes are associated with sponge cell membranes, where they may function as structural components.