Showing papers by "Macquarie University published in 2001"

Two contrasting granite types: 25 years later

Abstract: The concept of I‐ and S‐type granites was introduced in 1974 to account for the observation that, apart from the most felsic rocks, the granites in the Lachlan Fold Belt have properties that generally fall into two distinct groups. This has been interpreted to result from derivation by partial melting of two kinds of source rocks, namely sedimentary and older igneous rocks. The original publication on these two granite types is reprinted and reviewed in the light of 25 years of continuing study into these granites.

How closely correlated are molecular and quantitative measures of genetic variation? A meta-analysis

Abstract: The ability of populations to undergo adaptive evolution depends on the presence of quantitative genetic variation for ecologically important traits. Although molecular measures are widely used as surrogates for quantitative genetic variation, there is controversy about the strength of the relationship between the two. To resolve this issue, we carried out a meta-analysis based on 71 datasets. The mean correlation between molecular and quantitative measures of genetic variation was weak (r 5 0.217). Furthermore, there was no significant relationship between the two measures for life-history traits ( r 52 0.11) or for the quantitative measure generally considered as the best indicator of adaptive potential, heritability ( r 52 0.08). Consequently, molecular measures of genetic diversity have only a very limited ability to predict quantitative genetic variability. When information about a population's short-term evolutionary potential or estimates of local adaptation and population divergence are required, quantitative genetic variation should be measured directly.

Strategy shifts in leaf physiology, structure and nutrient content between species of high- and low-rainfall and high- and low-nutrient habitats

Abstract: Summary 1. Relationships were examined among photosynthetic capacity ( A mass and A area ), foliar dark respiration rate ( R d-mass and R d-area ), stomatal conductance to water ( G s ), specific leaf area (SLA), and leaf nitrogen (N) and phosphorus (P) across 79 perennial species occurring at four sites with contrasting rainfall levels and soil nutrients in eastern Australia. We hypothesized that the slope of log‐log ‘scaling’ relationships between these traits would be positive and would not differ between sites, although slope elevations might shift between habitat types. 2. A mass , R d-mass , SLA, N mass and P mass were positively associated in common slopes fitted across sites or rainfall zones, although rather weakly within individual sites in some cases. The relationships between A mass (and R d-mass ) with each of N mass and SLA were partially independent of each other, with A mass (or R d-mass ) increasing with SLA at a given N mass , or with N mass at a given SLA (only weakly in the case of A mass ). These results improve the quantification and extend the generalization of reported patterns to floras largely unlike those studied previously, with the additional contribution of including phosphorus data. 3. Species from drier sites differed in several important respects. They had (i) higher leaf N and P (per dry mass or area); (ii) lower photosynthetic capacity at a given leaf N or P; (iii) higher R d-mass at a given SLA or A mass ; and (iv) lower G s at a given A area (implying lower internal CO 2 concentration). 4. These trends can be interpreted as part of a previously undocumented water conservation strategy in species from dry habitats. By investing heavily in photosynthetic enzymes, a larger drawdown of internal CO 2 concentration is achieved, and a given photosynthetic rate is possible at a lower stomatal conductance. Transpirational water use is similar, however, due to the lower-humidity air in dry sites. The benefit of the strategy is that dry-site species reduce water loss at a given A area , down to levels similar to wet-site species, despite occurring in lower-humidity environments. The cost of high leaf N is reflected in higher dark respiration rates and, presumably, additional costs incurred by N acquisition and increased herbivory risk.

An introduction to long-memory time series models and fractional differencing

Abstract: The idea of fractional differencing is introduced in terms of the infinite filter that corresponds to the expansion of (1 - B)d. When the filter is applied to white noise, a class of time series is generated with distinctive properties, particularly in the very low frequencies and provides potentially useful long-memory forecasting properties. Such models are shown possibly to arise from aggregation of independent components. Generation and estimation of these models are considered and applications on generated and real data presented.

The Management, Measurement and Reporting of Intellectual Capital

Abstract: The rise of the “new economy”, one principally driven by information and knowledge, international competitiveness and changing patterns of interpersonal activities is attributed to the increased prominence of intellectual capital (IC) as a management and research topic. There is indeed much to support the assertion that IC in the new century will be instrumental in the determination of enterprise value and national economic performance. Stemming from this awareness of the value of know‐how is a drive to establish new metrics that can be used to record and report the value attributable to knowledge within an organisation. The task has been given impetus by the fact that early work appearing in the accounting financial reports of Swedish companies involves the application of non‐financial metrics and focuses on intangible assets. This represents a significant departure from traditional financial and management accounting orthodoxy.

GlycoMod--a software tool for determining glycosylation compositions from mass spectrometric data.

Abstract: GlycoMod (http://www.expasy.ch/tools/glycomod/) is a software tool designed to find all possible compositions of a glycan structure from its experimentally determined mass. The program can be used to predict the composition of any glycoprotein-derived oligosaccharide comprised of either underivatised, methylated or acetylated monosaccharides, or with a derivatised reducing terminus. The composition of a glycan attached to a peptide can be computed if the sequence or mass of the peptide is known. In addition, if the protein is known and is contained in the SWISS-PROT or TrEMBL databases, the program will match the experimentally determined masses against all the predicted protease-produced peptides (including any post-translational modifications annotated in these databases) which have the potential to be glycosylated with either N- or O-linked oligosaccharides. Since many possible glycan compositions can be generated from the same mass, the program can apply compositional constraints to the output if the user supplies either known or suspected monosaccharide constituents. Furthermore, known oligosaccharide structural constraints on monosaccharide composition are also incorporated into the program to limit the output.

The adaptive model of thermal comfort and energy conservation in the built environment.

Abstract: Current thermal comfort standards and the models underpinning them purport to be equally applicable across all types of building, ventilation, occupancy pattern and climate zone. A recent research project sponsored by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE, RP-884) critically evaluated these assumptions by statistically analysing a large database of research results in building comfort studies from all over the world (n=22,346). The results reported in this paper indicated a clear dependence of indoor comfort temperatures on outdoor air temperatures (instead of outdoor effective temperature ET* used in RP-884), especially in buildings that were free-running or naturally ventilated. These findings encourage significant revisions of ASHRAE’s comfort standard in terms of climatically relevant prescriptions. The paper highlights the potential for reduced cooling energy requirements by designing for natural or hybrid ventilation in many moderate climate zones of the world.

The management, measurement and the reporting of intellectual capital

Abstract: The rise of the “new economy”, one principally driven by information and knowledge, international competitiveness and changing patterns of interpersonal activities is attributed to the increased prominence of intellectual capital (IC) as a management and research topic. There is indeed much to support the assertion that IC in the new century will be instrumental in the determination of enterprise value and national economic performance. Stemming from this awareness of the value of know‐how is a drive to establish new metrics that can be used to record and report the value attributable to knowledge within an organisation. The task has been given impetus by the fact that early work appearing in the accounting financial reports of Swedish companies involves the application of non‐financial metrics and focuses on intangible assets. This represents a significant departure from traditional financial and management accounting orthodoxy.

The sustainability debate

Abstract: This paper serves as an introduction to this special issue of the journal on the topic of sustainability. It commences with definitions of sustainability, followed by a description of the roles played by governments and corporations as developers of standards and legislation, and investors in products and processes, respectively. The paper then goes on to discuss the company capacities required to achieve sustainability, paying particular attention to operations management capabilities and the management of human resources. The discussion of these topics is related to the content of the other papers subsequently presented in this special issue, and the paper concludes with suggestions for further research.

Morphological and ecological complexity in early eukaryotic ecosystems

Abstract: Molecular phylogeny and biogeochemistry indicate that eukaryotes differentiated early in Earth history. Sequence comparisons of small-subunit ribosomal RNA genes suggest a deep evolutionary divergence of Eukarya and Archaea1; C27–C29 steranes (derived from sterols synthesized by eukaryotes) and strong depletion of 13C (a biogeochemical signature of methanogenic Archaea) in 2,700 Myr old kerogens independently place a minimum age on this split2,3. Steranes, large spheroidal microfossils, and rare macrofossils of possible eukaryotic origin occur in Palaeoproterozoic rocks4,5,6. Until now, however, evidence for morphological and taxonomic diversification within the domain has generally been restricted to very late Mesoproterozoic and Neoproterozoic successions7. Here we show that the cytoskeletal and ecological prerequisites for eukaryotic diversification were already established in eukaryotic microorganisms fossilized nearly 1,500 Myr ago in shales of the early Mesoproterozoic Roper Group in northern Australia.

The Representation of Snow in Land Surface Schemes: Results from PILPS 2(d)

Abstract: Twenty-one land surface schemes (LSSs) performed simulations forced by 18 yr of observed meteorological data from a grassland catchment at Valdai, Russia, as part of the Project for the Intercomparison of Land-Surface Parameterization Schemes (PILPS) Phase 2(d). In this paper the authors examine the simulation of snow. In comparison with observations, the models are able to capture the broad features of the snow regime on both an intra- and interannual basis. However, weaknesses in the simulations exist, and early season ablation events are a significant source of model scatter. Over the 18-yr simulation, systematic differences between the models’ snow simulations are evident and reveal specific aspects of snow model parameterization and design as being responsible. Vapor exchange at the snow surface varies widely among the models, ranging from a large net loss to a small net source for the snow season. Snow albedo, fractional snow cover, and their interplay have a large effect on energy available for ablation, with differences among models most evident at low snow depths. The incorporation of the snowpack within an LSS structure affects the method by which snow accesses, as well as utilizes, available energy for ablation. The sensitivity of some models to longwave radiation, the dominant winter radiative flux, is partly due to a stability-induced feedback and the differing abilities of models to exchange turbulent energy with the atmosphere. Results presented in this paper suggest where weaknesses in macroscale snow modeling lie and where both theoretical and observational work should be focused to address these weaknesses.

The knowledge management spectrum – understanding the KM landscape

Abstract: Knowledge management (KM) is the subject of much literature, discussion, planning and some action. Effectively implementing a sound KM strategy and becoming a knowledge–based company is seen as a mandatory condition of success for organizations as they enter the era of the knowledge economy. Yet KM remains a broadly ill–defined term, with many, often disparate management theories, applications and technologies claiming a place under the KM banner. Read individually, the literature often presents a single view of what is a multifaceted topic. The KM spectrum has been developed to assist organizations in understanding the range of KM options, applications and technologies available to them. It provides a view of the totality and complexity of the various KM theories, tools and techniques presented in the literature. It provides a framework within which management can balance its KM focus and establish and communicate its strategic KM direction. This article introduces the KM spectrum as a synthesis of current KM theories, applications, tools and technologies described in the literature.

Relationships between leaf lifespan and structural defences in a low-nutrient, sclerophyll flora

Abstract: Summary 1. The spectrum between species with low leaf mass per area (LMA), short-lived leaves and high photosynthetic rate to those with high LMA, long-lived leaves and low photosynthetic rate is one of the major spectra of variation between plant species, and is of particular relevance to the ‘carbon-gain strategy’ of plants. 2. In this study the relationship between physical properties of leaves and their lifespan was quantified for 17 sclerophyllous species from a nutrient-poor woodland in eastern Australia. Fracture properties of leaves (force of fracture, tissue toughness) and other leaf traits [LMA, thickness, dry-matter content (DMC), leaf area] were measured for each species and evaluated as predictors of leaf lifespan in cross-species and phylogenetic analyses, and for intercorrelation with one another. 3. The LMA, mean force of fracture, leaf thickness and leaf area each explained approximately 30‐40% of variation in leaf lifespan. Leaf toughness explained 25% of variation in leaf lifespan, and DMC 12%. Leaf toughness and DMC were correlated with each other, but not with leaf thickness. Leaf thickness and toughness were related closely to LMA, while DMC and LMA were only marginally correlated. 4. Nutrients can be withdrawn prior to leaf death and redeployed elsewhere in the canopy when leaf death is initiated by a plant. However, when control is external to the plant these nutrients are lost. There may be advantages to increasing defence to give a high likelihood that the plant has control over the timing of leaf death.

Modulation of hippocampal and amygdalar-evoked activity of nucleus accumbens neurons by dopamine: cellular mechanisms of input selection.

Abstract: Inputs from multiple sites in the telencephalon, including the hippocampus and basolateral amygdala (BLA), converge on neurons in the nucleus accumbens (NAc), and dopamine (DA) is believed to play an essential role in the amplification and gating of these different limbic inputs. The present study used extracellular single-unit recordings of NAc neurons in combination with chronoamperometric sampling of mesoaccumbens DA efflux to assess the importance of DA in the integration of different limbic inputs to the NAc. Tetanic stimulation of the fimbria potentiated hippocampal-evoked firing activity of NAc neurons and increased DA extracellular levels. Systemic administration of the D1 receptor antagonist SCH23390 or the NMDA receptor antagonist CPP abolished the potentiation of hippocampal-evoked activity and produced a D2receptor-mediated suppression of evoked firing. In neurons that received converging input from the hippocampus and BLA, fimbria tetanus potentiated hippocampal-evoked firing activity and suppressed BLA-evoked activity in the same neurons. Both D1 and NMDA receptors participated in the potentiation of fimbria-evoked activity, whereas the suppression of BLA-evoked activity was blocked by either D1 receptor antagonism with SCH23390 or the adenosine A1 antagonist 8-cyclopentyl-1,2-dimethylxanthine. Coincidental tetanus of both the fimbria and BLA resulted in potentiation of both inputs, indicating that DA and adenosine-mediated suppression of BLA-evoked firing was activity-dependent. These data suggest that increases in mesoaccumbens DA efflux by hippocampal afferents to the NAc play a critical role in an input selection mechanism, which can ensure preferential responding to the information conveyed from the hippocampus to the ventral striatum.

The impact of habitat fragmentation on dispersal of Cunningham's skink (Egernia cunninghami): evidence from allelic and genotypic analyses of microsatellites

Abstract: The effects of habitat fragmentation on processes within and among populations are important for conservation management. Despite a broad spectrum of lifestyles and the conservation significance of many reptiles, very little work on fine-scale population genetics has been carried out on this group. This study examines the dispersal patterns of a rock crevice-dwelling lizard, Cunningham's skink (Egernia cunninghami), in a naturally vegetated reserve and an adjacent deforested site. Both genotypic and genic approaches were employed, using microsatellite loci. The spatial organization of individuals with respect to pairwise relatedness coefficients and allele frequencies, along with assignment tests, were used to infer dispersal characteristics for both sexes in a natural and a cleared area. The distribution of relatedness in both habitats was spatially structured, with E. cunninghami showing high pairwise relatedness within their rocky retreat sites. Analysis of relatedness over different spatial scales, spatial autocorrelation of alleles and assignment tests, all indicated that both sexes in the cleared area show less dispersal than their counterparts in the reserve. Furthermore, deforestation may inhibit female dispersal to a greater extent than that of males. The geographical structuring of allele frequencies for adults in the cleared area, but not the reserve, indicates that habitat fragmentation has the potential to alter at least the microevolution of E. cunninghami populations.

The Delphi Method and Health Research

Abstract: The Delphi method is well suited to the research needed to inform health education and health promotion campaigns. This paper measures the current interest in the method by way of a literature review. It then describes how the method has evolved from its inception in the 1950s, to its current form. The focus is on a Delphi variant that is particularly relevant to health education – the Policy Delphi. The benefits of the method for the developer of health education and health promotion campaigns are then discussed. The main benefits relate to the gaining of expert opinions without the time and geographical restraints involved in alternative methods. The anonymity that is central to the Delphi method also has benefits for the researcher. The last section of the paper deals with potential pitfalls in the Delphi method that might undermine the successful application of the method, and recommends steps the practitioner can take to address these pitfalls.

Identical Words are Read Differently in Different Languages

Abstract: It is hypothesized that written languages differ in the preferred grain size of units that emerge during reading acquisition. Smaller units (graphemes, phonemes) are thought to play a dominant role in relatively consistent orthographies (e.g., German), whereas larger units (bodies, rhymes) are thought to be more important in relatively inconsistent orthographies (e.g., English). This hypothesis was tested by having native English and German speakers read identical words and nonwords in their respective languages (zoo-Zoo, sand-Sand, etc.). Although the English participants exhibited stronger body-rhyme effects, the German participants exhibited a stronger length effect for words and nonwords. Thus, identical items were processed differently in different orthographies. These results suggest that orthographic consistency determines not only the relative contribution of orthographic versus phonological codes within a given orthography; but also the preferred grain size of units that are likely to be functional during reading.

Multiple microtubule alterations are associated with Vinca alkaloid resistance in human leukemia cells

Abstract: Vinca alkaloids are used extensively in the treatment of childhood acute lymphoblastic leukemia (ALL) and despite their usefulness, drug resistance remains a serious clinical problem. Vinca alkaloids bind to the beta-tubulin subunit of the alpha/beta-tubulin heterodimer and inhibit polymerization of microtubules. Recent studies have implicated altered beta-tubulin isotype expression and mutations in resistance to microtubule-stabilizing agents. Microtubule-associated protein (MAP) MAP4 binds to and stabilizes microtubules, and increased expression is associated with decreased sensitivity to microtubule-depolymerizing agents. To address the significance of beta-tubulin and MAP4 alterations in childhood ALL, two CCRF-CEM-derived Vinca alkaloid resistant cell lines, VCR R (vincristine) and VLB100 (vinblastine), were examined. Decreased expression of class III beta-tubulin was detected in both VCR R and VLB100 cells. VCR R cells and to a lesser extent VLB100 cells expressed increased levels of MAP4 protein. Increased microtubule stability was observed in these VCR R cells as identified by the high levels of polymerized tubulin (45.6 +/- 2.6%; P ATC; Leu(240)-->Ile) that was not present in CEM or VLB100 cells. This mutation resides in a region of beta-tubulin that lies in close proximity to the alpha/beta tubulin interface. Multiple alterations related to normal microtubule function were identified in ALL cells selected for resistance to Vinca alkaloids, and these alterations may provide important insight into mechanisms mediating resistance to Vinca alkaloids.

Teleworking: Frameworks for Organizational Research

Abstract: Teleworking is a work practice that entails remote working for at least some of the time. Common arrangements include work done at home or in the field, by teleworkers in a range of occupations. As such, telework is one of the most radical departures from standard working conditions in the suite of flexible work practices now gaining widespread acceptance. In this paper, we develop an explanatory model of organizational adoption of teleworking. We do this as a means of integrating the current literature on the incidence of teleworking and to provide a theoretical grounding and framework for understanding differentials in the growth of teleworking in different organizations, industries and countries. We begin by developing an appropriate framework for conceptualizing teleworking. We propose a multivariate approach that is able to differentiate the various forms of teleworking. We then use this framework to develop a model and a series of propositions concerning the adoption of different forms of teleworking. Neo-institutional theory, as well as recent empirical evidence on teleworking informs this model.

Superdeep diamonds from the Juina area, Mato Grosso State, Brazil

Abstract: Alluvial diamonds from the Juina area in Mato Grosso, Brazil, have been characterized in terms of their morphology, syngenetic mineral inclusions, carbon isotopes and nitrogen contents. Morphologically, they are similar to other Brazilian diamonds, showing a strong predominance of rounded dodecahedral crystals. However, other characteristics of the Juina diamonds make them unique. The inclusion parageneses of Juina diamonds are dominated by ultra-high-pressure ("superdeep") phases that differ both from "traditional" syngenetic minerals associated with diamonds and, in detail, from most other superdeep assemblages. Ferropericlase is the dominant inclusion in the Juina diamonds. It coexists with ilmenite, Cr-Ti spinel, a phase with the major-element composition of olivine, and SiO2. CaSi-perovskite inclusions coexist with titanite (sphene), "olivine" and native Ni. MgSi-perovskite coexists with TAPP (tetragonal almandine-pyrope phase). Majoritic garnet occurs in one diamond, associated with CaTi-perovskite, Mn-ilmenite and an unidentified Si-Mg phase. Neither Cr-pyrope nor Mg-chromite was found as inclusions. The spinel inclusions are low in Cr and Mg, and high in Ti (Cr2O3 10 wt%). Most ilmenite inclusions have low MgO contents, and some have very high (up to 11.5 wt%) MnO contents. The rare "olivine" inclusions coexisting with ferropericlase have low Mg# (87–89), and higher Ca, Cr and Zn contents than typical diamond-inclusion olivines. They are interpreted as inverted from spinel-structured (Mg, Fe)2Si2O4. This suite of inclusions is consistent with derivation of most of the diamonds from depths near 670 km, and adds ilmenite and relatively low-Cr, high-Ti spinel to the known phases of the superdeep paragenesis. Diamonds from the Juina area are characterized by a narrow range of carbon isotopic composition (δ13C=–7.8 to –2.5‰), except for the one majorite-bearing diamond (δ13C=–11.4‰). There are high proportions of nitrogen-free and low-nitrogen diamonds, and the aggregated B center is predominant in nitrogen-containing diamonds. These observations have practical consequences for diamond exploration: Low-Mg olivine, low-Mg and high-Mn ilmenite, and low-Cr spinel should be included in the list of diamond indicator minerals, and the role of high-Cr, low-Ti spinel as the only spinel associated with diamond, and hence as a criterion of diamond grade in kimberlites, should be reconsidered.