Showing papers by "Macquarie University published in 2002"

Igneous zircon: trace element composition as an indicator of source rock type

Abstract: Trace element abundances in igneous zircons, as determined by electron microprobe and laser-ablation microprobe ICPMS analysis, are shown to be sensitive to source rock type and crystallisation environment. The concentrations of 26 trace elements have been determined for zircons from a wide range of different rock types and reveal distinctive elemental abundances and chondrite-normalised trace element patterns for specific rock types. There is a general trend of increasing trace element abundance in zircons from ultramafic through mafic to granitic rocks. The average content of REE is typically less than 50 ppm in kimberlitic zircons, up to 600–700 ppm in carbonatitic and lamproitic zircons and 2,000 ppm in zircons from mafic rocks, and can reach per cent levels in zircons from granitoids and pegmatites. Relatively flat chondrite-normalised REE patterns with chondrite-normalised Yb/Sm ratios from 3 to 30 characterise zircons from kimberlites and carbonatites, but Yb/Sm is commonly over 100 in zircons from pegmatites. Th/U ratios typically range from 0.1 to 1, but can be 100–1000 in zircons from some carbonatites and nepheline syenite pegmatites. The geochemical signatures characteristic of zircon from some rock types can be recognised in bivariate discriminant diagrams, but multivariate statistical analysis is essential for the discrimination of zircons from most rock types. Classification trees based on recursive partitioning techniques provide a rapid means of relating parent rock type to zircon trace element analysis; zircons from many rock types can be discriminated at confidence levels of 75% or more. These trees allow recognition of the provenance of detrital zircons from heavy mineral concentrates, and significantly enhance the usefulness of zircon in regional crustal studies and as an indicator mineral in mineral exploration.

Cryptanalysis of Block Ciphers with Overdefined Systems of Equations

Abstract: Several recently proposed ciphers, for example Rijndael and Serpent, are built with layers of small S-boxes interconnected by linear key-dependent layers. Their security relies on the fact, that the classical methods of cryptanalysis (e.g. linear or differential attacks) are based on probabilistic characteristics, which makes their security grow exponentially with the number of rounds Nr.In this paper we study the security of such ciphers under an additional hypothesis: the S-box can be described by an overdefined system of algebraic equations (true with probability 1). We show that this is true for both Serpent (due to a small size of S-boxes) and Rijndael (due to unexpected algebraic properties). We study general methods known for solving overdefined systems of equations, such as XL from Eurocrypt'00, and show their inefficiency. Then we introduce a new method called XSL that uses the sparsity of the equations and their specific structure.The XSL attack uses only relations true with probability 1, and thus the security does not have to grow exponentially in the number of rounds. XSL has a parameter P, and from our estimations is seems that P should be a constant or grow very slowly with the number of rounds. The XSL attack would then be polynomial (or subexponential) in Nr, with a huge constant that is double-exponential in the size of the S-box. The exact complexity of such attacks is not known due to the redundant equations. Though the presented version of the XSL attack always gives always more than the exhaustive search for Rijndael, it seems to (marginally) break 256-bit Serpent. We suggest a new criterion for design of S-boxes in block ciphers: they should not be describable by a system of polynomial equations that is too small or too overdefined.

Social Comparison: Why, With Whom, and With What Effect?

Abstract: Social comparison consists of comparing oneself with others in order to evaluate or to enhance some aspects of the self. Evaluation of ability is concerned with the question “Can I do X?” and relies on the existence of a proxy performer. A proxy's relative standing on attributes vis‐a‐vis the comparer and whether the proxy exerted maximum effort on a preliminary task are variables influencing his or her informational utility. Evaluation of opinions is concerned with the questions “Do I like X?”“Is X correct?” and “Will I like X?” Important variables that affect an individual's use of social comparison to evaluate his or her opinions are the other person's expertise, similarity with the individual, and previous agreement with the individual. Whether social comparison serves a self-enhancement function depends on whether the comparer assimilates or contrasts his or her self relative to superior or inferior others. The kinds of self‐knowledge made cognitively accessible and variables such as mutability of se...

Competitive advantages of the latecomer firm : a resource-based account of industrial catch-up strategies

Abstract: The resource-based view of the firm provides a satisfactory account of how firms go about sustaining their existing competitive advantages, but it is less successful in accounting for how firms create such advantages in the first place, or overcome incumbent advantages, when the firms start with few resources. The paper utilizes the case of latecomer firms from the Asia-Pacific region breaking into knowledge-intensive industries such as semiconductors, to illustrate the issues involved and the resource-targeting strategies utilized. This results in a strategic theory of the overcoming of competitive disadvantages through linkage, resource leverage, and learning. The dynamic capabilities of such firms are enhanced through repeated applications of linkage and leverage. The resources strategically targeted are characterized as being those most amenable to such linkage and leverage, namely those that are least rare and most imitable and transferable, i.e. as positive versions of the criteria utilized in the conventional resource-based view of the firm. It is argued that this adaptation of the RBV is potentially of wide applicability, and is the needed amendment that makes it of prime significance in accounting for latecomer success within the conceptual framework of strategic management.

Teaching and Learning in their Disciplinary Contexts: A conceptual analysis

Abstract: The growing literature on undergraduate teaching and learning currently lacks an organising framework. This article sets out to provide one, distinguishing between hard pure, soft pure, hard applied and soft applied fields of study, and hence making it possible to highlight generally unremarked similarities and differences between the various research findings. In doing so, it draws extensively on the relevant literature, offering separate analyses of knowledge-related and socially related studies. The former embody curriculum, assessment and cognitive purpose, while the latter encompass group characteristics of teachers, types of teaching method and student learning requirements. The concluding section draws out the main implications for policy and practice related to staff development, computer-based learning, assessment of student learning and quality measures.

358,534 nonwords: The ARC Nonword Database

Abstract: The authors present a model of the phonotactic and orthographic constraints of Australian and Standard Southern British English monosyllables. This model is used as the basis for a web-based psycholinguistic resource, the ARC Nonword Database, which contains 358,534 monosyllabic nonwords—48,534 pseudohomophones and 310,000 non-pseudohomophonic nonwords. Items can be selected from the ARC Nonword Database on the basis of a wide variety of properties known or suspected to be of theoretical importance for the investigation of reading.

Expression profile analysis of the low-oxygen response in Arabidopsis root cultures.

Abstract: We used DNA microarray technology to identify genes involved in the low-oxygen response of Arabidopsis root cultures. A microarray containing 3500 cDNA clones was screened with cDNA samples taken at various times (0.5, 2, 4, and 20 h) after transfer to low-oxygen conditions. A package of statistical tools identified 210 differentially expressed genes over the four time points. Principal component analysis showed the 0.5-h response to contain a substantially different set of genes from those regulated differentially at the other three time points. The differentially expressed genes included the known anaerobic proteins as well as transcription factors, signal transduction components, and genes that encode enzymes of pathways not known previously to be involved in low-oxygen metabolism. We found that the regulatory regions of genes with a similar expression profile contained similar sequence motifs, suggesting the coordinated transcriptional control of groups of genes by common sets of regulatory factors.

Convergence towards higher leaf mass per area in dry and nutrient‐poor habitats has different consequences for leaf life span

Abstract: Summary 1 Leaf life span (LL) and leaf mass per area (LMA) are fundamental traits in the carbon economy of plants, representing the investment required per unit leaf area (LMA) and the duration of the resulting benefit (LL). Species on dry and infertile soils converge towards higher LMA. It has been generally assumed that this allows species from low-resource habitats to achieve longer average leaf life spans, as LMA and LL are often correlated. 2 Leaf life span and LMA were measured for 75 perennial species from eastern Australia. Species were sampled from nutrient-rich and nutrient-poor sites within high and low rainfall regions. LL and LMA were positively correlated across species within each site. In addition, evolutionary divergences in LL and LMA were correlated within each site, indicating that cross-species relationships were not simply driven by differences between higher taxonomic groups. 3 Within a rainfall zone, LL–LMA combinations shifted as expected along common axes of variation such that species on poorer soils had higher LMA and longer LL, but significantly so only at high rainfall. 4 Low rainfall species were expected to have shorter LL at a given LMA or, equally, require higher LMA to achieve a given LL, i.e. shift to a parallel axis of variation, and this was observed on both nutrient-rich and nutrient-poor soils. On average, 30% higher LMA was seemingly required at dry sites to achieve a given LL. Thus, convergence towards higher LMA has different consequences for leaf life span in dry and nutrient-poor habitats. 5 The broad shifts in LL–LMA combinations between site types were also seen when comparing closely related species-pairs (phylogenetically independent contrasts) occurring on nutrient-rich and nutrient-poor soils (within each rainfall zone), and at high- and low-rainfall sites (at each soil nutrient level).

Efficient classical simulation of continuous variable quantum information processes

Abstract: We obtain sufficient conditions for the efficient simulation of a continuous variable quantum algorithm or process on a classical computer. The resulting theorem is an extension of the Gottesman-Knill theorem to continuous variable quantum information. For a collection of harmonic oscillators, any quantum process that begins with unentangled Gaussian states, performs only transformations generated by Hamiltonians that are quadratic in the canonical operators, and involves only measurements of canonical operators (including finite losses) and suitable operations conditioned on these measurements can be simulated efficiently on a classical computer.

Leaves at low versus high rainfall: coordination of structure, lifespan and physiology

Abstract: Summary • Across species, leaf lifespan (LL) tends to be correlated with leaf mass per area (LMA). Previously we found that Australian perennial species from low-rainfall sites had c . 40% shorter LL at a given LMA than high-rainfall species. • Here we relate indices of leaf strength (work to shear, W shear , and tissue toughness) to LL and LMA across the same suite of species. W shear is the work required to cut a leaf with a blade; W shear divided by leaf thickness gives tissue toughness. • Low- and high-rainfall species did not differ in their LL at a given W shear , but dry-site species had lower W shear at a given LMA, leading to the observed LL – LMA shift with rainfall. These patterns were driven by 50% lower tissue toughness in dry-site species. • The lower toughness was linked with high leaf N concentration, which is known to enhance water conservation during photosynthesis in low-rainfall species. Our results suggest that a significant cost of this strategy is reduced LL for a given investment in leaf tissue (LMA).

Disturbed communication in schizophrenia: the role of poor pragmatics and poor mind-reading.

Abstract: Background. Disturbed speech in schizophrenia may reflect pragmatic deficits of expressive language. Pragmatic comprehension deficits also occur in schizophrenia. This study investigated whether poor 'mind-reading' (i.e. a general difficulty with inferring and monitoring other people's thoughts) causes pragmatic language impairments of both expression and comprehension in patients with schizophrenia. Method. Mind-reading (or theory of mind) was tested in patients with schizophrenia and in healthy controls using a false-belief picture-sequencing task. Pragmatic comprehension skills were assessed using a test of non-literal speech interpretation. Clinical ratings of formal thought disorder (FTD) indexed the expressive language deficits of patients. To control for possible contributory effects of executive dysfunction, inhibitory control was tested using capture picture-sequences and executive-planning was tested using the Tower of London task. Results. False-belief picture-sequencing, understanding of irony and understanding of metaphors were all selectively impaired in the patients. Poor mind-reading (indexed by high error rate in sequencing false-belief stories) was associated with poor understanding of irony, but was unrelated to poor understanding of metaphors. Whereas poor appreciation of irony and poor mind-reading were associated with high ratings of positive formal thought disorder, high ratings of negative formal thought disorder were associated with poor understanding of metaphors and executive dysfunction. Conclusions. Whereas poor mind-reading may contribute to positive aspects of formal thought disorder and impaired appreciation of irony in patients with schizophrenia; negative features of formal thought disorder and poor understanding of metaphors appear better explained by abnormal semantics. Overall, the findings of this study support the view that the functional basis of formal thought disorder in schizophrenia is not unitary.

Common Slope Tests for Bivariate Errors‐in‐Variables Models

Abstract: Summary Likelihood ratio tests are derived for bivariate normal structural relationships in the presence of group structure. These tests may also be applied to less restrictive models where only errors are assumed to be normally distributed. Tests for a common slope amongst those from several datasets are derived for three different cases – when the assumed ratio of error variances is the same across datasets and either known or unknown,and when the standardised major axis model is used. Estimation of the slope in the case where the ratio of error variances is unknown could be considered as a maximum likelihood grouping method. The derivations are accompanied by some small sample simulations,and the tests are applied to data arising from work on seed allometry.

SYSTRA‐SQ: a new measure of bank service quality

Abstract: We describe the development of a new scale designed to measure service quality perceptions of retail bank customers. Empirical studies were performed in two waves. First, qualitative research was undertaken in the form of seven focus groups and 39 one‐to‐one interviews. These produced 963 text items that described customers’ service quality perceptions. These were categorised against the technical and functional service quality schema proposed by Gronroos. Then, a three‐phase, four‐sample, quantitative study was undertaken to derive a quantitative measure of technical and functional service quality. We have developed and validated a new 21‐item scale comprising four dimensions: service system quality, behavioural service quality, service transactional accuracy, and machine service quality. We found that customers evaluate SQ at two levels: organisational and transactional. The parsimony, reliability and validity of the scale suggest this is a measure of high utility to the banking industry.

Dragon Multinational: A New Model for Global Growth

Abstract: The conventional view of globalization sees it as a process driven by giant firms from the Triad regions of North America, Europe, and Japan, shaping the world in their own image. This book contests such a view, describing the extraordinary success of a handful of multinationals from the "Periphery" in globalizing their operations extremely rapidly. Focusing on Acer, the Taiwanese IT company; the Hong Leong hotel group of Singapore; Ispat International in steel; Cemex of Mexico in cement; and Li and Fung from Hong Kong in contract manufacturing, Matthews demonstrates that these firms have been able to utilize strategies of international linkage and leverage to accelerate their global coverage. He contends that they are pioneers of a new kind of global firm, indicators that the global business civilization being created in the 21st century is like to be pluralistic and diverse, offering unprecedented opportunities for firms that know how to enmesh themselves in global networks.

A biopsy system for small cetaceans: darting success and wound healing in tursiops spp.

Abstract: Together with PAXARMS (NZ), we developed a biopsy system for small cetaceans and tested it on four populations of bottlenose dolphins (Tursiops spp.). The system consists of a modified 0.22 caliber rifle, and biopsy darts made out of polycarbonate with stainless steel biopsy tips. Animals were darted at a range of 2-15 m while travelling parallel to the vessel. Overall sampling success for obtaining biopsy samples when an animal was struck ranged from 96.6% to 100% in the four populations. However, hit rate varied for the four different populations. We did not observe a significant difference in strength of the reaction to the darting procedure when an animal was hit or missed, both among and within populations. Data from one population showed no significant difference in the reaction to biopsy sampling by four different age-sex classes. The only factor that had a significant influence on darting success was the hit location. Furthermore, we observed a significant positive correlation between the size of the sample obtained and the reaction to biopsy sampling. Biopsy samples were sufficient for microsatellite and d-loop analysis in 95.8% and for genetic sexing in 99% of all cases. In animals that we observed on a daily basis, wounds were healed after approximately 23 d.

The Insecurity of the Digital Signature Algorithm with Partially Known Nonces

Abstract: We present a polynomial-time algorithm that provably recovers the signer's secret DSA key when a few consecutive bits of the random nonces k (used at each signature generation) are known for a number of DSA signatures at most linear in log q (q denoting as usual the small prime of DSA), under a reasonable assumption on the hash function used in DSA. For most significant or least significant bits, the number of required bits is about log1/2 q , but can be decreased to log log q with a running time qO(1/log log q) subexponential in log q , and even further to two in polynomial time if one assumes access to ideal lattice basis reduction, namely an oracle for the lattice closest vector problem for the infinity norm. For arbitrary consecutive bits, the attack requires twice as many bits. All previously known results were only heuristic, including those of Howgrave-Graham and Smart who recently introduced that topic. Our attack is based on a connection with the hidden number problem (HNP) introduced at Crypto '96 by Boneh and Venkatesan in order to study the bit-security of the Diffie--Hellman key exchange. The HNP consists, given a prime number q , of recovering a number ? ? Fq such that for many known random t ? Fq a certain approximation of t ? is known. To handle the DSA case, we extend Boneh and Venkatesan's results on the HNP to the case where t has not necessarily perfectly uniform distribution, and establish uniformity statements on the DSA signatures, using exponential sum techniques. The efficiency of our attack has been validated experimentally, and illustrates once again the fact that one should be very cautious with the pseudo-random generation of the nonce within DSA.

Sexual dimorphism in lizard body shape: the roles of sexual selection and fecundity selection.

Abstract: Sexual dimorphism is widespread in lizards, with the most consistently dimorphic traits being head size (males have larger heads) and trunk length (the distance between the front and hind legs is greater in females). These dimorphisms have generally been interpreted as follows: (1) large heads in males evolve through male-male rivalry (sexual selection); and (2) larger interlimb lengths in females provide space for more eggs (fecundity selection). In an Australian lizard (the snow skink, Niveoscincus microlepidotus), we found no evidence for ongoing selection on head size. Trunk length, however, was under positive fecundity selection in females and under negative sexual selection in males. Thus, fecundity selection and sexual selection work in concert to drive the evolution of sexual dimorphism in trunk length in snow skinks.

Does service failure influence customer loyalty

Abstract: There is a general consensus that customer loyalty to service providers is not solely dependent upon their level of satisfaction or dissatisfaction. However, the identified antecedents of loyalty remain, at best, highly speculative. The aim of this extensive literature review is to give some understanding of the nature of customer loyalty and the antecedent effects of service dissatisfaction. The research reviewed suggests that customer loyalty is an attitudinal state, reflecting value, trust and commitment within supplier–customer relationships. Satisfaction is one of several antecedents of loyalty. A key influence on loyalty is the offer of unique value-delivering advantages not provided by competitors. Thus firms need to develop positive value-based exit barriers to achieve loyalty. When service failures occur, the recovery process is likely to have a greater impact on loyalty than the original service failure. The key to successful recoveries was found to be the customer's perception of ‘fairness’. Recovery programmes must get it right first time. Customers who remain dissatisfied after a complaint has been handled are more dissatisfied than if no recovery attempt had been made. Dissatisfaction and customer satiation are major causes of a customer's exit. The solution to customer satiation is dynamic value creation. Collection and monitoring of customer data is needed for success and two-way communication is vital. Copyright © 2002 Henry Stewart Publications.

Global Analysis of Outer Membrane Proteins from Leptospira interrogans Serovar Lai

Abstract: Recombinant leptospiral outer membrane proteins (OMPs) can elicit immunity to leptospirosis in a hamster infection model. Previously characterized OMPs appear highly conserved, and thus their potential to stimulate heterologous immunity is of critical importance. In this study we undertook a global analysis of leptospiral OMPs, which were obtained by Triton X-114 extraction and phase partitioning. Outer membrane fractions were isolated from Leptospira interrogans serovar Lai grown at 20, 30, and 37°C with or without 10% fetal calf serum and, finally, in iron-depleted medium. The OMPs were separated by two-dimensional gel electrophoresis. Gel patterns from each of the five conditions were compared via image analysis, and 37 gel-purified proteins were tryptically digested and characterized by mass spectrometry (MS). Matrix-assisted laser desorption ionization-time-of-flight MS was used to rapidly identify leptospiral OMPs present in sequence databases. Proteins identified by this approach included the outer membrane lipoproteins LipL32, LipL36, LipL41, and LipL48. No known proteins from any cellular location other than the outer membrane were identified. Tandem electrospray MS was used to obtain peptide sequence information from eight novel proteins designated pL18, pL21, pL22, pL24, pL45, pL47/49, pL50, and pL55. The expression of LipL36 and pL50 was not apparent at temperatures above 30°C or under iron-depleted conditions. The expression of pL24 was also downregulated after iron depletion. The leptospiral major OMP LipL32 was observed to undergo substantial cleavage under all conditions except iron depletion. Additionally, significant downregulation of these mass forms was observed under iron limitation at 30°C, but not at 30°C alone, suggesting that LipL32 processing is dependent on iron-regulated extracellular proteases. However, separate cleavage products responded differently to changes in growth temperature and medium constituents, indicating that more than one process may be involved in LipL32 processing. Furthermore, under iron-depleted conditions there was no concomitant increase in the levels of the intact form of LipL32. The temperature- and iron-regulated expression of LipL36 and the iron-dependent cleavage of LipL32 were confirmed by immunoblotting with specific antisera. Global analysis of the cellular location and expression of leptospiral proteins will be useful in the annotation of genomic sequence data and in providing insight into the biology of Leptospira.

Are There Ethnic Enclaves/Ghettos in English Cities?.

Abstract: The residential segregation of ethnic groups in urban areas remains an issue of importance for policy-making in multicultural societies, such as England's, with levels of segregation frequently lin...

Rapid genetic deterioration in captive populations: Causes and conservation implications

Abstract: Many species require captive breeding to ensuretheir survival. The eventual aim of suchprograms is usually to reintroduce the speciesinto the wild. Populations in captivitydeteriorate due to inbreeding depression, lossof genetic diversity, accumulation of newdeleterious mutations and genetic adaptationsto captivity that are deleterious in the wild.However, there is little evidence on themagnitude of these problems. We evaluatedchanges in reproductive fitness in populationsof Drosophila maintained under benigncaptive conditions for 50 generations witheffective population sizes of 500 (2replicates), 250 (3), 100 (4), 50 (6) and 25(8). At generation 50, fitness in the benigncaptive conditions was reduced in smallpopulations due to inbreeding depression andincreased in some of the large populations dueto modest genetic adaptation. When thepopulations were moved to `wild' conditions,all 23 populations showed a marked decline(64–86%percnt;) in reproductive fitness compared tocontrols. Reproductive fitness showed acurvilinear relationship with population size,the largest and smallest population sizetreatments being the worst. Genetic analysesindicated that inbreeding depression andgenetic adaptation were responsible for thegenetic deterioration in `wild' fitness.Consequently, genetic deterioration incaptivity is likely to be a major problem whenlong-term captive bred populations ofendangered species are returned to the wild. Aregime involving fragmentation of captivepopulations of endangered species is suggestedto minimize the problems.