Showing papers by "Macquarie University published in 1992"

Comparative evolutionary ecology of seed size

Abstract: A seedling's chances of establishing successfully are likely to be affected by the quantity of metabolic reserves in the seed. Seed size is thought to evolve as a compromise between producing numerous smaller seeds, each with few resources, and fewer larger seeds, each with more resources. Seed size varies 10 11 -fold across plant species, so the compromise has been struck at very different levels. These basic ideas have been accepted for 50 years, and many studies have interpreted seed size differences between species by reference to larger seed size being adaptive under a variety of hazards. However, experimental tests of the benefits of large seed size in relation to particular hazards have been rare. More experiments are now being reported, but a consistent picture has yet to emerge. There is typically at least a 10 5 -fold range of seed mass between species even within a single area, suggesting that much seed size variation is evolutionarily associated with other plant attributes.

Entangled coherent states

Abstract: The nonlinear Mach-Zehnder interferometer is presented as a device whereby a pair of coherent states can be transformed into an entangled superposition of coherent states for which the notion of entanglement is generalized to include nonorthogonal, but distinct, component states. Each mode is directed to a homodyne detector. We show that there exist nonclassical intensity correlations at the output ports of the homodyne detectors which facilitate a test of local realism. In contradistinction to previous optical schemes which test local realism, the initial state used here possesses a positive Glauber-Sudarshan representation and is therefore a semiclassical state. The nonlinearity itself is responsible for generating the nonclassical state.

The cross-cultural generalizability of the relation between participation, budget emphasis and job related attitudes

Abstract: This study uses Hofstede's cultural dimensions of power distance and individualism (Hofstede, G. H., Culture's Consequences: International Differences in Work-Related Values , 1980) to examine the cross-cultural or cross-national generalizability of participation's effect on the relation between budget emphasis in superior evaluate style and subordinates' job related attitudes. It is hypothesized that participation's effect will be the same in low power distance/high individualism and high power distance/low individualism cultures. The hypotheses are tested with respondent samples from Australia and Singapore as proxy nations. The results lend support to the hypotheses and carry implications for the cross-national transferability of the design characteristics of management accounting systems.

Point-defect energies in the nitrides of aluminum, gallium, and indium.

Abstract: Experimental data on the nature and energetic location of levels associated with native point defects in the group-III metal nitrides are critically reviewed and compared with theoretical estimates. All three show strong evidence of the existence of a triplet of donorlike states associated with the nitrogen vacancy. Ground states are at about 150, 400, and 900 meV from the conduction-band edge in InN, GaN, and AlN, respectively, with their charged derivatives lying closer to the band edge. These values agree with both modified-hydrogenic and deep-level calculations, surprisingly well in view of the inherent approximations in each in this depth range. The InN donor ground state is both optically active and usually occupied, showing a distinctive absorption band which is very well described by quantum-defect analysis. Variation of threshold with electron concentration shows a Moss-Burstein shift commensurate with that observed in band-to-band absorption. In both GaN and AlN, levels have been identified at about 1/4${\mathit{E}}_{\mathit{G}}$ and about 3/4${\mathit{E}}_{\mathit{G}}$, which correlate well with predictions for the antisite defects ${\mathrm{N}}_{\mathit{M}}$ and ${\mathit{M}}_{\mathrm{N}}$, respectively, while similar behavior in InN is at odds with theory. The metal-vacancy defect appears to generate a level somewhat below midgap in AlN and close to the valence-band edge in GaN, but has not been located experimentally in InN, where it is predicted to lie very close to the valence-band edge. A tentative scheme for the participation of two of the native defects in GaN, namely ${\mathit{V}}_{\mathrm{N}}$ and ${\mathrm{N}}_{\mathrm{Ga}}$, in the four broad emission bands found in Zn-compensated and undoped GaN is offered.

A high-frequency survey of the southern Galactic plane for pulsars

Abstract: Results of an HF survey designed to detect young, distant, and short-period pulsars are presented. The survey detected a total of 100 pulsars, 46 of which were previously unknown. The periods of the newly discovered pulsars range between 47 ms and 2.5 ms. One of the new discoveries, PSR 1259-63, is a member of a long-period binary system. At least three of the pulsars have ages less than 30,000 yr, bringing the total number of such pulsars to 12. The majority of the new discoveries are distant objects with high dispersion measures, which are difficult to detect at low frequencies. This demonstrates that the survey has reduced the severe selection effects of pulse scattering, high Galactic background temperature, and dispersion broadening, which hamper the detection of such pulsars at low radio frequencies. The pulsar distribution in the southern Galaxy is found to extend much further from the Galactic center than that in the north, probably due to two prominent spiral arms in the southern Galaxy.

Evolution of sex determination and the Y chromosome: SRY -related sequences in marsupials

Abstract: IN mammals, testis determination is under the control of the testis-determining factor borne by the Y chromosome1,2. SRY, a gene cloned from the sex-determining region of the human Y chromosome, has been equated with the testis-determining factor in man3–5 and mouse6,7. We have used a human SRY probe to identify and clone related genes from the Y chromosome of two marsupial species. Comparisons of eutherian and metatherian Y-located SRY sequences suggest rapid evolution of these genes, especially outside the region encoding the DNA-binding HMG box. The SRY homologues, together with the mouse Ubely homologues8, are the first genes to be identified on the marsupial Y chromosome.

Long-lived reactive species on free-radical-damaged proteins.

Abstract: We have demonstrated two novel reactive species on radical-modified proteins which are relatively long-lived, one oxidizing and one reducing. The two species are reactive with critical biological components, and so may be of physiological and pathological importance. The oxidizing species, which have been identified as protein hydroperoxides, can consume key cellular reductants, such as ascorbate and glutathione. The reducing species can act on both free and metalloprotein forms of copper and iron ions, which participate in radical generation. These findings suggest that proteins may act as traps for the chemical energy released by free radicals, with the capacity to pass it on to other molecules. The long-lived nature of both the reactive moieties indicates that they may be able to diffuse and transfer damaging reactions to distant sites.

Accounting: filling the negative space.

Abstract: The issue of this paper is not with the man-woman dichotomy, that is, gender, but with the Universal Feminine and Universal Masculine, also called, in Oriental cultures, the “Yin” and “Yang”. From this perspective, the interplay, tension, complementarity and union of opposites of the Universal Feminine and Masculine, or Yin and Yang, is seen to pervade all existence. Reduction of the interdependent Yin and Yang to the materialist woman-man dichotomy leaves the source of many environmental and social problems invisible and unaddressed. That source is a consciousness which is imbalanced towards the values and orientation of the Yang, resulting from a cultural repression of the realm of the Yin. Accounting — management, financial and international — represents a most extreme manifestation and embodiment of the Yang. Mainstream accounting research also reflects and reproduces the Yang orientation, without a balancing of and by the Yin. Alternative accounting research to the mainstream, may be seen as both reflecting and socially constructing a re-emergence of the values associated with the Yin.

Self-regulatory mechanisms governing gender development.

Abstract: This study tested predictions about development of gender-related thought and action from social cognitive theory. Children at 4 levels of gender constancy were assessed for their gender knowledge, personal gender standards, and gender-linked behavior under different situational conditions. Irrespective of gender constancy level, all children engaged in more same-sex than cross-sex typed behavior. Younger children reacted in a gender stereotypic manner to peers' gender-linked behavior but did not regulate their own behavior on the basis of personal gender standards. Older children exhibited substantial self-regulatory guidance based on personal standards. They expressed anticipatory self-approval for same-sex typed behavior and self-criticism for cross-sex typed behavior. Their anticipatory self-sanctions, in turn, predicted their actual gender-linked behavior. Neither gender knowledge nor gender constancy predicted gender-linked behavior. These results lend support to social cognitive theory that evaluation and regulation of gender-linked conduct shifts developmentally from anticipatory social sanctions to anticipatory self-sanctions rooted in personal standards.

Lying and Truthfulness: Children's Definitions, Standards, and Evaluative Reactions

Abstract: Preschool (M= 4.9 years), second- (M= 7.8 years), and fifth- (M= 11.0 years) grade children's definitions of, moral standards for, and internal evaluative reactions to both lies and truthful statements were investigated. The influence of 4 factors on these judgments was also examined: the falsity of the statement, the content of the statement, whether or not the statement was believed, and whether or not the statement resulted in punishment. Results revealed that while the older children identified almost all statements correctly, preschoolers correctly identified about 70% of lies and truthful statements. Lies were rated as worse than truthful statements by all age groups; however, only the second and fifth graders ascribed feelings of pride to story characters after truthfulness. Implications of these findings for children's moral development are discussed.

Germination biology of selected central Australian plants

Abstract: Risk spreading of germination may be particularly common in environments with unpredictable climates Germinability, propensity to germinate at different temperatures and germination speed were classified for seeds of 105 species from the central Australian arid zone, and related to plant growth form, perenniality, seed size and seed dispersal mode Almost all species had at least some seeds which were dormant, consistent with the idea that risk spreading is important in arid zones Dispersal mode and plant perenniality were not found to be associated with germinability Seeds of most species germinated rapidly relative to what has been recorded from higher-rainfall environments, as might be expected in an environment where wet soils are usually temporary Faster germination tended to be associated with low germinability, suggesting a spectrum of strategies from species that risk a small number of their seeds in many rainfall events, to those that germinate only in large rainfall events but then risk large numbers of seeds

Modeling problems in conservation genetics using captive Drosophila populations: Rapid genetic adaptation to captivity

Abstract: Long-term captive breeding programs for endangered species generally aim to preserve the option of release back into the wild. However, the success of re-release programs will be jeopardized if there is significant genetic adaptation to the captive environment. Since it is difficult to study this problem in rare and endangered species, a convenient laboratory animal model is required. The reproductive fitness of a large population of Drosophila melanogaster maintained in captivity for 12 months was compared with that of a recently caught wild population from the same locality. The competitive index measure of reproductive fitness for the captive population was twice that of the recently caught wild population, the difference being highly significant. Natural selection over approximately eight generations in captivity has caused rapid genetic adaptation. Captive breeding strategies for endangered species should minimize adaptation to captivity in populations destined for reintroduction into the wild. A framework for predicting the impact of factors on the rate of genetic adaptation to captivity is suggested. Equalization of family sizes is predicted to approximately halve the rate of genetic adaptation. Introduction of genes from the wild, increasing the generation interval, using captive environments close to those in the wild and achieving low mortality rates are all expected to slow genetic adaptation to captivity. Many of these procedures are already recommended for other reasons. © 1992 Wiley-Liss, Inc.

Children's and adults' reading of nonwords: effects of regularity and consistency.

Abstract: The procedures used by novice readers to assemble pronunciations for nonwords were investigated Children in Grades 1-3 read aloud consonant-vowel-consonant and longer monosyllabic nonwords By the end of Grade 1, children displayed a good grasp of grapheme-phoneme (G-P) correspondences (eg, ai, ow) Grade 2 and 3 readers increasingly used larger orthographic correspondences termed rimes (eg, -ook, -ild) However, G-P correspondences determined most responses Adults likewise used G-P rules when reading aloud nonwords and were more accurate at applying the rules The strong reliance of Grade 1 and 2 readers on G-P rules was also demonstrated by their superior oral reading of regular words along with a tendency to regularize exception words (eg, reading bull to rhyme with dull)

Differentiation of cucumber mosaic virus isolates using the polymerase chain reaction.

Abstract: A procedure based on the polymerase chain reaction (PCR) has been developed to classify cucumber mosaic cucumovirus (CMV) isolates accurately into two subgroups. Two CMV-specific primers that flank the CMV capsid protein gene were used to amplify a DNA fragment of approximately 870 bp. Restriction enzyme analysis of this fragment produces distinct restriction patterns that assign the CMV isolate into one of two subgroups. These two restriction groups correlate with the previously established CMV subgroupings; this PCR-based method may provide a simple alternative to the serological assays used for typing CMV isolates.

Modeling problems in conservation genetics using captive Drosophila populations: Improvement of reproductive fitness due to immigration of one individual into small partially inbred populations

Abstract: Immigration into small isolated captive and wild populations is recommended to alleviate inbreeding depression. The effects on reproductive fitness of introducing one immigrant into 10 small partially inbred captive populations of D. melanogaster were evaluated. The relative reproductive fitness of the immigrant populations (0.628) was approximately double that of the isolated populations (0.294) and about halfway between the isolated populations and the outbred base population (1.00). Every replicate population increased in fitness following the introduction of an immigrant. The improvements in reproductive fitness shown by the immigrant populations were not due to F1 hybrid vigor, as the experimental populations underwent three generations of random mating prior to the fitness tests. These results indicate substantial benefits can be gained by the translocation of as few as a single animal between small, partially inbred populations. © 1992 Wiley-Liss, Inc.

Generating referring expressions

Abstract: The generation of referring expressions is a key component task in many studies of natural language generation, and one that has attracted a significant amount of attention over the past 15–20 years. This article provides a formal characterization of the problem as a process of constructing a distinguishing description of an intended referent, so that a hearer is able to identify the intended referent within a context that contains other potential referents. The article outlines the historical development of algorithms that attempt to address various aspects of the problem, and points to further aspects of the problem that remain so far unexplored.

Continental cloudiness changes this century

Abstract: Surface-based observations of total cloud amount have been collected from historical records for four continents: North America, Europe, India and Australia. The records extend from 1900 to around 1985. Of the 350 individual station records investigated worldwide, 86% show an increase in total cloud amount or no change. In all four continents there is evidence of an increase in total cloud amount. This upward trend appears to be statistically significant for at least two regions: North America Australia. For North America this finding is corroborated by other recent studies.

Trace element partitioning between silicate minerals and carbonatite at 25 kbar and application to mantle metasomatism

Abstract: Experiments at 25 kbar and 1000°C, on a model trace element-enriched carbonatite-eridotite mix, produced augite + pargasite ± garnet ± dolomite coexisting with a carbonatite melt. Proton microprobe analysis of the phases showed that key trace elements (Rb, Ba, Sr, Nb, Ta, Zr, Y and REE) all partitioned strongly into the melt (with the exception of Y, Ho and Lu in garnet), verifying that carbonatite is potentially a highly effective metasomatizing agent. The data also indicate that carbonatitic metasomatism will impart higher Ba/Rb, Ba/Nb, Nb/Ta, Sr/Ta, La/Ta, and lower Zr/Y, with little change to Sr/Nb, in affected mantle.

Custom and the way of the land: past and present in vanuatu and fiji

Abstract: Tradition always encodes a relation between past and present, but that relation may be constituted as continuous or discontinuous (see Handler and Linnekin 1984). Pasts are related to presents in different ways at one extreme the past may be seen to flow effortlessly and continuously towards the present, at the other the past may be seen to be irrevocably separated from the present through a rupture, a break, which must be bridged through revival. Such differences in the construction of past-present relations are nowhere more apparent than in how the past is evoked in the politics of tradition in contemporary Pacific nations.1 Here I compare these processes in two independent states Vanuatu and Fiji. The terms kastom (custom or tradition in Bislama) and vakavanua ' the way of the land' in Fijian seem to be local variants of a pan-Pacific concept of tradition.2 What I suggest here is that these terms mark quite different articulations of past and present. Kastom is predicated on a sense of rupture and revival, vakavanua on a sense of continuity between past and present. Kastom tends more thoroughly to expunge European elements and is associated not just with a moral criticism of European ways but with more trenchant opposition towards foreigners in general and whites in particular. Vakavanua incorporates European elements Wesley an Methodism and British codifications of chiefly hierarchies and land tenure that are now seen as part of the way of the land This is in contrast to ' the way of money' , associated not only with foreigners, Europeans and Fiji-Indians, but also indigenous practitioners of the ' way of money' . In Vanuatu, Christianity and colonialism are seen much more as a rupture with a heathen past, in Fiji (at least from the viewpoint of the eastern confederacies) as flowing continuously from ancestral practices (Toren 1988). This contemporary contrast in the meanings of these terms, derives in part from a divergent experience of colonization and decolonization. In Fiji tradition was in large degree legitimated and codified by the colonial state; in Vanuatu, for the most part, it was not. In Fiji independence was attained without a struggle self-government was peacefully conferred by Britain in 1970. In Vanuatu independence was achieved after a protracted, complicated, and ultimately violent, struggle. Britain, which had long wanted to divest itself of this conj oint colony with France supported the nationalist movement from the early 1970s. But local and metropolitan French interests, American speculators and indigenous secessionists opposed independence, culminating in violent struggles on Santo and Tanna in the year of independence, 1980.3 Margaret Rodman suggests that in the colonization of Vanuatu (previously the New Hebrides/Nouvelles Hebrides) tradition was preserved in the service of metropolitan interests (1984:64). She argues, as many have done for Africa and Papua New Guinea, that preserving

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.

Upconversion versus Pr-deactivation for efficient 3 mu m laser operation in Er

Abstract: Erbium-doped BaY/sub 2/F/sub 8/ is evaluated as a potential material for a laser diode pumped 3- mu m laser. It is shown that the metastable Er/sup 4/I/sub 13/2/ level is efficiently quenched by the addition of a small amount of Pr, while still leaving the /sup 4/I/sub 11/2/ lifetime fairly long. Measurement of the /sup 4/I/sub 11/2/ and /sup 4/I/sub 13/2/ lifetimes in Er, Pr:BaY/sub 2/F/sub 8/ for 1-100% Er with 0.1-1% Pr show that the /sup 4/I/sub 13/2/ lifetime can be up to 10 times shorter than /sup 4/I/sub 11/2/. To compare this with upconversion type operation of this laser, the authors measured the upconversion coefficients alpha for 5, 10, 20, 50, and 100% Er:BaY/sub 2/F/sub 8/ and compared these to previous measurements for LiYF/sub 4/. These show a similar concentration dependence in both hosts, although BaY/sub 2/F/sub 8/ appears to have a slightly higher ratio of alpha /sub 13/2/ to alpha /sub 11/2/. Laser performance under argon and diode pumping are presented to compare upconversion operation in BaY/sub 2/F/sub 8/ and LiYF/sub 4/, and quasi-4-level operation in Er, Pr:LiYF/sub 4/ laser. >

An analysis of an ordinary differential equation model for a two-species predator-prey system with harvesting and stocking

Abstract: An analysis is presented for a model of a two-species predator-prey system where each species can be harvested or stocked. Using methods from bifurcation theory the qualitative nature of the steady-state solutions is examined. The effect of harvesting and stocking rates and the prey carrying capacity is examined in detail.

Antimicrobial properties of secretions from the metapleural glands of Myrmecia gulosa (the Australian bull ant).

Abstract: D.A. VEAL, J.E. TRIMBLE AND A.J. BEATTIE. 1992. Myrmecia gulose (Australian bull ant) produce secretions from their metapleural exocrine glands which have broad spectrum antimicrobial properties. Such secretions are probably of importance in disease control in bull ant communities. These antimicrobial secretions are stable at 100°C, resistant to proteolytic enzymes and are active over a wide pH range. Of the organisms tested only endospores of Bacillus cereus were found to be resistant. The antimicrobial agent(s) are absorbed by cells and result in cell lysis. The secretions do not interfere with any growth-related processes. These observations demonstrate that insects may be a source of novel antimicrobial agent(s).