Showing papers by "Griffith University published in 1989"
TL;DR: This paper investigates the properties of a Hermitian phase operator which follows directly and uniquely from the form of the phase states in this space and finds them to be well behaved.
Abstract: The usual mathematical model of the single-mode electromagnetic field is the harmonic oscillator with an infinite-dimensional state space, which unfortunately cannot accommodate the existence of a Hermitian phase operator. Recently we indicated that this difficulty may be circumvented by using an alternative, and physically indistinguishable, mathematical model of the single-mode field involving a finite but arbitrarily large state space, the dimension of which is allowed to tend to infinity after physically measurable results, such as expectation values, are calculated. In this paper we investigate the properties of a Hermitian phase operator which follows directly and uniquely from the form of the phase states in this space and find them to be well behaved. The phase-number commutator is not subject to the difficulties inherent in Dirac's original commutator, but still preserves the commutator--Poisson-bracket correspondence for physical field states. In the quantum regime of small field strengths, the phase operator predicts phase properties substantially different from those obtained using the conventional Susskind-Glogower operators. In particular, our results are consistent with the vacuum being a state of random phase and the phases of two vacuum fields being uncorrelated. For higher-intensity fields, the quantum phase properties agree with those previously obtained by phenomenological and semiclassical approaches, where such approximations are valid. We illustrate the properties of the phase with a discussion of partial phase states. The Hermitian phase operator also allows us to construct a unitary number-shift operator and phase-moment generating functions. We conclude that the alternative mathematical description of the single-mode field presented here provides a valid, and potentially useful, quantum-mechanical approach for calculating the phase properties of the electromagnetic field.
718 citations
TL;DR: In this paper, it was shown that the number-phase commutator differs from that originally postulated by Dirac and this difference allows consistent use of the commutators for inherently quantum states.
Abstract: It has long been believed that no Hermitian optical phase operator exists. However, such an operator can be constructed from the phase states. We demonstrate that its properties are precisely in accord with the results of semiclassical and phenomenological approaches when such approximate methods are valid. We find that the number-phase commutator differs from that originally postulated by Dirac. This difference allows the consistent use of the commutator for inherently quantum states. It also leads to the correct periodic phase behaviour of the Poisson bracket in the classical regime.
447 citations
TL;DR: In this article, the authors examined corporate social disclosure practices in Malaysian and Singapore companies and found that a positive correlation existed between corporate size and CSD (Trotman, 1979), as well as the relationship between CSD and industry groupings (Guthrie, 1983).
Abstract: Most studies on corporate social disclosure (CSD) have focused on the industrialised countries of Europe, United States and Australia (for example, Dierkes & Preston, 1977; Beresford & Cowen, 1979; Brockhoff, 1979). Even international comparative studies of CSD concentrated on analyses of the similarities and differences of CSD practices in these countries (for example, Schoenfeld, 1978; Ernst & Ernst, 1979; Guthrie & Parker, 1988). There is however, a paucity of CSD literature on practices in the developing countries. The purpose of this paper is to address this imbalance by examining CSD practices in Malaysian and Singapore companies. Within the CSD literature on developed countries, there is evidence that a positive correlation existed between corporate size and CSD (Trotman, 1979). More recently additional evidence was found concerning the themes, methods, extent of CSD in the annual reports, as well as the relationship between CSD and industry groupings (Guthrie, 1983). In the few studies available on developing countries, Teoh & Thong (1984) and Singh & Ahuja (1983) f ound broadly similar evidence. The data reported in this paper is intended to be purely descriptive. The paper explored the CSD characteristics mentioned above and assessed the
286 citations
TL;DR: The availability of metabolic energy provides a general measure of the environmental stress that can be tolerated by organisms, leading to the hypothesis that increased tolerance to a range of environmental stresses will be associated with a reduction in metabolic rate in Drosophila and many other organisms.
Abstract: The availability of metabolic energy provides a general measure of the environmental stress that can be tolerated by organisms, leading to the hypothesis that increased tolerance to a range of environmental stresses will be associated with a reduction in metabolic rate in Drosophila and many other organisms. This hypothesis makes three predictions about genetic variation for stress tolerance: (1) increased stress tolerance will tend to be associated with decreased metabolic rate; (2) genetic correlations between tolerance of different environmental stresses will tend to be positive; (3) stress tolerance and life-history traits will tend to be genetically correlated; in Drosophila correlations with life-history traits other than longevity will tend to be negative.
These predictions were tested by artificially selecting for increased desiccation tolerance in Drosophila melanogaster, using an 85% mortality level. The response to selection was rapid and the mean realized heritability was c. 0.65. The selection response was associated with a decreased rate of water loss, reduced activity and a decrease in metabolic rate in agreement with prediction (1). Selection did not alter body size. Selected lines were relatively more tolerant of starvation and a toxic concentration of ethanol in agreement with prediction (2), and had lower fecundities in agreement with prediction (3).
214 citations
TL;DR: It is suggested that organisational, behavioural, and physiological factors moderate the impact of night work on psychological well-being, and personality factors do not.
Abstract: This study tested the efficacy of selected personality, behavioural, and social/organizational variables as predictors of adaptation to night work. Sixty female student nurses were studied during their first IS months of shiftwork. Twenty-two worked on rotating day and afternoon shifts throughout, while the remaining 38 began regular night shifts after six months. Psychological symptoms were measured at baseline (Stage 1), six months (Stage 2) and 15 months (Stage 3). Repeated measures analysis of variance revealed a significant shift group x symptoms interaction (p < 0·05) between Stages 2 and 3. Only the night workers displayed a significant increase (Tukey HSD: p < 0·01) in symptoms between Stages 1 and 3. Multiple regression analysis revealed that neuroticism and perceived work/nonwork conflict predicted symptoms at Stage 2. Night work, social support from supervisors, and morningness were predictors at Stage 3. These results suggest that organisational, behavioural, and physiological factors moderate...
177 citations
TL;DR: In this article, two major dust transport pathways are described, based upon paleo-dune patterns and present day dust storms and related processes, which have been fed by alluvium deposited in internally-draining river basins.
162 citations
TL;DR: The authors examined the effect that sugar and amino acids in the adult diet of Jalmenus evagoras can have on female feeding behavior, somatic maintenance, longevity, fecundity and egg weight.
Abstract: This study examines the effect that sugars and amino acids in the adult diet of Jalmenus evagoras can have on female feeding behaviour, somatic maintenance, longevity, fecundity and egg weight. The presence of sugars in their adult food stimulated butterflies of this species to feed, and they appeared to compensate for low (1% wt/wt) sugar diets by feeding for longer periods. Butterflies were also more likely to feed on diets containing amino acids than on water controls. The availability of sugar allowed females to maintain or even increase their body weight and fat body size, but amino acids had no effect on these variables. Individuals on the medium (25% wt/wt) sugar diet attained the greatest longevity. Female fecundity was increased as much as threefold by the availability of sugar. However, amino acids in the diet had no effect on either longevity or fecundity. Egg weight was not affected by the concentration of sugars or amino acids in the adult diet, but was correlated with the weight of the female butterfly. These results demonstrate that the availability of carbohydrates in the adult diet could play an important role in the population dynamics of this species. However, the presence of amino acids had little effect on most of the variables measured, nor was there any interaction effect between sugars and amino acids.
112 citations
TL;DR: This paper examined the factors which influence high calibre students in their choice of a professional discipline of study and found that accountancy students appeared most concerned with job satisfaction, earnings potential, availability of employment, aptitude for subject and years of formal education, and to have a different and more distinctive profile than that of other students.
Abstract:
This paper examines the factors which influence high calibre students in their choice of a professional discipline of study. Using a questionnaire approach students were requested to determine the relative importance of eleven factors in their choice of discipline of study. Results showed that accountancy students appeared most concerned with job satisfaction, earnings potential, availability of employment, aptitude for subject and years of formal education, and to have a different, and more distinctive, profile than that of other students. These results may have important implications for recruitment into the profession.
105 citations
TL;DR: In this paper, the phase probability density of the unitary and hermitian phase operators was derived for the case of the squeezed vacuum. But the results differ markedly from previous calculations involving the Susskind and Glogower operators.
99 citations
TL;DR: In this article, the effects of trampling on the coral communities of the outer reef flat and reef crest were investigated at Heron Island at the southern end of the Great Barrier Reef.
Abstract: The effects of trampling on the coral communities of the outer reef flat and reef crest were investigated at Heron Island at the southern end of the Great Barrier Reef. Eighteen months of trampling at various intensities increased the percentage cover of unoccupied substrate and the cover of mobile rubble. The morphology of the coral was the most important feature relating to trampling resistance. Branching corals were reduced on the outer reef flat, and most broken branches were recorded in the initial phases of the experiment. The reef crest was much more resistant.
85 citations
TL;DR: In this paper, a novel method for determining the concentration and distribution across sites of substitutional impurities in crystals is described, as an alternative to the usual ratio method of atom location by the channelling enhanced microanalysis (ALCHEMI) technique.
Abstract: A novel method for determining the concentration and distribution across sites of substitutional impurities in crystals is described, as an alternative to the usual ratio method of atom location by the channelling enhanced microanalysis (ALCHEMI) technique. The integrated X-ray counts for emission from impurity and host atom species under strong zone-axis diffraction conditions are analysed using standard multivariate statistical procedures. This enables both the total concentration and the fractional site occupancy of the impurity species to be determined, together with quantitative estimates of the uncertainties in these quantities. This method of analysis is illustrated through the determination of the site occupancy of Fe in a Cr2MnO4 spinel. Advantages of this technique include reduced sensitivity both to the effects of delocalization and to the effects of experimental errors compared with standard ALCHEMI analyses.
TL;DR: There is a non-linear relationship of increasing dust storms with aridity, peaking at 200 mm and decreasing for lower rainfalls as discussed by the authors, and both the spatial and temporal occurrences of dust storms are strongly influenced by drought.
TL;DR: In this article, the authors show that hydrogen sulphide-producing lactobacillus sake L13 produced hydrogen sulfide during growth at 0°C on vacuum-packaged beef of normal pH (5·6-5·8) when the packaging films used had oxygen permeabilities as high as 200 ml/m2/24 h/atm (measured at 25°C and 98% relative humidity).
Abstract: Lactobacillus sake L13 produced hydrogen sulphide during growth at 0°C on vacuum-packaged beef of normal pH (5·6–5·8) when the packaging films used had oxygen permeabilities as high as 200 ml/m2/24 h/atm (measured at 25°C and 98% relative humidity. No hydrogen sulphide was detected when the film permeability was 300 ml/m2/24 h/atm. Sulphmyoglobin was formed whenever hydrogen sulphide was present except when the film permeability was very low (1 ml of oxygen/m2/24 h/atm). Lactobacillus sake L13 also produced hydrogen sulphide when grown on beef under anaerobic conditions at 5°C. When meat pH was high (6·4–6·6) hydrogen sulphide was first detected after incubation for 9 d. When 250 μg of glucose was added to each g of high pH meat, or when meat pH was normal (5·6–5·8), hydrogen sulphide was first detected after incubation for 18 d. The spoilage of beef by hydrogen sulphide-producing lactobacilli is more rapid when the pH of the meat is high because high-pH meat contains less glucose. Sulphmyoglobin formation and greening can be prevented by the use of packaging films of very low oxygen permeability.
Journal Article•
TL;DR: An environment-oriented approach to salt marsh management for mosquito control, runnelling, is described and compared with other forms of habitat modification such as ditching and Open Marsh Water Management (OMWM).
Abstract: Traditional methods of managing salt marsh mosquitoes focus primarily on maximizing the reduction of mosquito populations, with minimizing environmental impact as a secondary consideration. An environment-oriented approach to salt marsh management for mosquito control, runnelling, is described and compared with other forms of habitat modification such as ditching and Open Marsh Water Management (OMWM). Runnelling alters the salt marsh as little as possible while causing significant reductions in mosquito numbers. The effect of runnelling on the environment was monitored via the following variables: water table level, substrate characteristics (moisture, salinity and pH), vegetation (height and density of each Sporobolus virginicus) and the numbers of mosquito larvae. Runnelling had a statistically significant effect on only two of the seven variables. These were the height of Sporobolus, which increased near runnels, and the number of mosquito larvae, which decreased. The main difference between ditching, OMWM and runnelling lies in the magnitude of the habitat modification. Ditching involves the greatest alteration to the marsh, and runnelling the least. Consequently, runnelling has a smaller effect on the estuarine environment as a whole than does either ditching or OMWM.
TL;DR: The amino acid sequences of several actin regulatory proteins have recently been determined and it is shown that these proteins function by mimicking actin-actin interaction sites.
TL;DR: A focus on ‘modern’ industrialized societies obscures both the great antiquity of the state and the powerful selective pressures that have led to the dominance of interstate competition, especially warfare as discussed by the authors.
Abstract: A focus on ‘modern’ industrialized societies obscures both the great antiquity of the state and the powerful selective pressures that have led to the dominance of interstate competition, especially warfare. In pursuit of power, elites encouraged population growth and intensified the exploitation of the natural resource base, with progressively more severe ecological impacts. Modern technology has vastly amplified the problem. Though it makes possible sophisticated environmental management, that has been neglected for the demands of the military–industrial system. These ill-effects are reinforced by ignorance of ecology and inadequacy of traditional political thought. A major adaptive challenge faces modern states: to use their knowledge and resources for more humane, environmentally sensitive management and perhaps achieve a novel kind of steady state, or to renew emphasis on short-term competitive considerations.
TL;DR: The results indicate that the kinetic characteristics of the membrane-bound ecto-5'-nucleotidase are consistent with an important role in the formation of extracellular adenosine, whereas the other 5'-n nucleotidases are inconsistent with roles inAdenosine formation under the conditions of the present study.
Abstract: Changes in 5'-nucleotidase activity were calculated on the basis of alterations in ATP, ADP, phosphocreatine, Pi, Mg2+, IMP and AMP, determined by using 31P n.m.r. spectroscopy and h.p.l.c., during isoprenaline infusion, graded hypoxia and graded underperfusion in isolated rat heart. Calculated activity changes were compared with the total efflux of purines (adenosine + inosine + hypoxanthine) in order to assess the involvement of various 5'-nucleotidases in formation of adenosine. Purine efflux exhibited an exponential relation with cytosolic [AMP] during isoprenaline infusion and hypoxia (r = 0.92 and 0.95 respectively), supporting allosteric activation of 5'-nucleotidase under these conditions. Purine efflux displayed a linear relation with cytosolic [AMP] during graded ischaemia (r = 0.96), supporting substrate regulation in the ischaemic heart. The calculated activities of membrane-bound ecto-5'-nucleotidase were similar to the observed relations between purine efflux and cytosolic [AMP] in all hearts. The calculated activities of the ATP-activated cytosolic and lysosomal enzymes and of the ATP-inhibited cytosolic 5'-nucleotidase could not explain the observed release of purines under the conditions examined. These results indicate that the kinetic characteristics of the membrane-bound ecto-enzyme are consistent with an important role in the formation of extracellular adenosine, whereas the characteristics of the other 5'-nucleotidases are inconsistent with roles in adenosine formation under the conditions of the present study.
TL;DR: The authors showed that Johnson's results can be improved by using a different demand equation for the alcoholic beverages group and also considered the analysis of treating advertising as a stock rather than a flow, which showed that advertising on beer, wine and spirits depreciates in consumers' minds fully within a year.
Abstract: Johnson (1985) presents a system-wide analysis on the effects of advertising on the demand for beer, wine and spirits in the UK. However, his results are not consistent with other studies in the area. This paper shows that his results can be improved by using a different demand equation for the alcoholic beverages group. Furthermore, this paper also considers the analysis of treating advertising as a stock rather than a flow. This analysis reveals that advertising on beer, wine and spirits depreciates in consumers' minds fully within a year.
TL;DR: Computers in the Human Context provides a challenging reappraisal of the information technology revolution, showing that many companies and organizations are using computers ineffectively, wasting much of the over $300 billion that is being spent each year on computer and communications hardware and software.
Abstract: From the Publisher:
Our technical knowledge about computers is not matched by a knowledge of their social consequences and possibilities. Computers in the Human Context provides a challenging reappraisal of the information technology revolution. It shows that many companies and organizations are using computers ineffectively, wasting much of the over $300 billion that is being spent each year on computer and communications hardware and software.
It is clear from the studies reported here that the economic payoff from the information technology revolution has been slow in coming. The euphoria that greeted the arrival of the microchip in the 1970s has been displaced by a more critical assessment of the social benefits of computerization.
Several contributors debunk popular notions such as artificial intelligence, the electronic cottage, teledemocracy, and postindustrial society. Others describe the growing ethical problems of the information technology revolution, including computer crime, workplace surveillance, intellectual property rights, and government control of information.
Together these contributions are a major statement of the increasing awareness that what decides the success or failure of computer systems in all contexts in the human factor.
Tom Forester, Lecturer and Director of the Foundation Programme, in the School of Computing and Information at Griffith University in Queensland, Australia, is the author or editor of five books on technology and society.
TL;DR: In this article, experiments were conducted under controlled temperature and moisture conditions to further study wheat straw decomposition during the first 35 days after its addition to soil, and two methods of applying straw (incorporation, surface retention) were compared.
Abstract: Following field studies of wheat straw decomposition under different management techniques, experiments were conducted under controlled temperature and moisture conditions to further study straw decomposition during the first 35 days after its addition to soil. Two methods of applying straw (incorporation, surface retention) were compared. Also decomposition was studied in the presence or absence of the water-soluble fraction of straw. The 14C-labelled and unlabelled components of evolved CO2-C, soil soluble and total C, retrieved straw and biomass C were measured for up to 35 days. Incorporating the straw hastened its decomposition only within the first 15 days, thereafter the decomposition rate was similar to that of straw retained on the soil surface. Decomposition rates generally peaked between 4 and 15 days. Applying the soluble fraction of straw to soil after its extraction from straw showed it to be an important substrate during the early stages of straw decomposition. This C source, however, is quickly exhausted. Continued straw decomposition is largely dependent on mineralization of the initially insoluble pool of straw C.
TL;DR: It is concluded that the cellular site of iron deposition as well as the hepatic iron concentration is important in determining iron-induced liver injury and iron deposited in the parenchymal cells of the liver may lead to an altered free radical antioxidant protective system, resulting in lipid peroxidation in these cells at a similar level of iron loading.
TL;DR: Observations suggest that ansA and ORF1 constitute an operon, and a palindromic sequence exists in the 3' region of OrF1 which may function as a bidirectional transcription terminator both for the ansA-ORF1 operon and a second, convergent, ORF.
TL;DR: In this article, the authors examine the question of strategic structural choice between centralized and formalized means of control and propose an alternative approach in conceiving and operationalizing the problem of choice, using the "Indifference Curves" postulate as put forward in neo-classical economic theory.
Abstract: Drawing on previous research on patterns of organization structures, this paper examines the question of strategic structural choice between centralized and formalized means of control. An alternative approach in conceiving and operationalizing the problem of choice is suggested. This uses the 'Indifference Curves' postulate as put forward in neo-classical economic theory. An operational model featuring 'trade-offs' between centralized and formalized control is proposed.The conclusions are that the framework based on the notion of 'indifference' provides reasonable theoretical strength in portraying and explaining trade-offs in structural choices. Theoretically infinite trade-offs in choices between means of control find limits in the purposive search for equilibrium (optimum choice), for example in matching the amount/type of structuring with constraints such as size.
TL;DR: Examination of the genotypes of parents and offspring indicated that individuals from bisexual populations reproduced sexually whereas those from unisexual populations demonstrated ameiotic parthenogenesis.
Abstract: Individuals from six bisexual and six unisexual populations of Potamopyrgus antipodarum were examined electrophoretically, in order to determine their mode of reproduction. Extensive genetic variation within populations was revealed at four of seven presumptive loci, with no differences between unisexual and bisexual populations being observed. In addition, extensive heterogeneity was observed for both reproduction types. Examination of the genotypes of parents and offspring indicated that individuals from bisexual populations reproduced sexually whereas those from unisexual populations demonstrated ameiotic parthenogenesis.
TL;DR: The first homoleptic main group diazadiene complex was described in this article, which is a unique example of gallium(II) in which one of the diazadine ligands has been doubly reduced.
Abstract: Cocondensation of gallium vapour with 1,4-di-t-butyl-1,4-diazabuta-1,3-diene (Butdab) affords the title compound as the first example of a homoleptic main group diazadiene complex; X-ray crystallography shows the molecule to possess distorted tetrahedral geometry, and together with e.s.r. and magnetic data suggests it to be a unique example of gallium(II) in which one of the diazadine ligands has been doubly reduced.
TL;DR: In this article, the phase states of optical amplifiers and attenuators were used to analyze phase evolution in optical attenuator and optical amplifier, and the resulting diffusion of the phase probability distribution was compared with that obtained in conventional Fokker-Planck treatments.
TL;DR: A total of 72 polycyclic aromatic hydrocarbons were identified in the samples with fluoranthene and pyrene occurring in the highest concentrations, up to 2·34±1·73 and 2·26± 1·72 μg g −1, respectively, in sediments as discussed by the authors.
Abstract: Twenty-three composite sediment and eight water particulate and water filtrate samples were collected along the Brisbane River estuary from the mouth to 40 km upstream. The polycyclic aromatic hydrocarbons in the samples were isolated by solvent extraction and column chromatography then identified and quantified by gas chromatography and gas chromatography coupled with mass spectrometry. A total of 72 polycyclic aromatic hydrocarbons were identified in the samples with fluoranthene and pyrene occurring in the highest concentrations, up to 2·34±1·73 and 2·26±1·72 μg g −1 , respectively, in sediments. Total polycyclic aromatic hydrocarbon distribution patterns showed that the most urbanized zone of the study area had the highest total polycyclic aromatic hydrocarbon concentration (16·1 μg g −1 ). Concentrations were relatively lower both upstream and downstream from this area. Upstream there were no significant inputs but downstream various industries constituted major point sources; however, the concentrations were comparatively low, probably due to flushing by tides and currents. Distribution of polycyclic aromatic hydrocarbons were not significantly influenced by the organic carbon content and particle size composition of sediments. Polycyclic aromatic hydrocarbon assemblages observed in the samples were relatively rich in hydrocarbons having pyrolytic origins. However, the presence of petroleum derived components was also indicated by several characteristic component composition ratios.
TL;DR: In this article, the bioaccumulation of liphophilic compounds from sediments by polychaetes has been considered as two partition processes at equilibrium, the first partition was considered to be between sediment and interstitial water and the second partition between interstitial waters and the polychaete.
TL;DR: In this paper, the Priestley-Taylor model is used to predict the medium to long-term evapotranspiration from a basin in a small wet forested region.
Abstract: The hydrology of a small wet forested region is studied. Catchment discharge, solar radiation, air temperature, humidity, precipitation, soil moisture, and the water elevation in a swamp were monitored for several months in 1973 and 1975. These data are used to investigate various aspects of the catchment's hydrology and in particular to study the catchment's evapotranspirational requirements. The actual evapotranspiration loss is calculated from a water budget approach. The Priestley-Taylor model is used to predict the medium to long-term evapotranspiration from the basin. The predictions based on the model are in very good agreement with the actual evapotranspirational demand. Evapotranspiration is found to play a significant role in the catchment's water balance.
TL;DR: A theoretical derivation suggests that the Biomagnification Factor (body concentration/food concentration) will be independent of, or weakly dependent, on the octanol to water partition coefficient and will be unity for all compounds when expressed on a lipid weight basis.