Showing papers by "Swinburne University of Technology published in 2001"

Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant

Abstract: We present here the final results of the Hubble Space Telescope (HST) Key Project to measure the Hubble constant. We summarize our method, the results, and the uncertainties, tabulate our revised distances, and give the implications of these results for cosmology. Our results are based on a Cepheid calibration of several secondary distance methods applied over the range of about 60-400 Mpc. The analysis presented here benefits from a number of recent improvements and refinements, including (1) a larger LMC Cepheid sample to define the fiducial period-luminosity (PL) relations, (2) a more recent HST Wide Field and Planetary Camera 2 (WFPC2) photometric calibration, (3) a correction for Cepheid metallicity, and (4) a correction for incompleteness bias in the observed Cepheid PL samples. We adopt a distance modulus to the LMC (relative to which the more distant galaxies are measured) of μ0 = 18.50 ± 0.10 mag, or 50 kpc. New, revised distances are given for the 18 spiral galaxies for which Cepheids have been discovered as part of the Key Project, as well as for 13 additional galaxies with published Cepheid data. The new calibration results in a Cepheid distance to NGC 4258 in better agreement with the maser distance to this galaxy. Based on these revised Cepheid distances, we find values (in km s-1 Mpc-1) of H0 = 71 ± 2 ± 6 (systematic) (Type Ia supernovae), H0 = 71 ± 3 ± 7 (Tully-Fisher relation), H0 = 70 ± 5 ± 6 (surface brightness fluctuations), H0 = 72 ± 9 ± 7 (Type II supernovae), and H0 = 82 ± 6 ± 9 (fundamental plane). We combine these results for the different methods with three different weighting schemes, and find good agreement and consistency with H0 = 72 ± 8 km s-1 Mpc-1. Finally, we compare these results with other, global methods for measuring H0.

The HI Parkes All Sky Survey: southern observations, calibration and robust imaging

Abstract: The acquisition of HI Parkes All Shy Survey (HIPASS) southern sky data commenced at the Australia Telescope National Facility's Parkes 64-m telescope in 1997 February, and was completed in 2000 March. HIPASS is the deepest HI survey yet of the sky south of declination +2 degrees, and is sensitive to emission out to 170 h(75)(-1) Mpc. The characteristic root mean square noise in the survey images is 13.3 mJy. This paper describes the survey observations, which comprise 23 020 eight-degree scans of 9-min duration, and details the techniques used to calibrate and image the data. The processing algorithms are successfully designed to be statistically robust to the presence of interference signals, and are particular to imaging point (or nearly point) sources. Specifically, a major improvement in image quality is obtained by designing a median-gridding algorithm which uses the median estimator in place of the mean estimator.

Emotional intelligence and effective leadership

Abstract: Emotional intelligence has become increasingly popular as a measure for identifying potentially effective leaders, and as a tool for developing effective leadership skills. Despite this popularity, however, there is little empirical research that substantiates the efficacy of emotional intelligence in these areas. The aim of the present paper was to explore the relationship between emotional intelligence and effective leadership. Emotional intelligence was assessed by a modified version of the Trait Meta Mood Scale in 43 participants employed in management roles. Effective leaders were identified as those who displayed a transformational rather than transactional leadership style as measured by the multifactor leadership questionnaire. Emotional intelligence correlated with several components of transformational leadership suggesting that it may be an important component of effective leadership. In particular emotional intelligence may account for how effective leaders monitor and respond to subordinates and make them feel at work.

Spatial-temporal structures of human alpha rhythms: theory, microcurrent sources, multiscale measurements, and global binding of local networks

Abstract: A theoretical framework supporting experimental measures of dynamic properties of human EEG is proposed with emphasis on distinct alpha rhythms. Robust relationships between measured dynamics and cognitive or behavioral conditions are reviewed, and proposed physiological bases for EEG at cellular levels are considered. Classical EEG data are interpreted in the context of a conceptual framework that distinguishes between locally and globally dominated dynamic processes, as estimated with coherence or other measures of phase synchronization. Macroscopic (scalp) potentials generated by cortical current sources are described at three spatial scales, taking advantage of the columnar structure of neocortex. New EEG data demonstrate that both globally coherent and locally dominated behavior can occur within the alpha band, depending on narrow band frequency, spatial measurement scale, and brain state. Quasi-stable alpha phase structures consistent with global standing waves are observed. At the same time, alpha and theta phase locking between cortical regions during mental calculations is demonstrated, consistent with neural network formation. The brain-binding problem is considered in the context of EEG dynamic behavior that generally exhibits both of these local and global aspects. But specific experimental designs and data analysis methods may severely bias physiological interpretations in either local or global directions.

Properties of Globular Cluster Systems in Nearby Early-Type Galaxies

Abstract: We present a study of globular clusters (GCs) in 17 relatively nearby early-type galaxies, based on deep F555W and F814W images from the Wide Field Planetary Camera 2, on board the Hubble Space Telescope. A detailed analysis of color distributions, cluster sizes, and luminosity functions is performed and compared with GCs in the Milky Way. In nearly all cases, a KMM test returns a high confidence level for the hypothesis that a sum of two Gaussians provides a better fit to the observed color distribution than a single Gaussian, although histograms of the (V-I)0 distribution are not always obviously bimodal. The blue and red peak colors returned by the KMM test are both found to correlate with absolute host galaxy B-band magnitude and central velocity dispersion (at about the 2–3 σ level). Red GCs are generally smaller than blue GCs by about 20%. The size difference is seen at all radii at least out to 4' and within sub-bins in (V-I)0 color, and exists also in the Milky Way and Sombrero (M104) spiral galaxies. Fitting t5 functions to the luminosity functions of blue and red GC populations separately, we find that the V-band turnover of the blue GCs is brighter than that of the red ones by about 0.3 mag on the average, as expected if the two GC populations have similar ages and mass distributions but different metallicities. Brighter than the turnover at MV ~ -7.5, the luminosity functions (LFs) are well approximated by power laws with an exponent of about -1.75. This is similar to the LF for young star clusters, suggesting that young and old globular clusters form by the same basic mechanism. We discuss scenarios for GC formation and conclude that our data appear to favor in situ models in which all GCs in a galaxy formed after the main body of the protogalaxy had assembled into a single potential well.

A catalogue and analysis of X-ray luminosities of early-type galaxies

Abstract: ABSTRA C T We present a catalogue of X-ray luminosities for 401 early-type galaxies, of which 136 are based on newly analysed ROSAT PSPC pointed observations. The remaining luminosities are taken from the literature and converted to a common energy band, spectral model and distance scale. Using this sample we fit the LX : LB relation for early-type galaxies and find a best-fit slope for the catalogue of ,2.2. We demonstrate the influence of group-dominant galaxies on the fit and present evidence that the relation is not well modelled by a single power-law fit. We also derive estimates of the contribution to galaxy X-ray luminosities from discrete-sources and conclude that they provide Ldscr /L B . 29:5 erg s 21 L 21 B( . We compare this result with luminosities from our catalogue. Lastly, we examine the influence of environment on galaxy X-ray luminosity and on the form of the LX : LB relation. We conclude that although environment undoubtedly affects the X-ray properties of individual galaxies, particularly those in the centres of groups and clusters, it does not change the nature of whole

The chronic effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy human subjects

Abstract: Rationale: Extracts of Bacopa monniera have been reported to exert cognitive enhancing effects in animals. However, the effects on human cognition are inconclusive. Objective: The current study examined the chronic effects of an extract of B. monniera (Keenmind) on cognitive function in healthy human subjects. Methods: The study was a double-blind placebo-controlled independent-group design in which subjects were randomly allocated to one of two treatment conditions, B. monniera (300 mg) or placebo. Neuropsychological testing was conducted pre-(baseline) and at 5 and 12 weeks post drug administration. Results: B. monniera significantly improved speed of visual information processing measured by the IT task, learning rate and memory consolidation measured by the AVLT (P<0.05), and state anxiety (P<0.001) compared to placebo, with maximal effects evident after 12 weeks. Conclusions: These findings suggest that B. monniera may improve higher order cognitive processes that are critically dependent on the input of information from our environment such as learning and memory.

Is an alignment between business and information technology the appropriate paradigm to manage IT in today’s organisations?

Abstract: For many years practitioners and academics have tried to answer the question of how to strategically align the objectives of information technology (IT) and business and their delivery. A strategic alignment model (SAM) has been developed and improved over the years. This model was originally developed in the 1980s when the business environment was more stable. However, owing to major market changes SAM no longer provides companies with the much‐needed answers. The alignment concept is about a sequential development of strategies and a sequential operationalisation. Unfortunately, now that reliance on IT has increased to the level where a lack of IT agility and responsiveness can create a competitive disadvantage, the sequential model is too slow. This article promotes a notion of fusion. Today’s chief information officers are increasingly becoming company strategists who help their chief executive officer colleagues to steer companies. Business and IT strategies have to be developed simultaneously and implemented simultaneously. The conclusions of this article are based on practitioner views and experiences.

A test of general relativity from the three-dimensional orbital geometry of a binary pulsar

Abstract: Binary pulsars provide an excellent system for testing general relativity because of their intrinsic rotational stability and the precision with which radio observations can be used to determine their orbital dynamics. Measurements of the rate of orbital decay of two pulsars have been shown to be consistent with the emission of gravitational waves as predicted by general relativity, but independent verification was not possible. Such verification can in principle be obtained by determining the orbital inclination in a binary pulsar system using only classical geometrical constraints. This would permit a measurement of the expected retardation of the pulse signal arising from the general relativistic curvature of space-time in the vicinity of the companion object (the 'Shapiro delay'). Here we report high-precision radio observations of the binary millisecond pulsar PSR J0437-4715, which establish the three-dimensional structure of its orbit. We see the Shapiro delay predicted by general relativity, and we determine the mass of the neutron star and its white dwarf companion. The determination of such masses is necessary in order to understand the origin and evolution of neutron stars.

Evaluation of cognitive performance in the heat by functional brain imaging and psychometric testing.

Abstract: Military operations in tropical environments have imposed a significant challenge to the Australian Defence Forces (ADF). The hot and humid conditions are known to cause debilitating effects on soldiers deployed to northern regions of Australia, with the consequence that the effectiveness and efficiency of operations are severely compromised. While the adverse effects of thermal stress on soldiers' physiological capability are well established, this has not been confirmed for cognitive performance. A select range of psychometric tests were administered and functional brain electrical activity imaging was performed to investigate the impact of thermal stress on cognitive performance. The brain electrical activity of subjects was measured while undertaking a range of cognitive tasks. Steady State Probe Topography (SSPT), a novel brain imaging technology, was employed to monitor the changes in regional brain activity and neural processing speed of subjects under thermal stress. The psychometric test batteries included the following tasks; Rey Auditory Verbal Learning Test; Inspection Time; Digit Span test; a spatial working memory task; and the AX-continuous performance task. These tasks measure a range of cognitive processes including attention, memory, verbal learning, information processing and concentration. The functional brain imaging provided topographical information, which showed changes in electrical activity in response to thermal stress during cognitive performance. These changes in brain electrical activity and neural speed induced by thermal stress may help to identify the type of cognitive functions that are likely to be impaired under operational conditions. Results indicated that subjects experienced increasing cardiovascular strain through thermally neutral to thermally straining conditions. The results from the psychometric test battery showed some promising effects given the small sample size including deficits in working memory, in information retention and in information processing. There was also marked differences in the electrical responses of the brain when subjects were thermally strained. The Steady-State Visual Evoked Potential recordings showed an increase in amplitude and a decrease in latency, suggesting an increase in the utilisation of neural resources or effort by subjects to maintain the same level of performance as under thermally neutral conditions. The data are suggestive of the high sensitivity of brain imaging techniques with high temporal resolution to identify important decrements in cognitive performance in hostile environments.

Network models for social influence processes

Abstract: This paper generalizes thep* class of models for social network data to predict individual-level attributes from network ties. Thep* model for social networks permits the modeling of social relationships in terms of particular local relational or network configurations. In this paper we present methods for modeling attribute measures in terms of network ties, and so constructp* models for the patterns of social influence within a network. Attribute variables are included in a directed dependence graph and the Hammersley-Clifford theorem is employed to derive probability models whose parameters can be estimated using maximum pseudo-likelihood. The models are compared to existing network effects models. They can be interpreted in terms of public or private social influence phenomena within groups. The models are illustrated by an empirical example involving a training course, with trainees' reactions to aspects of the course found to relate to those of their network partners.

Culture and deception in business negotiations : A multilevel analysis

Abstract: This article investigates the relationship between culture, personality, and deception in a simulated international management negotiation at multiple levels of analysis. `Deception' was operationalized here as the propensity to lie and bribe. As predicted, at the cultural level the results from a scenario study with 1583 participants from eight cultures suggested that cultural collectivism was positively related to reported use of deception in negotiations, and to greater emotional reactions (i.e. guilt, shame, and disgust) after the use of deception. At the individual level, however, the personality variable of allocentrism (consisting of behaviors found in collectivist cultures) was negatively related to the use of deception. Theoretical implications are discussed.

TACCLE: a methodology for object-oriented software testing at the class and cluster levels

Abstract: Object-oriented programming consists of several different levels of abstraction, namely, the algorithmic level, class level, cluster level, and system level. The testing of object-oriented software at the algorithmic and system levels is similar to conventional program testing. Testing at the class and cluster levels poses new challenges. Since methods and objects may interact with one another with unforeseen combinations and invocations, they are much more complex to simulate and test than the hierarchy of functional calls in conventional programs. In this paper, we propose a methodology for object-oriented software testing at the class and cluster levels. In class-level testing, it is essential to determine whether objects produced from the execution of implemented systems would preserve the properties defined by the specification, such as behavioral equivalence and nonequivalence. Our class-level testing methodology addresses both of these aspects. For the testing of behavioral equivalence, we propose to select fundamental pairs of equivalent ground terms as test cases using a black-box technique based on algebraic specifications, and then determine by means of a white-box technique whether the objects resulting from executing such test cases are observationally equivalent. To address the testing of behavioral nonequivalence, we have identified and analyzed several nontrivial problems in the current literature. We propose to classify term equivalence into four types, thereby setting up new concepts and deriving important properties. Based on these results, we propose an approach to deal with the problems in the generation of nonequivalent ground terms as test cases. Relatively little research has contributed to cluster-level testing. In this paper, we also discuss black-box testing at the cluster level. We illustrate the feasibility of using contract, a formal specification language for the behavioral dependencies and interactions among cooperating objects of different classes in a given cluster. We propose an approach to test the interactions among different classes using every individual message-passing rule in the given Contract specification. We also present an approach to examine the interactions among composite message-passing sequences. We have developed four testing tools to support our methodology.

The Swinburne intermediate-latitude pulsar survey

Abstract: We have conducted a survey of intermediate Galactic latitudes using the 13-beam 21-cm multibeam receiver of the Parkes 64-m radio telescope. The survey covered the region enclosed by 5°<|b|<15° and −100°

Factors influencing market and entry mode selection: developing the MEMS model

Abstract: In the associated paper “Selecting overseas markets and entry modes: two decision processes or one?”, it was proposed that market selection and market entry mode selection be looked upon as two aspects of one decision process. Examines a wide spectrum of factor categories to be included in the proposed MEMS model and argues that an inclusive spectrum of analysis would make it a universally applicable model, capable of accommodating all business contexts and most relevant business practices.

A Combined Swarm Differential Evolution Algorithm for Optimization Problems

Abstract: An algorithm that is a combination of the particle swarm and differential evolution algorithms is introduced. The results of testing this on a graduated set of trial problems is given. It is shown that the combined algorithm out performs both of the component algorithms under most conditions, in both absolute and computational load weighted terms.

Selecting overseas markets and entry modes: two decision processes or one?

Abstract: Contrary to the prevalent theory approaches that treat market selection and market entry mode selection as two related but essentially separate decisions, this paper argues that these should most appropriately be looked on as two aspects of one decision process. It proposes that an exhaustive list of factors that can influence outcomes of such an integrated process be developed and argues that an inclusive spectrum of analysis would be able to accommodate all business contexts and most relevant business practice. It then presents a new market and market entry mode selection model (MEMS) which conforms to the proposed inclusive spectrum of the underlying decision process analysis.

Hypericum perforatum (St John's Wort): a non-selective reuptake inhibitor? A review of the recent advances in its pharmacology

Abstract: Hypericum possesses a unique pharmacology in that it displays the pharmacology of many classes of antidepressants and new mechanisms not typical of standard antidepressants. The most potent of all its action is the moderate to high potency for inhibition of the reuptake of monoamines, serotonin, dopamine and noradrenaline and the amino-acid neurotransmitters GABA and glutamate. Unlike standard reuptake inhibitors, hypericum exerts this reuptake inhibition non-competitively by enhancing intracellular Na+ ion concentrations. At a receptor level, chronic treatment with hypericum downregulates β1-adrenoceptor, upregulates post-synaptic 5-HT1A receptors and 5-HT2 receptors. Although the major constituent responsible for the antidepressant effect is thought to be hyperforin, other constituents such as hypericin, pseudohypericin, flavonoids and oligomeric procyanidines may also play a direct or indirect role. While reuptake inhibition may more than likely be responsible for most of the antidepressant effect, oth...

Structuration theory and information system development - frameworks for practice

Abstract: Giddens’ structuration theory (ST) offers an account of social life in terms of social practices developing and changing over time and space, which makes no attempt to directly theorize the Information Systems (IS) domain. IS researchers have long been interested in it as a way of deepening understanding; a common application is the analysis of empirical situations using Giddens’ ‘dimensions of the duality of structure’ model. Other writers, most notably Orlikowski, have used it help theorize the field. Often the mode of research employed has been the interpretative case study. However, direct attempts to influence practice (an important component of working in an applied field), perhaps through the vehicle of action research, have yet to be undertaken. There are at least three serious problems with attempting this. The first is the inaccessibility of the theory to IS researchers and practitioners. The second is the absence of specific theories of technology. The third is Giddens’ own disinterest in practical uses of his work – which leaves no obvious path to follow. This paper explores that path, in the context of information system development (ISD). Some frameworks for practice are suggested which are translated into forms of discourse that are more accessible to the IS community. In particular, we include an empirical illustration to demonstrate the potential of ISD tools based on structuration theory.

Evaluating design proposals for complex systems with work domain analysis.

Abstract: In this paper we propose a new framework for evaluating designs based on work domain analysis, the first phase of cognitive work analysis. We develop a rationale for a new approach to evaluation by describing the unique characteristics of complex systems and by showing that systems engineering techniques only partially accommodate these characteristics. We then present work domain analysis as a complementary framework for evaluation. We explain this technique by example by showing how the Australian Defence Force used work domain analysis to evaluate design proposals for a new system called Airborne Early Warning and Control. This case study also demonstrates that work domain analysis is a useful and feasible approach that complements standard techniques for evaluation and that promotes a central role for human factors professionals early in the system design and development process. Actual or potential applications of this research include the evaluation of designs for complex systems.

Developing Biodegradable Mulch Films from Starch-Based Polymers

Abstract: This paper examines the development of starch-based plastics for use as biodegradable mulch film. A variety of starch-based polymers are blended with high performance biodegradable polyester polymers in order to determine the applicability of films to be processed on a film blowing line and to perform well in mulch film field trials. The process of material formulation, film blowing processing and scale-up and performance properties are highlighted for a successful material. Insights into future developments of starch-derived biodegradable polymers are given.

High Time Resolution Observations of the Vela Pulsar

Abstract: We present high time resolution observations of single pulses from the Vela pulsar (PSR B0833-45) made with a baseband recording system at observing frequencies of 660 and 1413 MHz. We have discovered two startling features in the 1413 MHz single-pulse data. The first is the presence of giant micropulses that are confined to the leading edge of the pulse profile. One of these pulses has a peak flux density in excess of 2500 Jy, more than 40 times the integrated pulse peak. The second new result is the presence of a large-amplitude Gaussian component on the trailing edge of the pulse profile. This component can exceed the main pulse in intensity but is switched on only relatively rarely. Fluctuation spectra reveal a possible periodicity in this feature of 140 pulse periods. Unlike the rest of the profile, this component has low net polarization and emits predominantly in the orthogonal mode. This feature appears to be unique to the Vela pulsar. We have also detected microstructure in the Vela pulsar for the first time. These same features are present in the 660 MHz data. We suggest that the full width of the Vela pulse profile might be as large as 10 ms but that the conal edges emit only rarely.

The acute effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy normal subjects

Abstract: The Ayurvedic medicine Bacopa monniera (Brahmi) has been shown to exert cognitive enhancing effects in animals. The current study examined the acute effects of an extract of Bacopa monniera on cognitive function in normal healthy human subjects. The study was a double-blind, placebo-controlled independent group design in which subjects were randomly allocated to one of two treatment conditions, Bacopa monniera (300 mg) (n = 18) or placebo (n = 20). Neuropsychological testing was conducted before and 2 h after drug administration. No significant changes were found on any of the tests. The findings suggest that Bacopa monniera, at least for the dose administered, has no acute effects on cognitive functioning in normal healthy subjects. Copyright 2001 John Wiley & Sons, Ltd.