Showing papers by "Curtin University published in 2001"

Ethics in qualitative research.

Abstract: Purpose: To critically examine ethical issues in qualitative research. Organizing Construct: The ethical principles of autonomy, beneficence, and justice are guides for researchers to address initial and ongoing tensions between the needs and goals of the research and the rights of participants. Methods: Research literature, ethics literature, and researcher experiences. Conclusions: Ethical principles can be used to guide the research in addressing the initial and ongoing issues arising from qualitative research in order to meet the goals of the research as well as to maintain the rights of the research participants.

Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago.

Abstract: No crustal rocks are known to have survived since the time of the intense meteor bombardment that affected Earth between its formation about 4,550 Myr ago and 4,030 Myr, the age of the oldest known components in the Acasta Gneiss of northwestern Canada. But evidence of an even older crust is provided by detrital zircons in metamorphosed sediments at Mt Narryer and Jack Hills in the Narryer Gneiss Terrane, Yilgarn Craton, Western Australia, where grains as old as approximately 4,276 Myr have been found. Here we report, based on a detailed micro-analytical study of Jack Hills zircons, the discovery of a detrital zircon with an age as old as 4,404+/-8 Myr--about 130 million years older than any previously identified on Earth. We found that the zircon is zoned with respect to rare earth elements and oxygen isotope ratios (delta18O values from 7.4 to 5.0%), indicating that it formed from an evolving magmatic source. The evolved chemistry, high delta18O value and micro-inclusions of SiO2 are consistent with growth from a granitic melt with a delta18O value from 8.5 to 9.5%. Magmatic oxygen isotope ratios in this range point toward the involvement of supracrustal material that has undergone low-temperature interaction with a liquid hydrosphere. This zircon thus represents the earliest evidence for continental crust and oceans on the Earth.

The mental health of young people in Australia: key findings from the child and adolescent component of the national survey of mental health and well‐being

Abstract: Objective: To identify the prevalence of three mental disorders (Depressive Disorder, Conduct Disorder and Attention-Deficit/Hyperactivity Disorder), the prevalence of mental health problems, the health-related quality of life of those with problems, and patterns of service utilisation of those with and without mental health problems, among 4–17-year-olds in Australia. To identify rates of health-risk behaviours among adolescents with mental health problems.Method: The mental disorders were assessed using the parent-version of the Diagnostic Interview Schedule for Children Version IV. Parents completed the Child Behaviour Checklist to identify mental health problems and standard questionnaires to assess healthrelated quality of life and service use. The Youth Risk Behaviour Questionnaire completed by adolescents was employed to identify health-risk behaviours.Results: Fourteen percent of children and adolescents were identified as having mental health problems. Many of those with mental health problems ha...

Oxygen-isotope Evidence From Ancient Zircons for Liquid Water at the Earth's Surface 4,300 Myr Ago

Abstract: Granitoid gneisses and supracrustal rocks that are 3,800–4,000 Myr old are the oldest recognized exposures of continental crust1. To obtain insight into conditions at the Earth's surface more than 4 Gyr ago requires the analysis of yet older rocks or their mineral remnants. Such an opportunity is presented by detrital zircons more than 4 Gyr old found within 3-Gyr-old quartzitic rocks in the Murchison District of Western Australia2,3. Here we report in situ U–Pb and oxygen isotope results for such zircons that place constraints on the age and composition of their sources and may therefore provide information about the nature of the Earth's early surface. We find that 3,910–4,280 Myr old zircons have oxygen isotope (δ18O) values ranging from 5.4 ± 0.6‰ to 15.0 ± 0.4‰. On the basis of these results, we postulate that the ∼4,300-Myr-old zircons formed from magmas containing a significant component of re-worked continental crust that formed in the presence of water near the Earth's surface. These data are therefore consistent with the presence of a hydrosphere interacting with the crust by 4,300 Myr ago.

Understanding Mesozoic accretion in Southeast Asia: Significance of Triassic thermotectonism (Indosinian orogeny) in Vietnam

Abstract: Results from a zircon U-Pb study of the metamorphic basement of Vietnam reveal that a large part of the continental crust was affected by a short-lived episode of ductile deformation and high-temperature metamorphism between 258 ± 6 Ma and 243 ± 5 Ma. Although coincident with final stages of North-South China collision (Qinling orogenesis), the thermotectonism in Vietnam was caused by accretion of Sibumasu to Indochina–South China. This accretion event (Indosinian orogeny) has regional significance because it contributed to the final stages of North-South China collision, an aspect not explicitly recognized in Qinling orogenic models.

Opening Iapetus: Constraints from the Laurentian margin in Newfoundland

Abstract: Late Neoproterozoic to Early Cambrian geologic, geochronologic, and paleomagnetic data from along the Iapetus margin of Laurentia may be reconciled within a multistage rift history that involved an initial separation of Laurentia from the west Gondwana cratons ca. 570 Ma, followed by rifting of a further block or blocks from Laurentia ca. 540– 535 Ma into an already open Iapetus Ocean to establish the main passive-margin sequence in the Appalachians. Paleomagnetic data suggest that Laurentia rifted from Amazonia−Rio de la Plata cratons and began its northward movement ca. 570 Ma to produce a wide Iapetus Ocean by 550 Ma. Geologic data from the Newfoundland segment of the Laurentian margin provide evidence for a rift-drift transition ca. 540–535 Ma, as constrained by the youngest rift-related magmatism at 550.5 +3/–2 Ma (U/Pb zircon) for the Skinner Cove Formation and 555 +3/–5 Ma for the Lady Slipper pluton, and a late Early Cambrian age of ca. 525–520 Ma for the oldest drift-related sedimentation. Rifting between the Laurentia and the west Gondwana cratons was probably distributed among multiple rift systems that fostered the production of a number of terranes (such as the Argentine Precordillera, Oaxacan) as well as the Iapetus Ocean. Development of Laurentian-derived Iapetan terranes during the final breakout of Laurentia from Rodinia may have been facilitated by preexisting 760–700 Ma rift weaknesses and apparently rapidly changing plate vectors during latest Neoproterozoic time.

High-Pressure Granulites (Retrograded Eclogites) from the Hengshan Complex, North China Craton: Petrology and Tectonic Implications

Abstract: Both highand medium-pressure granulites have been found as because of the absence of modal minerals. The combination of petrographic textures, mineral compositions, metamorphic reaction enclaves and boudins in tonalitic–trondhjemitic–granodioritic gneisses in the Hengshan Complex. Petrological evidence from these history, petrogenetic grids and thermobarometric data defines a nearrocks indicates four distinct metamorphic assemblages. The early isothermal decompressional clockwise P–T path for the Hengshan prograde assemblage (M1) is preserved only in the high-pressure granulites, suggesting that the Hengshan Complex underwent initial granulites and represented by quartz and rutile inclusions within crustal thickening, subsequent exhumation, and cooling and retrothe cores of garnet porphyroblasts, and omphacite pseudomorphs gression. This tectonothermal path is considered to record a major that are indicated by clinopyroxene + sodic plagioclase symplectic phase of collision between two continental blocks, which resulted in intergrowths. The peak assemblage (M2) consists of clinopyroxene the final assembly of the North China Craton at >1·8 Ga. + garnet + sodic plagioclase + quartz ± hornblende in the high-pressure granulites and orthopyroxene + clinopyroxene + garnet + plagioclase + quartz in the medium-pressure granulites.

Palaeoproterozoic assembly of the North China Craton

Abstract: The basement of the North China Craton consists of the Eastern and Western blocks, separated by the Central Zone. Both the Eastern and Western blocks are dominated by late Archaean tonalitic–trondhjemitic–granodioritic gneiss complexes interdigitated with minor supracrustal rocks metamorphosed at ~2.5 Ga, with anticlockwise P–T paths. The Central Zone is composed of reworked late Archaean components and Palaeoproterozoic juvenile crustal materials that underwent regional metamorphism at ~1.85 Ga, with clockwise P–T paths involving isothermal decompression as a result of collision between the Eastern and Western blocks, which resulted in the final assembly of the North China Craton.

Resistance training over 2 years increases bone mass in calcium-replete postmenopausal women.

Abstract: Understanding the stress/strain relationship between exercise and bone is critical to understanding the potential benefit of exercise in preventing postmenopausal bone loss. This study examined the effect of a 2-year exercise intervention and calcium supplementation (600 mg) on bone mineral density (BMD) in 126 postmenopausal women (mean age, 60 +/- 5 years). Assignment was by block randomization to one of three groups: strength (S), fitness (F), or nonexercise control (C). The two exercise groups completed three sets of the same nine exercises, three times a week. The S group increased the loading, while the F group had additional stationary bicycle riding with minimal increase in loading. Retention at 2 years was 71% (59% in the S group, 69% in the F group, and 83% in the C group), while the exercise compliance did not differ between the exercise groups (S group, 74 +/- 13%; F group, 77 +/- 14%). BMD was measured at the hip, lumbar spine, and forearm sites every 6 months using a Hologic 4500. Whole body BMD also was measured every 6 months on a Hologic 2000. There was no difference between the groups at the forearm, lumbar spine, or whole body sites. There was a significant effect of the strength program at the total (0.9 +/- 2.6%; p < 0.05) and intertrochanter hip site (1.1 +/- 3.0%; p < 0.01). There was a significant time and group interaction (p < 0.05) at the intertrochanter site by repeated measures. This study shows the effectiveness of a progressive strength program in increasing bone density at the clinically important hip site. We concluded that a strength program could be recommended as an adjunct lifestyle approach to osteoporosis treatment or used in combination with other therapies.

Do autism spectrum disorders differ from each other and from non-spectrum disorders on emotion recognition tests?

Abstract: We tested whether dimensional measures of empathic ability, theory of mind, and intelligence would differentiate autism spectrum disorders from each other and from non-spectrum disorders. Tests were administered to children with a diagnosis of Autistic Disorder (AutD; n = 20), Asperger's Disorder (AspD; n = 28), Attention Deficit/Hyperactivity Disorder (Inattentive Type) (ADHD; n = 35), Mental Retardation (Mild) (MR; n = 34), Anxiety Disorder (AnxD; n = 14), or No Psychological Disorder (NPD; n = 36). Results showed that empathic ability discriminated among groups on the autism spectrum (AutD < AspD < NPD). Because empathic ability is not independent of intelligence (AutD < AspD < NPD on intelligence; MR < ADHD < NPD on empathic ability), both dimensions are necessary to discriminate autism spectrum from non-spectrum disorders. When intelligence is covaried, empathic ability discriminated AutD, but not AspD, from other disorders (AutD < MR < ADHD < NPD = AnxD = AspD).

The Marine-Atmospheric Emitted Radiance Interferometer: A High-Accuracy, Seagoing Infrared Spectroradiometer

Abstract: The Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) is described, and some examples of the environmental variables that can be derived from its measurements and the types of research that these can support are briefly presented. The M-AERI is a robust, accurate, self-calibrating, seagoing Fourier-transform interferometric infrared spectroradiometer that is deployed on marine platforms to measure the emission spectra from the sea surface and marine atmosphere. The instrument works continuously under computer control and functions well under a very wide range of environmental conditions with a high rate of data return. Spectral measurements are made in the range of ∼3 to ∼18 μm wavelength and are calibrated using two internal, National Institute of Standards and Technology–traceable blackbody cavities. The environmental variables derived from the spectra include the surface skin temperature of the ocean, surface emissivity, near-surface air temperature, and profiles of temperature and h...

Spectral subtraction using reduced delay convolution and adaptive averaging

Abstract: In hands-free speech communication, the signal-to-noise ratio (SNR) is often poor, which makes it difficult to have a relaxed conversation. By using noise suppression, the conversation quality can be improved. This paper describes a noise suppression algorithm based on spectral subtraction. The method employs a noise and speech-dependent gain function for each frequency component. Proper measures have been taken to obtain a corresponding causal filter and also to ensure that the circular convolution originating from fast Fourier transform (FFT) filtering yields a truly linear filtering. A novel method that uses spectrum-dependent adaptive averaging to decrease the variance of the gain function is also presented. The results show a 10-dB background noise reduction for all input SNR situations tested in the range -6 to 16 dB, as well as improvement in speech quality and reduction of noise artifacts as compared with conventional spectral subtraction methods.

Paleogeographic development of the east Laurentian margin: Constraints from U-Pb dating of detrital zircons in the Newfoundland Appalachians

Abstract: An upper Neoproterozoic to Ordovician Laurentian margin sedimentary sequence in the Newfoundland Appalachians records a cycle of ocean opening and closing. U-Pb dating by ion microprobe of 341 detrital- zircon grains from six samples from this sequence yielded ages from 3592 ± 5 Ma to 572 ± 14 Ma. Three of the analyzed samples are from rift-related formations, two are from drift-related formations, and one is from a foreland-basin unit. The U-Pb data allow grouping of the zircons into four major age components: (1) Archean grains with a maximum age frequency between 2850 and 2600 Ma, (2) Paleoproterozoic grains ranging from 1950 to 1750 Ma, (3) Mesoproterozoic to early Neoproterozoic grains ranging in age between 1450 and 950 Ma, and (4) Neoproterozoic grains ranging between 760 and 570 Ma. The relative proportions of these four age components vary among samples. Mesoproterozoic detritus is present in all samples, whereas Neoproterozoic detritus is restricted to two of the three rift-related samples. Two samples— one from a rift-related formation and one from a drift-related formation, but both lying at the base of their stratigraphic column—lack Paleoproterozoic and Archean detrital zircons. Potential source regions for the detrital zircons occur within the Laurentian hinterland: zircons of Archean age correspond to the age of rock units formed during major magmatic and tectonothermal pulses in the Superior craton, zircons with Paleoproterozoic ages correspond to the ages of orogenic belts marginal to the craton (e.g., Ungava, New Quebec, and Torngat), Mesoproterozoic zircons correspond to the ages of lithologies from the Grenville orogen, and Neoproterozoic zircons are the age of rift-related igneous activity along the Laurentian margin that is now preserved within the Appalachian orogen. The youngest grains in the rift-related sedimentary rocks yield ages of 580–570 Ma and provide a maximum age for accumulation of the Newfoundland sedimentary sequence.

Brand personality and consumer self-expression: Single or dual carriageway?

Abstract: Considerable research into consumer behaviour has examined the self-expressive role of brands, but has found little support for the premise that brand personality has an influence on consumer attitudes. This paper thus proposes that consumers have a part to play in influencing how a brand personality is perceived. This is in contrast to other research and propositions, which suggest that brand personality is created by how marketers and advertisers intend to project it. The findings suggest that when a brand commands a high preference, the preferred personality of the consumers actually has an influence over its perceived brand personality — provided that the consumer has built a positive relationship with the brand and then reinforces his/her personality on to the brand. The research also illustrated that the individualist's ‘self’ has a stronger positive influence on the perceived personality of their preferred brand as compared to collectivists. The findings from this research shed light on the self-expressive use of brands, and the effects of the cultural orientation of consumers in influencing the relationship between their self and the perceived brand personality of their preferred brand. Marketers must strategically position their brands to provide a vehicle for consumers to experience emotional benefits, subsequently leading to stronger brand equity.

Why batch and user evaluations do not give the same results

Abstract: Much system-oriented evaluation of information retrieval systems has used the Cranfield approach based upon queries run against test collections in a batch mode. Some researchers have questioned whether this approach can be applied to the real world, but little data exists for or against that assertion. We have studied this question in the context of the TREC Interactive Track. Previous results demonstrated that improved performance as measured by relevance-based metrics in batch studies did not correspond with the results of outcomes based on real user searching tasks. The experiments in this paper analyzed those results to determine why this occurred. Our assessment showed that while the queries entered by real users into systems yielding better results in batch studies gave comparable gains in ranking of relevant documents for those users, they did not translate into better performance on specific tasks. This was most likely due to users being able to adequately find and utilize relevant documents ranked further down the output list.

Science Teaching and Learning in Australian Schools: Results of a National Study

Abstract: This paper reports on a large scale study that investigated the quality of teaching and learning in science in Australian schools Its purposes were first, to describe ideal practice in the teaching and learning of school science; second, to describe the nature of teaching and learning of science in Australian schools; and third, to make recommendations to move the actual closer to the ideal Fundamental to the research was the belief that scientific literacy is a high priority for all citizens, helping them to be interested in, and understand the world around them, to be sceptical and questioning of claims made by others about scientific matters, to be able to identify questions, investigate and draw evidence-based conclusions, and to make informed decisions about the environment and their own health and well-being Based on national and international reports and research literature, and substantial new data collected from teachers, students and other Australian stakeholders in science education, the ideal picture was described in nine themes relating to the curriculum, teaching and learning strategies, professionalism of teachers and their career path, resources and facilities, and the value of science and science education to the community The actual picture was one of great variability, but overall, it was bleak The actual curriculum implemented in most schools differs from the intended curriculum, which is focused on developing scientific literacy and helping students progress towards achieving the stated outcomes Science in primary schools is generally student-centred and activity-based When students move to high school, many experience disappointment, because the science they are taught is neither relevant nor engaging and does not connect with their interests and experiences Disenchantment with science is reflected in the decline in science subjects taken by students in upper secondary school Many science teachers feel undervalued, under-resourced and overloaded with non-teaching duties The recommendations developed to improve the status and quality of science education were underlain by five fundamental premises: the purpose of science education is to develop scientific literacy, the focus for change is closing the gap between the actual and ideal, teachers are the key to change, change takes time and resources, and collaboration is essential for quality science education Preliminary recommendations were prepared and scrutinised by members of a government-appointed Steering Committee for the project, critical friends, and teacher focus groups Recommendations concerning awareness, teachers, resources, assessment, and national collaboration were developed incorporating feedback from the process described, each including a range of suggested actions for implementation that were feasible in the Australian context If Commonwealth and State governments choose to act on these recommendations, the gap between the actual picture of science teaching and learning in Australia and the ideal will be significantly reduced

Analysis of multicarrier PWM methods for a single-phase five level inverter

Abstract: This paper investigates and analyses different multicarrier PWM methods for a single phase five level cascaded inverter. Carrier disposition methods, phase shifted and a hybrid method are discussed with respect to resulting switching frequencies, complexity of implementation, spectrum of the output waveform, and the use of inverter state redundancies to perform additional application specific control tasks, such as power flow control from each DC source. A concept of separating the waveshaping function from the switch selection is explored and selected experimental results are presented.

Zero‐inflated Poisson regression with random effects to evaluate an occupational injury prevention programme

Abstract: This study presents a zero-inflated Poisson regression model with random effects to evaluate a manual handling injury prevention strategy trialled within the cleaning services department of a 600 bed public hospital between 1992 and 1995. The hospital had been experiencing high annual rates of compensable injuries of which over 60 per cent were attributed to manual handling. The strategy employed Workplace Risk Assessment Teams (WRATS) that utilized a workplace risk identification, assessment and control approach to manual handling injury hazard reduction. The WRATS programme was an intervention trial, covering the 1988-1995 financial years. In the course of compiling injury counts, it was found that the data exhibited an excess of zeros, in the context that the majority of cleaners did not suffer any injuries. This phenomenon is typical of data encountered in the occupational health discipline. We propose a zero-inflated random effects Poisson regression model to analyse such longitudinal count data with extra zeros. The WRATS intervention and other concomitant information on individual cleaners are considered as fixed effects in the model. The results provide statistical evidence showing the value of the WRATS programme. In addition, the methods can be applied to assess the effectiveness of intervention trials on populations at high risk of manual handling injury or indeed of injury from other hazards.

A battery management system for stand-alone photovoltaic energy systems

Abstract: It is estimated that about 80% of all photovoltaic (PV) modules are used in stand-alone applications. Continuous power is obtained from PV systems by using a storage buffer, typically in the form of a lead acid battery. Batteries used in PV applications have different performance characteristics compared with batteries used in more traditional applications. In PV applications, lead acid batteries do not reach the cycle of lead acid batteries used in other applications such as uninterruptible power supplies or electric vehicles. The shortened battery life contributes significantly to the costs of a PV system. In some PV systems the battery accounts for more than 40% of the life cycle costs. An increase in the lifetime of the battery will result in improved reliability of the system and a significant reduction in operating costs. The life of a lead acid battery can be extended by avoiding critical operating conditions such as overcharge and deep discharge. This paper presents a battery management system for such applications.