Showing papers by "Curtin University published in 1993"
TL;DR: The Sumudu transform as discussed by the authors is a new integral transform that makes its visualization easier and has many interesting properties, such as: (1) the differentiation and integration in the tdomain is equivalent to division and multiplication of the transformed function F(u) by uin the udomain.
Abstract: A new integral transform called the Sumudu transform is introduced. This transform possesses many interesting properties which make its visualization easier. Some of these properties are: (1) The differentiation and integration in the t‐domain is equivalent to division and multiplication of the transformed function F(u)by uin the u‐domain. (2) The unit‐step function in the t‐domain is transformed to unity in the u‐domain. (3) Scaling of the function f(t)in the t‐domain is equivalent to scaling of F(u) in the u‐domain by the same scale factor. (4) The limit of f(t) as ttends to zero is equal to the limit of F(u)as utends to zero. (5) For several cases, the limit of F(t)as ttends to infinity is the same as the limit of F(u)as u tends to infinity. (6) The slope of the function f(t) at t =0is the same as the slope of F(u) at u = 0. Hence uand F(u)are no longer dummies but can be treated as replicas of tand f(t).It is even possible to express uand F(u)using the units of tand f(t) respectively.
400 citations
23 Sep 1993
TL;DR: It is shown that a number of image distortions can be eliminated by the appropriate choice of camera and display systems parameters, however, there are some image distortions, which cannot be avoided due to the nature of human vision and limitations of current stereoscopic video display techniques.
Abstract: This paper discusses the origins, characteristics and effects of image distortions in stereoscopic video systems. The geometry of stereoscopic camera and display systems is presented first. This is followed by the analysis and diagrammatic presentation of various image distortions such as depth plane curvature, depth non-linearity, depth and size magnification, shearing distortion and keystone distortion. The variation of system parameters is also analyzed with the help of plots of image geometry to show their effects on image distortions. The converged (toed-in) and parallel camera configurations are compared and the amount of vertical parallax induced by lens distortion and keystone distortion are discussed. The range of acceptable vertical parallax and the convergence/accommodation limitations on depth range are also discussed. It is shown that a number of these distortions can be eliminated by the appropriate choice of camera and display systems parameters. There are some image distortions, however, which cannot be avoided due to the nature of human vision and limitations of current stereoscopic video display techniques.
398 citations
TL;DR: Although plants in small and large populations were similar in size, seed production per plant was much lower in small populations, indicating that even in large populations seed production may still not be at its maximum.
Abstract: All individuals of all known populations of Banksia goodii were assessed for seed production. Small populations produced no or only a few seeds per unit canopy area. Effects of population size on seed production per unit area and seed production per plant were present over the whole range of population sizes, indicating that even in large populations seed production may still not be at its maximum. Resource differences could not explain this disproportionate decrease in seed production with decline in population size, because there were no differences in soil properties and understorey or overstorey cover between the small and large populations. Although plants in small and large populations were similar in size, seed production per plant was much lower in small populations. This was not because plants in small populations produced fewer cones but because the fraction of these cones that was fertile was much lower. Five of the nine smallest populations (<200 m2) produced no fertile cones over the last 10 years. The number of seeds per fertile cone did not depend on population size. The results are discussed in relation to pollination biology.
391 citations
TL;DR: It appears that new MRSA strains have emerged in communities in the far north of WA and are being isolated at an increasing frequency in Perth hospitals 2000 km south.
377 citations
TL;DR: The intention here is to give an up-to-date overview of Giardia and giardiasis and provide an insight into the enormous wealth of literature on the subject, as well as highlight the most important recent developments and unresolved questions.
Abstract: It is over 10 years since Meyer and Radulescu (1979) reviewed Giardia and giardiasis in Advances in Parasitology. In their introduction, they emphasized that "despite their ubiquity and antiquity, the Giardia have, until recently, been little studied". In the intervening years, Giardia has been extensively studied. The number of papers published has increased enormously, two books on the parasite have been produced (Erlandsen and Meyer, 1984; Meyer, 1990a), and an international conference on Giardia has been organized (Wallis and Hammond, 1988). Yet it is still very difficult to keep up with developments in this productive field of research and, despite all these research efforts, several fundamental questions concerning Giardia and giardiasis remain unresolved (Table 1), particularly with respect to the relationship of Giardia and disease, and the role of zoonotic transmission. Indeed, it is only recently that we have started to appreciate the clinical significance of Giardia infections in developing countries and among disadvantaged groups. Giardia is now recognized as one of the 10 major parasites of humans, being equal to ascariasis as a cause of death in the developing world (Warren, 1989; Meyer, 1990b). In developed countries, Giardia has the distinction of being the most commonly reported human intestinal parasite (Acha and Szyfres, 1987; Thompson et al., 1990a; Schantz, 1991). Regrettably, however, the range of drugs available to treat giardiasis is limited and their efficacy leaves much to be desired. There is an urgent need for new antigiardial agents, yet this search is hampered by our lack of understanding of many fundamental aspects of Giardia biochemistry and metabolism. In addition, although the application of molecular biological techniques to research on Giardia has revealed new avenues of investigation, it has also given rise to many new questions about this intriguing organism concerning its phylogenetic position, reproductive behaviour and genetic diversity.
To review Giardia and giardiasis in detail would require at least an entire volume of Advances in Parasitology. Such treatment in depth is not warranted at this time in view of the excellent book recently edited by Meyer (1990a). Our intention here is to give an up-to-date overview of Giardia and giardiasis and provide an insight into the enormous wealth of literature on the subject, as well as highlight the most important recent developments and unresolved questions.
262 citations
TL;DR: It is shown that setting F= 1 is the more appropriate for ellipse fitting since it is less heavily curvature biased and less well suited than the A + C= 1 normalisation with respect to singularities and transformational invariance.
224 citations
TL;DR: In this paper, the Science Laboratory Environment Inventory was used to assess student cohesiveness, open-endedness, integration, rule clarity, and material environments in the laboratory class, and student outcomes encompassed two inquiry skills and four attitude measures.
Abstract: Past research on classroom environment was extended to science laboratory class settings in an investigation of associations between student outcomes and classroom environment. The sample consisted of 1,594 senior high school chemistry students in 92 classes. The Science Laboratory Environment Inventory was used to assess student cohesiveness, open-endedness, integration, rule clarity, and material environments in the laboratory class, and student outcomes encompassed two inquiry skill and four attitude measures. Simple, multiple, and canonical analyses were conducted separately for two units of analysis (student scores and class means) and separately with and without control for general ability. Past research was replicated in that the nature of the science laboratory classroom environment accounted for appreciable proportions of the variance in both cognitive and affective outcomes beyond that attributable to general ability.
219 citations
TL;DR: A simple FAS algorithm which guarantees a good (though not optimal) performance bound and executes in time O(m) is presented and achieves the same asymptotic performance bound that Berger-Shor does.
211 citations
TL;DR: The United States was a significant source of lead in the 1970s, but it has since declined considerably in relative importance, and this decline mirrors the decrease in use of leaded petrol in the United States.
Abstract: IN 1969, Murozumi et al.1 demonstrated that the concentration of lead in Greenland snow had increased by a factor of 200 since ancient times, and concluded that most of this increase was a result of the use of alkyl-leaded petrol. Partly because of these findings, the United States and other western countries limited the use of lead additives in petrol from about 1970. Recently, Boutron et al.2 showed that the lead concentration in Greenland snow had decreased by a factor of ∼7.5 over the past 20 years, and suggested that this was a result of the decline in use of leaded petrol. We present here measurements of the 206Pb/207Pb ratio of the lead contained in the samples studied by Boutron et al. Because aerosols from the atmosphere above the United States are more radiogenic than those from Eurasia, we can trace the relative contributions of these two sources in the Greenland lead over the period analysed by Boutron et al.We find that the United States was a significant source of lead in the 1970s, but it has since declined considerably in relative importance. This decline mirrors the decrease in use of leaded petrol in the United States, confirming the earlier hypothesis.
204 citations
Abstract: Analogies have long been tools of discovery in science and are often used as explanatory devices in the classroom. However, research has shown that analogies can engender alternative conceptions because some students visualize the analog in a different manner than the teacher and/or invalid analog-target transfers are left unchallenged. This case study describes one teacher’s implementation of a modified version of Clynn’s Teaching-With-Analogies (TWA) model with a Grade-10 optics class on refraction of light. The analogy likened a ray of light as it passes from air into glass to a pair of wheels that changed direction as they rolled obliquely from a hard onto a soft surface. The study indicates that a competent teacher can integrate this systematic approach into a teaching repertoire resulting in student conceptual understanding of the phenomena as expected at this level of science education. For analogies to be effective, it appears essential that the analogy be familiar to as many students as possible, that shared attributes be precisely identified by the teacher and/or students, and that the unshared attributes should be explicitly identified. The discussion concludes with recommendations for teaching and future research and discusses some limitations of this approach to analogical instruction. Since the beginning of recorded history, analogies have been used as concept-building tools for children and for adults. Metaphors, similes, analogies, and parables plus mental and physical models are common devices in spoken, acted, and written communication. Metaphors and analogies are woven into children’s stories, for example, with people represented by animals. Both fiction and nonfiction authors use analogies as descriptive tools, and they are especially ubiquitous in religious writings. Each of these literary devices are collectively considered to be analogies (Duit, 1991) because of their potential to compare one object or situation to another, and in the process, transfer either details, relational information, or both. Analogies are used because they have the power to evoke rich, almost instantaneous, mental pictures that serve to challenge the hearer to transfer knowledge from a familiar to an unfamiliar domain. Furthermore, analogies ensure that a person’s mental imagery is concrete, as in, for example, the analog of hard balls in a container representing gas molecules in a closed container. Analogies can also be tools of discovery. Johannes Kepler developed his concept of planetary motion from the workings of a clock (Bronowski, 1973) and Huygens used water wave motion to understand light phenomena (Duit, 1991). Perhaps the best described use of analogies in scientific discovery is Maxwell’s mathematical description of Faraday’s electric lines of force (Gee, 1978).
200 citations
TL;DR: Findings lend further weight to the view that prevention efforts should focus on licensed drinking environments and, in particular, the practice of continuing to serve obviously intoxicated customers.
Abstract: A household survey of 1160 Western Australian adults was used as a basis for exploring drinkers' reports about the settings in which they drank alcohol and their experiences of alcohol related harm. Of the 873 drinkers identified, 7.9% had experienced some form of acute alcohol related harm over the previous 3 months. Violent incidents were the most common of these and drink-driving offences the least. Such harm was significantly more likely among drinkers who variously drank 'heavily', were male, single, under 25 years of age and/or who drank on licensed premises. Regression analyses revealed that even when demographic characteristics of the drinkers were controlled for licensed premises were significantly more likely to be the settings used prior to harm occurring. Bar staff continuing to serve 'obviously intoxicated' customers was the most powerful predictor of harm. Premises which offered discounted drinks or permitted crowding also tended to be those where intoxication was permitted but these variables were not directly associated with an increased risk of harm. These findings lend further weight to the view that prevention efforts should focus on licensed drinking environments and, in particular, the practice of continuing to serve obviously intoxicated customers.
TL;DR: In this article, a questionnaire was sent to public service employees seeking information on their expectations regarding a proposal to increase their functional flexibility, and it was proposed that beliefs concerning the unfavorability of outcomes of the intervention would be correlated with a range of biographical, affective, and job content variables.
Abstract: Public service employees (3044) completed a questionnaire seeking information on their expectations regarding a proposal to increase their functional flexibility. It was proposed that beliefs concerning the unfavorability of outcomes of the intervention would be correlated with a range of biographical, affective, and job content variables. Multivariate analyses revealed that the scope of an employees' existing job and biographical variables (apart from age) were not generally predictive of attitudes to functional flexibility. Rather, unfavorable attitudes were weakly associated with low levels of extrinsic satisfaction, perceived reward equity, aspiration organizational commitment, and age. The implications of these findings for work and skills restructuring interventions and organizational change in general are discussed.
TL;DR: The America's Cup Defense Series was held in Fremantle, Australia, from October 1986 to February 1987 as discussed by the authors, and it was the largest such event ever held in the city.
TL;DR: The pecking order theory as discussed by the authors suggests that companies display a hierarchy of preferences with respect to funding sources, which may cause firms to refuse to issue stock, and therefore pass up valuable investment opportunities.
Abstract: This paper investigates the pecking order hypothesis, as previously suggested by Donaldson (1961) and further developed by Myers and Majluf (1984). It utilizes accounting information for a sample of 89 listed Australian industrial and commercial companies drawn from the Australian Graduate School of Management CRIF File for the period 1954–82. The pecking order theory suggests that companies display a hierarchy of preferences with respect to funding sources. This is the result of the existence of asymmetric information. Management is assumed to know more about the firm's value than potential investors. This may cause firms to refuse to issue stock, and they may, therefore, pass up valuable investment opportunities. In these circumstances, companies will prefer to fund by retentions; they will avoid new equity issues and their borrowing will be determined as a residual between desired investment and the supply of retained earnings. To avoid passing up favourable investment opportunities they will maintain ...
TL;DR: In this article, a conceptual framework is developed, delineating three key dimensions of urban social sustainability: equity, community and urbanity, and applied to the case study, showing that under the web of past and existing local and metropolitan planning policies, Perth's central area has not been able to sustain its social value for Perth's metropolitan community.
TL;DR: A new parallel hybrid energy system developed in Western Australia is described, which can cope with loads ranging from zero to approximately three times the generator capacity with excellent efficiency and can readily incorporate input from wind or photovoltaic systems.
TL;DR: U/Th (TIMS) and AMS (AMS) measurements from two coral cores from the Easter group of the Houtman Abrolhos Islands between 28°S and 29°S on the western continental margin of Australia were presented in this paper.
TL;DR: The authors investigated the mental representation from a weather map diagram by professional meteorologists and non-meteorologists using a series of drawing tasks and found that the superior recall of the meteorologists was associated with a qualitatively different approach to the weather map tasks.
TL;DR: In this paper, a mass-spectrometric dating of corals from the Abrolhos reefs, including dates obtained from drill cores, was established for the selection of suitable samples for dating and for assessing the reliability of dates.
TL;DR: In this article, a minor plutonic phase was found in the Shaw Batholith of the east Pilbara Block, Western Australia, and was dated at 3338±52 Ma, which is the same age as the Mt Edgar Batholith.
TL;DR: In this paper, the authors investigated whether cognitive misinterpretation of ambiguous interoceptive stimuli is a process specific to panic disorder or whether it is found in other anxiety disorders, and investigated the relationship of this cognitive bias to anxiety sensitivity.
Abstract: This study investigated whether cognitive misinterpretation of ambiguous interoceptive stimuli is a process specific to panic disorder or whether it is found in other anxiety disorders. It also investigated the relationship of this cognitive bias to anxiety sensitivity. Results showed it to be stronger in panic disorder than in social phobia but only when the relevant cognitive schema were specifically activated. This cognitive bias therefore also existed in social phobia, albeit to a lesser degree. Evidence of a strong relationship between misinterpretation of ambiguous interoceptive stimuli and anxiety sensitivity was lacking. The results were interpretated as supporting the view that attentional bias toward ambiguous somatic cues is specifically related to activation of relevant cognitive schema, which are particularly extensive in panic disorder.
TL;DR: Normalization using maximal voluntary isometric contractions (MVIC), irrespective of rms processing (total, mean or peak), demonstrated greater CV above the raw data for both muscle actions, which should not be at the expense of true biological variance.
TL;DR: A high inverse correlation was found between loneliness and life satisfaction in Australian subjects, with a much smaller inverse relationship observed among the Japanese, suggesting that loneliness in Japanese subjects did not emotionally translate into life dissatisfaction as it did in Australia subjects.
Abstract: We examined the relationship between loneliness and life satisfaction in 121 residents of Fukoku, Japan, and 139 residents of Melbourne, Australia, using the Satisfaction With Life Scale (Diener, Emmons, Larsen, & Griffin, 1983) and the Revised UCLA Loneliness Scale (Russell, Peplau, & Cutrona, 1980). Australian subjects reported significantly less loneliness and significantly greater life satisfaction than Japanese subjects. A high inverse correlation was found between loneliness and life satisfaction in Australian subjects, with a much smaller inverse relationship observed among the Japanese, suggesting that loneliness in Japanese subjects did not emotionally translate into life dissatisfaction as it did in Australian subjects. Instead, the experience of loneliness in Japanese individuals may remain largely independent of general life satisfaction.
TL;DR: Standard techniques for ellipse fitting such as the least squares method and the Hough Transform either make certain assumptions about the type of noise distribution, or require input parameters to work robustly over a large range of data, are described.
TL;DR: An analysis of the 100 single and multiple fallers showed that single fallers were more likely to have fallen from their bed; be discharged home from hospital; and be clinically deteriorating at the time of the fall.
Abstract: In order to compare the characteristics, preventive interventions and outcomes of single and multiple fallers, a retrospective cross-sectional study was conducted in a 680-bed acute-care hospital in Western Australia. Fifty patients falling more than once (multiple fallers) were randomly selected from all patients reported to have fallen between 1 July 1989 and 31 December 1989, and age-sex matched with 50 patients falling once in the trial period (single fallers). In total, 382 in-patients were reported to have sustained 578 falls in the 6-month trial period. Fifty-two per cent of these falls involved multiple fallers. An analysis of the 100 single and multiple fallers showed that single fallers were more likely to have fallen from their bed; be discharged home from hospital; and be clinically deteriorating at the time of the fall. Multiple fallers were more likely to be transferred to a long-term nursing facility after discharge from hospital; suffer blindness/poor vision; be sedated post fall; be ordered to be restrained following a fall; and be hospitalized for longer periods. There was also a tendency for multiple fallers to repeat the type and location of the fall on successive falls. Stepwise logistic regression showed that falling from the bed on the first fall predicted remaining a single faller. Being ordered to be restrained following the first fall and hospitalized for longer periods predicted the patient would fall repeatedly. Further analytical research incorporating an expanded number of independent variables is needed to allow confident assertions of causality. To test the effectiveness of preventive measures, a prospective longitudinal study is required.
TL;DR: In this paper, the authors present an empirical example of the systematic distortion of information and the consequent impacts in a particular planning context, and demonstrate how communicative action can illuminate the analysis of power relationships in a manner useful to planning theory and practice.
Abstract: The author presents an empirical example of the systematic distortion of information and the consequent impacts in a particular planning context. In so doing, she raises issues of professionalism, ethics, and democracy, Habermas's consideration of communicative action is of value in such analysis. She further reveals, however, that Habermassian thought tends to demonstrate a significant blindness to the role of power in such interaction. Consideration of Foucault's ideas, with regard to the manifold relations of power which characterise and constitute society, thus add an extra dimension to the work. In a strategic linking of the two the author attempts to demonstrate how communicative action can illuminate the analysis of power relationships in a manner useful to planning theory and practice. The paper concludes with a development of the Habermas-Foucault framework into a proposal for discursive democracy in an attempt to enable achievement of negotiated planning policies through a process of planning th...
TL;DR: In this article, the authors describe the evolution of an approach for using analogies in science teaching that addresses both findings from the research literature and recognises the needs of practising teachers.
Abstract: An important contribution to effective teaching and learning can be made by teachers' understanding of the central topics in each subject area and knowing how to transform their content knowledge into knowledge for teaching. One aspect of this knowledge is the use of analogies which can effectively communicate concepts to students of particular backgrounds and prerequisite knowledge. Indeed, analogies are considered to be an important component in the repertoire of effective teachers. However, research about teachers' use of analogies in science lessons provides little guidance about the optimum approaches that may be taken by preservice teachers, novice teachers, experienced teachers or reluctant analogy users. This paper describes the evolution of an approach for using analogies in science teaching that addresses both findings from the research literature and recognises the needs of practising teachers.
TL;DR: Two new corner detectors are presented, one works by using dissimilarity, along the contour direction to detect curves in the image contour, and the other estimates image curvature along the Contour direction.
Abstract: The authors present two new corner detectors. One works by using dissimilarity, along the contour direction to detect curves in the image contour, and the other estimates image curvature along the contour direction. These operators are fast, robust to noise, and require no subjective thresholding. >