693 resultados para critical frequency
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PURPOSE: To explore the effects of glaucoma and aging on low-spatial-frequency contrast sensitivity by using tests designed to assess performance of either the magnocellular (M) or parvocellular (P) visual pathways. METHODS: Contrast sensitivity was measured for spatial frequencies of 0.25 to 2 cyc/deg by using a published steady- and pulsed-pedestal approach. Sixteen patients with glaucoma and 16 approximately age-matched control subjects participated. Patients with glaucoma were tested foveally and at two midperipheral locations: (1) an area of early visual field loss, and (2) an area of normal visual field. Control subjects were assessed in matched locations. An additional group of 12 younger control subjects (aged 20-35 years) were also tested. RESULTS: Older control subjects demonstrated reduced sensitivity relative to the younger group for the steady (presumed M)- and pulsed (presumed P)-pedestal conditions. Sensitivity was reduced foveally and in the midperiphery across the spatial frequency range. In the area of early visual field loss, the glaucoma group demonstrated further sensitivity reduction relative to older control subjects across the spatial frequency range for both the steady- and pulsed-pedestal tasks. Sensitivity was also reduced in the midperipheral location of "normal" visual field for the pulsed condition. CONCLUSIONS: Normal aging results in a reduction of contrast sensitivity for the low-spatial-frequency-sensitive components of both the M and P pathways. Glaucoma results in a further reduction of sensitivity that is not selective for M or P function. The low-spatial-frequency-sensitive channels of both pathways, which are presumably mediated by cells with larger receptive fields, are approximately equivalently impaired in early glaucoma.
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CFO and I/Q mismatch could cause significant performance degradation to OFDM systems. Their estimation and compensation are generally difficult as they are entangled in the received signal. In this paper, we propose some low-complexity estimation and compensation schemes in the receiver, which are robust to various CFO and I/Q mismatch values although the performance is slightly degraded for very small CFO. These schemes consist of three steps: forming a cosine estimator free of I/Q mismatch interference, estimating I/Q mismatch using the estimated cosine value, and forming a sine estimator using samples after I/Q mismatch compensation. These estimators are based on the perception that an estimate of cosine serves much better as the basis for I/Q mismatch estimation than the estimate of CFO derived from the cosine function. Simulation results show that the proposed schemes can improve system performance significantly, and they are robust to CFO and I/Q mismatch.
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The service-orientation paradigm has not only become prevalent in the software systems domain in recent years, but is also increasingly applied on the business level to restructure organisational capabilities. In this paper, we present the results of an extensive literature review of 30 approaches related to service identification and analysis for both domains. Based on the consolidation of a superset of comparison criteria for service-oriented methodologies found in related literature, we compare and evaluate the different characteristics of service engineering methods with a focus on service analysis. Although a close business and IT alignment is regarded as one of the core beneficial promises of service-orientation, our analysis suggests that there is a lack of unified, comprehensive methodology for service identification and analysis integrating and addressing both domains. Thus, we discuss how our results can inform directions for future research in this area.
Negotiating multiple identities between school and the outside world : A critical discourse analysis
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This article examines interview talk of three students in an Australian high school to show how they negotiate their young adult identities between school and the outside world. It draws on Bakhtin’s concepts of dialogism and heteroglossia to argue that identities are linguistically and corporeally constituted. A critical discourse analysis of segments of transcribed interviews and student-related public documents finds a mismatch between a social justice curriculum at school and its transfer into students’ accounts of outside school lived realities. The article concludes that a productive social justice pedagogy must use its key principles of (con)textual interrogation to engage students in reflexive practice about their positioning within and against discourses of social justice in their student and civic lives. An impending national curriculum must decide whether or not it negotiates the discursive divide any better.
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Aim: In the current climate of medical education, there is an ever-increasing demand for and emphasis on simulation as both a teaching and training tool. The objective of our study was to compare the realism and practicality of a number of artificial blood products that could be used for high-fidelity simulation. Method: A literature and internet search was performed and 15 artificial blood products were identified from a variety of sources. One product was excluded due to its potential toxicity risks. Five observers, blinded to the products, performed two assessments on each product using an evaluation tool with 14 predefined criteria including color, consistency, clotting, and staining potential to manikin skin and clothing. Each criterion was rated using a five-point Likert scale. The products were left for 24 hours, both refrigerated and at room temperature, and then reassessed. Statistical analysis was performed to identify the most suitable products, and both inter- and intra-rater variability were examined. Results: Three products scored consistently well with all five assessors, with one product in particular scoring well in almost every criterion. This highest-rated product had a mean rating of 3.6 of 5.0 (95% posterior Interval 3.4-3.7). Inter-rater variability was minor with average ratings varying from 3.0 to 3.4 between the highest and lowest scorer. Intrarater variability was negligible with good agreement between first and second rating as per weighted kappa scores (K = 0.67). Conclusion: The most realistic and practical form of artificial blood identified was a commercial product called KD151 Flowing Blood Syrup. It was found to be not only realistic in appearance but practical in terms of storage and stain removal.
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Enhancing children's self-concepts is widely accepted as a critical educational outcome of schooling and is postulated as a mediating variable that facilitates the attainment of other desired outcomes such as improved academic achievement. Despite considerable advances in self-concept research, there has been limited progress in devising teacher-administered enhancement interventions. This is unfortunate as teachers are crucial change agents during important developmental periods when self-concept is formed. The primary aim of the present investigation is to build on the promising features of previous self-concept enhancement studies by: (a) combining two exciting research directions developed by Burnett and Craven to develop a potentially powerful cognitive-based intervention; (b) incorporating recent developments in theory and measurement to ensure that the multidimensionality of self-concept is accounted for in the research design; (c) fully investigating the effects of a potentially strong cognitive intervention on reading, mathematics, school and learning self-concepts by using a large sample size and a sophisticated research design; (d) evaluating the effects of the intervention on affective and cognitive subcomponents of reading, mathematics, school and learning self-concepts over time to test for differential effects of the intervention; (e) modifying and extending current procedures to maximise the successful implementation of a teacher-mediated intervention in a naturalistic setting by incorporating sophisticated teacher training as suggested by Hattie (1992) and including an assessment of the efficacy of implementation; and (f) examining the durability of effects associated with the intervention.
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In today's highly challenging business environment, an innovative and systemic approach is imperative to survival and growth. Organisational integration and technological integration, are often seen as a catalyst of change that could lead to significant improvements in organisations. The levels of improvement in inter and intra firm integration should arise from a detailed understanding and development of competences within and between organisations. Preliminary findings suggest that lack of trust across organisational cultures within the firms has a negative influence on the development of the capabilities to integrate and align technological innovations and hinders implementation and the effectiveness of the operations. Additionally, poor communication and conflict effects customer satisfaction. Firms need to transfer the competences that support cooperative integration, developed through interaction with supply chain partners, to their relationship arrangements with other supply chain partners, as these are key to ensuring low operational costs.
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An estimation of costs for maintenance and rehabilitation is subject to variation due to the uncertainties of input parameters. This paper presents the results of an analysis to identify input parameters that affect the prediction of variation in road deterioration. Road data obtained from 1688 km of a national highway located in the tropical northeast of Queensland in Australia were used in the analysis. Data were analysed using a probability-based method, the Monte Carlo simulation technique and HDM-4’s roughness prediction model. The results of the analysis indicated that among the input parameters the variability of pavement strength, rut depth, annual equivalent axle load and initial roughness affected the variability of the predicted roughness. The second part of the paper presents an analysis to assess the variation in cost estimates due to the variability of the overall identified critical input parameters.
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Decentralized and regional load-frequency control of power systems operating in normal and near-normal conditions has been well studied; and several analysis/synthesis approaches have been developed during the last few decades. However in contingency and off-normal conditions, the existing emergency control plans, such as under-frequency load shedding, are usually applied in a centralized structure using a different analysis model. This paper discusses the feasibility of using frequency-based emergency control schemes based on tie-line measurements and local information available within a control area. The conventional load-frequency control model is generalized by considering the dynamics of emergency control/protection schemes and an analytic approach to analyze the regional frequency response under normal and emergency conditions is presented.
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Readers and writers use a variety of modes of inscription – print, oral and multimedia – to understand, analyze, critique and transform their social, cultural and political worlds. Beginning from Freire (1970), ‘critical literacy’ has become a theoretically diverse educational project, drawing from reader response theory, linguistic and grammatical analysis from critical linguistics, feminist, poststructuralist, postcolonial and critical race theory, and cultural and media studies. In the UK, Australia, Canada, South Africa, New Zealand and the US different approaches to critical literacy have been developed in curriculum and schools. These focus on social and cultural analysis and on how print and digital texts and discourses work, with a necessary and delicate tension between classroom emphasis on student and community cultural ‘voice’ and social analysis – and on explicit engagement with the technical features and social uses of written and multimodal texts.
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Theories that inform pedagogical practices have positioned young children as innocent, pre-political and egocentric. This paper draws from an action research study that investigates the impact of “transformative storytelling”, where stories purposefully crafted to counter metanarratives, revealed the impact of human greed with one class of children aged five to six years of age. Derrida’s notion of “cinders” provided a concept for investigating the traces or imprints the language of story left behind, amidst the children’s comments and actions, enabling the possibilities of the history of these “cinders” (that is what informed these comments and actions) to be noticed. Readings of some of the children’s responses suggest that children aged five and six years can engage in political discourse through the provocation of “transformative storytelling”, and that their engagement demonstrated the consideration of others through critical awareness and intersubjectivity. These early readings raise questions regarding curriculum content and pedagogical practices in early years education and the validity of ongoing educational goals that incorporate critical awareness and intersubjectivity to equip students with communitarian strategies to counter the individualistic outlook of neoliberalist societies.
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That Kenneth Frampton has had a significant impact on architectural thinking in Australia was recently demonstrated by his visit, which included two well-attended public lectures and a one-day symposium dedicated to his thinking and writing. Billed as part of the Year of the Built Environment celebrations, these were hosted by the New South Wales chapter of the RAIA, the UNSW Faculty of the Built Environment and the Museum of Contemporary Art. Richard Francis-Jones of FJMT coordinated the symposium, which comprised presentations divided into two sessions, entitled - predictably through no doubt with good intentions - 'Theory' and 'Practice', with four academics and four practitioners in each. Frampton sat to the side throughout, and delivered his own response between them,noting his discomfort in seemingly straddling this divide, as an architect first, then writer and academic, later. Predictably, the familiar Critical Regionalism argument was the mainstay of the day, perhaps the easiest to handle and now almost automatic, despite the fact that Frampton noted when questioned that he hasn't talked much about it in the last 10 years.
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Every one and their dog has done a Docklands design studio at university if they were educated in Melbourne. And all designers have an opinion on the idea of Docklands and its potential in the future, but few, apart from the Docklands authority themselves, have a handle on what's going on there now and what constitutes its qualities.
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This year, as it has been during most of the years that I can remember, AILA's various state awards have been controversial (depending on who you talk to). In at least one state, after only a small number of awards have been handed out, the local chapter is thinking of modifying the awards to (presumably) bring them into synch with the values of local member practices. In almost every case when an awards-related complaint has been made, the judges have been seen as the problem. After all, the judges make the determination so they must have poor judgement.
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The recent Supreme Court decision of Queensland v B [2008] 2 Qd R 562 has significant implications for the law that governs consent and abortions. The judgment purports to extend the ratio of Secretary, Department of Health and Community Services (NT) v JWB and SMB (1991) 175 CLR 218 (Marion’s Case) and impose a requirement of court approval for terminations of pregnancy for minors who are not Gillick-competent. This article argues against the imposition of this requirement on the ground that such an approach is an unjustifiable extension of the reasoning in Marion’s Case. The decision, which is the first judicial consideration in Queensland of the position of medical terminations, also reveals systemic problems with the criminal law in that State. In concluding that the traditional legal excuse for abortions will not apply to those which are performed medically, Queensland v B provides further support for calls to reform this area of law.