853 resultados para Extreme value theory


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Assessment for Learning is a pedagogical practice with anticipated gains of increased student motivation, mastery and autonomy as learners develop their capacity to monitor and plan their own learning progress. Assessment for Learning (AfL) differs from Assessment of learning in its timing, occurring within the regular flow of learning rather than end point, in its purpose of improving student learning rather than summative grading and in the ownership of the learning where the student voice is heard in judging quality. Since Black and Wiliam (1998) highlighted the achievement gains that AfL practices seem to bring to all learners in classrooms, it has become part of current educational policy discourse in Australia, yet teacher adoption of the practices is not a straightforward implementation of techniques within an existing classroom repertoire. As can be seen from the following meta-analysis, recent research highlights a more complex interrelationship between teacher and student beliefs about learning and assessment, and the social and cultural interactions in and contexts of the classroom. More research is needed from a sociocultural perspective that allows meaning to emerge from practice. Before another policy push, we need to understand better the many factors within the assessment relationship. We need to hear from teachers and students through long-term AfL case studies both to inform AfL theory and to shed light on the complexities of pedagogical change for enhancing learner autonomy.

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Background The residue-wise contact order (RWCO) describes the sequence separations between the residues of interest and its contacting residues in a protein sequence. It is a new kind of one-dimensional protein structure that represents the extent of long-range contacts and is considered as a generalization of contact order. Together with secondary structure, accessible surface area, the B factor, and contact number, RWCO provides comprehensive and indispensable important information to reconstructing the protein three-dimensional structure from a set of one-dimensional structural properties. Accurately predicting RWCO values could have many important applications in protein three-dimensional structure prediction and protein folding rate prediction, and give deep insights into protein sequence-structure relationships. Results We developed a novel approach to predict residue-wise contact order values in proteins based on support vector regression (SVR), starting from primary amino acid sequences. We explored seven different sequence encoding schemes to examine their effects on the prediction performance, including local sequence in the form of PSI-BLAST profiles, local sequence plus amino acid composition, local sequence plus molecular weight, local sequence plus secondary structure predicted by PSIPRED, local sequence plus molecular weight and amino acid composition, local sequence plus molecular weight and predicted secondary structure, and local sequence plus molecular weight, amino acid composition and predicted secondary structure. When using local sequences with multiple sequence alignments in the form of PSI-BLAST profiles, we could predict the RWCO distribution with a Pearson correlation coefficient (CC) between the predicted and observed RWCO values of 0.55, and root mean square error (RMSE) of 0.82, based on a well-defined dataset with 680 protein sequences. Moreover, by incorporating global features such as molecular weight and amino acid composition we could further improve the prediction performance with the CC to 0.57 and an RMSE of 0.79. In addition, combining the predicted secondary structure by PSIPRED was found to significantly improve the prediction performance and could yield the best prediction accuracy with a CC of 0.60 and RMSE of 0.78, which provided at least comparable performance compared with the other existing methods. Conclusion The SVR method shows a prediction performance competitive with or at least comparable to the previously developed linear regression-based methods for predicting RWCO values. In contrast to support vector classification (SVC), SVR is very good at estimating the raw value profiles of the samples. The successful application of the SVR approach in this study reinforces the fact that support vector regression is a powerful tool in extracting the protein sequence-structure relationship and in estimating the protein structural profiles from amino acid sequences.

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Levels of waste within the construction industry need to be reduced for environmental and economic reasons. Changing people's wasteful behaviour can make a significant contribution. This paper describes a research project that used Ajzen's 'theory of planned behaviour' to investigate the attitudinal forces that shape behaviour at the operative level. It concludes that operatives see waste as an inevitable by-product of construction activity. Attitudes towards waste management are not negative, although they are pragmatic and impeded by perceptions of a lack of managerial commitment. Waste management is perceived as a low project priority, and there is an absence of appropriate resources and incentives to support it. A theory of waste behaviour is proposed for the construction industry, and recommendations are made to help managers improve operatives' attitudes towards waste.

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Poly(olefin sulfone)s, formed by the reaction of sulfur dioxide (SO2) and an olefin, are known to be highly susceptible to degradation by radiation and thus have been identified as candidate materials for chain scission-based extreme ultraviolet lithography (EUVL) resist materials. In order to investigate this further, the synthesis and characterisation of two poly(olefin sulfone)s namely poly(1-pentene sulfone) (PPS) and poly(2-methyl-1-pentene sulfone) (PMPS), was achieved and the two materials were evaluated for possible chain scission EUVL resist applications. It was found that both materials possess high sensitivities to EUV photons; however; the rates of outgassing were extremely high. The only observed degradation products were found to be SO2 and the respective olefin suggesting that depolymerisation takes place under irradiation in a vacuum environment. In addition to depolymerisation, a concurrent conversion of SO2 moieties to a sulfide phase was observed using XPS.

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A series of polymers with a comb architecture were prepared where the poly(olefin sulfone) backbone was designed to be highly sensitive to extreme ultraviolet (EUV) radiation, while the well-defined poly(methyl methacrylate) (PMMA) arms were incorporated with the aim of increasing structural stability. It is hypothesized that upon EUV radiation rapid degradation of the polysulfone backbone will occur leaving behind the well-defined PMMA arms. The synthesized polymers were characterised and have had their performance as chain-scission EUV photoresists evaluated. It was found that all materials possess high sensitivity towards degradation by EUV radiation (E0 in the range 4–6 mJ cm−2). Selective degradation of the poly(1-pentene sulfone) backbone relative to the PMMA arms was demonstrated by mass spectrometry headspace analysis during EUV irradiation and by grazing-angle ATR-FTIR. EUV interference patterning has shown that materials are capable of resolving 30 nm 1:1 line:space features. The incorporation of PMMA was found to increase the structural integrity of the patterned features. Thus, it has been shown that terpolymer materials possessing a highly sensitive poly(olefin sulfone) backbone and PMMA arms are able to provide a tuneable materials platform for chain scission EUV resists. These materials have the potential to benefit applications that require nanopattering, such as computer chip manufacture and nano-MEMS.

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A series of high-performance polycarbonates have been prepared with glass-transition temperatures and decomposition temperatures that are tunable by varying the repeat-unit chemical structure. Patterning of the polymers with extreme UV lithography has been achieved by taking advantage of direct photoinduced chain scission of the polymer chains, which results in a molecular-weight based solubility switch. After selective development of the irradiated regions of the polymers, feature sizes as small as 28.6 nm have been printed and the importance of resist-developer interactions for maximizing image quality has been demonstrated.

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Some initial EUVL patterning results for polycarbonate based non-chemically amplified resists are presented. Without full optimization the developer a resolution of 60 nm line spaces could be obtained. With slight overexposure (1.4 × E0) 43.5 nm lines at a half pitch of 50 nm could be printed. At 2x E0 a 28.6 nm lines at a half pitch of 50 nm could be obtained with a LER that was just above expected for mask roughness. Upon being irradiated with EUV photons, these polymers undergo chain scission with the loss of carbon dioxide and carbon monoxide. The remaining photoproducts appear to be non-volatile under standard EUV irradiation conditions, but do exhibit increased solubility in developer compared to the unirradiated polymer. The sensitivity of the polymers to EUV light is related to their oxygen content and ways to increase the sensitivity of the polymers to 10 mJ cm-2 is discussed.

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This paper offers a reply to Jochen Runde's critical appraisal of the ontological framework underpinning Dopfer and Potts's (2008) General Theory of Economic Evolution. We argue that Runde's comprehensive critique contains several of what we perceive to be misunderstandings in relation to the key concepts of ‘generic’ and ‘meso’ that we seek here to unpack and redress.

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Understanding consumer value is imperative in health care as the receipt of value drives the demand for health care services. While there is increasing research into health-care that adopts an economic approach to value, this paper investigates a non-financial exchange context and uses an experiential approach to value, guided by a social marketing approach to behaviour change. An experiential approach is deemed more appropriate for government health-care services that are free and for preventative rather than treatment purposes. Thus instead of using an illness-paradigm to view health services outcomes, we adopt a wellness paradigm. Using qualitative data gathered during 25 depth interviews the authors demonstrate how social marketing thinking has guided the identification of six themes that represent four dimensions of value (functional, emotional, social and altruistic) evident during the health care consumption process of a free government service.

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For the 2005 season, Mackay Sugar and its growers agreed to implement a new cane payment system. The aim of the new system was to better align the business drivers between the mill and its growers and as a result improve business decision making. The technical basis of the new cane payment system included a fixed sharing of the revenue from sugar cane between the mill and growers. Further, the new system replaced the CCS formula with a new estimate of recoverable sugar (PRS) and introduced NIR for payment analyses. Significant mill and grower consultation processes led to the agreement to implement the new system in 2005 and this consultative approach has been reflected in two seasons of successful operation.

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Alliances, with other inter-organisational forms, have become a strategy of choice and necessity for both the private and public sectors. From initial formation, alliances develop and change in different ways, with research suggesting that many alliances will be terminated without their potential value being realised. Alliance process theorists address this phenomenon, seeking explanations as to why alliances unfold the way they do. However, these explanations have generally focussed on economic and structural determinants: empirically, little is known about how and why the agency of alliance actors shapes the alliance path. Theorists have suggested that current alliance process theory has provided valuable, but partial accounts of alliance development, which could be usefully extended by considering social and individual factors. The purpose of this research therefore was to extend alliance process theory by exploring individual agency as an explanation of alliance events and in doing so, reveal the potential of a multi-frame approach for understanding alliance process. Through an historical study of a single, rich case of alliance process, this thesis provided three explanations for the sequence of alliance events, each informed by a different theoretical perspective. The explanatory contribution of the Individual Agency (IA) perspective was distilled through juxtaposition with the perspectives of Environmental Determinism (ED) and Indeterminacy/Chance (I/C). The research produced a number of findings. First, it provided empirical support for the tentative proposition that the choices and practices of alliance actors are partially explanatory of alliance change and that these practices are particular to the alliance context. Secondly, the study found that examining the case through three theoretical frames provided a more complete explanation. Two propositions were put forward as to how individual agency can be theorised within this three-perspective framework. Finally, the case explained which alliance actors were required to shape alliance decision making in this case and why.

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Purpose: This paper aims to examine the integration of entrepreneurship and strategy to develop a conceptual framework of strategic entrepreneurship. The framework is developed through an analysis of theory and refined through an examination of practice. Design/methodology/approach: This framework is considered in the context of potentially entrepreneurial and strategic activity undertaken by 12 of the 17 state-owned enterprises (SOEs) operating in New Zealand in 2006-2007. Based on a review of documents, observation, and interviews with SOE executives, cases of 12 SOE activities were analysed to compare and contrast strategic entrepreneurship in practice. Findings: The findings reveal distinct elements within the four activities classified as strategic entrepreneurship, activities, such as leveraging from core skills and resources from a strategic perspective, and innovation from an entrepreneurial perspective. Originality/value: This study is one of the first to examine the nature of strategic entrepreneurship in practice and the associated financial returns.

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Purpose – The aim of this paper is to examine the process of change in an Australian not-for-profit organization, from a cash-based to an accrual-based accounting system. Its particular focus is the relationship between the image portrayed by accrual accounting adoption and the technical realities of the new system. Design/methodology/approach – Data were gathered from interviews, documents and meetings, and were contextualized and interpreted using institutional theory. Findings – The decision to change to accrual accounting was made at the top of the organizational hierarchy in response to institutional pressure to present a corporate image. The implementation of the new system was poorly conceived, inadequately resourced, and hampered by an authoritarian structure that effectively ignored the technical incompetence and training needs of many accounting staff. This resulted in an accounting system half way between cash and accrual, and very different from the system as it had been promoted. The process caused conflict at all levels of the organizational hierarchy. Research limitations/implications – Accounting in not-for-profit organizations is an under-researched area offering potential for fruitful research in a changing institutional landscape. This institutional approach, while offering just one interpretation of the qualitative data gathered in this project, provides valuable insights about the process of change. Practical implications – Not-for-profit organizations play a vital economic and social role, and need carefully to assess their responses to ongoing institutional pressures. In implementing change, they face the challenge of balancing the promotion of an institutionally acceptable image and the need for technical efficiencies. Originality/value – The examination of change in an organization provides a rich context for the exploration of the dynamic, problematic process by which a new accounting practice is embedded and institutionalized. Keywords Institutional theory, Not-for-profit organizations, Accrual accounting, Change process, Qualitative research, Change management, Decision making, Training needs, Australia Paper type Research paper