901 resultados para Nontrivial critical point of a polynomial


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Currently there is no reliable objective method to quantify the setting properties of acrylic bone cements within an operating theatre environment. Ultrasonic technology can be used to determine the acoustic properties of the polymerising bone cement, which are linked to material properties and provide indications of the physical and chemical changes occurring within the cement. The focus of this study was the critical evaluation of pulse-echo ultrasonic test method in determining the setting and mechanical properties of three different acrylic bone cement when prepared under atmospheric and vacuum mixing conditions. Results indicated that the ultrasonic pulse-echo technique provided a highly reproducible and accurate method of monitoring the polymerisation reaction and indicating the principal setting parameters when compared to ISO 5833 standard, irrespective of the acrylic bone cement or mixing method used. However, applying the same test method to predict the final mechanical properties of acrylic bone cement did not prove a wholly accurate approach. Inhomogeneities within the cement microstructure and specimen geometry were found to have a significant influence on mechanical property predictions. Consideration of all the results suggests that the non-invasive and non-destructive pulse-echo ultrasonic test method is an effective and reliable method for following the full polymerisation reaction of acrylic bone cement in real-time and then determining the setting properties within a surgical theatre environment. However the application of similar technology for predicting the final mechanical properties of acrylic bone cement on a consistent basis may prove difficult.

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This paper describes a study that used video materials and visits to an airport to prepare children on the autism spectrum for travel by plane. Twenty parents and carers took part in the study with children aged from 3 to 16 years. The authors explain that the methods they used were based on Applied Behaviour Analysis (ABA) research; a video modeling technique called Point-Of-View Video-priming and during visits to an airport they used procedures known as Natural Environment Teaching. The findings suggest that using video and preparing children by taking them through what is likely to happen in the real environment when they travel by plane is effective and the authors suggest these strategies could be used to support children with autism with other experiences they need or would like to engage in such as visits to the dentist or hairdressers and access to leisure centres and other public spaces.

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The rhizosphere is a major sink for photo-assimilated carbon and quantifying inputs into this sink is one of the main goals of rhizosphere biology as organic carbon lost from plant roots supports a higher microbial population in the rhizosphere compared to bulk soil. Two fundamentally different14CO2 labelling strategies have been developed to estimate carbon fluxes through the rhizosphere - continuous feeding of shoots with labelled carbon dioxide and pulse-chase experiments. The biological interpretation that can be placed on the results of labelling experiments is greatly biased by the technique used. It is the purpose of this paper to assess the advantages, disadvantages and the biological interpretation of both continuous and pulse labelling and to consider how to partition carbon fluxes within the rhizosphere. © 1994 Kluwer Academic Publishers.

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Polycythaemia vera (PV) is a chronic blood cancer; its clinical features are dominated by myeloproliferation (erythrocytosis, often leucocytosis and/or thrombocytosis) and a tendency for thrombosis and transformation to myelofibrosis or acute myeloid leukaemia. In the past 10 years the pathophysiology of this condition has been defined as JAK/STAT pathway activation, almost always due to mutations in JAK2 exons 12 or 14 (JAK2 V617F). In the same time period our understanding of the optimal management of PV has expanded, most recently culminating in the approval of JAK inhibitors for the treatment of PV patients who are resistant or intolerant to therapy with hydroxycarbamide. It has also been demonstrated that life expectancy for many patients with PV is not normal, nor is their quality of life. We critically explore these findings and discuss their impact. In addition, we highlight persisting gaps in our current management strategy; for example, what is the optimal first line cytoreductive therapy and, indeed, which patients need cytoreductive drugs.

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Policy in Child and Adolescent Mental Health (CAMH) in England has undergone radical changes in the last 15 years, with far reaching implications for funding models, access to services and service delivery. Using corpus analysis and critical discourse analysis, we explore how childhood, mental health, and CAMHS are constituted in 15 policy documents, 9 pre‐2010, and 6 post 2010. We trace how these constructions have changed over time, and consider the practice implications of these changes. We identify how children’s distress is individualised, through medicalising discourses and shifting understandings of the relationship between socioeconomic context and mental health. This is evidenced in a shift from seeing children’s mental health challenges as produced by social and economic inequities, to a view that children’s mental health must be addressed early to prevent future socio‐economic burden. We consider the implications CAMHS policies for the relationship between children, families, mental health services and the state. The paper concludes by exploring how concepts of ‘parity of esteem’ and ‘stigma reduction’ may inadvertently exacerbate the individualisation of children’s mental health.

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European Community's Seventh Framework Programme FP7/2007-2013 under grant agreement no. 238128

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The scale and speed of China’s urbanization translate into major challenges for sustainability. Could the ‘eco-city’ and ‘low-carbon’ agendas, and the promotion of related pilot cities drive Chinese urban practice towards more environmentally sustainable solutions? We explore this question through a critical review of experience in China, identifying problems relating to the development of space, the treatment of scale and the pursuit of efficiency (the ‘space-scale-efficiency nexus’). China seeks sustainable solutions through eco and low-carbon agendas, but our review finds that current efforts fall short of expectations, and problematic patterns are repeated. We propose that a geo-administrative notion of functional regions could provide a strategic framework to address the range of design, physical and administrative planning problems, ensuring that eco-city and low-carbon city pilots result in comprehensive solutions that can be effectively replicated.

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This paper discusses the literature on the established determinants of productivity in the retail sector. It also draws attention to some neglected strands of research which provide useful insights into strategies that could allow productivity enhancements in this area of the economy. To date, very few attempts have been made to integrate different specialisms in order to explain what drives productivity in retail. Here this paper rectifies this omission by putting together studies from economics, geography, knowledge management and employment studies. It is the authors' view that quantitative studies of retail productivity should focus on total factor productivity in retailing as the result of competition/composition effects, planning regulations, information and communications technology, the multinational operation element and workforce skills. Further, the fact that retail firms possess advantages that are transferable between locations suggests that investment in strategies enhancing the transfer of explicit and tacit knowledge between and within businesses are crucial to achieve productivity gains.

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This thesis analyses how dominant policy approaches to peacebuilding have moved away from a single and universalised understanding of peace to be achieved through a top-down strategy of democratisation and economic liberalisation, prevalent at the beginning of 1990s. Instead, throughout the 2000s, peacebuilders have increasingly adopted a commitment to cultivating a bottom-up and hybrid peace building process that is context-sensitive and intended to be more respectful of the needs and values of post-war societies. The projects of statebuilding in Kosovo and, to a lesser extent, in Bosnia are examined to illustrate the shift. By capturing this shift, I seek to argue that contemporary practitioners of peace are sharing the sensibility of the theoretical critics of liberalism. These critics have long contended that post-war societies cannot be governed from ‘above’ and have advocated the adoption of a bottom-up approach to peacebuilding. Now, both peace practitioners and their critics share the tendency to embrace difference in peacebuilding operations, but this shift has failed to address meaningfully the problems and concerns of post-conflict societies. The conclusion of this research is that, drawing on the assumption that these societies are not capable of undertaking sovereign acts because of their problematic inter-subjective frames, the discourses of peacebuilding (in policy-making and academic critique) have increasingly legitimised an open-ended role of interference by external agencies, which now operate from ‘below’. Peacebuilding has turned into a long-term process, in which international and local actors engage relationally in the search for ever-more emancipatory hybrid outcomes, but in which self-government and self-determination are constantly deferred. Processes of emphasising difference have thus denied the political autonomy of post-war societies and have continuously questioned the political and human equality of these populations in a hierarchically divided world.

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This thesis explores the processes through which scarcity is constructed in informal settlements and how conditions emerging within its limits gives way to particular socio-spatial phenomena and influence the emergence of self-organisation and creative strategies from a non-expert perspective. At the same time, this thesis deconstructs these emerging tactics (reactive and transformative) in a diagrammatic way to generate a critical study of their potential for socio-spatial change that goes beyond the everyday survival. Most people associate scarcity with “not having enough” of something, most usually of a material nature. In contrast, this paper is based on the premise that scarcity is a constructed condition, therefore exploring it beyond its immediate manifestation and illustrating its discursive, distributive and socio-material components. In this line, the research uses Assemblage Theory as both an approach and a tool for analysis. This approach allows the research to depart from everyday narratives of the residents, and gradually evolve into a multi-scalar, non-linear reading of scarcity, by following leads into different realms and unpacking a series of routine events to uncover their connections to wider processes and particular elements affecting the settlement and the city as a whole. For this purpose, the research is based on a qualitative, flexible and multi-sited methodology, using different case studies as testing grounds. Collected data stems from a 11-months ethnographic fieldwork in informal settlements in Ecuador and Kenya, analysing the socio-spatial practices and strategies deployed by the different actors producing the built environment and arising from everyday and latent experiences of scarcity. The thesis examines the multi-scalar nature of these strategies, including self-building and management tactics, the mobilisation of grassroots organisations, the innovative ways of collaborating deployed by different coalitions and the reformulation of urban development policies. As outcomes of the research, the thesis will show illustrative diagrams that allow a better understanding of, firstly, the construction of scarcity in the built environment beyond its immediate manifestation and secondly, the way that emerging tactics a) improve existing conditions of scarcity, b) reinforce the status quo or c) contribute to the worsening of the original condition. Therefore, this thesis aims to offer lessons with both practical and theoretical considerations, by firstly, giving an insight into the complexity and transcalar nature of the construction of scarcity in informal settlements; secondly, by illustrating how acute conditions related to scarcity gives birth to a plethora of particular phenomena shaping the territory, social relationships and processes; and thirdly, by identifying specific characteristics within the informal that might allow for new readings of the city and possibilities for socio-spatial change under conditions of scarcity.

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This is the first critical edition of the works of Andrew Lang (1844-1912), the Scottish writer whose enormous output spanned the whole range of late nineteenth century intellectual culture. Neglected since his death, partly because of the diversity of his interests and the volume of his writing, his cultural centrality and the interdisciplinary nature of his work make him a vital figure for contemporary scholars. This volume covers his work in anthropology, including that on fairy tale, folklore, the origins of religion, and psychical research.

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This is the first critical edition of the works of Andrew Lang (1844-1912), the Scottish writer whose enormous output spanned the whole range of late nineteenth-century intellectual culture. Neglected since his death, partly because of the diversity of his interests and the volume of his writing, his cultural centrality and the interdisciplinary nature of his work make him a vital figure for contemporary scholars. This volume covers his work on literary criticism, history and biography.