930 resultados para Nuclear matters


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We report on recent estimates of the J/Ψ mass shift in infinite nuclear matter and finite nuclei arising from in-medium D and D* meson loops. The density dependence of the J/Ψ mass shift is evaluated employing medium-modified D and D* meson masses derived within the quark-meson coupling model. Using a local density approximation, J/Ψ-nuclear bound state energies are calculated for a range of nuclei. We predict that J/Ψ-nuclear bound states should be observed with a clear signal in experiments, provided the J/Ψ meson is produced in recoilless kinematics. © Published under licence by IOP Publishing Ltd.

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Summary. On 11 March 2011, a devastating earthquake struck Japan and caused a major nuclear accident at the Fukushima Daiichi nuclear plant. The disaster confirmed that nuclear reactors must be protected even against accidents that have been assessed as highly unlikely. It also revealed a well-known catalogue of problems: faulty design, insufficient back-up systems, human error, inadequate contingency plans, and poor communications. The catastrophe triggered the rapid launch of a major re-examination of nuclear reactor security in Europe. It also stopped in its tracks what had appeared to be a ‘nuclear renaissance’, both in Europe and globally, especially in the emerging countries. Under the accumulated pressure of rising demand and climate warming, many new nuclear projects had been proposed. Since 2011 there has been more ambivalence, especially in Europe. Some Member States have even decided to abandon the nuclear sector altogether. This Egmont Paper aims to examine the reactions of the EU regarding nuclear safety since 2011. Firstly, a general description of the nuclear sector in Europe is provided. The nuclear production of electricity currently employs around 500,000 people, including those working in the supply chain. It generates approximately €70 billion per year. It provides roughly 30% of the electricity consumed in the EU. At the end of 2013, there were 131 nuclear power reactors active in the EU, located in 14 countries. Four new reactors are under construction in France, Slovakia and Finland. Secondly, this paper will present the Euratom legal framework regarding nuclear safety. The European Atomic Energy Community (EAEC or Euratom) Treaty was signed in 1957, and somewhat obscured by the European Economic Community (EEC) Treaty. It was a more classical treaty, establishing institutions with limited powers. Its development remained relatively modest until the Chernobyl catastrophe, which provoked many initiatives. The most important was the final adoption of the Nuclear Safety Directive 2009/71. Thirdly, the general symbiosis between Euratom and the International Atomic Energy Agency (IAEA) will be explained. Fourthly, the paper analyses the initiatives taken by the EU in the wake of the Fukushima catastrophe. These initiatives are centred around the famous ‘stress tests’. Fifthly, the most important legal change brought about by this event was the revision of Directive 2009/71. Directive 2014/87 has been adopted quite rapidly, and has deepened in various ways the role of the EU in nuclear safety. It has reinforced the role and effective independence of the national regulatory authorities. It has enhanced transparency on nuclear safety matters. It has strengthened principles, and introduced new general nuclear safety objectives and requirements, addressing specific technical issues across the entire life cycle of nuclear installations, and in particular, nuclear power plants. It has extended monitoring and the exchange of experiences by establishing a European system of peer reviews. Finally, it has established a mechanism for developing EU-wide harmonized nuclear safety guidelines. In spite of these various improvements, Directive 2014/87 Euratom still reflects the ambiguity of the Euratom system in general, and especially in the field of nuclear safety. The use of nuclear energy remains controversial among Member States. Some of them remain adamantly in favour, others against or ambivalent. The intervention of the EAEC institutions remains sensitive. The use of the traditional Community method remains limited. The peer review method remains a very peculiar mechanism that deserves more attention.

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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 middle years of schooling has emerged as an important focus in Australian education. Student disengagement and alienation, the negative effects of non-completion of the senior years of schooling and underachievement have raised concerns about the quality of education during the middle years. For many schools, reshaping the middle years has involved incorporating Information and Communication Technologies (ICT) to motivate students. However, simultaneously there is a need to ensure that programs are academically rigorous. There is little doubt that there are potential benefits to integrating ICT into programs for middle years’ students. However, little is known about how middle years’ teachers perceive higher order thinking, which is a component of academic rigour. This paper investigates the question of What are teachers’ perceptions of higher order thinking in an ICT environment? The study is underpinned by socio-cultural theory which is based on the belief that learning occurs through social interaction and that individuals are shaped by the social and cultural tools and instruments they engage with. This investigation used a collective case study design. Two methods were used for data collection. These methods are semi-structured interviews with individual teachers and a class and a focus group discussion with teachers. Findings indicate that teachers hold various perceptions of higher order thinking that lead to productive approaches to integrating ICT in middle years’ classrooms. The paper highlights that there may be a continuum of perceptions of higher order thinking with ICT. This continuum may inform professional developers who are guiding and supporting teachers to integrate ICT into middle years’ classrooms.

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The global financial crisis, global pandemics, global warming and peak oil are indicative of a world facing major environmental, social and economic problems. At the same time, world population continues to rise and global inequalities deepen. Children are the most vulnerable to the impacts of unsustainable living with specific harms arising because of their physical and cognitive vulnerabilities. Nevertheless, children do not have to be victims in the face of these challenges. Education, including early childhood education, has an important role to in building resilience and capabilities in children that equip them as active and informed citizens now and in the future and who are capable of contributing to healthy and sustainable ways of living. Drawing on educational change literature, action research, education for sustainability, health promotion and systems theory, this paper outlines three strategies that can help reorient early childhood education towards sustainability. One strategy is the adoption of whole centre approaches to sustainability and education for sustainability. This means working across the whole of a centre’s operations – curriculum and pedagogy, physical and social environments, its partnerships and community connections. The second strategy – applied in conjunction with the first – is the use of action research to investigate the early childhood setting and to create the desired changes. The third strategy is the adoption of systems thinking as a way of leveraging support and momentum for change so that education for sustainability goes beyond the initiatives of individual teachers and centres, and becomes a systems-wide imperative.