Integrated optics for nulling interferometry in the thermal infrared: progress and recent achievements

The search for Earth-like exoplanets, orbiting in the habitable zone of stars other than our Sun and showing biological activity, is one of the most exciting and challenging quests of the present time. Nulling interferometry from space, in the thermal infrared, appears as a promising candidate technique for the task of directly observing extra-solar planets. It has been studied for about 10 years by ESA and NASA in the framework of the Darwin and TPF-I missions respectively. Nevertheless, nulling interferometry in the thermal infrared remains a technological challenge at several levels. Among them, the development of the "modal filter" function is mandatory for the filtering of the wavefronts in adequacy with the objective of rejecting the central star flux to an efficiency of about 105. Modal filtering takes benefit of the capability of single-mode waveguides to transmit a single amplitude function, to eliminate virtually any perturbation of the interfering wavefronts, thus making very high rejection ratios possible. The modal filter may either be based on single-mode Integrated Optics (IO) and/or Fiber Optics. In this paper, we focus on IO, and more specifically on the progress of the on-going "Integrated Optics" activity of the European Space Agency.

Incorporating HACCP into national food control systems - Analyzing progress in the United Arab Emirates

Today governments and other parties involved in food control are under constant pressure to find more efficient and effective mechanisms to carry out their mandates for food control. This has led to international recognition of the importance of the HACCP system as a food control tool and guidance on the role of government agencies in the application of such a system has been developed. Based on this international guidance, four main elements identified as key activities have been used in this study to evaluate the progress of HACCP implementation in the UAE. The internal Strengths and Weaknesses, as well as the external Opportunities and Threats that the government is facing towards the implementation of a HACCP-based food control system have been identified. The analysis shows that the government’s dedicated role has been an essential driving force to encourage the implementation of a HACCP-based food control system. Some areas of difficulty, including the dependence on high levels of food imports, are highlighted.

School effectiveness and the displacement of equity discourses in education

An essential aspect of school effectiveness theory is the shift from the social to the organisational context, from the macro- to the micro-culture. The school is represented largely as a bounded institution, set apart, but also in a precarious relationship with the broader social context. It is ironic that at a time when social disadvantage appears to be increasing in Britain and elsewhere, school effectiveness theory places less emphasis on poverty, deprivation and social exclusion. Instead, it places more emphasis on organisational factors such as professional leadership, home/school partnerships, the monitoring of academic progress, shared vision and goals. In this article, the authors evaluate the extent to which notions of effectiveness have displaced concerns about equity in theories of educational change. They explore the extent to which the social structures of gender, ethnicity, sexualities, special needs, social class, poverty and other historical forms of inequality have been incorporated into or distorted and excluded from effectiveness thinking.

Review of R&D progress and practical application of the solar photovoltaic/thermal (PV/T) technologies

In this paper, the global market potential of solar thermal, photovoltaic (PV) and combined photovoltaic/thermal (PV/T) technologies in current time and near future was discussed. The concept of the PV/T and the theory behind the PV/T operation were briefly introduced, and standards for evaluating technical, economic and environmental performance of the PV/T systems were addressed. A comprehensive literature review into R&D works and practical application of the PV/T technology was illustrated and the review results were critically analysed in terms of PV/T type and research methodology used. The major features, current status, research focuses and existing difficulties/barriers related to the various types of PV/T were identified. The research methods, including theoretical analyses and computer simulation, experimental and combined experimental/theoretical investigation, demonstration and feasibility study, as well as economic and environmental analyses, applied into the PV/T technology were individually discussed, and the achievement and problems remaining in each research method category were described. Finally, opportunities for further work to carry on PV/T study were identified. The review research indicated that air/water-based PV/T systems are the commonly used technologies but their thermal removal effectiveness is lower. Refrigerant/heat-pipe-based PV/Ts, although still in research/laboratory stage, could achieve much higher solar conversion efficiencies over the air/water-based systems. However, these systems were found a few technical challenges in practice which require further resolutions. The review research suggested that further works could be undertaken to (1) develop new feasible, economic and energy efficient PV/T systems; (2) optimise the structural/geometrical configurations of the existing PV/T systems; (3) study long term dynamic performance of the PV/T systems; (4) demonstrate the PV/T systems in real buildings and conduct the feasibility study; and (5) carry on advanced economic and environmental analyses. This review research helps finding the questions remaining in PV/T technology, identify new research topics/directions to further improve the performance of the PV/T, remove the barriers in PV/T practical application, establish the standards/regulations related to PV/T design and installation, and promote its market penetration throughout the world.