The BBC: the challenge to appeal to all audiences

The BBC's second most senior manager, Caroline Thompson gave the full story of the Russell Brand/Jonathan Ross scandal at Polis. Read her speech here. She denounced the phone call prank but said it must not stop the BBC taking risks and attempting to reach all audiences

Study of phase-matching geometries in bulk and periodically-poled lithium niobate and their use in intracavity terahertz optical parametric oscillators

This thesis describes the experimental implementation of novel intersecting cavity terahertz optical parametric oscillators based on bulk and periodically-poled magnesium oxide-doped lithium niobate. Both collinear and non-collinear phase-matching geometries have been demonstrated and injection-seeding has been implemented in devices using periodically-poled material to reduce threshold and increase the down-conversion efficiency. A comprehensive characterisation of the original intracavity terahertz OPO was undertaken, which revealed the parameters having the greatest impact on OPO efficiency (idler mirror reflectivity and cavity length) and led to a better understanding of the losses in the system. During the characterisation process, generation of further terahertz radiation at the same frequency as that generated by the parametric process was observed and identified as being a result of difference frequency generation (DFG) between the parametrically-generated idler and terahertz waves. This phenomenon had previously only been observed when periodically-poled materials were employed in the system. The effect of this additional DFG process has been analysed in terms of the enhancement of the terahertz field on the basis of the coupled wave equations and physically measured quantities. The use of periodically-poled lithium niobate has been a major part of the research presented in this thesis. A comprehensive study of the modified phase-matching conditions was carried out and both collinear and novel hybrid non-collinear phase-matching geometries were identified. Several computer models were developed to assess the performance of any given grating design in these different geometries and the effects of temperature tuning and pump wavelength variation were also investigated using the models. Experimental studies confirmed the viability of the modelling approach but material limitations (particularly the early onset of crystal damage) limited the outcomes of the experiments. A detailed comparison of the poled and bulk materials was made to highlight the present drawbacks of the poled material. Finally, injection seeding was used to improve the efficiency of the collinear phase-matched PPLN OPOs. When seeding was used the depletion of the pump pulse was increased to the point of being measurable, reaching an upper level of 10%. Coupling constraints placed on the seed laser limited the amount of depletion attained. The potential for injection seeding to be used in the hybrid non-collinear phase-matching scheme was also identified but not realised during the course of this work. Were this technique successful, the tuning range of the intersecting cavity terahertz OPO could be extended to encompass the sub-1THz region, something that has previously been limited by the available idler cavity angles

Evaluation of a peer led parenting intervention for disruptive behaviour problems in children: community based randomised controlled trial

Objective To evaluate the effectiveness of a peer led parenting intervention delivered to socially disadvantaged families. Design Randomised controlled trial. Setting Schools and children’s centres in a socially deprived borough of inner London. Participants Parental caregivers seeking help with managing the problem behaviours of 116 index children, aged 2-11 years; 59 families were randomised to the intervention and 57 to a waitlist control condition. Intervention Empowering parents, empowering communities is an eight week (two hours each week), manualised programme delivered to groups of parents by trained peer facilitators from the local community. Main outcome measures Child problems (number and severity), parental stress, and parenting competencies were assessed before and after the intervention using standardised parent reported measures. Results Significantly greater improvements in positive parenting practices and child problems were observed in the intervention group compared with the waitlist group, with no difference in parental stress between the groups. An intention to treat analysis for the primary outcome measure, the intensity subscale of the Eyberg child behaviour inventory, showed an intervention effect size of 0.38 (95% confidence interval 0.01 to 0.75, P=0.01). The intervention group had high rates of treatment retention (91.5%) and user satisfaction. Conclusion The peer led parenting intervention significantly reduced child behaviour problems and improved parenting competencies. This is a promising method for providing effective and acceptable parenting support to families considered hard to reach by mainstream services

Cytochrome b divergence between avian sister species is linked to generation length and body mass

It is increasingly realised that the molecular clock does not tick at a constant rate. Rather, mitochondrial mutation rates are influenced by factors such as generation length and body mass. This has implications for the use of genetic data in species delimitation. It could be that speciation, as recognised by avian taxonomists, is associated with a certain minimum genetic distance between sister taxa, in which case we would predict no difference in the cytochrome b divergence of sister taxa according to the species’ body size or generation time. Alternatively, if what taxonomists recognise as speciation has tended to be associated with the passage of a minimum amount of time since divergence, then there might be less genetic divergence between sister taxa with slower mutation rates, namely those that are heavier and/or with longer generation times. After excluding non-flying species, we analysed a database of over 600 avian sister species pairs, and found that species pairs with longer generation lengths (which tend to be the larger species) showed less cytochrome b divergence. This finding cautions against using any simple unitary criterion of genetic divergence to delimit species

Assessment of the sustainability performance of eco-engineering measures in the Mediterranean region

Eco-engineering has a crucial role in defining and achieving the sustainability credentials of a civil engineering project. Better eco-engineering practices would help better in reducing the adverse impacts on the environment and society, but also on the financial performance of the project. However, the assessment of the sustainability effects of eco-engineering strategies can be challenging, as the treatment of this topic has been neglected in the scientific literature. The challenges lie in balancing the project delivery objectives with the sustainable design that will ensure appropriate and satisfactory environmental and financial performance and deliver social benefits such as ecosystem services. In order to achieve better practice and advance the knowledge in the field, there is a need for broader analysis of completed eco-engineering projects applied at different spatio-temporal scales. The aim of this study was to critically analyse 23 eco-engineering case studies provided by the ECOMED project partners using a life cycle analysis through a single sustainability framework based on a relatively small set of key performance indicators (KPIs), which reflect the principles of sustainability, and which are not contextual for eco-engineering projects. The objectives of this study are twofold: (i) to highlight areas of best practice and potential enhancement in the application of eco-engineering strategies, and (ii) to propose refinement and enhancement of the existing framework with KPIs contextual to eco-engineering projects. The results of the study suggest that the feasibility, mobilisation, and the long-term stages of an eco-engineering project are the most sustainable project stages, while the award, construction, and monitoring stages could generally benefit from a range of enhancements including benefits stemming from double-loop learning and a common basis for the specification and quantification of the financial resources needed to apply eco-engineering strategies. The outcomes of this study will benefit decision makers and eco-engineering practitioners alike in terms of not only raising the sustainability profile of the projects they are involved in, but also in terms of more efficient and cost-effective application of eco-engineering strategies