High quality GaMnAs films grown with As dimers

We demonstrate that GaMnAs films grown with As2 have excellent structural, electrical and magnetic properties, comparable or better than similar films grown with As4. Using As2, a Curie temperature of 112K has been achieved, which is slightly higher than the best reported to date. More significantly, films showing metallic conduction have been obtained over a much wider range of Mn concentrations (from 1.5% to 8%) than has been reported for films grown with As4. The improved properties of the films grown with As2 are related to the lower concentration of antisite defects at the low growth temperatures employed.Comment: 8 pages, accepted for publication in J. Crystal Growt

Bone, antler, tooth and horn technology and utilisation in prehistoric Scotland

This study is concerned with the technology and utilisation of skeletal hard tissue in prehistoric Scotland. The natural properties of skeletal tissues were considered, their reaction to particular methods of manufacture and utilisation were studied and a detailed examination made of material from a number of archaeological sites. Whilst the conclusions reached are site-specific, their usefulness as general statements on technology and utilisation are explored. There are two volumes - volume I containing the main text and volume II the catalogues and illustrations. Volume I begins with an introduction (Chapter 1). There then follow two sections. Section I starts by examining the approaches which were taken, identifies parallel studies, the range of techniques which were used in the study and the nature of the generalisations presented here (Chapter 2). The structure and properties of skeletal materials, and the determinant effect which these have on the techniques of manufacture, are discussed in Chapters 3 & 4. Section II comprises four case studies of large assemblages from settlement sites which date from the Mesolithic Period to the Iron Age - the site of Risga, Loch Sunart, Ardnamurchan (Mesolithic, Chapter 5); Skara Brae, Orkney (Neolithic, Chapter 6); Midhowe in Rousay, Orkney and Cnoc Sligeach at Sollas, North Uist (both Iron Age, Chapters 7 & 8). In each study the site and its excavation are discussed. All the objects from the sites were examined afresh and those from animals sources analysed in terms of skeletal origin, techniques of manufacture, object classification and distribution on site. Volume I concludes with Chapter 9 in which the results are summarised and the general applicability of the results is discussed. Volume II contains simplified object catalogues for each site which are intended as a concordance to enable the individual objects studied to be identified by others. Illustrations are given of representative objects within the categories. For ease of reference volume II also contains the bibliography and all the other illustrations for the study

An investigation of the neuropharmacological and behavioural effects of fenamate and other NSAIDs.

Recent evidence has indicated that NSAIDs might have direct effects on CNS tissue in addition to their classical inhibitory action on COX enzymes. This thesis addresses this hypothesis using electrophysiological and behavioural techniques. The effects of fenamate and other NSAIDs on native neuronal GABA(_A), 5-HT(_3), nicotinic ACh, P2x and strychinine-sensitive glycine receptors, expressed on isolated vagus or optic nerves, was investigated using an extra-cellular recording technique. The fenamate NSAID, mefenamic acid (MFA) potentiated GABA (10µM)- evoked responses in the vagus nerve. Application of MFA also resulted in non-competitive inhibition of 5-HT-and a,βMeATP- evoked responses. Non-competitive like inhibition was also observed with flufenamic acid on DMPP- and a,βMeATP- evoked responses and with meclofenamic acid on GABA- evoked responses. Non-fenamate NSAIDs, including aspirin, did not significantly modulate the GABA(_A), 5-HT(_3), nicotinic ACh, P2x or glycine receptors. The cognitive and behavioural effects of fenamates and other NASIDs were then investigated. MFA (5-20mg/kg) caused a significant dose- and time-dependent enhancement in the non-spatial object discrimination working memory task when compared to saline controls. The enhancement observed with MFA was greater than that of the cognitive enhancer piracetam. This enhancement was not due to a change in non-mnemonic processes such as arousal, anxiety or locomotion. MFA also enhanced rats' performance in the spatial object location working memory task. The fenamate NSAID, meclofenamic acid (20mg/kg) mimicked the effect of MFA, but the non-fenamate NSAIDs aspirin and ibuprofen, did not enhance object discrimination indicating that these cognitive effects are not via inhibition of COX. The GABA(_A) receptor modulators diazepam, bicuculline and loreclezole, did not replicate the effect of MFA on object discrimination, suggesting that its effects do not depend entirely on the GABAa receptor. Scopolamine (0.25-lmg/kg) significantly impaired object discrimination in a dose-dependent manner. This action could be fully reversed by co-treatment with MFA (20mg/kg).In the T-maze task, MFA (20mg/kg) decreased the number of arm entry errors and days taken to reach criterion. The number of arm entry errors made when a 5-minute intra-trial interval was introduced was also significantly reduced by MFA compared with saline treated animals. In the radial maze, MFA (20mg/kg) did not decrease the number of never baited arm entries to reach criterion. However MFA did significantly reduce the number of re-entry errors to baited arms, compared to controls, when an intra-trial delay (10-30 sees) was introduced. These results support the hypothesis that MFA enhances spatial working memory and that these effects are not task-specific. Overall, the data in this thesis show that fenamate NSAIDs can directly modulate native neuronal ligand-gated ion channels and that MFA can enhance working memory in normal and scopolamine-impaired rats. These results suggest additional pharmacological potential for certain fenamate NSAIDs

Reorienting finance towards energy efficiency: the case of UK housing

This paper examines the challenges associated with stimulating large-scale investment in energy efficiency and demand management measures, using residential energy efficiency improving retrofits in the UK as a case study. We consider how issues of energy policy, consumer choice and financial systems intersect, drawing on recent literature including energy policy documents and research reports, and on interviews with stakeholders from the finance sector, energy efficiency practitioners and more. We suggest that following the withdrawal of the Green Deal, there is a need to reconsider the framing of policy for household energy efficiency improvements, and examine three potential aspects of a new framing: energy efficiency as infrastructure; new business and financing models for energy efficiency provision; and decentralised financing institutions for energy efficiency investment. This would require a long-term commitment from government on energy efficiency, and a need to ensure that projects are attractive and investable from both householders and investors’ perspectives. We conclude that there are important roles for government in any large scale initiative for energy efficient retrofitting of UK homes, even if the mechanisms are market based. These includes signalling long-term policy consistency and reducing risks for financial investment, and intermediating between finance and energy efficiency projects

Two-Dimensional, Pyrazine-Based Nonlinear Optical Chromophores with Ruthenium(II) Ammine Electron Donors

Six new nonlinear optical (NLO) chromophores with pyrazinyl-pyridinium electron acceptors have been synthesized by complexing a known pro-ligand with electron donating {Ru^(II)(NH_3)_5}^(2+) or trans-{Ru^(II)(NH_3)_4(py)}^(2+) (py = pyridine) centers. These cationic complexes have been characterized as their PF_6^− salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. The visible d → π* metal-to-ligand charge-transfer (MLCT) absorptions gain intensity on increasing the number of Ru^(II) centers from one to two, but remain at constant energy. One or two Ru^(III/II) redox processes are observed which are reversible, quasi-reversible, or irreversible, while all of the ligand-based reductions are irreversible. Molecular first hyperpolarizabilities β have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and depolarization studies show that the NLO responses of the symmetric species are strongly two-dimensional (2D) in character, with dominant “off-diagonal” β_(zyy) components. Stark (electroabsorption) spectroscopic measurements on the MLCT bands also allow the indirect determination of estimated static first hyperpolarizabilities β_0. Both the HRS and the Stark-derived β_0 values increase on moving from mono- to bimetallic complexes, and substantial enhancements in NLO response are achieved when compared with one-dimensional (1D) and 2D monometallic Ru^(II) ammine complexes reported previously

Comparing innovation systems for solar photovoltaics in the United Kingdom and in China

Innovation in renewable energy sources (RES), such as solar photovoltaics (PV), can play an important part in CO2 reductions for climate change mitigation, as well as contributing to economic development. With a production capacity growing by more than 70% per year over the last 7 years, China is rapidly emerging as an important player in the global PV market, with significant levels of exports to Western European countries. The country's low labour cost combined with the potentially huge internal market should enable it to contribute to technology learning processes, driving down costs and increasing market diffusion. By comparison, though the UK aims to show global leadership in climate change policy, e.g. by setting a legally binding target to reduce CO2 emissions by 60% by 2050, it has been slow in developing either production capacity or markets for PV technology. By adopting a national innovation systems framework of analysis, the paper identifies the different technological and institutional actors and relations of the innovation systems for PV in the UK and in China, and assesses the extent to which these are likely to encourage or constrain the technological development and the market diffusion of this technology in the two countries. This novel effort to compare and contrast the innovation systems in the two countries combines information collected in both the UK and China and interviews with a sample of key actors in the PV sector. The comparison of the two countries’ innovation systems both unveils striking differences from which valuable policy lessons can be derived for the management of innovation in the energy sector and helps understanding of how such innovation could contribute to economic development

Anisotropic excitation spectra of GaAs/AlGaAs quantum wells grown on vicinal plane substrates

We report measurements of the photoluminescence excitation spectra of a series of GaAs/AlGaAs quantum well samples grown on vicinal plane substrates with differing off‐cut angles. When the plane of polarization of the exciting light is changed we have observed a clear variation in the ratio of the strength of the n=1 light and heavy hole exciton transitions in samples grown on vicinal plane substrates. This behavior is attributed to anisotropic scattering at steps in the heterointerface

Reconciling qualitative storylines and quantitative descriptions: an iterative approach

Energy system transition research has been experimenting with the integration of qualitative and quantitative analysis due to the increased articulation it provides. Current approaches tend to be heavily biased by qualitative or quantitative methodologies, and more often are aimed toward a single academic discipline. This paper proposes an interdisciplinary methodology for the elaboration of energy system socio-technical scenarios, applied here to the low carbon transition of the UK. An iterative approach was used to produce quantitative descriptions of the UK's energy transition out to 2050, building on qualitative storylines or narratives that had been developed through the formal application of a transition pathways approach. The combination of the qualitative and quantitative analysis in this way subsequently formed the cornerstone of wider interdisciplinary research, helping to harmonise assumptions, and facilitating ‘whole systems’ thinking. The methodology pulls on niche expertise of contributors to map and investigate the governance and technological landscape of a system change. Initial inconsistencies were found between energy supply and demand and addressed, the treatment of gas generation, capacity factors, total installed generating capacity and installation rates of renewables employed. Knowledge gaps relating to the operation of combined heat and power, sources of waste heat and future fuel sources were also investigated. Adopting the methodological approach to integrate qualitative and quantitative analysis resulted in a far more comprehensive elaboration than previously, providing a stronger basis for wider research, and for deducing more robust insights for decision-making. It is asserted that this formal process helps build robust future scenarios not only for socio political storylines but also for the quantification of any qualitative storyline