Optimal Extraction of Fibre Optic Spectroscopy

We report an optimal extraction methodology, for the reduction of multi-object fibre spectroscopy data, operating in the regime of tightly packed (and hence significantly overlapping) fibre profiles. The routine minimises crosstalk between adjacent fibres and statistically weights the extraction to reduce noise. As an example of the process we use simulations of the numerous modes of operation of the AAOmega fibre spectrograph and observational data from the SPIRAL Integral Field Unit at the Anglo-Australian Telescope.Comment: Accepted for publication in PAS

Benefit Transfer: Choice Experiment Results

Benefit transfer entails using estimates of non-market values derived at one site as approximations to benefits at other sites. The method finds favour because it can be applied quickly and cheaply, however the validity of benefit transfer is frequently questioned. Published studies generally indicate that errors from the approach can be extremely large and could result in significant resource misallocations. Assessing the validity of benefit transfer is complicated by differences in the nature of study and policy sites, the changes being valued, valuation methods, time of study, availability of substitutes and complements, and demographic, social and cultural differences. A choice experiment was used to evaluate the transferability of benefit estimates for identical goods between two different populations. The study design allowed most of the confounding factors to be controlled, so provides a strong test of benefit transfer validity. Several different tests were applied to evaluate benefit transfer validity, with conflicting results. The paper investigates the merits of the alternative tests and concludes that utility functions were different for the two populations.Choice model, Choice experiment, Benefit transfer, Mitigation, Agricultural and Food Policy, Environmental Economics and Policy, Financial Economics, Land Economics/Use, Research Methods/ Statistical Methods, Resource /Energy Economics and Policy,

Slices of the Kerr ergosurface

The intrinsic geometry of the Kerr ergosurface on constant Boyer-Lindquist (BL), Kerr, and Doran time slices is characterized. Unlike the BL slice, which had been previously studied, the other slices (i) do not have conical singularities at the poles (except the Doran slice in the extremal limit), (ii) have finite polar circumference in the extremal limit, and (iii) for sufficiently large spin parameter fail to be isometrically embeddable as a surface of revolution above some latitude. The Doran slice develops an embeddable polar cap for spin parameters greater than about 0.96.Comment: 13 pages, 6 figures; v.2: minor editing for clarification, references added, typos fixed, version published in Classical and Quantum Gravit

Doing gender and development: understanding empowerment and local gender relations

A major dilemma in Gender and Development (GAD) work is why it is that sometimes women may feel better off colluding with gendered structures that ensure their continued subordination rather than seeking approaches that will allow them to break free of this. Kandiyoti (1988 Gender and Society 2 274-90) has identified this apparent collusion as 'patriarchal bargains', which offer women greater advantages than they perceive can be achieved by challenging the prevailing order. Such women are therefore reluctant to engage in empowering activities that may challenge their gendered bargain. This paper explains this dilemma in the context of GAD work undertaken with Bedouin women in Southern Egypt

Spatially and Temporally Explicit Energy System Modelling to Support the Transition to a Low Carbon Energy Infrastructure – Case Study for Wind Energy in the UK

Renewable energy sources and electricity demand vary with time and space and the energy system is constrained by the location of the current infrastructure in place. The transitioning to a low carbon energy society can be facilitated by combining long term planning of infrastructure with taking spatial and temporal characteristics of the energy system into account. There is a lack of studies addressing this systemic view. We soft-link two models in order to analyse long term investment decisions in generation, transmission and storage capacities and the effects of short-term fluctuation of renewable supply: The national energy system model UKTM (UK TIMES model) and a dispatch model. The modelling approach combines the benefits of two models: an energy system model to analyse decarbonisation pathways and a power dispatch model that can evaluate the technical feasibility of those pathways and the impact of intermittent renewable energy sources on the power market. Results give us the technical feasibility of the UKTM solution from 2010 until 2050. This allows us to determine lower bounds of flexible elements and feeding them back in an iterative process (e.g. storage, demand side control, balancing). We apply the methodology to study the long-term investments of wind infrastructure in the United Kingdom

Visualising gas heating from an RF plasma loudspeaker

In an electro-acoustic transduction mechanism, an ac modulation (here in the audio frequency range) of the electric field in an atmospheric pressure air plasma gives rise to a rapid increase in the gas temperature and dimensions of the gas volume. As in natural lightning, the rapid expansion in the ionised column though the air produces external pressure variations at the modulation frequency.  \ud Spatial and temporal measurement of the gas temperature can identify the nature of the thermal expansion and provide a direct approach to understanding its relationship to the sound pressure wave that is generated. However, the established method through spectroscopic measurement of rotational line emission from nitrogen molecules is limited to the main current channel where relaxation and subsequent optical emission of the excited nitrogen molecules occurs. The wider picture is revealed through the use of the Schlieren method where the refractive index gradients caused by gas heating in the plasma are imaged

Efficient design for willingness to pay in choice experiments: evidence from the field

Efficient experimental designs offer the potential to reduce confidence intervals for parameters of interest in choice models, or to reduce required sample sizes. C-efficiency recognizes the salience of willingness to pay estimates rather than utility function parameters. This study reports on a choice model application that incorporated updated statistical designs based on initial responses in order to maximize C-efficiency. The revised design delivered significant improvements.experimental design, choice experiment, efficiency, Environmental Economics and Policy, Research Methods/ Statistical Methods,