Application of Polychlorinated Biphenyl Signatures for Environmental Fingerprinting

Chapter 2 has been produced based on the original research of Megson et al., (2013b), which was published in Science of the Total Environment (DOI: http://dx.doi.org/10.1016/j.scitotenv.2013.04.082) (presented as Appendix A). Chapter 3 is based in part on the original research of Megson et al., (2013a), which was published in the Journal of Chromatography A (DOI: http://dx.doi.org/10.1016/j.chroma.2013.10.016) (presented as Appendix B). Chapter 5 has been produced based in part on the original research of Megson et al. (2014), which was published in Chemosphere (DOI: http://dx.doi.org/10.1016/j.chemosphere.2014.04.061) (presented as Appendix D).Polychlorinated Biphenyls (PCBs) are a group of 209 ‘man-made’ chlorinated organic compounds that were widely used in the 20th century for a variety of industrial uses. PCBs were first commercially produced in the 1929 and were manufactured until the 1980s when their use was phased out due to environmental and human health risks. However, due to their widespread use and persistence they are ubiquitous in the environment and remain a contaminant of concern. The structural properties that determine the persistence of PCBs in humans were therefore elucidated by statistical analysis of data from the National Health and Nutrition Examination Survey (NHANES). PCBs with chlorine bonding in the 2,5-and 2,3,6- positions (and 2- in di- and tri-chlorinated congeners) were rapidly biotransformed and so can be classed as episodic congeners whereas PCBs with chlorine bonding in the 2,3,4-, 2,4,5-, 3,4,5-, and 2,3,4,5- positions were more resistant to biotransformation and can therefore be classed as steady state congeners. A fundamental requirement of using PCB signatures for environmental fingerprinting is an effective analytical method capable of producing high resolution signatures from biological samples. An extraction and clean-up method was developed that was successfully applied to different biological matrices (blood and tissues). A two dimensional gas chromatography with time of flight mass spectrometry (GCxGC-ToFMS) method was designed and optimised to provide a congener specific method capable of identifying 200 out of the 209 PCBs, with detection limits in human serum in the range of 1 to 10 ng g-1 lipid. The extraction and detection methods were used to determine the source of PCB contamination and age date exposure in workers at a transformer dismantling plant. A total of 84 different PCB congeners were identified in the sera of 30 workers with concentrations of the 7 indicator PCBs ranging from 1.2 - 39 μg g-1 lipid. Analysis of PCB signatures was able to distinguish recent from prolonged exposure and also identified an additional source of inhalation exposure in a subgroup of workers. Analysis of 12 different tissue types obtained from the common guillemot (Uria aalge) suggested a high degree of perpetuation between the PCB signature in different tissue types. This shows that comparative assessments can be undertaken between animals using different tissue types and that small (1 g) samples of blood can be used as a non-lethal sampling technique. The regional provenance of 25 wrecked Leach’s storm petrels (Oceanodroma leucorhoa) was also determined using PCB signatures. Results from GCxGC-ToFMS analysis revealed distinctively different PCB signatures in birds from Canada and Europe. The findings reported in this thesis enhance our understanding of PCB signatures in the environment and show how they can be used effectively to age date and identify the source of exposure in humans and animals

Inverse scattering results for manifolds hyperbolic near infinity

We study the inverse resonance problem for conformally compact manifolds which are hyperbolic outside a compact set. Our results include compactness of isoresonant metrics in dimension two and of isophasal negatively curved metrics in dimension three. In dimensions four or higher we prove topological finiteness theorems under the negative curvature assumption.Comment: 25 pages. v3: Minor corrections, references adde

Lambeth LGBT Matters: The needs and experiences of lesbians, gay men, bisexual and trans men and women in Lambeth.

This report presents the findings of a study of the experiences of Lesbians, Gay men, Bisexual and Trans (LGBT) men and women who live, work and socialise in Lambeth. It presents the results of part of a larger study which included analysis of Lambeth’s policies and procedures, stakeholder interviews and staff focus groups. The full report can be found at our website. Here, we present the results of a self-completion quantitative survey of LGBT people who live, work or socialise in Lambeth (Chapter 2) and qualitative focus groups/interviews with LGBT residents of Lambeth (Chapter 3). Chapter 4 contains some conclusions and recommendations arising from this research. The study was commissioned by The London Borough of Lambeth (LBL) to provide the Council with information to improve services for these populations. LBL is the largest and possibly most diverse of inner London’s boroughs. Patterns of UK and international migration ensure that the LGBT population in London is far larger than elsewhere in the UK. Using Census (Office for National Statistics 2006) and other data (Mercer et al. 2004) we can estimate that Lambeth’s LGBT resident population is approximately 18-20,000 adults. This figure does not include people who come to Lambeth to work or socialise. Lambeth also hosts a substantial LGBT social and commercial scene with six Gay saunas / gyms, 12 LGBT social support agencies and at least 17 bars, clubs and cafes in the borough. Lambeth also contains several public areas where men meet for sex (parks, commons and public toilets)

Multi-agency training and the artist (Sharing our experience, Practitioner-led research 2008-2009; PLR0809/032)

The Multi-Agency Team Project approached issues of multi-agency training indirectly by using an artist as a catalyst in a group exercise examining movement and sound in relation to early childhood. The aim of the research was to run an experiential non-traditional training programme based on using an artist as a catalyst to promote inter-agency dialogue in one setting, Woodlands Park Nursery and Children’s Centre, and to analyse the findings. Eleven participants used this common experiential focus to frame collective research both as a focus group and as individual fieldworkers. The research demonstrated shared professional discourse but also collected judgements relevant to policy issues based on collaborative professional reflection triggered by the exercise. The findings are presented theoretically in terms of critical discourse analysis using the interpretation-supporting software ATLASti. We next take a further look at the role play exercise in which the group constituted itself as a ‘House of Commons Select Committee’ before summarizing what theoretical insights might be brought to bear and attempting to draw some provisional conclusions. Some evidence is presented suggesting there is a degree of tension and ambiguity between alterative models of multi-agency working

Adaptive Higher-order Spectral Estimators

Many applications involve estimation of a signal matrix from a noisy data matrix. In such cases, it has been observed that estimators that shrink or truncate the singular values of the data matrix perform well when the signal matrix has approximately low rank. In this article, we generalize this approach to the estimation of a tensor of parameters from noisy tensor data. We develop new classes of estimators that shrink or threshold the mode-specific singular values from the higher-order singular value decomposition. These classes of estimators are indexed by tuning parameters, which we adaptively choose from the data by minimizing Stein's unbiased risk estimate. In particular, this procedure provides a way to estimate the multilinear rank of the underlying signal tensor. Using simulation studies under a variety of conditions, we show that our estimators perform well when the mean tensor has approximately low multilinear rank, and perform competitively when the signal tensor does not have approximately low multilinear rank. We illustrate the use of these methods in an application to multivariate relational data.Comment: 29 pages, 3 figure

Simplicity of 2-graph algebras associated to Dynamical Systems

We give a combinatorial description of a family of 2-graphs which subsumes those described by Pask, Raeburn and Weaver. Each 2-graph $\Lambda$ we consider has an associated $C^*$-algebra, denoted $C^*(\Lambda)$, which is simple and purely infinite when $\Lambda$ is aperiodic. We give new, straightforward conditions which ensure that $\Lambda$ is aperiodic. These conditions are highly tractable as we only need to consider the finite set of vertices of $\Lambda$ in order to identify aperiodicity. In addition, the path space of each 2-graph can be realised as a two-dimensional dynamical system which we show must have zero entropy.Comment: 19 page