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During the middle and late second century, aristocratic Roman society underwent a transition: from the apparently orderly and settled imperial court of Marcus, through the reign of Commodus, punctuated by plots and purges, to the brief imperial tenure of Pertinax, riven by dynastic scheming. This thesis uses a prosopographical study of the career of Pertinax, who was born the son of a freedman and rose to become emperor in 193, to examine the shifting socio-political structures of this imperial society. The goal of the thesis is twofold: firstly, to gain a deeper understanding of the process and consequences of the transition of aristocratic society from 160-93; secondly, to emphasise the career of Pertinax as representative of these changes. Apart from prosopography, the methodology revolves predominantly on the analyses of literary sources - textual and epigraphic - created within an aristocratic Roman context, although where necessary these sources are supplemented with numismatic and archaeological evidence. Such a methodology allows us to examine the structural characteristics of imperial society and enables the study of its responses and developments throughout the numerous crises and upheavals, internal and external, of the middle and late second century. Prosopography provides the central evidentiary framework for the thesis. The career of Pertinax, which took place under the emperors Marcus Aurelius, Lucius Verus, and Commodus (as well as his own brief three month reign), provides fertile ground for the prosopographical study of an imperial society in transition. His career has typically been treated in a supplemental or fragmentary fashion, and numerous problems deserve systemic treatment on historical and historiographical grounds. These problems in turn provide the cases studies within the thesis for discussions of the changing nature of imperial society and its relationship to the institution and person of the emperor.

Magma mixing and mingling processes are widely recognised in the textures and geochemistry of igneous rocks. A common feature of rocks from mixed magmas is the presence of magmatic xenocrysts, crystals that have been mechanically transferred from a magma of a different composition. This thesis investigates both the physical mechanisms of crystal transfer, and the physio-chemical response of crystals to the change in temperature and melt composition it experiences. Analysis of xenocrysts in lavas from Unzen, Japan, demonstrates how an understanding of these processes can inform interpretations from textural and geochemical analyses. Experimental and numerical studies investigate the fundamental process of low Reynolds number gravitational settling of spheres through fluid interfaces as an analogue for crystal transfer. Experiments reveal the dominant control on the volume of fluid entrained during the transfer is shown to be the viscosity ratio, with significant entrainment occurring when the viscosity of the upper fluid is comparable or greater than that of the lower. However, boundary integral method simulations suggest the density contrasts between crystals and melt are too small for gravitational settling to account for crystal transfer between magmas. Plagioclase and quartz xenocrysts in a mafic enclave erupted at 4-5 ka from Unzen are analysed to determine the effect of transfer on their textures and chemistry. Plagioclase xenocrysts contain resorbed interiors, surrounded by Fe-rich rims of clear growth, whilst quartz are rounded, heavily embayed and surrounded by coronas of hornblende, glass and vesicles. 50% of plagioclase phenocrysts in the host magma have signatures of previous resorption events, suggesting repeated episodes of injection and crystal recycling in the magma storage system prior to eruption. Erupted lavas from 1792 and 1991-1995 suggest such processes have been occurring for the last 300 years, but this study suggests they have possibly been ongoing for at least 5000 years.

The increase in obesity prevalence over the past 20 years has become an international public health crisis. The lack of timely, accurate information led to a six year delay in recognising the obesity epidemic in UK children, despite height and weight measurements of children at various ages being routinely collected for many years. The chain of data, analytical methods and public health expertise for child obesity analysis and public health reporting is fragmented. This fragmented workflow leads to delayed or lost intelligence and public health decision-makers have little control of the underlying systems to produce the intelligence they require. This research addressed the specific need for a public health intelligence workflow system to profile child obesity. A web based software system known as Obesity Atlas was developed with and for the Greater Manchester Primary Care Trusts. In both requirements analysis and evaluation it was found that the combination of statistics, charts, and geo-visualisation are more informative if chained together in a workflow than used separately. In order to inform more public health decisions with current resources, there is a need for a common framework for finding, sharing, enacting, and re-using public health intelligence workflows.

Spatial datasets contain information relating to the locations of incidents of a disease or other phenomena. Appropriate analysis of such datasets can reveal information about the distribution of cases of the phenomena. Areas that contain higher than expected incidence of the phenomena, given the background population, are of particular interest. Such clusters of cases may be affected by external factors. By analysing the locations of potential influences, it may be possible to establish whether a cause and effect relationship is present within the dataset. This thesis describes research that has led to the development and application of cluster detection and feature selection techniques in order to determine whether causal relationships are present within generic spatial datasets. The techniques are described and demonstrated, and their effectiveness established by testing them using synthetic datasets. The techniques are then applied to a dataset supplied by the Welsh Leukaemia Registry that details all cases of leukaemia diagnosed in Wales between 1990 and 2000. Cluster detection techniques can be used to provide information about case distribution. A novel technique, CLAP, has been developed that scans the study region and identifies the statistical significance of the levels of incidence in specific areas. Feature selection techniques can be used to identify the extent to which a selection of inputs impact upon a given output. Results from CLAP are combined with details of the locations of potential causal factors, in the form of a numerical dataset that can be analysed using feature selection techniques. Established techniques and a newly developed technique are used for the analysis. Results from such analysis allow conclusions to be drawn as to whether geographical causal relationships are apparent.

The application of radiation detector materials, capable of operating at room temperature, has been studied. The advantage of such materials is that they do not need to be cooled to reduce thermally generated leakage currents. Therefore, systems utilising these detectors can be smaller and more portable than ones containing HpGe and Si(Li) detectors which need to be cooled using liquid nitrogen to reduce leakage current. Three materials, silicon, cadmium telluride and mercuric iodide, have been investigated. The silicon photodiode showed very good energy resolution down to photon energies of 13.4keV, but its low detection efficiency restricts its use to energies below 200keV for direct detection. Cadmium telluride produced energy spectra with worse energy resolution, due mainly to charge collection, leakage current and fabrication. But, cadmium telluride was able to produce spectra up to 661.6keV with reasonable efficiency and resolution. Mercuric iodide produced spectra with energy resolution on a par with the silicon photodiode but with a higher detection efficiency. Mercuric iodide crystals have been produced at Surrey using the polymer assisted transport growth method. A large crystal with dimensions exceeding 1cm3 has also been produced. Due to problems with application of electrical contacts no useful spectra were obtained with these devices. The importance of the polymer in the starting material was investigated. The addition of polyethylene was found to favour the growth of platelets. The size of the platelets was also found to increase with increasing proportion of polymer in the stalling mix. A computer simulation enabling the performance of semiconductor radiation detector materials to be predicted is also presented. The model follows processes from photon interactions in the detector through to charge collection. Energy spectra may be produced from the output of this model and energy resolution and detection efficiency may be analysed as a function of detector thickness, applied bias and photon energy. This model could be used to optimise performance of radiation detectors.

Chloroplasts are ancient organelles that house photosynthesis in all green plants. Most proteins required for chloroplast function are imported into the organelles from the cytosol via the coordinate action of two translocons - the TOC and TIC complexes. A recent forward genetic screen revealed that the TOC complex is conditionally targeted for degradation via the action of SP1, a chloroplast-resident E3 ubiquitin ligase. SP1 functions within the newly-described CHLORAD pathway - a pathway for the ubiquitination, membrane extraction, and degradation of chloroplast proteins. The CHLORAD pathway is activated by stress and developmental cues, but the mechanistic basis of this regulation is poorly understood. In this thesis, a genetic and functional link between chloroplast protein import, CHLORAD, and the SUMO system is described. Arabidopsis mutants representing most components of the SUMO pathway are shown to suppress the pale phenotype of TOC complex mutant ppi1 with respect to chlorophyll accumulation. This suppression is also linked to increases in the accumulation of TOC proteins and enhanced chloroplast development. Conversely, the overexpression of SUMO1 or SUMO3 accentuates the ppi1 phenotype. Protein/protein interaction studies demonstrate that key components of the SUMO system (the E2 SUMO conjugating enzyme, two E3 SUMO ligases) physically interact with TOC proteins at the chloroplast outer envelope, and SUMOylation assays indicate that TOC proteins are directly SUMOylated. This work is complemented by a forward genetic screen for additional regulators of the TOC complex. In this screen, a pale TOC complex mutant, ppi2-3 is chemically mutagenized and 28 viable suppressor mutants are identified, named, and characterised. Together, these two projects provide new insights into the regulation of chloroplast protein import and, perhaps, the CHLORAD pathway.

Plastids are an important group of plant organelles, and depending on their morphology and functions, plastids exist in different forms and have the ability to convert between these forms. Development of plastids depends on the import of preproteins from the cytosol through outer and inner envelope chloroplast membranes, TOC and TIC complexes. The TOC complex incorporates different client-specific receptors and these contact preproteins with differing specificity, controlling the proteomic composition, development fate, and functions of the plastid. The first identified chloroplast-localized E3 ligase of the plastid outer membrane, SP1, is a regulator of the TOC translocon. In Arabidopsis, SP1 functions to attach ubiquitin to TOC proteins for ubiquitin-proteasome system (UPS)-mediated degradation, controlling the proteomic composition of plastids. In this thesis, detail analyses of the role of SP1 were conducted in tomato and wheat plants with altered SP1 expression (both overexpression [OEX] and RNA interference-based knockdown, in each case), to further assess the extent to which its functions are conserved in different species, and to elucidate possible practical applications in crops. In accordance with previous findings in Arabidopsis, SP1 OEX promoted abiotic stress tolerance and leaf senescence in both tomato and wheat. SP1 was found to influence the abiotic stress tolerance where its particular effect on the plants' responses to stress conditions was dependent on the developmental stage at which the exposure to stress occurred. SP1 RNAi delayed senescence under dark-induced and natural senescence conditions, and influenced yield in 'stay-green' SP1 RNAi wheat plants. SP1-mediated changes in tomato were found to alter the duration of fruit ripening, without affecting the size and firmness of the fully ripened fruit. Specifically, SP1 OEX fruit showed accelerated ripening, and SP1 RNAi fruit showed delayed ripening. Finally, the role of SPL2, a homologue of SP1, in tomato was investigated. The RNAi-mediated knockdown of SPL2 expression in tomato plants had similar effects on fruit ripening, leaf senescence, and abiotic stress tolerance to SP1 RNAi, even though the transcript abundance of tomato SPL2 in various plant tissues was much less than that of tomato SP1.

Chloroplasts are photosynthetic organelles in plants, and their functions are dependent on the import of thousands of proteins from the cytosol. These proteins engage with the translocon at the outer envelope membrane of chloroplasts (TOC), which acts as a selective conduit for the first stage of their import across the double membrane system. Mutations affecting the TOC components, such as plastid protein import 1 (ppi1) of Arabidopsis thaliana, can hinder the efficiency of import activity, and have consequences for organelle development. A screen for second-site suppressors of ppi1 identified a novel regulator of the TOC machinery called suppressor of ppi1 locus 1 (sp1). Two homologues of SP1, SP1-Like1 (SPL1) and -2 (SPL2), were identified in Arabidopsis based on sequence similarity. In this thesis, the function of these two homologues was characterized in relation to chloroplast biogenesis. While spl1 null mutations had no profound effect on the ppi1 mutant, knockdown of SPL2 exhibited a weak suppression phenotype that could be attributed to a recovery in protein import activity and chloroplast development. Immunoprecipitation results revealed a strong physical interaction between SPL2 and the TOC components. Manipulation of SPL2 gene expression caused phenotypes reminiscent of those caused by SP1 manipulation during the dynamic process of leaf senescence. In vitro ubiquitination analysis showed that SPL1, unlike SP1 and SPL2, does not possess E3 ligase activity, but rather has an inhibitory effect on SP1 activity via an unknown mechanism. Accordingly, spl1 null mutants displayed an opposite phenotype to sp1 mutants during leaf senescence (i.e., senescence was accelerated), suggesting that SPL1 may be a negative regulator of SP1. However, SPL1 is only observed within the Brassicaceae family, which raises questions about the wider relevance of its role across different species. Lastly, a screen for new sp1 enhancer mutants was conducted, and this identified three putative sp1 enhanced chlorophyll (spec) mutants that display elevated chlorophyll levels, intermediate between those of sp1 ppi1 and wild-type plants. Mapping of the spec mutations by whole-genome sequencing identified several gene candidates in each case, which will require further analysis in order to conclude final identification of the causal locus in each case. Overall, the results revealed new regulatory mechanisms governing the chloroplast protein import machinery.

Plastids are a hub of biosynthetic activity, and in different tissues they take on specialised functions and develop into complex structures (e.g., chloroplasts in leaves). The structural and metabolic diversity and dynamism of plastids is dependent upon proteins imported from the cytosol. At the outer-envelope membrane of plastids, such proteins are transported by the translocon at the outer-envelope membrane of chloroplasts (TOC), comprising a protein-conducting channel and receptor proteins. Mutations affecting these TOC proteins cause profound effects to plastid development. To understand more about plastid development and the regulation of the TOC machinery, a screen for second-site suppressors of a mutant lacking the Toc33 receptor, called plastid protein import 1 (ppi1), was previously conducted. In this thesis, the resulting suppressor of ppi1 locus 2 (sp2) mutants were characterised. The SP2 genetic locus was identified, and it was found to affect the development of chloroplasts in a mechanism related to protein import. This was determined to involve a strong negative regulatory effect on the abundance of the TOC proteins, which was reminiscent of the effect of the SP1 locus. SP1 is an E3 ubiquitin ligase that triggers proteasomal degradation of TOC proteins. For this to occur, it is thought that TOC proteins require a mechanism of extraction from the chloroplast membrane, in a pathway that would require a retrotranslocon, as is the case for the degradation of endoplasmic reticulum (ER) proteins by the ER-associated degradation (ERAD) system. As a relative of the Omp85 superfamily of protein transporters, SP2 is here proposed to fulfil the role of retrotranslocon in a hypothesised chloroplast-associated degradation system (ChlorAD). Genetic interaction data suggest that SP1 and SP2 act in a common pathway, while co-immunoprecipitation and in vitro pulldown results reveal a strong physical interaction between SP1 and SP2, as well as an interaction between SP2 and the ERAD-associated ATPase, CDC48. Overall, evidence presented here strongly supports the proposed ChlorAD mechanism.

The ability to alert/warn all segments of a community regarding the potential of severe weather is essential for the safety and well-being of those affected. Such alerts/warnings must be tailored to accommodate all facets of the diverse population within communities. Essential to this is the construction and conveyance of a clear, concise message that identifies and encourages adequate, appropriate protective actions to be taken. This can be accomplished through the concerted efforts of communities to improve levels of preparedness with public education and outreach programmes, via collaboration of broadcast media, broadcast meteorologists and emergency management. Electronic web-based surveys were made available to the general public, to broadcast media and to emergency management personnel to collect quantitative data related to severe weather warning systems information. Qualitative data was obtained through the convening of six focus groups (three general public groups, one broadcast media group, one meteorology group and one emergency management group). The key results of this research indicated the need for: a broader community outreach and education programme related to severe weather; a comprehensive severe weather exercise programme; improvements in the NOAA Weather Radio and the Emergency Alert System (EAS); standardized back-up generators for broadcast radio; enhancement of the existing power grid; along with the need for increased capabilities of broadcast media and emergency management to alert and communicate with the non-English speaking and hard-of-hearing communities. In conclusion, this research indicated a continuing need for community education related to severe weather. In addition, there is also a need for standardization of initial disaster messages, along with conformity in the display of specific graphics and colours by television meteorologists.

Chloroplasts are photosynthetic organelles in plant and algal cells that capture sunlight energy to form energy-rich molecules that are the basis for almost all life. Chloroplast development requires more than 3000 different proteins, most of which are encoded by nuclear DNA. Thus, chloroplasts must import most of their proteins from the cytosol. They are surrounded by a double membrane called the envelope. Embedded in the envelope are the TOC and TIC complexes (translocon at the outer and inner envelope membrane of the chloroplast, respectively), which mediate protein import into the organelle. Several components of the TOC and TIC complexes have been identified. One example is the receptor Toc159, which in the model plant Arabidopsis thaliana has four isoforms: atToc159, atToc132, atToc120 and atToc90. It is known that atToc159 supports accumulation of photosynthetic proteins, while atToc132 and atToc120 support the import of non-photosynthetic, housekeeping proteins. However, the role of atToc90 remains uncertain. I investigated the function of atToc90 genetically by studying a series of Arabidopsis toc90 double and triple mutants, and by overexpressing atToc90 in mutants lacking other receptor isoforms. This work suggested limited functional redundancy between atToc90 and other TOC receptors (most notably, atToc159). By tagging TOC receptors known to act in each of the photosynthetic and non-photosynthetic import pathways, I was able to purify different TOC complexes from transgenic plants using tandem affinity purification (TAP). This indicated that atToc90 is present promiscuously in both atToc159- and atToc132/120-containing TOC complexes. Publicly available Affymetrix microarray data suggested a role for atToc90 during senescence. Thus, I investigated whether toc90 knockout mutants display any differences from wild type regarding leaf senescence. Indeed, some defects were observed, suggesting a role for atToc90 in the biochemical changes that occur in chloroplasts during leaf senescence.

This thesis documents the research which has led to the design of a number of techniques aiming to improve the performance of content-based image retrieval (CBIR) systems in wavelets domain using texture analysis. Attention was drawn on CBIR in transform domain and in particular wavelets because of the excellent characteristics for compression and texture extraction applications and the wide adoption in both the research community and the industry. The issue of performance is addressed in terms of accuracy and speed. The rationale for this research builds upon the conclusion that CBIR has not yet reached a good performance balance of accuracy, efficiency and speed for wide adoption in practical applications. The issue of bridging the sensory gap, which is defined as "[the difference] between the object in the real world and the information in a (computational) description derived from a recording of that scene." has yet to be resolved. Furthermore, speed improvement remains an uncharted territory as is feature extraction directly from the bitstream of compressed images. To address the above requirements the first part of this work introduces three techniques designed to jointly address the issue of accuracy and processing cost of texture characterization in wavelets domain. The second part introduces a new model for mapping the wavelet coefficients of an orthogonal wavelet transformation to a circular locus. The model is applied in order to design a novel rotation-invariant texture descriptor. All of the aforementioned techniques are also designed to bridge the gap between texture-based image retrieval and image compression by using appropriate compatible design parameters. The final part introduces three techniques for improving the speed of a CBIR query through more efficient calculation of the Li-distance, when it is used as an image similarity metric. The contributions conclude with a novel technique which, in conjunction with a widely adopted wavelet-based compression algorithm, extracts texture information directly from the compressed bit-stream for speed and storage requirements savings. The experimental findings indicate that the proposed techniques form a solid groundwork which can be extended to practical applications.

A complex simulation model, MAESTRO, has been developed and validated against field measurements in plantation in both Scotland and Australia. It has been shown that MAESTRO can reasonably predict the daily course of PAR (photosynetically active radiation) transmittance at points below the canopies of radiata pine and Sitka spruce plantations. 1. Four structural properties of the Sitka spruce tree crown have been identified and evaluation in relation to PAR absorption, photosynthesis and transpiration. They are : the total amount leaves within the tree crown, leaf inclination angle distribution and crown shape. The total area of leaves and their spatial distribution within the tree crown are ranked as the two most significant properties. 2. Among the four different structural properties studied, crown shape is least important for PAR absorption, photosynthesis and transpiration. For the Sitka spruce stand studied, transpiration was most sensitive to the total area of leaves within the tree crown, whereas photosynthesis can be significantly affected by the leaf angle distribution. The influence of crown structure also depends on the beam fraction, radiance of diffuse radiation, incident angle of beam radiation. 3. Application of MAESTRO has shown the importance of the spatial distribution of leaf area density distribution and the age structure of the leaf population within a dense Sitka spruce canopy for the radiation regime and for photosynthesis. It has been found that the non-uniform canopy structure. The actual leaf age structure within a dense Sitka spruce canopy has been compared with the leaf age structure that is optimal for maximising the PAR use efficiency of the canopy and it has been found that PAR use efficiencies of both canopies are very close. 4. The non-uniform structure of a tree crown has been described using a two-dimensional leaf area density distribution function within the tree crown. It was found that the spatial distribution of leaf area density and the age structure of the leaf population within the crowns of radiata pine trees were significantly affected by water stress and nutrient deficiency during the growing season. 5. The radiance distribution of diffuse radiation from the sky and the beam fraction of the incident radiation also affect PAR absorption, photosynthesis and transpiration by altering the uniformity of the radiation regime within the tree crown. The light use efficiency of the canopy decreases with the increase in beam fraction. 6. The stomatal and photosynthetic properties of the shoots of Sitka spruce were measure in an open path gas exchange system to parameterize a biochemical photosynthesis model. It was found that co-limitation of photosynthesis plays an important role in the PAR responses of both an isolated shoot and of a canopy. It was shown that co-limitation of canopy photosynthesis enables the canopy to use a high flux density of incident PAR efficiently. 7. The dry matter production of the above-ground biomass of a Sitka spruce stand was studied in relation to PAR absorption to test the Monteith hypothesis. It was found the relationship between the above-ground dry matter production and PAR absorption is approximately linear. The slope of this linear relationship is affected by nitrogen fertilization, but not by thinning for the Sitka spruce stands studied. Crown structure plays an important role in the processes or radiation transfer, photosynthesis and transpiration within the tree crown. Detailed descriptions of the important structural properties of the tree crown are necessary for adequate understanding of canopy processes, such as photosynthesis. Co-limitation of crown photosynthesis, determined by the structure of all the tree crowns in the stand, results in an efficient use of the incident solar radiation by the trees in the stand. Photosynthesis of the forest canopy is roughly proportional to the incident PAR. PAR absorption is the primary determinant of dry matter production of the above-ground biomass for the Sitka spruce stand studied.