Affine Matching with Bounded Sensor Error: A Study of Geometric Hashing and Alignment

Affine transformations are often used in recognition systems, to approximate the effects of perspective projection. The underlying mathematics is for exact feature data, with no positional uncertainty. In practice, heuristics are added to handle uncertainty. We provide a precise analysis of affine point matching, obtaining an expression for the range of affine-invariant values consistent with bounded uncertainty. This analysis reveals that the range of affine-invariant values depends on the actual $x$-$y$-positions of the features, i.e. with uncertainty, affine representations are not invariant with respect to the Cartesian coordinate system. We analyze the effect of this on geometric hashing and alignment recognition methods.

Conversion as transformative experience: a sociological study of identity formation and transformation processes

This thesis contributes to the understanding of the processes involved in the formation and transformation of identities. It achieves this goal by establishing the critical importance of ‘background’ and ‘liminality’ in the shaping of identity. Drawing mainly from the work of cultural anthropology and philosophical hermeneutics a theoretical framework is constructed from which transformative experiences can be analysed. The particular experience at the heart of this study is the phenomenon of conversion and the dynamics involved in the construction of that process. Establishing the axial age as the horizon from which the process of conversion emerged will be the main theme of the first part of the study. Identifying the ‘birth’ of conversion allows a deeper understanding of the historical dynamics that make up the process. From these fundamental dynamics a theoretical framework is constructed in order to analyse the conversion process. Applying this theoretical framework to a number of case-studies will be the central focus of this study. The transformative experiences of Saint Augustine, the fourteenth century nun Margaret Ebner, the communist revolutionary Karl Marx and the literary figure of Arthur Koestler will provide the material onto which the theoretical framework can be applied. A synthesis of the Judaic religious and the Greek philosophical traditions will be the main findings for the shaping of Augustine’s conversion experience. The dissolution of political order coupled with the institutionalisation of the conversion process will illuminate the mystical experiences of Margaret Ebner at a time when empathetic conversion reached its fullest expression. The final case-studies examine two modern ‘conversions’ that seem to have an ideological rather than a religious basis to them. On closer examination it will be found that the German tradition of Biblical Criticism played a most influential role in the ‘conversion’ of Marx and mythology the best medium to understand the experiences of Koestler. The main ideas emerging from this study highlight the fluidity of identity and the important role of ‘background’ in its transformation. The theoretical framework, as constructed for this study, is found to be a useful methodological tool that can offer insights into experiences, such as conversion, that otherwise would remain hidden from our enquiries.

Evaluation of rhizobacterial colonisation and the ability to induce Globodera pallida hatch

Three bacterial isolates, SB13 (Acinetobacter sp.), SB14 (Arthrobacter sp.) and SB15 (Bacillus sp.), were previously isolated from the rhizosphere of sugar beet (Beta vulgaris ssp. vulgaris) plants and shown to increase hatch of potato cyst nematodes in vitro. In this study, the three isolates were assayed for rhizosphere competence. Each isolate was applied to seeds at each of four concentrations (105-108 CFU ml−1) and the inoculated seeds were planted in plastic microcosms containing coarse sand. All three isolates were shown to colonise the rhizosphere, although to differing degrees, with the higher inoculation densities providing significantly better colonisation. The isolates increased sugar beet root and shoot dry weight. Isolates SB14 and SB15 were analysed for their ability to induce in vivo hatch of Globodera pallida in non-sterile soil planted with sugar beet. After 4 and 6 weeks, both isolates had induced significantly greater percentage hatch compared to controls.

Association analysis of apolipoprotein E genotype and risk of depressive symptoms in Alzheimer's disease

OBJECTIVES: Behavioural and psychological symptoms of dementia (BPSD) are potent predictors of carer distress and admission to institutional care. In Alzheimer's disease (AD), depressive symptoms are one of the most common complaints affecting around 50% of all patients. There is speculation these symptoms result from known genetic risk factors for AD, therefore we investigated the role of apolipoprotein E epsilon4 in the aetiology of depression in AD. METHODS: In this well-characterised cohort (n = 404) from the relatively genetically homogeneous Northern Ireland population, we tested the hypothesis that genetic variants of apolipoprotein E influence the risk for depressive symptoms in AD patients using the Neuropsychiatric Inventory (NPI-D) to determine the presence of depressive symptoms during the dementing illness. RESULTS: A total of 55% of patients exhibited a history of depression/dysphoria during the course of the illness as gathered by the NPI-D questionnaire. Forty-six percent were suffering from depression/dysphoria when the analysis was restricted to the month prior to interview. No statistically significant association between genotypes or alleles of apolipoprotein E and depression/dysphoria in AD was observed, nor was any association noted between the presence of severe symptoms and genotypes/alleles of apolipoprotein E. CONCLUSIONS: These results suggest apolipoprotein E genotype creates no additional risk for depressive symptoms in AD.

Behavioural and psychological syndromes in Alzheimer's disease

The origins of behavioural and psychological symptoms of dementia are still poorly understood. By focusing on piecemeal behaviours as opposed to more robust syndrome change valid biological correlates may be overlooked. Our understanding of BPSD via the identification of neuropsychiatric syndromes.

Apolipoprotein E e4 allele influences aggressive behaviour in Alzheimer's disease

The rising number of people with cognitive impairment is placing health care budgets under significant strain. Dementia related behavioural change is a major independent risk factor for admission to expensive institutional care, and aggressive symptoms in particular are poorly tolerated by carers and frequently precipitate the collapse of home coping strategies. Aggressive change may result from known genetic risk factors for Alzheimer's disease (AD) and therefore accompany conventional markers such as apolipoprotein E (ApoE). We tested this hypothesis in 400 moderately to severely affected AD patients who were phenotyped for the presence of aggressive or agitated behaviour during the month prior to interview using the Neuropsychiatric Inventory with Caregiver Distress. The proportion of subjects with aggression/agitation in the month prior to interview was 51.8%. A significantly higher frequency of the e4 allele was found in individuals recording aggression/agitation in the month prior to interview (chi2 = 6.69, df = 2, p = 0.03). The additional risk for aggression/agitation conferred by e4 was also noted when e4 genotypes were compared against non-e4 genotypes (chi2 = 5.45, df = 1, p = 0.02, OR = 1.60, confidence interval (CI) 1.06 to 2.43). These results indicate that advanced Alzheimer's disease patients are at greater risk of aggressive symptoms because of a genetic weakness in apolipoprotein E.

The interleukin 1beta gene promoter polymorphism (-511) acts as a risk factor for psychosis in Alzheimer's dementia

The explanation for why some patients develop psychotic change in Alzheimer's disease (AD) is unclear. "Psychosis-modifier genes" may act in the setting of neurodegeneration to produce AD plus psychosis in a similar way to how genetic modulation during neurodevelopment leads to schizophrenia. Because there is increasing interest in the common disruption of cytokine pathways seen in both AD and schizophrenia, we tested the association between the functional interleukin-1beta -511 promoter polymorphism with delusions and hallucinations in AD. Significant associations between psychotic symptoms and the CC genotype (p = 0.001 - p = 0.043) and C allele (p = 0.014 vs p = 0.048) were found, thus confirming the previously noted increased risk in schizophrenia.