Lack of accurate data for epidemiological studies of low dose radiation effects necessitates development of dosimetric models allowing prediction of cancer risks for different organs. The objective of this work is to develop a model of the radiation response of human bronchiolar tissue with single cell resolution. The computer model describes epithelial tissue as an ensemble of individual cells, with the geometry of a human bronchiole and the properties of different cell types are taken into account. The model simulates the tissue kinetics and radiation exposure in four dimensions: three spatial dimensions and a temporal dimension. The bronchiole is modeled as a regular hollow cylinder with the epithelial cells of three different types (basal, secretory, and ciliated) lining its interior. For the purposes of assessment of radiation damage to the cells only the nuclei of the cells have been modeled. Subroutines describing cellular kinetics have been developed to simulate cell turnover in a normal epithelial tissue. Monte Carlo subroutines have been developed to simulate exposure to alpha particles; the GEANT4 toolkit has been used to simulate exposure to low LET radiation. Each hit cell is provided with a record of energy deposition, and this record is passed to the progeny if the cell survives. The model output provides data on the number of basal progenitor cells in different phases of a cell life-cycle and secretory to ciliated cell ratio after several generations of cell proliferation. The model calculates labeling and mitotic indices and estimates the average cell turnover time for the bronchiolar tissue. Microdosimetric calculations are performed for cells traversed by ionizing particles. The model will be used to assess the accumulation of damage in cells due to protracted low level radiation exposure. The model output may provide directions for the future experimental design.

Student Number : 0102295F - MA research dissertation - School of Psychology - Faculty of Arts / A review of trauma literature indicated that in comparison to PTSD there is very little research into the effects of secondary trauma, especially with regards to trauma workers. The present study explored the psychological impact of trauma workers who work with victims of violent crimes. Both Figley’s (1995) trauma transmission model and Dutton and Rubenstein (1995) ecological model were used to develop a refined trauma model for trauma workers in South Africa, which formed the theoretical basis for the current research. This model looked at the relationships between specific key variables (level of exposure to traumatic material, empathy, and level of perceived social support) and secondary traumatic stress, and their interrelationship. In the present study relevant information was gathered from volunteer trauma workers (N=64) using self-report measures. Data was analysed using the following statistical techniques: Descriptive statistics, Pearson’s Correlation Coefficients, Two Independent Sample T-Test, and a Moderated Multiple Regression. Results indicated that the trauma workers, to some extent, experienced symptoms of secondary traumatic stress. In addition, it was found that previous exposure to traumatic material, level of empathy, and level of perceived social support have a significant relationship with secondary traumatic stress. Social support was not found to have a moderating effect, but empathy emerged as a consistent moderator between the trauma workers previous exposure to traumatic material and secondary traumatic stress. Results also revealed that ones qualification made no difference in the development of secondary traumatic stress. In summary, this study expanded on knowledge into the effects of criminal violence in South Africa, particularly with concern to trauma workers, a population often ignored. This study was considered to be a contribution to trauma literature as it provides much needed empirical evidence.

Aims: The aims of this thesis were to describe and gain an understanding of how people who live in the vicinity of wind turbines are affected by wind turbine noise, and how individual, situational and visual factors, as well as sound properties, moderate the response. Methods: A cross-sectional study was carried out in a flat, mainly rural area in Sweden, with the objective to estimate the prevalence of noise annoyance and to examine the dose-response relationship between A-weighted sound pressure levels (SPLs) and perception of and annoyance with wind turbine noise. Subjective responses were obtained through a questionnaire (n = 513; response rate: 68%) and outdoor, A-weighted SPLs were calculated for each respondent. To gain a deeper understanding of the observed noise annoyance, 15 people living in an area were interviewed using open-ended questions. The interviews were analysed using the comparative method of Grounded Theory (GT). An additional cross-sectional study, mainly exploring the influence of individual and situational factors, was carried out in seven areas in Sweden that differed with regard to terrain (flat or complex) and degree of urbanization (n = 765; response rate: 58%). To further explore the impact of visual factors, data from the two cross-sectional studies were tested with structural equation modelling. A proposed model of the influence of visual attitude on noise annoyance, also comprising the influence of noise level and general attitude, was tested among respondents who could see wind turbines versus respondents who could not see wind turbines from their dwelling, and respondents living in flat versus complex terrain. Results: Dose-response relationships were found both for perception of noise and for noise annoyance in relation to A-weighted SPLs. The risk of annoyance was enhanced among respondents who could see at least one turbine from their dwelling and among those living in a rural in comparison with a suburban area. Noise from wind turbines was appraised as an intrusion of privacy among people who expected quiet and peace in their living environment. Negative experiences that led to feelings of inferiority added to the distress. Sound characteristics describing the amplitude modulated aerodynamic sound were appraised as the most annoying (swishing, whistling and pulsating/throbbing). Wind turbines were judged as environmentally friendly, efficient and necessary, but also as ugly and unnatural. Being negative towards the visual impact of the wind turbines on the landscape scenery, rather than towards wind turbines as such, was strongly associated with annoyance. Self-reported health impairment was not correlated to SPL, while decreased well-being was associated with noise annoyance. Indications of possible hindrance to psycho-physiological restoration were observed. Conclusions: Wind turbine noise is easily perceived and is annoying even at low A-weighted SPLs. This could be due to perceived incongruence between the characteristics of wind turbine noise and the background sound. Wind turbines are furthermore prominent objects whose rotational movement attracts the eye. Multimodal sensory effects or negative aesthetic response could enhance the risk of noise annoyance. Adverse reactions could possibly lead to stress-related symptoms due to prolonged physiological arousal and hindrance to psychophysiological restoration. The observed differences in prevalence of noise annoyance between living environments make it necessary to assess separate dose-response relationships for different types of landscapes.