The planning of a South African airborne synthetic aperture radar measuring campaign

Bibliography: leaves 153-163.This thesis sets out the results of work done in preparation for a South African Airborne Synthetic Aperture Radar (SAR) measuring campaign envisaged for 1994/5. At present both airborne and spaceborne SARs have found a niche in remote sensing with applications in subsurface mapping, surface moisture mapping, vegetation mapping, rock type discrimination and Digital Elevation Modelling. Since these applications have considerable scientific and economic benefits, the Radar Remote Sensing Group at the University of Cape Town committed themselves to an airborne SAR campaign. The prime objective of the campaign is to provide the South African users with airborne SAR data and enable the Radar Remote Sensing Group to evaluate the usefulness of SAR as a remote sensing tool in South Africa

Space programs summary no. 37-51, volume 3 for the period April 1 to May 31, 1968. Supporting research and advanced development

Space Programs Summary - supporting research and advanced developmen

A study of dementia in a rural population

Dementia, in particular Alzheimer's disease, has been widely investigated in clinical settings. Moreover, many epidemiological studies have been carried out to estimate the prevalence and incidence of dementia and, less frequently, Alzheimer's disease. There have also been studies of ageing cohorts to examine mental changes associated with ageing. There has, however, been little research on unselected elderly populations which has been detailed enough to examine the relationship between normal and abnormal mental ageing. The aim of this study was to investigate the distribution of the indices of dementia in a rural population. This allowed investigation of the hypothesis that variables associated with dementia, in particular Alzheimer's disease, are distributed bimodally in the population and allowed investigation of possible associations with these distributions. It also provided prevalence estimates of dementia in a rural population. A population sample of women aged 70 to 79 was selected from a rural Cambridgeshire health centre. Using the Cambridge Examination for Mental Disorders in the Elderly all aspects required for the diagnosis of dementia and tentative differential diagnosis were collected on 365 women. There was no evidence of bimodality in any of the derived scales, whether cognitive, behavioural or ischaemic. The prevalence of dementia of all types and levels, including mild, was 4.3% in the 70 to 74 age group and 11.7% in the 75 to 79 age group. For more severe dementia a prevalence of 2.8% was found in the 75 to 79 age group, and 0% in the 70 to 74 age group. The rates for more severe dementia were lower than other recent prevalence studies in the UK, whereas the rates for all levels of severity were higher. The tentative diagnosis of Alzheimer's disease accounted for 52% of the diagnoses of dementia and multi-infarct dementia for 31%. Age, social class and education were all significantly and independently associated with scores on the longer cognitive scales (Mini-Mental State Examination and the CAMCOG scale of CAMDEX). Risk factors suggested in the literature for dementia, Alzheimer's disease and cognitive impairment was also investigated. Few factors were associated with either cognitive function or dementia. Age was the only variable associated with both cognitive function and the diagnosis of dementia. Only small proportions of the population were exposed to postulated risk factors and these risk factors, if proven, would account for little population excess risk. In this study no significant separation of performance on cognitive or behavioural scales between the demented and the non-demented was found. This could have been due to the small numbers in the tails of the frequency distributions but, if true, it is suggested that this observation might be related to the continuous distribution of underlying neuropathological lesions, such as plaques and tangles, noted in autopsy series of unselected populations. If so, current research into the mechanisms of the dementias may have implications for the understanding of cognitive decline noted in the non-demented elderly over time

An autecological study of bushbuck and common duiker in relation to forest management.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1986.Frequent reports of damage caused by bushbuck and common duiker browsing on commercially important timber seedlings, and an interest in the potential and feasibility of hunting these two species on State land were the primary factors responsible for the Directorate of Forestry's motivation of this study. The study area at Weza State Forest comprised approximately 21 000 ha of plantations, grasslands and indigenous forests which were considered representative of timbered areas throughout the Natal midlands. Several methods of age determination were investigated and these findings permitted assessments of growth, fecundity and population structure. The physiological condition of both antelope species was examined in relation to age, sex, reproduction and management strategies, and the results discussed in conjunction with mortality patterns. Principal foods of both bushbuck and duiker were determined from rumen analyses while 112 marked animals were regularly monitored to facilitate assessments of habitat selection and levels of spatial and social organisation. of these largely solitary and Estimates of the abundance nocturnal antelope were influenced by local movements in response to the availability of food and cover which varied seasonally and also fluctuated dramatically with forest succession and timber management activities. Although bushbuck and duiker bred throughout the year and had almost identical rates of reproductive performance, different factors were responsible in limiting the sizes of these two populations. All the available evidence gathered in this study indicated that food resources during winter and early spring were inadequate for bushbuck, particularly in 1983 when 33% of the marked population died from starvation and/or exposure. Notable differences in forage utilization and habitat selection inferred little interspecific competition at this time of the year. In contrast, territorial duiker appeared to be susceptible to highly localised habitat modifications (including the availability of food and cover) which occurred throughout the year and resulted from silvicultural and timber harvesting practices. Rumen analyses and quantitative damage assessment surveys revealed that browsing on timber seedlings was usually confined to localised areas during the winter months and was much less severe than had been originally suggested. Conifers were regarded as a starvati~n food and methods of reducing damage to these young trees were recommended for potential problem areas. Both antelope species were considered overabundant at Weza and recommendations for the future management of these populations included the limited utilization of surplus animals, by sport hunting on a sustained yield basis, and methods of manipulating and improving forest habitats