Science Collected Works - Theses
Now showing items 1-9 of 9
Forest management and biodiversity conservation: assessing and managing impacts with emphasis on birds and their habitats in Victoria, south-eastern Australia
This thesis includes publications dealing with issues related to conserving wildlife (and especially native birds) in landscapes where people impose multiple demands. The main focus is on forests, and the goal is to help achieve ecologically sustainable forest management (ESFM). The policy challenge is to satisfy the needs for biodiversity conservation while facilitating economic activities (e.g. logging) and other land uses (including fire management to maintain ecological integrity and protect human life, assets and property). The research challenge is to provide information about the habitat needs of wildlife, and their likely responses to different forms of management over long periods of time. The need to consider long periods of time (decades or centuries) is greater in forests than in many other ecosystems, as trees and forests take many decades to mature and develop the full range of habitat features used by wildlife (notably large hollows and other structural features).
Toward a transdisciplinary science of health and wellbeing spanning psychological science and epidemiology: a focus on vagal function
Health and wellbeing are now much studied and contested topics in science. The work presented in this thesis focuses on heart rate variability (HRV), a measure extracted from the electrocardiogram and index of vagal function with links to psychological flexibility, social engagement, and future health and wellbeing. At the heart of this body of work is a desire to better understand the relationship between mental, physical and social health. A total of thirteen published papers are included in this thesis, bridging the gap between psychological science and epidemiology. In papers one and two, I examine the associations between common mental disorders (and antidepressants) and coronary heart disease (CHD), highlighting the association between mental and physical ill-health. Papers three and four investigate whether depression or its treatment are associated with vagal impairment, a major source of debate and discussion in the field. Paper five is a randomised controlled trial of oxytocin, the mammalian neuropeptide, to determine whether oxytocin might augment resting state HRV, a fundamental psychophysiological feature of social behaviour. In paper six, I examine whether alterations are observed in women with a prior history – but not current – anxiety disorders and their offspring to determine potential adverse impacts on future generations. In paper seven, the major outcome of the work I conducted at the University of São Paulo, I examine the association between common mental disorders, antidepressant treatments and vagal function in the largest cohort to date. Paper eight and nine are follow-up studies to this that further explore whether specific subtypes of depression display more robust reductions in HRV, and whether there are differential associations of the selective serotonin reuptake inhibitors on HRV. In paper ten, I examine whether carotid intima-media thickness (cIMT) – a measure of subclinical atherosclerosis – is greater in people with anxiety and depressive symptoms. Paper eleven extends on this idea to examine whether insulin resistance and cIMT mediate the relationship between HRV and executive function. In the final two papers, I present two major syntheses of the extensive literature base on vagal function – including my own research outcomes – and provide two overarching and complimentary theoretical models linking psychological science and epidemiology, with an eye toward further scientific insights and public health outcomes. In conclusion, vagal impairment may provide a ‘spark’ that triggers a downstream cascade of adverse physiological effects that could lead to increasing morbidity and premature mortality. This body of work represents the first steps towards a transdisciplinary science of health and wellbeing, spanning psychological science and epidemiology, providing a platform for future research activity.
Human values in agriculture
The human element in agriculture has been overlooked for a long time. Values are an important dimension of the human element, and are recognized as important determinants of attitudes and behaviour. In the present study the values of some groups in agriculture were measured. The Rokeach Value Survey was administered to 195 farmers, 95 agricultural college staff and 329 agricultural college students. The data were presented in three ways. First, values of farmers were described and related to their reluctance to leave farming. Second, comparisons of values were made within the farmer group and with other groups - in particular farmers' and staff values were compared. Third, the values of students at each of three colleges were correlated with their perception of values espoused by their college. Results were examined in light of what is known about the attitudes and behaviour of these groups. The measurement was useful in pinpointing both actual and perceived value differences between farmers and staff. It also provided some useful descriptive data.
Inuit knowledge and perceptions of the land-water interface
The Inuit of Kangiqsualujjuaq have maintained functional and spiritual connections with the landscape and waters of Arctic Quebec (Nunavik) for over four thousand years. While ethnographic studies about this ocean-going population have revealed their pragmatic relationships with the arctic milieu, less is known, however, about their perceptions of terrestrial and aquatic realms. Three fieldtrips to Kangiqsualujjuaq were undertaken between 2003 and 2005 to explore how three generations of Inuit perceived the landwater interface, a geographical setting regularly frequented and considered spiritually important to the Inuit. Surveys were carried out to determine whether Inuit regarded the sea as an extension of the “land”, a way of thinking about space that is common among indigenous islanders in southern latitudes.
The preparation and properties of tantalum and some of its alloys
The study of tantalum, its compounds and alloys, first began in Melbourne in i942. It was undertaken as part of a programme to investigate the effect of adding hard, high melting point, metallic carbides, eg. tantalum carbide, to the tungsten carbide compacts which were being studied for tool tipping purposes. The early stages involved the development of a method for separating tantalum oxide and columbium (niobium) oxide from an ore which occurred abundantly in the Western States of Australia. This work, together with a review of the literature on the subject and the results of an investigation into a method of preparing pure tantalum and columbium carbides, has been described earlier. Because of the war situation it was considered more important to develop to the pilot scale, a plant for producing pure tantalum oxide and consequently the carbine work was discontinued. After the pilot plant had been established, work on tantalum ceased for two years owing to pressure of other problems in connection with the refractory metals project at the University. Subsequently, it was possible to return to a study of tantalum and the first step was to investigate the factors involved in the preparation of the metal. The electrolytic process was studied in some detail and this was followed by experiments on the consolidation of the tantalum powder produced. Apparatus for the high temperature, vacuum heat treatment of the pressed compacts was developed and methods of working and fabricating tantalum were studied. Some of the properties of consolidated tantalum were determined and the effect of deformation on these properties, and on the annealing temperature, was investigated. Finally the effect of alloying other high melting point metals with the tantalum was studied. The results of most of the work have been assembled in the form of papers, some of which have been published and others are ready for publication. These will be included as appendices to the thesis and will be, referred to frequently. The thesis will serve to link the various papers together to form a consolidated picture of the investigation to date. (From introduction)
Sulphate-oxide equilibria for copper, iron, cobalt, and nickel
Applications of the process of differential (or selective) sulphation have been extensively reported over the last ten years, coinciding with the adaptation of the fluidised bed reactor (or fluo-solids roaster) to metallurgical practice. With this technique a suitable combination of temperature and sulphur trioxide partial pressure is employed, so that metals with sulphate decomposition pressures higher than the chosen value (for the particular temperature), are converted to oxides, while the more stable sulphates are unaffected. The idea of such separations was first outlined by Marchal, and Wohler and Grunsweig (cited below). This method is particularly useful in the extraction of non-ferrous metals, where iron, the most common impurity, may be removed. In such processes reliance is placed on the instability of iron sulphates, which are converted to ferric oxide, while, for example, copper, nickel, cobalt and manganese, remain as sulphates. Hence, if roasting is followed by a water leach, the sulphates are dissolved, while the oxides remain in the residue. Table 1.1 lists a few of the many commercial separations achieved by suitable control with this process. As the table shows, a wide range of ores and concentrates may be treated by this technique which considerably shortens the steps necessary to achieve satisfactory separations and increases the efficiency of extraction of the valuable metals. A further advantage is that metal sulphides or oxides may be treated in this way. In the case of the former, air is admitted to give a gas of the required composition, while with the latter, air together with sulphur dioxide from an external source, such as a pyrites roaster is used.
The east Antarctic ice: from ice sheet flow to iceberg dissolution
This thesis investigates the question of the state of balance, mass budget and dynamics of a large section of the East Antarctic Ice Sheet. The distribution and dissolution of icebergs originating from the icesheet outflux is also determined. Comparison of field measurements collected from oversnow traversing, with balance calculations determined by computer modelling studies, shows that the ice sheet is not likely to be significantly out of balance (i.e. by more than ±10%). By assuming that it is in balance, the ratio of average column velocity to surface velocity is determined to be 0.89. Analysis of the mean strain-rate versus down slope shear-stress indicates values of the commonly used power flow law parameters to be n = 3.2 and k1 = 0.023 bar -n s-1. For the basal ice and high shear zone ice the value of k1 is shown to be k1 = 0.055 bar -n s-1. Comparison of the same results with laboratory work suggests temperatures of the basal ice to be between -5° C and -10° C. The outflux of ice between longitude 90° E and 150° E is estimated to be be 389 km3a-1. Analysis of iceberg size frequency distributions from shipboard observations reveals that Antarctic icebergs (less than 1000m in horizontal dimension) have a median life before breakage, of 0.2 years. This is significantly lower than previously thought. The mean melt rate is estimated to be 0.12 md-1 which agrees broadly with previous laboratory studies for water temperatures averaging + 1°C. More accurate data on iceberg calving, movement and dissolution is required to adequately assess discrepencies from balance computed by ice sheet accumulation and flow studies.
Glaciological studies made at Wilkes base and on the Antarctic Icecap between Wilkes and Vostok, in 1962
During 1962 data were collected at Wilkes Base, Antarctica and between Wilkes Base and Vostok, 850 miles inland, on snow accumulation rates and sub-surface ice temperatures. These data have been used in conjunction with information on ice thicknesses to calculate theoretical temperature profiles throughout the icecap, and the validity of these calculations examined by comparison with known temperatures. A method of preparation of plastic replicas of snow crystals and drift snow particles was studied, and the knowledge gained utilised to obtain accurate replicas of drift snow particles inland from Wilkes. Particle size frequency distributions of the drift particles were studied using the plastic replicas for measurement purposes.