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Biosecurity is one of the main mechanisms used to protect and mitigate the introduction of non-indigenous species. Effective biosecurity requires a knowledge and understanding of pathways and vectors along which invasion can occur. This study contributes to our knowledge and understanding of possible biosecurity risk factors in the Antarctic by identifying potential vectors for invasive species in the pathway between New Zealand and the Antarctic. The Antarctic has important indigenous terrestrial and marine, plant and animal species, all of which contribute to the food chain in Antarctica and the Southern Ocean. This study seeks to contribute some baseline data about pathways and vectors between the two regions and the implications for the biosecurity of both. An assessment of some of the risks associated with human activities within the Antarctic region, including the traffic of people and goods to and from the area, are the focus of this thesis. Current biosecurity practices with regard to personnel, shipping containers, and fresh produce are examined and where appropriate, recommendations to alleviate any detected risks are made. The results of the research indicate a significant volume of seed and plant material being unintentionally transported to Antarctica. The most striking finding was the presence of seeds in new clothes, which have previously been assumed not to be vectors. The presence of seeds in soil samples in Antarctica suggests that seeds have probably already been transported to Antarctica. Presently the climate in Scott Base seems to prevent non-indigenous species from becoming established. However, with the increases in temperature being experienced in Antarctica, this may not always be the case, therefore greater attention to biosecurity legislation and its implementation is required.

In the field cricket, Teleogryllus oceanicus, two types of auditory interneurons, AN2 and ON1, have been studied. AN2 responds best to ultrasound frequencies (≥20kHz) produced by echolocating bats and initiates negative phonotaxis by the cricket. ON1 responds to both low (4-5kHz) and high frequency sounds and encodes the temporal information present in sounds of both frequencies. ON1 also provides lateral inhibition to contralateral interneurons, such as AN2, thereby enhancing binaural contrast. The pharmacology associated with these two interneurons is investigated here. ON1's response to 4.5kHz sound is increased following picrotoxin application, while it's ability to encode temporal information present in low and high frequency sounds is reduced. An increase in spiking response and a decrease in response latency to low frequency sound is produced by the addition of atropine, while d-tubocurarine application increased ON1's response latency to both 4.5kHz and 30kHz sound. The neuromodulator octopamine reduced AN2's response to ultrasound.

The goal of this thesis was to investigate the role of colour in visual selective attention. Previous experiments exploring this topic in tasks where location varied led to mixed results. Some studies only found evidence of colour as a guide to a specific location where selection then takes place (e.g., Nissen, 1985). Others reported an effect, but could not decide clearly if the benefit was due to direct selection of colour in perception (e.g., Humphreys, 1981). One major contributor to the inconsistencies of findings seems to be the confounding of colour and location in these tasks. For that reason the initial paradigm used here was a rapid serial visual presentation (RSVP) task. Previous studies using similar paradigms have found no evidence for direct selection by colour (Poder, 2001; Shih & Sperling, 1996), but in these studies advance colour information was of limited usefulness because it only reduced the set of candidate stimuli by half. To assess an effect of colour in selection similar to the one associated with location, in all experiments reported here valid colour information led to only one item, as is typical in location cuing tasks. The first RSVP experiment explored whether colour certainty improved performance over a colour uncertainty condition. Colour was the defining feature of the target participants had to discriminate. In one condition the target colour was certain; in the other it could be one of two colours. Performance was improved when participants could focus on one colour. Further experiments used colour not as a defining feature of the target but as additional information presented in the form of cues, similar to the typical use of location cues. The participants� task was to discriminate whether a target letter within the RSVP sequence appeared in its upper or lower case version, and an advance cue indicated the colour in which the target letter was most likely to occur. An accuracy benefit of valid colour information was found, supporting the hypothesis that colour cuing allows the direct selection of objects for further perceptual processing. In addition, an effect of invalid colour cues was also observed. Subsequent experiments investigated possible factors influencing the colour cuing effect. Together, task requirements and properties of the stimulus set were shown to have an influence on the effect size, whereas an increase in perceptual load had no impact. Furthermore, the colour cuing effect seems to be due partially to both automatic and strategic processes. In all these experimental variations, benefits of colour cuing remained, indicating that the effect is very robust. Colour cuing effects were also found in a design where location could vary, extending the previous findings from selection in the time domain to selection in space. The two last experiments investigated whether advance colour knowledge would also lead to a performance benefit in single item tasks. No effect of colour cuing was found, indicating that colour information is only helpful in multiple item displays when a selection of one target stimulus among distractor items is necessary.

Includes bibliographical references (leaves 136-156) / 156 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Two novel in vitro preparations were developed from which recordings were made from colonic afferents in the rat and mouse. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2001

Thesis (Ph. D. in Neuroscience)--Vanderbilt University, May 2008. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 72-85). Also available via the Internet.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 72-74). Also available in electronic version.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Northern peatlands occupy a very small proportion of the Earth’s surface but contain nearly a third of the world’s soil organic carbon. These wetland systems produce substantial fluxes of CH4, a potent greenhouse gas, and are expected to experience particularly high annual mean temperature increases as global climate change proceeds, which could result in a significant positive feedback. Using radioisotope labeling, we quantified the rates of two pathways of CH4 production in six sites in northern Michigan along a physiochemical and ecological gradient that characterizes northern peatlands. We found that the rates of these two pathways displayed markedly different dynamics in space and time and that the hydrogenotrophic pathway, previously presumed to be less significant in these systems, can increase substantially and become dominant across the landscape when water tables are high. Quantifying these two pathways provides critical insight into understanding dynamics of CH4 production in northern peatlands.