UQ Theses Collection (RHD) - UQ staff and students only - UQ eSpace

Amino Acid Digestibility and Requirements of Broiler Chickens

Mulyantini Ni Gusti Ayu — 2009-01-30T00:00:00Z

The dietary requirement for protein is actually a requirement for the amino acids contained in the dietary protein. The efficiency of protein utilization depends to a large extent on the amino acid composition of the diet. Although a large volume of published amino acid digestibility values for poultry feedstuffs is available, there are still many gaps in our knowledge on digestibility and utilization of amino acids. The major focus of this thesis was to examine several aspects of amino acid digestibility and utilization in broiler chickens. Initial studies examined the performance of two commercial broiler strains fed diets formulated on total or digestible amino acids. The objective of this study was to determine the individual bird response to 4 different diets formulated on: 1) total amino acids; 2) digestible amino acids (book values)using the same ingredient as diet 1; 3) digestible amino acids values determined on the same ingredients as used in diet 1: and 4) digestible amino acids but formulated commercially. The results show that birds given diets formulated on digestible amino acid basis, grew faster, ate more feed and converted it into body weight more efficiently, and had a higher proportion of body protein (P<0.05) than birds given diet formulated on a total amino acid basis. It was also shown that males broiler were significantly faster growing, consumed more feed and had better feed efficiency than do female broilers. There was also a significant (P<0.05)sex x diet interaction for weight gain. Whilst, males always grew faster than females, the difference was much greater for those given the digestible amino acid formulated diets. The studies reported in Chapters 5 and 6 was conducted to determine the digestible methionine, lysine and threonine requirement of broilers during the starter and finisher periods. The minimum digestible methionine requirements to maximize weight gain for starter was similar with grower. Digestible lysine requirements to maximize weight gain represent a decrease 25%, respectively from starter to grower. The lysine digestible requirement for weight gain decreased from 11.4 g/kg diet (0 to 3 wk) to 8.5 g/kg diet (3 to 6 wk). For threonine, the starter threonine level of 6.5 g/kg resulted in the best responses (P<0.01). The study reported in Chapter 7 was to identify the extent of differences in the nutritional value of sorghum available within Australia, in particular the apparent digestibility of amino acids in sorghum samples based upon digesta samples taken from the lower ileum of the chicken. The results of this study suggest that it is possible to estimate digestible amino acid supply from sorghum from the protein content of the grain. Crude protein content (N x 6.25) of sorghum varied from 80.2 to 117.5 g/kg dry matter. In most Australian cereal based diet lysine is first limiting amino acids. In this experimental diet, methionine is the first limiting amino acid content ranged from 1.06 to 1.42%. It followed by lysine, histidine and glycine, respectively. The cereal-based diets fed to poultry contain substantial quantities of phytin,which is poorly digested by poultry. The poor digestive utilization of phytin-bound P by poultry and its consequences on digestibility of protein and amino acids lead to do some more extensive research in this aspect. In this regard, the effects of enzyme supplementation on apparent ileal amino acid digestibility of cereal were studied in Chapter 8. Supplementing wheat fed to 5-wk-old broilers with xylanase alone or a combination of xylanase and phytase improved the ileal digestibility of amino acids. Although there was improvement in sorghum based diet, phytase and xylanase supplementation had no effect on the avaergae of ileal amino acid digestibility. Overall, the results presented in this thesis demonstrate that formulation of poultry diets on a digestible amino acid basis is superior to formulation of diets on a total amino acid basis. This study suggested that genotype and sex differences in performance and body composition should be taken into account when formulating diets to maximize performance of broiler chickens. Moreover, the requirement of digestible lysine, methionine and threonine for broiler chicken during the starter and finisher periods were obtained in this study.

A MODEL FOR GRAVITY FLOW OF FRAGMENTED ROCK IN BLOCK CAVING MINES

Matthew Pierce — 2010-09-07T00:00:00Z

The work in this thesis is directed towards the development of a model for gravity flow prediction that can assist in the design of a drawpoint layout and draw schedule that maximizes recovery of ore from block and panel caving mines. Experience suggests that maximum recovery and minimum dilution are achieved most easily if one is able to achieve relatively uniform downward movement of all fragmented rock over the area under draw. A critical review of existing experimental and simulation data demonstrated that this is encouraged through overlap of the movement zones (IMZs) associated with each individual drawpoint and that the far-field shape, eccentricity and internal velocity profile of an IMZ are functions of the mean fragment size and friction angle of the caved rock. A series of DEM and continuum modelling studies were used to isolate shear banding as the mechanism controlling these behaviours. Incremental equations were developed to embody these mechanisms at the scale of a disk-shaped volume, representing a horizontal slice through an IMZ, and embedded within a cave-scale simulator (REBOP). It is shown that the resulting model provides predictions of far-field material movements (including free surface rilling) and extraction zone shapes that are consistent with observations from scaled physical models. It is also shown that the model is capable of providing reasonable predictions of drawpoint grade-tonnage trends when applied at the mine scale. This thesis also aimed to isolate the mechanisms controlling flow under interactive draw conditions, in which stress-driven yielding and flow of stagnant material between IMZs can result in uniform drawdown prior to overlap. A series of DEM and continuum modelling studies demonstrate that the stress distribution around a single IMZ is characterized by a plastic zone whose thickness is a function of IMZ radius, caved rock friction angle and overburden height. It was also demonstrated that when a group of IMZs are spaced such that their plastic zones overlap, vertical stresses above the yield limit of the rock in the overlapping region are capable of arching into surrounding stagnant material, thereby inhibiting interactive draw mechanisms. These findings suggest that the relation between stress and strength in the stagnant zone exerts more fundamental control over interactive draw than the ratio between IMZ diameter and drawpoint spacing, as has been suggested previously by other researchers. Logic was developed for the prediction of stresses and yielding inside the volume under draw that accounts for arching effects and can be used to infer where interactive draw conditions may exist. Comparison with the results of numerical and physical experiments suggests that the predictions are reasonable but would benefit from further testing and validation. A series of drawpoint-scale simulations were conducted using DEM to explore the mechanisms controlling fines migration in a caving environment. It was demonstrated that fines migration can occur inside the IMZ and that it is induced by the shearing that accompanies movement toward the drawpoint. It was also found that lateral movement of finer particles is restricted during percolation and that this can lead to stagnation and accumulation of fines near the base of an IMZ. A series of shear box tests were simulated via DEM to quantify percolation rates for caved rock materials. When embedded within REBOP, these were shown to reproduce the percolation rates observed in scaled physical models of draw. Secondary fragmentation within caving is commonly attributed to a combination of splitting (bulk fracture or crushing) and rounding (abrasion). A critical review of available data suggested that splitting occurs via compression in stagnant zones and via shearing inside the IMZ at high stress:strength ratios. Rounding is most likely to occur via shearing inside the IMZs at low stress:strength ratios. The factors controlling these mechanisms were isolated, including shear strain, stress, fragment shape, size distribution, intact strength and initial porosity. An existing empirical model for shearing-induced fragmentation of manufactured materials was adapted for embedment within REBOP and tested via comparison with changes in drawpoint fragmentation observed at an operating mine. The comparison suggests that the logic may overpredict the degree of secondary fragmentation due to the assumption of an initially uniform fragment size in the empirical model. New DEM techniques were developed for the study of secondary fragmentation and were shown to offer promise as a means to extend and improve existing empirical models for both shearing and compression-induced fragmentation. Ore grades and fragmentation measured in drawpoints of the 7700 Level panel cave at Henderson Mine were used to test the newly developed model on a full-scale problem. Good matches were obtained between predicted and measured drawpoint grades where accurate measures of initial fragment size were available. In other areas, poor matches between measured and expected grades could be accounted for in the new model via differences in fragmentation and by the tendency for materials to rill long distances horizontally beneath uncaved ground. Fines migration and secondary fragmentation mechanisms were predicted to have a measurable, but secondary influence on recovery and dilution.

A model for the chemorheological behaviour of thermoset polymers

Altmann, Nara. — 2011-04-27T18:59:27Z

A model of cluster adoption : the role of transaction costs, resource characteristics, and technology.

Castner, Grant James. — 2007-08-24T00:00:00Z

A model of industrial sugar crystallisation

Wright, Peter George — 2012-12-05T10:53:35Z

A molecular approach to study the interaction between environmental stress, immune response and disease in the black tiger prawn (Penaeus monodon)

De la Vega, Enrique — 2013-03-11T10:07:03Z

Amplectors : a new topology for mixed donor nitrogen-thioether ligands and template for encapsulated complexes

Sharrad, Clint Alan. — 2007-08-24T00:00:00Z

A multidisciplinary team approach to pharmaceutical care and outcomes for residents of aged care facilities

Lynne, Teresa Ann — 2007-08-24T00:00:00Z

A Multilevel Analysis of the Occupational Stressor-Strain Process: Contextual Variables as Additional Moderators in the Job Demand-Control Model

Michelle Tucker — 2010-11-19T00:00:00Z

Abstract Poor working conditions and other environmental stressors have been linked to detrimental effects on employee well-being (Ganster & Schaubroeck, 1991; Jex & Crossley, 2005; Siegrist, 2008; Segerstrom & Miller, 2004). A major objective of research in this area is to identify those factors that mitigate or lessen the negative impact of work stressors. Karasek's (1979) Job Demand-Control Model (JD-CM) endeavours to explain the stressor-strain process from a job design perspective, whereby job control is proposed to mitigate the negative effects of job demands on strain. However, the evidence in regards to the interactive effects of job demand and job control remain mixed, and it has been hypothesised that there may be additional moderating variables involved in the stressor-strain process that better explain how strain may be reduced. Although a number of additional individual-level moderators have been examined, such as self-efficacy, and social support, the role of broader contextual team and organisational factors, and the transaction between the individual and the environment have been largely overlooked. It is, therefore, important to investigate cross-level effects between individual-and group-level factors to gain a better understanding of the stressor-strain process. One such potential contextual factor is collective efficacy (Bandura, 1997) – the shared beliefs of a group that they have the resources and skills to manage a problem. It is hypothesised that group-level collective efficacy buffers the negative effects of stressors by providing the group with the confidence that they can cope in a productive manner, by using personal control to manage stressors. A second potential group-level moderator is group identification (Tafjel & Turner, 1979). Groups high in identification are characterised by shared values, goals, attitudes, and mutual respect. It has been argued that a strong sense of group identification buffers individuals and workgroups from the negative effects of stressors, by reducing uncertainty and providing a socially supportive environment that allows individuals to feel confident exercising personal control to deal with stressors. The objective of this thesis is to examine the role of these group-level factors as additional moderators of the JD-CM. The individual-, group-, and cross-level interactive effects of job design and contextual variables on strain will be investigated to develop a better understanding of how the broader social context in which one works impacts on individual factors and how strain is experienced at both the individual- and group-levels. The first study employed a cross-sectional survey design, whereas Study 2 was a longitudinal field study. A broad overview of each study is presented below. In Study 1, data was collected from 544 employees nested within 23 workgroups. Perceptions of job demands, job control, collective efficacy, workgroup identification, job satisfaction, and strain were measured. Variance components analyses found that significant amounts of variance in both anxiety and job satisfaction were shared collectively at the group-level. The major objective for this study was to evaluate whether collective efficacy and identification acted as group-level moderators of the individual-level JD-CM variables. Significant 3-way interactions were found among group-level collective efficacy, individual-level job control, and individual-level job demand on anxiety and job satisfaction, as well as among group-level identification, individual-level job control, and individual-level job demand on anxiety and job satisfaction. These interactions revealed that when collective efficacy was high, individuals perceiving high levels of job control were buffered from the negative effects of high job demands. Moreover, when group-level collective efficacy was low, high job control exacerbated the negative effects of job demands on both anxiety and job satisfaction. When group identification was high, the positive effects of high job control on job satisfaction were more marked. Conversely, when identification was low, high levels of perceived individual control were related to higher strain. These findings suggest that contextual factors may influence whether job control is perceived as a buffering or exacerbating factor. Study 2 examined the effects of these two contextual variables in the JD-CM over time. Using a sample of 120 participants nested within 8 workgroups, two surveys were conducted in a partial two-wave panel design. The results revealed significant 3-way interactions among group-level collective efficacy, individual-level job control, and individual-level job demands for depression, but not for anxiety, stress, or job satisfaction. The 3-way interaction among group-level workgroup identification, individual-level job control, and individual-level job demands was significant in the prediction of job satisfaction only. Both interactions followed similar patterns as those found in Study 1, providing additional support, albeit less consistently, for the notion that contextual factors need to be in place in order for job control to operate as a stress-buffer. Overall, the findings from both studies have several important implications for the JD-CM and for stress research in general. First, the findings suggest that aspects of strain are shared experiences among employees nested within workgroups, and this provides support for the notion that individuals are not independent of their contexts. Additionally, the findings from both studies suggest that the expansion of the JD-CM is warranted and that group-level contextual factors may act in concert with individual-level variables in buffering the effects of stressors in the work environment.

A Multi-method Investigation of the Relationship between Intra-team Values, Conflict and Trust

Ju-Li Ng — 2011-04-29T00:00:00Z

ABSTRACT Values serve as the guiding mechanism for behaviours and operate at different organisational levels. While there has been sustained interest in the study of organisational values over the years, the majority of these studies focused on how value congruity (or incongruity) affects organisational variables such as performance and productivity. Additionally, scholars continue to compartmentalise the study of values, focusing on individual, team and organisational levels as the units of analysis, while neglecting the cross-level effects of values. Thus, limited research has examined the process by which specific individual values impact team values and how these values drive behaviours to impact conflict. Along the same line, while conflict researchers identify trust as an important variable in the outcomes for workplace conflict, there is an emerging paradigm shift in conflict literature suggesting that conflict may be an antecedent and beneficial to trust. This thesis attempts to address these conceptual gaps. Anchored in Social Exchange Theory (SET) and drawing on values, conflict and trust literature over three studies, the present research develops and tests a cross-level model of the relationship between values, conflict and trust in organisational teams. Specifically, the thesis proposes that individual values (self-direction, achievement and benevolence) will influence the team values of team orientation and outcome orientation, while the values at the team level will influence the different dimensions of conflict (task, relationship and process). These, in turn, will impact different dimensions of trust (calculus, knowledge, and identification-based trust). A multi-method research design was employed in data collection to ascertain the hypothesised relationships in the proposed model for this research program. First, Study 1 explored the issues of workplace values, conflict and trust using in-depth interviews with 45 team members and leaders from two Australian organisations. The interviews revealed three forms of cross-level effects of values: top-down, bottom-up and an amalgamation of the two. Additionally, the interviewers indicated that the interplay between conflict and trust is multi-faceted, while communication was identified as an important tool in building trust when there is conflict. Study 2 employed observations, longitudinal open-ended surveys and post-observation interviews to further extricate the effects of conflict on the perception of trust in teams. Team processes of five postgraduate student work teams in a large public university were observed while these students were working on their assignment over a period of ten weeks. Data for Study 2 were analysed using Bales Interaction Process Analysis (IPA) (1951). Study 2 demonstrated that the influence of conflict on trust has temporal properties implying a dynamic association between conflict and trust. Study 2 also revealed that task conflict was linked with Knowledge-based Trust (KBT), while the presence of relationship and process conflict triggered both Identification-based Trust (IBT) and Calculus-based trust (CBT). Similarly, Study 2 findings identified task-oriented communication, positive socio-emotional communication and control mechanisms as buffers to protect trust and to build trust in the face of conflict. Overall, findings from Study 1 and Study 2 assisted in refining the preliminary research model. Finally, Study 3 quantitatively tested the hypothesised relationships in the proposed model with a sample of 237 leaders and team members from five Australian organisations. Using STATA 11.0 and Bootstrapping to examine the predictive ability and generalisability of the hypothesised relationships between variables depicted on the conceptual model, findings show that although there was no significant path between individual values and team outcome orientation value, individual values (self-direction, achievement and benevolence) positively predicted team orientation values. Team orientation values were negatively associated with task, relationship and process conflict and these, in turn, successfully mediated the relationship between team orientation and the different dimensions of trust as hypothesized. Finally, conflict (task, relationship and process) were negatively related with KBT and IBT. Taken together, the present research has made six significant contributions. First, it has made a theoretical contribution to values literature, as this is the first time that a cross-level effect of individual values on team values has been investigated. Second, results of the current research explicate the process by which shared values and specific values trigger conflict. Third, this research is among the first to empirically document the effects of different forms of conflict on different dimensions of trust, and evidence from Study 1 and Study 2 suggests that conflict can impact trust positively. The current research, therefore, is one of the pioneers of research on the reverse proposition that conflict may be beneficial for trust. Fourth, and methodologically, this is the first time that an IPA framework has been extended to code the unique characteristics of disclosure and conflict. Fifth, the research highlights the usefulness of multi-method research to understand the complex relationship between values, conflict and trust. Finally, the research contributes to the management of values, conflict and trust by espousing that positive socio-emotional communication, task-oriented communication and setting control mechanisms can have a significant impact on trust in the face of conflict. Keywords values, conflict, trust, multilevel, team processes Australian and New Zealand Standard Research Classifications (ANZSRC) 150311 Organisational Behaviour (70%) 150305 Human Resources Management (20%) 150399 Business and Management not elsewhere classified (10%)

A multiple-model repository with manipulation and analysis tools for process engineering

McGahey, Steven Lewis — 2013-03-08T13:36:31Z

An absence of saints

Licari, Rosanna — 2012-07-27T00:00:00Z

Anaerobic Degradation Process for Cellulosic Material using Rumen Microorganisms

Barnes, Sean Patrick — 2007-08-24T00:00:00Z

An agricultural loan evaluation expert system.

Bryant, Kay C. — 2010-12-15T00:00:00Z

Analyses of the relationship between stable isotope signatures, leaf epidermal morphology and the environment

Denton, Tricia M. — 2012-05-04T00:00:00Z

Analysing the Evolution of International Trade: A Complex Networks Approach

Timothy Kastelle — 2008-07-22T00:00:00Z

Analysis and Architectures for Bang-bang Phase Locked Loops

Mr Michael Chan — 2008-11-06T00:00:00Z

Analysis and Design of Free-Space Optical Interconnects for Optically Augmented Computing

Mr Feng-chuan Tsai — 2009-03-06T00:00:00Z

Performance requirements of short-distance digital communication links have increased considerably with the escalating demand for high speed and high density data links. The high aggregate bandwidth and channel density achievable by free-space optical interconnects (FSOIs) make them ideal replacement for electrical interconnection schemes. Optical interconnects potentially have low power consumption, and can facilitate the development of radically novel designs for VLSI architectures including heterogeneous multiprocessor systems, and highly parallel computing systems. Recent developments in the integration of Vertical-Cavity Surface-Emitting Laser (VCSEL) arrays and photodetector arrays with CMOS electronic circuitry have increased the practical potential of optical interconnects. However, VCSELs tend to operate in several transverse modes simultaneously, which will degrade the performance of FSOIs. Experimental investigation was performed to evaluate the operation characteristics and the intensity noise in VCSELs. The measurement results were later combined with optical simulations to analyse the effect of optical crosstalk in free-space optical interconnects. The VCSEL characterization included light-current-voltage relationships, relative intensity noise, modal spectral composition and modal beam profiles. The optical system simulation software (Code V) was used to simulate optical crosstalks in the FSOI system. Experimentally measured spectrally-resolved near-field images of VCSEL higher order modes were used as extended sources in the proposed simulation model. The simulation was performed using a combination of exact ray-tracing and the beam propagation method. A new type of crosstalk referred to as the stray-light crosstalk (SLC) was introduced. This type of crosstalk is caused by the overfill of the transmitter microlens by the VCSEL beam. It was discovered that part of the signal was imaged by the adjacent microlens to another channel, possibly far from the intended one. The simulation showed that the SLC is strongly dependent on the fill factor of the microlens, array pitch, and the channel density of the system. When comparing the diffraction-caused crosstalk (DCC) to SLC, an increase in the interconnection distance has little influence on the SLC. A simple behavioural model was developed which accurately approximates the crosstalk noise for a range of optical sources and interconnect configurations. The effect of transmitter and receiver array configurations on the performance of FSOIs was investigated. Our results demonstrate the importance of SLC in both square and hexagonal configuration. By changing the array lattice geometry from square to a hexagonal, we obtained an overall optical signal-to-noise ratio (SNR) improvement of 3 dB. The optical SNR is optimal for the hexagonal channel arrangement regardless of the transverse mode structure of the VCSEL beam was shown. Furthermore, the VCSEL drive current required for the best performance of the FSOI system was determined. The optimal focal length of the transmitter microlens array which maximises the SNR by minimising the combined effects of DCC and SLC was determined. Our results show that shorter focal length needs to be used for higher order modes to obtain optimal SNR in an FSOI system.

Analysis and design of process dynamics using spectral methods

Walsh, Ashley Michael. — 2010-10-26T00:00:00Z

Analysis and Enhancement of Communication Behaviour in Children with Cerebral Palsy

Tait, Kathleen J. — 2007-08-24T00:00:00Z

Analysis and modelling of dielectric response in power transformer insulation

Yao, Zheng Tong. — 2007-08-24T00:00:00Z

Analysis of Australian elapid snake venoms for the discovery and development of new human therapeutics

Earl, Stephen — 2011-03-15T00:00:00Z

Analysis of cadherin and receptor tyrosine kinase interactions: trafficking and function.

Bryant, David Michael — 2008-11-21T00:00:00Z

In multicellular organisms, sheets of polarized epithelial cells provide a functional barrier between the external world, and the internal milieu. One protein critical for epithelial polarization and cell-cell adhesion is the epithelial cadherin, or E-cadherin protein. Although the adhesive function of E-cadherin is mediated primarily at the cell surface, E-cadherin undergoes complex internalisation and intracellular trafficking in response various different physiological circumstances. The mechanisms that regulate these pathways remain poorly defined. A central aim of this thesis has been to characterise the pathways and machinery that regulate internalisation of E-cadherin. To this end, mammary adenocarcinoma (MCF-7) cells were examined for E-cadherin trafficking, cell-cell adhesion and morphogenetic status in response to stimulation with various growth factors, primarily fibroblast growth factors (FGFs), which play a key role in mammary development and tumourigenesis. FGF stimulation induced the cointernalisation of E-cadherin and the FGF receptor 1 (FGFR1) into early endosomes, resulting in disrupted cell-cell adhesion. FGFR1 translocated to the nucleus in response to a number of stimuli. These studies reveal endocytosis as an initial, requisite step for the subsequent nuclear translocation of FGFR1 by a still uncharacterised pathway. In a novel finding, the E-cadherin-catenin complex was found to conversely regulate signalling and nuclear translocation of FGFR1 in response to ligand. The internalisation pathway for E-cadherin was found to be independent of caveolin-1, yet only displayed partial dependence on classical clathrin-based endocytic pathways, suggesting the potential of either an unusual endocytic pathway or of multiple internalisation pathways. Interestingly, stimulation of the same cell type with an alternate growth factor, epidermal growth factor (EGF) resulted in internalisation of free E-cadherin through macropinocytosis, without disruption to polarized adhesion. Surprisingly, neither of these pathways resulted in a significant reduction in E-cadherin protein levels. Additional analyses of cellular machinery revealed recruitment of members of the sorting nexin (SNX) protein family to E-cadherin-containing vesicles, whereby SNX1 was noted to regulate intracellular sorting of E-cadherin away from the degradative pathway. Analysis of the morphogenetic effect of cadherin internalisation revealed that whilst a number of stimuli were able to induce internalisation of E-cadherin, stimulation with FGF alone was able to induce scattering and migratory activity in MCF-7 cells. Curiously, this behaviour was independent of E-cadherin expression, revealing a novel partial epithelial-mesenchymal transition (pEMT) in response to FGF. These findings underscore the notion that E-cadherin is able to utilise multiple pathways for internalisation, depending on growth factors, and on cellular context. Finally, studies using epithelial cell lines embedded in extracellular matrix to form glandular like structures suggest the potential for intracellular trafficking of E-cadherin to be studied in 3-D using epithelial cell culture models. These studies reveal the existence of alternate pathways for E-cadherin internalisation and provide an important insight in the differential regulation of E-cadherin localization and function under different physiological circumstances.

Analysis of Competitive Interactions in a Tropical Marine Epifaunal Community

Erin O'Leary — 2008-11-05T00:00:00Z

Analysis of Conservation and Chromatin Structure at Metazoan Splice Sites

Satu Nahkuri — 2010-11-22T00:00:00Z

The regulation of alternative splicing remains a mystery, as introns often harbour numerous decoy motifs similar to the consensus splice site sequence, and most auxiliary splicing enhancing and inhibiting sequences targeted by splicing factors are poorly conserved. Conversely, the conservation level of exonic and intronic sequences flanking alternative splice sites is significantly higher than that around constitutive splice sites. One such highly conserved sequence located in the mammalian serotonin receptor gene is likely targeted by the HBII-52 small nucleolar RNA (snoRNA) and implicated in the regulation of alternative splicing. Given the enormous size of the non-coding transcriptome, the possibility that many non-spliceosomal non-coding RNAs contribute to the outcome of alternative splicing by hybridizing the precursor messenger RNA (pre-mRNA) was considered in this thesis. Splicing, transcription and chromatin are intricately coupled, as demonstrated by the observations that various histone modifications exert a profound effect on transcription and alternative splicing, that dozens of crucial chromatin associated factors double as splicing or transcription factors, and that nucleosomes associated with genomic DNA at transcription start and termination sites can occlude target motifs from regulatory proteins. For example, the precise positioning of the +1 nucleosome at the transcription start site is implicated in the modulation of transcription initiation, while the backtracking of elongating RNA polymerase II (RNAPII) upon encountering this nucleosome is suggested to prompt the creation of transcription initiation RNAs (tiRNAs) via 5’ cleavage of the newly transcribed pre-mRNA. In this thesis, two parallel lines of research were pursued to investigate how alternative splicing and splicing in general are regulated in animals. Firstly, sequences flanking mammalian and insect splice sites were analysed in search for highly conserved blocks that could serve as potential landing pads for cis- or trans-acting regulatory non-coding RNAs. The analysis revealed two putative mutually exclusive cis-acting RNA structures in the homothorax pre-mRNA of Drosophila melanogaster, and thousands of conserved intronic blocks near splice sites (CIBSs) in mammals. Intriguingly, the human genes harbouring CIBSs were associated with chromatin modification and maintenance. The mammalian conservation study also led to the discovery of an unannotated snoRNA gene, SNORD119, which resides in the intron of a core splicing factor (SNRPB, SmB) and likely guides the methylation of ribosomal RNA. Evolutionary analysis revealed a link between SNORD119 and the HBII-52 snoRNA, suggesting that the duplication of the protein-coding host gene had given rise to an independently evolving copy of SNORD119, which gained a new function as a splicing regulator after the divergence of marsupials from the mammalian lineage and is currently known as HBII-52. The second line of study was an analysis of nucleosome positioning with respect to splice sites. For this purpose, whole genome nucleosome density libraries derived from human and medaka ChIP-Seq studies were bioinformatically reassessed. Contrary to the prevailing assumption that the location of nucleosomes with respect to the underlying gene structure elsewhere than at transcription start and termination sites is random, this analysis showed that nucleosomes in the body of genes are preferentially positioned at vertebrate exons in somatic and sperm cells. The observed elevated average nucleosome occupancy at internal exons is independent of the modification status of the nucleosome, the GC content of the exon, and the expression level of the gene. Importantly, the finding indicates that the location of exons is recorded in the epigenetic structure of the genome and can be inherited, while the nucleotide bias observed at synonymous substitutions and codon usage may be driven by factors affecting DNA curvature and potential for nucleosomal association. It also creates a putative link between regulatory RNAs and the epigenetic control of splicing patterns, since there is increasing evidence that regulatory RNAs guide chromatin-modifying enzymes to their sites of action. This thesis also discusses a novel class of small nuclear non-coding RNAs, termed spliRNAs, that terminate exactly at the 3’ ends of spliced exons in sense with the pre-mRNA in a wide variety of animals, tissues and cell lines, and presents evidence that suggests that spliRNAs are derived from many, if not most, splice sites. As spliRNAs and tiRNAs feature similar length distribution, cellular location and expression profile, it is proposed that they have a common biogenesis. In this model, RNAPII elongation is retarded by a strictly positioned exonic nucleosome, possibly containing histone H3 trimethylated at lysine 36 (H3K36me3), to generate spliRNAs, and by the +1 nucleosome to generate tiRNAs. Taken together, these findings support the notion that epigenetic regulation operates at an exonic level rather than only at a genic level. Future studies will show whether spliRNAs serve as vectors for epigenetic information.

Analysis of coupling, guiding and radiation mechanisms on several microwave structures

Yau, Desmond. — 2007-08-24T00:00:00Z

Analysis of early life history stages of the saucer scallop Amusium balloti (Bernardi, 1861) : impacts on the development of hatchery practices

Wang, Sizhong — 2008-11-21T00:00:00Z

Analysis of Gas and Water Production Pathways in Coal Seams

Emma Kinnon — 2010-11-15T00:00:00Z

Understanding gas flow pathways in coal seams will assist in optimising well placement and design for gas drainage in underground coal mines, coal bed methane (CBM) production in commercial fields and, in the future, enhanced CBM recovery with CO2 geosequestration. In this study, drilling, production and geological data from a CBM field in the Bowen Basin, Queensland, were analysed to determine how geology affected production rates over time. The study field produced from medium radius surface to in-seam wells, consisting of a vertical production well intersected most commonly by two lateral wells. Basic geological and gas data were provided by the company and analysed in this thesis, along with the development of well performance indicators, well path analysis, and an investigation into the origins of the gas and water determined using stable isotopes. Daily gas production data were averaged over yearly intervals and contoured for two coal seams across the field to illustrate the variability in gas production rates over a four year period relative to the geological setting. Gas production is variable with distinct domains of high and moderate production rates for the examined period, which reflects geological features across the field, in particular faults, folds and seam splits. The seams dip basinward, and are gently folded along strike into a syncline and anticline, which is separated by a large normal fault that marks a boundary between production domains. For one of the target seams, a master seam split occurs, resulting in elevated mineral matter content and separation of the seam reservoir. A number of smaller normal faults also occur across the anticline. The high production domain occurs north of the fault where gas reservoir size is greater due to higher gas contents in the syncline combined with greater net coal for both seams; the moderate gas production domain occurs south of the fault where gas contents are slightly lower across the crest of the anticline. Little communication occurs between these two distinct areas, and this compartmentalization was established by examining the geochemistry of the water and gas. Stable isotope analysis and water quality tests, including anions, cations and trace elements, were conducted on water samples from the two producing coal seams across the study field to assess zones of recharge, water mixing and pathways. The stable isotope analysis showed that production waters with higher δD and δ18O compositions were associated with areas of higher water production and shallower depths. Lower δD and δ18O compositions, and in particular those that lie above the GWL on the δD vs δ18O graph are generally associated with low water production and high gas production. The water quality analysis showed that waters with lower sodicity and bicarbonate concentrations were associated with high water production and waters with higher sodicity and bicarbonate concentrations were associated with high gas production. The presence of higher bicarbonate concentrations and lower δD and δ18O compositions in the high gas production domain suggests that biogenic gas could have been generated in this area, and is confirmed by the isotopic analysis of the methane. Stable isotope and composition analyses were undertaken on gas samples collected from selected wells in the study field. Gas compositions were consistent across the field with all CH4 composition measurements over 95% and CO2 compositions 1.6% or less. The results from the stable isotope analysis showed that biogenic gas was produced at shallow depths, and the ratio of thermogenic to biogenic CH4 increased with depth. Wells with the highest gas production have a well depth of between 200m and 300m, produce gas that is a mixture of biogenic and thermogenic gas and have larger CO2-CH4 carbon isotopic fractionations from 60.8‰ to 62.9‰. Areas of recharge had smaller isotopic fractionations ranging from 48.6‰ to 57.6‰.

Analysis of growth hormone receptor signalling in vivo - transgenic mouse models

Rowland, Jennifer Elizabeth. — 2011-08-25T00:00:00Z

Analysis of Information Flows within Small World Networks and the Effect on Financial Prices

Bowden, Mark P. — 2008-04-10T00:00:00Z

Analysis of Interacting Partners of GmNARK (Glycine max Nodule Autoregulation Receptor Kinase)

Akira Miyahara — 2008-11-18T00:00:00Z

Analysis of interactional strategies and reciprocal positions leading to a successful discussion in French

Julien Chartier — 2011-12-16T00:00:00Z

What constitutes successful participation in discussion in French? The project combines qualitative and quantitative methods to determine what behaviours constitute successful participation in French debate among learners of French. After group discussions on polemical topics among advanced learners of the language were recorded in Australia, a group of French age-peers judged the exchanges on their relative success and on aspects of interactional behaviour including the extent to which participants advanced debate, dominated and/or supported each other. These aspects were identified prior to the evaluation through a comparative analysis of definitions of a successful and a failed discussion as provided by the participants. The Francophone assessments of the recordings were then analysed to determine which of these aspects correlated with the overall success of the exchange. Building on these results, and drawing on the principles of cross-cultural pragmatics, a multidimensional interactionist analysis of the most and least successful exchanges was undertaken to identify interactional strategies contributing to the success or failure of the exchanges. This involved focussing on the various phenomena and behaviour observable in the discussions judged most successful but absent in the least successful discussions, analysing the waveform representations of the audio-recordings to determine the sound atmosphere, analysing non-verbal behaviour, and undertaking a detailed micro-analysis of the transcription of these exchanges. Results showed that advancing debate through advancing and challenging opinions was most likely to lead to the Francophones judging the discussions as successful. The most successful discussions showed participants adopting a wide range of interchangeable interactional positions in which all could successively take the lead in discussion, and consistently questioning and elaborating opinions, thus placing a clear emphasis on the co-construction of ideas. Least successful discussions as seen by the Francophones showed greater concern for facework strategies and followed a stable pattern of opinions being offered in turn but not negotiated, leading to agreement rather than debate. The sound and visual atmosphere of the discussion was also directly connected to the success of the discussion: the non-verbal behaviour analysis showed that participants in successful discussions displayed an increased use of hand gestures and maintained visual contact between the participants while the waveform analysis underlined situations of brouhaha as a recurring component of the most successful discussions. The project departs from previous studies by focusing on discussion in French as a multilayered cultural practice and therefore undertaking a multidimensional analysis to ascertain the elements that correlate with its success or failure. The findings of the project will provide a better understanding of the cultural specificity of different interactional styles, and of the cultural anchoring of interactional strategies contributing to the success or failure of a discussion. It will serve as a potential basis for teaching interactional skills and pragmatic competence in French as a second language.

Analysis of kinesin light chain 1 isoforms

McCart, Amy Ellen — 2007-08-24T18:44:26Z

Analysis of microsatellite loci in natural and cultured populations of tropical abalone, Haliotis asinina

Selvemani, Maria John Peter. — 2011-08-08T00:00:00Z

Analysis of Optical Flow for Indoor Mobile Robot Obstacle Avoidance.

Tobias Low — 2010-07-05T00:00:00Z

This thesis investigates the use of visual-motion information sampled through optical flow for the task of indoor obstacle avoidance on autonomous mobile robots. The methods focus on the practical use of optical flow and visual motion information in performing the obstacle avoidance task in real indoor environments. The methods serve to identify visual-motion properties that must be used in synergy with visual-spatial properties toward the goal of a complete robust visual-only obstacle avoidance system, as is evidently seen within nature. A review of vision-based obstacle avoidance techniques shows that early research mainly focused on visual-spatial techniques, which heavily rely on various assumptions of their environments to function successfully. On the other hand, more current research that looks toward the use of visual-motion information (sampled through optical flow) tends to focus on using optical flow in a subsidiary manner, and does not completely take advantage of the information encoded within an optical flow field. In the light of the current research limitations, this thesis describes two different approaches and evaluates their use of optical flow to perform the obstacle avoidance task. The first approach begins with the construction of a conventional range map using optical flow that stems from the structure-from-motion domain and the theory that optical flow encodes 3D environmental information under certain conditions. The second approach investigates optical flow in a causal mechanistic manner using machine learning of motor responses directly from optical flow - motivated from physical and behavioural evidence observed in biological creatures. Specifically, the second approach is designed with three main objectives in mind: 1) to investigate whether optical flow can be learnt for obstacle avoidance; 2) to create a system capable of repeatable obstacle avoidance performance in real-life environments; and 3) to analyse the system to determine what optical flow properties are actually being used for the motor control task. The range-map reconstruction results have demonstrated some good distance estimations through the use of a feature-based optical flow algorithm. However, the number of flow points were too sparse to provide adequate obstacle detection. Results froma differential-based optical flow algorithm helped to increase the density of flow points, but highlighted the high sensitivity of the optical flow field to the rotational errors and outliers that plague the majority of frames under real-life robot situations. Final results demonstrated that current optical flow algorithms are ill-suited to estimate obstacle distances consistently, as range-estimation techniques require an extremely accurate optical flow field with adequate density and coverage for success. This is a difficult problem within the optical flow estimation domain itself. In the machine learning approach, an initial study to examine whether optical flow can be machine learnt for obstacle avoidance and control in a simple environment was successful. However,there were certain problems. Several critical issues which arise with the use of a machine learning approach were highlighted. These included sample set completeness, sample set biases, and control system instability. Consequently, an extended neural network was proposed that had several improvements made to overcome the initial problems. Designing an automated system for gathering training data helped to eliminate most of the sample set problems. Key changes in the neural network architecture, optical flow filters, and navigation technique vastly improved the control system stability. As a result, the extended neural network system was able to successfully perform multiple obstacle avoidance loops in both familiar and unfamiliar real-life environments without collisions. The lap times of the machine learning approach were comparable to those of the laser-based navigation technique. The the machine learning approach was 13% slower in the familiar and 25% slower in the unfamiliar environment. Furthermore, through analysis of the neural network approach, flow magnitudes were revealed to be learnt for range information in an absolute manner, while flow directions were used to detect the focus of expansion (FOE) in order to predict critical collision situations and improve control stability. In addition, the precision of the flow fields was highlighted as an important requirement, as opposed to the high accuracy of flow vectors. For robot control purposes, image-processing techniques such as region finding and object boundary detection were employed to detect changes between optical flow vectors in the image space.

Analysis of post-translational modification sites in the aryl hydrocarbon receptor

Keyur Dave — 2009-08-11T00:00:00Z

The dioxin receptor (DR), a transcription factor with basic-helix-loop-helix/PERARNTSIM (bHLH/PAS) homology domains, is activated by toxic xenobiotic ligands leading to severe physiological disturbances most of which are due to deregulation of receptor’s central role in normal development. Activation mechanisms of DR in the presence of exogenous or endogenous ligands are poorly understood. Elucidation of factors involved in the activation of the receptor would assist not only in development of an optimal measure for risk assessment of levels of common environmental pollutants but also in providing novel targets for therapeutic interventions. Posttranslational modifications (PTMs) play an indispensable role in all major signal transduction pathways by increasing the inventory of chemical modifications beyond those already present in the side-chains of common amino acids. Thus, by simple on/off or complex patterns generated by these PTMs, they control a myriad of different biological outcomes. Numerous studies that have suggested an important role of posttranslational modifications in DR activation has prompted a search in this direction, however, apart from phosphorylations at Ser36 and Ser68 no other PTM sites are known. Advanced mass spectrometry (MS)-based characterisation of PTMs is an established technique that can comprehensively provide an accurate cast of all PTM variants and their locations on a protein. This thesis reports the first MS-based comprehensive characterisation of all PTM sites of the purified latent DR and preliminary analysis of identified PTM sites of the activated DR in response to developmental signals (suspension-activated DR) and signals leading to toxic outcomes (ligand-activated DR). The PTM map of the latent DR revealed from this study comprises of 25 phosphorylations, 4 monomethyl-lysines, 2 dimethyl-lysines, 1 O-acetyl-serine and 2 O-sulfono-serines. Most of the phosphorylations and other PTMs were present in the conserved regions of the protein. Investigation of the activated samples of the receptor revealed loss of the above repertoire of modifications and possible presence of some rarer modifications such as O-acetyl-serines in suspension-activated instead of O-sulfonations and pyrophosphorylation at Ser716 in both suspension- as well as ligand-activated DR. A comprehensive mutagenesis study is in progress to understand the functional consequence of each of these modification sites and unravel the functional posttranslational system in DR signalling.

Analysis of protected area management effectiveness evaluation data and its application for increasing understanding of management

Josephine Kelman — 2011-05-19T00:00:00Z

The number of protected area management effectiveness evaluations has been growing in response to calls for increased accountability and transparency in management. Thousands of site assessments have been conducted globally to build understanding of the protected area estate. It is imperative for biological conservation to have an understanding of the relative success of protected areas given that they are recognised as the cornerstone of conservation efforts globally. This dissertation uses the New South Wales, Australia, State of the Parks, which is one of the most comprehensive network-wide assessments ever conducted. The State of the Parks management effectiveness evaluation collected data on a full suite of park attributes, resource inputs and management practices, with the aim of better understanding management across the park network. This evaluation was also stimulated by the need to be accountable to stakeholders and by a desire for continuous improvement in management. The dataset that resulted from the State of the Parks management effectiveness evaluation was large. It collected information on 774 parks in the reserve network. The main objectives of this research were to develop a suitable method of analysis that provided an appropriate means of analysing and presenting the State of the Parks data to explain and interpret the factors most strongly influencing (driving) management effectiveness in the NSW protected area network. A review of existing management effectiveness evaluations revealed that little documented information on analysis methods was available. Broader review of the literature found that this was also a common problem in program evaluation. In protected area evaluation where information was available, the most common forms of analyses were summative statistics used to describe the data, and bivariate correlations used to understand the relationships between variables of interest. In-depth multivariate analysis of relationships between multiple variables was lacking. This also translated to a lack of understanding of the factors that most strongly influence management effectiveness. To fulfill the objective of understanding the driving influences of management effectiveness a series of analyses were conducted. The initial analysis was exploratory and had the benefit of using the majority of the State of the Parks data which could potentially have remained underutilized. A base analysis using the techniques applied in previous management effectiveness evaluations was also conducted to describe the data and to explain whether NSW PWS was achieving its management mandate and which management actions were important in achieving outcomes. A problem arose after the base and exploratory analysis in presentation of the data. The complexity and sheer extent of the data meant that some type of simplification was required so that it could be sufficiently understood by a range of audiences. A mathematical metric was used to simplify the data combining the results of the key management areas (i.e. General Administration, Natural Heritage, Cultural Heritage and Visitor Management) into single scores, which provided a relative measure of performance. These data were also presented spatially to enhance communication potential. It was found that NSW PWS was meeting its management mandate for the majority of protected areas. The main factors influencing management effectiveness were the landscape context of parks and the relative planning and staff time allocations. The NSW PWS resource allocations were found to correlate to high levels of contextual pressures, namely high visitation, high numbers of neighboring properties, the size and age of the park. This demonstrates, with the use of park typologies, that it is possible to define characteristics of parks and the associated expectations of performance using a set of key criteria. In current conservation and natural resource management the focus has shifted to a landscape scale. The finding of this thesis that landscape context is a driving influence on the ability to manage protected areas effectively in New South Wales adds weight to the argument for conservation that stretches beyond the boundaries of protected areas. Perhaps more importantly, it demonstrates that with management input and actions that directly address landscape pressures conservation can be successful in less than optimal situations.

Analysis of Snore Sound Pitch and Total Airway Response in Obstructive Sleep Apnoea Hypopnoea Detection

Asela S Karunajeewa — 2010-03-25T00:00:00Z

Obstructive sleep apnoea hypopnoea syndrome (OSAHS) is a highly prevalent disease in which upper airways are collapsed during sleep, leading to serious consequences. The reference standard of clinical diagnosis, called Polysomnography (PSG), requires a full-night hospital stay connected to over 15 measuring channels requiring physical contact with sensors. The vast quantity of physiological data acquired during the PSG has to be manually scored by a qualified technologist to assess the presence or absence of the decease. The PSG is inconvenient, time consuming, expensive and unsuited for community screening. The limited PSG facilities around the world have resulted in long waiting lists and a large fraction of patients remain undiagnosed at present. There has been a flurry of recent activities in developing a portable technology to resolve this need. All the devices have at least one sensor that requires physical contact with the subject. Unattended systems have not led to sufficiently high sensitivity/specificity levels to be used in a routine home monitoring or a community screening exercise. OSAHS is a sleep respiratory disorder principally caused by functional deficiencies occurring in the upper airways during sleep. These conditions and the reduced muscle tone during sleep, cause the muscles in the upper airways to collapse partially or completely thus resulting in episodes of hypopnoea and apnoea respectively. During the process leading to collapse of upper airways, upper airways act as an acoustic filter frequently producing snoring sounds. The process of snore sound production leads us to hypothesise that snore sounds should contain information on changes occurring in the upper airways during the OSAHS. Snoring almost always accompanies the OSAHS and is universally recognised as its earliest symptom. At present, however, the quantitative analysis of snore sounds is not a practice in clinical OSAHS detection. The vast potential of snoring in the diagnosis/screening of the OSAHS remains unused. Snoring-based technology opens up opportunities for building community-screening devices that do not depend on contact instrumentation. In this thesis, we present our work towards developing a snore–based non-contact instrumentation for the diagnosis/screening of the OSAHS. The primary task in the analysis of Snore Related Sounds (SRS) would be to segment the SRS data as accurately as possible into three main classes, snoring (voiced non-silence), breathing (unvoiced non-silence) and silence. A new algorithm was developed, based on pattern recognition for the SRS segmentation. Four features derived from the SRS were considered to classify samples of the SRS into three classes. We also investigated the performance of the algorithm with three commonly-used noise reduction (NR) techniques in speech processing, Amplitude Spectral Subtraction (ASS), Power Spectral Subtraction (PSS) and Short Time Spectral Amplitude (STSA) Estimation. It was found that the noise reduction, together with a proper choice of features, could improve the classification accuracy to 96.78%. A novel model for the SRS was proposed for the response of a mixed-phase system (total airways response, TAR) to a source excitation at the input. The TAR/source model is similar to the vocal tract/source model in speech synthesis and is capable of capturing the acoustical changes brought about by the collapsing upper airways in the OSAHS. An algorithm was developed, based on the higher-order-spectra (HOS) to jointly estimate the source and the TAR, preserving the true phase characteristics of the latter. Working on a clinical database of signals, we show that the TAR is indeed a mixed phased signal and second-order statistics cannot fully characterise it. Nocturnal speech sounds can corrupt snore recordings and pose a challenge to the snore-based OSAHS diagnosis. The TAR could be shown to detect speech segments embedded in snores and derive features to diagnose the OSAHS. Finally presented is a novel technique for diagnosing the OSAHS, based solely on multi-parametric snore sound analysis. The method comprises a logistic regression model fed with a range of snore parameters derived from its features — the pitch and Total Airways Response (TAR) estimated using a Higher Order Statistics (HOS) based algorithm. The model was developed and its performance validated on a clinical database consisting of overnight snoring sounds simultaneously recorded during a hospital PSG using a high fidelity sound recording setup. The K-fold cross validation technique was used for validating the model. The validation process achieved an 89.3% sensitivity with 92.3% specificity (the area under the Receiver Operating Characteristic (ROC) curve was 0.96) in classifying the data sets into the two groups, the OSAHS (AHI >10) and the non-OSAHS. These results are superior to the existing results and unequivocally illustrate the feasibility of developing a snore-based non-contact OSAHS screening device.

Analysis of SRY and SOX Gene Activities in the Regulation of Testis Formation in the Mouse.

Mr Juan Carlos Polanco-Barrero — 2008-09-16T00:00:00Z

Analysis of the binding properties and functions of scabies mite serine proteases

Reynolds, Simone Louise — 2012-12-14T09:38:22Z

Analysis of transcription factor gene expression in the developing and adult nervous system of the gastropod haliotis asinina

O'Brien, Elizabeth Katherine — 2008-09-18T00:00:00Z

Analytical Methods for Improving Earthmover Tyre Performance

Tilman Rasche — 2012-05-18T00:00:00Z

The mining industry commonly uses qualitative risk analysis methods to analyse hazards and business risks. These methods suffer from a number of limitations. The use of language required to describe risk events creates inherent subjectiveness. Assumptions, resultant model uncertainty and natural or statistical variability make scenario comparisons difficult. This thesis demonstrates how quantitative risk analysis, as an alternative can be successfully used to overcome these shortfalls. An industry survey confirmed the infrequent application of quantitative methods across the mining industry. Given the high risk/cost nature of the industry, adopting a more data focussed management approach would benefit many mine management functions. The value of quantitative risk analysis was successfully illustrated by an earthmover tyre management case study. A holistic summary of issues, considerations and variables around optimal tyre asset, technical and operational tyre management was developed. Tyre performance data was analysed using ‘grouped failure analysis’. Grouped failure analysis was found to provide more representative tyre data statistics as it does not assume that tyres enter service in ‘as good as new’ or equal condition when rotated across different vehicle positions throughout their lifecycle. This is a significant improvement as wear characteristics are now reflected more accurately for subsequent tyre life cycle modelling and decision making. Three decision making models simulating tyre rotation using Weibull analysis were developed. Rotation intervals optimising tyre operating cost, tyre demand and tyre wear were calculated. These are fundamental drivers of successful tyre management and the methods developed in this thesis have direct application to tyre management. There are no qualitative methods currently available capable of delivering such decision-making ability. Given the ongoing mining boom, quantitative risk analysis approaches to better manage the scarce and expensive earthmover tyre supply, or any other engineering asset will become increasingly important.

Analytical methods for stochastic discrete-time metapopulation models

Fionnuala Buckley — 2011-04-11T00:00:00Z

The term `metapopulation' is used to describe a population of individuals that live as a group of local populations in geographically separate, but connected, habitat patches. The patches are situated within an otherwise uninhabitable landscape which dispersing individuals traverse in search of suitable habitats. The central concepts associated with metapopulation dynamics are that of \textit{local extinction}, the extinction of a local population, and \textit{recolonisation}, where migrants establish new populations in unoccupied (empty) patches. The relationship between the processes of local extinction and colonisation is therefore an important consideration when formulating mathematical metapopulation models. We shall consider a particular type of metapopulation dynamic where extinction events and colonisation events are assumed to occur during separate time periods, or \textit{phases}, that alternate over time. This seasonal dynamic may be thought of as an annual cycle, say, where local populations are prone to extinction during winter and new populations establish during spring. In particular, we model the number $n_t$ of occupied patches at time $t$ as a discrete-time Markov chain ($\nt: t=0,1,2,\dots)$ with transition probabilities that alternate according to the seasonal phases. The models are naturally constructed in a discrete-time setting due to the assumed dynamic, however it will be made clear that whether the Markov chains are time-homogeneous (where the population census is taken after every cycle) or time-inhomogeneous (where the census is taken after each seasonal phase) depends on the monitoring scheme under investigation. We present a number of metapopulation models with the assumed seasonal dynamic where, in particular, the local extinction process is modelled in the same way in each case whilst the colonisation process is modelled according to various means of propagation. We assume that each local population goes extinct with the same, constant, probability, and that all events are independent. Hence, the number of extinction events that occur during the extinction phase is binomial. For metapopulation networks with a finite number $N$ of patches, we also assume that the number of colonisation events that occur during the colonisation phase is \mbox{binomial}. We investigate both state-independent and state-dependent colonisation probabilities, where the former is defined with a constant probability and the latter depends on the current number of occupied patches. Metapopulation models defined with a state-independent colonisation process are referred to as \textit{mainland models} because empty patches are thought to be colonised by migrants from an outside source population (the `mainland') in this case. For models defined with state-dependent colonisation processes, we refer to these as \textit{island} \mbox{\textit{models}} when colonists originate from occupied patches (islands) or \textit{mainland-island models} when both types of colonising behaviour are assumed. The overall two-phase model is called a \textit{chain \mbox{binomial} metapopulation model} since the extinction and colonisation processes together define a sequence of binomial random variables. We also investigate similar models but for networks with infinitely-many patches ($N=\infty$); the number of colonisation events is modelled as a Poisson random variable in such cases. The discrete-time Markov chain approach is well established in the applied metapopulation literature, however models of this type are usually examined via numerical methods and simulation. The models presented here are accompanied with extensive analytical treatments. For most of our finite-patch models, we evaluate conditional state distributions explicitly and use these distributions to establish convergence results (in the sense of convergence in distribution). These results include a law of large numbers, which identifies an approximating deterministic trajectory, and a central limit law, which establishes that the scaled fluctuations about the deterministic trajectory have an approximate normal (Gaussian) distribution. We show that the infinite-patch models are equivalent to branching processes. This body of work culminates by presenting limit theorems for discrete-time metapopulation models. First, we prove limit theorems for a general class of inhomogeneous Markov chains that exhibit the particular property of density dependence. These theorems include a law of large numbers and a central limit law (in the sense of convergence in finite-dimensional distribution), which establishes that the scaled fluctuations about this deterministic trajectory have an approximating autoregressive structure. Second, we apply these results to our Markov chain metapopulation models (both finite-patch and infinite-patch) where we demonstrate that the limiting behaviour of any of our metapopulation models with density-dependent phases can be evaluated explicitly, even in situations where a conditional state distribution could not be determined.

AN ANALOGUE STUDY OF PARENT-ADOLESCENT CONFLICT: PROCESSESS AND OUTCOMES

Atkin, Sharon Doreen — 2008-11-21T00:00:00Z

Conflict between parents and their adolescents has been widely acknowledged as a necessary forum for adolescents to develop their sense of self and make a successful transition into adulthood and as an important, and at times damaging, factor in adolescent adjustment. What constitute the negative and positive aspects of parentadolescent conflict and in what ways such interactions contribute to parent-adolescent relationships and adolescent adjustment is an important progression for such research. It would seem a positive step to begin with experimental investigations where aspects of parent-adolescent conflict communication can be controlled. Such an approach has a greater likelihood of providing information about which types of conflict are associated with which types of outcomes for adolescents and their families. The purpose of this study was to investigate specific styles of parent-adolescent conflict (coercion, demand/withdraw and mutuality) and the processes that link such conflict with parent-adolescent relationships and adolescent adjustment. An analogue approach was incorporated to capture the dynamics of the differing conflict styles (audio-tapes of simulated parent-adolescent conflict discussions), along with questionnaire approaches in regard to conflict behaviour. Participants were 58 two-parent family triads (mother, father, adolescent) and 27 singlemother family dyads (mother, adolescent). The adolescents were aged 12 to 16 years. Participants responded to questionnaires relating to their perceptions of, and affective responses to, the taped discussions. Family relationships were assessed in terms of the affection in their relationships, and parenting behavior (psychological control; behavioural control and acceptance). Adolescent adjustment was assessed in terms of internalising and externalising behavior and self-esteem. The validity of using an analogue method for research into parent-adolescent conflict was supported. In general, participants were able to identify the characteristics of the conflict styles and discriminate between them. The mutual style was perceived as the most likely to be resolved and the least likely to get worse, and the coercive style was perceived as the least likely to be resolved and the most likely to get worse. These results were more marked for the two-parent family members, as compared to the participants from single-mother families, who discriminated less between the styles. Based on an adaptation of Grych and Finchams Cognitive Contextual framework, it was proposed that adolescents understanding and experience of parent-adolescent conflict would be associated with their perceptions of their relationships with their parents which would in turn lead to particular adjustment outcomes. It was also proposed that for adolescents, either typically experiencing negative conflict interactions with their parents, or experiencing heightened negative affect during conflict interactions, would be associated with poorer relationships with their parents, which in turn would be associated with less positive adjustment outcomes. Mediation analyses allowing for multiple mediators were conducted. Results indicated that in the two-parent families, mothers and adolescents perceptions of their relationships mediated the associations between the typicality of the mother-adolescent coercive discussions and adolescent externalising behaviour and self-esteem. Also, fathers and adolescents perceptions of their relationships mediated the associations between the typicality of father-demands/adolescent-withdraws conflict and adolescents internalising and externalising behavior and self-esteem. There were no such associations found for the level of reported affect in relation to the taped discussions. Conversely, for the single-mother families, the typicality of the taped discussion did not show strong associations with mother-adolescent relationships and adolescent adjustment; however, perceptions of relationship quality mediated the relations between the level of affective response to the conflict and adolescent adjustment. Specifically, adolescents perceptions of their relationships mediated the associations between the adolescents levels of anger for single-mother-demands/adolescent-withdraws discussions and adolescents internalising behaviour. These adolescents perceptions of their relationships with their single mothers also mediated the associations between adolescents expectation that the mother-demands/adolescent-withdraws discussions would get worse and their self esteem. These results were discussed in terms of the current literature and the future directions of research into parent-adolescent conflict. The associations between parent-adolescent conflict, family relationships and adolescent adjustment in two-parent families revealed that the conflict dynamics that were associated with family relationships and adolescent adjustment were different for mother-adolescent and father-adolescent conflict. Results also indicated that single-mothers and their adolescents perceive conflict differently from married mothers and their adolescents. Future investigations could be aimed at exploring differences in conflict processes and outcomes between married mothers and fathers with their adolescents and married mothers and single-mothers with their adolescents in more detail, and with larger samples.

An analysis of ex-dividend day abnormal trading volumes and share price changes in the Australian equity market

Bellamy, David Ewan. — 2007-08-24T00:00:00Z

An analysis of fee-for-service medical practice in Australia : results for general practitioner markets

Connelly, Luke Brian. — 2010-12-15T00:00:00Z

An analysis of female labour supply and earnings in small islamic country: evidence from Brunei Darussalam

Teo, Siew Yea. — 2007-08-24T00:00:00Z

An analysis of intermediate filament end domains

Friend, Lexie Robyn. — 2007-08-24T00:00:00Z

An Analysis of Islamic Conceptualisations of Press Freedom in Malaysia

Nerawi Sedu — 2010-02-04T00:00:00Z

This research study investigated the conceptions of press freedom from the Islamic perspective. It examined how certain segments of Malaysian society, including government officers, religious leaders, members of non-governmental organisations (NGOs) and members of political parties, perceive press freedom in their country. Compared to previous studies on media freedom or press freedom in Malaysia, this study offered a comprehensive analysis of variables significantly related to the conceptualisation and practice of press freedom, which include economic development, information and communication technologies (ICTs) and globalisation. One significant difference between this study and previous studies was the specific examination of Islamic conceptions of press freedom, which represents a major contribution to existing knowledge. As Malaysia is a complex multi-racial and multi-religious nation, factors such as national ideologies and cultural values were addressed when examining conceptions of press freedom. Due to the focus of the study, two types of framework were utilised: an Islamic theoretical framework and media theories developed by Western scholars. Methodologically, this study employed an ethnographic approach for analysing Islamic conceptualisations of press freedom. A combination of three qualitative research techniques - in-depth face-to-face interviews, examination of archival documents, and personal observations - was utilised to investigate the issues identified in relation to perceptions of press freedom in Malaysia. In-depth face-to-face interviews involved the participation of staff and members from ten organisations and individuals who were not affiliated with these organisations. The organisations involved in this study were: Ministry of Internal Security Malaysia (MOIS); Institute of Islamic Understanding Malaysia (IKIM); Islamic Da’wah Foundation Malaysia (YADIM); Muslim Youth Movement of Malaysia (ABIM); Pertubuhan Jamaah Islah Malaysia (JIM); Centre for Independent Journalism (CIJ); Suara Rakyat Malaysia (SUARAM); Islamic Party of Malaysia (PAS), People’s Justice Party (PKR); and Puteri UMNO. The archival documents analysed in this study were gathered from these ten organisations. However, due to certain organisational policies and security concerns, personal observations were only conducted at eight organisations, IKIM, YADIM, ABIM, JIM, CIJ, SUARAM, PAS and PKR. The data were analysed using thematic analysis. The results of the data analysis were triangulated to ascertain the extent to which the information obtained was consistent or inconsistent across sources. The findings of the study showed that there were diverse views among respondents on what constitutes an Islamic press freedom in a multi-racial and multi-religious Malaysia. Due to the different levels of Islamic understanding and divergent interpretations of Islam among Muslims, especially among members of political parties, this study also found that the Islamic theory of press freedom is a highly contested concept. More often than not, the respondents of these organisations claimed that Islamic conceptualisations of press freedom should be based on their personal versions of Islam.

An analysis of the nature and quality of friendship relationships in a sample of Australian adolescents

Castan, Beulah. — 2007-08-24T00:00:00Z