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Dryland rivers and hydroclimatic change: past, present and future
No full textThesis by publication.Includes bibliographical references.Chapter 1. Introduction -- Chapter 2. From a sinuous to a straight ‘river of sand’ : the profound response of the dryland Warrego River, eastern Australia, to Holocene hydroclimatic change -- Chapter 3. River response to Holocene hydroclimatic change in the Okavango Panhandle, Botswana -- Chapter 4. Mechanisms of channel avulsion in the Panhandle region of the Okavango Delta, Botswana -- Chapter 5. Threshold responses of dryland rivers to future global hydroclimatic change -- Chapter 6. Discussion -- Appendices.Rivers and wetlands in drylands are vital components of the landscape that provide countless beneficial services to humans and ecosystems. The hydrological and geomorphological diversity of rivers across time and space makes comprehensive understanding of fluvial systems and prediction of future change very difficult. A long-term perspective, however, can improve our ability to assess the sensitivity of dryland rivers to extrinsic forcing, such as climate-driven hydrological (hydroclimatic) changes, and contextualises the natural range of variability defining modern rivers. This thesis aims to understand: 1)how dryland rivers have responded to past hydroclimatic changes, 2) the processes that define the n atural range of variability of modern rivers, and 3) how dryland rivers will respond to future hydroclimatic change. Hydroclimatic change has affected dryland rivers differently around the world,but evidence from eastern Australia and southern Africa suggests a relatively synchronous period of enhanced fluvial activity during the early to mid-Holocene (~8–4 ka) followed by relative quiescence of fluvial activity in the late Holocene. An inter-continental approach allows an improved understanding of how hydroclimatic changes manifest in dryland rivers in very different settings. The fan-shaped alluvial plain of the lower Warrego River in eastern Australia has preserved evidence for large (~160 m), sinuous, laterally migrating palaeochannels that were transporting ~20 times the discharge of the modern river and were active until ~5 ka. The modern Warrego River has a markedly different plan form,with narrower, straighter anabranching channels in the equivalent position on the plain. Similarly, in the Panhandle region of the Okavango Delta, northern Botswana, large (~120 m), sinuous, laterally migrating palaeochannels conveyed up to ~9 times the discharge of the modern system during a periodof enhanced rainfall over the headwaters that lasted until ~3.5 ka. The response of the Okavango Riverto subsequent declining discharge has been to contract considerably and, in the Panhandle, processes of channel adjustment by avulsion now dominate over lateral migration. A range of hydroclimatic drivers,related to orbital variations and climatic teleconnections, have likely been responsible for declining fluvial activity and dramatic transformations of river style in the late Holocene. The geomorphological sensitivity of the Warrego and Okavango rivers to relatively modest Holocene hydroclimatic change highlights that improving understanding of how rivers will respond to future climate change is of critical importance. Prediction of future fluvial change in dryland settings requires consideration of the intrinsic processes of river adjustment and the influence of extrinsic, hydroclimatic forcing on these processes. Catchment aridity strongly influences the geomorphology of Australian dryland rivers. By defining thresholds of aridity and modelling future climatic conditions, this research indicates that many Australian dryland rivers will likely undergo profound changes to their physical character and behaviour over coming decades/centuries, most likely in the form of increased likelihood of flow disconnection and channel breakdown.Mode of access: World wide web1 online resource (x, 238 pages) colour illustrations, maps (some coloured
Exploring lithospheric scale structure in the Southern Yilgarn Craton with 3D magnetotellurics
No full textEmpirical thesis.Bibliography: pages 46-49.Introduction -- Theory -- Data -- Modelling -- Discussion -- Conclusions -- References -- Supplementary data.The electrical structure of the southern Yilgarn Craton is of interest in building an understanding of the pathways for mineralisation at the lithospheric scale. This project uses three dimensional inversion of magnetotelluric data from both broadband and long period stations to investigate an east west traverse of the South West, Youanmi and Kalgoorlie terranes of the Yilgarn Craton in Western Australia. These data are from the Southern Cross magnetotelluric survey. Previous studies in the region focussed on two dimensional modelling, however, phase tensor analysis of these data show a predominantly three dimensional subsurface that varies in strike across the profile. For this study models were produced using 26 stations, four of which contain data from an additional long period survey. The modelling highlights several conductive regions within a predominantly resistive subsurface. One large western conductor dominates the South West Terrane at depth, and a second more conductive feature is observed underneath the Kalgoorlie Terrane. These conductive regions may be associated with various mineralisation events during mantle activity prior to cratonization of the Yilgarn Craton.Mode of access: World wide web1 online resource (v, 56 pages) colour map
Delivering 'valuable' justice: measuring the Impact of law reform advocacy by the not-for-profit legal sector
No full textTheoretical thesis.Bibliography: pages 91-107.Introduction -- 1. Key concepts and methodology -- 2. Protecting NFP law reform advocacy : law and practice -- 3. Legal and economic value of NFP law reform advocacy -- 4. Applying Social Return on Investment (SROI) to law reform advocacy -- 5. Conclusion --Appendix -- Bibliography.In this thesis, I argue that the law reform advocacy work of the Not-for-profit (NFP) legal sector has significant value and should be protected and supported.Current law and practice in Australia do not protect NFP law reform advocacy. Further, funding arrangements restrict or prohibit this important work, and non-legal barriers compound the issue. There is a strong case that NFP legal work should be protected and supported. NFP law reform advocacy has significant legal value in delivering access to justice, and there is clear economic value in that NFP law reform advocacy supports effective and efficient law reform. However, there is a lack of robust supporting evidence. Social return on investment (SROI) is a method that may help fill this gap. An exploratory baseline SROI analysis is conducted with a focus on one component of NFP law reform advocacy. By taking a stakeholder focused approach that measures the social and economic impacts valued by both government and the NFP legal sector, SROI provides the potential to balance economic legitimacy for law reform advocacy with the quest for social justice.Mode of access: World wide web1 online resource (107 pages
Identity has a history: rethinking identity politics through historical discourses of the self
No full textTheoretical thesis.Bibliography: pages 196-214.Introduction -- Literature review and method -- The early period : 1930s-1960s. 1. Women's rights and healthy personalities ; 2. Aboriginal rights and cultural pride -- The late period : 1970s-1980s. 3. Women's rights and sexist power ; 4. Aboriginal rights and colonial power -- Discussion -- Conclusion -- Bibliography.Identity politics has long been accused of fragmenting and destabilising progressive politics,and critiques of its political effects continue unabated in light of its enduring significance. Yet, the majority of these accounts fail to historicise identity, proceeding from metaphysical or psychological definitions that flatten its effects. This thesis takes a poststructuralist approach that conceptualises identity not as some ontological pre-given but as a historically-derived discourse, and thus does not examine what it is but what it does. The aim of this thesis is thus to trace the historical emergence of this discourse in order to move current theorisations about its political effects into a more nuanced, productive avenue.To do so, it considers two social movements in Australia that are often seen as central examples of the rise of identity politics: the women’s rights movement and the Aboriginal rights movement. Engaging in a close reading of the political claims made by activists involved in these movements, it traces the discourses of selfhood through which activists articulated their political demands. More specifically, it takes up the insight that the rise of the term ‘identity’ is actually historically recent and should be understood as part of a broader historical discourse of selfhood, in order to answer the question of how identity politics works.In doing so, this thesis suggests that discourses of selfhood in the 20th century were closely tied to the knowledges being produced by the social sciences in this period, and that the discourse of identity reproduced by activists was likewise enmeshed within these logics. Analysing these political claims reveals three ways that identity politics has historically ‘worked’: by naturalising and thus universalising the individual capacity for agency in terms of recognition, by subsequently politicising human relations as foundational to this agency, and by positing culture as necessary for the development of this agency (and likewise problematising the claim that this capacity was exclusive to Western culture). Ultimately, this demonstrates that the kinds of political claims made possible by identity politics are more extensive than existing accounts allow.Mode of access: World wide web1 online resource (v, 214 pages
Optical and plasmonic coupling in linear and nonlinear regimes
No full textThesis by publication.Bibliography: pages 145-161.1. Introduction -- 2. Surface Plasmons : background and methods -- 3. Plasmonic second harmonic generation -- 4. Phase-matched plasmonic generation using dielectric nonlinearities -- 5. Photonic-plasmonic directional couplers -- 6. Plasmonic-photonic couplers based on spatial adiabatic passage -- 7. Conclusion and future work -- Appendices -- References.Surface plasmon polaritons are electromagnetic surface waves that may be excited at the interface between metallic and dielectric materials. They confine light to subwavelength dimensions, and provide large field enhancement, making them useful for creating compact devices and sensing applications. Unfortunately, surface plasmons are difficult to utilise due to their characteristically large losses. They typically have propagation lengths from microns to hundreds of microns. Surface plasmon-to-optical coupling is also challenging, due to the inherent disparity in the size and wavevector of optical and plasmonic modes. In this thesis,we take two approaches to addressing these challenges.The first approach is to explore second-order nonlinear effects. Nonlinear effects benefit from the plasmon field-enhancement, and can potentially be used to provide gain via parametric amplification. In our study, we experimentally consider the nonlinearity of gold in plasmon-to-plasmon second harmonic generation, as well as the dielectric nonlinearity in lithium niobate. In gold-coated lithium niobate crystals, we explore optical-to-plasmonic processes, using quasi-phase-matching for second harmonic generation, and birefringent phase-matching for parametric down conversion. We find that the large size disparity in optical and plasmonic modes strongly inhibits the efficiency of the nonlinear response, and diminishes the contributions made by phase-matching. We were unable to overcome the plasmonic absorption losses using second-order nonlinear effects in the nanosecond domain.In our second approach, we consider directional coupling between optical and longrange surface plasmon waveguides using numerical methods. We then consider the design of a three-waveguide device, an adiabatic passage coupler with a plasmonic intermediate waveguide. By the use of a dark state, we show that light can be transported through the plasmonic waveguide without suffering plasmonic loss. This is achieved by supressing the surface plasmon amplitude. An analogous device, a digitised adiabatic passage coupler, is characterised experimentally, verifying the tolerance to loss in that design.Mode of access: World wide web1 online resource (xii, 161 pages) diagrams, graphs, table
The evolutionary impact of supermassive black holes on their host galaxies
No full textEmpirical thesis.Bibliography: pages 79-92.1. Introduction -- 2. Selecting AGN in ZFOURGE -- 3. An enhancement of star formation in AGN hosts -- 4. Decoupled black hole accretion and quenching -- 5. A two band approach to isolate the AGN contribution to observed SEDs -- 6. Conclusions and future work -- References -- Appendix.By exploiting the ultra-deep, Ks-band imaging of the FourStar Galaxy Evolution Survey (ZFOURGE), we investigate the evolutionary impact of supermassive black holes (SMBHs) on their host galaxies. We advance this line of research by applying new analyses to a more substantial number of sources, with higher quality photometric redshifts, over a broader redshift range, and down to deeper mass-limits than most studies before it. We begin by supplementing the ZFOURGE galaxy catalogues with data in radio, X-ray, and infrared wavebands to catalogue AGN host galaxies across a broad redshift range of z = 0:2--3:2. We then use these catalogues to construct a mass-complete, luminosity limited sample of AGN to compare their rest-frame U -- V versus V -- J (UVJ) colours and specific star formation rates (sSFRs) to a mass-matched control sample of inactive (non-AGN) galaxies. Our UVJ diagnostics reveal that the AGN tend to be hosted in a lower fraction of quiescent galaxies and a higher fraction of dusty galaxies than the control sample. Using 160 μm Herschel PACS data, we find the mean sSFRs of AGN hosts to be elevated by 0:34+-0:07 dex with respect to the control sample across all redshifts. This offset is primarily driven by infrared-selected AGN, where the mean sSFR is found to be elevated by as much as a factor of ~5. The remaining population, comprised predominantly of X-ray AGN hosts, is found mostly consistent with inactive galaxies, exhibiting only a marginal elevation. To probe the elevated star formation (SF) found in our AGN samples, we turn our attention to infrared-selected AGN and apply techniques to separate the AGN and SF components of each galaxy’s spectral energy distribution (SED). We use this approach to estimate the black hole accretion rate (BHAR) and star formation rate (SFR) for Milky Way (MW) and Andromeda (M31)-mass progenitors from z = 0:2 -- 2:5. Our motivation here is to minimise the effects of AGN contamination and selection-bias as we track the evolution of the SF-AGN connection of these sources from high to low redshift. Specifically, we track the evolution of their quenching rate via UVJ diagnostics, and their relative black hole-galaxy growth (i.e. their BHAR/SFR ratio). We find as the progenitors evolve, their BHAR/SFR ratio does not track the rate at which progenitors quench. Furthermore, the logarithm of the BHAR/SFR ratio of MW-mass progenitors evolves with a slope of 0:64 -- 0:11, whileM31-mass progenitors are 0:39 -- 0:08. These results contrast with previous studies that find an almost flat slope when adopting X-ray/AGN-selected or mass-limited samples and is likely due to their use of a broad mixture of galaxies with different evolutionary histories. Our use of progenitor-matched samples highlights the potential importance of carefully selecting progenitors when searching for evolutionary relationships between SMBHs and their host galaxies. Finally, we present a new technique to isolate the AGN contribution to the observed SED using only two photometric bands. Such an approach lends itself to studies where abundant photometric data may be lacking. While our approach is not without its limitations, we show it can reproduce underlying trends known to exist in AGN samples. Specifically, we reproduce the SF-AGN correlation found in infrared-selected AGN. However, similar to the previous chapter, we highlight where selection-bias may be driving these results. Overall, this thesis adds significant evidence to the suggestion that correlations observed between SMBHs and their host galaxies may be driven by selection effects, while also casting doubts over the idea that the suppression of star formation is predominantly driven by the negative feedback of luminous AGN over most of cosmic time.Mode of access: World wide web1 online resource (xxiii, 92 pages) diagrams, graphs, table
Probing the galactic ISM in OH absorption
No full textEmpirical thesis.Bibliography: pages 59-66.1. Introduction -- 2. Observations and data reduction -- 3. Gaussian decomposition -- 4. Results and discussion -- 5. Conclusions -- Appendices -- References.We examine the four 2π3/2, J = 3/2 ground state transitions of the hydroxyl radical (OH) along 15 sightlines through the Milky Way disk towards bright background continuum sources. We find that the OH gas along these sightlines is optically thin, consistent with the findings from the Southern Parkes Large Area Survey in Hydroxyl (SPLASH) pilot region]. We present a partially automated method for Gaussian decomposition of our spectra which identified 55 components across 28 OH-containing clouds. Three of these OH clouds had no associated 12CO emission (CO data from NANTEN).We test two methods of finding excitation temperature: a modified ‘on-off’ method, and a method where the excitation temperatures and column densities are solved for numerically .Neither method constrained Tex well. Column densities were calculated based on a range of possibleexcitation temperatures (Tex (1667) = 5-15 K), and conversions to N(H2) were made. N(OH) values were found to range from 1 - 40 x 1014cm-2, corresponding to N(H2) values ranging from1 - 40 x 1021 cm-2. We discuss our results in the context of CO-dark H2, and outline future directions for our work.Mode of access: World wide web1 online resource (66 pages) colour illustration
Effects of mining collapse on firm performance: evidence from Australia
No full textEmpirical thesis.Bibliography: pages 60-67.Chapter 1. Introduction -- Chapter 2. The Australian mining industry : a brief overview -- Chapter 3. Literature review and hypotheses development -- Chapter 4. Data, variable measures and methodology -- Chapter 5. Empirical results and discussion -- Chapter 6. Summary and conclusion.This study attempts to discover the extent to which Australian mining companies’ firm-level performance is affected by the mining collapse of 2011. To support the findings, this thesis also examines the effects on two related channels: cost of debt and investments. The difference-in-differences methodology is used on a relatively large unbalanced panel dataset comprising almost all mining and non-mining companies (except the financial sector) of the Australian Securities Exchange from 2006 to 2015. The results suggest that the mining companies have experienced a greater reduction in firm-level performance compared with the non-mining companies. The results also show that the mining companies have experienced a greater increase in the cost of debt and a greater reduction in their investments. These findings support previous literature and the expectation that the reduction in performance is associated with an increase in the cost of debt and a reduction in investments. The results are expected to contribute to our understanding of the nature of such sector-based crises on the companies within the sector compared with unaffected sectors. This thesis may have important policy implications for regulators who may bring necessary changes to their policies to assist more vulnerable companies.Mode of access: World wide web1 online resource (vii, 70 pages) graphs, table
Exploring scene setting as a strategy to support learning of students with a formal diagnosis of ADHD studying in higher education
No full textTheoretical thesis.Bibliography: pages 212-232.Chapter 1. Introduction -- Chapter 2. Literature review -- Chapter 3. Methodology -- Chapter 4. Data : the protraits -- Chapter 5. Discussion -- Chapter 6. Conclusion -- Appendices -- References.An increasing number of students diagnosed with attention deficit hyperactivity disorder (ADHD) are enrolling in higher education (HE) in Australia. Little is currently known about their needs and learning strategies or the support required for successful completion of their studies. What is known is that these students are at greater risk of psychological difficulties and academic failure. Bachelard’s (1964) Poetics of space, Dewey’s (1934) observations of experiential learning and Jackson’s (1998) theory of intersubjective relationships inform this inquiry. In-depth interviews and photo-voice were used to investigate what 13 students with a medical diagnosis of ADHD needed to support their HE learning. Interpretations of the data are found in the development of a new pedagogy for engineering students with ADHD (Hain, Turek, Zaghi, & Hain, 2017) and Ingold’s (2000, 2001, 2013) anthropological work culminating in his theory of attentionality (2016). Ingold (2016, p. 9) identifies the cognitive, sensory and motor experiences that occur during the developmental process of skill acquisition (enskilment) as the educational correspondences of attentionality, “attention as a resonant coupling of concurrent movements”. Meta-cognitive resources were interpreted through the concept of imaginative tools for placemaking developed by Fettes and Judson (2013).The participants in this study were found to use a range of strategies to set the scene for their learning by working to their strengths with the help of medication, psychosocial education, support and/or coaching. Scene setting helped participants to manage anxiety, eliminate distractions and focus their attention using learning strategies such as visual-spatial signposting to hyperfocus, which is expressed through the metaphor of gating. Gating extends to gate-keeping, time-keeping and book-keeping, forms of strategic partnering support that greatly benefit the participants. Such external support, combined with socio-economic status, stability, greater self-awareness and self-advocacy, strongly influenced how well the participants could function in the HE environment. The research also highlights the tensions between institutionalised learning environments and ADHD.Mode of access: World wide web1 online resource (xviii, 232 pages) colour illustration
Rumination and affective outcomes in women diagnosed with breast cancer
No full textEmpirical thesis.Bibliography: pages 277-349.Chapter 1. Introduction and structure of the thesis -- Chapter 2. Rumination : cognitive and emotional processing of illness threat -- Chapter 3. systematic review of the assessment of rumination -- Chapter 4. Item construction for the Multidimensional Rumination in Illness Scale -- Chapter 5. Asssessing rumination in response to illness : the development and validation of the Multidimensional Rumination in Illness Scale -- Chapter 6. Breast cancer -- Chapter 7. Rumination, psychological distress and post-traumatic growth in women diagnosed with breast cancer -- Chapter 8. The longitudinal study of rumination in breast cancer -- Chapter 9. General discussion -- Appendices -- References.Breast cancer entails a series of physical, psychosocial and existential challenges that extend into the survivorship period through late side effects from treatment and the potential for disease recurrence. Consequently, higher levels of depressive and anxious symptoms are experienced along the disease trajectory, although positive change, termed post-traumatic growth, can coexist. Perseverative thinking, specifically rumination, has been linked to the development and maintenance of depression and anxiety in clinically-well populations as well as to post-traumatic growth in the cancer context. With limited research into the pathways by which rumination might exert this dual influence, the overall aim was to increase understanding of how subcomponents of rumination are differentially related to positive and negative psychological outcomes in women diagnosed with breast cancer. Given the complexity of the rumination construct, the absence of a specific measure for the context of illness required the development of the Multidimensional Rumination in Illness Scale (MRIS) as an initial step to achieving this aim. Studies 1 and 2 addressed the development, pilot testing, refinement and validation of the MRIS, with solid psychometric properties being demonstrated. A cross-sectional study of individuals with breast cancer (Study 3) found that brooding rumination was associated with depressive and anxious symptoms whereas both instrumental and intrusive rumination were associated with post-traumatic growth. As timing of rumination can be significant, the longitudinal approach in Study 4 revealed more distinctly how patterns of rumination differentially affect psychological outcomes along the illness trajectory. These findings provide a basis for the enhancement of psychological interventions to minimise distress and optimise post-traumatic growth. While cognitive-behavioural therapy (CBT) approaches have been successful in managing distress, CBT does not specifically address rumination, placing importance on the evaluation of the effectiveness of newer CBT modalities, such as Mindfulness-Based Cognitive Therapy, that target rumination through the addition of disclosure techniques and mindfulness meditation.Mode of access: World wide web1 online resource (xv, 349 pages