Linear and nonlinear propagation of localised plasmon in metallic nanostructures

A major challenge in modern photonics and nano-optics is the diffraction limit of light which does not allow field localisation into regions with dimensions smaller than half the wavelength. Localisation of light into nanoscale regions (beyond its diffraction limit) has applications ranging from the design of optical sensors and measurement techniques with resolutions as high as a few nanometres, to the effective delivery of optical energy into targeted nanoscale regions such as quantum dots, nano-electronic and nano-optical devices. This field has become a major research direction over the last decade. The use of strongly localised surface plasmons in metallic nanostructures is one of the most promising approaches to overcome this problem. Therefore, the aim of this thesis is to investigate the linear and non-linear propagation of surface plasmons in metallic nanostructures. This thesis will focus on two main areas of plasmonic research –– plasmon nanofocusing and plasmon nanoguiding. Plasmon nanofocusing – The main aim of plasmon nanofocusing research is to focus plasmon energy into nanoscale regions using metallic nanostructures and at the same time achieve strong local field enhancement. Various structures for nanofocusing purposes have been proposed and analysed such as sharp metal wedges, tapered metal films on dielectric substrates, tapered metal rods, and dielectric V-grooves in metals. However, a number of important practical issues related to nanofocusing in these structures still remain unclear. Therefore, one of the main aims of this thesis is to address two of the most important of issues which are the coupling efficiency and heating effects of surface plasmons in metallic nanostructures. The method of analysis developed throughout this thesis is a general treatment that can be applied to a diversity of nanofocusing structures, with results shown here for the specific case of sharp metal wedges. Based on the geometrical optics approximation, it is demonstrated that the coupling efficiency from plasmons generated with a metal grating into the nanofocused symmetric or quasi-symmetric modes may vary between ~50% to ~100% depending on the structural parameters. Optimal conditions for nanofocusing with the view to minimise coupling and dissipative losses are also determined and discussed. It is shown that the temperature near the tip of a metal wedge heated by nanosecond plasmonic pulses can increase by several hundred degrees Celsius. This temperature increase is expected to lead to nonlinear effects, self-influence of the focused plasmon, and ultimately self-destruction of the metal tip. This thesis also investigates a different type of nanofocusing structure which consists of a tapered high-index dielectric layer resting on a metal surface. It is shown that the nanofocusing mechanism that occurs in this structure is somewhat different from other structures that have been considered thus far. For example, the surface plasmon experiences significant backreflection and mode transformation at a cut-off thickness. In addition, the reflected plasmon shows negative refraction properties that have not been observed in other nanofocusing structures considered to date. Plasmon nanoguiding – Guiding surface plasmons using metallic nanostructures is important for the development of highly integrated optical components and circuits which are expected to have a superior performance compared to their electronicbased counterparts. A number of different plasmonic waveguides have been considered over the last decade including the recently considered gap and trench plasmon waveguides. The gap and trench plasmon waveguides have proven to be difficult to fabricate. Therefore, this thesis will propose and analyse four different modified gap and trench plasmon waveguides that are expected to be easier to fabricate, and at the same time acquire improved propagation characteristics of the guided mode. In particular, it is demonstrated that the guided modes are significantly screened by the extended metal at the bottom of the structure. This is important for the design of highly integrated optics as it provides the opportunity to place two waveguides close together without significant cross-talk. This thesis also investigates the use of plasmonic nanowires to construct a Fabry-Pérot resonator/interferometer. It is shown that the resonance effect can be achieved with the appropriate resonator length and gap width. Typical quality factors of the Fabry- Pérot cavity are determined and explained in terms of radiative and dissipative losses. The possibility of using a nanowire resonator for the design of plasmonic filters with close to ~100% transmission is also demonstrated. It is expected that the results obtained in this thesis will play a vital role in the development of high resolution near field microscopy and spectroscopy, new measurement techniques and devices for single molecule detection, highly integrated optical devices, and nanobiotechnology devices for diagnostics of living cells.

Influence tactics and leader effectiveness : how effective, contemporary leaders influence subordinates

Defining the difference between successful and mediocre leaders is a quest that has attracted many renowned scholars, drawing vast amounts of research effort. Yet while there are excellent theoretical explanations of what leaders should do: exhibit transformational behaviours, demonstrate authenticity, build productive relationships with followers and so on; there is still a scarcity of empirically-based research advising practicing leaders how to do these things. This study seeks to provide guidance about the fine-grained processes that effective leaders use on a daily basis to undertake the core process of all leadership activity; influencing followers. Using a grounded research approach, this study employs qualitative methods to capture the detail of effective leader behaviour and the micro-level influence processes that leaders use to create effective follower outcomes. Conducted in the health services industry with medical and allied health leaders, the study sought to answer the question: What influence methods might effective, contemporary leaders be using? The study builds on existing influence research, seeking to extend and update the typology of 11 influence tactics originally developed by Yukl and others, and which has been static since the late 1990s. Eight new influence tactics were identified, offering practicing leaders a powerful suite of potential strategies and representing a significant contribution to the field. Further research is recommended to confirm the identified influence constructs and test the generalisability of these findings to broader leader populations in health organisations and other knowledge-based organisations.

Road trauma perceptions and the potential influence of the media

The United Nations Decade of Action for Road Safety (2011-2020) recognises the urgency of addressing global road trauma. Road crashes and attempts to reduce risky driving, including public education campaigns, receive media attention in many countries. In Australia, road fatalities have declined significantly. However, the extent of awareness about this success and of fatalities overall is unclear. A survey of 833 Australian drivers revealed the majority of participants under-estimated fatalities. Unexpectedly, some under-estimates appear based on recollections of media reports. The findings suggest lack of awareness of the extent of road deaths and that, paradoxically, media reports might contribute to underestimations. This represents a major public health challenge. Engaging community support for road safety, relative to other health/safety messages, may prove difficult if the extent of road trauma is misunderstood. Misperceptions about fatality levels may be a barrier to road users adopting safety precautions or supporting further road safety countermeasures.

Influence of organic matter in road deposited particulates in heavy metal accumulation and transport

The research study discussed in the paper investigated the influence of organic matter on heavy metal adsorption for different particle size ranges of build-up solids. Samples collected from road surfaces were assessed for organic matter content, mineral composition, particle size distribution and effective cation exchange capacity. It was found that the organic matter plays a key role in >75µm particles in the adsorption of Zinc, Lead, Nickel and Copper, which are generated by traffic activities. Clay forming minerals and metal oxides of Iron, Aluminium and Manganese was found to be important for heavy metal adsorption to <75µm particles. It was also found that heavy metals adsorbed to organic matter are strongly bound to particles and these metal ions will not be bio-available if the chemical quality of the media remains stable.

Antibiotics overuse in children with upper respiratory tract infections in Saudi Arabia : risk factors and potential interventions

Background: Antibiotics misuse is currently one of the major public health issues worldwide. This misuse can lead to the development of bacterial resistance, increasing the burden of chronic diseases, rising costs of health services, and the development of side effects. Several factors may influence this pattern of overuse. Objectives:This article will review the pertinent factors contributing to the overuse of antibiotics worldwide, and to assess the intervention strategies to limit this overuse. Methods: studies about antibiotics use in children were reviewed from several electronic databases, such as MEDLINE and Pubmed. Results: Factors contributing to the overuse of antibiotics could include psychosocial factors, such as behaviors and attitudes (e.g. self-medication, over-the-counter medication, or patients/parents pressure), and demographic factors, such as socio-economic status and education level. Several intervention strategies were reported to be effective in reducing the overuse of antibiotics, such as health education, doctor-patient communication, and policies change. Multifaceted interventions were found to be the most effective in reducing the antibiotics overuse.

The influence of justice theories on international climate policies and measures

While the justice implications of climate change are well understood by the international climate regime, solutions to meaningfully address climate injustice are still emerging. This article explores how a number of different theories of justice have influenced the development of international climate regime policies and measures. Such analysis is undertaken by examining the theories of remedial justice, environmental justice, energy justice, social justice and international justice. This article demonstrates how each of these theories has influenced the development of international climate policies or measures. No one theory of justice has the ability to respond to the multifaceted justice implications that arise as a result of climate change. It is argued that a variety of lenses of justice are useful when examining issues of injustice in the climate context. It is believed that articulating the justice implications of climate change by reference to theories of justice assists in clarifying the key issues giving rise to injustice. This article finds that while there has been some progress by the regime in recognising the injustices associated with climate change, such recognition is piecemeal and the implementation of many of the policies and measures discussed within this article needs to be either scaled up, or extended into more far-reaching policies and measures to overcome climate justice concerns. Overall it is suggested that climate justice concerns need to be clearly enunciated within key adaptation instruments so as to provide a legal and legitimate basis upon which to leverage action.

The influence of oxygenated organic aerosols (OOA) and its volatile organic content on the oxidative potential of diesel particulate mater

Airborne particulate matter pollution is of concern for a number of reasons and has been widely recognised as an important risk factor to human health. A number of toxicological and epidemiological studies reported negative health effects on both respiratory and cardiovascular system. Despite the availability of a huge body of research, the underlying toxicological mechanisms by which particles induce adverse health effects are not yet entirely understood. The production of reactive oxygen species (ROS) has been shown to induce oxidative stress, which is proposed as a mechanism for many of the adverse health outcomes associated with exposure to particulate matter (PM). Therefore, it is crucial to introduce a technique that will allow rapid and routine screenings of the oxidative potential of PM.

Influence of pre-exsiting surface defects on the vibrational properties of Ag nanowires

Large-scale molecular dynamics simulations are performed to characterize the effects of pre-existing surface defects on the vibrational properties of Ag nanowires. It is found that the first order natural frequency of the nanowire appears insensitive to different surface defects, indicating a defect insensitivity property of the nanowire’s Young’s modulus. In the meanwhile, an increase of the quality (Q)-factor is observed due to the presence of defects. Particular, a beat phenomenon is observed for the nanowire with the presence of a surface edge defect, which is driven by a single actuation. It is concluded that different surface defects could act as an effective mean to tune the vibrational properties of nanowires. This study sheds lights on the better understanding of nanowire’s mechanical performance when surface defects are presented, which would benefit the development of nanowire-based devices.

The potential influence of Neoliberalism on the capacity and form of spatial adaptation

Human spatial environments must adapt to climate change. Spatial planning is central to climate change adaptation and potentially well suited to the task, however neoliberal influences and trends threaten this capacity. This paper explores the potential interaction of emerging research areas, the first of which pursues climate change adaptation through spatial planning and the second of which has observed the neoliberalisation of urban planning, The potential capacity and form of spatial adaptation within the context a planning environment influenced by neoliberal principles is evaluated. This influence relates to the themes of spatial scale, temporal scale, responsibility for action, strategies and mechanisms, accrual of benefits, negotiation of priorities and approach to uncertainty. This paper presents a conceptual framework of the influence of neoliberalism on spatial adaptation and presents examples of this approach in documents which underpin adaptation in Australia. It identifies the potential characteristics and the challenges and opportunities of spatial adaptation under a neoliberal frame. The neoliberal frame does not entirely preclude spatial adaptation but significantly influence its form. Neoliberal approaches involve individual action in response to private incentives and near term impacts while collective action, regulatory mechanisms and long term planning is approached cautiously. Challenges concern the degree to which collective action and a long term orientation are necessary, how individual adaptation relates to collective vulnerability and the prioritisation of adaptation by markets. Opportunities might involve the operability of individual and local adaptation, the existence of private incentives to adapt and the potential to align adaptation with entrepreneurial projects.

The Authority of Influence : Women and Power in Burmese History

This book explores the relationship between gender and power in Burmese history from pre-colonial times to the present day and aims to identify the sources, nature and limitations of women’s power. The study takes as its starting point the apparent contradiction that, though Burmese women historically enjoyed relatively high social status and economic influence, for the most part they remained conspicuously absent from positions of authority in formal religious, social and political institutions. The book thus examines the concept of ‘family’ in Burmese political culture, and reveals how some women were able to gain political influence through their familial connections with powerful men, even while cultural models of ‘correct’ female behaviour prevented most women from attaining official positions of political authority. The study also considers how various influences – Buddhism, colonialism, nationalism, modernisation and militarism – shaped Burmese concepts of gender and power, with important implications for how women were able to exercise social, economic and political influence. The book explores how the effects of prolonged armed conflict, economic isolation and political oppression have constrained opportunities for women to attain power in contemporary Burma, and examines opportunities opened up by the pro-democracy movement and recent focus on women's issues and rights for women to exercise influence both inside Burma and in exile. Using an interdisciplinary approach that draws on feminist, anthropological and social science discourses, placing them within an historical framework, the author offers a broad understanding of how power is obtained and exercised in Burma in order to reassess historical representations of Burmese women and so provide a more comprehensive and inclusive understanding of power relations in historical and contemporary Burma.

Influence of filtration on I/O particle concentration ratios at urban office buildings

Epidemiological research has consistently shown an association between fine and ultrafine particle concentrations, and increases in both respiratory and cardiovascular morbidity and mortality. These particles, often found in vehicle emissions outside buildings, can penetrate inside via their envelopes and mechanically ventilated systems. Indoor activities such as printing, cooking and cleaning, as well as the movement of building occupants are also an additional source of these particles. In this context, the filtration systems of mechanically ventilated buildings can reduce indoor particle concentrations. Several studies have quantified the efficiency of dry-media and electrostatic filters, but they mainly focused on the particle size range > 300 nm. Some others studied ultrafine particles but their investigations were conducted in laboratories. At this point, there is still only limited information on in situ filter efficiency and an incomplete understanding of filtration influence on I/O ratios of particle concentrations. To help address these gaps in knowledge and provide new information for the selection of appropriate filter types in office building HVAC systems, we aimed to: (1) measure particle concentrations at up and down stream flows of filter devices, as well as outdoor and indoor office buildings; (2) quantify efficiency of different filter types at different buildings; and (3) assess the impact of these filters on I/O ratios at different indoor and outdoor source operation scenarios.

Beyond barcoding : a mitochondrial genomics approach to molecular phylogenetics and diagnostics of blowflies (Diptera: Calliphoridae)

Members of the Calliphoridae (blowflies) are significant for medical and veterinary management, due to the ability of some species to consume living flesh as larvae, and for forensic investigations due to the ability of others to develop in corpses. Due to the difficulty of accurately identifying larval blowflies to species there is a need for DNA-based diagnostics for this family, however the widely used DNA-barcoding marker, cox1, has been shown to fail for several groups within this family. Additionally, many phylogenetic relationships within the Calliphoridae are still unresolved, particularly deeper level relationships. Sequencing whole mt genomes has been demonstrated both as an effective method for identifying the most informative diagnostic markers and for resolving phylogenetic relationships. Twenty-seven complete, or nearly so, mt genomes were sequenced representing 13 species, seven genera and four calliphorid subfamilies and a member of the related family Tachinidae. PCR and sequencing primers developed for sequencing one calliphorid species could be reused to sequence related species within the same superfamily with success rates ranging from 61% to 100%, demonstrating the speed and efficiency with which an mt genome dataset can be assembled. Comparison of molecular divergences for each of the 13 protein-coding genes and 2 ribosomal RNA genes, at a range of taxonomic scales identified novel targets for developing as diagnostic markers which were 117–200% more variable than the markers which have been used previously in calliphorids. Phylogenetic analysis of whole mt genome sequences resulted in much stronger support for family and subfamily-level relationships. The Calliphoridae are polyphyletic, with the Polleninae more closely related to the Tachinidae, and the Sarcophagidae are the sister group of the remaining calliphorids. Within the Calliphoridae, there was strong support for the monophyly of the Chrysomyinae and Luciliinae and for the sister-grouping of Luciliinae with Calliphorinae. Relationships within Chrysomya were not well resolved. Whole mt genome data, supported the previously demonstrated paraphyly of Lucilia cuprina with respect to L. sericata and allowed us to conclude that it is due to hybrid introgression prior to the last common ancestor of modern sericata populations, rather than due to recent hybridisation, nuclear pseudogenes or incomplete lineage sorting.