2,139 research outputs found

    Tuna Baitfish and the Pole-and-line Industry in Kiribati

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    Livestock Production/Industries, Resource /Energy Economics and Policy,

    Optical properties of metallic systems

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    University of Technology, Sydney. Department of Physics and Advanced Materials, Faculty of Science.The continuous improvement of nanoscale fabrication techniques will ultimately result in a situation where the performance of plasmonic devices is not dependent on engineering defects, but rather on the fundamentally limiting behaviour of the underlying metals. This thesis addresses the following questions: Are silver and gold the best metals for plasmonics? What other materials are available? and finally; Can we design better plasmonic materials? To answer these questions, classical electrodynamics calculations are performed using tabulated dielectric functions from the literature. Starting from a comparison of nanoshells made of various free electron metals, it is shown that the low plasma frequency metals sodium and potassium perform well. However, these metals are not suitable for many common uses of nanoshells. As such, the material choice is extended to all non fgroup metals in the periodic table and a variety of additional geometries are studied, including nanorods, superlenses and a number of guiding structures. It is shown that gold, silver, the alkali metals and aluminium outperform all other metals, each over a range of frequencies and permittivities. None of the reviewed elements performs better than silver and gold. As none of the elements seem to offer any advantage over silver or gold, the search is extended to alternative materials with tabluated dielectric functions. A review of the plasmonic properties of these materials is presented, including alloys, intermetallic compounds , high pressure materials as well as silicides, metallic glasses, and liquid metals. It is discovered that liquid sodium outperforms its solid elemental counterpart. Additionally, several materials with simple crystal structures seem to perform well, but none to the extent of silver or gold. The number of compounds for which tabulated optical constants are available is severely limited. In order to evaluate the performance of a large number of materials, first principles quantum mechanical calculations must be performed. It is shown that the plasmonic performance can be approximately gleened from the relationship between the optical gap and the plasma frequency. However, in order to compare the calculated optical response of materials with experimental data for the elements, the Drude phenomenological scattering rate must be known. Here, for the first time, calculations of the real and imaginary components of the dielectric function including the electron-phonon scattering rate are performed in order to gauge the plasmonic performance of materials with no tabulated optical data. A list of publications associated with this work is presented on page iv

    The Populist Imaginary in David Ireland's The Unknown Industrial Prisoner and The Chosen

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    Benedict Anderson has argued that the modern nation-state, theorised as an "imagined community," is founded on the rise of a secular media, a media that not only provides a universal form of communication but also provides the stories that provide the basis of everyday ritual and shared community

    AN INTRODUCTION AND BACKGROUND TO THE BAITFISH RESEARCH PROJECT IN EASTERN INDONESIA

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    Pole-and-line fishing for tuna is a multi-million dollar industry in eastern Indonesia that employs many people, supports several canneries and generates export income

    Just Biofuels? Mapping dimensions of energy justice in relation to an international liquid biofuel supply chain

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    Abstract It is argued in this thesis that it is morally right to identify and address matters of energy justice associated with renewable energy technologies - and thus biofuels. Equity appraisals, as defined in this thesis, can help to identify social and environmental burdens caused by the implementation of these technologies and where they exist, thus helping to understand the extent to which global sustainable development ideals to reduce inequalities are being achieved. This study is the first equity appraisal of an internationally-traded (Brazil-UK) liquid biofuel (sugarcane bioethanol), across both sites of production and consumption, conducted in a manner advocated by energy justice and environmental justice theories. Furthermore, this study provides the first empirical insights in this context of the ways that principal dimensions of energy justice can interrelate and specifically how matters of procedural justice and recognition can drive distributional changes in outcomes amongst people connected and affected to a transnational liquid biofuel supply chain. Primary qualitative data collected from people living in producer and consumption localities revealed that the nature and geographical patterning of issues differed from the views of transnational governance actors and experts. Rather than the majority of burdens lying with those living in Brazil, and UK-based consumers largely indifferent and unaffected, this research found both positive and negative equity issues affecting people at both ends of the supply chain. Matters of recognition and procedural injustice were found to be affecting consumers, affecting their abilities to engage effectively with their liquid biofuels purchases that could help drive the consumption of more sustainable, just and socially acceptable biofuels. Conversely, higher levels of recognition of local communities and associated impacts in this particular Brazilian production locality were found to be improving social and environmental outcomes for residents. This research highlights the importance of situated, contextual, primary qualitative data for equity appraisals of liquid biofuels and other renewable technologies. It is argued that these types of appraisals should be conducted more systematically in the field to supplement existing forms of appraisals, support decision-making processes and improve the chances of achieving energy justice in relation to renewable energy technologies

    Optical performance and metallic absorption in nanoplasmonic systems

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    Optical metrics relating to metallic absorption in representative plasmonic systems are surveyed, with a view to developing heuristics for optimizing performance over a range of applications. We use the real part of the permittivity as the independent variable; consider strengths of particle resonances, resolving power of planar lenses, and guiding lengths of planar waveguides; and compare nearly-free-electron metals including Al, Cu, Ag, Au, Li, Na, and K. Whilst the imaginary part of metal permittivity has a strong damping effect, field distribution is equally important and thus factors including geometry, real permittivity and frequency must be considered when selecting a metal. Al performs well at low permittivities (e.g. sphere resonances, superlenses) whereas Au & Ag only perform well at very negative permittivities (shell and rod resonances, LRSPP). The alkali metals perform well overall but present engineering challenges. © 2009 Optical Society of America

    Species identification, distribution and abundance of Gerreidae (Teleostei) Bleeker,1859 in the estuaries of Natal

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    Comparison of published meristic and taxonomic data with measurements taken from specimens collected from Natal estuaries have provided information for an identification key to the Gerres of southern Africa. Body markings were different on each species of fry (< 40 mm S.L.) as well as immatures and adults (> 40 mm S.L.). A comparison of otoliths from the different species showed that they can be used to Identify specimens from a standard length of 20 mm. Turbidity may be a factor limiting the distribution of the genus in estuaries. The known distribution of Gerres species in the estuaries of southern Africa is given. The species of Gerres which is dominant in a particular locality depends on the salinity
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