Parametric excitation of high-frequency surface waves in a plasma-metal waveguide structure

The problem concerning the excitation of high-frequency surface waves (SW) propagating across an external magnetic field at a plasma-metal interface is considered. A homogeneous electric pump field is applied in the direction transverse with respect to the plasma-metal interface. Two high-frequency SW from different frequency ranges of existence and propagating in different directions are shown to be excited in this pump field. The instability threshold pump-field values and increments are obtained for different parameters of the considered waveguide structure. The results associated with saturation of the nonlinear instability due to self-interaction effects of the excited SW are given as well. The results are appropriate for both gaseous and semiconductor plasmas.

Two-channel waveguide modulator based on surface wave propagating in a semiconductor-metal thin-film structure

The results of theoretical investigations of two-channel waveguide modulator based on Surface Wave (SW) propagation are presented. The structure studied consists of two n-type semiconductor waveguide channels separated from each other by a dielectric gap and coated by a metal. The SW propagates at the semiconductor-metal interface across an external magnetic field which is parallel to the interface. An external dc voltage is applied to the metal surface of one channel to provide a small phase shift between two propagating modes. In a coupled mode approximation, two possible regimes of operation of the structure, namely as a directional coupler and as an electro-optical modulator, are considered. Our results suggest new applications in millimeter and submillimeter wave solid-state electronics and integrated optics.

How should future building structure and emergency response cope with bushfire attack?

Bushfires are regular occurrences in the Australian landscape which can, under adverse weather conditions, give rise to losses of life, property, infrastructure, environmental and cultural values. Where property loss is involved, historical surveys of house losses have focussed on ember, radiant heat and flame contact as key bushfire attack mechanisms. Although often noted, little work has been done to quantify the impact of fire generated or fire enhanced wind and pyro-convective events on house loss and to improve construction practice within Australia. It is well known that strong winds are always associated with bushfire events. It is less well known, although increasingly shown through anecdotal evidence, that bushfires are not a passive companion of wind, but indeed they interact with winds and can together cause significant damages to exposed buildings and ecological structures. Previous studies have revealed the effects of wind, fire and structure interactions with the result of increased pressure coefficient distributions on the windward side of a building downstream of a fire front. This paper presents a further analysis of the result in relations to the relevant standards and fire weather conditions. A review of wind code and bushfire code was conducted. Based on the result of the current study, the authors believe it is necessary to consider wind as an attack mechanism in bushfire events. The results of the study will also have implications on bushfire emergency management, design of emergency shelters, perception of danger, emergency evacuation and on risk assessment.

On-the-fly web content integrity check boosts users' confidence

Web servers are accessible by anyone who can access the Internet. Although this universal accessibility is attractive for all kinds of Web-based applications, Web servers are exposed to attackers who may want to alter their contents. Alterations range from humorous additions or changes, which are typically easy to spot, to more sinister tampering, such as providing false or damaging information.

Web crippling behaviour of C-section beams with web ribs

SupaCee section is one of the cold-formed steel members which is increasingly used in the construction sector. It is characterized by unique ribbed web and curved lip elements, and is claimed to be more economical with extra strength than the traditional channel sections. SupaCee sections are widely used in Australia as floor joists, bearers, purlins and girts. Many experimental and numerical studies have been carried out to evaluate the behaviour and design of conventional channel beams subject to web crippling. To date, however, no investigation has been conducted into the web crippling behaviour and strength of SupaCee sections. Current cold-formed steel design equations do not include any design procedures for SupaCee sections. Hence experimental studies were conducted to assess the web crippling behaviour and strengths of SupaCee sections under ETF and ITF load cases. Thirty six web crippling tests were conducted and the capacity results were compared with the predictions from the AS/NZS 4600 and AISI design rules developed for conventional channel sections. Comparison of ultimate web crippling capacities from tests showed that AS/NZS 4600 and AISI design equations are unconservative for SupaCee sections under ETF load case, but are overly conservative for ITF load case. Hence new equations were proposed to determine the web crippling capacities of SupaCee sections based on the experimental results from this study. Suitable design rules were also developed within the direct strength method format. This paper presents the details of this experimental study of SupaCee sections subject to web crippling and the results.

Structure-mediated thermal transport of monolayer graphene allotropes nanoribbons

We report the study of the thermal transport management of monolayer graphene allotrope nanoribbons (size ∼20 × 4 nm2) by the modulation of their structures via molecular dynamics simulations. The thermal conductivity of graphyne (GY)-like geometries is observed to decrease monotonously with increasing number of acetylenic linkages between adjacent hexagons. Strikingly, by incorporating those GY or GY-like structures, the thermal performance of graphene can be effectively engineered. The resulting hetero-junctions possess a sharp local temperature jump at the interface, and show a much lower effective thermal conductivity due to the enhanced phonon–phonon scattering. More importantly, by controlling the percentage, type and distribution pattern of the GY or GY-like structures, the hetero-junctions are found to exhibit tunable thermal transport properties (including the effective thermal conductivity, interfacial thermal resistance and rectification). This study provides a heuristic guideline to manipulate the thermal properties of 2D carbon networks, ideal for application in thermoelectric devices with strongly suppressed thermal conductivity.

Development and evaluation of the Ontrack Diabetes Program : an automated, web-based type 2 diabetes self-management and dysphoria intervention

This research was conducted in the area of Clinical and Health Psychology. The study involved the development and evaluation of a novel, web-based program aimed to improve Type 2 diabetes self-management and mood. The program was developed as an original technological intervention aimed to improve access to support for rural and remote communities, and is currently being trialled across Australia with a larger sample size. The researcher aims to continue research into the field of clinical psychology, and in particular is interested in working on further interventions to support those with comorbid physical and mental health conditions.

Organizational support and enterprise web 2.0 adoption : a qualitative study

The emerging growth of Web 2.0 has been observed by users in the workplace, and has therefore encouraged organisations to introduce Web 2.0 technologies in their businesses. Although its adoption is beneficial, it could meets with employees resistance due to some organisational factors. The successful implementation of Enterprise Web 2.0 is based on employee adoption of such social technology. Using a qualitative study, this research explores how organizational support can influence employees’ adoption of Enterprise Web 2.0. The findings show that organisational support encourages and facilitates a smooth adoption. Such support can be provided by management and colleagues in several forms: developing a Web 2.0 strategy, providing required resources for such training, recognising and encouraging adopters, and involving managers in the adoption.

Spectroscopic vibrations of austinite (CaZnAsO4⋅OH) and its mineral structure : Implications for identification of secondary arsenic-containing mineral

Austinite (CaZnAsO4⋅OH) is a unique secondary mineral in arsenic-contaminated mine wastes. The infrared and Raman spectroscopies were used to characterize the austenite vibrations. The IR bands at 369, 790 and 416 cm−1 are assigned to the ν2, ν3 and ν4 vibrations of AsO43− unit, respectively. The Raman bands at 814, 779 and 403 cm−1 correspond to the ν1, ν3 and ν4 vibrations of AsO43− unit respectively. The sharp bands at 3265 cm−1 for IR and 3270 cm−1 both reveals that the structural hydroxyl units exist in the austenite structure. The IR and Raman spectra both show that some SO4 units isomorphically replace AsO4 in austinite. X-ray single crystal diffraction provides the arrangement of each atom in the mineral structure, and also confirms that the conclusions made from the vibrational spectra. Micro-powder diffraction was used to confirm our mineral identification due to the small quantity of the austenite crystals.

Structure and assembly of immature HIV

The major structural components of HIV are synthesized as a 55-kDa polyprotein, Gag. Particle formation is driven by the self-assembly of Gag into a curved hexameric lattice, the structure of which is poorly understood. We used cryoelectron tomography and contrast-transfer-function corrected subtomogram averaging to study the structure of the assembled immature Gag lattice to approximate to 17-angstrom resolution. Gag is arranged in the immature virus as a single, continuous, but incomplete hexameric lattice whose curvature is mediated without a requirement for pentameric defects. The resolution of the structure allows positioning of individual protein domains. High-resolution crystal structures were fitted into the reconstruction to locate protein-protein interfaces involved in Gag assembly, and to identify the structural transformations associated with virus maturation. The results of this study suggest a concept for the formation of nonsymmetrical enveloped viruses of variable sizes.

Nanoscale phase domain structure and associated device performance of organic solar cells based on a diketopyrrolopyrrole polymer

We investigate the blend morphology and performance of bulk heterojunction organic photovoltaic devices comprising the donor polymer, pDPP-TNT (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1, 4-dione-alt-naphthalene}) and the fullerene acceptor, [70]PCBM ([6,6]-phenyl C71-butyric acid methyl ester). The blend morphology is heavily dependent upon the solvent system used in the fabrication of thin films. Thin films spin-coated from chloroform possess a cobblestone-like morphology, consisting of thick, round-shaped [70]PCBM-rich mounds separated by thin polymer-rich valleys. The size of the [70]PCBM domains is found to depend on the overall film thickness. Thin films spin-coated from a chloroform:dichlorobenzene mixed solvent system are smooth and consist of a network of pDPP-TNT nanofibers embedded in a [70]PCBM-rich matrix. Rinsing the films in hexane selectively removes [70]PCBM and allows for analysis of domain size and purity. It also provides a means for investigating exciton dissociation efficiency through relative photoluminescence yield measurements. Devices fabricated from chloroform solutions show much poorer performance than the devices fabricated from the mixed solvent system; this disparity in performance is seen to be more pronounced with increasing film thickness. The primary cause for the improved performance of devices fabricated from mixed solvents is attributed to the greater donor-acceptor interfacial area and resulting greater capacity for charge carrier generation.

Isolation, structure determination and cytotoxicity studies of tryptophan alkaloids from an Australian marine sponge Hyrtios sp

Mass-guided fractionation of the MeOH extract from a specimen of the Australian marine sponge Hyrtios sp. resulted in the isolation of two new tryptophan alkaloids, 6-oxofascaplysin (2), and secofascaplysic acid (3), in addition to the known metabolites fascaplysin (1) and reticulatate (4). The structures of all molecules were determined following NMR and MS data analysis. Structural ambiguities in 2 were addressed through comparison of experimental and DFT-generated theoretical NMR spectral values. Compounds 1–4 were evaluated for their cytotoxicity against a prostate cancer cell line (LNCaP) and were shown to display IC50 values ranging from 0.54 to 44.9 μM.

Web mediated market interactions and enterprise software

With increased consolidation and a few large vendors dominating the market, how can software vendors distinguish themselves in order to maintain profitability and gain market share? Increasingly customers are becoming more proactive in selecting a vendor and a product, drawing upon various publications, market surveys, mailing lists, and, of course, other users. In particular, though, a company's Web site is the obvious place to begin information gathering. In sum, it may seem that the days of the uninformed customer prepared to be "sold to" are potentially all but gone.

The sideways hourglass : establishing the lemniscate as a narrative structure for writing and reading non-linear stories

This thesis is a study in narratology that examines the pre-theoretical ideas that underlie the study of narrative and time. The thesis explores how the lemniscate can be transported from geometry to narrative in order to structure a non-linear story that breaks the rules of causality and chronology by coupling physical movement through space with the backward pull of memory. The findings offer new possibilities for understanding the nexus between shape and story and for recording non-linear narratives that are marked by simultaneity, counterpoint, and reversal.