988 research outputs found

    Co-rich cobalt platinum nanowire arrays: effects of annealing

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    The effects of annealing on the crystal structure and magnetic properties of Co-rich cobalt platinum nanowire arrays embedded in anodic aluminium oxide membranes have been investigated. For this purpose, a rapid thermal annealing to temperatures of 300 °C to 800 °C has been used. Transmission electron microscopy and scanning electron microscopy show that the nanowires have a mean diameter of 14 nm and an estimated wire density of 7.8Ă—1010 cm-2. From x-ray diffraction patterns, we find that the nanowires are hcp and possess a preferred texture in which the c axis of the grains tends to lie along the major axis of the wire. Vibrating sample magnetometry measurements indicate that the easy axis is along the nanowire axis direction. Hysteresis loops, saturation magnetization, squareness ratio (Mr/Ms), and coercivity (perpendicular and parallel to the nanowire axis) have all been investigated as a function of the annealing temperature (TA). Coercivity parallel to the wire axis first increases with TA, attains a maximum at 600 °C (which is 150% of the as-deposited sample), and then decreases. By contrast there is relatively little change in the coercivity measured perpendicular to the wires. The saturation magnetization for the as-deposited sample is 1360 emu/cc and remains almost constant for annealing temperatures up to 500 °C: for TA>500 °C it decreases significantly. The maximum (Mr/Ms) ratio attained in this study is 0.99, the highest value reported thus far for cobalt platinum alloy nanowires. The data suggest that these materials are potential candidates for high-density magnetic recording media

    Understanding aspects of alginate biosynthesis and regulation by Pseudomonas aeruginosa : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Microbiology at Massey University, Palmerston North, New Zealand

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    Alginate is a medically and industrially important polymer produced by seaweeds and certain bacteria. The bacterium Pseudomonas aeruginosa over-produces alginate during cystic fibrosis lung infections, forming biofilms, making the infection difficult to treat. Bacteria make alginate using membrane spanning multi-protein complexes. Although alginate biosynthesis and regulation have been studied in detail, there are still major gaps in knowledge. In particular, the requirement of AlgL (a periplasmic alginate degrading enzyme) and role played by MucR (an inner membrane c-di-GMP modulator) are not well understood. Here I show that AlgL and MucR are not essential for alginate production during biofilm growth. My findings suggest that while catalytically active AlgL negatively affects alginate production, expressing catalytically inactive AlgL enhances alginate yields. Furthermore, preliminary data show AlgL is not required for the stability or functionality of the alginate biosynthesis complex, suggesting that it is a free periplasmic protein dispensable for alginate production. These findings support the prediction that the primary function of AlgL is to degrade misguided alginate from the periplasm. For MucR, I show for the first time that its sensor domain mediates nitrate-induced suppression of alginate biosynthesis. This appears to occur at multiple levels in a manner only partially dependent on c-di-GMP signaling. These results indicate that MucR is associated with the negative effect of nitrate (and possibly denitrification) on alginate production. On the basis of these results, I propose a combination of nitrate (or denitrification intermediates), exogenous lyases and antimicrobial agents could be used to eliminate established chronic biofilm infections. Furthermore, catalytically inactive AlgL and/or homologs of MucR with disabled sensor motifs could be harnessed in non-pathogenic bacteria for producing tailor-made alginates

    The epidemiology of the first wave of H1N1 influenza pandemic in Australia : a population-based study

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    Objectives: Following the recent H1N1 influenza pandemic we were able to describe seropositivity in a repre-sentative sample of adults prior to the availability of a specific vaccine.Methods: This cross-sectional serological study is set in the Barwon Statistical Division, Australia. Blood samples were collected from September 2009 through to May 2010, from 1184 individuals (569 men, 615 women; median age 61.7 years), randomly selected from electoral rolls. Serum was analysed for specific H1N1 immunity using a haemagglutina-tion inhibition test. A self-report provided information about symptoms, demographics and healthcare. Associations be-tween H1N1 infection, gender, households and occupation were determined using logistic regression, adjusting for age.Results: Of 1184 individuals, 129 (58 men, 71 women) were seropositive. Gender-adjusted age-specific prevalence was: 8.3% 20-29 years, 13.5% 30-39, 10.4% 40-49, 6.5% 50-59, 9.7% 60-69, 10.3% 70-79, 18.8% 80+. Standardised preva-lence was 10.3% (95%CI 9.6-11.0). No associations were detected between seropositivity and gender (OR=0.82, 95%CI 0.57-1.19) or being a healthcare worker (OR=1.43, 95%CI 0.62-3.29). Smokers (OR=1.86, 95%CI 1.09-3.15) and those socioeconomically disadvantaged (OR=2.52, 95%CI 1.24-5.13) were at increased risk. Among 129 seropositive individu-als, 31 reported symptoms that were either mild (n = 13) or moderate (time off work, doctor visit, n = 18). For age &lt;60, 39.6% of seropositive individuals reported symptoms, whereas the proportion was 13.2% for age 60+.Conclusions: Following the pandemic, the proportion of seropositive adults was low, but significant subclinical infection was found. Social disadvantage increased the likelihood of infection. The low symptom rate for older ages may relate to pre-existing immunity.<br /

    Scaling New Heights: How to Spot Small Successes in the Public Sector and Make Them Big

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    Examines barriers to bringing innovations to scale in the social sector and recommends developing a market for social outcomes, designing funding models that encourage scaling, shaping the field of knowledge about what works, and investing in mentors

    Capital Ideas: How to Generate Innovation in the Public Sector

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    Offers suggestions for and examples of how to stimulate innovation in government, including identifying priorities, allowing for creative and entrepreneurial solutions, funding innovation, improving incentives, changing cultures, and scaling what works

    Oocyte cryopreservation as an adjunct to the assisted reproductive technologies

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    The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included. See page 2 of PDF for this item.Keith L Harrison, Michelle T Lane, Jeremy C Osborn, Christine A Kirby, Regan Jeffrey, John H Esler and David Mollo

    Energy and Accuracy Trade-Offs in Accelerometry-Based Activity Recognition

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    Driven by real-world applications such as fitness, wellbeing and healthcare, accelerometry-based activity recognition has been widely studied to provide context-awareness to future pervasive technologies. Accurate recognition and energy efficiency are key issues in enabling long-term and unobtrusive monitoring. While the majority of accelerometry-based activity recognition systems stream data to a central point for processing, some solutions process data locally on the sensor node to save energy. In this paper, we investigate the trade-offs between classification accuracy and energy efficiency by comparing on- and off-node schemes. An empirical energy model is presented and used to evaluate the energy efficiency of both systems, and a practical case study (monitoring the physical activities of office workers) is developed to evaluate the effect on classification accuracy. The results show a 40% energy saving can be obtained with a 13% reduction in classification accuracy, but this performance depends heavily on the wearer’s activity
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