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Mentoring and teacher induction
No full textThis paper will present details of a project on becoming a teacher and preview the direction of future research issues. The 1990 emphasis of this research-in-progress was to conduct a literature review and build up a theoretical overview on teacher education and the relationship between teacher training and induction
Agreement between self-reported perinatal outcomes and administrative data in New South Wales, Australia
No full textBackground: Many epidemiological studies that focus on pregnancy rely on maternal self-report of perinatal outcomes. The aim of this study was to evaluate the agreement between self-reported perinatal outcomes (gestational hypertension with or without proteinuria, gestational diabetes, premature birth and low birth weight) in a longitudinal study and linked to administrative data (medical records). Methods: Self-reported survey data from the Australian Longitudinal Study on Women's Health was linked with the New South Wales Perinatal Data Collection. Agreement between the two sources was evaluated using percentage agreement and kappa statistics. Analyses were conducted at two levels by: i) the mother and ii) each individual child. Results: Women reliably self-report their perinatal outcomes (≥87 % agreement). Gestational hypertension with or without proteinuria had the lowest level of agreement. Mothers' reports of perinatal outcomes were more reliable when evaluated by child. Restricting the analysis to complete and consistent reporting further strengthened the reliability of the child-specific data, increasing the agreement from >92 to >95 % for all outcomes. Conclusions: The present study offers a high degree of confidence in the use of maternal self-reports of the perinatal outcomes gestational hypertension, gestational diabetes, preterm birth and low birth weight in epidemiological research, particularly when reported on a per child basis. Furthermore self-report offers a cost-effective and convenient method for gathering detailed maternal perinatal histories
The expression of Dicer and Drosha in matched normal tissues, tumours and lymph node metastases in triple negative breast cancer
No full textBackground: Breast cancer is the most common malignancy in women world-wide. Triple negative breast cancer (TNBC) is a highly aggressive subtype that lacks expression of hormone receptors for estrogen, progesterone and human epidermal growth factor 2; and is associated with a high propensity for metastatic spread. Several studies have identified critical roles for microRNAs in breast cancer, but the role of two critical enzymes involved in microRNA biogenesis, Dicer and Drosha, is not well understood, particularly with respect to metastatic progression in this subtype. Methods: We examined the expression of Dicer and Drosha in a series of invasive 35 TNBCs with matched normal adjacent tissues (n = 18) and lymph node metastases (n = 15) using semi-quantitative real time RT-PCR. The relationship of their expression with clinical features including age at diagnosis, lymph node positivity and tumour size was analysed.
Results: We report that Dicer was significantly decreased while Drosha was significantly increased in tumours when compared to normal adjacent tissues. While there was no difference in Drosha expression in lymph node metastases when compared to the primary tumour, Dicer was significantly increased. There was no correlation between the expression of either Dicer or Drosha to age at diagnosis, lymph node positivity and tumour size. Conclusions: In conclusion, Dicer and Drosha are dysregulated in TNBC and matched lymph node metastases however, the clinical relevance of this is still not known. The altered expression of Dicer and Drosha may serve as markers for disrupted miRNA biogenesis in TNBC
Thyroid antibodies, autoimmunity and cognitive decline: is there a population-based link?
No full textBackground: Autoimmunity is considered an uncommon but under-recognised cause of cognitive decline. Methods: Serum samples from 3,253 randomly selected subjects enrolled in the Hunter Community Study, aged 55-85 years, were assayed for thyrotropin stimulatory hormone, anti-thyroid peroxidase antibodies (TPO-Ab), anti-nuclear antibodies (ANA) and extractable nuclear antigens (ENA). Cognitive function was assessed using the Audio Recorded Cognitive Screen (ARCS) tool. Results: TPO-Ab were found in 8.4% and ANA in 27.9% of the study population, of whom 3% had positive ENA findings. No relationship was found between the ARCS score and either TPO-Ab (coefficient = 0.133; 95% CI -0.20, 0.82, p = 0.616), ANA at a low (coefficient = 1.01; 95% CI -2.58, 0.55, p = 0.203) or a high titre (coefficient = -0.65; 95% CI -2.59, 1.28, p = 0.508), or ENA antibodies (coefficient = 5.12; 95% CI -0.53, 10.77; p = 0.076). Conclusions: Autoantibody findings are common in an aging population and are not associated with cognitive decline
Reactions, transformations and impacts of sulfur oxides during oxy-fuel combustion
No full textOxy-fuel combustion is one of the three main CO₂ capture and storage (CCS) technologies for coal-fired power generation; the other two being post-combustion and pre-combustion. Oxy-fuel combustion uses oxygen diluted with recycled flue gas as the oxidant rather than air to regulate temperature within the boiler. As a result, flue gas compositions are more concentrated in CO₂ and up to 4 times higher in impurities such as SOₓ and mercury. Emissions of SOₓ as well as condensation and deposition of corrosive sulfates are detrimental to processes utilised in oxy-fuel flow sheets and also to the plant efficiency. An understanding of the role and impacts of sulfur during coal combustion will benefit control of sulfur emissions and potential corrosion throughout the plant. It is vital for the Callide Oxy-fuel Project (COP) as no SOₓ and Hg removal is used at this plant due to the low sulfur coal used, as expected in all Australian plants. This study aims to establish an understanding of the reactions, transformations and impacts of SOₓ in oxy-fuel combustion by an experimental and theoretical study comparing oxy-fuel sulfur species with those in air firing for which plant impacts are known, including: (1) pilot scale coal combustion experiments to evaluate the overall impacts of coal quality on sulfur release and capture; (2) ash decomposition experiments to test the capture and retention of sulfur in the fly ash and the different sulfur species in fly ash; (3) conversion experiments to establish effects of different flue gas cleaning configurations on the pathways of SO₃ formation and the catalytic effect of fly ash on the conversion of SO₂ to SO₃; and (4) mercury and SOₓ interaction experiments to investigate the speciation and competition between mercury and SOₓ species in the bag filter. Ash produced during oxy-fuel combustion is expected to differ to ash produced during air combustion due to the higher CO₂ and SO₂ atmosphere in which it is generated. For a quantitative understanding of the sulfation behaviour of fly ash in oxy-fuel combustion, fly ash from three commercial Australian sub-bituminous coals were tested and decomposed under an inert atmosphere. Thermal evolved gas analysis was completed for ash produced in both air and oxy-fuel environments. Pure salts were also tested under the same conditions to allow identification of the species in the ash which potentially capture sulfur, along with thermodynamic modelling using FactSage 6.0. Sulfur evolved during the decomposition of air and oxy-fuel fly ash was compared with the total sulfur in the ash to close the sulfur balance. Both total sulfur captured by the ash and sulfur evolved during decomposition were higher for oxy-fuel fly ash than their air counterparts. The extent of sulfation resulting from thermal decomposition of oxy-fuel fly ash was 2 to 3 times greater than air fly ash. Correlations of capture with ash chemistry were attempted to show extent of sulfur capture and to identify active species in the fly ash responsible for the capture. The reaction of SO₂ with fly ash in the presence of O₂ and H₂O may lead to the formation of SO₃ and eventually H₂SO₄. Homogeneous experiments were conducted to evaluate the effects of the procedural variables: temperature, gas concentrations and residence time on the post-combustion conversion of SO₂ to SO₃. Results were compared to those predicted by existing global kinetics and found to be dependent on SO₂, O₂, residence time and temperature and independent of H₂O content. For a residence time of 1 s, at least 900°C is needed to have an observable conversion of SO₂ to SO₃. Literature suggests that the conversion of SO₂ to SO₃ is dependent on the iron oxide content of the fly ash. Experiments using the same fly ash were used to investigate the catalytic effects of fly ash on SO₂ conversion to SO₃ at a temperature range of 400°C to 1000°C. It was observed that fly ash acts as a catalyst in the formation of SO₃, with the largest conversion occurring at 700°C. Homogeneous reaction at 700°C, without fly ash present, converted 0.10% of the available SO₂ to SO₃. When fly ash was present the conversion increased to 1.78%. The catalytic effect accounts for roughly 95% of the total conversion at 700°C. Average SO₃/SO₂ conversion values between fly ash derived from air and oxy-fuel firing and under different flue gas environments were found to be similar. Increased mercury concentration is of concern because mercury is known to attack aluminium heat exchangers required in the compression of CO₂ during oxy-fuel combustion. A recent study has indicated that interaction of Hg and SOₓ may occur at oxy-fuel concentrations and so the competition between SOₓ and Hg was investigated in this study. The effect of Hg, SOx, H₂O and temperature on the native capture of Hg by fly ash was assessed using a quartz flow reactor packed with fly ash to simulate a bag filter. Doubling Hg in the system from 5 to 10 μg/Nm³ doubled the amount of Hg captured in the fly ash from 1.6 to 2.8% and increases the amount of Hg unaccounted from 5.8 to 18.1%. Increased SO₂ decreased the proportion of Hg⁰ in the flue gas. Temperature in the bag filter was found to have a huge impact on the mercury capture by fly ash. As temperature was increased from 90 to 200°C, Hg⁰ in the flue gas was found to increase from 77.9 to 98.3%, indicating better capture of Hg at lower temperatures. The COP is the largest existing plant utilising oxy-fuel technology that combines retrofit options for existing power plants; electricity generation and CO₂ processing. As there is no dedicated SOₓ, NOₓ and Hg removal in place, removal is expected to occur at the fabric filter or during compression. With higher SO₂, SO₃ and H₂SO₄ during oxy-fuel combustion, sulfur capture by the ash is higher compared to oxy-fuel firing. Higher SO₂ forms sulfates responsible for fireside corrosion, SO₃ captured in the fabric filter causes corrosion in the metal components while H₂SO₄ causes fouling of the air pre-heater (APH) and low temperature corrosion due to condensation of H₂SO₄ on surfaces. Shifting from air to oxy-fuel with full flue gas recycling can easily increase the H₂SO₄ dew point by as much as 60°C. Apart from corrosion and fouling, maintaining the APH at high temperature results in efficiency losses. Native mercury capture by the bag filter is also decreased with increasing ADP since the BF must be operated at much higher temperatures. With these reductions in capture at the bag filters due to an increase in operating BF temperature, downstream impacts in the CO₂ processing requiring a need for secondary Hg removals could be created
A serial-kinematic nanopositioner for high-speed atomic force microscopy
No full textA flexure-guided serial-kinematic XYZ nanopositioner for high-speed Atomic Force Microscopy is presented in this paper. Two aspects influencing the performance of serial-kinematic nanopositioners are studied in this work. First, mass reduction by using tapered flexures is proposed to increased the natural frequency of the nanopositioner. 25% increase in the natural frequency is achieved due to reduced mass with tapered flexures. Second, a study of possible sensor positioning in a serial-kinematic nanopositioner is presented. An arrangement of sensors for exact estimation of cross-coupling is incorporated in the proposed design. A feedforward control strategy based on phaser approach is presented to mitigate the dynamics and nonlinearity in the system. Limitations in design approach and control strategy are discussed in the Conclusion
Performance degradation in feedback control due to constraints
No full textIn this note, we present a method to characterize the degradation in performance that arises in linear systems due to constraints imposed on the magnitude of the control signal to avoid saturation effects. We do this in the context of cheap control for tracking step signals
Zero displacement microelectromechanical force sensor using feedback control
No full textConventional microscale force sensors use moving parts to infer applied forces. Whenever physical deformations are involved, the sensor characteristics become a function of mechanical parameters, and there is an inevitable trade-off between the sensitivity and measurement range. We developed a microfabricated force sensor that uses feedback control to nullify any displacements within the device, directly transducing forces as high as 1.5 mN with a 7.8 nN resolution. The range and sensitivity of the device no longer depend on mechanical parameters, which allow the same device to be used to test samples with a wide range of stiffnesses without loss of accuracy
Now I know why I have been knocking my head against a brick wall: doctoral candidates and stuck places
No full textThe research reported here was motivated by a comment from a doctoral candidate. I had asked her, as a Research Assistant not as a candidate working with me, to check a manuscript on Threshold Concepts in doctoral education in preparation for publication. Her main comment after reading the paper was, “If only I’d known that I was just in a stuck place it would have made it so much easier”. So began work with doctoral candidates to help them understand doctoral study as: an extended period of learning where the candidate might be in a liminal state until crossing the threshold of completion and ‘graduation’, and a period made up of a number of threshold crossings as candidates understand the various concepts that challenge them (Kiley, 2009), each preceded by a state of liminality and maybe being in a ‘stuck place’
Long-term corrosion of mild steel in natural and uv-treated coastal seawater
No full textHighly polished coupons (25 by 25 by 1.5 mm) sourced from the same steel sheet were continuously immersion-exposed either to natural coastal seawater or to seawater from the same source subjected to filtration and UV irradiation to eliminate microbiologically influenced corrosion as much as possible. This was continued for 943 days (2.6 years). Dissolved oxygen levels were very similar in both environments. On average the UV-treated seawater was 2°C warmer, but all coupons exposed to it showed less localized corrosion than those exposed to natural seawater. The typical topographical difference was about 60% as measured by surface roughness parameter Sa. Mass losses in UV-treated seawater were about 10% higher than in natural seawater, but after temperature correction were similar to natural seawater for the first year and tended to be lower subsequently. At all exposure periods the rusts in UV-treated seawater were less voluminous than the rusts in natural seawater. Eventually they also contained a higher proportion of magnetite