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(2008)Journal ArticlePurpose: Despite the established importance of the role of family history in prostate cancer, relatively little research encompasses the psychosocial issues relevant to unaffected men with a family history of prostate cancer. To determine the completeness and quality of available literature on the issues faced by men with a high risk of prostate cancer, we conducted a multidisciplinary review of the literature to provide some guidance on the information that clinicians might provide to men who are concerned about family history. Materials and Methods: A structured literature search was conducted by a multidisciplinary team of clinicians and researchers who reviewed the medical and psychosocial literature, and identified 21 relevant studies. Results: Research suggests that many high risk patients are concerned about the risk of prostate cancer, and some may significantly overestimate that risk. Several studies have shown high screening rates among high risk patients and high levels of interest in genetic testing for prostate cancer risk should it become available, yet many men also report a desire for more information about their personal risk and risk management options. Conclusions: Given the lack of clear data on the efficacy of prostate cancer screening among high risk patients, clinicians could consider providing men who are concerned about family history with information on their personal risk, help them to clarify the potential benefits, limitations and harms of prostate cancer screening in their situation, and then support their choice regarding the management of prostate cancer risk.
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(2013)Journal ArticleThe autoignition of dimethyl ether (DME) with temperature inhomogeneities is investigated by one-dimensional numerical simulations with detailed chemistry at high pressure and a constant volume. The primary purpose of the study is to provide an understanding of the autoignition of DME in a simplified configuration that is relevant to homogeneous charge compression ignition (HCCI) engines. The ignition structure and the negative temperature coefficient (NTC) behaviour are characterised in a homogeneous domain and one-dimensional domains with thermal stratification, at different initial mean temperatures and length scales. The thermal stratification is shown to strongly affect the spatial structure and temporal progress of ignition. The importance of diffusion and conduction on the ignition progress is assessed. It is shown that the effects of molecular diffusion decay relative to those of chemical reaction as the length-scale increases. This is to be expected, however the present study shows that these characteristics also depend on the mean temperature due to NTC behaviour. For the range of conditions studied here, which encompass a range of stratification length scales expected in HCCI engines, the effects of molecular transport are found to be small compared with chemical reaction effects for mean temperatures within the NTC regime. This is in contrast to previous work with fuels with single-stage ignition behaviour where practically realisable temperature gradients can lead to molecular transport effects becoming important. In addition, thermal stratification is demonstrated to result in significant reductions of the pressure-rise rate (PRR), even for the present fuel with two-stage ignition and NTC behaviour. The reduction of PRR is however strongly dependent on the mean initial temperature. The stratification length-scale is also shown to have an important influence on the pressure oscillations, with large-amplitude oscillations possible for larger length scales typical of integral scales in HCCI engines.
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(2008)Journal ArticlePurpose – The purpose of this paper is to present a localisation system for an indoor rotary-wing micro aerial vehicle (MAV) that uses three onboard LEDs and base station mounted active vision unit. Design/methodology/approach – A pair of blade mounted cyan LEDs and a tail mounted red LED are used as on-board landmarks. A base station tracks the landmarks and estimates the pose of the MAV in real time by analysing images taken using an active vision unit. In each image, the ellipse formed by the cyan LEDs is used for 5 degree of freedom (DoF) pose estimation with yaw estimation from the red LED providing the 6th DoF. Findings – About 1-3.5 per cent localisation error of the MAV at various ranges, rolls and angular speeds less than 45°/s relative to the base station at known location indicates that the MAV can be accurately localised at 9-12?Hz in an indoor environment. Research limitations/implications – Line-of-sight between the base station and MAV is necessary while limited accuracy is evident in yaw estimation at long distances. Additional yaw sensors and dynamic zoom are among future work. Practical implications – Provided an unmanned ground vehicle (UGV) as the base station equipped with its own localisation sensor, the developed system encourages the use of autonomous indoor rotary-wing MAVs in various robotics applications, such as urban search and rescue. Originality/value – The most significant contribution of this paper is the innovative LED configuration allowing full 6 DoF pose estimation using three LEDs, one camera and no fixed infrastructure. The active vision unit enables a wide range of observable flight as the ellipse generated by the cyan LEDs is recognisable from almost any direction.
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(2008)Journal ArticleThis paper presents a non-line-of-sight (NLOS) localization technique and its system for a quiet and known environment that uses first-arrival low-frequency acoustic signals. The proposed technique first measures the time-of-arrivals (ToAs) of the first-arrival low-frequency sounds. The technique then estimates the location of a target by minimizing the differences between the measured ToAs and the corresponding ToAs estimated from the known map. The strength of the proposed technique is that the positioning accuracy is not corrupted by any small or known obstacle. The performance of the technique was investigated by its comparison to other techniques in both simulations and an experiment. The numerical results show successful localization of a target in various situations, demonstrating the efficacy of the technique and system as a feasible solution for NLOS mitigation.
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(2008)Journal ArticleA Computational Fluid Dynamics investigation was conducted to ascertain and highlight the different ways in which ground effect phenomena are present around both an upright (lift generating) and inverted (downforce generating) cambered aerofoil when in close proximity to the ground. The trends in force and flow field behaviour were observed at various ground clearances, while the angle of attack was held constant at 6 degrees. The different mechanisms by which ground effect influences the two different configurations were highlighted through observation of the pressure coefficient plots, contour maps of velocity and turbulence intensity and their effect on the normal and drag forces. The primary contributing factor to the increase in normal force for the lifting aerofoil, as the ground was approached, was a constriction and rise in pressure of the flow. For the downforce aerofoil, a significantly sped up flow increased suction and enhanced downforce. Also discussed is the observation of a reduction in lift for the upright aerofoil as its ground clearance is reduced through high and medium clearances.
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(1995)Journal Article
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(2001)Journal ArticleThis article reports findings on the reliabilities of peer and teacher summative assessments of engineering students’ oral presentation skills in a fourth year communications subject. The context of the study is unusual, in that each oral presentation was subject to multiple ratings by teams of students and teams of academic staff. Analysis of variance procedures were used to provide separate estimates of inter-rater reliability of assessments by peers and teachers for classes in four succeeding years. Teacher ratings were found to have substantially higher levels of inter-rater agreement than peer ratings. Generalising over the four years, it would require the averaging of between two and four peer ratings to match the reliability of single teacher assessments. However, the estimates of individual rater reliability for teachers, based on the intra-class correlation coefficient, were moderately low (0.40 to 0.53). It is concluded that the reliability of summative assessments of oral presentations can be improved by combining teacher marks with the averaged marks obtained from multiple peer ratings.
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(2006)Journal ArticleTwo kinds of Al2O3/Ti(C0.7N0.3) nanocomposites were fabricated with traditional hot pressed sintering and repetitious-hot-pressing technology, one is added with nano-scale SiC, and the other is without SiC. The results showed that the mechanical properties of the former are higher than that of the latter, especially the fracture toughness can reach up to 8.3 MPa m1/2. Although the fracture toughness remains high, repetitious-hot-pressing results in the reduction of flexural strength. The improvement of the mechanical properties is interpreted from the different microstructure and fracture mode. The microstructure shows that the addition of nano-scale Ti(C0.7N0.3) and nano-scale SiC lead to the refinement of matrix grain, and the inter/intragranular microstructure can be formed instead of the intergranular microstructure in monolithic alumina. The higher fracture toughness resulted mainly from the transgranular fracture mode.
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(2006)Journal Article20 wt% TiN/3Y-TZP mixed with an amount of less than 15 wt% Al2O3 particles has been fabricated by hot-pressing techniques, and the mechanical properties and microstructure were investigated. There is a good chemical compatibility among ZrO2, TiN and Al2O3 and the addition of 5 wt% Al2O3 can improve the densification of composites. Al2O3 particles have little effect on improving flexural strength but have a distinct effect on toughening for 20 wt% TiN/3Y-TZP, which may be due to the residual stresses and microcracks resulting from the mismatch between the expansion coefficients of Al2O3 and ZrO2. An amount of 5 wt% Al2O3 in 20 wt% TiN/3Y-TZP can improve the bonding strength among grains and change the fracture pattern from intergranular to transgranular fracture.