On the importance of the first observation in GLS detrending in unit root testing

First-differencing is generally taken to imply the loss of one observation, the first, or at least that the effect of ignoring this observation is asymptotically negligible. However, this is not always true, as in the case of generalized least squares (GLS) detrending. In order to illustrate this, the current article considers as an example the use of GLS detrended data when testing for a unit root. The results show that the treatment of the first observation is absolutely crucial for test performance, and that ignorance causes test break-down.

Microstructure and mechanical properties of Ti-15Zr alloy used as dental implant material

Ti-Zr alloys have recently started to receive a considerable amount of attention as promising materials for dental applications. This work compares mechanical properties of a new Ti-15Zr alloy to those of commercially pure titanium Grade4 in two surface conditions - machined and modified by sand-blasting and etching (SLA). As a result of significantly smaller grain size in the initial condition (1-2µm), the strength of Ti-15Zr alloy was found to be 10-15% higher than that of Grade4 titanium without reduction in the tensile elongation or compromising the fracture toughness. The fatigue endurance limit of the alloy was increased by around 30% (560MPa vs. 435MPa and 500MPa vs. 380MPa for machined and SLA-treated surfaces, respectively). Additional implant fatigue tests showed enhanced fatigue performance of Ti-15Zr over Ti-Grade4.

Chronic condition management and self-management in Aboriginal communities in South Australia : outcomes of a longitudinal study

OBJECTIVES: This paper describes the longitudinal component of a larger mixed methods study into the processes and outcomes of chronic condition management and self-management strategies implemented in three Aboriginal communities in South Australia. The study was designed to document the connection between the application of structured systems of care for Aboriginal people and their longer-term health status. METHODS: The study concentrated on three diverse Aboriginal communities in South Australia; the Port Lincoln Aboriginal Health Service, the Riverland community, and Nunkuwarrin Yunti Aboriginal Health Service in the Adelaide metropolitan area. Repeated-measure clinical data were collected for individual participants using a range of clinical indicators for diabetes (type 1 and 2) and related chronic conditions. Clinical data were analysed using random effects modelling techniques with changes in key clinical indicators being modelled at both the individual and group levels. RESULTS: Where care planning has been in place longer than in other sites overall improvements were noted in BMI, cholesterol (high density and low density lipids) and HbA1c. These results indicate that for Aboriginal patients with complex chronic conditions, participation in and adherence to structured care planning and self-management strategies can contribute to improved overall health status and health outcomes. CONCLUSIONS: The outcomes reported here represent an initial and important step in quantifying the health benefits that can accrue for Aboriginal people living with complex chronic conditions such as diabetes, heart disease and respiratory disease. The study highlights the benefits of developing long-term working relationships with Aboriginal communities as a basis for conducting effective collaborative health research programs.

The internal consistency and construct validity of the partners in health scale : validation of a patient rated chronic condition self-management measure

PURPOSE: The purpose of this study was to test the internal consistency and construct validity of the revised 12-item self-rated Partners in Health (PIH) scale used to assess patients' chronic condition self-management knowledge and behaviours. METHODS: Baseline PIH data were collected for a total of 294 patients with a range of co-morbid chronic conditions including diabetes, cardiovascular disease and arthritis. Scale data for the initial sample of 176 patients were analysed for internal consistency and construct validity using Reliability Analysis and Factor Analysis. Construct validity was tested in a separate sample of 118 patients using confirmatory factor analysis and a structural equation model. RESULTS: Good internal consistency was indicated with a Cronbach's alpha coefficient of 0.82 in the initial sample. Factor analysis for this sample revealed four key factors (knowledge, coping, management of condition and adherence to treatment) across the twelve items of the scale. These four key factors were then confirmed by applying the exploratory structural equation model to the separate sample. CONCLUSION: The PIH scale exhibits construct validity and internal consistency. It therefore is both a generic self-rated clinical tool for assessing self-management in a range of chronic conditions as well as an outcome measure to compare populations and change in patient self-management knowledge and behaviour over time. The four domains of self-management provide a valid measure of patient competency in relation to the self-management of their chronic condition(s).

Extending light-weighting and mass-production of ultra high strength steels via condition-based maintenance

The use of ultra high strength steels (UHSS) in the automotive industry presents a significant opportunity for continued vehicle light-weighting, due to possible strength-to-weight improvements of three to four times that of conventional sheet steel grades. This performance benefit is achievable whist maintaining most of the advantages of low-cost mass-production associated with the cold stamping of sheet steel for automotive body components. However, the introduction of UHSS can result in significantly increased wear of the stamping tools, which is difficult to predict at the design stage and can lead to unexpected process failure during mass-production. Therefore, there is a need to be able to monitor and predict the onset of severe wear, such that the best course of condition-based maintenance can be scheduled and unscheduled stoppages due to tool wear eradicated. This paper describes a novel active monitoring system that is being developed by researchers at Deakin University, The Australian National University and Ford Motor Company, Asia Pacific and Africa. The aim of the active monitoring system is to detect the initial onset of a change of state, such as wear, through the measurement of variables such as punch force and audio signals. A semi-industrial stamping process, using a progressive die setup and high strength steel sheet with hardened tool steel tooling, is the experimental basis for the initial model and system development.

Initial destination hospital of paediatric prehospital patients in rural Victoria.

OBJECTIVE: The objective of this present study was to describe the initial destination hospital of paediatric patients transported by Ambulance Victoria paramedics within the South Western area of Victoria to determine the proportion of patients that bypassed their closest hospital. METHODS: All Ambulance Victoria primary ambulance transports for paediatric patients aged 1 month to 14 years in the Barwon South West region between 1 April 2008 and 28 February 2011 were reviewed. Each case was examined to determine the destination hospital location relative to the case scene location, and the overall nature of each case was grouped into one of seven categories (medical respiratory, medical cardiac, medical neurological, medical other, trauma time critical, and trauma non-time critical). RESULTS: There were 1191 cases identified, with 978 (82%) being taken to the closest hospital and 213 (18%) to a more distant facility. The average distance travelled from the scene to the destination hospital was 15.2 km, and almost 90% of patients transported to the nearest hospital were within 15 km of that hospital. Time critical trauma cases and respiratory-related medical cases had higher rates of transport to more distant hospitals as their initial destination (26% to non-closest and 23% to non-closest, respectively). CONCLUSION: The patient's condition and their location relative to the larger medical facilities appear to influence the decision of destination hospital. Uncertainty regarding the availability of 24 h hospital services and staffing details may contribute to longer transfers.