Fingerprint-based indoor localisation suffers from influences such as fingerprint pre-collection, environment changes and expending a lot of manpower and time to update the radio map. To solve the problem, we propose an efficient radio map updating algorithm based on K-Means and Gaussian Process Regression (KMGPR). The algorithm builds a Gaussian Process Regression (GPR) predictive model based on a Gaussian mean function and realises the update of the radio map using K-Means. We have conducted experiments to evaluate the performance of the proposed algorithm and results show that GPR using the Gaussian mean function improves localisation accuracy by about 13·76% compared with other functions and KMGPR can reduce the computational complexity by about 7% to 20% with no obvious effects on accuracy.

The observability of error states in Inertial Navigation System/Global Positioning System (INS/GPS) integration is of great importance. Rank tests or null space tests of the observability matrix have been adopted by previous works, however, for a time-varying system with a high-dimension error state vector, it is very difficult to analyse the observability matrix by these traditional methods. In this paper, the decoupled observability analysis method is proposed for an 18-dimensional INS/GPS integration system. By reducing the dimension of coupling error states, several six-dimensional decoupled observability sub-matrices are obtained, which make the observability analyses easier. The observability results of error states are obtained by the proposed method. Covariance simulation with an Extended Kalman filter (EKF) and a flying test were performed which confirmed the theoretical results.

Background: Investigations of mental health literacy are important because the recognition of a mental health problem is the first step in seeking appropriate mental health care. Lack of recognition is a significant barrier to accessing mental health resources. Older Chinese immigrants are at increased risk for depression; however, there is no research investigating their depression literacy, including their beliefs about treatment, etiology, and prognosis.

Methods: This study investigated depression literacy among 53 older Chinese immigrants in Canada (aged 55–87 years) and compared their literacy to Canadian-born participants of the same age who were part of a larger population-based survey. Depression literacy was assessed through interviews using a case vignette and included the following indices: rates of correct identification of depression; perceived efficacy of various people, professions and treatments; and perceptions of etiology and prognosis.

Results: In the Chinese sample, 11.3% correctly identified depression in the case vignette. In contrast, 74.0% of participants in the population-based survey correctly identified depression. Differences in the perceptions of helpful people and interventions, etiology, and prognosis were also noted between the samples. Both samples strongly endorsed physical activity as helpful in the treatment of depression.

Conclusions: In light of these results, it is clear that older Chinese immigrants would benefit from information regarding the symptoms, etiology, and treatment of depression, and that this information may begin to address the serious underutilization of mental health services among this group. Our discussion highlights practice implications and promising interventions.

The microstructures and mechanical properties of Mg–6Zn–5Al–4Gd–1RE (RE = Ce or Y) alloys were investigated. The addition of Ce or Y obviously refines the grain size for the Mg–6Zn–5Al–4Gd-based alloy, while the Y element has a better refining effect. The Ce and Y show different grain-refining mechanisms: Ce addition mostly promotes the growth of secondary dendrite, while Y addition mainly increases the heterogeneous nucleation sites. The hardness-versus-aging time curves indicate that all the alloys have excellent aging-hardening behavior, but the response to maximum hardness was delayed by the Ce or Y addition. The microstructure observation of the peak-aged alloys indicated a large number of nanocrystalline τ-Mg32(Al, Zn)49 precipitates in the matrix. The Y addition is beneficial to improve the mechanical properties, and the alloy has optimal values. However, the Ce addition decreases the ultimate tensile strength and elongation of the alloy due to formation of a lot of shrinkage porosities.

Background. Few epidemiological studies have examined the temporal relationship between chronic pain and depression using longitudinal data. In the present study, we examined major depression as both an antecedent risk factor and consequence of chronic back pain (CBP) in the general population.

Method. Data on 9909 pain-free individuals 15 years and older with no history of back problems were drawn from cycle 1 of the National Population Health Survey and followed up 24 months later. Major depression was assessed using a structured diagnostic interview.

Results. At cycle 2, the rate of new cases of CBP in persons who were depressed at cycle 1 was 3·6% compared to 1·1% in non-depressed persons. Compared to pain-free individuals, new cases of CBP were more likely to perceive their health status as poor or fair at cycle 1, were less likely to be working, reported more chronic health problems, and sustained a back or neck injury in the preceding 12 months. After controlling for other factors, pain-free individuals diagnosed as major depressed at cycle 1 were almost three times more likely (OR 2·9, 95% CI 1·2–7·0) to develop CBP at cycle 2.

Conclusions. Consistent with other longitudinal studies major depression increases the risk of developing future chronic pain. The causal mechanism linking these conditions is unknown however depression may represent a modifiable risk factor in the development of CBP.

Background. Major depression is a prevalent mental disorder in the general population, with a multi-factorial etiology. However, work stress as a risk factor for major depression has not been well studied.

Method. Using a longitudinal study design, this analysis investigated the association between the levels of work stress and major depressive episode(s) in the Canadian working population, aged 18 to 64 years. Data from the longitudinal cohort of the Canadian National Population Health Survey (NPHS) were used (n=6663). The NPHS participants who did not have major depressive episodes (MDE) at baseline (1994–1995 NPHS) were classified into four groups by the quartile values of the baseline work stress scores. The proportion of MDE of each group was calculated using the 1996–1997 NPHS data.

Results. The first three quartile groups had a similar risk of MDE. Those who had a work stress score above the 75th percentile had an elevated risk of MDE (7·1%). Using the 75th percentile as a cut-off, work stress was significantly associated with the risk of MDE in multivariate analysis (odds ratio=2·35, 95% confidence interval 1·54–3·77). Other factors associated with MDE in multivariate analysis included educational level, number of chronic medical illnesses and child and adulthood traumatic events. There was no evidence of effect modification between work stress and selected sociodemographic, clinical and psychosocial variables.

Conclusions. Work stress is an independent risk factor for the development of MDE in the working population. Strategies to improve working environment are needed to keep workers mentally healthy and productive.

Miniature and microscale fuel processors that incorporate novel catalysts and microtechnology-based designs are discussed. The novel catalyst allows for methanol reforming at high gas hourly space velocities of 50,000 hr-1 or higher while maintaining a carbon monoxide levels at 1% or less. The microtechnology-based designs extremely compact and lightweight devices. The miniature fuel processors, with a volume less than 25 cm3, a mass less than 200 grams, and thermal efficiencies of up to 83%, nominally provide 25 to 50 watts equivalent of hydrogen, which is ample for the portable power supplies described here. With reasonable assumptions on fuel cell efficiencies, anode gas and water management, parasitic power loss, the energy density was estimated at 1700 Whr/kg. These processors have been demonstrated with a CO cleanup method and a fuel cell stack. The microscale fuel processors, with a volume of less than 0.25 cm3 and a mass of less than 1 gram, are designed to provide up to 0.3 watt equivalent of power with efficiencies over 20%.