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Full-field non-destructive evaluation techniques are useful tools for indicating damage in fatigue-prone environments. Here, the full-field technique thermoelastic stress analysis (TSA) is employed to locate and track naturally initiating cracks in aluminium alloy specimens. An algorithm, based on the concept of optical flow, is used to track changes in the characteristic stress field present ahead of a crack during loading, and thereby to locate the crack-tip position. The initiation of cracks is indicated at sub-mm lengths, before the crack is observable by visual inspection, and in bolted specimens TSA indicates the presence of a crack before it extends beyond the bolt-head. The crack path propagation is mapped and matches well with the final crack geometry. Results are equivalent for surfaces prepared with matt black and aircraft primer paint, showing that optical flow processing of TSA data would be particularly useful for crack tracking in aerospace applications, as no additional surface preparation would be required to implement full-field TSA measurements.

Background. Asthma education and action plans (AP) have been recognized as important components in the optimal management of asthma. Studies have differed on the importance of a peak flow-based self-management plans in reducing health care costs and use due to asthma exacerbation. Objective. To analyze the cost-effectiveness of peak flow-based action plans in reducing costs associated with ER visits and hospitalizations due to acute asthma exacerbation in a population of high-risk and high-cost patients, defined as patients with moderate to severe asthma with a history of recent urgent treatment in the ER or hospitalization due to asthma. Methods. A literature review of randomized clinical trials comparing peak flow-based (PFB) action plans, symptom-based (SB) action plans, and usual care/no action plan (NAP) was performed. Probability values regarding the effectiveness of each alternative (as measured by increase/decrease in ER visits and hospitalizations over a 6-month period) were derived. Incremental cost-effectiveness and cost-benefit ratios were calculated for each alternative. Sensitivity analyses were performed. Results. For highrisk and high-cost asthma patients, our analysis revealed that the most cost-effective alternative for reducing ER visits was a peak flow-based self-management plan. The peak flow-based self-management program had an incremental costeffectiveness (C/E) ratio of $ 60.57 per ER visit averted compared to usual care/NAP and a C/E ratio of $31.46 compared to the SB-AP. The PFB-AP was also the most cost-effective in reducing asthma hospitalization costs with an

The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) offers transfemoral amputees an ambulatory method potentially reducing soft tissue complications seen with socket and stump devices. This study validated a finite element (in silico) model based on an ITAP design and investigated implant stem stiffness influence on periprosthetic femoral bone strain. Results showed good agreement in the validation of the in silico model against the in vitro results using uniaxial strain gauges and Digital Image Correlation (DIC). Using Strain Energy Density (SED) thresholds as the stimulus for adaptive bone remodelling, the validated model illustrated that: (a) bone apposition increased and resorption decreased with increasing implant stem flexibility in early stance; (b) bone apposition decreased (mean change = 2 9.8%) and resorption increased (mean change = 20.3%) from distal to proximal in most stem stiffness models in early stance. By engineering the flow of force through the implant/ bone (e.g. by changing material properties) these results demonstrate how periprosthetic bone remodelling, thus aseptic loosening, can be managed. This paper finds that future implant designs should be optimised for bone strain under a variety of relevant loading conditions using finite element models to maximise the chances of clinical success.

Thermoelastic stress analysis using arrays of small, low-cost detectors has the potential to be used in structural health monitoring. However, evaluation of the collected data is challenging using traditional methods, due to the lower resolution of these sensors, and the complex loading conditions experienced. An alternative method has been developed, using image decomposition to generate feature vectors which characterize the uncalibrated map of the magnitude of the thermoelastic effect. Thermal data have been collected using a state-of-the-art photovoltaic effect detector and lower cost, lower thermal resolution microbolometer detectors, during crack propagation induced by both constant amplitude and frequency loading, and by idealized flight cycles. The Euclidean distance calculated between the feature vectors of the initial and current state can be used to indicate the presence of damage. Cracks of the order of 1 mm in length can be detected and tracked, with an increase in the rate of change of the Euclidean distance indicating the onset of critical crack propagation. The differential feature vector method therefore represents a substantial advance in technology for monitoring the initiation and propagation of cracks in structures, both in structural testing and in-service using low-cost sensors.