Use of acoustic emission to identify novel candidate biomarkers for knee osteoarthritis (OA)

Our objective was to determine the efficacy and feasibility of a new approach for identifying candidate biomarkers for knee osteoarthritis (OA), based on selecting promising candidates from a range of high-frequency acoustic emission (AE) measurements generated during weight-bearing knee movement. Candidate AE biomarkers identified by this approach could then be validated in larger studies for use in future clinical trials and stratified medicine applications for this common health condition. A population cohort of participants with knee pain and a Kellgren-Lawrence (KL) score between 1-4 were recruited from local NHS primary and secondary care sites. Focusing on participants’ self-identified worse knee, and using our established movement protocol, sources of variation in AE measurement and associations of AE markers with other markers were explored. Using this approach we identified 4 initial candidate AE biomarkers, of which “number of hits” showed the best reproducibility, in terms of within-session, day to day, week to week, between-practitioner, and between-machine variation, at 2 different machine upper frequency settings. “Number of hits” was higher in knees with KL scores of 2 than in KL1, and also showed significant associations with pain in the contralateral knee, and with body weight. “Hits” occurred predominantly in 2 of 4 defined movement quadrants. The protocol was feasible and acceptable to all participants and professionals involved. This study demonstrates how AE measurement during simple sit-stand-sit movements can be used to generate novel candidate knee OA biomarkers. AE measurements probably reflect a composite of structural changes and joint loading factors. Refinement of the method and increasing understanding of factors contributing to AE will enable this approach to be used to generate further candidate biomarkers for validation and potential use in clinical trials

Detection of Aircraft Component Defects Using Low Voltage Excitation of Ultrasonic Transducers

Large areas of composite primary structure are now to be found both on civil and military aircraft throughout the world and the inspection of these structures contributes significantly to overall operating costs. Therefore methods to reduce the inspection time, whilst maintaining an acceptable minimum defect detection capability, are required in order to optimize the potential cost saving benefits offered by using that carbon fiber composite material.</p

A new method for generating site-specific clutter map for land based radar by using multimodal remote sensing images and digital terrain data

By using multimodal remote-sensing images and digital terrain data of the environment, this study presents a new method for generating the clutter map specific to the selected land radar site and the radar’s operating parameters. In the proposed method, the estimation of backscattering from the environment involves extrapolation of the airborne radar remote-sensing image to provide a detailed description of terrain types, use of digital terrain elevation data with the land radar position and height to provide local grazing angles and a terrain visibility map and use of the digital topographic map to provide the geometric reference for all data sets. Using actual remote-sensing images and digital terrain data acquired from a real environment with various terrain features, the clutter map generated by the proposed method for land based radar is compared with that generated by a comprehensive modelling method, The accuracy of the proposed method is demonstrated based on the differences with respect the actual clutter measurements using a different airborne radar-sensing configuration

Frame synchronisation methods for digital satellite systems

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Exploratory study of a non-invasive method based on acoustic emission for assessing the dynamic integrity of knee joints

The paper presents the development of a new measurement system based on acoustic emission (AE) for assessing the dynamic integrity of knee joints, and the evaluation of its efficacy, through an exploratory study using healthy and osteoarthritic knees. For the former, the paper describes the system implemented to acquire joint angle-based AE and the protocol developed to obtain repeatable results. For the latter, the paper reports significant differences between healthy and osteoarthritic knees using statistical analysis of AE occurrence and distribution of AE features in different movement phases. Osteoarthritic knees are found to produce 6–10 times more acoustic emissions than healthy knees, with amplitudes which can be 20 dB higher, and durations which can be 10 times longer. These findings lead to a visual representation method of AE feature profiles based on multidimensional density of AE hits per repeated movement and the use of principal component analysis for objective assessment of the clinical status of knee joints