Ambulatory human motion tracking by fusion of inertial and magnetic sensing with adaptive actuation

Over the last years, inertial sensing has proven to be a suitable ambulatory alternative to traditional human motion tracking based on optical position measurement systems, which are generally restricted to a laboratory environment. Besides many advantages, a major drawback is the inherent drift caused by integration of acceleration and angular velocity to obtain position and orientation. In addition, inertial sensing cannot be used to estimate relative positions and orientations of sensors with respect to each other. In order to overcome these drawbacks, this study presents an Extended Kalman Filter for fusion of inertial and magnetic sensing that is used to estimate relative positions and orientations. In between magnetic updates, change of position and orientation are estimated using inertial sensors. The system decides to perform a magnetic update only if the estimated uncertainty associated with the relative position and orientation exceeds a predefined threshold. The filter is able to provide a stable and accurate estimation of relative position and orientation for several types of movements, as indicated by the average rms error being 0.033 m for the position and 3.6 degrees for the orientation

A stakeholder analysis of the perceived outcomes of developing and implementing England’s obesity strategy 2008–2011

Background International recommendations urge governments to implement population-based strategies to reduce the burden of obesity. This study assesses the development and implementation of the obesity strategy in England 2008–2011, Healthy Weight, Healthy Lives (HWHL). The aim was to identify if stakeholders perceived HWHL to have made any difference to the action to address obesity in England, with the ultimate objective of identifying insights that could inform the development and implementation of future obesity strategies in England and elsewhere. Methods Qualitative study using semi-structured interviews and thematic framework analysis. 40 stakeholders involved in the development and implementation of the obesity strategy were interviewed. Results Evidence from this study suggests that HWHL was perceived to have made a positive difference to efforts to address obesity in England. It was credited with creating political buy-in, engaging more stakeholders, stimulating and facilitating action, enhancing knowledge and changing attitudes. But it was reported to have failed to fully catalyse action across all government departments and sectors, or to develop adequate mechanisms for learning about the effectiveness of the different elements and actions in the Strategy. Key elements of the Strategy contributing towards to the perceived positive differences included its multi-faceted, inclusive nature; governance structures; monitoring programme to assess progress against national and local targets; child-focus; and funding. The development of the Strategy was said to be stimulated and aided by the prior synthesis of a critical mass of scientific evidence. Conclusions The English experience of HWHL lends support to the recommendations to develop population-based obesity strategies. It indicates that in order to stimulate comprehensive, inter-sectoral action, obesity strategies need to take a population-based, multi-faceted approach, be implemented through a clear governance structure, follow a systematic process of aligning goals, objectives and agendas between government departments and sectors with a stake in obesity, and have a clear system of reporting changes in obesity rates against a target. In order to design effective policies and to build the case for continued investment, obesity strategies also need to incorporate a national framework for learning and evaluation from the outset

Radionuclide imaging of bone marrow disorders

Noninvasive imaging techniques have been used in the past for visualization the functional activity of the bone marrow compartment. Imaging with radiolabelled compounds may allow different bone marrow disorders to be distinguished. These imaging techniques, almost all of which use radionuclide-labelled tracers, such as 99mTc-nanocolloid, 99mTc-sulphur colloid, 111In-chloride, and radiolabelled white blood cells, have been used in nuclear medicine for several decades. With these techniques three separate compartments can be recognized including the reticuloendothelial system, the erythroid compartment and the myeloid compartment. Recent developments in research and the clinical use of PET tracers have made possible the analysis of additional properties such as cellular metabolism and proliferative activity, using 18F-FDG and 18F-FLT. These tracers may lead to better quantification and targeting of different cell systems in the bone marrow. In this review the imaging of different bone marrow targets with radionuclides including PET tracers in various bone marrow diseases are discussed

Thermal Perceptual Thresholds are typical in Autism Spectrum Disorder but Strongly Related to Intra-individual Response Variability

Individuals with autism spectrum disorder (ASD) are often reported to exhibit an apparent indifference to pain or temperature. Leading models suggest that this behavior is the result of elevated perceptual thresholds for thermal stimuli, but data to support these assertions are inconclusive. An alternative proposal suggests that the sensory features of ASD arise from increased intra-individual perceptual variability. In this study, we measured method-of-limits warm and cool detection thresholds in 142 individuals (83 with ASD, 59 with typical development [TD], aged 7–54 years), testing relationships with diagnostic group, demographics, and clinical measures. We also investigated the relationship between detection thresholds and a novel measure of intra-individual (trial-to-trial) threshold variability, a putative index of “perceptual noise.” This investigation found no differences in thermal detection thresholds between individuals with ASD and typical controls, despite large differences between groups in sensory reactivity questionnaires and modest group differences in intra-individual variability. Lower performance IQ, male sex, and higher intra-individual variability in threshold estimates were the most significant predictors of elevated detection thresholds. Although no psychophysical measure was significantly correlated with questionnaire measures of sensory hyporeactivity, large intra-individual variability may partially explain the elevated psychophysical thresholds seen in a subset of the ASD population

Musculoskeletal model-based inverse dynamic analysis under ambulatory conditions using inertial motion capture

Inverse dynamic analysis using musculoskeletal modeling is a powerful tool, which is utilized in a range of applications to estimate forces in ligaments, muscles, and joints, non-invasively. To date, the conventional input used in this analysis is derived from optical motion capture (OMC) and force plate (FP) systems, which restrict the application of musculoskeletal models to gait laboratories. To address this problem, we propose the use of inertial motion capture to perform musculoskeletal model-based inverse dynamics by utilizing a universally applicable ground reaction force and moment (GRF&M) prediction method. Validation against a conventional laboratory-based method showed excellent Pearson correlations for sagittal plane joint angles of ankle, knee, and hip ( 0.99, and 0.99, respectively) and root-mean-squared-differences (RMSD) of 4.1 ± 1.3°, 4.4 ± 2.0°, and 5.7 ± 2.1°, respectively. The GRF&M predicted using IMC input were found to have excellent correlations for three components (vertical: RMSD = 9.3 ± 3.0 %BW, anteroposterior: RMSD = 5.5 ± 1.2 %BW, sagittal: RMSD = 1.6 ± 0.6 %BW*BH), and strong correlations for mediolateral ( RMSD = 2.1 ± 0.6 %BW) and transverse ( RMSD = 0.2 ± 0.1 %BW*BH). The proposed IMC-based method removes the complexity and space restrictions of OMC and FP systems and could enable applications of musculoskeletal models in either monitoring patients during their daily lives or in wider clinical practice