A Systematic Review of Wearable Sensors for Monitoring Physical Activity

This article reviews the use of wearable sensors for the monitoring of physical activity (PA) for different purposes, including assessment of gait and balance, prevention and/or detection of falls, recognition of various PAs, conduction and assessment of rehabilitation exercises and monitoring of neurological disease progression. The article provides in-depth information on the retrieved articles and discusses study shortcomings related to demographic factors, i.e., age, gender, healthy participants vs patients, and study conditions. It is well known that motion patterns change with age and the onset of illnesses, and that the risk of falling increases with age. Yet, studies including older persons are rare. Gender distribution was not even provided in several studies, and others included only, or a majority of, men. Another shortcoming is that none of the studies were conducted in real-life conditions. Hence, there is still important work to be done in order to increase the usefulness of wearable sensors in these areas. The article highlights flaws in how studies based on previously collected datasets report on study samples and the data collected, which makes the validity and generalizability of those studies low. Exceptions exist, such as the promising recently reported open dataset FallAllD, wherein a longitudinal study with older adults is ongoing.

Revealing sound-induced motion patterns in fish hearing structures in 4D: A standing wave tube-like setup designed for high-resolution time-resolved tomography

Modern bony fishes possess a high morphological diversity in the auditory structures and their auditory capabilities. Yet, our knowledge of how the auditory structures such as the otoliths in the inner ears and the swim bladder work together remains elusive. Gathering experimental evidence on the in-situ motion of fish auditory structures while avoiding artifacts caused by surgical exposure of the structures has been challenging for decades. Synchrotron radiation-based tomography with high spatio-temporal resolution allows to study morphofunctional issues non-invasively in an unprecedented way. We therefore aimed to develop an approach that characterizes the moving structures in 4D (= three spatial dimensions+time). We designed a miniature standing wave tube-like setup to meet both the requirements of tomography and those of tank acoustics. With this new setup, we successfully visualized the motion of isolated otoliths and the auditory structures in zebrafish (Danio rerio) and the glass catfish (Kryptopterus vitreolus).

Hand Motion Analysis Illustrates Differences When Drilling Cadaveric and Printed Temporal Bone

Objective: Temporal bone simulation is now commonly used to augment cadaveric education. Assessment of these tools is ongoing, with haptic modeling illustrating dissimilar motion patterns compared to cadaveric opportunities. This has the potential to result in maladaptive skill development. It is hypothesized that trainee drill motion patterns during printed model dissection may likewise demonstrate dissimilar hand motion patterns. Methods: Resident surgeons dissected 3D-printed temporal bones generated from microCT data and cadaveric simulations. A magnetic position tracking system (TrakSTAR Ascension, Yarraville, Australia) captured drill position and orientation. Skill assessment included cortical mastoidectomy, thinning procedures (sigmoid sinus, dural plate, posterior canal wall) and facial recess development. Dissection was performed by 8 trainees (n = 5 < PGY3 > n = 3) using k-cos metrics to analyze drill strokes within position recordings. K-cos metrics define strokes by change in direction, providing metrics for stroke duration, curvature, and length. Results: T-tests between models showed no significant difference in drill stroke frequency (cadaveric = 1.36/s, printed = 1.50/s, P < .40) but demonstrate significantly shorter duration (cadaveric = 0.37 s, printed = 0.16 s, P < .01) and a higher percentage of curved strokes (cadaveric = 31, printed = 67, P < .01) employed in printed bone dissection. Junior staff used a higher number of short strokes (junior = 0.54, senior = 0.38, P < .01) and higher percentage of curved strokes (junior = 35%, senior = 21%, P < .01). Conclusions: Significant differences in hand motions were present between simulations, however the significance is unclear. This may indicate that printed bone is not best positioned to be the principal training schema.

Characterisation of Children's Head Motion for Magnetic Resonance Imaging With and Without General Anaesthesia

Head motion is one of the major reasons for artefacts in Magnetic Resonance Imaging (MRI), which is especially challenging for children who are often intimidated by the dimensions of the MR scanner. In order to optimise the MRI acquisition for children in the clinical setting, insights into children's motion patterns are essential. In this work, we analyse motion data from 61 paediatric patients. We compare structural MRI data of children imaged with and without general anaesthesia (GA), all scanned using the same hybrid PET/MR scanner. We analyse several metrics of motion based on the displacement relative to a reference, decompose the transformation matrix into translation and rotation, as well as investigate whether different regions in the brain are affected differently by the children's motion. Head motion for children without GA was significantly higher, with a median of the mean displacements of 2.19 ± 0.93 mm (median ± standard deviation) during 41.7±7.5 min scans; however, even anaesthetised children showed residual head motion (mean displacement of 1.12±0.35 mm). For both patient groups translation along the z-axis (along the scanner bore) was significantly larger in absolute terms (GA / no GA: 0.87±0.29/0.92 ± 0.49 mm) compared to the other directions. Considering directionality, both patient groups were moving in negative z-direction and thus, out of the scanner. The awake children additionally showed significantly more nodding rotation (0.33±0.20°). In future studies as well as in the clinical setting, these predominant types of motion need to be taken into consideration to limit artefacts and reduce re-scans due to poor image quality.

285 A rare case of atypical, non-triggered takotsubo recurrence

Aims Takotsubo syndrome (TTS) is an acute and reversible heart failure syndrome that, at presentation, mimics acute myocardial infarction. The most common echocardiographic manifestation is the so-called ‘apical ballooning’, but other much less common wall motion patterns have been described. The pathophysiology of the syndrome is not fully understood, but there is considerable evidence that sympathetic stimulation plays a central role. The prevalence of this syndrome is higher in post-menopausal women and in most cases, but not invariably, precipitated by an emotional or physical triggering event. A close relation between brain and circulatory system has been observed and for this reason psychiatric and neurologic disorders are often recognized as precipitating conditions. Although many risk factor persist after the acute manifestation, Takotsubo recurrences do represent an exception, especially in the absence of a clear precipitating event. Methods and results A 70-year-old woman was admitted for anginal pain associated with ischaemic electrocardiographic alterations and elevation of cardiac biomarkers. The coronary angiography with left ventriculogram and the echocardiographic findings were consistent with a diagnosis of mid-ventricular Takotsubo. Cardiac magnetic resonance confirmed the absence of an ischaemic pattern or evidence of infectious myocarditis. This case represents a recurrence of TTS, in fact two years earlier the patient was hospitalized to our division for stress cardiomyopathy with typical apical ballooning. Also in the present occasion, she had a favorable clinical course, with a complete recovery of the cardiac function at subsequent evaluations. The unicity of this case lies above all in the absence of a clear trigger event. Although, an altered mental status was present because the patient suffered from anxiety and depression on pharmacological treatment, with periods of exacerbation but not in occasion of the recurrence. Conclusions TTS is not a benign condition, with recurrence being possible even in the absence of precipitating events. Based on registry data, annual rate of Takotsubo recurrence is 1.5–1.8% and is estimated to reach 4% in life. A variable TTS pattern at recurrence is common in up to 20% of cases. Our paper reports a unique case of recurrent Takotsubo syndrome with variable patterns of ventricular involvement, with neither physical nor psychological trigger. Nevertheless, for what concerns our case, the psychiatric condition the patient suffered from, could have played a role of permanent status of sympathetic activation, that in the end elicitates the occurrence of the syndrome. A better understanding of the pathophysiology of the syndrome is needed to find evidence-based therapeutic strategies that could prevent recurrence.

Enabling Surveillance Cameras to Navigate

Smartphone localization is essential to a wide spectrum of applications in the era of mobile computing. The ubiquity of smartphone mobile cameras and surveillance ambient cameras holds promise for offering sub-meter accuracy localization services thanks to the maturity of computer vision techniques. In general, ambient-camera-based solutions are able to localize pedestrians in video frames at fine-grained, but the tracking performance under dynamic environments remains unreliable. On the contrary, mobile-camera-based solutions are capable of continuously tracking pedestrians; however, they usually involve constructing a large volume of image database, a labor-intensive overhead for practical deployment. We observe an opportunity of integrating these two most promising approaches to overcome above limitations and revisit the problem of smartphone localization with a fresh perspective. However, fusing mobile-camera-based and ambient-camera-based systems is non-trivial due to disparity of camera in terms of perspectives, parameters and incorrespondence of localization results. In this article, we propose iMAC, an integrated mobile cameras and ambient cameras based localization system that achieves sub-meter accuracy and enhanced robustness with zero-human start-up effort. The key innovation of iMAC is a well-designed fusing frame to eliminate disparity of cameras including a construction of projection map function to automatically calibrate ambient cameras, an instant crowd fingerprints model to describe user motion patterns, and a confidence-aware matching algorithm to associate results from two sub-systems. We fully implement iMAC on commodity smartphones and validate its performance in five different scenarios. The results show that iMAC achieves a remarkable localization accuracy of 0.68 m, outperforming the state-of-the-art systems by >75%.

SEARCHING 3D MOTION PATTERNS OF VIETNAMESE TRADITIONAL DANCES

Vietnam has many traditional dances suchas Xoan singing, “tuồng” or “chèo”. They all urgentlyneed to be preserved in digital formats, especially in3D motion capture format for dances. In digitalformats, they bring many values such as the ability toautomatically classify and search for content ofdances' movement. In this paper, we propose asystem for 3D movement search of Cheo dance 'spostures and gestures. The system applies slidingwindow technique, Dynamic Time Warpingalgorithm and a novel feature selection methodnamed CheoAngle. Results show that the proposedsystem reach good scores in several metrics. We alsocompare CheoAngle with other feature selectionmethods for 3D movement and show that CheoAnglegive the best results

Fundamentals and working mechanisms of artificial muscles with textile application in the loop

Natural muscles, that convert chemical energy derived from glucose into mechanical and thermal energy, are capable of performing complex movements. This natural muscle power was the only way to perform mechanical work in a targeted manner for millions of years. In the course of thousands of years of technical development, mankind has succeeded in harnessing various physical and chemical phenomena to drive specific mechanical processes. Wind and water power, steam and combustion engines or electric motors are just a few examples. However, in order to make the diversity and flexibility of natural motion patterns usable for machines, attempts have been made for many years to develop artificial muscles. These man-made smart materials are able to react to environmental conditions by significantly changing their shape or size. For the design of effective artificial muscles that closely resemble the natural original, the usage of textile technology offers great advantages. By means of weaving, individual actuators can be parallelized, which enables the transmission of greater forces. By knitting the maximum stretching performance can be enhanced by combining the intrinsic stretching capacity of the actuators with the structural-geometric stretching capacity of the fabric. Furthermore textile production techniques are well suited for the requirement-specific, individual placement of actuators in order to achieve the optimal geometry for the respective needs in every load case. Ongoing technical development has created fiber based and non-fibrous artificial muscles that are capable of mimicking and even out-performing their biological prodigy. Meanwhile, a large number of partly similar, but also very different functional principles and configurations were developed, each with its own specific characteristics. This paper provides an overview of the relevant and most promising technical approaches for realising artificial muscles, classifies them to specific material types and explains the mechanisms used as well as the possible textile applications.