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The development of the Drag-Free and Attitude Control System is crucial for space-based gravitational wave detectors. The Drag-Free and Attitude Control System includes for spacecraft attitude control, drag-free control, moving optical subassemblies pointing control, and test masses electrostatic control during multiple phases of the mission lifetime. An accurate model of the spacecraft dynamics model is not only a precondition for the control design of Drag-Free and Attitude Control System, but also can serve as a valuable reference to assess the noise budget of gravitational wave detectors. This paper presents a generic, nonlinear mathematical model that describes the multi-body dynamics for the gravitational wave detectors. The model fully considers the couplings between the bodies involved, with a particular focus on the impact of the moving optical subassemblies on the spacecraft attitude. Additionally, a corresponding reduced model for the control design of the science mode is divided. Both models are validated numerically by Monte Carlo simulations and motion analysis, respectively. • Introduce a spacecraft dynamics model that fully describes the motion coupling. • Simscape simulation has validated the accuracy of the dynamics model. • The spacecraft dynamics model is applicable to multiple phases of motion. • Monte Carlo simulations have validated the applicability to different parameters. [ABSTRACT FROM AUTHOR]

• fMRI bilateral motor control task was used to evaluate longitudinal changes in brain activity. • Neuromuscular training induced movement adaptations in MC and HxSRC groups. • MCs demonstrate increased cerebellar activity associated with improved frontal plane ROM. • HxSRCs demonstrate increased somatosensory activity associated with improved frontal plane ROM. Sports-related concussion (SRC) in adolescent athletes is associated with an increased risk of subsequent lower extremity injury. Neuromuscular training (NMT) has shown promise for reducing lower extremity injuries following SRC, however, neural adaptations in response to changes in lower extremity biomechanics following NMT in athletes with a history of SRC (HxSRC) remains poorly understood. Therefore, the purpose of this study was to identify changes in neural activity associated with lower extremity movement adaptations following a six-week NMT intervention in athletes with a HxSRC. Thirty-two right-hand/foot-dominant female adolescent athletes (16 with self-reported HxSRC, 16 age- and anthropometrically-matched controls) completed a bilateral leg press task with 3D motion analysis during functional magnetic resonance imaging (fMRI). Movement adaptations were defined as a change in frontal and sagittal plane range of motion (ROM) during the fMRI bilateral leg press task. Significant pre- to post-NMT reductions were observed in the non-dominant (left) mean frontal plane ROM. Whole-brain neural correlate analysis revealed that increased cerebellar activity was significantly associated with reduced mean left-knee frontal ROM for matched controls. Exploratory within group analyses identified neural correlates in the postcentral gyrus for the HxSRC group which was associated with reduced mean left-knee frontal plane ROM. These distinct longitudinal changes provide preliminary evidence of differential neural activity associated with NMT to support knee frontal plane control in athletes with and without a HxSRC. [ABSTRACT FROM AUTHOR]

The disturbance of the coal caving mechanism is the main method to solve the problem of coal falling into an arch during the top coal caving process, and the clearance in the caving mechanism is an important factor affecting its disturbance. To study the influence of clearance on the hydraulic supports, the dynamic analysis of hydraulic supports with two-level and three-level caving mechanisms is conducted considering the clearance. Based on Lagrange's equations of first kind, the mathematical model is constructed, and the equivalent spring stiffness of the oil cylinder is solved. The dynamic response of hydraulic support is studied by solving the mathematical model, and the relative position changes of the journal and bearing are compared. The research results prove that clearance has a better disturbance effect on the three-level caving mechanism. At the same time, the influence of clearance size and motion process on the motion error of the three-level caving mechanism is analyzed. Using the Kriging surrogate model and polynomial interpolation, the motion prediction model for the secondary tail beam with different clearance sizes is proposed, and the predicted values of the test samples are compared with the numerical solution values to prove the feasibility. [ABSTRACT FROM AUTHOR]

Over the past decades, tremendous technological advances have emerged in human motion analysis (HMA). How has technology for analysing human motion evolved over the past decades, and what clinical applications has it enabled? The literature on HMA has been extensively reviewed, focusing on three main approaches: Fully-Instrumented Gait Analysis (FGA), Wearable Sensor Analysis (WSA), and Deep-Learning Video Analysis (DVA), considering both technical and clinical aspects. FGA techniques relying on data collected using stereophotogrammetric systems, force plates, and electromyographic sensors have been dramatically improved providing highly accurate estimates of the biomechanics of motion. WSA techniques have been developed with the advances in data collection at home and in community settings. DVA techniques have emerged through artificial intelligence, which has marked the last decade. Some authors have considered WSA and DVA techniques as alternatives to "traditional" HMA techniques. They have suggested that WSA and DVA techniques are destined to replace FGA. We argue that FGA, WSA, and DVA complement each other and hence should be accounted as "synergistic" in the context of modern HMA and its clinical applications. We point out that DVA techniques are especially attractive as screening techniques, WSA methods enable data collection in the home and community for extensive periods of time, and FGA does maintain superior accuracy and should be the preferred technique when a complete and highly accurate biomechanical data is required. Accordingly, we envision that future clinical applications of HMA would favour screening patients using DVA in the outpatient setting. If deemed clinically appropriate, then WSA would be used to collect data in the home and community to derive relevant information. If accurate kinetic data is needed, then patients should be referred to specialized centres where an FGA system is available, together with medical imaging and thorough clinical assessments. • Gait analysis by stereophotogrammetry provides highly accurate biomechanics of motion. • Wearable sensors enable ecological data collection at home and in community setting. • Deep-learning video analysis can perform motion capture without instruments on subjects. • Several authors suggest more modern technologies shall replace traditional gait analysis. • We argue that these three technologies complement each other and shall be "synergistic". [ABSTRACT FROM AUTHOR]

Traditional 3D motion analysis typically considers the spine as a rigid entity. Nevertheless, previous single-joint models have proven inadequate in evaluating the movement across different spinal segments in patients with idiopathic scoliosis (IS). Scoliosis significantly impairs movement functions, especially during activities such as ascending and descending stairs. There is a lack of research on the patterns of stair movement specifically for patients with IS. This study aims to investigate trunk kinematics in college students with IS during stair ascent and descent tasks. A total of 56 participants, 28 with IS and 28 with healthy controls, were recruited for this case-control study. The trunk movements were analyzed using a motion analysis system that incorporated a multisegment spine model. Understanding the multi-segment spine kinematics during stair tasks can contribute to the development of effective rehabilitation programs for individuals with IS. Case-control study. Twenty-eight IS and 28 controls. Cobb angle, spinal curvature, spinal active range of motion (ROM), Kinematics. The Qualisys system (Gothenburg, Sweden) was utilized in this study with a sampling frequency of 150 Hz. It recorded the kinematics in the thoracic, lumbar, thoracic cage, and pelvis while ascending and descending stairs for both the 28 IS individuals and the 28 control participants. Additionally, clinical parameters such as the Cobb angle, curvature of the spine, spinal range of motion (ROM), and other relevant factors were concurrently assessed among the subjects. Project supported by the National Natural Science Foundation of China (Grant No. 82205306). The authors declare no conflict of interest in preparing this article. The findings of this study revealed that IS individuals exhibited reduced kyphotic curvature in the sagittal plane (p<.05) when compared to the control group. In contrast, these IS patients displayed greater coronal curvature (Cobb angle) in the frontal plane and a more substantial difference in thoracic side bending range of motion in comparison to the control group (p.05). Moreover, during the ascending stair activity, IS patients showed reduced thoracic cage flexion-extension range of motion (p<.05), while displaying increased lumbar rotation range of motion and anterior-posterior pelvic tilt range of motion (p<.05) in contrast to the control group. Notably, the kinematic analysis during the descent of stairs indicated that IS patients exhibited a larger range of motion in thoracic flexion-extension, thoracic side bending, thoracic cage side bending, thoracic rotation, and thoracic cage rotation when compared to the control group (p<.05). The results showed significant differences in trunk kinematics between the two groups during both stair ascent and descent tasks. The utilization of the "multisegment spine model" facilitates the acquisition of motion information across multiple segments of the spine in patients diagnosed with IS, effectively enhancing the assessment outcomes derived from imaging information. The three-dimensional structural deformity in the trunk affects both static and dynamic activity patterns. In different activity states, IS patients demonstrate stiff movements in certain segments while experiencing compensatory instability in others. In the future, clinical rehabilitation programs for IS should prioritize stair-related activity training. [ABSTRACT FROM AUTHOR]

Shoulder instability (SI) is a complex impairment, and identifying biomarkers that differentiate subgroups is challenging. Children and adolescents with SI (irrespective of etiology) have differences in their movement and muscle activity profiles compared to age- and sex-matched controls (2-tailed). There are limited fundamental movement and muscle activity data for identifying different mechanisms for SI in children and adolescents that can inform subgrouping and treatment allocation. Young people between 8 and 18 years were recruited into 2 groups of SI and age- and sex-matched controls (CG). All forms of SI were included, and young people with coexisting neurologic pathologies or deficits were excluded. Participants attended a single session and carried out 4 unweighted and 3 weighted tasks in which their movements and muscle activity was measured using 3-dimensional (3D) movement analysis and surface electromyography (sEMG). Statistical parametric mapping was used to identify between-group differences. Data were collected for 30 young people (15 SI [6 male, 9 female] and 15 CG [8 male, 7 female]). The mean (standard deviation) age of the participants was 13.6 years (3.0). The SI group demonstrated consistently more protracted and elevated sternoclavicular joint positions during all movements. Normalized muscle activity in latissimus dorsi was lower in the SI group and had the most statistically significant differences across all movements. Where differences were identified, the SI group also had increased normalized activity of their middle trapezius, posterior deltoid, and biceps muscles but decreased activity of their latissimus dorsi, triceps and anterior deltoid muscles compared with the CG group. No statistically significant differences were found for the pectoralis major across any movements. Weighted tasks produced fewer differences in muscle activity patterns compared with unweighted tasks. Young people with SI may adapt their movements to minimize glenohumeral joint instability. This was demonstrated by reduced variability in acromioclavicular and sternoclavicular joint angles, adoption of different movement strategies across the same joints, and increased activity of the scapular stabilizing muscles, despite achieving similar arm positions to the CG. Young people with SI demonstrated consistent differences in their muscle activity and movement patterns. Consistently observed differences at the shoulder girdle included increased sternoclavicular protraction and elevation accompanied by increased normalized activity of the posterior scapula–stabilizing muscles. Existing methods of measurement may be used to inform clinical decision making; however, further work is needed to evaluate the prognostic and clinical utility of derived 3D and sEMG data for informing decision making within SI. [ABSTRACT FROM AUTHOR]

To define the regular upper eyelid anatomy and their changes during dynamic motion using ultrasonographically depicted structures. A cross-sectional study. High-resolution ultrasound biomicroscopy (50MHz) was performed on 84 upper eyelids of 42 healthy volunteers without evidence of eyelid conditions. The skin-orbicularis oculi complex (SOOC), levator aponeurosis, and Müller's muscle-conjunctival complex were imaged. The thickness of these structures was measured in primary gaze and downgaze positions. SOOC and levator aponeurosis thickness was bigger with eyes open than with eyes closed (p < 0.01). With eyes closed, the thickness of SOOC on the pupillary midline and levator aponeurosis was positively correlated with age (p < 0.05, p < 0.01, respectively), and the thickness of levator aponeurosis and SOOC on the pupil midline was also positively correlated with BMI index (p < 0.05). Similarly, SOOC thickness on the medial and lateral canthus line is also positively correlated with BMI index and age (p < 0.05, p < 0.01, respectively). As for the differences between genders, the mean thickness of SOOC and levator aponeurosis was statistically different (p < 0.05, respectively). The magnitude of levator aponeurosis thickness in men varied more than in women in different ocular positions (p < 0.05). All measurements had an intramethod between 0.624 and 0.792, and inter-rater ICC and intrarater ICC between 0.748 and 0.850. Ultrasound biomicroscopy represents a noninvasive tool for the visualization of upper eyelid morphology. Expanding its application can help to understand the dynamics of upper eyelid physiological movement, aging, and disease research in different populations and evaluate surgical outcomes. [ABSTRACT FROM AUTHOR]

Stereotactic body radiation therapy (SBRT) and hypofractionation using pencil-beam scanning (PBS) proton therapy (PBSPT) is an attractive option for thoracic malignancies. Combining the advantages of target coverage conformity and critical organ sparing from both PBSPT and SBRT, this new delivery technique has great potential to improve the therapeutic ratio, particularly for tumors near critical organs. Safe and effective implementation of PBSPT SBRT/hypofractionation to treat thoracic malignancies is more challenging than the conventionally fractionated PBSPT because of concerns of amplified uncertainties at the larger dose per fraction. The NRG Oncology and Particle Therapy Cooperative Group Thoracic Subcommittee surveyed proton centers in the United States to identify practice patterns of thoracic PBSPT SBRT/hypofractionation. From these patterns, we present recommendations for future technical development of proton SBRT/hypofractionation for thoracic treatment. Among other points, the recommendations highlight the need for volumetric image guidance and multiple computed tomography–based robust optimization and robustness tools to minimize further the effect of uncertainties associated with respiratory motion. Advances in direct motion analysis techniques are urgently needed to supplement current motion management techniques. [ABSTRACT FROM AUTHOR]

[Display omitted] The typical mammalian neck consisting of seven cervical vertebrae (C1–C7) was established by the Late Permian in the cynodont forerunners of modern mammals. This structure is precisely adapted to facilitate movements of the head during feeding, locomotion, predator evasion, and social interactions. Eutheria, the clade including crown placentals, has a fossil record extending back more than 125 million years revealing significant morphological diversification in the Mesozoic. Yet very little is known concerning the early evolution of eutherian cervical morphology and its functional adaptations. A specimen of Zalambdalestes lechei from the Late Cretaceous of Mongolia boasts exceptional preservation of an almost complete series of cervical vertebrae (C2–C7) revealing a highly modified axis (C2). The significance of this cervical morphology is explored utilizing an integrated approach combining comparative anatomical examination across mammals, muscle reconstruction, geometric morphometrics and virtual range of motion analysis. We compared the shape of the axis in Zalambdalestes to a dataset of 88 mammalian species (monotremes, marsupials, and placentals) using three-dimensional landmark analysis. The results indicate that the unique axis morphology of Zalambdalestes has no close analog among living mammals. Virtual range of motion analysis of the neck strongly implies Zalambdalestes was capable of exerting very forceful head movements and had a high degree of ventral flexion for an animal its size. These findings reveal unexpected complexity in the early evolution of the eutherian cervical morphology and suggest a feeding behavior similar to insectivores specialized in vermivory and defensive behaviors in Zalambdalestes akin to modern spiniferous mammals. [ABSTRACT FROM AUTHOR]

The decline in cognitive function in older adults with mild cognitive impairment (MCI) may contribute to a change in movement pattern during sit-to-stand transitions (STS). However, when comparing older adults with MCI to older adults without MCI, there is a lack of evidence of kinematic and kinetic data during STS. Furthermore, while significant cognitive dual-task interference has been demonstrated in older adults with MCI, studies on the effects of dual motor tasks in MCI, particularly during STS, have not been reported. Are there any differences in the movement time, joint angles, and maximum joint moments while performing STS under single- and dual-task conditions in older adults with and without MCI? In a cross-sectional study, 70 participants were divided into two groups: older adults with MCI and without MCI. Motion analysis and a force plate system were used to collect and analyze the STS movement. All participants were asked to do the STS movement alone and the STS with a dual motor task with the self-selected pattern on an adjustable bench. Older adults with MCI had greater maximum trunk flexion during STS with a dual task than older adults without MCI and greater than STS alone. Furthermore, older adults with MCI had a greater ankle plantar flexion moment during STS with a dual task than during STS alone. Even though the STS task is one of the simplest functional activities, different strategies to achieve the STS action with dual tasks were found among older adults with and without MCI in terms of joint angle and joint moments. • The time used for STS showed no difference between older adults with and without MCI. • STS with dual tasks spent more time to complete than STS alone. • Older adults with MCI perform more trunk flexion during STS with dual tasks. • Older adults with MCI rely on the ankle plantar flexor during STS with dual tasks. [ABSTRACT FROM AUTHOR]

The functional goals of cervical disc arthroplasty (CDA) are to restore enough range of motion (ROM) to reduce the risk of accelerated adjacent segment degeneration but limit excessive motion to maintain a biomechanically stable index segment. This motion-range is termed the "Physiological mobility range." Clinical studies report postoperative ROM averaged over all study subjects but they do not report what proportion of reconstructed segments yield ROM in the Physiological mobility range following CDA surgery. To calculate the proportion of reconstructed segments that yield flexion-extension ROM (FE-ROM) in the Physiological mobility range (defined as 5°-16°) by analyzing the 24-month postoperative data reported by clinical trials of various cervical disc prostheses. Analysis of 24-month postoperative FE-ROM data from clinical trials. Data from 1,173 patients from single-level disc replacement clinical trials of 7 cervical disc prostheses. 24-month postoperative index-level FE-ROM. The FE-ROM histograms reported in Food and Drug Administration-Investigational Device Exemption (FDA-IDE) submissions and available for this analysis were used to calculate the frequencies of implanted levels with postoperative FE-ROM in the following motion-ranges: Hypomobile (0°–4°), Physiological (5°–16°), and Hypermobile (≥17°). The ROM histograms also allowed calculation of the average ROM of implanted segments in each of the 3 motion-ranges. Only 762 of 1,173 patients (implanted levels) yielded 24-month postCDA FE-ROM in the physiological mobility range (5°–16°). The proportions ranged from 60% to 79% across the 7 disc-prostheses, with an average of 65.0%±6.2%. Three-hundred and two (302) of 1,173 implanted levels yielded ROM in the 0°–4° range. The proportions ranged from 15% to 38% with an average of 25.7%±8.9%. One-hundred and nine (109) of 1,173 implanted levels yielded ROM of ≥17° with a range of 2%-21% and an average proportion of 9.3%±7.9%. The prosthesis with built-in stiffness due to its nucleus-annulus design yielded the highest proportion (103/131, 79%) of implanted segments in the physiological mobility range, compared to the cohort average of 65% (p<.01). Sixty-five of the 350 (18.6%) discs implanted with the 2 mobile-core designs in this cohort yielded ROM≥17° as compared to the cohort average of 9.3% (109/1,173) (p<.05). At 2-year postCDA, the "hypomobile" segments moved on average 2.4±1.2°, those in the "physiological-mobility" group moved 9.4±3.2°, and the hypermobile segments moved 19.6±2.6°. Prosthesis design significantly influenced the likelihood of achieving FE-ROM in the physiological mobility range, while avoiding hypomobility or hypermobility (p<.01). Postoperative ROM averaged over all study subjects provides incomplete information about the prosthesis performance - it does not tell us how many implanted segments achieve physiological mobility and how many end up with hypomobility or hypermobility. We conclude that the proportion of index levels achieving postCDA motions in the physiological mobility range (5°–16°) is a more useful outcome measure for future clinical trials. [ABSTRACT FROM AUTHOR]

In den letzten Jahren hat die digitale Revolution auch die Prävention und Rehabilitation von Sportverletzungen rasant erfasst. Für die Prävention spielt die Digitalisierung bereits durch die Integration verschiedener Technologien und Ansätze eine wichtige Rolle. Dazu gehören Wearables, Sensoren und Tracking-Plattformen, virtuelles Training und Simulation sowie Big Data und künstliche Intelligenz (KI). Die Digitalisierung ermöglicht mit diesen Methoden einen ganzheitlichen Ansatz zur Verletzungsprävention im Sport, indem Echtzeitdaten, Analysetools und innovative Technologien genutzt werden, um potenzielle Risiken zu erkennen und um umgehend präventive Maßnahmen zu ergreifen. Auch in der Rehabilitation von Sportverletzungen spielt die Digitalisierung heute eine große Rolle. Mobile Anwendungen, in die KI, Sensoren oder virtuelle Realität integriert werden können, werden in der sportmedizinischen Rehabilitation bereits klinisch eingesetzt. Diese Apps können den Rehabilitationsprozess unterstützen, indem sie Übungsprogramme vorschlagen, Feedback über Sensoren geben und den Rehabilitationsprozess mithilfe von KI an die aktuellen Fähigkeiten des Patienten anpassen. Zusammenfassend lässt sich sagen, dass die Digitalisierung zweifellos das Potenzial hat, unser bisheriges Verständnis von Prävention und Rehabilitation zu revolutionieren. Um die Risiken dieser neuen Technologien einschätzen zu können, sind jedoch weitere Forschungsarbeiten erforderlich. In recent years, the digital revolution has rapidly affected the prevention and rehabilitation of sports injuries. For prevention, digitalization plays an important role by integrating various technologies and approaches. These include wearables, sensors and tracking platforms for monitoring, motion capture for biomechanical analysis, virtual training and simulation, and big data and artificial intelligence (AI) for identifying patterns and relationships that indicate risk of injury. Digitalization therefore enables a holistic approach to injury prevention in sport by using real-time data, analysis tools and innovative technologies to identify potential risks and take appropriate measures. Digitalization also plays a major role in the rehabilitation of sports injuries today. Mobile applications in which AI, sensors or virtual reality can be integrated are already used clinically in sports medicine rehabilitation. These apps can support the rehabilitation process by suggesting exercise programs, providing feedback via sensors and using AI to adapt the rehabilitation process to the patient's current abilities. In summary, digitalization undoubtedly has the potential to revolutionize the way we have previously understood prevention and rehabilitation. However, further research is necessary to be able to assess the risks of these new technologies. [ABSTRACT FROM AUTHOR]

Walking is the most affected motor function in children with cerebral palsy (CP). Orthopaedic surgery is regularly used to improve ambulation in children with CP. Selective Percutaneous Myofascial Lengthening (SPML) is considered the state-of-the art technique for surgical lengthening of spastic/contracted muscles in CP. The purpose of this study was to investigate the effect of combined SPML surgery and postoperative functional physiotherapy on gait function and characteristics of children with spastic cerebral palsy (CP). Twenty-six children with spastic CP, aged 5–7 years, Gross Motor Function Classification System (GMFCS) levels II (n = 6), III (n = 12) and IV (n = 8) participated in a quasi-experimental one-group pretest-posttest study with a 9-month follow-up. The Global Motion Graph Deviation Index (MGDI) (including MGDI sub-indices of each joint in each plane of motion) and spatiotemporal parameters of a three-dimensional kinematic gait analysis were used to assess the gait function and characteristics, respectively. Nine months following SPML and functional physiotherapy, statistically significant improvements (p < 0.05) were noted in the Global MGDI, the MGDIs of sagittal plane knee and ankle motion analysis graphs, and the four most common spatiotemporal measures of gait: walking velocity, stride length, step length, and cadence. Children with spastic CP seem to gain better overall gait function following SPML procedure and functional physiotherapy, by achieving higher walking velocity, longer stride length and step length, and faster cadence. Further studies with control group and longer follow-up three-dimensional gait analyses are warranted to validate these positive results. [ABSTRACT FROM AUTHOR]

Due to the challenges of separation and high costs, coal slime is often directly burned without further separation processing, leading to environmental pollution. Therefore, a feed-regulated water-only cyclone has been proposed to improve the coal slime separation efficiency by controlling the suspended bed. This method optimizes particle characteristics by incorporating a pre-desliming hydrocyclone, the characteristics of particles were optimized to regulate the hindered settling in suspension layer. Response surface experiments were conducted to investigate the impact of structural parameters on separation efficiency, Additionally, under optimal parameter conditions, particle size and density were characterized, and a simulation analysis was conducted using CFD–EDEM. The results showed that the maximum separation efficiency achieved in the experiment was 35.31%. Particle characterization analysis also revealed that, after feed regulation, the proportion of particles with a size of 0.045 mm within high density exceeded 75%. Industrial application experiments demonstrated the feasibility of obtaining a high-quality coal product with over screen yield of 9.29% and an ash content of 9.47%. This transformation of coal slurry into a valuable resource has generated significant economic benefits for enterprises and will address the environmental pollution issue caused by direct combustion and improper disposal. [Display omitted] • A feed-regulated water-only cyclone was proposed. • The active mechanism to regulate the hindered settling was studied. • The maximum separation efficiency achieved in the experiment is 35.31%. • The medium on particle motion analysis was simulated by CFD–EDEM. [ABSTRACT FROM AUTHOR]

We searched to quantify the influence of sagittal vertical axis (SVA) on the improvement of spatiotemporal gait parameters using a gait motion analysis (GMA) before and after decompression surgery in patients suffering from lumbar spinal stenosis (LSS). Thirty-nine patients with severe LisSS planned for lumbar decompression underwent a full-body biplanar radiographs (EOS) to quantify the SVA and have benefited from a 3-dimensional GMA 1 month before surgery (M0) and 6 month (M6) after surgery. The first step of this study was to confirm the validation of 3-dimensional sagittal vertical axis (3D SVA) for posture analysis. An analysis of modification of the 3D SVA and spatiotemporal gait parameters was then carried out in order to identify any correlation. Decompression surgery did not significantly improve 3D SVA between M0 and M6 (respectively 49.1 [50.3] vs. 49.84 [19.02], P = 0.42). Concerning spatiotemporal parameters, we found significant difference for all parameters between M0 and M6. A strong correlation (R2 > 0.65) between static SVA (EOS) and 3D SVA was demonstrated using a statistical regression equation. There was also a statistically significant correlation between SVA (static and 3-dimension) and improvement in spatiotemporal gait parameters after decompression surgery. This study analyses the relationship between postural change (SVA) and improvement in gait parameters measured during GMA before and after decompression surgery for LSS. This specific analysis of gait parameters may represent a prognostic assessment tool for the recovery of patients undergoing surgery for a LSS. [ABSTRACT FROM AUTHOR]

To verify the possibility of space debris removal by an ion beam, the problem of mission analysis for the motion of virtual configuration comprising a service spacecraft and space debris was solved. It is shown that using the state-of-the-art technologies it is possible to develop a service spacecraft equipped with a system for contactless removal of space debris based on a high-frequency ion source and a compensating electric propulsion system comprising a pair of stationary plasma thrusters. Such a system could provide removal of up to ten space debris from the protected area of the geostationary orbit to disposal orbits. • Space debris removal from the near-Earth space by a contactless technique is considered. • Mission analysis for a virtual configuration "service spacecraft - space debris objects" was carried out on the basis of the developed model. • Efficiency of the system for space debris removal from the geostationary orbit to ensure the space flight safety is shown. [ABSTRACT FROM AUTHOR]

Plantar fascia tension is considered to cause plantar fasciitis, and medial longitudinal arch decrease is believed to be a risk factor for plantar fasciitis. Arch height index (AHI) and arch height flexibility (AHF) are useful indicators for evaluating medial longitudinal arch. However, the relationship between plantar fascia tension during running and these indicators remain unclear. Are the foot characteristics in AHI and AHF that represent medial longitudinal arch related to plantar fascia tension during running? Twenty-two male participants enrolled in this study. Foot characteristics required for calculating AHI and AHF were measured using the AHI measurement system. AHI was defined as the height from the floor to the dorsum of the foot divided by the truncated foot length with 10% or 50% load. AHF was defined as the change in arch height from the 10% and 50% loads. Marker trajectories of the foot and force plate data during running were measured using a three-dimensional motion analysis system and a force plate. Based on the measured data, the peak values of the plantar fascia tension were analyzed. Pearson's correlation was used to determine the relationship between foot characteristics and plantar fascia tension. No significant correlation was found between AHI in the 10% load condition and plantar fascia tension (r = −0.36, p = 0.09) or between AHI in the 50% load condition and plantar fascia tension (r = −0.148, p = 0.515). In contrast, a significant moderate positive correlation was observed between AHF and plantar fascia tension (r = 0.568, p < 0.01). AHF is a change in arch height between sitting and standing positions, can be easily used to evaluate plantar fascia tension in clinical settings. This study implies that evaluating AHF is a useful tool in considering plantar fascia tension during running. • No correlation exists between arch height index and plantar fascia tension. • Arch height flexibility (AHF) is significantly related to plantar fascia tension. • Individuals with high AHF have increased plantar fascia tension during running. [ABSTRACT FROM AUTHOR]

The effect of Deep Brain Stimulation (DBS) on gait in Parkinson's Disease (PD) is poorly understood. Kinematic studies utilizing quantitative gait outcomes such as speed, cadence, and stride length have shown mixed results and were done mostly before and after acute DBS discontinuation. To examine longitudinal changes in kinematic gait outcomes before and after DBS surgery. We retrospectively assessed changes in quantitative gait outcomes via motion capture in 22 PD patients before and after subthalamic (STN) or globus pallidus internus (GPi) DBS, in on medication state. Associations between gait outcomes and clinical variables were also assessed. Gait speed reduced from 110.7 ± 21.3 cm/s before surgery to 93.6 ± 24.9 after surgery (7.7 ± 2.9 months post-surgery, duration between assessments was 15.0 ± 3.8 months). Cadence, step length, stride length, and single support time reduced, while total support time, and initial double support time increased. Despite this, there was overall improvement in the Movement Disorder Society-Unified Parkinson Disease Rating Scale-Part III score "on medication/on stimulation" score (from 19.8 ± 10.7–13.9 ± 8.6). Change of gait speed was not related to changes in levodopa dosage, disease duration, unilateral vs bilateral stimulation, or target nucleus. Quantitative gait outcomes in on medication state worsened after chronic DBS therapy despite improvement in other clinical outcomes. Whether these changes reflect the effects of DBS as opposed to ongoing disease progression is unknown. ● Kinematic gait parameters in Parkinson's disease change after deep brain stimulation. ● Gait velocity decreases despite improvement in motor function. ● Gait velocity change did not correlate with levodopa dose reduction. [ABSTRACT FROM AUTHOR]

In recent decades, high-tech prostheses, including microprocessor-controlled knee (MPK), have been developed to improve the functional abilities of lower limb amputees and to reduce gait asymmetry for the prevention of early joint degradation of the intact limb. The aim of this study was to determine the differences in joint moment and power of the intact limb of transfemoral amputees (TFAs) with an MPK compared to healthy individuals in 2 walking speed conditions. Twenty-one TFAs with MPK and matched 21 healthy individuals performed a walking task at spontaneous and rapid self-selected speeds. Spatiotemporal gait parameters and intact limb kinetic data were recorded. The hip and knee moments in the frontal plane during rapid walking were not significantly higher than spontaneous walking in TFA group (respectively p = 0.08 and p = 0.48) and were lower than the control group. In the sagittal plane, the hip extensor moment in TFA was higher than the control group in the landing phase (p < 0.001 in both speed conditions). The kinetics of the intact limb of active TFAs with an MPK showed a significant reduction at the knee internal abductor moment compared to the control, potentially limiting risk factors for knee osteoarthritis. However, in the sagittal plane, higher hip extensor moments could favor low-back pain appearance. Gait analysis of lower limb amputees should thus be performed to highlight these kinetic adaptations and then help to propose the most relevant rehabilitation and prevention exercises to limit the appearance of early musculoskeletal degeneration. • Lower limb kinetics analysis during gait at different speeds in TFA and control. • TFA intact leg kinetics were different from control despite high-tech prostheses. • TFA with MPK reduced hip and knee stress in frontal plane compared to control. • TFA with MPK did not increase frontal hip and knee moments in rapid walking. • TFA with MPK showed higher hip extensor moment than control. [ABSTRACT FROM AUTHOR]

The drop vertical jump (DVJ) is commonly used in return-to-play evaluations to assess movement quality and risk during a dynamic task. However, across biomechanics literature, a multitude of DVJ variations have been used, influencing the generalizability and potential interpretation of the reported findings. The purpose of this study was to identify differences in lower extremity kinematics and kinetics between DVJ variations that differ based on horizontal jump distance, verbal instructions, and the use of a jump target. A single-group repeated measures design was used in a laboratory setting. Twenty participants were tested, and three-dimensional angles and moments of the pelvis, hip, knee, and ankle were computed. Wilcoxon signed rank tests were performed to determine differences between DVJ variations. Reduced knee flexion at initial contact and greater knee extensor moments across the descent phase were observed with increased horizontal jump distance. Additionally, both verbal instructions and a jump target influenced movement strategies at the pelvis, hip, and knee. Ground reaction forces were found to be similar across conditions and jump height following the first landing increased with a target. Although subtle, the biomechanical differences observed between task variations emphasize the importance of standardizing motion analysis protocols for research and clinical decision-making. Given the findings of the current study, the authors recommend using the Half Height variation in patients treated for a knee injury as it will likely be the most indicative of movement quality. • Greater horizontal jump distance led to reduced knee flexion at initial contact. • Greater knee extensor moments across descent were found with further jump distance. • Verbal instructions and a jump target altered pelvis, hip, and knee mechanics. • Jump height following the first landing increased with the use of a jump target. • Motion analysis protocols for clinical / research assessments must be standardized. [ABSTRACT FROM AUTHOR]

Spine stereotactic body radiation therapy (SBRT) requires high positioning accuracy and a stable patient to maximize target coverage and reduce excessive irradiation to organs at risk. Positional verification during spine SBRT delivery helps to ensure accurate positioning for all patients. We report our experience with noninvasive 3-dimensional target position monitoring during volumetric modulated arc therapy of spine metastases in nonimmobilized patients positioned using only a thin mattress and simple arm and knee supports. Fluoroscopic planar kV images were acquired at 7 frames/s using the on-board imaging system during volumetric modulated arc therapy spine SBRT. Template matching and triangulation were used to track the target in vertical, longitudinal, and lateral directions. If the tracking trace deviated >1 mm from the planned position in ≥1 direction, treatment was manually interrupted and 6-dimensional cone beam computed tomography (CBCT)–based couch correction was performed. Tracking data were used to retrospectively analyze the target position. Positional data, agreement with CBCT, correlation between position of the couch and direction of any positional correction, and treatment times were analyzed. In total, 175 fractions were analyzed. Delivery was interrupted 83 times in 66 fractions for a deviation >1 mm. In 97% of cases the difference between tracking data and subsequent clinical shift performed after the CBCT match was ≤0.5 mm. Lateral/longitudinal shift performed after intervention correlated with the couch roll/pitch at the start of treatment (correlation coefficient, –0.63/0.53). Mean (SD; range) time between start of first imaging and end of the last arc was 15.2 minutes (5.1; 7.6-36.3). Spine tracking during irradiation can be used to prompt an intervention CBCT scan and repositioning so that a spine SBRT target deviates by ≤1 mm from the planned position, even in nonimmobilized patients. kV tracking and CBCT are in good agreement. The data support verification CBCT after all 6 degrees-of-freedom positional corrections in nonimmobilized spine SBRT patients. [ABSTRACT FROM AUTHOR]

Individuals with highly pronated feet (PF) are more prone to lower extremity injuries than those with mildly PF. However, whether foot kinematics and ground reaction force (GRF) characteristics differ according to the severity of PF deformity is unclear. Are there differences in foot kinematics and GRF characteristics during walking between individuals with mildly PF and those with highly PF? Ten individuals with mildly PF and 10 with highly PF (six-item foot posture index scores: 6–9 and 10–12 points, respectively) participated in this study. A three-dimensional motion analysis system measured participants' foot kinematics and GRF characteristics during gait trials. Participants with highly PF exhibited significantly lower medial longitudinal arch heights than those with mildly PF from 0 % to 90 % of the stance phase (p < 0.05). No significant differences were observed in any of the angles between the foot segments. Additionally, participants with highly PF exhibited significantly larger posterior GRF than those with mildly PF from 2 % to 7 % of the stance phase (p < 0.05). Participants with highly PF also exhibited significantly larger anterior GRF than those with mildly PF, from 62 % to 82 % of the stance phase (p < 0.05). The results of this study suggest that the more severe the PF deformity, the more inefficient the foot ground force transmission, and the stronger the load applied to the foot. These results may be related to the higher incidence of lower extremity injuries in individuals with highly PF than in those with mildly PF. • Highly pronated feet (PF) are more prone to lower extremity injury than mildly PF. • We examined foot kinematics and ground reaction force characteristics when walking. • Highly PF showed lower medial longitudinal arch heights than mildly PF. • Highly PF exhibited a larger anteroposterior ground reaction force than mildly PF. • A stronger impact may be related to the higher injury incidence with highly PF. [ABSTRACT FROM AUTHOR]

Motion analysis can be used to evaluate functional recovery after anterior cruciate ligament (ACL) reconstruction; however, the biomechanics parameters of the lower limb that are specifically altered in ACL-reconstructed knees compared to the contralateral side are not well understood. This retrospective study aimed to compare side-to-side differences in lower limb biomechanics during the first 100 milliseconds (ms) after initial contact in a single-leg forward landing task. Using three-dimensional motion analysis, lower joint kinematic and kinetic variables were measured 8–10 months postoperatively in 22 patients who had undergone ACL reconstruction. We determined side-to-side differences in lower limb biomechanics over the 100-ms timeframe after landing, and receiver operating characteristic (ROC) curve analyses were performed to calculate the area under the curve (AUC) for parameters showing significant side-to-side differences. During the 100-ms timeframe after landing, 58 kinematic and kinetic items showed significant side-to-side differences. Side-to-side differences in lower limb biomechanics over the 40-ms timeframe after landing existed. The ROC curve analysis identified 11 items with AUC values ≥ 0.70, including hip flexion, abduction moment, and knee joint power, and their AUC values were not significantly different. Hip flexion/abduction moment and knee power after GRF max could be used as outcomes for assessing functional recovery in patients who have undergone ACL reconstruction. [ABSTRACT FROM AUTHOR]

• Dynamic modeling of an underwater glider considering the effect of the loss of one wing. • The influence of key control parameter on the motion performance of underwater glider with the loss of one wing is given. • Three kinds of fault diagnosis methods are proposed for the wing loss of underwater glider. • The effectiveness of the proposed fault diagnosis methods is verified based on the real sea trial data. Underwater glider is one of the most promising ocean observation platforms and plays an important role in ocean observation and exploration because of its low energy consumption, long endurance and low cost. However, due to the complex and unpredictable ocean environment, many wing loss accidents of underwater gliders have been reported in recent years, which could not only lead to the uncontrollability of mission trajectory, but also cause the interruption of observation research. Therefore, this study explores the fault diagnosis of underwater gliders with the loss of one wing through dynamic modeling and motion analysis. First, a dynamic model of the Petrel underwater glider with the loss of one wing is established by considering the kinematic and dynamic theory, which is fundamentally different from the healthy prototypes. Then, the motion analysis of underwater gliders with the loss of one wing during the diving and climbing phases is performed using the proposed dynamic model, and the control strategy and parameter adjustment method are proposed for maintaining the target heading. Finally, three fault diagnosis methods of underwater gliders with the loss of one wing are proposed to timely and accurately detect the wing loss, which are verified by the massive sea trial data. Furthermore, the dynamic modeling, control strategy and fault diagnosis methods are also applicable to other underwater gliders. [ABSTRACT FROM AUTHOR]

Adolescent idiopathic scoliosis (AIS) is the most prevalent spinal deformity in adolescents. However, pathophysiology and long-term complications remain unclear. Characteristics of the mechanical work in AIS gait have not been well-studied. This study aimed to elucidate the characteristics of mechanical work in AIS gait. Observational comparison study. Participants were composed of two groups: scoliosis group with 68 participants and a control group with 17 participants. Spinal deformity and coronal spinal balance in the scoliosis group were assessed with Cobb angle, coronal balance, and apical vertebra translation. Three-dimensional motion analysis during walking was conducted to calculate lower limb joint works and external work on the whole body's center of mass. Lower limb joint work (JW) and external work on the whole body center of mass (CoM) were compared between the 2 groups with an independent t-test. Inter-limb and intra-limb comparisons of mechanical work were conducted with a paired t-test. The relationships between mechanical work and frontal trunk deformity were investigated in the scoliosis group. Walking speed and external work on whole body CoM did not differ between the two groups. Compared to the control group, the scoliosis group showed significantly larger JW on the convex and concave sides. The scoliosis group showed increased lower limb joint burden and limited trunk function for mechanical work during walking. Investigation of mechanical work during walking provides insight into the biomechanical characteristics of AIS. Therefore, future studies should be conducted to verify mechanical work characteristics which have relevance to the progression of spinal deformity and the development of lower limb complications in AIS. [ABSTRACT FROM AUTHOR]

Motion error and wear growth are two crucial factors that determine the performance of the manipulator system. The two factors are distinct from the sensitivity to time and respectively indicate its control performance and lifespan level. In this paper, a double-time-scale non-probabilistic reliability (DTSNPR)-based optimization method, which considers time-sensitive factor motion error as time-dependent reliability (TDR) and time-insensitive factor clearance wear growth as time-independent reliability (TIR), is proposed to comprehensively evaluate and optimize the controller of the manipulator system in consideration of these multi-scale factors. Meanwhile, for a highly nonlinear response problem of a manipulator system, the adaptive subinterval collocation method (ASICM) which transfers the highly nonlinear uncertainty propagation problem into a sequence of small subintervals, is adopted to obtain the response range more precisely. The proposed DTSNPR-based optimization method is applied to three numerical manipulator systems and ensures each of them under a predefined level of reliability upon both motion error and wear growth. The results also indicate that the proposed ASICM owns an advantage over computational cost and precision, with only 0.4% error and 1% computational cost compared with the Monte-Carlo methods. • Double-time-scale reliability analysis on motion error and clearance wear growth respectively as time-dependent reliability and time-independent reliability. • Analysis of the effect of the non-uniform clearance and growth of wear. • Calculation of system range in a more accurate manner by adaptive subinterval collocation method. [ABSTRACT FROM AUTHOR]

Clinical motion analysis involves quantitative measurement of gait patterns to identify gait anomalies that currently or have the potential to impact function, activities of daily living and participation. Clinical motion analysis services are equipped with motion capture technology and comprise specialised staff who deliver 3-dimensional motion analysis services to children and adults who present with varying levels of gait impairment. Data is then used to inform intervention recommendations to clinicians with a view to maintaining independent, functional and pain free walking (or appropriate mobility). The ANZ-CMAG (established in 2013) identified a need to establish recommendations to assist in standardising practice guidelines for both current and new clinical motion analysis services within the region. The group serves to promote collaboration between services in quality assurance processes, clinical practices, data sets and research activities. The clinical practice recommendations described in this paper cover: i) requirements for a motion analysis service (including staffing, facilities and equipment), ii) patient assessments (requirements, clinical information and data gathered, reporting and interpretation of patient data), iii) quality assurance processes (including motion capture system / biomechanical models & limitations, marker placement, data storage / record keeping, creation of normative dataset); iv) helpful resources. Better outcomes for children and adults with gait deviations is dependent upon accurate measurement and evaluation of walking and requires input from multidisciplinary clinical teams with specialist knowledge and skills. The ANZ-CMAG hopes these clinical practice recommendations are beneficial to motion analysis services with an aim to improve clinical practices, patient outcomes, and support research collaboration. [ABSTRACT FROM AUTHOR]

A functional biomechanics garment (FBG) may help to prevent injury by improved kinematics during motion such as single leg drop landing (SLDL). The purpose of this study was to investigate the effects of the FBG on the biomechanics of SLDL. Seventeen female university basketball players participated. Characteristics of the FBG were designed based on biomechanics during weight-loaded performance of human movement. The average values of lower limb kinematics and kinetics in the sagittal and frontal planes from 3 SLDL with and without FBG were measured and compared. The maximum varus angle of the knee showed a significant difference between the use of FBG (15.3 ± 15.1°) and without the use of FBG (5.9 ± 15.4°), the flexion angular displacement of the hip (with FBG, 21.5 ± 8.1°; without FBG, 24.0 ± 6.7°) between with and without FBG. The moment of the hip with FGB (1.1 ± 0.6 Nm) was significantly smaller than without FGB (1.4 ± 0.8 Nm). Regarding function of the FBG, the rigid part of the hip could counter the excessive adduction and flexion of the hip, and the elastic part of the thigh could support the varus moment when the elastic part stretched. Therefore, the subjects with FBG could control the frontal motion of the knee, which has a risk of knee injury, such as the dynamic valgus of the knee during the SLDL. Use of the FBG decreases dynamic knee valgus, which reduces risk of knee injury. • The functional garment may improve sports performance, increase muscular endurance, and enhance recovery. • We have produced a functional biomechanics garment (FBG) based on the biomechanics of braking and inducing joint motion during athletic performance. • We found that the FBG could decrease dynamic knee valgus and adductor moment of the hip. • Our functional garment can decrease dynamic knee valgus during the single leg drop landing, which may prevent knee injuries, such as ACL injury, which is related to dynamic knee valgus. [ABSTRACT FROM AUTHOR]

• New perturbed relative motion equations are derived. • Periodic orbits of deputy satellite are obtained numerically. • One, two, and three loops periodic orbits are analyzed. • The velocity and position of deputy satellite are also analyzed. • Single variable regression model developed to find the true anomaly initial value. This paper presents a novel dynamical system for the perturbed relative motion of deputy satellite. The governing equations are derived in the LVLH frame under the second zonal harmonic coefficient effect of the Earth on both chief and deputy satellites. An extended numerical analysis on the deputy satellite motion is performed, where the initial state vector of deputy satellite and eccentricity of chief satellite are used as initial conditions for finding its own periodic orbits. The interior loops of periodic orbits are obtained using numerical integrator RKEOM. Such orbits are analysed for different parameters and their stability are also discussed, where these orbits have considerable importance in the resonance analysis of motion The second zonal harmonic coefficient effect on the periodicity, initial position, initial true anomaly is studied, alongside exploring these orbits with one, two and three loops. Furthermore, a single variable nonlinear regression model is developed to predict initial true anomaly using eccentricity of chief satellite's orbit. [ABSTRACT FROM AUTHOR]

The paper describes a spreadsheet-based analysis of the motion of a climber ascending an Earth space elevator tether. The tether is represented by elements of varying lengths, each of mean cross-sectional area based on a taper ratio equation from earlier studies. The tether tension force is calculated in each element based on gravity and centrifugal forces plus the tension force in the element below. A climber is defined by mass, drive power and maximum speed: no consideration is given to design details, the analysis assumes a tractive force simply defined by the traction power. These details derive the mean climber speed on each tether segment and hence the time to ascend each segment. Spreadsheet logic then allocates multiple climber masses on elements at variable travel time spacings, for example 24 h spacings for climbers despatched from the Earth Port once per day. The effective weight of each climber yields an additional tether tension force, giving the total tension in the tether at any altitude. Spreadsheet enhancements include an algorithm for daylight duration at varying altitudes, variable with the time of year: this permits an option for climber spacing to be calculated for solar-powered climbing. The impact of input parameters (climber mass, power and maximum speed, departure intervals, continuous or daylight-only climbing, etc.) yield outputs such as maximum tether tension and climb time. The value of this technique becomes apparent when inputs are adjusted to yield similar tether tensions, representing a scenario with a maximum tether stress limit. It is possible to find, for example, how the maximum climber gross mass varies with maximum speed or drive power. Examples of findings include (1) the benefits of higher power and maximum speed are complex, and highly dependent on the climber power/weight ratio (2) 24-h climbing might allow 20% more payload (for any given tether strength and climber design) compared with daylight-only climbing (3) two smaller climbers launched daily might enable 15% more payload to be raised compared with a single daily launch. Such deeper understanding of climber dynamics highlights the complexity of climber design optimisation: key parameters are the net climber power/mass ratio and the maximum climber speed. • Method described to maximise payload • Smaller climbers with 24-hr power are best [ABSTRACT FROM AUTHOR]

Unilateral lower limb amputees have asymmetrical gaits, particularly on irregular surfaces and slopes. It is unclear how coordination between arms and legs can adapt during cross-slope walking. How do transfemoral amputees (TFAs) adapt their upper-lower limb coordination on cross-slope surfaces? Twenty TFA and 20 healthy adults (Ctrl) performed a three-dimensional gait analysis in 2 walking conditions: level ground and cross-slope with prosthesis uphill. Sagittal joint angles and velocities of hips and shoulders were calculated. Continuous relative phases (CRP) were computed between the shoulder and the hip of the opposite side. The closer to 0 the CRP is, the more coordinated the joints are. Curve analysis were conducted using SPM. The mean CRP between the downhill shoulder and the uphill hip was higher in TFA compared to Ctrl (p = 0.02), with a walking conditions effect (p = 0.005). TFA showed significant differences about the end of the stance phase (p = 0.01) between level ground and cross-slope, while Ctrl showed a significant difference (p = 0.008) between these walking conditions at the end of the swing phase. In CRP between the uphill shoulder and the downhill hip, SnPM analysis showed intergroup differences during the stance phase (p < 0.05), but not in the comparison between walking conditions in TFA and Ctrl groups. TFA showed an asymmetrical coordination in level ground walking compared to Ctrl. Walking on cross-slope led to upper-lower limb coordination adaptations: this condition impacted the CRP between downhill shoulder and uphill hip in both groups. The management of the prosthetic limb, positioned uphill, induced a reorganization of the coordination with the upper limb of the amputated side. Identifying upper-lower limb coordination adaptations on cross-slope surfaces will help to achieve rehabilitation goals for effective walking in urban environments. • TFA have asymmetrical coordination during level ground walking. • Walking on cross-slope induces coordination adaptations in healthy individuals. • TFA show coordination changes, especially during the end of prosthetic stance phase. • Quantifying coordination would help to meet rehabilitation goals for urban walking. [ABSTRACT FROM AUTHOR]

Excessive knee flexion during stance in children with cerebral palsy is often treated by surgical hamstrings lengthening. Pre-operative hamstrings muscle-tendon length can be estimated from kinematics and often used for decision making to rule out surgical lengthening if peak hamstrings muscle-tendon length is 'Not Short'. If peak hamstrings muscle-tendon length is within two standard deviations of typical, is that a sufficient indicator to rule out surgical hamstrings lengthening? Three motion analysis centers retrospectively identified children with cerebral palsy, age 6–17 years, who had consecutive gait analyses with knee flexion at initial contact > 20° and popliteal angle > 35° at initial study. Three groups were considered: Medial Hamstrings Lengthening (MHL), Medial and Lateral Hamstrings Lengthening (MLHL), no surgical intervention (Control). Peak hamstrings muscle-tendon length at initial gait study was computed and categorized as 'Short' or 'Not Short'. Two outcomes variables were considered: change in peak knee extension (PKE) and change in pelvic tilt. Univariate comparisons of all variables were assessed along with a multivariate stepwise regression analysis to identify pre-operative characteristics that may predict post-operative improvement. 440 individuals met inclusion criteria. Percentage of individuals with improved PKE by grouping were- MHL-'Short': 60%, MHL-'Not Short': 65%, MLHL-'Short': 74%, MLHL-'Not Short': 74%, Control 'Short': 20%, Control 'Not Short': 19%. Percentage of individuals with worsened pelvic tilt were- MHL-'Short': 25%, MHL-'Not Short': 11%, MLHL-'Short': 42%, MLHL-'Not Short': 21% with significantly more individuals in MHL-'Short' subgroup compared to MHL-'Not Short'. Multivariate analysis suggested that pre-operative pelvic tilt and weak hip extensor strength have the largest effect on predicting post-operative increase in APT. Peak muscle-tendon length was not a significant predictor of post-operative knee kinematics or increase in APT. This study suggests that hamstrings muscle-tendon length criteria by itself is not a sufficient indicator to recommend against hamstrings lengthening. • Muscle-length alone does not seem sufficient criteria to rule out hamstring surgery. • Muscle length is not predictive of post-operative increase in anterior pelvic tilt. • Initial posterior pelvic tilt leads to larger increase in anterior pelvic tilt. • Hamstrings lengthening leads to mean 8.97° improvement in peak knee extension. • Hamstrings lengthening leads to mean 4.19° increase in anterior pelvic tilt. [ABSTRACT FROM AUTHOR]

This paper proposes an easy to calculate and adaptable summary gait metric, the Gait Abnormality Index (GAI), which is capable of simultaneously including kinematic and kinetic data, overcoming a key limitation of existing metrics. To determine the validity, reliability and sensitivity of the GAI. The GAI is calculated by averaging Gait Abnormality Scores, which are normalised distance metrics used to describe the deviation of pathological gait data from that of healthy controls. Validity was assessed using Pearson's correlation analysis to explore relationships between the GAI and the Gait Profile Score. Test-retest reliability of the GAI was assessed using intra-class correlation coefficients (ICC) and standard error of the measurement (SEM), and data from total hip arthroplasty patients. An independent samples t-test was used to compare GAI scores between knee osteoarthritis and total hip arthroplasty patients to explore the metrics sensitivity. A strong positive correlation (r ≥ 0.896; p < 001) was reported between the GAI and the Gait Profile Score. Good test-retest reliability (ICC =0.830) was reported for the GAI. Knee osteoarthritis patients displayed significantly (p =.017; Hedge's g effect size = 0.98) greater GAI scores compared to total hip arthroplasty patients, with the mean difference (0.34 a.u) above the SEM (0.15 a.u). The GAI offers an easy to calculate summary metric for three-dimensional gait analysis, which displays good validity and reliability, and is sensitive to different pathological conditions. ● The Gait Abnormality Index provides a valid summary gait metric. ● The Gait Abnormality Index provides a reliable summary gait metric. ● The Gait Abnormality Index provides a sensitive summary gait metric. [ABSTRACT FROM AUTHOR]

Net joint moments (NJM) are typically normalized for a (combination of) physical body characteristics such as mass, height, and limb length using ratio scaling to account for differences in body characteristics between individuals. Four assumptions must be met when normalizing NJM data this way to ensure valid conclusions. First, the relationship between the non-normalized NJM and participant characteristic should be linear. Second, the regression line between NJM and the characteristic(s) used should pass through the origin. Third, scaling should not significantly perturb the statistical distribution of the data. Fourth, normalizing a NJM should eliminate its correlation with the characteristic(s) normalized for. This study assessed these assumptions using data collected among 59 individuals running at 10 km h−1. Standard inverse dynamics analyses were conducted, and ratios were computed between the sagittal-plane hip, knee and ankle NJM's and the participant's mass, height, leg length, mass × height, and mass × leg length. The most important finding of this study was that none of the scaling variables fulfilled all assumptions across all joints. However, scaling by mass, mass*height and mass*leg length satisfied the assumptions for the knee joint moment and log-transformed hip joint moment, suggesting these methods generally performed best. Our findings suggests that scaling by mass, mass*height and mass*leg length may be considered to normalize joint moments during running. Nevertheless, we urge researchers to check the statistical assumptions to ensure valid conclusions. We provide supplementary code to check the statistical assumptions, and discuss consequences of inappropriate scaling. • Joint moments are often normalized for body characteristics such as mass and height. • Four assumptions must be met when normalizing joint moments for valid conclusions. • None of the normalization variables fulfilled all assumptions across all joints. • Normalizing by mass, mass*height and mass*leg length may be considered for running. [ABSTRACT FROM AUTHOR]

• A novel model of using nSFEM and DPM to solve particle-laden flows. • The super robustness in handling extremely distorted polygonal meshes of the present method. • The unified implementation of mean value coordinates interpolation as shape function and fluid drag interpolation with high-fidelity. • The polygon mesh in this paper shows a great adaptation to complex geometry. In this work, an n-sided polygonal smoothed finite element method (nSFEM) using mean value shape function for concave polygonal element coupled with the discrete phase model (DPM) is developed to solve particle-laden flows. The fluid phase is solved using nSFEM stabilized by the well-developed characteristic-based split (CBS) algorithm. The concave polygonal element is successfully constructed via the intrinsic characteristic of mean value shape function and a new smoothing domain (SD) construction with more physical meaning; thus, addressing the severely distorted local mesh, as well as retaining good geometric adaptability. In the meantime, the modeling of the coupling between the fluid and the particle is achieved by reusing the mean value interpolation to obtain the fluid drag force acting on the particle. The accurate capture of fluid velocities at particle positions within arbitrary polygonal elements via mean value interpolation ensures fluid drag with high-fidelity. Several classical numerical examples, including particle-laden flow around a circular cylinder, are presented to demonstrate the high accuracy and good robustness, and the capability of the proposed method for predicting particle motion in the analysis of complex particle-laden flows. [ABSTRACT FROM AUTHOR]

An asymptotic analysis is conducted of the effect surface vibrations may play in mitigating the resistance present in the system consisting of a fluid contained between a pair of parallel flat plates in relative motion. Previous numerical computations of this situation, which has applications in both biological and technological contexts, have suggested that small vibrations that move at a fast phase speed can lead to substantial reductions in the resistance. The effect seems to be a somewhat intricate function of the wavelength of the vibration modes. Our analysis uncovers the properties of the various phenomena that are at work and describes the interplay between them. The techniques employed here lend themselves to the extension to other situations including problems in which propulsion effects in fluid systems can be induced by vibrations. [ABSTRACT FROM AUTHOR]

Postural instability is a risk factor for falls in older adults. It is possible to detect postural stability using an integrated accelerometer (ACC) sensor in a smartphone. Therefore, a novel ACC-based smartphone application running on the Android operating system called BalanceLab was created and tested. This study aimed to determine the validity and reliability of a novel ACC-based Android smartphone application for assessing balance in older adults. Using BalanceLab, 20 older adults completed three balance assessments: the Modified Clinical Test of Sensory Interaction in Balance (MCTSIB), a single-leg stance test (SLST), and a limit of stability test (LOS). The validity of this mobile application was investigated using a three-dimensional (3D) motion analysis system and the Fullerton Advanced Balance (FAB) scale. The test-retest reliability of this mobile application was determined on two separate occasions within one day, at least two hours apart. The two static balance assessments (the MCTSIB and SLST) demonstrated moderate to excellent correlation with the 3D motion analysis system (r = 0.70–0.91) and the FAB scale (r = 0.67–0.80). However, the majority of the dynamic balance tests (the LOS tests) did not demonstrate any correlation with the 3D motion analysis system or the FAB scale. This novel ACC-based application demonstrated good to excellent test-retest reliability (ICC = 0.76–0.91). A static, but not dynamic, balance assessment tool that uses a novel ACC-based application for Android can be used to measure balance in older adults. This application has moderate to excellent validity and test-retest reliability. • A new accelerometer-based app was examined for its reliability and validity. • A balance app demonstrated high test-retest reliability. • An app showed a high level of validity in static but not in dynamic balance tests. • An older adult's static balance can be evaluated with a new balance app. [ABSTRACT FROM AUTHOR]

Markerless motion capture systems have the potential to make clinical gait analysis more efficient and convenient. Theia3D is a commercially available markerless system that may serve as an alternative to traditional gait analysis for clinical gait laboratories. What is the concurrent validity of markerless gait analysis using Theia3D compared to traditional marker-based gait analysis in pediatric clinical gait patients? Thirty-six patients (20 male, age 2–25 years) with a range of diagnoses underwent clinical gait analysis with data being captured concurrently by a traditional marker-based motion capture system (Vicon Nexus) and a commercial markerless system (Theia3D). Multiple left strides were averaged for each subject, and the difference in kinematics (Theia - Vicon) was calculated over the gait cycle and evaluated using root mean square difference (RMSD), mean difference, and RMSD after subtracting the mean value across the gait cycle (RMSD offset). Sub-analysis was performed for 25 patients with foot deformities, 9 wearing ankle-foot orthoses, and 6 walking with assistance (cane, crutches, walker, or handheld). Kinematics showed similar patterns between the marker-based and markerless systems. RMSD was < 6° except for pelvic tilt, hip flexion, ankle inversion, foot progression, and transverse plane rotation of the hip, knee, and ankle. These measures mainly differed due to an offset between the curves. After adjusting for offsets, all RMSD offset were < 6°. RMSD was larger for patients with foot deformities, wearing orthoses, or using assistive devices, but all RMSD offset were still < 8°. In some cases, however, the markerless system had greater trial-to-trial variability, showed a larger knee varus "bump" in swing, or failed to track the subject. This study provides preliminary evidence of concurrent validity of Theia3D for pediatric patients with abnormal gait. However, some questions remain regarding identification of the knee axis and for patients with foot deformity or assistive devices. • Theia3D and Plug-in-Gait produce similar kinematic patterns. • Markerless kinematic curves are offset from marker-based for some variables. • Systems differ more with foot deformity, orthotics, and assistive devices. • Questions remain about Theia3D knee axis definition and hip rotation. [ABSTRACT FROM AUTHOR]

Visual motion analysis is crucial for humans to detect external moving objects and self-motion which are informative for planning and executing actions for various interactions with environments. Here we show that the image motion analysis trained to decode the self-motion during human natural movements by a convolutional neural network exhibits similar specificities with the reflexive ocular and manual responses induced by a large-field visual motion, in terms of stimulus spatiotemporal frequency tuning. The spatiotemporal frequency tuning of the decoder peaked at high-temporal and low-spatial frequencies, as observed in the reflexive ocular and manual responses, but differed significantly from the frequency power of the visual image itself and the density distribution of self-motion. Further, artificial manipulations of the learning data sets predicted great changes in the specificity of the spatiotemporal tuning. Interestingly, despite similar spatiotemporal frequency tunings in the vertical-axis rotational direction and in the transversal direction to full-field visual stimuli, the tunings for center-masked stimuli were different between those directions, and the specificity difference is qualitatively similar to the discrepancy between ocular and manual responses, respectively. In addition, the representational analysis demonstrated that head-axis rotation was decoded by relatively simple spatial accumulation over the visual field, while the transversal motion was decoded by more complex spatial interaction of visual information. These synthetic model examinations support the idea that visual motion analyses eliciting the reflexive motor responses, which are critical in interacting with the external world, are acquired for decoding self-motion. • Visual motion analysis is crucial for humans in executing quick reactions. • CNN was trained to decode self-motion from visual images during natural movements. • Distinct spatial integration is formed to decode rotational and translation motions. • The CNN exhibited similar tunings to motion stimuli with visuomotor reflexes'. • Estimated self-motion from visual motion could lead reflexive responses. [ABSTRACT FROM AUTHOR]

To investigate the effects of bandaging techniques on wrist motion on impact during different shot types in elite male boxers. Repeated-measures study. Field Experiment Two shot types, straight and bent arm, were assessed with 18 elite male boxers wearing either bandage only or bandage plus tape. Wrist motions and time to peak wrist angles, on impact, were measured with an electromagnetic tracking system. Wrist motion on impact occurred concurrently in flexion and ulnar deviation for both shot types. For both motions, significant (p < 0.001) effects for bandaging techniques (η2 = 0.580–0.729) and shot types (η2 = 0.165–0.280) were observed. For straight and bent arm shots, wrist motion on impact occurred within 50% and 40% respectively of total active wrist motion for bandage only compared to within 20% and 15% for bandage plus tape. Time to peak wrist angle on impact increased significantly (p < 0.001) for both shot types when adding tape to bandage. Adding tape provided an additional 25–30% reduction in wrist motion compared to bandage only, with a 1.2–1.4 increase in time to peak wrist angle, on impact for both shot types. This information could assist various individuals and organisations towards better hand-wrist protection. • This is the first study confirming bandaging effects on wrist kinematics in boxing. • Adding tape to bandage significantly reduces wrist motion on impact in boxing. • Greater effect with tape on wrist motion occurs in straight than bent arm shots. • Use of tape with bandage should be considered as standard practice when boxing. [ABSTRACT FROM AUTHOR]

The miniaturization of MEMS-based inertial measurement units (IMUs) facilitates their widespread use in a growing number of application domains. The fundamental sensor fusion task of orientation estimation is a prerequisite for most further data processing steps in inertial motion tracking, such as position and velocity estimation, joint angle estimation, and 3D visualization. Errors in the estimated orientations severely affect all further processing steps. Recent systematic comparisons of existing algorithms show that out-of-the-box accuracy is often low and that application-specific tuning is required to obtain high accuracy. In the present work, we propose and extensively evaluate a quaternion-based orientation estimation algorithm that is based on a novel approach of filtering the acceleration measurements in an almost-inertial frame and that includes extensions for gyroscope bias estimation and magnetic disturbance rejection, as well as a variant for offline data processing. In contrast to all existing work, we perform an extensive evaluation, using a large collection of publicly available datasets and eight literature methods for comparison. The proposed method consistently outperforms all eight literature methods and achieves an average RMSE of 2.9°, while the errors obtained with literature methods range from 5.3° to 16.7°. This improved accuracy with respect to the state of the art is observed not only in average but also for each of several different motion characteristics, as well as for gyroscope bias estimation. Since the evaluation was performed with one single fixed parametrization across a very diverse dataset collection, we conclude that the proposed method provides unprecedented out-of-the-box performance for a broad range of motions, sensor hardware, and environmental conditions. This gain in orientation estimation accuracy is expected to advance the field of IMU-based motion analysis and provide performance benefits in numerous applications. The provided open-source implementation makes it easy to employ the proposed method. • 6D+9D inertial sensor fusion with bias estimation and magnetic disturbance rejection. • Extensive validation against 8 literature methods on 6 diverse reference datasets. • Results show unprecedented accuracy with 2–5 times lower errors than existing filters. • VQF uses a single generic parametrization across all datasets, tuning is obsolete. • Easy-to-use open-source implementation provided in C++, Python, and Matlab. [Display omitted] [ABSTRACT FROM AUTHOR]

• The Kinematic Theory Transform (KTT), an efficient tool for analyzing spatiotemporal sequences. • Findings on arc and Euler curves to link virtual target points. • Findings on multiple functions to model bell-shaped velocities. • Statistical independence of the results with different primitives for biological and robotic movements. The Kinematic Theory of rapid movements, and its associated Sigma-Lognormal, model 2D spatiotemporal trajectories. It is constructed mainly as a temporal overlap of curves between virtual target points. Specifically, it uses an arc and a lognormal as primitives for the representation of the trajectory and velocity, respectively. This paper proposes developing this model, in what we call the Kinematic Theory Transform, which establishes a mathematical framework that allows further primitives to be used. Mainly, we evaluate Euler curves to link virtual target points and Gaussian, Beta, Gamma, Double-bounded lognormal, and Generalized Extreme Value functions to model the bell-shaped velocity profile. Using these primitives, we report reconstruction results with spatiotemporal trajectories executed by human beings, animals, and anthropomorphic robots. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel real-time physical interaction system that allows users to throw a virtual ball without using an intermediary device such as a controller. A dataset of throwing motions was captured from six actors, from which ground truth Point of Release (PoR) frames were calculated. We trained a PoR prediction model using motion features extracted from arm joints, and developed a detection algorithm to predict the PoR of a throwing motion in real-time. Evaluation of the system with pre-recorded throwing motion data results in detection errors of less than 50 ms. Qualitative results from six users of the real-time system in VR indicate that the task of throwing without a controller was very natural, although the system performed better for underarm than overarm throws. Finally, we report the relative importance of different joints and motion features for the PoR prediction task. [Display omitted] • A corpus of 1679 throwing/catching motions annotated with Point of Release (PoR). • A PoR prediction model using motion features extracted from arm joints in real-time. • A real-time VR system for throwing interactions using only the user's arm motion. • A ranking of 15 joint and motion feature combinations for PoR prediction. [ABSTRACT FROM AUTHOR]

The movement of the upper extremities is important for balance control in human walking. However, it is still unknown which mode of arm swing ensures the most stable gait due to the lack of appropriate measures which can quantify the movement of the upper extremities. In this study, we formulate a new parameter to numerically describe the arm swing. We investigated the effect of walking speed, sports activities and the subject's BMI on the movement of the upper limbs. Data of healthy 50 subjects from an external database was used. We used a human gait database for this analysis. All experimental trials were performed in Centre National de Rééducation Fonctionnelle et de Réadaptation – Rehazenter in Laboratoire d′Analyse du Mouvement et de la Posture in Luxembourg. Participants were asked to walk on a straight level walkway at 5 different speeds: 0–0.4 m/s, 0.4–0.8 m/s, 0.8–1.2 m/s, self-selected spontaneous and fast speeds. The human motion was recorded by using a 10-camera optoelectronic system. The amplitude of arm swing was greater in gait with self-selected fast speed then in slow walking. Higher walking speeds entailed also the more structured and repetitive movement of the upper extremities. For self-selected fast speed, the mean value of Pearson's correlation coefficient between arm swing amplitude of the left and right side was 0.935 ± 0.102, 0.943 ± 0.073 and 0.973 ± 0.020 for the young, middle aged and elderly group respectively, while in slow walking it was in the range 0.393–0.633 (for the representatives of the three groups). Our results could suggest other factors which influence arm swing, such as obesity and doing asymmetric sports. Our results suggest that choosing the lowest possible walking speed is not the best strategy as the most symmetric arm swing occurs during gait with self-selected speed. 1. Upper limbs movement analysis was performed on the basis of a human gait database. 2. Walking speed has a significant influence on the movements of the upper limbs. 3. The asymmetric sports, intensive exercises and obesity are factors which meaningfully affect the arm swing. [ABSTRACT FROM AUTHOR]

Owing to the growing number of elderly workers in developed countries, the age-friendly design of production systems is crucial for the success of human-centric manufacturing. To obtain knowledge for designing age-friendly production systems, this study conducted the first characteristic analysis of elderly workers, focusing on the set parts supply process. By combining motion analysis with the subjective mental workload survey, this study clarified the differences in how tasks are performed by elderly and young workers and how such differences affect the mental workload of elderly workers. The findings enable evidence-based design and implementation of age-friendly production systems. [ABSTRACT FROM AUTHOR]

The concept of installing two wind turbines on a floating platform, known as a floating twin-rotor wind turbine system, has recently garnered significant interest. This configuration can harness greater wind energy resources, reduce installation and mooring costs by sharing mooring lines, and minimize losses due to wake effects between turbines through yaw control. However, previous research has not sufficiently addressed the dynamic performance analysis of such systems. This study focuses on a high-capacity floating twin-rotor wind turbine system and develops an aero-hydrodynamic coupled analysis method based on the free vortex wake method and potential flow theory, specifically tailored for the twin-rotor configuration. This method facilitates real-time iterative calculations of wind and wave loads acting on the system and suggests optimization strategies for its design. Our findings indicate that the design of high-capacity floating twin-rotor systems can significantly reduce costs. Furthermore, the twin-rotor floating system design enhances wake recovery and achieves optimal comprehensive performance when the rotor spacing ratio (S/D) is 1.2 for the IEA 15 MW turbine. The coupled interactions induce periodic variations in aerodynamic performance, with the amplitude of these variations increasing with turbulence intensity. This research lays a theoretical foundation for advancing the design, platform optimization, and coupled computational analyses of large-capacity, large-scale floating twin-rotor wind turbine systems. • Floating twin-rotor wind turbine system. • Simulation method combine free vortex wake and potential flow theory. • Wake analysis of twin-rotor under turbulence effect. • System aero-hydro coupled motion analysis under turbulence effect. • The rotor spacing ratio in this system is recommended to be 1.2 under consideration of wake recovery and cost. [ABSTRACT FROM AUTHOR]

Accurate position information of an underwater target is the premise of successfully executing underwater missions, and this paper focuses on underwater target motion analysis (TMA) using delayed azimuth angles. Considering that the underwater sound speed (around 1500 m/s) is much smaller than the speed of light (3 × 108 m/s), the underwater TMA needs to adopt the non-stop model considering the effect of the target movement during signal propagation on state estimation, instead of the traditional go-stop model ignoring the target movement during signal propagation. The existing non-stop model is based on a constant-velocity target, and the model mismatch will make the estimated results biased when it is applied to a maneuvering target. In this paper, we focus on the constant-acceleration (CA) target and propose two methods to solve this problem. One is to extend the non-stop model to the case of a constant-acceleration target. We build the corresponding least squares (LS) estimator and derive the expression of the root mean square error (RMSE) of the LS solution. The other is to directly offset the estimation bias of the CA go-stop model and a bias-compensated algorithm is proposed to improve the performance. Simulations prove that the proposed methods can result in a smaller RMSE than the traditional CA go-stop model. Their RMSEs decrease with the number of measurements and observers and increase with random angle errors. When the number of measurements is small, the RMSE of the established CA non-stop model is smaller than that of the bias-compensated algorithm. As the number of measurements increases, their estimation precisions become gradually equal. The running time of the proposed methods increases with the number of measurements and observers. When the number of observers is small, the bias-compensated algorithm has the advantage of needing less running time. In addition, the running time of the bias-compensated algorithm does not approximately change with the random angle errors, while that of the CA non-stop model increases with the random angle errors. • The effect of delayed azimuth angles on state estimation is analyzed when the traditional CA go-stop model is used to achieve the underwater target motion analysis. • The CA non-stop model is established, and the RMSE analysis of the corresponding LS estimator is conducted. • A bias-compensated algorithm is proposed to improve the performance of the LS solution of the traditional CA go-stop model. [ABSTRACT FROM AUTHOR]

The evaluation of laser speckle statistics at different illumination angles is highly significant in industry, e.g., non-destructive surface inspection or motion analysis and measurement. Current speckle theories overlook the shadowing effect and the shape of laser spot, leading to inaccurate speckle statistics at large incident angles. This paper presents an oblique-incidence statistical model (OISM) for calculating subjective speckle statistics under oblique illumination. The model introduces an autocorrelation function of the scattered wave with shadowing effects and considers laser spot deformation by oblique illumination. With these additions, OISM allows for incident angles ranging from 0 ° to 80 ° and any lateral correlation length of the surface-height fluctuations. Extensive experiments demonstrate the accuracy of the proposed model, especially when the lateral correlation length is small or the illumination angle is close to 80 °. [Display omitted] • Subjective speckle statistics are affected by shadowing effect and laser spot shape. • Shadowing effects and laser spot deformation fundamentally affect speckle statistics. • The speckle shape is gradually compressed due to increasing incident angles. [ABSTRACT FROM AUTHOR]