Fast Movements Research Articles

Coastal Wetlands of Indus River Delta Are Under Risk Due to Reclamation: A Spatiotemporal Analysis During the Past 50 Years From 1972 to 2022

ABSTRACTCoastal wetlands are the most productive and biologically diverse ecosystems, benefiting both human populations and the total environment. However, they are continuously threatened by anthropogenic activities. Indus River Delta is the sixth largest in the world, has been adversely affected due to reclamation. The study examined the spatiotemporal dynamics of coastal wetlands and reclamation in the Indus River Delta from 1972 to 2022. Wetlands conversion to reclamation was extracted from 6‐Landsat images. A land cover transfer matrix was used to analyze land use land cover (LULC) changes in different time intervals. Area‐weight centroid was constructed to determine the migration trend of reclamation and coastal wetlands. Spatial accurateness was assessed using Producer's Accuracy (PA), User Accuracy (UA) and KAPPA coefficient (KC). The results reveal that from 1972 to 2022, the net area of wetlands declined by 1.9% (26.1 km2), while reclamation (settlement and cultivated land) increased by 14.7% (200.1 km2), and 27.5% (373.5 km2), respectively. The fastest areal change rate for coastal wetlands was −1.1 km2/year from 2012 to 2022, whereas the fastest areal change rate for settlement and cultivated land were 7.6 km2/year from 1992 to 2002 and 28.6 km2/year from 2012 to 2022. Centroids of wetlands moved slowly eastwards from Kharo Chan taluka to Keti Bandar in the first and third decades, then southwards in the second decade, later on, westwards in the fourth decade, and finally back southwards from Keti Bandar taluka to the Kharo Chan in the fifth decade with fastest movement. Centroids of settlement expanded in all directions over five decades. Centroids of cultivated land migrated westwards in the first, third and fourth decades, northwards in the second decade and southwards in the fifth decade from Keti Bandar to Kharo Chan. The findings of this study provide a scientific basis for sustainable land development and future planning.

EMG-assessed paratonia: A novel approach to investigating motor response inhibition in healthy subjects.

Paratonia is an involuntary muscle activity that occurs during passive joint mobilization and is common in people with dementia. It includes oppositional paratonia, in which muscle activity resists passive movement, and facilitatory paratonia, in which it assists movement. This phenomenon reflects a defect in motor response inhibition. In a recently published paper, we demonstrated that paratonia can be detected using surface electromyography (EMG) not only in patients with dementia but also in healthy individuals, the majority of whom do not exhibit clinically observable paratonia. This finding suggests that EMG-assessed paratonia may provide a novel approach to studying motor response inhibition in healthy subjects. The present study investigates this possibility for the first time. We recruited 120 healthy subjects under the age of 30, divided equally into three groups: sedentary, amateur, and professional athletes with low, moderate, and high levels of physical activity, respectively. Paratonia was assessed in the triceps and biceps brachii muscles during passive forearm movements performed manually. The results indicate that paratonia is more pronounced during fast and continuous passive movements, with facilitatory paratonia being more prevalent than oppositional paratonia. It is also more pronounced in the biceps than in the triceps. These findings, which mirror those previously observed in patients with dementia, suggest a similarity between paratonia in healthy subjects and those with cognitive impairment, supporting the hypothesis that paratonia in healthy individuals represents a form of impaired motor response inhibition. Furthermore, the comparison between groups showed that paratonia decreased with increasing physical activity, being least evident in athletes, more noticeable in amateurs, and most pronounced in sedentary individuals. This pattern confirms a key feature of motor response inhibition that has been shown in studies using traditional methods. Overall, our findings suggest that EMG-assessed paratonia provides a new method for studying motor response inhibition in healthy individuals.

Estimating descending activation patterns from EMG in fast and slow movements using a model of the stretch reflex.

Due to spinal reflex loops, descending activation from the brain is not the only source of muscle activation that ultimately generates movement. This study directly estimates descending activation patterns from measured patterns of muscle activation (EMG) during human arm movements. A simple model of the spinal stretch reflex is calibrated in a postural unloading task and then used to estimate descending activation patterns from muscle EMG patterns and kinematics during voluntary arm motion performed at different speeds. We observed three key features of the estimated descending activation patterns: (1) Within about the first 15% of movement duration, descending and muscle activations are temporally aligned. Thereafter, they diverge and develop qualitatively different temporal profiles. (2) The time course of descending activation is monotonic for slow movements, non-monotonic for fast movements. (3) Varying model parameters like the spinal reflex gain or the level of co-contraction does not qualitatively change the temporal pattern of estimated descending activation. Our findings highlight the substantial contribution of spinal reflex loops to movement generation, while at the same time providing evidence that the brain must generate qualitatively different descending activation patterns for movements that vary in their mechanical dynamics.

Evaluation of MRI safety of Ru-106 Eye applicators

Introduction: Ruthenium-106 brachytherapy is a primary treatment for Uveal Melanoma (UM), the most common intraocular malignancy in adults. This study evaluated the safety of Ru-106 applicators at 3 Tesla (T) MRI and their impact on image quality. Methods: Magnetic attraction and eddy currents were tested on a 20mm diameter Ru-106 applicator using a nylon string and a porcine eye. Safety criteria were defined by ocular oncologists, comparing magnetic field interactions to the forces exerted on the eye during surgery. Five UM patients were scanned at 3T MRI with the applicator in-situ using both conventional anatomical sequences and scans optimized to reduce metal artifacts. Results: Minimal magnetic interactions was observed. Eddy currents caused slight lagging during fast movements, and temporary detachment of the applicator of the porcine eye in conditions that were considered unrealistic for clinical scans. Significant susceptibility artifacts compromised image quality of the affected eye. Conclusion: Patients with Ru-106 applicators can be safely used in 3T MRI with some simple precautions. MR-image quality of the eye was poor due to major susceptibility artefacts, however, imaging of extra-ocular anatomy is feasible.

Insights Gained from the Review of Landslide Susceptibility Assessment Studies in Italy

We conducted a systematic literature review of 105 landslide susceptibility studies in Italy from 1980 to 2023, retrieved from the Scopus database. We discovered that Italian researchers primarily focus on rainfall-induced landslides (86.67% of the articles), especially shallow and fast movements (60%), with 72% of studies conducted at the local scale, while regional and national-level studies are rare. The most common data sources include remote sensing images validated by field surveys and official data portals at the national or regional level. Data splitting usually follows a 70:30 ratio and 24 modelling techniques were identified, with logistic regression being historically prevalent, although machine learning methods have rapidly gained popularity. Italian studies used 97 predisposing factors, with slope angle (98.09%), lithology (89.52%), land use/land cover (78.09%), and aspect (77.14%) being the most employed. This review also identifies and discusses a few less-used factors, like soil sealing, rainfall, NDVI, and proximity to faults, which showed promising results in experimental studies. Predisposing factors are generally selected by expert judgment, but methods for forward factors selection and collinearity tests are becoming more common. This review synthesizes current knowledge, pinpointing gaps, highlighting emerging methodologies, and suggesting future research directions for better integration of susceptibility studies with landslide risk management.

Sieve element traits differ in pulvini and petioles of Mimosa (Leguminosae, Caesalpinioideae) with different types of leaf movement

The vascular system, particularly the phloem, has been considered a key issue in driving the pulvini functioning. Studies comparing phloem in different leaf regions and in plants with different leaf movement types can help clarifying the aspects involved in the pulvini functioning. Here, we investigated the morphological traits of the sieve tube elements in a comparative way between pulvini and petioles of Mimosa pudica (a legume with fast leaf movements) and M. caesalpiniifolia (a legume with slow leaf movements). Pulvini and petioles were analyzed under light and transmission electron microscopy. Sieve elements in pulvini had thicker walls than those of petioles, especially in M. pudica. Nacreous walls occurred in the sieve elements of M. pudica pulvini. Dispersive and non-dispersive P-proteins and P-plastids occurred in the pulvini and petioles of both species. The marked differences in the lumen area and cell wall features of the sieve elements between pulvini and petiole indicate the specialization of the phloem in the pulvinus functioning.

International armed conflicts and their impact on aviation safety

Aviation transport is an integral part of the global infrastructure that ensures fast and efficient movement of people and cargo around the world. However, international armed conflicts create serious challenges for the aviation industry, affecting the safety of flights, the economic stability of airlines, as well as the international aviation community as a whole. This article is devoted to the analysis of the impact of armed conflicts on air traffic, taking into account real examples from different regions of the world. One key aspect of the research is examining the effects of airspace closures over conflict zones, which force airlines to change routes, increasing fuel and operating costs. In addition, the issue of flight security in conflict zones, where commercial aircraft are at increased risk of accidental or deliberate attacks, is analyzed. An important aspect of the article is also the assessment of economic losses suffered by airlines and airports due to conflicts. In particular, cases of flight cancellations, a decrease in passenger traffic, as well as an increase in insurance premiums, which significantly affect the financial performance of companies, are considered. The article also touches on issues of international cooperation in the field of aviation security, which is critically important for minimizing risks and ensuring the stability of air traffic in armed conflicts. In particular, the role of international organizations such as ICAO and the effectiveness of existing international agreements and treaties aimed at coordinating actions between states during crisis situations are analyzed. The article also focuses on developing practical recommendations for airlines and governments to improve their conflict preparedness, including route planning, risk management and improved information sharing systems. Given the complexity and multifaceted nature of the issue, the authors emphasize the need for further scientific research in this area in order to develop new strategies and tools to ensure the safety and stability of the global aviation industry in the face of armed conflicts. Thus, the article makes a significant contribution to the understanding of the impact of international armed conflicts on air traffic and offers a comprehensive approach to solving this problem.

A high-response-frequency bimodal network polyacrylate elastomer with ultrahigh power density under low electric field

Dielectric elastomers, used as driver modules, require high power density to enable fast movement and efficient work of soft robots. Polyacrylate elastomers usually suffer from low power density under low electric fields due to limited response frequency. Here, we propose a bimodal network polyacrylate dielectric elastomer which breaks the intrinsic coupling relationship between dielectric and mechanical properties, featuring relatively high dielectric constant, low Young’s modulus, and wide driving frequency bandwidth (~200 Hz) like silicones. Therefore, an ultrahigh power density (154 W kg−1@20 MV m−1, 200 Hz) is realized at low electric field and high resonance frequency, 75 times greater than at 10 Hz. Further, a rotary motor is developed, reaching an impressive speed of 1245 rpm at 19.6 MV m−1 and 125 Hz, surpassing previous acrylate-based motors and entering the high-speed domain of silicone-based motors. These findings offer a versatile strategy to fabricate high-power-density dielectric elastomers for low-electric-field soft actuators.

Managing operational resilience during the implementation of digital transformation in healthcare organisational practices.

The aim of this study is to investigate ways in which healthcare organisations can successfully maintain operational resilience within intricate and varied engagements during digital transformation processes. The present research applied cultural-historical activity theory as the theoretical framework and the ethnographic account as an approach and strategy to interpret and understand theoperational resilience of digital transformation tools in daily practices. Fieldwork was based on the research technique of shadowing, whereby the researcher closely accompanied the participants to record their conduct, activities and exchanges. Research results propose that effective operational resilience management in the implementation of digital transformation projects is based on (1) identifying and interpreting internal contradictions in everyday interactions as opportunities for capability developments; (2) navigating through multiple sites in fast and improvised movements, which derives in distributed and emergent practices; (3) interplaying between dyadic interactions and networked dependencies, which is achieved through the articulation of varied interests and (4)implementing novel intermediary tools, roles and regulations that facilitate the reduction of disturbances. The propositions of the present study indicate that the management of operational resilience extends beyond conventional adaptive and socio-technical models in healthcare services. The study emphasises the significance of expressing and converting differing interests into mutual advantages. It additionally demonstrates the intricacy of this obstacle, as it entails navigating through uncertain information, concealed interpretations and conflicting interests.

Reconfiguration and compensation design method for single-DoF closed-chain leg mechanism

Compared with a wheeled robot propelled by a rotary drive, a legged robot equipped with multiple motors on a single leg possesses superior adaptability, while at the cost of high energy consumption and less velocity. Inspired by the California mite, the design method of reconfigurable closed-chain leg mechanism with single degree of freedom (DoF) is proposed for effective striding and smooth propelling. Furthermore, the lower-mobility closed-chain leg mechanism is more appropriate for obtaining high frequency and fast movement with the merits of simple control system and rotary drive. Firstly, a reconfigurable design is performed in the swing phase for a high-knee motion intermittently driven by a walking motor through dynamic coupling. Secondly, its fluctuations in vertical displacement and horizontal speed are compensated through the contact outline curve and variable speed input in the supporting phase. Finally, the simulated performance is analyzed and compared, and a prototype is fabricated for fluctuating and obstacle-crossing experiments.

Foxtrot migration and dynamic over-wintering range of an Arctic raptor

Advances in tracking technologies have revealed the diverse migration patterns of birds, which are critical for range mapping and population estimation. Population trends are usually estimated in breeding ranges where birds remain stationary, but for species that breed in remote areas like the Arctic, these trends are often assessed in over-wintering ranges. Assessing population trends during the wintering season is challenging due to the extensive movements of birds in these ranges, which requires a deep understanding of the movement dynamics. However, these movements remain understudied, particularly in the mid-latitudes, where many Arctic breeders overwinter, increasing uncertainty in their ranges and numbers. Here, we show that the Arctic breeding raptor Rough-legged buzzard, which overwinters in the mid-latitudes, has a specific wintering strategy. After migrating ca. 1500 km from the Arctic to mid-latitudes, the birds continue to move throughout the entire over-wintering period, traveling another 1000 km southwest and then back northeast as the snowline advances. This continuous movement makes their wintering range dynamic throughout the season. In essence, this movement represents an extension of the quick migration process, albeit at a slower pace, and we have termed this migration pattern ‘foxtrot migration’, drawing an analogy to the alternating fast and slow movements of the foxtrot dance. These results highlight the potential errors in range mapping from single mid-winter surveys and emphasize the importance of this migration pattern in assessing the conservation status of bird species. Understanding this migration pattern could help to correctly estimate bird populations in over-wintering ranges, which is especially important for species that nest in hard-to-reach regions such as the Arctic.

Foxtrot migration and dynamic over-wintering range of an Arctic raptor.

Advances in tracking technologies have revealed the diverse migration patterns of birds, which are critical for range mapping and population estimation. Population trends are usually estimated in breeding ranges where birds remain stationary, but for species that breed in remote areas like the Arctic, these trends are often assessed in over-wintering ranges. Assessing population trends during the wintering season is challenging due to the extensive movements of birds in these ranges, which requires a deep understanding of the movement dynamics. However, these movements remain understudied, particularly in the mid-latitudes, where many Arctic breeders overwinter, increasing uncertainty in their ranges and numbers. Here, we show that the Arctic breeding raptor Rough-legged buzzard, which overwinters in the mid-latitudes, has a specific wintering strategy. After migrating ca. 1500 km from the Arctic to mid-latitudes, the birds continue to move throughout the entire over-wintering period, traveling another 1000 km southwest and then back northeast as the snowline advances. This continuous movement makes their wintering range dynamic throughout the season. In essence, this movement represents an extension of the quick migration process, albeit at a slower pace, and we have termed this migration pattern 'foxtrot migration', drawing an analogy to the alternating fast and slow movements of the foxtrot dance. These results highlight the potential errors in range mapping from single mid-winter surveys and emphasize the importance of this migration pattern in assessing the conservation status of bird species. Understanding this migration pattern could help to correctly estimate bird populations in over-wintering ranges, which is especially important for species that nest in hard-to-reach regions such as the Arctic.

Tau P301S Transgenic Mice Develop Gait and Eye Movement Impairments That Mimic Progressive Supranuclear Palsy.

Progressive supranuclear palsy (PSP) is a neurodegenerative disorder with an estimated prevalence of 5-7 people in 100,000. Clinically characterized by impairments in gait, balance, and eye movements, as well as aggregated Tau pathology, PSP leads to death in approximately 5-8 years. No disease-modifying treatments are currently available. The contribution of Tau pathology to the symptoms of patients with PSP is poorly understood, in part due to lack of a rodent model that recapitulates characteristic aspects of PSP. Here, we assessed the hTau.P301S mouse for key clinical features of PSP, finding progressive impairments in balance and gait coordination. Additionally, we found impairments in fast vertical eye movements, one of the most distinctive features of PSP. Across animals, we found that Tau pathology in motor control regions correlated with motor deficits. These findings highlight the utility of the hP301S mouse in modeling key aspects of PSP.

A slow limit: extensive motor training cannot overcome a limit on the production of slow and smooth motion.

Previous research from several paradigms indicated that people have difficulty in producing slow and smooth movements (SSM). It is not clear whether these difficulties are due to biomechanical constraints, planning constraints, or lack of experience with moving slowly. Here, we investigated the latter possibility: we empirically tested whether short-term practice and long-term expertise with moving slowly would result in an increased ability to perform SSM. In study 1, novice participants completed 10 training sessions in which they moved a stylus on a digitizing tablet as they traced an ellipse that moved at different frequency/peak velocity combinations, with frequencies ranging from 0.25 Hz to 0.875 Hz. In study 2, experts in slow movement (tai chi performers) and fast movement (karate performers) completed the same task in one session. The results indicated that all participants had difficulties in producing SSM, as evidenced by an increase in submovement rate with decreasing frequency. Participants in study 1 did show a marked improvement in their ability to produce fewer submovements while reducing mean squared jerk (MSJ). These short-term improvements were not evident in long-term slow motor expertise (i.e., tai chi). Taken together, our results suggest that SSM are likely difficult to produce due to a combination of several factors: lack of experience, planning, biomechanical, and neural constraints.NEW & NOTEWORTHY People can improve their ability to produce smooth slow movements in the short term (10 training sessions) in a sinusoidal tracking task by reducing the rate of submovements, but they are not able to eliminate them entirely. This lack of an ability to move slowly and smoothly was confirmed in a second experiment, where there was a lack of difference observed between long-term slow movement practitioners (i.e., tai chi experts) and novices.

Inter-beam handover schemes for LEO satellites in 5G satellite–terrestrial integrated networks

Unlike terrestrial handover schemes, the handover schemes in 5G satellite–terrestrial integrated network (STIN) face several challenges, such as large propagation delay, complex channel environment, and fast satellite movement. Therefore, the handover schemes designed in the 5G terrestrial network is not suitable for the 5G STIN. In view of this, this paper considers the inter-beam handover problem for the 5G STIN with a low earth orbit satellite and a ground user. We establish the satellite channel model, which includes path loss, rain attenuation, and multi-beam antenna gain. To model the mobile feature of the user, we consider a two-dimensional random walk model. Then, we propose A5 event-based conditional handover (CHO) scheme, time factor-based CHO scheme, and load factor-based CHO scheme to achieve efficient inter-beam handover. Considering that there may be multiple beams that meet the triggering condition in each handover scheme, we also propose three kinds of beam selection schemes, namely random beam selection scheme, maximum power-based beam selection scheme, and minimum distance-based beam selection scheme. To evaluate the performance of the proposed handover schemes, key performance indicators, such as handover frequency, ping-pong handover rate, unnecessary handover rate, handover failure rate, and average transmission rate are analyzed. Simulation results verify the superiority of the proposed handover schemes by comparing them with the benchmark scheme.

A piezoelectric driven amphibious microrobot capable of fast and controllable movement

Abstract Due to its excellent adaptability to the environment and flexibility in narrow spaces, amphibious microrobots have become an important research direction recently. This study proposes an amphibious microrobot driven by piezoelectric actuators with a body length of 4.5 cm and a mass of 1.4 g. The microrobot consists of two active front legs, two passive rear legs, two caudal fins, and a support frame. Each front leg and each caudal fin are designed as structures integrated with their respective piezoelectric actuators. The microrobot has a tilted body, and the ground exerts an oblique upward impact force that makes it jump forward when its front legs swing backwards. The opposite swing of the two caudal fins generates propulsion for swimming. The components of the microrobot are manufactured based on the monolithic laminate process. The monolithic front actuator-leg and monolithic actuator-fin both emerge from a multi-layer material laminate. The support frame is designed and fabricated as a monolithic structure to improve assembly accuracy and reduce redundant assembly steps. The manufactured microrobot demonstrates its flexible and fast amphibious movements. Its maximum land walking speed reaches 15.3 cm/s and its turning speed reaches 48.2 degrees per second. The microrobot has a maximum payload capacity of 5 g moving on land. When the front legs and caudal fins work simultaneously, its underwater swimming speed reaches 9.1 cm/s, and the maximum turning speed is 20.5 degrees per second. The microrobot also confirms a maximum payload of 3 g during its underwater movement.

Performance analysis of a blockchain-based messaging system implementation for air cargo supply chains

ABSTRACT The air cargo supply chain’s goal is to achieve fast shipment movement through multistage coordination among multiple air cargo stakeholders. The lack of transparency in the end-to-end supply chain and complex digital connectivity is what limits the traditional peer-to-peer communication flow in the fragmented air cargo industry. Blockchain technology can enhance communication transparency by streamlining multistage message flows via smart contracts and by acting as an intermediary to simplify digital connections among air cargo stakeholders. Despite the benefits of applying blockchain for air cargo messaging, as blockchain is an emerging technology, technical concerns in the areas of performance, privacy, and interoperability can hinder the practical adoption of the blockchain system. To address practical implementation concerns, a blockchain-based messaging system using the Algorand public blockchain is developed in our work to demonstrate the practicality of blockchain. Transaction data privacy can be protected by the encryption key exchange algorithm, which supports forward secrecy. Our experimental results provide practical performance insights into the Algorand blockchain for streamlined messaging from various aspects related to transaction submission, confirmation, and retrieval. Our results show that by leveraging the Algorand blockchain, our proposed system can offer scalable, efficient, reliable, and cost-effective communication channels for air cargo messaging.

The statistical building blocks of animal movement simulations.

Animal movement plays a key role in many ecological processes and has a direct influence on an individual's fitness at several scales of analysis (i.e., next-step, subdiel, day-by-day, seasonal). This highlights the need to dissect movement behavior at different spatio-temporal scales and develop hierarchical movement tools for generating realistic tracks to supplement existing single-temporal-scale simulators. In reality, animal movement paths are a concatenation of fundamental movement elements (FuMEs: e.g., a step or wing flap), but these are not generally extractable from a relocation time-series track (e.g., sequential GPS fixes) from which step-length (SL, aka velocity) and turning-angle (TA) time series can be extracted. For short, fixed-length segments of track, we generate their SL and TA statistics (e.g., means, standard deviations, correlations) to obtain segment-specific vectors that can be cluster into different types. We use the centroids of these clusters to obtain a set of statistical movement elements (StaMEs; e.g.,directed fast movement versus random slow movement elements) that we use as a basis for analyzing and simulating movement tracks. Our novel concept is that sequences of StaMEs provide a basis for constructing and fitting step-selection kernels at the scale of fixed-length canonical activity modes: short fixed-length sequences of interpretable activity such as dithering, ambling, directed walking, or running. Beyond this, variable length pure or characteristic mixtures of CAMs can be interpreted as behavioral activity modes (BAMs), such as gathering resources (a sequence of dithering and walking StaMEs) or beelining (a sequence of fast directed-walk StaMEs interspersed with vigilance and navigation stops). Here we formulate a multi-modal, step-selection kernel simulation framework, and construct a 2-mode movement simulator (Numerus ANIMOVER_1), using Numerus RAMP technology. These RAMPs run as stand alone applications: they require no coding but only the input of selected parameter values. They can also be used in R programming environments as virtual R packages. We illustrate our methods for extracting StaMEs from both ANIMOVER_1 simulated data and empirical data from two barn owls (Tyto alba) in the Harod Valley, Israel. Overall, our new bottom-up approach to path segmentation allows us to both dissect real movement tracks and generate realistic synthetic ones, thereby providing a general tool for testing hypothesis in movement ecology and simulating animal movement in diverse contexts such as evaluating an individual's response to landscape changes, release of an individual into a novel environment, or identifying when individuals are sick or unusually stressed.

Comparison of joint kinematics from optical marker-based and inertial sensor-based motion capture during change-of-direction movements

The development of inertial measurement units (IMUs) has opened up possibilities to test kinematics of sports movements in natural environments (Di Paolo et al., 2023). This advantage over lab-based optical motion capture (OMC) comes at the cost of inherent inaccuracies. Especially, fast multidirectional movements including de- and accelerations pose a challenge for inertial-based movement reconstruction with limited task-specific validation research available (Heuvelmans et al., 2022). Therefore, we aimed to test the validity of IMU-based kinematics in a 180° change of direction (COD) task to provide insight into the applicability for future on-field ACL injury risk research. Twenty-six sports science students were equipped with eight IMU sensors of the Noraxon Ultium Motion System and an adaption of the Plug-in-Gait markerset (53 markers) recorded by a VICON OMC system. They performed five 180° anti-clockwise CODs at their maximum speed. As an example for sagittal and frontal plane angles relevant for ACL injury risk, the knee flexion and abduction angle at the initial contact of the cutting step (right leg) were calculated using the Noraxon MyoMotion software for IMU-recorded data and OpenSim for marker-based OMC data. At the time of abstract submission, the data of five (randomly chosen) participants had been analysed. More participants and more joint angle outcomes will be included in follow-up analyses. Deviations between IMU-generated and OMC-generated joint angles are depicted in Figure 1. Within subjects, deviations below 1.5 standard deviations were observed. Between subjects, deviations ranged from 0° and 22° in knee flexion angles and 0° and 11° in knee abduction angles. A general trend towards higher joint angles measured by the IMU system is noticeable, suggesting a possible off-set error. For four out of five participants, the knee flexion deviation was below 10°, which can be considered an accuracy which is tolerable but requires consideration in the interpretation (< 2°: good accuracy, 2-5°: acceptable accuracy, 5-10°: tolerable accuracy, > 10° unbearable accuracy; Bessone et al., 2022). Deviations in knee abduction angles appear too large given the small physiological joint range and motion in this plane. This preliminary analysis of individual deviations suggests acceptable deviations between IMU and OMC measurements regarding knee flexion but problematic deviations for knee abduction. Prospectively, we aim to investigate possible off-set corrections, e.g. through a better alignment of the underlying biomechanical models, and alternative approaches for IMU-based movement reconstruction, e.g. through optimal control simulations (Nitschke et al., 2024).

An enhanced electromagnetic energy harvester based on dual ratchet structure with secondary energy recovery

Abstract With the continuous advancement of ultra-low-power electronic devices, capturing energy from the surrounding environment to power these smart devices has emerged as a new direction. However, most of the mechanical energy available for harvesting in the environment exhibits ultra-low frequencies. Therefore, the feasibility of self-powering low-power devices largely depends on the effective utilization of this ultra-low-frequency mechanical energy. Consequently, this work proposes an enhanced electromagnetic energy harvester based on a dual ratchet structure with secondary energy recovery. It converts ultra-low frequency vibrations into fast rotational movements by means of a rack and pinion mechanism, thus achieving high power output while maintaining a simple structure. Experimental tests demonstrate that the proposed harvester exhibits excellent power output under ultra-low-frequency external excitation. Under external excitation with a frequency of 1.5 Hz and an amplitude of 22 mm, with the optimal load matched at 20 Ω, the maximum power output reaches 598 mW, with a power density of 1572.65 μW/cm³. The secondary energy recovery power accounts for 34.4 %, resulting in a 52.56 % enhancement in the energy harvester's output performance. Additionally, hand-cranking tests indicate that the fabricated prototype of the electromagnetic energy harvester can power some common electronic devices, including smartphones, showcasing significant application potential.