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Specific aesthetic features of the object and observer's expertise seem to be related to the perception of motion aesthetics. How differing kinematic motion characteristics and their manifestation are related to the perception of motion aesthetics and how this relates to the observer's expertise is still investigated. It is hypothesized that different manifestations of the kinematic motion characteristics amplitude, fluency, and complexity are related to perceived motion aesthetics of dance skills and observer's expertise. Dancers' and non-dancers' perception of motion aesthetics was assessed when watching stick-figure video sequences of semi-standardized dance jumps, classified relating to three kinematic motion characteristics and their semantic differentials. Large, fluent, and complex dance jumps were perceived as more aesthetic than small, jerky, and simple jumps. There was no general effect on the observer's expertise. Nevertheless, non-dancers gave higher aesthetic ratings for complex dance jumps than dancers. Findings indicate that expertise does not relate to the perception of motion aesthetics per se. In contrast, specific kinematic motion characteristics of dance jumps do. Amplitude and fluency seem to be remarkable objective aesthetic qualities when perceiving motion aesthetics of dance skills. The observed dance skills' complexity appears to be a critical parameter when addressing observers with different expertise. [ABSTRACT FROM AUTHOR]

In this study, structural characteristics and response characteristics of a base isolated building are evaluated in Time-Frequency domain. Structure story responses and earthquake data set were recorded by the accelerometer network during the 1994 Northridge earthquake. Timefrequency domain continuous wavelet transform is used to monitor the variations of structural frequencies in time. In accordance with the efficiency of the base isolation, reduction of significant energy transmission to upper structure in the higher frequency range is traced instantaneously. The seismic base isolation performance of the observed structure can be identified and understood clearly in the time-frequency domain also. It has been observed that the time-frequency analysis is a very efficient method in terms of showing the variations of the earthquake effect and the behavior kinematics and design forces in the superstructure in time and frequency domain. [ABSTRACT FROM AUTHOR]

Hallux Rigidus is the result of degeneration of the 1st metatarsophalangeal joint (1st MTPJ). In end-stage hallux rigidus, treatment is mainly surgical with arthrodesis being a favourable option. Although the biomechanical effects of arthrodesis have been examined, a detailed comparison of pre- and post-operative biomechanics has yet to be conducted. Does 1st MTPJ arthrodesis positively affect foot kinematics and plantar pressure distribution? Twelve 1st MTPJ arthrodesis were performed in patients with a mean age of 53.5 ± 5.4 years and follow up time of 6.9 ± 1.0 months. Pre- and post-operative data were collected at a CMAS (Clinical Movement Analysis Society) accredited gait laboratory using a BTS motion capture system and pedobarographic pressure plates. Patient outcome measures were also assessed using the MOXFQ. Statistical analysis was conducted using a two-way repeated measures ANOVA. Significant changes in stride length, cycle duration, cadence and velocity were identified following 1st MTPJ arthrodesis. A significant reduction in forefoot-hallux dorsiflexion at toe-off was identified for the operated foot from the pre-operative (20.23 ± 5.98°) to post-operative (7.56 ± 2.96°) assessment. Post-operative sagittal and transverse plane changes in the operated foot were also identified. Peak pressure and PTI results indicated significant lateralisation of load for the operated foot, but importantly this was not influenced following arthrodesis. Finally, there was a significant improvement in MOXFQ score. Following 1st MTPJ fusion there is an improvement in overall gait mechanics which accompanied by the improved MOXFQ score indicates a reduction in pain and improved confidence during gait. The lack of post-operative dorsiflexion at forefoot-hallux caused load to remain lateralised and compensatory mechanisms to occur at the more proximal joints within the foot. These results provide valuable information for clinicians and will enable more accurate counselling to be provided to patients with end-stage hallux rigidus. • Stride length, cycle duration and cadence significantly increased. • There was an improvement in the patient reported outcome. • Forefoot-hallux dorsiflexion for the operated foot significantly reduced at toe-off for the operated foot. • Load remains weighed on the lateral aspect of the foot. • Compensatory kinematic mechanics occur at more proximal joints within the foot. [ABSTRACT FROM AUTHOR]

To study the body posture characteristics when walking with trolley case, and to explore the effects of different usage methods and weights of trolley case on body posture characteristics. Fifteen subjects pushed and pulled(Condition 1 and 2) the case with three load weights of 10 %, 20 % and 30 % of their own body weight with 0 % no load as baseline for both conditions. The basic gait parameters, kinematic and kinetic data were collected using the VICON infrared motion capture system and a 3D force platform. Two repeated measures factor (condition×weight) analysis of variance was used for statistical analysis of the gait temporal and spatial parameters, as well as trunk angle, kinetic ground reaction force, shoulder joint force, and trunk moment. Significant condition*weight interactions were detected in DLST (Double Limb Stance Time) (F=5.341，P = 0.006), GRF (Ground Reaction Force) in frontal plane (F=10.507, p < 0.001) and vertical plane (F=3.751, p = 0.021), shoulder joint force in sagittal plane (F=21.129, p < 0.001), and flexion-extension angle of the trunk in the sagittal plane (F=4.888, p < 0.010). Significant main effects were detected in walking speed (F=35.842, p < 0.001), right support time (F=12.156, p < 0.001), left swing time (F=8.506, p < 0.001), left support time (F=1.122, p < 0.001), right step length (F=33.900, p < 0.001), and left step length (F=14.960, p < 0.001) under different weights. A significant main effect was detected in sagittal GRF (F=11.77, p < 0.001), trunk rotation angle (F=4.124, p = 0.016), amplitude of COM (F=2.993, p = 0.046), under different weights. When the weight of the case exceeds 20 % of the body weight, from the perspective of energy efficiency, the push method is more advantageous than the pull method. When walking with luggage, people tend to maintain the stability of their trunk posture by adjusting the force on their arms more often. • To explore the effects of Trolley Case on body posture characteristics. • Adopt two methods and three kinds of weight control trolley. • VICON and three-dimensional dynamometer measure the basic parameters. • Changes in body posture parameters vary across different Trolley Case usage methods. • It is recommended to use the side push mode and 20 % body weight control trolley. [ABSTRACT FROM AUTHOR]

Perinatal running participation has increased recently; however, pregnancy related symptoms can limit activity. Perinatal running biomechanics could inform interventions to help perinatal individuals maintain an active lifestyle. Are perinatal running biomaechanics and muscle activation different compared to nulligravida females? Sixteen pregnant participants completed self-selected velocity running during second trimester (2 T), third trimester (3 T), and postpartum (PP) and 16 matched controls completed these procedures once in this case control study. Kinematic, kinetic, and electromyography (EMG) data were collected using a motion capture system, force plates, and EMG electrodes. Peak trunk, pelvis, hip, knee, and ankle kinematics and hip, knee, and ankle moments during stance phase, and average and peak erector spinae (ES), gluteus maximus (GMax), and gluteus medius (GMed) EMG amplitude and duration of activation during stance and swing phases were calculated. Independent t-tests were used to compare 2 T, 3 T, and PP to control participants (α < 0.05). Running velocity was slower during 3 T compared to control participants. At all pregnancy timepoints compared to the control group, peak trunk contralateral rotation was smaller. During 2 T and 3 T peak hip flexor moments were smaller. At 3 T pelvis contralateral rotation was smaller, ES average amplitude was greater during swing, GMax percent duration during stance and GMed percent duration during swing were smaller. At PP trunk flexion was smaller and knee abduction was greater (all p < 0.05). Decreased running velocity may help offset increased demand during pregnancy. During 3 T, greater ES activation, smaller trunk and pelvis motion, and altered gluteal activation could indicate trunk rigidity combined with modified hip stabilizer muscle utilization. During PP, the rigid trunk combined with greater knee abduction may indicate hip and trunk strength deficits. Altered trunk and hip motion and activation could be relevant to pathologies such as perinatal low back, pelvic girdle, or knee pain. • Decreased trunk rotation was observed during and after pregnancy with running. • Increased trunk activity and decreased gluteal muscle duration were observed during pregnancy. • During third trimester slower running may decrease joint and muscle demand. • Postpartum runners demonstrated an upright trunk and increased knee abduction. [ABSTRACT FROM AUTHOR]

Exploring the use of minimum marker sets is important for balancing the technical quality of motion capture with challenging data collection environments and protocols. While minimum marker sets have been demonstrated to be appropriate for evaluation of some motion patterns, there is limited evidence to support model choices for abrupt, asymmetrical, non-cyclic motion such as balance disturbance during a bathtub exit task. How effective are six models of reduced complexity for the estimation of centre of mass (COM) displacement and velocity, relative to a full-body model. Eight participants completed a bathtub exit task. Participants received a balance perturbation as they crossed the bathtub rim, stepping from a soapy wet bathtub to a dry floor. Six reduced models were developed from the full, 72-marker, 12 segment 3D kinematic data set. Peak displacement and velocity of the body COM, and RMSE (relative to the full-body model) for displacement and velocity of the body COM were determined for each model. Main effects were observed for peak right, left, anterior, posterior, upwards and downwards motion, and peak left, anterior, posterior, upwards and downwards velocity. Time-varying (RMSE) was smaller for models including the thighs than models not containing the thighs. In contrast, inclusion of upper arm, forearm, and hand segments did not improve model performance. The model containing the sacrum marker only consistently performed the worst across peak and RMSE metrics. Findings suggest a simplified centre of mass model may adequately capture abrupt, asymmetrical, non-cyclic tasks, such as balance disturbance recovery during obstacle crossing. A reduced kinematic model should include the thighs, trunk and pelvis segments, although models that are more complex are recommended, depending on the metrics of interest. • Participants were perturbed as they stepped from a soapy wet bathtub to a dry floor. • Six reduced models were compared against a 12-segment full-body model. • A simplified centre of mass model may capture abrupt, asymmetrical, non-cyclic tasks. • A reduced kinematic model should include the thighs, trunk and pelvis segments. [ABSTRACT FROM AUTHOR]

It has been suggested that sitting posture affects clavicular, scapular and spinal kinematics, however its effects in people with neck pain and scapular dysfunction remain unknown. The study aimed to determine the clavicular and scapular kinematics in different sitting postures in patients with neck pain and scapular dysfunction. Thirty-four participants with neck pain and scapular dysfunction were recruited into the study. Kinematics of the clavicle and scapula were recorded using motion analysis at rest and during arm elevation (at 30, 60, 90, and 120 degrees) in a slouched and upright sitting posture. Compared to the upright sitting posture, the slouched sitting posture had increased clavicular protraction and elevation as well as scapular internal rotation and anterior tilt at rest and during the arm raising and lowering phases (at 30, 60, 90, and 120 degrees) (p < 0.05). The slouched sitting also had increased scapular upward rotation in the lowering phase at all angles (p < 0.05). The slouched sitting posture has a significant influence on clavicular and scapular kinematics. Awareness of good sitting posture should be encouraged in patients with neck pain and scapular dysfunction. • Slouched sitting alters the clavicular and scapular orientations and movements. • Patients with neck pain tend to protract shoulder girdle in slouched sitting. • Side of neck pain has no influence on clavicular and scapular positions in sitting. [ABSTRACT FROM AUTHOR]

Longer distance water delivery culverts pose obstacles such as deposited silt, stones, and dead trees. In this paper, a crawling robot is designed to mimic the joint structure of a turtle using bionic design principles. The mechanism and gait of the robot are analyzed. The kinematics model of the robot is established using the D-H method and analytical approach, while the dynamics model is established using Lagrange's method. Based on kinematics and dynamics analysis theory, compound cycloid and cubic polynomial motion trajectories for the robot foot are planned along with a crawling gait resembling that of a turtle's abdomen. Simulation experiments and scale prototype experiments confirm that when gait parameters are identical, the energy consumption of compound cycloid trajectory exceeds that of cubic polynomial foot trajectory. When planning these two types of foot trajectories, it was observed that energy consumption ratio decreases with increasing step length but increases with increasing step height. [ABSTRACT FROM AUTHOR]

The thermodynamic non-equilibrium (TNE) effects and the relationships between various TNE effects and entropy production rate, morphology, kinematics, and dynamics during two initially static droplet coalescences are studied in detail via the discrete Boltzmann method. Temporal evolutions of the total TNE strength D ¯ * and the total entropy production rate can both provide concise, effective, and consistent physical criteria to distinguish different stages of droplet coalescence. Specifically, when the total TNE strength D ¯ * and the total entropy production rate reach their maxima, it corresponds to the time when the liquid–vapor interface length changes the fastest; when the total TNE strength D ¯ * and the total entropy production rate reach their valleys, it corresponds to the moment of the droplet being the longest elliptical shape. Throughout the merging process, the force contributed by surface tension in the coalescence direction acts as the primary driving force for droplet coalescence and reaches its maximum simultaneously with coalescent acceleration. In contrast, the force arising from non-organized momentum fluxes (NOMFs) in the coalescing direction inhibits the merging process and reaches its maximum at the same time as the total TNE strength D ¯ * . In the coalescence of two unequal-sized droplets, contrary to the larger droplet, the smaller droplet exhibits higher values for total TNE strength D ¯ * , merging velocity, driving force contributed by surface tension, and resistance contributed by the NOMFs. Moreover, these values gradually increase with the initial radius ratio of the large and small droplets due to the stronger non-equilibrium driving forces stemming from larger curvature. However, non-equilibrium components and forces related to shear velocity in the small droplet are consistently smaller than those in the larger droplet and diminish with the radius ratio. This study offers kinetic insights into the complexity of thermodynamic non-equilibrium effects during the process of droplet coalescence, advancing our comprehension of the underlying physical processes in both engineering applications and the natural world. [ABSTRACT FROM AUTHOR]

This study investigates the free-turning flight of butterflies (Idea leuconoe) and analyze the influence of body posture and asymmetric motions of left and right wings on aerodynamics and the asymmetric flow field structure. Three high-speed cameras were used in the biological experiment to observe the turning flight motions, and varied motion angles were calculated. The results showed that the body started to tilt to the right at 0.3 cycles and the flapping amplitude of the inner wing increased by 20.31% relative to the outer wing during a cycle. The outer wing showed a forward-then-backward deviation, whereas the inner wing exhibited the opposite trend. A three-dimensional numerical model with six degrees of freedom and prescribed motion functions was constructed to simulate the flight of butterflies. The results revealed that the roll angle was the primary factor influencing the direction of aerodynamic forces and had a similar mechanism as the banked turn of a fixed wing. During the downstroke, the outer wing provided the normal force while the inner wing contributed to the vertical force, and both wings generated horizontal thrust during the upstroke. The asymmetric wing motions and the lateral inflow velocity were the two major factors affecting the flow field structure. The difference in flapping amplitudes caused the inner wing to generate greater vertical-normal resultant force first. The asymmetric forewing-deviation angle and the lateral flow influenced the direction of the spanwise flow to enhance the strength of the leading-edge vortex and stabilize the attached flow for the outer wing. [ABSTRACT FROM AUTHOR]

Mosquitoes exhibit a distinctive and remarkable flight pattern, flapping their wings at a high frequency with relatively small stroke amplitude. However, until recently, the underlying aerodynamic mechanisms have remained unclear. Furthermore, there is a lack of understanding about their flight behaviors after blood-feeding and the corresponding aerodynamic characteristics. This study aims to explore this uncharted area, conducts experiments to acquire kinematic and morphological data and numerical simulations to obtain three-dimensional flow characteristic. Further analysis uncovers several key findings. Both before and after blood-feeding hovering exhibit a similar flapping wing pattern, characterized by downstroke and upstroke with three stages of each half stroke. After blood-feeding, there are significant increases in stroke amplitude, mid-downstroke duration, velocity, and flip angles. Additionally, body pitch, stroke plane tilt, and Reynolds number experience increments. In hovering, mosquitoes balance vertical force with weight, with substantial peaks observed in each stage, particularly during the mid-stroke. After blood-feeding, the vertical force experiences a 3.3-fold increase, with the majority of the increase occurring during the mid-downstroke. The study identifies three unsteady mechanisms for aerodynamic force generation without blood-feeding hovering, namely, added-mass force, delayed stall, and fast-pitching-up rotation. These mechanisms persist after blood-feeding, with a greater reliance on delayed stall to support increased weight. [ABSTRACT FROM AUTHOR]

The ability to estimate lower-extremity mechanics in real-world scenarios may untether biomechanics research from a laboratory environment. This is particularly important for military populations where outdoor ruck marches over variable terrain and the addition of external load are cited as leading causes of musculoskeletal injury As such, this study aimed to examine (1) the validity of a minimal IMU sensor system for quantifying lower-extremity kinematics during treadmill walking and running compared with optical motion capture (OMC) and (2) the sensitivity of this IMU system to kinematic changes induced by load, grade, or a combination of the two. The IMU system was able to estimate hip and knee range of motion (ROM) with moderate accuracy during walking but not running. However, SPM analyses revealed IMU and OMC kinematic waveforms were significantly different at most gait phases. The IMU system was capable of detecting kinematic differences in knee kinematic waveforms that occur with added load but was not sensitive to changes in grade that influence lower-extremity kinematics when measured with OMC. While IMUs may be able to identify hip and knee ROM during gait, they are not suitable for replicating lab-level kinematic waveforms. [ABSTRACT FROM AUTHOR]

Children aged 3–8 are in a critical period for motor development and postural control. Running is a basic motor skill that children need to master in early childhood. While running, children are prone to dangerous events such as falls. This study investigates the kinematic characteristics of running by children associated with different interference tasks, i.e., normalized running, cognitive dual-tasks, and obstacle crossing tasks, and provides a theoretical foundation for the interference mechanism of children's dynamic postural control and for screening of motor disorders. Two hundred children aged 3–8 were recruited. The BTS Bioengineering infrared motion capture system was used to collect spatiotemporal and kinematic running data under three tasks. Repeated measures of variance analysis were used to compare the effects of different interference tasks and ages on children's running signs. The main and interaction effect tests were compared by the Bonferroni method. The results and conclusions are as follows: (1) Running characteristics of early childhood are influenced by interference tasks and age. With interference tasks, the overall characteristics of running by children aged 3–8 showed an increasing trend in running cycle time and a decreasing trend in stride length, step length, cadence, and speed. (2) Both cognitive and obstacle crossing tasks had costs, and cognitive task costs were greater than obstacle crossing costs. Children adopted a "task first" running strategy with different interference tasks. When facing cognitive tasks, their overall joint motion decreased, and they reduced joint motions to promote task completion. When facing obstacle crossing tasks, because of the characteristics of the task itself, children increased joint motions to cope with interference. (3) In terms of age, the running characteristics showed a nonlinear development trend in various indicators, with a degree of recurrence and high variability in adjacent age groups. (4) The dual-task interference paradigm of "postural-cognition" can be used as a motor intervention tool to promote the development of basic motor skills in early childhood. [ABSTRACT FROM AUTHOR]

In women, the laxity of the plantar fascia increases during the ovulation phase of the menstrual cycle. Although it is possible that this increased laxity results in a decreased height of the foot in the medial longitudinal arch and exacerbates symptoms of several overuse injuries of the lower extremity, the influence of the menstrual cycle on static and dynamic kinematics of the medial longitudinal arch is unclear. The purpose of this study was to confirm that the medial longitudinal arch height during static standing, gait, and landing decrease during the menstrual cycle ovulation phase. Participants in this study were 16 female college students with normal menstrual cycles and 16 male college students. Navicular height in the static standing position was measured using a three-dimensional foot scanner. Kinematics of the medial longitudinal arch during gait and landing were measured using a three-dimensional motion capture system to determine the navicular height at initial contact, minimal navicular height, and dynamic navicular drop. In all measurements, female participants were tested twice during the course of one complete menstrual cycle: once during the follicular phase and once during the ovulation phase. Male participants were tested twice with an interval of ≥1 week and <2 weeks. In women, navicular height in the static standing position significantly decreased during the ovulation phase compared with follicular phase (mean difference [95% confidence interval] = 2.1 [0.9–3.4] mm; p = 0.002), whereas men showed no statistical difference between the first and second measurements. In both men and women, no statistical differences were identified for the dynamic medial longitudinal arch kinematics measured during gait and landing. Navicular height in the static standing position slightly decreased during the ovulation phase. [ABSTRACT FROM AUTHOR]

Background: In young patients with irreparable subscapularis deficiency (SSC-D) and absence of severe osteoarthritis, anterior latissimus dorsi transfer (aLDT) has been proposed as a treatment option to restore the anteroposterior muscular force couple to regain sufficient shoulder function. However, evidence regarding the biomechanical effect of an aLDT on glenohumeral kinematics remains sparse. Purpose/Hypothesis: The purpose of this study was to investigate the effects of an aLDT on range of glenohumeral abduction motion, superior migration of the humeral head (SM), and cumulative deltoid force (cDF) in a simulated SSC-D model using a dynamic shoulder model. It was hypothesized that an aLDT would restore native shoulder kinematics by reestablishing the insufficient anteroposterior force couple. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric shoulders were tested using a validated shoulder simulator. Glenohumeral abduction angle (gAA), SM, and cDF were compared across 3 conditions: (1) native, (2) SSC-D, and (3) aLDT. gAA and SM were measured using 3-dimensional motion tracking, while cDF was recorded in real time during dynamic abduction motion by load cells connected to actuators. Results: The SSC-D significantly decreased gAA (Δ–9.8°; 95% CI, –14.1° to −5.5°; P <.001) and showed a significant increase in SM (Δ2.0 mm; 95% CI, 0.9 to 3.1 mm; P =.003), while cDF was similar (Δ7.8 N; 95% CI, –9.2 to 24.7 N; P =.586) when compared with the native state. Performing an aLDT resulted in a significantly increased gAA (Δ3.8°; 95% CI, 1.8° to 5.7°; P <.001), while cDF (Δ–36.1 N; 95% CI, –48.7 to −23.7 N; P <.001) was significantly reduced compared with the SSC-D. For the aLDT, no anterior subluxation was observed. However, the aLDT was not able to restore native gAA (Δ–6.1°; 95% CI, –8.9° to −3.2°; P <.001). Conclusion: In this cadaveric study, performing an aLDT for an irreparable subscapularis insufficiency restored the anteroposterior force couple and prevented superior and anterior humeral head migration, thus improving glenohumeral kinematics. Furthermore, compensatory deltoid forces were reduced by performing an aLDT. Clinical Relevance: Given the favorable effect of the aLDT on shoulder kinematics in this dynamic shoulder model, performing an aLDT may be considered as a treatment option in patients with irreparable SSC-D. [ABSTRACT FROM AUTHOR]

Just as vocalization proceeds in a continuous stream in speech, so too do movements of the hands, face, and body in sign languages. Here, we use motion-capture technology to distinguish lexical signs in sign language from other common types of expression in the signing stream. One type of expression is constructed action, the enactment of (aspects of) referents and events by (parts of) the body. Another is classifier constructions, the manual representation of analogue and gradient motions and locations simultaneously with specified referent morphemes. The term signing is commonly used for all of these, but we show that not all visual signals in sign languages are of the same type. In this study of Israeli Sign Language, we use motion capture to show that the motion of lexical signs differs significantly along several kinematic parameters from that of the two other modes of expression: constructed action and the classifier forms. In so doing, we show how motion-capture technology can help to define the universal linguistic category "word," and to distinguish it from the expressive gestural elements that are commonly found across sign languages. [ABSTRACT FROM AUTHOR]

Glossolalia can be regarded as an instance of speech production in which practitioners produce syllables in seemingly random sequences. However, a closer inspection of glossalalia's statistical properties reveals that sequences show a Zipfian pattern similar to natural languages, with some syllables being more probable than others. It is well established that statistical properties of sequences are implicitly learned, and that these statistical properties correlate with changes in kinematic and speech behavior. For speech, this means that more predictable items are phonetically shorter. Accordingly, we hypothesized for glossolalia that if practitioners have learned a serial pattern in glossolalia in the same manner as in natural languages, its statistical properties should correlate with its phonetic characteristics. Our hypothesis was supported. We find significantly shorter syllables associated with higher syllable probabilities in glossolalia. We discuss this finding in relation to theories about the sources of probability-related changes in the speech signal. [ABSTRACT FROM AUTHOR]

Self-propelled oscillating foils provide an effective model system to explore the intricacies of oscillatory and undulatory bio-locomotion, particularly the coupled thrust and drag mechanism that enable self-propulsion. Here, we explain the design, construction, and working of an experimental apparatus that can achieve self-propulsion. Our apparatus utilizes a long, freely rotating arm pivoted on one end and houses the airfoil on the other. The novelty of the apparatus is a spiral-spring-based crank rocker mechanism employed to provide the necessary sinusoidal actuation to the airfoil. We discuss the kinematics of a four-bar crank-rocker mechanism and identify the conditions under which the rocker motion can be approximated as sinusoidal. We describe the mechanism's design and construction with these kinematic constraints, test it under various loading conditions, and observe that it can produce sinusoidal actuation up to 20°. As a characterization, we use the apparatus to record the self-propulsion speed in two airfoil models – rigid (NACA0015) and hybrid (NACA0015 with flexible flap). Our results demonstrate high repeatability and less than a 2% error in all cases. The apparatus can attain self-propelling speeds ranging from 1 cm/s to almost 45 cm/s. Additionally, we explore potential applications for the mechanism, such as in large robotic fishes. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the utility and applicability of electrooculography (EOG) when studying ocular activity during complex motor behavior. Due to its lower spatial resolution relative to eye tracking (ET), it is unclear whether EOG can provide valid and accurate temporal measurements such as the duration of the Quiet Eye (QE), that is the uninterrupted dwell time on the visual target prior to and during action. However, because of its greater temporal resolution, EOG is better suited for temporal‐spectral decomposition, a technique that allows us to distinguish between lower and higher frequency activity as a function of time. Sixteen golfers of varying expertise (novices to experts) putted 60 balls to a 4‐m distant target on a flat surface while we recorded EOG, ET, performance accuracy, and putter kinematics. Correlational and discrepancy analyses confirmed that EOG yielded valid and accurate QE measurements, but only when using certain processing parameters. Nested cross‐validation indicated that, among a set of ET and EOG temporal and spectral oculomotor features, EOG power was the most useful when predicting performance accuracy through robust regression. Follow‐up cross‐validation and correlational analyses revealed that more accurate performance was preceded by diminished lower‐frequency activity immediately before movement initiation and elevated higher‐frequency activity during movement recorded from the horizontal channel. This higher‐frequency activity was also found to accompany a smoother movement execution. This study validates EOG algorithms (code provided) for measuring temporal parameters and presents a novel approach to extracting temporal and spectral oculomotor features during complex motor behavior. This study validates electrooculography for computing temporal indices of oculomotor activity typically obtained through mobile eye tracking. It also indicates that using EOG indices that embed both temporal and spectral features can improve predictions of movement accuracy compared to those that rely on temporal features only. [ABSTRACT FROM AUTHOR]

Purpose: Performance is the benchmark to assess the level of an athlete: in this respect, a more precise qualitative and quantitative evaluation of the performance represents an important target to be achieved. Methods: The work presents a possible method, based on the biomechanical evaluation of the motor exercise with an optoelectronic system, to characterise single or multiple repetitions of pull-ups of 12 athletes of sport climbing and sportive healthy subjects, monitoring and scoring the performance and the safety of the executions. The analysis includes the time courses of the segmental kinematics and some newly developed synthetic indices in the form of performance and safety scores. Results: The time courses make it possible to analyse the linear and angular kinematics district-by-district and have a direct overview of the ranges of motion, the patterns of task execution, together with the possible strategies adopted to complete the exercise in terms of compensations. The proposed characterisation provides a condensed summary of the global execution quality and offers the possibility to identify which single biomechanical parameters are modified. Conclusion: The method is intended as a practical tool to enrich the training schedule in terms of the qualitative and quantitative evaluation of the performances and to increase the self-awareness while training. [ABSTRACT FROM AUTHOR]

Purpose: Exercise intensity during walking can be increased by attaching an external load or accelerating the walking speed. However, the combination of these effects on the human body remains unclear. To investigate the influence of different walking speeds and ankle weight loads on metabolic and neuromuscular responses and lower limb kinematics during walking. Methods: Twelve healthy participants walked on a treadmill under eight conditions (speed: 4 and 7 km/h × ankle weight loads: 0, 2, 4, and 6 kg). We recorded V ˙ O 2 , heart rate (HR), lower limb neuromuscular activities, and kinematic data. Results: The interaction effect of speed and ankle weight load on V ˙ O 2 and HR was significant (p < 0.05). V ˙ O 2 and HR were higher during walking at 7 than 4 km/h (p < 0.05). V ˙ O 2 rapidly rose with an increase in ankle weight loading from 4 to 6 kg during walking at 7 km/h compared with that at 4 km/h (p < 0.05). Rectus femoris proximal activity with 6 kg ankle weight loading was higher than that under the no-loading condition during walking at 7 km/h (p < 0.05). During walking at 4 km/h, medial gastrocnemius muscle activity with 4- and 6 kg ankle weight loading was significantly higher than under the no-loading condition (p < 0.05). All targeted lower limb muscle activity and the maximum hip flexion angle were greater during walking at 7 than 4 km/h. Conclusion: Our results suggest that the effect of ankle weight loading on metabolic and neuromuscular responses is potentiated by a faster walking speed. [ABSTRACT FROM AUTHOR]

Purpose: Increasing access to marker-less technology has enabled practitioners to obtain kinematic data more quickly. However, the validation of many of these methods is lacking. Therefore, the validity of pre-trained neural networks was explored in this study compared to reflective marker tracking from sagittal plane cycling motion. Methods: Twenty-six cyclists were assessed during stationary cycling at self-selected cadence and moderate intensity exercise. Standard video from their sagittal plane was obtained to extract joint kinematics. Hip, knee, and ankle angles were calculated from marker digitisation and from two deep learning-based approaches (TransPose and MediaPipe). Results: Typical errors ranged between 1 and 10° for TransPose and 3–9° for MediaPipe. Correlations between joint angles calculated from TransPose and marker digitalization were stronger (0.47–0.98) than those from MediaPipe (0.25–0.96). Conclusion: TransPose seemed to perform better than MediaPipe but both methods presented poor performance when tracking the foot and ankle. This seems to be associated with the low frame rate and image resolution when using standard video mode. [ABSTRACT FROM AUTHOR]

This systematic review aimed to investigate the effect of focal vibration (FV) on muscle tone, kinematic parameters and motor functions in individuals with stroke, Parkinson' disease and multiple sclerosis. It also determined the influence of vibration parameters such as frequency and amplitude, stimulation session duration, and the total number of intervention sessions on the outcome measures. PubMed, Scopus, Cochrane, Web of Science, and EBSCO were searched, yielding 21 qualifying articles. Within a week post-treatment, FV effectively reduced elbow spasticity (P = 0.04), improved upper limb kinematic parameters (SMD = -0.75, 95% CI: -1.50 to -0.01), and enhanced upper limb motor function (P = 0.05) in stroke patients. FV significantly improved lower limb kinematic parameters of Parkinson's disease patients (P = 0.03). Over a week post-treatment, the effect of FV was not significant in reducing spasticity for upper limb in stroke (P = 0.25) and improving kinematic parameters for lower limb in Parkinson's disease (SMD = 0.38, 95% CI: -0.58 to 1.35). The total therapy sessions significantly associated with the effect size (p = 0.042) for upper limb motor function outcome measure. Conclusion, integrating FV into rehabilitation may benefit patients with neurological disorders such as stroke, Parkinson's disease, and multiple sclerosis. [ABSTRACT FROM AUTHOR]

Differences in running biomechanics have been reported in adult long-distance runners when running in motion control or neutral shoes. The influence of growth and coordination refinement during puberty limits the generalisability of adult research to adolescents and it is unknown if biomechanics differ between adolescent who run in different types of shoes. The purpose of our study was to compare lower extremity kinematics and ground reaction forces between adolescents running in motion control or neutral shoes. We matched 18 adolescent long-distance runners who ran in motion control shoes with 18 adolescent long-distance runners who ran in neutral shoes according to running speed, sex, and physical maturation. We collected three-dimensional kinematic and ground reaction force data during overground running and performed statistical parametric mapping to compare joint angle and ground reaction force waveforms between the motion control and neutral shoe groups. We found no significant differences for hip, knee, or ankle joint angles (average differences <2°) or ground reaction forces (average differences <0.05 N/kg) between runners who ran in motion control or neutral shoes. Lower extremity kinematics and ground reaction forces were similar between adolescents who ran in motion control or neutral shoes. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to evaluate patellar tendon loading profiles (loading index, based on loading peak, loading impulse, and loading rate) of rehabilitation exercises to develop clinical guidelines to incrementally increase the rate and magnitude of patellar tendon loading during rehabilitation. Methods: Twenty healthy adults (10 females/10 males, 25.9 ± 5.7 yr) performed 35 rehabilitation exercises, including different variations of squats, lunge, jumps, hops, landings, running, and sports specific tasks. Kinematic and kinetic data were collected, and a patellar tendon loading index was determined for each exercise using a weighted sum of loading peak, loading rate, and cumulative loading impulse. Then the exercises were ranked, according to the loading index, into tier 1 (loading index ≤0.33), tier 2 (0.33 < loading index <0.66), and tier 3 (loading index ≥0.66). Results: The single-leg decline squat showed the highest loading index (0.747). Other tier 3 exercises included single-leg forward hop (0.666), single-leg countermovement jump (0.711), and running cut (0.725). The Spanish squat was categorized as a tier 2 exercise (0.563), as was running (0.612), double-leg countermovement jump (0.610), single-leg drop vertical jump (0.599), single-leg full squat (0.580), double-leg drop vertical jump (0.563), lunge (0.471), double-leg full squat (0.428), single-leg 60° squat (0.411), and Bulgarian squat (0.406). Tier 1 exercises included 20 cm step up (0.187), 20 cm step down (0.288), 30 cm step up (0.321), and double-leg 60° squat (0.224). Conclusions: Three patellar tendon loading tiers were established based on a combination of loading peak, loading impulse, and loading rate. Clinicians may use these loading tiers as a guide to progressively increase patellar tendon loading during the rehabilitation of patients with patellar tendon disorders and after anterior cruciate ligament reconstruction using the bone–patellar tendon–bone graft. [ABSTRACT FROM AUTHOR]

Aberrant gait biomechanics in individuals with anterior cruciate ligament reconstruction (ACLR) are linked to posttraumatic osteoarthritis (PTOA) development, indicating a need to normalize gait biomechanics to prevent PTOA. Anterior cruciate ligament reconstruction individuals walk slower than uninjured controls and slower speeds are associated with aberrant gait biomechanics. Yet, it is unclear if increasing walking speed normalizes gait biomechanics post-ACLR. Purpose: To determine the effect of acutely increasing walking speed on gait biomechanics in ACLR individuals compared with their habitual speed and uninjured matched-controls. Methods: Gait biomechanics were collected on 30 ACLR individuals (20 females; age, 22.0 ± 4.2 yr; body mass index, 24.0 ± 3.0 kg·m−2) at their habitual speed and at 1.3 m·s−1, a speed similar to controls, and 30 uninjured matched-controls (age: 21.9 ± 3.8, body mass index: 23.6 ± 2.5) at their habitual speed. Functional waveform analyses compared biomechanics between: i) walking at habitual speed vs 1.3 m·s−1 in ACLR individuals; and ii) ACLR individuals at 1.3 m·s−1 vs controls. Results: In the ACLR group, there were no statistically significant biomechanical differences between walking at habitual speed (1.18 ± 0.12 m·s−1) and 1.3 m·s−1 (1.29 ± 0.05 m·s−1). Compared with controls (habitual speed: 1.34 ± 0.12 m·s−1), the ACLR group while walking at 1.3 m·s−1 exhibited smaller vertical ground reaction force (vGRF) during early and late stance (13–28, 78–90% stance phase), greater midstance vGRF (47–61%), smaller early-to-midstance knee flexion angle (KFA; 1–44%), greater mid-to-late stance KFA (68–73, 96–101%), greater internal knee abduction moment (69–101%), and smaller internal knee extension moment (4–51, 88–96%). Conclusions: Increasing walking speed to a speed similar to uninjured controls did not elicit significant changes to gait biomechanics, and ACLR individuals continued to demonstrate biomechanical profiles that are associated with PTOA development and differ from controls. [ABSTRACT FROM AUTHOR]

Objective: The aim of the study is to assess the effects of leg length discrepancy on paraspinal muscle activity and kinematic variables during gait. Design: Thirty-nine healthy participants aged 5–12 yrs performed the 10-m walk test using the surface electromyography and G-walk sensor for the following conditions: (1) non–leg length discrepancy condition (leg length discrepancy 0 cm) and (2) leg length discrepancy condition with an insole on the right leg at three different heights (leg length discrepancy 0.5 cm, 1.0 cm, and 1.5 cm). The root mean square was normalized using maximal voluntary contraction and reference voluntary contraction methods (RMS_MVC and RMS_ref) and compared between the sides. Results: The mean RMS_MVC of the 12th thoracic erector spinae on the right side was significantly higher at a leg length discrepancy 0.5 cm and 1 cm. Regarding the 3rd lumbar multifidus, the mean RMS_MVC on the right side was significantly higher at a leg length discrepancy 1.5 cm. The mean RMS_ref exhibited similar patterns. Pelvic obliquity and rotation showed asymmetry at a leg length discrepancy 1.5 cm compared with a leg length discrepancy 0 cm. Conclusions: A small leg length discrepancy significantly affected the asymmetric hyperactivation of the 3rd lumbar multifidus and 12th thoracic erector spinae muscles during gait. Considering the action of these muscles, asymmetric hyperactivation might result in rotation and bending of the lumbar spine and the bending of the thoracolumbar spine. [ABSTRACT FROM AUTHOR]

Waves and wave breaking are important to many deep and shallow water processes. We describe the wavedrifter, an in situ water-following inertial measurement unit (IMU)-based drifter that measures wave steepening and overturning kinematics, and the subsequent transition to turbulence. The wavedrifter has 5 cm diameter, 77 g mass, and 0.84 saltwater specific gravity. GPS provides time synchronization. MATLAB's Attitude, Heading, Reference System (AHRS) library provides wavedrifter orientation. Laboratory experiments quantify the wavedrifter vertical oscillation mode, water following properties, and ability to reproduce wave spectra for small, $f = 1.5$ f = 1.5 Hz waves. The wavedrifter observed wave overturning and the transition to turbulence at the Surf Ranch wave basin. Synchronized video observations provide context. The upper-back of the overturn had large ($ \approx 4g$ ≈ 4 g) accelerations and $14g$ 14 g acceleration magnitude occurs with the impact of the overturning jet. Trajectories reveal the Lagrangian structure of the overturn and subsurface vortex. Although it has limitations, the wavedrifter is a powerful in situ tool to probe wave processes. [ABSTRACT FROM AUTHOR]

The computation of master integrals from their differential equations requires boundary values to be supplied by an independent method. These boundary values are often desired at singular kinematical points. We demonstrate how the auxiliary mass flow technique can be extended to compute the expansion coefficients of master integrals in a singular limit in an analytical manner, thereby providing these boundary conditions. To illustrate the application of the method, we re-compute the phase space integrals relevant to initial-final antenna functions at NNLO, now including higher-order terms in their ϵ-expansion in view of their application in third-order QCD corrections. [ABSTRACT FROM AUTHOR]

In this work, we present a complete theoretical framework for analyzing the distribution of polarized hadrons within jets, with and without measuring the transverse momentum relative to the standard jet axis. Using soft-collinear effective theory (SCET), we derive the factorization and provide the theoretical calculation of both semi-inclusive and exclusive fragmenting jet functions (FJFs) under longitudinal and transverse polarization. With the polarized FJFs, one gains access to a variety of new observables that can be used for extracting both collinear and transverse momentum dependent parton distribution functions (PDFs) and fragmentation functions (FFs). As examples, we provide numerical results for the spin asymmetry A TU , T cos ϕ S − ϕ ̂ S h from polarized semi-inclusive hadron-in-jet production in polarized pp collisions at RHIC kinematics, where a transversely polarized quark would lead to the transverse spin of the final-state hadron inside the jet and is thus sensitive to the transversity fragmentation functions. Similarly, another spin asymmetry, A TU , L cos ϕ q − ϕ S from polarized exclusive hadron-in-jet production in polarized ep collisions at EIC kinematics would allow us to access the helicity fragmentation functions. These observables demonstrate promising potential in investigating transverse momentum dependent PDFs and FFs and are worthwhile for further measurements. [ABSTRACT FROM AUTHOR]

Maximal sprinting in humans requires the contribution of various muscle–tendon units (MTUs) and joints to maximize performance. The plantar flexor MTU and ankle joint are of particular importance due to their role in applying force to the ground. This narrative review examines the contribution of the ankle joint and plantar flexor MTUs across the phases of sprinting (start, acceleration, and maximum velocity), alongside the musculotendinous properties that contribute to improved plantar flexor MTU performance. For the sprint start, the rear leg ankle joint appears to be a particularly important contributor to sprint start performance, alongside the stretch–shortening cycle (SSC) action of the plantar flexor MTU. Comparing elite and sub-elite sprinters revealed that elite sprinters had a higher rate of force development (RFD) and normalized average horizontal block power, which was transferred via the ankle joint to the block. For the acceleration phase, the ankle joint and plantar flexor MTU appear to be the most critical of the major lower limb joints/MTUs. The contribution of the ankle joint to power generation and positive work is minimal during the first stance, but an increased contribution is observed during the second stance, mid-acceleration, and late-acceleration. In terms of muscular contributions, the gastrocnemius and soleus have distinct roles. The soleus acts mainly as a supporter, generating large portions of the upward impulse, whereas the gastrocnemius acts as both an accelerator and a supporter, contributing significantly to propulsive and upward impulses. During maximum velocity sprinting the ankle joint is a net dissipater of energy, potentially due to the greater vertical loading placed on the plantar flexors. However, the ankle joint is critical for energy transfer from proximal joints to ground force application to maintain velocity. In terms of the contribution of musculoskeletal factors to ankle joint and plantar flexor performance, an optimal plantar flexor MTU profile potentially exists, which is possibly a combination of several musculoskeletal factors, alongside factors such as footwear and technique. [ABSTRACT FROM AUTHOR]

PURPOSE: Unilateral cerebral palsy (UCP) represents about 30–40% of overall cerebral palsy diagnoses. Upper limb impairment has a significant negative impact on activities of daily living (ADL), and recent studies have shown that the use of virtual reality (VR) can increase motivation and promote an improvement in ADL. This preliminary study was aimed at exploring the acceptability and usability of a VR rehabilitation treatment, using the VITAMIN Platform, for children with UCP. A secondary goal of the study was to compare the results of usual standardized clinical scales and questionnaires with kinematic results as well as with the quantitative measures acquired by the VITAMIN platform in each exercise of the rehabilitation sessions. METHODS: Six children with UCP (aged 7–15) were recruited for a preliminary investigation in using a non-immersive VR system. The treatment was composed of 10 weekly sessions of 45 minutes. Each child played five types of exergames, using the impaired upper limb to hit virtual objects projected on a wide screen. Standardized clinical scales, kinematic analysis, and questionnaires were used to extensively assess upper limb function before and at the end of treatment. Five typically-developing children provided a reference for the instrumented kinematic assessment. RESULTS: At the end of the treatment, Melbourne Assessment 2 (MA2) scores increased for all the participants (mean increase in range of movement (ROM) + 19.1%, accuracy + 4.6%, dexterity + 13.1%, fluency + 10.3%). Shoulder flexion-extension ROM also improved (mean increase + 10.5°), and according to the kinematic analysis, shoulder movements became more similar to reference profiles. These results were confirmed by a general improvement in performing ADL, assessed by the ABILHAND-Kids questionnaire. Finally, a general agreement among the different measures and indexes emerged from the acquired data. CONCLUSION: The results show that VR treatment with the VITAMIN platform could be engaging and functional for rehabilitation of children with UCP. The good agreement among the qualitative and quantitative measures and indexes confirms the potential of such novel treatment. However, due to the limited sample size and small number of sessions, further and larger investigations are required to evaluate the effectiveness and to generalize the results. [ABSTRACT FROM AUTHOR]

PURPOSE: This study examined the effects of a dynamic neoprene orthosis on kinematic variables of gait in children with spastic bilateral cerebral palsy (CP). METHODS: Five children (whose median age was 9.6 years and who ranged in age from six to 12) with spastic bilateral CP and flexed knee at levels I-III of the Gross Motor Function Classification System were examined using kinematic gait analysis in three different conditions: 1) with dynamic neoprene orthosis; 2) without dynamic neoprene orthosis (immediate effect); and 3) without orthosis after six weeks of intervention. RESULTS: The comparison between condition one (with dynamic neoprene orthosis) and condition two (without dynamic neoprene orthosis) demonstrated the existence of improvements in minimum hip and knee flexion variables. Moreover, the results indicated that the improvements remained constant in several key gait variables after six weeks. CONCLUSION: The results varied from subject to subject, and there were signs of improvement in some of the subjects. Therefore, it was not possible to draw conclusions at a group level. Nonetheless, a number of individuals may benefit from this type of orthosis. [ABSTRACT FROM AUTHOR]

Background: Prior studies investigated selected discrete sagittal‐plane outcomes (e.g., peak knee flexion) in relation to running economy, hereby discarding the potential relevance of running technique parameters during noninvestigated phases of the gait cycle and in other movement planes. Purpose: Investigate which components of running technique distinguish groups of runners with better and poorer economy and higher and lower weekly running distance using an artificial neural network (ANN) approach with layer‐wise relevance propagation. Methods: Forty‐one participants (22 males and 19 females) ran at 2.78 m∙s−1 while three‐dimensional kinematics and gas exchange data were collected. Two groups were created that differed in running economy or weekly training distance. The three‐dimensional kinematic data were used as input to an ANN to predict group allocations. Layer‐wise relevance propagation was used to determine the relevance of three‐dimensional kinematics for group classification. Results: The ANN classified runners in the correct economy or distance group with accuracies of up to 62% and 71%, respectively. Knee, hip, and ankle flexion were most relevant to both classifications. Runners with poorer running economy showed higher knee flexion during swing, more hip flexion during early stance, and more ankle extension after toe‐off. Runners with higher running distance showed less trunk rotation during swing. Conclusion: The ANN accuracy was moderate when predicting whether runners had better, or poorer running economy, or had a higher or lower weekly training distance based on their running technique. The kinematic components that contributed the most to the classification may nevertheless inform future research and training. [ABSTRACT FROM AUTHOR]

We investigated the acute effects of caffeine supplementation (6 mg･kg−1) on 60‐m sprint performance and underlying components with a step‐to‐step ground reaction force measurement in 13 male sprinters. After the first round sprint as a control, caffeine supplementation‐induced improvement in 60‐m sprint times (7.811 s at the first versus 7.648 s at the second round, 2.05%) were greater compared with the placebo condition (7.769 s at the first versus 7.768 s at the second round, 0.02%). Using average values for every four steps, in the caffeine condition, higher running speed (all six step groups), higher step frequency (5th–16th and 21st–24th step groups), shorter support time (all the step groups except for 13th–16th step) and shorter braking time (9th–24th step groups) were found. Regarding ground reaction forces variables, greater braking mean force (13th–19th step group), propulsive mean force (1st–12th and 17th–20th step groups), and effective vertical mean force (9th–12th step group) were found in the caffeine condition. For the block clearance phase at the sprint start, push‐off and reaction times did not change, while higher total anteroposterior mean force, average horizontal external power, and ratio of force were found in the caffeine condition. These results indicate that, compared with placebo, acute caffeine supplementation improved sprint performance regardless of sprint sections during the entire acceleration phase from the start through increases in step frequency with decreases in support time. Moreover, acute caffeine supplementation promoted increases in the propulsive mean force, resulting in the improvement of sprint performance. [ABSTRACT FROM AUTHOR]

We construct the Schwarzschild dynamical models for 11 early-type galaxies with the SAURON and Mitchell stellar IFUs out to 2–4 R e, and construct dynamical models with combined stellar and H i kinematics for a subsample of four galaxies with H i velocity fields out to 10 R e obtained from the Westerbork Synthesis Radio Telescope, thus robustly obtaining the dark matter content out to large radii for these galaxies. Adopting a generalized-NFW dark matter profile, we measure an NFW-like density cusp in the dark matter inner slopes for all sample galaxies, with a mean value of 1.00 ± 0.04 (rms scatter 0.15). The mean dark matter fraction for the sample is 0.2 within 1 R e, and increases to 0.4 at 2 R e, and 0.6 at 5 R e. The dark matter fractions within 1 R e of these galaxies are systematically lower than the predictions of both the TNG-100 and EAGLE simulations. For the dark matter fractions within 2 R e and 5 R e, 40 and 70 per cent galaxies are 1σ consistent with either the TNG-100 or the EAGLE predictions, while the remaining 60 and 30 per cent galaxies lie below the 1σ region. Combined with 36 galaxies with dark matter fractions measured out to 5 R e in the literature, about 10 per cent of these 47 galaxies lie below the 3σ region of the TNG-100 or EAGLE predictions. [ABSTRACT FROM AUTHOR]

The warp is a well-known undulation of the Milky Way disc. Its structure has been widely studied, but only since Gaia DR2 has it been possible to reveal its kinematic signature beyond the solar neighbourhood. In this work, we present an analysis of the warp traced by Classical Cepheids by means of a Fourier decomposition of their height (Z) and, for the first time, of their vertical velocity (Vz). We find a clear but complex signal that in both variables reveals an asymmetrical warp. In Z , we find the warp to be almost symmetric in amplitude at the disc's outskirts, with the two extremes never being diametrically opposed at any radius and the line of nodes presenting a twist in the direction of stellar rotation for R > 11 kpc. For Vz , in addition to the usual m  = 1 mode, an m  = 2 mode is needed to represent the kinematic signal of the warp, reflecting its azimuthal asymmetry. The line of maximum vertical velocity is similarly twisted as the line of nodes and trails behind by ≈25°. We develop a new formalism to derive the pattern speed and change in amplitude with time |$\dot{A}$| of each Fourier mode at each radius, via a joint analysis of the Fourier decomposition in Z and Vz. By applying it to the Cepheids we find, for the m  = 1 mode, a constant pattern speed in the direction of stellar rotation of 9.2 ± 3.1 km s−1 kpc−1, a negligible |$\dot{A}$| up to R ≈ 14 kpc and a slight increase at larger radii, in agreement with previous works. [ABSTRACT FROM AUTHOR]

Geomorphological and sedimentological characteristics are key evidences for understanding the emplacement mechanisms of rock avalanches. Based on remote sensing, photogrammetry, and field surveys, the depositional characteristics of the Alasu rock avalanche (ARA) in southern Tianshan, China, were investigated in detail. It is reached that the ARA has a detached rock mass volume of ~ 93 × 106 m3 and propagated 3874 m on rugged terrain with a drop height of 1030 m. Large rock blocks (95,598 rock blocks with sizes ≥ 0.5 m) are widely distributed on the deposit surface. There is no decreasing trend in block size with travel distance for these rock blocks, while jigsaw and sibling structures of megablocks commonly occur in the carapace facies. The size and structural features of megablocks demonstrate that the carapace facies underwent a passive emplacement process with low degrees of fragmentation and disturbance. Furthermore, a series of surficial landforms, including irregular platforms, minor scarps, lateral levees, run-ups, ridges, and troughs, are preserved in the rock avalanche deposit. The most remarkable features are the large, subparallel, curved longitudinal ridges with continuous directional variations and three run-up traces. Extensions of these ridges indicate that the avalanche mass experienced a continuous extension-dominated process in emplacement due to its momentum transfer effect and high energy propagation. These observations and analyses may elucidate the emplacement mechanisms of rock avalanches in rugged landscapes. [ABSTRACT FROM AUTHOR]

This article presents the design and modeling of a new aerial manipulator system, called Q-PRR, composed of three joints with a fixed base in the center of mass of the multirotor considered as a whole system. This structure has a prismatic joint as a first joint which allows to keep the center of gravity of the Q-PRR as close as possible to the center of gravity of the multirotor. This will also allow to reduce the influence of arm motion on the multirotor roll thus to ensure the stability of the system on trajectory tracking with dynamic changes in the multirotor's center of gravity. Furthermore, the configuration of the manipulator arm for the desired position of the end-effector given by the inverse kinematics model is kept without any change in the position and attitude of the multirotor. This article develops both forward and inverse kinematics models for a nonlinear underactuated system using the Denavit–Hartenberg notation. When a new algorithm is presented for the inverse kinematics based on Levenberg–Marquardt algorithm. Then, the dynamic model in the joint spaces is developed with the Lagrangian formalism. The Q-PRR is controlled using a model-free control with a comparison of two states, a free fly and disturbance forces applied to the whole system with manipulator arm movement. [ABSTRACT FROM AUTHOR]

We tested twenty-one 6- to 10-month-old infants with a wide range of sitting experience in forward and rightward reaching during unsupported sitting on the floor. Sessions were video-recorded for further behavioral and machine learning-based kinematic analyses. All infants, including novice sitters, successfully touched and grasped toys in both directions. Infant falls, hand support, and base of support changes were rare. Infants with more sitting experience showed better upright posture than novice sitters. However, we found no differences in trunk displacement or reaching kinematics between directions or across sitting experience. Thus, multi-directional reaching is functional in both novice and experienced infant sitters. We suggest that trunk and arm stability in sagittal and frontal planes is integral to learning to sit. [ABSTRACT FROM AUTHOR]

Torsional stiffness of athletic footwear plays a crucial role in preventing injury and improving sports performance. Yet, there is a lack of research focused on the biomechanical effect of torsional stiffness in badminton shoes. This study aimed to comprehensively investigate the influence of three different levels of torsional stiffness in badminton shoes on biomechanical characteristics, sports performance, and injury risk in badminton players. Fifteen male players, aged 22.8 ± 1.96 years, participated in the study, performing badminton-specific tasks, including forehand clear stroke [left foot (FCL) and right foot (FCR)], 45-degree sidestep cutting (45C), and consecutive vertical jumps (CVJ). The tasks were conducted wearing badminton shoes of torsional stiffness measured with Shore D hardness 50, 60, and 70 (referred to as 50D, 60D, and 70D, respectively). The primary biomechanical parameters included ankle, knee, and MTP joint kinematics, ankle and knee joint moments, peak ground reaction forces, joint range of motion (ROM), and stance time. A one-way repeated measures ANOVA was employed for normally distributed data and Friedman tests for non-normally distributed data. The 70D shoe exhibited the highest ankle dorsiflexion and lowest ankle inversion peak angles during 45C task. The 60D shoe showed significantly lower knee abduction angle and coronal motions compared to the 50D and 70D shoes. Increased torsional stiffness reduced stance time in the FCR task. No significant differences were observed in anterior-posterior and medial-lateral ground reaction forces (GRF). However, the 70D shoe demonstrated higher vertical GRF than the 50D shoe while performing the FCR task, particularly during 70% - 75% of stance. Findings from this study revealed the significant role of torsional stiffness in reducing injury risk and optimizing performance during badminton tasks, indicating that shoes with an intermediate level of stiffness (60D) could provide a beneficial balance between flexibility and stability. These findings may provide practical references in guiding future badminton shoe research and development. Further research is necessary to explore the long-term effects of altering stiffness, considering factors such as athletic levels and foot morphology, to understand of the influence of torsional stiffness on motion biomechanics and injury prevalence in badminton-specific tasks. [ABSTRACT FROM AUTHOR]

Linear geo-textures are widely recognized on synthetic scaled images of planetary surfaces and consist of elongated alignments of tonal contrasts. When these linear patterns are clustered in azimuthal sets and organized in domains occurring on specific terranes, they reflect the structural grain of the crust and provide clues on the stress trajectories. In this way, the geostatistical analysis of lineament domains represents a useful tool to highlight the geotectonic settings of planetary surfaces. In this work, we applied a lineament domain analysis to better frame the tectonic evolution of the Claritas Fossae (CF) area on Mars, the origin of which is still debated, and both dip–slip and strike–slip tectonics have been described in the literature. A twofold approach was followed that included the identification of a linear pattern with manual and automatic approaches. The automatic method confirmed and validated the results of the manual detection. The statistical analysis of the identified lineaments showed their clustering in two domains that persisted on different terranes separated by the regionally sized scarp associated with the CF. This scarp is the surface manifestation of the CF crustal fault. The spatial distribution of the two domains and their constant angular relationship of about 30° allowed relating one domain to the main CF fault and the other domain to the extensional deformation associated with the fault kinematics. Our results suggest that the CF frames well within a regional setting characterized by right–lateral kinematics with about 20% transtension. Temporal constraints derive from the ages of the terrains where the two domains develop. On this basis, we propose that a first tectonic event occurred in the Noachian age followed by a reactivation occurring after the emplacement of the Late Hesperian lavas. [ABSTRACT FROM AUTHOR]

Background: Occlusal interferences lead to changes in mandibular kinematics to compensate and improve function. However, the effects of different types of eccentric disturbance on the comminution capacity are not known. Objective: To determine the immediate effect of eccentric occlusal interferences on masticatory performance. Methods: This crossover clinical trial included 12 healthy dentate subjects aged 25.2 ± 3.3 years who were randomly submitted to seven types of occlusal interference: unilateral and bilateral laterotrusive and mediotrusive, protrusive, dummy and control (no interference). The interference forms were planned in a semi‐adjustable articulator, fabricated with composite resin and adhered to the mandibular first molars such that subjects' maximum intercuspation was maintained. Masticatory performance and the chewing rate during 20 cycles were evaluated during subjects' comminution of silicone test food under one interference condition per test day; the multiple sieve method was applied to the comminuted particles. The interference was removed upon test completion, and a 1‐week washout period was applied between tests. Results: Comminuted median particle sizes were larger under unilateral (4.94 ± 0.41 mm) and bilateral (4.81 ± 0.49 mm) laterotrusive, bilateral mediotrusive (4.65 ± 0.50 mm) and protrusive (4.83 ± 0.54 mm) interferences (p <.05) than under the control (4.01 ± 0.52 mm) and dummy (4.18 ± 0.58 mm) conditions (p <.05). Only unilateral and bilateral laterotrusive interferences narrowed the comminuted particle size dispersion (p <.05). The chewing rate did not differ among conditions (p =.1944). Conclusion: Artificial eccentric interferences had an immediate adverse effect on masticatory performance by resulting in larger comminuted particles. Clinical trial registration: Brazilian Registry of Clinical Trials (RBR‐8g5zfg8). [ABSTRACT FROM AUTHOR]

Background: Excessive shoulder anterior force has been implicated in pathology of the rotator cuff in little league and professional baseball pitchers; in particular, anterior laxity, posterior stiffness, and glenohumeral joint impingement. Distinctly characterized motions associated with excessive shoulder anterior force remain poorly understood. Methods: High school and professional pitchers were instructed to throw fastballs while being evaluated with 3D motion capture (480 Hz). A supplementary random forest model was designed and implemented to identify the most important features for regressing to shoulder anterior force, with subsequent standardized regression coefficients to quantify directionality. Results: 130 high school pitchers (16.3 ± 1.2 yrs; 179.9 ± 7.7 cm; 74.5 ± 12.0 kg) and 322 professionals (21.9 ± 2.1 yrs; 189.7 ± 5.7 cm; 94.8 ± 9.5 kg) were included. Random forest models determined nearly all the variance for professional pitchers (R2 = 0.96), and less than half for high school pitchers (R2 = 0.41). Important predictors of shoulder anterior force in high school pitchers included: trunk flexion at maximum shoulder external rotation (MER) (X.IncMSE = 2.4, β = −0.23, p < 0.001), shoulder external rotation at ball release (BR)(X.IncMSE = 1.7, β = −0.34, p < 0.001), and shoulder abduction at BR (X.IncMSE = 3.1, β = 0.17, p < 0.001). In professional pitchers, shoulder horizontal adduction at foot contact (FC) was the highest predictor (X.IncMSE = 13.9, β = 0.50, p < 0.001), followed by shoulder external rotation at FC (X.IncMSE = 3.6, β = 0.26, p < 0.001), and maximum elbow extension velocity (X.IncMSE = 8.5, β = 0.19, p < 0.001). Conclusion: A random forest model successfully selected a subset of features that accounted for the majority of variance in shoulder anterior force for professional pitchers; however, less than half of the variance was accounted for in high school pitchers. Temporal and kinematic movements at the shoulder were prominent predictors of shoulder anterior force for both groups. Clinical relevance: : Our statistical model successfully identified a combination of features with the ability to adequately explain the majority of variance in anterior shoulder force among high school and professional pitchers. To minimize shoulder anterior force, high school pitchers should emphasize decreased shoulder abduction at BR, while professionals can decrease shoulder horizontal adduction at FC. [ABSTRACT FROM AUTHOR]

Belt-positioning booster (BPB) seats may prevent submarining in reclined child occupants in frontal impacts. BPB-seated child volunteers showed reduced lateral displacement in reclined seating in low-acceleration lateral-oblique impacts. As submarining was particularly evident in reclined small adult female occupants, we examined if a booster seat could provide similar effects on the kinematics of the small female occupant to the ones found on the reclined child volunteers in low-acceleration far-side lateral oblique impacts. The THOR-AV-5F was seated on a vehicle seat on a sled simulating a far-side lateral-oblique impact (80 deg from frontal, maximum acceleration ∼2 g, duration ∼170 ms). Lateral and forward head and trunk displacements, trunk rotation, knee-head distance, seatbelt loads, and head acceleration were recorded. Three seatback angles (25 deg, 45 deg, 60 deg) and two booster conditions were examined. Lateral peak head and trunk displacements decreased in more severe reclined seatback angles (25–36 mm decrease compared to nominal). Forward peak head, trunk displacements, and knee-head distance were greater with the seatback reclined and no BPB. Knee-head distance increased in the severe reclined angle also with the booster seat (>40 mm compared to nominal). Seat belt peak loads increased with increased recline angle with the booster, but not without the booster seat. Booster-like solutions may be beneficial for reclined small female adult occupants to reduce head and trunk displacements in far-side lateral-oblique impacts, and knee-head distance and motion variability in severe reclined seatback angles. [ABSTRACT FROM AUTHOR]

Head impacts in bicycle accidents are typically oblique to the impact surface and transmit both normal and tangential forces to the head, causing linear and rotational head kinematics, respectively. Traditional expanded polystyrene (EPS) foam bicycle helmets are effective at preventing many head injuries, especially skull fractures and severe traumatic brain injuries (TBIs) (primarily from normal contact forces). However, the incidence of concussion from collisions (primarily from rotational head motion) remains high, indicating need for enhanced protection. An elastomeric honeycomb helmet design is proposed herein as an alternative to EPS foam to improve TBI protection and be potentially reusable for multiple impacts, and tested using a twin-wire drop tower. Small-scale normal and oblique impact tests showed honeycomb had lower oblique strength than EPS foam, beneficial for diffuse TBI protection by permitting greater shear deformation and had the potential to be reusable. Honeycomb helmets were developed based on the geometry of an existing EPS foam helmet, prototypes were three-dimensional-printed with thermoplastic polyurethane and full-scale flat and oblique drop tests were performed. In flat impacts, honeycomb helmets resulted in a 34% higher peak linear acceleration and 7% lower head injury criteria (HIC15) than EPS foam helmets. In oblique tests, honeycomb helmets resulted in a 30% lower HIC15 and 40% lower peak rotational acceleration compared to EPS foam helmets. This new helmet design has the potential to reduce the risk of TBI in a bicycle accident, and as such, reduce its social and economic burden. Also, the honeycomb design showed potential to be effective for repetitive impact events without the need for replacement, offering benefits to consumers. [ABSTRACT FROM AUTHOR]

Background: The features of cerebral small vessel disease (CSVD) range from occurrence of asymptomatic radiological markers to symptomatic characteristics that include cognitive deficits and gait decline. The aim of the present study was to examine whether handwriting movement is abnormal in older people with CSVD through handwriting and drawing tasks using digitized handwriting kinematic assessment technology. Methods: Older subjects (n = 60) were grouped according to Fazekas score, with 16 in the Severe CSVD group, 12 in the Non-severe group and 32 in the Healthy group. Kinematic data were recorded and analyzed during handwriting and drawing tasks: signature; writing of Chinese characters ("正" and "永"); and Archimedes' spiral drawing. Results: The Severe CSVD group showed lower velocity and higher tortuosity during signature writing, lower velocity of stroke #4 of "正" and vertical size of "永" than did the Non-severe and Healthy groups. Both Severe CSVD and Non-severe CSVD subjects displayed higher average normalized jerk than did the Healthy group. Partial correlation analysis adjusting for age, gender, education, and mini-mental state evaluation (MMSE) showed that CSVD burden was positively associated with tortuosity of signature and average normalized jerk of Archimedes' spiral, and was negatively associated with velocity of strokes #3 and #4 of "正", as well as vertical size of "永". Conclusions: Older adults with CSVD showed abnormal handwriting movement. And the handwriting abnormalities captured by digitized handwriting analysis were correlated with CSVD severity in users of simplified Chinese characters. [ABSTRACT FROM AUTHOR]

This research aimed to measure lower extremity kinematics for male and female youths during daily activities and to identify gender differences from kinematics of lower limbs. A total of 87 healthy participants, comprising 43 Chinese male youths and 44 female youths, were recruited from Anhui Polytechnic University to participate in this research. All participants were instructed to perform squatting activities on a soft mat starting from an upright position. Every participant completed six squatting exercises, and motion capture technology was used to gather 3D kinematic data. SPSS software was used for statistical analysis. The average 3D angles of the hip, knee, and ankle joints of male and female youths were calculated, and then the independent t-test was used for statistical significance. Data analysis showed no significant gender differences in the sagittal movements of the knee and ankle joints for Chinese male and female youths. The mean hip joint angle during squatting was 1 2 2. 8 7 ∘ ± 2. 2 9 ∘ for male youths and 1 2 9. 0 6 ∘ ± 2. 6 3 ∘ for female youths. The knee joint angle was 1 3 1. 2 1 ∘ ± 2. 0 0 ∘ for male youths and 1 3 8. 7 9 ∘ ± 1. 9 4 ∘ for female youths. With regard to ankle mobility, the hip and ankle ranges of motion were 2 6. 7 3 ∘ and 1 0. 0 2 ∘ for male youths and 2 1. 2 8 ∘ and 9. 7 6 ∘ for female youths. Both sexes showed significant gender differences in the nonsagittal plane. The range of motion (ROM) observed during deep squatting exceeds the ROM after arthroplasty for Chinese male and female youths. These findings contribute to a comprehensive understanding of deep squatting biomechanics for the Chinese population and provide a basis for mitigating hyperflexion exercises and fabricating appropriate joint injury prostheses. By understanding the specific movement patterns of Chinese male and female youths, healthcare professionals can develop individualized interventions and rehabilitation programs to improve functional outcomes, prevent joint injuries, and improve the overall quality of life. The research found significant gender differences for sagittal hip and anterior ankle movements of male youths during squatting. These findings shed light on the kinematics of lower limbs. They have the potential to influence future research and medical practice to improve joint health and functional mobility for Chinese male and female youths. [ABSTRACT FROM AUTHOR]

To ensure the operation safety and efficiency of an autonomous rice transplanter, a path planning method of obstacle avoidance based on the improved artificial potential field is proposed. Firstly, the obstacles are divided into circular or elliptic obstacles according to the difference between the length and width of an obstacle as well as the angle between the vehicle's forward direction and the length direction of the obstacle. Secondly, improved repulsive fields for circular and elliptic models are developed. To escape the local minimum and goal inaccessibility of the traditional artificial potential field as well as meet the requirements of agronomy and vehicle kinematics constraints, the adaptive setting and adjusting strategy for virtual goal points is proposed according to relative azimuth between obstacle and vehicle. The path smoothing method based on the B-spline interpolation method is presented. Finally, the intelligent obstacle avoidance algorithm is designed, and the path evaluation rule is given to obtain the low-cost, non-collision, smooth and shortest obstacle avoidance path. To verify the effectiveness of the proposed obstacle avoidance algorithm, simulation and field experiments are conducted. Simulation and experimental results demonstrate that the proposed improved collision avoidance algorithm is highly effective and realizable. [ABSTRACT FROM AUTHOR]

The relative motion between the workpiece and the fixed abrasive pad (FAP) determines the abrasive trajectories and the distribution of abrasives' sliding distance (ASD), and further affects the surface accuracy of the lapping process. To improve the surface accuracy of the swinging fixed abrasive plane lapping (SFAPL), the influence of the workpiece's swinging modes on the lapping uniformity was studied in this paper. The kinematics model of SFAPL was established by the coordinate transformation method based on the kinematical principle of the crank-rocker mechanism. The numerical simulation method was adopted to investigate the abrasive trajectories and the ASD on the workpiece surface in different swinging modes. Furthermore, the regional meshing and statistical methods were applied to visualize the simulation results, and the non-uniformity coefficient (NUC) and root mean square (rms) were employed to quantitatively evaluate the lapping uniformity. Finally, the verification experiments were carried out. Results indicated that the additional swinging could avoid the periodic distribution of material removal on the workpiece surface. The swinging mode significantly affected the lapping efficiency and lapping uniformity. Compared with the traditional lapping method, the lapping uniformity was optimal when the workpiece swung out of the FAP from the bottom and inner sides, and the lapping uniformity could be improved by 44.3 %; The lapping efficiency was the highest when the workpiece swung out of the FAP from the bottom side, and the material removal rate could be increased by 45.23 %. The appropriate swinging mode should be selected based on different processing requirements in SFAPL. [Display omitted] • Swinging fixed abrasive plane lapping (SFAPL) was introduced to improve the lapping accuracy of BK7 glass. • The lapping uniformity of SFAPL was investigated through kinematics and trajectory analysis. • Simulation results were visualized based on regional meshing and statistical methods. • The influence of swinging modes on the lapping performance was revealed. • The optimal swinging mode to ameliorate the lapping uniformity was determined. [ABSTRACT FROM AUTHOR]