Kinematic Asymmetries Research Articles

Kinematic asymmetry of galaxy pairs

AbstractThe interaction between galaxies is believed to be the main origin of the peculiarities of galaxies. It can disturb not only the morphology but also the kinematics of galaxies. These disturbed and asymmetric features are the indicators of galaxy interaction. We study the velocity field of ionized gas in galaxy pairs based on MaNGA survey. Using the kinemetry package, we fit the velocity field and quantify the degree of kinematic asymmetry. We find that the fraction of high kinematic asymmetry is much higher for galaxy pairs with dp⩽30h−1kpc. Moreover, compared to a control sample of single galaxies, we find that the star formation rate is enhanced in paired galaxies with high kinematic asymmetry. For paired galaxies with low kinematic asymmetry, no significant SFR enhancement has been found. The galaxy pairs with high kinematic asymmetry are more likely to be real interacting galaxies rather than projected pairs.

Lower Extremity Kinetic and Kinematic Asymmetries 4, 6, and 9 Months Post-ACL Reconstruction In Elite Collegiate Athletes

Abnormal lower extremity (LE) biomechanics post-anterior cruciate ligament reconstruction (ACLR) may increase re-injury risk and reduce sports performance. Although most athletes return to sport (RTS) within 1 year from ACLR, the timeline for recovery of LE kinetics and kinematics during athletic tasks is not well defined. Identifying specific movement deficiencies will guide rehabilitation efforts to promote successful RTS and reduce re-injury risk. PURPOSE: To evaluate vertical ground reaction forces (vGRF) and hip, knee, and ankle kinematics during running and jumping in elite collegiate athletes 4, 6, and 9 months post-ACLR. METHODS: Twelve Division I athletes (age 20.5 ± 1.2, BMI 25.9 ± 3.6, 6 female) performed maximal countermovement jumps (CMJ) and treadmill running at a maximally comfortable speed 4.0 ± 0.3, 6.1 ± 0.5 and 8.9 ± 1.5 months post-surgery while whole body kinematics were recorded. VGRF impulses, knee flexion excursion, and peak sagittal plane hip, knee, and ankle joint angles were obtained during the stance phase of running (RUN) and the eccentric, concentric (CON), and landing (LAND) phases of the CMJ. Limb symmetry indices (LSI) were computed for all variables and effect sizes (ES) were calculated. LSIs at each interval were evaluated using the Wilcoxon Signed-Ranks test. RESULTS: At 4 months post-surgery, all CMJ and RUN asymmetries were significant (LSI: 69.5-95.9%, p < .023, ES: .46-.62). Involved limb CMJ CONC phase and RUN vGRF impulses were significantly less than uninvolved limb values at all intervals (LSI: 85.7-94.2%, p < .005, ES: .58-.63). RUN peak joint angle and knee flexion excursion asymmetries were significant at all intervals (LSI: 69.5-94.7%, p < .013, ES: .51-.62). Involved limb CMJ CONC phase knee (LSI: 90.6-98.6%, p < .041, ES: .42-.62) and ankle (LSI: 80.2-86.1%, p < .010, ES: .53-.62) angles were reduced throughout, while no CMJ LAND phase asymmetries were detected 9 months post-op. CONCLUSIONS: Despite excellent surgical care and high volumes of rehabilitation, elite collegiate athletes present with LE kinetic and kinematic asymmetries 9 months post-surgery, after or close to typical RTS. In particular, knee joint kinematics during the stance phase of running and the CONC phase of the CMJ are categorically asymmetric and should be addressed with targeted interventions.

Women’s Collegiate Volleyball Players Exhibit Kinetic Asymmetries during Sport-Specific Tasks

Women’s volleyball demands frequent lateral movements and vertical jumps. Repetitive lateral movements in the same direction could lead to biomechanical asymmetries and a potential increased risk of lower extremity injury. PURPOSE:To identify and analyze biomechanical asymmetries in collegiate women’s volleyball players during sport-specific lateral and vertical jumping tasks. METHODS: Nineteen female collegiate volleyball players were analyzed using standard 3D motion capture techniques during a drop vertical jump (DVJ) from a 30-cm box and a reactive jump (REACT) task. For the REACT, participants began in an athletic stance awaiting a directional cue on a screen placed in front of them. Once directed, participants were instructed to jump laterally and then vertically as high and fast as possible to mimic a volleyball block. Repeated measures MANOVA models were used to identify asymmetries in kinematic and kinetic measures in the DVJ and REACT task (α=0.05). Paired t-tests identified asymmetries in reaction time during the REACT task. Limb symmetry indices (LSI) were calculated for significant findings. RESULTS:Significant kinetic asymmetries were identified for both the DVJ (p=0.01) and REACT (p=0.003) tasks, but no kinematic asymmetries were found in either task (p>0.05). During the DVJ, participants exhibited asymmetrical knee abduction (LSI=81%, p=0.03), ankle dorsiflexion (LSI=94%, p=0.03), and ankle inversion (LSI=30%, p=0.001) external joint moments and vertical ground reaction forces (LSI=93%, p=0.04). During the REACT task, participants exhibited asymmetrical ankle dorsiflexion (LSI=85%, p=0.03), and ankle inversion (LSI=73%, p=0.001) external joint moments. There were no differences in reaction times between the two limbs (p>0.05). CONCLUSIONS:Collegiate women’s volleyball players exhibit significant asymmetry in the knee and ankle during jumping and landing tasks. Interestingly, asymmetries were identified in kinetic variables but not kinematic variables. These findings indicate that screening, injury prevention and rehabilitation practices cannot solely rely on visual observation to identify lower extremity asymmetry in this athletic population.

The SAMI Galaxy Survey: Bayesian inference for gas disc kinematics using a hierarchical Gaussian mixture model

Abstract We present a novel Bayesian method, referred to as blobby3d, to infer gas kinematics that mitigates the effects of beam smearing for observations using integral field spectroscopy. The method is robust for regularly rotating galaxies despite substructure in the gas distribution. Modelling the gas substructure within the disc is achieved by using a hierarchical Gaussian mixture model. To account for beam smearing effects, we construct a modelled cube that is then convolved per wavelength slice by the seeing, before calculating the likelihood function. We show that our method can model complex gas substructure including clumps and spiral arms. We also show that kinematic asymmetries can be observed after beam smearing for regularly rotating galaxies with asymmetries only introduced in the spatial distribution of the gas. We present findings for our method applied to a sample of 20 star-forming galaxies from the SAMI Galaxy Survey. We estimate the global H α gas velocity dispersion for our sample to be in the range $\bar{\sigma }_v \sim$[7, 30] km s−1. The relative difference between our approach and estimates using the single Gaussian component fits per spaxel is $\Delta \bar{\sigma }_v / \bar{\sigma }_v = - 0.29 \pm 0.18$ for the H α flux-weighted mean velocity dispersion.

Asymmetry in healthy adult knee kinematics revealed through biplane radiography of the full gait cycle.

One commonly used criterion in evaluating a patients' response to knee surgery or rehabilitation is bilateral symmetry. However, the natural symmetry in uninjured healthy adult knee kinematics remains relatively unknown, making it challenging to determine if clinical treatment has adequately restored bilateral symmetry. The primary purpose of this study was to determine the typical side-to-side differences in 6 degree of freedom (DOF) knee kinematics over the entire gait cycle in healthy adults using biplane radiography. Six DOF tibiofemoral kinematics were measured during treadmill walking in 19 participants using a validated volumetric model-based tracking process that matched subject-specific bone models to biplane radiographs collected at 100 images/s. Average absolute side-to-side differences in knee kinematics at foot strike were 1.3 mm or less in translation and 3.8° or less in rotation. Peak side-to-side differences in knee kinematics occurred during the swing phase and were up to 2.2 mm in translation and 7.1° in rotation. Dominant versus non-dominant leg differences were 0.8 mm and 2.8° or less at foot strike and reached maximum values of 0.8 mm and 7.2° over the full gait cycle. Statement of Clinical Significance: This study quantifies the inherent asymmetry of knee kinematics in healthy individuals over the entire gait cycle. The values of asymmetry presented here may serve as a guide for evaluating functional outcomes and restoration of so-called "normal" kinematics after injury and clinical intervention. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Search for CP violation with kinematic asymmetries in the D0→K+K−π+π− decay

We search for $CP$ violation in the singly-Cabibbo-suppressed decay $D^{0}\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}$ using data corresponding to an integrated luminosity of $988\text{ }{\rm fb}^{-1}$ collected by the Belle detector at the KEKB $e^{+}e^{-}$ collider. We measure a set of five kinematically dependent $CP$ asymmetries, of which four asymmetries are measured for the first time. The set of asymmetry measurements can be sensitive to $CP$ violation via interference between the different partial-wave contributions to the decay and performed on other pseudoscalar decays. We find no evidence of $CP$ violation.

Evaluating movement performance: What you see isn’t necessarily what you get

With the goal of reducing injury and enhancing performance, movement screening tools score an individual’s movements against a standard and because it is a predictor of injury symmetry is often included in the score. Movement quality screening tools only consider kinematic asymmetry, which may underestimate the degree of asymmetry present during movement. Consider joint forces: if these forces are atypical, additional stress is created and control is reduced, which can lead to injury if the asymmetry is not addressed. The purpose of this study is to investigate movement symmetry in the kinematic, kinetic and muscle activity components of movement during a parallel squat.Thirty-four healthy individuals completed five body-weight, parallel squats. A motion capture system, two portable force plates, and electromyography (EMG) sensors recorded the squat motion, ground reaction forces and muscle activity. The variables of interest were the joint angles, joint moments, and EMG waveforms. Cross-correlations and normalized root-mean-square values were calculated for the left and right ankles, knees, and hips for each variable. A repeated-measures analysis of variance (ANOVA) tested for differences in symmetry (cross-correlation and nRMS) between the kinematic, kinetic, and muscle activity components at the ankle, knee, and hip during the squat.At all joints the kinematic component had the highest degree of symmetry, and the kinetic and muscle activity components showed poorer symmetry, with the muscle activity component being the least symmetric. The differences in symmetry between movement components suggests that movement performance evaluations should not rely exclusively on kinematics and observation to identify potential movement faults.

Symmetric Versus Asymmetric Pitching of a Cycloidal Rotor Blade at Ultra-Low Reynolds Numbers

This paper provides a fundamental understanding of the unsteady aerodynamic phenomena on a cycloidal rotor blade operating with symmetric as well as asymmetric pitching at ultralow Reynolds numbers () by using a combination of experimental (force and flowfield measurements) and computational fluid dynamics (CFD) studies. The instantaneous blade fluid dynamic forces on a rotating cycloidal rotor blade were measured, which, along with particle image velocimetry (PIV) based flowfield measurements revealed the key fluid dynamic mechanisms acting on the blade. A two-dimensional CFD analysis of the cycloidal rotor was developed and systematically validated using both force and flowfield measurements. The CFD flow solution and PIV-measured flowfield correlated well, especially in the upper half of the circular blade trajectory, and both showed the formation and shedding of strong dynamic stall or leading-edge vortices at high pitch amplitudes, which is the reason for the stall delay and force enhancement. The dynamic virtual camber induced by the flow curvature decreased the blade lift in the upper half due to negative induced camber; however, the lift increased in the lower half due to positive camber. Therefore, introducing an asymmetry in pitch kinematics with higher pitch in the upper half and lower pitch in the bottom half counteracted this inherent lift asymmetry and improved efficiency through a more uniform lift production.

Influence of Center of Gravity Location on Flight Dynamic Stability in a Hovering Tailless FW-MAV: Longitudinal Motion

This paper reports the effect of the Center of Gravity (CG) position on lateral flight dynamic stability of hovering KUBeetle, a tailless FW-MAV, providing further insights on the effects of asymmetries in body mass distribution and wing kinematics. For the current study, the standard linearized equations of motion were applied as in the previous work on longitudinal dynamic stability. The stability derivatives were acquired using the computational fluid dynamic methods via the commercial software of ANSYS Fluent. There exists a stable region for CG between 2.6% and 3.5% of the mean chord below the wing pivot point, in which the lateral motion of hovering KUBeetle is passively stable. For CG below the stable region, because of an unstable oscillatory mode, the lateral motion of the FW-MAV is unstable but can be stabilized using rolling rate feedback. For CG above the stable region, because of a divergence mode, the system remains unstable even with the rolling rate feedback. Comparison with other works on an FW-MAV based on a quasi-steady aerodynamic model and on insect showed similar characteristics for flapping flight. It is also interesting to note that the asymmetries in body mass and wing kinematics can enlarge the stable region of the system by a non-zero Ixz which approaches the root square of √IxI2, a negative LrNp, and a positive Ixz(Ir+Np). Combining the current result with that of the previous work on longitudinal motion, the most beneficial region of the CG for full 6-DOF flight dynamic stability of hovering KUBeetle was suggested.

Sculpting Andromeda – made-to-measure models for M31’s bar and composite bulge: dynamics, stellar and dark matter mass

The Andromeda galaxy (M31) contains a box/peanut bulge (BPB) entangled with a classical bulge (CB) requiring a triaxial modelling to determine the dynamics, stellar and dark matter mass. We construct made-to-measure models fitting new VIRUS-W IFU bulge stellar kinematic observations, the IRAC-3.6$\mu$m photometry, and the disc's HI rotation curve. We explore the parameter space for the 3.6$\mu$m mass-to-light ratio $(\Upsilon_{3.6})$, the bar pattern speed ($\Omega_p$), and the dark matter mass in the composite bulge ($M^B_{DM}$) within 3.2kpc. Considering Einasto dark matter profiles, we find the best models for $\Upsilon_{3.6}=0.72\pm0.02\,M_\odot/L_\odot$, $M^B_{DM}=1.2^{+0.2}_{-0.4}\times10^{10}M_\odot$ and $\Omega_p=40\pm5\,km/s/kpc$. These models have a dynamical bulge mass of $M_{dyn}^B=4.25^{+0.10}_{-0.29}\times10^{10}M_{\odot}$ including a stellar mass of $M^B=3.09^{+0.10}_{-0.12}\times10^{10}M_\odot$(73%), of which the CB has $M^{CB}=1.18^{+0.06}_{-0.07}\times10^{10}M_\odot$(28%) and the BPB $M^{BPB}=1.91\pm0.06\times10^{10}M_\odot$(45%). We also explore models with NFW haloes finding that, while the Einasto models better fit the stellar kinematics, the obtained parameters agree within the errors. The $M^B_{DM}$ values agree with adiabatically contracted cosmological NFW haloes with M31's virial mass and radius. The best model has two bulge components with completely different kinematics that only together successfully reproduce the observations ($\mu_{3.6},\upsilon_{los},\sigma_{los},h3,h4$). The modelling includes dust absorption which reproduces the observed kinematic asymmetries. Our results provide new constraints for the early formation of M31 given the lower mass found for the classical bulge and the shallow dark matter profile, as well as the secular evolution of M31 implied by the bar and its resonant interactions with the classical bulge, stellar halo and disc.

Asymmetric expansion of the Fe ejecta in Kepler’s supernova remnant

Abstract The ejecta kinematics of supernova remnants (SNRs) is one of the crucial clues to understanding the explosion mechanism of type Ia supernovae (SNe). In particular, the kinematic asymmetry of iron-peak elements provides the key to understanding the physical processes taking place in the core of the exploding white dwarfs (WDs), although it has been poorly understood by observations. In this paper, we show for the first time the asymmetric expansion structure in the line-of-sight direction of Fe ejecta in Kepler’s SNR revealed by spectral and imaging analysis using the Chandra archival data. We found that the Kα line centroid energy and line width is relatively lower (&amp;lt;6.4 keV) and narrower (∼80 eV) around the center of the remnant, which implies that the majority of the Fe ejecta in the central region is redshifted. At the outer regions, we identify bright blueshifted structures as have been ejected as high-velocity dense clumps. Taking into account the broad population of the Fe charge states, we estimate the redshifted velocity of ∼2000 km s−1 and the blueshifted velocity of ∼3000 km s−1 for each velocity structure. We also present the possibility that a portion of the Fe ejecta near the center are interacting with the dense circumstellar medium (CSM) on the near side of the remnant. For the origin of the asymmetric motion of the Fe ejecta, we suggest three scenarios; (1) the asymmetric distribution of the CSM, (2) the “shadow” in Fe cast by the companion star, and (3) the asymmetric explosion.

Psychological Readiness to Return to Sport Is Associated With Knee Kinematic Asymmetry During Gait Following Anterior Cruciate Ligament Reconstruction

Gait asymmetry is frequently observed following anterior cruciate ligament reconstruction (ACLR). Psychological readiness to return to sport is associated with functional and activity-related outcomes after ACLR. However, the association between gait asymmetry and psychological readiness to return to sport is unknown. To determine the relationship between kinematic and kinetic measures of knee symmetry during gait and psychological readiness to return to sport following ACLR. In this controlled laboratory, cross-sectional study, 79 athletes (39 women) underwent gait analysis following impairment resolution after ACLR (ie, full range of motion, minimal or no effusion, quadriceps strength index of 80% or greater). Interlimb differences during gait were calculated for sagittal plane knee angles at initial contact, peak knee flexion, and peak knee extension, as well as for peak knee flexion moment and peak knee adduction moment. Athletes completed the Anterior Cruciate Ligament-Return to Sport after Injury scale (ACL-RSI) to assess psychological readiness to return to sport. Pearson correlations were used to examine the association between ACL-RSI score and each gait symmetry variable. Significant negative correlations were observed between the ACL-RSI and 2 kinematic variables: knee flexion angle at initial contact (r = -0.281, P = .012) and peak knee flexion (r = -0.248, P = .027). In general, lower scores on the ACL-RSI were associated with greater interlimb asymmetry. There was a weak association between psychological readiness to return to sport and knee kinematic asymmetry during gait. J Orthop Sports Phys Ther 2018;48(12):968-973. Epub 27 Jul 2018. doi:10.2519/jospt.2018.8084.

The effect of a novel gait retraining device on lower limb kinematics and muscle activation in healthy adults

The Re-Link Trainer (RLT) is a modified walking frame with a linkage system designed to apply a non-individualized kinematic constraint to normalize gait trajectory of the left limb. The premise behind the RLT is that a user’s lower limb is constrained into a physiologically normal gait pattern, ideally generating symmetry across gait cycle parameters and kinematics. This pilot study investigated adaptations in the natural gait pattern of healthy adults when using the RLT compared to normal overground walking. Bilateral lower limb kinematic and electromyography data were collected while participants walked overground at a self-selected speed, followed by walking in the RLT. A series of 2-way analyses of variance examined between-limb and between-condition differences. Peak hip extension and knee flexion were reduced bilaterally when walking in the RLT. Left peak hip extension occurred earlier in the gait cycle when using the RLT, but later for the right limb. Peak hip flexion was significantly increased and occurred earlier for the constrained limb, while peak plantarflexion was significantly reduced. Peak knee flexion and plantarflexion in the right limb occurred later when using the RLT. Significant bilateral reductions in peak electromyography amplitude were evident when walking in the RLT, along with a significant shift in when peak muscle activity was occurring. These findings suggest that the RLT does impose a significant constraint, but generates asymmetries in lower limb kinematics and muscle activity patterns. The large interindividual variation suggests users may utilize differing motor strategies to adapt their gait pattern to the imposed constraint.

Numerical prediction of slamming on bow-flared section considering geometrical and kinematic asymmetry

Asymmetric impacting phenomenon is quite common for the sailing ship when it encounters oblique waves. The asymmetrical water entry problem of a full scale bow-flared section from Ultra Large Container Ship (ULCS) was investigated using CFD method in commercial code FLUENT. A two-phase flow model was established based on N-S equations, which were discretized through the finite volume method and the free surface was captured by VOF model. The body motion was achieved in the dynamic mesh model with prescribed dynamic boundary condition. The impacting forces were obtained through direct numerical integration on the body surface. The validation and convergence were carried out through comparing experimental data and other numerical methods in already published literature. Two kinds of asymmetry, heel angle as geometrical asymmetry and horizontal velocity as the kinematic asymmetry, were comprehensively considered in numerical simulation and significant attention is given into the discussion of their effects on impacting hydrodynamics including pile-up water, pressure and slamming forces. The results show the geometrical asymmetry is important on these hydrodynamics if the flow separation does not happen. Otherwise, the kinematic asymmetry can significantly influence pile-up water form and further determines the pressure and slamming forces.

Pelvic excursion during walking post-stroke: A novel classification system

BackgroundResearchers and clinicians often use gait speed to classify hemiparetic gait dysfunction because it offers clinical predictive capacity. However, gait speed fails to distinguish unique biomechanical characteristics that differentiate aspects of gait dysfunction. Research questionHere we describe a novel classification of hemiparetic gait dysfunction based on biomechanical traits of pelvic excursion. We hypothesize that individuals with greater deviation of pelvic excursion, relative to controls, demonstrate greater impairment in key gait characteristics. MethodsWe compared 41 participants (61.0 ± 11.2yrs) with chronic post-stroke hemiparesis to 21 non-disabled controls (55.8 ± 9.0yrs). Participants walked on an instrumented split-belt treadmill at self-selected walking speed. Pelvic excursion was quantified as the peak-to-peak magnitude of pelvic motion in three orthogonal planes (i.e., tilt, rotation, and obliquity). Raw values of pelvic excursion were compared against the distribution of control data to establish deviation scores which were assigned bilaterally for the three planes producing six values per individual. Deviation scores were then summed to produce a composite pelvic deviation score. Based on composite scores, participants were allocated to one of three categories of hemiparetic gait dysfunction with progressively increasing pelvic excursion deviation relative to controls: Type I (n = 15) – minimal pelvic excursion deviation; Type II (n = 20) – moderate pelvic excursion deviation; and Type III (n = 6) – marked pelvic excursion deviation. We assessed resulting groups for asymmetry in key gait parameters including: kinematics, joint powers temporally linked to the stance-to-swing transition, and timing of lower extremity muscle activity. ResultsAll groups post-stroke walked at similar self-selected speeds; however, classification based on pelvic excursion deviation revealed progressive asymmetry in gait kinematics, kinetics and temporal patterns of muscle activity. SignificanceThe progressive asymmetry revealed in multiple gait characteristics suggests exaggerated pelvic motion contributes to gait dysfunction post-stroke.

Kinematics of ventrally mediated grasp-to-eat actions: right-hand advantage is dependent on dorsal stream input.

Studies have suggested a left-hemisphere specialization for visually guided grasp-to-eat actions by way of task-dependent kinematic asymmetries (i.e., smaller maximum grip apertures for right-handed grasp-to-eat movements than for right-handed grasp-to-place movements or left-handed movements of either type). It is unknown, however, whether this left-hemisphere/right-hand kinematic advantage is reliant on the dorsal "vision-for-action" visual stream. The present study investigates the kinematic differences between grasp-to-eat and grasp-to place actions performance during closed-loop (i.e., dorsally mediated) and open-loop delay (i.e., ventrally mediated) conditions. Twenty-one right-handed adult participants were asked to reach to grasp small food items to (1) eat them, or (2) place them in a container below the mouth. Grasps were performed in both closed-loop and open-loop delay conditions, in separate sessions. We show that participants displayed the right-hand grasp-to-eat kinematic advantage in the closed-loop condition, but not in the open-loop delay condition. As no task-dependent kinematic differences were found in ventrally mediated grasps, we posit that the left-hemisphere/right-hand advantage is dependent on dorsal stream processing.

Scapular kinematics during scaption in competitive swimmers

This study aimed (1) to describe and compare scapular kinematics between three groups of swimmers of different levels and a group of non-swimmers, and (2) to assess whether swimming practice alters the asymmetries in scapular kinematics between the dominant and non-dominant sides, both during unilateral arm raising and lowering in the scapular plane. Scapular kinematics were assessed bilaterally during arm raising and lowering in the scapular plane using an electromagnetic system in 42 healthy males, which were split into four groups: control (n = 11), adolescent elite swimmers (n = 11), adult elite swimmers (n = 10), and club-level adult swimmers (n = 10). One-Way ANOVA SPM(t) on two repeated measures showed that the three groups of swimmers had more protracted shoulder between 30° and 90° of arm raising and lowering (p < .001). The three groups of swimmers presented no bilateral difference in scapular upward rotation, while the dominant scapula was more upwardly rotated than the non-dominant one between 74° and 104° of arm elevation in the control group (p < .001). The scapula of adult elite swimmers was more internally rotated between 67° and 116° of humeral elevation during arm raising, and between 81° and 54° during arm lowering in comparison to the other swimming and control groups (p ≤ .02), who presented similar scapular positioning in internal rotation. In conclusion, the findings of the study pointed out that swimming practice generated protracted shoulders and removed bilateral differences in scapular upward rotation during scaption, while accumulation of swimming practice at elite level enlarged scapular internal rotation.

Gait symmetry and hip strength in women with developmental dysplasia following hip arthroplasty compared to healthy subjects: A cross-sectional study

IntroductionUntreated unilateral developmental dysplasia of the hip (DDH) results in asymmetry of gait and hip strength and may lead to early osteoarthritis, which is commonly treated with a total hip arthroplasty (THA). There is limited knowledge about the obtained symmetry of gait and hip strength after the THA. The objectives of this cross-sectional study were to: a) identify asymmetries between the operated and non-operated side in kinematics, kinetics and hip strength, b) analyze if increased walking speed changed the level of asymmetry in patients c) compare these results with those of healthy subjects.MethodsWomen (18–70 year) with unilateral DDH who had undergone unilateral THA were eligible for inclusion. Vicon gait analysis system was used to collect frontal and sagittal plane kinematic and kinetic parameters of the hip joint, pelvis and trunk during walking at comfortable walking speed and increased walking speed. Furthermore, hip abductor and extensor muscle strength was measured.ResultsSix patients and eight healthy subjects were included. In the patients, modest asymmetries in lower limb kinematics and kinetics were present during gait, but trunk lateral flexion asymmetry was evident. Patients’ trunk lateral flexion also differed compared to healthy subjects. Walking speed did not significantly influence the level of asymmetry. The hip abduction strength asymmetry of 23% was not statistically significant, but the muscle strength of both sides were significantly weaker than those of healthy subjects.ConclusionsIn patients with a DDH treated with an IBG THA modest asymmetries in gait kinematics and kinetics were present, with the exception of a substantial asymmetry of the trunk lateral flexion. Increased walking speed did not result in increased asymmetries in gait kinematics and kinetics. Hip muscle strength was symmetrical in patients, but significantly weaker than in healthy subjects. Trunk kinematics should be included as an outcome measure to assess the biomechanical benefits of the THA surgery after DDH.

The SAMI Galaxy Survey: gas content and interaction as the drivers of kinematic asymmetry

In order to determine the causes of kinematic asymmetry in the H$\alpha$ gas in the SAMI Galaxy Survey sample, we investigate the comparative influences of environment and intrinsic properties of galaxies on perturbation. We use spatially resolved H$\alpha$ velocity fields from the SAMI Galaxy Survey to quantify kinematic asymmetry ($\overline{v_{asym}}$) in nearby galaxies and environmental and stellar mass data from the GAMA survey. {We find that local environment, measured as distance to nearest neighbour, is inversely correlated with kinematic asymmetry for galaxies with $\mathrm{\log(M_*/M_\odot)}>10.0$, but there is no significant correlation for galaxies with $\mathrm{\log(M_*/M_\odot)}<10.0$. Moreover, low mass galaxies ($\mathrm{\log(M_*/M_\odot)}<9.0$) have greater kinematic asymmetry at all separations, suggesting a different physical source of asymmetry is important in low mass galaxies.} We propose that secular effects derived from gas fraction and gas mass may be the primary causes of asymmetry in low mass galaxies. High gas fraction is linked to high $\frac{\sigma_{m}}{V}$ (where $\sigma_m$ is H$\alpha$ velocity dispersion and $V$ the rotation velocity), which is strongly correlated with $\overline{v_{asym}}$, and galaxies with $\log(M_*/M_\odot)<9.0$ have offset $\overline{\frac{\sigma_{m}}{V}}$ from the rest of the sample. Further, asymmetry as a fraction of dispersion decreases for galaxies with $\log(M_*/M_\odot)<9.0$. Gas mass and asymmetry are also inversely correlated in our sample. We propose that low gas masses in dwarf galaxies may lead to asymmetric distribution of gas clouds, leading to increased relative turbulence.

Spatiotemporal analysis of 3D kinematic asymmetry in professional cycling during an incremental test to exhaustion

ABSTRACTThis study investigated the influence of an incremental exercise on bilateral asymmetry through the spatio-temporal evolution of 3D joint angular displacement, using the Normalized Symmetry Index () and cross-correlation methods. Twelve professional cyclists performed an incremental test to exhaustion, during which motion capture was used. Results revealed a decrease in range of motion between the first and last stages for twelve of the eighteen joint rotations, with the highest impact observed for right hip flexion/extension (61.8 ± 4.7° to 58.8 ± 4.1°, p < 0.05, ES = 0.68). For both stages, significant bilateral differences greater than 10° were observed for hip and knee flexion/extension (p < 0.05, ES>0.90) and ankle and hip internal/external rotation (p < 0.05, ES>0.25). Cross-correlation displayed the lowest pattern similarities for hip abduction/adduction and the highest similarities for knee flexion/extension, ankle plantarflexion/dorsiflexion and hip internal/external rotation. The cross-correlation method showed that the right leg was mostly ahead of time with respect to the left leg, a trend that was accentuated with power output increase. Instantaneous fluctuated up to 18% throughout the pedalling cycle, with different behaviour between the power and recovery phases. This study demonstrated the workload effects on side-to-side joint angular pattern similarity.