Measure Of Symmetry Research Articles

Accurate measurement and enhancement of fiber coil symmetry.

The pure Shupe effect is substantially reduced in a fiber optic gyroscope (FOG) with symmetrical windings. However, the effect of the temperature-induced nonuniformity of the stress in the coil depends on the mean temperature derivative (T-dot). Research on precision winding technology has discovered that the symmetry of optical fiber rings affects the temperature performance of fiber optic gyroscopes. Optical fiber rings with good symmetry also have good temperature performance. This paper first establishes a temperature drift model of optical fiber rings that includes the Shupe effect and T-dot effect and then uses finite element simulation to analyze the drift error of optical fiber rings in a variable temperature environment. Analysis shows that this drift is caused by the variation and uneven distribution of the fiber length and the refractive index in the positive and negative winding of the optical fiber ring, which results in a residual phase difference that is directly related to the symmetry of the optical fiber ring. Simulation and analysis show that balancing the residual phase difference of the optical fiber ring can be achieved by cutting the length of the optical fiber ring at both ends. This paper uses optical frequency domain reflectometry (OFDR) technology to precisely test the symmetry of the optical fiber ring, ensuring accurate adjustment of the lengths at both ends of the optical fiber ring. Experimental tests on two gyroscopes have shown that the optical fiber ring with a smaller drift error can be obtained after testing and adjusting its length. The experimental data indicates that the bias stability of two laboratory gyros are increased by 23.6% and 18.1%, and the bias range are reduced by 22.4% and 30.0%.

A Framework for Detection of Exact Global and Partial Symmetry in 3D CAD Models

The most common way to retrieve symmetry information (i.e., the planes and axes of symmetry) in 3D CAD models is through visual recognition by engineers. However, engineers are not able to visually recognize exact symmetry in any CAD model, and their ability to recognize symmetry decreases as the number of CAD models increases. To overcome these limitations, computer-aided symmetry detection is employed, which enables the (semi)automatic extraction of the symmetry information in CAD models. Hence, the present paper introduces a symmetry detection framework for 3D CAD models with boundary representation. The novelty of this research was that it addressed the detection of exact and partial axi- and reflectional symmetry in CAD models with analytic and numeric surfaces. Further, symmetry measures were proposed to differentiate exact, partial, or non-symmetry in the CAD model. The framework was implemented into a state-of-the-art CAD system and subjected to performance and time complexity validation. The results showed that the implemented framework’s performance was 0.94 F1-score, and the time complexity was linear with respect to the number of faces in the CAD model. Hence, it was concluded that the framework is suitable for industrial applications to support engineers in symmetry detection.

49. Assessing the Benefit of Adding Cross-facial Nerve Grafts to a Masseteric to Facial Nerve Transfer for Smile and Periorbital Reanimation in Subacute Facial Palsy

PURPOSE: Comparing long-term outcomes of nerve to masseter (NTM) to facial nerve (FN) transfer with and without cross-facial nerve graft (CFNG). METHODS: Patients with subacute facial palsy who received a NTM to FN transfer with or without a CFNG from 2013-2020 were reviewed. One year minimal follow up was required. Outcomes measures based on professional standardized photos of patients in repose, closed, and open smile were analyzed pre-operatively, at 3-months, 1-year, 3-years, and 5-years postoperatively as available. Emotrics software (Massachusetts Eye and Ear Infirmary, Boston, MA) and ImageJ (Rasband, W.S., ImageJ, U.S, National Institutes of Health, Bethesda, MD) were used for all measurements. Between group and within group longitudinal comparisons at each timepoint were analyzed using Wilcoxon Two-Sample Testing. RESULTS: Preoperative midface smile parameters were similar between groups (NTM=7, NTM+CFNG=17). At one-year (NTM=6, NTM+CFNG=17), closed mouth smile modiolus angle in NTM+CFNG was increased (NTM=96.135 degrees, NTM+CFNG=105.953 degrees, p=0.019). At 3-year (NTM=4, NTM+CFNG=16), open mouth modiolus angle in NTM+CFNG was increased (NTM=102.929mm, NTM+CFNG=115.269mm, p=0.0206). Midface smile parameters were similar between the groups at 5-year follow up. Preoperative periorbital symmetry measurements in repose were similar between groups. At one-year, marginal reflex distance 1 in NTM+CFNG was decreased (NTM=1.312mm, NTM+CFNG=0.587mm, p=0.025). At three-year, there were significant differences in marginal reflex distance 1 (NTM=1.728mm, NTM+CFNG=0.417mm, p=0.0264) and marginal reflex distance 2 (NTM=0.603mm, NTM+CFNG=0.632mm, p=0.0071). Symmetry measurements were similar at the 5-year point. CONCLUSION: There was long-term improvement in resting periorbital symmetry with the addition of a CFNG. Midface smile showed no consistent long-term improvement.

Functional septorhinoplasty alters brain structure and function: Neuroanatomical correlates of olfactory dysfunction.

We previously demonstrated functionally significant structural plasticity within the central olfactory networks, in association with improved olfaction after surgical treatment of chronic rhinosinusitis (CRS). In order to confirm and expand on these findings, the primary aim of this study was to determine whether these same regions undergo functionally significant structural plasticity following functional septorhinoplasty (fSRP), in patients with non-CRS olfactory dysfunction (OD) of mixed cause. fSRP has previously been shown to improve olfactory function, and the secondary aim of this study was to provide initial insights into the mechanism by which fSRP affects olfaction. We performed a pilot prospective, multimodal neuroimaging study in 20 participants undergoing fSRP, including patients with non-CRS OD of mixed cause, as well as normosmic surgical controls. Participants underwent psychophysical olfactory testing, assessment of nasal airway, structural and functional neuroimaging. This was performed pre- and postoperatively in patients, and preoperatively in controls. There was a statistically and clinically significant improvement in mean psychophysical olfactory scores after surgery. This was associated with structural and functional plasticity within areas of the central olfactory network (anterior cingulate, orbitofrontal cortex, insula, temporal pole). Improved psychophysical scores were significantly correlated with change in bilateral measures of nasal airflow, not measures of airflow symmetry, suggesting that improved overall airflow was more important than correction of septal deviation. This work highlights the importance of these neuroanatomical regions as potential structural correlates of olfactory function and dysfunction. Our results also provide initial insight into the mechanistic effects of fSRP on olfaction. Further work could investigate the utility of these regions as personalised biomarkers of OD, as well as the role of fSRP in treating OD.

Prevalence of vertical movement asymmetries at trot in Standardbred and Swedish Warmblood foals.

Many horses, just before and during their athletic career, show vertical movement asymmetries, to the same degree as clinically lame horses. It is unknown whether these asymmetries are caused by pain or have alternative explanations, such as inherent biological variation. In the latter case, movement asymmetries would be expected to be present at a very young age. This study aimed to investigate the prevalence of movement asymmetries in foals. Motion analysis, using an inertial measurement unit-based system (Equinosis), was performed on 54 foals (31 Swedish Warmbloods, 23 Standardbreds) during straight-line trot. The foals were between 4-13 weeks old and considered sound by their owners. Differences between the vertical minimum and maximum values recorded for the head (HDmin, HDmax) and pelvis (PDmin, PDmax) between left and right stance were calculated for each stride and an average was computed for each trial. Thresholds for asymmetry were defined as absolute trial mean >6 mm for HDmin and HDmax, and >3 mm for PDmin and PDmax. These thresholds were exceeded for one or several parameters by 83% of Standardbred foals and 45% of Swedish Warmblood foals, demonstrating surprisingly high prevalence of asymmetries in young foals, although the risk of repetitive strain injuries and cumulative risk of trauma injuries was expected to be low in this age group. Standardbred foals showed similar prevalence of asymmetries to that reported previously for yearling Standardbred trotters, so relatively higher prevalence of movement asymmetries may be expected among trotters as a breed. In general, vertical head and pelvic movement asymmetries can be anticipated among foals considered sound by their owners. A better understanding of the aetiology of asymmetries is needed for correct interpretation of objective symmetry measurements in different populations of horses.

One-dimensional pseudoharmonic oscillator: classical remarks and quantum-information theory

Motion along semi-infinite straight line in a potential that is a combination of positive quadratic and inverse quadratic functions of the position is considered with the emphasis on the analysis of its quantum-information properties. Classical measure of symmetry of the potential is proposed and its dependence on the particle energy and the factor describing a relative strength of its constituents is described; in particular, it is shown that a variation of the parameter alters the shape from the half-harmonic oscillator (HHO) at to the perfectly symmetric one of the double frequency oscillator (DFO) in the limit of huge . Quantum consideration focuses on the analysis of information-theoretical measures, such as standard deviations, Shannon, Rényi and Tsallis entropies together with Fisher information, Onicescu energy and non–Gaussianity. For doing this, among others, a method of calculating momentum waveforms is proposed that results in their analytic expressions in form of the confluent hypergeometric functions. Increasing parameter modifies the measures in such a way that they gradually transform into those corresponding to the DFO what, in particular, means that the lowest orbital saturates Heisenberg, Shannon, Rényi and Tsallis uncertainty relations with the corresponding position and momentum non–Gaussianities turning to zero. A simple expression is derived of the orbital-independent lower threshold of the semi-infinite range of the dimensionless Rényi/Tsallis coefficient where momentum components of these one-parameter entropies exist which shows that it varies between 1/4 at HHO and zero when tends to infinity. Physical interpretation of obtained mathematical results is provided.

Abstract WP39: Subhairline Electroencephalography For Detection Of Large Vessel Occlusion Stroke

Introduction: Endovascular thrombectomy (EVT) for large vessel occlusion stroke of the anterior circulation (LVO-a) can only be performed in selected hospitals. A prehospital triage instrument with which paramedics can reliably identify patients with an LVO-a stroke would enable direct routing of these patients to the right hospital and would consequently improve patient outcome. Electroencephalography (EEG) has previously shown to discriminate between patients with and without an LVO-a stroke. In this study, the diagnostic accuracy of subhairline EEG for LVO-a stroke was evaluated. Methods: A 3-minute EEG recording was performed in 35 patients who were presented to the emergency room with a suspected stroke or known LVO-a stroke, as soon as possible after presentation, and prior to potential EVT. Recordings were performed using 9 self-adhesive electrodes placed on the forehead and behind the ears. We evaluated the diagnostic accuracies of EEG features quantifying frequency band power (relative delta, theta, alpha and lower beta powers and power ratios), brain symmetry (pairwise derived Brain Symmetry Index [pdBSI]) and connectivity (Magnitude Squared Coherence [MSC] and Weighted Phase Lag Index) for LVO-a stroke using receiver operating characteristic analysis. Optimal cut-off points were determined as the maximum sensitivity at a specificity of ≥ 80% for LVO-a stroke. Results: Median age was 75 (IQR 67-81) years and 20/35 (57%) patients were male. 13/35 (37%) patients had an LVO-a stroke, 12/35 (34%) a non-LVO-a ischemic stroke, 4/35 (11%) a transient ischemic attack and 6/35 (17%) a stroke mimic. Median onset-to-EEG-time was 250 (IQR 118-535) minutes. Recordings of all patients were of sufficient quality to calculate frequency band power and brain symmetry measures. The connectivity measures could not be calculated for 3 LVO-a stroke patients. The highest diagnostic accuracy for LVO-a stroke was reached by the MSC in the delta frequency band (AUC 0.80; sensitivity 80%; specificity 82%) and the pdBSI in the theta frequency band (AUC 0.78; sensitivity 77%; specificity 82%). Conclusions: Subhairline EEG is a promising instrument for detection of LVO-a stroke, but validation in a larger study population and in the prehospital setting is necessary.

Asymmetry as an indicator of stress: From population statistics to clinical life-saving applications

Most symmetrical objects can be efficiently described in terms of their deviation from a specific symmetry group, whether it be a mirror, radial, or translatory symmetry, among other groups. Fundamentally, asymmetry is an individual trait, but the asymmetry distribution of a given population may provide valuable information about the well-being of that population. Quantification of these deviations from perfect symmetry evolved from counts and linear measures of distances to landmarks conducive to structures with consistent topology, and then to Continuous Symmetry Measures (CSM) conducive to structures with no consistent topology. We demonstrate the usefulness of this approach on quantification of leaf veins that mirror bifurcating structures. Deviations from a given symmetry group can be described in terms of (i) Fluctuating Asymmetries (FA) or (ii) broken asymmetries. Fluctuating Asymmetry (FA) is a controversial indicator of stress, and therefore tackling the problem needs a large number of species and populations in habitats with well-known stressors. We found such a site at “Evolution Canyon”, Israel, and we examine and discuss a study of twenty-four species that live in the canyon’s opposing slopes. We conclude with examples from asymmetry as a neurophysiological bioindicator by presenting several studies on Amyotrophic Lateral Sclerosis (ALS), Parkinson’s disease, and stroke. We show how machine-learning methods, applied on asymmetry indicators (in addition to the traditional signal processing features), can improve the sensitivity of the system and provide reliable diagnostic results.

Can the continuous symmetry measure TPR6 measure the axial magnetic anisotropy in hexacoordinated Co(ii) SIMs?

A nice correlation between the experimental axial magnetic anisotropy D values and TPR6 continuous symmetry measures (R ∼ 0.90) for a set of 64 mononuclear Co(ii) compounds with SIM properties was established and analyzed.

Obesity Is Associated With Gait Alterations and Gait Asymmetry in Older Adults.

The prevalence of obesity (OB) has increased in the older adult (OA) population. However, it is not quite clear whether OB exaggerates gait instability and leads to a higher risk of falls in OAs. The first goal of this study was to investigate whether OB is associated with gait alterations and gait asymmetry in OAs. The second goal of this study was to examine relationships between various OB measures with gait measures and gait symmetry measures in OAs. A total of 30 OAs were included and categorized according to their body mass index (BMI) values into groups of persons with normal weight (NW), overweight (OW), and OB. Participants were required to complete an anthropometric assessment, a body composition assessment, and overground walking tests. The group with OB had shorter swing phase, longer stance phase, and shorter single support phase than the NW group. Increased body weight, BMI, visceral adipose tissue mass, and android fat had correlations with shorter swing phase, longer stance phase, and shorter single support phase. Increased body weight and BMI had significantly positive correlations with symmetry index of knee range of motion. OB may impair gait automation capacity in OAs. Both body weight and BMI remain good measures in terms of establishing correlations with gait stability in OAs. However, the amount of fat mass surrounding the abdomen could be vital to interpreting the alterations in the gait of OAs with obesity.

GlottisNetV2: Temporal Glottal Midline Detection Using Deep Convolutional Neural Networks.

High-speed videoendoscopy is a major tool for quantitative laryngology. Glottis segmentation and glottal midline detection are crucial for computing vocal fold-specific, quantitative parameters. However, fully automated solutions show limited clinical applicability. Especially unbiased glottal midline detection remains a challenging problem. We developed a multitask deep neural network for glottis segmentation and glottal midline detection. We used techniques from pose estimation to estimate the anterior and posterior points in endoscopy images. Neural networks were set up in TensorFlow/Keras and trained and evaluated with the BAGLS dataset. We found that a dual decoder deep neural network termed GlottisNetV2 outperforms the previously proposed GlottisNet in terms of MAPE on the test dataset (1.85% to 6.3%) while converging faster. Using various hyperparameter tunings, we allow fast and directed training. Using temporal variant data on an additional data set designed for this task, we can improve the median prediction accuracy from 2.1% to 1.76% when using 12 consecutive frames and additional temporal filtering. We found that temporal glottal midline detection using a dual decoder architecture together with keypoint estimation allows accurate midline prediction. We show that our proposed architecture allows stable and reliable glottal midline predictions ready for clinical use and analysis of symmetry measures.

Association of Dosimetric Parameters and Boost Volume with Quantitative Cosmetic Outcomes in a Randomized Trial of Conventionally Fractionated vs. Hypofractionated Whole Breast Irradiation

<h3>Purpose/Objective(s)</h3> Whole breast irradiation (WBI) is the most common treatment in radiation oncology, yet there is a relative paucity of evidence delineating the relationship between dosimetric parameters and long-term outcomes. We conducted a prospective randomized trial with longitudinal follow up to compare two different WBI dosing schedules and sought to evaluate the association of dosimetric parameters and boost volume with long term cosmetic outcomes using novel, previously validated, quantitative metrics of breast cosmesis derived from 2-dimensional photographs. <h3>Materials/Methods</h3> A prospective randomized trial of patients with early breast cancer who were randomly assigned to conventionally fractionated or hypofractionated WBI plus boost was conducted from 2011-14. Anteroposterior photographs from the low-neck to umbilicus were obtained at baseline, 6 months, and yearly through 5 years. Fiducial points marking each nipple and inframammary fold were delineated on each photograph and used to calculate a measure of nipple symmetry (M1) and breast vertical symmetry (M2), as previously described (PMID 28333010). These values range from 0 to 1 with values closer to 1 indicating better symmetry. Multivariable logistic regression longitudinal models with M1 and M2 as outcomes, dichotomized at the median, evaluated associations of dosimetric parameters and boost volume with M1 and M2 adjusting for relevant clinical, demographic and treatment variables. Candidate dosimetric variables included volume of tissue encompassed by the 90% isodose line (PTV), tumor bed volume, volume encompassed by the 105% isodose line, maximum point dose in the breast (Dmax), central axis separation, percent dose delivered with 18 MV photons, boost energy, boost position, boost modality, and cross-sectional area of the boost field. <h3>Results</h3> Of the 287 patients included in this trial, 149 patients received CF-WBI and 138 received HF-WBI, with median follow up 48 months. Median age was 60 years. Median PTV was 1340cc (IQR 904-1760), median tumor bed volume was 23cc (IQR 13-43), and median boost field size was 64cm² (IQR 54-80). 50% of patients had a Dmax of ≥107% of the prescription dose. A total of 1600 photographs were annotated to calculate M1 and M2. In multivariable analysis, highest quartile of PTV (OR 0.40, P=0.002) and boost field size (OR 0.50, P=0.02) were associated with worse M1 outcome compared to the lowest quartile. Highest quartile of tumor bed volume was associated with worse M2 compared to the lowest quartile (OR 0.52, P=0.03). <h3>Conclusion</h3> Utilizing previously validated quantitative measures of cosmetic outcome derived from 2D photographs, we found that boost fields with cross-sectional area <54 cm² and PTV <1760cc were associated with better nipple symmetry, and tumor bed volume >43cc was associated with worse vertical breast symmetry. Understanding how dosimetric parameters and boost volume affect long-term cosmetic outcomes can facilitate optimization of breast radiation treatment plans.

Association of Treatment Arm with Quantitative Cosmetic Outcome in a Randomized Trial Comparing Whole Breast Irradiation Dosing Schedules

<h3>Purpose/Objective(s)</h3> We have previously validated that two measures of breast symmetry derived from an anteroposterior photograph, termed M1 and M2, correlate with patient- and physician-reported cosmetic outcome and offer an opportunity to quantitate breast cosmesis without relying on subjective human assessment. Within the context of a prospective randomized trial comparing two dosing schedules for whole breast irradiation (WBI) (50 Gy/25fx+10-14 Gy/5-7fx boost [CF-WBI] versus 42.56 Gy/16fx+10-12.5 Gy/4-5fx boost [HF-WBI]), we evaluated the impact of treatment arm on M1 and M2 through five years follow up. <h3>Materials/Methods</h3> 2D AP photographs framed from the mid-neck to umbilicus were obtained at baseline, 6 months, and yearly through 5 years on a prospective randomized trial of 287 patients with early breast cancer who were randomly assigned to CF-WBI+boost or HF-WBI+boost. For each photograph, we marked the coordinates of each nipple and inframammary fold and used these values to calculate M1 and M2 as per prior methods (PMID 28333010). M1 and M2 range from 0 to 1 with higher values indicating better nipple symmetry (M1) or vertical breast symmetry (M2). Multivariable logistic regression longitudinal models were created with M1 and M2 as outcomes, dichotomized at the median, to evaluate associations of treatment arm with M1 and M2 adjusting for relevant clinical, demographic, and treatment variables. <h3>Results</h3> A total of 287 patients were enrolled on this trial (n=149 allocated to CF-WBI; n=138 to HF-WBI) with median follow up 48 months. Median age was 60 years with 11% Black and 13% Hispanic and 44% obese. A total of 1600 photographs were acquired and marked to calculate M1 and M2. At five-years follow up, M1 was 0.92 for CF-WBI and 0.91 for HF-WBI (P=0.55) and M2 was 0.63 for CF-WBI and 0.66 for HF-WBI (P=0.40). In multivariable longitudinal analysis, treatment arm was not correlated with either M1 (OR 0.76; P=0.16) or M2 (OR 1.19; P=0.39). In contrast, obesity was associated with worse M1 (OR 0.50; P=0.003) and worse M2 (OR 0.58; P=0.03) and age≥70 years was associated with worse M2 (OR 0.39; P=0.02). <h3>Conclusion</h3> This is one of the first randomized trials to use an objective, quantitative approach to measure breast cosmesis and compare outcomes by treatment arm. We found that cosmesis as assessed via M1 and M2 was similar by treatment arm, providing high quality evidence supporting cosmetic equivalence of CF-WBI and HF-WBI. Future breast cancer radiation trials could adopt this approach to compare different radiation regimens.

Reconstruction of Dentomaxillofacial Deformity Secondary to Mandibular Defect Using Concomitant Orthognathic Surgery and Fibula Free Flap.

The reconstruction of mandibular defects may be delayed or compromised for many reasons, especially in pediatric patients. With the growth of the remaining mandible and the maxilla in the malocclusion status, secondary dentomaxillofacial deformity is plausible. To treat the concomitant mandibular defect and secondary dentomaxillofacial deformity, a hierarchical algorithm using orthodontics, orthognathic surgery, and fibula free flap was developed. This retrospective case series included six patients with long-term mandibular defects caused by tumor resection without repair or with compromised costochondral reconstruction. All patients were treated using the same staged protocol, but with minor changes: (1) presurgical orthodontics, (2) virtual surgical planning, (3) fabrication of the guides and splints, (4) sequenced operations, and (5) postoperative care. The sequence of surgery included the Le Fort I osteotomy, mandibular sagittal split ramus osteotomy of the remaining ramus, final occlusion registration, repositioning of the distal segment of the mandible, segmented fibula reconstruction, and finally, the fixation of mandibular sagittal split ramus osteotomy. The operations and wound healing were uneventful in all patients, and no flap failure or severe complications were detected. Also, the patients exhibited no signs of temporomandibular joint ankylosis during the follow-up. The subspinale-nasion-supramental angle was significantly reduced after surgery. A significant improvement was detected in the facial contour symmetry measurements postoperatively. This proposed workflow of concomitant orthognathic surgery and the fibula free flap is effective and reliable for the reconstruction of dentomaxillofacial deformity secondary to the long-term mandibular defect.

Upper limb movement during locomotion in patients with neurological disorders: a wearable-based approach

The contribution of upper limbs during walking is crucial in maintaining balance and stability: humans, in fact, swing each upper limb in phase with contra-lateral lower limb at their comfortable walking speed, with a ratio of 1:1 [1], thus counteracting the angular momentum, reducing the energy expenditure, and improving the overall gait efficiency [2,3]. In people who suffer from neurological disorders, like Multiple Sclerosis (MS) or Traumatic Brain Injury (TBI), upper limb function is often impaired, resulting in differences in arm swing frequency, amplitude, symmetry, as well as in the ratio between step and arm swing frequency, compared to healthy people [2]. Although it is known that a neurological rehabilitation program should focus on the recovery of a proper gait also emphasizing the contribution of upper limbs [1], few studies analyzed the contribution of the upper arms during locomotion in people with neurological disorders. The aim of this study is to explore a wearable sensor-based protocol for the assessment of the upper limb movement in patients with MS and TBI compared to healthy participants. Thirty-three patients suffering from MS (24 F; 49.8±9.3 y; EDSS 4.0±1.6), 8 patients suffering from TBI (2 F; 32.3±14.1 y; DGI 18.3±5.9), and 20 healthy adults (HC) (9 F; 37.0±19.9 y) were enrolled in this study (CE/PROG.700). Each participant performed a 10-meter Walking Test (10mWT) while wearing 5 synchronized inertial measurement units (IMUs) located at sternum, both wrists and distal tibiae level. Stride segmentation was performed using tibiae-mounted IMUs and the following parameters were estimated from wrist- and sternum-mounted IMUs [4]: arm oscillation frequency, peak and range of the angular velocity norm, as well as step to arm oscillation frequency ratio for the right (RW) and left (LW) wrists (freq, gyro peak, gyro range, Step-freq ratio). The range of the sternum cranio-caudal angular velocity was also obtained (sternum gyro range), together with a measure of symmetry (Symmetry Index [5]) between RW and LW angular velocity ranges. After checking for data normality, a one-way ANOVA was used to test for significant differences among MS, TBI, and HC. Post-hoc analysis was performed using Bonferroni-Holmes correction for multiple comparisons. Results are depicted in Fig. 1 (the larger the spider, the better the performance). Significant differences were found in frequency, symmetry, and angular velocity parameters among the MS, TBI, and HC. Patients with TBI seem to be characterized by a reduced performance with respect to MS, except for the step to arm swing ratio. The proposed assessment protocol demonstrates a potential clinical value in discriminating not only patients with neurological disorders from HC, but also patients with MS from TBI, who showed significant differences in terms of swing frequency, angular velocity range, and symmetry. This information could be useful in tailoring rehabilitation treatments involving the upper limbs during gait exercises [1]. Although in the present study, no significant difference was found among the three populations walking speed, the effect of the latter on the proposed metrics should be better investigated in further studies.

Biomechanical differences between self-paced and fixed-speed treadmill walking in persons after stroke.

Using self-paced treadmills for gait analysis requires less space compared to overground gait labs while a more natural walking pattern could be preserved compared to fixed-speed treadmill walking. Although self-paced treadmills have been used in stroke related intervention studies, studies comparing self-paced to fixed-speed treadmill walking in this population are scarce. Twenty-five persons after stroke (10 males/15 females; 53±12.05years; 40.72±42.94months post stroke) walked on a treadmill in a virtual environment (GRAIL, Motek) in two conditions (self-paced and fixed-speed). After familiarization, all participants completed two trials (3min) at comfortable walking velocity in randomized order. A paired-sample t-test or Wilcoxon Signed Rank test was used to calculate differences between both conditions for spatiotemporal parameters. Statistical Parametric mapping was conducted using the t-tests (SPM(t)), to statistically compare the kinematic and kinetic curves. The self-selected walking velocity on the treadmill was higher in the self-paced condition compared to the fixed-speed condition (p<0.001). However, most variability and symmetry measures were similar in both conditions. Only the standard deviation of the step length at the paretic side was significant higher (p=0.007) and step length symmetry was significantly better (p=0.032) in the self-paced condition. Detected kinematic and kinetic differences were small (< 3°, < 0.1Nm/kg) and stride to stride variability was comparable in both conditions. Based on the results of the current study, self-paced walking can be used as an equivalent to fixed-speed treadmill walking in persons after stroke. Accordingly, this justifies the use of this more functional mode in clinical gait assessment and rehabilitation trials.

Growth of the hard palate between the ages of 6 and 10 years: A longitudinal study

Several studies have found that the shape of the palate can affect articulation of speech sounds, but not much information is available characterizing the three-dimensional shape of the palate. This is especially important in children, since their speech is maturing at the same time that the palate is still growing. This study examines the longitudinal growth of the palate from 8 children between the ages of 6 and 10 years, based on high-resolution three-dimensional digitized palate impressions. Measures of palate width, height, depth, and symmetry were derived from three anatomically defined points: the marginal gingiva between the front teeth, and between the second premolar and the first molar on both sides. While palate height was most difficult to measure accurately, it was also most highly correlated with age (R2 = .42, p&amp;lt;.001), while palate depth, width, and symmetry were poorly correlated with age (R2&amp;lt;.07, p&amp;gt;.17). Age and standing height were strongly correlated (R2 = .77, p&amp;lt;.001). At the individual level, palate height appeared to grow linearly with age, while the growth of palate width and depth was nonlinear and even non-monotonic, indicating a complex interaction between growth and the ongoing structural rearrangement of dentition in this age group. [Work supported, in part, by the NSF.]

Walking speed influences spatiotemporal but not symmetry measures of gait in children and adolescents with hemiplegia

BackgroundThe measurement of gait is likely influenced by walking speed in children with hemiplegia, but this relationship is not well characterized. Research questionWhat is the influence of walking speed on spatiotemporal and symmetry measures of gait in children with hemiplegia, with consideration of side and footwear condition? MethodsChildren with hemiparetic gait due to stroke were recruited for a small pilot intervention study. Participants walked at self-selected and fast speeds while barefoot and while wearing shoes. Data from baseline sessions were included in this analysis. The influence of walking speed on five spatiotemporal gait measures was determined using a generalized estimating equation to calculate the proportion of variability in the gait measures that was explained by walking speed. Differences between sides and footwear conditions, and the relationships between walking speed and two symmetry measures, are also reported. ResultsA total of 820 steps were analyzed from ten children (11.2 ± 4.1 years). Walking velocity significantly influenced all spatiotemporal measures of gait. As speed increased, step length increased and all temporal measures decreased, on both paretic and nonparetic sides. Wearing shoes increased step length and stance time for both paretic and nonparetic sides, and slowed step time on the nonparetic side. Regardless of footwear, the paretic side demonstrated slower step and swing times, and faster stance and single support times. We did not observe significant relationships between walking speed and gait symmetry. SignificanceOur observations suggest that walking speed alone influences the spatiotemporal measurement of gait in children with hemiplegia and should be considered in the interpretation of walking function. Yet, controlling for walking speed is often not feasible or not preferred in this population. We offer suggestions for clinicians and researchers who seek to measure gait during overground walking at freely-selected speeds.

Step Length Asymmetry Predicts Rehabilitation Length in Subacute Post Stroke Patients

Background: During the rehabilitation of individuals post stroke, evaluations are performed in order to discern the patient’s prognosis and optimize the treatment plan. However, these tests do not focus on gait symmetry, which might be a predictor for rehabilitation outcomes. We aimed to correlate gait symmetry measures of subacute post stroke patients with rehabilitation outcome and find the symmetry measure that best predicts the variability of the rehabilitation duration. A secondary aim was to compare these measures between patients with right and left brain lesions. Methods: We recruited 30 subacute post stroke patients (14 with right side lesion). We collected the following measures: National Institutes of Health Stroke Scale (NIHSS), Functional Independence Measure (FIM), the 10 m walk test (10MWT), Functional Ambulation Categories (FAC), spatial-temporal gait measures, and gait symmetry and variability. Results: We found moderate correlations between the step length symmetry and the length of rehabilitation, NIHSS, FIM, FAC and 10MWT. The symmetry index of the step length predicted the length of the rehabilitation period as it explained 32.1% of its variance (p = 0.001). Discussion: We conclude that a simple test of the step length symmetry might be informative in predicting rehabilitation length in subacute post stroke patients.

Partial Asymmetry Measures for Square Contingency Tables

In square contingency table analysis, we consider a partial measure that represents the degree of departure from symmetry for each of several pairs. It may be useful to pool the values of the measure into a single summary measure of partial asymmetry. We show that the estimator of partial measures is asymptotically mutually independent for a large sample size. The present paper proposes a symmetry measure in the class of weighted averages that is different from previous studies. The proposed measure is an approximation of the measure in the class of weighted averages that has the smallest variance.