Head Angle Research Articles

Comparing the effect of the posture of using smartphones on head and neck angles among college students

Smartphone users' posture can affect the musculoskeletal load of the user's neck. This study aims to compare the effect of the posture of using smartphones on head and neck angles among college students. The cross-sectional study was conducted among 80 college students. The Severity of Neck Pain (SNP) and the head and neck tilt angles, the gaze angle, and the amount of change in the forward head posture were determined. The angles were measured in three postures including standing, sitting on a chair with and without a backrest. Most of the participants (51.3%) reported moderate and severe neck pain. The angles during using smartphone had a significant difference in different positions, so that the best head (100.6 ± 11.3°) and neck (32.5 ± 11.2°) tilt angles and gaze angle (58.2 ± 13.7°) were in sitting position with leaning on a backrest of the chair. Head (109.6 ± 14.4°) and neck (22.0 ± 12.6°) tilt angles, and the forward head posture (15.9 ± 4.9 cm) have the worst posture in sitting position on a chair without a backrest while gaze angle (67.1 ± 12.0°) has the most awkward posture in standing. Practitioner summary: The posture of using a smartphone affects the amount of pressure on the neck. This study aims to investigate the effect of different positions of using smartphone on head and neck angles among Iranian university students. The angles during using smartphone had a significant difference in different positions.

Molecular and morphological analyses to improve taxonomic classification ofMetridia lucens/pacificain the North Pacific

AbstractMolecular and morphological analyses were used to resolve the taxonomy of Metridia lucens/pacifica in the North Pacific. Phylogenetic analysis of mitochondrial cytochrome c oxidase subunit I (mtCOI) revealed two lineages of M. lucens and M. pacifica with an average sequence difference of 13.0%, which were supported by variations in nuclear internal transcribed spacer sequences. Metridia pseudopacifica in the eastern Pacific, mentioned by Mackas and Galbraith (2002), was included in M. lucens. The presence of M. lucens and M. pacifica was confirmed across the North Pacific, and different genetic population structures were suggested between the two species in the North Pacific based on mtCOI sequences. The morphological identification character of length of setae on the fifth pair of legs was not useful for classifying adult female M. pacifica and M. lucens. There were regional variations in prosome length and head angle; these two characters successfully classified >98.2% of M. pacifica and M. lucens specimens from the North Pacific. As M. lucens and M. pacifica are key copepods in the North Pacific, accurate classification of individuals should be made in future studies to understand their relative contributions to marine ecosystems and improve detection of ecosystem change.

Quantitative effects of head rotation angle on apnea hypopnea index in positional obstructive sleep apnea \u2013 a preliminary case series

ObjectivesQuantify the effects of head rotation and head incline on obstructive sleep apnea (OSA) severity.DesignSingle-arm, intervention study.SettingPulmonary specialty clinic.Case presentationTen adults diagnosed with positional OSA ranging from 32 to 64 years of age 6 females, 4 males reporting persistent daytime sleepiness and health issues with consistent use of CPAP.InterventionStandard polysomnography with a head angle sensor attached to the forehead and coaching to fall asleep with head at various rotation and incline angles and torso in supine and non-supine positions.MeasurementsOSA severity was scored according to American Academy of Sleep Medicine guidelines. Apnea hypopnea index (AHI) and peripheral capillary oxygen (SpO2) saturation were measured during each sleep epoch of unique head rotation, head incline, and torso position.ResultsTwo participants (1 with no apneas and 1 with central sleep apnea) were excluded. Among the remaining 8 participants, average reduction in peak AHI was 66% (range 18–88%) with head rotation ≤ 20° above the horizon compared with > 20° above the horizon. The average of peak AHI values with head rotation ≤ 20° was significantly lower than with head rotation > 20° (20.0 vs 45.3, P = 0.002). Minimum SpO2 was significantly higher for head rotation ≤ 20° compared with > 20° (mean: 90.6% vs 84.3%, P = 0.03). In the torso supine position, average peak AHI was significantly lower with head rotation ≤ 20° compared with > 20° (7.1 vs 52.1, P < 0.001). In the torso non-supine position, lower average peak AHI with head rotation ≤ 20° was not statistically significant (22.3 vs 38.4, P = 0.09).ConclusionThese results support further exploration of maintaining head position ≤ 20° above the horizon to minimize AHI and oxygen desaturation in OSA patients.Trial registrationApnea Hypopnea Index Severity Versus Head Position During Sleep.ClinicalTrials.gov Identifier: NCT04086407 September 11, 2019 Registered retrospectively.

Predicting Collapse in Osteonecrosis of the Femoral Head Using a New Method: Preserved Angles of Anterior and Lateral Femoral Head.

Femoral head collapse (FHC) is associated with a poor prognosis in osteonecrosis of the femoral head (ONFH). Preserved angles (PAs), including the lateral preserved angle (LPA), the anterior preserved angle (APA) and the combined preserved angle (CPA), can be used to quantify the extent of femoral head necrosis and predict the risk of femoral head collapse. The purpose of this retrospective cohort study was to assess the efficacy of these preserved angles in the prediction of femoral head collapse using plain radiographs. Patients with ONFH treated conservatively between January 2010 and January 2019 were analyzed retrospectively to assess the risk of FHC. A logistic regression model was used to evaluate the independent prognostic factors associated with FHC, including age, sex, etiology, onset of symptom, The Japanese Investigation Committee classification, and PAs (LPA, APA, and CPA). A total of 137 patients, with 180 hips, had follow-up of at least two years and were included. During the follow-up period, FHC occurred in 89 hips (49.44%) after the initial diagnosis. Multivariable analysis indicated that CPA (odds ratio [OR] = 0.95; 95%CI = 0.93-0.97; P < 0.01) was a stronger predictor of femoral head collapse compared with the Japanese Investigation Committee classification (OR = 2.40, 95%CI = 0.92-6.25; P > 0.01). The receiver operating characteristic and survival curve analyses revealed that the predictive cutoff point for the CPA was 118.7° (sensitivity = 96.70%, specificity = 79.78%, log-rank test: P < 0.01). Assessment of preserved angles on plain radiographs is a simple method to quantify the extent of lateral and anterior necrosis of the femoral head. Specifically, CPA has a potential value in predicting femoral head collapse.

Effects of head flexion posture in patients with dysphagia.

The chin-down posture is often used as a compensatory manoeuvre for patients with dysphagia. This posture presumably involves flexion of the head and/or neck, but this is not clearly defined. This study aimed to assess the effects of head flexion posture in a retrospective study of videofluoroscopic examination of swallowing (VF). A total of 73 patients who underwent VF both with and without head flexion posture in the lateral projection were included in the analysis. The head and neck angles at the initiation of the swallowing reflex, penetration-aspiration scale (PAS), nasopharyngeal closure time, stage transition duration, duration of laryngeal closure, time from swallowing reflex to laryngeal closure and to the opening of upper oesophageal sphincter (UES), duration of UES opening, location of the bolus leading edge at swallowing reflex, and bolus transition time were evaluated. The head flexion angle increased (p<0.001), but the neck flexion angle did not change in the head flexion posture. Moreover, PAS improved (p<0.001), aspiration was reduced (p<0.001), the time between the swallowing reflex and the onset of laryngeal closure was shortened (p=0.006), and the leading edge of the bolus at swallowing reflex became shallower (p=0.004) in the head flexion posture. Other parameters did not significantly change. The head flexion posture resulted in earlier laryngeal closure and a shallower position of the leading bolus edge at swallowing reflex, resulting in PAS improvement and decreased aspiration.

MRI-Compatible Soft Robotic Sensing Pad for Head Motion Detection

Head motion remains a prevalent challenge to overcome in MRI as it results in severe image degradation. This letter presents the design, fabrication, and evaluation of a novel pneumatic based MRI-compatible soft sensing pad to be used for head motion detection. A modal based calibration method is used to estimate the weight of the head on the sensing pad. A calibration error of 0.12 <inline-formula><tex-math notation="LaTeX">$ \pm$</tex-math></inline-formula> 0.06 kg was observed. Gaussian process regression is then employed to establish a mapping from the weight of the head and the internal pressures of the sensing pad to the head motion based on experimental data. The testing result of the regression indicates that the sensing pad is capable of predicting the angle of the head in pure 1&#x00B0; of freedom rotations with a maximum RMSE of 1.48<inline-formula><tex-math notation="LaTeX">$ \pm$</tex-math></inline-formula>1.12 deg over a range of <inline-formula><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula>40 deg. Over a range commonly observed in clinical practice of <inline-formula><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula>10 deg, the sensing pad is able to predict the head angle with an RMSE of 0.88<inline-formula><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula>0.54 deg. The sensing pad has been deemed MRI safe and no significant SNR variation was observed during MRI compatibility experiments.

Functional relationship between the anatomical structures of the calf and athletic ability.

Calf muscle plays an important function in driving the movement of stepping on the ground and moving forward when walking or running. The Achilles tendon has been reported to be closely related to the elasticity of tendons to absorb shock and rebound and convert energy into propulsion. We wanted to determine the effect and correlation of the anatomical structure of the calf region on function. Measurements of anatomical structures were conducted with 51 volunteers using ultrasonography, and exercise capacity tests were conducted to measure anaerobic power, elasticity, and flexibility. The mean power and length of the calf (LoC), muscle thickness (MT), and fascicle angle (FA) of the medial head of gastrocnemius (p < 0.001) showed the strongest positive correlation among the variables of anatomical structures. MT of the Gastrocnemius and LoC Gastrocnemius were also correlated with peak power. In the anatomical structure variables, the FA of the lateral head of gastrocnemius, length and width of the Achilles tendon, and part of the athletic ability, the standing long jump test and sitting trunk flexion test, were not significantly correlated. Based on these results, it can be concluded that the height and degree of development of the calf muscles are structures that affect the exercise of anaerobic power. Hence, it can be used as a predictor of athletic ability. Furthermore, the trainer can predict athletic ability according to the characteristics of the event by first understanding the athlete's physical condition.

Hold that pose: capturing cervical dystonia's head deviation severity from video

ObjectiveDeviated head posture is a defining characteristic of cervical dystonia (CD). Head posture severity is typically quantified with clinical rating scales such as the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Because clinical rating scales are inherently subjective, they are susceptible to variability that reduces their sensitivity as outcome measures. The variability could be circumvented with methods to measure CD head posture objectively. However, previously used objective methods require specialized equipment and have been limited to studies with a small number of cases. The objective of this study was to evaluate a novel software system—the Computational Motor Objective Rater (CMOR)—to quantify multi‐axis directionality and severity of head posture in CD using only conventional video camera recordings.MethodsCMOR is based on computer vision and machine learning technology that captures 3D head angle from video. We used CMOR to quantify the axial patterns and severity of predominant head posture in a retrospective, cross‐sectional study of 185 patients with isolated CD recruited from 10 sites in the Dystonia Coalition.ResultsThe predominant head posture involved more than one axis in 80.5% of patients and all three axes in 44.4%. CMOR's metrics for head posture severity correlated with severity ratings from movement disorders neurologists using both the TWSTRS‐2 and an adapted version of the Global Dystonia Rating Scale (rho = 0.59–0.68, all p <0.001).ConclusionsCMOR's convergent validity with clinical rating scales and reliance upon only conventional video recordings supports its future potential for large scale multisite clinical trials.

Therapeutic routine with respiratory exercises improves posture, muscle activity, and respiratory pattern of patients with neck pain: a randomized controlled trial

Neck pain and forward head posture (FHP) are typical in prolonged smartphone users and need to be targeted for treatment. We aimed to compare the effect of a routine therapeutic program with and without respiratory exercises on smartphone users with FHP and non-specific chronic neck pain (NSCNP). Sixty patients (aged 24.7 ± 2.1 years) with FHP and NSCNP were randomly assigned to the routine therapeutic program (n = 20), combined respiratory exercises with a routine therapeutic program (n = 20), or control (n = 20) groups. At baseline, there was no difference among groups at all variables. Each programme was implemented three times a week for eight weeks. Primary Outcome was pain measured by visual analogue scale (VAS), and secondary ones were forward head angle, the activity of specific muscles, and respiratory patterns, measured by photogrammetry, electromyography and manual, respectively. All outcomes were measured at baseline and eight weeks post-treatment. We used the repeated measures analysis of variance to examine the interaction between time and group, paired t-test for intragroup comparison, one-way analysis of variance for intergroup comparison, and Tukey post hoc test at a significant level 95% was used. There were significant differences in the combined group compared with the routine therapeutic group (P = 0.03) for diaphragm muscle activation, respiratory balance (P = 0.01), and the number of breaths (P = 0.02). There were significant within-group changes from baseline to post-treatment in the combined group for all outcomes above, but no changes in the therapeutic exercise routine group. Despite respiratory pattern, none of the secondary outcomes proved to be superior in the combination group compared to the routine therapeutic program in smartphone users with FHP and NSCNP. Future studies with longer follow-up assessments could strengthen these results.Trial registration: Current Controlled Trials using the IRCT website with ID number of, IRCT20200212046469N1 “Prospectively registered” at 04/03/2020.

Effect of upper surface shape on waverider performances

Waveriders are of high lift-to-drag (L/D) ratio in hypersonic states; however, low volume of loading limits its application in practical engineering significantly. Raising the upper surface is a method to increase the volume space for waveriders, and this article studies the effect of the upper surface shape on the aerodynamic performances based on a single swept waverider configuration. Cubic polynomials were employed to construct the upper surface to replace the freestream-traced surface, and 2 parameters, the trailing edge thickness and inclination angle of head, were extracted as design variables. Analyzing the flow field using computational fluid dynamics techniques, raising the upper surface only had effect on the aerodynamic performance from the upper surface, but nearly no effect on the lower surface, and thus the design of upper and lower surfaces can be decoupled. As the trailing edge thickness and inclination angle of head increase, the volume of waveriders grows rapidly, while the loss in L/D ratio is limited. Compared with expanding the lower surface, raising the upper surface yielded better aerodynamic performances. The results indicate that raising the upper surface is a feasible and efficient approach to increase the loading volume of the waverider and hence promote its application in engineering.

Qigong Training Positively Impacts Both Posture and Mood in Breast Cancer Survivors With Persistent Post-surgical Pain: Support for an Embodied Cognition Paradigm.

Theories of embodied cognition hypothesize interdependencies between psychological well-being and physical posture. The purpose of this study was to assess the feasibility of objectively measuring posture, and to explore the relationship between posture and affect and other patient centered outcomes in breast cancer survivors (BCS) with persistent postsurgical pain (PPSP) over a 12-week course of therapeutic Qigong mind-body training. Twenty-one BCS with PPSP attended group Qigong training. Clinical outcomes were pain, fatigue, self-esteem, anxiety, depression, stress and exercise self-efficacy. Posture outcomes were vertical spine and vertical head angles in the sagittal plane, measured with a 3D motion capture system in three conditions: eyes open (EO), eyes open relaxed (EOR) and eyes closed (EC). Assessments were made before and after the Qigong training. The association between categorical variables (angle and mood) was measured by Cramer’s V. In the EO condition, most participants who improved in fatigue and anxiety scales also had better vertical head values. For the EOR condition, a moderate correlation was observed between changes in vertical head angle and changes in fatigue scale. In the EC condition, most of the participants who improved in measures of fatigue also improved vertical head angle. Additionally, pain severity decreased while vertical spine angle improved. These preliminary findings support that emotion and other patient centered outcomes should be considered within an embodied framework, and that Qigong may be a promising intervention for addressing biopsychosocially complex interventions such as PPSP in BCSs.

Quantitative Analysis of Dynamic Subacromial Ultrasonography: Reliability and Influencing Factors.

Objective: Current imaging methods used to examine patients with subacromial impingement syndrome (SIS) are limited by their semi-quantitative nature and their capability of capturing dynamic movements. This study aimed to develop a quantitative analytic model to assess subacromial motions using dynamic ultrasound and to examine their reliability and potential influencing factors. Method: We included 48 healthy volunteers and examined their subacromial motions with dynamic ultrasound imaging. The parameters were the minimal vertical acromiohumeral distance, rotation radius, and degrees of the humeral head. The generalized estimating equation (GEE) was used to investigate the impact of different shoulder laterality, postures, and motion phases on the outcome. Result: Using the data of the minimal vertical acromiohumeral distance, the intra-rater and inter-rater reliabilities (intra-class correlation coefficient) were determined as 0.94 and 0.88, respectively. In the GEE analysis, a decrease in the minimal vertical acromiohumeral distance was associated with the abduction phase and full-can posture, with a beta coefficient of −0.02 cm [95% confidence interval (CI), −0.03 to −0.01] and −0.07 cm (95% CI, −0.11 to −0.02), respectively. The abduction phase led to a decrease in the radius of humeral rotation and an increase in the angle of humeral rotation, with a beta coefficient of −1.28 cm (95% CI, −2.16 to −0.40) and 6.60° (95% CI, 3.54–9.67), respectively. A significant negative correlation was observed between the rotation angle and radius of the humeral head and between the rotation angle and the minimal vertical acromiohumeral distance. Conclusion: Quantitative analysis of dynamic ultrasound imaging enables the delineation of subacromial motion with good reliability. The vertical acromiohumeral distance is the lowest in the abduction phase and full-can posture, and the rotation angle of the humeral head has the potential to serve as a new parameter for the evaluation of SIS.

Combination of Anterior Acetabular Coverage and Femoral Head Shape Predicts Femoroacetabular Impingement After Periacetabular Osteotomy.

Femoroacetabular impingement (FAI) after periacetabular osteotomy (PAO) may be affected by both anterior acetabular coverage and femoral head shape. This study aimed to radiographically evaluate the relationship of the combination of acetabular coverage and femoral head shape with the occurrence of FAI after curved PAO. In this study, 76 hip joints from patients with symptomatic developmental dysplasia of the hip underwent curved PAO. The relationship between the combined postoperative anterior center-edge and alpha angles (ie, the combination angle) and the occurrence of postoperative FAI was evaluated. Clinical factors and the preoperative and postoperative 3-dimensional center-edge angles, acetabular versions, femoral versions, radiographic alpha angles of the femoral head, and the combination angle were measured and compared to clinical outcomes. The modified Harris Hip Scores, University of California, Los Angeles activity scores, and acetabular coverage angles were significantly improved following curved PAO. Receiver operator characteristic curve analysis demonstrated that the combination angle over 108° may be a predictive factor for the occurrence of FAI after curved PAO. Multivariate analysis demonstrated that an age <40 years (odds ratio 6.6, 95% confidence interval 1.2-36.4, P= .037) and a combination angle <108° (odds ratio 9.2, 95% confidence interval 1.7-50.0, P= .010) were significantly associated with modified Harris Hip Scores ≧90 points. A combination angle >108° may be a predictive factor for the occurrence of FAI after curved PAO and impaired clinical outcomes. To avoid postoperative FAI, we propose that osteochondroplasty of the femoral head should be performed for patients with preoperative combination angles >90°.

Automatic Measurement of Postural Abnormalities With a Pose Estimation Algorithm in Parkinson’s Disease

ObjectiveThis study aims to develop an automated and objective tool to evaluate postural abnormalities in Parkinson’s disease (PD) patients.MethodsWe applied a deep learning-based pose-estimation algorithm to lateral photos of prospectively enrolled PD patients (n = 28). We automatically measured the anterior flexion angle (AFA) and dropped head angle (DHA), which were validated with conventional manual labeling methods.Results The automatically measured DHA and AFA were in excellent agreement with manual labeling methods (intraclass correlation coefficient > 0.95) with mean bias equal to or less than 3 degrees.ConclusionThe deep learning-based pose-estimation algorithm objectively measured postural abnormalities in PD patients.

Anterior acetabular coverage and femoral head-neck measurements predict postoperative anterior impingement: A simulation study.

The aim of this simulation study was to evaluate the relationship of elements of anterior acetabular coverage and femoral head-neck shape with the occurrence of postoperative anterior impingement after curved periacetabular osteotomy (PAO). Sixty-two patients with symptomatic developmental dysplasia of the hip who had undergone curved PAO were selected. The likelihood of developing postoperative anterior impingement was explored through simulations of the range of motion by collision detection of the pelvis and femur. Postoperative anterior impingement was defined as impingement that occurred during postoperative bone flexion <105° or postoperative internal rotation <20° at 90° flexion. The three-dimensional center-edge (CE) angles, acetabular and femoral versions, radiographic alpha angles of the femoral head, combination angles of anterior CE and alpha angles, and combined anteversions of acetabular and femoral versions were compared between patients with postoperative anterior impingement and nonimpingement. A receiver operator characteristic (ROC) analysis was conducted to determine thresholds of the examined radiographic parameters and calculate their accuracy for predicting postoperative anterior impingement. A multivariate analysis was performed to test whether combined anteversion, anterior CE angle, and combination angle are associated with excellent modified Harris Hip Scores (mHHSs).ROC analysis demonstrated a combination angle ≥108° was predictive of the occurrence of postoperative anterior impingement after curved PAO, which can lead to impaired clinical outcomes. Conversely, a combination angle <108° was significantly associated with mHHS ≥ 90 points. To avoid postoperative anterior impingement, osteochondroplasty of the femoral head or anterior CE angle control should be performed for patients with preoperative combination angles ≥90°.

Tongue Postures and Tongue Centers: A Study of Acoustic-Articulatory Correspondences Across Different Head Angles.

Recent research on body and head positions has shown that postural changes may induce varying degrees of changes on acoustic speech signals and articulatory gestures. While the preservation of formant profiles across different postures is suitably accounted for by the two-tube model and perturbation theory, it remains unclear whether it is resulted from the accommodation of tongue postures. Specifically, whether the tongue accommodates the changes in head angle to maintain the target acoustics is yet to be determined. The present study examines vowel acoustics and their correspondence with the articulatory maneuvers of the tongue, including both tongue postures and movements of the tongue center, across different head angles. The results show that vowel acoustics, including pitch and formants, are largely unaffected by upward or downward tilting of the head. These preserved acoustics may be attributed to the lingual gestures that compensate for the effects of gravity. Our results also reveal that the tongue postures in response to head movements appear to be vowel-dependent, and the tongue center may serve as an underlying drive that covariates with the head angle changes. These results imply a close relationship between vowel acoustics and tongue postures as well as a target-oriented strategy for different head angles.

The Validity of Wireless Earbud-Type Wearable Sensors for Head Angle Estimation and the Relationships of Head with Trunk, Pelvis, Hip, and Knee during Workouts.

The present study was performed to investigate the validity of a wireless earbud-type inertial measurement unit (Ear-IMU) sensor used to estimate head angle during four workouts. In addition, relationships between head angle obtained from the Ear-IMU sensor and the angles of other joints determined with a 3D motion analysis system were investigated. The study population consisted of 20 active volunteers. The Ear-IMU sensor measured the head angle, while a 3D motion analysis system simultaneously measured the angles of the head, trunk, pelvis, hips, and knees during workouts. Comparison with the head angle measured using the 3D motion analysis system indicated that the validity of the Ear-IMU sensor was very strong or moderate in the sagittal and frontal planes. In addition, the trunk angle in the frontal plane showed a fair correlation with the head angle determined with the Ear-IMU sensor during a single-leg squat, reverse lunge, and standing hip abduction; the correlation was poor in the sagittal plane. Our results indicated that the Ear-IMU sensor can be used to directly estimate head motion and indirectly estimate trunk motion.

Finite element analysis of different medial fixation strategies in double-plate osteosynthesis for AO type 33-C2 Femoral fractures

ObjectivesIn this study, we evaluated the biomechanical characteristics of different locations of medial fixation strategies in double-plate osteosynthesis for fixing AO/ASIF type 33-C2 femoral fractures by means of finite element analysis. MethodsWe used 3-matic software and UG-NX software to construct AO/ASIF type 33-C2 Femoral fractures and lateral less invasive stabilization system (LISS) plates, medial plates (MPs), and medial support pads (MSPs), respectively. Then, the LISS, MP and MSP were assembled into the fracture model separately to form three fixation models: MSP+LISS, anteromedial plate (AMP+LISS), and MP+LISS. In the next procedure, we performed finite element analysis using ANSYS software after meshing the elements of the models in HyperMesh 11.0 software. Loading conditions including lateral-medial four-point bending, anterior-posterior four-point bending, axial loading, and torsional loading were applied to evaluate the biomechanical advantages among the three fixation types. We observed the peak Von Mises Stress (VMS) value, maximum displacement, bending angle in the coronal plane of the fracture, and torsional angle of the fracture to assess the degree of plate deformation and fixation stability. ResultsOur results showed that in both lateral-medial four-point bending and anterior-posterior four-point bending, the calculations of MP+LISS were marginally better than those of AMP+LISS. However, with the action of axial loading and torsional loading, the deformation of MP+LISS was distinctly smaller than that of AMP+LISS, and the fixation stability of MP+LISS was also prominently better. Under lateral-medial four-point bending, the VMS on the lateral plate of MSP+LISS (59.977 MPa) was approximately half of the two double-plate models. Under anterior and posterior four-point bending, the 38.209 MPa peak VMS of MSP+LISS was still superior to the other two double-plate models. Under torsional loading, the peak VMS (347.75 MPa), the maximum torsional angle of the femoral head (7.852 °), and the torsional angle of fracture (0.036 °) of MSP+LISS preceded those of the other two models. However, under axial loading, the peak VMS (76.376 MPa) and the maximum displacement (3.1798 mm) of MSP+LISS were slightly higher than those of MP+LISS. ConclusionThe MSP+LISS model showed better biomechanical performance than the double-plate models, which might be an effective solution for the treatment of comminuted distal femur fractures.

Sound Source Selection Based on Head Movements in Natural Group Conversation.

To optimally improve signal-to-noise ratio in noisy environments, a hearing assistance device must correctly identify what is signal and what is noise. Many of the biosignal-based approaches to solving this question are themselves subject to noise, but head angle is an overt behavior that may be possible to capture in practical devices in the real world. Previous orientation studies have demonstrated that head angle is systematically related to listening target; our study aimed to examine whether this relationship is sufficiently reliable to be used in group conversations where participants may be seated in different layouts and the listener is free to turn their body as well as their head. In addition to this simple method, we developed a source-selection algorithm based on a hidden Markov model (HMM) trained on listeners’ head movement. The performance of this model and the simple head-steering method was evaluated using publicly available behavioral data. Head angle during group conversation was predictive of active talker, exhibiting an undershoot with a slope consistent with that found in simple orientation studies, but the intercept of the linear relationship was different for different talker layouts, suggesting it would be problematic to rely exclusively on this information to predict the location of auditory attention. Provided the location of all target talkers is known, the HMM source selection model implemented here, however, showed significantly lower error in identifying listeners’ auditory attention than the linear head-steering method.

Wide-angle, monocular head tracking using passive markers

BackgroundCamera images can encode large amounts of visual information of an animal and its environment, enabling high fidelity 3D reconstruction of the animal and its environment using computer vision methods. Most systems, both markerless (e.g. deep learning based) and marker-based, require multiple cameras to track features across multiple points of view to enable such 3D reconstruction. However, such systems can be expensive and are challenging to set up in small animal research apparatuses. New methodsWe present an open-source, marker-based system for tracking the head of a rodent for behavioral research that requires only a single camera with a potentially wide field of view. The system features a lightweight visual target and computer vision algorithms that together enable high-accuracy tracking of the six-degree-of-freedom position and orientation of the animal’s head. The system, which only requires a single camera positioned above the behavioral arena, robustly reconstructs the pose over a wide range of head angles (360° in yaw, and approximately ± 120° in roll and pitch). ResultsExperiments with live animals demonstrate that the system can reliably identify rat head position and orientation. Evaluations using a commercial optical tracker device show that the system achieves accuracy that rivals commercial multi-camera systems. Comparison with existing methodsOur solution significantly improves upon existing monocular marker-based tracking methods, both in accuracy and in allowable range of motion. ConclusionsThe proposed system enables the study of complex behaviors by providing robust, fine-scale measurements of rodent head motions in a wide range of orientations.