Deviation Angle Research Articles

Robotically Assisted vs. Manual Total Hip Arthroplasty in Developmental Hip Dysplasia: A Comparative Analysis of Radiological and Functional Outcomes

Background/Objectives: Developmental dysplasia of the hip (DDH), defined by the malalignment of the femoral head and acetabulum, is a major precursor to coxarthrosis, posing substantial challenges during total hip arthroplasty (THA). Patients with coxarthrosis secondary to DDH often exhibit acetabular bone insufficiency, which makes challenging surgical reconstruction difficult. This study aimed to compare the radiologic and functional outcomes of robotically assisted and conventional manual THA techniques in patients with coxarthrosis secondary to Crowe type III–IV DDH. Methods: This prospective study included 40 patients divided into robotically assisted (n = 20) and conventional manual (n = 20) THA groups. Evaluations encompassed hip pain (Visual Analogue Scale, VAS), function (Harris hip score and University of California, Los Angeles, activity scale), quality of life (Short Form-12), and prosthesis sensation (Forgotten Joint Score-12). Radiologic outcomes included acetabular inclination and anteversion angles. Femoral shortening, operative duration, and follow-up times were also analyzed. Results: Demographic characteristics did not differ between groups (p > 0.05). Robotically assisted THA exhibited a significantly longer operative time (171.40 ± 11.96 vs. 150.30 ± 14.67 min; p = 0.001) but a shorter follow-up (29.3 ± 8.51 vs. 52.95 ± 18.96 months; p = 0.001), without a difference in the amount of femoral shortening (p = 0.947). Despite the extended surgical duration, the two techniques achieved comparable radiologic outcomes, with no significant differences in acetabular inclination or anteversion angles (p > 0.05). Functional assessments, including Harris hip scores (73.85 vs. 73.95; p = 0.978), UCLA activity scores, and VAS, indicated similar efficacy between groups. SF-12 physical and mental quality of life and Forgotten Joint Score-12 prosthesis sensation did not differ between groups (p > 0.05). Conclusions: This study concludes that robotically assisted and conventional manual THA present similar radiologic and functional outcomes in patients with coxarthrosis secondary to Crowe type III–IV DDH, as displayed by comparable acetabular anteversion and inclination alignment, femoral shortening, hip function, pain, quality of life, and prosthesis sensation scores. While robotically assisted THA requires a longer operative time, its precision in implant placement may hold potential advantages for long-term outcomes, demanding further investigation in extended follow-up studies.

Kinematic Alterations with Changes in Putting Distance and Slope Incline in Recreational Golfers

Golfers must modify their motor patterns when the demands of a putting task change. The objective was to compare joint angles and putter kinematics during putting at two distances and inclines. Recreational golfers (n = 14) completed putts over four conditions: 3-foot putts on flat and incline surfaces, and 7-foot putts on flat and incline surfaces. A Vicon motion capture system measured kinematic data. Joint angles, putter angles, and spatiotemporal variables were calculated. Analysis of variance compared spatiotemporal variables, and statistical parametric mapping compared angles between putts. There were faster putter head and ball velocities during longer and incline putts. The amplitude and time of backswing increased with longer putts. Longer putts resulted in increased trunk axial rotation during backswing, downswing, and follow-through, while incline putts only resulted in greater rotation during follow-through. There were minimal differences in shoulder angle. There was greater head rotation toward the hole during all putting phases for longer putts and during follow-through for incline putts. The trunk is the primary mechanism to increase putter head amplitude, and thereby velocity, when putting from longer distances. A similar strategy could be used when putting uphill. Additional work should confirm these results in highly skilled golfers.

The impact of side and top arm techniques during the backstroke breakout phase on 15-meter swimming performance

Background Research on the swimming starts and turns in professional swimming has become increasingly refined. The breakout phase is a crucial transition from point between underwater and above-water movements. The side arm technique is commonly used during the backstroke breakout phase. However, some swimmers have also achieved good performance using the top arm technique. The impact of the two techniques during the backstroke breakout phase is yet to be explored. Purpose To compare the velocity and key angles differences between the side arm and top arm techniques and analyze their effect on the first 15-m performance after push-off. Methods The subjects were 16 high-level swimmers: eight males (20.4 ± 1.6 yr) and eight females (20.9 ± 1.7 yr). Of these, 14 were backstrokers or had individual medley as their primary event. The best performances in the history of the sport’s level World Aquatics Points are 682.1 ± 59.0 and 729.3 ± 41.5 for males and females, respectively. A within-subject design was used to test both the side arm and top arm techniques. Four underwater cameras were used to capture two-dimensional data from two perspectives, focusing on the breakout phase. A two-way ANOVA used to compare segment velocity, angles, and 15-m performance between the two genders and breakout techniques. Pearson’s correlation analysis was used to explore the relationship between segment velocity and 15-m performance, and hierarchical regression was employed to investigate the impact of breakout velocity on the 15-m performance. Results Both male and female swimmers exhibited a significantly faster top arm velocities of (1.72 ± 0.20 and 1.47 ± 0.16 m/s, respectively) compared to the side arm velocities (1.51 ± 0.23 and 1.29 ± 0.19 m/s, respectively) during the breakout phase. Additionally, significant differences were found between the two genders (F = 11.189, p = 0.002, η2 = 0.286) and breakout techniques (F = 8.014, p = 0.008, η2 = 0.223), with no interaction effect (F = 0.037, p = 0.849, η2 = 0.001). Furthermore, both male (R = −0.447, p = 0.109) and female (R = −0.555, p = 0.017) swimmers showed a moderate positive correlation between breakout velocity and 15-m performance, and the regression model indicated a significant impact on the 15-m performance. Conclusion The top arm technique during backstroke may offer a velocity advantage over the traditional side arm technique during the breakout phase, influencing 15-m performance. However, considering the short duration of the breakout phase, this advantage and its impact may need to be considered in conjunction with the smoothness of the transition to the subsequent phases.

Efficacy of virtual reality balance training on rehabilitation outcomes following anterior cruciate ligament reconstruction: A systematic review and meta-analysis.

The objective of this systematic review and meta-analysis is to clarify the rehabilitation efficacy of virtual reality (VR) balance training after anterior cruciate ligament reconstruction (ACLR). This meta-analysis was registered in PROSPERO with the registration number CRD42024520383. The electronic databases PubMed, Web of Science, Cochrane Library, MEDLINE, Embase, China National Knowledge Infrastructure, Chinese Biomedical Literature, China Science and Technology Journal Database, and Wanfang Digital Periodical database were systematically searched to identify eligible studies from their inception up to January 2024. The investigated outcomes included International Knee Documentation Committee (IKDC) score, visual analogue scale (VAS), Holden grading, Extensor peak torque (EPT), Flexor peak torque (FPT), knee reaction time, knee reproduction angle difference. The pooled mean difference (MD) and 95% confidence intervals (CIs) were calculated using the random-effects model. Six RCTs with a total of 464 patients after unilateral ACLR were included for 8-12 weeks of VR balance training intervention. Analysis of the results showed that compared with the conventional rehabilitation control group, the VR balance training group significantly improved the International Knee Documentation Committee (IKDC) score (MD = 3.88, 95%CI: 0.95~6.81), Holden grading (MD = 0.42, 95%CI: 0.33~0.51), Extensor peak torque (EPT) (MD = 12.03, 95%CI: 3.28~20.78)and Flexor peak torque (FPT) (MD = 14.57, 95%CI: 9.52~19.63) in postoperative ACLR patients, and significantly reduced knee reaction time (MD = -0.30, 95%CI: -0.35~-0.25), knee angle reproduction difference at 30° (MD = -0.88, 95%CI: -1.16~-0.61), knee angle reproduction difference at 60° (MD = -0.80, 95%CI: -1.09~-0.50), and VAS score (MD = -0.52, 95%CI: -0.65~-0.39). Since many of the included results are based on low-or very-low-quality evidence, although the results show a certain trend, the conclusion has great uncertainty. In the rehabilitation training following ACLR and lower-limb balance training, the application of VR might be advantageous for the recovery of patients' knee joint function, lower-limb muscle strength, proprioception, and pain management. The level of immersion may influence the rehabilitation outcome. Because of the limitations in data quality and heterogeneity as well as the small sample size, the strength of the conclusions is weakened. These findings should be verified in further large-scale prospective studies.

Kinematic analysis of aerobics using biomechanics: Comparisons between different complex movements in ten athletes

Accurately executing high-difficulty aerobics movements is essential for improving competitive scores. This paper carried out a kinematic analysis of two complex movements, A104 and A136, ten aerobics athletes from three universities in Beijing. The results indicated minimal difference between the two movements during the plio push-up phase. However, in the airborne phase, A136 demonstrated a higher elevation and a larger angle of the elbow joints to facilitate subsequent landing. In the touchdown cushioning phase, A136 and A104 exhibited significant differences in the right hip joint angle and left shoulder joint angle. Amateur athletes had a higher degree of joint variation during airborne and touchdown buffer phases compared to professional athletes, making them more prone to joint injuries.

Spinal Alignment and Pain: An Assessment of Amateur Road Cyclists—A Pilot Study

Background: Cycling involves specific body positions that, when maintained for prolonged periods, may affect spinal curvature and increase the risk of pain-related issues. This study aimed to evaluate sagittal spinal curvatures, the prevalence of pain in spinal segments, and their interrelation among amateur road cyclists. Methoods: The research included 30 male participants aged 18–48 years. Pain severity was assessed using the Visual Analog Scale (VAS) and Laitinen scale, while spinal curvature was evaluated with an electronic inclinometer. Results: Results showed no statistically significant differences in spinal curvature angles between cyclists with and without pain complaints (p = 0.056). However, tendencies were noted, such as higher mean VAS scores for lower back pain (4.90) compared to neck pain (3.38), and variations in parameters like Beta, LL, and KGP. Conclusions: While the findings did not confirm clear distinctions, they suggest trends indicating potential links between spinal curvatures and pain occurrence. These results underscore the importance of further studies involving larger cohorts to verify these observations and explore the biomechanical adaptations associated with amateur cycling. Insights from such research could inform strategies for preventing and managing spinal pain among cyclists.

Machine learning algorithms for predicting delayed hyponatremia after transsphenoidal surgery for patients with pituitary adenoma

This study aimed to develop and validate machine learning (ML) models to predict the occurrence of delayed hyponatremia after transsphenoidal surgery for pituitary adenoma. We retrospectively collected clinical data on patients with pituitary adenomas treated with transsphenoidal surgery between January 2010 and December 2020. From January 2021 to December 2022, patients with pituitary adenomas were prospectively enrolled. We trained seven ML models to predict delayed hyponatremia using the clinical variables in the training set. The final model was internally validated using a test set and a prospective dataset. The SHapley Additive exPlanations (SHAP) algorithm was used to determine the significance of each variable in the occurrence of delayed hyponatremia. In the training dataset, the best predictive performance was observed for XGBoost (area under the ROC curve; AUC = 0.821), followed by Random Forest (AUC = 0.8), Logistic Regression (AUC = 0.793), Support Vector Machine (AUC = 0.776), naïve Bayes (AUC = 0.774), K-Nearest Neighbors (AUC = 0.742), and Decision Tree (AUC = 0.717). The AUC of the XGBoost model for the test and prospective datasets are 0.831 and 0.785, respectively. The differences in pituitary stalk deviation angle, the “measurable pituitary stalk” length before and after surgery, and blood sodium concentration between preoperative and postoperative day 2 were important variables for predicting delayed hyponatremia as determined by the SHAP algorithm. The XGBoost model was best able to predict delayed hyponatremia after transsphenoidal surgery for pituitary adenomas. The differences in pituitary stalk deviation angle, pre- versus postoperative “measurable pituitary stalk” length, and pre- versus postoperative day 2 blood sodium concentrations were important variables for predicting delayed hyponatremia.

Risk prediction for elderly cognitive impairment by radiomic and morphological quantification analysis based on a cerebral MRA imaging cohort.

To establish morphological and radiomic models for early prediction of cognitive impairment associated with cerebrovascular disease (CI-CVD) in an elderly cohort based on cerebral magnetic resonance angiography (MRA). One-hundred four patients with CI-CVD and 107 control subjects were retrospectively recruited from the 14-year elderly MRA cohort, and 63 subjects were enrolled for external validation. Automated quantitative analysis was applied to analyse the morphological features, including the stenosis score, length, relative length, twisted angle, and maximum deviation of cerebral arteries. Clinical and morphological risk factors were screened using univariate logistic regression. Radiomic features were extracted via least absolute shrinkage and selection operator (LASSO) regression. The predictive models of CI-CVD were established in the training set and verified in the external testing set. A history of stroke was demonstrated to be a clinical risk factor (OR 2.796, 1.359-5.751). Stenosis ≥ 50% in the right middle cerebral artery (RMCA) and left posterior cerebral artery (LPCA), maximum deviation of the left internal carotid artery (LICA), and twisted angles of the right internal carotid artery (RICA) and LICA were identified as morphological risk factors, with ORs of 4.522 (1.237-16.523), 2.851 (1.438-5.652), 1.373 (1.136-1.661), 0.981 (0.966-0.997) and 0.976 (0.958-0.994), respectively. Overall, 33 radiomic features were screened as risk factors. The clinical-morphological-radiomic model demonstrated optimal performance, with an AUC of 0.883 (0.838-0.928) in the training set and 0.843 (0.743-0.943) in the external testing set. Radiomics features combined with morphological indicators of cerebral arteries were effective indicators for early signs of CI-CVD in elderly individuals. Question The relationship between morphological features of cerebral arteries and cognitive impairment associated with cerebrovascular disease (CI-CVD) deserves to be explored. Findings The multipredictor model combining with stroke history, vascular morphological indicators and radiomic features of cerebral arteries demonstrated optimal performance for the early warning of CI-CVD. Clinical relevance Stenosis percentage and tortuosity score of the cerebral arteries are important risk factors for cognitive impairment. The radiomic features combined with morphological quantification analysis based on cerebral MRA provide higher predictive performance of CI-CVD.

Sex-Related Differences in Motor Unit Firing Rate and Pennation Angle.

Motor unit firing rate (MUFR) and pennation angle were measured concurrently in males and females from submaximal to maximal intensities. Thirty participants, (16F and 14M) performed isometric dorsiflexion contractions at 20%, 40%, 60%, 80% and 100% of maximal voluntary contraction (MVC). During each contraction, measures of MUFR were obtained via surface electromyography decomposition, and muscle fiber pennation angle and fascicle length were obtained via ultrasound. There was no significant interaction effect of sex and contraction intensity present for mean MUFR (p=0.24), pennation angle (p=0.98), or fascicle length (p=0.81). Males had greater mean MUFR (p<0.001), pennation angle (p=0.02), and fascicle length (p=0.03) compared to females. In general, mean MUFR (p<0.001) and pennation angle (p<0.02), increased with increasing contraction intensity, however, fascicle length (p=0.30) was similar across contraction intensities. There were no significant relationships between mean MUFR and pennation angle for males (r=0.18, p=0.13) or females (r=0.20, p=0.09), nor between mean MUFR and fascicle length for males (r=0.20, p=0.10) or females (r=0.21, p=0.07). Although sex-related differences in MUFR, pennation angle and fascicle length were present, there were no relationships between MUFR and the muscle properties. These results suggest that sex-related differences in mean MUFR may not be associated with the sex-related differences in the muscle architectural properties currently investigated.

Decoding the Torsional Dynamics of Main-Chain Atoms Within CαNN Motif Facilitating Specific Anion Recognition.

The structural plasticity of proteins at the molecular level is largely dictated by backbone torsion angles, which play a critical role in ligand recognition and binding. To establish the anion-induced cooperative arrangement of the main-chain (mc) torsion, herein, we analyzed a set of naturally occurring CαNN motifs as "static models" for their anion-binding competence through docking and molecular dynamics simulations and decoded its torsion angle influenced mc-driven anion recognition potential. By comparing a pool of 20 distinct sets of CαNN motif with identical sequences in their "anion bound/present, aP" and "anion free/absent, aA" versions, we could discern that there exists a positive correlation between the "difference of anion residence time (ΔRT)" and "difference among the main-chain torsion angle" of the aP and aA population. Notably, the anion interaction with CαNNs is locally energetically favorable even in a context-free non-proteinaceous environment and if the difference of the mc-torsion angles involving the Cα-1, N0, N1 residues for a population is higher between the aP and aA state, the difference among the ligand RT is also greater. At the atomistic level, the accommodation of anion is highly synergistic and cooperatively sways the interacting mc-atom torsions. By comparing the clustering of H-bonding patterns, the free energy of binding, and RT in both states, we provide evidence that to establish favorable thermodynamics and kinetics of ligand accommodation in these short structural motifs, proper reorientation of local-mc governed by torsions is a prerequisite. Our findings position the CαNN motif as a promising scaffold for peptidomimetic design and emphasize the critical role of loop region dynamics in protein structure-function relationships.

Reliability and Validity of the Articulation Motion Assessment System Using a Rotary Encoder

This study aimed to validate the effectiveness of the Articulation Motion Assessment System (AMAS), a joint kinematic evaluation system, for clinical applications. AMAS enables synchronised measurement using neurophysiological indicators, overcoming laboratory setting limitations. We compared AMAS-based ankle joint kinematic evaluations, particularly the sagittal and frontal plane angles, with two-dimensional (2D) motion analysis to determine the validity and reliability of AMAS. Both AMAS and 2D motion analysis reliably detected significant differences in angles within the sagittal and frontal planes. Correlation analysis revealed a significant moderate-to-strong correlation between the AMAS and the conventional method of 2D motion analysis, proving the measurement validity of the AMAS (ρ = 0.53–0.77 for sagittal plane angles; ρ = 0.46–0.72 for frontal plane angles). The average root mean squared error (RMSE) was significantly lower in AMAS (10.90 ± 2.93° for sagittal plane angles; 13.44 ± 1.09° for frontal plane angles) than in the inertial sensor-based three-dimensional (3D) motion analysis. Reliability analysis revealed high reliability of measurements (intraclass correlation coefficients (ICC) ≥ 0.76). However, the Bland–Altman analysis identified a slightly lower fixed bias, which was observed as a characteristic of each measurement system. The AMAS accurately detects ankle joint angles without being constrained by measurement environment limitations. Synchronised measurements using neurophysiological indicators potentially contribute to understanding ankle joint control mechanisms and developing rehabilitation strategies.

A radiological study on the relationship between the novel acromial angle and rotator cuff tears

To investigate the relationship between the novel acromial angle and rotator cuff tears through imaging studies. We retrospectively selected 148 patients who underwent complete imaging examinations including scapular outlet X-rays and shoulder MRIs from January 2023 to September 2024 at our hospital. Based on whether the subjects had rotator cuff tears, they were divided into an injury group and a normal group, and the differences in the novel acromial angle between the two groups were compared. The novel acromial angle in the normal group was (149.1 ± 5.957)°, while in the injury group, it was (142.3 ± 6.558)°, showing a statistically significant difference between the two groups (P < 0.001). The probability of rotator cuff injury was 79.07% for individuals with a novel acromial angle smaller than the average in the injury group. The novel acromial angle in the injury group was generally smaller than that in the normal group. A novel acromial angle smaller than the average was associated with a higher probability of rotator cuff injury, and smaller angles were more likely to lead to more severe rotator cuff tears. Therefore, the novel acromial angle may serve as a simple and objective method to predict the probability of rotator cuff tears.

Comparison of tooth substance loss and angle deviation in access cavity preparation using guided endodontics and conventional method in calcified canals – An in vitro study

Abstract Aims: This study aimed to evaluate the accuracy of access cavity preparation using guided endodontics (GE) and conventional technique (CT) in calcified canals. Subjects and Methods: Twenty teeth with calcification up to middle third were collected after scanning through RadioVisioGraphy (RVG). Preoperative cone-beam computed tomography (CBCT) scan was done and samples were randomly divided into two groups of ten samples each on the basis of method of access cavity preparation. Group 1: Access cavity was prepared by CT, Group 2: Access cavity was prepared by GE. 3D template and corresponding guide drill were made for group 2 samples after performing optical surface scans. After access cavity preparation, postoperative CBCT scanning was performed for all samples. The amount of tooth structure loss and angle deviation were calculated using Sidexis Software. Statistical Analysis Used: The data were analyzed using IBM SPSS Statistics, version 22. A t-test compared tooth structure loss and angle deviation between groups, and a one-way ANOVA calculated tooth structure loss in multiple directions for both groups (P &lt; 0.001). Results: Our study found that the mean tooth volume loss (17.19 mm3 ± 06.11 standard deviation [SD]) and angle deviation (4.82° ±01.66 SD) in GE was significantly less (P &lt; 0.001) as compared to mean tooth structure loss (38.85 mm3 ± 19.07 SD) and angle deviation (13.16° ±2.34 SD) by CT. Conclusion: GE is more accurate and conservative than CT in management of calcified canals.

Optimizing spin dressing sensitivity for the nEDMSF experiment

Abstract nEDMSF aims to measure the neutron electric dipole moment (dn ) with unprecedented precision. In this paper we explore the experiment's sensitivity when operating with an implementation of the critical dressing method in which the angle between the neutron and Helium-3 spins (ϕ 3n ) is subjected to a square modulation by an amount ϕ d (the “dressing angle”). Several parameters can be tuned to optimize sensitivity. We find roughly 10% improvement over a previous estimate, resulting primarily from the addition of a waiting period between the π/2 pulse that initiates dn -driven ϕ 3n growth and the start of ϕ 3n modulation. We find negligible further improvement by allowing ϕ d to vary continuously over the course of a run, and no degradation resulting from the addition of an in situ background measurement into each ϕ 3n modulation sequence. A complete simulation confirms a 300 live-day sensitivity of σ = 1.45×10-28 e ·cm. At this level of sensitivity, σ ϕ 3n 0 = 1 mrad precision on the initial n/3He angle difference is not negligible.

Correction Method for Deviations in Phase Angle for PMUs at Both Ends of a Transmission Line With Unknown Parameters

Correction Method for Deviations in Phase Angle for PMUs at Both Ends of a Transmission Line With Unknown Parameters

Enhanced constant extinction angle control for subsequent commutation failure in LCC‐HVDC

AbstractTo mitigate subsequent commutation failure (SCF) in line‐commutated converter‐based high‐voltage direct current transmission systems, the response and limitations of the control system are analysed. The results reveal that due to the prolonged negative deviation of the extinction angle during recovery, the integral output of the proportional–integral controller in constant extinction angle (CEA) significantly reduces the advanced firing angle order, even below normal operating angle. This directly leads to a delayed transition between control strategies and diminishes the effectiveness of CEA. Furthermore, the influence of fault severity, fault type, and AC system strength on SCF is examined. Based on these findings, an enhanced CEA control method to suppress SCF is proposed. By setting an expected firing angle and adaptively adjusting the integral parameter, the control strategy switching moment can be advanced, improving the CEA's control margin and enhancing capability. Moreover, introducing a notch filter reduces firing angle fluctuations and strengthens CEA's ability to suppress SCF. Finally, the theoretical analysis and the effectiveness of the proposed optimization method are validated.

Real-time, accurate, and open source upper-limb musculoskeletal analysis using a single RGBD camera — An exploratory hand-cycling study

Biomechanical biofeedback may enhance rehabilitation and provide clinicians with more objective task evaluation. These feedbacks often rely on expensive motion capture systems (∼$100000), which restricts their widespread use, leading to the development of computer vision-based methods. These methods are subject to large joint angle errors, considering the upper limb, and exclude the scapula and clavicle motion in the analysis. Our open-source approach offers a user-friendly solution for high-fidelity upper-limb kinematics using a single consumer-grade depth-sensing camera (∼$500) and includes semi-automatic skin marker labeling. Real-time biomechanical analysis, ranging from kinematics to muscle force estimation, was conducted on eight participants performing a hand-cycling motion to demonstrate the applicability of our approach on the upper limb. Markers were recorded by the depth-sensing camera and an optoelectronic camera system, considered as a reference. Muscle activity and external load were recorded using eight electromyography sensors and instrumented hand pedals, respectively. Bland-Altman analysis revealed significant agreements in the 3D markers’ positions between the two motion capture methods, with errors averaging 3.3 ± 3.9 mm. The error propagation was low for the biomechanical analysis, with joint angle differences, for example, below 5° when comparing both systems. Biofeedback from the depth-sensing camera was provided at 68 Hz. Our study introduces a novel method for using a depth-sensing camera as a low-cost motion capture solution. Results from healthy participants suggest its potential for accurate kinematic reconstruction and comprehensive upper-limb biomechanical studies. Further investigation is needed to explore its clinical applications in pathological populations.

Ethnic Differences in Tweed’s Facial Triangle: A Comparative Study between Sudanese and the Major Racial Classes

Aim: This study evaluated Tweed’s facial triangle in various racial groups, including Sudanese, Black African, Black American, East Asian, and Caucasian populations with normal occlusion. Material and Method: Using 29 cephalometric radiographs from Sudanese patients aged 18-25 with class I malocclusion. Result: The analysis revealed significant differences in facial angles among these groups. Notably, increased proclination of lower incisors was observed in Sudanese, Arabs, East Asians, and African-descended populations. Conclusion: The findings highlight the importance of incorporating ethnic-specific cephalometric norms into orthodontic practice for accurate diagnosis and effective treatment planning.

Numerical and experimental investigation on vortex control and sedimentation suppression in a Y-shaped diversion channel with circular inlet tanks

A sudden angle change between the Y-shaped diversion channel and the inlet tank of the circular pump station often leads to boundary layer separation and large vortex formation. These flow patterns can cause significant sediment deposition in sediment-laden rivers, reducing pump efficiency. A mixture model is introduced to describe water-sediment two-phase flows. Simulation results analyze vortex characteristics and formation mechanisms, and evaluate potential sediment deposition areas. Without rectification, vortex areas cause significant sediment migration towards the sidewalls of the Y-shaped diversion channel and pump inlet. Diversion measures like sills and pressure plates are introduced to reduce flow vortices. Results show that sills generally optimize flow structures. Sills in the main Y-shaped diversion channel outperform those in other channels in terms of optimization. Pressure plates also optimize flow structures. Vortex structure and position are closely related to the distance between the pressure plate and the circular intake tank. Optimized measures with pressure plates significantly reduce the flow deviation angle and improve flow velocity uniformity. Numerical simulation accuracy is validated through experiments. Results reveal the formation mechanism of adverse vortices and their sedimentation effects, which are detrimental to pump stations. The proposed rectification scheme provides theoretical support for optimizing pump station operation.

Behavior of a mobile robot with symmetrical structure of mecanium wheels when movement along a curvolinear trajectory

The article presents a comparative analysis of two variants of symmetrical placement of omnidirectional mecanum wheels in a mobile robot. The modeling of the mobile robot behavior with two symmetrical variants of mecanum wheel arrangement along curvilinear trajectories in the MATLAB Simulink environment is considered. Graphs of the robot center trajectories in the X–Y axes are obtained for two variants of symmetrical mecanum wheel configurations when moving along the trajectories of a lemniscate, ellipse, hypotrochoid, and track. Dependences of the robot position errors in the X–Y axes on time are obtained for two variants of wheel topologies when moving along four trajectories. Dependences of the robot body rotation angle deviation on time are analyzed for two variants of wheel topologies when moving along four curvilinear trajectories. The comparative analysis made it possible to give recommendations on movement along the ellipse and lemniscate, which are characterized by smaller position errors and deviations in the rotation angle compared to more complex curves.