Axis Angle Research Articles

Does the Lens Deflection Angle Affect Laparoscopic Camera Navigation?

Background: In laparoscopic surgery, a 30° lens is frequently used to obtain a wider field of view. However, it is difficult for inexperienced surgeons to maintain the horizontal state of the image in laparoscopic camera navigation (LCN). If there is a great deviation in the camera's horizontal axis, it may result in ambiguous anatomical recognition, which could impair patient safety. Scientific assessment of the degree of camera's horizontal axis deflection in camera holders with differing proficiencies is necessary for improving novice surgeons' fundamentals of laparoscopic surgery. This study aims to develop an evaluation and training system based on the deflection angle (refers to the change in the angle of the camera axis from its preset vertical position) and assess its potential value in the training and clinical application of laparoscopic surgery. Methods: A total of 15 postgraduates without laparoscopic surgery experience and 15 skilled senior attending physicians with an experience in more than 50 cases of laparoscopic surgery were recruited. The participants completed an LCN exercise. An inclinometer module was used to measure the camera's horizontal axis deflection angle and the difference in the deviation angle was compared between the two groups. Results: A deflection angle greater than ±15° was found in 57.98% and 31.76% of participants in the novice group and skilled group, respectively, whereas a deflection angle greater than ±30° was found in 18.4% and 7.58% of participants in the novice group and the skilled group, respectively. The thresholds (we designate 15°, 30°, 45°, and 60° as the checkpoints) for all angles were significantly different for the two groups. Conclusions: There was a significant difference in the technique of maintaining the camera's horizontal axis within an acceptable range between the novice and the skilled participants. Training that focuses on this deflection angle may be helpful for novice camera holders.

Morphological data of the superior vena cava predicted by multiple linear regression equations

This study explores the main surface markers in the hemodialysis puncture catheterization pathway and the relative spatial position of venous vessels in the puncture results, providing data support for venous puncture. Seventy cadavers were studied; angles of vertical axis with superior vena cava, left and right brachiocephalic vein at the confluence and circumference of superior vena cava were the primary parameters. Bivariate correlation analysis was used to determine in relation to other body parameters, and a regression equation was also obtained. The angle of the vertical axis with the superior vena cava at the confluence was linearly correlated with the distances between the coracoid processes and the jugular notch to coracoid processes. The angle of the vertical axis with left brachiocephalic vein was linearly correlated with the thickness of thorax and the length from the upper pericardial margin to the confluence. The angle of the vertical axis with right brachiocephalic vein was correlated with clavicular midline length, acromial distance, intersection point of clavicle to clavicular midline, confluence to clavicular midline, superior edge of the blood vessels to superior edge of clavicle at the right intersection, and superior edge of pericardium to confluence. There is a linear relationship between the superior vena cava circumference and the distance from the superior vena cava to the aorta. A number of parameters influence angles of the vertical axis with superior vena cava, left and right brachiocephalic veins and the superior vena cava circumference which can provide guidance for intubation.

Can Cadaver Testing Replicate In Vivo Kinematics of Total Knee Arthroplasty?

Whether the kinematics of cadaveric knees recreate those of the patient's knees after total knee arthroplasty (TKA) remains unknown. This study compared in vivo and in vitro fluoroscopic kinematics of knees after TKA during knee bending using the same implant design. Patients who had undergone cruciate-retaining and cruciate-substituting total knee arthroplasty (CR-TKA and CS-TKA) did squatting motions. Fresh-frozen human cadaveric knees were tested under dynamic closed-chain knee extension in an Oxford knee rig. Fluoroscopic kinematics were measured in vivo and in vitro using a 2-dimensional to 3-dimensional registration technique. The axial rotation angle and anterior-posterior translation of medial and lateral contact points of the femoral implant relative to the tibial implant was evaluated in each flexion angle. No notable differences in the axial rotation angles were found between in vivo and in vitro measurements in both CR-TKA and CS-TKA. In early flexion, the medial and lateral contact points in cadaver knees were located more posterior than those in in vivo after CR-TKA. From early flexion to high flexion, the medial and lateral contact points in cadaver knees were located more posterior than those in in vivo after CS-TKA. The axial rotation angle of cadaveric knees in the Oxford knee rig was similar to that measured in vivo after TKA. However, the anterior-posterior location of the femoral implant in cadaver knee was more posterior than that in in vivo knees after TKA.

High efficiency high brightness spectral beam combination based on an ultra-broad area laser diode stack

We demonstrate what we believe to be for the first time a high efficiency, high brightness laser source by external cavity spectral beam combination (SBC) in the fast axis based on the 1000 µm ultra-broad area laser diode (UBALD). Regarding the slow axis beam quality of UBALD, we propose a feedback model of the slow axis angle energy distribution in the oscillation process. By adding a structure with a filtering effect in the external cavity, both theory and experiment show that the beam quality of the slow axis can be effectively improved. With a 25-emitter UBALD stack, an SBC maximum CW output power reaches up to 730.6 W with an electro-optical efficiency of 63.7%. The SBC spectrum consists of 25 discrete peaks with a central wavelength of ∼967 nm and an overall spectrum width of 27.2 nm. The beam quality M2 values along the fast and slow axes are measured to be 5.2 and 22.8 at an output power of 623.4 W, corresponding to a brightness as high as 562.3 MW/(cm2•sr).

Effect of tip injection on performance of highly loaded helium compressor in high-temperature gas-cooled reactor

As one of the representatives of the fourth-generation advanced nuclear reactor, the continuous development and application of high-temperature gas-cooled reactor (HTGR) technology has promoted the technical progress of the whole nuclear energy field. Helium compressor is one of the core components of HTGR. The highly loaded helium compressor effectively solves the disadvantages of the low single-stage pressure ratio and numerous stages of the traditional helium compressor. But it also brings a more complex tip-leakage flow. Tip injection, which is an active control method, can effectively control the tip clearance leakage and inhibit the development of the leakage vortex. This paper analyses the effects of axial deflection angle and injection pitch angle on the rotor performance of a highly loaded helium compressor via numerical simulation and validates them via experiment. Results show that the leakage vortex can be blown to the pressure surface of the adjacent blade by proper axial deflection angle to reduce the vorticity of the leakage vortex. The injection pitch angle directly affects the intensity of the leakage vortex during its initiation and development. When the axial deflection angle is 60° and the injection pitch angle is 20°, the adiabatic compression efficiency and total pressure ratio increase by 0.554 % and 0.160 % respectively under the design condition, and by 0.822 % and 0.162 % respectively under near-stall conditions.

Experimental and analytical analysis of tapered optical fiber tweezers

This paper presents the experimental development and analytical modeling of cost-effective Optical Fiber Tweezers fabricated from tapered optical fibers. The optical fiber tweezers use a 976 nm pump laser to obtain the multimode effect in conventional silica optical fibers (since it is below the cutoff wavelength). In addition, the taper is performed in the optical fiber using a conventional optical fiber splicing machine, where the diameter of the taper can be controlled by simply changing the taper parameters. The simplified analytical model is performed for the analysis of the intensity and optical power variations of the fiber tip as a function of the axial distance and angle between the fiber tip and the region of interest as well as the attractive (or repulsive) force on the optical field. In this case, 3 optical fiber tweezers were fabricated with different tip diameters and tested as a function of two set of particle specimens, one using polystyrene with 17 μm diameter and the other with glass particles of 3.2 μm. Results show that the repulsive forces presented in the force estimation model do not occur as expected, where all optical fiber tweezers presented higher attractive forces than the expected by the analytical model. Such differences can be related to the photothermal effect, which may have led to an unbalanced relation between its sub-effects known as thermophoresis and negative photophoresis. The results also indicated a high dependency of the attractive forces as a function of the optical fiber tip diameter, where the fiber tweezer with smallest diameter presented a fivefold and fourfold increase in the optical force when compared with the fiber tweezer with highest diameter for polymer and glass particles, respectively. Therefore, the proposed approach is a cost-effective method with relatively large control of the optical fiber tip for the optical actuator of micro-scale particles.

Accuracy of Combined High Tibial Slope Correction Osteotomy Using 3-Dimensional-Planned Patient-Specific Instrumentation.

If an increased posterior tibial slope (PTS) and concomitant unicompartmental osteoarthritis are present, a simultaneous sagittal (slope) and coronal correcting high tibial osteotomy has been recommended. However, no study has investigated the accuracy of such combined high tibial slope correction osteotomies. (1) To report the accuracy of navigated high tibial slope correction osteotomies using patient-specific instruments (PSI) and (2) to analyze the influence of an open wedge osteotomy (OWO) versus a closed wedge osteotomy (CWO) and the hinge axis angle (HAA) on the accuracy of the PTS correction. Cohort study; Level of evidence, 3. All PSI PTS-reducing osteotomies performed at 1 institution between 2019 and 2022 were reviewed. Three-dimensional (3D) accuracy was defined as the mean absolute 3D angular difference between the planned and achieved surgical correction (in degrees) in 3D models of computed tomography data. The influence of OWO versus CWO and the HAA on the reported accuracy was analyzed and a cutoff defined using receiver operating characteristic curve analysis. Eighteen patients who underwent a slope-reducing CWO (n = 9) or OWO (n = 9) were included. The 3D accuracy for PTS was 2.3°± 1.1° (mean ± SD), with CWO being more accurate than OWO (1.4°± 0.9° vs 3.1°± 0.6°; P < .01). Accuracy strongly correlated with the HAA (r = 0.788; P < .01). An HAA >38.9° predicted a PTS error >2° (odds ratio, 1.12 [95% CI, 1.04-1.20; P = .004]; area under the curve, 0.95 [95% CI, 0.89-1.00; P < .001]) corresponding to a coronal/sagittal correction of 0.8:1. Slope-reducing osteotomy can accurately be achieved using PSI. CWO demonstrated an increased accuracy when compared with OWO, which strongly depended on the HAA. With an aim of combined PTS and coronal correction, CWO should be considered the primary choice for accurate slope reduction with a coronal/sagittal correction cutoff of 0.8:1 (HAA, 38.9°).

Experimental and numerical analysis of geometry on joint strength in GFRP-aluminum alloy adhesive joints

Enhancing the bonding strength between composites and metals is one of the urgent challenges that needs to be addressed. One of the methods to improve the strength of adhesive joints is to change the geometry of the joints. In this paper, four different types of aluminum alloy sleeves were developed by designing grooves with varying angles and shapes. Glass fiber reinforced polymer rods were adhesively bonded to these sleeves, resulting in the preparation of five different types of adhesive joints, including a conventional structure. The mechanical performance and failure mechanisms of these joints were analyzed experimentally and numerically. The results indicate that, compared to conventional adhesive joints, the load-bearing capacity of the four designed adhesive joints has been significantly improved, with a maximum increase of 49.6% and a minimum increase of 35.6%. The axial angle of the groove structures designed within the joint is a factor that influences the ultimate load capacity of the joint. Furthermore, the shear stress in the adhesive layer is identified as the primary cause of adhesive layer failure. The designed mechanical interlocking structures can not only increase the interfacial bonding force between the adhesive layer and the substrate but also delay the complete failure of the adhesive layer, thereby improving the load-bearing strength of the joint. This work is expected to provide new insights for the design of composite and metal joints.

Novel technique for achieving the under-correction of native tibial varus in calipered restricted kinematically aligned total knee arthroplasty - A validation study

PurposeRestricted kinematic alignment (rKA) TKA is relatively newer technique for achieving an overall under-corrected limb alignment. The present study aims to provide an easy and reproducible technique for achieving calipered rKA-TKA (crKA-TKA) using routine instrumentation. MethodA prospective study was conducted including 30 patients (30 knees). All patients underwent crKA-TKA by the same surgeon. Pre-operatively all patients underwent long film standing radiographs, and coronal angles were measured to plan tibial bony cuts and the femoral axis angle (FAA) to restore tibial varus under correction and native distal femoral anatomy, respectively. Intra-operatively while taking tibial cuts, the alignment rod was noted to be always pointing towards the “third metatarsal” of the ipsilateral foot. Results30 patients underwent total knee replacement with crKA technique. Angular corrections were satisfactory with all patients reaching the target MPTA of 87.48 ± 0.78 and LDFA of 90.301 ± 2.66 as planned, with an overall under-corrected limb alignment. HKA was achieved within a target of < ± 3 degrees of the native knee (3.56 ± 1.29). Post-operative radiological parameters were checked by two separate observers with excellent intra-class correlation coefficients. ConclusionThe present study validates a novel intra-operative technique of confirming an under-corrected native tibial varus while performing crKA-TKA. The radiological outcomes of the study confirm that with careful pre-operative planning, coronal angular targets were easily achievable with very less outliers. Study further establishes that this method of calipered technique in rKA-TKA using routine digital templating software and standard instrumentations is an alternative method of executing rKA. Level of evidenceIV, Prospective case series.

Effect of filter type on the topology of the eigenframe of the subfilter stress tensor and interscale energy transfer

Effects of different filter kernels, namely, spectral cutoff ( $\mathcal {S}$ -filter) and Gaussian ( $\mathcal {G}$ -filter), on the geometrical properties of the subfilter stress (SFS) tensor and the filtered strain-rate (FSR) tensor are analysed in a forced homogeneous isotropic turbulence. Utilizing the Euler angle–axis methodology, it is observed that despite similar mean behaviour, the eigenframe alignment between SFS and FSR exhibits a non-trivially different statistical distribution for two different filters. Besides the eigenframe alignment, the eigenstructure of these tensors is also investigated. It is found that in contrast to the eigenstructure of the FSR which does not show sensitive dependence on the filter kernel type, the eigenstructure of the SFS tensor is significantly influenced by the filter type. Subsequently, the impact of different filter kernels on the subfilter energy flux (SFEF) is investigated. It is observed that energy transfer in $\mathcal {G}$ -filtering is preferably distributed over the forward region, whereas for the $\mathcal {S}$ -filter, the SFEF is more evenly distributed over both forward–backward regions, leading to a heavy energy transfer cancellation. Additionally, by decomposing the SFEF into different partial energy fluxes, it is found that the impact of the $\mathcal {S}$ -filtering on the eigenstructure of the SFS leads to the amplification of the backward energy transfer. Conversely, the $\mathcal {G}$ -filtering amplifies the forward energy transfer by producing a more pronounced alignment between the contractive–extensive eigenvectors.

Geographically-Informed Modeling and Analysis of Platform Attitude Jitter in GF-7 Sub-Meter Stereo Mapping Satellite

The GF-7 satellite, China’s inaugural sub-meter-level stereoscopic mapping satellite, has been deployed for a wide range of applications, including natural resource investigation, environmental monitoring, fundamental surveying, and the development of global geospatial information resources. The satellite’s stable platform and reliable imaging systems are crucial for achieving high-quality imaging and precise attitude measurements. However, the satellite’s operation is affected by both internal and external factors, which induce vibrations in the satellite platform, thereby affecting image quality and mapping accuracy. To address this challenge, this paper proposes a novel method for constructing a satellite platform vibration model based on geographic location information. The model is developed by integrating composite data from star sensors and gyroscopes (gyro) with subsatellite point location data. The experimental methodology involves the composite processing of gyro data and star sensor optical axis angles, integration of the processed data through time-matching and normalization, and denoising of the integrated data, followed by trigonometric fitting to capture the periodic characteristics of platform vibrations. The positions of the satellite substellar points are determined from the satellite orbit data. A rigorous geometric imaging model is then used to construct a vibration model with geographic location correlation in combination with the satellite subsatellite point positions. The experimental results demonstrate the following: (1) Over the same temporal range, there is a significant convergence in the waveform similarities between the gyro data and the star sensor optical axis angles, indicating a strong correlation in the jitter information; (2) The platform vibration exhibits a robust correlation with the satellite’s geographic location along its orbit. Specifically, the model reveals that the GF-7 satellite experiences the maximum vibration amplitude between 5° S and 20° S latitude during its ascending phase, and the minimum vibration amplitude between 5° N and 20° N latitude during the descending phase. The model established in this study offers theoretical support for optimizing satellite attitude and mitigating platform vibrations.

Differences in spinal axial rotation angles during the lumbar-locked rotation test between hyper and normal thoracic rotation groups: A cross-sectional study.

Trunk rotation is important in many sporting activities The thoracic spine has reciprocal relationships with the lumbar and pelvic spines, such that reduced flexibility in the lumbar or thoracic spine can lead to abnormal patterns of trunk movement and pain. However, few studies have investigated the relative trunk rotation mobilities of the thorax, lumbar, and pelvis. To compare thoracic, lumbar, and pelvic rotation angles during the lumbar-locked rotation test between hyper and normal thoracic rotation groups. Thirty-two young, active participants were enrolled in this study. After the attachment of inertial measurement units at the T1, T7, T12, L3, and S2 levels, the participants were required to stand in a comfortable upright posture for 5s to allow postural measurements before performing the lumbar-locked rotation test. The participants were then divided into hyper thoracic rotation and normal thoracic rotation groups based on T1 angle measurements obtained during the lumbar-locked rotation test. The hyper thoracic rotation group had significantly higher thoracic rotation angles on both the right (p< 0.05) and left (p< 0.05) sides compared with the normal thoracic rotation group. Furthermore, we observed flat lumbar lordosis in the hyper thoracic rotation group compared with the normal thoracic rotation group, particularly in the lower lumbar region in standing posture. Our data suggest that evaluations of thoracic mobility should consider relative thoracic, lumbar, and pelvic motions, rather than the T1 angle alone. This study provides a basis for health professionals to evaluate movement dysfunctions associated with thoracic hypermobility.

Temperature Distribution of Frozen Wall Formed by Irregular Hole Arrangement During In Situ Repair of Underground Shield Machine

In order to study the development law of the irregular hole freezing temperature field, combined with the shield solution project of the Nanjing Water Supply Corridor, the distribution characteristics and influencing factors of the irregular freezing temperature field of the river bottom shield machine are studied by numerical simulation. The following conclusions are obtained: (1) The extension length of the outer ring pipe is correlated approximately positively with the thickness and average temperature of the freezing wall at the bottom of the cup. The thickness increases by 0.25 m, and the average temperature decreases by 1.25 °C for every 1 m increase in the extension length. (2) The intersection time decreases logarithmically with the increase in the extension length of the outer ring tube. (3) As the ratio of the axial angle between the two adjacent tubes in the weak area of the outer ring tube becomes larger, the temperature of the weak point in the center of the two tubes increases approximately linearly. The midpoint temperature of the two tubes increases by 3.3 °C for every 1 increase in the angle coefficient. (4) With the increase in the opening angle of the inner ring hole, the thickness and average temperature change, respectively, at 150 d are not more than 0.15 m and 0.6 °C. The results show that under the irregular freezing form, the angle and length of the outer ring pipe have a great influence on the temperature field, and the angle of the inner ring pipe has little influence on the final distribution of the temperature field. The average temperature and the temperature distribution of the weak points show a trend of decreasing first and then increasing along the shield advancing direction, reaching a minimum near the cutterhead.

Developments on friction surfaced coatings for corrosion, wear-resistant and composite

Friction surfacing is the most recent technology applied in surface engineering for developing surface materials. It is a solid-state technique employed to coat one material over another material in order to reconstruct the worn-out parts, to enhance protection from ware and corrosion, to develop mechanical features and composite materials.This is an environmentally-safe process in which a consumable rod is deformed plastically and forms a deposit of viscoelastic material over the substrate. The thickness and properties of the layer can be controlled by the rotational speed, axial downwards force, horizontal motion, time and tilt angle. Different materials have been taken in friction surfacing for deposition. The friction surfaced coating is also modified in different way according to requirement. Friction surfacing has been significantly applied to industrial applications. This paper reviews thoroughly the properties and microstructure of friction surfaced coating using different operating parameters and processes, focusing alternative technology on future research.

Digital Cephalometric Analysis: Unveiling the Role and Reliability of Semi-automated OneCeph, Artificial Intelligence-Powered WebCeph Mobile App, and Semi-automated Computer-Aided NemoCeph Software in Orthodontic Practice.

Background Cephalometric analysis is essential in orthodontic diagnosis and treatment planning. With the emergence of digital tools for cephalometric analysis such as OneCeph, WebCeph, and NemoCeph, there is growing interest in their reliability compared to traditional manual tracings. This study aimed to compare the reliability of these digital tools with manual tracings in doing cephalometric analysis. Methodology Cephalometric radiographs from a diverse patient population were analyzed using OneCeph (NXS, Hyderabad, India), WebCeph (AssembleCircle Corp., Republic of Korea), NemoCeph (Nemotec, Madrid, Spain), and manual tracings by experienced orthodontists. Interobserver reliability and agreement with manual tracings were assessed using the intraclass correlation coefficient (ICC). Results The comparison of cephalometric measurements using the four methods - manual, OneCeph, WebCeph, and NemoCeph - revealed significant differences in the Sella-Nasion to Point A angle (SNA) (P = 0.002) and angle of difference between Sella-Nasion to Point A angleand Sella-Nasion to Point B angle(ANB) (P<0.001). Specifically, WebCeph produced significantly higher SNA measurements than manual tracing, while NemoCeph, OneCeph, and WebCeph yielded higher ANB measurements than manual tracing. There were no significant differences in other measurements, including Sella-Nasion to Point B angle (SNB), Nasion to Point A (N to Pt A), Nasion to Point B (N to Pt B), Gonion-Gnathion to Sella-Nasion angle (Go-Gn to SN), Lower Anterior Facial Height (LAFH), Y-axis (growth axis angle), facial axis, the sum of posterior measurements, and various angular and linear distances [1 to NA, 1 to SN, 1 to NB, 1 to Apog, Incisor Mandibular Plane Angle (IMPA), Sella to Upper Lip (S to UL), and Sella to Lower Lip (S to LL)]. The reliability analysis indicated a strong internal consistencywith Cronbach's α values of 0.811 for manual vs. NemoCeph, 0.859 for manual vs. OneCeph, and 0.861 for manual vs. WebCeph, and good agreement in the ICC(P<0.001). Conclusion OneCeph, WebCeph, and NemoCeph demonstrate promising reliability for cephalometric analysis. However, the results should be interpreted with caution, considering the limitations of digital tools. Ongoing research and collaboration among developers, researchers, and clinicians are essential to validate these the performance of these tools and improve their clinical applicability.

Introducing Angle B: A Novel Quantitative Approach for Sagittal Alignment Reduction in Atlanto-Axial Dislocation Surgery.

This study aims to establish a quantitative relationship between cervical lordosis (CL) and the rotation angle of the axis for the surgical reduction of atlantoaxial dislocation (AAD) and to explore the potential applications of this relationship in preoperative planning and selection of surgical techniques. To construct the correlation between horizontal gaze and location of axis, we introduced the angle B, defined as the angle between the Frankfort horizontal line and the extension line of the posterior edge of the axis, and explored its application in surgical planning. We retrospectively analyzed imaging data from computed tomography of 23 AAD patients who had undergone posterior reduction and fixation. Theoretical equations were deduced through a series of angular transformations, and linear regression analysis was used to validate our findings. Our results showed a strong linear relationship between the change in CL (ΔCL) and the change in B(ΔB) (y=-1.0402x, coefficient of determination R²=0.978, P<0.001), supporting our deduction that ΔCL=ΔB. Furthermore, we found that the rotation angle of the axis (angle D) was equal to ΔCL. By resolving the atlantoaxial interval into the vertical dimension (h) and horizontal dimension (d), we could calculate the maximum vertical and horizontal distance that the axis could move theoretically according to a patient's maximum ΔCL. This finding supports our theory that the introduction of angle B can provide more precise preoperative planning and surgical technique selection for patients with AAD. By introducing angle B and deducing the equation ΔB=ΔCL=D, we have provided an innovative tool for preoperative planning and surgical technique selection for patients with AAD. This equation not only helps surgeons achieve more precise and effective surgical reductions but also emphasizes the important role of angle B in surgical planning.

Evaluating proximal ulnar morphology in relation to the humeral flexion-extension axis

AimThe study aimed to evaluate the 3D relationship between the plane of the posterior surface of the olecranon, a newly defined plane through the ridge of the greater sigmoid notch, and the ulno-humeral flexion-extension axis (FE-axis), respectively. Methods24 healthy left elbows were CT-scanned and 3D segmented. First, a Cartesian ulnar coordinate system (UCS) was determined. Next, several anatomical landmarks were identified. The UCS and landmarks were assessed for repeatability and reproducibility. The orientation of the posterior surface and the plane through the greater sigmoid notch was evaluated relative to the anatomical FE-axis. ResultsBoth the UCS and the landmarks were considered repeatable and reproducible. In the axial plane, the mean angle between the posterior surface and the FE-axis was 3° (SD: ± 5 °, 95%CI: [-6°;12°]) external rotation. The mean axial angle between the greater sigmoid notch and the FE-axis was 88° (SD: ± 3°, 95%CI: [83°; 94°]) external rotation. ConclusionsThis study concludes that the angulation between the posterior plane surface and the FE-axis is highly variable (95% CI range: 18°). The plane through the ridge of the greater sigmoid notch of a healthy proximal ulna could provide a more reliable anatomical landmark to estimate the position of the elbow FE-axis compared to the posterior surface (95% CI range: 11°).

Study on lubrication characteristics of multi-layer structure hinge under the influence of clearance dynamic

This paper presents a methodology for investigating the lubrication characteristics of multi-layer structural mechanical hinges based on clearance dynamics. By multi-layer hinged structures, we mean the four mediums: the journal, lubricating oil film, bearing sleeve, and connecting rod. Initially, a dynamic model that incorporates clearance is established using the automatic dynamic analysis of mechanical systems, revealing that the primary contact area is located between 50° and 70°. Subsequently, a lubrication model for the multi-layer structural mechanical hinge is constructed using ANSYS FLUENT software, which demonstrates the effects of critical parameters—such as contact angle, sleeve installation angle, inlet pressure, and shaft neck speed—on lubricant flow, pressure, and void fraction. The findings indicate that the motion offset angle significantly influences the pressure distribution within the oil film area, with high-pressure and low-pressure zones oriented counterclockwise and clockwise, respectively, relative to the offset angle axis. Furthermore, as the distance between the offset angle and the oil inlet increases, the volume fraction of cavitation decreases from 1.77% to 1.16%. When the sleeve installation angle aligns with the motion offset, the volume fraction of cavitation reaches 1.9%. Conversely, when the assembly angle aligns the oil inlet hole with the injection hole, the volume fraction of cavitation is minimized to 0.36%, resulting in an approximate performance improvement of 81.11%. This study provides a theoretical foundation for optimizing the lubrication design of multi-layer structural mechanical hinges and offers substantial guidance for the lubrication of mechanical hinges.

Exploring cortical trajectory of the lumbar vertebrae: a morphometric study in dry skeletons: a retrospective study in Thailand.

Retrospective cohort study. This study aimed to explore the morphometry of the Thai lumbar vertebrae. The cortical bone trajectory (CBT) is a novel approach for vertebral screw fixation aimed at addressing spinal instability associated with spinal disorders. The morphometry of the lumbar vertebrae is crucial in tailoring screw design for each CBT application, given the significant variations in optimal screw sizes, lengths, and angles among populations. A total of 300 dried lumbar columns were used to measure the pedicle height (PH) and width (PW), length for cortical bone trajectory (LCT), cephalad screw angle (CSA), axial cortical bone trajectory angle (ACA), and possible cortical zones for the CBT. The following average values were calculated: PH in L1, 15.09±1.44 mm; PW in L5, 16.96±2.42 mm; LCT in L3, 35.75±2.61 mm; CSA in L1, 20.85°±2.30°; and ACA in L5, 21.83°±2.49°. Women generally had shorter PH and PW than men, with significant differences across lumbar levels. The LCT was significantly shorter in women and was notably different between the left and right sides. The CSA and ACA varied significantly between sexes and sides, with specific lumbar levels showing wider angles in one sex over the other. The most common cortical zones for screw tips were Z3 and Z10, with high incidences across all lumbar levels. This study presents detailed lumbar vertebral morphometry data specific to the Thai population. The results are essential for CBT application in screw fixation procedures. This information will contribute to the production of optimally designed screws for Thai patients in the future.

Dosimetric optimization for dynamic mixed beam arc therapy (DYMBARC).

Non-coplanarity and mixed beam modality could be combined to further enhance dosimetric treatment plan quality. We introduce dynamic mixed beam arc therapy (DYMBARC) as an innovative technique that combines non-coplanar photon and electron arcs, dynamic gantry and collimator rotations, and intensity modulation with photon multileaf collimator (MLC). However, finding favorable beam directions for DYMBARC is challenging due to the large solution space, machine component constraints, and optimization parameters, posing a highly non-convex optimization problem. To establish DYMBARC and solve the pathfinding challenge by employing direct aperture optimization (DAO) to determine the table angles and gantry angle ranges of photon and electron arcs for different clinically motivated cases. The method starts by generating a grid of beam directions based on user-defined resolutions along the gantry and table angle axes for each beam quality considered. Beam directions causing collisions or entering through the end of CT are excluded. For electrons, a fixed source-to-surface distance of 80cm is used to reduce in-air scatter. Electron beam energies with insufficient range to reach the target or beam directions impinging on the table before reaching the patient are excluded. The remaining beam directions form the pathfinding solution space. Promising photon and electron MLC-defined apertures, with associated monitor unit (MU) weights, are iteratively added using a hybrid-DAO algorithm. This algorithm combines column generation to add apertures and simulated annealing to further refine aperture shapes and weights. Apertures are added until the requested number of paths are formed and the user-defined maximum total gantry angle range is reached. Paths are resampled to a finer gantry angle resolution and subject to DAO for simultaneous optimization of beam intensities along the photon/electron arcs. Subsequent final dose calculation and MU weight reoptimization result in a deliverable DYMBARC plan. DYMBARC plans are created for three clinically motivated cases (brain, breast, and pelvis) and compared to DYMBARC variants: colli-DTRT (dynamic collimator trajectory radiotherapy) using non-coplanar photon arcs; and Arc-MBRT (mixed beam radiotherapy) using photons and electrons but restricted to coplanar setup. Additionally, a manually defined volumetric modulated arc therapy (VMAT) setup serves as a reference clinical technique. Dose distributions, dose-volume histograms, and dosimetric endpoints are evaluated. Dosimetric validation with radiochromic film measurements (gamma evaluation, 3% / 2mm (global), 10% dose threshold) is performed on a TrueBeam system in developer mode for one case. While maintaining similar target coverage and homogeneity, DYMBARC reduced mean doses to organs-at-risk compared to VMAT by an average of 3.2, 0.5, and 2.9Gy for the brain, breast, and pelvis cases, respectively. Similar or smaller mean dose reductions were observed for Arc-MBRT or colli-DTRT, compared to VMAT. Electron contributions to the mean planning target volume dose ranged from 2% to 34% for DYMBARC and from 11% to 40% for Arc-MBRT. Measurement validation showed>99.7% gamma passing rate. DYMBARC was successfully established using a dosimetrically optimized pathfinding approach, combining non-coplanarity with mixed beam modality. DYMBARC facilitated the determination of photon and electron contributions on a case-by-case basis, enhancing more personalized treatment modalities.