Normal Angle Research Articles

Association of Normal vs Abnormal Meary Angle With Hindfoot Malalignment and First Metatarsal Rotation: A Short Report.

Recent work has reported a significant association between first metatarsal (M1) rotation and hindfoot alignment, with the finding of a moderate association between the calcaneal moment arm (CMA) and 2 M1 pronation angular measures: Saltzman (r = 0.641, P < .01) and Kim (r = 0.615, P < .01). The aim of the current post hoc investigation was to determine if this association is related with Meary angle. We reanalyzed previously published data set separating patients into 2 groups: (1) those with normal Meary angle (n = 128) and (2) those with abnormal Meary angle (n = 147). Hindfoot alignment and M1 rotation were measured on weightbearing computed tomography. Statistical analyses were performed to evaluate for association between these variables among the groups. The correlation between CMA and M1 rotation of the entire cohort was r = 0.577 (Saltzman ankle) and r = 0.540 (Kim angle). For the subset with a normal Meary angle, this association was negligible (Saltzman and Kim angles, r = 0.194 and 0.240, respectively). Conversely, for the abnormal Meary angle subset, the association was substantial (Saltzman and Kim angles, r = 0.733 and 0.675, respectively). Patients presenting with an abnormal Meary angle and hindfoot deformity have a high likelihood of manifesting a proportionate degree of M1 rotation. Level III, Retrospective Cohort Study.

Three-Dimensional Morphometric Characterization of Femoral Cam Lesions: Quantifying the Radial and Lateral Extents

To quantify the radial and lateral extents of femoral cam lesions in FAI patients relative to the alpha angle and correlate with clinical data. Retrospective study of 81 hips with femoral cam morphology that underwent arthroscopic surgery between 2017 and 2019. At each hour over the clockface, the alpha angle (α) (abnormal defined as > 55°), radial extent, and lateral extent of cam lesions were measured on CT. These measurements were correlated with clinical and arthroscopic data. Statistics included independent samples t-test and chi-squared test with Bonferroni correction and multivariate logistic regression. Larger α at 12:00-4:00 in males vs females (56.6-63.4° vs 44.3-58.5°, P < 0.001) and at 2:00-4:00 with elite sports participation vs without (56.7-70.9° vs 49.6-61.1°, P ≤ 0.004). Independent risk factors for radial extent beyond 12:00-3:00 were: male sex (OR 4.82, 95% CI [1.46, 15.85], P=0.010), BMI > 25 (OR 4.74, 95% CI [1.61, 14.00], P=0.005), and elite sports participation (OR 3.28, 95% CI [1.09, 9.82], P=0.034). Lateral extent increased at 1:00-4:00 in males vs females (7.8-18.6 mm vs 1.6-9.1 mm, P < 0.0001). A 16% prevalence of distal cam lesions was found at locations with normal α, resulting in underestimation of radial extent by an average of 1.7 hours. There is a positive correlation between the alpha angle, lateral extent, and radial extent of cam lesions. FAI patients who were male, participated in elite level sports, and had a BMI > 25 had larger cam lesions. A larger alpha angle is a risk factor for cartilage damage. Patients may have distal cam lesions at locations with normal alpha angles, though their significance is unknown.

Induced side-branching in smooth and faceted dendrites: theory and phase-field simulations.

The present work is devoted to the phenomenon of induced side branching stemming from the disruption of free dendrite growth. We postulate that the secondary branching instability can be triggered by the departure of the morphology of the dendrite from its steady state shape. Thence, the instability results from the thermodynamic trade-off between non monotonic variations of interface temperature, surface energy, kinetic anisotropy and interface velocity within the Gibbs-Thomson equation. For the purposes of illustration, the toy model of capillary anisotropy modulation is prospected both analytically and numerically by means of phase-field simulations. It is evidenced that side branching can befall both smooth and faceted dendrites, at a normal angle from the front tip which is specific to the nature of the capillary anisotropy shift applied. This article is part of the theme issue 'Transport phenomena in complex systems (part 2)'.

A neophyte gonioscopist's animative and videographic atlas with focal points for effective practice.

Background:Though various gonioscopy teaching platforms are available, they predominantly comprise of real time scenarios and videos. For a beginner, we suggest providing animations of the real time scenario for cognitive training; and then putting them in real time scenarios for a better concept application and practice.Purpose:This video highlights the basic tips and tricks needed to perform gonioscopy with metaphorical conceptual learning matching the 2D and 3D animations with real time scenarios.Synopsis:Simple and practical scenarios with technical details on how to perform gonioscopy and various challenges are shown. All the animations and videos are created by us, tailored to a neophyte. The following concepts are covered: normal angle (animation versus real-time), dynamicity of the gonioscopic dates of person, methods of gonioscopy - direct and Indirect, precautions and slit lamp adjustment, bubble trouble, patient examination, iris process versus peripheral anterior synechiae (animation versus real-time), patient examination (angle viewing order) for different lens, how to remove gonioscopy lens from the eye, static versus dynamic gonioscopy, situations where gonioscopy is contraindicated, grading of the angle (with animations), clinical scenarios (pseudoexfoliation, pigment dispersion, angle recession and aniridia), and surgical scenarios (patent ostium and blocked ostium).Highlights:Multiple animations and real-time videos with focal points for effective practice are the highlights of this video.Video link: https://youtu.be/fFmPmqgdjyM

Clinical Evaluation of the Hip With Focus on Assessment of Hip Instability

Background: Hip instability is a challenging clinical diagnosis, which often overlaps with the presentation of hip impingement and/or hip dysplasia. Many factors contribute to hip instability, including acetabular undercoverage, femoroacetabular-impingement-induced instability, and soft tissue laxity. It can cause significant pain and disability, either as a primary pathology or as a complication of surgery and if untreated can ultimately lead to early osteoarthritis. Indications: Hip dysplasia is often diagnosed with an anterior-posterior pelvic radiograph. The literature has supported a normal lateral center edge angle (LCEA) as ≥25°, borderline dysplasia an LCEA of 18° to 25°, and an LCEA &lt;18° as true dysplasia, though some authors will diagnose borderline dysplasia as an LCEA of 20° to 25° and true dysplasia as an LCEA &lt;20°. In addition, there are many radiographic measurements that have been described to aid in the diagnosis of hip instability beyond LCEA, including the acetabular inclination (or Tönnis angle), the femoro-epiphyseal acetabular roof (FEAR) index, and the cliff sign. Technique Description: Hip instability can be present even in the absence of radiographic findings, and many with insufficient coverage of the femoral head do not meet the radiographic definition of dysplasia. For this reason, it is important to have an understanding of the clinical assessment that may aid in the diagnosis of hip instability. Here, we present our preferred technique for clinical examination of the hip, focusing on the assessment of hip instability. Results: While no one maneuver is sufficient to diagnose hip instability, incorporation of multiple examinations in conjunction with radiographs can help to properly diagnose the presence of hip instability. Discussion/Conclusion: Hip instability is a challenging clinical diagnosis, and many examination maneuvers have been described to assess for hip instability. In this technical note, we describe our preferred technique for clinical examination of the hip, focusing on the assessment of hip instability.

Evaluation of normal calcaneal angles in chennai population

Evaluation of normal calcaneal angles in chennai population

Hyoid Bone Position as an Etiological Factor in Mandibular Divergence and Morphology

Objectives: The objective is to determine whether there are differences in the position of the hyoid bone at rest in natural head position in subjects with mandibular hyperdivergence and to evaluate whether there are differences in hyoid position and antegonial notch depth in mandibular hyperdivergent males and females. Methods and Materials: This is a retrospective cohort study involving a review of lateral cephalometric radiographs of 45 adult men and women with mandibular hyperdivergency. Hyperdivergency was determined by cephalometric ranges of: SN-GoGn as least +2 SD from normal, Y-axis, PP-GoGN, and gonial angle greater than +1SD from normal. A group of 45 normodivergent adults served as a control, with cephalometric ranges of: SN-GoGn within ±1 SD of normal, with only one measurement of the other three between +1 and +1.5 standard deviations. A custom digital cephalometric analysis, the Hyoid Analysis, was designed, to measure the vertical and horizontal position and inclination of the hyoid and the antegonial notch depth. Results: In hyperdivergent subjects, the posterior aspect of the hyoid is located lower and more posterior, compared to the control group, while there is no difference in position of the anterior surface of the hyoid and the antegonial notch is 0.6 mm deeper. In males, the posterior aspect of hyoid is lower by 8.5 mm, while the anterior surface is located 9.0 mm lower. In males, the hyoid is inclined more steeply than in females by 4.4 degrees and the antegonial notch is deeper than in females by 0.6 mm. Conclusions: There are differences in hyoid bone position and mandibular morphology in hyperdivergent subjects compared to normodivergent subjects and in males compared to females.

Morphometric Study of Proximal Femur and its Applications in Prosthesis Designing: A Cross-sectional Study from Western India

Introduction : The hip joint is subjected to daily stresses as it bears the weight of the upper body. Osteoarthritis of the hip may cause irreversible damage. Proximal geometry of the femur, like neck-shaft angle and torsion is important in designing prostheses for a specific population. Most of the prostheses manufacturers follow the Western parameters as there is a scarcity of data in the Indian context. Aim: To analyse the normal Neck-Shaft Angle (NSA) and torsion of the femur in the Indian population. Materials and Methods: This cross-sectional analytical study was carried out in a total of 300 dried femora (150 right and 150 left) of unknown age and gender without any defect or damage during a period of 2.6 years (June 2019 to December 2021) in Sumandeep Vidyapeeth University, Gujarat, India. The NSA and the angle of femoral torsion was measured using a Goniometer. Mean and standard deviation were calculated. Student’s t-tests was applied to ascertain the statistical difference between right and left femur. Results: The average NSA was 128.55±6.99°. The mean values were 130.70±6.03° and 126.41±7.22° on right and left sides respectively with statistically significant difference (p-value&lt;0.0001). The average femoral torsion was found to be 16.43±2.34°. On the left side, it was 16.43±2.31° and 16.43±2.36° on the right side with No statistically significant difference was found between right and left femorae (p-value=1.00). Conclusion: The accuracy and success of the hip replacement surgery demands complete knowledge of the morphometry of the proximal femur which is highly specific among the races, region and gender. The present study provides the normal morphometry of the proximal femur of Indian population.

THE RELEVANCE OF BONE GRAFTS AND THE RELATIONSHIP OF BOHLER'S ANGLE IN INTRA-ARTICULAR CALCANEAL FRACTURES' PROGNOSIS

Background: The most frequently broken tarsal bone is the calcaneum. Even if the rehabilitation process can take a while and the treatment is challenging, the results are still very unexpected. As a result, calcaneal fractures place a significant socioeconomic strain on society. As a result, we looked for a factor, such as Bohler's angle, that we might link to the functional result of patients with intra-articular calcaneal fractures. Method: A calcaneum intra-articular fracture was present in 40 individuals. X-rays and CT scans were used to assess each patient before to surgery. With the use of a goniometer, Bohler's angle was manually determined on the lateral radiograph, and a record was created for future use. All patients were treated using open reductions and intermaxillary fixation with a plate, accompanied by or without bone transplant, according to a randomization process. Following surgery, Bohler's angle was assessed at follow-up visits at 2, 4, and 6 weeks as well as 2, 4, and 6 months. The American Orthopedic Foot and Ankle Score (AOFAS) was used to evaluate the patient's functional recovery at least 5 months following the injury. Results: Our analysis of 40 calcaneal fractures demonstrates that there was a statistically significant distinction in the functional outcomes of patients according to the surgically corrected Bohler's angle. Less comorbidities and statistically significant better outcomes were seen in surgical calcaneus fractures when Bohler's angle was restored within normal bounds. The benefit of autologous bone transplant in restoring calcaneal elevation and anatomic minimization was also proven by our research. Conclusion: We recommend using Bohler's angle as a key to achieving outstanding results in displaced calcaneal fractures as well as the use of autologous bone graft in attaining and maintaining normal Bohler's angle in light of the great results gained with Bohler's angle rehabilitation.

An Imaging Measurement Study of Normal Knee Parameters in Southeast China.

Imaging measurement of distal femur and proximal tibia has been the hot point in the research of total knee arthroplasty and prosthesis development, which is an important treatment for patients with advanced knee joint disease. This study retrospectively investigated the digital imaging measurement of normal knee parameters in southeast China and evaluated their clinical value. From February 2010 to May 2014, and in accordance with the inclusion criteria, a total of 677 knees (334 female knees and 343 male knees) were categorized into 3 age groups. Clinical and digital imaging data, including the distal Femoral Condyle Diameter (FCD), Tibial Plateau Diameter (TPD), the distance between the medial tibial plateau and fibular head (DPF), tibiofemoral valgus angle, distal femoral valgus angle, Proximal Tibia (PT) varus angle and the angle from femoral condyle to tibial perpendicular (FT), were measured by using AutoCAD 10.0 software. All measured variables were statistically analyzed by SPSS statistical software (version 18.0). Data are presented as the mean ± standard deviation. The normal female and male femoral condyle diameter was (7.69 ± 0.46) cm and (8.68 ± 0.55) cm, while the normal female and male tibial plateau diameter was (7.66 ± 0.46) cm and (8.60 ± 0.55) cm, respectively. The normal female and male DPF was (0.76 ± 0.36) cm and (0.79 ± 0.36) cm. For females and males, the tibiofemoral valgus angle and distal femoral valgus angle were (3.89 ± 2.20) ° and (3.29 ± 2.12) °, (9.03 ± 2.18) ° and (8.25 ± 2.20) °. As the two methods to measure tibial plateau varus angle, PT angle of normal female and male was (4.29 ± 1.86) ° and (4.84 ± 2.23) °, while the normal female and male FT angle was (5.34 ± 1.95) ° and (5.52 ± 2.07) °. Based on the data obtained, we found significant differences between the two genders in terms of the femoral condyle diameter and tibial plateau diameter in all age groups (P < 0.01). The DPF parameter showed an obvious difference between the young group and the middle-aged group (P < 0.05), and no significant difference was observed between the sides and genders (P > 0.05). The distal femoral valgus angle showed statistical differences between genders in the left side of the young group and middle-aged group (P < 0.05), while angle PT and FT showed no significant difference (P > 0.05). A large number of knee measurements was obtained, and a local knee database was developed in this study. Imaging measurement prior to total knee arthroplasty is clinically important for increasing the accuracy and long-term efficacy of total knee arthroplasty. These data can also provide useful information for knee surgery and sports medicine as well as prosthesis development.

A Wideband Monofilar Helical Reflectarray Antenna With Large-Angle Beam-Scanning Performance

A circularly polarized wideband reflectarray is presented using a monofilar single-turn helical antenna as reflecting element. An <inline-formula> <tex-math notation="LaTeX">$11\times 11$ </tex-math></inline-formula> elements reflectarray is designed, simulated and measured in X-band which demonstrates a wide bandwidth and large-angle beam-scanning performance. Phase range of 360&#x00B0; is obtained by rotating off-centred reflecting elements. Full wave simulations show that 1-dB bandwidth of 29.1&#x0025; is achieved at the center frequency of 10 GHz with a maximum gain of 23.9 dB at normal angle of incidence (<inline-formula> <tex-math notation="LaTeX">$\boldsymbol {\phi }$ </tex-math></inline-formula> &#x003D; 0&#x00B0;, <inline-formula> <tex-math notation="LaTeX">$\boldsymbol {\theta }$ </tex-math></inline-formula> &#x003D; 0&#x00B0;) where the measured gain for the focused beam is 23.6 dB with an aperture efficiency of 51.7&#x0025;. Simulated and tested axial ratio is less than 3 dB from 8.9 GHz to 10.7 GHz. Moreover, large-angle beam scanning performance is verified by changing the angle of incidence from &#x002B;30&#x00B0; to &#x2212;30&#x00B0; in both orthogonal planes and maximum gain loss is tested to be less than 1.3 dB at all scanned angles. Feasibility of design is demonstrated by the measured radiation performance and the results are in good agreement with the simulations.

Unsupervised Semantic Segmenting TLS Data of Individual Tree Based on Smoothness Constraint Using Open-Source Datasets

Unsupervised segmentation of Terrestrial Laser Scanning (TLS) data into wood and leaf is the key for studying forest carbon storage, photosynthesis, canopy radiation. Further segmentation of wood data into trunk and larger branch (TLB), remaining branch (RB) is of great significance and challenge for dust retention, soil heavy metal enrichment. We proposed an unsupervised, automatic semantic segmentation method based on TLS data of individual tree. The method firstly performs initial segmentation based on plane fitting residuals and neighborhood normal angle, which can extract smooth and connected regions in point cloud. Then, the geometric features of segmented clusters are quantified to approximate RB or leaf features. Finally, the segmentation of TLB, RB, and leaf is realized by combining different clusters from bottom to top with geometric features and neighborhood relations. The segmentation performance of our method was evaluated with 104 tree samples from 23 tree species in two open-source datasets from Indonesia, Peru, Guyana and from Canada and Finland. The micro-average precision of our method is 93.61%. The micro-average recalls of TLB, RB, and leaf are 97.08%, 86.44%, and 89.62%. Compared with the well-known method of separating wood and leaf, our method has 33.56% higher sensitivity, 1.82% higher specificity, 20.52% higher precision, and 0.217 higher F1-score. Besides, we estimated the surface area and volume of TLB, the surface area and volume of RB based on the segmented data. The above parameters have good consistency compared to those calculated based on manually separated point clouds (Pearson correlation coefficient (PCC) of 0.55-0.93).

Ray-tracing simulations of whistler-mode wave propagation in different rescaled dipole magnetic fields

Kinetic simulation is a powerful tool to study the excitation and propagation of whistler-mode waves in the Earth’s inner magnetosphere. This method typically applies a scaled-down dipole magnetic field to save computational time. However, it remains unknown whether whistler wave propagation in the scaled-down dipole field is consistent with that in the realistic dipole field. In this work, we develop a ray-tracing code with a scalable dipole magnetic field to address this concern. The simulation results show that parallel whistler waves at different frequencies gradually become oblique after leaving the equator and propagate in different raypaths in a dipole magnetic field. During their propagation, the higher frequency waves tend to have larger wave normal angles at the same latitude. Compared with the wave propagation in a realistic dipole field, the wave raypath and wave normal remain the same, whereas the wave amplification or attenuation is smaller because of the shorter propagation time in a scaled-down dipole field. Our study provides significant guidance for kinetic simulations of whistler-mode waves.

Assessment of the convergence angle of teeth prepared for full crown by preclinical dental students

The objective of this study was to measure the buccolingual and mesiodistal convergence angles of six typodont teeth (# 26, 36, 45, 15, 21, and 13), prepared by preclinical dental students at Ajman University, for porcelain fused to a metal full crown and to compare them with the recommended convergence angle (6.5°). Additionally, we sought to compare the angles recorded for the six sets of teeth and relate the results according to the tooth position and surface and to know which one shows the greater tendency of straying from the normal convergence angle. Materials and methods: The angle of convergence of one hundred ninety-eight typodont teeth preparations was measured both buccolingually and mesiodistally by using a Dino-lite pro digital microscope (AM-413ZT Taiwan) with a Dinocapture (2.0 version 1.5.27.A, AnMo Electronics Corporation). All the results were recorded, and the data were analyzed by means of a one-sample t-test and one-way ANOVA. Results: The mean total convergence angle for this study was 11.29°± 6.66° from both surfaces, which is greater than the recommended value of 6.5° and statistically significant (p&lt;0.000). Only 7.07% of teeth met the ideal convergence angle from both surfaces, and the one-sample test showed a statistically significant difference (p&lt;0.057) from the recommended convergence angle, except for the mesiodistal convergence angle of the lower-right second premolar, which revealed no significant difference. The mean convergence angle for the buccolingual surface was 12.42°± 6.16°, which was higher than that of the mesiodistal surface (10.16°± 7°). One-way ANOVA showed a significant difference between all selected teeth (p&lt;0.000), and a paired samples t-test showed a significant difference within two teeth only, the lower-right second premolar and upper-right canine (p&lt;0.000), in which the mesiodistal measurement showed a lower convergence angle than the buccolingual angle. Conclusions: Preclinical students prepared teeth with a convergence angle higher than the recommended convergence angle. However, all the recorded angles were within the range of previous studies. It was concluded that the recommended convergence angle was difficult to achieve in preclinical practice.

Analysis of the surface plasmon resonance interferometric imaging performance of scanning confocal surface plasmon microscopy.

Here, we apply rigorous coupled-wave theory to analyze the optical phase imaging performance of scanning confocal surface plasmon microscope. The scanning confocal surface plasmon resonance microscope is an embedded interferometric microscope interfering between two integrated optical beams. One beam is provided by the central part around the normal incident angle of the back focal plane, and the other beam is the incident angles beyond the critical angle, exciting the surface plasmon. Furthermore, the two beams can form an interference signal inside a confocal pinhole in the image plane, which provides a well-defined path for the surface plasmon propagation. The scanning confocal surface plasmon resonance microscope operates by scanning the sample along the optical axis z, so-called V(z). The study investigates two imaging modes: non-quantitative imaging and quantitative imaging modes. We also propose a theoretical framework to analyze the scanning confocal surface plasmon resonance microscope compared to non-interferometric surface plasmon microscopes and quantify quantitative performance parameters including spatial resolution and optical contrast for non-quantitative imaging; sensitivity and crosstalk for quantitative imaging. The scanning confocal SPR microscope can provide a higher spatial resolution, better sensitivity, and lower crosstalk measurement. The confocal SPR microscope configuration is a strong candidate for high throughput measurements since it requires a smaller sensing channel than the other SPR microscopes.

Propagation of Chorus Waves Generated in Minimum‐B Pockets

AbstractWe present the first ray tracing results of chorus waves generated in minimum‐B pockets. A new ray tracer is developed to accommodate an arbitrary magnetic field model, which enables us to construct minimum‐B pocket geometries using the Tsyganenko (1989) model. Rays with different frequencies and initial wave normal angles are launched from minimum‐B pockets and traced under different geomagnetic activity and hot electron density conditions. Our results indicate that chorus waves generated from minimum‐B pockets are usually highly localized and thus are unlikely to be detected unless the spacecraft is very close to the source region. These waves are also very unlikely to propagate into the plasmasphere. The propagation distances generally decrease with increasing geomagnetic activity.

The Superior Mesenteric Artery Angle and Abdominal Main Vessel Diameters in Normovolemic Children: For Practical Sonographic Evaluation.

Knowledge of the normal size of important abdominal vessels is important for determination of hydration status and intravascular volume. Knowing the normal value of superior mesenteric artery (SMA) exit angle from the aorta (SMA angle) is necessary for the diagnosis of clinical pathologies caused by SMA compression. The aim of this study was to determine the normal SMA angles and normal diameters of the main abdominal vascular structures of pediatric participants on ultrasonography (USG). Between January 2019 and July March 2019, the USG examinations obtained from 210 participants (age range, 1-214 years; mean age, 83.5 [SD, 5.5] months; females 51%, males 49%) with normal abdominal examinations were prospectively evaluated. The participants were divided into 5 groups according to age. Body mass index values of the participants were kept equal. The diameters of the abdominal vascular structures increased with age, and the statistical differences among the age groups were significant. In all groups, no statistically significant difference was observed between sexes (P > 0.05). The SMA angle was between 17° and 58° (mean, 37.8° [SD, 8.5°]). A statistically significant difference was observed between the age groups in terms of SMA angle (P < 0.05). No statistically difference was found between sexes (P > 0.58-0.912). In our study, we think that the measurements obtained by USG provide normal values of the diameters of the abdominal main vessels and SMA angle. These values can be used as a reference for interpreting hydration status, vascular diameter assessment, and SMA compression syndromes.

Quasilinear Diffusion of Protons by Equatorial Magnetosonic Waves at Quasi‐Perpendicular Propagation: Comparison With the Test‐Particle Approach

AbstractAlthough some plasma waves exhibit the largest growth rate and amplitude at 90° wave normal angle (WNA), particle scattering by these waves in a quasilinear (QL) sense has seldom been examined previously. Using test‐particle calculation and QL theory and assuming a uniform background magnetic field, the present study investigates the proton scattering by equatorial fast magnetosonic waves (MSWs; a.k.a equatorial noise) with varying WNAs including 90°. Comparison with the diffusion coefficients in momentum space obtained from the test‐particle approach indicates that the QL diffusion coefficients due to MSWs are consistent with those estimated from the test‐particle method up to 90° WNA, provided that MSWs described conform to the usual QL theory assumptions. The test‐particle dynamics due to MSWs at 90° WNA are examined in detail. Although in the QL picture, perpendicularly propagating MSWs are only supposed to resonate with protons at integer harmonic frequencies, waves at slightly off‐integer harmonic frequencies as part of a narrowband discrete spectrum of incoherent MSWs play an important role in making the proton scattering stochastic. Considering the recent test‐particle result of bounce‐averaged resonance of energetic protons, non‐zero wave power at the WNAs ≳89.5° typically excluded in QL diffusion can be important for ring current proton dynamics.

Propagation of Electromagnetic Ion Cyclotron Waves in a Dipole Magnetic Field: A 2‐D Hybrid Simulation

AbstractsElectromagnetic ion cyclotron (EMIC) waves are one commonly observed plasma waves in the Earth's inner magnetosphere and play a crucial role in particle dynamics in the radiation belt and ring current. EMIC waves are excited by a proton temperature anisotropy and generally have a left‐handed polarization, however satellite observations have usually reported the existence of linearly polarized EMIC waves in the inner magnetosphere. In this paper, we employ a two‐dimensional (2D) hybrid code in a dipole field (gcPIC‐hybrid) to simulate the propagation of EMIC waves from the equatorial source region. We track one single EMIC wave packet and analyze how its properties evolve along its trajectory. In diagnosing the wave normal angle (WNA) of the packet, we propose a novel method called Wave Front Shape Identification (WFSI). The ellipticity can also been calculated after we know the WNA. By comparing the ellipticity calculated from the linear theory and the ellipticity diagnosed from the simulation, we conclude that in a proton‐electron plasma, EMIC waves would turn from a left‐handed polarization to a linear polarization solely due to the propagation effect when the waves propagate toward higher latitudes and become oblique. We also find that the peak frequency of the wave packet (the wave mode with the maximum amplitude) decreases when propagating toward higher latitudes, which is due to different growth and damping behavior of different modes.

Comparison of optical coherence tomography angiography metrics in primary angle-closure glaucoma and normal-tension glaucoma

To investigate the peripapillary vascular metrics in early normal tension glaucoma (NTG) and early primary angle closure glaucoma (PACG) eyes using optical coherence tomography angiography (OCT-A). One or both eyes of each subject were imaged for a 3 × 3 mm peripapillary region by swept-source OCT-A (DRI-OCT Triton, Topcon, Japan) and assessed by an automated MATLAB program. OCT-A metrics including circumpapillary vessel density (cpVD) and fractal dimension (cpFD) were compared. Their association with visual field (VF) parameters and retinal nerve fiber layer (RNFL) thickness were determined. Sixty-eight eyes of 51 PACG, 68 eyes of 48 NTG, and 68 eyes of 49 control subjects were cross-sectionally analyzed. NTG eyes had significantly lower global cpVD (52.369 ± 0.781%) compared with PACG eyes (55.389 ± 0.721%, P = 0.004) that had comparable disease severity and average RNFL thickness. Multivariable analysis revealed that, for PACG and NTG eyes, decreased cpVD ([PACG] β = −4.242; CI: −8.120, −0.363 vs [NTG] β = −5.531; CI: −9.472, −1.590) and cpFD ([PACG] β = −8.894;CI: −11.925, −5.864 vs [NTG] β = −12.064; CI: −17.095, −6.932) were associated with decreased RNFL thickness (all P ≤ 0.032); with a stronger association between decrease cpFD and decreased RNFL thickness in NTG eyes (P = 0.028). Decreased cpVD was associated with decrease mean deviation (MD) in NTG eyes (β = −0.707; CI: −1.090, −0.324; P ≤ 0.001) and not associated with the visual field parameters in PACG eyes. Early NTG had lower global cpVD compared with early PACG, despite similar disease severity and average RNFL thickness.