Angle Parameters Research Articles

Numerical Study of Williamson Fluid Flow over a Stretching Sheet with Newtonian Heating Embedded in a Porous Medium in Presence of Thermal Radiation and Heat Source/Sink

Williamson fluid has been utilized to explore the aligned magnetic field in the presence of thermal radiation and heat source/sink utilizing Newtonian heating on a stretched sheet soaked in porous medium. The governing partial differential equations are transformed into nonlinear ordinary differential equations by applying similarity transformations. These equations are then solved using MATLAB and the Runge-Kutta fourth-order technique with a shooting technique. Graphs were used to investigate the effects of different factors on dimensionless velocity and temperature. A decrease in the velocity field and an improvement in the distribution of temperature are caused by an enhancement in the Non-Newtonian Williamson fluid parameter and permeability restriction K, whereas the opposite effect is evident when the Aligned angle parameter is increased. When the conjugate factor for Newtonian heating parameter is increased, temperature rises, even as the reverse effect is seen in Prandtl number The coefficient of skin friction is an decreasing function and the Nusselt number is increasing function of Non-Newtonian Williamson fluid parameter and permeability restriction K. while the reverse effect is seen in Aligned angle parameter . The Nusselt number is increased function of heat source/sink parameter , and Newtonian heating parameter . While the reverse effect is seen in Prandtl number .

Effect of Different Working Settings of Sandblasting on Resin Composite Repair Bond Strength

To investigate the effect of different sandblasting settings on the shear bond strength (SBS) in the repair of resin composite, specimens (resin composite, enamel, and dentin; each group n = 16) were sandblasted by varying the parameters of air pressure (0.2/0.3/0.4 MPa), angle (45/90°), particle size (27/50 μm), tip size (0.8/1.2 mm), and distance (2/5/10 mm) prior to the application of a universal adhesive (Adhese Universal) and resin composite (adhesive area: 7.07 mm2). The specimens were subjected to artificial aging (10,000 cycles, 5–55 °C) prior to (resin composite only) and after repair. Groups without mechanical pretreatment and resin composite incremental bond strength served as controls. Statistical analysis was performed using ANOVAs, post hoc tests, and Chi2-tests (p < 0.05). Only air pressure and distance impacted SBS (p ≤ 0.049). However, resin composite SBS did not differ from the resin composite incremental SBS within all sandblasting settings (positive control: 21.0 ± 5.0 MPa, p ≥ 0.566). While sandblasting did not impact bond strength on enamel (control: 20.5 ± 5.1 MPa, p ≥ 0.999), most settings resulted in a lower bond strength on dentin (control: 20.1 ± 4.7 MPa, p ≤ 0.027). In conclusion, sandblasting significantly improves resin composite repair bond strength, while application parameters are of minor relevance.

Geometry optimization of auxetic honeycomb and dynamic analysis of sandwich plate and shell panels with variable stiffness composite laminates

In the present investigation, the fiber orientations and geometric parameters of the sandwich plate and shell panels with auxetic honeycomb core and curvilinear fiber-reinforced facesheets are optimized for the maximum fundamental frequency. The dynamic analysis is carried out considering a higher-order shear deformation theory and employing a C0 eight-noded isoparametric element with nine degrees of freedom per node. The artificial bee colony algorithm is used to optimize different parameters of the auxetic core of the sandwich panel. The mechanical properties of the original material and the geometrical features of the unit cells are used to determine the mechanical properties of the auxetic core. The effects of fiber orientations, and geometric parameters like rib thickness, inclined cell angle, vertical cell rib length, and inclined cell rib length of the core on maximizing fundamental frequency parameters of the panels are investigated. It is evident from the present study that the natural frequency of the panels can be altered without changing their plan dimensions and mass by suitably altering the geometric parameters of the auxetic honeycomb core. The analysis is extended for the different ratios of the density of facesheets and auxetic core materials. The analysis is carried out for three and five-layer sandwich panels with different facesheet-auxetic core arrangements and boundary conditions. For five layered auxetic honeycomb sandwich plates and shell panels, the non-dimensional fundamental frequency is observed to be lower for sandwich with alternate facesheet-core arrangement i.e., three facesheets and two core layers, compared to that of a single core at the middle. The non-dimensional frequency parameter is also found to be sensitive to geometry parameters of auxetic core and fiber angles of the facesheets.

The significance of ultrasound parameters and clinical factors in predicting successful labor induction among nulliparous women.

To compare the values of ultrasound and clinical parameters for predicting outcomes of induction of labor (IOL) among healthy nulliparous women with a singleton, term cephalic pregnancy. The cervical length, cervical strain elastography, posterior cervical angle, head-perineum distance, Bishop score, and maternal parameters were assessed before IOL with a combined method-Foley catheter and Misoprostol perorally. The main outcome was vaginal delivery. Variation in cervical tissue elasticity, represented by elasticity index (E), was significantly different between outcome groups-vaginal delivery and cesarean section (CS) in internal os, in the anterior lip near the cervical canal and the midpoint of the anterior and posterior lip (p < 0.05). The E was higher-softer in the vaginal delivery group. The overall elasticity was significantly higher in the middle part of the cervix in the vaginal delivery group. However, other ultrasound metrics did not differ significantly across the outcome groups. Overall, women who delivered vaginally were taller and had a lower pre-pregnancy BMI (p = 0.02 for both variables). Univariate and multivariate analyses showed maternal height was the significant independent predictor of CS (AOR 0.91, 95% CI 0.84-0.98). The prognostic value for vaginal delivery, based on cervical length, maternal height, Bishop score, and parameters of cervical strain elastography, was poor (AUC < 0.7). The study underscores the importance of cervical tissue elasticity in predicting vaginal delivery outcomes, while also highlighting that maternal height is a significant independent predictor of cesarean delivery. However, evaluated metrics in the study have limited prognostic value for predicting vaginal delivery. This suggests a need for further research to identify more reliable predictors of delivery outcomes.

Patient-specific spine digital twins: a computational characterization of the idiopathic scoliosis

Background:Scoliosis is an idiopathic three-dimensional spine strain. The orthopedic parameter used to diagnose and evaluate the severity of the strain is Cobb’s angle. This study proposes using this clinical parameter to reproduce a digital twin of the spine, calculate biomechanical stress changes, and characterize idiopathic scoliosis deformity through symmetrical degeneration of intervertebral discs, relying on patient-specific radiological measurements of the scoliotic curves.Methods:A three-dimensional computational model of the spine was developed, where patient-specific curves were generated by modifying intervertebral disc mechanical properties via a mathematical model derived from radiological data. Validation of the model was performed by comparing the resultant scoliotic curves with patient radiological images. Finite element analysis was then used to elucidate the biomechanical effects on the spine due to the deformity.Results:The model successfully replicated patient-specific thoracic scoliotic deformities, revealing a discernible relationship between disc strain and its proximity to the apex, indicating a heightened risk of disc stress closer to the apex. Moreover, “type-C” curves exhibited a greater risk of herniation compared to “type-S” curves due to differences in compressive stress distribution.Conclusion:This modeling approach enhances the understanding of scoliosis biomechanics, facilitating risk assessment for disc prolapse and aiding in treatment selection, including the design of condition-specific orthotics. Furthermore, it establishes a quantitative link between scoliosis severity and disc strain, integrating Cobb’s angle and other orthopedic parameters into computational models to approximate patient-specific conditions.

Effect of curvature angle and structural configurations on dynamic performance of honeycomb sandwich structures

The aim of this study is to investigate the effects of curve angle and structural parameters on ballistic performance of honeycomb sandwich structures. In the study, high-velocity impact simulations were performed in LS DYNA finite element program to investigate the effects of honeycomb structural parameters, curve angle, residual velocity, specific energy absorption (SEA) and damage mechanism. Progressive damage analysis based on the combination of cohesive zone model (CZM) and bilinear traction-separation law was performed. The ballistic limit value increased by 41.9% when the facesheet thickness increased by two times. When the cell wall thickness increased by five times, the ballistic limit value increased by 13.3%. When the core height was two times increased, the ballistic limit velocity value increased by 2.076 times. Although the ballistic limit velocity value of the CFRP Facesheet and Aluminum (Al) core sandwich structure is 7.14% lower than the all Al specimen, the SEA value is 9.47% higher. When the curve angle increases from 0˚ to 180˚, the ballistic limit value decreases by 22.8%. In general, this study provides useful information about the design of ballistic structures, parameters affecting their performance and their effects.

Numerical investigation of angle parameters of tip sails for improvement of aircraft flight performance

Inspired by the tip feathers of soaring birds, the device of tip sails was designed and installed on the wing to achieve drag reduction. The influences of design parameters including cant angles, toe angles and twist angles on aerodynamic characteristics of tip sails were investigated through 77 cases of 11 configurations at 7 different angles of attack. According to the results grouped, the optimal cant angles ( 30 , 15 , 0 ) were determined. By adjusting the toe angles, drag reduction can be improved under different flight conditions. The decreasing twist angles can inhibit flow separation on sail surface. The optimal toe angles ( 18 , 15 , 12 ) and twist angles ( 12 , 9 , 6 ) resulted in the weakest flow separation. Ensuring that the twist angle of each sail is 6 ∘ less than that of the corresponding toe angle can effectively inhibit flow separation on the sail surface. The tip sails can also split and weaken the wingtip vortex. In addition, in the validation of the numerical method, we also investigate the influence of numerical schemes and turbulence models on the results of wingtip vortex flow. In the cases with unstructured meshes, the third-order finite volume scheme had higher computational efficiency than the traditional second-order finite volume scheme in obtaining grid independent solutions, and the turbulence model with rotation correction can improve the calculation accuracy of the wingtip vortex flow. The results of this paper provide a valuable reference for the design of tip sails.

Optimization of tensile strength of AlSi10Mg material in the powder bed fusion process using the Taguchi method

This study examined scan speed, hatch distance, and scan rotation angle parameters to determine the effects of the powder bed fusion process on the tensile strength of AlSi10Mg material. The Taguchi L9 experimental design was applied to evaluate the effects of the parameters systematically. The experimental results revealed the importance of the parameters affecting the tensile strength of the AlSi10Mg material. While the scan speed was determined to be the parameter that most affected the tensile strength with a contribution rate of 81.4%, the scan rotation angle and hatch distance were effective at 7.8% and 6.1%, respectively. In the optimization performed using signal/noise analysis, 1200 mm/s scan speed, 80 μm hatch distance, and 17° scan rotation angle were found to be the most suitable parameters to ensure the highest tensile strength. The tensile strength obtained in the verification test was measured at 598 MPa. The findings increase the application potential of SLM technology with AlSi10Mg material and provide valuable information for process optimization. The results can significantly contribute to strategies to increase tensile strength and improve material performance in industrial production processes.

Molecular Modelling and Investigation of Bioactive Stable DNA G-Quadruplex d(G4T4G4) under Different Physiological Conditions using Molecular Dynamics Simulation

We are reporting a molecular dynamics study on the structure and conformation of the DNA quadruplex. The single molecule quadruplex's coordinates were obtained and modeled using PDB ID 1d59. The simulation's sequence is d(GGGGTTTTGGGG). In the beginning, two hairpin structures were constructed with loops holding thymine residues at either end, forming a four-stranded helical structure. The cyclic hydrogen bonds created by the structure kept the guanine residues of all four strands in one plane. The molecule was subjected to molecular dynamics simulation for 100ns and at periodic intervals of 10ns, the dynamical pathway's trajectory was examined. The deviations and fluctuations viz. RMSD, RMSF and Rg plots were analyzed, the structure and shape of the time-evolved trajectory were examined. The outcome was compared with the crystal structure. Our findings reveal a few peculiar properties which we have discussed in this paper. The helix axis and torsion angle parameters were calculated. The results of this interpretation give the idea about quadruplex interaction with external agents and inspire to do further research on DNA quadruplex structures in telomeric regions of living chromosomes.

Hallux valgus interphalangeus is more common in juvenile-onset hallux valgus than in adult-onset hallux valgus

BackgroundThis study aimed to compare the prevalence of hallux valgus interphalangeus (HVI) in juvenile-onset hallux valgus and adult-onset hallux valgus and to analyze the correlation between the hallux interphalangeal angle (HIA) and other radiographic parameters in juvenile-onset hallux valgus.MethodsThis retrospective study included 640 feet and 320 patients with hallux valgus (160 juvenile-onset and 160 adult-onset cases). Eight radiographic parameters were measured: HIA, hallux valgus angle, intermetatarsal angle, talonavicular coverage angle, anteroposterior talocalcaneal angle, lateral talocalcaneal angle, lateral talo-first metatarsal angle, and calcaneal pitch. The two groups were compared based on the radiographic parameters, and the correlation between the HIA and other radiographic parameters in juvenile-onset valgus was analyzed.ResultsThe prevalence of HVI in juvenile-onset hallux valgus (63%) was higher than that in adult-onset hallux valgus (28%), and juvenile-onset hallux valgus demonstrated a greater HIA than that displayed by adult-onset hallux valgus (mean ± standard deviation, 12.9 ± 5.7 and 8.3 ± 5.2, respectively). In juvenile-onset valgus, the HIA was negatively correlated with the hallux valgus (r = -0.218, p < 0.001) and intermetatarsal angles (r = -0.143, p = 0.015) and positively correlated with the talonavicular coverage (r = 0.240, p < 0.001) and anteroposterior talocalcaneal angles (r = 0.127, p = 0.008).ConclusionsJuvenile-onset hallux valgus is associated with more HVI than that in adults. Moreover, forefoot abduction deformity is related to the progression of HVI. These findings highlight the need to consider concomitant HVI when juvenile-onset valgus is encountered.Level of evidenceLevel III, retrospective comparative study.

Incidence of acute angle closure in patients with primary angle closure without prophylactic iridotomy during pharmacological mydriasis for cataract surgery.

The objective was to study the incidence of acute primary angle closure (acute PAC) during pharmacologic mydriasis before cataract surgery and changes in anterior chamber angle parameters in patients with primary angle closure diseases (PACD) with and without prophylaxis laser peripheral iridotomy (LPI). This was a prospective, comparative study of cataract patients with PACD with and without prophylaxis LPI presented at the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand during June 2022 to December 2023. The incidence of acute PAC during pharmacologic mydriasis prior to cataract surgery was recorded. Changes in anterior chamber depth (ACD) and anterior chamber angle parameters measured with anterior segment optical coherence tomography before and after cataract surgery were compared between groups using Student t test. There were 195 eyes of 116 patients with a mean age of 70 years enrolled in the study. Eighty patients were women and 36 were men. There were 99 eyes without prophylaxis LPI and 96 eyes with LPI. There was significantly more angle-closure glaucoma in the non-LPI group than in the LPI group. Preoperatively, all anterior chamber angle parameters were significantly greater in the LPI group than in the non-LPI group (P < .001 all parameters), except ACD (P = .83) and anterior chamber width (ACW) (P = .30). All participants underwent uneventful cataract surgery. Postoperatively, all parameters of the anterior chamber angle and ACD increased significantly in both groups. When comparing between groups, all postoperative anterior chamber angle parameters were not significantly different between the groups, but ACD was significantly greater (P = .036) and ACW was lower in the LPI group (P = .008). There was no incidence of acute PAC occurring during pharmacological mydriasis before cataract surgery in both groups. There was no incidence of acute PAC in patients with and without prophylaxis LPI during pharmacological mydriasis in the preoperative preparation for cataract surgery. Eyes without LPI showed significantly lower preoperative anterior chamber angle parameters compared to eyes with previous LPI, but not significantly different postoperatively. The benefits of prophylactic LPI for PACD scheduled for cataract surgery must be further investigated.

Linear anchored Gaussian mixture model for location and width computations of objects in thick line shape

ABSTRACT To detect linear structure, model-based approaches using Hough and Radon transforms are often used but, are not recommended for thick line detection, whereas methods based on image derivatives need further tedious step-by-step processing. In this paper, a novel detection paradigm is presented, where the 3D image gray level representation is considered as finite mixture model of statistical distributions, called linear anchored Gaussian and parametrized by radius, angle and scale parameters dealing with structure location and thickness. These parameters could estimated by Expectation-Maximization algorithm. To rid the data of irrelevant information brought by nonuniform and noisy background, a modified EM algorithm is detailed. The proposed method gives very accurate results on real-world and synthetic images, where, for the latter with strong Gaussian blur and Additive White Gaussian Noise ( σ n = 150 ), the mean estimation errors on the orientation, the distance from the origin and the thickness reach 0.35 ∘ , 0.4 and 0.48 pixel, respectively.

Study on the mechanical properties of the thin-walled double circular tube filled with a novel NPR lattice core based on the concave rotating mechanism

Abstract This study presents a thin-walled double circular tube filled with a novel negative Poisson’s ratio(NPR) lattice core based on the concave rotating mechanism. The unit cell of the NPR lattice core is constructed by replacing each inclined side of a concave hexagon with a smaller concave hexagon with an identical geometry aspect ratio. The single cell is arrayed to obtain a two-dimensional honeycomb structure, and then curling and mirroring operations are utilized to get a circular tube structure. Compressive deformation and load-displacement response of NPR lattice core with different concave angles are analyzed by FEM. To validate with numerical results, the NPR lattice core samples are prepared using 3D printing technology and subjected to quasi-static uniaxial compression experiments. Then, the thin-walled double circular tube filled with the NPR lattice core(FDCT) is established. The load-displacement relationship and energy absorption characteristics are analyzed, and the effects of two angle parameters on the specific energy absorption of the structure are discussed. The results show that an increase in the concave angle decreases the rigidity of the NPR lattice core. When subject to compression, all models show NPR effects, with minimum and maximum Poisson's ratios of -0.29 and -0.5, respectively. For FDCT, it is found that the interaction between the core layer and the tube wall enhances the structure's energy absorption performance. Changes in the core layer angle parameters affect the energy absorption of the FDCT structure, where increasing the concave angle improves the energy absorption efficiency of the structure. In contrast, the effect of the rotational angle is not significant.&amp;#xD;

Omnidirectional Bending Sensor with Bianisotropic Structure for Wearable Electronics.

Bending sensors are critical to the advancement of wearable electronics and can be applied in the dynamic monitoring of flexible object morphology. However, current bending sensors are constrained by sensing range and precision, especially in full-range detection. The maximum sensing range of existing flexible bending sensors is 0-240°. This study introduces a bianisotropic responsive structure into the design of an all-textile bending sensor, thereby realizing 0-360° full-range omnidirectional bending sensing. First, the project elucidated the sensing mechanism of the piezoresistive bianisotropic structured bending sensor and identified critical factors through a numerical simulation method. Then, the bianisotropic structured bending sensors were produced through the stitch method and analyzed on their electromechanical performance. Further, the recognition model for both bending angle and direction parameters was developed via numerical calculation, achieving a high accuracy with an error rate of 2.82%. Last, according to the ergonomics of body joints, the sensors were customized and validated in body joint monitoring scenarios. This work significantly enhances the performance of flexible bending sensors in sensing range, accuracy, and comfort for the wearer. The versatility of this bending sensor positions it as a promising candidate to supplant traditional heavy equipment or rigid devices, particularly in wearable joint motion monitoring and soft robotics.

SHEAR STRENGTH PARAMETERS AND DEFORMABILITY PROPERTIES OF SILICATE-BASED RESIN ADDED SAND-TYPE SOIL SPECIMENS

In this study, the shear strength, uniaxial compressive strength (UCS) values and deformability properties of silicate-based polymer resin added silty sand type soil specimens were examined through a series of experimental studies. Although the UCS and shear strength values increased, minor decreases in the internal friction angle values were measured as the resin ratio increased. It was determined that the main reason of improvement in the strength values due to the increase in resin content is the increase in cohesion values. It was found that the UCS values calculated according to the cohesion and internal friction angle parameters of the Mohr&amp;Coulomb failure criterion (UCSc) were 2.6-3.0 times lower than the values obtained from the direct UCS experiment. According to this finding, it was concluded that the Mohr&amp;Coulomb failure criterion is not properly usable to represent the mechanical behaviors of resin added sands. As another outcome, the ratio between UCS/UCSc slightly decreased with an increase in the resin amount. In other words, it has been determined that the Mohr&amp;Coulomb failure criterion gives a bit more inaccurate results for the specimens with low binder contents. With the increase in the resin content ratio, significant increases were obtained in both elastic modulus and ductility properties of the samples. It has been evaluated that the silicate-based polymer resin binder is advantageous to provide significant increases in the toughness and energy absorption capacity of soils.

A comparison of the new parameter, “MKG angle” with ANB, Wits’ appraisal, Yen, Pi, and W angles

Objectives: The objectives of the study are to compare and assess the precision of MKG angle with ANB, Wits’ appraisal, Yen, Pi, and W angles and reproducibility between them. Material and Methods: 160 pre-treatment cephalograms of 80 skeletal class I and 80 skeletal class II patients were selected from the Department of Orthodontics and Dentofacial Orthopedics and were divided into Group 1 and Group 2. MKG angle, ANB angle, Wits’ appraisal, W, Yen, and Pi angles were measured, and MKG angle was compared with each of them for the evaluation of its precision. Results: The statistical analysis was done using SPSS software version 26.0. The mean, standard deviation, t-test, and Pearson correlation coefficient were calculated. Descriptive statistics were done to know the mean and standard deviation. The Pearson correlation coefficient was done to know the correlation between the MKG angle and other parameters in both the groups. A statistically significant difference was observed between MKG angle and all other parameters – ANB, Wits’ appraisal, YEN, W, Pi angles in general population. Conclusion: MKG angle can be used to assess the anteroposterior discrepancy but as an adjunct with other parameters.

Anterior Segment Pharmacological Accommodative Changes and Its Impact on the Circumferential Anterior Chamber Angle after ICL V4c Implantation: Angle following ICL implantation.

To investigate the pharmacological accommodative changes of the anterior segment and its impact on the circumferential anterior chamber angle (ACA) after implantable collamer lens (ICL) implantation using swept-source optical coherence tomography (SS-OCT). Eye and ENT Hospital, Fudan University, Shanghai, CHINA. Prospective randomized contralateral eye study. Eight men and 24 women (mean age, 28.2 ± 5.8 years; range, 19-42 years); 64 eyes were included at 3 months after ICL implantation. One eye per patient was randomly assigned to undergo tropicamide instillation (mydriasis group), and the contralateral eye underwent pilocarpine instillation (miosis group). SS-OCT examinations were performed before and after instillation to measure angle parameters. Trabecular-iris angle 500 (TIA500), angle opening distance 500 (AOD500), trabecular-iris space area (TISA500), angle opening distance circumference area 500 (AODA500), trabecular-iris circumference volume 500 (TICV500), and central vault (ICL to crystalline lens [ICL-L]) were evaluated. Relative to baseline levels, TIA500, AOD500, and TISA500 values all increased significantly in both groups (all P < 0.01). AODA500 and TICV500 values increased by 19.7% and 12.1%, respectively, in the mydriasis group (all P < 0.001), and these values similarly increased by 23.4% and 27.7%, respectively, in the miosis group (all P < 0.001). After instillation, the ICL-L decrease in the miosis group was significantly larger than that in the mydriasis group (P = 0.004). Mean AOD500, TISA500, and TICV500 in the miosis group were significantly larger than those in the mydriasis group (all P ≤ 0.036), especially at 8 and 10 o'clock (all P ≤ 0.014). Correlation analyses indicated that the increase in anterior chamber angle parameters was positively correlated with the change in ICL-L for both groups. Pilocarpine induced a more significant increase in ACA than tropicamide, because of different mechanism of anterior segment changes. We recommend circumferential meridian scan to assess angle status.

Aerodynamic Performance Evaluation of Subsonic Compressor Cascade Blade With Leading-Edge Damage

Abstract Material loss at the leading edge of in-service gas-turbine engine blades is detrimental to the aerodynamic performances of compressors. In this study, computational simulations and experiments using pneumatic probes were conducted to measure the total pressure loss of compressor cascade blades with material loss at their leading edges. The correlations between blade leading-edge damage geometries and cascade blade total pressure losses were analyzed. The geometrical features of blade leading-edge damage that most affect the cascade blade total pressure loss were distinguished, and the influences of leading-edge damage region cross-sectional shapes on the cascade blade total pressure loss were examined. Two methods for evaluating the total pressure loss of damaged cascade blades were developed using experimental and numerical data. In the first method, an attempt is made to correlate the cascade blade total pressure loss with a characteristic parameter that is defined using scale and angle parameters of the leading-edge damage region. The second method is based on the probability distribution function as well as the critical loss boundary of the geometrical parameters of the leading-edge damage region. The results of this study provide a better understanding of the influence of damaged leading edges on compressor cascade blade aerodynamic performance and can help establish low-cost methods for the estimation of compressor performance degradation.

Is There a Relation Between High Pelvic Incidence and Sagittal Angle of Posterior Lumbar Facets?

In recent years, several studies have shown the presence of a linear correlation between the pelvic incidence (PI) and spondylolisthesis. However, no study has attempted to investigate a potential association between facet sagittal angle and spinopelvic parameters, especially PI in the normal population. Abdominopelvic computed tomography (CT) scans were collected. Inclusion criteria included age less than 40 years and CT done for non-orthopedic diagnostic purposes. All cases with any spinal pathology were excluded. Spinopelvic and lumbar spinal parameters were collected using the KEOPS software (SMAIO, Lyon, France), and the facet sagittal angle were evaluated on axial CT images from L1-L2 to L5-S1 using the institution PACS system (GE Centricity, Chicago, IL). A total of 450 patients' imaging were analyzed, with a mean age of 31.3 years (±4.9). Facet sagittal angle was found to be significantly correlated to an increase in PI but only at the L5-S1 level (odds ratio=2.3). The effect of sex on sagittal angle of facet joints was found to be non-significant compared with high PI. Finally, at the L5-S1 level, facet tropism was associated with a higher PI but was not found to play a direct role in the angle of facet joints. The PI seems to be correlated to the other spondylolisthesis risk factors: facet tropism and female sex. It carries the heaviest load in the progression towards sagittally oriented facet joints, which might lead to segmental instability and eventual spinal pathologies.

Reverse Shock Emission from Misaligned Structured Jets in Gamma-Ray Bursts

The afterglow of gamma-ray bursts (GRBs) has been extensively discussed in the context of shocks generated during an interaction of relativistic outflows with their ambient medium. This process leads to the formation of both a forward and a reverse shock. While the emission from the forward shock, observed off-axis, has been well-studied as a potential electromagnetic counterpart to a gravitational-wave-detected merger, the contribution of the reverse shock is commonly overlooked. In this paper, we investigate the contribution of the reverse shock to the GRB afterglows observed off-axis. In our analysis, we consider jets with different angular profiles, including two-component jets, power-law structured jets, Gaussian jets, and “mixed jets” featuring a Poynting-flux-dominated core surrounded by a baryonic wing. We apply our model to GRB 170817A/GW170817 and employ the Markov Chain Monte Carlo method to obtain model parameters. Our findings suggest that the reverse shock emission can significantly contribute to the early afterglow. In addition, our calculations indicate that the light curves observable in future off-axis GRBs may exhibit either double peaks or a single peak with a prominent feature, depending on the jet structure, viewing angle, and microphysics shock parameters.