Vertical Stability Research Articles

Distribution of PM10, PM2.5, and NO2 in the Cergy‐Pontoise urban area (France)

AbstractThis study employed a network comprising 16 fixed “Ecosmart” sensors deployed in the Cergy‐Pontoise conurbation. Continuous measurements of PM10, PM2.5, and NO2, significant pollutants in the Paris region, were conducted from April 8 to June 6, 2022. The collected data were represented as statistically composite spatial matrices due to the heterogeneous urban landscape and the overlapping of multiple pollution sources. Temporal variations on a daily basis were influenced by both traffic and meteorological conditions. Daytime, characterized by denser traffic compared to nighttime, exhibited higher concentrations of PM10 and PM2.5. Conversely, NO2 concentration levels displayed two peaks associated with traffic volume, and relatively elevated nocturnal values compared with midday due to atmospheric vertical stability during the nighttime phase. The analysis of weather‐type impacts revealed that during unstable weather conditions, elevated particle concentrations stemmed from dust resuspension from the ground and long‐range transport. Maximum NO2 concentrations were observed during stable weather conditions, whereas minimum concentrations occurred during unstable weather.

Implications of vertical stability control on the SPARC tokamak

To achieve its performance goals, SPARC plans to operate in equilibrium configurations with a strong elongation of κareal∼1.75 , which in turn will destabilize the n = 0 vertical instability. However, SPARC also features a relatively thick conducting wall that is designed to withstand disruption forces, leading to lower vertical instability growth rates than usually encountered. In this work, we use the TokSyS framework to survey families of accessible shapes near the SPARC baseline configuration, finding maximum growth rates in the range of γ≲100 s−1. The addition of steel vertical stability plates has only a modest ( ∼25% ) effect on reducing the vertical growth rate and almost no effect on the plasma controllability when the full vertical stability system is taken into account, providing flexibility in the plate conductivity in the SPARC design. Analysis of the maximum controllable displacement on SPARC is used to inform the power supply voltage and current limit requirements needed to control an initial vertical displacement of 5% of the minor radius. From the expected spectra of plasma disturbances and diagnostic noise, requirements for filter latency and vertical stability coil heating tolerances are also obtained. Small modifications to the outboard limiter location are suggested to allow for an unmitigated vertical disturbance as large as 5% of the minor radius without allowing the plasma to become limited. Further, investigations with the 3D COMSOL code reveal that strategic inclusion of insulating structures within the VSC supports are needed to maintain sufficient magnetic response. The workflows presented here help to establish a model for the integrated predictive design for future devices by coupling engineering decisions with physics needs.

Effect of different lumbar–iliac fixation and sacral slope for Tile C1.3 pelvic fractures: a biomechanical study

BackgroundLumbar–iliac fixation (LIF) is a common treatment for Tile C1.3 pelvic fractures, but different techniques, including L4–L5/L5 unilateral LIF (L4–L5/L5 ULIF), bilateral LIF (BLIF), and L4–L5/L5 triangular osteosynthesis (L4–L5/L5 TOS), still lack biomechanical evaluation. The sacral slope (SS) is key to the vertical shear of the sacrum but has not been investigated for its biomechanical role in lumbar–iliac fixation. The aim of this study is to evaluate the biomechanical effects of different LIF and SS on Tile C1.3 pelvic fracture under two-legged standing load in human cadavers.MethodsEight male fresh-frozen human lumbar–pelvic specimens were used in this study. Compressive force of 500 N was applied to the L4 vertebrae in the two-legged standing position of the pelvis. The Tile C1.3 pelvic fracture was prepared, and the posterior pelvic ring was fixed with L5 ULIF, L4–L5 ULIF, L5 TOS, L4–L5 TOS, and L4–L5 BLIF, respectively. Displacement and rotation of the anterior S1 foramen at 30° and 40° sacral slope (SS) were analyzed.ResultsThe displacement of L4–L5/L5 TOS in the left–right and vertical direction, total displacement, and rotation in lateral bending decreased significantly, which is more pronounced at 40° SS. The difference in stability between L4–L5 and L5 ULIF was not significant. BLIF significantly limited left–right displacement. The ULIF vertical displacement at 40° SS was significantly higher than that at 30° SS.ConclusionsThis study developed an in vitro two-legged standing pelvic model and demonstrated that TOS enhanced pelvic stability in the coronal plane and cephalad–caudal direction, and BLIF enhanced stability in the left–right direction. L4–L5 ULIF did not further improve the immediate stability, whereas TOS is required to increase the vertical stability at greater SS.

Multi-Objective Optimization of Bogie Stability for Minimum Radius Curve of Battery Track Engineering Vehicle

A battery track engineering vehicle faces challenges such as derailment and other safety concerns when navigating an R20m minimum radius curve, primarily owing to its low vertical and horizontal stabilities. To address these issues, a methodology integrating genetic optimization algorithms with a rigid and flexible coupled multi-body dynamics simulation is proposed to optimize the primary suspensions of the bogie of the vehicle. Initially, a multi-objective optimization model combining rigid and flexible coupled multi-body dynamics of battery track engineering vehicles with a genetic optimization algorithm was formulated. Subsequently, the optimal Latin hypercube design was applied to analyze the sensitivity of vertical and horizontal stability to various suspension parameters. Finally, a non-dominated sorting genetic algorithm (NSGA-II) and an archive-based micro genetic algorithm (AMGA) were applied to optimize the primary suspensions to enhance stability. Consequently, a set of optimal suspension parameter combinations was obtained. A notable enhancement was observed in the lateral stability of the optimized battery track engineering vehicles by 23.33% and in the vertical stability by 3.5% when traversing the R20m minimum radius curve, thereby establishing a theoretical foundation for further improving the running safety of railway vehicles and resolving the shortcomings of less research on the smallest radius curve.

A Novel Small Form-Factor Handheld Optical Coherence Tomography Probe for Oral Soft Tissue Imaging.

Tissue imaging is crucial in oral cancer diagnostics. Imaging techniques such as X-ray imaging, magnetic resonance imaging, optical coherence tomography (OCT) and computed tomography (CT) enable the visualization and analysis of tissues, aiding in the detection and diagnosis of cancers. A significant amount of research has been conducted on designing OCT probes for tissue imaging, but most probes are either heavy, bulky and require external mounting or are lightweight but straight. This study addresses these challenges, resulting in a curved lightweight, low-voltage and compact handheld imaging probe for oral soft tissue examination. To the best of our knowledge, this is the first curved handheld OCT probe with its shape optimized for oral applications. This probe features highly compact all-fiber optics with a diameter of 125 μm and utilizes innovative central deflection magnetic actuation for controlled beam scanning. To ensure vertical stability while scanning oral soft tissues, the fiber was secured through multiple narrow slits at the probe's distal end. This apparatus was encased in a 3D-printed angular cylinder tube (15 mm outer diameter, 12 mm inner diameter and 160 mm in length, weighing < 20 g). An angle of 115° makes the probe easy to hold and suitable for scanning in space-limited locations. To validate the feasibility of this probe, we conducted assessments on a multi-layered imaging phantom and human tissues, visualizing microstructural features with high contrast.

Control of elongated plasmas in superconductive tokamaks in the absence of in-vessel coils

The roadmap for the commissioning and first operations of superconductive tokamaks envisages the possibility of running discharges with fairly elongated plasmas before the complete installation of the in-vessel components, including vertical stabilization coils, or any other specific sets of coils to be used for the magnetic control of fast transients. In the absence of dedicated actuators, the magnetic control system shall perform the essential fast control actions by using the out-vessel superconductive coils, if needed. These are typically less efficient in reacting to fast transients, due to the shielding effect of the vessel and imply a coupling with other control tasks relying on the same actuators, such as plasma current, position, and shape control. Hence, effective actuator-sharing strategies must be put in place. This paper presents an architecture and a possible control strategy that is able to cope with vertically unstable elongated plasmas subject to fast varying disturbances, in the absence of dedicated in-vessel coils. The architecture exploits a model-based actuator-sharing approach to effectively accomplish the main magnetic control objectives while minimizing the cross-couplings among the various tasks. The effectiveness of the approach is demonstrated by means of nonlinear simulations of realistic JT-60SA scenarios. In particular, an isoflux plasma shape controller is integrated with plasma current control and vertical stabilization. The proposed control approach proves to control vertical displacement events and plasma deformations due to fast variations of poloidal beta with satisfactory performance.

Research on Aerodynamic characteristics of Lightweight Spheres Suspended in Vertical Airflow

Experimenting to obtain data about the drag force is usually difficult and expensive. In this paper, an experiment is conducted using a hair dryer as a provision of a controllable airflow, and two ping pong balls as the object in an airflow to find out the factors that affect the stability of an object in an airflow by using the control variate method and use the turbulent jets theory to calculate the drag force. The result of this experiment is that when the balls have the same mass, as the wind speed increases, the vertical stability of the ball becomes better and the horizontal stability becomes better as well. When the wind speed is the same, as the mass of the ball increases, the vertical stability of the ball becomes better. The equations to calculate the drag force are correct and can simulate and calculate the result of the track of an object. The value of this experiment is that it provides an easy way to experiment with the drag force.

Assessment of vertical stability for negative triangularity pilot plants

Negative triangularity (NT) tokamak configurations may be more susceptible to magneto-hydrodynamic instability, posing challenges for recent reactor designs centered around their favorable properties, such as improved confinement and operation free of edge-localized modes. In this work, we assess the vertical stability of plasmas with NT shaping and develop potential reactor solutions. When coupled with a conformal wall, NT equilibria are confirmed to be less vertically stable than equivalent positive triangularity (PT) configurations. Unlike PT, their vertical stability is degraded at higher poloidal beta. Furthermore, improvements in vertical stability at low aspect ratio do not translate to the NT geometry. NT equilibria are stabilized in PT vacuum vessels due to the increased proximity of the plasma and the wall on the outboard side, but this scenario is found to be undesirable due to reduced vertical gaps which give less spatial margin for control recovery. Instead, we demonstrate that informed positioning of passively conducting plates can lead to improved vertical stability in NT configurations on par with stability metrics expected in PT scenarios. An optimal setup for passive plates in highly elongated NT devices is presented, where plates on the outboard side of the device reduce vertical instability growth rates to 16% of their baseline value. For lower target elongations, integration of passive stabilizers with divertor concepts can lead to significant improvements in vertical stability. Plates on the inboard side of the device are also uniquely enabled in NT geometries, providing opportunity for spatial separation of vertical stability coils and passive stabilizers.

Assembly procedure and tooling development plan for in-situ winding of ITER in-vessel vertical stability coils

The ITER in-vessel Vertical Stabilization (VS) coils, composed by the upper and lower VS coils, are designed to provide fast vertical stabilization of the plasma through a fast-current noise profile to compensate small plasma oscillations and to recover vertical displacement events.The VS coils are made by 4 continuous turns of Mineral Insulated Conductor (MIC) joined by Inconel ® 625 welded brackets, installed on rails on the inner wall of ITER Vacuum Vessel (VV). Thus, the coil turns winding/forming and the entire coils assembly have to be performed inside ITER VV, forcing the assembly procedure and tooling design to cope with the very limited space and strict constraints of ITER VV environment. The proposed procedure foresees that MIC conductor is un-spooled in the Neutral Beam (NB) port area and inserted into the ITER VV through a NB equatorial port, then a set of tooling is installed on a reinforced staging platform to wind, form and seal the conductor turns and finally to weld brackets under pre-compression. For this purpose, the tooling design including the reinforcement staging has been developed to meet the required tooling function, configuration optimization, assembly procedure and environmental constraints. The dedicated tools to be used for the assembly procedure of the VS coils are categorized into ex-vessel tools for unspooling and cleaning, in-vessel tools for winding and bump forming, bracket assembly tools for pre-compression and welding, termination and sealing tools, ancillary lifting tools and reinforcement staging platforms. This paper provides the overall assembly procedure and tooling development for the in-situ winding of VS coils.

Analysis of a bus vertical dynamic performances – a comparison between linear and nonlinear suspension systems

This paper mainly focuses on the numerical calculation to determine the vertical evaluation indexes with all three types of typical harmonic, transient and random road excitations. The effects of linear and nonlinear suspension characteristics on the vertical evaluation indexes are fully understood systematically. The ride comfort, suspension working space, and road holding are analyzed for both two cases of linear and nonlinear suspension systems. The improvement of the vertical stability and road holding in the case of nonlinear suspension subjected under three different excitations could be characterized most meaningfully. The obtained results help to systematically get full understanding of the investigated problem nature. It also should guide interested readers in suspension design to improve the stability, safety, and ride comfort of buses.

Customized and high-performing acoustic levitators for contact-free experiments

Acoustic levitators are becoming increasingly common research instrumentation for contact-free, lab-in-a-droplet studies. Recently, levitators that employ multiple, small, ultrasonic transducers have gained popularity, given their low price, temperature and spatial stability, low voltage, and accessibility. Yet, the current state-of-the-art device, TinyLev, presents limitations for certain applications in terms of stability, strength, and compactness. Herein, we developed three new levitators and evaluated the effect of the construction parameters (e.g., distance of opposing arrays, number and arrangement of transducers, etc.) on their performance. The best performing levitator from this work had half the number of transducers, compared to TinyLev, though presented 1.7 and 3.5 times higher levitation capacity along the horizontal and vertical configurations, respectively, and 4.7 and 2.0 times higher horizontal and vertical stability of a levitated object, respectively. Additionally, we present a direct means to evaluate the acoustic radiation net force acting on a deformable object for uniaxial levitators, without the use of a microphone or a schlieren deflectometer for this type of levitators. The theoretical and experimental observations provide insights for adapting the acoustic levitator design for specific applications. Finally, we developed an open-source software which allows the evaluation of the acoustic pressure field generated by customized designs and provides the necessary files for 3D printing the scaffold of the levitator. This study aims to increase accessibility and promote further developments in contact-free experiments.

Reduced-order modelling for real-time physics-based variation simulation enhanced with adaptive sampling and optimized interpolation

AbstractManufacturing industries require a right-first-time paradigm to remain competitive. Variation simulation (VS) is a key tool to predict variation of the final shape of flexible assemblies, allowing to reduce defects and waste. VS models involving compliant sheet-metal parts commonly integrate physics-based simulation with statistical approaches (usually Monte Carlo simulation). Although increasingly used as a backbone of synthesis techniques for (stochastic) optimization of assembly systems, the main roadblock of VS methods is the intense computational costs due to time-intensive simulations and high-dimensional design space. Driven by the need of time reduction, this paper presents an innovative real-time physics-based VS model of assembly systems with compliant sheet-metal parts. The proposed methodology involves a non-intrusive reduced-order model (niROM), empowered by a novel adaptive sampling procedure for dataset generation, and a cross-validation-based optimized radial basis function (RBF) formulation for interpolation. Demonstrated through two case studies—(i) a remote laser welding operation to predict mechanical distortions, with two input parameters, and (ii) the assembly of an aircraft vertical stabilizer with five input parameters—the methodology achieves accurate real-time results, with up to a 43% improvement in accuracy compared to traditional sampling techniques. Findings highlight the critical influence of the sampling strategy and the number of input parameters on ROM accuracy. Better results are reached by employing adaptive sampling in combination with optimum RBF, which additionally disengages the user from the choice of the interpolation settings. This study unlocks new avenues in the field of variation simulation and dimensional/quality monitoring by narrowing the gap between any advanced CAE solver and VS models with real-time physics-based simulations.

An In Vitro Study Demonstrating the Significance of Acromioclavicular Ligament Repair in Restoring Horizontal and Rotational Acromioclavicular Joint Stability.

The principle of joint reconstruction surgery is to try to recreate the native joint biomechanics and stability. With respect to acromioclavicular joint (ACJ) surgery, much focus to date has been on restoring the superoinferior stability. There is concern that persistent horizontal instability following ACJ reconstruction could lead to poorer patient outcomes; therefore, we evaluated whether acromioclavicular (AC) ligament repair offers improved horizontal stability in conjunction with ACJ reconstruction. A whole-body human cadaver was used. The ACJ was exposed and subjected to a constant 70N load on the lateral end of the clavicle to test the anteroposterior (AP), superoinferior (SI), and horizontal pivot angle (HPA) around the ACJ. The AC and coracoclavicular (CC) ligaments were subsequently divided, and the above three parameters were re-tested. Ligament augmentation and reconstruction system (Corin Group, Cirencester, UK), LockDown (LockDown Medical Limited, Redditch, UK), Endobutton (Smith and Nephew Inc.,London, UK), and Neoligament implant (Xiros Ltd., Leeds, UK) were used to reconstruct the CC ligaments and tested with and without AC repair. The native ACJ allowed an average 2.48 mm AP and 3.88 mm SI translation with a 27° HPA. All synthetic implants significantly improved the vertical stability of the ACJ but allowed up to a four-fold increase in AP translation. Coupled with ACJ repair, all the reconstructions were far superior, especially in restoring horizontal stability. The implants varied in their approach to fixation and concentrated primarily on the reconstruction of CC ligaments. Our study was able to demonstrate that AC repair significantly improves the stability of the construct and significantly reduces vertical and horizontal instability.

High Vertical and Horizontal Stability at Short-Term Follow-Up After an All-Endoscopic Double Cerclage Endobutton Technique for Acute Acromioclavicular Joint Separations

PurposeThe aim of this study was to evaluate the clinical and radiological outcomes in the treatment of acute acromioclavicular joint (ACJ) separations using an all-endoscopic double cerclage endobutton technique compared to an arthroscopic-assisted single bundle endobutton technique. The secondary aim was to analyze the complication, failure and revision rate of both procedures. Material and methodsAll patients with acute ACJ separations Rockwood IIIB and V who were operated on using an all-endoscopic double-cerclage technique (2019-2022) or an arthroscopic-assisted single bundle technique (2017-2019) were included. The follow-up period was at least 12 months. Clinical and radiographic assessment was performed at follow-up. Complications, failures, and the revision rate were also investigated. ResultsTwenty-eight patients (14 double cerclage group, 14 single bundle group, all male) with an average age of 37 (IQR: 15) years were available for follow-up after 45 (IQR: 38) months. The median time between trauma and surgery was 7 (IQR: 8) days. Very good clinical results without significant differences were observed in both groups (Constant score: 94 (IQR: 12) vs. 95 (IQR: 15), p=0.427, ACJ Instability score: 95 (IQR: 11) vs 87 (IQR: 22), p=0.210). All patients returned to sport, with an average sports level of 95% compared to the preoperative status. The single bundle group showed significantly increased anteroposterior instability (6 vs. 0, p=0.006). A total of 5 complications occurred (2 vs. 3), leading to 1 revision surgery in each group. ConclusionExcellent clinical results and high vertical and horizontal stability can be achieved with the all-endoscopic double cerclage technique. Horizontal instability occurred significantly more frequently with the single bundle technique. The prolonged operation time in the double cerclage group had no negative impact on postoperative outcomes, including complication and failure rates, and a learning curve to reduce this prolonged operative time should be considered. Level of EvidenceIII, retrospective comparative clinical series

Acromioclavicular Joint Reconstruction with Modified Weaver–Dunn Operation Versus Hamstring Tendon Autograft Comparative Study

Abstract Background: The dislocation of the acromioclavicular joint (ACJ) is recognized as one of the most frequently occurring injuries most often after either direct or indirect force is applied to the affected shoulder. The best method of AC reconstruction is still controversial. Modified Weaver–Dunn operation (WD) is one of the popular operations. Recent ACJ reconstruction methods include the usage of the gracilis, semitendinosus auto grafts, synthetic grafts, end buttons, nonabsorbable sutures, suture anchors, and tight-rope system. Aim and Objectives: Clinical and radiological results of hamstring autograft versus modified WD operation for reconsrtuction of coracoclavicular and acromioclavicular ligaments. Patients and Methods: This prospective study was carried out at the orthopedic department of Benha University Hospital carried out on 30 cases with chronic ACJ dislocation. They divided into two groups. The modified WD technique was employed on 15 patients, whereas an autogenous semitendinosus tendon graft was used on the other 15. There was a comparison of radiographs taken before and after surgery. Results: Mean surgical time and coracoclavicular (CC) distance differed statistically between groups. Neither demographic data nor postoperative information (pain, range of motion, and postop) showed a difference of statistical significance between the groups. Constant score and post operative American Shoulder and Elbow Surgeons Score (ASES) and post operative complications show no statistically significant difference. Conclusion: Both AC and CC reconstruction by hamstring tendon autograft showed good-to-excellent outcomes with no implant-related complications as some other treatment methods, also more anatomical procedure more than WD operation with better biomechanical vertical and horizontal stability.

Relationship between foot morphologic characteristic and postural control after jump-landing in youth competitive athletes.

Foot arch dynamics play an important role in dynamic postural control. Association between foot arch dynamics and postural control among adolescent athletes remains poorly explored. To examine the relationship between foot arch dynamics, intrinsic foot muscle (IFM) morphology, and toe flexor strength and dynamic postural stability after jump landing and repetitive rebound jump performance in competitive adolescent athletes. Based on foot arch dynamics, evaluated from relative change in the foot arch height in sitting and standing positions, 50 adolescent athletes were classified as stiff, normal, or flexible. IFM morphology was evaluated by ultrasonography. Dynamic postural stability index (DPSI) was measured as participants jumped and landed with the right leg onto a force plate, whereas repetitive rebound jumping performance was assessed using the jump height and reactive jump index. The stiff group had a significantly worse DPSI and vertical stability index than the normal group (p= 0.26, p= 0.44, respectively), and worse anteroposterior stability index (APSI) values than the flexible group (p= 0.005). Multivariate regression models of the relationship between the APSI and foot arch dynamics showed adequate power (probability of error = 0.912). Increased foot arch stiffness negatively affects dynamic balance during jump-landing, which may deteriorate their performance.

Study on the Vertical Stability of Drilling Wellbore under Optimized Constraints

With the development of coal resource extraction and wellbore construction proceeding towards deeper depths, the stability of drilling wellbore structures has become increasingly severe, even posing a barrier to the use of drilling method technology in deep wellbore construction. To address this issue, this study raised an optimized constraints method involving pre-throwing cement slurry to the bottom before wellbore decent, altering bottom constraints. Firstly, the critical depth and instability criterion of this optimized method was derived by catastrophe theory. Subsequently, the role of single-factor and multi-factor sensitivity analyses on critical depth was discussed. The engineering effects of optimized constraint methods were contrasted and examined in several drilling projects. Finally, the characteristic values of real engineering were computed using numerical techniques and ABAQUS2020 software, and the efficacy of optimization approaches was examined and validated. The results revealed that the critical depth increased by 41.39 ± 5%. The influence factors described in order of the degree were the counterweight water height, the elastic modulus, the thickness of the wellbore, and the self-weight of the wellbore, sequentially. The conclusion on structural stability between the numerical calculation solution and theoretical calculation solution was completely the same. The optimized constraints method can effectively improve the stability of the wellbore structure.

Current Concepts in Management of Acromioclavicular Joint Injury.

Background: The management of acromioclavicular joint injuries requires a thorough understanding of the anatomy and biomechanics of the joint, as well as knowledge of the pertinent physical exam findings and classification to determine an appropriate treatment approach, whether operative or nonoperative. In this article, we present a narrative review of the current state of understanding surrounding these issues. Although there are a large number of options for operative intervention, we additionally present our experience with anatomic coracoclavicular ligament reconstruction (ACCR) with imbrication of the deltoid fascia. Methods: A retrospective review of prospectively collected data on a total of 45 patients who had undergone ACCR between 2003 and 2016 were collected. Results: We found that improvements were seen in American Shoulder and Elbow Surgeons Score (ASES) (53 ± 19 to 81 ± 23), Simple Shoulder Test (SST) (6 ± 3 to 12 ± 13), Constant-Murley (CM) (60 ± 18 to 92 ± 8), and Rowe (67 ± 14 to 89 ± 11) and the mean post-operative SANE score was 86 ± 17. Conclusions: ACCR has the advantage of addressing both horizontal and vertical stability with good outcomes.

Functional reconstruction of chronic acromioclavicular joint separation using a double suture technique combined with semitendinosus autograft.

We present the functional and clinical results of a combined surgical technique that functionally restores chronic Acromioclavicular Joint Instability (AJI). The method combines a double-looped suture fixation augmented with a semitendinosus autograft. Between 2017 and 2021, 15 patients were treated using the surgical technique. All patients suffered an Acromioclavicular Joint Separation that remained untreated for at least 6 (6-16) weeks after the initial injury. Four Ethibond sutures were passed below the coracoid process and through a 4.5 drill hole in the clavicle. The sutures provided adequate horizontal and vertical reduction and stabilization of the clavicle. A semitendinosus autograft was passed below the coracoid process and looped around the clavicle. The remaining graft limbs were used to reconstruct the acromioclavicular capsule. Patients were radiologically evaluated with bilateral anteroposterior (AP), Zanca, and Alexander views. The clinical evaluation was based on the Acromioclavicular Joint Instability Score and the Constant-Murley Score. The mean follow-up period was 31.2months (17-61). The mean last ACJIS and CMS scores were 96 (90-100) and 97.67 (87-100), respectively. Reduction of the clavicle was radiologically confirmed in all cases throughout the follow-up period. AC arthritis was reported in 1 case without associated clinical symptoms. No significant complications were reported, and all patients returned to the pre-injury activity level. The presented functional reconstruction of the AC joint disruption in chronic cases is an effective and secure method with low complication rates and good clinical results. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

What caused large ozone variabilities in three megacity clusters in eastern China during 2015–2020?

Abstract. Due to a robust emission control policy, significant reductions in major air pollutants, such as PM2.5, SO2, NO2, and CO, were observed in China between 2015 and 2020. On the other hand, during the same period, there was a notable increase in ozone (O3) concentrations, making it a prominent air pollutant in eastern China. The annual mean concentration of maximum daily 8 h average (MDA8) O3 exhibited alarming linear increases of 2.4, 1.1, and 2.0 ppb yr−1 (ppb is for parts per billion) in three megacity clusters: Beijing–Tianjin–Hebei (BTH), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD), respectively. Meanwhile, there was a significant 3-fold increase in the number of O3-exceeding days, defined as MDA8 O3 &gt; 75 ppb. Our analysis indicated that the upward increases in the annual mean concentration of MDA8 were primarily driven by the rise in consecutive O3-exceeding days. There were expansions of high O3 in urban centers to rural areas accompanied by a saturation effect so that MDA8 O3 concentrations at the high-O3 stations in 2015 remained nearly constant at 100 ppb. Last, we found a close association between O3 episodes with 4 or more consecutive O3-exceeding days and the position and strength of tropical cyclones (TCs) in the northwest Pacific and the West Pacific subtropical high (WPSH). The TC and WPSH contributed to meteorological conditions characterized by clear skies, subsiding air motion, high vertical stability in the lower troposphere, increased solar radiation, and a positive temperature anomaly at the surface. These favorable meteorological conditions greatly facilitated the formation of O3. Thus, we propose that the worsening O3 increases observed in the BTH, YRD, and PRD regions from 2015 to 2020 can be mostly attributed to enhanced photochemical O3 production resulting from an increased occurrence of meteorological conditions with high solar radiation and positive temperature anomalies under the influence of the WPSH and TCs.