Are Solar Active Regions Born with Neutralized Currents?

Solar active regions(ARs)are formed by the emergence of current-carrying magnetic flux tubes from below the photosphere.Although for an isolated flux tube the direct and return currents flowing along the tube should balance with each other,it remains controversial whether such a neutralization of currents is also maintained during the emergence process.Here we present a systematic survey of the degrees of the current neutralization in a large sample of flux-emerging ARs which appeared on the solar disk around the central meridian from 2010 to 2022.The vector magnetograms taken by Helioseismic and Magnetic Imager onboard Solar Dynamic Observatory are employed to calculate the distributions of the vertical current density at the photosphere.Focusing on the main phase of flux emergence,i.e.,the phase in which the total unsigned magnetic flux is continuously increased,we statistically examined the ratios of direct to return currents in all the ARs.Such a large-sample statistical study suggests that most of the ARs were born with currents close to neutralization.The degree of current neutralization seems to be not affected by the active-region size,the active-region growing rate,and the total unsigned current.The only correlation of significance as found is that the stronger the magnetic field nonpotentiality is,the further the AR deviates from current neutrality,which supports previous event studies that eruption-productive ARs often have non-neutralized currents.

A Comprehensive Classification and Analysis of Geomagnetic Storms Over Solar Cycle 24

A geomagnetic storm is a global disturbance of Earth?s magnetosphere,occurring as a result of the interaction with magnetic plasma ejected from the Sun.Despite considerable research,a comprehensive classification of storms for a complete solar cycle has not yet been fully developed,as most previous studies have been limited to specific storm types.This study,therefore,attempted to present complete statistics for solar cycle 24,detailing the occurrence of geomagnetic storm events and classifying them by type of intensity(moderate,intense,and severe),type of complete interval(normal or complex),duration of the recovery phase(rapid or long),and the number of steps in the storm?s development.The analysis was applied to data from ground-based magnetometers,which measured the Dst index as provided by the World Data Center for Geomagnetism,Kyoto,Japan.This study identified 211 storm events,comprising moderate(177 events),intense(33 events),and severe(1 event)types.About 36%of ICMEs and 23%of CIRs are found to be geoeffective,which caused geomagnetic storms.Up to four-step development of geomagnetic storms was exhibited during the main phase for this solar cycle.Analysis showed the geomagnetic storms developed one or more steps in the main phase,which were probably related to the driver that triggered the geomagnetic storms.A case study was additionally conducted to observe the variations of the ionospheric disturbance dynamo(Ddyn)phenomenon that resulted from the geomagnetic storm event of 2015July 13.The attenuation of the Ddyn in the equatorial region was analyzed using the H component of geomagnetic field data from stations in the Asian sector(Malaysia and India).The variations in the Ddyn signatures were observed at both stations,with the TIR station(India)showing higher intensity than the LKW station(Malaysia).

Coronal plane stability of cruciate-retaining total knee arthroplasty in valgus gonarthrosis patients:A mid-term evaluation using stress radiographs

BACKGROUND Total knee arthroplasty(TKA)using implants with a high level of constraint has generally been recommended for patients with osteoarthritis(OA)who have valgus alignment.However,studies have reported favorable outcomes even with cruciate-retaining(CR)implants.AIM To evaluate the coronal plane stability of CR-TKA in patients with valgus OA at the mid-term follow-up.METHODS Patients with primary valgus OA of the knee who underwent TKA from January 2014 to January 2021 were evaluated through stress radiography using a digital stress device with 100 N of force on both the medial and lateral side.Gap openings and degrees of angulation change were determined.Descriptive statistical analysis was performed for both continuous and categorical variables.Inter-rater reliability of the radiographic measurements was evaluated using Cronbach’s alpha.RESULTS This study included 25 patients(28 knees)with a mean preoperative mechanical valgus axis of 11.3(3.6-27.3)degrees.The mean follow-up duration was 3.4(1.04-7.4)years.Stress radiographs showed a median varus and valgus gap opening of 1.6(IQR 0.6-3.0)mm and 1.7(IQR 1.3-2.3)mm and varus and valgus angulation changes of 2.5(IQR 1.3-4.8)degrees and 2.3(IQR 2.0-3.6)degrees,respectively.No clinical signs of instability,implant loosening,or revision due to instability were observed throughout this case series.CONCLUSION The present study demonstrated that using CR-TKA for patients with valgus OA of the knee promoted excellent coronal plane stability.

Finite Element Analysis of Coronal Shear Fractures of the Femoral Neck: Displacement of the Femoral Head and Effect of Osteosynthetic Implants

Coronal shear fractures of the femoral neck (CSFF) are the most challenging to treat among proximal femur fractures, directly affecting the life expectancy of patients with osteoporosis. However, an adequate osteosynthesis method has not been elucidated yet. This study investigated the displacement direction of the femoral head fragment and its effect on the bone using finite element method. A finite element model for CSFF was developed from CT image data of a patient with osteoporosis using Mechanical Finder (ver. 11). Subsequently, finite element analyses were performed on six osteosynthesis models under maximum load applied during walking. The compressive stresses, tensile stresses, and compressive strains of each model were examined. The results suggested that the compressive and tensile stress distributions were concentrated on the anterior side of the femoral neck. Compressive strain distribution in the femoral head and neck was concentrated in four areas: at the tip of the blade or lag screw, the anteroinferior side of the blade or lag screw near the fracture site, and the upper right and lower left near the junction of the blade or lag screw and nail. Thus, the distribution of both these stresses revealed that the femoral head fragment was prone to anterior and inferior displacement. Distribution of compressive strains revealed the direction of the stress exerted by the osteosynthetic implant on the bone. The same results were observed in all osteosynthetic implants;thus, the findings could lay the foundation for developing methods for placing osteosynthetic implants less prone to displacement and the osteosynthetic implants themselves. In particular, the study provides insight into the optimal treatment of CSFF.

Breaking of Large-Scale Filament due to Magnetic Reconnection and Consequent Partial Eruption

Following our previous work,we studied the partial eruption of a large-scale horse-shoe-like filament that had beenobserved in a decaying active region on the solar disk for more than 4.5 days.The filament became active after itwas broken into two pieces,P1 and P2 seen in Hα,by magnetic reconnection between the magnetic field around itand that of a newly emerging active region nearby.P1 eventually erupted 13 hr after the breaking and escaped fromthe Sun,developing to a fast coronal mass ejection,and P2 stayed.But the mass in P1 falling down to P2 in theeruption suggests that the global magnetic fields over P1 and P2 were still connected to each other prior to theeruption.The reconnection process breaking the filament occurred outside the filament,and P1 and P2 were locatedalmost at the same altitude,so the fashion of the filament partial eruption studied here differs from that of the“double-decker model”and that of reconnection inside the filament.Analyzing the decay indices of thebackground fields above P1 and P2,n_(1)and n_(2),showed that the altitude where n_(1)exceeds the critical value of n_(c)=1.5 for the loss of equilibrium or the torus instability is lower than that where n_(2)>nc,and that n_(1)>n_(2) alwaysholds at all altitudes.Combining this fact with that the eruption occurred 13 hr after filament was broken byreconnection,we conclude that the eruption of P1 was triggered by the loss of equilibrium or the torus instability inthe configuration,and magnetic reconnection breaking the filament helped weaken the confinement of thebackground field on P1,allowing P1 to erupt.Detailed features of the eruption and the corresponding physicalscenario were also discussed.

A Revised Graduated Cylindrical Shell Model and its Application to a Prominence Eruption

In this paper,the well-known graduated cylindrical shell(GCS)model is slightly revised by introducing longitudinal and latitudinal deflections of prominences originating from active regions(ARs).Subsequently,it is applied to the three-dimensional(3D)reconstruction of an eruptive prominence in AR 13110,which produced an M1.7 class flare and a fast coronal mass ejection(CME)on 2022 September 23.It is revealed that the prominence undergoes acceleration from~246 to~708 km s^(-1).Meanwhile,the prominence experiences southward deflection by 15°±1°without longitudinal deflection,suggesting that the prominence erupts non-radially.Southward deflections of the prominence and associated CME are consistent,validating the results of fitting using the revised GCS model.Besides,the true speed of the CME is calculated to be 1637±15 km s^(-1),which is~2.3 times higher than that of prominence.This is indicative of continuing acceleration of the prominence during which flare magnetic reconnection reaches maximum beneath the erupting prominence.Hence,the reconstruction using the revised GCS model could successfully track a prominence in its early phase of evolution,including acceleration and deflection.

Global Energetics of Solar Powerful Events on 2017 September 6

Solar flares and coronal mass ejections(CMEs)are thought to be the most powerful events on the Sun.They can release energy as high as~10^(32)erg in tens of minutes,and also can release solar energetic particles(SEPs)into interplanetary space.We explore global energy budgets of solar major eruptions that occurred on 2017 September 6,including the energy partition of a powerful solar flare,and the energy budget of the accompanying CME and SEPs.In the wavelength range shortward of~222 nm,a major contribution of the flare radiated energy is in the soft X-ray(SXR)0.1-7 nm domain.The flare energy radiated at wavelengths of Lyαand mid-ultraviolet is larger than that radiated in the extreme ultraviolet wavelengths,but it is much less than that radiated in the SxR waveband.The total flare radiated energy could be comparable to the thermal and nonthermal energies.The energies carried by the major flare and its accompanying CME are roughly equal,and they are both powered by the magnetic free energy in the NOAA AR 12673.Moreover,the CME is efficient in accelerating SEPs,and the prompt component(whether it comes from the solar flare or the CME)contributes only a negligible fraction.

Investigation on the Formation of Herringbone Structure in TypeⅡSolar Radio Bursts

We report detailed observation of the“herringbone”of a Type II solar radio burst that occurred on 2010 November 3rd.Data from the Space Weather Prediction Center,National Oceanic and Atmospheric Administration,e-CALLISTO,and Nan?ay Radio Heliograph are analyzed.We determine the brightness temperature and degree of circular polarization of the“herringbone”burst.Correlations between the physical parameters and the“herringbone”are examined.Based on the relationship,this is the first study that suggested this“herringbone”was generated through fundamental plasma.

An in Vitro Analysis to Evaluate Coronal Residual Dentine Thickness after Different Anterior Crown Preparations

Background: Knife edge, chamfer, and shoulder are the three distinct finishing lines utilized in crown preparations. Each finishing line has relative benefits and drawbacks. However, not much scientific data exists regarding which of these finishing lines will leave the most amount of residual dentine coronally on maxillary lateral incisors and mandibular incisors. Objective: To assess the coronal residual dentine thickness after different cervical finishing lines for anterior crown preparations. Materials and Methods: A prospective comparative study was conducted including mandibular incisors and maxillary laterals that were taken from subjects from 18 to 30 years old. Teeth in each of the three groups were randomly separated into three cervical margin preparation groups: knife edge, chamfer and shoulder. The teeth were then prepared for single crown coverage using these finishing lines. The teeth were sectioned halfway through the crown preparation, and a digital caliper was used to determine the residual dentine thickness at the buccal, lingual, mesial and distal areas. The Tukey test was used for mean comparison, and ANOVA analysis was used to evaluate the variation in mean residual dentine thickness. Results: For upper lateral incisors, knife edge finishing lines showed the highest amount of remaining dentine thickness—1.5 mm. lingually, while the upper lateral incisors mesially had the least amount of 0.53 mm for shoulder finishing lines. The least residual dentine (0.53 mm for the shoulder and 0.70 mm for the chamfer finishing line) was found in the interproximal portions of all the teeth that were selected. Lower central incisors had the least amount of residual dentine 0.61 mm for shoulder preparations mesially whiles lower lateral incisors had the least amount of residual dentine for shoulder preparations 0.58 mm distally. There was a statistically significant difference of 0.001 across the groups. Conclusion: The thickness of residual dentine seen coronally after the three finishing line preparations showed a statistically significant difference and the knife edge finishing line provided enough coronal protection within the scope of this study.

Management of distal humeral coronal shear fractures

Coronal shear fractures of the distal humerus are rare,complex fractures that can be technically challenging to manage. They usually result from a low-energy fall and direct compression of the distal humerus by the radial head in a hyper-extended or semi-flexed elbow or from spontaneous reduction of a posterolateral subluxation or dislocation. Due to the small number of soft tissue attachments at this site, almost all of these fractures are displaced. The incidence of distal humeral coronal shear fractures is higher among women because of the higher rate of osteoporosis in women and the difference in carrying angle between men and women. Distal humeral coronal shear fractures may occur in isolation, may be part of a complex elbow injury, or may be associated with injuries proximal or distal to the elbow. An associated lateral collateral ligament injury is seen in up to 40% and an associated radial head fracture is seen in up to 30% of these fractures. Given the complex nature of distal humeral coronal shear fractures, there is preference for operative management. Operative fixation leads to stable anatomic reduction, restores articular congruity, and allows initiation of early range-of-motion movements in the majority of cases. Several surgical exposure and fixation techniques are available to reconstruct the articular surface fol owing distal humeral coronal shear fractures. The lateral extensile approach and fixation with countersunk headless compression screws placed in an anterior-to-posterior fashion are commonly used. We have found a two-incision approach(direct anterior and lateral) that results in less soft tissue dissection and better outcomes than the lateral extensile approach in our experience. Stiffness, pain, articular incongruity, arthritis, and ulnohumeral instability may result if reduction is non-anatomic or if fixation fails.

The Lyman-alpha Solar Telescope (LST) for the ASO-S mission——Ⅰ. Scientific objectives and overview

As one of the payloads for the Advanced Space-based Solar Observatory(ASO-S)mission,the Lyman-alpha(Lyα)Solar Telescope(LST)is aimed at imaging the Sun and the inner corona up to 2.5 R⊙(mean solar radius)in both the Lyα(121.6 nm)and visible wavebands with high temporo-spatial resolution,mainly targeting solar flares,coronal mass ejections(CMEs)and filaments/prominences.LST observations allow us to trace solar eruptive phenomena from the disk center to the inner corona,to study the relationships between eruptive prominences/filaments,solar flares and CMEs,to explore the dynamical processes and evolution of solar eruptions,to diagnose solar winds,and to derive physical parameters of the solar atmosphere.LST is actually an instrument suite,which consists of a Solar Disk Imager(SDI),a Solar Corona Imager(SCI),a White-light Solar Telescope(WST)and two Guide Telescopes(GTs).This is the first paper in a series of LST-related papers.In this paper,we introduce the scientific objectives,present an overview of the LST payload and describe the planned observations.The detailed design and data along with potential diagnostics are described in the second(Paper II)and third(Paper III)papers,respectively,appearing in this issue.

Numerical Simulation of the 12 May 1997 CME Event

Our newly developed CESE MHD model is used to simulate sun-earth connection event with the well-studied 12 May 1997 CME event as an example. The main features and approximations of our numerical model are as follows： （1） The modifed conservation element and solution element （CESE） numerical scheme in spherical geometry is implemented in our code. （2） The background solar wind is derived from a 3D time-dependent numerical MHD model by input measured photospheric magnetic fields. （3） Transient disturbances are derived from solar surface by introducing a mass flow of hot plasma. The numerical simulation has enabled us to predict the arrival of the interplanetary shock and provided us with a relatively satisfactory comparison with the WIND spacecraft observations.

The Lyman-alpha Solar Telescope(LST) for the ASO-S mission——Ⅲ. data and potential diagnostics

The Lyman-alpha Solar Telescope(LST)is one of the three payloads onboard the Advanced Space-based Solar Observatory(ASO-S)mission.It aims at imaging the Sun from the disk center up to 2.5 R⊙targeting solar eruptions,particularly coronal mass ejections(CMEs),solar flares,prominences/filaments and related phenomena,as well as the fast and slow solar wind.The most prominent speciality of LST is the simultaneous observation of the solar atmosphere in both Lyαand white light(WL)with high temporospatial resolution both on the solar disk and the inner corona.New observations in the Lyαline together with traditional WL observations will provide us with many new insights into solar eruptions and solar wind.LST consists of a Solar Corona Imager(SCI)with a field of view(FOV)of 1.1–2.5 R⊙,a Solar Disk Imager(SDI)and a full-disk White-light Solar Telescope(WST)with an identical FOV up to 1.2 R⊙.SCI has a dual waveband in Lyα(121.6±10 nm)and in WL(700±40 nm),while SDI works in the Lyαwaveband of 121.6±7.5 nm and WST works in the violet narrow-band continuum of 360±2.0 nm.To produce high quality science data,careful ground and in-flight calibrations are required.We present our methods for different calibrations including dark field correction,flat field correction,radiometry,instrumental polarization and optical geometry.Based on the data calibration,definitions of the data levels and processing procedures for the defined levels from raw data are described.Plasma physical diagnostics offer key ingredients to understand ejecta and plasma flows in the inner corona,as well as different features on the solar disk including flares,filaments,etc.Therefore,we are making efforts to develop various tools to detect the different features observed by LST,and then to derive their physical parameters,for example,the electron density and temperature of CMEs,the outflow velocity of the solar wind,and the hydrogen density and mass flows of prominences.Coordinated observations and data analyses with the coronagraphs onboard Solar Orbiter,PROBA-3,and Aditya are also briefly discussed.

The Lyman-alpha Solar Telescope(LST) for the ASO-S mission——Ⅱ. design of LST

As one of the three payloads for the Advanced Space-based Solar Observatory(ASO-S)mission,the Lyman-alpha(Lyα)Solar Telescope(LST)is composed of three instruments:a Solar Corona Imager(SCI),a LyαSolar Disk Imager(SDI)and a full-disk White-light Solar Telescope(WST).When working in-orbit,LST will simultaneously perform high-resolution imaging observations of all regions from the solar disk to the inner corona up to 2.5 R⊙(R⊙stands for the mean solar radius)with a spatial resolution of 4.8′′and 1.2′′for coronal and disk observations,respectively,and a temporal resolution of 30–120 s and 1–120 s for coronal and disk observations,respectively.The maximum exposure time can be up to20 s due to precise pointing and image stabilization function.Among the three telescopes of LST,SCI is a dual-waveband coronagraph simultaneously and independently observing the inner corona in the HI Lyα(121.6±10 nm)line and white light(WL)(700±40 nm)wavebands by using a narrowband Lyαbeam splitter and has a field of view(FOV)from 1.1 to 2.5 R⊙.The stray-light suppression level can attain<10^-6 B⊙(B⊙is the mean brightness of the solar disk)at 1.1 R⊙and≤5×10^-8 B⊙at 2.5 R⊙.SDI and WST are solar disk imagers working in the Lyαline and 360.0 nm wavebands,respectively,which adopt an off-axis two-mirror reflective structure with an FOV up to 1.2 R⊙,covering the inner coronal edge area and relating to coronal imaging.We present the up-to-date design for the LST payload.

Propagation of Fast Magnetoacoustic Waves in Stratified Solar Atmosphere

The characteristics of magnetohydrodynamic fast wave propagation in the solar stratified atmosphere are studied by the ray tracing method. The propagation behaviour of the wavefronts is described in detail. A magnetic field incorporating the characteristics field spreading expected in flux tubes is used, which represents the main feature of an active region. Partly ionization is considered beside the stratified solar atmosphere consisting chromosphere, transition region and corona. The study may explain the characteristics in observations of Moreton and extraultraviolet image telescope （EIT） waves. The wavefront incurred by the disturbance initialized at the base of the transition region propagates fast initially due to strong magnetic field, and it slows down when arriving beyond the region of flux-tube. Meanwhile, the wave propagates in the corona with a more consistent speed, as seen in the observation of EIT waves. The speeds and propagated characteristics in chromosphere and corona of the wavefronts are in agreement with those observed in H~ Moreton and EIT waves, respectively.

Influence of coronal holes on CMEs in causing SEP events

The issue of the influence of coronal holes （CHs） on coronal mass ejections （CMEs） in causing solar energetic particle （SEP） events is revisited. It is a continuation and extension of our previous work, in which no evident effects of CHs on CMEs in generating SEPs were found by statistically investigating 56 CME events. This result is consistent with the conclusion obtained by Kahler in 2004. We extrapolate the coronal magnetic field, define CHs as the regions consisting of only open magnetic field lines and perform a similar analysis on this issue for 76 events in total by extending the study interval to the end of 2008. Three key parameters, CH proximity, CH area and CH relative position, are involved in the analysis. The new result confirms the previous conclusion that CHs did not show any evident effect on CMEs in causing SEP events.

Overview of the Solar Polar Orbit Telescope Project for Space Weather Mission

The Solar Polar ORbit Telescope(SPORT) project for space weather mission has been under intensive scientific and engineering background studies since it was incorporated into the Chinese Space Science Strategic Pioneer Project in 2011.SPORT is designed to carry a suite of remote-sensing and in-situ instruments to observe Coronal Mass Ejections(CMEs),energetic particles,solar high-latitude magnetism,and the fast solar wind from a polar orbit around the Sun.The first extended view of the polar regions of the Sun and the ecliptic enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere,and the solar high-latitude magnetism giving rise to eruptions and the fast solar wind.Coordinated observations between SPORT and other spaceborne/ground-based facilities within the International Living With a Star(ILWS) framework can significantly enhance scientific output.SPORT is now competing for official selection and implementation during China's 13 th Five-Year Plan period of 2016-2020.

Possible Connections between X-Solar Flares and Worldwide Variation in Seismicity Enhancement

We developed a?statistical study analyzing global seismicity enhancement and its variation?overtwenty years.?X-flares sometimes occur in conjunction with Coronal Mass Ejections (CME),which make their connection with the Earth’s magnetosphere stronger.?The preliminary study divided the Earth into seven regions determined by longitude and latitude, and nine levels of depth valid for most locations?in the?Pacific area.?The results showed that X beams influenced seismicity in terrestrial localities, mainly high magnitude earthquakes occurring below the crust at 70 km.?These internal enhancements happen without the presence of any external forces such as studied in Solar Speed Winds.?Nevertheless, those variations are perceptible in the presence of intense X flares and CME and less observed in the periods during which flares were absent. Two cases of high magnitude earthquakes in recent?years are analyzed, and the extreme external conditions of those events fit?with this theory.

Three-dimensional imaging of the uterus:The value of the coronal plane

Advent in three-dimensional(3D) imaging technology has seen 3D ultrasound establish itself as a useful adjunct complementary to traditional two-dimensional imaging of the female pelvis. This advantage largely arises from its ability to reconstruct the coronal plane of the uterus, which allows further delineation of many gynecological disorders. 3D imaging of the uterus is now the preferred imaging modality for assessing congenital uterine anomalies and intrauterine device localization. Newer indications include the diagnosis of adenomyosis. It can also add invaluable information to delineate other endometrial and myometrial pathology such as fibroids and endometrial polyps.

Sun-Moon-Earth Interactions, External Factors for Earthquakes

The aim of this paper is to continue analyzing the interactions in the three-body system made up of the Sun, the Moon, and the Earth. First, we review new details about Moon-Earth connections, with a special focus on mechanical forces. Following, we expand the study to consider the pair Sun-Earth, with calculations for electromagnetic forces. The objective in both cases is to know how mechanical and electromagnetic forces affect seismological events on Earth. Our calculations found that Solar Cycles have no direct interaction with earthquake variations. Instead, we established that there is an internal discrepancy for quakes below 35 km detected in some of the regions analyzed. The results indicate that geomagnetic variations must be studied next to understand their connections to earthquakes.