Stereoscopic diagnosing of a filament-cavity flux rope system by tracing the path of a two-sided-loop jet

The fine magnetic structure is vitally important to understanding the formation, stabilization and eruption of solar filaments, but so far, it is still an open question yet to be resolved. Using stereoscopic observations taken by the Solar Dynamics Observatory and Solar TErrestrial RElations Obsevatory, we studied the generation mechanism of a two-sided-loop jet (TJ) and the ejection process of the jet plasma into the overlying filament-cavity system. We find that the generation of the two-sided-loop jet was due to the magnetic reconnection between an emerging flux loop and the overlying filament. The jet's two arms ejected along the filament axis during the initial stage. Then, the north arm bifurcated into two parts at about 50 Mm from the reconnection site. After the bifurcation, the two bifurcated parts were along the filament axis and the cavity which hosted the filament, respectively. By tracing the ejecting plasma flows of the TJ inside the filament, we not only measured that the magnetic twist stored in the filament was at least 5$\pi$ but also found that the fine magnetic structure of the filament-cavity flux rope system is in well agreement with the theoretical results of Magnetic flux rope models.Comment: 6 pages, 7 figures. Accepted by the MNRAS Letter

Total reflection of a flare-driven quasi-periodic extreme ultraviolet wave train at a coronal hole boundary

Context. A flare-driven quasi-periodic extreme ultraviolet wave train totally reflected at a coronal hole boundary was well imaged on both temporal and spatial scales by AIA/SDO. Aims. We aim to investigate the driving mechanisms of the quasi-periodic wave train and demonstrate the total reflection effect at the coronal hole boundary. Methods. The speeds of the incident and reflected wave trains are studied. The periodic correlation of the wave trains with the related flare is probed. We compare the measured incidence angle and the estimated critical angle. Results. We find that the periods of the incident and reflected wave trains are both about 100 s. The excitation of the quasi-periodic wave train was possibly due to the intermittent energy release in the associated flare since its period is similar to that of the quasi-periodic pulsations in the associated flare. Our observational results show that the reflection of the wave train at the boundary of the coronal hole was a total reflection because the measured incidence and critical angles satisfy the theory of total reflection: the incidence angle is smaller than the critical angle

Fast and Fine Location of Total Lightning from Low Frequency Signals Based on Deep-Learning Encoding Features

Lightning location provides an important means for the study of lightning discharge process and thunderstorms activity. The fine positioning capability of total lightning based on low-frequency signals has been improved in many aspects, but most of them are based on post waveform processing, and the positioning speed is slow. In this study, artificial intelligence technology is introduced for the first time to lightning positioning, based on low-frequency electric-field detection array (LFEDA). A new method based on deep-learning encoding features matching is also proposed, which provides a means for fast and fine location of total lightning. Compared to other LFEDA positioning methods, the new method greatly improves the matching efficiency, up to more than 50%, thereby considerably improving the positioning speed. Moreover, the new algorithm has greater fine-positioning and anti-interference abilities, and maintains high-quality positioning under low signal-to-noise ratio conditions. The positioning efficiency for return strokes of triggered lightning was 99.17%, and the standard deviation of the positioning accuracy in the X and Y directions was approximately 70 m

Macrospicules and Their Connection to Magnetic Reconnection in the Lower Solar Atmosphere

Solar macrospicules are beam-like cool plasma ejections of size in between spicules and coronal jets, which can elucidate potential connections between plasma jetting activity at different scales. With high-resolution observations from the New Vacuum Solar Telescope and Solar Dynamics Observatory, we investigate the origin of five groups of recurrent active-region macrospicules. Before the launch of each macrospicule, we detect a compact bright patch (BP) at its base where a newly emerging dipole contacts and cancel with the preexisting ambient field. The spectral diagnosis from the Interface Region Imaging Spectrograph at one of BPs reveals signatures of reconnection at the lower atmosphere. Multiwavelength imaging of these BPs show that they mainly occur at the rising phase of the flux emergence and slowly ascend from the lower to the upper chromosphere. Remarkable macrospicules occur and fade out once the BPs appear and decay from the AIA 304 Å images, respectively. We suggest that these macrospicules and related BPs form in a common reconnection process, in which the increasing reconnection height between the emerging dipole and the ambient field results in the observed variations from BPs to macrospicules. Interestingly, most macrospicules show similar characteristics to larger-scale coronal jets and/or smaller-scale spicules, i.e., the rotating motions, the presence of minifilaments and BPs before the eruptions, and magnetic flux emergence and cancellation. We conclude that the formation mechanism of macrospicules should be the same as spicules and coronal jets, i.e., solar jetting phenomena at different scales share the same physical mechanism in association with magnetic reconnection

Application and effect of tension-reducing suture in surgical treatment of hypertrophic scar

Abstract Purpose To investigate the application and effectiveness of tension-reducing suture in the repair of hypertrophic scars. Methods A retrospective analysis of clinical data was conducted on 82 patients with hypertrophic scars treated at the Department of Burns and Plastic Surgery of Nanjing Drum Tower Hospital from September 2021 to December 2022. Patients were operated with combination of heart-shaped tension-reducing suturing technique and looped, broad, and deep buried (LBD) suturing technique or conventional suture method. Outcomes of surgical treatment were assessed before and 6 months after surgery using the Patient and Observer Scar Assessment Scale (POSAS) and the Vancouver Scar Scale (VSS). Results Improvements were achieved on scar quality compared to that preoperatively, with a reduction in scar width (1.7 ± 0.6 cm vs. 0.7 ± 0.2 cm, P < 0.001). Assessment using the POSAS and VSS scales showed significant improvements in each single parameter and total score compared to preoperative values (P < 0.05). The Combination method group achieved better score in total score of VSS scale, in color, stiffness, thickness and overall opinion of PSAS scale, and in vascularity, thickness, pliability and overall opinion of OSAS scale. Conclusion The amalgamation of the heart-shaped tension-reducing suturing technique and the LBD suturing technique has shown promising outcomes, garnering notably high levels of patient satisfaction in the context of hypertrophic scar repair. Patients have exhibited favorable postoperative recoveries, underscoring the clinical merit and the prospective broader applicability of this approach in the realm of hypertrophic scar management

White-light QFP wave train and the associated failed breakout eruption

Quasi-periodic fast-propagating (QFP) magnetosonic wave trains are commonly observed in the low corona at extreme ultraviolet wavelength bands. Here, we report the first white-light imaging observation of a QFP wave train propagating outwardly in the outer corona ranging from 2 to 4 R⊙. The wave train was recorded by the Large Angle Spectroscopic Coronagraph on board the Solar and Heliospheric Observatory (SOHO), and was associated with a GOES M1.5 flare in NOAA active region AR12172 at the southwest limb of the solar disk. Measurements show that the speed and period of the wave train were about 218 km s−1 and 26 min, respectively. The extreme ultraviolet imaging observations taken by the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory reveal that in the low corona the QFP wave train was associated with the failed eruption of a breakout magnetic system consisting of three low-lying closed loop systems enclosed by a high-lying large-scale one. Data analysis results show that the failed eruption of the breakout magnetic system was mainly because of the magnetic reconnection that occurred between the two lateral low-lying closed-loop systems. This reconnection enhances the confinement capacity of the magnetic breakout system because the upward-moving reconnected loops continuously feed new magnetic fluxes to the high-lying large-scale loop system. For the generation of the QFP wave train, we propose that it could be excited by the intermittent energy pulses released by the quasi-periodic generation, rapid stretching, and expansion of the upward-moving, strongly bent reconnected loops

Isomerization and bioaccessibility of cypermethrin and fenpropathrin in Pacific oyster during simulated digestion as influenced by domestic cooking methods

Pyrethroids can be ingested by humans through eating contaminated oysters, which is potentially harmful to health. This study aimed to investigate the effects of raw, steaming, and roasting on cypermethrin (CP) and fenpropathrin (FP) in oysters during simulated digestion. Results showed that the amount of released CP and FP was different from raw (CP: 0.617 µg·g−1, FP: 0.266 µg·g−1), steaming (CP: 0.498 µg·g−1, FP: 0.660 µg·g−1), and roasting (CP: 1.186 µg·g−1, FP: 0.588 µg·g−1) at the end of simulated digestion. The share of cis-CP and low-efficiency CP increased significantly (p < 0.05), and the share of high-efficiency trans-CP did not maintain a high level for a long time during simulated digestion. The fluorimetric titration and isothermal titration calorimetry confirmed that CP and FP could spontaneously interact with oyster actin, and CP could bind with oyster actin more tightly than FP. This study reveals that cooking methods affect the binding capacity of CP and FP to oyster tissues and influence the changes of CP and FP in oysters during digestion. Furthermore, the current study provides a reference for assessing the potential harm of pyrethroids in oysters to consumers

Double-decker Pair of Flux Ropes Formed by Two Successive Tether-cutting Eruptions

Double-decker filaments and their eruptions have been widely observed in recent years, but their physical formation mechanism is still unclear. Using high spatiotemporal resolution, multi-wavelength observations taken by the New Vacuum Solar Telescope and the Solar Dynamics Observatory, we show the formation of a double-decker pair of flux rope system by two successive tether-cutting eruptions in a bipolar active region. Due to the combined effect of photospheric shearing and convergence motions around the active region’s polarity inversion line (PIL), the arms of two overlapping inverse-S-shaped short filaments reconnected at their intersection, which created a simultaneous upward-moving magnetic flux rope (MFR) and a downward-moving post-flare-loop (PFL) system striding the PIL. Meanwhile, four bright flare ribbons appeared at the footpoints of the newly formed MFR and the PFL. As the MFR rose, two elongated flare ribbons connected by a relatively larger PFL appeared on either side of the PIL. After a few minutes, another MFR formed in the same way at the same location and then erupted in the same direction as the first one. Detailed observational results suggest that the eruption of the first MFR might experienced a short pause before its successful eruption, while the second MFR was a failed eruption. This implies that the two newly formed MFRs might reach a new equilibrium at relatively higher heights for a while, which can be regarded as a transient double-decker flux rope system. The observations can well be explained by the tether-cutting model, and we propose that two successive confined tether-cutting eruptions can naturally produce a double-decker flux rope system, especially when the background coronal magnetic field has a saddle-like distribution of magnetic decay index profile in height

Additional file 1 of Application and effect of tension-reducing suture in surgical treatment of hypertrophic scar

Supplementary Material