Search

Anther dehiscence is a crucial event in plant reproduction, tightly regulated and dependent on the lignification of the anther endothecium. In this study, we investigated the rapid lignification process that ensures timely anther dehiscence in Arabidopsis. Our findings reveal that endothecium lignification can be divided into two distinct phases. During Phase I, lignin precursors are synthesized without polymerization, while Phase II involves simultaneous synthesis of lignin precursors and polymerization. The transcription factors MYB26, NST1/2, and ARF17 specifically regulate the pathway responsible for the synthesis and polymerization of lignin monomers in Phase II. MYB26‐NST1/2 is the key regulatory pathway responsible for endothecium lignification, while ARF17 facilitates this process by interacting with MYB26. Interestingly, our results demonstrate that the lignification of the endothecium, which occurs within approximately 26 h, is much faster than that of the vascular tissue. These findings provide valuable insights into the regulation mechanism of rapid lignification in the endothecium, which enables timely anther dehiscence and successful pollen release during plant reproduction. [ABSTRACT FROM AUTHOR]

Copyright of Cancer Medicine is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The distribution of Mg isotopes in minerals is becoming increasingly relevant in Earth science. Usually, they are determined by dissolving mineral concentrates and, after purifying Mg with ion exchange resins, analysing the resulting solutions by TIMS or, most often, MC‐ICP‐MS. When applied to individual minerals, these methods are slow and prone to contamination from impurities in the concentrates, inconveniences that may be avoided using spot analysis techniques such as LA‐MC‐ICP‐MS or SIMS, albeit at the price of a large instrumental mass fractionation (IMF) and isobaric interferences, most prominent in the former. Here, we studied the potential of the multi‐collector SHRIMP II ion microprobe for measuring Mg isotopes in Fe‐Mg silicates and oxides. We found that, when corrected for the divergence of the Mg ion paths within the sample chamber caused by the Earth's magnetic field, the SHRIMP's IMF overwhelmingly depends on the mineral species, and the effects of variable chemical composition are negligible. We propose that the IMF is caused by the force constant difference, ∆F, between "hard" and "soft" bonds linking the ions of the studied element to the mineral lattice. Given that ∆F is a constant for each mineral species, we calculated IMF‐correction factors for the most common Mg‐bearing minerals. The thus‐calculated correction factors permit the analysis in the same session, and with reasonable accuracy (within ~ 0.3‰ of the δ26Mg determined by SN‐MC‐ICP‐MS analyses of concentrates), of samples from different mineral species, facilitating the application of Mg isotopes to terrestrial studies. [ABSTRACT FROM AUTHOR]

Currently, the improvement in AI is mainly related to deep learning techniques that are employed for the classification, identification, and quantification of patterns in clinical images. The deep learning models show more remarkable performance than the traditional methods for medical image processing tasks, such as skin cancer, colorectal cancer, brain tumour, cardiac disease, Breast cancer (BrC), and a few more. The manual diagnosis of medical issues always requires an expert and is also expensive. Therefore, developing some computer diagnosis techniques based on deep learning is essential. Breast cancer is the most frequently diagnosed cancer in females with a rapidly growing percentage. It is estimated that patients with BrC will rise to 70% in the next 20 years. If diagnosed at a later stage, the survival rate of patients with BrC is shallow. Hence, early detection is essential, increasing the survival rate to 50%. A new framework for BrC classification is presented that utilises deep learning and feature optimization. The significant steps of the presented framework include (i) hybrid contrast enhancement of acquired images, (ii) data augmentation to facilitate better learning of the Convolutional Neural Network (CNN) model, (iii) a pre‐trained ResNet‐101 model is utilised and modified according to selected dataset classes, (iv) deep transfer learning based model training for feature extraction, (v) the fusion of features using the proposed highly corrected function‐controlled canonical correlation analysis approach, and (vi) optimal feature selection using the modified Satin Bowerbird Optimization controlled Newton Raphson algorithm that finally classified using 10 machine learning classifiers. The experiments of the proposed framework have been carried out using the most critical and publicly available dataset, such as CBIS‐DDSM, and obtained the best accuracy of 94.5% along with improved computation time. The comparison depicts that the presented method surpasses the current state‐of‐the‐art approaches. [ABSTRACT FROM AUTHOR]

Summary: Starch accounts for up to 90% of the dry weight of rice endosperm and is a key determinant of grain quality. Although starch biosynthesis enzymes have been comprehensively studied, transcriptional regulation of starch‐synthesis enzyme‐coding genes (SECGs) is largely unknown. In this study, we explored the role of a NAC transcription factor, OsNAC24, in regulating starch biosynthesis in rice. OsNAC24 is highly expressed in developing endosperm. The endosperm of osnac24 mutants is normal in appearance as is starch granule morphology, while total starch content, amylose content, chain length distribution of amylopectin and the physicochemical properties of the starch are changed. In addition, the expression of several SECGs was altered in osnac24 mutant plants. OsNAC24 is a transcriptional activator that targets the promoters of six SECGs; OsGBSSI, OsSBEI, OsAGPS2, OsSSI, OsSSIIIa and OsSSIVb. Since both the mRNA and protein abundances of OsGBSSI and OsSBEI were decreased in the mutants, OsNAC24 functions to regulate starch synthesis mainly through OsGBSSI and OsSBEI. Furthermore, OsNAC24 binds to the newly identified motifs TTGACAA, AGAAGA and ACAAGA as well as the core NAC‐binding motif CACG. Another NAC family member, OsNAP, interacts with OsNAC24 and coactivates target gene expression. Loss‐of‐function of OsNAP led to altered expression in all tested SECGs and reduced the starch content. These results demonstrate that the OsNAC24‐OsNAP complex plays key roles in fine‐tuning starch synthesis in rice endosperm and further suggest that manipulating the OsNAC24‐OsNAP complex regulatory network could be a potential strategy for breeding rice cultivars with improved cooking and eating quality. [ABSTRACT FROM AUTHOR]

Background and Aim: Severe colitis is a common side effect of chemotherapy in cancer patients. In this study, we attempted to enhance the viability of probiotics in a gastric acid environment and improve the colitis induced by dextran sulfate sodium (DSS) and docetaxel. Methods: We purified Lactobacillus from yogurt and estimated their growth at pH 6.8 and pH 2.0. In the further investigation, the bacterial biofilm formation was used to define the mechanism by which administration of Lactobacillus rhamnosus (LGG) via oral gavage alleviates the colitis and intestine permeability of the mice induced by DSS and docetaxel. The potential benefit of probiotics on the treatment of breast cancer metastasis has been assessed as well. Results: Lactobacillus from yogurt growth was unexpectedly faster in the pH 2.0 than in the neutral pH medium during the first hour. LGG administered in the fasting state via oral gavage significantly improved the preventive effect in the colitis caused by DSS and docetaxel. LGG reduced the permeability of the intestine and decreased the expression of proinflammatory cytokines, TNF‐α, IL‐1β, and IL‐6, in colitis by biofilm formation. Increasing the docetaxel dose may reduce breast tumor growth and metastasis in the lung but did not benefit survival due to severe colitis. However, the LGG supplement significantly improved the survival of tumor‐bearing mice following a high dose of docetaxel treatment. Conclusions: Our findings provide new insights into the potential mechanism of probiotic protection of the intestine and provide a novel therapeutic strategy to augment the chemotherapeutic treatment of tumors. [ABSTRACT FROM AUTHOR]

The behavior of nickel (Ni) isotopes during magmatic differentiation is not adequately explored. Here, we find that tholeiitic rocks in the Kīlauea Iki (KI) lava lake, Hawai'i, show progressively lighter Ni isotopic compositions with increasing magmatic differentiation, whereas calc‐alkaline rocks from the thick Kamchatka arc (30–45 km), located at the convergent boundary of the Eurasian and Pacific plates show increasing Ni isotope values as MgO and Ni decrease. Forty‐three global intermediate‐felsic continental igneous rocks analyzed in this study display large Ni isotopic variations, with the Eoarchean samples having light Ni isotopic compositions that fall in the trend defined by the KI lavas, and the post‐Eoarchean samples showing systematically heavier Ni isotopic compositions overlapping those of Kamchatka arc rocks. The isotopic dichotomy results from the crystallization of isotopically heavy magnetite during low‐pressure differentiation of KI lavas, whereas the participation of sulfide separation that removes isotopically light Ni during high‐pressure differentiation of magmas traversing thick continental crust. Combined with Rhyolite‐MELTS and sulfur concentration at sulfide saturation simulations, we demonstrate that the Ni isotope fractionation during magmatic differentiation is mainly controlled by the tempo of magnetite crystallization and sulfide formation, which is a function of pressure, oxygen fugacity, and water activity. High‐pressure calc‐alkaline differentiation usually suppresses magnetite crystallization while stabilizing sulfide, leading to heavy Ni isotopic compositions for the evolved magmas, significantly deviating from the low‐pressure fractionation trend seen in the KI lavas. Ni isotopes can be used in the future as a tracer of magmatic differentiation and processes of continent formation and differentiation. Plain Language Summary: Magmatic differentiation plays an important role in generating the distinctive calc‐alkaline compositions of the continental crust. We show that low‐pressure differentiation of the Kīlauea Iki tholeiitic lavas displays progressively lighter Ni isotopes with differentiation, whereas high‐pressure differentiation of calc‐alkaline volcanic rocks from the thick Kamchatka arc leads to heavier Ni isotopes. This difference may result from the fact that higher pressure may have suppressed magnetite crystallization while stabilized sulfide relative to low‐pressure differentiation. The degree and direction of Ni isotope fractionation during magmatic differentiation are mainly controlled by the differentiation pressure, oxygen fugacity, and water activity. Thus, Ni isotopes can be a novel tracer of magmatic differentiation and processes of continent formation and differentiation. Key Points: Nickel isotopic compositions of Kīlauea Iki lavas become lighter with increasing magmatic differentiationNickel isotopic compositions of Kamchatka arc lavas become heavier with increasing magmatic differentiationNickel isotope fractionation during magmatic differentiation is controlled by the tempo of magnetite crystallization and sulfide formation [ABSTRACT FROM AUTHOR]

Electron cyclotron harmonic (ECH) waves are one of the most common plasma waves in the Earth's magnetosphere, and they are considered to be excited by the electron loss‐cone distributions near the magnetic equator. Using the Magnetospheric Multiscale data, we report an unusual event of ECH waves at L = ∼12.4 and MLT = ∼16.0 hr, where the ECH waves are locally excited inside non‐propagating magnetic oscillations, that is, mirror mode structures. The observation reveals that the mirror mode structures are generated by anisotropic ions (Ti⊥/Ti∥ ${T}_{i\perp }/{T}_{i{\Vert} }$ ∼ 1.3 – 1.7), and electron mirror loss‐cone distributions are formed due to the magnetic configuration of the mirror mode structures. Combing with the linear instability analysis, we confirm that the ECH waves are locally excited by the electron mirror loss‐cone distributions inside the mirror mode structures. Therefore, we propose that the mirror mode structures provide another potential source region for ECH waves in the Earth's magnetosphere. Plain Language Summary: Electron cyclotron harmonic (ECH) waves are widely observed in the Earth's magnetosphere, which are important for the diffusion auroral precipitation. Previous studies have shown that the main source region of ECH waves in the magnetosphere is near the magnetic equator, and the electron loss‐cone distribution provides the free energy to excite ECH waves. In this study, we reveal that there also exists another potential source region of ECH waves, that is, mirror mode structures. Using the Magnetospheric Multiscale data, we report an unusual event of ECH waves inside the mirror mode structures in the Earth's outer magnetosphere. By analyzing the plasma conditions, we show that the mirror mode structures are generated by anisotropic ions, and electron mirror loss‐cone distributions are formed due to the magnetic configuration of the mirror mode structures. Based on the linear instability analysis, we demonstrate that the ECH waves are excited by the electron mirror loss‐cone distributions within the mirror mode structures. These results provide new insights into the generation of ECH waves in the Earth's magnetosphere. Key Points: Using the Magnetospheric Multiscale data, we report the first observation of electron cyclotron harmonic (ECH) waves within mirror mode structures in the Earth's outer magnetosphereThe mirror mode structures observed as quasi‐periodic magnetic oscillations are excited by anisotropic ionsThe simultaneously detected ECH waves are excited by the electron mirror loss‐cone distributions inside the mirror mode structures [ABSTRACT FROM AUTHOR]

Summary: High quality medical images are expected for the detailed analysis in medical diagnostic system. However, spatial resolution of medical images mostly suffers from the factors such as medical equipment and time constraints. Despite these limitations, a well‐designed super‐resolution (SR) algorithm will help to improve the resolution of the medical images for medical diagnosis. When comparing to upgrade medical equipment, the adaptation of SR algorithms as a post‐processing method after medical imaging gives the benefits of lower cost and superior performance. This article proposes a piecewise linear regression system for learning image specific low‐to‐high resolution mapping via domain transform filtering and weighted least squares (WLS) optimization framework. We initially employed a WLS optimization framework for gradually coarsen the original input images and extract the multi‐scale information by constructing edge‐preserving multi‐scale decompositions. Then, with the aim of adequately preserving the edges of the medical images, we utilize a recursive filtering in transform domain. The Hadamard patterns generated from low‐resolution training patches are then used to classify the LR–HR training patch pairs into different classes. In the end, the piecewise linear regression system is utilized to learn the mapping relationship between LR space to HR space for each class, which is subsequently utilized to obtain desired HR image. In the context of quantitative metrices and qualitative analysis, our proposed method generates high‐quality medical images as compares to other existing state‐of‐the‐art SR methods. [ABSTRACT FROM AUTHOR]

Global basaltic rocks show large variations in nickel (Ni) isotopic compositions relative to peridotites. The origin of this difference remains unknown. We analyzed Ni isotopic compositions of mineral separates from seven Beiyan peridotite xenoliths and 16 nephelinites from eastern China. Spinel is isotopically heavier, and clinopyroxene is systemically lighter than coexisting olivine and orthopyroxene. An ionic model predicts that olivine, orthopyroxene, and spinel are in Ni isotopic equilibrium, whereas clinopyroxene of metasomatic origin is out of equilibrium. The nephelinites have higher Fe3+/ΣFe but lower δ60/58Ni values than the peridotites. Mantle silicate melting likely leads to enrichment of heavy Ni isotopes in melts, and, importantly, it cannot explain the negative correlation between δ60/58Ni and Fe3+/ΣFe of the nephelinites. Therefore, the light Ni isotopic signature requires the involvement of a low‐δ60/58Ni component. Sulfide is a minor Ni‐rich component in the mantle and is isotopically lighter than the silicates. The relative proportion of Ni from sulfides vs. that from silicates varies in mantle‐derived magmas, depending on the sulfur content at sulfide saturation and melting degree. Thus, low‐degree melts with high abundance of dissolved sulfides can be variably enriched in light Ni isotopes. We propose that enhanced sulfide dissolution at high oxygen fugacity is a key reason for light Ni isotopic compositions in the nephelinites. This sulfide dissolution model may also be responsible for producing the Ni isotopic variation in global mafic lithologies. When the highly oxidized, low‐degree melts react with the peridotitic region, they can impart light Ni isotopic signatures to mantle rocks. Plain Language Summary: There is scant information on why global basaltic rocks show large Ni isotopic variations relative to peridotites. We present Ni isotopic data for mineral separates from peridotite xenoliths as well as nephelinites from eastern China. The olivine, orthopyroxene, and spinel are in Ni isotopic equilibrium, whereas clinopyroxene of metasomatic origin is out of equilibrium. Compared to the normal mantle value, the nephelinites have lower Ni isotope values, which are negatively correlated with Fe3+/ΣFe. This signature cannot be produced by mantle silicate melting. Instead, the data suggest enhanced dissolution of isotopically light sulfide into the mantle melts at high oxygen fugacity. Recycling of carbonate sediments can induce incipient mantle melting and increase the oxygen fugacity. The oxidized, low‐degree melts, as represented by the nephelinites, have higher sulfur content at sulfide saturation, leading to a higher proportion of sulfide‐derived Ni in the melts, and thus lighter Ni isotopic compositions. When such melts react with the peridotitic region, they can impart light Ni isotopic signatures to mantle rocks, and potentially lead to the newly formed minerals being out of Ni isotopic equilibrium with primary ones. This sulfide dissolution model may also be responsible for producing the Ni isotopic variation in global mafic lithologies. Key Points: The clinopyroxene is enriched in lighter Ni isotopes, and is out of equilibrium with other silicate minerals due to metasomatic originThe nephelinites have lower δ60/58Ni values, because enhanced sulfide dissolution at high fo2 introduces light Ni isotopes to the meltsSulfide dissolution is an important step in producing the Ni isotopic variations observed in global mafic rocks [ABSTRACT FROM AUTHOR]

Minimally invasive thermal therapies have been attempted in the treatment of breast cancer, and the immune response induced by these therapies has not been fully reported. A clinical trial is performed to determine the effect of microwave ablation (MWA) in the treatment of early‐stage breast cancer. The authors perform single‐cell RNA sequencing on peripheral blood mononuclear cells (PBMCs) from six patients before and after ablation. NK and CD8+T cells are activated by MWA of breast cancer, with the increased inhibitory signature of CD8+T cells but not dysfunctional. Enhanced co‐stimulatory signature of CD4+ T cells is observed and increased frequency of ICOS+CD4+ T cells after MWA is confirmed by flow cytometric analysis. After ablation, T‐cell clones expand with increased T‐cell receptor diversities. Activated antigen receptor‐mediated signaling pathways are found in B cells. Enhanced interactions between B cells and CD4+ T cells are found, indicating that B cells are important antigen‐presenting cells that initiate CD4+T cells in MWA‐induced immune response. Blockade of CTLA‐4 or PD‐1 of post‐MWA PBMCs show higher T‐cell activity than that of pre‐MWA PBMCs. This study provide global characteristics of MWA‐induced systemic immune response and pave a way for the identification of potential targets to improve the immune response. [ABSTRACT FROM AUTHOR]

The visual inspection of histopathological samples is the benchmark for detecting breast cancer, but a strenuous and complicated process takes a long time of the pathologist practice. Deep learning models have shown excellent outcomes in clinical diagnosis and image processing and advances in various fields, including drug development, frequency simulation, and optimization techniques. However, the resemblance of histopathologic images of breast cancer and the inclusion of stable and infected tissues in different areas make detecting and classifying tumors on entire slide images more difficult. In breast cancer, a correct diagnosis is needed for complete care in a limited amount of time. An effective detection can relieve the pathologist's workload and mitigate diagnostic subjectivity. Therefore, this research work investigates improved the pre‐trained xception and deeplabv3+ design semantic model. The model has been trained on input images with ground masks on the tuned parameters that significantly improve the segmentation of ultrasound breast images into respective classes, that is, benign/malignant. The segmentation model delivered an accuracy of greater than 99% to prove the model's effectiveness. The segmented images and histopathological breast images are transferred to the 4‐qubit‐quantum circuit with six‐layered architecture to detect breast malignancy. The proposed framework achieved remarkable performance as contrasted to currently published methodologies. Highlights: This research proposed hybrid semantic model using pre‐trained xception and deeplabv3 for breast microscopic cancer classification in to benign and malignant classes at accuracy of 95% accuracy, 99% accuracy for detection of breast malignancy. [ABSTRACT FROM AUTHOR]

In this paper, by performing two‐dimensional (2‐D) particle‐in‐cell simulations of collisionless magnetic reconnection in a Harris current sheet, we analyze the formation of electron inflow along the separatrices toward the X‐line from the perspective of fluid. The results show that both the parallel electric field and mirror force can drive the electron inflow to stream toward the X‐line. The speed of the electron inflow can reach about 4VA(where VA is the Alfvén speed based on the upstream asymptotic magnetic field magnitude and peak density in the current sheet). Although the contribution of the parallel electric field is much larger than that of the mirror force, the mirror force cannot be ignored. When the electron inflow streams toward the X‐line, it is heated in the parallel direction. The resulted gradient of the parallel electron pressure leads to the attenuation of the electron inflow. We also investigate the effects of the density and temperature of the background plasma on the formation of the electron inflow. With the decrease of the background plasma density, the contribution of the parallel electric field becomes larger while that of the mirror force almost remains unchanged. With the decrease of the background plasma temperature, the contribution of the parallel electric field becomes larger while that of the mirror force becomes smaller. Plain Language Summary: Magnetic reconnection is a universal process in which the topology of the magnetic field changes, accompanied by plasma heating and particle acceleration. During reconnection, electrons moving along the separatrices toward the X‐line form the electron inflow. The electron inflow has been confirmed in simulations and observations, but its generation mechanism remains unclear. This paper focuses on the dynamics of inflow electrons along the separatrices during magnetic reconnection, and quantitatively analyzes the formation of electron inflow. We found that the formation of electron inflow is contributed by three effects: accelerated by the parallel electric field, accelerated by the magnetic mirror force, and decelerated by the gradient of parallel electron pressure. The acceleration contribution of the parallel electric field is dominant, but that of mirror force cannot be ignored, especially when the background plasma density and temperature are sufficiently high. Key Points: Electron inflow is accelerated by parallel electric field and mirror force and decelerated by the gradient of parallel electron pressureParallel electric field plays a major role in the formation of electron inflow, while the contribution of mirror force cannot be ignoredThe contributions of parallel electric field and mirror force change with the background plasma density and temperature [ABSTRACT FROM AUTHOR]

The power gap around 0.5Ωe (where Ωe is the equatorial electron gyrofrequency) of whistler‐mode waves is commonly observed in the Earth's inner magnetosphere, but its generation mechanism is still under debate. By performing two‐dimensional particle‐in‐cell simulations in a uniform background magnetic field, we investigate the spectral properties of whistler‐mode waves excited by temperature anisotropic electrons. The waves have positive growth rates in a wide range of normal angles (θ ≈ 0°–35°), resulting in the generation of both parallel and nonparallel waves. Although the nonparallel wave modes are weaker than the parallel ones, they can cause the plateau‐like shape around 0.5 VAe (where VAe represent the electron Alfven speed) in the parallel direction of electron velocity distribution. The plateau‐like electron component can then lead to severe damping in the waves around 0.5Ωe via the cyclotron resonance, and the power gap is formed. This mechanism is called as "spectrum bite". Our study sheds fresh light on the well‐known gap formation at ∼0.5Ωe in the whistler‐mode waves, which is ubiquitously detected near the equator in the inner magnetosphere. Key Points: The whistler‐mode waves with power gaps around 0.5Ωe in the Earth's magnetosphere are investigated by 2‐D PIC simulationsThe power gap is formed due to the severe damping by the plateau‐like electron component in the parallel velocity distribution at ∼0.5VAeThe plateau‐like distribution in the parallel direction is caused by the nonparallel wave modes through Landau resonance [ABSTRACT FROM AUTHOR]

Solar wind‐magnetosphere coupling is a key link of the space weather chain. There have been increasing reports of solar wind dynamic pressure pulses influencing the whistler‐mode chorus wave growth in the inner magnetosphere, but the response conditions and mechanisms of chorus growth remain under debate. Here we present a statistical study of the immediate impact of solar wind dynamic pressure pulses on inner magnetospheric chorus waves using Van Allen Probes data from 2012 to 2019. A stronger pulse is found to have a greater likelihood to change the chorus amplitude particularly on the dayside. Positive pulses can significantly enhance chorus amplitudes, while negative ones result in a weakening in chorus amplitudes. As supported by direct observations, these pulses alter the linear growth of waves by modifying energetic electron distributions; in contrast, geomagnetic field modeling indicates no significant changes in the geomagnetic field inhomogeneity controlling the nonlinear growth threshold of waves. Plain Language Summary: The geospace environment is highly controlled by the solar wind. In the inner magnetosphere, the whistler‐mode chorus waves, contributing significantly to the radiation belt electron acceleration and the auroral electron precipitation, have been increasingly reported to respond to the solar wind dynamic pressure pulses upstream of the Earth. However, how positive and negative solar wind dynamic pulses affect the inner magnetospheric chorus waves remains under debate. By statistically analyzing and modeling Van Allen Probes data, we show that solar wind dynamic pressure pulses mainly alter the linear growth of waves by modifying energetic electron distributions, with stronger pulses leading to a greater likelihood of causing observable enhancement or weakening in wave amplitudes. The present study contributes to our understanding of the evolution of chorus waves and the chorus‐driven particle dynamics in the inner magnetosphere. Key Points: A stronger solar wind pressure pulse has a greater likelihood to change the magnetospheric chorus amplitude particularly on the daysidePositive (negative) pressure pules can immediately increase (decrease) chorus amplitudes in the inner magnetosphereThese pulses mainly alter the linear growth of chorus waves by modifying the source electron distributions in the inner magnetosphere [ABSTRACT FROM AUTHOR]

Photoperiod/temperature‐sensitive genic male sterility (P/TGMS) is widely applied for improving crop production. Previous investigations using the reversible male sterile (rvms) mutant showed that slow development is a general mechanism for restoring fertility to P/TGMS lines in Arabidopsis. In this work, we isolated a restorer of rvms–2 (res3), as the male sterility of rvms–2 was rescued by res3. Phenotype analysis and molecular cloning show that a point mutation in UPEX1 l in res3 leads to delayed secretion of callase A6 from the tapetum to the locule and tetrad callose wall degradation. Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis demonstrated that the tapetal transcription factor ABORTED MICROSPORES directly regulates UPEX1 expression, revealing a pathway for tapetum secretory function. Early degradation of the callose wall in the transgenic line eliminated the fertility restoration effect of res3. The fertility of multiple known P/TGMS lines with pollen wall defects was also restored by res3. We propose that the remnant callose wall may broadly compensate for the pollen wall defects of P/TGMS lines by providing protection for pollen formation. A cellular mechanism is proposed to explain how slow development restores the fertility of P/TGMS lines in Arabidopsis. [ABSTRACT FROM AUTHOR]

Aim: Fruit category classification is important in factory packing and transportation, price prediction, dietary intake, and so forth. Methods: This study proposed a novel artificial intelligence system to classify fruit categories. First, 2D fractional Fourier entropy with rotation angle vector grid was used to extract features from fruit images. Afterwards, a five‐layer stacked sparse autoencoder was used as the classifier. Results: Ten runs on the test set showed our method achieved a micro‐averaged F1 score of 95.08% for an 18‐category fruit dataset. Conclusion: Our method gives better micro‐averaged F1 score than 10 state‐of‐the‐art approaches. [ABSTRACT FROM AUTHOR]

Whistler‐mode waves can modulate the electron distributions through wave‐particle interactions in the Earth's inner magnetosphere. In this paper, we have investigated the effects of the whistler waves on the electron distributions by a combination of electron magnetohydrodynamics and test‐particle simulations. Our simulations show a parallel whistler wave becomes gradually oblique during its propagation from the magnetic equator to higher latitudes. Such a whistler wave causes distinct flux increases of tens of keV electrons at large pitch angles to form electron butterfly distributions. This whistler wave traps numerous resonant electrons and transports them from lower latitudes to higher latitudes through nonlinear Landau trapping. Meanwhile, these trapped electrons are efficiently accelerated to higher energies contributing to the rapid formation of electron butterfly distributions at higher latitudes. Our study suggests nonlinear Landau trapping is a potential formation mechanism of the electron butterfly distributions observed in the Earth's inner magnetosphere. Plain Language Summary: Wave‐particle interactions are known to play an important role in regulating energetic electron distributions in the Earth's inner magnetosphere. In particular, whistler‐mode waves can efficiently modulate the electron distributions by cyclotron and Landau resonant interactions. In this paper, we used a 2‐D electron magnetohydrodynamics model to simulate a whistler wave in the dipole geomagnetic field. The simulation results indicate a parallel whistler wave becomes gradually oblique during its propagation from the magnetic equator to high latitudes. Furthermore, a test‐particle simulation shows that such a whistler wave can trap and accelerate electrons from the lower latitudes to higher latitudes by nonlinear Landau trapping, which leads to the rapid formation of electron butterfly distributions at tens of keV. Previous studies suggested that nonlinear cyclotron trapping can cause electron butterfly distributions at tens of keV observed in the Earth's magnetosphere. Our study provides a new potential formation mechanism of electron butterfly distributions in the Earth's magnetosphere. Key Points: Effects of whistler waves on electron distributions have been studied by a combination of electron magnetohydrodynamics and test‐particle simulationsA whistler wave causes distinct flux enhancements of 10s keV electrons at large pitch angles to form electron butterfly distributionsNonlinear Landau trapping contributes to the rapid formation of the electron butterfly distributions [ABSTRACT FROM AUTHOR]

In this study, we report observations from the Magnetospheric Multiscale (MMS) mission of large‐scale parallel electric fields in a magnetosheath reconnecting current sheet. The four MMS satellites successively crossed an electron jet embedded in a broad current sheet and detected a unipolar E|| being colocated with the jet. The strong electron pressure anisotropy inside the broad current sheet suggests that the jet could be generated by the firehose instability. The observations show that the large‐amplitude E|| can fill the entire electron diffusion region (EDR) in the magnetosheath reconnection and thus dominates electron acceleration therein, dramatically different from EDRs in the magnetotail and magnetopause where large‐amplitude unipolar E|| was rarely detected. The appearance of this E|| could be due to the strong guide field which is common in the magnetosheath. Plain Language Summary: Magnetic reconnection is a fundamental physical process in space and astrophysical plasmas in which magnetic energy is converted into plasma kinetic energy and heat. Magnetic reconnection is believed to be initiated in a small‐scale electron diffusion region (EDR) where electrons are decoupled from the magnetic field lines. Recent spacecraft observations in Earth's magnetosheath have revealed a new form of magnetic reconnection without ion coupling in electron‐scale current sheets. The detailed properties of the EDR in these electron‐only reconnection events have been scarce. In this letter, we report Magnetospheric Multiscale mission observations of large‐amplitude and unipolar parallel electric fields being colocated with the EDR of a magnetosheath reconnecting current sheet. The parallel electric field has a large spatial extent that fills the entire EDR. This parallel electric field generates a potential drop of 120 V, which can accelerate electrons passing through the EDR. Altogether, our results suggest that large‐scale parallel electric fields can dominate the electron dynamics in the EDR of magnetosheath electron‐only reconnection events that usually have large guide fields. Key Points: A strong electron jet was detected in a broad current sheet with a significant pressure anisotropyThe electron jet was identified as an extended electron diffusion region and large‐scale parallel electric field was observed inside itParallel electric field generates a potential of 120 V and dominates electron acceleration therein [ABSTRACT FROM AUTHOR]

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

When the interplanetary magnetic field (IMF) is northward, magnetic reconnection between the IMF and the geomagnetic field can occur at the high latitude magnetopause, which allows energy transfer from the solar wind into Earth's magnetosphere. In this letter, by using three‐dimensional global hybrid simulations, we find that during the northward IMF, high latitude magnetic reconnection both poleward and equatorward of the cusp can occur almost simultaneously. High latitude magnetopause flux ropes (HLMFRs) with four topologies of magnetic field lines can be formed by multiple X‐line reconnection. At the center of the HLMFRs, there is a decrease in the surrounding magnetic field magnitude (weak core field) and an increase in parallel temperature. When the IMF is purely northward, the HLMFRs are located at the noon‐midnight meridian plane. When the IMF has a positive By component, the HLMFRs in the northern hemisphere shift duskward. Plain Language Summary: When the interplanetary magnetic field (IMF) is southward, magnetic reconnection between the IMF and the Earth's magnetic field can occur at the low latitude magnetopause, and flux ropes are formed. However, when the IMF is northward, the reconnection site is at high latitude magnetopause. In many previous studies, the high latitude magnetopause reconnection with the northward IMF was considered as no flux rope is formed. In this letter, we use computer simulations to investigate the high latitude magnetopause reconnection during the northward IMF in different directions. When the IMF is northward, the high latitude magnetopause flux ropes (HLMFRs) with four types of magnetic field lines are formed. At the center of the HLMFRs, there is a decrease in the surrounding magnetic field magnitude, an increase in parallel temperature. Compared with the flux ropes formed during the southward IMF, the HLMFRs are fewer and smaller. When the IMF is purely northward, the HLMFRs are located at the noon‐midnight meridian plane; when the IMF rotates to the duskward (but still northward), the HLMFRs in the northern hemisphere shift duskward. Key Points: High latitude magnetopause reconnection with different northward IMF clock angles is studied by using 3‐D global hybrid simulationsHigh latitude magnetopause flux ropes (HLMFRs) with four topologies of magnetic field lines are formed by multiple X‐line reconnectionIMF clock angle effects where the HLMFRs occurs and the direction of the HLMFRs' axis [ABSTRACT FROM AUTHOR]

The beam‐like electron population is often observed along with whistler mode waves in the Earth's magnetosphere, but its generation mechanism is still under debate. In this study, we use a test particle simulation model to study the Landau resonance between whistler mode waves and electrons, and quantify the proportion nb/nh of beam‐like electrons. There is a trend that the nb/nh first increases and then decreases with the increasing temperature of hot electrons or ratio of plasma frequency to electron gyrofrequency. While the nb/nh is positively correlated with the parallel electric field, magnetic amplitude, wave normal angle, or frequency of whistler mode waves if other parameters are fixed. Essentially the parallel electric field is the key parameter in determining nb/nh. Furthermore, we have also compared simulation results with THEMIS observations for one year. The results suggest the observed beam‐like population could be generated by simultaneously observed whistler mode waves for 44.5% quasi‐parallel cases. But the beam‐like population is unlikely to be generated by simultaneously observed waves for the remaining 55.5% of quasi‐parallel cases and nearly all oblique cases. Our study provides a better understanding of the formation of beam‐like electron distribution in the Earth's magnetosphere. Key Points: With a test particle model, we have quantified the proportion of beam‐like electrons caused by Landau resonance with whistler wavesThe dependences of nb/nh on plasma conditions and wave parameters are also studied, and E∥ plays a dominant roleCompared with observations, the detected beam‐like population can be driven by some quasi‐parallel waves but is unlikely for oblique waves [ABSTRACT FROM AUTHOR]

A two‐dimensional particle‐in‐cell (PIC) simulation is performed to study the formation of the pitch angle distribution of energetic electrons at dipolarization fronts (DFs) driven by magnetic reconnection. The energetic electrons at DFs are originated from the lobe region, and experience a two‐step acceleration process at the reconnection x‐line and the DFs, respectively. Three kinds of pitch angle distributions commonly observed in the magnetotail, Pancake, Rolling pin, and Cigar distributions, are formed in sequence during the propagation of the DFs. In the early stage, Pancake distributions are formed through betatron acceleration. During this stage, the flux of energetic electrons with pitch angles around 0° and 180° is low because these electrons have no time to be reflected many times at the DFs to obtain sufficient Fermi acceleration. However, the electrons with pitch angles around 90° are difficult to be trapped around the DFs for a long time, and their flux saturates quickly; while the electrons with pitch angles around 0° and 180° can be trapped inside the closed field lines and they get continuous Fermi acceleration during the propagation of the DFs. Therefore, in the later stage, the flux of energetic electrons with pitch angles around 0° and 180° gradually increases and at last exceeds that of energetic electrons with pitch angles around 90°, forming Rolling pin and Cigar distributions in sequence. Plain Language Summary: Energetic electrons in the magnetotail usually show anisotropic pitch angle distributions, such as Pancake, Cigar, and Rolling‐pin distributions. All of the three kinds of pitch angle distributions are frequently observed to be related to dipolarization fronts. Pancake distribution is characterized by the enhancement of energetic electron flux with pitch angles around 90°; Cigar distribution is characterized by the enhancement of energetic electron flux with pitch angles around 0° and 180°; Rolling‐pin distribution is characterized by the enhancement of energetic electron flux with pitch angles around 0°, 90°, and 180°. It has been long accepted that electrons with pitch angles around 90° are generated by betatron acceleration, and electrons with pitch angles around 0° and 180° are generated by Fermi acceleration. However, the differences in the conditions to form the three kinds of distributions are far less understood. In this paper, we study when and where these distributions can be formed, and the detailed acceleration processes that lead the energetic electrons to form these distributions. Key Points: The energetic electrons at the dipolarization fronts (DFs) experience a two‐step acceleration process at the reconnection x‐line and DFsPancake, Rolling pin, and Cigar distributions are formed in sequence during the propagation of the DFsThese distributions are resulted from the different time scales of betatron and Fermi mechanisms at the DFs [ABSTRACT FROM AUTHOR]

Collisionless magnetic reconnection occurs ubiquitously in space plasma environments and plays an important role in energy conversion therein. In collisionless magnetic reconnection, the reconnection site is usually unsteady and ejects reconnection fronts away from it. Using two‐dimensional particle‐in‐cell simulations, we study the energy budgets from the collisionless magnetic reconnection site to reconnection fronts. It is concluded that the reconnection rate cannot well reflect energy conversion of nonsteady state magnetic reconnection because energy conversion occurs predominantly at the reconnection fronts, whereas the reconnection rate can only represent the energy conversion at the reconnection site. We clarify the connection between the reconnection site and the reconnection fronts in terms of energy conversion. The reconnection site functions as a trigger and energy source that generates the outflow of Poynting flux, bulk kinetic energy flux, and enthalpy flux forming the reconnection fronts that move downstream. The well‐developed reconnection fronts are no longer related to the reconnection site. The energy income at the reconnection fronts is mainly the Poynting flux from their top and bottom boundaries, most of which is transformed to P¯⋅V flux flowing downstream out of the moving front through the work by the electric field. The work done by the electric force is compensated with the work done by the thermal pressure gradient, which guarantees that the released magnetic energy is mostly converted to thermal energy. Key Points: Energy budgets from collisionless magnetic reconnection site to reconnection fronts are studied through two‐dimensional particle‐in‐cell simulationsThe reconnection fronts that dominate the energy conversion are generated from the reconnection siteEnergy conversion at the well‐developed reconnection front is unrelated to the reconnection site. The Poynting flux inflow is mainly converted to enthalpy flux [ABSTRACT FROM AUTHOR]

A variety of plasma waves have been observed in the separatrix region during magnetic reconnection, and their roles on reconnection and exciting mechanisms are still controversial. In this paper, we report the whistler wave with a very narrow frequency band just above half of the electron cyclotron frequency in the separatrix region. This whistler wave is accompanied with the electron cyclotron harmonic (ECH) waves. The ECH waves have frequencies between the first and fifth harmonic of electron cyclotron frequency fce. The wave normal angle of the whistler waves is ∼20°–∼40°, meaning the quasi‐parallel propagation, while the ECH waves propagate perpendicular to the background magnetic field with θ∼87°±2°. In the separatrix region, the electrons have a loss‐cone distribution while these two kinds of waves are observed. Based on the linear theory, such an electron distribution is unstable for both whistler waves and ECH waves. It indicates that these two kinds of waves are generated by the electron loss‐cone instability. Key Points: A very narrow band whistler wave and electron cyclotron harmonic waves are simultaneously observed in the magnetosphere separatrix regionThe electron loss‐cone distributions are continuously detected while the two kinds of waves are observedThe two kinds of waves are probably excited by the electron loss‐cone instability [ABSTRACT FROM AUTHOR]

Chorus waves in the inner magnetospheres of the Earth and other magnetized planets typically occur in the form of discrete and repetitive quasi‐monochromatic emissions with a frequency chirping, which was discovered more than 50 years ago. However, until now there is still no satisfactory explanations for repetitive emissions of chorus waves. In this Letter, chorus emissions excited by energetic electrons with a temperature anisotropy are studied by a one‐dimensional PIC‐δf simulation in a dipole magnetic field, and it is demonstrated that a continuous injection of energetic electrons caused by an azimuthal drift is essential for the repetitive emissions of chorus waves. Consistent with satellite observations, both discrete and continuous spectra can be reproduced. An intense injection of energetic electrons will lead to a decrease of the time separation between the chorus elements, and the chorus emissions evolve from a discrete to a continuous spectrum when the injection is sufficiently strong. Plain Language Summary: Chorus waves are electromagnetic emissions that are commonly observed in the Earth's inner magnetosphere, and they typically occur in the form of discrete and repetitive quasi‐monochromatic emissions with a rising frequency chirping. The rising frequency chirping of chorus waves are considered to be related with electromagnetic electron holes in the wave phase space formed after resonant electrons have been trapped by whistler‐mode waves. However, until now there is still no satisfactory explanations for repetitive emissions of chorus waves. We develop a one‐dimensional PIC‐δf simulation model to study the excitation of chorus waves by energetic electrons with a temperature anisotropy in a dipole magnetic field, and a continuous injection of energetic electrons is embedded in the model. The repetitive emissions of chorus waves with a rising frequency chirping are generated in the simulations, and it is demonstrated clearly that the continuous injection of energetic electrons caused by an azimuthal drift is the reason for the repetitive emissions of chorus waves. It is further found that an intense injection of energetic electrons will lead to a decrease of the time separation between the chorus elements, and a continuous spectrum is formed when the injection is sufficiently strong. Key Points: We develop a 1D PIC‐δf simulation model embedding a continuous injection of energetic electrons in a dipole magnetic fieldIt is demonstrated that a continuous injection of energetic electrons is essential for the repetitive emissions of chorus wavesAn intense injection of energetic electrons will lead to a decrease of the time separation between the chorus elements [ABSTRACT FROM AUTHOR]

Electrostatic solitary waves (ESWs) are ubiquitously observed in magnetic reconnection. In this study, two‐dimensional (2‐D) particle‐in‐cell (PIC) simulations are performed to investigate the characteristics of ESWs in asymmetric magnetic reconnection. ESWs with bipolar structures of the parallel electric field can be generated near the separatrices only on the magnetosphere side, and propagate to reconnection downstream direction along the magnetic field. These structures corresponding to electron phase‐space holes (electron holes) can cross both the electron outflow and inflow channels although their main part is located in the electron outflow. When there is no guide field, the ESWs are generated by electron two‐stream instability. When there is a guide field, the amplitude of the ESWs are different on the right and left side of the X line. On the left side, the ESWs are weaker and generated by the electron two‐stream instability. On the right side, the ESWs are stronger, and there are two kinds of ESWs with distinct phase speed. The faster one is generated by electron two‐stream instability, while the slower one is generated by Buneman instability. Key Points: ESWs corresponding to electron holes appear near the separatrices only on the magnetosphere side during asymmetric reconnectionWhen there is no guide field, ESWs are generated by electron two‐stream instabilityWhen there is a guide field, ESWs with distinct phase speed are generated by electron two‐stream instability and Buneman instability [ABSTRACT FROM AUTHOR]

Whistler‐mode waves are electromagnetic waves pervasively observed in the Earth's and other planetary magnetospheres. They are considered to be mainly responsible for producing the hazardous radiation and diffuse aurora, which heavily relies on their properties. Density irregularities, frequently observed in the Earth's magnetospheres, are found to change largely the properties of whistler‐mode waves. Here we report, using Van Allen Probes measurements, whistler‐mode waves strongly modulated by two different density enhancements. With particle‐in‐cell simulations, we propose wave trapping caused by field‐aligned density irregularities (ducts) may account for this phenomenon. Simulation results show that whistler‐mode waves can be trapped inside the enhanced density ducts. These trapped waves remain quasi‐parallel and usually get much larger amplitudes than those unducted whistler waves during propagation away from the magnetic equator, and tend to focus at a spatially narrow channel, consistent with observations. Our results imply density irregularities may be significant to modulate radiation‐belt electrons. Key Points: Particle‐in‐cell (PIC) simulations demonstrate whistler‐mode waves can be trapped inside the enhanced density ducts which can interpret satellite observationsThese trapped waves remain quasi‐parallel and get much larger amplitudes during propagation toward high latitudesThese trapped waves focus at a spatially narrow channel inside the enhanced density ducts [ABSTRACT FROM AUTHOR]

Inner magnetospheric magnetosonic waves are usually considered to grow from the near‐equatorial ion Bernstein instability below the lower hybrid resonance frequency and contribute significantly to the radiation belt electron dynamics. We here present unusual observations of magnetosonic waves extending above the local lower hybrid resonance frequency in the midlatitude ∼15° plasmasphere after the substorm proton injection. Linear instability analyses and ray‐tracing simulations show that, because of the latitudinal variation of normal angles, these waves have little growth near the equator but are amplified accumulatively to the observable level over broad latitudes |λ| < 30° during the bounce‐drift propagation. Our data and modeling illustrate a previously unexplored scenario that off‐equatorial proton ring distributions could be a significant source of magnetosonic waves in the inner magnetosphere. Such off‐equatorially generated magnetosonic waves might differ from the near‐equatorially generated ones in latitudinal coverage, wavevector distribution, and then effect on the radiation belt electrons. Plain Language Summary: Magnetosonic waves refer to the nearly linearly polarized, compressional, electromagnetic emissions in the inner magnetosphere. They have recently received an increased interest for their contributions to the Van Allen radiation belt electron dynamics. A fundamental question has been where and how the magnetosonic waves are generated. In contrast to the traditional view that magnetosonic waves grow from ion Bernstein instability near the magnetic equator, we here propose the possibility of off‐equatorial sources for magnetosonic waves on the basis of the analysis of the unusual magnetosonic waves extending above the local lower hybrid resonance frequency in the midlatitude plasmasphere. Our modeling shows that these waves have little growth near the equator but are amplified accumulatively to the observable level by substorm‐injected protons over latitudes |λ| < 30° during the bounce‐drift propagation. Because of the differences in latitudinal coverage and wavevector distribution, the off‐equatorially and near‐equatorially generated magnetosonic waves are expected to have different effects on the radiation belt electrons. Key Points: Magnetosonic waves can extend above the lower hybrid resonance frequency in the off‐equatorial high‐density plasmasphereThe near‐equatorial instabilities of hot protons are difficult to explain the observed frequency extension of magnetosonic wavesThe unusual magnetosonic waves are more likely to grow accumulatively over latitudes |λ| < 30° during the bounce‐drift propagation [ABSTRACT FROM AUTHOR]

We present observational support for whistler mode waves guidance by the plasmapause gradients based on a case study and statistical analyses. Due to the combined effects of inhomogeneous magnetic fields and plasma densities, whistler mode waves near the inner edge of plasmapause (plasmasphere side) will be guided by a high density duct‐like (HDD) gradient, and tend to have very small wave normal angles (WNAs ≤ 20°) relative to the ambient magnetic field,B0. In contrast, whistler mode waves near the outer edge of the plasmapause (plasmatrough side) guided by a low density duct‐like (LDD) gradient, tend to have quite large WNAs (≥∼60°). Statistical analyses emphasize these remarkably different properties of waves in the plasmapause gradients. The results indicate that the wave ducting effects at the plasmapause may lead to unusual and anomalous energetic pitch angle scattering. Plain Language Summary: The plasmapause is a naturally formed transition region with a sharp gradient in density, dividing the Earth's magnetosphere into two physically distinct plasma regions: a dense inner region (i.e., plasmasphere) and a tenuous outer region (i.e., plasma trough). Whistler mode waves guidance by the inner and outer edges of plasmapause have been predicted by ray tracing studies and electron magnetohydrodynamics simulations. However, to date no direct observational evidence has been reported due to the lack of simultaneous measurements of waves and detailed plasma densities with sufficiently high resolution and reliability. We use Van Allen Probes (RBSP) orbiting satellite data to present in situ observations of whistler wave guidance by plasmapause gradients. Our analyses reveal that whistler mode waves near the inner edge of plasmapause are guided by a high density duct (HDD)‐like density gradient, and tend to have small wave normal angles (WNAs ≤ 20°). Whistler mode waves near the outer edge of the plasmapause are guided by a low density duct (LDD)‐like density gradient, and tend to have large WNAs (≥∼60°). These results reveal that the plasmapause can guide whistler waves and lead to unusual and anomalous pitch angle scattering. Key Points: We present in situ observation of the guiding effect of whistler mode waves by the plasmapause with NASA's Van Allen Probes dataThe guiding effect is resulted from the combined effect of the inhomogeneous magnetic field and plasma densityWhistler mode waves around the inner (outer) edge of plasmapause guided by high density duct‐like (low density duct‐like) density gradient, tend to have small (large) wave normal angles [ABSTRACT FROM AUTHOR]

With a one‐dimensional particle‐in‐cell simulation model, we have investigated the gap formation around 0.5Ωe of the quasi‐parallel whistler‐mode waves excited by an electron temperature anisotropy. When the frequencies of excited waves in the linear stage cross 0.5Ωe, or when they are slightly larger than 0.5Ωe but then drift to lower values, the Landau resonance can make the electron distribution form a beam‐like/plateau population. Such an electron distribution only slightly changes the dispersion relation of whistler‐mode waves, but can cause severe damping around 0.5Ωe via cyclotron resonance. At last, the wave spectrum is separated into two bands with a power gap around 0.5Ωe. The condition under different electron temperature anisotropy and plasma beta is also surveyed for such kind of power gap. Besides, when only the waves with frequencies lower than 0.5Ωe are excited in the linear stage, a power gap can also be formed due to the wave‐wave interactions, i.e., lower band cascade. Our study provides a clue to reveal the well‐known 0.5Ωe power gap of whistler‐mode waves ubiquitously observed in the inner magnetosphere.Plain Language Summary: The whistler‐mode waves, which have a great influence on electron dynamics in the Earth’s magnetosphere, are ubiquitously observed with a power minimum around 0.5Ωe. This phenomenon is also called the 0.5Ωe power gap. How the power gap forms is still one of the remaining issues since whistler waves were in‐situ detected by satellites about 50 years ago. In this study, with a PIC simulation model, we propose a promising and natural generation mechanism of the power gap in the quasi‐parallel whistler waves. When the frequencies of excited waves in the linear stage cross 0.5Ωe, or when they are slightly larger than 0.5Ωe but then drift to lower values, a pronounced beam‐like/plateau electron distribution in the parallel direction is formed due to the Landau resonance. Such an electron distribution can cause a severe damping around 0.5Ωe via cyclotron resonance. At last, the power gap naturally generates. Besides, when only the waves with frequencies lower than 0.5Ωe are excited in the linear stage, a power gap can also be formed due to the wave‐wave interactions. Our study can shed light on the formation of 0.5Ωe power gap in the whistler‐mode waves observed in the inner magnetosphere.Key Points: Quasi‐parallel whistler waves excited by anisotropic electrons can evolve into a spectrum with a power gap around 0.5ΩeThe electrons form a beam‐like/plateau distribution in the parallel direction due to the Landau resonanceThe electron beam‐like/plateau distribution leads to the severe damping of whistler waves around 0.5Ωe via cyclotron resonance [ABSTRACT FROM AUTHOR]

Flux ropes are ubiquitous at Earth's magnetopause and play important roles in energy transport between the solar wind and Earth's magnetosphere. In this study, structure and coalescence of the magnetopause flux ropes formed by multiple X line reconnection in cases with different southward interplanetary magnetic field (IMF) clock angles are investigated by using three‐dimensional global hybrid simulations. As the IMF clock angle decreases from 180°, the axial direction of the flux ropes becomes tilted relative to the equatorial plane, the length of the flux ropes gradually increases, and core field within flux ropes is formed by the increase in the guide field. The flux ropes are formed mostly near the subsolar point and then move poleward toward cusps. The flux ropes can eventually enter the cusps, during which their helical structure collapses, their core field weakens gradually, and their axial length decreases. When the IMF clock angle is large (i.e., the IMF is predominantly southward), the flux ropes can coalesce and form new ones with larger diameter. The coalescence between flux ropes can occur both near the subsolar point when they are newly formed and away from the subsolar point (e.g., in the southern hemisphere) when they move toward cusps. However, when the IMF clock angle is small (≤135°), we do not find coalescence between flux ropes.Key Points: We study the global structures of flux ropes formed by magnetopause reconnection in cases with different southward IMF clock anglesWhen flux ropes enter the cusps, their helical structure collapses, their core field weakens gradually, and their axial length decreasesIMF clock angle can affect whether and where flux ropes coalescence occurs [ABSTRACT FROM AUTHOR]

Introduction: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common and frequently occurring disease of the upper respiratory tract. The nasal instillation of the Gram‐negative (G−) bacterial product lipopolysaccharide (LPS) can induce not only acute sinusitis but also the development of CRSwNP in animal models. Nevertheless, the expression and distribution of LPS in patients with CRSwNP have not been investigated. And the study was to investigate the expression of LPS and its relationship with glucocorticoid receptors (GRs) in CRSwNP. Methods: Multiple methods, including bacterial culture and immunohistochemistry, were used to detect and analyze nasal bacteria, plasma LPS content, and the levels of LPS and GR‐α/β, cluster of differentiation 68 (CD68), and myeloperoxidase (MPO) expression, as well as their relationship in CRSwNP. Results: The number of G− bacteria and Escherichia coli (E. coli) was not significantly different between CRSwNP subjects and the controls. However, the positive rate of LPS was much higher than that of E. coli in CRSwNP subjects and was significantly higher in noneosinophilic CRSwNP subjects than in eosinophilic CRSwNP subjects. Moreover, the LPS levels were positively correlated with GR‐β but not GR‐α expression in CRSwNP. Immunofluorescence assays showed that LPS was mainly detected in CD68+ macrophages and MPO+ neutrophils, in addition to histiocytes, in CRSwNP. Conclusions: Persistent LPS in CRSwNP can lead to unresolved mucosal inflammation, eventually leading to tissue remodeling and the development of CRSwNP. Our findings suggest that increased LPS content and possible resistance to glucocorticoids may be one of the important pathogenic mechanisms of G− bacteria in CRSwNP. [ABSTRACT FROM AUTHOR]

By comparing an electron‐only reconnection event with a traditional reconnection event observed in the magnetotail, we illustrate the differences between and similarities of the two events. The electron behaviors are very similar in both events, but intensities of the electron flows and temperature in the traditional reconnection are much stronger than those in the electron‐only reconnection. The Hall electric field in the traditional reconnection occurs on the ion‐scale and is deflected from the normal direction by the significant magnetic field reconnected, while this field varies on the electron‐scale and points to the middle plane in the electron‐only reconnection. The comparison indicates that the electrons are undergoing the same process in both events, and the electron‐only reconnection was prior to the traditional reconnection. The Hall electric field could control the form of reconnection: producing either electron‐only reconnection or traditional reconnection. Key Points: We illustrate the differences between and similarities of the electron‐only reconnection and the normal reconnectionThe electron reconnection was prior to the normal reconnectionThe Hall electric field and the reconnected magnetic field intensity could control the form of reconnection [ABSTRACT FROM AUTHOR]

Substorm injection and solar wind dynamic pressure have long been considered as two main drivers of electromagnetic ion cyclotron (EMIC) wave excitation, but clear observational evidence is still lacking. With Van Allen Probes data from 2012–2017, we have investigated the roles of the two EMIC wave drivers separately, by using time‐modified AE+ and Pd+. Both the occurrence rate and magnetic amplitude of waves significantly increase with the enhancement of each index. During large AE+, EMIC waves are mainly generated in the dusk sector (16 ≤ MLT ≤ 20) and near the magnetic equator (|MLAT| < 10°). This is presumably due to substorm‐injected protons drifting from midnight sector to the plasmaspheric bulge. While during large Pd+, EMIC waves mainly occur in the noon sector (9 ≤ MLT ≤ 15). But there exist higher‐latitude (10° < |MLAT| < 20°) source regions besides equatorial source, possibly due to the minimum B regions. Our results provide strong observational support to existing generation mechanisms of EMIC waves in the Earth's magnetosphere. Plain Language Summary: Electromagnetic ion cyclotron (EMIC) waves are natural emissions in the Earth's magnetosphere, which are believed to be responsible for ion dynamics in the ring current and the loss of relativistic electrons in the radiation belts. How to excite these waves has attracted much attention. In the literature, there exist two potential drivers to excite EMIC waves, such as substorm injection (AE) and solar wind dynamic pressure (Pd). Although previous studies have shown that EMIC waves are closely correlated with AE and Pd, the observational evidence is still needed to confirm these two scenarios of wave excitation. In this study, we have developed a new technique to separately investigate the effects of each driver for EMIC wave generation, with time‐modified AE+ and Pd+. First of all, either strong substorm injection or solar wind pressure can individually cause the generation of EMIC waves. More importantly, the source regions of EMIC waves caused by two drivers can be clearly distinguished, and the expected high‐latitude source region is found during large Pd+. Our study provides valuable observational evidence to support the two drivers of EMIC wave excitation in the Earth's magnetosphere. Key Points: We have separately investigated the roles of substorm injection and solar wind pressure in exciting EMIC wave with time‐modified AE+ and Pd+The source region of EMIC waves driven by large AE+ is located in the dusk sector and near the magnetic equatorLarge Pd+ can solely cause EMIC wave excitation, which has two source regions: near the magnetic equator and in the higher‐latitude regions [ABSTRACT FROM AUTHOR]

Atmospheric escape is a fundamental process in the long‐term habitability evolution of terrestrial planets. Recent observations on Mars have found the concurrence of the severe ionospheric erosion and the large‐amplitude, quasi‐perpendicular magnetosonic waves. However, whether and then how these magnetosonic waves had contributed to the ionospheric erosion remains unclear. Here we propose a new candidate mechanism, electron Landau heating by magnetosonic waves, for the Martian ionospheric erosion. In contrast to the cyclotron resonance with oxygen atomic and molecular ions above the escape energies, the magnetosonic waves Landau‐resonate with the thermal electrons at energy channels of the order of 0.01–0.1 eV. Through the Landau resonance over tens of minutes, the large‐amplitude (12 nT) magnetosonic waves can heat the topside ionospheric electrons to ∼2 times the normal temperature. The topside ionospheric electron heating could result in the enhancement of the ambipolar electric potential and eventually facilitate the escape of ionospheric plasma. Plain Language Summary: An atmosphere of sufficient density is a fundamental condition for a habitable terrestrial planet. Mars as a terrestrial planet in the habitable zone of our solar system lost much of its atmosphere over billions of years and has thus become a unique testing ground to understand the planetary atmospheric loss processes. Recent observations on Mars have shown that the severe erosion of the ionosphere, an ionized part of the upper atmosphere, was accompanied by the large‐amplitude, quasi‐perpendicular magnetosonic waves. However, whether and then how these magnetosonic waves had contributed to the ionospheric erosion remains unclear. On the basis of space observations and numerical calculations, we propose a new physical mechanism, electron Landau heating by magnetosonic waves, for the Martian ionospheric erosion. The large‐amplitude magnetosonic waves can heat the topside ionospheric electrons to ∼2 times the normal temperature over tens of minutes, enhance the ambipolar electric potential, and eventually facilitate the escape of ionospheric plasma. The electron Landau heating process may also contribute to the ionospheric erosion of other terrestrial planets within and beyond our solar system. Key Points: Magnetosonic waves are difficult to cyclotron‐resonate with Martian ionospheric oxygen atomic and molecular ions below the escape energiesStrong magnetosonic waves can Landau‐heat Martian topside ionospheric electrons to 2 times the normal temperature over tens of minutesElectron Landau heating by magnetosonic waves may facilitate the Martian ionospheric erosion by enhancing the ambipolar electric field [ABSTRACT FROM AUTHOR]

Suprathermal electrons are a major heat source of ionospheric plasma. How the suprathermal electrons evolve during their bounces inside the plasmasphere is a fundamental question for the magnetosphere‐ionosphere coupling. On the basis of Van Allen Probes observations and quasi‐linear simulations, we present here the first quantitative study on the evolution of suprathermal electrons under the competition between Landau heating by whistler mode hiss waves and Coulomb collisional cooling by background plasma inside a plasmaspheric plume. We show that the Landau heating can prevail over the collisional cooling for >50 eV electrons and cause the field‐aligned suprathermal electron fluxes to increase by up to 1 order of magnitude within 1.5 hr. Our results imply that the plasmaspheric plume hiss waves could mediate energy from the ring current electrons to the ionospheric plasma. Plain Language Summary: The ionospheric plasma temperature variation can affect the Earth's atmospheric escape and the spacecraft orbit decay. A major heat source of the ionospheric plasma is the suprathermal (several eV to hundreds of eV) electrons, which can bounce along the magnetic field lines inside the plasmasphere. How these suprathermal electrons evolve during their bounces is a fundamental question for the magnetosphere‐ionosphere coupling. In the past, the plasmaspheric suprathermal electrons were usually considered to gain energy from the ring current ions through Coulomb collisions and wave‐particle interactions. Here we show that strong whistler mode hiss waves can grow from the instability of the ring current electrons in the plasmaspheric drainage plume, and their Landau heating can prevail over the collisional cooling by background plasma for >50 eV electrons. The enhanced field‐aligned suprathermal electrons could eventually heat the ionospheric plasma. These results have significant implications for understanding the energy transfer process from the magnetosphere to the ionosphere. Key Points: The collisional cooling by background plasma counteracts largely the Landau heating by hiss waves for <50 eV electronsThe Landau heating can increase the field‐aligned fluxes of >50 eV electrons by 1 order of magnitude within 1.5 hrPlasmaspheric plume hiss could mediate energy from the ring current electrons through the suprathermal electrons to the ionospheric plasma [ABSTRACT FROM AUTHOR]

Electromagnetic ion cyclotron (EMIC) waves play an important role in the energy transfer among particles of different energies and species in the magnetosphere, whose drivers have been commonly recognized as solar wind compressions and storm/substorm proton injections. However, how the solar wind decompressions related to frequently occurring discontinuities compete with the proton injections in the evolution of EMIC waves has been rarely investigated. Here we present a complete end‐to‐end observation by Wind, THEMIS, and Van Allen Probes missions during the main phase of the 23 February 2014 storm of a succession of solar wind rotational discontinuities decompressing the magnetosphere within 200 s, adiabatically decelerating the freshly injected >10 keV protons, and thus suppressing the EMIC waves in the inner magnetosphere. Our results highlight the importance of solar wind conditions for the evolution of inner magnetospheric EMIC waves from a new perspective. Plain Language Summary: Magnetospheric electromagnetic ion cyclotron (EMIC) waves are ultralow‐frequency (0.1–5.0 Hz) pulsations observable both on the ground and in space. They contribute significantly to the magnetospheric particle dynamics and the magnetosphere‐ionosphere coupling. Previous studies have recognized two main drivers for EMIC waves: solar wind compressions and magnetospheric storm/substorm proton injections. However, both compressive and decompressive discontinuities, with dynamic pressure jumps on a timescale of seconds to minutes, can occur in the solar wind upstream of Earth, and under the condition of the fresh proton injections, to what extent the solar wind decompressive discontinuities can affect the EMIC waves in the inner magnetosphere remains to be determined. On the basis of observations by three space missions in the solar wind and magnetosphere during the main phase of a moderate storm, we show that the solar wind decompressive discontinuities can cause a relaxation of the magnetosphere, deceleration of the freshly injected protons, and thus quenching of the EMIC waves in the inner magnetosphere. These results illustrate the importance of solar wind conditions for the evolution of inner magnetospheric EMIC waves from a new perspective. Key Points: In the temperature anisotropic solar wind, a group of rotational discontinuities caused a substantial decrease in the dynamic pressureAlong with the magnetospheric relaxation within 200 s, the storm‐injected protons experienced betatron and Fermi decelerationsThe adiabatical reduction of hot proton fluxes suppressed the EMIC wave instabilities in the inner magnetosphere [ABSTRACT FROM AUTHOR]

Background: Male breast cancer is a rare malignant disease, accounting for <1% of all breast cancers. The treatment of male breast cancer is mainly extrapolated from the enormous literature and clinical experience in women. The objective of the current study was to assess the relationship between adjuvant chemotherapy and survival in a large population-based cohort of patients with early-stage male breast cancer.Methods: Men with invasive stage I to stage III breast cancer were identified in the Surveillance, Epidemiology, and End Results cancer database from 1990 to 2014. The effect of chemotherapy on survival was determined using multivariable Cox regression.Results: Of 2713 male patients enrolled, 1817 (66.9%) did not receive chemotherapy. Age, T classification, N classification, tumor grade, and progesterone receptor (PR) status were found to be strong predictors of chemotherapy administration. Chemotherapy was associated with a significant 26% reduction in all-cause mortality (P < .001) and a marginally significant 21% reduction in breast cancer-specific mortality (P = .085). For men with PR-negative breast cancer, use of chemotherapy was associated with improved breast cancer-specific survival (hazards ratio [HR], 0.50; 95% confidence interval [95% CI], 0.28-0.91 [P = .023]) and overall survival (HR, 0.54; 95% CI, 0.37-0.77 [P = .001]). However, chemotherapy did not improve the breast cancer-specific survival for all men with PR-positive tumors (P = .959); it was associated with improved overall survival (HR, 0.78; 95% CI, 0.66-0.92 [P = .004]) for men with PR-positive stage II and stage III breast cancer.Conclusions: Chemotherapy should be considered for men with PR-negative, nonmetastatic breast cancer and PR-positive, stage II and stage III breast cancer. [ABSTRACT FROM AUTHOR]

Whistler mode chorus waves in the Earth's inner magnetosphere are usually composed of discrete elements, and each element can be characterized by the following properties: the amplitude, the duration, the frequency span, and the frequency chirping rate. Using a one‐dimensional (1‐D) particle‐in‐cell (PIC) simulation code, we study the dependence of these properties of a rising‐tone chorus on the number density nheq/nc0 and temperature anisotropy AT of energetic electrons at the magnetic equator. The whistler waves are first excited around the magnetic equator by anisotropic energetic electrons and then develop into a rising‐tone chorus when they leave away from the equator. During the propagation toward the pole, the rising‐tone chorus with nearly constant frequency span first enhances and then decays. Its frequency chirping rate declines in the early stage and then gradually increases. Meanwhile, the chorus duration is quite the opposite due to propagation effect. Over a suitable range of nheq/nc0 to generate rising‐tone chorus, the frequency chirping rate of the excited rising‐tone chorus first increases and then saturates, while its saturated amplitude, duration, and frequency span have a rising tendency with the increasing nheq/nc0. As for AT, the frequency chirping rate of the generated rising‐tone chorus is increasing with the increase of AT that is consistent with prediction of nonlinear theory, while the duration is just the opposite. Our simulation study can give a further understanding of the generation and propagation of rising‐tone chorus waves. Key Points: The frequency chirping rate and the duration of the rising‐tone chorus excited near the magnetic equator change due to propagation effectThe amplitude, duration and frequency span of the rising‐tone chorus increase with the increasing number density of energetic electronsThe frequency chirping rate increases with increasing temperature anisotropy of energetic electrons, while the duration is the opposite [ABSTRACT FROM AUTHOR]

The oral maintenance of patients with periodontal disease mainly depends on clinical examination. However, insufficient number of medical workers cannot carry out detailed oral health education for a large number of patients within limited time and provide these patients with proper and effective oral health nursing methods. In this research, our study put forward a new Artificial Intelligence (AI) based method to diagnose chronic gingivitis, which is based on multichannel gray‐levelco‐occurrence matrix (MGLCM) and particle swarm optimization neural network(PSONN). Meanwhile, different training algorithms were used as comparison groups. The data set contains 800 images: 400 chronic gingivitis images and 400 healthy gingiva images. The results certify that the specificity, sensitivity, precision, accuracy and F1 Score of MGLCM (PSONN as a classifier) method is 78.17%, 78.23%, 78.24% ,78.20%and 78.17%, respectively. The association of MGLCM and PSONN is more accurate and efficient than approaches: NBC, WN+SVM,ELM and CLAHE+ELM. [ABSTRACT FROM AUTHOR]

Whistler mode chorus waves are coherent electromagnetic emissions in planetary magnetospheres, characterized by rising‐tone or falling‐tone chirping elements. Understanding the cause of different chirping directions and their properties is an important step in resolving the long‐standing problem of nonlinear chorus generation. We report here, for the first time, particle‐in‐cell simulations of bidirectional chirping of whistler waves in a uniform magnetic field and falling‐tone‐only chirping in an inhomogeneous field. Combined with previous simulations of rising‐tone‐only emissions, we demonstrate that the background magnetic field inhomogeneity is not required for chirping of chorus, but it plays a key role in determining the chirping direction. The findings of the present work also unveil the critical role of the dipole geometry of Earth's magnetic field in causing the statistical predominance of rising‐tone chorus and the oblique propagation of falling‐tone chorus. Plain Language Summary: Whistler mode chorus is a type of naturally occurring electromagnetic emission in planetary magnetospheres. This important wave is known to produce relativistic electrons in the hazardous radiation belts and to precipitate energetic electrons from space into the upper atmosphere to form diffuse aurora. Chorus consists of discrete spectral elements with fast frequency chirping in either upward (rising‐tone) or downward (falling‐tone) directions. A long‐standing problem is to understand the origin of different chirping directions and their distinctive observational properties. Here, we show, by first‐principle particle simulations, that the background magnetic field inhomogeneity plays a key role in determining the chirping direction and that the dipole geometry of Earth's magnetic field essentially controls the properties of chorus. Our results naturally account for the dominance of rising‐tone chorus and the oblique propagation of falling‐tone chorus and provide important insights into the fundamental mechanism of the nonlinear chirping process. The propagation properties of chorus are also expected to be similar in all planetary magnetospheres with a dipole‐type magnetic field. Key Points: We present the first PIC simulations of falling‐tone chorus waves and chirping with a uniform background magnetic fieldWe demonstrate that the background magnetic field inhomogeneity controls the chirping direction of parallel‐propagating chorusOur results explain the dominance of rising‐tone chorus and the oblique propagation of falling‐tone chorus in the magnetosphere [ABSTRACT FROM AUTHOR]

This study aimed to retrospectively evaluate the circulating free DNA (cfDNA) level in patients with locally advanced breast cancer (LABC) having different neoadjuvant chemotherapy (NCT) responses and to investigate whether dynamic changes in cfDNA level could predict the effectiveness of NCT in patients with LABC. Data on 61 patients with LABC were included. NCT responses were evaluated using the response evaluation criteria. Blood samples were collected for cfDNA detection before treatment and after the first and eighth courses of chemotherapy. The Alu 111‐bp and 260‐bp fragment levels were evaluated by polymerase chain reaction, and the predictive value of the cfDNA level in the NCT response was determined. In vitro, the MCF‐7 and MCF‐7/ADR cell lines were applied to simulate the phenomenon of drug resistance and explain the underlying mechanism. The Alu 111‐bp level increased after the first NCT course (P =.014) and then remained high after NCT in the high‐R group (P =.047), but it remained steady in the low‐R group during NCT. A similar tendency in the Alu 260‐bp level was revealed in different groups. The ∆∆Ct value of Alu 260‐bp had good diagnostic efficiency in assessing predictive ability. The area under the curve for the ∆∆Ct1 and ∆∆Ct2 of Alu 260‐bp was 0.697 and 0.647, respectively. The cfDNA level was closely related to epirubicin‐induced apoptosis and changes in the Ki‐67 index in vitro. The elevation of cfDNA after one chemotherapy cycle was mediated by the apoptosis of tumor cells and related to the improved chemotherapy response. [ABSTRACT FROM AUTHOR]

Breast cancer has become the most common cancer in women, and nontriple negative breast cancer (non‐TNBC) accounts for 80–90% of all invasive breast cancers. Early detection, diagnosis, and treatment are considered key to a successful cure. Conventionally, breast imaging and needle core biopsy are used for detection and monitoring. However, small variations in volume might be ignored in imaging, and traditional biopsies are spatially and temporally limited, leading to a significant delay in cancer detection and thus prompting renewed focus on early and accurate diagnosis. In this article, we investigated whether there is an accurate molecule in peripheral blood that can help diagnose breast cancer. Similar to microRNAs, tRNA‐derived fragments (tRFs) have been reported to be involved in many pathological processes in breast cancer, but whether they can serve as candidate biomarkers for breast cancer remains unclear. Using high‐throughput sequencing technology, we identified 4,021 differentially expressed tRFs in normal and breast cancer cell lines, and eight tRFs were selected to establish a signature as a predictive biomarker of non‐TNBC. Furthermore, quantitative reverse‐transcriptase polymerase chain reaction was performed to verify the expression of the signature and analyze the correlation between dysregulated tRFs and breast cancer. The results indicated that tDR‐7816, tDR‐5334, and tDR‐4733 might be promising biomarkers. Through further bioinformatics analysis, we predicted that tDR‐7816 influences the xenobiotic metabolic processes that support the oncogenesis of breast cancer. In summary, our results provide a rationale for using circulating tDR‐7816 expression as a novel potential biomarker for the diagnosis of patients with early non‐TNBC. [ABSTRACT FROM AUTHOR]

Plasmaspheric hiss is an important whistler‐mode emission shaping the Van Allen radiation belt environment. How the plasmaspheric hiss waves are generated, propagate, and dissipate remains under intense debate. With the five spacecraft of Van Allen Probes, Exploration of energization and Radiation in Geospace (Arase), and Geostationary Operational Environmental Satellites missions at widely spaced locations, we present here the first comprehensive observations of hiss waves growing from the substorm‐injected electron instability, spreading within the plasmasphere, and dissipating over a large spatial scale. During substorms, hot electrons were injected energy‐dispersively into the plasmasphere near the dawnside and, probably through a combination of linear and nonlinear cyclotron resonances, generated whistler‐mode waves with globally drifting frequencies. These waves were able to propagate from the dawnside to the noonside, with the frequency‐drifting feature retained. Approximately 5 hr of magnetic local time away from the source region in the dayside sector, the wave power was dissipated to e−4 of its original level. Plain Language Summary: A noisy band of electromagnetic waves with frequencies ranging from tens of hertz to several kilohertz in the Earth's plasmasphere is termed plasmaspheric hiss. These waves are recognized to shape the Van Allen radiation belt environment and then affect the spacecraft survivability and lifetime. How the plasmaspheric hiss waves are generated, propagate, and dissipate has been a fundamental unanswered question since their discovery. With three space missions scattered in the inner magnetosphere, we present here the first comprehensive observations of hiss waves growing from the substorm‐injected electron instability, spreading within the plasmasphere, and dissipating over a large spatial scale. These findings have significant implications for the modeling of the plasmaspheric hiss waves and the Van Allen radiation belt dynamics. Key Points: Near the dawnside, energy‐dispersively injected electrons generated plasmaspheric hiss with globally drifting frequenciesThe frequency drift feature allowed tracing the plasmaspheric hiss propagation from the dawnside to the noonsideThe dayside plasmaspheric hiss dissipated away roughly within a magnetic local time span of 5 hr [ABSTRACT FROM AUTHOR]

Using measurements by the Magnetospheric Multiscale spacecraft in the magnetotail, we studied electron distribution functions across an electron diffusion region. The dependence of the nongyrotropic distribution on the energy and vertical distance from the electron diffusion region midplane was revealed for the first time. The nongyrotropic distribution was observed everywhere except for an extremely narrow layer right at the electron diffusion region midplane. The energy of the nongyrotropic distribution increased with growth of the vertical distance from the midplane. For the electrons within certain energy range, they exhibited the nongyrotropic distribution at the distance further away from the midplane than that expected from the meandering motion. The correlation between the crescent‐shaped distribution with multiple stripes and the large Hall electric field was established. It appears that the measured nongyrotropic distribution and the crescent‐shaped distribution were caused by the meandering motion and the Hall electric field together. Plain Language Summary: The Magnetospheric Multiscale mission is designed to study electron physics of magnetic reconnection, a key process for many explosive phenomena in solar flares and magnetosphere. Understanding electron motion is highly important in the study of magnetic reconnection, and the electron velocity distribution is an intuitive and effective way to study the electron dynamics. In this paper, we present a complete electron diffusion region crossing by Magnetospheric Multiscale during a nearly symmetric magnetic reconnection in the magnetotail and show the evolution of the electron velocity distributions across the electron diffusion region. In addition, the relationship between Hall electric field and crescent‐shaped electron distribution is also shown in this paper. Key Points: The electron nongyrotropic distribution depended on the energy and the normal distance from the midplane of the electron diffusion regionThe electron crescent distributions were caused by the meandering motion and the Hall electric field togetherThe fine substructures were observed in the narrow electron diffusion region [ABSTRACT FROM AUTHOR]

Accurately classify teeth category is important in further dental diagnosis. Analyzing huge dental data, that is, identifying the teeth category, is often a hard task. Current automatic methods are based on computer vision and deep learning approaches. In this study, we aimed to classify the teeth category into four classes: incisor, canine, premolar, and molar. Cone beam computed tomography was used to collect the data. We proposed a seven‐layer deep convolutional neural network with global average pooling to identify teeth category. Data augmentation method was used to enlarge the size of training dataset. The results showed the sensitivities of incisor, canine, premolar, and molar teeth are 88%, 86%, 84%, and 90%, respectively. The average sensitivity is 87.0%. We validated max pooling gives better results than average pooling. Our method is better than three state‐of‐the‐art approaches. [ABSTRACT FROM AUTHOR]

In this letter, we have investigated the correlation between lower band chorus waves and electron beam‐like distribution with long‐term THEMIS data. Cold, hot, and beam electrons are assumed in the plasma. For quasi‐parallel chorus waves, they are usually observed along with a relatively weak electron beam. Moreover, the density ratio between beam and hot electrons nb/nh is positively correlated with the wave parallel electric field and inversely correlated with the hot electron density, in agreement with a formation of the beam by Landau acceleration during wave propagation, while, along with oblique waves, there typically exists a strong electron beam. Notably, the nb/nh is found to be independent of both the parallel electric field and hot electron density, indicating that the electron beam‐like distribution should be a precondition for exciting oblique waves rather than caused by waves. Our study provides some new insights into understanding the generation and evolution of chorus waves. Plain Language Summary: The interaction between whistler‐mode chorus waves and electrons has long been a hot topic, which is important for understanding the evolution and generation of chorus waves. Both theoretical and simulation studies have indicated that quasi‐parallel chorus waves are initially excited near the magnetic equator and then propagate toward high‐latitude regions with increasing wave normal angles and enhanced parallel electric fields. During the propagation, the Landau resonance between chorus waves and electrons begins to take effect, causing the damping of waves and the formation of local electron beam. Within the equatorial region, there also exist a number of oblique chorus waves with large wave normal angles, which should be also locally excited. To generate oblique waves, a beam‐like electron distribution is needed to suppress the Landau damping of oblique chorus waves, which should already exist before those waves. Although the two physical pictures are well known in this community, actually, there is still a lack of observational support. In this paper, we have made some new progress in understanding these two different scenarios by studying the correlation between chorus waves and electron beam‐like distribution with long‐term THEMIS data. Key Points: We have investigated the correlation between lower‐band chorus waves and electron beam‐like distribution using THEMIS data.Along with quasi‐parallel chorus waves, a weak elelctron beam can be observed, which is caused by Landau resonance with waves.But for oblique chorus waves, the electron beam‐like distribution should be a precondition for exciting waves rather than caused by waves. [ABSTRACT FROM AUTHOR]

Breast cancer (BC) is one of the most common cancers in females. Since early detection can bring prognosis benefit, discovery of novel noninvasive biomarkers for BC diagnosis is in urgent need. In this four‐phase study, we profiled miRNA expression in plasma samples from a total of 257 BC patients and 257 normal controls (NCs). Exiqon miRNA qPCR panel was used to select candidate miRNAs in the screening phase which were further analyzed using qRT‐PCR in the following training, testing and external validation phases. Finally, we identified five plasma miRNAs (let‐7b‐5p, miR‐122‐5p, miR‐146b‐5p, miR‐210‐3p and miR‐215‐5p) whose expression levels were significantly different between BC patients and NCs. A 5‐miRNA panel in plasma with high sensitivity and specificity was then constructed to detect BC. The areas under the receiver‐operating characteristic curves (AUCs) of the panel were 0.683, 0.966, 0.978 for the training, testing and external validation sets, respectively. Expression of the identified miRNAs was further analyzed among 32 pairs of BC tissue and the adjacent normal tissue samples as well as plasma‐derived exosome samples from 32 BC patients vs 32 NCs. Let‐7b‐5p was contrarily down‐regulated in BC tissue. In exosomes samples, only miR‐122‐5p was significantly up‐regulated as in plasma for BC patients. In conclusion, we identified a 5‐miRNA plasma panel (let‐7b‐5p, miR‐122‐5p, miR‐146b‐5p, miR‐210‐3p and miR‐215‐5p) that could serve as a promising biomarker for BC detection. [ABSTRACT FROM AUTHOR]

Based on the Magnetospheric Multiscale observations in the magnetotail, we present a complete crossing of the current sheet with ongoing magnetic reconnection. The field‐aligned inflowing electrons were observed in both separatrix regions (SRs) and their energy extended up to several times of the thermal energy. Along the SR, a net parallel electrostatic potential was estimated and could be the reason for the inflowing electron streaming. In the northern SR, the electron frozen‐in condition was violated and nonideal electric field was inferred to be caused by the gradient of the electron pressure tensor. The nongyrotropic electron distribution and significant energy dissipation were observed at the same region. The observations indicate that the inner electron diffusion region can extend along the separatrices or some electron‐scale instability can be destabilized in the SR. Plain Language Summary: The microphysics in the separatrix region (SR) plays an important role for the energy conversion in reconnection. In this letter, we present nonideal electric field in the SR and the electron acceleration therein. These observations indicate that a significant part of energy conversion takes place in the SR during reconnection. Key Points: Nonideal electric field was observed in the separatrix region and inferred to be caused by gradient of the electron pressure tensorThe nongyrotropic electron distribution and substantial energy dissipation were observed in the separatrix regionAsymmetry between two sides of the current sheet was observed in the symmetric reconnection [ABSTRACT FROM AUTHOR]