Identification of optical auroras caused by mantle precipitation with the aid of particle observations from DMSP satellites

Particle observations of the Defense Meteorological Satellite Program (DMSP) show that discrete auroral structures commonly exist in the region of the plasma mantle, but the optical features of the aurora generated by particles from the plasma mantle (called ‘mantle aurora’ in this paper) have not been established. A comparison of 7-year optical auroral observations made at the Yellow River Station with conjugate particle observations obtained from the DMSP confirm that mantle auroras have common features and can be clearly identified from all-sky imager observations. The mantle auroras normally present as sporadic and weak auroral structures split poleward of the dayside auroral oval. They are observed in both the green and red lines with the intensity of the red line being greater than that of the green line. In this paper, we illustrate typical mantle auroras and provide statistics on 55 mantle aurora cases that are confirmed by particle observation by the DMSP. Statistical results show that the occurrence of the mantle aurora has no clear dependence on the IMF By and Bz conditions, but the motion of the mantle aurora strongly depends on the IMF By, which indicates that the generation of the mantle aurora is intimately related to the dayside magnetopause reconnection. With the fundamental criteria for distinguishing the mantle aurora presented in this paper, we will be able to independently identify the mantle auroras from ground optical observations. This will allow us to investigate the physical processes that occur in the plasma mantle by monitoring the evolution of the auroral forms

Interplanetary shock-associated aurora

Interplanetary shocks or solar wind pressure pulses have prompted impacts on Earth’s magnetospheric and ionospheric environment, especially in causing dynamic changes to the bright aurora in the polar ionosphere. The auroral phenomenon associated with shock impingements, referred to as shock aurora, exhibits distinct signatures differing from other geophysical features on the dayside polar ionosphere. Shock aurora provides a direct manifestation of the solar wind–magnetosphere–ionosphere interaction. Imagers onboard satellites can obtain the associated large-scale auroral characteristics during shock impingement on the magnetopause. Therefore, auroral data from satellites are very useful for surveying the comprehensive features of shock aurora and their general evolution. Nonetheless, the ground-based high temporal-spatial resolution all-sky imagers installed at scientific stations play an essential role in revealing medium- and small-scale characteristics of shock aurora. Here, we focus on shock aurora imaging signatures measured by imagers onboard satellites and ground-based all-sky imagers

Data-Driven Distributionally Robust Electric Vehicle Balancing for Autonomous Mobility-on-Demand Systems under Demand and Supply Uncertainties

Electric vehicles (EVs) are being rapidly adopted due to their economic and societal benefits. Autonomous mobility-on-demand (AMoD) systems also embrace this trend. However, the long charging time and high recharging frequency of EVs pose challenges to efficiently managing EV AMoD systems. The complicated dynamic charging and mobility process of EV AMoD systems makes the demand and supply uncertainties significant when designing vehicle balancing algorithms. In this work, we design a data-driven distributionally robust optimization (DRO) approach to balance EVs for both the mobility service and the charging process. The optimization goal is to minimize the worst-case expected cost under both passenger mobility demand uncertainties and EV supply uncertainties. We then propose a novel distributional uncertainty sets construction algorithm that guarantees the produced parameters are contained in desired confidence regions with a given probability. To solve the proposed DRO AMoD EV balancing problem, we derive an equivalent computationally tractable convex optimization problem. Based on real-world EV data of a taxi system, we show that with our solution the average total balancing cost is reduced by 14.49%, and the average mobility fairness and charging fairness are improved by 15.78% and 34.51%, respectively, compared to solutions that do not consider uncertainties.Comment: 16 page

Optical and SuperDARN radar observations of duskside shock aurora over Zhongshan Station

We present observations of a duskside shock aurora occurred on 21 April 2001 by the SuperDARN radar at Syowa Station and the all-sky camera at Zhongshan Station (ZHS) in Antarctica when the radar was operated in fast-scan mode covering the ZHS region. With the two independent data sets, we examine ionospheric plasma convection and aurora arising from a sudden impulse (SI) event associated with an interplanetary shock. During the transient shock compression, the aurora was quiescent without any optical emission at the preliminary impulse of the SI. About 7 min later, a new thin auroral arc with brighter emissions and a lifetime of ~14 min expanded westward from the region above ZHS during the main impulse of the SI. SuperDARN radar line-of-sight measurements showed periodical oscillation in the flow direction with ultra-low-frequency waves having a period of ~8 min during the shock compression. We suggest that downward field-aligned current during the preliminary impulse stage of the SI was the main driver of the first plasma flow reversal, and the subsequent new discrete auroral arc may be associated with field-aligned acceleration in the region of the main impulse related upward field-aligned currents. The ground magnetometer observations suggest that the oscillation of the ionospheric convection on the duskside was associated with field line resonance activity

Geomagnetic pulsations caused by the Sumatra earthquake on December 26, 2004

A long period Pc5 pulsation was observed at Phimai in Thailand, shortly after the origin time of the Sumatra earthquake on December 26, 2004. The localized nature and the period of oscillations suggest that the long period magnetic pulsation was generated by dynamo action in the lower ionosphere, set up by an atmospheric pressure pulse which propagated vertically as an acoustic wave when the ocean floor suddenly moved vertically. It is speculated that a Pc3 type pulsation observed at Tong Hai in China, 10 degrees north of Phimai in latitude, was the result of magnetic field line resonance with a magnetosonic wave generated from the electric and magnetic fields of the dynamo current caused by the Earthquake.publishersversionPeer reviewe

Simultaneous optical and radar observations of poleward moving auroral forms under different IMF conditions

Using high temporal resolution optical data obtained from three-wavelength all-sky imagers at Chinese Yellow River Station in the Arctic, together with the EISCAT Svalbard radar (ESR) and SuperDARN radars, we investigated the dayside poleward moving auroral forms (PMAFs) and the associated plasma features in the polar ionosphere under different interplanetary magnetic field (IMF) conditions, between 0900 and 1010 UT on 22 December 2003. Simultaneous optical and ESR observations revealed that all PMAFs were clearly associated with pulsed particle precipitations. During northward IMF, particles can precipitate into lower altitudes and reach the ionospheric E-region, and there is a reverse convection cell associated with these PMAFs. This cell is one of the typical signatures of the dayside high-latitude (lobe) reconnection in the polar ionosphere. These results indicate that the PMAFs were associated with the high-latitude reconnection. During southward IMF, the PMAFs show larger latitudinal motion, indicating a longer mean lifetime, and the associated ionospheric features indicate that the PMAFs were generated by the dayside low-latitude reconnection

BaFe12O19 single-particle-chain nanofibers : preparation, characterization, formation principle, and magnetization reversal mechanism

BaFe12O19 single-particle-chain nanofibers have been successfully prepared by an electrospinning method and calcination process, and their morphology, chemistry, and crystal structure have been characterized at the nanoscale. It is found that individual BaFe12O19 nanofibers consist of single nanoparticles which are found to stack along the nanofiber axis. The chemical analysis shows that the atomic ratio of Ba/Fe is 1:12, suggesting a BaFe12O19 composition. The crystal structure of the BaFe12O19 single-particle-chain nanofibers is proved to be M-type hexagonal. The single crystallites on each BaFe12O19 single-particlechain nanofibers have random orientations. A formation mechanism is proposed based on thermogravimetry/differential thermal analysis (TG-DTA), X-ray diffraction (XRD), and transmission electron microscopy (TEM) at six temperatures, 250, 400, 500, 600, 650, and 800 �C. The magnetic measurement of the BaFe12O19 single-particle-chain nanofibers reveals that the coercivity reaches a maximum of 5943 Oe and the saturated magnetization is 71.5 emu/g at room temperature. Theoretical analysis at the micromagnetism level is adapted to describe the magnetic behavior of the BaFe12O19 single-particle-chain nanofibers

Chinese Antarctic Magnetometer Chain at the Cusp Latitude

A Chinese Antarctic Magnetometer (CAM) chain from Zhongshan Station (ZHS) to Dome-A (DMA) has been established since February 2009. A regular magnetometer is operated at ZHS, and four low power magnetometers are operated along the interior route from ZHS to DMA in the cusp latitude, extending over a distance of 1260 km. These stations fill an important void in the Antarctic magnetometer network. Furthermore, the CAM chain is magnetically conjugated with the Arctic region reaching from the Svalbard archipelago to Daneborg, on the east coast of Greenland. Conjugate measurements using the Arctic and Antarctic magnetometers provide excellent opportunities to investigate phenomena related to the coupling of the solar wind to the magnetosphere and ionosphere, such as magnetic impulse events, flux transfer events, traveling convection vortices and ultra-low frequency waves

Lenvatinib improves anti-PD-1 therapeutic efficacy by promoting vascular normalization via the NRP-1-PDGFRβ complex in hepatocellular carcinoma

IntroductionThe limited response to immune checkpoint blockades (ICBs) in patients with hepatocellular carcinoma (HCC) highlights the urgent need for broadening the scope of current immunotherapy approaches. Lenvatinib has been shown a potential synergistic effect with ICBs. This study investigated the optimal method for combining these two therapeutic agents and the underlying mechanisms.MethodsThe effect of lenvatinib at three different doses on promoting tissue perfusion and vascular normalization was evaluated in both immunodeficient and immunocompetent mouse models. The underlying mechanisms were investigated by analyzing the vascular morphology of endothelial cells and pericytes. The enhanced immune infiltration of optimal-dose lenvatinib and its synergistic effect of lenvatinib and anti-PD-1 antibody was further evaluated by flow cytometry and immunofluorescence imaging.ResultsThere was an optimal dose that superiorly normalized tumor vasculature and increased immune cell infiltration in both immunodeficient and immunocompetent mouse models. An adequate concentration of lenvatinib strengthened the integrity of human umbilical vein endothelial cells by inducing the formation of the NRP-1-PDGFRβ complex and activating the Crkl-C3G-Rap1 signaling pathway in endothelial cells. Additionally, it promoted the interaction between endothelial cells and pericytes by inducing tyrosine-phosphorylation in pericytes. Furthermore, the combination of an optimal dose of lenvatinib and an anti-PD-1 antibody robustly suppressed tumor growth.ConclusionsOur study proposes a mechanism that explains how the optimal dose of lenvatinib induces vascular normalization and confirms its enhanced synergistic effect with ICBs