Rare earth ion-doped Y2.95R0.05MgAl3SiO12 (R = Yb, Y, Dy, Eu, Sm) garnet-type microwave ceramics for 5G application

In this work, Y2.95R0.05MgAl3SiO12 (R=Yb, Y, Dy, Eu, Sm) microwave single-phase dielectric ce-ramics were successfully prepared via conventional ceramic technology by doping a series of rare earth elements with different ionic radius (Yb, Y, Dy, Eu, Sm) for the first time. The effects of A site occupied by rare earth elements on the microwave dielectric properties of Y2.95R0.05MgAl3SiO12 were studied by crystal structure refinement, scanning electron microscope (SEM), bond valence theory, P-V-L theory and infrared reflection spectroscopy. It was found that the ionicity of Y-O bond, the lattice energy, the bond energy and bond valance of Al(Tet)-O bond had important effects on microwave dielectric properties. Particularly, the optimum microwave dielectric properties were obtained for Y2.95Dy0.05MgAl3SiO12 sintered at 1575 °C for 6 h, with εr = 9.68, Q×f = 68,866 GHz, and τf = -35.8 ppm/°C, displaying its potential prospect in the 5G communication

Modelling the observed distortion of multiple (ghost) CME fronts in STEREO Heliospheric imagers

In this work, we have, for the first time, applied the interpretation of multiple ghost-fronts to two synthetic CMEs propagating within a structured solar wind using the HUXt solar wind model. The two coronal mass ejections (CMEs) occurred on 2012 June 13-14 showing multiple fronts in images from STEREO HIs. The HUXt model is used to simulate the evolution of these CMEs across the inner heliosphere as they interacted with structured ambient solar wind. The simulations reveal that the evolution of CME shape is consistent with observations across a wide range of solar latitudes and that the manifestation of multiple `ghost-fronts' within HIs field of view is consistent with the positions of the nose and flank of the same CME structure. This provides further conformation that the angular separation of these features provides information on the longitudinal extent of a CME. For one of the CMEs considered in this study, both simulations and observations show that a concave shape develops within the outer CME front. We conclude that this distortion results from latitudinal structure in the ambient solar wind speed. The work emphasizes that the shape of the CME cannot be assumed to remain a coherent geometrical shape during its propagation in the heliosphere. Our analysis demonstrates that the presence of `ghost' CME fronts can be used to infer the distortion of CMEs by ambient solar wind structure as a function of both latitude and longitude. Those information have potential to improve the forecasting of space weather events at Earth

FXYD3 functionally demarcates an ancestral breast cancer stem cell subpopulation with features of drug-tolerant persisters

乳がんの再発を起こす原因細胞を解明. 京都大学プレスリリース. 2023-11-16.The heterogeneity of cancer stem cells (CSCs) within tumors presents a challenge in therapeutic targeting. To decipher the cellular plasticity that fuels phenotypic heterogeneity, we undertook single-cell transcriptomics analysis in triple-negative breast cancer (TNBC) to identify subpopulations in CSCs. We found a subpopulation of CSCs with ancestral features that is marked by FXYD domain–containing ion transport regulator 3 (FXYD3), a component of the Na⁺/K⁺ pump. Accordingly, FXYD3⁺ CSCs evolve and proliferate, while displaying traits of alveolar progenitors that are normally induced during pregnancy. Clinically, FXYD3⁺ CSCs were persistent during neoadjuvant chemotherapy, hence linking them to drug-tolerant persisters (DTPs) and identifying them as crucial therapeutic targets. Importantly, FXYD3⁺ CSCs were sensitive to senolytic Na⁺/K⁺ pump inhibitors, such as cardiac glycosides. Together, our data indicate that FXYD3⁺ CSCs with ancestral features are drivers of plasticity and chemoresistance in TNBC. Targeting the Na⁺/K⁺ pump could be an effective strategy to eliminate CSCs with ancestral and DTP features that could improve TNBC prognosis

Using "ghost front" to predict the arrival time and speed of CMEs at Venus and Earth

Using in-situ measurements and remote-sensing observations, we study two Coronal Mass Ejections (CMEs) that left the Sun on 13-14 June 2012 and impacted both Venus and Earth while the planets were in close radial alignment. The two CMEs generate multiple fronts in STEREO/HI images, which can also be observed in ‘J-map’ as bifurcated features. We present the ‘ghost front’ model to combine remote observations from STEREO/SECCHI and in-situ observations from the Wind and VEX spacecraft, and to derive the kinematics and propagation directions of the CMEs. By fitting the observations of multiple fronts to a kinematically evolving flux rope (KEFR) model and assuming the CMEs undergo deceleration through frictional drag with a steady-state solar wind, we confirm that the outer and inner fronts of the CMEs as detected in HI images are consistent with peaks in Thomson scattered light returned from the flank and nose of a single front for each CME. An interaction takes place between the CME-1 and CME-2 that can be observed in the HI-1 field of view before CME-1 encounters Venus. The multi-point in-situ observations of the shock-CME interaction event serve as further evidence of the interaction between CMEs. The arrival times calculated from the ghost-front model are within 2.5 hours of those observed at VEX and Wind. Our analysis indicates that ghost fronts could provide information about the longitudinally-extended shape of the CME in the field of view of HI-1, which can be used to improve the forecast of ICME arrival time at Earth

The dynamic evolution of multipoint interplanetary coronal mass ejections observed with BepiColombo, Tianwen-1, and MAVEN

We present two multipoint interplanetary coronal mass ejections (ICMEs) detected by the Tianwen-1 and Mars Atmosphere and Volatile Evolution spacecraft at Mars and the BepiColombo (0.56 au ∼0.67 au) upstream of Mars from 2021 December 5 to 31. This is the first time that BepiColombo is used as an upstream solar wind monitor ahead of Mars and that Tianwen-1 is used to investigate the magnetic field characteristics of ICMEs at Mars. The Heliospheric Upwind Extrapolation time model was used to connect the multiple in situ observations and the coronagraph observations from STEREO/SECCHI and SOHO/LASCO. The first fast coronal mass ejection event (∼761.2 km s−1), which erupted on December 4, impacted Mars centrally and grazed BepiColombo by its western flank. The ambient slow solar wind decelerated the west flank of the ICME, implying that the ICME event was significantly distorted by the solar wind structure. The second slow ICME event (∼390.7 km s−1) underwent an acceleration from its eruption to a distance within 0.69 au and then traveled with the constant velocity of the ambient solar wind. These findings highlight the importance of background solar wind in determining the interplanetary evolution and global morphology of ICMEs up to Mars distance. Observations from multiple locations are invaluable for space weather studies at Mars and merit more exploration in the future

Optimal error estimates to smooth solutions of the central discontinuous Galerkin methods for nonlinear scalar conservation laws

In this paper, we study the error estimates to sufficiently smooth solutions of the nonlinear scalar conservation laws for the semi-discrete central discontinuous Galerkin (DG) finite element methods on uniform Cartesian meshes. A general approach with an explicitly checkable condition is established for the proof of optimal L2 error estimates of the semi-discrete CDG schemes, and this condition is checked to be valid in one and two dimensions for polynomials of degree up to k = 8. Numerical experiments are given to verify the theoretical results

Three-Dimensional Parameters of the Earth-Impacting CMEs Based on the GCS Model

When a CME arrives at the Earth, it will interact with the magnetosphere, sometimes causing hazardous space weather events. Thus, the study of CMEs which arrived at Earth (hereinafter, Earth-impacting CMEs) has attracted much attention in the space weather and space physics communities. Previous results have suggested that the three-dimensional parameters of CMEs play a crucial role in deciding whether and when they reach Earth. In this work, we use observations from the Solar TErrestrial RElations Observatory (STEREO) to study the three-dimensional parameters of 71 Earth-impacting CMEs from the middle of 2008 to the end of 2012. We find that the majority Earth-impacting CMEs originate from the region of [30S,30N] × [40E,40W] on the solar disk; Earth-impacting CMEs are more likely to have a central propagation angle (CPA) no larger than half-angular width, a negative correlation between velocity and acceleration, and propagation time is inversely related to velocity. Based on our findings, we develop an empirical statistical model to forecast the arrival time of the Earth-impacting CME. Also included is a comparison between our model and the aerodynamic drag model

Predictive Capabilities of Corotating Interaction 2 Regions using STEREO and Wind in-situ observations

Solar wind stream interaction regions (SIRs) and corotating interaction regions (CIRs) can cause geomagnetic storms and change energetic particle environment, ionospheric composition on Earth. Therefore advanced warning of SIRs/CIRs is vital for mitigating the effect of space weather on critical infrastructures in modern society. Recently, several solar missions, e.g., Vigil mission (Luntama et al., 2020) and Solar Ring mission (Wang et al., 2020), that can be served as a space weather monitor, have been proposed. To evaluate the capabilities of these future missions of predicting SIRs/CIRs, the STEREO B spacecraft is used to investigate the correlation between SIRs/CIRs detected by STEREO B and Wind spacecraft. The correlation coeffcients of solar wind velocity in SIRs/CIRs are signi�ficantly higher than that of magnetic fi�eld intensity or plasma density. It indicates that the velocity structure of solar wind is more persistent than magnetic �field and ion density. By assuming the SIR/CIR structures are stable and ideal corotation, 58.9% of SIRs/CIRs in the STEREO-B CIR catalogue can be used to predict CIR arrival time in near-Earth space. With increasing longitudinal and latitudinal separations between STEREO-B and Wind, the percentage of accurately predicted CIRs decreases gradually from 100% to 20%. If the separation angle between STEREO-B and Wind is within 30 degrees in longitude and approximately plus/minus 5 degrees in latitude, more than 93.2% of SIRs/CIRs can be accurately predicted several days in advance. This demonstrates that a spacecraft situated 30 degrees trailing Earth in its orbit, can optimize our space weather-predicting capabilities for the Earth and lessen the risk of missing or false alarms" CIRs