ALBERT

Description: The prediction of the background global solar wind is a necessary part of space weather forecasting. Several coronal and heliospheric models have been installed and/or recently upgraded at the Community Coordinated Modeling Center (CCMC), including the Wang-Sheely-Arge (WSA)-Enlil model, MHD-Around-a-Sphere (MAS)-Enlil model, Space Weather Modeling Framework (SWMF), and heliospheric tomography using interplanetary scintillation (IPS) data. Ulysses recorded the last fast latitudinal scan from southern to northern poles in 2007. By comparing the modeling results with Ulysses observations over seven Carrington rotations, we have extended our third-party validation from the previous near-Earth solar wind to mid-to-high latitudes, in the same late declining phase of solar cycle 23. Besides visual comparison, we have quantitatively assessed the models’ capabilities in reproducing the time series, statistics, and latitudinal variations of solar wind parameters for a specific range of model parameter settings, inputs, and grid configurations available at CCMC. The WSA-Enlil model results vary with three different magnetogram input. The MAS-Enlil model captures the solar wind parameters well, despite its underestimation of the speed at mid-to-high latitudes. The new version of SWMF misses many solar wind variations probably because it uses lower grid resolution than other models. The IPS-Tomography cannot capture the latitudinal variations of solar wind well yet. Because the model performance varies with parameter settings which are optimized for different epochs or flow states, the performance metric study provided here can serve as a template that researchers can use to validate the models for the time periods and conditions of interest to them.

Description: Article LiTi 2 O 4 is the only known spinel oxide superconductor, but systematic investigations of its transport properties have been lacking so far. Here, the authors' analyses detect an unusual magnetoresistance, revealing spin-orbit fluctuations similar to those in high-temperature superconductors. Nature Communications doi: 10.1038/ncomms8183 Authors: K. Jin, G. He, X. Zhang, S. Maruyama, S. Yasui, R. Suchoski, J. Shin, Y. Jiang, H. S. Yu, J. Yuan, L. Shan, F. V. Kusmartsev, R. L. Greene, I. Takeuchi

Description: Multiple coronal and heliospheric models have been recently upgraded at the Community Coordinated Modeling Center (CCMC), including the Wang-Sheely-Arge (WSA)-Enlil model, MHD-Around-a-Sphere (MAS)-Enlil model, Space Weather Modeling Framework (SWMF), and heliospheric tomography using interplanetary scintillation data. To investigate the effects of photospheric magnetograms from different sources, different coronal models, and different model versions on the model performance, we run these models in 10 combinations. Choosing 7 Carrington rotations in 2007 as the time window, we compare the modeling results with the OMNI data for near-Earth space environment during the late declining phase of solar cycle 23. Visual comparison is proved to be a necessary addition to the quantitative assessment of the models’ capabilities in reproducing the time series and statistics of solar wind parameters. The MAS-Enlil model captures the time patterns of solar wind parameters better while the WSA-Enlil model matches with the time series of normalized solar wind parameters better. Models generally overestimate slow wind temperature, underestimate fast wind temperature and magnetic field. Using improved algorithms, we have identified magnetic field sector boundaries (SBs) and slow-to-fast stream interaction regions (SIRs) as focused structures. The success rate of capturing them and the time offset vary largely with models. For this quiet period, the new version of MAS-Enlil model works best for SBs, while heliospheric tomography works best for SIRs. The new version of SWMF with more physics added needs more development. General strengths and weaknesses for each model are diagnosed to provide an unbiased reference to model developers and users.

Description: Observations of interplanetary scintillation (IPS) provide a set of data that are used in estimating the solar wind parameters with reasonably good accuracy. Various tomography techniques have been developed to deconvolve the line-of-sight integration effects ingrained in observations of IPS to improve the accuracy of solar wind reconstructions. Among those, the time-dependent tomography developed at the University of California, San Diego (UCSD) is well-known for its remarkable accuracy in reproducing the solar wind speed and density at Earth by iteratively fitting a kinematic solar wind model to observations of IPS and near-Earth spacecraft measurements. However, the kinematic model gradually breaks down as the distance from the Sun increases beyond the orbit of Earth. Therefore, it would be appropriate to use a more sophisticated model, such as a magnetohydrodynamics (MHD) model, to extend the kinematic solar wind reconstruction beyond the Earth's orbit and to the outer heliosphere. To testthe suitability of this approach, we use boundary conditions provided by the UCSD time-dependent tomography to propagate the solar wind outward in a MHD model and compare the simulation results with in situ measurements and also with the corresponding kinematic solution. Interestingly, we find notable differences in proton radial velocity and number density at Earth and various locations in the inner heliosphere between the MHD results and both the in situ data and thekinematic solution. For example at 1 AU, the MHD velocities are generally larger than the spacecraft data by up to 150 km s −1 , and the amplitude of density fluctuations is also markedly larger in the MHD solution. We show that the MHD model can deliver more reasonable results at Earth with an ad hoc adjustment of the inner boundary values. However, we conclude that the MHD model using the inner boundary conditions derived from kinematic simulations has little chance to match IPS and textitin situ data as well as the kinematic model does unless it too is iteratively fit to the observational data and measurements.

Description: The UCSD interplanetary scintillation (IPS) time-dependent kinematic 3D-reconstruction technique has been used and expanded upon for over a decade, to provide predictions of heliospheric solar wind parameters. These parameters include global reconstructions of velocity, density and also (through potential field modeling and extrapolation upward from the solar surface) radial and tangential interplanetary magnetic fields. Time-dependent results can be extracted at any solar distance within the reconstructed volume and are now being exploited as inner-boundary values to drive the ENLIL 3D-MHD model in near real-time. The advantage of this coupled system is that it uses the more complete physics of 3D-MHD modeling to provide an automatic prediction of coronal mass ejections (CMEs) and solar wind stream structures several days prior to their arrival at Earth without employing coronagraph observations. Here we explore, with several examples, the current differences between the IPS real-time kinematic analyses and those from the ENLIL 3D-MHD modeling using IPS-derived real-time boundaries. Future possibilities for this system include incorporating many different worldwide IPS stations as input to the remote sensing analysis using ENLIL as a kernel in the iterative 3D-reconstructions.

Description: High-speed jet responses in the polar solar wind are enigmatic. Here, we measure a jet response that emanates from the southern polar coronal hole on 17 June 2011 at the extreme speed of over 1200 km/s. This response was recorded from the Sun-Earth line in SDO/AIA and LASCO/C2 and both STEREO EUVI and COR2 coronagraphs when the three spacecraft were situated ~90° from one another. These certify the coronal 3D location of the response that is associated with an existing solar plume structure, and show its high speed to distances of over 14 Rs. This jetting is associated with magnetic flux changes in the polar region as measured by the SDO/HMI instrumentation over a period of several hours. The fastest coronal response observed can be tracked to a time near the period of greatest flux changes, and to the onset of the brightest flaring in AIA. This high-speed response can be tracked directly as a small patch of outward-moving brightness in coronal images as in Yu et al. [2014] where three slower events were followed from the perspective of Earth. This accumulated jet response has the largest mass and energy we have yet seen in 3D reconstructions from Solar Mass Ejection Imager (SMEI) observations, and its outward motion is certified for the first time using interplanetary scintillation (IPS) observations. This jet response is surrounded by similar high-speed patches but these are smoothed out in Ulysses polar measurements, we speculate about how these dynamic activities relate to solar wind acceleration.

Description: This article investigates the use of two different types of National Solar Observatory magnetograms and two different coronal field modeling techniques over ten years. Both the “open-field” Current Sheet Source Surface (CSSS) and a “closed-field” technique using CSSS modeling are compared. The University of California, San Diego tomographic modeling, using interplanetary scintillation (IPS) data from Japan, provides the global velocities to extrapolate these fields outward, which are then compared with fields measured in situ near Earth. Although the open-field technique generally gives a better result for radial and tangential fields, we find that a portion of the closed extrapolated fields measured in situ near Earth comes from the direct outward mapping of these fields in the low solar corona. All three closed-field components are non-zero at 1 AU, and are compared with the appropriate magnetometer values. A significant positive correlation exists between these closed-field components and the in-situ measurements over the last ten years. We determine that a small fraction of the static low-coronal component flux, that includes the Bn (north-south) component, regularly escapes from closed-field regions. The closed-field flux fraction varies by about a factor of three from a mean value during this period, relative to the magnitude of the field components measured in situ near Earth, and maximizes in 2014. This implies that a relatively more efficient process for closed-flux escape occurs near solar maximum. We also compare and find that the popular Potential Field Source Surface- and CSSS-model closed fields are nearly identical in sign and strength.

Description: Author(s): M. C. Wang, H. S. Yu, J. Xiong, Y.-F. Yang, S. N. Luo, K. Jin, and J. Qi By applying ultrafast optical spectroscopy to electron-doped La 1.9 Ce 0.1 CuO 4 ± δ , we discern a bosonic mode of electronic origin and provide the evolution of its coupling with the charge carriers as a function of temperature. Our results show that it has the strongest coupling strength near T c and can ... [Phys. Rev. B 97, 155157] Published Fri Apr 27, 2018

Description: Androgen receptor-mediated apoptosis in bovine testicular induced pluripotent stem cells in response to phthalate esters Cell Death and Disease 4, e907 (November 2013). doi:10.1038/cddis.2013.420 Authors: S-W Wang, S S-W Wang, D-C Wu, Y-C Lin, C-C Ku, C-C Wu, C-Y Chai, J-N Lee, E-M Tsai, C-LS Lin, R-C Yang, Y-C Ko, H-S Yu, C Huo, C-P Chuu, Y Murayama, Y Nakamura, S Hashimoto, K Matsushima, C Jin, R Eckner, C-S Lin, S Saito & K K Yokoyama