ALBERT

Description: Author(s): R. Chen, J. F. Wang, Z. W. Ouyang, Z. Z. He, S. M. Wang, L. Lin, J. M. Liu, C. L. Lu, Y. Liu, C. Dong, C. B. Liu, Z. C. Xia, A. Matsuo, Y. Kohama, and K. Kindo Low-dimensional frustrated antiferromagnet is a good model system to study exotic quantum physics. Here we report the observation of half magnetization plateau and ferroelectricity which emerge simultaneously in the bond-alternating skew-chain compounds R 2 V 2 O 7 ( R = Ni , Co ) induced by high magnetic field... [Phys. Rev. B 98, 184404] Published Mon Nov 05, 2018

Description: Galaxies grow inefficiently, with only a small percentage of the available gas converted into stars each free-fall time. Feedback processes, such as outflowing winds driven by radiation pressure, supernovae, or supermassive black hole accretion, can act to halt star formation if they heat or expel the gas supply. We report a molecular outflow launched from a dust-rich star-forming galaxy at redshift 5.3, 1 billion years after the Big Bang. The outflow reaches velocities up to 800 kilometers per second relative to the galaxy, is resolved into multiple clumps, and carries mass at a rate within a factor of 2 of the star formation rate. Our results show that molecular outflows can remove a large fraction of the gas available for star formation from galaxies at high redshift.

Description: The curlometer was introduced to estimate the electric current density from four-point measurements in space; anticipating the realization of the four spacecraft Cluster mission which began full science operations in February 2001. The method uses Ampère's law to estimate current from the magnetic field measurements, suitable for the high conductivity plasma of the magnetosphere and surrounding regions. The accuracy of the method is limited by the spatial separation knowledge, accuracy of the magnetic field measurement and the relative scale size of the current structures sampled, but nevertheless has proven to be robust and reliable in many regions of the magnetosphere. The method has been applied successfully, and has been a key element, in studies of: the magnetopause currents; the magnetotail current sheet, and the ring current, as well as allowing other current structures such as flux tubes and field aligned currents to be determined. The method is also applicable to situations where less than four spacecraft are closely grouped or where special assumptions (particularly stationarity) can be made. In view of the new four-point observations of the MMS mission taking place now, which cover a dramatically different spatial regime, we comment on the performance, adaptability and lessons learnt from the curlometer technique. We emphasise the adaptability of the method, in particular to the new sampling regime offered by the MMS mission; thereby offering a tool to address open questions on small scale current structures.

Description: Least-squares reverse time migration (LSRTM) refines the seismic image toward true reflectivity by inversion. Its iterative nature and modeling capability enable the use of synthetic data to guide the preconditioning of input data. When the velocity contains errors, dynamic warping can be used to shift the input data and force the traveltime to be consistent with the imperfect migration velocity. A crosscorrelation-based confidence level is introduced to control the quality of dynamic warping for field data. The confidence level also is used as an inverse weighting to adaptively precondition the data residual. The adaptive preconditioning automatically balances data fitting in the shallow and deep and speeds up convergence in subsalt. Both synthetic and field data experiments based in the Gulf of Mexico show that the adaptive LSRTM can improve the image quality in subsalt effectively and efficiently. Within only a few iterations, the adaptive LSRTM suppresses the salt halo artifacts and increases the signal-to-noise ratio in poorly illuminated areas. It also improves the termination of sediments against salt boundaries and enhances subsalt image coherency. Compared with conventional RTM, the adaptive LSRTM image is more favorable to geologic interpretation.

Description: Abstract MESSENGER measurements taken during passes over Mercury's dayside hemisphere indicate that on 4 occasions the spacecraft remained in the magnetosheath even though it reached altitudes below 300 km. During these disappearing dayside magnetosphere (DDM) events, MESSENGER did not encounter the magnetopause until it was at very high magnetic latitudes, ~ 66 to 80o. These DDM events stand‐out with respect to their extremely high solar wind dynamic pressures, Psw ~ 140 to 290 nPa, and intense southward magnetic fields, Bz ~ ‐ 100 to ‐ 400 nT, measured in the magnetosheath. In addition, the bow shock was observed very close to the surface during these events with a subsolar altitude of ~ 1200 km. It is suggested that DDM events, which are closely associated with coronal mass ejections, are due to solar wind compression and/or reconnection‐driven erosion of the dayside magnetosphere. The very low altitude of the bow shock during these events strongly suggests that the solar wind impacts much of Mercury's sunlit hemisphere during these events. More study of these disappearing dayside events is required, but it is likely that solar wind sputtering of neutrals from the surface into the exosphere maximizes during these intervals.

Description: Abstract Traditionally, dipolarization front (DF) is a discontinuity at the leading edge of the high‐speed plasma jets, separating hot tenuous plasma from the denser ambient plasma. The particles behind the DF are usually hot population resulting from various heating and acceleration processes therein. Here, using Magnetospheric Multiscale (MMS) observations, we report that cold ions of ionospheric origin can be found behind the DFs. These cold ions move along the reconnected magnetic field lines directly from lobe during substorm, forming counter‐streaming cold ion flows behind the DFs. We find that cold ionospheric ions, as an additional population behind the DF, could increase ion density by ~50%. This indicates that the cold ions can change the gradients in the plasma density, such as the density‐driven instabilities near the DFs, and further affect the DF dynamics.

Description: Abstract The low‐latitude boundary layer (LLBL) plays an important role as a transition layer in coupling the magnetosheath and magnetosphere. Using high‐resolution Magnetospheric Multiscale data, we analyze the electron distributions in the inner region of the LLBL, during an active period of magnetic reconnection under southward interplanetary magnetic field. According to the measured electron energy anisotropy, we suggest that this inner LLBL can be divided into six sublayers corresponding to three types of magnetic field‐line topologies: (1) open magnetic field line topology from magnetosheath to southern magnetosphere, (2) open magnetic field line topology from magnetosheath to northern magnetosphere, and (3) reclosed magnetic field line topology. These different scenarios indicate that magnetic reconnection occurs at both northern and southern locations of the spacecraft and thus suggest that magnetic reconnection was active simultaneously at high and low latitude on the magnetopause, equatorward of the cusps. These results provide evidence within the LLBL for such multiple X‐line formation.

Description: According to a first-principles study of the transport properties of two thiolated anthracene-9,10-diono molecules sandwiching ethyl, a new method to induce molecular low bias negative differential resistance with multi-peaks for strong n - or p -type molecules is proposed. The anthracene-9,10-diono molecule shows strong n -type characteristics when in contact with Au and Ag electrodes via a thiolate. The multiple negative differential resistance effect originated from the molecule–electrode couple is different between Ag and Au electrodes. Our investigations may promise potential for applications in molecular devices with low power dissipation and multifunction in the future.

Description: The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above the well-mixed atmosphere, the layer of peak extreme ultraviolet heating and primary reservoir for atmospheric escape. In situ measurements of the upper atmosphere reveal previously unmeasured populations of neutral and charged particles, the homopause altitude at approximately 130 kilometers, and an unexpected level of variability both on an orbit-to-orbit basis and within individual orbits. These observations help constrain volatile escape processes controlled by thermosphere and ionosphere structure and variability.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bougher, S -- Jakosky, B -- Halekas, J -- Grebowsky, J -- Luhmann, J -- Mahaffy, P -- Connerney, J -- Eparvier, F -- Ergun, R -- Larson, D -- McFadden, J -- Mitchell, D -- Schneider, N -- Zurek, R -- Mazelle, C -- Andersson, L -- Andrews, D -- Baird, D -- Baker, D N -- Bell, J M -- Benna, M -- Brain, D -- Chaffin, M -- Chamberlin, P -- Chaufray, J-Y -- Clarke, J -- Collinson, G -- Combi, M -- Crary, F -- Cravens, T -- Crismani, M -- Curry, S -- Curtis, D -- Deighan, J -- Delory, G -- Dewey, R -- DiBraccio, G -- Dong, C -- Dong, Y -- Dunn, P -- Elrod, M -- England, S -- Eriksson, A -- Espley, J -- Evans, S -- Fang, X -- Fillingim, M -- Fortier, K -- Fowler, C M -- Fox, J -- Groller, H -- Guzewich, S -- Hara, T -- Harada, Y -- Holsclaw, G -- Jain, S K -- Jolitz, R -- Leblanc, F -- Lee, C O -- Lee, Y -- Lefevre, F -- Lillis, R -- Livi, R -- Lo, D -- Ma, Y -- Mayyasi, M -- McClintock, W -- McEnulty, T -- Modolo, R -- Montmessin, F -- Morooka, M -- Nagy, A -- Olsen, K -- Peterson, W -- Rahmati, A -- Ruhunusiri, S -- Russell, C T -- Sakai, S -- Sauvaud, J-A -- Seki, K -- Steckiewicz, M -- Stevens, M -- Stewart, A I F -- Stiepen, A -- Stone, S -- Tenishev, V -- Thiemann, E -- Tolson, R -- Toublanc, D -- Vogt, M -- Weber, T -- Withers, P -- Woods, T -- Yelle, R -- New York, N.Y. -- Science. 2015 Nov 6;350(6261):aad0459. doi: 10.1126/science.aad0459.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉CLaSP Department, University of Michigan, Ann Arbor, MI, USA. bougher@umich.edu. ; Laboratory for Atmospheric and Space Physics, University. of Colorado, Boulder, CO, USA. ; Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA. ; NASA/Goddard Space Flight Center, Greenbelt, MD, USA. ; Space Sciences Laboratory, University of California at Berkeley, Berkeley, CA, USA. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA. ; CNRS/Institut de Recherche en Astrophysique et Planetologie, Toulouse, France. University Paul Sabatier, Toulouse, France. ; Swedish Institute of Space Physics, Kiruna, Sweden. ; NASA/Johnson Space Center, Houston, TX, USA. ; National Institute of Aerospace, Hampton, VA, USA. ; Laboratoire Atmospheres, Milieux, Observations Spatiales /CNRS, Verrieres-le-Buisson, France. ; Department of Astronomy, Boston University, Boston, MA, USA. ; CLaSP Department, University of Michigan, Ann Arbor, MI, USA. ; Department of Physics and Astronomy, University of Kansas, Lawrence, KS, USA. ; Computational Physics, Springfield, VA, USA. ; Department of Physics, Wright State University, Fairborn, OH, USA. ; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA. ; Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA, USA. ; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Aichi, Japan. ; Naval Research Laboratory, Washington, DC, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26542579" target="_blank"〉PubMed〈/a〉