bluuebunny/crossref_metadata_2025_split huggingface dataset:
APOGEE: the Sloan Digital Sky Survey Apache Point Observatory Galactic Evolution Experiment. Insights into the Galactic Disk: A Review
Authors: Holtzman Jon A. , Hasselquist Sten ,   the SDSS-IV/APOGEE-2 collaboration
Published: August 2018

AbstractThe SDSS Apache Point Observatory Galactic Evolution Experiment (APOGEE) has collected high resolution near-IR spectra for several hundred thousand stars throughout the Milky Way. We review some of the results related to chemistry of stars in the disk, where APOGEE has a particular advantage by virtue of being able to work in more obscured areas. The ability to measure carbon and nitrogen abundances in giants in the near-IR provides insight into stellar ages. We summarize results on the variation of mean metallicity, metallicity distribution functions, and the [α/Fe]–[Fe/H] relation across the Galactic disk, as well as results on the structural parameters in mono-abundance populations. Many of these results suggest that radial migration has played a significant role in the Galactic disk. It may be possible to disentangle radial mixing using multi-element abundance patterns.
Investigation on fundamental plane of open clusters
Authors: Pang Xiao-Ying , Lin Chien-Cheng 
Published: August 2018

AbstractThe fundamental plane (FP) is the relation between the surface brightness (I), velocity dispersion (σ) and radius (R). The tilt of FP from the virial plane (R = σ2 I) not only tells the dynamical states of the system but also its formation and evolution. We motivate to looking for an FP in Galactic open clusters (OCs). To form a sample of OCs, we access the most recent DR 14 data from the SDSS/APOGEE2 and the Gaia-ESO survey. Membership of stars is determined via radial velocity and metallicity, plus star’s location in the color-magnitude diagram. Besides the velocity dispersion (σrv) obtained from SDSS/APOGEE2 &amp; Gaia-ESO, the average surface brightness (IKs), and apparent radii (r2) of OCs are taken from known OC catalog. A weak relation is found: log(r2) ∝ -0.34 * log(σ) - 0.08 * IKs. An implication of this FP needs further investigation.
The RAdial Velocity Experiment: preparing the 6th Data Release chemical abundances with GAUGUIN
Authors: Guiglion Guillaume ,   THE RAVE COLLABORATION
Published: August 2018

AbstractIn the context of the Radial Velocity Experiment (RAVE, Steinmetz et al. 2006), we present chemical abundances derived with the pipeline GAUGUIN. Based of 520 701 RAVE stars with medium resolution (R~7 500) spectra and stellar atmospheric parameters of the fifth Data Release, the analysis is performed around the infrared Ca-triple domain for 6 chemical elements: Mg, Ni, Si, Ti, Fe and Al. We discuss here the reliability of the chemical abundances provided by GAUGUIN, and the implications for the future Data Release 6 of the RAVE Survey. We also present elemental abundance patterns of Milky Way components based of kinematical criteria.
On The Metal-poor non-Sagittarius Globular Cluster NGC 5053: Orbit, Mg, Al, and Si
Authors: Tang Baitian 
Published: August 2018

AbstractMetal-poor globular clusters (GCs) show intriguing Al-Mg and Si-Al correlations, which are important clues to decipher the multiple population phenomenon. NGC 5053 is one of the most metal-poor GCs, and has been suggested to be associated with the Sagittarius dwarf galaxy (Sgr), due to its similar location and radial velocity with one of the Sgr arms. In this work, we simulate the orbit of NGC 5053, and argue against the connection between Sgr and NGC 5053. Meanwhile, Mg, Al, and Si spectral lines, which are difficult to detect in the optical spectra, have been detected in the near-infrared APOGEE spectra. We use three different sets of stellar parameters and codes to derive the Mg, Al, and Si abundances, and we always see a large Al variation, and a substantial Si enhancement. Comparing with other metal-poor GCs, we suggest metallicity may not be the only parameter that controls the multiple populations.
Galactic Phylogenetics
Authors: Jofré Paula , Das Payel 
Published: August 2018

AbstractPhylogenetics is a widely used concept in evolutionary biology. It is the reconstruction of evolutionary history by building trees that represent branching patterns and sequences. These trees represent shared history, and it is our contention that this approach can be employed in the analysis of Galactic history. In Galactic archaeology the shared environment is the interstellar medium in which stars form and provides the basis for tree-building as a methodological tool. Using elemental abundances of solar-type stars as a proxy for DNA, we built such an evolutionary tree to study the chemical evolution of the solar neighbourhood and published in Jofré15 et al. (2017). In this proceeding we summarise these results and discuss future prospects.
Probing Galactic Chemical Evolution with J-PLUS Photometry
Authors: Whitten Devin D. , Placco Vinicius M. , Beers Timothy C. , Clark Spencer , Ederoclite Alessandro , de Oliveira Cláudia Mendes 
Published: August 2018

AbstractNarrow-band photometric surveys, such as the Javalambre Photometric Local Universe Survey (J-PLUS), provide not only a means of pre-selection for high-resolution follow-up, but open a new era of precision photometric stellar parameter determination. Using a family of machine learning algorithms known as Artificial Neural Networks (ANNs), we have obtained photometric estimates of effective temperature (Teff) and metallicity ([Fe/H]) across a wide parameter range of temperature and metallicity (4000 &lt; Teff &lt;7000 K; −3.5 &lt;[Fe/H]&lt;0.0) for a number of stars in the J-PLUS Early Data Release. With this methodology, we expect to increase the number of known Carbon-enhanced Metal-poor (CEMP; [C/Fe]&gt;+0.7) stars by several orders of magnitude, as well as constrain the metallicity distribution function of the Milky Way Halo system.
Constructing Mars: Concrete and Energy Production From Serpentinization Products
Authors: Scott Allan N. , Oze Christopher 
Published: August 2018

AbstractIn situ building materials and energy resources are necessary for the long‐term human habitation of Mars. Olivine ((Mg,Fe)2SiO4) is a regionally abundant mineral on Mars and may potentially serve both purposes. Here we assess olivine hydrolysis (i.e., serpentinization) and related products including magnesite (MgCO3) as a means to produce a Mg‐based cement and molecular hydrogen (H2) as an energy resource. Magnesium oxide (MgO) may be derived from Mg(OH)2 dehydration or calcination (i.e., thermal decomposition) of MgCO3. In laboratory experiments, Mg‐based concrete using MgO achieved a compressive strength in excess of 20 MPa. Serpentinization‐related H2 gas concentrations increased with increasing temperature (20 to 50 °C) and decreasing olivine particle size reaching a maximum H2 production rate of 4.73 μmol g−1 day−1, 3 orders of magnitude greater than previously observed. Results from this study indicate that serpentinization and related products serve as a viable pathway for both concrete and fuel production on Mars with minimal energy expenditure and primarily constrained to the availability of water. Moreover, this process would work equally as well on Earth and has significant potential to decrease global industrial CO2 emissions.
Physically Accurate Large Dynamic Range Pseudo Moments for the MMS Fast Plasma Investigation
Authors: Barrie A. C. , da Silva D. , Elkington S. , Sternovsky Z. , Rager A. C. , Gershman D. J. , Paterson W. R. , Dorelli J. C. , Giles B. 
Published: August 2018

The Fast Plasma Investigation onboard the Magnetospheric Multiscale (MMS) mission captures full‐sky particle data over a range of 10 eV to 30 keV every 30 ms for electrons and 150 ms for ions. Only about 5% of the count data at this time resolution are sent to the ground due to telemetry limitations; however, a complete set of onboard trigger terms are sent due to their small data volume. These trigger terms are composed of simplified integrals that scale proportionally to plasma moments. They were initially conceived as a mechanism to rank scientific data for priority downlink; however, they can be adapted to represent pseudo moment quantities that are accurate to within several percent of fully corrected plasma moments. Tuning the dynamic range per plasma region and correcting via a trained neural network allow for far greater accuracy than previous missions. Corrections are performed based on statistical sampling of data from the first MMS day side pass. The corrections are validated by comparing pseudo moments to a published event showcasing detection of kinetic Alfvén waves. Physically accurate pseudo plasma moment quantities are available for the entirety of the MMS prime science regions, and can be a valuable asset for future scientific analysis of the MMS data repository.
Enhancement of the Jovian Magnetospheric Plasma Circulation Caused by the Change in Plasma Supply From the Satellite Io
Authors: Tsuchiya F. , Yoshioka K. , Kimura T. , Koga R. , Murakami G. , Yamazaki A. , Kagitani M. , Tao C. , Suzuki F. , Hikida R. , Yoshikawa I. , Kasaba Y. , Kita H. , Misawa H. , Sakanoi T. 
Published: August 2018

AbstractThe innermost Galilean satellite, Io, supplies a large amount of volcanic gasses to the Jovian magnetosphere. The fast rotation of Jupiter and the outward transport of ionized gasses are responsible for forming a huge and rotationally dominant magnetosphere. The plasma supply from the satellite has a key role in the characterization of the Jovian magnetosphere. In fact, significant variations of the plasma population in the inner magnetosphere caused by the volcanic eruptions in Io were found in early 2015, using a continuous data set of the Io plasma torus obtained from an extreme ultraviolet spectroscope onboard the Hisaki satellite. The time evolution of the Io plasma torus radial distribution showed that the outward transport of plasma through 8 RJ from Jupiter was enhanced for approximately 2 months (from the end of January to the beginning of April 2015). Intense short‐lived auroral brightenings––which represent transient energy releases in the outer part of the magnetosphere—occurred frequently during this period. The short‐lived auroral brightenings accompanied well‐defined sporadic enhancements of the ion brightness in the plasma torus, indicating a rapid inward transport of energy from the outer part of the magnetosphere and the resultant enhancement of hot electron population in the inner magnetosphere. This evidently shows that the change in a plasma source in the inner magnetosphere affects a large‐scale radial circulation of mass and energy in a rotationally dominant magnetosphere.
Solar Cycle Response of CO2 Over the Austral Winter Mesosphere and Lower Thermosphere Region
Authors: Salinas Cornelius Csar Jude H. , Chang Loren C. , Liang Mao‐Chang , Qian Liying , Yue Jia , Lee Jae N. , Russell James , Mlynczak Martin , Wu Dong L. 
Published: August 2018

AbstractThis work uses Sounding of the Atmosphere using Broadband Emission Radiometry CO2 data from 2002 to 2015 and Specified Dynamics‐Whole Atmosphere Community Climate Model (SD‐WACCM) outputs from 1979 to 2014 to show, for the first time, the solar cycle response of CO2 in the Austral winter mesosphere and lower thermosphere region. Both Sounding of the Atmosphere using Broadband Emission Radiometry and SD‐WACCM show that CO2 experiences a decrease during solar maximum throughout the Austral winter mesosphere and lower thermosphere region. This work highlights the regions where CO2 experiences its strongest and weakest solar cycle responses as modeled by SD‐WACCM. The region with the strongest solar cycle response experiences around 5% reduction in CO2 between solar maximum and solar minimum. The region with weakest solar cycle response experiences less than 1% reduction in CO2 between solar maximum and solar minimum. It is shown that the region of the strongest CO2 response is driven by photodissociation, downwelling, and reduced eddy diffusion. On the other hand, the region of the weakest CO2 response is driven by the opposing effects of photodissociation and enhanced eddy diffusion. This is the first work to show that the solar cycle could affect the Austral winter lower thermosphere circulation and eddy diffusion processes. These anomalies in the lower thermospheric circulation and eddy diffusion are found to be related to the solar cycle response in the Austral winter mesosphere wave‐mean flow dynamics. This work therefore concludes that the solar cycle affects lower thermospheric CO2 via modulations of the lower thermospheric circulation and eddy diffusion processes.
Dissolved Lead in the East China Sea With Implications for Impacts of Marginal Seas on the Open Ocean Through Cross‐Shelf Exchange
Authors: Jiang Shuo , Zhang Jing , Zhang Ruifeng , Xue Yun , Zheng Wei 
Published: August 2018

AbstractThe distribution of lead (Pb) in the ocean is influenced by human activities. During a cruise in the East China Sea (ECS) in August 2013, we investigated six representative stations and gave the first systematic description of dissolved lead (DPb) distributions after the phasing out of leaded gasoline in China. The DPb concentration in the ECS ranged from 23.8 to 96.7 pmol/kg, with the highest concentrations observed at the surface of the middle shelf, while the lowest concentrations were determined to be in deep samples collected at the shelf break. Vertical profiles of DPb vary with geographic locations, seawater turbidity, hypoxic conditions, atmospheric deposition, and hydrographic regimes. As one of the most important western boundary currents, Kuroshio receives an additional 10–20 pmol/kg of DPb from the ECS shelf through a cross‐shelf exchange process, and approximately (1.1–1.7) × 109 g/yr of DPb was exported through the shelf break area, which will directly join the North Pacific circulation based on a preliminary box model. In addition, the ECS shelf exported another 1.4 × 109 g/yr of DPb from the Tsushima/Korea Strait, which has the potential to influence the northwestern Pacific Ocean as well as the Sea of Japan/East Sea. A residence time of 2–3 months for DPb in the ECS was inferred.
Locating Preliminary Breakdown Pulses in Positive Cloud‐to‐Ground Lightning
Authors: Wu Ting , Wang Daohong , Takagi Nobuyuki 
Published: August 2018

AbstractThis paper provides the first concrete evidence that preliminary breakdown (PB) pulses of either polarity in positive cloud‐to‐ground (+CG) lightning are produced by negative leaders. Three‐dimensional location results of PB pulses in 46 +CG flashes are analyzed. The majority (40) of the +CG flashes started with positive PB pulses (+PBPs), the same polarity as the positive return stroke. Location results showed that +PBPs were produced by leaders propagating upward, which were determined to be negative leaders based on PB pulse polarities. Similarly, for the negative PB pulses (−PBPs) found in six +CG flashes, location results showed that they were produced by leaders propagating downward, and we determined that these were also negative leaders. Upward negative leaders producing +PBPs in +CG lightning are very similar to those in intracloud lightning. They usually propagate upward before turning in a horizontal direction. Downward negative leaders producing −PBPs in +CG lightning are more complicated. They usually move back upward after a period of downward propagation. Positive leaders could not be detected, but their possible propagations are analyzed along with possible charge structures for different types of PB pulses. We also demonstrate that PB pulse studies based on single‐site records are potentially unreliable.
Penetrative Convection in Super‐Earth Planets: Consequences of MgSiO3 Postperovskite Dissociation Transition and Implications for Super‐Earth GJ 876 d
Authors: Shahnas M. H. , Pysklywec R. N. , Yuen D. A. 
Published: August 2018

AbstractTheoretical studies suggest that MgSiO3 postperovskite dissociates into MgO and MgSi2O5 at 0.9 TPa, and MgSi2O5 dissociates into MgO and SiO2 at 2.1 TPa, both with negative Clapeyron slopes. In addition, unlike a conventional view, the viscosity in super‐Earth planets is proposed to decrease with pressure when pressure exceeds ~0.1 TPa. Employing 2‐D‐axisymmtric and 3‐D‐spherical control volume compressible models, we perform an investigation on the impact of deep mantle dissociation of postperovskite into oxides, in conjunction with variations of the mantle viscosity, on the degree of the deep mantle layering, and the consequences of this layering on cooling of the rocky planets similar to super‐Earth GJ 876 d. Small‐scale convection in a layer of thickness ~500 km from which penetrative plumes originate, develops above the core‐mantle boundary (CMB) in the models for which the viscosity at the dissociation transition depth and below is less than ~1023 Pa·s. Due to the buffering effect of this deep mantle layering, while the mean mantle temperature above the layer decreases, resulting in a viscosity increase above the layer, it increases in the layered region above the CMB. This leads to a further reduction in viscosity at the bottom of the mantle. The effect is enhanced with increasing the CMB temperature and the contrast in thermal expansivity. The cooling rate of the planet decreases in the layered models due to the buffering effect of this deep mantle transition, as well as the influence of the viscosity increase above transition depth.
A Methodology for Anomaly Coupling in Climate Simulation
Authors: Toniazzo Thomas , Koseki Shunya 
Published: August 2018

AbstractWe demonstrate a new methodology for anomaly coupling in general circulation models on the basis of simulations with the Norwegian Earth System Model. A correction is applied to the sea surface temperature (SST) and wind‐stress climatology of the coupled model during the integration in such a way as to match the observed climatology. The correction is found iteratively by updating the model climatology at every time step, allowing the simulation to converge toward a self‐consistent surface climatology close to that observed, with minimal impact on the simulation of variability. Our approach differs from the traditional way of anomaly coupling that employs fixed model climatologies from stand‐alone model runs to correct the model's climatological mean state. While the atmosphere and ocean components are forced by inconsistent surface fluxes in our methodology, the inconsistency becomes smaller as the simulated climatology converges toward the observations after about 30 years. Our methodology achieves a significant reduction in the systematic SST biases of the coupled model climatology, especially over the tropical and subtropical oceans. Associated with the reduction of tropical SST biases, the double‐ Inter‐tropical Convergence Zone (ITCZ) problem is mitigated, the seasonal cycle is well represented, and some aspects of coupled variability such as the El Nino Southern Oscillation are improved. The methodology can be extended in a way that ensures global energy conservation without affecting the improvements in the simulated climatology and may be thus applied for prediction purposes.
Astronomically Driven Variations in Depositional Environments in the South Atlantic During the Early Cretaceous
Authors: Behrooz L. , Naafs B. D. A. , Dickson A. J. , Love G. D. , Batenburg S. J. , Pancost R. D. 
Published: August 2018

AbstractThe extent and persistence of anoxia in the South Atlantic Ocean during its early opening phase in the Early Cretaceous is not well constrained, hindering a holistic understanding of the processes and mechanisms that drive past changes in water column redox conditions, as well as the impacts of such changes on marine ecosystems. Here we provide high‐resolution geochemical records from Deep Sea Drilling Project Site 364 that document variations in redox conditions, chemocline depth, marine productivity, and marine ecosystem dynamics in the northern South Atlantic during the Aptian. We show that many of these parameters varied across discrete sedimentary cycles expressed in the Deep Sea Drilling Project 364 succession. Our data indicate that during the initial stages of basin development, anoxic and euxinic conditions were prevalent and occasionally extended into the upper water column. However, strong cyclicity in sedimentological and geochemical parameters imply that the anoxia/euxinia was not a persistent state. We argue that the water column redox conditions during the Aptian were driven by changes in the hydrological cycle, induced by variations in astronomical forcing. We suggest that the episodically amplified hydrological cycle not only enhanced nutrient availability and marine productivity, but might also have caused density‐driven upper ocean stratification. The presence of black shales of similar age in other ocean basins suggests that this mechanism is broadly important for the formation of Early Cretaceous organic‐rich successions.
Structure of the essential peptidoglycan amidotransferase MurT/GatD complex from Streptococcus pneumoniae
Authors: Morlot Cécile , Straume Daniel , Peters Katharina , Hegnar Olav A. , Simon Nolwenn , Villard Anne-Marie , Contreras-Martel Carlos , Leisico Francisco , Breukink Eefjan , Gravier-Pelletier Christine , Le Corre Laurent , Vollmer Waldemar , Pietrancosta Nicolas , Håvarstein Leiv Sigve , Zapun André 
Published: August 2018

AbstractThe universality of peptidoglycan in bacteria underlies the broad spectrum of many successful antibiotics. However, in our times of widespread resistance, the diversity of peptidoglycan modifications offers a variety of new antibacterials targets. In some Gram-positive species such as Streptococcus pneumoniae, Staphylococcus aureus, or Mycobacterium tuberculosis, the second residue of the peptidoglycan precursor, D-glutamate, is amidated into iso-D-glutamine by the essential amidotransferase MurT/GatD complex. Here, we present the structure of this complex at 3.0 Å resolution. MurT has central and C-terminal domains similar to Mur ligases with a cysteine-rich insertion, which probably binds zinc, contributing to the interface with GatD. The mechanism of amidation by MurT is likely similar to the condensation catalyzed by Mur ligases. GatD is a glutaminase providing ammonia that is likely channeled to the MurT active site through a cavity network. The structure and assay presented here constitute a knowledge base for future drug development studies.
Plant and animal functional diversity drive mutualistic network assembly across an elevational gradient
Authors: Albrecht Jörg , Classen Alice , Vollstädt Maximilian G. R. , Mayr Antonia , Mollel Neduvoto P. , Schellenberger Costa David , Dulle Hamadi I. , Fischer Markus , Hemp Andreas , Howell Kim M. , Kleyer Michael , Nauss Thomas , Peters Marcell K. , Tschapka Marco , Steffan-Dewenter Ingolf , Böhning-Gaese Katrin , Schleuning Matthias 
Published: August 2018

AbstractSpecies’ functional traits set the blueprint for pair-wise interactions in ecological networks. Yet, it is unknown to what extent the functional diversity of plant and animal communities controls network assembly along environmental gradients in real-world ecosystems. Here we address this question with a unique dataset of mutualistic bird–fruit, bird–flower and insect–flower interaction networks and associated functional traits of 200 plant and 282 animal species sampled along broad climate and land-use gradients on Mt. Kilimanjaro. We show that plant functional diversity is mainly limited by precipitation, while animal functional diversity is primarily limited by temperature. Furthermore, shifts in plant and animal functional diversity along the elevational gradient control the niche breadth and partitioning of the respective other trophic level. These findings reveal that climatic constraints on the functional diversity of either plants or animals determine the relative importance of bottom-up and top-down control in plant–animal interaction networks.