bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic fields along the pre-main sequence: new magnetic field measurements of Herbig Ae/Be stars using high-resolution HARPS spectropolarimetry
Authors: Järvinen S. P. , Hubrig S. , Schöller M. , Ilyin I. 
Published: March 2020

AbstractHerbig Ae/Be-type stars are analogs of T Tauri stars at higher masses. Since the confirmation of magnetospheric accretion using Balmer and sodium line profiles in the Herbig Ae star UX Ori, a number of magnetic studies have been attempted, indicating that about 20 Herbig Ae/Be stars likely have globally organized magnetic fields. The low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. The obtained density distribution of the root mean square longitudinal magnetic field values revealed that only a few stars have magnetic fields stronger than 200 G, and half of the sample possesses magnetic fields of about 100 G or less. We report on the results of our analysis of a sample of presumably single Herbig Ae/Be stars based on recent observations obtained with HARPSpol attached to ESO’s 3.6m telescope. Knowledge of the magnetic field structure combined with the determination of the chemical composition are indispensable to constrain theories on star formation and magnetospheric accretion in intermediate-mass stars. As of today, magnetic phase curves have been obtained only for two Herbig Ae/Be stars, HD 101412 and V380 Ori.
Eclipses and the Earth’s Rotation
Authors: Stephenson F. R. , Morrison L. V. , Hohenkerk C. Y. 
Published: March 2020

AbstractAnalysis of historical records of eclipses of the Sun and Moon between 720 BC and AD 1600 gives a measure of the time difference, TT − UT = ΔT. The first derivative in time along a smooth curve fitted to the values of Δ T measures the changes in the length of the day (lod). The average rate of change of the lod is found to be significantly less than that expected on the basis of tidal friction. Fluctuations on a time-scale of centuries to millennia are mainly attributed to the effects of post-glacial uplift and core-mantle coupling.
Changes in the Unchangeable: Simulation of Transient Astronomical Phenomena with Stellarium
Authors: Zotti Georg , Wolf Alexander 
Published: March 2020

AbstractThe open-source desktop planetarium Stellarium has become very popular in astronomical education and outreach. Our recent changes aim for its applicability in historical and archaeoastronomical simulation contexts. Apart from visualizing the seemingly perpetual regular motions of the celestial bodies, it can be used to visualize and demonstrate historical solar and lunar eclipses, historical and present comets, meteors, and also novae and supernovae.
Go beyond radial gradient: azimuthal variations of ISM abundance in 3D
Authors: Ho I-Ting 
Published: March 2020

AbstractUsing 3D spectroscopy data from the TYPHOON Project (PI: B. Madore), I show convincing observational evidence that the ISM oxygen abundance traced by HII regions presents systematic azimuthal variations in NGC 1365 and NGC 2997. I discuss a possible physical origin and on-going efforts to explore the prevalence and cause of such variations.
Metallicity gradients in M31, M33, NGC 300, and Milky Way using Argon abundances
Authors: Flores-Durán Sheila N. , Peña Miriam 
Published: March 2020

AbstractWe studied Planetary Nebulae (PNe) metallicity gradients using Ar abundances. We compared them with H ii regions in the galaxies of the local universe M 31, M 33, NGC 300 and in the Milky Way. Galactocentric radio (RG) and chemical abundances were collected from the literature, carefully selecting an homogeneous sample for each galaxy. In these galaxies, metallicity gradients computed with PNe abundances are flatter than those of H ii regions.
Magnetism in the Square Kilometre Array Era
Authors: Mao S. A. 
Published: March 2020

AbstractThe unprecedented sensitivity, angular resolution and broad bandwidth coverage of Square Kilometre Array (SKA) radio polarimetric observations will allow us to address many long-standing mysteries in cosmic magnetism science. I will highlight the unique capabilities of the SKA to map the warm hot intergalactic medium, reveal detailed 3-dimensional structures of magnetic fields in local galaxies and trace the redshift evolution of galactic magnetic fields.
On long-duration 3D simulations of stellar convection using ANTARES
Authors: Kupka F. , D.  , Fabbian  , D.  , Krüger  , N.  , Kostogryz  , L.  , Gizon  
Published: March 2020

AbstractWe present initial results from three-dimensional (3-D) radiation hydrodynamical simulations for the Sun and targeted Sun-like stars. We plan to extend these simulations up to several stellar days to study p-mode excitation and damping processes. The level of variation of irradiance on the time scales spanned by our 3-D simulations will be studied too. Here we show results from a first analysis of the computational data we produced so far.
Passband reconstruction from photometry
Authors: Weiler Michael , Jordi Carme , Carrasco Josep Manel , Fabricius Claus 
Published: March 2020

AbstractPhotometric passbands are usually characterised through laboratory measurements and once in operations they are refined with true observations of reference sources with known spectral energy distribution. This paper revises the methods to determine those passbands and discusses the limitations encountered. The passbands are not fully constrained by the reference sources used and the method presented here allows to evaluate which is the constrained and the unconstrained component of the passband.
The Calibration of the UVIT Detectors for the ASTROSAT Observatory
Authors: Leahy Denis , Postma J. , Hutchings J. B. , Tandon S. N. 
Published: March 2020

AbstractThe UVIT ultraviolet and visual band detectors and electronics for the ASTROSAT observatory were calibrated in the vacuum laboratory at the University of Calgary. This work was supported by the Canadian Space Agengy and carried out prior to integration with the UVIT optical assembly and the ASTROSAT spacecraft. The multiband (X-ray, ultraviolet and optical) ASTROSAT observatory was successfully launched by the Indian Space Research Organization on Sept. 28, 2015, with subsequent in-orbit verification and ongoing calibration activities. Here we discuss the current issues of calibrating the UVIT data, such as distortion corrections, and how the laboratory data is being used to address these issues.
VO for education and outreach
Authors: Iafrate Giulia 
Published: March 2020

AbstractThe Virtual Observatory (VO) is an international astronomical community-based initiative. VO aims to allow global electronic access to the available astronomical data archives of space and ground-based observatories and other sky survey databases. VO for education is a project developed within the framework of the European Virtual Observatory (EuroVO) with the aim of diffusing VO data and software to the public, in particular students, teachers and astronomy enthusiasts. VO for education offers use cases, pedagogical units, and simplified professional software that will allow a taste of the emotion of scientific research even to those approaching astronomy for the first time or simply wishing to wander between stars.
Transforming research (and public engagement) through citizen science
Authors: Blickhan Samantha , Trouille Laura , Lintott Chris J. 
Published: March 2020

AbstractProcessing our increasingly large datasets poses a bottleneck for producing real scientific outcomes and citizen science - engaging the public in research - provides a solution, particularly when coupled with automated routines. In this talk we will provide a broad overview of citizen science approaches and best practices. We will also highlight in particular recent advances through Zooniverse, the world’s largest platform for online citizen science, engaging more than 1.7 million volunteers in tasks including discovering exoplanets, identifying features on Mars’ surface, transcribing artist’s notebooks, and tracking resistance to antibiotics.
AAS Nova and Astrobites as Bridges Between Astronomy Communities
Authors: Kohler Susanna ,   the AAS Publishing Team,   the Astrobites Collaboration
Published: March 2020

AbstractEducation and outreach in astronomy often focuses on communicating broad astronomical concepts. But how can educators and outreach practitioners also share current astronomical research results with students and the public, conveying both the process of science and the excitement of new discoveries? AAS Nova and Astrobites are two resources freely available to the astronomy community and the general public, intended to help readers learn about the most recent research published across the field of astronomy. Both supported by the American Astronomical Society, these two daily astrophysical literature blogs provide accessible summaries of recent publications in AAS journals and on the arXiv. As both AAS Nova and Astrobites directly distill original studies, these resources constitute a critical bridge between astronomy researchers and educators, outreach practitioners, and the broader astronomy community. The material on these two websites — which includes a total archive of more than 2,500 research study summaries — is written accessibly while still providing access to the original sources and outcomes. As a result, AAS Nova and Astrobites can be used by educators and outreach practitioners to easily introduce the latest in astronomical research studies into classrooms and outreach events.
FM14 Session 2: Communicating Astronomy in our Changing World
Authors: Waller William H. , Canas Lina , Agata Hidehiko , Yamaoka Hitoshi , Karino Shigeyuki , Cenadelli Davide , Bernagozzi Andrea Ettore , Christille Jean Marc , Benedetto Matteo , Calabrese Matteo , Calcidese Paolo , Gelderman Richard , Hayashi Saeko S. , Lubowich Donald , Madura Thomas , Christian Carol , Hurd David , Silberman Ken , Walker Kyle , McVoy Shannon , Massey Robert , Radajewski Bogumił , Mikołajewski Maciej , Czart Krzysztof , Guz Iwona , Rubaszewski Adam , Stelmach Tomasz , Ros Rosa M. , Viñuales Ederlinda , Garca Beatriz , Sánchez Yuly E. , Vargas Domínguez Santiago , Acosta Cesar , Rodríguez Nayive , Sekhar Aswin , Sundin Maria , Andersson Petra , Finnsgård Christian , Larsson Lars , Miller Ron , Tomita Akihiko , Wadadekar Yogesh 
Published: March 2020

AbstractAs the IAU heads towards its second century, many changes have simultaneously transformed Astronomy and the human condition world-wide. Amid the amazing recent discoveries of exoplanets, primeval galaxies, and gravitational radiation, the human condition on Earth has become blazingly interconnected, yet beset with ever-increasing problems of over-population, pollution, and never-ending wars. Fossil-fueled global climate change has begun to yield perilous consequences. And the displacement of people from war-torn nations has reached levels not seen since World War II.
The IAU Strategic Plan for 2020-2030: OAD
Authors: van Dishoeck Ewine F. , Meloy Elmegreen Debra 
Published: March 2020

AbstractThe IAU Strategic Plan for 2020-2030 presents an overview of all of the activities of the IAU along with priorities, key goals, mandates, and specific actions. Here future plans and goals are outlined for the Office of Astronomy for Development (OAD).
The DARA Big Data Project
Authors: Scaife Anna M. M. , Cooper Sally E. 
Published: March 2020

AbstractThe DARA Big Data project is a flagship UK Newton Fund & GCRF program in partnership with the South African Department of Science & Technology (DST). DARA Big Data provides bursaries for students from the partner countries of the African VLBI Network (AVN), namely Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia and Zambia, to study for MSc(R) and PhD degrees at universities in South Africa and the UK. These degrees are in the three data intensive DARA Big Data focus areas of astrophysics, health data and sustainable agriculture. The project also provides training courses in machine learning, big data techniques and data intensive methodologies as part of the Big Data Africa initiative.
The Data Observatory, a vehicle to foster digital economy using natural advantages in astronomy in Chile
Authors: Arancibia Demián , Bayo Amelia , Cabrera-Vives Guillermo , Föster Francisco , González Roberto , Hamuy Mario , Carlos Maureira Juan , Quinn Peter , Rada Juan , Rodriguez Gabriel , Santander-Vela Juande , Tarenghi Massimo , Teresa Ruiz María , San-Martin Mauro , Williams Robert 
Published: March 2020

AbstractThe Astroinformatics Program is funded by the Chilean Economy Ministry’s (FIE Grant FIE-2016-V022, CORFO Grant 16IFI6626) with the mission to identify and initiate investments to foster Chilean Digital Economy, using Astronomy data-centric tools (known as astroinformatics). Over 2017 we worked with communities across sectors identifying opportunities to achieve the program mission, the Data Observatory vision emerged from that work and will guide design activities throughout 2018.
Elastic Impact Consequences for High‐Frequency Earthquake Ground Motion
Authors: Tsai Victor C. , Hirth Greg 
Published: March 2020

AbstractA fundamental question of earthquake science is what produces damaging high‐frequency ground motion, with the classic Brune‐Haskell model postulating that abrupt fault slip causes it. However, even when amended with heterogeneous rupture, the model fails to explain observations of different sized repeating earthquakes and has challenges explaining high‐frequency radiation patterns. We propose an additional cause for high‐frequency earthquake spectra from elastic collisions of structures within a rupturing fault zone. The collision spectrum is set by an impact contact time proportional to the size of colliding structures so that spectra depend on fundamentally different physical parameters compared with slip models. When added to standard models, collisions can reconcile the discrepant observations since the size, shape, and orientation of structures vary between different fault zones but remain constant within a fault segment. High‐frequency earthquake ground motions and damage may therefore be an outgrowth of fault‐zone structure rather than sudden initiation of slip.
Assessing Long‐Term Postseismic Transients From GPS Time Series in Southern California
Authors: Guns K. A. , Bennett R. A. 
Published: March 2020

AbstractIn order to gain insight into long‐term plate boundary motion and to shed light on geodetic‐based fault slip rates and the seismic hazards they inform, we apply a forward modeling strategy to identify and reduce the short‐ and long‐term effects of viscoelastic postseismic deformation on modern GPS observations following large magnitude earthquakes in Southern California. We assess ongoing postseismic deformation in the southwestern United States by analyzing all magnitude ≥Mw6.0 earthquakes that have occurred there and in Baja California and Sonora, Mexico, since year 1800, finding that ongoing postseismic displacements from 12 events are potentially contributing to the modern day deformation field in Southern California. With a forward modeling step, we calculate postseismic displacements associated with these 12 events using a reference model consisting of a layered, laterally homogeneous, viscoelastic Earth structure; these displacements are then subtracted from processed horizontal GPS coordinate time series data to produce a postseismic‐reduced data set. In order to quantify the success of this forward modeling in reducing the postseismic signal, we estimate parameters representing logarithmic decay associated with the 2010 Mw7.2 El Mayor‐Cucapah earthquake using two different time series analysis methods. Variance reduction indicates we were able to reduce postseismic deformation in this test case by up to 60%. Anomaly maps produced using our assessment of deformation around the El Mayor‐Cucapah event highlight hot spots in which secondary processes may be occurring or where a more complex viscosity structure may be necessary.
Crack‐Induced Shear‐Wave Orthorhombic Anisotropy: Modeling and Inversion of Shear‐Wave Borehole Measurements
Authors: Xu Song , Tang Xiao Ming , Su Yuan Da , Torres‐Verdín Carlos 
Published: March 2020

AbstractRocks in horizontally layered sediments often exhibit transversely isotropic (TI) characteristics and contain aligned fractures/cracks due to tectonic movement and stress. We model the effective elastic properties of the TI medium containing vertically aligned cracks using the sphere‐equivalency of the effective scattering method. Results show that the corresponding anisotropy of the VTI background medium containing vertically fluid‐filled ellipsoidal inclusions can be characterized by the orthorhombic anisotropy model. The shear‐wave anisotropy of the model is governed by three anisotropy parameters, corresponding to the horizontal plane, and the two vertical planes that are normal and parallel to the crack plane, respectively. Effects on anisotropy parameters due to cracks are examined in detail, showing that one can use shear‐wave measurements to evaluate both the TI and crack parameters of the cracked TI‐rock. Based on the theoretical analysis, we develop an inversion method to estimate shear anisotropy parameters from the four‐component shear‐wave logging measurement in a vertical borehole penetrating the orthorhombic rock. The inversion method is validated with synthetic data and applied to interpret acoustic anisotropy from borehole measurements acquired in a fractured shale formation, where theoretical predictions and measurements are found in good agreement.
Climate Simulations of Early Mars With Estimated Precipitation, Runoff, and Erosion Rates
Authors: Ramirez Ramses M. , Craddock Robert A. , Usui Tomohiro 
Published: March 2020

AbstractThe debate over the early Martian climate is among the most intriguing in planetary science. Although the geologic evidence generally supports a warmer and wetter climate, climate models have had difficulty simulating such a scenario, leading some to suggest that the observed fluvial geology (e.g., valley networks, modified landscapes) on the Martian surface could have formed in a cold climate instead. However, as we have originally predicted using a single‐column radiative‐convective climate model (Ramirez, Kopparapu, Zugger, et al., 2014, https://doi.org/10.1038/ngeo2000), warming from CO2‐H2 collision‐induced absorption on a volcanically active early Mars could have raised mean surface temperatures above the freezing point, with later calculations showing that this is achievable with hydrogen concentrations as low as ~1%. Nevertheless, these predictions should be tested against more complex models. Here we use an advanced energy balance model that includes a northern lowlands ocean to show that mean surface temperatures near or slightly above the freezing point of water were necessary to carve the valley networks. Our scenario is consistent with a relatively large ocean as has been suggested. Valley network distributions would have been global prior to subsequent removal processes. At lower mean surface temperatures and smaller ocean sizes, precipitation and surface erosion efficiency diminish. The warm period may have been approximately <107 years, perhaps suggesting that episodic warming mechanisms were not needed. Atmospheric collapse and permanently glaciated conditions occur once surface ice coverage exceeds a threshold depending on collision‐induced absorption assumptions. Our results support an early warm and semiarid climate consistent with many geologic observations.
Application of a High‐Resolution Distributed Hydrological Model on a U.S.‐Canada Transboundary Basin: Simulation of the Multiyear Mean AnnualHydrograph and 2011 Flood of theRichelieu River Basin
Authors: Lucas‐Picher Philippe , Arsenault Richard , Poulin Annie , Ricard Simon , Lachance‐Cloutier Simon , Turcotte Richard 
Published: March 2020

AbstractDuring spring 2011, an extreme flood occurred along the Richelieu River located in southern Quebec, Canada. The Richelieu River is the last section of the complex Richelieu basin, which is composed of the large Lake Champlain located in a valley between two large mountains. Previous attempts in reproducing the Richelieu River flow relied on the use of simplified lumped models and showed mixed results. In order to prepare a tool to assess accurately the change of flood recurrences in the future, a state‐of‐the‐art distributed hydrological model was applied over the Richelieu basin. The model setup comprises several novel methods and data sets such as a very high resolution river network, a modern calibration technique considering the net basin supply of Lake Champlain, a new optimization algorithm, and the use of an up‐to‐date meteorological data set to force the model. The results show that the hydrological model is able to satisfactorily reproduce the multiyear mean annual hydrograph and the 2011 flow time series when compared with the observed river flow and an estimation of the Lake Champlain net basin supply. Many factors, such as the quality of the meteorological forcing data, that are affected by the low density of the station network, the steep terrain, and the lake storage effect challenged the simulation of the river flow. Overall, the satisfactory validation of the hydrological model allows to move to the next step, which consists in assessing the impacts of climate change on the recurrence of Richelieu River floods.
Tumor necrosis factor alpha mediates neuromuscular synapse elimination
Authors: Fu Xiu-Qing , Peng Jian , Wang Ai-Hua , Luo Zhen-Ge 
Published: March 2020

AbstractDuring the development of mammalian neuromuscular junction (NMJ), the original supernumerary axon inputs are gradually eliminated, finally leaving each muscle fiber innervated by a single axon terminal. However, the molecular cues that mediate the elimination of redundant axon inputs remain unclear. Here we show that tumor necrosis factor-α (TNFα) expressed in postsynaptic muscle cells plays an important role in presynaptic axonal elimination at the NMJ. We found that intramuscular injection of TNFα into the levator auris longus (LAL) muscles caused disassociation of presynaptic nerve terminals from the postsynaptic acetylcholine receptor (AChR) clusters. By contrast, genetic ablation of TNFα globally or specifically in skeletal muscle cells, but not in motoneurons or Schwann cells, delayed the synaptic elimination. Moreover, ablation of TNFα in muscle cells attenuated the tendency of activity-dependent competition in a motoneuron–muscle coculture system. These results suggest a role of postsynaptic TNFα in the elimination of redundant synaptic inputs.
Transcriptomic resources for evolutionary studies in flat periwinkles and related species
Authors: Marques João P. , Sotelo Graciela , Galindo Juan , Chaube Pragya , Costa Diana , Afonso Sandra , Panova Marina , Nowick Katja , Butlin Roger , Hollander Johan , Faria Rui 
Published: March 2020

AbstractThe flat periwinkles,Littorina fabalisandL. obtusata, comprise two sister gastropod species that have an enormous potential to elucidate the mechanisms involved in ecological speciation in the marine realm. However, the molecular resources currently available for these species are still scarce. In order to circumvent this limitation, we used RNA-seq data to characterize the transcriptome of four individuals from each species sampled in different locations across the Iberian Peninsula. Fourde novotranscriptome assemblies were generated, as well as a pseudo-reference using theL. saxatilisreference transcriptome as backbone. After transcripts’ annotation, variant calling resulted in the identification of 19,072 to 45,340 putatively species-diagnostic SNPs. The discriminatory power of a subset of these SNPs was validated by implementing an independent genotyping assay to characterize reference populations, resulting in an accurate classification of individuals into each species and in the identification of hybrids between the two. These data comprise valuable genomic resources for a wide range of evolutionary and conservation studies in flat periwinkles and related taxa.