bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploring the Solar System using stellar occultations
Authors: Sicardy Bruno 
Published: March 2018

AbstractStellar occultations by solar system objects allow kilometric accuracy, permit the detection of tenuous atmospheres (at nbar level), and the discovery of rings. The main limitation was the prediction accuracy, typically 40 mas, corresponding to about 1,000 km projected at the body. This lead to large time dedicated to astrometry, tedious logistical issues, and more often than not, mere miss of the event. The Gaia catalog, with sub-mas accuracy, hugely improves both the star positions, resulting in achievable accuracies of about 1 mas for the shadow track on Earth. This permits much more carefully planned campaigns, with success rate approaching 100%, weather permitting. Scientific perspectives are presented, e.g. central flashes caused by Plutos atmosphere revealing hazes and winds near its surface, grazing occultations showing topographic features, occultations by Chariklos rings unveiling dynamical features such as proper mode “breathing”.
The Differential Astrometric Reference Frame on short timescales in the Gaia Era
Authors: Abbas Ummi , Bucciarelli Beatrice , Lattanzi Mario G. , Crosta Mariateresa , Gai Mario , Smart Richard , Sozzetti Alessandro , Vecchiato Alberto 
Published: March 2018

AbstractWe use methods of differential astrometry to construct a small field inertial reference frame stable at the micro-arcsecond level. Using Gaia measurements of field angles we look at the influence of the number of reference stars and the stars magnitude as well as astrometric systematics on the total error budget with the help of Gaia-like simulations around the Ecliptic Pole in a differential astrometric scenario. We find that the systematic errors are modeled and reliably estimated to the μas level even in fields with a modest number of 37 stars with G <13 mag over a 0.24 sq. degrees field of view for short timescales of the order of a day for a perfect instrument and with high-cadence observations. Accounting for large-scale calibrations by including the geometric instrument model over such short timescales requires fainter stars down to G=14 mag without diminishing the accuracy of the reference frame.
Using Gaia as an Astrometric Tool for Deep Ground-based Surveys
Authors: Casetti-Dinescu Dana I. , Girard Terrence M. , Schriefer Michael 
Published: March 2018

AbstractGaia DR1 positions are used to astrometrically calibrate three epochs’ worth of Subaru SuprimeCam images in the fields of globular cluster NGC 2419 and the Sextans dwarf spheroidal galaxy. Distortion-correction “maps” are constructed from a combination of offset dithers and reference to Gaia DR1. These are used to derive absolute proper motions in the field of NGC 2419. Notably, we identify the photometrically-detected Monoceros structure in the foreground of NGC 2419 as a kinematically-cold population of stars, distinct from Galactic-field stars. This project demonstrates the feasibility of combining Gaia with deep, ground-based surveys, thus extending high-quality astrometry to magnitudes beyond the limits of Gaia.
Finding evolved stars in the inner Galactic disk withGaia
Authors: Quiroga-Nuñez L. H. , van Langevelde H. J. , Pihlström Y. M. , Sjouwerman L. O. , Brown A. G. A. 
Published: March 2018

AbstractThe Bulge Asymmetries and Dynamical Evolution (BAaDE) survey will provide positions and line-of-sight velocities of ~20, 000 evolved, maser bearing stars in the Galactic plane. Although this Galactic region is affected by optical extinction, BAaDE targets may haveGaiacross-matches, eventually providing additional stellar information. In an initial attempt to cross-match BAaDE targets withGaia, we have found more than 5,000 candidates. Of these, we may expect half to show SiO emission, which will allow us to obtain velocity information. The cross-match is being refined to avoid false positives using different criteria based on distance analysis, flux variability, and color assessment in the mid- and near-IR. Once the cross-matches can be confirmed, we will have a unique sample to characterize the stellar population of evolved stars in the Galactic bulge, which can be considered fossils of the Milky Way formation.
Local tests of gravitation with Gaia observations of Solar System Objects
Authors: Hees Aurélien , Le Poncin-Lafitte Christophe , Hestroffer Daniel , David Pedro 
Published: March 2018

AbstractIn this proceeding, we show how observations of Solar System Objects with Gaia can be used to test General Relativity and to constrain modified gravitational theories. The high number of Solar System objects observed and the variety of their orbital parameters associated with the impressive astrometric accuracy will allow us to perform local tests of General Relativity. In this communication, we present a preliminary sensitivity study of the Gaia observations on dynamical parameters such as the Sun quadrupolar moment and on various extensions to general relativity such as the parametrized post-Newtonian parameters, the fifth force formalism and a violation of Lorentz symmetry parametrized by the Standard-Model extension framework. We take into account the time sequences and the geometry of the observations that are particular to Gaia for its nominal mission (5 years) and for an extended mission (10 years).
Search for Galactic warp signal in Gaia DR1 proper motions
Authors: Poggio E. , Drimmel R. , Smart R. L. , Spagna A. , Lattanzi M. G. 
Published: March 2018

AbstractThe nature and origin of the Galactic warp represent one of the open questions posed by Galactic evolution. Thanks to Gaia high precision absolute astrometry, steps towards the understanding of the warp's dynamical nature can be made. Indeed, proper motions for long-lived stable warp are expected to show measurable trends in the component vertical to the galactic plane. Within this context, we search for the kinematic warp signal in the first Gaia data release (DR1). By analyzing distant spectroscopically-identified OB stars in the Hipparcos subset in Gaia DR1, we find that the kinematic trends cannot be explained by a simple model of a long-lived warp. We therefore discuss possible scenarios for the interpretation of the obtained results. We also present current work in progress to select a larger sample of OB star candidates from the Tycho-Gaia Astrometric Solution (TGAS) subsample in DR1, and delineate the points that we will be addressing in the near future.
Determining the Local Dark Matter Density with SDSS G-dwarf data
Authors: Silverwood Hamish , Sivertsson Sofia , Read Justin , Bertone Gianfranco , Steger Pascal 
Published: March 2018

AbstractWe present a determination of the local dark matter density derived using the integrated Jeans equation method presented in Silverwoodet al.(2016) applied to SDSS-SEGUE G-dwarf data processed by Büdenbender et al. (2015). For our analysis we construct models for the tracer density, dark matter and baryon distribution, and tilt term (linking radial and vertical motions), and then calculate the vertical velocity dispersion using the integrated Jeans equation. These models are then fit to the data usingMultiNest, and a posterior distribution for the local dark matter density is derived. We find the most reliable determination to come from the α-young population presented in Büdenbenderet al.(2015), yielding a result of ρDM= 0.46+0.07−0.09GeV cm−3= 0.012+0.001−0.002M⊙pc−3. Our results also illuminate the path ahead for future analyses using Gaia DR2 data, highlighting which quantities will need to be determined and which assumptions could be relaxed.
The PMA Catalogue as a realization of the extragalactic reference system in optical and near infrared wavelengths
Authors: Akhmetov Volodymyr S. , Fedorov Peter N. , Velichko Anna B. 
Published: March 2018

AbstractWe combined the data from theGaiaDR1 and Two-Micron All Sky Survey (2MASS) catalogues in order to derive the absolute proper motions more than 420 million stars distributed all over the sky in the stellar magnitude range 8 mag < G < 21 mag (Gaia magnitude). To eliminate the systematic zonal errors in position of 2MASS catalogue objects, the 2-dimensional median filter was used. The PMA system of proper motion has been obtained by direct link to 1.6 millions extragalactic sources. The short analysis of the absolute proper motion of the PMA stars Catalogue is presented in this work. From a comparison of this data with same stars from the TGAS, UCAC4 and PPMXL catalogues, the equatorial components of the mutual rotation vector of these coordinate systems are determined.
Galactic Disk Structure and Metallicity from Mono-age Stellar Populations of LAMOST
Authors: Xiang Maosheng , Liu Xiaowei , Shi Jianrong , Yuan Haibo , Huang Yang , Chen Bingqiu , Wang Chun 
Published: March 2018

AbstractThe LAMOST Galactic surveys provide robust stellar atmospheric parameters, abundances, masses and ages of millions of stars, allowing a unprecedented mapping of matter distribution, spatial structure, star formation rate, chemistry and kinematics of the Galaxy. In this proceeding we present structure and metallicity of the Galactic disk revealed by mono-age stellar populations within a few kilo-parsec of the solar neighborhood.
The time evolution of gaps in tidal streams in axisymmetric potentials
Authors: Koppelman Helmer H. , Helmi Amina 
Published: March 2018

AbstractOur goal is to understand the evolution and properties of gaps produced by dark matter subhalos in stellar tidal streams. Here we explore how gaps grow in spherical potentials in comparison to axisymmetric potentials. We develop a model that uses the divergence of two orbits, one on each side of the gap, to describe the size of the gap and how this varies with time and depends on the characteristics of the encounter with the dark subhalo. To this end we use a formalism based on action-angle variables.
RAVE-Gaia and the impact on Galactic archeology
Authors: Kunder Andrea 
Published: March 2018

AbstractThe new data release (DR5) of the RAdial Velocity Experiment (RAVE) includes radial velocities of 520,781 spectra of 457,588 individual stars, of which 215,590 individual stars are released in the Tycho-Gaia astrometric solution (TGAS) in Gaia DR1. Therefore, RAVE contains the largest TGAS overlap of the recent and ongoing Milky Way spectroscopic surveys. Most of the RAVE stars also contain stellar parameters (effective temperature, surface gravity, overall metallicity), as well as individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni. Combining RAVE with TGAS brings the uncertainties in space velocities down by a factor of 2 for stars in the RAVE volume – 10 km s−1 uncertainties in space velocities are now able to be derived for the majority (70%) of the RAVE-TGAS sample, providing a powerful platform for chemo-dynamic analyses of the Milky Way. Here we discuss the RAVE-TGAS impact on Galactic archaeology as well as how the Gaia parallaxes can be used to break degeneracies within the RAVE spectral regime for an even better return in the derivation of stellar parameters and abundances.
Prediction of stellar occultations by distant solar system bodies in the Gaia era
Authors: Desmars Josselin , Camargo Julio , Sicardy Bruno , Braga-Ribas Felipe , Vieira-Martins Roberto , Assafin Marcelo , Bérard Diane , Benedetti-Rossi Gustavo 
Published: March 2018

AbstractStellar occultations are a unique technique to access physical characteristics of distant solar system objects from the ground. They allow the measure of the size and the shape at kilometric level, the detection of tenuous atmospheres (few nanobars), and the investigation of close vicinity (satellites, rings) of Transneptunian objects and Centaurs. This technique is made successful thanks to accurate predictions of occultations. Accuracy of the predictions depends on the uncertainty in the position of the occulted star and the object's orbit. The Gaia stellar catalogue (Gaia Collaboration (2017)) now allows to get accurate astrometric stellar positions (to the mas level). The main uncertainty remains on the orbit. In this context, we now take advantage of the NIMA method (Desmars et al.(2015)) for the orbit determination and of the Gaia DR1 catalogue for the astrometry. In this document, we show how the orbit determination is improved by reducing current and some past observations with Gaia DR1. Moreover, we also use more than 45 past positive occultations observed in the 2009-2017 period to derive very accurate astrometric positions only depending on the position of the occulted stars (about few mas with Gaia DR1). We use the case of (10199) Chariklo as an illustration. The main limitation lies in the imprecision of the proper motions which is going to be solved by the Gaia DR2 release.
Astrometry and Spectra Classification of Near Earth Asteroids with Lijiang 2.4m Telescope
Authors: Zhang X. L. , Yang B. , Bai J. M. 
Published: March 2018

AbstractThe Lijiang 2.4m telescope of Yunnan Observatories is located at longitude E100°01′51″, latitude N26°42′32″ and height 3250m above sea level (IAU code O44). Because of low latitude of the site, long-focus system and planetary tracking mode of telescope, high accuracy positioning and spectral classification of the near Earth objects (NEAs) especially in the Southern Hemisphere can be studied with the Lijiang 2.4m telescope. As a set of observational campaigns organized by the GAIA-FUN-SSO, astrometry of several near Earth asteroids including (367943) Duende and (99942) Apophis were made with Lijiang 2.4m telescope during 2013. From December 12, 2015, spectra of three near earth asteroids were also observed with the YFOSC terminal attached to the Lijiang 2.4m telescope. This paper will give the detailed introduction of Lijiaing 2.4m telescope and observational results of near Earth asteroids obtained with it.
Modelling the Milky Way with Gaia-TGAS
Authors: Hunt Jason A. S. 
Published: March 2018

AbstractI summarize two recent projects involving the Gaia-TGAS data. Firstly, I discuss a detection of a lack of disc stars in the Solar neighbourhood with velocities close to zero angular momentum. We use predictions of this effect to make a measurement of the Solar rotation velocity around the Galactic centre, and also of R0. Secondly, I discuss a detection of a group of stars with systematically high Galactic rotation velocity. We propose that it may be caused by the Perseus arm and compare the data with simulations.
The AMBRE Project: r-process element abundances in the Milky Way thin and thick discs
Authors: Guiglion Guillaume , de Laverny Patrick , Recio-Blanco Alejandra , Worley C. Clare 
Published: March 2018

AbstractChemical evolution of r-process elements in the Milky Way disc is still a matter of debate. We took advantage of high resolution HARPS spectra from the ESO archive in order to derive precise chemical abundances of 3 r-process elements Eu, Dy & Gd for a sample of 4 355 FGK Milky Way stars. The chemical analysis has been performed thanks to the automatic optimization pipeline GAUGUIN. Based on the [α/Fe] ratio, we chemically characterized the thin and the thick discs, and present here results of these 3 r-process element abundances in both discs. We found an unexpected Gadolinium and Dysprosium enrichment in the thick disc stars compared to Europium, while these three elements track well each other in the thin disc.
Galaxy simulations in the Gaia era
Authors: Minchev Ivan 
Published: March 2018

AbstractWe live in an age where an enormous amount of astrometric, photometric, asteroseismic, and spectroscopic data of Milky Way stars are being acquired, many orders of magnitude larger than about a decade ago. Thanks to the Gaia astrometric mission and followup ground-based spectroscopic surveys in the next 5-10 years about 10-20 Million stars will have accurate 6D kinematics and chemical composition measurements. KEPLER-2, PLATO, and TESS will provide asteroseismic ages for a good fraction of those. In this article we outline some outstanding problems concerning the formation and evolution of the Milky Way and argue that, due to the complexity of physical processes involved in the formation of disk galaxies, numerical simulations in the cosmological context are needed for the interpretation of Milky Way observations. We also discuss in some detail the formation of the Milky Way thick disk, chemodynamical models, and the effects of radial migration.
Impact on the Hipparcos2-UCAC4 geometric relation from some physical properties of the stars
Authors: Marco Francisco J. , Martínez María J. , López Jose A. 
Published: March 2018

AbstractThe aim of this paper is the study of the impact that the consideration of different physical properties as magnitude and spectral type of stars has on the geometric relations between Hipparcos2 and UCAC4. In this sense, the pairs of residuals Δα* and Δδ can be considered as functions of (α, δ, r) and for each fixed r, we can fit a vector field on the sphere from which to obtain its components in the VSH basis. The same can be done by grouping the stars considering their magnitudes, spectral types (or mixing them) and then studying the variations in the mentioned geometry. We must not forget that Δα* and Δδ are numerical random variables whose regression on the magnitude m, for example, can be estimated. The results will be computed taking into account r as well as the physical mentioned properties. So, we avoid the assumption that the harmonic coefficients depend only on m.
A 3D-Study of the residual vector field
Authors: Marco Francisco J. , Martínez María J. , López Jose A. 
Published: March 2018

AbstractOne of the important challenges that Gaia imposes on the Astrometric Catalogs, is a careful study in everything affected by parallax. A particularly important case is the necessary linkage Gaia - HCRF - ICRF2, which require methods of analysis that are accurate enough so that the provided results are at the same precision level as the work data.
The Gaia sky: version 1.0
Authors: Brown Anthony G. A. 
Published: March 2018

AbstractIn this contribution I provide a brief summary of the contents of Gaia DR1. This is followed by a discussion of studies in the literature that attempt to characterize the quality of the Tycho-Gaia Astrometric Solution parallaxes in Gaia DR1, and I point out a misconception about the handling of the known systematic errors in the Gaia DR1 parallaxes. I highlight some of the more unexpected uses of the Gaia DR1 data and close with a look ahead at the next Gaia data releases, with Gaia DR2 coming up in April 2018.
Self-consistent modelling of our Galaxy with Gaia data
Authors: Binney James 
Published: March 2018

AbstractGalaxy models are fundamental to exploiting surveys of our Galaxy. There is now a significant body of work on axisymmetric models. A model can be defined by giving the DF of each major class of stars and of dark matter. Then the self-consistent gravitational potential is determined. Other modelling techniques are briefly considered before an overview of some early work on non-axisymmetric models.
Detection of PRMT1 inhibitors with stopped flow fluorescence
Authors: Qian Kun , Hu Hao , Xu Hui , Zheng Y George 
Published: March 2018

AbstractProtein arginine methyltransferases (PRMTs) are crucial epigenetic regulators in eukaryotic organisms that serve as histone writers for chromatin remodeling. PRMTs also methylate a variety of non-histone protein substrates to modulate their function and activity. The development of potent PRMT inhibitors has become an emerging and imperative research area in the drug discovery field to provide novel therapeutic agents for treating diseases and as tools to investigate the biological functions of PRMTs. PRMT1 is the major type I enzyme that catalyzes the formation of asymmetric dimethyl arginine, and PRMT1 plays important regulatory roles in signal transduction, transcriptional activation, RNA splicing, and DNA repair. Aberrant expression of PRMT1 is found in many types of cancers, pulmonary diseases, cardiovascular disease, diabetes, and renal diseases. PRMT1 is a highly promising target for therapeutic development. We created a stopped flow fluorescence-based assay for PRMT1 inhibitor detection and characterization that has the advantages of being homogeneous, nonradioactive, and mix-and-measure in nature, allowing for continuous measurement of the methylation reaction and its inhibition. To our knowledge, this is the first continuous assay for PRMT1 reaction detection and inhibitor characterization. The approach is not only capable of quantitatively determining the potency (IC50) of PRMT1 inhibitors but can also distinguish cofactor-competitive inhibitors, substrate-competitive inhibitors, and mixed-type inhibitors.
Disease-induced assemblage of a plant-beneficial bacterial consortium
Authors: Berendsen Roeland L , Vismans Gilles , Yu Ke , Song Yang , de Jonge Ronnie , Burgman Wilco P , Burmølle Mette , Herschend Jakob , Bakker Peter A H M , Pieterse Corné M J 
Published: March 2018

Abstract
Disease suppressive soils typically develop after a disease outbreak due to the subsequent assembly of protective microbiota in the rhizosphere. The role of the plant immune system in the assemblage of a protective rhizosphere microbiome is largely unknown. In this study, we demonstrate that Arabidopsis thaliana specifically promotes three bacterial species in the rhizosphere upon foliar defense activation by the downy mildew pathogen Hyaloperonospora arabidopsidis. The promoted bacteria were isolated and found to interact synergistically in biofilm formation in vitro. Although separately these bacteria did not affect the plant significantly, together they induced systemic resistance against downy mildew and promoted growth of the plant. Moreover, we show that the soil-mediated legacy of a primary population of downy mildew infected plants confers enhanced protection against this pathogen in a second population of plants growing in the same soil. Together our results indicate that plants can adjust their root microbiome upon pathogen infection and specifically recruit a group of disease resistance-inducing and growth-promoting beneficial microbes, therewith potentially maximizing the chance of survival of their offspring that will grow in the same soil.
The convergent roles of NF-κB and ER stress in sunitinib-mediated expression of pro-tumorigenic cytokines and refractory phenotype in renal cell carcinoma
Authors: Makhov Peter , Naito Sei , Haifler Miki , Kutikov Alexander , Boumber Yanis , Uzzo Robert G. , Kolenko Vladimir M. 
Published: March 2018

AbstractRenal cell carcinoma (RCC) is the most common form of kidney cancer. While cure remains exceptionally infrequent in RCC patients with systemic or recurrent disease, current targeted molecular strategies, including multi-targeted tyrosine kinase inhibitors (TKIs), notably changed the treatment paradigm of advanced renal cancer. Yet, complete and durable responses have been noted in only a few cases. Our studies reveal that sunitinib triggers two resistance-promoting signaling pathways in RCC cells, which emanate from the endoplasmic reticulum (ER) stress response: a PERK-driven ER stress response that induces expression of the pro-tumorigenic cytokines IL-6, IL-8, and TNF-α, and a TRAF2-mediated NF-κB survival program that protects tumor cells against cell death. PERK blockade completely prevents sunitinib-induced expression of IL-6, IL-8 and TNF-α, whereas NF-κB inhibition reinstates sensitivity of RCC cells to sunitinib both in vitro and in vivo. Taken together, our findings indicate that ER stress response may contribute to sunitinib resistance in RCC patients.