bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nature et composition chimique des micas de deux lamprophyres
Authors: Métais Danielle , Ravier Jean , Phan Kieu-Duong 
Published: October 2018

L'étude des compositions chimiques des micas de deux lamprophyres (une kersantite de Bretagne et une minette des Vosges) a montré qu'il s'agissait, dans les deux roches, de phlogopites.
Ces phlogopites sont, par ailleurs, zonées, comme il en est dans la plupart des roches lamprophyriques : elles présentent, en effet, une couronne sombre entourant complètement un centre plus clair. Des mesures qualitatives et quantitatives à la sonde de Castaing ont prouvé que cette zonation correspondait à une différence de composition chimique (voir fig. 7) : la partie centrale des micas est la seule à comporter du chrome ; elle est plus riche en magnésium que la couronne externe. Cette couronne, au contraire, est la seule à contenir du baryum et du manganèse ; elle est plus riche en fer, en titane et en cérium que la partie centrale.
La zunyite ; recherches expérimentales physico-chimiques en liaison avec l'étude du nouveau gisement de Beni-Embarek
Authors: Turco Guy 
Published: October 2018

En liaison avec la description minéralogique et cristallographique des cristaux de zunyite provenant du nouveau gisement de Beni-Embarek (Algérie), nous avons entrepris une étude physico-chimique d'ensemble de la zunyite.
Les cristaux tétraédriques montrent la macle type cuivre gris ; le paramètre «a » de la maille cubique vaut : 13,93 ± 0,01 Â ; la densité est déterminée avec précision Djr-c = 2,873 ; la présence constante de quartz dans les cristaux est mise en évidence et discutée. La formule chimique établie est du type de celle donnée par L. Pauling : Al₁₃Si₅O₂₀ (OH₁₄F₂)F₂Cl. La décomposition thermique est étudiée par analyse thermique différentielle et analyse thermo-pondérale : la perte de masse est de l'ordre de 18 % entre 20 et 1 300° C ; les stades de la thermolyse sont suivis par les techniques de diffraction des rayons X et de microscopie électronique : les conclusions permettent d'interpréter les courbes obtenues (A. T. D. et A. T. P.) et de déduire le mécanisme chimique de la réaction.
La mullite qui prend naissance directement au cours de la thermolyse (sans phase intermédiaire) possède des relations d'orientation par rapport à la zunyite de départ : les rangées [110] et [100] de la zunyite coïncident respectivement avec les rangées [001] et [120] de la mullite ; l'explication envisagée pour justifier ce fait expérimental conduit à admettre un phénomène de topotaxie.
Les propriétés de la zunyite vis-à-vis des radiations infrarouges sont étudiées entre 2 et 25 µ par spectrographie d'absorption ; les pics d'absorption enregistrés sont en partie expliqués.
Des expériences de synthèse par voie hydrothermale permettent de préciser les conditions physico-chimiques de la formation de la zunyite au laboratoire ; le domaine de stabilité du minéral est délimité entre 4700 et 6oo° C ; le rôle fondamental du fluor est souligné.
Multi-epoch L-band Spectroscopy of the Be Star μ Centauri Prior to Outburst
Authors: Aguayo G. , Mennickent R. E. , Granada A. , Otero S. 
Published: October 2018

Abstract
With the aim of contributing to the understanding of the disk formation process in Be stars, we pursued a one-year spectroscopic observing campaign of the Be star μ Centauri in the L-band, using VLT/ISAAC. We present the nine near-IR spectra we obtained in an epoch of relative photometric quiescence prior to an outburst of ΔV = 0.4 magnitude. Visual estimates during the epoch of our L-band spectroscopy are also presented for the first time, together with the unpublished complete visual light curve between the years 1998 and 2014. We observe significant and monotonic changes in emission line strength of Bracket-α and Pfund-γ lines relative to Humphreys lines, and also in the continuum slope. We interpret these observed changes in terms of important changes to the column density of the line emitting regions, moving from an optically thin to an optically thick stage just prior to a major outburst. For each observing date, we provide estimates for the column density and relative extension of the line emitting region. If the changes observed toward the end of our observing campaign were related to mass-loss changes from the central star, they would correspond to an increase in a factor of two in the mass of the disk in the innermost region. If related to the visual outburst observed one month later, the variability observed in our spectra would be the first detection of the early disk formation process in the L-band.
A SEA BASS on the Exoplanet HD 209458b
Authors: Morello G. 
Published: October 2018

Abstract
We present here the first application of Stellar and Exoplanetary Atmospheres Bayesian Analysis Simultaneous Spectroscopy (SEA BASS) on real data sets. SEA BASS is a scheme that enables the simultaneous derivation of four-coefficient stellar limb-darkening profiles, transit depths, and orbital parameters from exoplanetary transits at multiple wavelengths. It relies on the wavelength independence of the system geometry and on the reduced limb-darkening effect in the infrared. This approach has been introduced by Morello et al. (without the SEA BASS acronym), who discuss several tests on synthetic data sets. Here, we (1) improve on the original algorithm using multiple Spitzer/InfraRed Array Camera passbands and a more effective set of geometric parameters, (2) demonstrate its ability with Hubble Space Telescope/Space Telescope Imaging Spectrograph data sets by (3) measuring the HD 209458 stellar limb-darkening profile over multiple passbands in the 290–570 nm range with sufficient precision to rule out some theoretical models that have been adopted previously in the literature, and (4) simultaneously extracting the transmission spectrum of the exoplanet atmosphere. The higher photometric precision of the next-generation instruments, such as those on board the James Webb Space Telescope, will enable modeling the star–planet systems with unprecedented detail, and increase the importance of SEA BASS for avoiding the potential biases introduced by inaccurate stellar limb-darkening models.
Constraining the Gap Size in the Disk around HD 100546 in the Mid-infrared
Authors: Jamialahmadi Narges , Ratzka Thorsten , Panić Olja , Fathivavsari Hassan , Boekel Roy van , Flement Sebastien , Henning Thomas , Jaffe Walter , Mulders Gijs D. 
Published: October 2018

Abstract
We refine the gap size measurements of the disk surrounding the Herbig Ae star HD 100546 in the N band. Our new mid-infrared interferometric (MIDI) data have been taken with the UT baselines and span the full range of orientations. The correlated fluxes show a wavy pattern in which the minima separation links to a geometrical structure in the disk. We fit each correlated flux measurement with a spline function, deriving the corresponding spatial scale, while assuming that the pattern arises interferometrically due to the bright emission from the inner disk and the opposing sides of the wall of the outer disk. We then fit an ellipse to the derived separations at their corresponding position angles, thereby using the observations to constrain the disk inclination to i = 47° ± 1° and the disk position angle to PA = 135.°0 ± 2.°5 east of north, both of which are consistent with the estimated values in previous studies. We also derive the radius of the ellipse to 15.7 ± 0.8 au. To confirm that the minima separations translate to a geometrical structure in the disk, we model the disk of HD 100546 using a semianalytical approach taking into account the temperature and optical depth gradients. Using this model, we simultaneously reproduce the level and the minima of the correlated fluxes and constrain the gap size of the disk for each observation. The values obtained for the projected gap size in different orientations are consistent with the separation found by the geometrical model.
Volans-Carina: A New 90 Myr Old Stellar Association at 85 pc
Authors: Gagné Jonathan , Faherty Jacqueline K. , Mamajek Eric E. 
Published: October 2018

Abstract
We present a characterization of the new Volans-Carina Association (VCA) of stars near the Galactic plane (b ≃ −10°) at a distance of ≃75–100 pc, previously identified as group 30 by Oh et al. We compile a list of 19 likely members from Gaia DR2 with spectral types B8–M2, and 46 additional candidate members from Gaia DR2, 2MASS, and AllWISE with spectral types A0–M9 that require further follow-up for confirmation. We find an isochronal age of

Myr based on MIST isochrones calibrated with Pleiades members. This new association of stars is slightly younger than the Pleiades, with less members but located at a closer distance, making its members ≃3 times as bright as those of the Pleiades on average. It is located further than members of the AB Doradus moving group, which have a similar age, but it is more compact on the sky, which makes it less prone to contamination from random field interlopers. Its members will be useful benchmarks to understand the fundamental properties of stars, brown dwarfs, and exoplanets at ≃90 Myr. We also provide an updated version of the BANYAN Σ Bayesian classification tool that includes the VCA.
Chemical Evolution of N2H+ in Six Massive Star-forming Regions
Authors: Yu Nai-Ping , Xu Jin-Long , Wang Jun-Jie , Liu Xiao-Lan 
Published: October 2018

Abstract
To investigate how the abundance of N2H+ varies as massive clumps evolve, here we present a multiwavelength study toward six molecular clouds. All of these clouds contain several massive clumps in different evolutionary stages of star formation. Using archival data of the Herschel infrared Galactic Plane Survey (Hi-GAL), we made H2 column density and dust temperature maps of these regions by the spectral energy distribution method. We found that all of the six clouds show distinct dust temperature gradients, ranging from ∼20 to ∼30 K. This makes them good candidates to study chemical evolution of molecules (such as N2H+) in different evolutionary stages of star formation. Our molecular line data comes from the Millimeter Astronomy Legacy Team Survey at 90 GHz (MALT90). We made column density and then abundance maps of N2H+. We found that when the dust temperature is above 27 K, the abundance of N2H+ begins to decrease or reaches a plateau. We regard that this is because in the photodissociation regions around classical H ii regions, N2H+ is heavily destroyed by free electrons. However, when the dust temperature is below 27 K, the abundance of N2H+ increases with the dust temperature. This seems to be inconsistent with previous chemical models made in low-mass star-forming regions. In order to investigate whether this inconsistency is caused by a different chemistry in high-mass star-forming clumps, higher angular resolution observations are necessary.
Detection of Prebiotic Molecules in Plasma and Photochemical Aerosol Analogs Using GC/MS/MS Techniques
Authors: Sebree Joshua A. , C. Roach Madeline , Shipley Emma R. , He Chao , Hörst Sarah M. 
Published: October 2018

Abstract
The formation and identification of prebiotic compounds in the organically rich atmospheres of Titan and Pluto are of great interest due to the potential implications such discoveries may have on theories of the origins of life on the early Earth. In past work, hindrances in detecting prebiotic molecules in lab-generated aerosol analogs have been the large number of products formed, often compounded by limited sample amounts. In this work, we detail a GC/MS/MS protocol that is highly selective (>30 simultaneously detectable compounds) and highly sensitive (limits of detection ∼1 picomole). Using this method to analyze aerosol analogs (tholins) generated by either cold plasma or photochemical irradiation of 1:1 mixtures of methane and carbon monoxide in nitrogen, this work has expanded the number of identifiable compounds in Titan/Pluto analog aerosols to include the nonbiological nucleobases xanthine and hypoxanthine in plasma aerosols and the first identification of glycine as a product in photochemical aerosols produced under reducing atmospheric conditions. Several species (glycine, guanidine, urea, and glycolic acid) were found to be present in both plasma and photochemical aerosols. Such parallel product pathways bring new understanding to the nature of plasma and photochemical aerosols and allow for new insights into the prebiotic chemistry of organically rich atmospheres including Pluto, Titan, and the early Earth.
Predicting the COSIE-C Signal from the Outer Corona up to 3 Solar Radii
Authors: Del Zanna Giulio , Raymond John , Andretta Vincenzo , Telloni Daniele , Golub Leon 
Published: October 2018

Abstract
We present estimates of the signal to be expected in quiescent solar conditions, as would be obtained with the COronal Spectrographic Imager in the EUV in its coronagraphic mode (COSIE-C). COSIE-C has been proposed to routinely observe the relatively unexplored outer corona, where we know that many fundamental processes affecting both the lower corona and the solar wind are taking place. The COSIE-C spectral band, 186–205 Å, is well-known as it has been observed with Hinode EIS. We present Hinode EIS observations that we obtained in 2007 out to 1.5 R
⊙, to show that this spectral band in quiescent streamers is dominated by Fe xii and Fe xi and that the ionization temperature is nearly constant. To estimate the COSIE-C signal in the 1.5–3.1 R
⊙ region we use a model based on CHIANTI atomic data and SoHO UVCS observations in the Si xii and Mg x coronal lines of two quiescent 1996 streamers. We reproduce the observed EUV radiances with a simple density model, photospheric abundances, and a constant temperature of 1.4 MK. We show that other theoretical or semi-empirical models fail to reproduce the observations. We find that the coronal COSIE-C signal at 3 R
⊙ should be about 5 counts/s per 3.″1 pixel in quiescent streamers. This is unprecedented and opens up a significant discovery space. We also briefly discuss stray light and the visibility of other solar features. In particular, we present UVCS observations of an active region streamer, indicating increased signal compared to the quiet Sun cases.
High-resolution ALMA Study of the Proto-brown-dwarf Candidate L328-IRS
Authors: Lee Chang Won , Kim Gwanjeong , Myers Philip C. , Saito Masao , Kim Shinyoung , Kwon Woojin , Lyo A-Ran , Soam Archana , Kim Mi-Ryang 
Published: October 2018

Abstract
This paper presents our observational attempts to precisely measure the central mass of a proto-brown dwarf candidate, L328-IRS, in order to investigate whether L328-IRS is in the substellar mass regime. Observations were made for the central region of L328-IRS with the dust continuum and CO isotopologue line emission at Atacama Large Millimeter/submillimeter Array (ALMA) band 6, discovering the detailed outflow activities and a deconvolved disk structure of a size of ∼87 × 37 au. We investigated the rotational velocities as a function of the disk radius, finding that its motions between 130 and 60 au are partially fitted with a Keplerian orbit by a stellar object of ∼0.30 M
⊙, while the motions within 60 au do not follow any Keplerian orbit at all. This makes it difficult to lead a reliable estimation of the mass of L328-IRS. Nonetheless, our ALMA observations were useful enough to well constrain the inclination angle of the outflow cavity of L328-IRS as ∼66°, enabling us to better determine the mass accretion rate of ∼8.9 × 10−7
M
⊙ yr−1. From assumptions that the internal luminosity of L328-IRS is mostly due to this mass accretion process in the disk, or that L328-IRS has mostly accumulated the mass through this constant accretion rate during its outflow activity, its mass was estimated to be ∼0.012–0.023 M
⊙, suggesting L328-IRS to be a substellar object. However, we leave our identification of L328-IRS as a proto-brown dwarf to be tentative because of various uncertainties, especially regarding the mass accretion rate.
The Carrier of 3.3 μm Aromatic Infrared Bands: Anharmonicity and Temperature Effects on Neutral PAHs
Authors: Chen Tao 
Published: October 2018

Abstract
Anharmonic infrared (IR) spectra are crucial for the study of interstellar polycyclic aromatic hydrocarbon (PAH) molecules. This work aims to provide a comprehensive study of the features that may influence the accuracy of anharmonic IR spectra of PAHs so that a reliable spectrum that incorporates all necessary features for interpreting the observational IR spectra can be obtained. Six PAHs are investigated: naphthalene, anthracene, pyrene, chrysene, 9,10-dimethylanthracene, and 9,10-dihydroanthracene. The NIST spectra and high-resolution IR absorption spectra are utilized as the reference for the comparisons. The influences of different resonances and resonant thresholds are studied. Four methods for electronic structure calculations are tested. The quantitative comparisons indicate that for the NIST data, B3LYP/N07D provides the best agreement with measured spectra concerning band positions and B3LYP/cc-pVTZ is superior in the description of the relative intensities. The importance of 1–3 Darling–Dennison resonances, which are required for generating triple combination bands, is investigated through a comparison to a high-resolution experimental spectrum. For interpreting the bandwidths and profiles of the observational spectra, the temperature effects are included through the Wand-Landau random walk technique. The comparisons between calculated high-temperature anharmonic and observational spectra indicate that small and compact PAHs might be responsible for the 3.3 μm aromatic infrared bands.
HST STIS UV Spectroscopic Observations of the Protoplanetary Nebula Hen3-1475∗
†
Authors: Fang Xuan , Castro Ana I. Gómez de , Toalá Jesús A. , Riera Angels 
Published: October 2018

Abstract
We present UV spectra of the protoplanetary nebula (pPN) Hen 3-1475 obtained with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). Our deep, low-dispersion spectroscopy enables monochromatic imaging of Hen 3-1475 in ultraviolet (UV) nebular emission lines, the first of such attempt ever made for a pPN. The high spatial resolution of STIS imaging allows an unprecedentedly sharp view of the S-shaped jet, especially the inner NW1 knot, which is resolved into four components in Mg ii
λ2800. Through critical comparison with HST optical narrowband images, we found a negative radial velocity gradient in NW1, from −1550 km s−1 on its innermost component to ∼−300 km s−1 on the outermost. Despite their high radial velocities, these components of NW1 mostly show no obvious (or very small) proper motions, indicating that they might be quasi-stationary shocks near the tip of the conical flow along the collimated jet of Hen 3-1475.
Quadriceps Weakness and Risk of Knee Cartilage Loss Seen on Magnetic Resonance Imaging in a Population-based Cohort with Knee Pain
Authors: Chin Carson , Sayre Eric C. , Guermazi Ali , Nicolaou Savvas , Esdaile John M. , Kopec Jacek , Thorne Anona , Singer Joel , Wong Hubert , Cibere Jolanda 
Published: October 2018

Objective.To determine whether baseline quadriceps weakness predicts cartilage loss assessed on magnetic resonance imaging (MRI).Methods.Subjects aged 40–79 with knee pain (n = 163) were recruited from a random population sample and examined for quadriceps weakness with manual isometric strength testing, using a 3-point scoring system (0 = poor resistance, 1 = moderate resistance, 2 = full resistance), which was dichotomized as normal (grade 2) versus weak (grade 0/1). MRI of the more symptomatic knee was obtained at baseline and at mean of 3.3 years. Cartilage was graded 0–4 on MRI. Exponential regression analysis was used to evaluate whether quadriceps weakness was associated with whole knee cartilage loss, and in secondary analyses with compartment-specific cartilage loss, adjusted for age, sex, body mass index, Western Ontario and McMaster Universities Osteoarthritis Arthritis Index pain score, and baseline MRI cartilage score.Results.Of 163 subjects, 54% were female, with a mean age of 57.7 years. Quadriceps weakness was seen in 11.9% of the subjects. Weakness was a predictor of whole knee cartilage loss (HR 3.48, 95% CI 1.30–9.35). Quadriceps weakness was associated with cartilage loss in the medial tibiofemoral (TF) compartment (HR 4.60, 95% CI 1.25–17.02), while no significant association was found with lateral TF (HR 1.53, 95% CI 0.24–9.78) or patellofemoral compartment (HR 2.76, 95% CI 0.46–16.44).Conclusion.In this symptomatic, population-based cohort, quadriceps weakness predicted whole knee and medial TF cartilage loss after 3 years. To our knowledge, this is the first study to show that a simple clinical examination of quadriceps strength can predict the risk of knee cartilage loss.
Performance of the Expanded Cardiovascular Risk Prediction Score for Rheumatoid Arthritis Is Not Superior to the ACC/AHA Risk Calculator
Authors: Wahlin Bengt , Innala Lena , Magnusson Staffan , Möller Bozena , Smedby Torgny , Rantapää-Dahlqvist Solbritt , Wållberg-Jonsson Solveig 
Published: October 2018

Objective.Cardiovascular (CV) risk estimation calculators for the general population do not perform well in patients with rheumatoid arthritis (RA). An RA-specific risk calculator has been developed, but did not perform better than a risk calculator for the general population when validated in a heterogeneous multinational cohort.Methods.In a cohort of patients with new-onset RA from northern Sweden (n = 665), the risk of CV disease was estimated by the Expanded Cardiovascular Risk Prediction Score for Rheumatoid Arthritis (ERS-RA) and the American College of Cardiology/American Heart Association algorithm (ACC/AHA). The ACC/AHA estimation was analyzed, both as crude data and when adjusted according to the recommendations by the European League Against Rheumatism (ACC/AHA × 1.5). ERS-RA was calculated using 2 variants: 1 from patient and physician reports of hypertension (HTN) and hyperlipidemia [ERS-RA (reported)] and 1 from assessments of blood pressure (BP) and blood lipids [ERS-RA (measured)]. The estimations were compared with observed CV events.Results.All variants of risk calculators underestimated the CV risk. Discrimination was good for all risk calculators studied. Performance of all risk calculators was poorer in patients with a high grade of inflammation, whereas ACC/AHA × 1.5 performed best in the high-inflammatory patients. In those patients with an estimated risk of 5–15%, no risk calculator performed well.Conclusion.ERS-RA underestimated the risk of a CV event in our cohort of patients, especially when risk estimations were based on patient or physician reports of HTN and hyperlipidemia instead of assessment of BP and blood lipids. The performance of ERS-RA was no better than that of ACC/AHA × 1.5, and neither performed well in high-inflammatory patients.