bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studying the H-alpha line of the B[ e ] supergiant binary GG Carinae using high-cadence optical spectroscopy
Authors: Porter Augustus , Blundell Katherine , Lee Steven 
Published: December 2019

AbstractWe present a case study of GG Carinae (GG Car), a Galactic B[ e ] supergiant binary having significant eccentricity (0.28), based on Global Jet Watch spectroscopy data which has been collecting high-time-sampled optical spectra since early 2015. GG Car has so far not been observed in the X-ray band, however it is of similar phenomenology to known X-ray binaries and may therefore be an obscured X-ray source. We have discovered that the absorption component of the H-alpha line displays a ∼62-478-day period in both equivalent width and wavelength centroid indicating cycles in the dynamics of the circumstellar environment, such as precession of the circumbinary or circumprimary disk. Circumbinary disk precession is an as-of-yet underexplored origin of super-orbital variations in the X-ray flux of X-ray binaries, since the rate of precession is generally much longer than the orbital period of the inner binary.
MAXI observations of long-term X-ray activities in SFXTs
Authors: Negoro Hitoshi 
Published: December 2019

AbstractSupergiant Fast X-ray Transients (SFXTs) are of great interest not only because of their peculiar properties but also as possible progenitors of gravitational-wave objects. The all-sky X-ray monitor MAXI/GSC has detected short flares on timescales of hours and long flares on timescales of days from SFXTs. Using nine-years of MAXI/GSC data, I attempted to search periodicity of eight SFXTs of which the one-day average fluxes were below the detection limit (∼ 10 mCrab), and confirmed the orbital periods of IGR J18483–0311 and IGR J17544–2619. This demonstrates that MAXI data are useful to find periodicities of sources even if the sources are undetectable in one day.
Optical and X-ray study of V404 Cyg during its activity in the Summer 2015
Authors: Nikolaeva Evgeniya A. , Bikmaev Ilfan F. , Glushkov Maxim V. , Irtuganov Eldar N. , Khamitov Irek M. 
Published: December 2019

Abstract. The black hole X-ray binary V404Cyg was studied during of the 2015 outburst. Optical photometry and spectroscopy were performed by using 1.5-meter Russian-Turkish telescope (RTT-150) facilities at the TUBITAK National Observatory (Antalya, Turkey). From June 22 to June 28, 2015, shell expansion velocity decreased from 650 to 400 km s–1 as measured by Hα and Hβ lines and from 450 to 330 km s–1 as measured by HeI and HeII lines. Thus, the shell expansion occurred with deceleration, where the hydrogen and helium line formation regions are at different radial distances from the center of the star. The correlation of flow variability in the optical and X-ray ranges is caused by fluctuations in the rate of accretion near a compact source where X-ray photons are generated.
Vertical distribution of HMXBs in NGC 55: Constraining their centre of mass velocity
Authors: Politakis Babis , Zezas Andreas , Andrews Jeff J. , Williams Stephen J. 
Published: December 2019

AbstractWe analyse the vertical distribution of High Mass X-ray Binaries (HMXBs) in NGC 55, the nearest edge-on galaxy to the Milky Way. Our analysis reveals significant spatial offsets of HMXBs from the star forming regions, greater than those observed in the SMC and the LMC but similar with the Milky Way. The spatial offsets can be explained by a momentum kick the X-ray binaries receive during the formation of the compact object. The difference between the scale height of the vertical distribution of HMXBs and the vertical distribution of star-forming activity is 0.48±0.04 kpc. The centre-of-mass velocity of the distribution of HMXBs in NGC 55 is moving at a velocity of 52.4±11.4 km s−1, greater than the corresponding velocity of HMXBs in the SMC and LMC, but consistent with velocities of Milky Way HMXBs.
On the nature of Supergiant Fast X-ray Transients
Authors: Negueruela Ignacio 
Published: December 2019

AbstractMore than a decade after fast x-ray transients with an OB supergiant counterpart were identified as a distinct class of wind-accreting sources, we still have not reached a consensus on the physical origin of their similarities and differences with persistent sources. Both kinds seem to extend over the same range of every relevant parameter. Here I argue that, despite this overall overlap, persistent sources have – on average – later-type, more evolved counterparts, and discuss the hypothesis that SFXTs are – on average – a younger population, as well as some of its possible implications.
Testing how massive stars evolve, lose mass, and collapse at low metal content
Authors: Rojas Montes Eliceth Y. , Vink Jorick 
Published: December 2019

AbstractIn order to test massive star evolution above 25 M⊙, we perform spectral analysis on a sample of massive stars in the Small Magellanic Cloud that includes both O stars as well as more evolved Wolf-Rayet stars. We present a grid of non-LTE stellar atmospheres that has been calculated using the cmfgen code, in order to have a systematic and homogeneous approach. We obtain stellar and wind parameters for O stars, spectral types ranging from O2 to O6, and the complete sample of known Wolf-Rayet stars. We discuss the evolutionary status of both the O and WR stars and the links between them, as well as the most likely evolutionary path towards black hole formation in a low metallicity environment, including testing theoretical predictions for mass-loss rates at low metallicities.
The possible origin of high frequency quasi-periodic oscillations in low mass X-ray binaries
Authors: Shi Chang Sheng , Zhang Shuang Nan , Li Xiang Dong 
Published: December 2019

AbstractWe summarize our model that high frequency quasi-periodic oscillations (QPOs) both in the neutron star low mass X-ray binaries (NS-LMXBs) and black hole LMXBs may originate from magnetohydrodynamic (MHD) waves. Based on the MHD model in NS-LMXBs, the explanation of the parallel tracks is presented. The slowly varying effective surface magnetic field of a NS leads to the shift of parallel tracks of QPOs in NS-LMXBs. In the study of kilohertz (kHz) QPOs in NS-LMXBs, we obtain a simple power-law relation between the kHz QPO frequencies and the combined parameter of accretion rate and the effective surface magnetic field. Based on the MHD model in BH-LMXBs, we suggest that two stable modes of the Alfv́en waves in the accretion disks with a toroidal magnetic field may lead to the double high frequency QPOs. This model, in which the effect of the general relativity in BH-LMXBs is considered, naturally accounts for the 3:2 relation for the upper and lower frequencies of the QPOs and the relation between the BH mass and QPO frequency.
Prospecting the wind structure of IGR J16320–4751 with XMM-NewtonandSwift
Authors: García F. , Fogantini F. A. , Chaty S. , Combi J. A. 
Published: December 2019

Abstract. TheINTEGRALsatellite has revealed a previously hidden population of absorbed High Mass X-ray Binaries (HMXBs) hosting supergiant (SG) stars. Among them, IGR J16320–4751 is a classical system intrinsically obscured by its environment, with a column density of~1023cm-2, more than an order of magnitude higher than the interstellar absorption along the line of sight. It is composed of a neutron star (NS) rotating with a spin period of~1300 s, accreting matter from the stellar wind of an O8I SG, with an orbital period of~9 days. We analyzed all existing archival XMM-NewtonandSwift/BAT observations of the obscured HMXB IGR J16320–4751 performing a detailed temporal and spectral analysis of the source along its orbit. Using a typical model for the supergiant wind profile, we simultaneously fitted the evolution of the hard X-ray emission and intrinsic column density along the full orbit of the NS around the SG, which allowed us to constrain physical and geometrical parameters of the binary system.
Dynamical versus isolated formation channels of gravitational wave sources
Authors: Mapelli Michela 
Published: December 2019

AbstractWhat are the formation channels of merging black holes and neutron stars? The first two observing runs of Advanced LIGO and Virgo give us invaluable insights to address this question, but a new approach to theoretical models is required, in order to match the challenges posed by the new data. In this review, I discuss the impact of stellar winds, core-collapse and pair instability supernovae on the formation of compact remnants in both isolated and dynamically formed binaries. Finally, I show that dynamical processes, such as the runaway collision scenario and the Kozai-Lidov mechanism, leave a clear imprint on the demography of merging systems.
Detection of the progenitors of Be X-ray Binaries
Authors: Gies Douglas , Wang Luqian , Peters Geraldine 
Published: December 2019

AbstractA recent survey of the far-ultraviolet spectra of 264 B-emission line stars has revealed 16 systems with hot companions that are the stripped down remains of a former mass donor star. Some of these will probably become Be + neutron star X-ray binaries in the future. The actual numbers of such systems may be large, because the detected systems have companions that occupy the brief and bright, He-shell burning stage of evolution.
Binarity of Pleione and its influence on the circumstellar disk
Authors: Iliev Lubomir 
Published: December 2019

AbstractPleione is a classical Be star well known for its cyclic transitions between Be-, shell- and normal B spectral phases. Its nature as a binary system was discussed by McAlister et al. (1989), Gies et al. (1990), Luthardt & Menchenkova (1994) and Nemravova et al (2010). We present the results that trace the evolution of the dimensions of the circumstellar disk of Pleione that are related to the binary system.
High mass X-ray binaries: Beacons in a stormy universe
Authors: Gies Douglas R. 
Published: December 2019

AbstractThe discovery of gravity waves from the mergers of black hole binaries has focused the astronomical community on the high mass X-ray binaries (HMXBs) as the potential progenitors of close pairs of compact stars. This symposium gathered experts in observational and theoretical work for a very timely review of our understanding of the processes that drive the X-ray luminosity of the diverse kinds of binaries and what evolutionary stages are revealed in the observed cases. Here I offer a condensed summary of some of the results about massive star properties, the observational categories of HMXBs, their accretion processes, their numbers in the Milky Way and other galaxies, and how they may be related to the compact binaries that merge in a burst of gravity waves.
V1187 Herculis: A Red Novae progenitor, and the most extreme mass ratio binary known
Authors: Samec Ronald G. , Chamberlain Heather , Caton Daniel , Robb Russell , Faulkner Danny R. 
Published: December 2019

AbstractComplete BVRCIC light curves of V1187 Her were obtained in May 2017 at the Dark Sky Observatory in North Carolina with the 0.81-m reflector of Appalachian State University. Earlier, spectra were taken at the Dominion Astrophysical Observatory with the 1.8-m telescope. The spectral type was found to be F8±1 V (6250 K), so the binary is of solar-type. V1187 Her was previously identified as a low amplitude (V < 0.2 mag), short period, overcontact eclipsing binary (EW) with a period of 0.310726 d. Strikingly, despite its low amplitude, the early light curves show total eclipses (eclipse duration ≍31.5 minutes), which is a characteristic of an extreme mass ratio binary. A period study covering 11 years reveals a continuous period decrease dP/dt=–4.7×10–9 d yr–1. The multi-band Wilson-Devinney light curve solution gives a fill-out of 79% and a mass ratio of only 0.0440±0.0001. There is a cool spot region on the secondary component, which is 400 K hotter than the primary. The inclination is only 66.85±0.05 despite the system’s total eclipses.
Polar Ionospheric Large‐Scale Structures and Dynamics Revealed by TEC Keogram Extracted From TEC Maps
Authors: Wang Y. , Zhang Q.‐H. , Ma Y.‐Z. , Jayachandran P. T. , Xing Z.‐Y. , Balan N. , Zhang S.‐R. 
Published: December 2019

AbstractA method named total electron content (TEC) keogram is introduced for surveying the large‐scale irregularities continuously in the polar ionosphere. The TEC keogram is developed from a movie of TEC maps along various meridian lines from the dayside to the nightside across the magnetic pole, trying to identify and track several types of ionospheric structures. Through two examples, a clear train of polar cap patches are identified from TEC keogram and confirmed by SuperDARN radar observations. The motion speed of these patches estimated from this tool agrees with SuperDARN radar measurements. Then, the motions of patches relative to the background convection through the whole polar cap are statistically studied for the first time. Moreover, the occurrence dependence of fully tracked patches on months, UT hours, and interplanetary magnetic field conditions is generally consistent with previous reports. These results suggest that the TEC keogram offers a power tool for continuous monitoring and studying of large‐scale plasma irregularities in the polar ionosphere.
Predicting how color and shape combine in the human visual system to direct attention
Authors: Buetti Simona , Xu Jing , Lleras Alejandro 
Published: December 2019

AbstractObjects in a scene can be distinct from one another along a multitude of visual attributes, such as color and shape, and the more distinct an object is from its surroundings, the easier it is to find it. However, exactly how this distinctiveness advantage arises in vision is not well understood. Here we studied whether and how visual distinctiveness along different visual attributes (color and shape, assessed in four experiments) combine to determine an object’s overall distinctiveness in a scene. Unidimensional distinctiveness scores were used to predict performance in six separate experiments where a target object differed from distractor objects along both color and shape. Results showed that there is mathematical law determining overall distinctiveness as the simple sum of the distinctiveness scores along each visual attribute. Thus, the brain must compute distinctiveness scores independently for each visual attribute before summing them into the overall score that directs human attention.
Modification of asphalt mixtures for cold regions using microencapsulated phase change materials
Authors: Bueno Moises , Kakar Muhammad Rafiq , Refaa Zakariaa , Worlitschek Jörg , Stamatiou Anastasia , Partl Manfred N. 
Published: December 2019

AbstractPhase change materials (PCMs) may be used to regulate the temperature of road surfaces to avoid low-temperature damages when asphalt materials become brittle and prone to cracking. With this in mind, different asphalt mixtures were modified with microencapsulated phase change materials (i.e. tetradecane) to assess their thermal benefits during the phase change process. Likewise, the effect on the mechanical performance of PCMs as a replacement of mineral filler was assessed. Special attention was paid to dry and wet modification processes for incorporating the PCMs into the mixtures. The results showed that PCM modifications are indeed able to slow down cooling and affect temperatures below zero. Approximately, a maximum of 2.5 °C offset was achieved under the tested cooling conditions compared to the unmodified reference specimens. Regarding the mechanical response at 0 °C and 10 °C, the results indicated that the PCM modification significantly reduces the stiffness of the material in comparison with the values obtained for the reference mixture.
Short-lived long noncoding RNAs as surrogate indicators for chemical stress in HepG2 cells and their degradation by nuclear RNases
Authors: Tani Hidenori , Numajiri Ayaka , Aoki Motohide , Umemura Tomonari , Nakazato Tetsuya 
Published: December 2019

AbstractLong noncoding RNAs (lncRNAs) are non-protein-coding transcripts >200 nucleotides in length that have been shown to play important roles in various biological processes. The mechanisms underlying the induction of lncRNA expression by chemical exposure remain to be determined. We identified a novel class of short-lived lncRNAs with half-lives (t1/2) ≤4 hours in human HeLa Tet-off cells, which have been suggested to express many lncRNAs with regulatory functions. As they may affect various human biological processes, short-lived lncRNAs may be useful indicators of the degree of stress on chemical exposure. In the present study, we identified four short-lived lncRNAs, designated as OIP5-AS1, FLJ46906, LINC01137, and GABPB1-AS1, which showed significantly upregulated expression following exposure to hydrogen peroxide (oxidative stress), mercury II chloride (heavy metal stress), and etoposide (DNA damage stress) in human HepG2 cells. These lncRNAs may be useful indicators of chemical stress responses. The levels of these lncRNAs in the cells were increased because of chemical stress-induced prolongation of their decay. These lncRNAs were degraded by nuclear RNases, which are components of the exosome and XRN2, and chemical exposure inhibited the RNase activities within the cells.
Mathematical modeling and computer simulation of the three-dimensional pattern formation of honeycombs
Authors: Jeong Darae , Li Yibao , Kim Sangkwon , Choi Yongho , Lee Chaeyoung , Kim Junseok 
Published: December 2019

AbstractWe present a mathematical model, a numerical scheme, and computer simulations of the three-dimensional pattern formation of a honeycomb structure by using the immersed boundary method. In our model, we assume that initially the honeycomb cells have a hollow hemisphere mounted by a hollow circular cylinder shape at their birth and there is force acting upon the entire side of the cell. The net force from the individual cells is a key factor in their transformation from a hollow hemisphere mounted by a hollow circular cylinder shape to a rounded rhombohedral surfaces mounted by a hexagonal cylinder shape. Numerical simulations of the proposed mathematical model equation produce the rounded rhombohedral surfaces mounted by a hexagonal cylinder patterns observed in honeybee colonies.
Immunotoxins: Targeted Toxin Delivery for Cancer Therapy
Authors: Mei Xin , Chen Junsheng , Wang Jing , Zhu Jianwei 
Published: December 2019

AbstractImmunotoxins are proteins that consist of a protein toxin conjugated to a specific targeting moiety. The targeting moiety is usually an antibody or ligand, such as monoclonal antibody, antibody fragment, a cytokine, or a growth factor. The toxins usually come from plant toxins, bacterial toxins, or human-origin cytotoxic elements. Nearly all toxins work by enzymatically inhibiting protein synthesis. After binding to antigens or receptors on target cell surfaces, immunotoxins are internalized and translocated to the cytosol where they can kill the cells. Immunotoxins have demonstrated high cytotoxicity to cancer cells and to date two immunotoxins have been approved by U.S. Food and Drug Administration on the markets for the treatment of hematological tumors: Lumoxiti and Ontak. Many other molecules are under development or clinical trials for different forms of cancer. Although immunotoxins exhibit great potency in xenograft model systems and early clinical trials, there are obstacles that limit successful treatments, including immunogenicity, nonspecific toxicity, and poor penetration. However, efforts are underway to address these problems. In this review, we summarize immunotoxins currently in clinical trials for either hematological tumors or solid tumors, outline the design of immunotoxins utilizing variety of components, and discuss the prominent examples of redesigned immunotoxins with reduced immunogenicity and nonspecific toxicity, as well as the strategies in manufacturing immunotoxins. With further improvements, it is anticipated that immunotoxins will play an increasing role in cancer therapy.
Executive Functions and Academic Outcomes of Low Birthweight Infants: A Prospective Longitudinal U.S. Cohort
Authors: Miller Sarah E. , DeBoer Mark D. , Scharf Rebecca J. 
Published: December 2019

Abstract
Objective Executive functions such as working memory and cognitive flexibility are key to lifelong learning. Our hypothesis was that children born low birthweight (LBW), defined as weight < 2,500 g, would have lower cognitive outcomes than those born normal weight, and children with poor executive functioning would be at risk for poor academic outcomes.
Study Design We evaluated data from 12,656 children followed prospectively in the Early Childhood Longitudinal Study, Kindergarten Class 2010–2011, assessing outcomes from kindergarten, first grade, and second grade. Multivariable linear and logistic regressions were run evaluating the relationship between birthweight and cognitive outcomes, and the odds of infants with poor executive functioning having poor academic outcomes.
Results Compared with children with normal birthweight, those born LBW had lower mean z-scores for academic and directly assessed executive functions from kindergarten through second grade. LBW children were at an increased risk of scoring in the bottom 20% of children at all time points: second-grade reading odds ratio (OR) = 1.60 (95% confidence interval [CI:] 1.23–2.09), math OR = 1.49 (95% CI: 1.21–1.84), science OR = 1.41 (95% CI: 1.11–1.81), cognitive flexibility OR = 1.61 (95% CI: 1.27–2.02), and working memory OR = 1.40 (95% CI: 1.10–1.77).
Conclusion LBW infants remain at risk of poor cognitive outcomes in second grade. Early difficulties with executive functioning can increase the risk of a child's academic performance years later.
High Dose Indomethacin for Patent Ductus Arteriosus Closure Increases Neonatal Morbidity
Authors: Waldvogel Salome , Atkinson Andrew , Wilbeaux Mélanie , Nelle Mathias , Berger Markus R. , Gerull Roland 
Published: December 2019

AbstractObjective Symptomatic patent ductus arteriosus (sPDA) is the most common heart abnormality in preterm infants. Optimal duration and dose of medical treatment is still unclear. We assessed undesired effects and closure rate of high-dose indomethacin (HDI) for pharmacological closure of sPDA.Study Design Retrospective single center analysis of 248 preterm infants born between January 2006 and December 2015 with a birth weight <2,000 g and sPDA which was treated with indomethacin. Patients were treated with either standard dose indomethacin (SDI; n = 196) or HDI (n = 52). Undesired effects and PDA closure were compared between patients treated with SDI and HDI.Results In univariate analysis, patients receiving HDI had a significant increase in gastrointestinal hemorrhage (32.7 vs.11.7%, p = 0.001), bronchopulmonary dysplasia (BPD) (77.8 vs. 55.1%, p = 0.003), and retinopathy of prematurity (13.5 vs. 2.6%, p = 0.004). Moreover, HDI patients needed longer mechanical ventilation (2.5 vs. 1.0 days, p = 0.01). Multivariate analyses indicated that necrotizing enterocolitis (17 vs. 7%, p = 0.01) and BPD (79 vs. 55%, p = 0.02) were more frequent in HDI patients. PDA closure rate was 79.0% with HDI versus 65.3% with SDI.Conclusion HDI used for PDA closure is associated with an increase in necrotizing enterocolitis and BPD. Risks of HDI should be balanced against other treatment options.