bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inflowing gas in the central parsec of M81
Authors: Devereux Nick 
Published: June 2019

Abstract
Spectroscopic observations of the Seyfert 1/Liner nucleus of M81, obtained recently with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope(HST), have revealed an ultraviolet (UV)–visible spectrum rich with emission lines of a variety of widths, ionization potentials, and critical densities, including several in the UV that have not previously been reported. Even at the highest angular resolution currently achievable with HST, the broad-line region of M81 cannot be uniquely defined on the basis of commonly used observables such as the full width at half-maximum of the emission lines, or ratios of various emission lines. Numerous broad forbidden lines complicate interpretation of the spectra. At least three separate line-emitting components are inferred. Firstly, a large, highly ionized, low-density, low-metallicity H+ region producing the broad Balmer lines. Located within the H+ region are smaller condensations spanning a wide range in density, and the source of forbidden line emission through collisional excitation of the respective ions. Intermingled with the H+ region and the condensations is a curious extended source of time-variable C iv λ1548 emission. Collectively, these observations can be qualitatively understood in the context of a shock-excited jet cavity within a large H+ region that is photoionized by the central UV–X-ray source. The H+ region contains ∼500 M⊙ of low-metallicity gas that is dynamically unstable to inflow. At the current rate, the available H+ gas can sustain the advection-dominated accretion flow that powers the central UV–X-ray source for 105 yr.
Global analysis of luminosity- and colour-dependent galaxy clustering in the Sloan Digital Sky Survey
Authors: Paul Niladri , Pahwa Isha , Paranjape Aseem 
Published: June 2019

ABSTRACT
We present a halo occupation distribution (HOD) analysis of the luminosity- and colour-dependent galaxy clustering in the Sloan Digital Sky Survey. A novelty of our technique is that it uses a combination of clustering measurements in luminosity bins to perform a global likelihood analysis, simultaneously constraining the HOD parameters for a range of luminosity thresholds. We present simple, smooth fitting functions which accurately describe the resulting luminosity dependence of the best-fitting HOD parameters. To minimize systematic halo modelling effects, we use theoretical halo 2-point correlation functions directly measured and tabulated from a suite of N-body simulations spanning a large enough dynamic range in halo mass and spatial separation. Thus, our modelling correctly accounts for non-linear and scale-dependent halo bias as well as any departure of halo profiles from universality, and we additionally account for halo exclusion using the hard sphere approximation. Using colour-dependent clustering information, we constrain the satellite galaxy red fraction in a model-independent manner which does not rely on any group-finding algorithm. We find that the resulting luminosity dependence of the satellite red fraction is significantly shallower than corresponding measurements from galaxy group catalogues, and we provide a simple fitting function to describe this dependence. Our fitting functions are readily usable in generating low-redshift mock galaxy catalogues, and we discuss some potentially interesting applications as well as possible extensions of our technique.
The angular scale of homogeneity in the local Universe with the SDSS blue galaxies
Authors: Avila F , Novaes C P , Bernui A , de Carvalho E , Nogueira-Cavalcante J P 
Published: June 2019

ABSTRACT
We probe the angular scale of homogeneity in the local Universe using blue galaxies from the SDSS survey as a cosmological tracer. Through the scaled counts in spherical caps, $\mathcal {N}(\lt \theta)$, and the fractal correlation dimension, $\mathcal {D}_{2}(\theta)$, we find an angular scale of transition to homogeneity for this sample of θH = 22.19° ± 1.02°. A comparison of this measurement with another obtained using a different cosmic tracer at a similar redshift range (z < 0.06), namely, the H i extragalactic sources from the ALFALFA catalogue, confirms that both results are in excellent agreement (taking into account the corresponding bias correction). We also perform tests to assess the robustness of our results. For instance, we test if the size of the surveyed area is large enough to identify the transition scale we search for, and also we investigate a reduced sample of blue galaxies, obtaining in both cases a similar angular scale for the transition to homogeneity. Our results, besides confirming the existence of an angular scale of transition to homogeneity in different cosmic tracers present in the local Universe, show that the observed angular scale θH agrees well with what is expected in the ΛCDM scenario. Although we cannot prove spatial homogeneity within the approach followed, our results provide one more evidence of it, strengthening the validity of the Cosmological Principle.
Calibration of the virial factor f in supermassive black hole masses of reverberation-mapped AGNs
Authors: Yu Li-Ming , Bian Wei-Hao , Wang Chan , Zhao Bi-Xuan , Ge Xue 
Published: June 2019

ABSTRACT
Using a compiled sample of 34 broad-line active galactic nuclei (AGNs) with measured H β time lags from the reverberation mapping (RM) method and measured bulge stellar velocity dispersions σ*, we calculate the virial factor f by assuming that the RM AGNs intrinsically obey the same MBH−σ* relation as quiescent galaxies, where MBH is the mass of the supermassive black hole (SMBH). Considering four tracers of the velocity of the broad-line regions (BLRs), i.e. the H β line width or line dispersion from the mean or rms spectrum, there are four kinds of the factor f. Using the H β full width at half-maximum (FWHM) to trace the BLRs velocity, we find significant correlations between the factor f and some observational parameters, e.g. FWHM, the line dispersion. Using the line dispersion to trace the BLRs velocity, these relations disappear or become weaker. It implies the effect of inclination in BLRs geometry. It also suggests that the variable f in MBH estimated from luminosity and FWHM in a single-epoch spectrum is not negligible. Using a simple model of thick-disc BLRs, we also find that, as the tracer of the BLRs velocity, H β FWHM has some dependence on the inclination, while the line dispersion σH β is insensitive to the inclination. Considering the calibrated FWHM-based factor f from the mean spectrum, the scatter of the SMBH mass is 0.39 dex for our sample of 34 low-redshift RM AGNs. For a high-redshift sample of 30 Sloan Digital Sky Survey RM AGNs with measured stellar velocity dispersions, we find that the SMBH mass scatter is larger than that for our sample of 34 low-redshift RM AGNs. It implies the possibility of evolution of the MBH−σ* relation from high-redshift to low-redshift AGNs.
Evidence for two early accretion events that built the Milky Way stellar halo
Authors: Myeong G C , Vasiliev E , Iorio G , Evans N W , Belokurov V 
Published: June 2019

AbstractThe Gaia Sausage is the major accretion event that built the stellar halo of the Milky Way galaxy. Here, we provide dynamical and chemical evidence for a second substantial accretion episode, distinct from the Gaia Sausage. The Sequoia Event provided the bulk of the high-energy retrograde stars in the stellar halo, as well as the recently discovered globular cluster FSR 1758. There are up to six further globular clusters, including ω Centauri, as well as many of the retrograde substructures in Myeong et al., associated with the progenitor dwarf galaxy, named the Sequoia. The stellar mass in the Sequoia galaxy is ∼5 × 10  M⊙ , whilst the total mass is ∼1010 M⊙ , as judged from abundance matching or from the total sum of the globular cluster mass. Although clearly less massive than the Sausage, the Sequoia has a distinct chemodynamical signature. The strongly retrograde Sequoia stars have a typical eccentricity of ∼0.6, whereas the Sausage stars have no clear net rotation and move on predominantly radial orbits. On average, the Sequoia stars have lower metallicity by ∼0.3 dex and higher abundance ratios as compared to the Sausage. We conjecture that the Sausage and the Sequoia galaxies may have been associated and accreted at a comparable epoch.
The X-ray coronae of two massive galaxies in the core of the perseus cluster
Authors: Arakawa N , Fabian A C , Walker S A 
Published: June 2019

Abstract
We study the X-ray properties of two elliptical galaxies, NGC 1270 and NGC 1272, in the core of the Perseus cluster with deep Chandra observations. Both galaxies have central supermassive black holes, the mass of which is 6.0 × 109 and 2.0 × 109 $\rm{M}_\odot$, respectively. Our aim is to examine relatively cool soft X-ray-emitting gas within the central region of these massive early-type galaxies. Such gas, referred to as a Minicorona in previous studies is common in the core of large elliptical cluster galaxies. It has not been completely stripped or evaporated by the surrounding hot intracluster medium and nor fully accreted on to the central black hole. With thermal emission from the minicorona dominating over any power-law radiation components, we find that both NGC 1270 and NGC 1272 encompass minicoronae, the temperature and radius of which are 0.99 and 0.63 keV; 1.4 and 1.2 kpc, respectively. For NGC 1272, the thermal coronal component dominates the core emission by a factor of over 10. We show that the depletion time-scale of minicoronal gas via viscous stripping is shorter by a factor of 100 than the replenishment time-scale due to stellar mass-loss. Magnetic fields are presumably responsible for suppression of the transport processes. Finally, we show that both objects have to meet a balance between cooling and heating as well as that among mass replenishment, stripping, and accretion.
Multifractal detrended moving average analysis of Kepler stars with surface differential rotation traces
Authors: de Freitas D B , Nepomuceno M M F , Cordeiro J G , Das Chagas M L , De Medeiros J R 
Published: June 2019

ABSTRACTA multifractal formalism is employed to analyse high-precision time-series data of Kepler stars with surface differential rotation (DR) traces. The multifractal detrended moving average (MFDMA) algorithm has been explored to characterize the multiscale behaviour of the observed time series from a sample of 662 stars selected with parameters close to those of the Sun (e.g. effective temperature, mass, effective gravity and rotation period). Among these stars, 141 have surface DR traces, whereas 521 have no detected DR signatures. In our sample, we also include the Sun in its active phase. Our results can be summarized in two points. First, our work suggests that star-spots for time series with and without DR have distinct dynamics. Secondly, the magnetic fields of active stars are apparently governed by two mechanisms with different levels of complexity for fluctuations. Throughout the course of the study, we identified an overall trend whereby the DR is distributed in two H regimes segregated by the degree of asymmetry A, where H-index denotes the global Hurst exponent that is used as a measure of long-term memory of time series. As a result, we show that the degree of asymmetry can be considered a segregation factor that distinguishes the DR behaviour when related to the effect of the rotational modulation on the time series. In summary, the multifractality signals in our sample are the result of magnetic activity control mechanisms leading to activity-related long-term persistent signatures.
Accretion and outflow in V404 Cyg
Authors: Casares J , Muñoz-Darias T , Mata Sánchez D , Charles P A , Torres M A P , Armas Padilla M , Fender R P , García-Rojas J 
Published: June 2019

ABSTRACT
We study the optical evolution of the 2015 outburst in V404 Cyg, with emphasis on the peculiar nebular phase and subsequent decay to quiescence. From the decay time-scale of the Balmer emission associated with the nebula, we measure an outflow mass Mwind ≃ 4 × 10−6 M⊙. Remarkably, this is ∼100 times larger than the accreted mass and ∼10 per cent of the total mass stored in the disc. The wind efficiency must therefore be significantly larger than previous estimates for black hole transients, suggesting that radiation pressure (in addition to other mechanisms such as Compton-heating) plays a key role in V404 Cyg. In addition, we compare the evolution of the 2015 and 1989 outbursts and find not only clear similarities (namely a large luminosity drop ∼10 d after the X-ray trigger, followed by a brief nebular phase) but also remarkable differences in decay time-scales and long-term evolution of the H α profile. In particular, we see evidence for a rapid disc contraction in 2015, consistent with a burst of mass transfer. This could be driven by the response of the companion to hard X-ray illumination, most notably during the last gigantic (super-Eddington) flare on 2015 June 25. We argue that irradiation and consequential disc wind are key factors to understand the different outburst histories in 1989 and 2015. In the latter case, radiation pressure may be responsible for the abrupt end of the outburst through depleting inner parts of the disc, thus quenching accretion and X-ray irradiation. We also present a refined orbital period and updated ephemeris.
Fly-by encounters between two planetary systems I: Solar system analogues
Authors: Li Daohai , Mustill Alexander J , Davies Melvyn B 
Published: June 2019

ABSTRACTStars formed in clusters can encounter other stars at close distances. In typical open clusters in the Solar neighbourhood containing hundreds or thousands of member stars, 10–20 per cent of Solar-mass member stars are expected to encounter another star at distances closer than 100 au. These close encounters strongly perturb the planetary systems, directly causing ejection of planets or their capture by the intruding star, as well as exciting the orbits. Using extensive N-body simulations, we study such fly-by encounters between two Solar system analogues, each with four giant planets from Jupiter to Neptune. We quantify the rates of loss and capture immediately after the encounter, e.g. the Neptune analogue is lost in one in four encounters within 100 au, and captured by the flying-by star in 1 in 12 encounters. We then perform long-term (up to 1 Gyr) simulations investigating the ensuing post-encounter evolution. We show that large numbers of planets are removed from systems due to planet–planet interactions and that captured planets further enhance the system instability. While encounters can initially leave a planetary system containing more planets by inserting additional ones, the long-term instability causes a net reduction in planet number. A captured planet ends up on a retrograde orbit in half of the runs in which it survives for 1Gyr; also, a planet bound to its original host star but flipped during the encounter may survive. Thus, encounters between planetary systems are a channel to create counter-rotating planets, This would happen in around 1 per cent of systems, and such planets are potentially detectable through astrometry or direct imaging.
Machine-learning identification of asteroid groups
Authors: Carruba V , Aljbaae S , Lucchini A 
Published: June 2019

ABSTRACTAsteroid families are groups of asteroids that share a common origin. They can be the outcome of a collision or be the result of the rotational failure of a parent body or its satellites. Collisional asteroid families have been identified for several decades using hierarchical clustering methods (HCMs) in proper elements domains. In this method, the distance of an asteroid from a reference body is computed, and, if it is less than a critical value, the asteroid is added to the family list. The process is then repeated with the new object as a reference, until no new family members are found. Recently, new machine-learning clustering algorithms have been introduced for the purpose of cluster classification. Here, we apply supervised-learning hierarchical clustering algorithms for the purpose of asteroid families identification. The accuracy, precision, and recall values of results obtained with the new method, when compared with classical HCM, show that this approach is able to found family members with an accuracy above 89.5 per cent, and that all asteroid previously identified as family members by traditional methods are consistently retrieved. Values of the areas under the curve coefficients below Receiver Operating Characteristic curves are also optimal, with values consistently above 85 per cent. Overall, we identify 6 new families and 13 new clumps in regions where the method can be applied that appear to be consistent and homogeneous in terms of physical and taxonomic properties. Machine-learning clustering algorithms can, therefore, be very efficient and fast tools for the problem of asteroid family identification.
Behavioral Interventions for Smokeless Tobacco Cessation
Authors: Nethan Suzanne Tanya , Sinha Dhirendra Narain , Sharma Shashi , Mehrotra Ravi 
Published: June 2019

AbstractIntroductionConsumption of smokeless tobacco (SLT) is on the rise (especially in the World Health Organization South-East Asian region) and has numerous repercussions over the consumer’s health. This article reviews studies performed for SLT cessation using behavioral interventions, worldwide till 2017.MethodsA systematic review by PICO (Problem, intervention, comparison, outcome) of behavioral intervention-based SLT cessation studies with minimum 6 months’ follow-up, reporting outcomes in terms of risk ratios (RRs) and 95% confidence interval (CI), published between 1992 and 2017 was performed. This was followed by a meta-analysis of the outcomes of these studies by deriving the pooled estimates by the random effects model, for those on adults and youth, categorized according to the type of country where the study was performed, that is, in terms of developed or developing. Publication bias among the included studies was assessed by the Begg’s test.ResultsNineteen eligible studies comprising 24 498 participants, from all over the world were included. Behavioral interventions showed overall efficacy in SLT cessation in adults (RR = 1.63, 95% CI = 1.32 to 1.94) both in the developed (RR = 1.39, 95% CI = 1.16 to 1.63) and developing (RR = 2.79, 95% CI = 2.32 to 3.25) countries. However, these interventions did not prove effective for SLT cessation among youth overall (RR = 1.07, 95% CI = 0.73 to 1.41), either in the developed (RR = 1.39, 95% CI = 0.58 to 2.21) or in the developing (RR = 0.87, 95% CI = 0.68 to 1.07) countries. Publication bias was noted in all the studies among adults (p = .22) and youth (p = .05).ConclusionBehavioral interventions as a single modality are effective in SLT cessation, both in the developed and developing countries. Health care providers should be sensitized to provide the same.ImplicationsA recent literature survey by Cochrane reviewed studies on interventions for SLT, including behavioral interventions, which included only those from the developed countries. The current analysis provides a broader, global update on the same by including studies performed both in the developed and developing countries (specifically the South-East Asian region—the high burden countries of SLT products).
Blurred Molecular Epidemiological Lines Between the Two Dominant Methicillin-Resistant Staphylococcus aureus Clones
Authors: Dupper Amy C , Sullivan Mitchell J , Chacko Kieran I , Mishkin Aaron , Ciferri Brianne , Kumaresh Ajay , Berbel Caban Ana , Oussenko Irina , Beckford Colleen , Zeitouni Nathalie E , Sebra Robert , Hamula Camille , Smith Melissa , Kasarskis Andrew , Patel Gopi , McBride Russell B , van Bakel Harm , Altman Deena R 
Published: June 2019

Abstract

Background
Methicillin-resistant Staphylococcus aureus (MRSA) causes life-threatening infections in both community and hospital settings and is a leading cause of health care–associated infections (HAIs). We sought to describe the molecular epidemiological landscape of patients with MRSA bloodstream infections (BSIs) at an urban medical center by evaluating the clinical characteristics associated with the two dominant endemic clones.

Methods
Comprehensive clinical data from the electronic health records of 227 hospitalized patients ≥18 years old with MRSA BSI over a 33-month period in New York City were collected. The descriptive epidemiology and mortality associated with the two dominant clones were compared using logistic regression.

Results
Molecular analysis revealed that 91% of all single-patient MRSA BSIs were due to two equally represented genotypes, clonal complex (CC) 5 (n = 117) and CC8 (n = 110). MRSA BSIs were associated with a 90-day mortality rate of 27%. CC8 caused disease more frequently in younger age groups (56 ± 17 vs 67 ± 17 years old; P &lt; .001) and in those of nonwhite race (odds ratio [OR], 3.45; 95% confidence interval [CI], 1.51–7.87; P = .003), with few other major distinguishing features. Morbidity and mortality also did not differ significantly between the two clones. CC8 caused BSIs more frequently in the setting of peripheral intravenous catheters (OR, 5.96; 95% CI, 1.51–23.50; P = .01).

Conclusions
The clinical features distinguishing dominant MRSA clones continue to converge. The association of CC8 with peripheral intravenous catheter infections underscores the importance of classical community clones causing hospital-onset infections. Ongoing monitoring and analysis of the dynamic epidemiology of this endemic pathogen are crucial to inform management and prevent disease.
Between distribution and allocation: growth models, sectoral coalitions and the politics of taxation revisited
Authors: Haffert Lukas , Mertens Daniel 
Published: June 2019

Abstract
Comparative political economists typically analyze taxation as a matter of distribution. This article, by contrast, develops an allocational explanation of tax policy choices: as taxes channel resources into some economic activities and restrain others, they become subject to the allocational concerns of different sectors of the economy. We argue that sectoral coalitions straddling the class divide substantially influence the development of tax systems, and that the power of these coalitions is associated with differences in growth models. Employing a mixed methods approach, we first demonstrate a systematic association between growth models and consumption taxation across advanced capitalist countries. Afterward, we study the German value-added tax increase in 2005 to illustrate the political dynamics behind this result. In this debate, an export sector coalition prevailed over a domestic sector coalition that strongly opposed the reform. We conclude by discussing the wider implications for the study of taxation and comparative capitalism.
Impact of climate change on insect–human interactions
Authors: Vega Arantza , Castro Leopoldo 
Published: June 2019

Purpose of review
To update the influence of the global climate change on Hymenoptera venom allergy.

Recent findings
Climate change facilitates biological invasions of hymenopteran species and plays a role in the impact of introduced species relevant for human health. It contributes to a rise in the incidence of sting injuries and allergy reactions across the world.

Summary
Global climate change has contributed to the expansion and the redistribution of allergenic insect species, increasing the number of allergy cases caused by stinging insects worldwide. Imported insects are trending species in systemic reactions for multiple stings or hymenopteran venom allergy. They represent a threat for humans and a challenge for the allergists.