bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of the mass ratio in ballistic capture
Authors: Luo Zong-Fu 
Published: August 2020

ABSTRACT
A massless particle can be naturally captured by a celestial body with the aid of a third body. In this work, the influence of the mass ratio on ballistic capture is investigated in the planar circular restricted three-body problem (CR3BP) model. Four typical dynamical environments with decreasing mass ratios, that is, the Pluto–Charon, Earth–Moon, Sun–Jupiter, and Saturn–Titan systems, are considered. A generalized method is introduced to derive ballistic capture orbits by starting from a set of initial conditions and integrating backward in time. Particular attention is paid to the backward escape orbits, following which a test particle can be temporarily trapped by a three-body gravity system, although the particle will eventually deviate away from the system. This approach is applied to the four candidate systems with a series of Jacobi constant levels to survey and compare the capture probability (quantitatively) and capture capability (qualitatively) when the mass ratio varies. Capture mechanisms inducing favourable ballistic capture are discussed. Moreover, the possibility and stability of capture by secondary celestial bodies are analysed. The obtained results may be useful in explaining the capture phenomena of minor bodies or in designing mission trajectories for interplanetary probes.
Tidally trapped pulsations in binary stars
Authors: Fuller J , Kurtz D W , Handler G , Rappaport S 
Published: August 2020

ABSTRACT
A new class of pulsating binary stars was recently discovered, whose pulsation amplitudes are strongly modulated with orbital phase. Stars in close binaries are tidally distorted, so we examine how a star’s tidally induced asphericity affects its oscillation mode frequencies and eigenfunctions. We explain the pulsation amplitude modulation via tidal mode coupling such that the pulsations are effectively confined to certain regions of the star, e.g. the tidal pole or the tidal equator. In addition to a rigorous mathematical formalism to compute this coupling, we provide a more intuitive semi-analytic description of the process. We discuss three resulting effects: (1) Tidal alignment, i.e. the alignment of oscillation modes about the tidal axis rather than the rotation axis; (2) Tidal trapping, e.g. the confinement of oscillations near the tidal poles or the tidal equator; (3) Tidal amplification, i.e. increased flux perturbations near the tidal poles where acoustic modes can propagate closer to the surface of the star. Together, these phenomena can account for the pulsation amplitude and phase modulation of the recently discovered class of ‘tidally tilted pulsators.’ We compare our theory to the three tidally tilted pulsators HD 74423, CO Cam, and TIC 63328020, finding that tidally trapped modes that are axisymmetric about the tidal axis can largely explain the first two, while a non-axisymmetric tidally aligned mode is present in the latter. Finally, we discuss implications and limitations of the theory, and we make predictions for the many new tidally tilted pulsators likely to be discovered in the near future.
Kinematic modelling of clusters with Gaia: the death throes of the Hyades
Authors: Oh Semyeong , Evans Neil Wyn 
Published: August 2020

ABSTRACT
The precision of the Gaia data offers a unique opportunity to study the internal velocity field of star clusters. We develop and validate a forward-modelling method for the internal motions of stars in a cluster. The model allows an anisotropic velocity dispersion matrix and linear velocity gradient describing rotation and shear, combines radial velocities available for a subset of stars, and accounts for contamination from background sources via a mixture model. We apply the method to Gaia DR2 data of the Hyades cluster and its tidal tails, dividing and comparing the kinematics of stars within and beyond 10 pc, which is roughly the tidal radius of the cluster. While the velocity dispersion for the cluster is nearly isotropic, the velocity ellipsoid for the tails is clearly elongated with the major axis pointing towards the Galactic centre. We find positive and negative expansions at ≈2σ significance in Galactic azimuthal and vertical directions for the cluster but no rotation. The tidal tails are stretching in a direction tilted from the Galactic centre while equally contracting as the cluster in Galactic vertical direction. The tails have a shear (A) of 16.90 ± 0.92 $\mathrm{m}\, \mathrm{s}^{-1}\, \mathrm{pc}^{-1}$ and a vorticity (B) of −6.48 ± 1.15 $\mathrm{m}\, \mathrm{s}^{-1}\, \mathrm{pc}^{-1}$, values distinct from the local Oort constants. By solving the Jeans equations for flattened models of the Hyades, we show that the observed velocity dispersions are a factor of ≈2 greater than required for virial equilibrium due to tidal heating and disruption. From simple models of the mass loss, we estimate that the Hyades is close to final dissolution with only a further ≲30 Myr left.
Inverted metallicity gradients in two Virgo cluster star-forming dwarf galaxies: evidence of recent merging?
Authors: Grossi M , García-Benito R , Cortesi A , Gonçalves D R , Gonçalves T S , Lopes P A A , Menéndez-Delmestre K , Telles E 
Published: August 2020

ABSTRACT
We present integral field spectroscopy observations of two star-forming dwarf galaxies in the Virgo cluster (VCC 135 and VCC 324) obtained with Potsdam Multi-Aperture Spectrograph/PPak at the Calar Alto 3.5 m telescope. We derive metallicity maps using the N2 empirical calibrator. The galaxies show positive gas metallicity gradients, contrarily to what is usually found in other dwarfs or spiral galaxies. We measure gradient slopes of 0.20 ± 0.06 and 0.15 ± 0.03 dex/Re for VCC 135 and VCC 324, respectively. Such a trend has been only observed in few, very isolated galaxies or at higher redshifts (z &gt; 1). It is thought to be associated with the accretion of metal-poor gas from the intergalactic medium, a mechanism that would be less likely to occur in a high-density environment like Virgo. We combine emission-line observations with deep optical images to investigate the origin of the peculiar metallicity gradient. The presence of weak underlying substructures in both galaxies and the analysis of morphological diagnostics and ionized gas kinematics suggest that the inflow of metal-poor gas to the central regions of the dwarfs may be related to a recent merging event with a gas-rich companion.
Detecting neutral hydrogen at z ≳ 3 in large spectroscopic surveys of quasars
Authors: Fumagalli Michele , Fotopoulou Sotiria , Thomson Laura 
Published: August 2020

ABSTRACT
We present a pipeline based on a random forest classifier for the identification of high column density clouds of neutral hydrogen (i.e. the Lyman limit systems, LLSs) in absorption within large spectroscopic surveys of z ≳ 3 quasars. We test the performance of this method on mock quasar spectra that reproduce the expected data quality of the Dark Energy Spectroscopic Instrument and the WHT (William Herschel Telescope) Enhanced Area Velocity Explorer surveys, finding ${\gtrsim}90{{\ \rm per\ cent}}$ completeness and purity for $N_{\rm H\,\rm{\small I}} \gtrsim 10^{17.2}~\rm cm^{-2}$ LLSs against quasars of g &lt; 23 mag at z ≈ 3.5–3.7. After training and applying our method on 10 000 quasar spectra at z ≈ 3.5–4.0 from the Sloan Digital Sky Survey (Data Release 16), we identify ≈6600 LLSs with $N_{\rm H\,\rm{\small I}} \gtrsim 10^{17.5}~\rm cm^{-2}$ between z ≈ 3.1 and 4.0 with a completeness and purity of ${\gtrsim}90{{\ \rm per\ cent}}$ for the classification of LLSs. Using this sample, we measure a number of LLSs per unit redshift of ℓ(z) = 2.32 ± 0.08 at z = [3.3, 3.6]. We also present results on the performance of random forest for the measurement of the LLS redshifts and H i column densities, and for the identification of broad absorption line quasars.
Feedback between Sgr A and B: AGN–starburst connection in the galactic centre
Authors: Sofue Yoshiaki 
Published: August 2020

ABSTRACT
Propagation of fast-mode magnetohydrodynamic (MHD) compression waves is traced in the Galactic Centre. MHD waves produced by the active Galactic nucleus (Sgr A) focus on the molecular clouds such as Sgr B in the central molecular zone, which will trigger star formation, or possibly starburst. MHD waves newly excited by the starburst propagate backwards, and focus on the nucleus (Sgr A), where implosive waves compress the nuclear gas to promote fuelling the nucleus and may trigger nucleus activity. Echoing focusing of MHD waves between Sgr A (active galactic nucleus: AGN) and Sgr B (starburst) trigger each other at high efficiency by minimal energy requirement. It also solves the problem of angular momentum for AGN fuelling, as the focusing waves do not require global gas flow.
Occurrence rates of planets orbiting M Stars: applying ABC to Kepler DR25, Gaia DR2, and 2MASS data
Authors: Hsu Danley C , Ford Eric B , Terrien Ryan 
Published: August 2020

ABSTRACT
We present robust planet occurrence rates for Kepler planet candidates around M stars for planet radii Rp = 0.5–4 R⊕ and orbital periods P = 0.5–256 d using the approximate Bayesian computation technique. This work incorporates the final Kepler DR25 planet candidate catalogue and data products and augments them with updated stellar properties using Gaia DR2 and 2MASS point source catalogue. We apply a set of selection criteria to select a sample of 1746 Kepler M dwarf targets that host 89 associated planet candidates. These early-type M dwarfs and late K dwarfs were selected from cross-referenced targets using several photometric quality flags from Gaia DR2 and colour–magnitude cuts using 2MASS magnitudes. We estimate a habitable zone occurrence rate of $f_{\textrm {M,HZ}} = 0.33^{+0.10}_{-0.12}$ for planets with 0.75–1.5 R⊕ size. We caution that occurrence rate estimates for Kepler M stars are sensitive to the choice of prior due to the small sample of target stars and planet candidates. For example, we find an occurrence rate of $4.2^{+0.6}_{-0.6}$ or $8.4^{+1.2}_{-1.1}$ planets per M dwarf (integrating over Rp = 0.5–4 R⊕ and P = 0.5–256 d) for our two choices of prior. These occurrence rates are greater than those for FGK dwarf target when compared at the same range of orbital periods, but similar to occurrence rates when computed as a function of equivalent stellar insolation. Combining our result with recent studies of exoplanet architectures indicates that most, and potentially all, early-type M dwarfs harbour planetary systems.
Drifting through the medium: kicks and self-propulsion of binaries within accretion discs and other environments
Authors: Cardoso Vitor , Macedo Caio F B 
Published: August 2020

ABSTRACTCompact binaries are within the reach of gravitational and electromagnetic wave detectors, and are important for our understanding of astrophysical environments and the composition of compact objects. There is a vast body of work devoted to the evolution of such binaries in background media, such as in common-envelope evolution, accretion discs and dark matter mini spikes. Here, we explore further gravitationally bound binaries evolving within an environment. We show that dissipative effects such as gravitational drag and accretion impart a momentum to the centre of mass (CM) of asymmetric binaries. We numerically evolve the binaries in a Newtonian setup and show that, depending on the medium density, the CM can accelerate to high speeds – in some cases $300\, {\rm km\, s^{-1}}$ or more – during inspiral, with potentially observable signatures. Our numerical results are fully consistent with an analytical result for the CM evolution at first order in the medium density.
Compliance of Oral Snuff (Naswar) Packaging and Sales Practices with National Tobacco Control Laws and the Relevant Articles of Framework Convention on Tobacco Control in Khyber Pakhtunkhwa Pakistan
Authors: Ahmad Fayaz , Khan Zohaib , Siddiqi Kamran , Khan Muhammad Naseem , Boeckman Melanie , Dregger Steffen , Bauld Linda , Zeeb Hajo , Forberger Sarah 
Published: August 2020

Abstract

Introduction
Smokeless tobacco (SLT) is a significant contributor to tobacco-related harm in Pakistan but its control has lags behind that of combustible tobacco. We assessed the compliance of Naswar’s (a widely used SLT product in the Southeast Asia) packaging and sales practices with the national legislations and relevant articles of the WHO framework convention on tobacco control (FCTC).

Aims and Methods
A cross-sectional observational audit was conducted in three districts of Pakistan. We recruited 286 general point of sale (GPOS) and exclusive Naswar sellers (ENS) through a multistage cluster sampling strategy. Data were gathered on packaging and labeling practices of Naswar and advertisement and promotion practices inside and outside the shops. Statistical tests for association between the dependent variable-advertisement practices, and independent variables-area and vendor types were conducted.

Results
We analyzed 133 and 49 unique Naswar products sold in 229 GPOS and by 57 ENS, respectively. None of the local products had any written or pictorial health warning. More than half of retailers used one or two methods of advertising Naswar inside the shops while only 9% advertised outside the shops. ENS were more likely to be noncompliant with tobacco advertisement and promotion compared with GPOS.

Conclusions
The study presents first insights on the compliance of Naswar packaging and sale practices with local regulations and WHO FCTC provisions in Pakistan. Almost all products were on display in the shops and none of the local products had any health warning or contents disclosure on the packages.

Implications
Naswar is a form of SLT used extensively in Pakistan, Central Asia, and Pashtun populations across the globe. This study provides an important insight into the Naswar retail environment in a geographical setting where the use of Naswar is endemic. The study brings to fore previously unreported issues like an urban–rural disparity, and differences between exclusive and nonENS, with regards to Naswar advertisement and promotion. These findings have potential implication on the implementation of tobacco control retail policies. The lack of health warnings and free display of Naswar brands call for alignment of tobacco control efforts with the FCTC.
Repurposing Metformin in Nondiabetic People With HIV: Influence on Weight and Gut Microbiota
Authors: Isnard Stéphane , Lin John , Fombuena Brandon , Ouyang Jing , Varin Thibault V , Richard Corentin , Marette André , Ramendra Rayoun , Planas Delphine , Raymond Marchand Laurence , Messaoudene Meriem , Van der Ley Claude P , Kema Ido P , Sohail Ahmed Darakhshan , Zhang Yonglong , Finkelman Malcolm , Routy Bertrand , Angel Jonathan , Ancuta Petronela , Routy Jean-Pierre 
Published: August 2020

Abstract

Background
People with HIV (PWH) taking antiretroviral therapy (ART) may experience weight gain, dyslipidemia, increased risk of non-AIDS comorbidities, and long-term alteration of the gut microbiota. Both low CD4/CD8 ratio and chronic inflammation have been associated with changes in the gut microbiota of PWH. The antidiabetic drug metformin has been shown to improve gut microbiota composition while decreasing weight and inflammation in diabetes and polycystic ovary syndrome. Nevertheless, it remains unknown whether metformin may benefit PWH receiving ART, especially those with a low CD4/CD8 ratio.

Methods
In the Lilac pilot trial, we recruited 23 nondiabetic PWH receiving ART for more than 2 years with a low CD4/CD8 ratio (&lt;0.7). Blood and stool samples were collected during study visits at baseline, after a 12-week metformin treatment, and 12 weeks after discontinuation. Microbiota composition was analyzed by 16S rDNA gene sequencing, and markers of inflammation were assessed in plasma.

Results
Metformin decreased weight in PWH, and weight loss was inversely correlated with plasma levels of the satiety factor GDF-15. Furthermore, metformin changed the gut microbiota composition by increasing the abundance of anti-inflammatory bacteria such as butyrate-producing species and the protective Akkermansia muciniphila.

Conclusions
Our study provides the first evidence that a 12-week metformin treatment decreased weight and favored anti-inflammatory bacteria abundance in the microbiota of nondiabetic ART-treated PWH. Larger randomized placebo-controlled clinical trials with longer metformin treatment will be needed to further investigate the role of metformin in reducing inflammation and the risk of non-AIDS comorbidities in ART-treated PWH.
Sleep quality relates to emotional reactivity via intracortical myelination
Authors: Toschi Nicola , Passamonti Luca , Bellesi Michele 
Published: August 2020

AbstractA good quality and amount of sleep are fundamental to preserve cognition and affect. New evidence also indicates that poor sleep is detrimental to brain myelination. In this study, we test the hypothesis that sleep quality and/or quantity relate to variability in cognitive and emotional function via the mediating effect of interindividual differences in proxy neuroimaging measures of white matter integrity and intracortical myelination. By employing a demographically and neuropsychologically well-characterized sample of healthy people drawn from the Human Connectome Project (n = 974), we found that quality and amount of sleep were only marginally linked to cognitive performance. In contrast, poor quality and short sleep increased negative affect (i.e. anger, fear, and perceived stress) and reduced life satisfaction and positive emotionality. At the brain level, poorer sleep quality and shorter sleep duration related to lower intracortical myelin in the mid-posterior cingulate cortex (p = 0.038), middle temporal cortex (p = 0.024), and anterior orbitofrontal cortex (OFC, p = 0.034) but did not significantly affect different measures of white matter integrity. Finally, lower intracortical myelin in the OFC mediated the association between poor sleep quality and negative emotionality (p &lt; 0.05). We conclude that intracortical myelination is an important mediator of the negative consequences of poor sleep on affective behavior.
Do Alignment and Trimming Methods Matter for Phylogenomic (UCE) Analyses?
Authors: Portik Daniel M , Wiens John J 
Published: August 2020

Abstract
Alignment is a crucial issue in molecular phylogenetics because different alignment methods can potentially yield very different topologies for individual genes. But it is unclear if the choice of alignment methods remains important in phylogenomic analyses, which incorporate data from hundreds or thousands of genes. For example, problematic biases in alignment might be multiplied across many loci, whereas alignment errors in individual genes might become irrelevant. The issue of alignment trimming (i.e., removing poorly aligned regions or missing data from individual genes) is also poorly explored. Here, we test the impact of 12 different combinations of alignment and trimming methods on phylogenomic analyses. We compare these methods using published phylogenomic data from ultraconserved elements (UCEs) from squamate reptiles (lizards and snakes), birds, and tetrapods. We compare the properties of alignments generated by different alignment and trimming methods (e.g., length, informative sites, missing data). We also test whether these data sets can recover well-established clades when analyzed with concatenated (RAxML) and species-tree methods (ASTRAL-III), using the full data ($\sim $5000 loci) and subsampled data sets (10% and 1% of loci). We show that different alignment and trimming methods can significantly impact various aspects of phylogenomic data sets (e.g., length, informative sites). However, these different methods generally had little impact on the recovery and support values for well-established clades, even across very different numbers of loci. Nevertheless, our results suggest several “best practices” for alignment and trimming. Intriguingly, the choice of phylogenetic methods impacted the phylogenetic results most strongly, with concatenated analyses recovering significantly more well-established clades (with stronger support) than the species-tree analyses. [Alignment; concatenated analysis; phylogenomics; sequence length heterogeneity; species-tree analysis; trimming]
A new elasmosaurid plesiosaurian from the Early Cretaceous of Russia marks an early attempt at neck elongation
Authors: Fischer Valentin , Zverkov Nikolay G , Arkhangelsky Maxim S , Stenshin Ilya M , Blagovetshensky Ivan V , Uspensky Gleb N 
Published: August 2020

AbstractPlesiosaurian marine reptiles evolved a wide range of body shapes during the Jurassic and Cretaceous, including long-necked forms. Many Late Cretaceous members of the clade Elasmosauridae epitomized this part of the plesiosaurian morphological spectrum by evolving extremely long necks through somitogenesis (resulting in an increase in the number of cervical centra) and differential growth (resulting in the elongation of cervical centra). However, the early evolution of elasmosaurids remains poorly understood because of a generally poor Lower Cretaceous fossil record. We describe a new elasmosaurid, Jucha squalea gen. et sp. nov., from the upper Hauterivian (Lower Cretaceous) of Ulyanovsk (European Russia), in addition to other elasmosaurid remains from the same area. Jucha squalea is one of the oldest and basalmost elasmosaurids known and lacks a series of features that otherwise characterize the group, such as the heart-shaped intercoracoid fenestra and the median pectoral bar. However, Jucha squalea marks an early attempt at cervical elongation through differential growth. The data we gathered on the shape of cervical centra among elasmosaurids suggest multiple episodes of elongation and shortening. However, the precise patterns are obscured by an unstable phylogenetic signal.
Innovation in Nurse Residency: Blazing a Trail With Online Technology
Authors: Weathers Nicole M. , Forneris Lori A. 
Published: August 2020

Abstract
To prepare new graduate nurses for the work of the future, the Iowa Action Coalition identified implementation of nurse residency as a top priority. A taskforce of Iowa nurse leaders developed a turn-key program for all sizes and types of health care organizations, available as all online and blended options. Implementation provided statistically significant outcomes similar to traditional programs. Innovation continues to drive the program with transition to an RN residency apprenticeship. This work is a testament to how innovation can be used to prepare our nursing workforce for the future, foster collaboration through partnerships, and advance nursing research.
Lessons Learned: Utilizing the NEWS Tool in High-Fidelity Simulation
Authors: Wiles Brenda , Alfes Celeste M. , Dolansky Mary 
Published: August 2020

Abstract
Nurse educators can enhance students’ clinical judgment by providing cues to guide decision-making during simulation. The purpose of this experimental feasibility study was to evaluate the effectiveness of using the National Early Warning Score as a set of cues during high-fidelity simulation to guide students in the development of clinical judgment, resulting in early detection of patient deterioration. Differences in clinical judgment scores and speed of detection of patient deterioration between groups of junior-level nursing students trained in the use of National Early Warning Score versus those who were not were evaluated. No significant differences were detected between the groups; however, valuable lessons were learned.