bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity of plazomicin against carbapenem-intermediate or -resistantEscherichia coliisolates from the United States and international sites in relation to clonal background, resistance genes, co-resistance, and region
Authors: Johnston Brian D , Thuras Paul , Porter Stephen B , Anacker Melissa , VonBank Brittany , Snippes Vagnone Paula , Witwer Medora , Castanheira Mariana , Johnson James R
Published: April 2021

Background

Emerging carbapenem resistance in Escherichia coli, including sequence type 131 (ST131), threatens therapeutic efficacy. Plazomicin (PLZ), a semisynthetic aminoglycoside approved by the FDA in 2018, overcomes the most common aminoglycoside resistance mechanisms and maintains activity against many carbapenem-intermediate or -resistant (CIR) E. coli strains.

Objectives

To assess plazomicin susceptibility among CIR E. coli in relation to region and multiple bacterial characteristics.

Methods

We determined broth microdilution MICs for plazomicin and 11 comparators against 343 CIR clinical E. coli isolates, then compared susceptibility results by bacterial characteristics and region. The collection comprised 203 US isolates (2002–17) and 141 isolates from 17 countries in Europe, Latin America, and the Asia-West Pacific region (2003–17). Isolates were characterized for phylogenetic group, resistance-associated sequence types (STs) and subsets thereof, and relevant β-lactamase-encoding genes.

Results

Plazomicin exhibited the highest percentage susceptible (89%) after tigecycline (99%). The percentage susceptible to plazomicin varied significantly by phylogroup (63%, group B1; versus >93%, others) and ST131 subclone (92%, H30Rx; versus 87%–89%, H30R1 and non-H30), but not ST. It also varied by resistance genotype [higher with Klebsiella pneumoniae carbapenemase (KPC), lower with metallo-β-lactamases], global region [highest for Latin America (94%), lowest for Asia-West Pacific (69%)], and US region (80%, South, versus 96%–100%, others). Although reduced susceptibility to comparators often predicted reduced susceptibility to plazomicin, even among comparator-intermediate or -resistant isolates the plazomicin-susceptible fraction was ≥77%, except for amikacin (53%).

Conclusions

The likely utility of plazomicin against CIR E. coli is high overall, but varies with region and multiple bacterial characteristics.
Antibiotic exposure and the risk of hospital-acquired diarrhoea and Clostridioides difficile infection: a cohort study
Authors: Schechner Vered , Fallach Noga , Braun Tali , Temkin Elizabeth , Carmeli Yehuda
Published: April 2021

Background

Hospital-acquired diarrhoea (HAD) and Clostridioides difficile infection (CDI) may be triggered by antibiotic use.

Objectives

To determine the effect of specific antibiotic agents and duration of therapy on the risk of HAD and CDI.

Patients and methods

A single-centre retrospective cohort study was conducted between May 2012 and December 2014 in the internal medicine division. HAD was defined based on documentation of diarrhoea in the medical record or an uncancelled C. difficile test in the laboratory database. CDI was diagnosed using a two-step test (initial glutamate dehydrogenase and toxin A/B EIA, with PCR for discrepant results). Outcomes first occurred on hospital Day 4 or later. Treatment with antibiotics and days of therapy were modelled.

Results

In 29 063 hospitalizations there were 970 HAD events [incidence rate per 10 000 patient days (IR) = 38.5] and 105 CDI events (IR = 3.9). Any antibiotic treatment increased the risk of HAD [adjusted relative risk (aRR) 2.79; 95% CI 2.27–3.43] and CDI (aRR 5.31; 95% CI 2.23–12.69). Each day of β-lactam/β-lactamase inhibitors (βL/βLIs), carbapenems, IV glycopeptides and metronidazole increased the risk of HAD. Each day of βL/βLIs, third- and fourth-generation cephalosporins and carbapenems increased the risk of CDI by over 2%.

Conclusions

Preventing HAD and CDI should focus on reducing the overall use of antibiotics and shortening antibiotic exposure, rather than focusing on specific agents.
Antiretroviral drug exposure in urethral and glans surface sampling of the penis
Authors: Haaland Richard E. , Fountain Jeffrey , Dinh Chuong , Lupo L. Davis , Martin Amy , Conway-Washington Christopher , Hall LaShonda , Kelley Colleen F. , Garcia-Lerma J. Gerardo , Heneine Walid
Published: April 2021

Background

HIV exposure to penile tissues provides a risk of acquisition among men, yet studies evaluating penile antiretroviral (ARV) drug distribution have been lacking. We measured ARVs on urethral and glans surface swabs collected following a dose of tenofovir alafenamide, emtricitabine, elvitegravir, darunavir and cobicistat.

Methods

Thirty-five HIV-negative male participants provided urethral swabs, glans swabs, rectal swabs, blood and urine up to 96 h following a single dose of tenofovir alafenamide/emtricitabine/elvitegravir/cobicistat and darunavir. ARVs were measured by liquid chromatography–mass spectrometry with a lower limit of detection (LOD) of 1 ng/swab for swabs and 10 ng/mL for plasma and urine. Concentrations are reported as median and range.

Results

Urethral swab emtricitabine and darunavir concentrations peaked at 4 h for emtricitabine (36 ng/swab; 3–307 ng/swab) and 8 h for darunavir (25 ng/swab; 2–52 ng/swab). Glans swab emtricitabine and darunavir concentrations peaked 24 h after dosing (emtricitabine 14 ng/swab, <LOD–328 ng/swab; darunavir 6 ng/swab, <LOD–149 ng/swab). Estimated peak urethral secretion emtricitabine and darunavir concentrations are between 10 and 20 μg/mL, similar to rectal secretions, 4-fold greater than in plasma, but 2-fold lower than in urine. Tenofovir and elvitegravir were detected on less than 20% of urethral or glans swabs collected within 24 h of dosing.

Conclusions

We document ARV dosing in the urethra and on the glans surface with high drug concentrations noted for emtricitabine and darunavir and lower tenofovir and elvitegravir concentrations. Data suggest a potential protective role of urethral emtricitabine or darunavir against penile HIV acquisition.
Medical Summary Template for the Transfer of Patients with Inflammatory Bowel Disease from Pediatric to Adult Care
Authors: Benchimol Eric I , Afif Waqqas , Plamondon Sophie , Newhook Dennis , Nicholls Stuart G , Lévesque Dominique
Published: April 2021

Background

The transfer of information is a key aspect of the transition of adolescent patients with inflammatory bowel disease (IBD) from pediatric to adult care. This is typically accomplished through the use of a consultation letter with a medical summary of the patient being transferred. To improve the quality and completeness of information included in a transfer letter, we developed a standardized medical summary template by integrating the feedback of adult and pediatric health care providers.

Methods

To develop the letter template, we purposively sampled gastroenterologists or nurse practitioners caring for patients with IBD in four Canadian cities and invited them to take part in focus group discussions. Using a semi-structured approach, we explored the items deemed essential for inclusion in a transfer summary. Using the conventional content analysis framework, the focus group discussions were inductively coded to identify areas of priority for inclusion in the template.

Results

Four focus groups were conducted, comprising 17 health care providers of 30 invited (56.7% participation). The resulting medical summary template included the following major headings: patient/disease characteristics, therapeutics history (including medications and surgeries), clinical history and current status, noteworthy investigations, history of complications (including hospitalizations), family history, immunization history and psychosocial history. The template also addressed health system process factors (i.e., urgency of transfer, mode of delivery and confidentiality) to ensure a seamless transfer to adult care.

Conclusions

The standardized medical summary template should be used by pediatric providers to ensure that essential patient information and disease characteristics are sent to an adult provider.
Effect of Chilling on Quality Control Parameters of Sterile Queensland Fruit Fly (Diptera: Tephritidae)
Authors: Gaire Sushil K , Biswas Md Jamil Hossain , Benelli Maurizio , Rempoulakis Polychronis , Taylor Phillip W , Mainali Bishwo P
Published: April 2021

Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt), presents a major threat to Australian fruit production and trade. The sterile insect technique (SIT) is increasingly employed to manage Q-fly. Quality of sterile males released in SIT programs, and hence program efficacy, can be affected by pre- and post-production processes, such as mass rearing, packing, irradiation, transportation, and release. Given long distances from rear-out facilities to release sites, adult flies are usually chilled to reduce metabolism and stress during transportation. To guide SIT procedures, it is important to understand the impact of such practices on performance of sterile Q-fly. The present study assesses the effect of chilling temperature and exposure period on quality parameters of sterile Q-fly. We considered the effects of two temperature regimes (4 and 6°C) and six exposure periods (0, 1, 2, 4, 6, and 12 h) on chill-coma recovery time, flight ability, survival under nutritional stress, and longevity of both males and females. Flies chilled at 4°C took longer to recover than that those chilled at 6°C. Flight ability, survival under nutritional stress, and longevity all decreased as chilling period increased but did not differ between the two tested temperatures. We recommend that periods of chilling during transportation from rear-out facilities to release sites be minimized in order to retain quality of sterile Q-fly and that increased release rates be considered when longer chilling periods are required.
Topical Review: Medical Trauma During Early Childhood
Authors: De Young Alexandra C , Paterson Rebecca S , Brown Erin A , Egberts Marthe R , Le Brocque Robyne M , Kenardy Justin A , Landolt Markus A , Marsac Meghan L , Alisic Eva , Haag Ann-Christin
Published: April 2021

Objective

Early childhood is a high-risk period for exposure to traumatic medical events due to injury/illness. It is also one of the most important and vulnerable periods due to rapid development in neurobiological systems, attachment relationships, cognitive and linguistic capacities, and emotion regulation. The aim of this topical review is to evaluate empirical literature on the psychological impact of medical trauma during early childhood (0–6 years) to inform models of clinical care for assessing, preventing, and treating traumatic stress following injury/illness.

Methods

Topical review of empirical and theoretical literature on pediatric medical traumatic stress (PMTS) during early childhood.

Results

There are important developmental factors that influence how infants and young children perceive and respond to medical events. The emerging literature indicates that up to 30% of young children experience PMTS within the first month of an acute illness/injury and between 3% and 10% develop posttraumatic stress disorder. However, significant knowledge gaps remain in our understanding of psychological outcomes for infants and young children, identification of risk-factors and availability of evidence-based interventions for medical trauma following illness.

Conclusions

This topical review on medical trauma during early childhood provides: (a) definitions of key medical trauma terminology, (b) discussion of important developmental considerations, (c) summary of the empirical literature on psychological outcomes, risk factors, and interventions, (d) introduction to a stepped-model-of-care framework to guide clinical practice, and (e) summary of limitations and directions for future research.
Andexanet Alfa Use for Small Bowel Obstruction Patient With History of Sugiura Procedure
Authors: Brust Adam K , LeCourt Amarateedha P , Benham Derek A , Gower Jonathan R , Birmingham Sean D
Published: April 2021

This case report is about a 51-year-old active duty male with JAK2 mutation and medical history significant for prehepatic portal hypertension from portal vein thrombus on lifelong anticoagulation with rivaroxaban, an oral factor Xa inhibitor, presenting with closed-loop small bowel obstruction requiring emergent laparotomy. We present this surgical case as it required emergent reversal of the oral factor Xa inhibitor with andexanet alfa.
Galaxy zoo builder: Morphological dependence of spiral galaxy pitch angle
Authors: Lingard Timothy , Masters Karen L , Krawczyk Coleman , Lintott Chris , Kruk Sandor , Simmons Brooke , Keel William , Nichol Robert C , Baeten Elisabeth
Published: April 2021

Spiral structure is ubiquitous in the Universe, and the pitch angle of arms in spiral galaxies provide an important observable in efforts to discriminate between different mechanisms of spiral arm formation and evolution. In this paper, we present a hierarchical Bayesian approach to galaxy pitch angle determination, using spiral arm data obtained through the Galaxy Builder citizen science project. We present a new approach to deal with the large variations in pitch angle between different arms in a single galaxy, which obtains full posterior distributions on parameters. We make use of our pitch angles to examine previously reported links between bulge and bar strength and pitch angle, finding no correlation in our data (with a caveat that we use observational proxies for both bulge size and bar strength which differ from other work). We test a recent model for spiral arm winding, which predicts uniformity of the cotangent of pitch angle between some unknown upper and lower limits, finding our observations are consistent with this model of transient and recurrent spiral pitch angle as long as the pitch angle at which most winding spirals dissipate or disappear is larger than 10°.
Good and proper: self-similarity of N-body simulations with proper force softening
Authors: Garrison Lehman H , Joyce Michael , Eisenstein Daniel J
Published: April 2021

Analysis of self-similarity in scale-free N-body simulations reveals the spatial and temporal scales for which statistics measured in cosmological simulations are converged to the physical continuum limit. We examine how the range of scales in which the two-point correlation function is converged depends on the force softening length and whether it is held constant in comoving or proper coordinates. We find that a proper softening that reaches roughly 1/30th of the inter-particle spacing by the end of the simulation resolves the same spatial and temporal scales as a comoving softening of the same length while using a third fewer time-steps, for a range of scale factors typical to Lambda cold dark matter (ΛCDM) simulations. We additionally infer an inherent resolution limit, set by the particle mass and scaling as a−1/2, beyond which reducing the softening does not improve the resolution. We postulate a mapping of these results with spectral index n = −2 to ΛCDM simulations.
A light echo from the warm outflow in the ULIRG F01004-2237 following a major flare in its optical continuum emission
Authors: Tadhunter C , Patel M , Mullaney J
Published: April 2021

Emission-line variability studies have the potential to provide key information about the structures of the near-nuclear outflow regions of active galactic nuclei (AGN). Here we present a VLT/Xshooter spectrum of the nucleus of the ULIRG F01004-2237 that was taken in 2018 August, about 8 yr after a major flare in its integrated optical emission. Compared with our WHT/ISIS spectrum from 2015 September, the broad, red wings of the emission lines most closely associated with the flaring event, including He iiλ4686, N iiiλλ4640,4100, and He iλ5876, have substantially declined in flux. In contrast, the broad, blue wings that dominate the [O iii], [Ne iii], [Ne v], and [O i] forbidden lines have increased in flux by a factor 1.4–4.4 (depending on the line). Moreover, the [Fe vii]λ6087 line is detected in the new spectrum for the first time. We interpret these results in terms of a light echo from the outflowing warm gas: the direct emission from the flaring event is continuing to fade, but due to light travel time effects we are only now observing the impact of the flare on the emission from the extended outflow region. Unless the outflow is confined to a small range of angles close to our line of sight, these observations imply that the outflow must be relatively compact (r <50 pc). In terms of the nature of the flare event, we speculate that the properties of the F01004-2237 flare may be the result of a tidal disruption event occurring in an object with pre-existing AGN activity.
Hybrid analytic and machine-learned baryonic property insertion into galactic dark matter haloes
Authors: Moews Ben , Davé Romeel , Mitra Sourav , Hassan Sultan , Cui Weiguang
Published: April 2021

While cosmological dark matter-only simulations relying solely on gravitational effects are comparably fast to compute, baryonic properties in simulated galaxies require complex hydrodynamic simulations that are computationally costly to run. We explore the merging of an extended version of the equilibrium model, an analytic formalism describing the evolution of the stellar, gas, and metal content of galaxies, into a machine learning framework. In doing so, we are able to recover more properties than the analytic formalism alone can provide, creating a high-speed hydrodynamic simulation emulator that populates galactic dark matter haloes in N-body simulations with baryonic properties. While there exists a trade-off between the reached accuracy and the speed advantage this approach offers, our results outperform an approach using only machine learning for a subset of baryonic properties. We demonstrate that this novel hybrid system enables the fast completion of dark matter-only information by mimicking the properties of a full hydrodynamic suite to a reasonable degree, and discuss the advantages and disadvantages of hybrid versus machine learning-only frameworks. In doing so, we offer an acceleration of commonly deployed simulations in cosmology.
Ionizing feedback from an O star formed in a filament
Authors: Whitworth A P , Priestley F D
Published: April 2021

We explore a simple semi-analytic model for what happens when an O star (or cluster of O stars) forms in an isolated filamentary cloud. The model is characterized by three configuration parameters: the radius of the filament, $R_{_{\rm FIL}}$, the mean density of H2 in the filament, $n_{_{\rm FIL}}$, and the rate at which the O star emits ionizing photons, $\dot{\cal N}_{_{\rm LyC}}$. We show that for a wide range of these configuration parameters, ionizing radiation from the O star rapidly erodes the filament, and the ionized gas from the filament disperses into the surroundings. Under these circumstances the distance, L, from the O star to the ionization front (IF) is given approximately by $L(t) \sim 5.2 {\rm pc} [R_{_{\rm FIL}}/0.2 {\rm pc}]^{-1/6} [n_{_{\rm FIL}}/10^4 {\rm cm^{-3}}]^{-1/3} [\dot{\cal N}_{_{\rm LyC}}/10^{49} {\rm s}^{-1}]^{1/6} [t/{\rm Myr}]^{2/3}$, and we derive similar simple power-law expressions for other quantities, for example the rate at which ionized gas boils off the filament, $\dot{M}_{_{\rm IF}}(t)$, and the mass, $M_{_{\rm SCL}}(t)$, of the shock-compressed layer that is swept up behind the IF. We show that a very small fraction of the ionizing radiation is expended locally, and a rather small amount of molecular gas is ionized and dispersed. We discuss some features of more realistic models, and the extent to which they might modify or invalidate the predictions of this idealized model. In particular we show that, for very large $R_{_{\rm FIL}}$ and/or large $n_{_{\rm FIL}}$ and/or low $\dot{\cal N}_{_{\rm LyC}}$, continuing accretion on to the filament might trap the ionizing radiation from the O star, slowing erosion of the filament even further.
Caught in the act: core-powered mass-loss predictions for observing atmospheric escape
Authors: Gupta Akash , Schlichting Hilke E
Published: April 2021

Past studies have demonstrated that atmospheric escape by the core-powered mass-loss mechanism can explain a multitude of observations associated with the radius valley that separates the super-Earth and sub-Neptune planet populations. Complementing such studies, in this work, we present a shortlist of planets that could be losing their atmospheres today if their evolution is indeed primarily dictated by core-powered mass-loss. We use Bayesian inference analysis on our planet evolution and mass-loss model to estimate the posteriors of the parameters that encapsulate the current state of a given planet, given their published masses, radii, and host star properties. Our models predict that the following planets could be losing their atmospheres today at a rate ≳107 g s−1 at 50 per cent confidence level: pi Men c, Kepler-60 d, Kepler-60 b, HD 86226 c, EPIC 249893012 b, Kepler-107 c, HD 219134 b, Kepler-80 e, Kepler-138 d, and GJ 9827 d. As a by-product of our Bayesian inference analysis, we were also able to identify planets that most-likely harbour either secondary atmospheres abundant with high mean-molecular weight species, low-density interiors abundant with ices, or both. The planets belonging to this second category are WASP-47 e, Kepler-78 b, Kepler-10 b, CoRoT-7 b, HD 80653 b, 55 Cnc e, and Kepler-36 b. While the aforementioned lists are by no means exhaustive, we believe that candidates presented here can serve as useful input for target selection for future surveys and for testing the importance of core-powered mass-loss in individual planetary systems.
Characterization of lensing selection effects for LISA massive black hole binary mergers
Authors: Cusin Giulia , Tamanini Nicola
Published: April 2021

We present a method to include lensing selection effects due to the finite horizon of a given detector when studying lensing of gravitational wave (GW) sources. When selection effects are included, the mean of the magnification distribution is shifted from one to higher values for sufficiently high-redshift sources. This introduces an irreducible (multiplicative) bias on the luminosity distance reconstruction, in addition to the typical source of uncertainty in the distance determination. We apply this method to study lensing of GWs emitted by massive black hole binary mergers at high redshift detectable by Laser Interferometer Space Antenna (LISA). We estimate the expected bias induced by selection effects on the luminosity distance reconstruction as function of cosmological redshift, and discuss its implications for cosmological and astrophysical analyses with LISA. We also reconstruct the distribution of lensing magnification as a function of the observed luminosity distance to a source, which is the observable quantity in the absence of an electromagnetic counterpart. Lensing provides the dominant source of errors in distance measurements of high-redshift GW sources. Its full characterization, including the impact of selection effects, is of paramount importance to correctly determine the astrophysical properties of the underlying source population and to be able to use GW sources as a new cosmological probe.
AGNs in small galaxy systems: comparing the main properties of active objects in pairs, triplets, and groups
Authors: Duplancic Fernanda , Lambas Diego G , Alonso Sol , Coldwell Georgina V
Published: April 2021

We perform a comparative study of active galactic nuclei (AGNs) in pairs, triplets, and groups. To this end, we use the Duplancic et al. catalogue of small galaxy systems and consider BPT and WHAN diagnostic diagrams to select optical AGNs. Also, we identify mid-IR AGNs by using WISE data. We performed a comparison between the different AGN classification methodologies and study the AGN fraction in pairs, triplets, and groups with four to six members. We also analyse the main properties of Optical and mid-IR AGN hosts and the influence of environment on the active nuclei phenomena in these small galaxy systems. Our results show that, regardless the specifically adopted classification scheme, the fraction of AGN in pairs and triplets is always higher than the corresponding fraction in groups. Moreover, the fraction of powerful AGNs in pair and triplets is about twice the fraction of regular AGNs. We also find a remarkable difference between Optical and mid-IR AGNs in groups, where host galaxies of WISE AGNs are less massive and concentrated, with young stellar populations and blue colours. Also, all WISE AGNs in groups have a very close companions and reside in an intermediate global density environment. Galaxy triplets show a larger AGN fraction for galaxies with a close nearest neighbours, while pairs present a nearly constant AGN fraction regardless the distance to the nearest companion. Our studies highlight the important role of interactions, besides the global environment dependence, in the activation of the AGN phenomenon in small galaxy systems.
Protocluster detection in simulations of HSC–SSP and the 10-yr LSST forecast, using PCcones
Authors: Araya-Araya Pablo , Vicentin Marcelo C , Sodré Laerte , Overzier Roderik A , Cuevas Hector
Published: April 2021

The progenitors of present-day galaxy clusters give important clues about the evolution of the large-scale structure, cosmic mass assembly, and galaxy evolution. Simulations are a major tool for these studies since they are used to interpret observations. In this work, we introduce a set of ‘protocluster-light-cones’, dubbed PCcones. They are mock galaxy catalogues generated from the Millennium Simulation with the L-GALAXIES semi-analytic model. These light-cones were constructed by placing a desired structure at the redshift of interest in the centre of the cone. This approach allows to adopt a set of observational constraints, such as magnitude limits and uncertainties in magnitudes and photometric redshifts (photo-zs) to produce realistic simulations of photometric surveys. We show that photo-zs obtained with PCcones are more accurate than those obtained directly with the Millennium Simulation, mostly due to the difference in how apparent magnitudes are computed. We apply PCcones in the determination of the expected accuracy of protocluster detection using photo-zs in the z = 1−3 range in the wide layer of HSC–SSP and the 10-yr LSST forecast. With our technique, we expect to recover only $\sim 38{{\ \rm per\ cent}}$ and $\sim 43{{\ \rm per\ cent}}$ of all massive galaxy cluster progenitors with more than 70 per cent of purity for HSC–SSP and LSST, respectively. Indeed, the combination of observational constraints and photo-z uncertainties affects the detection of structures critically for both emulations, indicating the need of spectroscopic redshifts to improve detection. We also compare our mocks of the Deep CFHTLS at z < 1.5 with observed cluster catalogues, as an extra validation of the light-cones and methods.
Deciphering the origin of ionized gas in IC 1459 with VLT/MUSE
Authors: Mulcahey C R , Prichard L J , Krajnović D , Jorgenson R A
Published: April 2021

IC 1459 is an early-type galaxy (ETG) with a rapidly counter-rotating stellar core, and is the central galaxy in a gas-rich group of spirals. In this work, we investigate the abundant ionized gas in IC 1459 and present new stellar orbital models to connect its complex array of observed properties and build a more complete picture of its evolution. Using the Multi-Unit Spectroscopic Explorer (MUSE), the optical integral field unit (IFU) on the Very Large Telescope (VLT), we examine the gas and stellar properties of IC 1459 to decipher the origin and powering mechanism of the galaxy’s ionized gas. We detect ionized gas in a non-disc-like structure rotating in the opposite sense to the central stars. Using emission-line flux ratios and velocity dispersion from full-spectral fitting, we find two kinematically distinct regions of shocked emission-line gas in IC 1459, which we distinguished using narrow (σ ≤ 155 km s−1) and broad (σ > 155 km s−1) profiles. Our results imply that the emission-line gas in IC 1459 has a different origin than that of its counter-rotating stellar component. We propose that the ionized gas is from late-stage accretion of gas from the group environment, which occurred long after the formation of the central stellar component. We find that shock heating and AGN activity are both ionizing mechanisms in IC 1459 but that the dominant excitation mechanism is by post-asymptotic giant branch stars from its old stellar population.
The parametrization of gas flows in discs in the Auriga simulations
Authors: Okalidis Periklis , Grand Robert J J , Yates Robert M , Kauffmann Guinevere
Published: April 2021

We study the radial motions of cold, star-forming gas in the secular evolution phase of a set of 14 magnetohydrodynamical cosmological zoom-in simulations of Milky Way-mass galaxies. We study the radial transport of material within the disc plane in a series of concentric rings. For the gas in each ring at a given time we compute two quantities as a function of time and radius: (1) the radial bulk flow of the gas and (2) the radial spread of the gas relative to the bulk flow. Averaging the data from all the haloes, we find that the radial spread increases with radius in the form of a power law with strong secondary dependencies on the fraction of accreted material and the local radial velocity dispersion of the gas. We find that the bulk motion of gas is well described in the inner disc regions by a radially independent mean inwards flow speed of $-2.4\, \rm {km\ s}^{-1}$. The spread around this value relates to the change in angular momentum of the gas and also the amount of accreted material. These scalings from fully cosmological, MHD simulations of galaxy formation can then be used in semi-analytic models to better parametrize the radial flow of gas in discs.
The SAMI Galaxy Survey: stellar population and structural trends across the Fundamental Plane
Authors: D’Eugenio Francesco , Colless Matthew , Scott Nicholas , van der Wel Arjen , Davies Roger L , van de Sande Jesse , Sweet Sarah M , Oh Sree , Groves Brent , Sharp Rob , Owers Matt S , Bland-Hawthorn Joss , Croom Scott M , Brough Sarah , Bryant Julia J , Goodwin Michael , Lawrence Jon S , Lorente Nuria P F , Richards Samuel N
Published: April 2021

We study the Fundamental Plane (FP) for a volume- and luminosity-limited sample of 560 early-type galaxies from the SAMI survey. Using r-band sizes and luminosities from new multi-Gaussian expansion photometric measurements, and treating luminosity as the dependent variable, the FP has coefficients a = 1.294 ± 0.039, b = 0.912 ± 0.025, and zero-point c = 7.067 ± 0.078. We leverage the high signal-to-noise ratio of SAMI integral field spectroscopy, to determine how structural and stellar population observables affect the scatter about the FP. The FP residuals correlate most strongly (8σ significance) with luminosity-weighted simple stellar population (SSP) age. In contrast, the structural observables surface mass density, rotation-to-dispersion ratio, Sérsic index, and projected shape all show little or no significant correlation. We connect the FP residuals to the empirical relation between age (or stellar mass-to-light ratio Υ⋆ ) and surface mass density, the best predictor of SSP age amongst parameters based on FP observables. We show that the FP residuals (anti)correlate with the residuals of the relation between surface density and Υ⋆ . This correlation implies that part of the FP scatter is due to the broad age and Υ⋆ distribution at any given surface mass density. Using virial mass and Υ⋆, we construct a simulated FP and compare it to the observed FP. We find that, while the empirical relations between observed stellar population relations and FP observables are responsible for most (75 per cent) of the FP scatter, on their own they do not explain the observed tilt of the FP away from the virial plane.
HERMES spectroscopy of normal A and Am stars
Authors: Trust Otto , Jurua Edward , De Cat Peter , Joshi Santosh , Lampens Patricia
Published: April 2021

The nominal Kepler mission provided very high precision photometric data. Using these data, interesting phenomena such as spots, and ‘hump and spike’ features were observed in the light curves of some normal A and metallic lined A stars (Am stars). However, the connection between such phenomena and the chemical peculiarity of the Am stars is still unclear. In order to make progress on these issues, it's important to collect high-resolution spectroscopic data to determine their fundamental parameters and individual chemical abundances. In this paper, we present a spectroscopic study of a sample of ‘hump and spike’ stars in the nominal Kepler field. We used data collected with the High Efficiency and Resolution Mercator Échelle Spectrograph (HERMES). We determined the spectral types of these stars and obtained the atmospheric stellar parameters such as effective temperatures, surface gravities, projected rotational, microturbulent, and radial velocities. We also performed a detailed individual chemical abundance analysis for each target. We confirmed KIC 3459226 and KIC 6266219 as Am stars, KIC 9349245 as a marginal Am star, while KIC 4567097, KIC 4818496, KIC 5524045, KIC 5650229, KIC 7667560, and KIC 9272082 are non-Am stars. To estimate their evolutionary phases, all the stars were placed in the Hertzsprung–Russell diagram. Based on their spectral classification and chemical abundance pattern, we reclassified KIC 6266219 (previously treated as chemically normal) as an Am star (kA3hA7mF1) and KIC 9272082 (previously treated as Am) as non-Am.
Detection of complex organic molecules in young starless core L1521E
Authors: Scibelli Samantha , Shirley Yancy , Vasyunin Anton , Launhardt Ralf
Published: April 2021

Determining the level of chemical complexity within dense starless and gravitationally bound pre-stellar cores is crucial for constructing chemical models, which subsequently constrain the initial chemical conditions of star formation. We have searched for complex organic molecules (COMs) in the young starless core L1521E, and report the first clear detection of dimethyl ether (CH3OCH3), methyl formate (HCOOCH3), and vinyl cyanide (CH2CHCN). Eight transitions of acetaldehyde (CH3CHO) were also detected, five of which (A states) were used to determine an excitation temperature to then calculate column densities for the other oxygen-bearing COMs. If source size was not taken into account (i.e. if filling fraction was assumed to be one), column density was underestimated, and thus we stress the need for higher resolution mapping data. We calculated L1521E COM abundances and compared them to other stages of low-mass star formation, also finding similarities to other starless/pre-stellar cores, suggesting related chemical evolution. The scenario that assumes formation of COMs in gas-phase reactions between precursors formed on grains and then ejected to the cold gas via reactive desorption was tested and was unable to reproduce observed COM abundances, with the exception of CH3CHO. These results suggest that COMs observed in cold gas are formed not by gas-phase reactions alone, but also through surface reactions on interstellar grains. Our observations present a new, unique challenge for existing theoretical astrochemical models.
ExoMol molecular line lists – XLII. Rovibronic molecular line list for the low-lying states of NO
Authors: Qu Qianwei , Yurchenko Sergei N , Tennyson Jonathan
Published: April 2021

An accurate line list, called XABC, is computed for nitric oxide which covers its pure rotational, vibrational and rovibronic spectra. A mixture of empirical and theoretical electronic transition dipole moments are used for the final calculation of 14N16O rovibronic $\mathrm{A}\, ^2\Sigma ^+$ – $\mathrm{X}\, ^2\Pi$, $\mathrm{B}\, ^2\Pi$ – X2Π, and $\mathrm{C}\, ^2\Pi$ – $\mathrm{X}\, ^2\Pi$ which correspond to the γ, β, and δ band systems, respectively, as well as minor improvements to transitions within the $\mathrm{X}\, ^2\Pi$ ground state. The work is a major update of the ExoMol NOname line list. It provides a high-accuracy NO ultraviolet line list covering the complicated regions where the $\mathrm{B}\, ^2\Pi$-$\mathrm{C}\, ^2\Pi$ states interact. XABC provides comprehensive data for the lowest four doublet states of NO in the region of λ > 160 nm ($\tilde{\nu } \lt 63~000~\mathrm{cm}^{-1}$) for the analysis of atmospheric NO on Earth, Venus, or Mars, other astronomical observations and applications. The data are available via www.exomol.com.
Strong evidence of low levels of solar activity during the Maunder Minimum
Authors: Carrasco V M S , Hayakawa H , Kuroyanagi C , Gallego M C , Vaquero J M
Published: April 2021

The Maunder Minimum (MM) was a period of prolonged solar activity minimum between 1645 and 1715. Several works have identified a significant number of problematic spotless days in the MM included in existing data bases. We have found a list of exact spotless (in the second half of 1709) and spot days (January and August 1709) provided by Johann Heinrich Müller. We computed the most probable value and upper/lower limits of the active day fraction (ADF) from Müller's data using the hypergeometrical probability distribution. Our sample is not strictly random because Müller recorded observations in consecutive days when he observed sunspots. Therefore, our result represents an upper threshold of solar activity for 1709. We compared this result with annual values of the ADF calculated for the Dalton Minimum and the most recent solar cycles. We concluded that, although 1709 is one of the most active years in the MM, it was less active than most years both in the Dalton Minimum and in the most recent solar cycles. Therefore, the solar activity level estimated in this work for 1709 represents robust evidence of low solar activity levels in the MM.
Impact of initial mass functions on the dynamical channel of gravitational wave sources
Authors: Wang Long , Fujii Michiko S , Tanikawa Ataru
Published: April 2021

Dynamically formed black hole (BH) binaries (BBHs) are important sources of gravitational waves (GWs). Globular clusters (GCs) provide a major environment to produce such BBHs, but the total mass of the known GCs is small compared to that in the Galaxy; thus, the fraction of BBHs formed in GCs is also small. However, this assumes that GCs contain a canonical initial mass function (IMF) similar to that of field stars. This might not be true because several studies suggest that extreme dense and metal-poor environment can result in top-heavy IMFs, where GCs may originate. Although GCs with top-heavy IMFs were easily disrupted or have become dark clusters, the contribution to the GW sources can be significant. Using a high-performance and accurate N-body code, petar, we investigate the effect of varying IMFs by carrying out four star-by-star simulations of dense GCs with the initial mass of 5 × 105 M⊙ and the half-mass radius of 2 pc. We find that the BBH merger rate does not monotonically correlate with the slope of IMFs. Due to a rapid expansion, top-heavy IMFs lead to less efficient formation of merging BBHs. The formation rate continuously decreases as the cluster expands because of the dynamical heating caused by BHs. However, in star clusters with a top-heavier IMF, the total number of BHs is larger, and therefore, the final contribution to merging BBHs can still be more than that from clusters with the standard IMF, if the initial cluster mass and density are higher than those used in our model.
Optical and ultraviolet monitoring of the black hole X-ray binary MAXI J1820+070/ASASSN-18ey for 18 months
Authors: Sai Hanna , Wang Xiaofeng , Wu Jianfeng , Lin Jie , Feng Hua , Zhang Tianmeng , Li Wenxiong , Zhang Jujia , Mo Jun , Sun Tianrui , Ehgamberdiev Shuhrat A , Mirzaqulov Davron , Rui Liming , Lin Weili , Zhao Xulin , Lin Han , Zhang Jicheng , Zhang Xinghan , Zhao Yong , Li Xue , Xiang Danfeng , Wang Lingzhi , Wu Chengyuan
Published: April 2021

MAXI J1820+070 is a low-mass black hole X-ray binary system with high luminosity in both optical and X-ray bands during its outburst periods. We present extensive photometry in the X-ray, ultraviolet, and optical bands, as well as densely cadenced optical spectra, covering the phase from the beginning of the optical outburst to ∼550 days. During the rebrightening process, the optical emission precedes the X-ray by 20.80 ± 2.85 days. The spectra are characterized by blue continua and emission features of Balmer series, He i, and He ii lines and a broad Bowen blend. The pseudo equivalent widths (pEWs) of emission lines are found to show anticorrelations with the X-ray flux measured at comparable phases, due to increased suppression by the optical continuum. At around the X-ray peak, the full widths at half-maximum (FWHMs) of Hβ and He ii λ4686 tend to stabilize at 19.4 and 21.8 Å, corresponding to the line-forming regions at radii of 1.7 and 1.3 R⊙ within the disc. We further analysed the absolute fluxes of the lines and found that the fluxes of Hβ and He ii λ4686 show positive correlations with the X-ray flux, favouring the suggestion that the irradiation model is responsible for the optical emission. However, the fact that X-ray emission experiences a dramatic flux drop at t ∼ 200 days after the outburst, while the optical flux only shows a little variation, suggests that additional energy such as viscous energy may contribute to the optical radiation, in addition to X-ray irradiation.
An Evolutionary Portrait of the Progenitor SARS-CoV-2 and Its Dominant Offshoots in COVID-19 Pandemic
Authors: Kumar Sudhir , Tao Qiqing , Weaver Steven , Sanderford Maxwell , Caraballo-Ortiz Marcos A , Sharma Sudip , Pond Sergei L K , Miura Sayaka
Published: April 2021

Global sequencing of genomes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has continued to reveal new genetic variants that are the key to unraveling its early evolutionary history and tracking its global spread over time. Here we present the heretofore cryptic mutational history and spatiotemporal dynamics of SARS-CoV-2 from an analysis of thousands of high-quality genomes. We report the likely most recent common ancestor of SARS-CoV-2, reconstructed through a novel application and advancement of computational methods initially developed to infer the mutational history of tumor cells in a patient. This progenitor genome differs from genomes of the first coronaviruses sampled in China by three variants, implying that none of the earliest patients represent the index case or gave rise to all the human infections. However, multiple coronavirus infections in China and the United States harbored the progenitor genetic fingerprint in January 2020 and later, suggesting that the progenitor was spreading worldwide months before and after the first reported cases of COVID-19 in China. Mutations of the progenitor and its offshoots have produced many dominant coronavirus strains that have spread episodically over time. Fingerprinting based on common mutations reveals that the same coronavirus lineage has dominated North America for most of the pandemic in 2020. There have been multiple replacements of predominant coronavirus strains in Europe and Asia as well as continued presence of multiple high-frequency strains in Asia and North America. We have developed a continually updating dashboard of global evolution and spatiotemporal trends of SARS-CoV-2 spread (http://sars2evo.datamonkey.org/).
MEGA11: Molecular Evolutionary Genetics Analysis Version 11
Authors: Tamura Koichiro , Stecher Glen , Kumar Sudhir
Published: April 2021

The Molecular Evolutionary Genetics Analysis (MEGA) software has matured to contain a large collection of methods and tools of computational molecular evolution. Here, we describe new additions that make MEGA a more comprehensive tool for building timetrees of species, pathogens, and gene families using rapid relaxed-clock methods. Methods for estimating divergence times and confidence intervals are implemented to use probability densities for calibration constraints for node-dating and sequence sampling dates for tip-dating analyses. They are supported by new options for tagging sequences with spatiotemporal sampling information, an expanded interactive Node Calibrations Editor, and an extended Tree Explorer to display timetrees. Also added is a Bayesian method for estimating neutral evolutionary probabilities of alleles in a species using multispecies sequence alignments and a machine learning method to test for the autocorrelation of evolutionary rates in phylogenies. The computer memory requirements for the maximum likelihood analysis are reduced significantly through reprogramming, and the graphical user interface has been made more responsive and interactive for very big data sets. These enhancements will improve the user experience, quality of results, and the pace of biological discovery. Natively compiled graphical user interface and command-line versions of MEGA11 are available for Microsoft Windows, Linux, and macOS from www.megasoftware.net.
RNA sequencing and proteomic profiling reveal different alterations by dietary methylmercury in the hippocampal transcriptome and proteome in BALB/c mice
Authors: Mellingen Ragnhild Marie , Myrmel Lene Secher , Lie Kai Kristoffer , Rasinger Josef Daniel , Madsen Lise , Nøstbakken Ole Jakob
Published: April 2021

Methylmercury (MeHg) is a highly neurotoxic form of mercury (Hg) present in seafood. Here, we recorded and compared proteomic and transcriptomic changes in hippocampus of male BALB/c mice exposed to two doses of MeHg. Mice were fed diets spiked with 0.28 mg MeHg kg–1, 5 mg MeHg kg–1, or an unspiked control diet for 77 days. Total mercury content was significantly (P < 0.05) increased in brain tissue of both MeHg-exposed groups (18 ± 2 mg Hg kg–1 and 0.56 ± 0.06 mg Hg kg–1). Hippocampal protein and ribonucleic acid (RNA) expression levels were significantly altered both in tissues from mice receiving a low dose MeHg (20 proteins/294 RNA transcripts) and a high dose MeHg (61 proteins/876 RNA transcripts). The majority but not all the differentially expressed features in hippocampus were dose dependent. The combined use of transcriptomic and proteomic profiling data provided insight on the influence of MeHg on neurotoxicity, energy metabolism, and oxidative stress through several regulated features and pathways, including RXR function and superoxide radical degradation.