bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of radiation pressure in lithium deficit for stars in the stage of late accretion: failure of lithium test for young stellar clusters
Authors: Shestakova Lyubov I , Serebryanskiy Aleksander 
Published: February 2024

ABSTRACT
We study the behaviour of lithium atoms in the radiation field of main-sequence (MS) stars. The radiation pressure on atoms in the resonant lines of the ${\rm Li\, {\small I}}$ 6708 Å doublet exceeds the gravity at Teff &gt; 3000 K. The lifetime of ${\rm Li}$ atoms before their ionization is sufficient to achieve the escape velocity. Free ${\rm Li}$ atoms cannot approach the pre-main sequence (PMS) and MS stars if the surrounding gas is sufficiently transparent. Accretion of small bodies (SBs) can partially restore the lithium abundance when SB directly falls on to the star in elongated orbits. In the case of accretion from discs consisting of SB fragments, when the parent bodies move in quasi-circular orbits, the boundary of the SB sublimation region plays a decisive role. Near hot stars, the free ${\rm Li}$ atom is rapidly ionized and participates in accretion on to the star in the form of ions, contributing to an increase in the ${\rm Li}$ abundance. Low-mass stars with low temperatures cannot hold lithium atoms. Near stars with Planck energy distribution in the radiation field, lithium deficiency occurs if 3000 K &lt; Teff &lt; 3400 K. New stars with [Fe/H] = 0.0 may indicate a lithium deficiency at Teff &lt; 5000 K. Failure of the lithium test to estimate the age of a stellar cluster may indicate a significant contribution of accretion in the form of debris discs consisting of SBs.
Microlensing black hole shadows
Authors: Verma Himanshu , Silk Joseph 
Published: February 2024

ABSTRACT
A detailed analysis is presented of gravitational microlensing by intervening compact objects of the black hole shadows imaged by the Event Horizon Telescope (EHT). We show how the centre, size, and shape of the shadow depend on the Einstein angle relative to the true/unlensed shadow size, and how the location of the lens affects the shift, size, and asymmetry of the black hole shadow due to microlensing. Assuming a supermassive black hole (SMBH) casts a circular-shaped true shadow, microlensing can create an asymmetry of up to approximately 8 per cent, which is twice the asymmetry caused by the SMBH’s spin and its tilt relative to us. Furthermore, the size can be enhanced by ∼50 per cent of the true shadow. Currently, the terrestrial baselines of EHT lack the resolution to detect microlensing signatures in the shadows. However, future expansions of EHT, including space-based baselines at the Moon and L2, could potentially enable the detection of microlensing events. For Sgr A*, an event rate of 0.0014 per year makes the microlensing phenomena difficult to observe even with space-based baselines for the stellar population in the stellar bulge and stellar disc for lens masses ∼M⊙. None the less, the presence of a cluster of 20 000 stellar-mass black holes in the central parsec of the Milky Way, expected to arise from dynamical friction acting on infalling stellar clusters, significantly boosts the event rate. Hence, continuously monitoring the shadow of Sgr A* could offer novel insights into the compact object population surrounding the Galactic Centre.
Families of eccentric resonant orbits in galaxy discs: backbones for bars and spirals
Authors: Struck Curtis 
Published: February 2024

ABSTRACT
It is widely believed that resonant orbits play an important role in formation and evolution of bars and large-scale spirals in galaxy discs. These resonant orbits have been studied in a number of specific potentials, often with an imposed bar component. In this paper, I show that families of resonant (e.g. two-dimensional x1) orbits of differing eccentricities can be excited at a common pattern speed, in a variety of axisymmetric potentials. These families only exist over finite ranges of frequency in most of these potentials. Populations of such resonant eccentric orbits (REOs) can provide the backbone of both bars and spirals. At each frequency in the allowed range, there is a maximum eccentricity, beyond which the REOs generically become quasi-stable (or ‘sticky’), then unstable (or chaotic), as the eccentricity increases, at values that depend on the potential and the orbit frequency. Sticky and chaotic orbits have been extensively studied recently with invariant/unstable manifolds in a variety of phase planes; however, it is found that studying them as a function of eccentricity and pattern speed provides a particularly useful framework for classifying them and their stability transitions. The characteristics of these orbit families depend on the galaxy potential and the pattern speed, and as backbones of bars and spirals can help understand a number of observed or predicted regularities. These include: the size and speed of bars in different potentials, the range of pattern speeds and wind-up rates in spirals within galaxy discs, and constraints wave growth.
Effective yields as tracers of feedback effects on metallicity scaling relations in the EAGLE cosmological simulations
Authors: Zerbo M C , De Rossi M E , Lara-López M A , Cora S A , Zenocratti L J 
Published: February 2024

ABSTRACT
Effective yields, yeff, are defined by fundamental galaxy properties (i.e. stellar mass M⋆, gas mass Mgas, and gas-phase metallicity). For a closed-box model, yeff is constant and equivalent to the mass in metals returned to the gas per unit mass locked in long-lived stars. Deviations from such behaviour have been often considered observational signatures of past feedback events. By analysing eagle simulations with different feedback models, we evaluate the impact of supernovae (SNe) and active galactic nuclei (AGNs) feedback on yeff at redshift z = 0. When removing supermassive black holes (BHs) and, hence, AGN effects, in simulations, galaxies are located around a plane in the M⋆–Mgas–O/H parameter space (being O/H a proxy for gas metallicity, as usual), with such a plane roughly describing a surface of constant yeff. As the ratio between BH mass and M⋆ increases, galaxies deviate from that plane towards lower yeff as a consequence of AGN feedback. For galaxies not strongly affected by AGN feedback, a stronger SN feedback efficiency generates deviations towards lower yeff, while galaxies move towards the opposite side of the plane (i.e. towards higher values of yeff) as SN feedback becomes weaker. Star-forming galaxies observed in the Local Universe are located around a similar 3D plane. Our results suggest that the features of the scatter around the observed plane are related to the different feedback histories of galaxies, which might be traced by yeff.
The 21-cm bispectrum from neutral hydrogen islands at z &lt; 6
Authors: Raste Janakee , Kulkarni Girish , Watkinson Catherine A , Keating Laura C , Haehnelt Martin G 
Published: February 2024

ABSTRACT
Spatial variations in the Lyman-α forest opacity at z &lt; 6 seem to require a late end to cosmic reionization. In this picture, the Universe contains neutral hydrogen ‘islands’ of up to 100 cMpc/h in extent down to redshifts as low as z ∼ 5.3. This delayed end to reionization also seems to be corroborated by various other observables. An implication of this scenario is that the power spectrum of the cosmological 21-cm signal at z &lt; 6 is enhanced relative to conventional reionization models by orders of magnitude. However, these neutral hydrogen islands are also predicted to be at the locations of the deepest voids in the cosmological large-scale structure. As a result, the distribution of the 21-cm signal from them is highly non-Gaussian. We derive the 21-cm bispectrum signal from these regions using high-dynamic-range radiative transfer simulations of reionization. We find that relative to conventional models in which reionization is complete at z &gt; 6, our model has a significantly larger value of the 21-cm bispectrum. The neutral islands also imprint a feature in the isosceles bispectrum at a characteristic scale of ∼1 cMpc−1. We also study the 21-cm bispectrum for general triangle configuration by defining a triangle index. It should be possible to detect the 21-cm bispectrum signal at ν ≳ 200 MHz using SKA1-LOW for 1080 h of observation, assuming optimistic foreground removal.
The invisible black widow PSR J1720−0534: implications for the electron density towards the North Polar Spur
Authors: Koljonen K I I , Lindseth S S , Linares M , Harding A K , Turchetta M 
Published: February 2024

ABSTRACT
Radio emission from pulsars can be used to map out their distances through dispersion measure (DM), which quantifies the amount of radio pulse dispersion. However, this method relies on accurately modelling the free electron density in the line of sight. Here, we present a detailed study of the multiwavelength emission from PSR J1720−0534, a black widow compact binary millisecond pulsar discovered in 2021, which the latest electron density model of the Galaxy places at only 191 pc. We obtained and analysed deep multiwavelength observations in the γ-ray (Fermi-Large Area Telescope, 2008–2022), optical (Las Cumbres Observatory, 2.7 h), near-infrared (Nordic Optical Telescope, 3.5 h), and X-ray (Swift-X-Ray Telescope, 10 ks) bands. We found no significant detection of γ-ray, optical, near-infrared, or X-ray counterparts around the radio-timing position of PSR J1720−0534, which we thus nickname ‘the invisible black widow’. Employing the most constraining near-infrared limit (J &gt; 23.4 mag), we established a lower limit on the source distance, d &gt; 1.1 kpc, assuming conservative properties for the black widow companion star. This distance lower limit differs drastically (by a factor of more than 5) from the Yao et al. DM distance estimate. We attribute this difference to the inclusion in the Yao et al. model of a large and dense component towards the North Polar Spur. Considering our results and recent parallax distances to other pulsars in this direction, we argue that such a local and large component in the electron density model of the Galaxy is unnecessary.
Adaptive Evolution of Pseudomonas aeruginosa in Human Airways Shows Phenotypic Convergence Despite Diverse Patterns of Genomic Changes
Authors: Espaillat Akbar , Colque Claudia Antonella , Rago Daniela , La Rosa Ruggero , Molin Søren , Johansen Helle Krogh 
Published: February 2024

Abstract
Selective forces in the environment drive bacterial adaptation to novel niches, choosing the fitter variants in the population. However, in dynamic and changing environments, the evolutionary processes controlling bacterial adaptation are difficult to monitor. Here, we follow 9 people with cystic fibrosis chronically infected with Pseudomonas aeruginosa, as a proxy for bacterial adaptation. We identify and describe the bacterial changes and evolution occurring between 15 and 35 yr of within-host evolution. We combine whole-genome sequencing, RNA sequencing, and metabolomics and compare the evolutionary trajectories directed by the adaptation of 4 different P. aeruginosa lineages to the lung. Our data suggest divergent evolution at the genomic level for most of the genes, with signs of convergent evolution with respect to the acquisition of mutations in regulatory genes, which drive the transcriptional and metabolomic program at late time of evolution. Metabolomics further confirmed convergent adaptive phenotypic evolution as documented by the reduction of the quorum-sensing molecules acyl-homoserine lactone, phenazines, and rhamnolipids (except for quinolones). The modulation of the quorum-sensing repertoire suggests that similar selective forces characterize at late times of evolution independent of the patient. Collectively, our data suggest that similar environments and similar P. aeruginosa populations in the patients at prolonged time of infection are associated with an overall reduction of virulence-associated features and phenotypic convergence.
Sperm DNA methylation defects in a new mouse model of the 5,10-methylenetetrahydrofolate reductase 677C&gt;T variant and correction with moderate dose folic acid supplementation
Authors: Martínez Duncker Rebolledo Edgar , Chan Donovan , Christensen Karen E , Reagan Alaina M , Howell Gareth R , Rozen Rima , Trasler Jacquetta 
Published: February 2024

Abstract
5,10-Methylenetetrahydrofolate reductase (MTHFR) is an enzyme that plays a key role in providing methyl groups for DNA methylation, including during spermatogenesis. A common genetic variant in humans (MTHFR 677C&gt;T) results in reduced enzyme activity and has been linked to various disorders, including male infertility. A new animal model has been created by reproducing the human equivalent of the polymorphism in mice using CRISPR/Cas9. Biochemical parameters in the Mthfr 677TT mice recapitulate alterations found in MTHFR 677TT men. Our aims were to characterize the sperm DNA methylome of the Mthfr 677CC and TT mice on a control diet (2 mg folic acid/kg diet) and assess the effects of folic acid supplementation (10 mg/kg diet) on the sperm DNA methylome. Body and reproductive organ weights, testicular sperm counts, and histology were examined. DNA methylation in sperm was assessed using bisulfite pyrosequencing and whole-genome bisulfite sequencing (WGBS). Reproductive parameters and locus-specific imprinted gene methylation were unaffected by genotype or diet. Using WGBS, sperm from 677TT mice had 360 differentially methylated tiles as compared to 677CC mice, predominantly hypomethylation (60% of tiles). Folic acid supplementation mostly caused hypermethylation in sperm of males of both genotypes and was found to partially correct the DNA methylation alterations in sperm associated with the TT genotype. The new mouse model will be useful in understanding the role of MTHFR deficiency in male fertility and in designing folate supplementation regimens for the clinic.
Professional Supervision Among Music Therapists: A Survey
Authors: Macrae Amanda 
Published: February 2024

Abstract
Following completion of formal clinical training, music therapists may choose to seek professional supervision to stimulate and support their professional development. The American Music Therapy Association and Certification Board for Music Therapists assert that music therapists are responsible for seeking supervision when needed. However, no means of accountability for music therapists or standard of training for music therapy supervisors exist. Little is known about the current rate of music therapists’ participation in professional supervision or their experiences therein. For this study, a 38-item survey was disseminated to credentialed music therapists. A total of 339 (39%) of 875 music therapist respondents participated in professional supervision; 231 (68%) of those were supervised by a music therapist; and about 100 (43%) of those supervisors used music in supervision. Most participants felt comfortable addressing cultural issues within supervision. Almost 75% of participants believed there should be a formalized training program to become a professional music therapy supervisor, 47% believed there should be a required credential to provide music therapy supervision, and 67% believed music therapists should be required to receive supervision. Concerns about standardizing the supervision process were shared. Recommendations include providing an incentive for participation in supervision, offering accessible options of supervision, and further research into music therapists’ needs and experiences in supervision.
Temperature-sensitive splicing defects in Arabidopsis mitochondria caused by mutations in the ROOT PRIMORDIUM DEFECTIVE 1 gene
Authors: Wang Chuande , Quadrado Martine , Mireau Hakim 
Published: February 2024

Abstract
Group II introns in plant organelles have lost splicing autonomy and require the assistance of nuclear-encoded trans-factors whose roles remain to be elucidated. These factors can be mono- or poly-specific with respect to the number of introns whose splicing they facilitate. Poly-acting splicing factors are often essential and their genetic identification may benefit from the use of conditional mutations. Temperature-sensitive (TS) mutations in the ROOT PRIMORDIUM DEFECTIVE 1 (RPD1) gene were initially selected for their inhibitory effect on root formation in Arabidopsis. Further analysis revealed that RPD1 encodes a mitochondria-targeted RNA-binding protein family member, suggesting a role in mitochondrial gene expression and making its role in root formation enigmatic. We analysed the function of RPD1 and found that it is required for the removal of 9 mitochondrial group II introns and that the identified TS mutations affect the splicing function of RPD1. These results support that the inhibition of adventitious root formation at non-permissive temperature results from a reduction in RPD1 activity and thus mitochondrial activity. We further show that RPD1 physically associates in vivo with the introns whose splicing it facilitates. Preliminary mapping indicates that RPD1 may not bind to the same regions within all of its intron targets, suggesting potential variability in its influence on splicing activation.
Leveraging chromatin state transitions for the identification of regulatory networks orchestrating heart regeneration
Authors: Cordero Julio , Elsherbiny Adel , Wang Yinuo , Jürgensen Lonny , Constanty Florian , Günther Stefan , Boerries Melanie , Heineke Joerg , Beisaw Arica , Leuschner Florian , Hassel David , Dobreva Gergana 
Published: February 2024

Abstract
The limited regenerative capacity of the human heart contributes to high morbidity and mortality worldwide. In contrast, zebrafish exhibit robust regenerative capacity, providing a powerful model for studying how to overcome intrinsic epigenetic barriers maintaining cardiac homeostasis and initiate regeneration. Here, we present a comprehensive analysis of the histone modifications H3K4me1, H3K4me3, H3K27me3 and H3K27ac during various stages of zebrafish heart regeneration. We found a vast gain of repressive chromatin marks one day after myocardial injury, followed by the acquisition of active chromatin characteristics on day four and a transition to a repressive state on day 14, and identified distinct transcription factor ensembles associated with these events. The rapid transcriptional response involves the engagement of super-enhancers at genes implicated in extracellular matrix reorganization and TOR signaling, while H3K4me3 breadth highly correlates with transcriptional activity and dynamic changes at genes involved in proteolysis, cell cycle activity, and cell differentiation. Using loss- and gain-of-function approaches, we identified transcription factors in cardiomyocytes and endothelial cells influencing cardiomyocyte dedifferentiation or proliferation. Finally, we detected significant evolutionary conservation between regulatory regions that drive zebrafish and neonatal mouse heart regeneration, suggesting that reactivating transcriptional and epigenetic networks converging on these regulatory elements might unlock the regenerative potential of adult human hearts.
Ribosomal collision is not a prerequisite for ZNF598-mediated ribosome ubiquitination and disassembly of ribosomal complexes by ASCC
Authors: Miścicka Anna , Bulakhov Alexander G , Kuroha Kazushige , Zinoviev Alexandra , Hellen Christopher U T , Pestova Tatyana V 
Published: February 2024

Abstract
Ribosomal stalling induces the ribosome-associated quality control (RQC) pathway targeting aberrant polypeptides. RQC is initiated by K63-polyubiquitination of ribosomal protein uS10 located at the mRNA entrance of stalled ribosomes by the E3 ubiquitin ligase ZNF598 (Hel2 in yeast). Ubiquitinated ribosomes are dissociated by the ASC-1 complex (ASCC) (RQC-Trigger (RQT) complex in yeast). A cryo-EM structure of the ribosome-bound RQT complex suggested the dissociation mechanism, in which the RNA helicase Slh1 subunit of RQT (ASCC3 in mammals) applies a pulling force on the mRNA, inducing destabilizing conformational changes in the 40S subunit, whereas the collided ribosome acts as a wedge, promoting subunit dissociation. Here, using an in vitro reconstitution approach, we found that ribosomal collision is not a strict prerequisite for ribosomal ubiquitination by ZNF598 or for ASCC-mediated ribosome release. Following ubiquitination by ZNF598, ASCC efficiently dissociated all polysomal ribosomes in a stalled queue, monosomes assembled in RRL, in vitro reconstituted 80S elongation complexes in pre- and post-translocated states, and 48S initiation complexes, as long as such complexes contained ≥ 30–35 3′-terminal mRNA nt. downstream from the P site and sufficiently long ubiquitin chains. Dissociation of polysomes and monosomes both involved ribosomal splitting, enabling Listerin-mediated ubiquitination of 60S-associated nascent chains.
Prediction of DNA i-motifs via machine learning
Authors: Yang Bibo , Guneri Dilek , Yu Haopeng , Wright Elisé P , Chen Wenqian , Waller Zoë A E , Ding Yiliang 
Published: February 2024

Abstracti-Motifs (iMs), are secondary structures formed in cytosine-rich DNA sequences and are involved in multiple functions in the genome. Although putative iM forming sequences are widely distributed in the human genome, the folding status and strength of putative iMs vary dramatically. Much previous research on iM has focused on assessing the iM folding properties using biophysical experiments. However, there are no dedicated computational tools for predicting the folding status and strength of iM structures. Here, we introduce a machine learning pipeline, iM-Seeker, to predict both folding status and structural stability of DNA iMs. The programme iM-Seeker incorporates a Balanced Random Forest classifier trained on genome-wide iMab antibody-based CUT&Tag sequencing data to predict the folding status and an Extreme Gradient Boosting regressor to estimate the folding strength according to both literature biophysical data and our in-house biophysical experiments. iM-Seeker predicts DNA iM folding status with a classification accuracy of 81% and estimates the folding strength with coefficient of determination (R2) of 0.642 on the test set. Model interpretation confirms that the nucleotide composition of the C-rich sequence significantly affects iM stability, with a positive correlation with sequences containing cytosine and thymine and a negative correlation with guanine and adenine.