bluuebunny/crossref_metadata_2025_split huggingface dataset:
A statistical analysis of the nulling pulsar population
Authors: Sheikh Sofia Z , MacDonald Mariah G 
Published: February 2021

ABSTRACTApproximately 8 per cent of the ∼2800 known pulsars exhibit ‘nulling,’ a temporary broad-band cessation of normal pulsar emission. Nulling behaviour can be coarsely quantified by the nulling fraction, which describes the percentage of time a given pulsar will be found in a null state. In this paper, we perform the most thorough statistical analysis thus far of the properties of 141 known nulling pulsars. We find weak, non-linear correlations between nulling fraction and pulse width, as well as nulling fraction and spin period which could be attributed to selection effects. We also further investigate a recently hypothesized gap at 40 per cent nulling fraction. While a local minimum does exist in the distribution, we cannot confirm a consistent and unique break in the distribution when we investigate with univariate and multivariate clustering methods, nor can we prove the existence of two statistically distinct populations about this minimum. Using the same methods, we find that nulling pulsars are a statistically different population from normal, radio, non-nulling pulsars, which has never been quantitatively verified. In addition, we summarize the findings of the prior nulling pulsar statistics literature, which are notoriously contradictory. This study, in context, furthers the idea that nulling fraction alone does not contain enough information to describe the behaviour of a nulling pulsar and that other parameters such as null lengths and null randomness, in addition to a better understanding of selection effects, are required to fully understand this phenomenon.
Magnetic white dwarfs in post-common-envelope binaries
Authors: Parsons S G , Gänsicke B T , Schreiber M R , Marsh T R , Ashley R P , Breedt E , Littlefair S P , Meusinger H 
Published: February 2021

ABSTRACT
Magnitude-limited samples have shown that 20–25 per cent of cataclysmic variables contain white dwarfs with magnetic fields of Mega Gauss strength, in stark contrast to the approximately 5 per cent of single white dwarfs with similar magnetic field strengths. Moreover, the lack of identifiable progenitor systems for magnetic cataclysmic variables leads to considerable challenges when trying to understand how these systems form and evolve. Here, we present a sample of six magnetic white dwarfs in detached binaries with low-mass stellar companions where we have constrained the stellar and binary parameters including, for the first time, reliable mass estimates for these magnetic white dwarfs. We find that they are systematically more massive than non-magnetic white dwarfs in detached binaries. These magnetic white dwarfs generally have cooling ages of more than 1 Gyr and reside in systems that are very close to Roche lobe filling. Our findings are more consistent with these systems being temporarily detached cataclysmic variables, rather than pre-cataclysmic binaries, but we cannot rule out the latter possibility. We find that these systems can display unusual asymmetric light curves that may offer a way to identify them in larger numbers in future. Seven new candidate magnetic white dwarf systems are also presented, three of which have asymmetric light curves. Finally, we note that several newly identified magnetic systems have archival spectra where there is no clear evidence of magnetism, meaning that these binaries have been previously missed. Nevertheless, there remains a clear lack of younger detached magnetic white dwarf systems.
The antesonic condition for the explosion of core-collapse supernovae – II. Rotation and turbulence
Authors: Raives Matthias J , Thompson Todd A , Couch Sean M 
Published: February 2021

ABSTRACT
In the problem of steady free fall on to a standing shockwave around a central mass, the ‘antesonic’ condition limits the regime of stable accretion to $c_T^2/v_\mathrm{esc}^2\le 3/16$, where cT is the isothermal sound speed in the subsonic post-shock flow, and vesc is the escape velocity at the shock radius. Above this limit, it is impossible to satisfy both the Euler equation and the shock jump conditions, and the system transitions to a wind. This physics explains the existence of a critical neutrino luminosity in steady-state models of accretion in the context of core-collapse supernovae. Here, we extend the antesonic condition to flows with rotation and turbulence using a simple one-dimensional formalism. Both effects decrease the critical post-shock sound speed required for explosion. While quite rapid rotation is required for a significant change to the critical condition, we show that the level of turbulence typically achieved in supernova simulations can greatly impact the critical value of $c_T^2/v_\mathrm{esc}^2$. A core angular velocity corresponding to a millisecond rotation period after contraction of the proto-neutron star results in only a ∼5 per cent reduction of the critical curve. In contrast, near-sonic turbulence with specific turbulent kinetic energy $K/c_T^2=0.5-1$, leads to a decrease in the critical value of $c_T^2/v_{\rm esc}^2$ by ∼20 to 40 per cent. This analysis provides a framework for understanding the role of post-shock turbulence in instigating explosions in models that would otherwise fail and helps explain why multidimensional simulations explode more easily than their one-dimensional counterparts.
Inside out and upside-down: The roles of gas cooling and dynamical heating in shaping the stellar age–velocity relation
Authors: Bird Jonathan C , Loebman Sarah R , Weinberg David H , Brooks Alyson M , Quinn Thomas R , Christensen Charlotte R 
Published: February 2021

ABSTRACT
Kinematic studies of disc galaxies, using individual stars in the Milky Way or statistical studies of global disc kinematics over time, provide insight into how discs form and evolve. We use a high-resolution, cosmological zoom-simulation of a Milky Way-mass disc galaxy (h277) to tie together local disc kinematics and the evolution of the disc over time. The present-day stellar age–velocity relationship (AVR) of h277 is nearly identical to that of the analogous solar-neighbourhood measurement in the Milky Way. A crucial element of this success is the simulation’s dynamically cold multiphase ISM, which allows young stars to form with a low velocity dispersion (σbirth$\sim \!6 - 8 \ \mathrm{km\, s}^{-1}$) at late times. Older stars are born kinematically hotter (i.e. the disc settles over time in an ‘upside-down’ formation scenario), and are subsequently heated after birth. The disc also grows ‘inside-out’, and many of the older stars in the present-day solar neighbourhood are present because of radial mixing. We demonstrate that the evolution of σbirth in h277 can be explained by the same model used to describe the general decrease in velocity dispersion observed in disc galaxies from z ∼ 2–3 to the present-day, in which the disc evolves in quasi-stable equilibrium and the ISM velocity dispersion decreases over time due to a decreasing gas fraction. Thus, our results tie together local observations of the Milky Way’s AVR with observed kinematics of high z disc galaxies.
Galactic potential constraints from clustering in action space of combined stellar stream data
Authors: Reino Stella , Rossi Elena M , Sanderson Robyn E , Sellentin Elena , Helmi Amina , Koppelman Helmer H , Sharma Sanjib 
Published: February 2021

ABSTRACT
Stream stars removed by tides from their progenitor satellite galaxy or globular cluster act as a group of test particles on neighbouring orbits, probing the gravitational field of the Milky Way. While constraints from individual streams have been shown to be susceptible to biases, combining several streams from orbits with various distances reduces these biases. We fit a common gravitational potential to multiple stellar streams simultaneously by maximizing the clustering of the stream stars in action space. We apply this technique to members of the GD-1, Palomar 5 (Pal 5), Orphan, and Helmi streams, exploiting both the individual and combined data sets. We describe the Galactic potential with a Stäckel model, and vary up to five parameters simultaneously. We find that we can only constrain the enclosed mass, and that the strongest constraints come from the GD-1, Pal 5, and Orphan streams whose combined data set yields $M(\lt 20\, \mathrm{kpc}) = 2.96^{+0.25}_{-0.26} \times 10^{11} \, \mathrm{ M}_{\odot}$. When including the Helmi stream in the data set, the mass uncertainty increases to $M(\lt 20\, \mathrm{kpc}) = 3.12^{+3.21}_{-0.46} \times 10^{11} \, \mathrm{M}_{\odot}$.
The dynamics of the globular cluster NGC 3201 out to the Jacobi radius
Authors: Wan Zhen , Oliver William H , Baumgardt Holger , Lewis Geraint F , Gieles Mark , Hénault-Brunet Vincent , de Boer Thomas , Balbinot Eduardo , Da Costa Gary , Mackey Dougal 
Published: February 2021

ABSTRACT
As part of a chemodynamical survey of five nearby globular clusters with 2dF/AAOmega on the Anglo-Australian Telescope (AAT), we have obtained kinematic information for the globular cluster NGC 3201. Our new observations confirm the presence of a significant velocity gradient across the cluster which can almost entirely be explained by the high proper motion of the cluster (${\sim}9\, \mathrm{mas\, yr^{-1}}$). After subtracting the contribution of this perspective rotation, we found a remaining rotation signal with an amplitude of ${\sim}1\, \mathrm{km\, s^{-1}}$ around a different axis to what we expect from the tidal tails and the potential escapers, suggesting that this rotation is internal and can be a remnant of its formation process. At the outer part, we found a rotational signal that is likely a result from potential escapers. The proper motion dispersion at large radii reported by Bianchini et al. ($3.5\pm 0.9\, \mathrm{km\, s^{-1}}$) has previously been attributed to dark matter. Here, we show that the LOS dispersion between 0.5 and 1 Jacobi radius is lower ($2.01\pm 0.18\, \mathrm{km\, s^{-1}}$), yet above the predictions from an N-body model of NGC 3201 that we ran for this study ($1.48\pm 0.14\, \mathrm{km\, s^{-1}}$). Based on the simulation, we find that potential escapers cannot fully explain the observed velocity dispersion. We also estimate the effect on the velocity dispersion of different amounts of stellar-mass black holes and unbound stars from the tidal tails with varying escape rates and find that these effects cannot explain the difference between the LOS dispersion and the N-body model. Given the recent discovery of tidal tail stars at large distances from the cluster, a dark matter halo is an unlikely explanation. We show that the effect of binary stars, which is not included in the N-body model, is important and can explain part of the difference in dispersion. We speculate that the remaining difference must be the result of effects not included in the N-body model, such as initial cluster rotation, velocity anisotropy, and Galactic substructure.
The AGN–galaxy–halo connection: the distribution of AGN host halo masses to z = 2.5
Authors: Aird James , Coil Alison L 
Published: February 2021

ABSTRACT
It is widely reported, based on clustering measurements of observed active galactic nucleus (AGN) samples, that AGNs reside in similar mass host dark matter haloes across the bulk of cosmic time, with log $\mathcal {M}/\mathcal {M}_{\odot }\sim 12.5\!-\!13.0$ to z ∼ 2.5. We show that this is due in part to the AGN fraction in galaxies rising with increasing stellar mass, combined with AGN observational selection effects that exacerbate this trend. Here, we use AGN specific accretion rate distribution functions determined as a function of stellar mass and redshift for star-forming and quiescent galaxies separately, combined with the latest galaxy–halo connection models, to determine the parent and subhalo mass distribution function of AGNs to various observational limits. We find that while the median (sub)halo mass of AGNs, $\approx 10^{12}\mathcal {M}_{\odot }$, is fairly constant with luminosity, specific accretion rate, and redshift, the full halo mass distribution function is broad, spanning several orders of magnitude. We show that widely used methods to infer a typical dark matter halo mass based on an observed AGN clustering amplitude can result in biased, systematically high host halo masses. While the AGN satellite fraction rises with increasing parent halo mass, we find that the central galaxy is often not an AGN. Our results elucidate the physical causes for the apparent uniformity of AGN host haloes across cosmic time and underscore the importance of accounting for AGN selection biases when interpreting observational AGN clustering results. We further show that AGN clustering is most easily interpreted in terms of the relative bias to galaxy samples, not from absolute bias measurements alone.
Human METTL18 is a histidine-specific methyltransferase that targets RPL3 and affects ribosome biogenesis and function
Authors: Małecki Jędrzej M , Odonohue Marie-Francoise , Kim Yeji , Jakobsson Magnus E , Gessa Luca , Pinto Rita , Wu Jie , Davydova Erna , Moen Anders , Olsen Jesper V , Thiede Bernd , Gleizes Pierre-Emmanuel , Leidel Sebastian A , Falnes Pål Ø 
Published: February 2021

Abstract
Protein methylation occurs primarily on lysine and arginine, but also on some other residues, such as histidine. METTL18 is the last uncharacterized member of a group of human methyltransferases (MTases) that mainly exert lysine methylation, and here we set out to elucidate its function. We found METTL18 to be a nuclear protein that contains a functional nuclear localization signal and accumulates in nucleoli. Recombinant METTL18 methylated a single protein in nuclear extracts and in isolated ribosomes from METTL18 knockout (KO) cells, identified as 60S ribosomal protein L3 (RPL3). We also performed an RPL3 interactomics screen and identified METTL18 as the most significantly enriched MTase. We found that His-245 in RPL3 carries a 3-methylhistidine (3MH; τ-methylhistidine) modification, which was absent in METTL18 KO cells. In addition, both recombinant and endogenous METTL18 were found to be automethylated at His-154, thus further corroborating METTL18 as a histidine-specific MTase. Finally, METTL18 KO cells displayed altered pre-rRNA processing, decreased polysome formation and codon-specific changes in mRNA translation, indicating that METTL18-mediated methylation of RPL3 is important for optimal ribosome biogenesis and function. In conclusion, we have here established METTL18 as the second human histidine-specific protein MTase, and demonstrated its functional relevance.
Roles for hENT1 and dCK in gemcitabine sensitivity and malignancy of meningioma
Authors: Yamamoto Masahiro , Sanomachi Tomomi , Suzuki Shuhei , Uchida Hiroyuki , Yonezawa Hajime , Higa Nayuta , Takajo Tomoko , Yamada Yuki , Sugai Asuka , Togashi Keita , Seino Shizuka , Okada Masashi , Sonoda Yukihiko , Hirano Hirofumi , Yoshimoto Koji , Kitanaka Chifumi 
Published: February 2021

AbstractBackgroundHigh-grade meningiomas are aggressive tumors with high morbidity and mortality rates that frequently recur even after surgery and adjuvant radiotherapy. However, limited information is currently available on the biology of these tumors, and no alternative adjuvant treatment options exist. Although we previously demonstrated that high-grade meningioma cells were highly sensitive to gemcitabine in vitro and in vivo, the underlying molecular mechanisms remain unknown.MethodsWe examined the roles of hENT1 (human equilibrative nucleoside transporter 1) and dCK (deoxycytidine kinase) in the gemcitabine sensitivity and growth of meningioma cells in vitro. Tissue samples from meningiomas (26 WHO grade I and 21 WHO grade II/III meningiomas) were immunohistochemically analyzed for hENT1 and dCK as well as for Ki-67 as a marker of proliferative activity.ResultshENT1 and dCK, which play critical roles in the intracellular transport and activation of gemcitabine, respectively, were responsible for the high gemcitabine sensitivity of high-grade meningioma cells and were strongly expressed in high-grade meningiomas. hENT1 expression was required for the proliferation and survival of high-grade meningioma cells and dCK expression. Furthermore, high hENT1 and dCK expression levels correlated with stronger tumor cell proliferative activity and shorter survival in meningioma patients.ConclusionsThe present results suggest that hENT1 is a key molecular factor influencing the growth capacity and gemcitabine sensitivity of meningioma cells and also that hENT1, together with dCK, may be a viable prognostic marker for meningioma patients as well as a predictive marker of their responses to gemcitabine.
A serum-based DNA methylation assay provides accurate detection of glioma
Authors: Sabedot Thais S , Malta Tathiane M , Snyder James , Nelson Kevin , Wells Michael , deCarvalho Ana C , Mukherjee Abir , Chitale Dhananjay A , Mosella Maritza S , Sokolov Artem , Asmaro Karam P , Robin Adam , Rosenblum Mark L , Mikkelsen Tom , Rock Jack , Poisson Laila M , Lee Ian , Walbert Tobias , Kalkanis Steven , Iavarone Antonio , Castro Ana Valeria , Noushmehr Houtan 
Published: February 2021

AbstractBackgroundThe detection of somatic mutations in cell-free DNA (cfDNA) from liquid biopsy has emerged as a noninvasive tool to monitor the follow-up of cancer patients. However, the significance of cfDNA clinical utility remains uncertain in patients with brain tumors, primarily because of the limited sensitivity cfDNA has to detect real tumor-specific somatic mutations. This unresolved challenge has prevented accurate follow-up of glioma patients with noninvasive approaches.MethodsGenome-wide DNA methylation profiling of tumor tissue and serum cfDNA of glioma patients.ResultsHere, we developed a noninvasive approach to profile the DNA methylation status in the serum of patients with gliomas and identified a cfDNA-derived methylation signature that is associated with the presence of gliomas and related immune features. By testing the signature in an independent discovery and validation cohorts, we developed and verified a score metric (the “glioma-epigenetic liquid biopsy score” or GeLB) that optimally distinguished patients with or without glioma (sensitivity: 100%, specificity: 97.78%). Furthermore, we found that changes in GeLB score reflected clinicopathological changes during surveillance (eg, progression, pseudoprogression, and response to standard or experimental treatment).ConclusionsOur results suggest that the GeLB score can be used as a complementary approach to diagnose and follow up patients with glioma.
Diagnostic Pathology of Tumors of Peripheral Nerve
Authors: Belakhoua Sarra M , Rodriguez Fausto J 
Published: February 2021

AbstractNeoplasms of the peripheral nervous system represent a heterogenous group with a wide spectrum of morphological features and biological potential. They range from benign and curable by complete excision (schwannoma and soft tissue perineurioma) to benign but potentially aggressive at the local level (plexiform neurofibroma) to the highly malignant (malignant peripheral nerve sheath tumors [MPNST]). In this review, we discuss the diagnostic and pathologic features of common peripheral nerve sheath tumors, particularly those that may be encountered in the intracranial compartment or in the spine and paraspinal region. The discussion will cover schwannoma, neurofibroma, atypical neurofibromatous neoplasms of uncertain biological potential, intraneural and soft tissue perineurioma, hybrid nerve sheath tumors, MPNST, and the recently renamed enigmatic tumor, malignant melanotic nerve sheath tumor, formerly referred to as melanotic schwannoma. We also discuss the diagnostic relevance of these neoplasms to specific genetic and familial syndromes of nerve, including neurofibromatosis 1, neurofibromatosis 2, and schwannomatosis. In addition, we discuss updates in our understanding of the molecular alterations that represent key drivers of these neoplasms, including neurofibromatosis type 1 and type 2,SMARCB1, LZTR1, andPRKAR1Aloss, as well as the acquisition ofCDKN2A/Bmutations and alterations in the polycomb repressor complex members (SUZ12andEED) in the malignant progression to MPNST. In summary, this review covers practical aspects of pathologic diagnosis with updates relevant to neurosurgical practice.
The Role of Surgery in IDH-Wild-Type Lower-Grade Gliomas: Threshold at a High Extent of Resection Should be Pursued
Authors: Wang Peng , Luo Chen , Hong Peng-jie , Rui Wen-ting , Wu Shuai 
Published: February 2021

Abstract

BACKGROUND
While maximizing extent of resection (EOR) is associated with longer survival in lower-grade glioma (LGG) patients, the number of cases remains insufficient in determining a EOR threshold to elucidate the clinical benefits, especially in IDH-wild-type LGG patients.

OBJECTIVE
To identify the effects of EOR on the survival outcomes of IDH-wild-type LGG patients.

METHODS
IDH-wild-type LGG patients were retrospectively reviewed. The effect of EOR and other predictor variables on overall survival (OS) and progression-free survival (PFS) was analyzed using Cox regression models and the Kaplan-Meier method.

RESULTS
A total of 94 patients (median OS: 48.9 mo; median follow-up: 30.6 mo) were included in this study. In the multivariable Cox regression analysis, postoperative residual volume was associated with prolonged OS (HR = 2.238; 95% confidence interval [CI], 1.130-4.435; P = .021) and PFS (HR = 2.075; 95% CI, 1.113-3.869; P = .022). Thresholds at a minimum EOR of 97.0% or a maximum residue of 3.0 cm3 were necessary to impact OS positively. For the telomerase reverse transcriptase (TERT)p-wild-type group, such an association was absent. Significant differences in survival existed between the TERTp-wild-type and mutant patients who underwent relatively incomplete resections (residual ≥2.0 cm3 + TERTp wild type: median OS of 62.6 mo [95% CI: 39.7-85.5 mo]; residual ≥2.0 cm3 + TERTp mutant: median OS of 20.0 mo [95% CI:14.6-25.4 mo]).

CONCLUSION
Our results support the core role of maximal safe resection in the treatment of IDH-wild-type LGGs, especially for IDH-wild-type + TERTp-mutant LGGs. Importantly, the survival benefits of surgery could only be elucidated at a high EOR cut-off point.
Privity: Rights, Standing, and the Road Not Taken
Authors: Liau Timothy 
Published: February 2021

Abstract
Privity is generally understood as a rule comprising a burdens limb and a more controversial benefits or ‘rights’ limb. This rendition of privity is too simplistic. Privity has multiple aspects, but its underlying complexity has been obscured by an overwhelming focus on ‘rights’, explaining in part the persistent unclarity plaguing the area. In this article, I argue that an elision of concepts has hampered our understanding of privity and its reform. The literature on contractual rights to performance and secondary rights to damages for their breach is legion. By contrast, standing, as a separate and distinct concept, has been overlooked. These are concepts that need to be more clearly differentiated. While not a panacea to resolve all issues, it is a necessary step to a firmer handle over the distinct issues at stake, and to opening up a novel angle to privity reform—third-party standing—the road not taken.