bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct collapse to supermassive black hole seeds: the critical conditions for suppression of H2 cooling
Authors: Luo Yang , Shlosman Isaac , Nagamine Kentaro , Fang Taotao 
Published: January 2020

ABSTRACT
Observations of high-redshift quasars imply the presence of supermassive black holes (SMBHs) already at $z$ ∼ 7.5. An appealing and promising pathway to their formation is the direct collapse scenario of a primordial gas in atomic-cooling haloes at $z$ ∼ 10–20, when the $\rm H_{2}$ formation is inhibited by a strong background radiation field, whose intensity exceeds a critical value, Jcrit. To estimate Jcrit, typically, studies have assumed idealized spectra, with a fixed ratio of $\rm H_{2}$ photodissociation rate $k_{\rm H_2}$ to the $\rm H^-$ photodetachment rate $k_{\rm H^-}$. This assumption, however, could be too narrow in scope as the nature of the background radiation field is not known precisely. In this work we argue that the critical condition for suppressing the H2 cooling in the collapsing gas could be described in a more general way by a combination of $k_{\rm H_2}$ and $k_{\rm H^-}$ parameters, without any additional assumptions about the shape of the underlying radiation spectrum. By performing a series of cosmological zoom-in simulations covering a wide range of relevant $k_{\rm H_2}$ and $k_{\rm H^-}$ parameters, we examine the gas flow by following evolution of basic parameters of the accretion flow. We test under what conditions the gas evolution is dominated by $\rm H_{2}$ and/or atomic cooling. We confirm the existence of a critical curve in the $k_{\rm H_2}{\!-\!}k_{\rm H^-}$ plane and provide an analytical fit to it. This curve depends on the conditions in the direct collapse, and reveals domains where the atomic cooling dominates over the molecular cooling. Furthermore, we have considered the effect of $\rm H_{2}$ self-shielding on the critical curve, by adopting three methods for the effective column density approximation in $\rm H_{2}$. We find that the estimate of the characteristic length scale for shielding can be improved by using λJeans25, which is 0.25 times that of the local Jeans length, which is consistent with previous one-zone modelling.
VVV-WIT-01: highly obscured classical nova or protostellar collision?
Authors: Lucas P W , Minniti D , Kamble A , Kaplan D L , Cross N , Dekany I , Ivanov V D , Kurtev R , Saito R K , Smith L C , Catelan M , Masetti N , Toledo I , Hempel M , Thompson M A , Contreras Peña C , Forbrich J , Krause M , Dale J , Borissova J , Emerson J 
Published: January 2020

ABSTRACT
A search of the first Data Release of the VISTA Variables in the Via Lactea (VVV) Survey discovered the exceptionally red transient VVV-WIT-01 (H − Ks = 5.2). It peaked before March 2010, then faded by ∼9.5 mag over the following 2 yr. The 1.6–22 μm spectral energy distribution in March 2010 was well fit by a highly obscured blackbody with T ∼ 1000 K and $A_{K_s} \sim 6.6$ mag. The source is projected against the Infrared Dark Cloud (IRDC) SDC G331.062−0.294. The chance projection probability is small for any single event (p ≈ 0.01–0.02), which suggests a physical association, e.g. a collision between low mass protostars. However, blackbody emission at T ∼ 1000 K is common in classical novae (especially CO novae) at the infrared peak in the light curve due to condensation of dust ∼30–60 d after the explosion. Radio follow-up with the Australia Telescope Compact Array detected a fading continuum source with properties consistent with a classical nova but probably inconsistent with colliding protostars. Considering all VVV transients that could have been projected against a catalogued IRDC raises the probability of a chance association to p = 0.13–0.24. After weighing several options, it appears likely that VVV-WIT-01 was a classical nova event located behind an IRDC.
Atmospheric parameters at the 6-m Big Telescope Alt-azimuthal site
Authors: Shikhovtsev A Yu , Bolbasova L A , Kovadlo P G , Kiselev A V 
Published: January 2020

ABSTRACT
In this paper, we introduce the results of the statistical analysis of atmospheric characteristics at the site of the Big Telescope Alt-azimuthal (BTA) of the Special Astrophysical Observatory (SAO) of the Russian Academy of Science (RAS). The BTA is the largest optical telescope in Eurasia and is located near Mt Pastukhova in the northern part of the Caucasus Mountains, at an altitude of 2070 m above sea level. The atmosphere of the Earth is a major challenge for observing and it limits the quality of astronomical images obtained by ground-based telescopes. The study of the atmosphere above astronomical observatories is important for the planning of observing time, for the optimization of instrument performance and for the development of adaptive optics systems. We discuss the results of a study of the meteorological conditions at the BTA site: total cloud cover, wind speed at the pressure level of 200 hPa, vertical motions, vertical profiles of the wind speed employing data from the ERA-Interim and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) re-analysis data bases.
An ALMA survey of the SCUBA-2 cosmology legacy survey UKIDSS/UDS field: Dust attenuation in high-redshift Lyman-break galaxies
Authors: Koprowski M P , Coppin K E K , Geach J E , Dudzevičiūtė U , Smail Ian , Almaini O , An Fangxia , Blain A W , Chapman S C , Chen Chian-Chou , Conselice C J , Dunlop J S , Farrah D , Gullberg B , Hartley W , Ivison R J , Karska A , Maltby D , Malek K , Michałowski M J , Pope A , Salim S , Scott D , Simpson C J , Simpson J M , Swinbank A M , Thomson A P , Wardlow J L , van der Werf P P , Whitaker K E 
Published: January 2020

ABSTRACT
We analyse 870 $\mu$m Atacama Large Millimetre Array (ALMA) dust continuum detections of 41 canonically selected $z$ ≃ 3 Lyman-break galaxies (LBGs), as well as 209 ALMA-undetected LBGs, in follow-up of SCUBA-2 mapping of the UKIDSS Ultra Deep Survey (UDS) field. We find that our ALMA-bright LBGs lie significantly off the local IRX-beta relation and have relatively bluer rest-frame UV slopes (as parametrized by β), given their high values of the ‘infrared excess’ (IRX ≡ LIR/LUV), relative to the average ‘local’ IRX-β relation. We attribute this finding in part to the young ages of the underlying stellar populations but we find that the main reason behind the unusually blue UV slopes are the relatively shallow slopes of the corresponding dust attenuation curves. We show that, when stellar masses, M*, are being established via SED fitting, it is absolutely crucial to allow the attenuation curves to vary (rather than fixing it on Calzetti-like law), where we find that the inappropriate curves may underestimate the resulting stellar masses by a factor of ≃2–3× on average. In addition, we find these LBGs to have relatively high specific star-formation rates (sSFRs), dominated by the dust component, as quantified via the fraction of obscured star formation $(f_{\rm obs}\equiv {\rm SFR_{\rm IR}/{\rm SFR}_{\rm UV+IR}})$. We conclude that the ALMA-bright LBGs are, by selection, massive galaxies undergoing a burst of a star formation (large sSFRs, driven, for example, by secular or merger processes), with a likely geometrical disconnection of the dust and stars, responsible for producing shallow dust attenuation curves.
Spectral evidence of an accretion disc in wind-fed X-ray pulsar Vela X-1 during an unusual spin-up period
Authors: Liao Zhenxuan , Liu Jiren , Zheng Xueying , Gou Lijun 
Published: January 2020

ABSTRACT
In classical supergiant X-ray binaries (SgXBs), the Bondi–Hoyle–Lyttleton wind accretion was usually assumed, and the angular momentum transport to the accretors is inefficient. The observed spin-up/spin-down behaviour of the neutron star in SgXBs is not well understood. In this paper, we report an extended low state of Vela X-1 (at orbital phases 0.16–0.2), lasting for at least 30 ks, observed with Chandra during the onset of an unusual spin-up period. During this low state, the continuum fluxes dropped by a factor of 10 compared to the preceding flare period, and the continuum pulsation almost disappeared. Meanwhile, the Fe K α fluxes of the low state were similar to the preceding flare period, leading to an Fe K α equivalent width (EW) of 0.6 keV, as high as the Fe K α EW during the eclipse phase of Vela X-1. Both the pulsation cessation and the high Fe K α EW indicate an axisymmetric structure with a column density larger than 1024 cm−2 on a spatial scale of the accretion radius of Vela X-1. These phenomena are consistent with the existence of an accretion disc that leads to the following spin-up of Vela X-1. It indicates that disc accretion, although not always, does occur in classical wind-fed SgXBs.
First results from MFOSC-P: low-resolution optical spectroscopy of a sample of M dwarfs within 100 parsecs
Authors: Rajpurohit A S , Kumar Vipin , Srivastava Mudit K , Allard F , Homeier D , Dixit Vaibhav , Patel Ankita 
Published: January 2020

ABSTRACT
Mt Abu Faint Object Spectrograph and Camera (MFOSC-P) is an in-house-developed instrument for the Physical Research Laboratory (PRL) 1.2 m telescope at Mt Abu, India, commissioned in 2019 February. Here we present the first science results derived from the low-resolution spectroscopy programme of a sample of M dwarfs carried out during the commissioning run of MFOSC-P between 2019 February and June. M dwarfs carry great significance for exoplanet searches in the habitable zone and are among the promising candidates for the observatory’s several ongoing observational campaigns. Determination of their accurate atmospheric properties and fundamental parameters is essential to constrain both their atmospheric and evolutionary models. In this study, we provide a low-resolution (R ∼ 500) spectroscopic catalogue of 80 bright M dwarfs (J &lt; 10) and classify them using their optical spectra. We have also performed spectral synthesis and χ2 minimization techniques to determine their fundamental parameters regarding effective temperature and surface gravity by comparing the observed spectra with the most recent BT-Settl synthetic spectra. The spectral type of M dwarfs in our sample ranges from M0 to M5. The derived effective temperature and surface gravity range from 4000–3000 K and 4.5–5.5 dex, respectively. In most of the cases, the derived spectral types are in good agreement with previously assigned photometric classifications.
The accretion rates and mechanisms of Herbig Ae/Be stars
Authors: Wichittanakom C , Oudmaijer R D , Fairlamb J R , Mendigutía I , Vioque M , Ababakr K M 
Published: January 2020

ABSTRACT
This work presents a spectroscopic study of 163 Herbig Ae/Be stars. Amongst these, we present new data for 30 objects. Stellar parameters such as temperature, reddening, mass, luminosity, and age are homogeneously determined. Mass accretion rates are determined from $\rm H\alpha$ emission line measurements. Our data is complemented with the X-Shooter sample from previous studies and we update results using Gaia DR2 parallaxes giving a total of 78 objects with homogeneously determined stellar parameters and mass accretion rates. In addition, mass accretion rates of an additional 85 HAeBes are determined. We confirm previous findings that the mass accretion rate increases as a function of stellar mass, and the existence of a different slope for lower and higher mass stars, respectively. The mass where the slope changes is determined tobe $3.98^{+1.37}_{-0.94}\, \rm M_{\odot }$. We discuss this break in the context of different modes of disc accretion for low- and high-mass stars. Because of their similarities with T Tauri stars, we identify the accretion mechanism for the late-type Herbig stars with the Magnetospheric Accretion. The possibilities for the earlier-type stars are still open, we suggest the Boundary Layer accretion model may be a viable alternative. Finally, we investigated themass accretion–age relationship. Even using the superior Gaia based data, it proved hard to select a large enough sub-sample to remove the mass dependence in this relationship. Yet, it would appear that the mass accretion does decline with age as expected from basic theoretical considerations.
Improved constraints from ultra-faint dwarf galaxies on primordial black holes as dark matter
Authors: Stegmann Jakob , Capelo Pedro R , Bortolas Elisa , Mayer Lucio 
Published: January 2020

ABSTRACT
Soon after the recent first ever detection of gravitational waves from merging black holes it has been suggested that their origin is primordial. Appealingly, a sufficient number of primordial black holes (PBHs) could also partially or entirely constitute the dark matter (DM) in our Universe. However, recent studies on PBHs in ultra-faint dwarf galaxies (UFDGs) suggest that they would dynamically heat up the stellar component due to two-body relaxation processes. From the comparison with the observed stellar velocity dispersions and the stellar half-light radii, it was claimed that only PBHs with masses $\lesssim 10\, {\rm M}_\odot$ can significantly contribute to the DM. In this work, we improve the latter constraints by considering the largest observational sample of UFDGs and by allowing the PBH masses to follow an extended (lognormal) distribution. By means of collisional Fokker–Planck simulations, we explore a wide parameter space of UFDGs containing PBHs. The analysis of the half-light radii and velocity dispersions resulting from the simulations leads to three general findings that exclude PBHs with masses $\sim \mathcal {O}(1\operatorname{-}100)\, {\rm M}_\odot {}$ from constituting all of the DM: (i) we identify a critical sub-sample of UFDGs that only allows for $\sim \mathcal {O}(1)\, {\rm M}_\odot$ PBH masses; (ii) for any PBH mass, there is an UFDG in our sample that disfavours it; (iii) the spatial extensions of a majority of simulated UFDGs containing PBHs are too large to match the observed.
The ‘red supergiant problem’: the upper luminosity boundary of Type II supernova progenitors
Authors: Davies Ben , Beasor Emma R 
Published: January 2020

ABSTRACT
By comparing the properties of red supergiant (RSG) supernova (SN) progenitors to those of field RSGs, it has been claimed that there is an absence of progenitors with luminosities L above log (L/L⊙) &gt; 5.2. This is in tension with the empirical upper luminosity limit of RSGs at log (L/L⊙) = 5.5, a result known as the ‘RSG problem’. This has been interpreted as an evidence for an upper mass threshold for the formation of black holes. In this paper, we compare the observed luminosities of RSG SN progenitors with the observed RSG L-distribution in the Magellanic Clouds. Our results indicate that the absence of bright SN II-P/L progenitors in this sample can be explained at least in part by the steepness of the L-distribution and a small sample size, and that the statistical significance of the RSG problem is between 1σ and 2σ . Secondly, we model the luminosity distribution of II-P/L progenitors as a simple power law with an upper and lower cut-off, and find an upper luminosity limit of $\log (L_{\rm hi}/\mathrm{L}_\odot) = 5.20^{+0.17}_{-0.11}$ (68 per cent confidence), though this increases to ∼5.3 if one fixes the power-law slope to be that expected from theoretical arguments. Again, the results point to the significance of the RSG problem being within ∼2σ. Under the assumption that all progenitors are the result of single-star evolution, this corresponds to an upper mass limit for the parent distribution of $M_{\rm hi} = 19.2\, {\rm M_\odot }$, $\pm 1.3 \, {\rm M_\odot (systematic)}$, $^{+4.5}_{-2.3} \, {\rm M_\odot }$ (random; 68 per cent confidence limits).
WDR5 is a conserved regulator of protein synthesis gene expression
Authors: Bryan Audra F , Wang Jing , Howard Gregory C , Guarnaccia Alissa D , Woodley Chase M , Aho Erin R , Rellinger Eric J , Matlock Brittany K , Flaherty David K , Lorey Shelly L , Chung Dai H , Fesik Stephen W , Liu Qi , Weissmiller April M , Tansey William P 
Published: January 2020

Abstract
WDR5 is a highly-conserved nuclear protein that performs multiple scaffolding functions in the context of chromatin. WDR5 is also a promising target for pharmacological inhibition in cancer, with small molecule inhibitors of an arginine-binding pocket of WDR5 (the ‘WIN’ site) showing efficacy against a range of cancer cell lines in vitro. Efforts to understand WDR5, or establish the mechanism of action of WIN site inhibitors, however, are stymied by its many functions in the nucleus, and a lack of knowledge of the conserved gene networks—if any—that are under its control. Here, we have performed comparative genomic analyses to identify the conserved sites of WDR5 binding to chromatin, and the conserved genes regulated by WDR5, across a diverse panel of cancer cell lines. We show that a specific cohort of protein synthesis genes (PSGs) are invariantly bound by WDR5, demonstrate that the WIN site anchors WDR5 to chromatin at these sites, and establish that PSGs are bona fide, acute, and persistent targets of WIN site blockade. Together, these data reveal that WDR5 plays a predominant transcriptional role in biomass accumulation and provide further evidence that WIN site inhibitors act to repress gene networks linked to protein synthesis homeostasis.
Effectiveness of Proactive Tobacco Cessation Treatment Outreach Among Smokers With Serious Mental Illness
Authors: Japuntich Sandra J , Hammett Patrick J , Rogers Erin S , Fu Steven , Burgess Diana J , El Shahawy Omar , Melzer Anne C , Noorbaloochi Siamak , Krebs Paul , Sherman Scott E 
Published: January 2020

Abstract

Introduction
People with serious mental illness (SMI) have a high smoking prevalence and low quit rates. Few cessation treatments are tested in smokers with SMI. Mental health (MH) providers are reluctant to address smoking. Proactive tobacco cessation treatment strategies reach out directly to smokers to offer counseling and medication and improve treatment utilization and quit rates. The current study is a secondary analysis of a randomized controlled trial of proactive outreach for tobacco cessation treatment in VA MH patients.

Aims and Methods
Participants (N = 1938, 83% male, mean age 55.7) across four recruitment sites, who were current smokers and had a MH visit in the past 12 months, were identified using the electronic medical record. Participants were randomized to Intervention (telephone outreach call plus invitation to engage in MH tailored telephone counseling and assistance obtaining nicotine replacement therapy) or Control (usual care). The current study assessed outcomes in participants with SMI (N = 982).

Results
Compared to the Control group, participants assigned to the Intervention group were more likely to engage in telephone counseling (22% vs. 3%) and use nicotine replacement therapy (51% vs. 41%). Participants in the Intervention group were more likely to be abstinent (7-day point prevalence; 18%) at 12 months than participants in the Control group (11%) but equally likely to make quit attempts.

Conclusions
Proactive tobacco cessation treatment is an effective strategy for tobacco users with SMI. Proactive outreach had a particularly strong effect on counseling utilization. Future randomized clinical trials examining proactive tobacco treatment approaches in SMI treatment settings are needed.

Implications
Few effective treatment models exist for smokers with SMI. Proactive tobacco cessation outreach with connections to MH tailored telephone counseling and medication promotes tobacco abstinence among smokers with SMI and is an effective treatment strategy for this underserved population.
Teachers’ Pay for Performance in the Long-Run: The Dynamic Pattern of Treatment Effects on Students’ Educational and Labour Market Outcomes in Adulthood
Authors: Lavy Victor 
Published: January 2020

Abstract
This article examines the dynamic effects of a teachers’ pay for performance experiment on long-term outcomes at adulthood. The program led to a gradual increase in university education of the treated high school students, reaching an increase of 0.25 years of schooling by age 28–30. The effects on employment and earnings were initially negative, coinciding with a higher rate of enrolment in university, but became positive and significant with time. These gains are largely mediated by the positive effect of the program on several high school outcomes, including quantitative and qualitative gains in the high-stakes matriculation exams.
The Colonial–Religious Institutional Contract: Muslim Women Activists in Israel
Authors: Ashqar-Sharary Nahed , Abu-Rabia-Queder Sarab 
Published: January 2020

Abstract
This study examines the growth of a progressive religious Muslim activism among Palestinian women in Israel and the challenges it poses to the religious patriarchy and colonial power structures. Based on semistructured interviews with a religious feminist organization’s activists, the study revealed that feminist Islamic activism addresses an alliance between state officials and patriarchal–religious establishment gatekeepers that interlock to block Muslim feminist reform. Unlike other Muslim activists in former settler colonial states where state and religion are separate and unlike progressive Muslim women in Muslim states who struggle to escape the religious–patriarchal trap, in Israel, these activists face a religious–colonial–patriarchal trap.
Stability Analysis of Delayed Age-structured Resource-Consumer Model of Population Dynamics with Saturated Intake Rate
Authors: Akimenko Vitalii V. 
Published: January 2020

AbstractThe nonlinear n-resource-consumer autonomous system with age-structured consumer population is studied. While the model of consumer population dynamics is described by a delayed transport equation, the dynamics of resource patches are described by ordinary differential equations with saturated intake rate. The delay models the digestion period of generalist consumer and is included in the calorie intake rate which impacts on consumer’s fertility and mortality. Saturated intake rate models the inhibition effect from the behavioural change of the resource patches when they react on the consumer population growing or from the crowding effect of the consumer. The model is studied both analytically and numerically. Conditions for existence of trivial, semi-trivial and non-trivial equilibria and their local asymptotic stability are obtained. Numerical experiments confirm and illustrate these theoretical results.
Programmable low-cost DNA-based platform for viral RNA detection
Authors: Zhou Lifeng , Chandrasekaran Arun Richard , Punnoose Jibin Abraham , Bonenfant Gaston , Charles Stephon , Levchenko Oksana , Badu Pheonah , Cavaliere Cassandra , Pager Cara T. , Halvorsen Ken 
Published: January 2020

AbstractViral detection is critical for controlling disease spread and progression. Recent emerging viral threats including Zika, Ebola, and the current COVID-19 outbreak highlight the cost and difficulty in responding rapidly. To address these challenges, we develop a platform for low-cost and rapid detection of viral RNA with DNA nanoswitches designed to mechanically reconfigure in response to specific viruses. Using Zika virus as a model system, we show non-enzymatic detection of viral RNA to the attomole level, with selective and multiplexed detection between related viruses and viral strains. For clinical-level sensitivity in biological fluids, we paired the assay with a sample preparation step using either RNA extraction or isothermal pre-amplification. Our assay can be performed with minimal or no lab infrastructure, and is readily adaptable to detect other viruses. We demonstrate the adaptability of our method by quickly developing and testing DNA nanoswitches for detecting a fragment of SARS-CoV-2 RNA in human saliva. Given this versatility, we expect that further development and field implementation will improve our ability to detect emergent viral threats and ultimately limit their impact.