bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared Echoes of Optical Tidal Disruption Events: ∼1% Dust-covering Factor or Less at Subparsec Scale
Authors: Jiang Ning , Wang Tinggui , Hu Xueyang , Sun Luming , Dou Liming , Xiao Lin 
Published: April 2021

Abstract
The past decade has experienced an explosive increase of optically discovered tidal disruption events (TDEs) with the advent of modern time-domain surveys. However, we still lack a comprehensive observational view of their infrared (IR) echoes in spite of individual detections. To this end, we have conducted a statistical study of the IR variability of the 23 optical TDEs discovered between 2009 and 2018 using the full public data set of the Wide-field Infrared Survey Explorer. The detection of variability is performed on the difference images, yielding 11 objects with significant (>3σ) variability in at least one band, while dust emission can be only fit in 8 objects. Their peak dust luminosity is around 1041–1042 erg s−1, corresponding to a dust-covering factor f

c
∼ 0.01 at a subparsec scale. The only exception is the disputed source ASASSN-15lh, which shows an ultra-high dust luminosity (∼1043.5 erg s−1), and this makes its nature even more elusive. Other nondetected objects show even lower f

c
, which could be lower by one more order of magnitude. The derived f

c
is generally much lower than those of dusty tori in active galactic nuclei, suggesting either a dearth of dust or a geometrically thin and flat disk in the vicinity of supermassive black holes. Our results also indicate that the optical TDE sample (post-starburst galaxies overrepresented) is seriously biased to events with little dust at subparsec scale, while TDEs in dusty star-forming systems could be more efficiently unveiled by IR echoes.
The TW Hya Rosetta Stone Project IV: A Hydrocarbon-rich Disk Atmosphere
Authors: Cleeves L. Ilsedore , Loomis Ryan A. , Teague Richard , Bergin Edwin A. , Wilner David J. , Bergner Jennifer B. , Blake Geoffrey A. , Calahan Jenny K. , Cazzoletti Paolo , van Dishoeck Ewine F. , Guzmán Viviana V. , Hogerheijde Michiel R. , Huang Jane , Kama Mihkel , Öberg Karin I. , Qi Chunhua , van Scheltinga Jeroen Terwisscha , Walsh Catherine 
Published: April 2021

Abstract
Connecting the composition of planet-forming disks with that of gas giant exoplanet atmospheres, in particular through C/O ratios, is one of the key goals of disk chemistry. Small hydrocarbons like C2H and C3H2 have been identified as tracers of C/O, as they form abundantly under high C/O conditions. We present resolved c–C3H2 observations from the TW Hya Rosetta Stone Project, a program designed to map the chemistry of common molecules at 15–20 au resolution in the TW Hya disk. Augmented by archival data, these observations comprise the most extensive multi-line set for disks of both ortho and para spin isomers spanning a wide range of energies, E

u
= 29–97 K. We find the ortho-to-para ratio of c–C3H2 is consistent with 3 throughout extent of the emission, and the total abundance of both c–C3H2 isomers is (7.5–10) × 10−11 per H atom, or 1%–10% of the previously published C2H abundance in the same source. We find c–C3H2 comes from a layer near the surface that extends no deeper than z/r = 0.25. Our observations are consistent with substantial radial variation in gas-phase C/O in TW Hya, with a sharp increase outside ∼30 au. Even if we are not directly tracing the midplane, if planets accrete from the surface via, e.g., meridional flows, then such a change should be imprinted on forming planets. Perhaps interestingly, the HR 8799 planetary system also shows an increasing gradient in its giant planets’ atmospheric C/O ratios. While these stars are quite different, hydrocarbon rings in disks are common, and therefore our results are consistent with the young planets of HR 8799 still bearing the imprint of their parent disk’s volatile chemistry.
The Milky Way Project: Probing Star Formation with First Results on Yellowballs from DR2
Authors: Wolf-Chase Grace , Kerton C. R. , Devine Kathryn , Pouydal Anupa , Mori Johanna , Trujillo Leonardo , Cossairt Aurora , Schoultz Sarah , Jayasinghe Tharindu , Povich Matthew 
Published: April 2021

Abstract
Yellowballs (YBs) were first discovered during the Milky Way Project (MWP) citizen science initiative. The MWP users noticed compact, yellow regions in Spitzer Space Telescope mid-infrared (MIR) images of the Milky Way plane and asked professional astronomers to explain these “yellow balls.” Follow-up work by Kerton et al. determined that YBs likely trace compact photodissociation regions associated with massive and intermediate-mass star formation. The YBs were included as target objects in a version of the MWP launched in 2016, which produced a listing of over 6000 YB locations. We have measured distances, cross-match associations, physical properties, and MIR colors of ∼500 YBs within a pilot region covering the l = 30°–40°, b = ±1° region of the Galactic plane. We find that ∼20%–30% of YBs in our pilot region contain high-mass star formation capable of becoming expanding H ii regions that produce MIR bubbles. A majority of YBs represent intermediate-mass star-forming regions whose placement in evolutionary diagrams suggest they are still actively accreting and may be precursors to optically revealed Herbig Ae/Be nebulae. Many of these intermediate-mass YBs were missed by surveys of massive star formation tracers; thus, this catalog provides information for many new sites of star formation. Future work will expand this pilot region analysis to the entire YB catalog.
The Biermann Battery Driven by a Streaming Plasma
Authors: Ohira Yutaka 
Published: April 2021

Abstract
The Biermann battery is a promising generation mechanism of a seed magnetic field in the universe. We propose a new driving mechanism for the Biermann battery in an inhomogeneous plasma with a beam component. An inhomogeneous electron flow induced by the return current can make an electron pressure gradient that is not parallel to the density gradient. As a result, the magnetic field is generated by the Biermann battery. We demonstrate the new generation mechanism of the magnetic field by conducting three-fluid plasma simulations. By this mechanism, the first cosmic rays can generate the seed magnetic field with astrophysical scales at redshift around 20.
Precise Ages of Field Stars from White Dwarf Companions in Gaia DR2
Authors: Qiu Dan , Tian Hai-Jun , Wang Xi-Dong , Nie Jia-Lu , Hippel Ted von , Liu Gao-Chao , Fouesneau Morgan , Rix Hans-Walter 
Published: April 2021

Abstract
We analyze 4050 wide binary star systems involving a white dwarf (WD) and usually a main-sequence (MS) star, drawn from the large sample assembled by Tian et al. Using the modeling code BASE-9, we determine the system’s ages, the WD progenitors’ zero-age MS masses, the extinction values (A

V
), and the distance moduli. Discarding the cases with poor age convergences, we obtain ages for 3551 WDs, with a median age precision of σ

τ
/τ = 20%, and system ages typically in the range of 1–6 Gyr. We validated these ages against the very few known clusters and through cross validation of 236 WD-WD binaries. Under the assumption that the components are coeval in a binary system, this provides precise age constraints on the usually low-mass MS companions, mostly inaccessible by any other means.
An Energy-conserving Integrator for Conservative Hamiltonian Systems with Ten-dimensional Phase Space
Authors: Hu Shiyang , Wu Xin , Liang Enwei 
Published: April 2021

Abstract
In this paper, an implicit nonsymplectic exact energy-preserving integrator is specifically designed for a ten-dimensional phase-space conservative Hamiltonian system with five degrees of freedom. It is based on a suitable discretization-averaging of the Hamiltonian gradient, with a second-order accuracy to numerical solutions. A one-dimensional disordered discrete nonlinear Schrödinger equation and a post-Newtonian Hamiltonian system of spinning compact binaries are taken as our two examples. We demonstrate numerically that the proposed algorithm exhibits good long-term performance in the preservation of energy, if roundoff errors are neglected. This result is independent of time steps, initial orbital eccentricities, and regular and chaotic orbital dynamical behavior. In particular, the application of appropriately large time steps to the new algorithm is helpful in reducing time-consuming and roundoff errors. This new method, combined with fast Lyapunov indicators, is well suited to studying the influence of some parameters or initial conditions related to chaos in the two example problems. It is found that chaos in the former system is mainly responsible for one of the parameters. In the latter problem, a combination of small initial separations and high initial eccentricities can easily induce chaos.
Galactic O-type Stars in LAMOST Data
Authors: Li 李 Guang-Wei 广伟 
Published: April 2021

Abstract
This paper reports 209 O-type stars found with LAMOST. All 135 new O-type stars discovered so far with LAMOST are given. Among them, 94 stars are first presented in this sample. There are 1 Iafpe star, 5 Onfp stars, 12 Oe stars, 1 Ofc stars, 3 ON stars, 16 double-lined spectroscopic binaries, and 33 single-lined spectroscopic binaries. All O-type stars are determined based on LAMOST low-resolution spectra (R ∼ 1800), with their LAMOST median-resolution spectra (R ∼ 7500) as supplements.
Formation de la fracture territoriale en Nouvelle-Aquitaine
Authors: Lalanne Aurélie 
Published: April 2021

Cet article étudie la formation de la fracture territoriale en Nouvelle-Aquitaine sur deux siècles (1800-2015) et analyse le système urbain régional dans son ensemble. Cette vaste région contrastée, comptant autant d’atouts métropolitains que des communes rurales à faible attractivité, fait face à des enjeux d’équité et de cohésion territoriale que le prisme métropolitain des récentes réformes territoriales exacerbent. D’une part, cet article revisite les principes théoriques d’organisation des systèmes urbains (lois de Zipf et de Gibrat) en les mobilisant en tant qu’outils méthodologiques (paramétriques et non-paramétriques) permettant de décrire le creusement des inégalités de taille, d’appréhender l’évolution du lien entre la taille des communes et leur croissance ainsi que l’importance de la proximité à Bordeaux dans les dynamiques de croissance. D’autre part, cet article questionne les capacités de ruissellement d’une métropole ainsi que la possibilité des politiques d’attractivité à assurer la cohésion démographique, économique et sociale des territoires. Classification JEL : R11, R12.
Migration résidentielle vers le rural et le périurbain : un processus ségrégatif ?
Authors: Batisse Cécile , Truchet Stéphanie , Zhu Nong 
Published: April 2021

À partir des données issues du recensement général de la population de 2014, nous analysons à l’échelle des bassins de vie, le lien entre migration résidentielle à destination des espaces ruraux et périurbains et ségrégation socio-spatiale. Nos résultats montrent que les individus sont sensibles aux caractéristiques sociodémographiques du voisinage dans leurs territoires d’origine et de destination. Alors que le capital humain est source de rétention pour les territoires d’origine, les individus mobiles apparaissent sensibles au degré d’homogénéité sociale des territoires. Enfin, l’influence des caractéristiques sociodémographiques sur les migrations résidentielles vers les territoires ruraux et périurbains varie selon les catégories socioprofessionnelles. Classification JEL : J61, R23, R15, C01.
Efficacy and Safety of SanJieZhenTong Capsules, a Traditional Chinese Patent Medicine, on Long-term Management of Endometriosis: A Randomized Controlled Trial
Authors: Ruan Jing-Yao , Zheng Yun-Xi , Tian Qi , Ke Jun-Ya , Wang Li , Du Yan , Zhu Zhi-Ling , Yi Xiao-Fang , Xu Cong-Jian 
Published: April 2021

Abstract

Objective:
To compare the efficacy of the traditional Chinese medicine SanJieZhenTong (SJZT) capsules versus gonadotropin-releasing hormone analogs (GnRHa) or oral contraceptives (OCs) in the postoperative treatment of moderate-to-severe endometriosis.

Methods:
In this prospective clinical trial, women with stage III-IV endometriosis according to the revised American Fertility Society scoring system received three doses of GnRHa immediately after laparoscopic conservative surgery, followed by random assignment to receive treatment with SJZT, GnRHa, or OCs for another 6 months. The primary endpoint was 2-year recurrence, and the secondary endpoints were adverse events, changes in physical function, and quality of life (QoL). Recurrence was assessed using Kaplan-Meier curves and log-rank tests. Generalized estimating equations were used to determine the parameters of the secondary endpoints.

Results:
A total of 66 women were randomly assigned to the SJZT (n = 21), GnRHa (n = 21), and OCs (n = 24) groups. At a median follow-up of 22 months, no difference in recurrence was found (P = 0.72), with one (4.8%), two (9.5%), and one (4.2%) incidence in the SJZT, GnRHa, and OCs groups, respectively. Expectedly, the incidence of side effects such as hot flush, insomnia, and arthralgia in the SJZT and OCs groups was significantly lower than that in the GnRHa group (P = 0.00). In addition, the female sexual function index was significantly improved in the SJZT group, with a higher value than that in the GnRHa (odds ratio [OR] = 5.25, 95% confidence interval [CI]: 2.09-13.14, P = 0.00) and OCs (OR = 3.94, 95% CI: 1.58-9.83, P = 0.00) groups.

Conclusions:
SJZT showed more effective pain relief and QoL improvement in patients with moderate-to-severe endometriosis than GnRHa or OCs did. Fewer adverse events than those observed with other agents indicate that this alternative medicine, SJZT, could be a novel option for the long-term management of endometriosis.
Compliance with the use of Compression Stockings, Experience from a Tertiary Center in Oman
Authors: AlHarthi Rahma , Stephen Edwin , Abdelhedy Ibrahim , AlMaawali Hanan , AlWahaibi Khalifa 
Published: April 2021

Objectives:
Compression stockings (CSs) are effective in the treatment of chronic venous and lymphatic diseases. Noncompliance with wearing them remains a hindrance to good results. This study aims to quantify the issue of noncompliance and to identify the reasons behind it.

Methods:
Over a period of 6 months, a set of questionnaire to assess the compliance to CSs was conducted on patients seen during their follow-up visits and of whom CSs were prescribed previously.

Results:
A total of 50 patients were recruited in this study. Females formed the majority of participants (76%), with a mean age of 42 years. The body mass index of our participants ranged between normal (18%), overweight (52%), and obese (30%). Most (78%) of our patients used CSs, while 22% did not. Duration of use ranged as follows: 40% of the patients used them for <2 weeks, 26% used them for 2–8 weeks, while 30% used them for >8 weeks. 71% of our patients encountered difficulty in finding appropriate CSs.

Conclusions:
Noncompliance with CSs is a true challenge. The reasons behind it start from difficulty in finding appropriate size/quality, to patient-related characteristics. These need to be frequently assessed by the prescribing doctor and addressed.
Influence of Body Mass Index on Developing Ulceration in Patients with Venous Disease
Authors: Lal Pearl , Stephen Edwin , Premkumar Prabhu , Kota Albert A , Samuel Vimalin , Agarwal Sunil , Selvaraj Dheepak 
Published: April 2021

Aim:
The aim of this study was to assess the influence of body mass index (BMI) on the development of ulceration in patients with venous disease. We also analyzed other risk factors that might lead to the progression of disease to ulceration.

Design:
A prospective case–control study from January 2016 to June 2017.

Materials and Methods:
This study was conducted at the vascular surgery outpatient department of a tertiary care hospital in India. One hundred and thirty cases with an active or healed venous ulcer were compared with 130 controls with no ulceration. A questionnaire was administered to look at the factors that influence the risk of developing ulceration. The patients underwent a clinical examination and the clinical class of venous disease was documented using the Clinical, Etiological, Anatomical and Pathophysiological classification. The patient's height and weight were measured, and the BMI was calculated.

Results:
The mean BMI of the study population was 29.04. Nearly 38.8% of the 260 patients recruited were obese and another 38.8% were overweight. Nearly 35.4% of the cases and 42.3% of the controls were obese. About 45.5% of the obese patients had an active or healed ulcer. About 77.8% of the patients with recurrent ulcers were either overweight or obese. However, on comparing the BMI between the cases and controls, there was no statistically significant difference. On multivariate analysis, we found older age, male gender, deep-vein thrombosis, and prolonged periods of standing, to have a significant association with ulceration in venous disease.

Conclusion:
Our study suggests that there is no association between BMI and ulceration in patients with venous disease. Older age, male gender, deep-vein thrombosis, and periods of prolonged standing have a higher association with venous ulceration.
Retrograde Mesenteric Bypass with Saphenous Vein Graft in Chronic Mesenteric Ischemia in a Resource-Challenged Setting
Authors: Sharma Anil , Dixit Sunil , Mittal Sourabh , Sharma Dhruva 
Published: April 2021

Introduction:
Chronic mesenteric ischemia is a pathophysiologic condition arising due to demand–supply mismatch of blood supply to bowel postprandially, resulting in chronic abdominal pain, food fear, and weight loss. The most common cause is atherosclerosis. Timely intervention in the form of mesenteric revascularization is the key to successful outcome. There are limited contemporary data on in-hospital outcomes of mesenteric revascularization via open versus endovascular therapy in a resource-challenged setting.

Materials and Methods:
This retrospective-prospective observational study included eight patients of chronic mesenteric ischemia who underwent open revascularization and were followed for a mean duration of 15 months. All patients were evaluated as per the institutional protocol, and retrograde mesenteric bypass with reverse saphenous vein graft was done in all cases. Outcomes were evaluated in terms of resolution of symptoms and confirmation of graft patency with duplex scan after 1 month and every 6 months thereafter.

Results:
Out of 8 patients, six patients were males. Predisposing factors for atheromatous diseases were present in all. All patients presented with postprandial abdominal pain and weight loss. Majority of patients (n = 5) had involvement of all three mesenteric vessels (superior mesenteric artery, inferior mesenteric artery, and celiac axis). One patient was re-explored for bleeding in immediate postoperative period. One patient was admitted for small bowel obstruction in 1st month of follow-up after surgery and was managed conservatively. Two patients were lost to follow-up and six patients are symptom free and doing well on a close follow-up of 15 months.

Conclusion:
Open mesenteric revascularization, by reverse saphenous vein graft as conduit for bypass, performed by experienced surgeon gives promising results in terms of symptom-free duration and graft patency and can be preferred over endoscopic revascularization as a viable option in resource-challenged settings in developing nations.
Bayesian multilevel model application on determinants of perinatal mortality in Ethiopia using 2011 and 2016 EDHS data
Authors: Debelu Berhanu Bekele , Belay Denekew Bitew , Terye Nigatu Degu 
Published: April 2021

Perinatal mortality is the death of a fetus after the age of viability until the 7th day of life. Perinatal mortality is estimated by the addition of stillbirths plus the early neonatal mortality, which represents deaths occurring during the first 7 days after delivery. Perinatal mortality remains a great burden in Ethiopia. The purpose of this study was to assess and compare the demographic and socio-economic determinant factors of perinatal mortality in Ethiopia using the 2011 and 2016 Ethiopian Demographic Health Surveys (EDHS). For data analysis, the Bayesian multilevel Model was used in this study. The study revealed that there is a regional variation in perinatal mortality and this variation was high in 2011 EDHS than in 2016 EDHS data. Factors like sex of the child, age of mother, wealth index, family size, birth order, source of drinking water, place of residence, place of delivery, and child twin were found to be the determinant factors of perinatal mortality in both 2011 and 2016 EDHS. In this study, we found that perinatal mortality variation across regions has decreased from 2011 to 2016 surveys which shows the promising progress of health intervention in the country.
Legitimizing the development and use of Cameroon’s national languages: Lessons from COVID-19
Authors: Akumbu Pius W. 
Published: April 2021

The advent of COVID-19 has revealed the inability of the Cameroonian Government to provide information to all its citizens in the languages they understand best since a majority of the languages are neither developed for use nor empowered by the language policy of the country. Based on data from online and secondary sources this study highlights and insists on the necessity to develop and use national languages in official communication particularly when transmitting health related information. If this is done, it will become possible to easily reach out to all Cameroonians with vital information for their wellbeing whenever need be. Other sectors of the country such as education and agriculture would benefit squarely from a language policy that incorporates the language of each and every Cameroonian.
Keywords: Legitimize, development, use, national languages, Cameroon, COVID-19

L’avènement du COVID-19 a révélé l’incapacité du gouvernement camerounais à informer ses citoyens dans les langues qu’ils comprennent puisqu’une majorité de ces langues ne sont ni développées pour être utilisées ni habilitées par la politique linguistique du pays. Sur la base de données provenant de sources en ligne et secondaires, cette contribution souligne et insiste sur la nécessité de développer et d’utiliser les langues nationales dans la communication officielle, en particulier lorsqu’il s’agit de transmettre des informations liées à la santé. Si cela est fait, il deviendra possible de tendre facilement la main à tous les Camerounais chaque fois qu’il sera nécessaire de leur transmettre des informations vitales pour leur bien-être. D’autres secteurs du pays, tels que l’éducation et l’agriculture, bénéficieraient aussi d’une politique linguistique qui intègre la langue de chaque Camerounais.
Mots clés : Légitimer, développement, utilisation, langues nationales, Cameroun, COVID-19