bluuebunny/crossref_metadata_2025_split huggingface dataset:
Birth of convective low-mass to high-mass second Larson cores
Authors: Bhandare Asmita , Kuiper Rolf , Henning Thomas , Fendt Christian , Flock Mario , Marleau Gabriel-Dominique 
Published: May 2020

Context. Stars form as an end product of the gravitational collapse of cold, dense gas in magnetized molecular clouds. This fundamentally multi-scale scenario occurs via the formation of two quasi-hydrostatic Larson cores and involves complex physical processes, which require a robust, self-consistent numerical treatment.
Aims. The primary aim of this study is to understand the formation and evolution of the second hydrostatic Larson core and the dependence of its properties on the initial cloud core mass.
Methods. We used the PLUTO code to perform high-resolution, one- and two-dimensional radiation hydrodynamic (RHD) core collapse simulations. We include self-gravity and use a grey flux-limited diffusion approximation for the radiative transfer. Additionally, we use for the gas equation of state density- and temperature-dependent thermodynamic quantities (heat capacity, mean molecular weight, etc.) to account for effects such as dissociation of molecular hydrogen, ionisation of atomic hydrogen and helium, and molecular vibrations and rotations. Properties of the second core are investigated using one-dimensional studies spanning a wide range of initial cloud core masses from 0.5 M⊙ to 100 M⊙. Furthermore, we expand to two-dimensional (2D) collapse simulations for a selected few cases of 1 M⊙, 5 M⊙, 10 M⊙, and 20 M⊙. We follow the evolution of the second core for ≥100 years after its formation, for each of these non-rotating cases.
Results. Our results indicate a dependence of several second core properties on the initial cloud core mass. Molecular cloud cores with a higher initial mass collapse faster to form bigger and more massive second cores. The high-mass second cores can accrete at a much faster rate of ≈10−2 M⊙ yr−1 compared to the low-mass second cores, which have accretion rates as low as 10−5 M⊙ yr−1. For the first time, owing to a resolution that has not been achieved before, our 2D non-rotating collapse studies indicate that convection is generated in the outer layers of the second core, which is formed due to the gravitational collapse of a 1 M⊙ cloud core. Additionally, we find large-scale oscillations of the second accretion shock front triggered by the standing accretion shock instability, which has not been seen before in early evolutionary stages of stars. We predict that the physics within the second core would not be significantly influenced by the effects of magnetic fields or an initial cloud rotation.
Conclusions. In our 2D RHD simulations, we find convection being driven from the accretion shock towards the interior of the second Larson core. This supports an interesting possibility that dynamo-driven magnetic fields may be generated during the very early phases of low-mass star formation.
Wind-driven halo in high-contrast images
Authors: Cantalloube F. , Farley O. J. D. , Milli J. , Bharmal N. , Brandner W. , Correia C. , Dohlen K. , Henning Th. , Osborn J. , Por E. , Suárez Valles M. , Vigan A. 
Published: May 2020

Context.The wind-driven halo is a feature that is observed in images that were delivered by the latest generation of ground-based instruments that are equipped with an extreme adaptive optics system and a coronagraphic device, such as SPHERE at the Very Large Telescope (VLT). This signature appears when the atmospheric turbulence conditions vary faster than the adaptive optics loop can correct for. The wind-driven halo is observed as a radial extension of the point spread function along a distinct direction (this is sometimes referred to as the butterfly pattern). When this is present, it significantly limits the contrast capabilities of the instrument and prevents the extraction of signals at close separation or extended signals such as circumstellar disks. This limitation is consequential because it contaminates the data for a substantial fraction of the time: about 30% of the data produced by the VLT/SPHERE instrument are affected by the wind-driven halo.Aims.This paper reviews the causes of the wind-driven halo and presents a method for analyzing its contribution directly from the scientific images. Its effect on the raw contrast and on the final contrast after post-processing is demonstrated.Methods.We used simulations and on-sky SPHERE data to verify that the parameters extracted with our method can describe the wind-driven halo in the images. We studied the temporal, spatial, and spectral variation of these parameters to point out its deleterious effect on the final contrast.Results.The data-driven analysis we propose provides information to accurately describe the wind-driven halo contribution in the images. This analysis confirms that this is a fundamental limitation of the finally reached contrast performance.Conclusions.With the established procedure, we will analyze a large sample of data delivered by SPHERE in order to propose post-processing techniques that are tailored to removing the wind-driven halo.
Temporal evolution of oscillating coronal loops
Authors: Goddard C. R. , Nisticò G. 
Published: May 2020

Context. Transverse oscillations of coronal structures are currently intensively studied to explore the associated magnetohydrodynamic wave physics and perform seismology of the local medium.
Aims. We make a first attempt to measure the thermodynamic evolution of a sample of coronal loops that undergo decaying kink oscillations in response to an eruption in the corresponding active region.
Methods. Using data from the six coronal wavelengths of SDO/AIA, we performed a differential emission measure (DEM) analysis of 15 coronal loops before, during, and after the eruption and oscillation.
Results. We find that the emission measure, temperature, and width of the DEM distribution undergo significant variations on timescales relevant for the study of transverse oscillations. There are no clear collective trends of increases or decreases for the parameters we analysed. The strongest variations of the parameters occur during the initial perturbation of the loops, and the influence of background structures may also account for much of this variation.
Conclusions. The DEM analysis of oscillating coronal loops in erupting active regions shows evidence of evolution on timescales important for the study of oscillations. Further work is needed to separate the various observational and physical mechanisms that may be responsible for the variations in temperature, DEM distribution width, and total emission measure.
The GALAH survey: multiple stars and our Galaxy
Authors: Traven G. , Feltzing S. , Merle T. , Van der Swaelmen M. , Čotar K. , Church R. , Zwitter T. , Ting Y.-S. , Sahlholdt C. , Asplund M. , Bland-Hawthorn J. , De Silva G. , Freeman K. , Martell S. , Sharma S. , Zucker D. , Buder S. , Casey A. , D’Orazi V. , Kos J. , Lewis G. , Lin J. , Lind K. , Simpson J. , Stello D. , Munari U. , Wittenmyer R. A. 
Published: May 2020

Context. Binary stellar systems form a large fraction of the Galaxy’s stars. They are useful as laboratories for studying the physical processes taking place within stars, and must be correctly taken into account when observations of stars are used to study the structure and evolution of the Galaxy. The advent of large-scale spectroscopic and photometric surveys allows us to obtain large samples of binaries that permit characterising their populations.
Aims. We aim to obtain a large sample of double-lined spectroscopic binaries (SB2s) by analysis of spectra from the GALAH survey in combination with photometric and astrometric data. A combined analysis will provide stellar parameters of thousands of binary stars that can be combined to form statistical observables of a given population. We aim to produce a catalogue of well-characterised systems, which can in turn be compared to models of populations of binary stars, or to follow-up individual systems of interest.
Methods. We obtained a list of candidate SB2 systems from a t-distributed stochastic neighbour embedding (t-SNE) classification and a cross-correlation analysis of GALAH spectra. To compute parameters of the primary and secondary star, we used a Bayesian approach that includes a parallax prior from Gaia DR2, spectra from GALAH, and apparent magnitudes from APASS, Gaia DR2, 2MASS, and WISE. We used a Markov chain Monte Carlo approach to sample the posterior distributions of the following model parameters for the two stars: Teff[1,2], logg[1,2], [Fe/H], Vr[1,2], vmic[1,2], vbroad[1,2], R[1,2], and E(B−V).
Results. We present results for 12 760 binary stars detected as SB2s. We construct the statistical observables T1∕T2, ΔVr, and R1∕R2, which demonstrate that our sample mostly consists of dwarfs, with a significant fraction of evolved stars and several dozen members of the giant branch. The majority of these binary stars is concentrated at the lower boundary of the ΔVr distribution, and the R1∕R2 ratio is mostly close to unity. The derived metallicity of our binary stars is statistically lower than that of single dwarf stars from the same magnitude-limited sample.
Conclusions. Our sample of binary stars represents a large population of well-characterised double-lined spectroscopic binaries that are appropriate for statistical studies of the binary populations. The derived stellar properties and their distributions show trends that are expected for a population of close binary stars (a < 10 AU) detected through double lines in their spectra. Our detection technique allows us to probe binary systems with mass ratios 0.5 ≤q ≤ 1.
Catalogue of new Herbig Ae/Be and classical Be stars
Authors: Vioque M. , Oudmaijer R. D. , Schreiner M. , Mendigutía I. , Baines D. , Mowlavi N. , Pérez-Martínez R. 
Published: May 2020

Context. The intermediate-mass pre-main sequence Herbig Ae/Be stars are key to understanding the differences in formation mechanisms between low- and high-mass stars. The study of the general properties of these objects is hampered by the lack of a well-defined, homogeneous sample, and because few and mostly serendipitously discovered sources are known.
Aims. Our goal is to identify new Herbig Ae/Be candidates to create a homogeneous and well defined catalogue of these objects.
Methods. We have applied machine learning techniques to 4 150 983 sources with data from Gaia DR2, 2MASS, WISE, and IPHAS or VPHAS+. Several observables were chosen to identify new Herbig Ae/Be candidates based on our current knowledge of this class, which is characterised by infrared excesses, photometric variabilities, and Hα emission lines. Classical techniques are not efficient for identifying new Herbig Ae/Be stars mainly because of their similarity with classical Be stars, with which they share many characteristics. By focusing on disentangling these two types of objects, our algorithm has also identified new classical Be stars.
Results. We have obtained a large catalogue of 8470 new pre-main sequence candidates and another catalogue of 693 new classical Be candidates with a completeness of 78.8 ± 1.4% and 85.5 ± 1.2%, respectively. Of the catalogue of pre-main sequence candidates, at least 1361 sources are potentially new Herbig Ae/Be candidates according to their position in the Hertzsprung-Russell diagram. In this study we present the methodology used, evaluate the quality of the catalogues, and perform an analysis of their flaws and biases. For this assessment, we make use of observables that have not been accounted for by the algorithm and hence are selection-independent, such as coordinates and parallax based distances. The catalogue of new Herbig Ae/Be stars that we present here increases the number of known objects of the class by an order of magnitude.
Ambipolar diffusion in the Bifrost code
Authors: Nóbrega-Siverio D. , Martínez-Sykora J. , Moreno-Insertis F. , Carlsson M. 
Published: May 2020

Context. Ambipolar diffusion is a physical mechanism related to the drift between charged and neutral particles in a partially ionized plasma that is key to many different astrophysical systems. However, understanding its effects is challenging due to basic uncertainties concerning relevant microphysical aspects and the strong constraints it imposes on the numerical modeling.
Aims. Our aim is to introduce a numerical tool that allows us to address complex problems involving ambipolar diffusion in which, additionally, departures from ionization equilibrium are important or high resolution is needed. The primary application of this tool is for solar atmosphere calculations, but the methods and results presented here may also have a potential impact on other astrophysical systems.
Methods. We have developed a new module for the stellar atmosphere Bifrost code that improves its computational capabilities of the ambipolar diffusion term in the generalized Ohm’s law. This module includes, among other things, collision terms adequate to processes in the coolest regions in the solar chromosphere. As the main feature of the module, we have implemented the super time stepping (STS) technique, which allows an important acceleration of the calculations. We have also introduced hyperdiffusion terms to guarantee the stability of the code.
Results. We show that to have an accurate value for the ambipolar diffusion coefficient in the solar atmosphere it is necessary to include as atomic elements in the equation of state not only hydrogen and helium, but also the main electron donors like sodium, silicon, and potassium. In addition, we establish a range of criteria to set up an automatic selection of the free parameters of the STS method that guarantees the best performance, optimizing the stability and speed for the ambipolar diffusion calculations. We validate the STS implementation by comparison with a self-similar analytical solution.
Les bactéries, organismes de choix pour comprendre les mécanismes de réparation des protéines oxydées
Authors: Broc Marianne , Hachemane Mohand , Novelli Marine , Sourice Mathieu , Aussel Laurent 
Published: May 2020

Dans le cadre de l’unité d’enseignement « Rédiger en sciences » proposée par l’université d’Aix-Marseille, les étudiants du Master 2 de microbiologie se sont confrontés aux exigences de l’écriture scientifique.
Quatre thématiques leur ont été proposées : les virus géants, les systèmes de sécrétion, la motilité bactérienne et la réparation des protéines oxydées. Après un travail préparatoire effectué avec l’équipe pédagogique et les auteurs des publications originales, les étudiants, organisés en groupes de trois ou quatre, ont rédigé une Nouvelle soulignant les résultats majeurs et l’originalité des quatre articles étudiés. Complété par un entretien avec les chercheurs auteurs de ces articles, l’ensemble offre un éclairage original sur la compréhension du vivant dans le domaine de la microbiologie.
L’éthique des essais thérapeutiques
Authors: Alperovitch Annick , Lazar Philippe 
Published: May 2020

La pandémie de COVID-19 a conduit certains acteurs reconnus de la médecine à renoncer aux méthodes codifiées de la recherche médicale au profit d’affirmations établies dans l’urgence et sans réelle évaluation scientifique. Autant l’on peut comprendre que certains praticiens recourent à ce qui leur est ainsi proposé, autant cette confusion entre action dans l’urgence et recherche scientifique serait lourde de conséquences si elle venait à se généraliser, et cela à de multiples points de vue : image et rôle de la science, qualité et éthique de la recherche médicale et en fin de compte sort des malades soumis à des traitements mal évalués. Ce sont ces questions qui motivent la mise au point qui suit sur les questions d’éthique associées de longue date aux « essais thérapeutiques », cette procédure rationnelle d’acquisition dans les meilleurs délais d’informations fiables sur les avantages et les risques des traitements dont on envisage l’éventuelle utilisation.
Kombinationstherapie von schweren Onychomykosen – Empfehlungen eines Expertengremiums
Authors: Effendy I. , Mayer J. , Nenoff P. , Reinel D. , Schaller M. 
Published: May 2020

ZusammenfassungOnychomykosen sind schwer behandelbare Pilzinfektionen des Nagelorgans mit einer hohen Rezidivrate. Klinische Studien zeigen, dass bei gesicherter schwerer Nagelmykose durch Dermatophyten eine Steigerung der kompletten Heilungsrate (mykologisch plus klinisch) durch eine Kombinationsbehandlung mit lokal applizierten und oral verabreichten Antimykotika im Vergleich zur systemischen Monotherapie erreicht werden kann. Am besten untersucht sind Regime mit kontinuierlich täglicher Einnahme von Terbinafin und wöchentlicher Applikation eines Amorolfin-haltigen Nagellacks. Eine topische Monotherapie mit einem Nagellack kommt v. a. bei einer superfiziellen weißen Onychomykose (SWO) oder einer distal-subungualen Onychomykose (DSO) mit einem geringeren Befallsgrad ohne Beteiligung der Matrix infrage. Die mechanische Entfernung des infizierten Nagelmaterials und hygienische Maßnahmen unterstützen die Therapie. Kritisch für die Erfolgsaussichten ist eine hohe Langzeitadhärenz der Patienten. Die Therapie sollte bis zum Auftreten der Erscheinungsfreiheit andauern. Anschließend empfiehlt sich eine dauerhafte Rezidivprophylaxe mit antimykotischem Nagellack.
Verspätete Aufklärung vor Lasertherapie eines Naevus flammeus
Authors: Elsner P. , Meyer J. 
Published: May 2020

ZusammenfassungEin Naevus flammeus im Bereich der rechten Wange einer Patientin wurde von einem Dermatologen mit einem Diodenlaser behandelt. In der Folge kam es zu einer Wundheilungsstörung und einer hypertrophen Narbe, die in einer Klinik für plastische Chirurgie mittels Vollhauttransplantation korrigiert wurde. Es verblieben dokumentierte Narbenzustände sowie ein beginnendes Ektropium.Während ein von der Schlichtungsstelle beauftragter Gutachter keinen Behandlungsfehler feststellen konnte, kam die Schlichtungsstelle aufgrund rechtlicher Überlegungen zu dem Schluss, dass der Hautarzt gleichwohl der Patientin gegenüber für die eingetretenen Körperschäden haftbar sei, da keine rechtswirksame Einwilligung für die Laserbehandlung vorgelegen habe. Diese setze eine entsprechende Aufklärung voraus. Die Aufklärung der Patientin erfolgte jedoch am gleichen Tag, an dem ebenfalls die Behandlung durch den Hautarzt stattfand. Eine Aufklärung dürfe auch bei kleineren Eingriffen nicht erst so kurzfristig erfolgen, dass der Patient schon während der Aufklärung mit der anschließenden Durchführung des Eingriffs rechnen muss und deshalb unter Druck steht, sich nicht mehr aus dem bereits in Gang gesetzten Geschehensablauf lösen zu können.Gerade bei dermatologischen Eingriffen im Grenzbereich zwischen medizinischer Notwendigkeit und kosmetischer Indikation kommt einer umfassenden Aufklärung auch über seltene Risiken einer Behandlung als Voraussetzung für eine rechtswirksame Einwilligung in die Durchführung der Behandlung große Bedeutung zu. Diese sollte grundsätzlich mündlich und schriftlich sowie rechtzeitig vor der Behandlung stattfinden, um dem Patienten Bedenkzeit zu geben und die Voraussetzung für eine informierte Einwilligung zu schaffen. Von einer Aufklärung erst kurz vor Durchführung der Laserbehandlung am gleichen Tag ist abzuraten. Nach der umfassenden mündlichen Aufklärung und Beantwortung allfälliger Fragen des Patienten sollten der Umfang der Aufklärung und die Einwilligung schriftlich dokumentiert werden.
Colonoscopy later than 270 days in a fecal immunochemical test-based population screening program is associated with higher prevalence of colorectal cancer
Authors: Zorzi Manuel , Hassan Cesare , Capodaglio Giulia , Baracco Maddalena , Antonelli Giulio , Bovo Emanuela , Rugge Massimo 
Published: May 2020

Background Colorectal cancer (CRC) screening programs based on fecal immunochemical testing (FIT) generate substantial pressure on colonoscopy capacity in Europe. Thus, a relevant proportion of FIT-positive patients undergo colonoscopy after the recommended 30-day interval, which may be associated with an excess CRC risk.
Methods In a cohort of 50–69-year-old patients undergoing biennial rounds of FIT (OC-Hemodia latex agglutination test; cutoff 20 µg hemoglobin/g feces) between 2004 and 2017, we assessed the outcome at colonoscopy (low/high risk adenoma/CRC/advanced stage CRC) among FIT-positive patients, according to different time intervals. The association of each outcome with waiting time, and demographic and clinical factors, was analyzed through multivariable analysis.
Results 123 138/154 213 FIT-positive patients (79.8 %) underwent post-FIT colonoscopy. Time to colonoscopy was ≤ 30 days, 31–180 days, and ≥ 181 days in 50 406 (40.9 %), 71 724 (58.3 %), and 1008 (0.8 %) patients, respectively. At colonoscopy, CRC, high risk adenoma, and low risk adenoma were diagnosed in 4813 (3.9 %), 30 500 (24.8 %), and 22 986 (18.7 %) patients, respectively. An increased CRC prevalence at colonoscopy was observed for a time to colonoscopy of ≥ 270 days (odds ratio [OR] 1.75, 95 % confidence interval [CI] 1.15–2.67), whereas it was stable for waiting times of < 180 days. The proportion of advanced CRC also increased after 270 days (OR 2.79, 95 %CI 1.03–7.57). No increase for low or high risk adenomas according to time to colonoscopy was observed.
Conclusion In a European FIT-based screening program, post-FIT colonoscopy after 9 months was associated with an increased risk of CRC and CRC progression.
Bevölkerungsbezogene psychische Gesundheit als
Schlüsselfaktor im Umgang mit COVID-19
Authors: Hahad Omar , Gilan Donya A , Daiber Andreas , Münzel Thomas 
Published: May 2020

Zusammenfassung
Ziel Das Ziel des Beitrages besteht darin, auf die bedeutsame Rolle der
Prävention und Reduktion der psychischen Belastungen in der
Allgemeinbevölkerung und in sensiblen Gruppen im Rahmen der
Coronavirus-Krankheit-2019 (COVID-19) -Pandemie hinzuweisen.
Methodik Der vorliegende Beitrag umfasst die Analyse und Bewertung von
Studien und Empfehlungen von Organisationen wie der Weltgesundheitsorganisation
(WHO), die die bevölkerungsbezogenen psychischen Auswirkungen von
Epi-/Pandemien und deren Einfluss auf den weiteren Verlauf untersucht
haben.
Ergebnisse Angstbedingte Verhaltensweisen können sich negativ auf
den Verlauf von Epidemien auswirken. Im Rahmen vergangener Ausbrüche von
Infektionskrankheiten (Ebola- und Zika-Virus) konnte ermittelt werden, dass
maladaptive Verhaltensweisen, bedingt durch erhöhte psychische
Belastungen und Ängste, die Implementierung von Behandlungsstrategien
und -maßnahmen beeinträchtigen und zu einer stärkeren
Ausbreitung beitragen können. Hierbei können Strategien im
Umgang mit Infektionskrankheiten, die Verdrängung und
Unterdrückung von Ängsten beinhalten, einen Teufelskreis
auslösen, wobei Ängste und Verdrängung sich gegenseitig
verstärken.
Schlussfolgerungen Die COVID-19-Pandemie stellt eine immense
Herausforderung mit noch ungewissem Ausgang für Regierungen,
Gesundheitssysteme und Menschen dar, die mit erheblichen
Beeinträchtigungen der psychischen Gesundheit in der Bevölkerung
verbunden ist. Im Einklang mit Empfehlungen der WHO sollten nationale Leitlinien
und präventive Maßnahmen die psychischen Auswirkungen, die
Akzeptanz und Normalisierung von Ängsten und die Förderung von
Resilienz in der Bevölkerung im Umgang mit COVID-19 umfassen, um einer
weiteren Ausbreitung entgegenwirken zu können.