bluuebunny/crossref_metadata_2025 huggingface dataset:
A moral no ensino superior: produções científicas sobre desenvolvimento moral e formação de professores
Authors: Martins Maíra de Oliveira , Gonçalves Érica de Cassia
Published: February 2021

Este trabalho trata-se de uma pesquisa bibliográfica acerca do desenvolvimento moral na formação de professores. Para isto, pesquisamos os artigos científicos que envolvem o desenvolvimento moral na formação de professores, pois consideramos importante que haja uma preocupação com a formação moral destes, visto que são os agentes mediadores em sala de aula e formadores de crianças em desenvolvimento. Nesta pesquisa, encontramos poucos trabalhos que tratam destes temas de maneira íntima, o que nos leva a pensar que existe muito trabalho a fazer. Isto também se nota a partir das relações existentes nas escolas, os conflitos, e o despreparo do professor para lidar com estas questões. Nos propusemos a investigar as pesquisas relacionadas com esta temática a fim de contribuir para uma reflexão mais ampla, no sentido de como o ensino superior pode formar professores qualificados adequadamente para lidar com questões que extrapolam o campo intelectual; como também, no próprio ensino superior, ultrapassar o campo universitário e pensar o professor atuante, aquele que lida com inúmeros problemas sociais, econômicos e afetivos de seus alunos. Tendo um papel tão importante que é do professor, acreditamos que precisam, e merecem, uma formação mais digna de atuação.
Клинический случай генетического обследования пациентки в поздней постменопаузе: оценка полиморфизмов гена рецептора витамина D (VDR): FokI и A283G (BsmI)
Authors: Вихарева А. А. , Сафьяник Е. А. , Попов А. А. , Изможерова Н. В.
Published: February 2021

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Reichlich Geld steht bereit
Authors: Genath Bernd
Published: February 2021

Der Bund wird laut Haushaltsentwurf 2021 in diesem Jahr rund sechs Milliarden Euro zur Gebäudeenergieförderung bereitstellen – nach dem bisherigen Rekord von 3,5 Milliarden in 2020 erneut eine deutliche Steigerung. Das Geld soll ein Bau- und Modernisierungsvolumen um 25 Milliarden Euro auslösen. Sorgen über einen Förderstopp aufgrund ausgeschöpfter Mittel beziehungsweise eine Verlagerung von Teilsummen in die Abfederung der Pandemie-Verluste von Unternehmen seien unbegründet, heißt es aus Berlin. Mehrheitlich werden die Milliarden in die neue Bundesförderung effiziente Gebäude fließen. Einige Details.
Analisis Konsep Wilayatul Faqih dalam Ketatangeraan Iran
Authors: Guanti Wiwin , Hasiah Hasiah
Published: February 2021

Penelitian ini bertujuan menganalisa konsep Wilayatul Faqih yang diimplementasikan oleh negara Iran sebagai sistem politik dan ketatanegaraannya. Adapun metode yang digunakan adalah kualitatif dengan jenis penelitian kepustakaan. Hasil pembahasan menyimpulkan bahwa munculnya Pertama, sistem Wilayatul Faqih disebabkan masyarakat Iran yang bercita-cita akan kepimipinan Imamah dan melepaskan diri dari sistem pemerintahan sekuler pada masa Pahlevi. Kedua, sistem Wilayatul Faqih meletakkan otoritas hukum tertinggi pada wali faqih atau ulama yang berperan sebagai pengatur segala arah kebijakan di Iran. Ketiga, meskipun wilayatul faqih berbasis theologi politik syiah, namun tetap memakai sistem demokrasi yaitu pemilihan lansung oleh rakyat.
A Educação de Jovens e Adultos em Cordel: o sistema de numeração decimal
Authors: Flôr Anildo Soares , Alencar Edvonete  Souza de , Furtado Alessandra Cristina
Published: February 2021

Este artigo traz um recorte da dissertação “Literatura de Cordel para o Ensino do Sistema de Numeração Decimal” que teve como objetivo desenvolver uma sequência didática com a Literatura de Cordel para o ensino do sistema de numeração decimal em uma turma da Primeira Fase da Educação de Jovens e Adultos (EJA). Neste estudo, apresentaremos fragmentos do teste diagnóstico, do bloco dois das atividades da Unidade um e ao desenvolvimento dos alunos em relação a aprendizagem do conteúdo avaliado na atividade – do pós-teste. Esses dados nos ajudaram a compreender a questão de investigação: “Quais são as contribuições do uso da literatura de cordel para o ensino do sistema de numeração decimal na aprendizagem dos alunos em uma turma da 1ª Fase da EJA? Com o desenvolvimento da sequência didática foi possível constatar uma evolução da turma em relação a aprendizagem do sistema de numeração decimal passando de 75% de acertos no teste inicial para 90% no teste final. Evidenciando assim, o quanto é importante a utilização de novos meios que torne estes alunos protagonistas de sua aprendizagem.

Palavras-chave: Educação de jovens adultos. Educação matemática. Literatura de cordel. Sistema de numeração decimal.
Famotidine Research Progress
Authors: Al Mosawi AJ
Published: February 2021

There has been an increasing interest in famotidine research within the scientific medical community because of the emerging preliminary evidence suggesting its possible beneficial role in patients with COVID‑19. The aim of this paper to provide an overview of famotidine research progress relevant to COVID‑19.
Measurement of Total Electronic Cross-Section, Total Atomic Cross-Section, Effective Atomic Numbers, Effective Electron Densities and Kerma for Some Br Compounds
Authors: Saniye T , Adnan K
Published: February 2021

The aim of this study is to calculate the experimental and theoretical the mass attenuation coefficient some Br compounds by using transmission method. Also using these values were determined the total electronic section, total atomic section, effective atomic number, effective electron density and Kerma. We performed the calculations of these values in attenuation by using direct excitation experimental geometry. The total attenuation cross sections of some halogene Br compounds were measured in a narrow beam good geometry using a high resolution Si(Li) detector in the energy with γ photons at 59.543 keV from Am-241 annular source. Theoretical mass attenuation coefficient values were computed from the XCOM data programme, based on mixture rule method. This study provide new insight into the literature since the values of effective atomic number, electron density and Kerma for some Br compounds have not been determined before. According to the results shown in mass attenuation coefficient, Zeff and Neff of Br compounds are closely associated with chemical structure. This research were undertaken to explore how Bromine compounds is gamma ray shielding material.
Medicinal values of a horticultural plant - Coleus hadiensis (Forssk.) A. J. Paton
Authors: VİVEKANANDARAJAH SATHASİVAMPİLLAİ Saravanan , AUTHİNARAYANAN Dr. A. Rajesh , SEBASTİAN Pholtan Rajeev
Published: February 2021

Coleus hadiensis (Forssk.) A.J.Paton is a horticultural herb that goes to the Lamiaceae family. This plant species has been using to treat diarrhea, skin and digestive disorders, diabetes, and carcinoma in ethnomedicines. This minireview work purposes to analyze, summarize, and document the reported bioactivities of C. hadiensis. Suitable published works were obtained employing the Web of Science, Scopus, PubMed, Semantic Scholar, and ScienceDirect databases from 1900 to December 2020. Hitherto, in vitro level of scientific evidence is the highest level of scientific evidence available for the bioactivities of this plant species. Various parts of C. hadiensis exhibited antioxidant, antibacterial, anti-inflammatory, anticancer, and antimalarial activities in a range of assays. To date, eight bioactive (antimalarial and antioxidant) compounds have been isolated from C. hadiensis. This minireview analyzed, summarized, and documented the reported bioactivities of C. hadiensis. In addition, this minireview provides a basis for further bioactivities researches using C. hadiensis in future.
A Koszovóból kiinduló migráció jellemzése
Authors: Urbán Ferenc
Published: February 2021

The author provides an overview of the causes and morphology of irregular migration from Kosovo to Hungary.
ESTIMATION OF TRANSPORT ACCESSIBILITY IN CASE OF RATIONAL TRANSPORT HUB LOCATION
Authors: Rossolov Alexander , Naumov Vitalii , Popova Nadezhda , Vakulenko Ekaterina , Levchenko Olena
Published: February 2021

The public transit accessibility has become an important attribute of social and economic activity of contemporary society. The shift to the sustainable paradigm of the current cities’ development has made public transport the basic mean for population travels execution. The spatial character of the travels in the megapolises supposes its implementation with the transfers. This may result in the travel time increase if the transport hubs are designed or located inefficiently. In some cases, the transport hub locations do not reflect the current demand for public transport services and require the fulfilment of the infrastructure measures. The paper presents the Hub Location Problem (HLP) solving in the case of rapid transit and trolleybus lines interaction. It has been proposed the combined criterion for the HLP solving based on the two-dimensional coordinate system with the estimation of passenger walk turnover. The simulation procedure to estimate the transport hub relocation has been made in the PTV VISUM software in the case of the Industrial District of Kharkiv City (Ukraine). The results of the economic effect available from the transport hub rational location have been estimated.
Analysis of Previously Classified White Dwarf–Main-sequence Binaries Using Data from the APOGEE Survey
Authors: Corcoran Kyle A. , Lewis Hannah M. , Anguiano Borja , Majewski Steven R. , Kounkel Marina , McDonald Devin J , Stassun Keivan G. , Cunha Katia , Smith Verne , Prieto Carlos Allende , Badenes Carles , De Lee Nathan , Mazzola Christine N. , Longa-Peña Penélope , Roman-Lopes Alexandre
Published: February 2021

We present analyses of near-infrared spectroscopic data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey for 45 previously confirmed or candidate white dwarf–main-sequence (WDMS) binaries identified by the optical Sloan Digital Sky Survey (SDSS) and LAMOST surveys. Among these 45 systems, we classify three as having red giant primaries in the LAMOST sample and 14 as young stellar object contaminants in the photometrically identified SDSS sample. From among the subsample of 28 systems that we confirm to have MS primaries, we derive and place limits on orbital periods and velocity amplitudes for 14. Seven systems have significant velocity variations that warrant a post-common-envelope (PCE) binary classification, four of which are newly classified, three of which are newly confirmed, and five for which we can derive full orbital parameters. If confirmed, one of these newly discovered systems (2M14544500+4626456) will have the second-longest orbital period reported for a typical compact PCE WDMS binary (P = 15.1 days). In addition to the seven above, we also recover and characterize with APOGEE data the well-known PCE WDMS systems EG UMa and HZ 9. We also investigate the overall metallicity distribution of the WDMS sample, which is a parameter space not often explored for these systems. Of note, we find one system (2M14244053+4929580) to be extremely metal-poor ([Fe/H] = − 1.42) relative to the rest of the near-solar sample. Additionally, the PCE systems in our sample are found to be, on average, higher in metallicity than their wide-binary counterparts, though we caution that with this small number of systems, the sample may not be representative of the overall distribution of WDMS systems.
The Extreme Space Weather Event in 1941 February/March
Authors: Hayakawa Hisashi , Blake Sean P. , Bhaskar Ankush , Hattori Kentaro , Oliveira Denny M. , Ebihara Yusuke
Published: February 2021

Given the infrequency of extreme geomagnetic storms, it is significant to note the concentration of three extreme geomagnetic storms in 1941, whose intensities ranked fourth, twelfth, and fifth within the aa index between 1868–2010. Among them, the geomagnetic storm on 1941 March 1 was so intense that three of the four Dst station magnetograms went off scale. Herein, we reconstruct its time series and measure the storm intensity with an alternative Dst estimate (Dst*). The source solar eruption at 09:29–09:38 GMT on February 28 was located at RGO AR 13814 and its significant intensity is confirmed by large magnetic crochets of ∣35∣ nT measured at Abinger. This solar eruption most likely released a fast interplanetary coronal mass ejection with estimated speed 2260 km s−1. After its impact at 03:57–03:59 GMT on March 1, an extreme magnetic storm was recorded worldwide. Comparative analyses on the contemporary magnetograms show the storm peak intensity of minimum Dst* ≤ −464 nT at 16 GMT, comparable to the most and the second most extreme magnetic storms within the standard Dst index since 1957. This storm triggered significant low-latitude aurorae in the East Asian sector and their equatorward boundary has been reconstructed as 38.°5 in invariant latitude. This result agrees with British magnetograms, which indicate an auroral oval moving above Abinger at 53.°0 in magnetic latitude. The storm amplitude was even more enhanced in equatorial stations and consequently casts caveats on their usage for measurements of the storm intensity in Dst estimates.
Nearly 30,000 Late-type Main-sequence Stars with Stellar Age from LAMOST DR5
Authors: Zhang Jiajun , Zhao Jingkun , Oswalt Terry D. , Liang Xilong , Ye Xianhao , Zhao Gang
Published: February 2021

We construct a sample of nearly 30,000 main-sequence stars with 4500 K < T
eff < 5000 K and stellar ages estimated by the chromospheric activity−age relation. This sample is used to determine the age distribution in the R–Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As ∣Z∣ increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called a flare. A mild flare from R ∼ 8.0 to 9.0 kpc in stellar age distribution is found. We also find that the velocity dispersion increases with age as confirmed by previous studies. Finally we present spiral-shaped structures in Z–υ

Z
phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last ∼1.0 Gyr.
A New Cosmic-Ray-driven Instability
Authors: Shalaby Mohamad , Thomas Timon , Pfrommer Christoph
Published: February 2021

Cosmic-ray-driven (CR-driven) instabilities play a decisive role during particle acceleration at shocks and CR propagation in galaxies and galaxy clusters. These instabilities amplify magnetic fields and modulate CR transport so that the intrinsically collisionless CR population is tightly coupled to the thermal plasma and provides dynamical feedback. Here, we show that CRs with a finite pitch angle drive electromagnetic waves (along the background magnetic field) unstable on intermediate scales between the gyroradii of CR ions and electrons as long as CRs are drifting with a velocity less than half of the Alfvén speed of electrons. By solving the linear dispersion relation, we show that this new instability typically grows faster by more than an order of magnitude in comparison to the commonly discussed resonant instability at the ion gyroscale. We find the growth rate for this intermediate-scale instability and identify the growing modes as background ion-cyclotron modes in the frame that is comoving with the CRs. We confirm the theoretical growth rate with a particle-in-cell simulation and study the nonlinear saturation of this instability. We identify three important astrophysical applications of this intermediate-scale instability, which is expected to (1) modulate CR transport and strengthen CR feedback in galaxies and galaxy clusters, (2) enable electron injection into the diffusive shock acceleration process, and (3) decelerate CR escape from the sites of particle acceleration, which would generate gamma-ray halos surrounding CR sources such as supernova remnants.
In the Trenches of the Solar–Stellar Connection. II. Extreme Ultraviolet Flux–Flux Correlations across Solar Cycle 24
Authors: Ayres Thomas R.
Published: February 2021

Solar extreme-ultraviolet (EUV: 100–1100 Å) radiation rises in the 104 K upper chromosphere and hotter layers extending into the million-degree corona. Much of the EUV normally is not visible in other stars owing to interstellar H i absorption. The present study derived power-law scaling relations for EUV species based on irradiance spectra from the Extreme Ultraviolet Variability Experiment on board the Solar Dynamics Observatory, over the rise and fall of recent sunspot Cycle 24. These relations not only can test solar models, but also allow “invisible” stellar EUV emissions to be reconstructed from more accessible ultraviolet (UV: 1100–3000 Å) proxies, with implications for heating, ionization, and erosion of exoplanet atmospheres by Sun-like hosts. Hot EUV coronal tracers like Si xii 520 Å (8 MK) show strongly curved power laws relative to chromospheric H i 1025 Å Lyβ, as was seen in Paper I for 0.2–2 keV soft X-rays versus Mg ii 2800 Å. The brightest EUV feature, He ii 303 Å, exhibits a nearly 1:1 correlation with Lyβ (and H i 1215 Lyα, but slightly steeper than 1:1 relative to Mg ii). The second brightest, C iii 977 Å, has a shallower power-law slope of ∼0.5. Correlations for low first ionization potential species, such as Mg, Si, and Fe, might be affected by cycle-dependent chemical fractionation. Parameterized flux–flux relations are presented for most of the strong EUV (and selected UV) features, together with fluxes of individual lines and broad EUV wavelength bands at the highs and lows of Cycle 24.
Aurora Sightings Observed in Chinese History Caused by CIRs or Great-storm CMEs
Authors: Wang Guowei , Yao Shuo , Yu Yiqun , Wei Dong , Di Fei , Bao Xiujuan , Zhang Shihong , Liu Jianjun
Published: February 2021

Auroras observed at middle and low geographic latitudes are related to external inputs and varying geomagnetic fields. This work aims to exclude corotating interaction region (CIR) storms and identify strong coronal mass ejection (CME) storms according to historical auroral records when the geomagnetic field varies substantially. An existing catalog of the aurora records in Chinese history reported by Zeng & Jin from 193 B.C. to 1911 A.D. is used. Archaeomagnetic field models are adopted to estimate the variation of the dipole field. According to the empirical relation between the equatorward boundary of the auroral oval, Dst index, and geomagnetic field intensity, the auroras caused by CIRs can be excluded, and those caused by strong CMEs are identified. After 1500 A.D., China’s magnetic latitude decreased substantially due to the pole shift. This shift provides a better opportunity to investigate the existence of great-level storms. These great-storm CMEs occurred in both solar maximum and minimum. The space weather modeling framework is used to calculate the cusp area and the downward ion flux through the cusp for varied geomagnetic field and solar wind. For the present solar wind condition and tilt angle <15°, stronger geomagnetic field tends to generate a larger cusp area and higher ion flux through the cusp. For the weaker solar wind in the Maunder minimum, the ion flux is lower, but the cusp area is similar to that at present.
A Large Population of Luminous Active Galactic Nuclei Lacking X-Ray Detections: Evidence for Heavy Obscuration?
Authors: Carroll Christopher M. , Hickox Ryan C. , Masini Alberto , Lanz Lauranne , Assef Roberto J. , Stern Daniel , Chen Chien-Ting J. , Ananna Tonima T.
Published: February 2021

We present a large sample of infrared-luminous candidate active galactic nuclei (AGNs) that lack X-ray detections in Chandra, XMM-Newton, and NuSTAR fields. We selected all optically detected SDSS sources with redshift measurements, combined additional broadband photometry from WISE, UKIDSS, 2MASS, and GALEX, and modeled the spectral energy distributions (SEDs) of our sample sources. We parameterize nuclear obscuration in our SEDs with

and uncover thousands of powerful obscured AGNs that lack X-ray counterparts, many of which are identified as AGN candidates based on straightforward WISE photometric criteria. Using the observed luminosity correlation between rest-frame 2–10 keV (

) and rest-frame AGN

(

), we estimate the intrinsic X-ray luminosities of our sample sources and combine these data with flux limits from X-ray catalogs to determine lower limits on nuclear obscuration. Using the ratio of intrinsic-to-observed X-ray luminosity (

), we find a significant fraction of sources with column densities approaching

 cm–2, suggesting that multiwavelength observations are necessary to account for the population of heavily obscured AGNs. We simulate the underlying

distribution for the X-ray non-detected sources in our sample through survival analysis, and confirm the presence of AGN activity via X-ray stacking. Our results point to a considerable population of extremely obscured AGNs undetected by current X-ray observatories.
Timing Calibration of the NuSTAR X-Ray Telescope
Authors: Bachetti Matteo , Markwardt Craig B. , Grefenstette Brian W. , Gotthelf Eric V. , Kuiper Lucien , Barret Didier , Cook W. Rick , Davis Andrew , Fürst Felix , Forster Karl , Harrison Fiona A. , Madsen Kristin K. , Miyasaka Hiromasa , Roberts Bryce , Tomsick John A. , Walton Dominic J.
Published: February 2021

The Nuclear Spectroscopic Telescope Array (NuSTAR) mission is the first focusing X-ray telescope in the hard X-ray (3–79 keV) band. Among the phenomena that can be studied in this energy band, some require high time resolution and stability: rotation-powered and accreting millisecond pulsars, fast variability from black holes and neutron stars, X-ray bursts, and more. Moreover, a good alignment of the timestamps of X-ray photons to UTC is key for multi-instrument studies of fast astrophysical processes. In this paper, we describe the timing calibration of the NuSTAR mission. In particular, we present a method to correct the temperature-dependent frequency response of the on-board temperature-compensated crystal oscillator. Together with measurements of the spacecraft clock offsets obtained during downlinks passes, this allows a precise characterization of the behavior of the oscillator. The calibrated NuSTAR event timestamps for a typical observation are shown to be accurate to a precision of ∼65 μs.
A Possible Selection Rule for Flares Causing Sunquakes
Authors: Chen Ruizhu , Zhao Junwei
Published: February 2021

Sunquakes are helioseismic power enhancements initiated by solar flares, but not all flares generate sunquakes. It is curious why some flares cause sunquakes while others do not. Here we propose a hypothesis to explain the disproportionate occurrence of sunquakes: during a flare’s impulsive phase when the flare’s impulse acts upon the photosphere, delivered by shock waves, energetic particles from higher atmosphere, or by downward Lorentz Force, a sunquake tends to occur if the background oscillation at the flare footpoint happens to oscillate downward in the same direction with the impulse from above. To verify this hypothesis, we select 60 strong flares in Solar Cycle 24, and examine the background oscillatory velocity at the sunquake sources during the flares’ impulsive phases. Since the Doppler velocity observations at sunquake sources are usually corrupted during the flares, we reconstruct the oscillatory velocity in the flare sites using helioseismic holography method with an observation-based Green’s function. A total of 24 flares are found to be sunquake active, giving a total of 41 sunquakes. It is also found that in 3–5 mHz frequency band, 25 out of 31 sunquakes show net downward oscillatory velocities during the flares’ impulsive phases, and in the 5–7 mHz frequency band, 33 out of 38 sunquakes show net downward velocities. These results support the hypothesis that a sunquake more likely occurs when a flare impacts a photospheric area with a downward background oscillation.
Tracing Dark Energy History with Gamma-Ray Bursts
Authors: Muccino M. , Izzo L. , Luongo O. , Boshkayev K. , Amati L. , Della Valle M. , Pisani G. B. , Zaninoni E.
Published: February 2021

Observations of gamma-ray bursts up to z ∼ 9 are best suited to study the possible evolution of the universe equation of state at intermediate redshifts. We apply the Combo relation to a sample of 174 gamma-ray bursts to investigate possible evidence of evolving dark energy parameter w(z). We first build a gamma-ray burst Hubble’s diagram and then we estimate the set (Ω
m
, ΩΛ) in the framework of flat and non-flat ΛCDM paradigm. We then get bounds over the wCDM model, where w is thought to evolve with redshift, adopting two priors over the Hubble constant in tension at 4.4σ, i.e., H
0 = (67.4 ± 0.5) km s−1 Mpc−1 and H
0 = (74.03 ± 1.42) km s−1 Mpc−1. We show our new sample provides tighter constraints on Ω
m
since at z ≤ 1.2 we see that w(z) agrees within 1σ with the standard value w = −1. The situation is the opposite at larger z, where gamma-ray bursts better fix w(z) that seems to deviate from w = −1 at 2σ and 4σ level, depending on the redshift bins. In particular, we investigate the w(z) evolution through a piecewise formulation over seven redshift intervals. From our fitting procedure we show that at z ≥ 1.2 the case w < −1 cannot be fully excluded, indicating that dark energy’s influence is not negligible at larger z. We confirm the Combo relation as a powerful tool to investigate cosmological evolution of dark energy. Future space missions will significantly enrich the gamma-ray burst database even at smaller redshifts, improving de facto the results discussed in this paper.
Identifying Candidate Optical Variables Using Gaia Data Release 2
Authors: Andrew Shion , Swihart Samuel J. , Strader Jay
Published: February 2021

Gaia is undertaking a deep synoptic survey of the Galaxy, but photometry from individual epochs has, as of yet, only been released for a minimal number of sources. We show that it is possible to identify variable stars in Gaia Data Release 2 by selecting stars with unexpectedly large photometric uncertainties given their brightness and number of observations. By comparing our results to existing catalogs of variables, we show that information on the amplitude of variability is also implicitly present in the Gaia photometric uncertainties. We present a catalog of about 9.3 million candidate variable stars, and discuss its limitations and prospects for future tests and extensions.
Elliptical Accretion Disk as a Model for Tidal Disruption Events
Authors: Liu F. K. , Cao C. Y. , Abramowicz M. A. , Wielgus M. , Cao R. , Zhou Z. Q.
Published: February 2021

Elliptical accretion disk models for tidal disruption events (TDEs) have been recently proposed and independently developed by two groups. Although these two models are characterized by a similar geometry, their physical properties differ considerably. In this paper, we further investigate the properties of the elliptical accretion disk of the nearly uniform distribution of eccentricity within the disk plane. Our results show that the elliptical accretion disks have distinctive hydrodynamic structures and spectral energy distributions, associated with TDEs. The soft X-ray photons generated at pericenter and nearby are trapped in the disk and advected around the ellipse because of large electron scattering opacity. They are absorbed and reprocessed into emission lines and low-frequency continuum via recombination and bremsstrahlung emission. Because of the rapid increase of bound–free and free–free opacities with radius, the low-frequency continuum photons become trapped in the disk at large radius and are advected through apocenter and back to the photon-trapping radius. Elliptical accretion disks predict sub-Eddington luminosities and emit mainly at the photon-trapping radius of thousands of Schwarzschild radii with a blackbody spectrum of nearly single temperature of typically about 3 × 104 K. Because of the self-regulation, the photon-trapping radius expands and contracts following the rise and fall of accretion rate. The radiation temperature is nearly independent of BH mass and accretion rate and varies weakly with the stellar mass and the viscosity parameter. Our results are well consistent with the observations of optical/UV TDEs.
Low-energy Measurement of the 96Zr(α,n)99Mo Reaction Cross Section and Its Impact on Weak r-process Nucleosynthesis
Authors: Kiss G. G. , Szegedi T. N. , Mohr P. , Jacobi M. , Gyürky Gy. , Huszánk R. , Arcones A.
Published: February 2021

Lighter heavy elements beyond iron and up to around silver can form in neutrino-driven ejecta in core-collapse supernovae and neutron star mergers. Slightly neutron-rich conditions favor a weak r-process that follows a path close to stability. Therefore, the beta decays are slow compared to the expansion timescales, and (α,n) reactions become critical to move matter toward heavier nuclei. The rates of these reactions are calculated with the statistical model and their main uncertainty, at energies relevant for the weak r-process, is the α+nucleus optical potential. There are several sets of parameters to calculate the α+nucleus optical potential leading to large deviations for the reaction rates, exceeding even one order of magnitude. Recently the 96Zr(α,n)99Mo reaction has been identified as a key reaction that impacts the production of elements from Ru to Cd. Here, we present the first cross section measurement of this reaction at energies (6.22 MeV ≤ Ec.m. ≤ 12.47 MeV) relevant for the weak r-process. The new data provide a stringent test of various model predictions which is necessary to improve the precision of the weak r-process network calculations. The strongly reduced reaction rate uncertainty leads to very well-constrained nucleosynthesis yields for Z = 44–48 isotopes under different neutrino-driven wind conditions.
Small-scale Bright Blobs Ejected from a Sunspot Light Bridge
Authors: Li Fuyu , Chen Yajie , Hou Yijun , Tian Hui , Bai Xianyong , Song Yongliang
Published: February 2021

Light bridges (LBs) are bright lanes that divide an umbra into multiple parts in some sunspots. Persistent oscillatory bright fronts at a temperature of ∼105 K are commonly observed above LBs in the 1400/1330 Å passbands of the Interface Region Imaging Spectrograph (IRIS). Based on IRIS observations, we report small-scale bright blobs ejected from the oscillating bright front above a light bridge. Some of these blobs reveal a clear acceleration, whereas the others do not. The average speed of these blobs projected onto the plane of sky is 71.7 ± 14.7 km s−1, with an initial acceleration of 1.9 ± 1.3 km s−2. These blobs normally reach a projected distance of 3–7 Mm from their origin sites. They have an average projected area of 0.57 ± 0.37 Mm2. The blobs were also detected in multiple extreme-ultraviolet passbands of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, but not in the Hα images taken by the New Vacuum Solar Telescope. The typical temperature and electron density of these blobs are around

K and

cm−3, respectively. The estimated kinetic and thermal energies are on the order of

erg and

erg, respectively. These small-scale blobs appear to show three different types of formation processes. They are possibly triggered by induced reconnection or release of enhanced magnetic tension due to interaction of adjacent shocks, local magnetic reconnection between emerging magnetic bipoles on the light bridge and surrounding unipolar umbral fields, and plasma acceleration or instability caused by upward shocks, respectively.
Years-delayed X-Ray Afterglows of TDEs Originated from Wind–Torus Interactions
Authors: Mou Guobin , Dou Liming , Jiang Ning , Wang Tinggui , Guo Fulai , Wang Wei , Wang Hu , Shu Xinwen , He Zhicheng , Zhang Ruiyu , Sun Luming
Published: February 2021

Tidal disruption events (TDEs) occurring in active galactic nuclei (AGNs) are a special class of sources with outstanding scientific significance. TDEs can generate ultrafast winds, which should almost inevitably collide with the preexisting AGN dusty tori. We perform analytical calculations and simulations on the wind–torus interactions and find such a process can generate considerable X-ray afterglow radiation several years or decades later after the TDE outburst. This provides a new origin for the years delayed X-rays in TDEs. The X-ray luminosity can reach 1041−42 erg s−1, and the light curve characteristics depend on the parameters of winds and tori. We apply the model to two TDE candidates, and provide lower limits on the masses of the disrupted stars, as well as rigorous constraints on the gas densities of tori. Our results suggest that the observations of the time delay, spectral shape, luminosity, and the light curve of the X-ray afterglow can be used to constrain the physical parameters of both TDE winds and tori, including the wind velocity, wind density, cloud density, and cloud size.
Peeking Between the Pulses: The Far-UV Spectrum of the Previously Unseen White Dwarf in AR Scorpii
Authors: Garnavich Peter , Littlefield Colin , Lyutikov Maxim , Barkov Maxim
Published: February 2021

The compact object in the interacting binary AR Sco has widely been presumed to be a rapidly rotating, magnetized white dwarf (WD), but it has never been detected directly. Isolating its spectrum has proven difficult because the spin-down of the WD generates pulsed synchrotron radiation that far outshines the WD’s photosphere. As a result, a previous study of AR Sco was unable to detect the WD in the averaged far-ultraviolet spectrum from a Hubble Space Telescope (HST) observation. In an effort to unveil the WD’s spectrum, we reanalyze these HST observations by calculating the average spectrum in the troughs between synchrotron pulses. We identify weak spectral features from the previously unseen WD and estimate its surface temperature to be 11,500 ± 500 K. Additionally, during the synchrotron pulses, we detect broad Lyα absorption consistent with hot WD spectral models. We infer the presence of a pair of hotspots, with temperatures between 23,000 and 28,000 K, near the magnetic poles of the WD. As the WD is not expected to be accreting from its companion, we describe two possible mechanisms for heating the magnetic poles. The Lyα absorption of the hotspots appears relatively undistorted by Zeeman splitting, constraining the WD’s field strength to be ≲100 MG, but the data are insufficient to search for the subtle Zeeman splits expected at lower field strengths.
Mass-gap Mergers in Active Galactic Nuclei
Authors: Tagawa Hiromichi , Kocsis Bence , Haiman Zoltán , Bartos Imre , Omukai Kazuyuki , Samsing Johan
Published: February 2021

The recently discovered gravitational wave sources GW190521 and GW190814 have shown evidence of BH mergers with masses and spins outside of the range expected from isolated stellar evolution. These merging objects could have undergone previous mergers. Such hierarchical mergers are predicted to be frequent in active galactic nuclei (AGNs) disks, where binaries form and evolve efficiently by dynamical interactions and gaseous dissipation. Here we compare the properties of these observed events to the theoretical models of mergers in AGN disks, which are obtained by performing one-dimensional N-body simulations combined with semi-analytical prescriptions. The high BH masses in GW190521 are consistent with mergers of high-generation (high-g) BHs where the initial progenitor stars had high metallicity, 2g BHs if the original progenitors were metal-poor, or 1g BHs that had gained mass via super-Eddington accretion. Other measured properties related to spin parameters in GW190521 are also consistent with mergers in AGN disks. Furthermore, mergers in the lower mass gap or those with low mass ratio as found in GW190814 and GW190412 are also reproduced by mergers of 2g–1g or 1g–1g objects with significant accretion in AGN disks. Finally, due to gas accretion, the massive neutron star merger reported in GW190425 can be produced in an AGN disk.
White Dwarf Photospheric Abundances in Cataclysmic Variables. I. SS Aurigae and TU Mensae*
Authors: Godon Patrick , Sion Edward M.
Published: February 2021

Chemical abundance studies of cataclysmic variables have revealed high nitrogen to carbon ratios in a number of cataclysmic variable white dwarfs (based on ultraviolet emission and absorption lines), as well as possible carbon deficiency in many secondaries (based on the absence of infrared CO absorption lines). These indicate that the accreted material on the white dwarf surface and the donor itself might be contaminated with CNO processed material. To further understand the origin of this abundance anomaly, there is a need for further chemical abundance study. In the present work, we carry out a far-ultraviolet spectral analysis of the extreme SU UMa dwarf nova TU Men and the U Gem dwarf nova SS Aur using archival spectra. We derive the mass and temperature of the WD using the recently available DR2 Gaia parallaxes. The analysis of HST STIS spectra yields a WD mass

with a temperature of 27,750 ± 1000 K for TU Men and a WD mass M
wd ∼ 0.80 ± 0.15 M
⊙ with a temperature of ∼30,000 ± 1000 K for SS Aur. However, the analysis of a FUSE spectrum for SS Aur gives a higher temperature of ∼33,375 ± 1875 K, yielding a higher WD mass of ∼1 ± 0.25 M
⊙, which could be due to the effect of a second hot emitting component present in the short wavelengths of FUSE. Most importantly, based on the white dwarf far-ultraviolet absorption lines, we find that both systems have subsolar carbon and silicon abundances. For TU Men, we also find suprasolar nitrogen abundance, evidence of CNO processing.
Ensuring Robustness in Training-set-based Global 21 cm Cosmology Analysis
Authors: Bassett Neil , Rapetti David , Tauscher Keith , Burns Jack O. , Hibbard Joshua J.
Published: February 2021

We present a methodology for ensuring the robustness of our analysis pipeline in separating the global 21 cm hydrogen cosmology signal from large systematics based on singular value decomposition (SVD) of training sets. We show how traditional goodness-of-fit metrics such as the χ
2 statistic that assess the fit to the full data may not be able to detect a suboptimal extraction of the 21 cm signal when it is fit alongside one or more additional components owing to significant covariance between them. However, we find that comparing the number of SVD eigenmodes for each component chosen by the pipeline for a given fit to the distribution of eigenmodes chosen for synthetic data realizations created from training set curves can detect when one or more of the training sets is insufficient to optimally extract the signal. Furthermore, this test can distinguish which training set (e.g., foreground, 21 cm signal) needs to be modified in order to better describe the data and improve the quality of the 21 cm signal extraction. We also extend this goodness-of-fit testing to cases where a prior distribution derived from the training sets is applied and find that, in this case, the χ
2 statistic and the recently introduced ψ
2 statistic are able to detect inadequacies in the training sets due to the increased restrictions imposed by the prior. Crucially, the tests described in this paper can be performed when analyzing any type of observations with our pipeline.
The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs
Authors: Kirkpatrick J. Davy , Gelino Christopher R. , Faherty Jacqueline K. , Meisner Aaron M. , Caselden Dan , Schneider Adam C. , Marocco Federico , Cayago Alfred J. , Smart R. L. , Eisenhardt Peter R. , Kuchner Marc J. , Wright Edward L. , Cushing Michael C. , Allers Katelyn N. , Bardalez Gagliuffi Daniella C. , Burgasser Adam J. , Gagné Jonathan , Logsdon Sarah E. , Martin Emily C. , Ingalls James G. , Lowrance Patrick J. , Abrahams Ellianna S. , Aganze Christian , Gerasimov Roman , Gonzales Eileen C. , Hsu Chih-Chun , Kamraj Nikita , Kiman Rocio , Rees Jon , Theissen Christopher , Ammar Kareem , Andersen Nikolaj Stevnbak , Beaulieu Paul , Colin Guillaume , Elachi Charles A. , Goodman Samuel J. , Gramaize Léopold , Hamlet Leslie K. , Hong Justin , Jonkeren Alexander , Khalil Mohammed , Martin David W. , Pendrill William , Pumphrey Benjamin , Rothermich Austin , Sainio Arttu , Stenner Andres , Tanner Christopher , Thévenot Melina , Voloshin Nikita V. , Walla Jim , Wędracki Zbigniew ,   The Backyard Worlds: Planet 9 Collaboration
Published: February 2021

We present final Spitzer trigonometric parallaxes for 361 L, T, and Y dwarfs. We combine these with prior studies to build a list of 525 known L, T, and Y dwarfs within 20 pc of the Sun, 38 of which are presented here for the first time. Using published photometry and spectroscopy as well as our own follow-up, we present an array of color–magnitude and color–color diagrams to further characterize census members, and we provide polynomial fits to the bulk trends. Using these characterizations, we assign each object a T
eff value and judge sample completeness over bins of T
eff and spectral type. Except for types ≥T8 and T
eff < 600 K, our census is statistically complete to the 20 pc limit. We compare our measured space densities to simulated density distributions and find that the best fit is a power law (

) with α = 0.6 ± 0.1. We find that the evolutionary models of Saumon & Marley correctly predict the observed magnitude of the space density spike seen at 1200 K < T
eff < 1350 K, believed to be caused by an increase in the cooling timescale across the L/T transition. Defining the low-mass terminus using this sample requires a more statistically robust and complete sample of dwarfs ≥Y0.5 and with T
eff < 400 K. We conclude that such frigid objects must exist in substantial numbers, despite the fact that few have so far been identified, and we discuss possible reasons why they have largely eluded detection.
Numerical Research on the Effect of the Initial Parameters of a CME Flux-rope Model on Simulation Results
Authors: Shen Fang , Liu Yousheng , Yang Yi
Published: February 2021

Coronal mass ejections (CMEs) are the major drivers of space weather, and an accurate modeling of their initialization and propagation up to 1 au and beyond is an important issue for space weather research and forecasts. In this research, we use the newly developed three-dimensional (3D) flux-rope CME initialization model and 3D IN (interplanetary)-TVD MHD model to study the effect of different CME initial parameters on simulation outputs. The initial CME flux model is established based on the graduated cylindrical shell model. In order to test the influence of the CME initial parameters on the simulation results, we try to run several simulations with different CME initial parameters, then investigate the outputs in interplanetary space. Here, we focus only on cases in which observers are located in the same initial direction of propagation of the CME. Our analysis shows that the parameters specifying the CME initialization in the model, including the initial density, the thickness of CME flux tube, initial mass, and initial magnetic field, have different effects on the simulation results for observers near the Earth and Mars, and on the process of propagation of the CME in interplanetary space. This confirms the important role played by details of the initial implementation of geometric and physical parameters on space weather research and forecasts.
TESS Observations of Cepheid Stars: First Light Results
Authors: Plachy E. , Pál A. , Bódi A. , Szabó P. , Molnár L. , Szabados L. , Benkő J. M. , Anderson R. I. , Bellinger E. P. , Bhardwaj A. , Ebadi M. , Gazeas K. , Hambsch F.-J. , Hasanzadeh A. , Jurkovic M. I. , Kalaee M. J. , Kervella P. , Kolenberg K. , Mikołajczyk P. , Nardetto N. , Nemec J. M. , Netzel H. , Ngeow C.-C. , Ozuyar D. , Pascual-Granado J. , Pilecki B. , Ripepi V. , Skarka M. , Smolec R. , Sódor Á. , Szabó R. , Christensen-Dalsgaard J. , Jenkins J. M. , Kjeldsen H. , Ricker G. R. , Vanderspek R.
Published: February 2021

We present the first analysis of Cepheid stars observed by the TESS space mission in Sectors 1–5. Our sample consists of 25 pulsators: ten fundamental mode, three overtone and two double-mode classical Cepheids, plus three type II and seven anomalous Cepheids. The targets were chosen from fields with different stellar densities, both from the Galactic field and from the Magellanic System. Three targets have 2 minutes cadence light curves available by the TESS Science Processing Operations Center: for the rest, we prepared custom light curves from the full-frame images with our own differential photometric FITSH pipeline. Our main goal was to explore the potential and the limitations of TESS concerning the various subtypes of Cepheids. We detected many low-amplitude features: weak modulation, period jitter, and timing variations due to light-time effect. We also report signs of nonradial modes and the first discovery of such a mode in an anomalous Cepheid, the overtone star XZ Cet, which we then confirmed with ground-based multicolor photometric measurements. We prepared a custom photometric solution to minimize saturation effects in the bright fundamental-mode classical Cepheid, β Dor with the lightkurve software, and we revealed strong evidence of cycle-to-cycle variations in the star. In several cases, however, fluctuations in the pulsation could not be distinguished from instrumental effects, such as contamination from nearby sources, which also varies between sectors. Finally, we discuss how precise light-curve shapes will be crucial not only for classification purposes but also to determine physical properties of these stars.
O uso do SIGAA: um estudo de caso sobre o processo de ensino-aprendizagem no componente curricular máquinas elétricas no curso técnico em eletroeletrônica
Authors: Lopes-Silva Paulo , Gomes Ednaldo
Published: February 2021

O presente estudo investiga o uso das potencialidades pedagógicas do SIGAA como parte integradora das ações educativas em cursos técnicos na modalidade presencial. Esta pesquisa foi desenvolvida usando a metodologia da pesquisa-ação e considerou a percepção dos sujeitos participantes e suas reflexões sobre o uso dos recursos do ambiente. Para a coleta de dados foram usados um questionário e recursos de Estatística do SIGAA, os registros e constatações dos pesquisadores e um questionário semiestruturado aplicado aos participantes. Os três instrumentos de coleta de dados fornecem dados quantitativos e qualitativos usados para afirmar e/ou infirmar as percepções acerca do ambiente. Os resultados mostram que os participantes percebem a contribuição do Sistema no processo ensino-aprendizagem e o inferem como subutilizado. Com algumas ressalvas sobre o acesso via dispositivos móveis e instabilidades pontuais, o SIGAA facilita e amplia o acesso aos materiais e conteúdos didáticos trabalhados, contribui com a interação entre professor e aluno e auxilia nas ações avaliativas, destacando-se como provável aliado no cotidiano do ensino presencial.