bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Warm Gas in the MW: A Kinematical Model
Authors: Qu Zhijie , Bregman Joel N. , Hodges-Kluck Edmund , Li Jiang-Tao , Lindley Ryan 
Published: May 2020

Abstract
We develop a kinematical model for the Milky Way Si iv-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line-shape sample extracted from the Hubble Space Telescope/Cosmic Origins Spectrograph archival data, which contains 186 active galactic nucleus sight lines. We find that the Si iv ion density distribution is dominated by an extended disk along the z-direction (above or below the midplane), i.e.,

, where z
0 is the scale height of

kpc (northern hemisphere) and

kpc (southern hemisphere). The density distribution of the disk in the radial direction shows a sharp edge at 15–20 kpc given by,

, where r
0 ≈ 12.5 ± 0.6 kpc. The difference of density distributions over r
XY and z directions indicates that the warm gas traced by Si iv is mainly associated with disk processes (e.g., feedback or cycling gas) rather than accretion. We estimate the mass of the warm gas (within 50 kpc) is

(assuming Z ≈ 0.5 Z
⊙), and a 3σ upper limit of

(excluding the Magellanic system). Kinematically, the warm gas disk is nearly co-rotating with the stellar disk at

, which lags the midplane rotation by about

(within 5 kpc). Meanwhile, we note that the warm gas in the northern hemisphere has significant accretion with v
acc of 69 ± 7

at 10 kpc (an accretion rate of

), while in the southern hemisphere, there is no measurable accretion, with an upper limit of 0.4 M
⊙ yr−1.
On the Contribution of Quiet-Sun Magnetism to Solar Irradiance Variations: Constraints on Quiet-Sun Variability and Grand-minimum Scenarios
Authors: Rempel M. 
Published: May 2020

Abstract
While the quiet-Sun magnetic field shows only little variation with the solar cycle, long-term variations cannot be completely ruled out from first principles. We investigate the potential effect of quiet-Sun magnetism on spectral solar irradiance through a series of small-scale dynamo simulations with zero vertical flux imbalance (

) and varying levels of small-scale magnetic field strength, and one weak network case with an additional flux imbalance corresponding to a flux density of

G. From these setups, we compute the dependence of the outgoing radiative energy flux on the mean vertical magnetic field strength in the photosphere at a continuum optical depth τ = 1 (

). We find that a quiet-Sun setup with a mean vertical field strength of

G is about 0.6% brighter than a non-magnetic reference case. We find a linear dependence of the outgoing radiative energy flux on the mean field strength

with a relative slope of 1.4 × 10−4 G−1. With this sensitivity, only a moderate change of the quiet-Sun field strength by 10% would lead to a total solar irradiance variation comparable to the observed solar cycle variation. While this does provide strong indirect constraints on possible quiet-Sun variations during a regular solar cycle, it also emphasizes that potential variability over longer timescales could make a significant contribution to longer-term solar irradiance variations.
An Extreme Ultraviolet Wave Associated with a Solar Filament Activation
Authors: Zheng Ruisheng , Chen Yao , Wang Bing , Song Hongqiang 
Published: May 2020

Abstract
Extreme ultraviolet (EUV) waves are impressive coronal propagating disturbances. They are closely associated with various eruptions and can be used for global coronal seismology and the acceleration of solar energetic particles. Hence, the study of EUV waves plays an important role in solar eruptions and space weather. Here we present an EUV wave associated with a filament activation that did not evolve into any eruption. Due to the continuous magnetic flux emergence and cancellation around its one end, the filament rose with untwisting motion, and the filament mass flowed toward another end along the rising fields. Intriguingly, following the filament activation, an EUV wave formed with a fast constant speed (∼500 km s−1) ahead of the mass flow, and the overlying coronal loops expanded in both lateral and radial directions. Excluding the possibility of a remote flare and an absent coronal mass ejection, we suggest that the EUV wave was only closely associated with the filament activation. Furthermore, their intimate spatial and temporal relationship indicates that the EUV wave was likely directly triggered by the lateral expansion of overlying loops. We propose that the EUV wave can be interpreted as a linear fast-mode wave, and the most vital key for the successful generation of the EUV wave is the impulsive early phase lateral expansion of overlying loops that was driven by the activated filament mass flow without any eruption.
CHAOS V: Recombination Line Carbon Abundances in M 101
Authors: Skillman Evan D. , Berg Danielle A. , Pogge Richard W. , Moustakas John , Rogers Noah S. J. , Croxall Kevin V. 
Published: May 2020

Abstract
The CHemical Abundances Of Spirals (CHAOS) project is building a large database of Large Binocular Telescope (LBT) H ii region spectra in nearby spiral galaxies to use direct abundances to better determine the dispersion in metallicity as a function of galactic radius. Here, we present CHAOS LBT observations of C ii
λ4267 emission detected in 10 H ii regions in M 101, and using a new photoionization model-based ionization correction factor, we convert these measurements into total carbon abundances. A comparison with M 101 C ii recombination line observations from the literature shows excellent agreement, and we measure a relatively steep gradient in log(C/H) of −0.37 ± 0.06 dex

. The C/N observations are consistent with a constant value of log(C/N) = 0.84 with a dispersion of only 0.09 dex, which, given the different nucleosynthetic sources of C and N, is challenging to understand. We also note that when plotting N/O versus O/H, all of the H ii regions with detections of C ii
λ4267 present N/O abundances at the minimum of the scatter in N/O at a given value of O/H. If the high surface brightness necessary for the detection of the faint recombination lines is interpreted as an indicator of H ii region youth, then this may point to a lack of nitrogen pollution in the youngest H ii regions. In the future, we anticipate that the CHAOS project will significantly increase the total number of C ii
λ4267 measurements in extragalactic H ii regions.
A Unique Resource for Solar Flare Diagnostic Studies: The SMM Bent Crystal Spectrometer
Authors: Sylwester J. , Sylwester B. , Phillips K. J. H. , Kępa A. , Rapley C. G. 
Published: May 2020

Abstract
The Bent Crystal Spectrometer (BCS) on the NASA Solar Maximum Mission spacecraft observed the X-ray spectra of numerous solar flares during the periods 1980 February–November and 1984–1989. The instrument, the first of its kind to use curved crystal technology, observed the resonance lines of He-like Ca (Ca xix) and Fe (Fe xxv), and neighboring satellite lines, allowing the study of the rapid evolution of flare plasma temperature, turbulence, mass motions etc. To date there has not been a solar X-ray spectrometer with comparable spectral and time resolution, while subsequent solar cycles have delivered far fewer and less intense flares. The BCS data archive thus offers an unparalleled resource for flare studies. A recent reassessment of the BCS calibration and its operations is extended here by using data during a spacecraft scan in the course of a flare on 1980 November 6 that highlights small deformations in the crystal curvature of the important channel 1 (viewing lines of Ca xix and satellites). The results explain long-standing anomalies in spectral line ratios which have been widely discussed in the past. We also provide an in-flight estimation of the BCS collimator field of view which improves the absolute intensity calibration of the BCS. The BCS channel 1 background is shown to be entirely due to solar continuum radiation, confirming earlier analyses implying a time-variable flare abundance of Ca. We suggest that BCS high-resolution Ca xix and Fe xxv line spectra be used as templates for the analysis of X-ray spectra of nonsolar sources.
Fast Acceleration of Transrelativistic Electrons in Astrophysical Turbulence
Authors: Trotta Domenico , Franci Luca , Burgess David , Hellinger Petr 
Published: May 2020

Abstract
Highly energetic, relativistic electrons are commonly present in many astrophysical systems, from solar flares to the intracluster medium, as indicated by observed electromagnetic radiation. However, open questions remain about the mechanisms responsible for their acceleration, and possible reacceleration. Ubiquitous plasma turbulence is one of the possible universal mechanisms. We study the energization of transrelativistic electrons in turbulence using a hybrid particle-in-cell method, which provides a realistic model of Alfvénic turbulence from MHD to subion scales, and test particle simulations for electrons. We find that, depending on the electron initial energy and turbulence strength, electrons may undergo a fast and efficient phase of energization due to the magnetic curvature drift during the time they are trapped in dynamic magnetic structures. In addition, electrons are accelerated stochastically, which is a slower process that yields lower maximum energies. The combined effect of these two processes determines the overall electron acceleration. With appropriate turbulence parameters, we find that superthermal electrons can be accelerated up to relativistic energies. For example, with heliospheric parameters and a relatively high turbulence level, rapid energization to megaelectronvolt energies is possible.
Fingerprints of Binary Black Hole Formation Channels Encoded in the Mass and Spin of Merger Remnants
Authors: Sedda Manuel Arca , Mapelli Michela , Spera Mario , Benacquista Matthew , Giacobbo Nicola 
Published: May 2020

Abstract
Binary black holes (BBHs) are thought to form in different environments, including the galactic field and (globular, nuclear, young, and open) star clusters. Here, we propose a method to estimate the fingerprints of the main BBH formation channels associated with these different environments. We show that the metallicity distribution of galaxies in the local universe along with the relative amount of mergers forming in the field or in star clusters determine the main properties of the BBH population. Our fiducial model predicts that the heaviest merger to date, GW170729, originated from a progenitor that underwent 2–3 merger events in a dense star cluster, possibly a galactic nucleus. The model predicts that at least one merger remnant out of a hundred BBH mergers in the local universe has mass

, and one in a thousand can reach a mass as large as

. Such massive black holes would bridge the gap between stellar-mass and intermediate-mass black holes. The relative number of low- and high-mass BBHs can help us unravel the fingerprints of different formation channels. Based on the assumptions of our model, we expect that isolated binaries are the main channel of BBH merger formation if

of the whole BBH population has remnants with masses

, whereas

% of remnants having masses

points to a significant subpopulation of dynamically formed BBH binaries.
Radiolysis of Ices by Cosmic-Rays: CH4 and H2O Ices Mixtures Irradiated by 40 MeV 58Ni11+ Ions
Authors: Mejía C. , de Barros A. L. F. , Rothard H. , Boduch P. , da Silveira E. F. 
Published: May 2020

Abstract
Physico-chemical modifications induced by swift heavy ions on methane-water (CH4:H2O) ices at 15 K are analyzed. Ice films, at concentrations of (1:3) and (1:15), were irradiated by 40 MeV 58Ni11+ ions. Fourier transform transmission spectroscopy in the mid-range was used to monitor the evolution ices at 15 K as a function of projectile fluence. New IR bands appearing for the irradiated (CH4:H2O) (1:3) ice are attributed to the synthesized molecules: C3H8, HCO, H2CO, CO, CO2, H2O2, HCOOH, CH3OH, C2H5OH, and CH3CHO. For the irradiated (CH4:H2O) (1:15) ice, the abundances of the compounds containing two carbons atoms are lower than those for the (1:3) ice; in contrast, CH3OH and H2O2 abundances increase when compared to the values obtained with the (1:3) ice. After irradiation, the ices were warmed up until 110 K, when the IR spectra reveal features of complex organic molecules. The destruction and formation cross sections and the sputtering yields of the ice mixtures are estimated. These findings provide possible pathways for the occurrence of compounds rich in C, O, and H, which are indeed observed in the cold regions of the universe such as ices in grain mantles of the interstellar medium and circumstellar envelopes.
Active-region Tilt Angles from White-light Images and Magnetograms: The Role of Magnetic Tongues
Authors: Poisson Mariano , Démoulin Pascal , Mandrini Cristina H. , Fuentes Marcelo C. López 
Published: May 2020

Abstract
The presence of elongations in active-region (AR) polarities, called magnetic tongues, is mostly visible during their emergence phase. AR tilts have been measured thoroughly using long-term white-light (WL) databases, sometimes combined with magnetic-field information. Since the influence of magnetic tongues on WL tilt measurements has not been taken into account before, we aim to investigate their role in tilt-angle values and to compare them with those derived from LOS magnetograms. We apply four methods to compute the tilt angle of generally bipolar ARs: one applies the k-means algorithm to WL data, a second one includes the magnetic-field sign of the polarities to WL data, and a third one uses the magnetic flux-weighted center of each polarity. The tilt values computed in any of these ways are affected by the presence of magnetic tongues. Therefore, we apply the newly developed Core Field Fit Estimator (CoFFE) method to separate the magnetic flux in the tongues from that in the AR core. We compare the four computed tilt-angle values, as well as these with the ones reported in long-term WL databases. For ARs with low-magnetic-flux tongues, the different methods report consistent tilt-angle values. But for ARs with high-flux tongues, there are noticeable discrepancies between all methods, indicating that magnetic tongues differently affect WL and magnetic data. However, in general, CoFFE achieves a better estimation of the main bipole tilt because it removes both the effect of tongues as well as the emergence of secondary bipoles when it occurs in between the main bipole magnetic polarities.
Revisiting the Relationship between the Long GRB Rate and Cosmic Star Formation History Based on a Large Swift Sample
Authors: Hao Jing-Meng , Cao Liang , Lu You-Jun , Chu Qing-Bo , Fan Jun-Hui , Yuan Ye-Fei , Yuan Yu-Hai 
Published: May 2020

Abstract
The exact relationship between the long gamma-ray burst (LGRB) rate and the cosmic star formation rate (CSFR) is essential for using LGRBs as cosmological probes. In this work, we collect a large sample composed of 371 Swift LGRBs with known redshifts and prompt emission properties. We first compare the rest-frame prompt properties of these bursts in different redshift bins, finding negligible redshift evolution of the luminosity of LGRBs with

between z ∼ 1 and z ∼ 4. Then, by utilizing the CSFR obtained from the large-scale cosmological hydrodynamical simulation, the Illustris simulation, we calculate the cumulative redshift distribution of LGRBs under different metallicity thresholds. After comparing with our sample, we find that the predictions with a moderate threshold between

are consistent with the sample between redshift 0 < z < 3, while at higher redshifts, between 3 < z < 5, all metallicity thresholds fit the data well. When changing to an empirical model based on observations, the predictions show similar results as well. After comparing with the metallicity distribution of the observed LGRB host galaxies between 0 < z < 1, we confirm that the production of LGRBs in galaxies with super-solar metallicity is suppressed. Nevertheless, considering that a significant fraction of stars are born in sub-solar metallicity environments at z ≳ 3, we suggest that, as a first approximation, LGRBs can be used as direct tracers of the CSFR in this redshift range.
Les pleins pouvoirs ? Éléments de sociologie des arbitres de football en France
Authors: Nuytens Williams , Penin Nicolas , Duvant Grégoire 
Published: May 2020

Cet article est consacré aux arbitres de football en France, c’est-à-dire ceux qui régulent plus de 600000 rencontres sportives chaque année. Il s’agit ici de relever les principales dimensions d’une activité complexe, de caractériser l’hétérogénéité d’un groupe et de questionner le mode de gouvernement auquel il contribue. Les éléments sociologiques proposés proviennent d’une revue de littérature, d’une passation de questionnaires réalisée auprès de 5000 arbitres français, de 29 entretiens touchant presque tous les niveaux de l’arbitrage. L’article montre l’existence de profils d’arbitres variés et les inégales distributions et consistances de pouvoirs qui en découlent. Ainsi l’usage du pouvoir et sa dimension discrétionnaire sont-ils dépendants de la position occupée par l’arbitre dans sa hiérarchie et dans la carrière.
Analyse des conceptions d’élèves sur le vivant, dans une situation de conception expérimentale avec un environnement informatique
Authors: Bonnat Catherine , Marzin-Janvier Patricia , Girault Isabelle 
Published: May 2020

Nous présentons des résultats issus d’un travail mené sur l’activité de conception expérimentale en biologie par des élèves de terminale scientifique (17-18 ans), avec un environnement informatique (LabBook) qui structure cette activité. Le premier objectif de recherche est d’identifier, à partir d’un questionnaire, les conceptions initiales des élèves sur le concept du vivant, à partir de l’étude d’une de ses manifestations, le métabolisme de la fermentation alcoolique, en lien avec les conceptions d’élèves identifiées dans la littérature. Le deuxième objectif consiste à étudier l’influence de l’activité de rédaction du protocole expérimental lors de la conception expérimentale, sur les conceptions initiales des élèves. Pour cela, une analyse des protocoles produits nous informe des connaissances sur le vivant mobilisées par les élèves, contextualisées à la conception expérimentale sur la fermentation alcoolique. Ensuite, les réponses des élèves au même questionnaire après l’activité nous permettent d’analyser le changement des connaissances initiales des élèves, en lien avec les connaissances mobilisées dans un contexte expérimental.
MKP-1 Modulates Mitochondrial Transcription Factors, Oxidative Phosphorylation, and Glycolysis
Authors: Bauerfeld Christian , Talwar Harvinder , Zhang Kezhong , Liu Yusen , Samavati Lobelia 
Published: May 2020

Abstract
Sepsis is the leading cause of death in the world. Recent reports suggest that in response to sepsis, metabolism of macrophages switches from oxidative phosphorylation to aerobic glycolysis. MAPK phosphatase (MKP)–1 (also known as DUSP1) localized in the nucleus and preferentially dephosphorylates p38 and JNK. MKP-1 controls the expression of numerous inflammatory genes and transcription factors, thereby regulating innate and adaptive immunity. MKP-1–deficient animals exhibit aberrant metabolic responses following bacterial infections with a markedly increased mortality in response to sepsis. Because metabolic reprogramming modulates immune responses to TLR-4 activation, we investigated the effect of MKP-1 deficiency on mitochondrial electron transport chains involved in oxidative phosphorylation and transcription factors regulating mitochondrial biogenesis. Mitochondrial biogenesis is regulated by three nuclear-encoded proteins, including transcription factor A (TFAM), nuclear respiratory factors (NRF-1), and peroxisome proliferator–activated receptor γ coactivator-1-α (PGC-1α). We show that MKP-1–deficient mice/macrophages exhibit, at baseline, higher expression of oxidative phosphorylation, TFAM, PGC-1α, and NRF-1 associated with increased respiration and production of reactive oxygen species as compared with wild-type mice. Surprisingly, MKP-1–deficient mice/macrophages responded to Escherichia coli sepsis or LPS with an impaired metabolic switch; despite enhanced glycolysis, a preserved mitochondrial function and biogenesis are exhibited. Furthermore, inhibition of p38 MAPK had no significant effect on TFAM and NRF-1 either in MKP-1–deficient macrophages or in wild-type macrophages. These findings support the conclusion that MKP-1 plays an important role in regulating proteins involved in glycolysis and oxidative phosphorylation and modulates expression of mitochondrial transcription factors.
Behavior simulation of nitrogen compounds in rivers with uncertainty analysis
Authors: Fortunato Tatiana Candeia da Silva , Reis José Antonio Tosta dos , Mendonça Antonio Sérgio , Silva Fernando Das Graças Braga da 
Published: May 2020

This study simulated nitrogen-compound concentration changes in rivers, taking into account uncertainty analysis carried out by the Monte Carlo Method. The study area is the final stretch of the Piracicaba River, located in Minas Gerais, Brazil, which is an important Doce River tributary. The uncertainty analysis took into account random generation of hydrodynamic variables, initial water quality conditions and kinetic constants. Different variation percentages for the organic nitrogen decay kinetic constants random generation did not influence considerably the ammonia or organic nitrogen maximum concentration extreme values. In the simulations, maximum organic nitrogen concentrations were most frequently between 0.20 mg.L-1 and 0.22 mg.L-1 (42%), maximum ammonia nitrogen between 0.28 mg.L-1 and 0.30 mg.L-1 (30%), maximum nitrite between 0.05 mg.L-1 and 0.07 mg.L-1 (49%) and maximum nitrate between 0.46 mg.L-1 and 0.50 mg.L-1 (37%). Estimated maximum concentrations for ammonia nitrogen, nitrite and nitrate did not exceed the environmental quality standards established by Brazilian CONAMA Resolution 357/2005 for Class 2 watercourses. Random generation of kinetic constants that regulate ammonia and nitrite decay produced significant ammonia nitrogen, nitrite, and nitrate peak concentrations value frequencies, histograms and forms changes, when considering variation percentages equal to or greater than 50%. Some simulation results showed more inhibition of oxidized nitrogen forms production.