bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Tidal Clock Effects of the Lunisolar Gravitational Field and the Earth’s Tidal Deformation
Authors: Qin Cheng-Gang , Tan Yu-Jie , Shao Ceng-Gang 
Published: November 2020

Abstract
State-of-the-art atomic and optical clocks have the great potential to precisely test fundamental physical assumptions and enhance our understanding of nature. Their widespread applications require us to rigorously deduce the relativistic frequency shift in the framework of general relativity. One interesting question for clocks is tidal field effect which contains variously periodic variations. By introducing tidally deformed Earth, the general algorithms for clock and frequency comparisons are derived. We investigate the effects of external gravitational bodies and Earth’s tidal deformation on the ground- and space-based clocks. The orbital elements of satellite and locations of laboratory are introduced for corresponding clocks, in which the secular and long-period terms and short-period terms are subsequently presented. These effects called tidal clock effects produce the non-negligible contributions in the modern clock experiments and can be directly evaluated from our parameterized formulas. In addition, we also demonstrate for tidal clock effects the position and distance dependences, as well as periodicity. These tidal effects and dependences can provide valuable information for the clock comparison experiments.
A Likely Magnetic Activity Cycle for the Exoplanet Host M Dwarf GJ 3512
Authors: Lopez-Santiago Javier , Martino Luca , Míguez Joaquín , Vázquez Manuel A. 
Published: November 2020

Abstract
Current radial velocity data from specialized instruments contain a large amount of information that may pass unnoticed if their analysis is not accurate. The joint use of Bayesian inference tools and frequency analysis has been shown as effective in revealing exoplanets but they have been used less frequently to investigate stellar activity. We intend to use radial velocity data of the exoplanet host star GJ 3512 to investigate its magnetic activity. Our study includes the analysis of the photometric data available. The main objectives of our work are to constrain the orbital parameters of the exoplanets in the system, to determine the current level of activity of the star and to derive an activity cycle length for it. An adaptive importance sampling method was used to determine the parameters of the exoplanets orbit. Generalized Lomb–Scargle periodograms were constructed with both radial velocity curve and photometric data. A careful analysis of the harmonic frequencies was conducted in each periodogram. Our fit to multiple Keplerian orbits constrained the orbital parameters of two giant gas planets orbiting the star GJ 3512. The host star showed an increase of its magnetic activity during the last observing campaign. The accurate fit of the radial velocity curve data to the multi-Keplerian orbit permitted to reveal the star rotation in the residuals of the best fit and estimate an activity cycle length of ∼14 yr.
Canonical X-Ray Fluorescence Line Intensities as Column Density Indicators
Authors: Rahin Roi , Behar Ehud 
Published: November 2020

Abstract
X-ray line fluorescence is ubiquitous around powerful accretion sources, namely, active galactic nuclei and X-ray binaries. The brightest and best-studied line is the Fe Kα line at λ = 1.937 Å(6.4 keV). This paper presents a survey of all well-measured Chandra/HETG grating spectra featuring several Kα fluorescence lines from elements between Mg and Ni. Despite the variety of sources and physical conditions, we identify a common trend that dictates the Kα line intensity ratios between elements. For the most part, the line intensities are well described by a simple, plane-parallel approximation of a near-neutral, solar-abundance, high column density (N
H > 1024 cm−2) medium. This approximation gives canonical photon-intensity line ratios for the Kα fluorescence of all elements, e.g., 0.104:0.069:1.0:0.043 for Si:S:Fe:Ni, respectively. Deviations from these ratios are shown to be primarily due to excess column density along the line of sight beyond the Galactic column. Therefore, measured fluorescence line ratios provide an independent estimate of N
H and insight into the environment of accretion sources. Residual discrepancies with the canonical ratios could be due to a variety of effects such as a fluorescing medium with N
H < 1024 cm−2, a non-neutral medium, variations in the illuminating spectrum, nonsolar abundances, or an irregular source geometry. However, evidently and perhaps surprisingly, these are uncommon, and their effect remains minor.
Screening Effects on Electron Capture Rates and Type Ia Supernova Nucleosynthesis
Authors: Mori Kanji , Suzuki Toshio , Honma Michio , Famiano Michael A. , Kajino Toshitaka , Kusakabe Motohiko , Balantekin A. Baha 
Published: November 2020

Abstract
Type Ia supernovae (SNe Ia) are believed to be a thermonuclear explosion of a white dwarf, but the mass of their progenitors is still an open problem. In near-Chandrasekhar-mass (near-M
Ch) models of SNe Ia, the central density reaches ≳109 g cm−3. The electron chemical potential becomes higher than the Q-values of electron capture (EC) transitions between fp-shell nuclei, so a portion of the available electrons is captured by iron group elements and thus neutron-rich isotopes are formed. Since EC reaction rates are sensitive to the density, the degree of neutronization is a key to distinguish near- and sub-M
Ch models. In order to compare observations and theoretical models, an accurate treatment of EC reactions is necessary. In previous theoretical works, however, effects of electron screening on ECs are ignored. Screening lowers EC rates and thus leads to a higher electron fraction. We implement electron screening on ECs to calculate explosive SN Ia nucleosynthesis in a near-M
Ch single degenerate model. It is found that some of neutron-rich nuclear abundances, namely, those of 46,48Ca, 50Ti, 54Cr, 58Fe, 64Ni, and 67,70Zn, decrease when screening effects on ECs are considered. Of these, 50Ti, 54Cr, and 58Fe are particularly interesting because a significant portion of the solar abundance of these nuclei is presumed to originate from SNe Ia. We conclude that implementing the screening effect on ECs in modern SN Ia models is desirable to precisely calculate abundances of neutron-rich nuclides.
Recurrent Galactic Cosmic-Ray Flux Modulation in L1 and Geomagnetic Activity during the Declining Phase of the Solar Cycle 24
Authors: Grimani Catia , Cesarini Andrea , Fabi Michele , Sabbatini Federico , Telloni Daniele , Villani Mattia 
Published: November 2020

Abstract
Short-term variations (<1 month) of the galactic cosmic-ray (GCR) flux in the inner heliosphere are mainly associated with the passage of high-speed solar wind streams (HSS) and interplanetary (IP) counterparts of coronal mass ejections (ICMEs). Data gathered with a particle detector flown on board the ESA LISA Pathfinder (LPF) spacecraft, during the declining part of solar cycle 24 (2016 February–2017 July) around the Lagrange point L1, have allowed us to study the characteristics of recurrent cosmic-ray flux modulations above 70 MeV n−1. It is shown that the amplitude and evolution of individual modulations depend in a unique way on both IP plasma parameters and particle flux intensity before HSS and ICME transit. By comparing the LPF data with those gathered contemporaneously with the magnetic spectrometer experiment AMS-02 on board the International Space Station and with those of Earth’s polar neutron monitors, the GCR flux modulation was studied at different energies during recurrent short-term variations. It is also aimed to set the near real-time particle observation requirements to disentangle the role of long- and short-term variations of the GCR flux to evaluate the performance of high-sensitivity instruments in space such as the future interferometers for gravitational wave detection. Finally, the association between recurrent GCR flux variation observations in L1 and weak to moderate geomagnetic activity in 2016–2017 is discussed. Short-term recurrent GCR flux variations are good proxies of recurrent geomagnetic activity when the B
z
component of the IP magnetic field is directed north.
Internetwork Magnetic Fields Seen in Fe i 1564.8 nm Full-disk Images
Authors: Hanaoka Yoichiro , Sakurai Takashi 
Published: November 2020

Abstract
We studied the properties of internetwork magnetic fields in the solar photosphere, taking advantage of full-disk Stokes V/I maps of the Fe i 1564.8 nm line, which were obtained during 2010–2019. In contrast to most previous studies, we used data with moderate spatial and spectral resolutions. Nonetheless, we were able to distinguish the internetwork field components and the active region/network boundary components using large Zeeman splitting of the Fe i 1564.8 nm line. Thus, our analysis provides a point of view quite different from that of previous studies. We analyzed the data statistically without ordinary inversions, yet we successfully derived some properties of internetwork fields; the internetwork is filled with small-scale magnetic fields, their strength is within the weak field regime of the Fe i 1564.8 nm line (300–400 G or less), and the internetwork fields are highly inclined. Although the results were obtained from the analysis performed from a different perspective, they are consistent with the majority of previous findings. In addition, no notable variation in the properties of the internetwork fields was found during the period covering most of solar cycle 24.
Zero Net Flux MRI Turbulence in Disks: Sustenance Scheme and Magnetic Prandtl Number Dependence
Authors: Mamatsashvili George , Chagelishvili George , Pessah Martin E. , Stefani Frank , Bodo Gianluigi 
Published: November 2020

Abstract
We investigate sustenance and dependence on magnetic Prandtl number (Pm) for magnetorotational instability (MRI)-driven turbulence in Keplerian disks with zero net magnetic flux using standard shearing box simulations. We focus on the turbulence dynamics in Fourier space, capturing specific/noncanonical anisotropy of nonlinear processes due to disk flow shear. This is a new type of nonlinear redistribution of modes over wavevector orientations in Fourier space—the nonlinear transverse cascade—which is generic to shear flows and fundamentally different from the usual direct/inverse cascade. The zero flux MRI has no exponentially growing modes, so its growth is transient, or nonmodal. Turbulence self-sustenance is governed by constructive cooperation of the transient growth of MRI and the nonlinear transverse cascade. This cooperation takes place at small wavenumbers (on the flow size scales) referred to as the vital area in Fourier space. The direct cascade transfers mode energy from the vital area to larger wavenumbers. At large Pm, the transverse cascade prevails over the direct one, keeping most of modes’ energy contained in small wavenumbers. With decreasing Pm, however, the action of the transverse cascade weakens and can no longer oppose the action of the direct cascade, which more efficiently transfers energy to higher wavenumbers, leading to increased resistive dissipation. This undermines the sustenance scheme, resulting in the turbulence decay. Thus, the decay of zero net flux MRI turbulence with decreasing Pm is attributed to the topological rearrangement of the nonlinear processes when the direct cascade begins to prevail over the transverse cascade.
The Zwicky Transient Facility Bright Transient Survey. II. A Public Statistical Sample for Exploring Supernova Demographics*
Authors: Perley Daniel A. , Fremling Christoffer , Sollerman Jesper , Miller Adam A. , Dahiwale Aishwarya S. , Sharma Yashvi , Bellm Eric C. , Biswas Rahul , Brink Thomas G. , Bruch Rachel J. , De Kishalay , Dekany Richard , Drake Andrew J. , Duev Dmitry A. , Filippenko Alexei V. , Gal-Yam Avishay , Goobar Ariel , Graham Matthew J. , Graham Melissa L. , Ho Anna Y. Q. , Irani Ido , Kasliwal Mansi M. , Kim Young-Lo , Kulkarni S. R. , Mahabal Ashish , Masci Frank J. , Modak Shaunak , Neill James D. , Nordin Jakob , Riddle Reed L. , Soumagnac Maayane T. , Strotjohann Nora L. , Schulze Steve , Taggart Kirsty , Tzanidakis Anastasios , Walters Richard S. , Yan Lin 
Published: November 2020

Abstract
We present a public catalog of transients from the Zwicky Transient Facility (ZTF) Bright Transient Survey, a magnitude-limited (m < 19 mag in either the g or r filter) survey for extragalactic transients in the ZTF public stream. We introduce cuts on survey coverage, sky visibility around peak light, and other properties unconnected to the nature of the transient, and show that the resulting statistical sample is spectroscopically 97% complete at <18 mag, 93% complete at <18.5 mag, and 75% complete at <19 mag. We summarize the fundamental properties of this population, identifying distinct duration–luminosity correlations in a variety of supernova (SN) classes and associating the majority of fast optical transients with well-established spectroscopic SN types (primarily SN Ibn and II/IIb). We measure the Type Ia SN and core-collapse (CC) SN rates and luminosity functions, which show good consistency with recent work. About 7% of CC SNe explode in very low-luminosity galaxies (M

i
> −16 mag), 10% in red-sequence galaxies, and 1% in massive ellipticals. We find no significant difference in the luminosity or color distributions between the host galaxies of SNe Type II and SNe Type Ib/c, suggesting that line-driven wind stripping does not play a major role in the loss of the hydrogen envelope from their progenitors. Future large-scale classification efforts with ZTF and other wide-area surveys will provide high-quality measurements of the rates, properties, and environments of all known types of optical transients and limits on the existence of theoretically predicted but as yet unobserved explosions.
Analytical and Numerical Studies of Central Galactic Outflows Powered by Tidal Disruption Events: A Model for the Fermi Bubbles?
Authors: Ko C. M. , Breitschwerdt D. , Chernyshov D. O. , Cheng H. , Dai L. , Dogiel V. A. 
Published: November 2020

Abstract
Capture and tidal disruption of stars by the supermassive black hole in the Galactic center (GC) should occur regularly. The energy released and dissipated by these processes will affect both the ambient environment of the GC and the Galactic halo. The single star of a super-Eddington eruption generates a subsonic outflow with an energy release of more than 1052 erg, which still is not high enough to push shock heated gas into the halo. Only routine tidal disruption of stars near the GC can provide enough cumulative energy to form and maintain large-scale structures like the Fermi Bubbles. The average rate of disruption events is expected to be 10−4 ∼ 10−5 yr−1, providing the average power of energy release from the GC into the halo of

erg s−1, which is needed to support the Fermi Bubbles. The GC black hole is surrounded by molecular clouds in the disk, but their overall mass and filling factor are too low to significantly stall the shocks from tidal disruption events. The de facto continuous energy injection on timescales of megayears will lead to the propagation of strong shocks in a density stratified Galactic halo and thus create elongated bubble-like features that are symmetric to the Galactic midplane.
Evolution of C iv Absorbers. I. The Cosmic Incidence
Authors: Hasan Farhanul , Churchill Christopher W. , Stemock Bryson , Mathes Nigel L. , Nielsen Nikole M. , Finlator Kristian , Doughty Caitlin , Croom Mark , Kacprzak Glenn G. , Murphy Michael T. 
Published: November 2020

Abstract
We present a large high-resolution study of the distribution and evolution of C iv absorbers, including the weakest population with equivalent widths

. By searching 369 high-resolution, high signal-to-noise ratio spectra of quasars at

from Keck/HIRES and VLT/UVES, we find 1268 C iv absorbers with

Å (our ∼50% completeness limit) at redshifts

. A Schechter function describes the observed equivalent width distribution with a transition from power-law to exponential decline at

. The power-law slope α rises by ∼7%, and the transition equivalent width W
⋆ falls by ∼20% from

to 3.6. We find that the comoving redshift path density,

, of

Å absorbers rises by ∼1.8 times from z ≃ 4.0 to 1.3, while the

Å

rises by a factor of ∼8.5. We quantify the observed evolution by a model in which

decreases linearly with increasing redshift. The model suggests that populations with larger

thresholds evolve faster with redshift and appear later in the universe. The cosmological Technicolor Dawn simulations at z = 3–5 overproduce the observed abundance of absorbers with

while yielding better agreement at higher

. Our empirical linear model successfully describes C iv evolution in the simulations and the observed evolution of

Å C iv for the past

. Combining our measurements with the literature gives us a picture of C iv absorbing structures becoming more numerous and/or larger in physical size over the last

of cosmic time (z ∼ 6–0).
The Kinematic Evolution of Erupting Structures in Confined Solar Flares
Authors: Huang Z. W. , Cheng X. , Ding M. D. 
Published: November 2020

Abstract
In this Letter, we study the kinematic properties of ascending hot blobs associated with confined flares. Taking advantage of high-cadence extreme-ultraviolet images provided by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we find that for the 26 events selected here, the hot blobs are first impulsively accelerated outward, but then quickly slow down to motionlessness. Their velocity evolution is basically synchronous with the temporal variation of the Geostationary Operational Environmental Satellite soft X-ray flux of the associated flares, except that the velocity peak precedes the soft X-ray peak by minutes. Moreover, the duration of the acceleration phase of the erupting blobs is moderately correlated with that of the flare rise phase. For nine of the 26 cases, the erupting blobs even appear minutes prior to the onset of the associated flares. Our results show that a fraction of confined flares also involve the eruption of a magnetic flux rope, which sometimes is formed and heated prior to the flare onset. We suggest that the initiation and development of these confined flares are similar to that of eruptive ones, and the main difference may lie in the background field constraint, which is stronger for the former than for the latter.
GWSkyNet: A Real-time Classifier for Public Gravitational-wave Candidates
Authors: Cabero Miriam , Mahabal Ashish , McIver Jess 
Published: November 2020

Abstract
The rapid release of accurate sky localization for gravitational-wave (GW) candidates is crucial for multi-messenger observations. During the third observing run of Advanced LIGO and Advanced Virgo, automated GW alerts were publicly released within minutes of detection. Subsequent inspection and analysis resulted in the eventual retraction of a fraction of the candidates. Updates could be delayed by up to several days, sometimes issued during or after exhaustive multi-messenger follow-up campaigns. We introduce GWSkyNet, a real-time framework to distinguish between astrophysical events and instrumental artifacts using only publicly available information from the LIGO-Virgo open public alerts. This framework consists of a non-sequential convolutional neural network involving sky maps and metadata. GWSkyNet achieves a prediction accuracy of 93.5% on a testing data set.
Operating experience and ways to improve the performance of the service water supply system at the Novovoronezh NPP II (Units 1 and 2)
Authors: Povarov Vladimir P. , Statsura Dmitry B. , Usachev Dmitry Ye. 
Published: November 2020

The operating experience of Novovoronezh NPP II-1 shows that, in the summer period, the temperature of the cooling water exceeds the design value: this indicates the insufficient performance of the service water supply system. The main factor that has a negative impact on the performance of this system is the formation of carbonate deposits on the cooling tower filler. At Novovoronezh NPP II-1, the cooling tower water distribution system was cleaned from carbonate deposits by the method of combined vibration and aerohydraulic impact. The tested method of cleaning the filler cannot be considered optimal, since the main stage that determines the entire cleaning duration is the assembly/disassembly of the cooling tower filler. It is necessary to continue research on the choice of a strategy for controlling the carbonate deposition rate, taking into account the revealed influence of the design features of the main cooling water pipelines and pipelines of the cooling tower water distribution system on the mechanism of deposit formation in the peripheral spraying area.
As compensating measures to ensure the required temperature regime of the turbine plant equipment at Novovoronezh NPP II-1, it is practiced during the summer period to put the standby heat exchangers of the lubrication system and the standby pump of the nonessential services cooling water system into parallel operation. This solution is fraught with the risk of an unplanned decrease in the electrical load if this equipment is turned off in the event of a malfunction.
To increase the operating stability of Novovoronezh NPP II-1 and -2 in the summer period, it is proposed to carry out a number of measures aimed at mitigating the negative consequences caused by the elevated service water temperature.
Equipment upgrade options are evaluated, e.g., by installing an additional pump for the turbine building services cooling system and (or) laying an additional pipeline to supply part of the makeup water from the Don River directly to the suction pipelines of the pumps of the turbine building services cooling system.
L’enseignement supérieur en France
Authors: Dumont Gérard-François 
Published: November 2020

Le nombre d’étudiants de l’enseignement supérieur a connu, en France, une évolution irrégulière en fonction des dynamiques démographiques et des taux de scolarisation. La répartition démographique des étudiants montre une singularité du système français, marqué par une diversité d’institutions exerçant des missions différentes. Une approche économique permet d’évaluer la part du Produit Intérieur Brut consacrée à l’enseignement supérieur et l’apport des différents financeurs. Quels sont les besoins du futur ?
Tu aimeras tes microbes comme toi-même
Authors: Sansonetti Philippe 
Published: November 2020

Si l'histoire de la microbiologie a prouvé que l'existence de « bulles » sans microbes était possible, à quoi ressemblerait un monde sans microbes ?

Entre représentations utopiques et faits scientifiques, Philippe Sansonetti retrace l’épopée des microbes, de leur découverte en 1674 jusqu’à nos jours, et invite à réfléchir sur le regard que nous portons sur ces êtres vivants apparus il y a 3 milliards et demi d’années. Paraphrasant l’Évangile selon saint Matthieu – tu aimeras tes microbes comme toi-même –, il nous alerte sur les dangers de l’appauvrissement en cours de la diversité microbienne. S’il faut maîtriser les microbes pathogènes, il faut également préserver les microbes indispensables à l’équilibre du vivant et de la planète. Cette perspective nécessite des changements drastiques dans nos approches médicales, vétérinaires et environnementales.