bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intermediate-mass Early-type Disk Galaxies in the Virgo Cluster. II. Near-Infrared Spectra and Evidence for Differences in Evolution* † ‡

†

‡
Authors: Davidge T. J. 
Published: April 2020

Abstract
We discuss near-infrared (NIR) slit spectra of six early-type disk galaxies in the Virgo Cluster that were examined previously at visible/red wavelengths. Despite having similar intrinsic luminosities, colors, and morphologies, the NIR spectrophotometric properties of these galaxies indicate that they are not a homogeneous ensemble differing only in terms of luminosity-weighted age and metallicity. While the depth of the CO(2,0) band is consistent with the centers of these galaxies having solar or slightly sub-solar luminosity-weighted metallicities, galaxy-to-galaxy variations in the depth of the Na i 2.21 μm doublet are found, with Na i2.21 μm lines in three galaxies (NGC 4491, NGC 4584, and NGC 4620) that are deeper than those predicted for a solar chemical mixture and a solar-neighborhood mass function. In contrast, the Ca i2.26 μm triplet shows good galaxy-to-galaxy agreement but tends to be deeper than the model prediction. Considering the depth of the NaD lines, the deep Na i2.21 μm lines are tentatively attributed to a bottom-heavy mass function. This is counter to observed trends between mass function slope and velocity dispersion, and so the possibility of a super-solar [Na/Fe] is also discussed. Two of the three galaxies with deep Na i 2.21 μm (NGC 4584 and NGC 4620) have Sérsic exponents that are consistent with a classical bulge. As for NGC 4491, its central NIR spectrum contains prominent emission lines. The relative strengths of Brγ and H2S(1), the presence of [Fe ii] emission, and the mid-infrared spectral-energy distribution are all consistent with intense recent star formation near the center of that galaxy. The NIR spectrum of NGC 4584 is devoid of line emission in the NIR, suggesting that star formation does not power the emission detected at visible wavelengths from that galaxy. Wavelengths that contain the Ballick–Ramsey C2 band at 1.76 μm are matched by moderately metal-poor E-MILES model spectra with an age of 2 Gyr. The radial age trends in these galaxies are in the opposite sense to those in late-type disk galaxies, and it is concluded that they have evolved in a cluster environment for at least several Gyr.
Variability and the Size–Luminosity Relation of the Intermediate-mass AGN in NGC 4395
Authors: Cho Hojin , Woo Jong-Hak , Hodges-Kluck Edmund , Son Donghoon , Shin Jaejin , Gallo Elena , Bae Hyun-Jin , Brink Thomas G. , Cho Wanjin , Filippenko Alexei V. , Horst John C. , Ilić Dragana , Joner Michael. D. , Kang Daeun , Kang Wonseok , Kaspi Shai , Kim Taewoo , Kovačević Andjelka B. , Kumar Sahana , N. Le Huynh Anh , Nadzhip A. E. , Pozo Nuñez Francisco , Metlov V. G. , Oknyansky V. L. , Park Songyoun , Popović Luka Č. , Rakshit Suvendu , Schramm Malte , Shatsky N. I. , Spencer Michelle , Sung Eon-Chang , Sung Hyun-il , Tatarnikov A. M. , Vince Oliver 
Published: April 2020

Abstract
We present a variability study of the lowest-luminosity Seyfert 1 nucleus of the galaxy NGC 4395 based on photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC 4395 with a ∼5-minute cadence during a period of 10 days and obtained light curves in the ultraviolet (UV), V, J, H, and K/Ks
bands, as well as narrowband Hα. The rms variability is ∼0.13 mag in the Swift UVM2 and V filter light curves, decreasing down to ∼0.01 mag in the K filter. After correcting for the continuum contribution to the Hα narrow band, we measured the time lag of the Hα emission line with respect to the V-band continuum as

–

minutes in 2017 and

–

minutes in 2018, depending on assumptions about the continuum variability amplitude in the Hα narrow band. We obtained no reliable measurements for the continuum-to-continuum lag between UV and V bands and among near-IR bands, owing to the large flux uncertainty of UV observations and the limited time baseline. We determined the active galactic nucleus (AGN) monochromatic luminosity at 5100 Å,

, after subtracting the contribution of the nuclear star cluster. While the optical luminosity of NGC 4395 is two orders of magnitude lower than that of other reverberation-mapped AGNs, NGC 4395 follows the size–luminosity relation, albeit with an offset of 0.48 dex (≥2.5σ) from the previous best-fit relation of Bentz et al.
On Frequency-dependent Dispersion Measures and Extreme Scattering Events
Authors: Lam M. T. , Lazio T. J. W. , Dolch T. , Jones M. L. , McLaughlin M. A. , Stinebring D. R. , Surnis M. 
Published: April 2020

Abstract
Radio emission propagating over an Earth-pulsar line of sight provides a unique probe of the intervening ionized interstellar medium (ISM). Variations in the integrated electron column density along this line of sight, or dispersion measure (DM), have been observed since shortly after the discovery of pulsars. As early as 2006, frequency-dependent DMs have been observed and attributed to several possible causes. Ray-path averaging over different effective light-cone volumes through the turbulent ISM contributes to this effect, as will DM misestimation due to radio propagation across compact lensing structures such as those caused by “extreme scattering events (ESEs).” We present methods to assess the variations in frequency-dependent DMs due to the turbulent ISM versus these compact lensing structures along the line of sight. We analyze recent Low-Frequency Array observations of PSR J2219+4754 to test the underlying physical mechanism of the observed frequency-dependent DM. Previous analyses have indicated the presence of strong lensing due to compact overdensities halfway between the Earth and pulsar. Instead, we find the frequency dependence of the DM time series for PSR J2219+4754 is consistent with being due solely to ISM turbulence and there is no evidence for any ESE or small-scale lensing structure. The data show possible deviations from a uniform turbulent medium, suggesting that there may be an enhanced scattering screen near one of the two ends of the line of sight. We present this analysis as an example of the power of low-frequency observations to distinguish the underlying mechanisms in frequency-dependent propagation effects.
Coronal Electron Temperature Inferred from the Strahl Electrons in the Inner Heliosphere: Parker Solar Probe and Helios Observations
Authors: Berčič Laura , Larson Davin , Whittlesey Phyllis , Maksimović Milan , Badman Samuel T. , Landi Simone , Matteini Lorenzo , Bale Stuart. D. , Bonnell John W. , Case Anthony W. , Dudok de Wit Thierry , Goetz Keith , Harvey Peter R. , Kasper Justin C. , Korreck Kelly E. , Livi Roberto , MacDowall Robert J. , Malaspina David M. , Pulupa Marc , Stevens Michael L. 
Published: April 2020

Abstract
The shape of the electron velocity distribution function plays an important role in the dynamics of the solar wind acceleration. Electrons are normally modeled with three components, the core, the halo, and the strahl. We investigate how well the fast strahl electrons in the inner heliosphere preserve the information about the coronal electron temperature at their origin. We analyzed the data obtained by two missions, Helios, spanning the distances between 65 and 215 R
S, and Parker Solar Probe (PSP), reaching down to 35 R
S during its first two orbits around the Sun. The electron strahl was characterized with two parameters: pitch-angle width (PAW) and the strahl parallel temperature (T
s∥). PSP observations confirm the already reported dependence of strahl PAW on core parallel plasma beta (

). Most of the strahl measured by PSP appear narrow with PAW reaching down to 30°. The portion of the strahl velocity distribution function aligned with the magnetic field is for the measured energy range well described by a Maxwellian distribution function. T
s∥ was found to be anticorrelated with the solar wind velocity and independent of radial distance. These observations imply that T
s∥ carries the information about the coronal electron temperature. The obtained values are in agreement with coronal temperatures measured using spectroscopy, and the inferred solar wind source regions during the first orbit of PSP agree with the predictions using a PFSS model.
The Variability of the Star Formation Rate in Galaxies. I. Star Formation Histories Traced by EW(Hα) and EW(HδA)
Authors: Wang Enci , Lilly Simon J. 
Published: April 2020

Abstract
To investigate the variability of the star formation rate (SFR) of galaxies, we define a star formation change parameter, SFR5 Myr/SFR800 Myr, which is the ratio of the SFR averaged within the last 5 Myr to the SFR averaged within the last 800 Myr. We show that this parameter can be determined from a combination of Hα emission and Hδ absorption, plus the 4000 Å break, with an uncertainty of ∼0.07 dex for star-forming galaxies. We then apply this estimator to MaNGA galaxies, both globally within R

e
and within radial annuli. We find that the global SFR5 Myr/SFR800 Myr, which indicates by how much a galaxy has changed its specific SFR (sSFR), is nearly independent of its sSFR, i.e., of its position relative to the star formation main sequence (SFMS) as defined by SFR800 Myr. Also, at any sSFR, there are as many galaxies increasing their sSFR as decreasing it, as required if the dispersion in the SFMS is to stay the same. The SFR5 Myr/SFR800 Myr of the overall galaxy population is very close to that expected for the evolving main sequence. Both of these provide a reassuring check on the validity of our calibration of the estimator. We find that galaxies with higher global SFR5 Myr/SFR800 Myr appear to have higher SFR5 Myr/SFR800 Myr at all galactic radii, i.e., that galaxies with a recent temporal enhancement in overall SFR have enhanced star formation at all galactic radii. The dispersion of the SFR5 Myr/SFR800 Myr at a given relative galactic radius and a given stellar mass decreases with the (indirectly inferred) gas depletion time: locations with short gas depletion time appear to undergo bigger variations in their star formation rates on Gyr or less timescales. In Wang et al., we showed that the dispersion in star formation rate surface densities ΣSFR in the galaxy population appears to be inversely correlated with the inferred gas depletion timescale and interpreted this in terms of the dynamical response of a gas-regulator system to changes in the gas inflow rate. In this paper, we can now prove directly with SFR5 Myr/SFR800 Myr that these effects are indeed due to genuine temporal variations in the SFR of individual galaxies on timescales between 107 and 109 yr rather than possibly reflecting intrinsic, non-temporal, differences between different galaxies.
Electron Firehose Instabilities in High-β Intracluster Shocks
Authors: Kim Sunjung , Ha Ji-Hoon , Ryu Dongsu , Kang Hyesung 
Published: April 2020

Abstract
The preacceleration of electrons through reflection and shock drift acceleration (SDA) is essential for the diffusive shock acceleration of nonthermal electrons in collisionless shocks. Previous studies suggested that, in weak quasi-perpendicular (Q
⊥) shocks in the high-β (

) intracluster medium (ICM), the temperature anisotropy due to SDA-reflected electrons can drive the electron firehose instability, which excites oblique nonpropagating waves in the shock foot. In this paper, we investigate, through a linear analysis and particle-in-cell simulations, the firehose instabilities driven by an electron temperature anisotropy (ETAFI) and also by a drifting electron beam (EBFI) in β ∼ 100 ICM plasmas. The EBFI should be more relevant to describing the self-excitation of upstream waves in Q
⊥-shocks, since backstreaming electrons in the shock foot behave more like an electron beam rather than an anisotropic bi-Maxwellian population. We find that the basic properties of the two instabilities, such as the growth rate, γ, and the wavenumber of fast-growing oblique modes, are similar in the ICM environment, with one exception; while the waves excited by the ETAFI are nonpropagating (ω

r
= 0), those excited by the EBFI have a nonzero frequency (

). However, the frequency is small with ω

r
< γ. Thus, we conclude that the interpretation of previous studies for the nature of upstream waves based on the ETAFI remains valid in Q
⊥-shocks in the ICM.
Compact Bright Radio-loud AGNs. III. A Large VLBA Survey at 43 GHz
Authors: Cheng X.-P. , An T. , Frey S. , Hong X.-Y. , He X. , Kellermann K. I. , Lister M. L. , Lao B.-Q. , Li X.-F. , Mohan P. , Yang J. , Wu X.-C. , Zhang Z.-L. , Zhang Y.-K. , Zhao W. 
Published: April 2020

Abstract
We present the results from the 43 GHz Very Long Baseline Array (VLBA) observations of 124 compact radio-loud active galactic nuclei (AGNs) that were conducted between 2014 November and 2016 May. The typical dimensions of the restoring beam in each image are about 0.5 mas × 0.2 mas. The highest resolution of 0.2 mas corresponds to a physical size of 0.02 pc for the lowest redshift source in the sample. The 43 GHz very long baseline interferometry (VLBI) images of 97 AGNs are presented for the first time. We study the source compactness on milliarcsecond and submilliarcsecond scales, and suggest that 95 sources in our sample are suitable for future space VLBI observations. By analyzing our data supplemented with other VLBA AGN surveys from the literature, we find that the core brightness temperature increases with increasing frequency below a break frequency ∼7 GHz, and decreases between ∼7 and 240 GHz but increases again above 240 GHz in the rest frame of the sources. This indicates that the synchrotron opacity changes from optically thick to thin. We also find a strong statistical correlation between radio and γ-ray flux densities. Our correlation is tighter than those in the literature derived from lower-frequency VLBI data, suggesting that the γ-ray emission is produced more cospatially with the 43 GHz VLBA core emission. This correlation can also be extrapolated to the unbeamed AGN population, implying that a universal γ-ray production mechanism might be at work for all types of AGNs.
2SXPS: An Improved and Expanded Swift X-Ray Telescope Point-source Catalog
Authors: Evans P. A. , Page K. L. , Osborne J. P. , Beardmore A. P. , Willingale R. , Burrows D. N. , Kennea J. A. , Perri M. , Capalbi M. , Tagliaferri G. , Cenko S. B. 
Published: April 2020

Abstract
We present the 2SXPS (Swift-XRT Point Source) catalog, containing 206,335 point sources detected by the Swift X-ray Telescope (XRT) in the 0.3–10 keV energy range. This catalog represents a significant improvement over 1SXPS, with double the sky coverage (now 3790 deg2), and several significant developments in source detection and classification. In particular, we present for the first time techniques to model the effect of stray light—significantly reducing the number of spurious sources detected. These techniques will be very important for future, large effective area X-ray missions, such as the forthcoming Athena X-ray observatory. We also present a new model of the XRT point-spread function and a method for correctly localizing and characterizing piled-up sources. We provide light curves—in four energy bands, two hardness ratios, and two binning timescales—for every source, and from these deduce that over 80,000 of the sources in 2SXPS are variable in at least one band or hardness ratio. The catalog data can be queried or downloaded via a web interface at https://www.swift.ac.uk/2SXPS, via HEASARC, or in Vizier (IX/58).
Characterization of katG, inhA, rpoB and pncA in Mycobacterium tuberculosis isolates from MDR-TB risk patients in Thailand
Authors: Suthum Krairerk , Samosornsuk Worada , Samosornsuk Seksun 
Published: April 2020

Introduction: Multidrug-resistant tuberculosis (MDR-TB) is commonly found in Thailand especially in the public health region 5, the Western region of Thailand. This study’s aim was to characterize katG, inhA, rpoB and pncA genes in Mycobacterium tuberculosis.
Methodology: One hundred strains of Mycobacterium tuberculosis (MTB) were isolated from sputum samples of MDR-TB risk patients in the laboratory of the Office of Disease Prevention and Control 5th Ratchaburi province, Thailand from January to December 2015. Drug susceptibility testing (DST) was performed using a BACTEC MGIT 960 system. Furthermore, the genes katG, inhA, rpoB and pncA were characterized by DNA sequencing.
Results: Of a total of 100 MTB samples which underwent drug susceptibility testing, 42% showed isoniazid (INH) and rifampicin (RIF) resistance, and a further 25% showed INH mono-resistance (25%). The most common gene mutations found using DNA sequencing were katG_Ser315Thr (70%), rpoB_Ser531leu (81%) and pncA_Ile31Thr (84%). The common mutation of pncA_Ile31Thr substitution was detected in 26 of 91 (29%) pyrazinamide (PZA) susceptible isolates.
Conclusion: Using DNA sequencing to screen for gene mutations conferring drug resistance may be feasible and use less time than using DST to detect resistance patterns.
The novel zoonotic COVID-19 pandemic: An expected global health concern
Authors: Contini Carlo , Di Nuzzo Mariachiara , Barp Nicole , Bonazza Aurora , De Giorgio Roberto , Tognon Mauro , Rubino Salvatore 
Published: April 2020

18 years ago, in 2002, the world was astonished by the appearance of Severe Acute Respiratory Syndrome (SARS), supported by a zoonotic coronavirus, called SARS-CoV, from the Guangdong Province of southern China. After about 10 years, in 2012, another similar coronavirus triggered the Middle East Respiratory Syndrome (MERS-CoV) in Saudi Arabia. Both caused severe pneumonia killing 774 and 858 people with 8700 cases of confirmed infection for the former, and 2494 for the latter, causing significant economic losses. 8 years later, despite the MERS outbreak remaining in certain parts of the world, at the end of 2019, a new zoonotic coronavirus (SARS-CoV-2) and responsible of coronavirus Disease (COVID-19), arose from Wuhan, Hubei Province, China. It spread rapidly and to date has killed 3,242 persons with more than 81,000 cases of infection in China and causing over 126,000 global cases and 5,414 deaths in 166 other countries around the world, especially Italy. SARS-CoV-2 would seem to have come from a bat, but the intermediate reservoir continues to be unknown. Nonetheless, as for SARS-CoV and MERS CoV, the Spillover effect linked to animal-human promiscuity, human activities including deforestation, illegal bush-trafficking and bushmeat, cannot be excluded. Recently, however, evidence of inter-human only transmission of SARS-CoV-2 has been accumulated and thus, the outbreak seems to be spreading by human-to-human transmission throughout a large part of the world.
Herein we will provide with an update on the main features of COVID-19 and suggest possible solutions how to halt the expansion of this novel pandemic.
Communication in Pediatric Critical Care Units: A Review of the Literature
Authors: Hallman Melissa L. , Bellury Lanell M. 
Published: April 2020

Topic
Current communication styles in pediatric critical care units do not often consider the needs of providers, patients, or family members.

Clinical Relevance
The Child Hospital Consumer Assessment of Healthcare Providers and Systems score has begun real-world testing and soon will be mandatory and tied to reimbursement. Poor communication in pediatric critical care units can lead to reduced continuity of care, escalated or unnecessary care, and poor outcomes for patients and hospitals. Improving communication in pediatric critical care units is imperative.

Purpose of Paper
Extant literature was reviewed to assess communication in pediatric critical care from the provider, parent, and patient perspectives. Communication tools were also reviewed.

Content Covered
Twenty-eight articles met inclusion criteria and were analyzed according to study focus (provider, parent/caregiver, patient, or tool). This review links communication to outcomes related to providers, parents, and patients. Current tools are reviewed to evaluate their effectiveness in addressing communication barriers and to guide future research in communication. Findings indicate that effective communication is challenging in intensive care units despite robust evidence that effective communication improves patient outcomes and quality metrics. Repeated and varied forms of communication, especially written reinforced with verbal communication, seem to have the strongest effect and show promising results. Common barriers nurses face on their units are identified, and solutions are suggested. This review adds to current knowledge by linking communication to measurable outcomes and examining communication barriers and needs specific to pediatric critical care populations from the provider, parent, and patient perspectives.
NEW PLANT BREEDING TECHNOLOGIES FOR A SUSTAINABLE AGRICULTURE
Authors: Kater Martin 
Published: April 2020

Agriculture has a 10,000-year history. During this period, humans selected natural mutants that were found to be useful for cultivation and human consumption. However, the selected characteristics are not always favorable for the plants themselves, often compromising their ability to survive and adapt to the natural environment. In this way, cultivated plants have become dependent, for their survival, on man as man is dependent on plants to survive. The increase in agricultural production was notable during the green revolution and even afterwards new genetic knowledge made it possible to drastically increase food production. However, now with the rapid growth of the world population, the selection of new cultivars has become necessary, not only capable of producing more but also able to do so with less water, fertilizers, insecticides etc. Plants that are more resistant to biotic and abiotic stresses, which are increasingly frequent in a world where climate change is becoming a major challenge for the future. Studying the genomes of plants and the functions of their genes is the only way to accelerate the genetic improvement of plants while protecting the environment. A very important technology to try to solve these problems is "genome editing", using the CRISPR-Cas system. Unfortunately, in Europe the use of this new technology in agriculture has found it is not easy to apply not so much for scientific reasons but for political ideologies contrary to this type of innovation in agriculture.