bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evolution of High-energy Particle Distribution in Supernova Remnants
Authors: Zeng Houdun , Xin Yuliang , Liu Siming 
Published: March 2019

Abstract
Supernova remnants (SNRs) have been considered to be the dominant contributors to Galactic cosmic rays. However, the relation between high-energy particles trapped in SNRs and cosmic rays observed at the Earth remains obscure. In this paper, we fit the spectral energy distributions of 35 SNRs with a simple one-zone emission model and analyze correlations of model parameters to uncover the evolution of high-energy particle distribution in SNRs. We find that (1) the particle distribution in general can be described by a broken power-law function with a high-energy cutoff for all SNRs; (2) the low-energy spectrum becomes harder and the break energy decreases with aging of SNRs, (3) for most middle-age SNRs, the energy loss timescale of electrons at the high-energy cutoff is approximately equal to the age of the corresponding remnant implying quenching of very-high-energy electron acceleration; for young SNRs, this energy loss timescale is shorter than the age of SNRs implying continuous electron acceleration at the cutoff energy; and for a few old age SNRs, the energy loss timescale is longer than the corresponding age, which may suggest escaping of higher energy particles from SNRs. Finally, we comment on the implications of these results on the SNR origin of Galactic cosmic rays.
Systematic Physical Characterization of the γ-Ray Spectra of 2FHL Blazars
Authors: van den Berg Jacobus P. , Böttcher Markus , Domínguez Alberto , López-Moya Marcos 
Published: March 2019

Abstract
We test different physically motivated models for the spectral shape of the γ-ray emission in a sample of 128 blazars with known redshifts detected by the Fermi Large Area Telescope (LAT) at energies above 50 GeV. The first nine years of LAT data in the energy range from 300 MeV to 2 TeV are analyzed in order to extend the spectral energy coverage of the 2FHL blazars in our sample. We compare these spectral data to four leptonic models for the production of γ-rays through Compton scattering by a population of electrons with different spectral shapes. In the first three models we consider Compton scattering in the Thomson regime with different acceleration mechanisms for the electrons. In the fourth model we consider Compton scattering by a pure power-law distribution of electrons with spectral curvature due to scattering in the Klein–Nishina regime. The majority of blazar γ-ray spectra are preferentially fit with either a power law with exponential cutoff in the Thomson regime or a power-law electron distribution with Compton scattering in the Klein–Nishina regime, while a log-parabola with a low-energy power-law and broken power-law spectral shape in the Thomson regime appears systematically disfavored, which is likely a consequence of the restriction to pure Thomson scattering that we imposed on those models. This finding may be an indication that the γ-ray emission from flat-spectrum radio quasars (FSRQs) in the 2FHL catalog is dominated by Compton scattering of radiation from the dusty torus, while in the case of BL Lac objects, it is dominated by synchrotron self-Compton radiation.
The First Galaxy Cluster Discovered by the VISTA Variables in the Vía Láctea Survey
Authors: Baravalle L. D. , Castellón J. L. Nilo , Alonso M. V. , Tello J. Díaz , Damke G. , Valotto C. , Larenas H. Cuevas , Sánchez B. , Ríos M. de los , Minniti D. , Domínguez M. , Gurovich S. , Barbá R. , Soto M. , Castro F. Milla 
Published: March 2019

Abstract
We report the first confirmed detection of the galaxy cluster VVV-J144321-611754 at very low latitudes (l = 315.°836, b = −1.°650) located in the tile d015 of the VISTA Variables in the Vía Láctea (VVV) survey. We defined the region of 30 × 30 arcmin2 centered in the brightest galaxy finding 25 galaxies. For these objects, extinction-corrected median colors of (H−K

s
) = 0.34 ± 0.05 mag, (J−H) = 0.57 ± 0.08 mag, and (J−K

s
) = 0.87 ± 0.06 mag; R
1/2 = 1.59 ± 0.″16; C = 3.01 ± 0.08; and Sérsic index n = 4.63 ± 0.39 were estimated. They were visually confirmed showing characteristics of early-type galaxies in the near-IR images. An automatic clustering analysis performed in the whole tile found that the concentration of galaxies VVV-J144321-611754 is a real, compact concentration of early-type galaxies. Assuming a typical galaxy cluster with low X-ray luminosity, the photometric redshift of the brightest galaxy is z = 0.196 ± 0.025. Follow-up near-IR spectroscopy with FLAMINGOS-2 at the Gemini-South telescope revealed that the two brighter cluster galaxies have typical spectra of early-type galaxies and the estimated redshift for the brightest galaxy VVV-J144321.06-611753.9 is z = 0.234 ± 0.022 and that for VVV-J144319.02-611746.1 is z = 0.232 ± 0.019. Finally, these galaxies clearly follow the cluster red sequence in the rest-frame near-IR color–magnitude diagram with a slope similar to a galaxy cluster at a redshift of 0.2. These results are consistent with the presence of a bona fide galaxy cluster beyond the Milky Way disk.
Examination of the EUV Intensity in the Open Magnetic Field Regions Associated with Coronal Holes
Authors: Huang Guan-Han , Lin Chia-Hsien , Lee Lou-Chuang 
Published: March 2019

Abstract
Coronal holes can be identified as the regions with magnetic field lines extending far away from the Sun, or the darkest regions in EUV/X-ray images with predominantly unipolar magnetic fields. A comparison between the locations of our determined regions with open magnetic field lines (OMF) and regions with low EUV intensity (LIR) reveals that only 12% of the OMF regions coincide with the LIRs. The aim of this study is to investigate the conditions leading to the different brightnesses of OMF regions, and to provide a means to predict whether an OMF region would be bright or dark. Examining the statistical distribution profiles of the magnetic field expansion factor (f

s
) and Atmospheric Imaging Assembly 193 Å intensity (I
193) reveals that both profiles are approximately log-normal. The analysis of the spatial and temporal distributions of f

s
and I
193 indicates that the bright OMF regions often are inside or next to regions with closed field lines, including quiet-Sun regions and regions with strong magnetic fields. Examining the relationship between I
193 and f

s
reveals a weak positive correlation between log I
193 and log f

s
, with a correlation coefficient ≈0.39. As a first-order approximation, the positive relationship is determined to be log I
193 = 0.62 log f

s
+ 1.51 based on the principle of the whitening/dewhitening transformation. This linear relationship is demonstrated to increase the consistency between the OMF regions and LIRs from 12% to 23%.
The Evolution of Magnetic Rayleigh–Taylor Unstable Plumes and Hybrid KH-RT Instability into a Loop-like Eruptive Prominence
Authors: Mishra Sudheer K. , Srivastava A. K. 
Published: March 2019

Abstract
MRT-unstable plumes are observed in a loop-like eruptive prominence using Solar Dynamic Observatory/Atmospheric Imaging Assembly observations. The small-scale cavities are developed within the prominence, where perturbations trigger dark plumes (P1 and P2) propagating with speeds of 35–46 km s−1. The self-similar plume formation initially shows the growth of a linear MRT-unstable plume (P1), and thereafter the evolution of a nonlinear single-mode MRT-unstable second plume (P2). A differential emission measure analysis shows that plumes are less dense and hotter than the prominence. We have estimated the observational growth rate for both plumes as 1.32 ± 0.29 × 10−3 s−1 and 1.48 ± 0.29 × 10−3 s−1, respectively, which are comparable to the estimated theoretical growth rate (1.95 × 10−3 s−1). The nonlinear phase of an MRT-unstable plume (P2) may collapse via a Kelvin–Helmholtz vortex formation in the downfalling plasma. Later, a plasma thread is evident in the rising segment of this prominence. It may be associated with the tangled field and Rayleigh–Taylor instability. The tangled field initiates shearing at the prominence–cavity boundary. Due to this shear motion, the plasma downfall occurred at the right part of the prominence–cavity boundary. It triggers the characteristic KH unstable vortices and MRT-unstable plasma bubbles propagating at different speeds and merging with each other. The shear motion and lateral plasma downfall may initiate hybrid KH-RT instability there.
Electromagnetic Waves around the Proton Cyclotron Frequency in the Sheath Regions of Interplanetary Magnetic Clouds: STEREO Observations
Authors: Li Q. H. , Yang L. , Wu D. J. , Wang T. Y. 
Published: March 2019

Abstract
The compressed and turbulent sheath regions of interplanetary magnetic clouds (IMCs) provide a natural laboratory to study electromagnetic waves (EMWs) around the proton cyclotron frequency f
cp. Based on the Morlet wavelet spectral analysis, the repeated filtering analysis and the minimum variance analysis of high-resolution magnetic field data from the STEREO spacecraft, 81 EMW events are identified in the sheath regions of six IMCs. These EMWs are all transverse, almost circularly polarized, and quasi-parallel propagating along the background magnetic field

. They can be left-handed (LH) or right-handed (RH) polarized in the spacecraft frame, where the occurrence rate of the LH-polarized EMWs is higher than that of RH-polarized ones, consistent with previous observations in the solar wind. Also, a comparative analysis of polarization sense of these EMWs has been made in the spacecraft and plasma frames. Our results show that more than half of EMW events suffer a polarization reversal from the spacecraft to plasma frames, which are deduced to propagate inward relative to the solar wind flow. Others are outward-propagating waves. In the plasma frame, the outward-propagating LH-EMWs and inward-propagating RH-EMWs have relatively higher occurrence rates than the inward-propagating LH-EMWs and outward-propagating RH-EMWs, respectively. Furthermore, in the plasma frame all the frequencies of LH-EMWs are below f
cp, but the RH-EMW frequencies can exceed f
cp. These results are helpful in understanding the physical properties of EMWs and their roles in the sheath regions of IMCs.
The Fraction of Active Galactic Nuclei in the USS 1558–003 Protocluster at z = 2.53
Authors: Macuga Michael , Martini Paul , Miller Eric D. , Brodwin Mark , Hayashi Masao , Kodama Tadayuki , Koyama Yusei , Overzier Roderik A. , Shimakawa Rhythm , Tadaki Ken-ichi , Tanaka Ichi 
Published: March 2019

Abstract
The incidence of active galactic nuclei (AGNs) within the local environment is a potentially valuable probe of the mechanisms that trigger and provide fuel for accretion onto supermassive black holes. While the correlation between AGN fraction and environment has been well-studied in the local universe, AGN fractions have been measured for relatively few dense environments at high redshift. In this paper, we present a measurement of the X-ray AGN fraction in the USS 1558−003 protocluster associated with the z = 2.53 radio galaxy 4C-00.62. Our measurement is based on a 100-ks Chandra observation, follow-up spectroscopy from the Multi-Object Double Spectrograph on the Large Binocular Telescope, and broad and narrowband photometry. These data are sensitive to AGNs more luminous than L
X > 2 × 1043 erg s−1 in the rest-frame hard X-ray band (2–10 keV). We have identified two X-ray AGNs at the redshift of USS 1558−003, one of which is the radio galaxy. We have determined that

of the Hα emitters in the protocluster are X-ray AGNs. Unlike most other high-redshift cluster progenitors studied with similar techniques, USS 1558−003 does not have a significantly higher fraction of AGNs than field galaxies at similar redshifts. This lower AGN fraction is inconsistent with the expectation that the higher gas fractions at high redshift, combined with the high galaxy densities and modest relative velocities in protoclusters, should produce higher AGN fractions.
Rapid “Turn-on” of Type-1 AGN in a Quiescent Early-type Galaxy SDSS1115+0544
Authors: Yan Lin , Wang Tinggui , Jiang Ning , Stern Daniel , Dou Liming , Fremling C. , Graham M. J. , Drake A. J. , Yang Chenwei , Burdge K. , Kasliwal M. M. 
Published: March 2019

Abstract
We present a detailed study of a transient in the center of SDSS1115+0544 based on the extensive UV, optical, mid-IR light curves (LCs) and spectra over 1200 days. The host galaxy is a quiescent early-type galaxy at z = 0.0899 with a black hole mass of 2 × 107
M
⊙. The transient underwent a 2.5 mag brightening over ∼120 days, reaching a peak V-band luminosity (extinction corrected) of −20.9 mag, then fading 0.5 mag over 200 days, settling into a plateau of >600 days. Following the optical brightening are the significant mid-IR flares at 3.4 and 4.5 μm, with a peak time delay of ∼180 days. The mid-IR LCs are explained as the echo of UV photons by a dust medium with a radius of 5 × 1017 cm, consistent with E(B − V) of 0.58 inferred from the spectra. This event is very energetic with an extinction corrected L
bol ∼ 4 × 1044 erg s−1. Optical spectra over 400 days in the plateau phase revealed newly formed broad Hα, β emission with a FWHM of ∼3750 km s−1 and narrow coronal lines such as [Fe vii], [Ne v]. This flare also has a steeply rising UV continuum, detected by multi-epoch Swift data at +700 to +900 days post optical peak. The broad Balmer lines and the UV continuum do not show significant temporal variations. The slow evolving LCs over 1200 days, the constant Balmer lines, and UV continuum at late times rule out tidal disruption event and SN IIn as the physical model for this event. We propose that this event is a “turn-on” AGN, transitioning from a quiescent state to a type-1 AGN with a sub-Eddington accretion rate of 0.017 M
⊙ yr−1. This change occurred on a very short timescale of ∼120–200 days. The discovery of such a rapid “turn-on” AGN poses challenges to accretion disk theories and suggests more future detections of similar events.
Neutral Gas Properties and Lyα Escape in Extreme Green Pea Galaxies∗
Authors: McKinney Jed H. , Jaskot Anne E. , Oey M. S. , Yun Min S. , Dowd Tara , Lowenthal James D. 
Published: March 2019

Abstract
Mechanisms regulating the escape of Lyα photons and ionizing radiation remain poorly understood. To study these processes, we analyze Very Large Array 21 cm observations of one Green Pea (GP), J160810+352809 (hereafter J1608), and Hubble Space Telescope Cosmic Origins Spectrograph (COS) spectra of 17 GP galaxies at

. All are highly ionized: J1608 has the highest [O iii] λ5007/[O ii] λ3727 for star-forming galaxies in Sloan Digital Sky Survey, and the 17 GPs have [O iii]/[O
ii] ≥ 6.6. We set an upper limit on J1608's H i mass of

, near or below average compared to similar-mass dwarf galaxies. In the COS sample, eight GPs show Lyα absorption components, six of which also have Lyα emission. The H i column densities derived from Lyα absorption are high,

cm−2 = 19–21, well above the LyC optically thick limit. Using low-ionization absorption lines, we measure covering fractions (

) of 0.1–1 and find that

strongly anticorrelates with Lyα escape fraction. Low covering fractions may facilitate Lyα and LyC escape through dense neutral regions. GPs with

all have low neutral gas velocities, while GPs with lower

have a larger range of velocities. Conventional mechanical feedback may help establish low

in some cases, whereas other processes may be important for GPs with low velocities. Finally, we compare

with proposed indicators of LyC escape. Ionizing photon escape likely depends on a combination of neutral gas geometry and kinematics, complicating the use of emission-line diagnostics for identifying LyC emitters.
NOISE LEVELS OF ORTHOPEDIC INSTRUMENTS AND THEIR POTENTIAL HEALTH RISKS
Authors: Holmes George B , Goodman Kathy Landau , Hang David W , McCorvey V Monique 
Published: March 2019

ABSTRACT
Exposure to intense levels of noise has been identified as a potential workplace risk for the development of hearing impairment for health care workers. With this knowledge a noise level survey was performed on selected orthopedic equipment. Several instruments produced threshold levels of 95 dBA to 106 dBA. Often these levels remained as high as 90 dBA at 4 ft from the source. Based on the results of this survey, audiometric tests were conducted on five cast technicians to determine the prevalence of noise-induced hearing loss (NIHL). Audiometric measurements of the cast technicians indicated that, in the absence of other risk factors for hearing loss, there was an association between the presence of NIHL and the years of exposure. NIHL was most evident on the side of the dominant hand used for holding the cast cutter. These findings suggest there may be a risk of NIHL from the occupational exposure to various orthopedic instruments. Further, this level of risk may warrant the use of an individual hearing protection device or the development of quieter instruments.
High-Dimensional Characterization of IL-10 Production and IL-10–Dependent Regulation during Primary Gammaherpesvirus Infection
Authors: Kimball Abigail K , Oko Lauren M , Kaspar Rachael E , van Dyk Linda F , Clambey Eric T 
Published: March 2019

Abstract
IL-10 is a potent immunomodulatory cytokine produced by multiple cell types to restrain immune activation. Many herpesviruses use the IL-10 pathway to facilitate infection, but how endogenous IL-10 is regulated during primary infection in vivo remains poorly characterized. In this study, we infected mice with murine gammaherpesvirus 68 (γHV68) and analyzed the production and genetic contribution of IL-10 by mass cytometry (cytometry by time-of-flight) analysis. γHV68 infection elicited a breadth of effector CD4 T cells in the lungs of acutely infected mice, including a highly activated effector subset that coexpressed IFN-γ, TNF-α, and IL-10. By using IL-10 GFP transcriptional reporter mice, we identified that IL-10 was primarily expressed within CD4 T cells during acute infection in the lungs. IL10gfp-expressing CD4 T cells were highly proliferative and characterized by the expression of multiple coinhibitory receptors, including PD-1 and LAG-3. When we analyzed acute γHV68 infection of IL-10–deficient mice, we found that IL-10 limits the frequency of both myeloid and effector CD4 T cell subsets in the infected lung, with minimal changes at a distant mucosal site. These data emphasize the unique insights that high-dimensional analysis can afford in investigating antiviral immunity and provide new insights into the breadth, phenotype, and function of IL-10–expressing effector CD4 T cells during acute virus infection.
Análisis de redes sociales mediante cadenas de Markov
Authors: Carreño Sanchez Amanda , Sanabria Codesal Esther 
Published: March 2019

<p>El objetivo de este trabajo es mostrar un modelo matemático sencillo, aplicado al análisis de las redes sociales, que potencie el interés de los alumnos en la asignatura Matemáticas I. El planteamiento y la resolución de este modelo, basado en las cadenas de Markov, nos permiten ilustrar la aplicabilidad los sistemas de ecuaciones discretas y reforzar los conceptos de autovalores, autovectores y diagonalización. Utilizaremos el software de cálculo Mathematica, al que tienen acceso los estudiantes de la asignatura, para resolver el problema, lo que facilitará trabajar con diversos modelos y dimensiones grandes.</p>
Constructing a data-driven receptor model for organic and inorganic aerosol – a synthesis analysis of eight mass spectrometric data sets from a boreal forest site
Authors: Äijälä Mikko , Daellenbach Kaspar R. , Canonaco Francesco , Heikkinen Liine , Junninen Heikki , Petäjä Tuukka , Kulmala Markku , Prévôt André S. H. , Ehn Mikael 
Published: March 2019

Abstract. The interactions between organic and
inorganic aerosol chemical components are integral to understanding and
modelling climate and health-relevant aerosol physicochemical properties,
such as volatility, hygroscopicity, light scattering and toxicity. This study
presents a synthesis analysis for eight data sets, of non-refractory aerosol
composition, measured at a boreal forest site. The measurements, performed
with an aerosol mass spectrometer, cover in total around 9 months over the
course of 3 years. In our statistical analysis, we use the complete organic
and inorganic unit-resolution mass spectra, as opposed to the more common
approach of only including the organic fraction. The analysis is based on
iterative, combined use of (1) data reduction, (2) classification and
(3) scaling tools, producing a data-driven chemical mass balance type of
model capable of describing site-specific aerosol composition. The receptor
model we constructed was able to explain 83±8 % of variation in
data, which increased to 96±3 % when signals from low
signal-to-noise variables were not considered. The resulting interpretation
of an extensive set of aerosol mass spectrometric data infers seven distinct
aerosol chemical components for a rural boreal forest site: ammonium sulfate
(35±7 % of mass), low and semi-volatile oxidised organic aerosols
(27±8 % and 12±7 %), biomass burning organic aerosol (11±7 %), a nitrate-containing organic aerosol type (7±2 %),
ammonium nitrate (5±2 %), and hydrocarbon-like organic aerosol (3±1 %). Some of the additionally observed, rare outlier aerosol types
likely emerge due to surface ionisation effects and likely represent amine
compounds from an unknown source and alkaline metals from emissions of a
nearby district heating plant. Compared to traditional, ion-balance-based
inorganics apportionment schemes for aerosol mass spectrometer data, our
statistics-based method provides an improved, more robust approach, yielding
readily useful information for the modelling of submicron atmospheric
aerosols physical and chemical properties. The results also shed light on the
division between organic and inorganic aerosol types and dynamics of salt
formation in aerosol. Equally importantly, the combined methodology
exemplifies an iterative analysis, using consequent analysis steps by a
combination of statistical methods. Such an approach offers new ways to home
in on physicochemically sensible solutions with minimal need for a priori
information or analyst interference. We therefore suggest that similar
statistics-based approaches offer significant potential for un- or semi-supervised machine-learning applications in future analyses of aerosol
mass spectrometric data.