bluuebunny/crossref_metadata_2025_split huggingface dataset:
La contabilidad un elemento indispensable en el desarrollo de las empresas
Authors: Morales Espinoza Dina Yolanda , Morales Espinosa Judith  María 
Published: April 2019

Este artículo tuvo como objetivo explicar sobre el estudio de la contabilidad como un elemento indispensable en el desarrollo de las empresas, es de conocimiento general que desde tiempos muy remotos las organizaciones han necesitado de la contabilidad para su eficiente desenvolvimiento empresarial. Dentro del alcance de la investigación se estableció un manejo adecuado de la contabilidad con el fin de que les permita a las empresas una correcta toma de decisiones y así asegurar la permanencia de las empresas a largo plazo.
En cuanto a la metodología se utilizó el enfoque de tipo participativa, cualitativa, exploratoria y descriptiva, en donde se manejó el razonamiento para obtener conclusiones que partieron de hechos aceptados como válidos, y así llegar a las conclusiones generales. Para realizar el sondeo de la información se utilizó dos técnicas: la técnica de observación en las empresas privadas y la realización de encuestas a diez directivos representantes de la Cámara de Comercio de la ciudad de Loja.
En los resultados se hizo mención a la información obtenida de los actores involucrados en la investigación, quienes aludieron a la importancia de la contabilidad para el desarrollo de las empresas, pues la consideran un pilar fundamental en la gerencia de las empresas que refleja el fruto de la toma de decisiones de los administradores, así como un excelente referente de información financiera para predecir el futuro de las empresas.
Finalmente se concluyó que para que una empresa funcione eficientemente es necesario un esfuerzo en conjunto de los directivos y subordinados. Es así, que en las empresas la contabilidad es una herramienta importante e indispensable para su desarrollo, sin embargo, en la actualidad muchos empresarios no reconocen estas ventajas y no le dan importancia que merece a la contabilidad.
Properties of the Bare Nucleus of Comet 96P/Machholz 1*
Authors: Eisner N. L. , Knight M. M. , Snodgrass C. , Kelley M. S. P. , Fitzsimmons A. , Kokotanekova R. 
Published: April 2019

Abstract
We observed comet 96P/Machholz 1 on a total of nine nights before and after perihelion during its 2017/2018 apparition. Both its unusually small perihelion distance and the observed fragmentation during multiple apparitions make 96P an object of great interest. Our observations show no evidence of a detectable dust coma, implying that we are observing a bare nucleus at distances ranging from 2.3 to 3.8 au. Based on this assumption, we calculated its color and found average values of g′–r′ = 0.50 ± 0.04, r′–i′ = 0.17 ± 0.03, and i′–z′ = 0.06 ± 0.04. These are notably more blue than those of the nuclei of other Jupiter-family and long-period comets. Furthermore, assuming a bare nucleus, we found an equivalent nuclear radius of 3.4 ± 0.2 km with an axial ratio of at least 1.6 ± 0.1. The lightcurve clearly displays one large peak, one broad flat peak, and two distinct troughs, with a clear asymmetry that suggests that the shape of the nucleus deviates from that of a simple triaxial ellipsoid. This asymmetry in the lightcurve allowed us to constrain the nuclear rotation period to 4.10 ± 0.03 hr and 4.096 ± 0.002 hr before and after perihelion, respectively. Within the uncertainties, 96P’s rotation period does not appear to have changed throughout the apparition, and we conclude a maximum possible change in rotation period of 130 s. The observed properties were compared to those of comet 322P and interstellar object 1I/‘Oumuamua in an attempt to study the effects of close perihelion passages on cometary surfaces and their internal structure and the potential interstellar origin of 96P.
An Updated Model for Circumbinary Planets Orbiting the sdB Binary NY Virginis
Authors: Song Shuo , Mai Xinyu , Mutel Robert L. , Pulley David , Faillace George , Watkins Americo 
Published: April 2019

Abstract
We report 18 new primary minima timing observations of the short-period eclipsing binary system NY Virginis. We combined these minima with previously published primary minima to update circumbinary exoplanet models in this system based on O − C timing variations. We performed a nonlinear least-squares minimization search using a quadratic ephemeris and either one or two exoplanets. The only model with an acceptable fit includes a period derivative

and two planets in eccentric orbits e = 0.15, 0.15 with minimum masses of 2.7 and 5.5 Jovian masses. Analysis of the orbit stability shows that this solution is stable for at least 108 years, but a small increase in eccentricity (e ≥ 0.20) for either planet renders the orbits unstable in less than 106 years. A number of model parameters are significantly degenerate, so additional observations are required to determine planetary parameters with high statistical confidence.
Five Gas-rich Ultrafaint Dwarf Galaxy Candidates Discovered in WIYN Imaging of ALFALFA Sources
Authors: Janesh William , Rhode Katherine L. , Salzer John J. , Janowiecki Steven , Adams Elizabeth A. K. , Haynes Martha P. , Giovanelli Riccardo , Cannon John M. 
Published: April 2019

Abstract
We present results from the analysis of WIYN pODI imaging of 23 ultracompact high-velocity clouds (UCHVCs), which were identified in the ALFALFA H i survey as possible dwarf galaxies in or near the Local Group. To search for a resolved stellar population associated with the H i gas in these objects, we carried out a series of steps designed to identify stellar overdensities in our optical images. We identify five objects that are likely stellar counterparts to the UCHVCs, at distances of ∼350 kpc to ∼1.6 Mpc. Two of the counterparts were already described in Janesh et al.; the estimated distance and detection significance for one of them changed in the final analysis of the full pODI data set. At their estimated distances, the detected objects have H i masses from 2 × 104 to 3 × 106
M
⊙, M

V
from −1.4 to −7.1, and stellar masses from 4 × 102 to 4 × 105
M
⊙. None of the objects shows evidence of a young stellar population. Their properties would make the UCHVCs some of the most extreme objects in and around the Local Group, comparable to ultrafaint dwarf galaxies in their stellar populations, but with significant gas content. Such objects probe the extreme end of the galaxy mass function and provide a test bed for theories regarding the baryonic feedback processes that impact star formation and galaxy evolution in this low-mass regime.
Sub-band Image Reconstruction Using Differential Chromatic Refraction
Authors: Lee Matthias A. , Budavári Tamás , Sullivan Ian S. , Connolly Andrew J. 
Published: April 2019

Abstract
Refraction by the atmosphere causes the positions of sources to depend on the airmass through which an observation was taken. This shift is dependent on the underlying spectral energy of the source and the filter or bandpass through which it is observed. Wavelength-dependent refraction within a single passband is often referred to as differential chromatic refraction (DCR). With a new generation of astronomical surveys undertaking repeated observations of the same part of the sky over a range of different airmasses and parallactic angles, DCR should be a detectable and measurable astrometric signal. In this paper we introduce a novel procedure that takes this astrometric signal and uses it to infer the underlying spectral energy distribution of a source; we solve for multiple latent images at specific wavelengths via a generalized deconvolution procedure built on robust statistics. We demonstrate the utility of such an approach for estimating a partially deconvolved image, at higher spectral resolution than the input images, for surveys such as the Large Synoptic Survey Telescope.
Evidence for Super-Alfvénic Oscillations in Solar Type III Radio Burst Sources
Authors: Mohan Atul , Mondal Surajit , Oberoi Divya , Lonsdale Colin J. 
Published: April 2019

Abstract
At the site of their origin, solar meter-wave radio bursts contain pristine information about the local coronal magnetic field and plasma parameters. On its way through the turbulent corona, this radiation gets substantially modified due to propagation effects. Effectively disentangling the intrinsic variations in emission from propagation effects has remained a challenge. We demonstrate a way to achieve this using a snapshot spectroscopic imaging study of weak type III bursts using data from the Murchison Widefield Array. Using this study, we present the first observational evidence for second-scale quasi-periodic oscillations (QPOs) in burst source sizes and orientation with simultaneous QPOs in intensity. The observed oscillations in source sizes are so fast and large that they require two orders of magnitude larger Alfvén speed than the typical local value of 0.5 Mm s−1 at the burst generation heights, if interpreted within an MHD framework. These observations imply the presence of a quasi-periodic regulation mechanism operating at the particle injection site, modulating the geometry of energetic electron beams that generate type III bursts. In addition, we introduce a method to characterize plasma turbulence in the mid-coronal ranges. We also detect evidence for a systematic drift in the location of the burst sources superposed on the random jitter induced by scattering. We interpret this as the motion of the open flux tube within which the energetic electron beams travel.
Application of Clumpy Torus Model to Broadband X-Ray Spectra of Two Seyfert 1 Galaxies: IC 4329A and NGC 7469
Authors: Ogawa Shoji , Ueda Yoshihiro , Yamada Satoshi , Tanimoto Atsushi , Kawaguchi Toshihiro 
Published: April 2019

Abstract
We apply a new X-ray clumpy torus model, XCLUMPY, in which the clump distribution is assumed to be the same as that in the infrared clumpy torus model (CLUMPY) by Nenkova et al., to the broadband X-ray spectra of type-1 active galactic nuclei (AGNs) for the first time. We analyze the archival data of IC 4329A and NGC 7469 observed with NuSTAR/Suzaku and NuSTAR/XMM-Newton, respectively, whose infrared spectra were studied with CLUMPY by Ichikawa et al. and optical extinctions (A
V) of the tori were estimated. We consider two models, invoking (Model 1) a relativistic reflection component from the accretion disk and (Model 2) a partial absorber. Assuming that the narrow Fe Kα emission line at 6.4 keV originates from the torus, we separate the contribution of the torus reflection components in the total spectra. Our models yield equatorial hydrogen column densities of the tori to be

(0.53–1.43) × 1023 cm−2 and

(0.84–1.43) × 1024 cm−2, for IC 4329A and NGC 7469, respectively. We find that the N
H/A
V ratios in the tori are by factors of 25–68 (IC 4329A) and 2.4–3.9 (NGC 7469) smaller than that in the Galactic interstellar medium (ISM). These results suggest that a non-negligible fraction of AGNs are “dust-rich” compared with the Galactic ISM, as opposite to the general trend previously reported in many obscured AGNs.
Comparison of Gaia DR2 Parallaxes of Stars with VLBI Astrometry
Authors: Xu 徐 Shuangjing 双敬 , Zhang 张 Bo 波 , Reid Mark J. , Zheng 郑 Xingwu 兴武 , Wang 王 Guangli 广利 
Published: April 2019

Abstract
We compare the parallaxes of stars from VLBI astrometry in the literature to those in the Gaia DR2 catalog. Our full sample contains young stellar objects, evolved AGB stars, pulsars, and other radio stars. Excluding AGB stars, which show significant discrepancies between Gaia and VLBI parallaxes, and stars in binary systems, we obtain an average, systematic, parallax offset of −75 ± 29 μas for Gaia DR2, consistent with their estimate of a parallax zero-point between −100 and 0 μas.
MMS Observations of Kinetic-size Magnetic Holes in the Terrestrial Magnetotail Plasma Sheet
Authors: Huang S. Y. , He L. H. , Yuan Z. G. , Sahraoui F. , Contel O. Le , Deng X. H. , Zhou M. , Fu H. S. , Jiang K. , Yu X. D. , Li H. M. , Deng D. , Pollock C. J. , Torbert R. B. , Burch J. L. 
Published: April 2019

Abstract
Kinetic-size magnetic holes (KSMHs) in the terrestrial magnetotail plasma sheet are statistically investigated using the observations from the Magnetospheric Multiscale mission. The scales of KSMHs are found to be smaller than one ion gyroradius or tens of electron gyroradii. The occurrence distributions of KSMHs have dawn–dusk asymmetry (duskside preference) in the magnetotail, which may be caused by the Hall effect. Most events of KSMHs (71.7%) are accompanied by a substorm, implying that substorms may provide favorable conditions for the excitation of KSMHs. However, there is a weak correlation between KSMHs and magnetic reconnection. The statistical results reveal that for most of the events, the electron total temperature and perpendicular temperature increase while the electron parallel temperature decreases inside the KSMHs. The electron temperature anisotropy (T
e⊥/

) is observed in 72% of KSMHs. Whistler-mode waves are frequently observed inside the KSMHs, and most (92%) KSMHs associated with whistler waves have enhancements of electron perpendicular distributions and satisfy the unstable condition of whistler instability. This suggests that the observed electron-scale whistler waves, locally generated by the electron temperature anisotropy, could couple with the electron-scale KSMHs. The observed features of KSMHs and their coupling to electron-scale whistlers are similar to the ones in the turbulent magnetosheath, implying that they are ubiquitous in the space plasmas. The generation of KSMHs in the plasma sheet could be explained by an electron vortex magnetic hole, magnetosonic solitons, and/or ballooning/interchange instabilities.
Four Metal-poor Stars in the Sagittarius Dwarf Spheroidal Galaxy∗
Authors: Chiti Anirudh , Frebel Anna 
Published: April 2019

Abstract
We present the metallicities and carbon abundances of four newly discovered metal-poor stars with −2.2 < [Fe/H] < −1.6 in the Sagittarius dwarf spheroidal galaxy. These stars were selected as metal-poor member candidates using a combination of public photometry from the SkyMapper Southern Sky Survey and proper-motion data from the second data release from the Gaia mission. The SkyMapper filters include a metallicity-sensitive narrowband v filter centered on the Ca ii K line, which we use to identify metal-poor candidates. In tandem, we use proper-motion data to remove metal-poor stars that are not velocity members of the Sagittarius dwarf spheroidal galaxy. We find that these two data sets allow for efficient identification of metal-poor members of the Sagittarius dwarf galaxy to follow up with further spectroscopic study. Two of the stars we present have [Fe/H] < −2.0, which adds to the few other such stars currently identified in the Sagittarius dwarf galaxy that are likely not associated with the globular cluster M54, which resides in the nucleus of the system. Our results confirm that there exists a very metal-poor stellar population in the Sagittarius dwarf galaxy. We find that none of our stars can be classified as carbon-enhanced metal-poor stars. Efficiently identifying members of this population will be helpful to further our understanding of the early chemical evolution of the system.
The Evolution of the He ii-ionizing Background at Redshifts 2.3 < z < 3.8 Inferred from a Statistical Sample of 24 HST/COS He ii Lyα Absorption Spectra*
Authors: Worseck Gábor , Davies Frederick B. , Hennawi Joseph F. , Prochaska J. Xavier 
Published: April 2019

Abstract
We present measurements of the large-scale (≈40 comoving Mpc) effective optical depth of He ii Lyα absorption,

, at 2.54 < z < 3.86 toward 16 He ii-transparent quasars observed with the Cosmic Origins Spectrograph on the Hubble Space Telescope, to characterize the ionization state of helium in the intergalactic medium (IGM). We provide the first statistical sample of

measurements in six signal-to-noise ratio ≳3 He ii sightlines at z > 3.5, and study the redshift evolution and sightline-to-sightline variance of

in 24 He ii sightlines. We confirm an increase of the median

from ≃2 at z = 2.7 to

at z > 3, and a scatter in

that increases with redshift. The z > 3.5 He ii absorption is predominantly saturated, but isolated narrow (Δv < 650 km s−1) transmission spikes indicate patches of reionized helium. We compare our measurements to predictions for a range of UV background models applied to outputs of a large-volume (146 comoving Mpc)3 hydrodynamical simulation by forward-modeling our sample’s quality and size. At z > 2.74, the variance in

significantly exceeds expectations for a spatially uniform UV background, but is consistent with a fluctuating radiation field sourced by variations in the quasar number density and the mean free path in the post-reionization IGM. We develop a method to infer the approximate median He ii photoionization rate

of a fluctuating UV background from the median

, finding a factor ≃5 decrease in

between z ≃ 2.6 and z ≃ 3.1. At z ≃ 3.1,

s−1 corresponds to a median He ii fraction of ≃2.5%, indicating that our data probe the tail end of He ii reionization.
Nonequilibrium Ionization States within Galactic Outflows: Explaining Their O vi and N v Column Densities
Authors: Gray William J. , Scannapieco Evan , Lehnert Matthew D. 
Published: April 2019

Abstract
We present a suite of one-dimensional spherically symmetric hydrodynamic simulations that study the atomic ionization structure of galactic outflows. We track the ionization state of the outflowing gas with a nonequilibrium atomic chemistry network that includes photoionization, photoheating, and ion-by-ion cooling. Each simulation describes a steady-state outflow that is defined by its mass and energy input rates, sonic radius, metallicity, and UV flux from both the host galaxy and metagalactic background. We find that for a large range of parameter choices, the ionization state of the material departs strongly from what it would be in photoionization equilibrium, in conflict with what is commonly assumed in the analysis of observations. In addition, nearly all the models reproduce the low N v to O vi column density ratios and the relatively high O vi column densities that are observed.
Extended Radio Structures and a Compact X-Ray Cool-core in the Cluster Source PKS 1353–341
Authors: Cheung C. C. , Giacintucci Simona , Clarke T. E. 
Published: April 2019

Abstract
We present a radio and X-ray study of PKS 1353–341, the brightest cluster galaxy radio source at the center of a recent Chandra-discovered X-ray cluster. Our multi-frequency Very Large Array images reveal an edge-brightened (FR-II), double-lobed structure with a total ∼50 kpc extent, and 1.5 GHz power of 1.2 × 1025 W Hz−1, separated from the bright, arcsecond-scale core. We reanalyzed the Chandra data and found that the X-ray-emitting active galactic nucleus (AGN) is offset by ∼9 kpc from a compact X-ray cool-core with temperature kT = 3.1 ± 0.5 keV, and a radius of ∼22 kpc, surrounded by a hotter kT = 6.3 ± 0.7 keV gas out to ∼50 kpc. The offset suggests sloshing inside the cool-core induced by a minor merger or a past outburst of the AGN that produced large-scale radio lobes. The comparable spatial scales of the lobes with the interface between the different temperature X-ray plasmas indicate the lobes are actively heating the outer layers of what is now a remnant compact cool-core. Our dual-frequency Very Long Baseline Array (VLBA) images reveal substructure in the central radio source, consisting of a radio core with double-sided parsec-scale jets pointing toward the kiloparsec-scale structures. The northern jet is detected only at 8.4 GHz, indicating its emission is behind an absorbing torus or disk. We also measured faster apparent motions in the southern jet up to 1.9 ± 1.1c than in the northern jet (0.8 ± 0.5c). While the VLBA observations indicate the southern jet is aligned slightly closer to our line of sight, the asymmetries are overall modest and imply minimal projection effects in the large-scale radio structures.
XMM-Newton and Chandra Observations of the Unidentified Fermi-LAT Source 3FGL J1016.5–6034: A Young Pulsar with a Nebula?
Authors: Hare Jeremy , Volkov Igor , Kargaltsev Oleg , Younes George , Rangelov Blagoy 
Published: April 2019

Abstract
We report the discovery of a bright X-ray source in the XMM-Newton and Chandra X-Ray Observatory (Chandra) images of the unidentified Fermi-LAT source 3FGL J1016.5–6034. The XMM-Newton spectrum of the source is well fit by an absorbed blackbody+power-law model with a temperature kT = 0.20 ± 0.02 keV and photon index Γ = 1.8 ± 0.1. Chandra resolves the same source into a point source (CXOU J101546.0–602939) and a surrounding compact nebula seen up to about 30″ from the point source. The Chandra spectrum of the nebula can be described by an absorbed power law with Γ = 1.7 ± 0.3 and is partly responsible for the nonthermal emission observed in the XMM-Newton spectrum. The XMM-Newton images also reveal faint extended emission on arcminute scales. These properties strongly suggest that the X-ray source and the accompanying extended emission are a newly discovered young pulsar with a pulsar wind nebula. We also analyze ∼10 yr of Fermi-LAT data and find that the improved LAT source localization is consistent with the position of CXOU J101546.0–602939.
Electron Acceleration by ICME-driven Shocks at 1 au
Authors: Yang Liu , Wang Linghua , Li Gang , Wimmer-Schweingruber Robert F. , He Jiansen , Tu Chuanyi , Tian Hui , Bale Stuart D. 
Published: April 2019

Abstract
We present a comprehensive study of in situ electron acceleration during 74 shocks driven by interplanetary coronal mass ejections (ICMEs) with good suprathermal electron observations by the Wind 3DP instrument at 1 au from 1995 through 2014. Among the selected 59 quasi-perpendicular (15 quasi-parallel) shock cases, ∼86% (∼60%), ∼62% (∼36%), and ∼17% (∼7%) show significant electron flux enhancements of J

D
/J

A
> 1.5 across the shock, respectively at 0.43, 1.95, and 40 keV, where J

D
and J

A
are the electron flux in the shock’s downstream and the preceding ambient solar wind. For significantly shocked suprathermal electrons, the differential flux J

D
positively correlates most with the magnetosonic Mach number M

s
, while the flux enhancement J

D
/J

A
positively correlates most with the magnetic compression ratio r

B
, among the shock parameters. Both J

D
and J

A
generally fit well to a double-power-law spectrum at ∼0.4–100 keV, J ∝ E
−β
, with an index of β
1 ∼ 2–6 below a break energy of E
br (which is typically ∼2 keV) and an index of β
2 ∼ 2.0–3.2 at energies above.

is similar to

in all the shock cases, while

is similar to (larger than)

in ∼60% (∼40%) of the shock cases with significant electron enhancements. Furthermore, J

D
/J

A
mostly peaks in the directions perpendicular to the interplanetary magnetic field at ∼0.4–50 keV. These results suggest that both quasi-parallel and quasi-perpendicular shocks accelerate electrons in situ at 1 au mainly via shock drift acceleration, with an acceleration efficiency probably affected by the induced electric field at the shock surface.