bluuebunny/crossref_metadata_2025_split huggingface dataset:
AstroSat/LAXPC Detection of Millisecond Phenomena in 4U 1728-34
Authors: Chauhan Jai Verdhan , Yadav J S , Misra Ranjeev , Agrawal P C , Antia H M , Pahari Mayukh , Sridhar Navin , Dedhia Dhiraj , Katoch Tilak , Madhwani P. , Manchanda R K , Paul B , Shah Parag 
Published: May 2017

Abstract
The low-mass X-ray binary 4U 1728-24 was observed with AstroSat/LAXPC on 2016 March 8th. Data from a randomly chosen orbit of over 3 ks was analyzed for detection of rapid intensity variations. We found that the source intensity was nearly steady but, toward the end of the observation, a typical Type-1 burst was detected. Dynamical power spectrum of the data in the 3–20 keV band, reveals the presence of a kHz Quasi-Periodic Oscillation (QPO) for which the frequency drifted from ∼815 Hz at the beginning of the observation to about 850 Hz just before the burst. The QPO is also detected in the 10–20 keV band, which was not obtainable by earlier RXTE observations of this source. Even for such a short observation with a drifting QPO frequency, the time lag between the 5–10 and 10–20 keV bands can be constrained to be less than 100 microseconds. The Type-1 burst that lasted for about 20 s had a typical profile. During the first four seconds, dynamic power spectra reveal a burst oscillation for which the frequency increased from ∼361.5 to ∼363.5 Hz. This is consistent with the earlier results obtained with RXTE/PCA, showing the same spin frequency of the neutron star. The present results demonstrate the capability of the LAXPC instrument for detecting millisecond variability even from short observations. After RXTE ceased operation, LAXPC on AstroSat is the only instrument at present with the capability of detecting kHz QPOs and other kinds of rapid variations from 3 keV to 20 keV and possibly at higher energies as well.
Masses and Ages for 230,000 LAMOST Giants, via Their Carbon and Nitrogen Abundances
Authors: Ho Anna Y. Q. , Rix Hans-Walter , Ness Melissa K. , Hogg David W. , Liu Chao , Ting 丁 Yuan-Sen 源森 
Published: May 2017

Abstract
We measure carbon and nitrogen abundances to a precision of

dex for 450,000 giant stars from their low-resolution (

) LAMOST DR2 survey spectra. We use these

and

measurements, together with empirical relations based on the APOKASC sample, to infer stellar masses and implied ages for 230,000 of these objects to 0.08 dex and 0.2 dex respectively. We use The Cannon, a data-driven approach to spectral modeling, to construct a predictive model for LAMOST spectra. Our reference set comprises 8125 stars observed in common between the APOGEE and LAMOST surveys, taking seven APOGEE DR12 labels (parameters) as ground truth:

,

,

,

,

,

, and

. We add seven colors to the Cannon model, based on the g, r, i, J, H, K, W1, W2 magnitudes from APASS, 2MASS, and WISE, which improves our constraints on

and

by up to 20% and on

by up to 70%. Cross-validation of the model demonstrates that, for high-

objects, our inferred labels agree with the APOGEE values to within 50 K in temperature, 0.04 mag in

, and

dex in

,

,

,

, and

. We apply the model to 450,000 giants in LAMOST DR2 that have not been observed by APOGEE. This demonstrates that precise individual abundances can be measured from low-resolution spectra and represents the largest catalog to date of homogeneous stellar

,

, masses, and ages. As a result, we greatly increase the number and sky coverage of stars with mass and age estimates.
Hints on the Gradual Resizing of the Torus in AGNs through Decomposition of Spitzer/IRS Spectra
Authors: González-Martín Omaira , Masegosa Josefa , Hernán-Caballero Antonio , Márquez Isabel , Almeida Cristina Ramos , Alonso-Herrero Almudena , Aretxaga Itziar , Rodríguez-Espinosa José Miguel , Acosta-Pulido Jose Antonio , Hernández-García Lorena , Esparza-Arredondo Donaji , Martínez-Paredes Mariela , Bonfini Paolo , Pasetto Alice , Dultzin Deborah 
Published: May 2017

Abstract
Several authors have claimed that less luminous active galactic nuclei (AGNs) are not capable of sustaining a dusty torus structure. Thus, a gradual resizing of the torus is expected when the AGN luminosity decreases. Our aim is to examine mid-infrared observations of local AGNs of different luminosities for the gradual resizing and disappearance of the torus. We applied the decomposition method described by Hernán-Caballero et al. to a sample of ∼100 Spitzer/IRS spectra of low-luminosity AGNs and powerful Seyferts in order to decontaminate the torus component from other contributors. We have also included Starburst objects to ensure secure decomposition of the Spitzer/IRS spectra. We have used the affinity propagation (AP) method to cluster the data into five groups within the sample according to torus contribution to the 5–15 μm range (

) and bolometric luminosity (

). The AP groups show a progressively higher torus contribution and an increase of the bolometric luminosity from Group 1 (

and

) up to Group 5 (

and

). We have fitted the average spectra of each of the AP groups to clumpy models. The torus is no longer present in Group 1, supporting its disappearance at low luminosities. We were able to fit the average spectra for the torus component in Groups 3 (

and

), 4 (

and

), and 5 to Clumpy torus models. We did not find a good fitting to Clumpy torus models for Group 2 (

and

). This might suggest a different configuration and/or composition of the clouds for Group 2, which is consistent with the different gas content seen in Groups 1, 2, and 3, according to detections of

molecular lines. Groups 3, 4, and 5 show a trend of decreasing torus width (which leads to a likely decrease of the geometrical covering factor), although we cannot confirm it with the present data. Finally, Groups 3, 4, and 5 show an increase of the outer radius of the torus for higher luminosities, consistent with a resizing of the torus according to AGN luminosity.
Collisions between Sintered Icy Aggregates
Authors: Sirono Sin-iti , Ueno Haruta 
Published: May 2017

Abstract
Collisions between sintered icy dust aggregates are numerically simulated. If the temperature of an icy aggregate is sufficiently high, sintering promotes molecular transport and a neck between adjacent grains grows. This growth changes the mechanical responses of the neck. We included this effect in a simulation code, and conducted collisional simulations. For porous aggregates, the critical velocity for growth, below which the mass of an aggregate increases, decreased from 50 m s−1 for the non-sintered case to 20 m s−1. For compacted aggregates, the main collisional outcome is bouncing. These results come from the fact that the strength of the neck is increased by sintering. The numerical results suggest that the collisional growth of icy grain aggregates is strongly affected by sintering.
An XMM-Newton and NuSTAR Study of IGR J18214-1318: A Non-pulsating High-mass X-Ray Binary with a Neutron Star
Authors: Fornasini Francesca M. , Tomsick John A. , Bachetti Matteo , Krivonos Roman A. , Fürst Felix , Natalucci Lorenzo , Pottschmidt Katja , Wilms Jörn 
Published: May 2017

Abstract
IGR J18214-1318, a Galactic source discovered by the International Gamma-Ray Astrophysics Laboratory, is a high-mass X-ray binary (HMXB) with a supergiant O-type stellar donor. We report on the XMM-Newton and NuSTAR observations that were undertaken to determine the nature of the compact object in this system. This source exhibits high levels of aperiodic variability, but no periodic pulsations are detected with a 90% confidence upper limit of 2% fractional rms between 0.00003–88 Hz, a frequency range that includes the typical pulse periods of neutron stars (NSs) in HMXBs (0.1–103 s). Although the lack of pulsations prevents us from definitively identifying the compact object in IGR J18214-1318, the presence of an exponential cutoff with e-folding energy

in its 0.3–79 keV spectrum strongly suggests that the compact object is an NS. The X-ray spectrum also shows a Fe Kα emission line and a soft excess, which can be accounted for by either a partial-covering absorber with

cm−2, which could be due to the inhomogeneous supergiant wind, or a blackbody component with

keV and

km, which may originate from NS hot spots. Although neither explanation for the soft excess can be excluded, the former is more consistent with the properties observed in other supergiant HMXBs. We compare IGR J18214-1318 to other HMXBs that lack pulsations or have long pulsation periods beyond the range covered by our observations.
Splashback Shells of Cold Dark Matter Halos
Authors: Mansfield Philip , Kravtsov Andrey V. , Diemer Benedikt 
Published: May 2017

Abstract
The density field in the outskirts of dark matter halos is discontinuous as a result of a caustic formed by matter at its first apocenter after infall. In this paper, we present an algorithm to identify the “splashback shell” formed by these apocenters in individual simulated halos using only a single snapshot of the density field. We implement this algorithm in the code Shellfish (SHELL Finding In Spheroidal Halos) and demonstrate that the code identifies splashback shells correctly and measures their properties with an accuracy of

for halos with more than 50,000 particles and mass accretion rates of

. Using Shellfish, we present the first estimates for several basic properties of individual splashback shells, such as radius,

, mass, and overdensity, and provide fits to the distribution of these quantities as functions of

,

, and

We confirm previous findings that

decreases with increasing

, but we show that, independent of accretion rate, it also decreases with increasing

. We also study the 3D structures of these shells and find that they generally have non-ellipsoidal oval shapes. We find that splashback radii estimated by Shellfish are 20%–30% larger than those estimated in previous studies from stacked density profiles at high accretion rates. We demonstrate that the latter are biased low owing to the contribution of high-mass subhalos to these profiles, and we show that using the median instead of mean density in each radial bin mitigates the effect of substructure on density profiles and removes the bias.
A Catalog of GALEX Ultraviolet Emission from Asymptotic Giant Branch Stars
Authors: Montez Rodolfo , Ramstedt Sofia , Kastner Joel H. , Vlemmings Wouter , Sanchez Enmanuel 
Published: May 2017

Abstract
We have performed a comprehensive study of the UV emission detected from asymptotic giant branch (AGB) stars by the Galaxy Evolution Explorer (GALEX). Of the 468 AGB stars in our sample, 316 were observed by GALEX. In the near-UV (NUV) bandpass (

), 179 AGB stars were detected and 137 were not detected. Only 38 AGB stars were detected in the far-UV (FUV) bandpass (

). We find that NUV emission is correlated with optical to near-infrared emission, leading to higher detection fractions among the brightest, and hence closest, AGB stars. Comparing the AGB time-variable visible phased light curves to corresponding GALEX NUV phased light curves, we find evidence that for some AGB stars the NUV emission varies in phase with the visible light curves. We also find evidence that the NUV emission and possibly the FUV emission are anticorrelated with the circumstellar envelope density. These results suggest that the origin of the GALEX-detected UV emission is an inherent characteristic of the AGB stars that can most likely be traced to a combination of photospheric and chromospheric emission. In most cases, UV detections of AGB stars are not likely to be indicative of the presence of binary companions.
Velocity Dispersion, Size, Sérsic Index, and Dn4000: The Scaling of Stellar Mass with Dynamical Mass for Quiescent Galaxies
Authors: Zahid H. Jabran , Geller Margaret J. 
Published: May 2017

Abstract
We examine the relation between stellar mass, velocity dispersion, size, Sérsic index, and

for a volume-limited sample of ∼40,000 quiescent galaxies in the SDSS. At a fixed stellar mass, galaxies with higher

have larger velocity dispersions and smaller sizes.

is a proxy for stellar population age, thus these trends suggest that older galaxies typically have larger velocity dispersions and smaller sizes. We combine velocity dispersion and size into a dynamical mass estimator,

. At a fixed stellar mass,

depends on

. The Sérsic index is also correlated with

. The dependence of

and Sérsic index on

suggests that quiescent galaxies are not structurally homologous systems. We derive an empirical correction for non-homology which is consistent with the analytical correction derived from the virial theorem. After accounting for non-homologous galactic structure, we measure

, where M
* is the stellar mass and M

d
is the dynamical mass derived from the velocity dispersion and size; stellar mass is directly proportional to dynamical mass. Quiescent galaxies appear to be in approximate virial equilibrium, and deviations of the fundamental plane parameters from the expected virial relation may result from mass-to-light ratio variations, selection effects, and the non-homology of quiescent galaxies. We infer the redshift evolution of velocity dispersion and size for galaxies in our sample assuming purely passive evolution. The inferred evolution is inconsistent with direct measurements at higher redshifts. Thus quiescent galaxies do not passively evolve. Quiescent galaxies have properties that are consistent with standard galaxy formation in ΛCDM. They form at different epochs and evolve modestly, increasing their size, velocity dispersion, and Sérsic index after they cease star formation.
Solar Tornadoes Triggered by Interaction between Filaments and EUV Jets
Authors: Chen Huadong , Zhang Jun , Ma Suli , Yan Xiaoli , Xue Jianchao 
Published: May 2017

Abstract
We investigate the formations and evolutions of two successive solar tornadoes in/near AR 12297 during 2015 March 19–20. Recurrent EUV jets close to two filaments were detected along a large-scale coronal loop prior to the appearances of the tornadoes. Under the disturbances from the activities, the filaments continually ascended and finally interacted with the loops tracked by the jets. Subsequently, the structures of the filaments and the loop were merged together, probably via magnetic reconnections, and formed tornado-like structures with a long spiral arm. Our observations suggest that solar tornadoes can be triggered by the interaction between filaments and nearby coronal jets, which has rarely been reported before. At the earlier development phase of the first tornado, about 30 small-scale sub-jets appeared in the tornado’s arm, accompanied by local EUV brightenings. They have an ejection direction approximately vertical to the axis of the arm and a typical maximum speed of ∼280 km s−1. During the ruinations of the two tornadoes, fast plasma outflows from the strong EUV brightenings inside tornadoes are observed, in company with the untangling or unwinding of the highly twisted tornado structures. These observational features indicate that self reconnections probably occurred between the tangled magnetic fields of the tornadoes and resulted in the rapid disintegrations and disappearances of the tornadoes. According to the reconnection theory, we also derive the field strength of the tornado core to be ∼8 G.
Node Verification to Join the Cloud Environment Using Third Party Verification Server
Authors: Aljammal Ashraf Hamdan , Bani-Salameh Hani , Alsarhan Ayoub , Kharabsheh Mohammad , Obiedat Mamoon 
Published: May 2017

<strong>Currently, cloud computing is facing different types of threats whether from inside or outside its environment. This may cause cloud to be crashed or at least unable to provide services to the requests made by clients. In this paper, a new technique is proposed to make sure that the new node which asks to join the cloud is not composing a threat on the cloud environment. Our new technique checks the node before it will be guaranteed to join the cloud whether it runs malwares or software that could be used to launch an attack. In this way the cloud will allow only the clean node to join it, eliminating the risk of some types of threats that could be caused by infected nodes.</strong>
Assessing the Effectiveness of Mobile Learning Devices in Tertiary Institutions: The Experience of Undergraduates in a Nigerian Private University
Authors: Odukoya Jonathan Adedayo , Adekeye Olajide , Okunlola Sola 
Published: May 2017

<em>Over the years, technology appears to be making life easier and better. However, in some instances, it appears technology is counterproductive. Mobile learning devices, as the name suggests, have been developed to facilitate learning on the move. The questions are: Are these devices truly facilitating learning? If they are truly facilitating learning, are they facilitating learning positively or negatively? To answer these questions, the survey research design was adopted on a sample of 215 randomly selected students. In the process, questionnaire and focused group discussion guideline were used to collect relevant data. Data analysis was both qualitative and quantitative. Some of the core findings from this investigation were that majority of the respondents, and by extension the target population, were barely using the tablets and free internet browsing megabytes [10Gb monthly] given to all students for the intended purpose of learning. Some were pre-occupied with downloading videos, films and music while some spend endless hours playing computer games or chatting on social networks with the attendant consequence of poor learning, dwindling academic performance and productivity. Relevant recommendations to redress this unwholesome trend were proffered</em>
Deaflympians' Satisfaction With Athletic Training Services at the 2013 Deaflympic Summer Games
Authors: Brancaleone Matthew Paul , Shingles René Revis , DeLellis Nailya 
Published: May 2017

Context: Athletic trainers have the opportunity to treat unique populations. Determining athletes' satisfaction with the athletic training services supplied can offer insights into how to improve the health care provided to athletes.Objective: To explore Deaflympians' satisfaction with athletic training services at the 2013 Deaflympic Summer Games.Design: Cross-sectional survey.Setting: The 2013 Deaflympic Summer Games in Sofia, Bulgaria.Patients or Other Participants: Of the 115 Deaflympians contacted, 55 completed the questionnaire, for a 48% response rate (women = 33, men = 22).Main Outcome Measure(s): The Medical Interview Satisfaction Survey–Athletic Training was used. The questionnaire gathered demographic data and included 25 Likert-scale items that assessed 6 components of athletic training. Descriptive statistics were calculated as normalized scores to adjust for the different numbers of questions for each item. On a 5-point scale, the scores ranged from 3.82 (management) to 4.24 (environment), with an overall satisfaction score of 3.89. We conducted comparison tests to assess possible differences in overall satisfaction and satisfaction components. Satisfaction with frequency of use of the athletic training room and knowledge were the only areas that showed statistically significant differences. Other differences were in perceptions of medical coverage among age groups and management between sexes.Results: Satisfaction with the athletic training services provided was lower among these Deaflympians than among collegiate athletes in other studies. However, we observed no differences in overall satisfaction scores by age, sex, race, previous Deaflympic experience, or individual or team sport. Deaflympians who used and visited the athletic training facility more often had higher overall satisfaction scores than individuals who used and visited the facility less.Conclusions: Deaflympians were satisfied with the athletic training services provided at the 2013 Deaflympic Summer Games.
The role of quantity surveyors in public–private partnerships in South Africa
Authors: Cruywagen Hoffie , Llale Josephine 
Published: May 2017

Background: Quantity surveyors play an important role in providing cost and contractual advice in the built environment. This article seeks to investigate the current extent of their involvement in public–private partnerships (PPPs) in South Africa.Aim: The study intends to establish factors that influence quantity surveyors’ participation in PPPs.Methodology: A mixed-methods research approach was followed by firstly conducting a survey amongst South African quantity surveyors in order to determine their level of participation in PPPs. For triangulation purposes, a case study was also conducted.Results: The results of the research show that, although quantity surveyors have the corresponding skills and competencies required in a PPP project, their current involvement in PPPs in South Africa is limited and that there is a greater role they can play in future.Conclusion: Quantity surveyors are uniquely positioned to play a bigger role in the implementation of PPPs in South Africa.
Digital preservation of cultural and scientific heritage: involving university students to raise awareness of its importance
Authors: Redweik Paula , Cláudio Ana Paula , Carmo Maria Beatriz , Naranjo José Manuel , Sanjosé José Juan 
Published: May 2017

<p>Cultural heritage is a relevant issue in contemporary society. While its preservation is a challenge, its dissemination, can contribute for an economic balance between costs and benefits. Scientific heritage can be considered as a special domain of cultural heritage, not yet sought by the mass tourism, but worth being preserved as the roots of today’s knowledge. Considering that university students of engineering and computer science traditionally do not address cultural or scientific heritage issues in their syllabus, and that they constitute a layer of young citizens that will come to be influential in the future of society, an effort was undertaken to focus on this theme in disciplines of different courses, allying the learning of technical skills with the natural interest of younger people for 3D and animation for the profit of heritage. The goal was to raise the awareness of this particular group to the importance of maintaining heritage issues, in particular, in a virtual way, both for documentation and for divulgating their existence. Raising funds for buildings’ restoration, attracting the public to visit buildings and collections that are outside the usual tourism routes, contributing to revenue generation, or allowing virtual visits of not accessible issues, complementing physical visits on site, were the general aims of the proposed projects. A survey was undertaken under the participating students to evaluate how the projects influenced their attitude towards heritage. The obtained feedback was very positive: 76% agreed that the project alerted them for the importance of preserving historical and cultural heritage, while 72% considered it was interesting that the topic of digital cultural heritage was used for the assessments of the disciplines.</p>