bluuebunny/crossref_metadata_2025_split huggingface dataset:
COSMIC REIONIZATION ON COMPUTERS. ULTRAVIOLET CONTINUUM SLOPES AND DUST OPACITIES IN HIGH REDSHIFT GALAXIES
Authors: Khakhaleva-Li Zimu , Gnedin Nickolay Y. 
Published: March 2016

ABSTRACT
We compare the properties of stellar populations of model galaxies from the Cosmic Reionization On Computers (CROC) project with the exiting ultraviolet (UV) and IR data. Since CROC simulations do not follow cosmic dust directly, we adopt two variants of the dust-follows-metals ansatz to populate model galaxies with dust. Using the dust radiative transfer code Hyperion, we compute synthetic stellar spectra, UV continuum slopes, and IR fluxes for simulated galaxies. We find that the simulation results generally match observational measurements, but, perhaps, not in full detail. The differences seem to indicate that our adopted dust-follows-metals ansatzes are not fully sufficient. While the discrepancies with the exiting data are marginal, the future James Webb Space Telescope (JWST) data will be of much higher precision, rendering highly significant any tentative difference between theory and observations. It is, therefore, likely, that in order to fully utilize the precision of JWST observations, fully dynamical modeling of dust formation, evolution, and destruction may be required.
GALAXY STRATEGY FOR LIGO-VIRGO GRAVITATIONAL WAVE COUNTERPART SEARCHES
Authors: Gehrels Neil , Cannizzo John K. , Kanner Jonah , Kasliwal Mansi M. , Nissanke Samaya , Singer Leo P. 
Published: March 2016

ABSTRACT
In this work we continue a line of inquiry begun in Kanner et al. which detailed a strategy for utilizing telescopes with narrow fields of view, such as the Swift X-ray Telescope (XRT), to localize gravitational wave (GW) triggers from LIGO/Virgo. If one considers the brightest galaxies that produce ∼50% of the light, then the number of galaxies inside typical GW error boxes will be several tens. We have found that this result applies both in the early years of Advanced LIGO when the range was small and the error boxes were large, and will apply in the later years when the error boxes will be small and the range will be large. This strategy has the beneficial property of reducing the number of telescope pointings by a factor of 10–100 compared with tiling the entire error box. Additional galaxy count reduction will come from a GW rapid distance estimate which will restrict the radial slice in search volume. Combining the bright galaxy strategy with a convolution based on anticipated GW localizations, we find that the searches can be restricted to about 18 ± 5 galaxies for 2015, about 23 ± 4 for 2017, and about 11 ± 2 for 2020. This assumes a distance localization at the putative neutron star–neutron star merger range μ for each target year, and these totals are integrated out to the range. Integrating out to the horizon would roughly double the totals. For localizations with

the totals would decrease. The galaxy strategy we present in this work will enable numerous sensitive optical and XRTs with small fields of view to participate meaningfully in searches wherein the prospects for rapidly fading afterglow place a premium on a fast response time.
MODELING SEVEN YEARS OF EVENT HORIZON TELESCOPE OBSERVATIONS WITH RADIATIVELY INEFFICIENT ACCRETION FLOW MODELS
Authors: Broderick Avery E. , Fish Vincent L. , Johnson Michael D. , Rosenfeld Katherine , Wang Carlos , Doeleman Sheperd S. , Akiyama Kazunori , Johannsen Tim , Roy Alan L. 
Published: March 2016

ABSTRACT
An initial three-station version of the Event Horizon Telescope, a millimeter-wavelength very-long baseline interferometer, has observed Sagittarius A* (Sgr A*) repeatedly from 2007 to 2013, resulting in the measurement of a variety of interferometric quantities. Of particular importance is that there is now a large set of closure phases measured over a number of independent observing epochs. We analyze these observations within the context of a realization of semi-analytic radiatively inefficient disk models, implicated by the low luminosity of Sgr A*. We find a broad consistency among the various observing epochs and between different interferometric data types, with the latter providing significant support for this class of model of Sgr A*. The new data significantly tighten existing constraints on the spin magnitude and its orientation within this model context, finding a spin magnitude of

a
=

0.10

−
0.10
−
0.10

+
0.30
+
0.56

, an inclination with respect to the line of sight of

θ
=

60
°

−

8

°

−

13

°

+

5

°

+

10

°

, and a position angle of

ξ
=

156
°

−

17

°

−

27

°

+

10

°

+

14

°

east of north. These are in good agreement with previous analyses. Notably, the previous 180° degeneracy in the position angle has now been conclusively broken by the inclusion of the closure-phase measurements. A reflection degeneracy in the inclination remains, permitting two localizations of the spin vector orientation, one of which is in agreement with the orbital angular momentum of the infrared gas cloud G2 and the clockwise disk of young stars. This may support a relationship between Sgr A*'s accretion flow and these larger-scale features.
CLUSTERING-BASED FEATURE LEARNING ON VARIABLE STARS
Authors: Mackenzie Cristóbal , Pichara Karim , Protopapas Pavlos 
Published: March 2016

ABSTRACT
The success of automatic classification of variable stars depends strongly on the lightcurve representation. Usually, lightcurves are represented as a vector of many descriptors designed by astronomers called features. These descriptors are expensive in terms of computing, require substantial research effort to develop, and do not guarantee a good classification. Today, lightcurve representation is not entirely automatic; algorithms must be designed and manually tuned up for every survey. The amounts of data that will be generated in the future mean astronomers must develop scalable and automated analysis pipelines. In this work we present a feature learning algorithm designed for variable objects. Our method works by extracting a large number of lightcurve subsequences from a given set, which are then clustered to find common local patterns in the time series. Representatives of these common patterns are then used to transform lightcurves of a labeled set into a new representation that can be used to train a classifier. The proposed algorithm learns the features from both labeled and unlabeled lightcurves, overcoming the bias using only labeled data. We test our method on data sets from the Massive Compact Halo Object survey and the Optical Gravitational Lensing Experiment; the results show that our classification performance is as good as and in some cases better than the performance achieved using traditional statistical features, while the computational cost is significantly lower. With these promising results, we believe that our method constitutes a significant step toward the automation of the lightcurve classification pipeline.
THE ORIGIN OF THE COSMIC GAMMA-RAY BACKGROUND IN THE MeV RANGE
Authors: Ruiz-Lapuente Pilar , The Lih-Sin , Hartmann Dieter H. , Ajello Marco , Canal Ramon , Röpke Friedrich K. , Ohlmann Sebastian T. , Hillebrandt Wolfgang 
Published: March 2016

ABSTRACT
There has been much debate about the origin of the diffuse γ-ray background in the MeV range. At lower energies, AGNs and Seyfert galaxies can explain the background, but not above ≃0.3 MeV. Beyond ∼10 MeV blazars appear to account for the flux observed. That leaves an unexplained gap for which different candidates have been proposed, including annihilations of WIMPS. One candidate is Type Ia supernovae (SNe Ia). Early studies concluded that they were able to account for the γ-ray background in the gap, while later work attributed a significantly lower contribution to them. All those estimates were based on SN Ia explosion models that did not reflect the full 3D hydrodynamics of SN Ia explosions. In addition, new measurements obtained since 2010 have provided new, direct estimates of high-z SN Ia rates beyond z ∼ 2. We take into account these new advances to see the predicted contribution to the gamma-ray background. We use here a wide variety of explosion models and a plethora of new measurements of SN Ia rates. SNe Ia still fall short of the observed background. Only for a fit, which would imply ∼150% systematic error in detecting SN Ia events, do the theoretical predictions approach the observed fluxes. This fit is, however, at odds at the highest redshifts with recent SN Ia rate estimates. Other astrophysical sources such as flat-spectrum radio quasars do match the observed flux levels in the MeV regime, while SNe Ia make up to 30%–50% of the observed flux.
ERRATUM: “UTILIZATION OF THE WAVEFRONT SENSOR AND SHORT-EXPOSURE IMAGES FOR SIMULTANEOUS ESTIMATION OF QUASI-STATIC ABERRATION AND EXOPLANET INTENSITY” (ApJ, 767, 21)
Authors: Frazin Richard A. 
Published: March 2016

ABSTRACT
This paper first demonstrates analytically that, at millisecond timescales, the adaptive optics system in a ground-based telescope will maintain the faint planetary emission nearly constant in time, while the speckle intensity at the planet’s location will undergo wild fluctuations. Then, it presents a method for the simultaneous determination of the image of an exo-planetary system and pupil-plane aberrations that are not corrected by the adaptive optics system (so-called “non-common path aberrations”), which cause a confounding speckle background. The central idea of the method is to take simultaneous millisecond exposures in both the wavefront sensor and science camera, and then perform statistical inference procedures to determine both the aberrations and planetary image. The statistical inference is based on a Taylor expansion of an exponential containing the aberration function. While the first order terms given in the paper are correct, it is missing some second-order terms, which are important when the aberrations are large enough so that a first order expansion is not adequate. Since the numerical experiments used small aberrations, this correction has little effect on the results.
DUST DYNAMICS IN PROTOPLANETARY DISK WINDS DRIVEN BY MAGNETOROTATIONAL TURBULENCE: A MECHANISM FOR FLOATING DUST GRAINS WITH CHARACTERISTIC SIZES
Authors: Miyake Tomoya , Suzuki Takeru K. , Inutsuka Shu-ichiro 
Published: March 2016

ABSTRACT
We investigate the dynamics of dust grains of various sizes in protoplanetary disk winds driven by magnetorotational turbulence, by simulating the time evolution of the dust grain distribution in the vertical direction. Small dust grains, which are well-coupled to the gas, are dragged upward with the upflowing gas, while large grains remain near the midplane of a disk. Intermediate-size grains float near the sonic point of the disk wind located at several scale heights from the midplane, where the grains are loosely coupled to the background gas. For the minimum mass solar nebula at 1 au, dust grains with size of 25–45 μm float around 4 scale heights from the midplane. Considering the dependence on the distance from the central star, smaller-size grains remain only in an outer region of the disk, while larger-size grains are distributed in a broader region. We also discuss the implications of our result for observations of dusty material around young stellar objects.
IMAGING A MAGNETIC-BREAKOUT SOLAR ERUPTION
Authors: Chen Yao , Du Guohui , Zhao Di , Wu Zhao , Liu Wei , Wang Bing , Ruan Guiping , Feng Shiwei , Song Hongqiang 
Published: March 2016

ABSTRACT
The fundamental mechanism initiating coronal mass ejections (CMEs) remains controversial. One of the leading theories is magnetic breakout, in which magnetic reconnection occurring high in the corona removes the confinement on an energized low-corona structure from the overlying magnetic field, thus allowing it to erupt. Here, we report critical observational evidence of this elusive breakout reconnection in a multi-polar magnetic configuration that leads to a CME and an X-class, long-duration flare. Its occurrence is supported by the presence of pairs of heated cusp-shaped loops around an X-type null point and signatures of reconnection inflows. Other peculiar features new to the breakout picture include sequential loop brightening, coronal hard X-rays at energies up to ∼100 keV, and extended high-corona X-rays above the later restored multi-polar structure. These observations, from a novel perspective with clarity never achieved before, present crucial clues to understanding the initiation mechanism of solar eruptions.
Application of UBD Technology for Basement Drilling in Malaysia
Authors: Arathoon Mark 
Published: March 2016

Abstract
The objective of applying underbalanced drilling (UBD) technology to drill basement plays in Malaysia was to determine the true, undamaged production capability, and at the same time determine productivity index while drilling, in order to characterise the reservoir inflow performance versus depth. Previous exploration and appraisal wells had determined oil flow from the basement, but at lower than expected rates, with the understanding that this was due to formation damage.
The key approach was to maintain bottom-hole pressure below formation pressure while drilling. The lower boundary of the formation pressure uncertainty range was hydrostatic pressure. Therefore, the drilling system had to be sub-hydrostatic to ensure underbalanced conditions and eliminate the risk of creating formation damage. Two fluid choices were suitable from a density perspective, base oil and nitrified water. The latter was selected because it enabled simplified separation, avoiding the risk of live oil being returned to the rig pits.
The well design was conventional down to the top of the reservoir, with 9-5/8? liner set 10m inside fresh basement. A tieback liner was run to improve annular velocity and facilitate running a downhole isolation valve to provide improved well integrity and faster bit trips. At first, nitrified seawater was used. However, this was changed to nitrified drillwater to reduce corrosion and scale. Membrane nitrogen was selected on both wells to avoid logistical constraints of supplying cryogenic nitrogen. Two UBD wells were drilled; the first experienced problems with the tieback liner, which backed off while drilling. The liner was re-run and cemented in place to eliminate the risk of recurrence. This approach was repeated on the second well. Although underbalanced conditions were maintained throughout the basement, there was no influx while drilling, or during a subsequent 1000psi drawdown test that was performed with the final drilling BHA. The ROP and bit life exceeded all expectations and demonstrated one of the recognised benefits of UBD. Although oil staining was visible on sidewall cores, it was determined that there were insufficient open and connected fractures to enable the well to flow. The drawdown test was conclusive in avoiding potential additional expenditure on a well test.
These wells demonstrate that basement wells in Malaysia can be successfully drilled using UBD technology and that qualitative reservoir performance information can be obtained while drilling, allowing optimal decision making. From worldwide UBD experience, key benefits include faster ROP, longer bit life, early reservoir characterisation and enhanced productivity. The first three of these have been demonstrated on this project, while the last would still be expected if drilling into open and connected fracture zones.
Tropospheric mercury vertical profiles between 500 and 10 000 m in central Europe
Authors: Weigelt Andreas , Ebinghaus Ralf , Pirrone Nicola , Bieser Johannes , Bödewadt Jan , Esposito Giulio , Slemr Franz , van Velthoven Peter F. J. , Zahn Andreas , Ziereis Helmut 
Published: March 2016

Abstract. The knowledge of the vertical distribution of atmospheric mercury (Hg) plays an important role in determining the transport and cycling of mercury. However, measurements of the vertical distribution are rare, because airborne measurements are expensive and labour intensive. Consequently, only a few vertical Hg profile measurements have been reported since the 1970s. Besides the Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) observations, the latest vertical profile over Europe was measured in 1996. Within the Global Mercury Observation System (GMOS) project, four vertical profiles were taken on board research aircraft (CASA-212) in August 2013 in background air over different locations in Slovenia and Germany. Each vertical profile consists of at least seven 5 min horizontal flight sections from 500 m above ground to 3000 m a.s.l. Gaseous elemental mercury (GEM) and total gaseous mercury (TGM) were measured with Tekran 2537X and Tekran 2537B analysers. In addition to the mercury measurements, SO2, CO, O3, NO, and NO2, basic meteorological parameters (pressure, temperature, relative humidity) have been measured. Additional ground-based mercury measurements at the GMOS master site in Waldhof, Germany and measurements onboard the CARIBIC passenger aircraft were used to extend the profile to the ground and upper troposphere respectively. No vertical gradient was found inside the well-mixed boundary layer (variation of less than 0.1 ng m−3) at different sites, with GEM varying from location to location between 1.4 and 1.6 ng m−3 (standard temperature and pressure, STP: T  =  273.15 K, p  =  1013.25 hPa). At all locations GEM dropped to 1.3 ng m−3 (STP) when entering the free troposphere and remained constant at higher altitudes. The combination of the vertical profile, measured on 21 August 2013 over Leipzig, Germany, with the CARIBIC measurements during ascent and descent to Frankfurt Airport, Germany, taken at approximately the same time, provide a unique central European vertical profile from inside the boundary layer (550 m a.s.l) to the upper free troposphere (10 500 m a.s.l.) and show a fairly constant free-tropospheric TGM concentration of 1.3 ng m−3 (STP).
Re-evaluating the Frankfurt isothermal static diffusion chamber for ice nucleation
Authors: Schrod Jann , Danielczok Anja , Weber Daniel , Ebert Martin , Thomson Erik S. , Bingemer Heinz G. 
Published: March 2016

Abstract. Recently significant advances have been made in the collection, detection and characterization of ice nucleating particles (INPs). Ice nuclei are particles that facilitate the heterogeneous formation of ice within the atmospheric aerosol by lowering the free energy barrier to spontaneous nucleation and growth of ice from atmospheric water and/or vapor. The Frankfurt isostatic diffusion chamber (FRankfurt Ice nucleation Deposition freezinG Experiment: FRIDGE) is an INP collection and offline detection system that has become widely deployed and shows additional potential for ambient measurements. Since its initial development FRIDGE has gone through several iterations and improvements. Here we describe improvements that have been made in the collection and analysis techniques. We detail the uncertainties inherent in the measurement method and suggest a systematic method of error analysis for FRIDGE measurements. Thus what is presented herein should serve as a foundation for the dissemination of all current and future measurements using FRIDGE instrumentation.
Automation of soil flux chamber measurements: potentials and pitfalls
Authors: Görres Carolyn-Monika , Kammann Claudia , Ceulemans Reinhart 
Published: March 2016

Abstract. Recent technological advances have enabled the wider application of automated chambers for soil greenhouse gas (GHG) flux measurements, several of them commercially available. However, few studies addressed the challenges associated with operating these systems. In this contribution we compared two commercial soil GHG chamber systems – the LI-8100A Automated Soil CO2 Flux System and the greenhouse gas monitoring system AGPS. From April until August 2014, the two systems monitored in parallel soil respiration (SR) fluxes at a recently harvested poplar (Populus) plantation, which provided a bare field situation directly after the harvest as well as a closed canopy later on. For the bare field situation (15 April–30 June 2014), the cumulated average SR obtained from the unfiltered data sets of the LI-8100A and the AGPS were 520 and 433 g CO2 m−2 respectively. For the closed canopy phase (1 July–31 August 2014), which was characterized by a higher soil moisture content, the cumulated average SR estimates were not significantly different with 507 and 501 g CO2 m−2 for the AGPS and the LI-8100A respectively. Flux quality control and filtering did not significantly alter the results obtained by the LI-8100A, whereas the AGPS SR estimates were reduced by at least 20 %. The main reasons for the observed differences in the performance of the two systems were (i) a lower data coverage provided by the AGPS due to technical problems; (ii) incomplete headspace mixing in the AGPS chambers; (iii) lateral soil CO2 diffusion below the collars during AGPS chamber measurements; and (iv) a possible overestimation of nighttime SR fluxes by the LI-8100A. Additionally, increased root growth was observed within the LI-8100A collars but not within the AGPS collars, which might have also contributed to the observed differences. In contrast to the LI-8100A, the AGPS had the gas sample inlets installed inside the collars and not the chambers. This unique design feature enabled for the first time the detection of disturbed chamber measurements during nights with a stratified atmosphere, resulting in unbiased nighttime SR estimates. Thus besides providing high temporal frequency flux data, automated chamber systems offer another possibility to greatly improve our understanding of SR fluxes.
دور خدمات المعلومات في المكتبة الطبية بجامعة السلطان قابوس في رفع المستوى المعرفي للطلاب
Authors: Hamdan Alaamri Jamila , Juma Al-Riyami Rabab , Saif Al-mayahi Samiya 
Published: March 2016

دور خدمات المعلومات في المكتبة الطبية بجامعة السلطان قابوس في رفع المستوى المعرفي للطلابتعتبر المكتبة الطبية في جامعة السلطان قابوس أحد المؤسسات المعلوماتية المتخصصة في مجال الطب والعلوم الصحية التي تقدم خدماتها لأساتذة كلية الطب في الجامعة، إضافة إلى المتخصصين في مجال الطب والعلوم الصحية في سلطنة عمان.ومن أبرز أهداف هذه المكتبة رفع المستوى المعرفي في مجال الطب والعلوم الصحية لدى طلبة الكلية والسعي إلى دعم وتعزيز المقررات الدراسية في الطلبة.
هدفت الدراسة إلى التعرف على أنواع ومستوى الخدمات المعلوماتية التي تقدمها المكتبة للطلبة ودور هذه الخدمات (قواعد البيانات، الكتب الالكترونية، الدوريات الالكترونية، المواد السمعية والبصرية، بالإضافة إلى خدمة الطب السريري) في رفع المستوى المعرفي لدى الطلبة والارتقاء بمستوى خبراتهم، كما هدفت الدراسة إلى تقصي الصعوبات التي تواجه الطلبة في استخدامهم للخدمات المعلوماتية التي تقدمها المكتبة ومدى قدرتهم على تجاوزها. اعتمدت الدراسة على استخدام المنهج الوصفي التحليلي وذلك من خلال إعداد استبانة تتضمن محاورها أنواع الخدمات المعلوماتية التي تقدمها المكتبة وأهمية هذه الخدمات بالنسبة للطلبة ،وتم توزيع استبانة على عينة عشوائية من الطلبة في كلية الطب بواقع 26 طالبًا وطالبة من مختلف المراحل الدراسية.
وتوصلت الدراسة إلى جملة من النتائج، أهمها يلجأ الكثير من الطلاب والطالبات من كلية الطب إلى استخدم خدمات المكتبة ومصادرها بصورة مستمرة بنسبة 89% . وقدرة الطلاب على الحصول على حاجتهم المعلوماتية عند البحث في قواعد البيانات الطبية بمختلف أنواعها المتاحة على موقع المكتبة بنسبة 88%. وكذلك تقدم المكتبة الطبية كتب إلكترونية مختلفة في كل المجالات الطبية بنسبة 87%. تقدم المكتبة خدمة الطب السريري بكفاءة عالية ومستوى فعًال بنسبة 50% رغم أنها خدمة جديدة تقدمها المكتبة.و أيضًا أكثر صعوبة تواجه الطلاب والطالبات هي ضيق الوقت وكثافة المواد الدراسية. وتوصي الدراسة ضرورة وجود تحديث فعّال في الدوريات الإلكترونية الطبية التي تصدر بشكل دوري حتى يستطيع الطلاب مسايرة التطورات العلمية الطبية.وكذلك ضرورة وجود قسم خاص بالتطوير المهني وتدريب أطباء الطب السريري؛ ليكون المسؤول عن متابعتهم وتوفير الفرص اللازمة. تفعيل دور التواصل بين الهيئة الاكاديمية في الكلية والمكتبة؛ لتفعيل استخدام المصادر والتقليل من كثافة المواد الدراسية مع تنوع في تلقينها ، لتبادل الخبرات وتنمية المهارات الطبية.