bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of Formation Damage at Water Injectors Wells due to Channelization in Unconsolidated Formations
Authors: Bautista J. F. , Taleghani A. Dahi 
Published: January 2016

Abstract
Formation damage due to chemical reactions or physical failure of rock is a well-known issue in the oil and gas industry. In this paper, we look at the changes of injectivity at water injectors located in unconsolidated formations as a result of sand channelization. In these situations, sand particles migrate from the formation matrix toward the wellbore and consequently affect permeability of the formation and completion components like frac-packs or gravel-packs. To model this phenomenon, we propose a model that decomposes the sand matrix into two different phases by means of their volumetric fractions. The first phase consists of the immobile granular phase while the other is the fraction of grains that are detached from the matrix and carried away by the fluid. The ratio of these two phases evolves over time by means of erosion and deposition. A finite element code is developed for numerical implementation of this model for different reservoir properties. The results show how the porosity evolves over time around the wellbore by the formation of channels that enhance the flow, however, upon well shut-in, Flowback induced by the water hammer effect brings a large amount sand into the well and fill it up. A study of the effect of frac-packs which are typical completions for wells targeting soft formations is performed to demonstrate potential damage of repetitive shut-ins on injectivity in these wells. The presented model appears as a robust tool to predict sand production in different completion systems to achieve more sustainable injection treatments.
Sand Screen Design and Optimization for Horizontal Wells Using Reservoir Grain Size Distribution Mapping
Authors: Mahmoudi Mahdi , Roostaei Morteza , Ghalambor Ali 
Published: January 2016

Abstract
The primary goal of screen design for steam assisted gravity drainage (SAGD) operations is to prevent the entrance of the poorly or unconsolidated sand into the production flow stream, which could cause serious damages to the downhole/surface facilities. Current screen design approach fits one screen opening size for the entire length of the well, which leads to a conservative screen opening to avoid sand production along the well. This study introduces a new approach to design the screen opening, considering different opening sizes along the horizontal well.
The proposed workflow in designing the optimum screen opening relies on well logs and core analysis to map the grain size distribution within reservoir through a geostatistical approach. Considering the horizontal well path and the changes in liner length due to installation and thermal loads, we design the screen aperture size to optimize the screen selection based on sand facies present in different sections of the wellbore. This enables us to provide different screen opening for different sand facies along the horizontal well.
The new approach provides a more detailed design for screen opening for the horizontal well according to the sand size distribution within the reservoir instead of trying to fit one opening size for the entire horizontal section. It also considers the thermal expansion of the joints. This approach designs the screen opening for different sand facies along the horizontal well in a way which obtains the highest productivity and lowest produced sand.
This paper provides a novel workflow for the design and optimization of screen for horizontal wells, which could be used to optimize the design of different standalone screens such as slotted liner, precise punch screen (PPS) and wire wrapped screen (WWS).
Soil Moisture Differences between Terracette Benches and Risers on Semiarid Rangeland Hillslopes
Authors: Corrao Mark , Heinse Robert , Eitel Jan , Cosens Barbara , Link Tim 
Published: January 2016

Core IdeasHoof impact on terracetted hillslopes affects bulk density and compaction between bench and riser.Increased soil moisture is not plant available and doesn't increase forage production.Greater water content on benches is due to shifts to smaller pore sizes with compaction.Reduced vegetative cover due to root impedance results in greater water content.Microtopographic features known asterracettesare found throughout semiarid rangelands. Their soil properties and hydrologic function, however, are virtually unknown. This research aimed to quantify whether or not terracetted hillslopes retain more soil water. The objectives of this research were to: (i) assess soil moisture measured at two terracetted field sites comparing bench and riser; (ii) identify to what extent microtopography, soil properties, and land use affect soil moisture; and (iii) quantify differences in soil moisture at the field scale between terracetted and control sites (grazed and ungrazed) in eastern Washington. We measured volumetric water content (θv), bulk density, soil texture, saturated hydraulic conductivity, and organic matter in addition to compaction, vegetative cover, and cattle density. Our results show significant θvdifferences between terracette benches and risers in the upper 10 cm, with benches exhibiting higher mean θvthan risers across all sites during both wet (+6.14%) and dry (+6.63%) seasons. Soil texture and organic matter did not vary between bench and riser features, and microtopography itself was not driving observed soil moisture differences. Soil moisture differences were attributed to land use (i.e., cattle) impact on soil bulk density and vegetative cover. Greater water content on terracette benches is partially attributed to shifts to smaller pore sizes with compaction and a reduction in transpiration resulting from lower vegetative cover due to root impedance. However, this increased water storage is not plant accessible and does not contribute to increased forage production. This work is intended to provide a mechanistic understanding of terracette hydrology for semiarid rangeland management.
Age at Menarche and Risk of Gestational Diabetes Mellitus: A Prospective Cohort Study Among 27,482 Women
Authors: Chen Liwei , Li Shanshan , He Chunyan , Zhu Yeyi , Buck Louis Germaine M. , Yeung Edwina , Hu Frank B. , Zhang Cuilin 
Published: January 2016

OBJECTIVE
To examine the association between age at menarche and risk of gestational diabetes mellitus (GDM).

RESEARCH DESIGN AND METHODS
A prospective cohort study of 42,109 eligible pregnancies from 27,482 women in the Nurses’ Health Study II.

RESULTS
The adjusted risk ratios for GDM across the age at menarche categories (≤11, 12, 13, and ≥14 years) were 1.34 (95% CI 1.14–1.58), 1.13 (0.97–1.31), 1.11 (0.95–1.29), and 1.00 (referent; P for trend = 0.0005), respectively. Analysis of the mediating effect indicated that 42.1% (P = 0.0007) of the association was mediated through prepregnancy BMI.

CONCLUSIONS
These findings suggested that earlier menarche was significantly associated with an increased risk of GDM. This association was largely mediated through prepregnancy excessive body adiposity.
On the Classification of Simple Singularities in Positive Characteristic
Authors: Afzal Deeba , Binyamin Muhammad Ahsan , Janjua Faira Kanwal 
Published: January 2016

Abstract
The aim of the article is to describe the classification of simple isolated hypersurface sin- gularities over a field of positive characteristic by certain invariants without computing the normal form. We also give a description of the algorithms to compute the classification which we have implemented in the Singular libraries classifyCeq.lib and classifyReq.lib. 1 Int
On Characteristic Poset and Stanley Decomposition
Authors: Ahmad Sarfraz , Anwar Imran , Qureshi Ayesha Asloob 
Published: January 2016

Abstract
Let J ⊂ I be two monomial ideals such that I/J is Cohen Macaulay. By associating a finite posets

P

I
/
J

g

$P_{I/J}^g$

to I/J, we show that if I/J is a Stanley ideal then

I
/
J

˜

$\widetilde{I/J}$

is also a Stanley ideal, where

I
/
J

˜

$\widetilde{I/J}$

is the polarization of I/J. We also give relations between sdepth and fdepth of I/J and

I
/
J

˜

$\widetilde{I/J}$
A new proof of the bound for the first Dirichlet eigenvalue of the Laplacian operator
Authors: Li Chang-Jun , Gao Xiang 
Published: January 2016

Abstract
In this paper, we present a new proof of the upper and lower bound estimates for the first Dirichlet eigenvalue

λ
1
D

(

B

(

p
,
r

)

)

$\lambda _1^D \left({B\left({p,r} \right)} \right)$

of Laplacian operator for the manifold with Ricci curvature Rc ≥ −K, by using Li-Yau’s gradient estimate for the heat equation.
On the recovery of the doping profile in an time-dependent drift-diffusion model
Authors: Wu Bin , Wang Zewen 
Published: January 2016

Abstract
We consider an inverse problem arising from an time-dependent drift-diffusion model in semiconductor devices, which is formulated in terms of a system of parabolic equations for the electron and hole densities and the Poisson equation for the electric potential. This inverse problem aims to identify the doping profile from the final overdetermination data of the electric potential. By using the Schauder’s fixed point theorem in suitable Sobolev space, the existence of this inverse problem are obtained. Moreover by means of Gronwall inequality, we prove the uniqueness of this inverse problem for small measurement time. For this nonlinear inverse problem, our theoretical results guarantee the solvability for the proposed physical model.
Immediate Effect of Active Abdominal Contraction on Inter-recti Distance
Authors: Chiarello Cynthia M. , McAuley J. Adrienne , Hartigan Erin H. 
Published: January 2016

Study Design Controlled laboratory study. Background Inter-recti distance (IRD) is the measurement of the linear distance between the medial aspects of the rectus abdominis muscle. Inter-recti distance has been reported to decrease in postpartum women during a curl-up maneuver. Objective To determine if IRD decreases with active abdominal contraction in men and in nulliparous and parous women. Methods Fifty-six subjects (male, 11; nulliparous female, 22; parous female, 23) participated. Inter-recti distance was measured with the abdominal muscles at rest and during active contraction (curl-up), at 2 locations (above and below the umbilicus), using ultrasound imaging. A mixed-model, repeated-measures analysis of covariance was used for each of the 2 locations, to determine whether IRD differed between contraction states among the 3 groups, with age and umbilicus circumference as covariates. When significant differences were found, planned t test comparisons were made. Results The parous group's IRD significantly decreased from rest to contraction at both locations, whereas the nulliparous and male groups' IRD did not significantly change from rest to contraction. The nulliparous group's IRD was significantly narrower than the other groups at rest at both locations, and narrower than the parous group during active contraction. Conclusion Parous women had a narrower IRD in the curl-up condition than at rest, as hypothesized. However, an unexpected finding of a lack of significant within-group change in IRD in nulliparous women and men occurred. Findings suggest that the IRD in men may only differ from that of nulliparous women. J Orthop Sports Phys Ther 2016;46(3):177–183. Epub 26 Jan 2016. doi:10.2519/jospt.2016.6102
CHEMICAL EVOLUTION OF THE INNER 2 DEGREES OF THE MILKY WAY BULGE: [α/Fe] TRENDS AND METALLICITY GRADIENTS
Authors: Ryde N. , Schultheis M. , Grieco V. , Matteucci F. , Rich R. M. , Uttenthaler S. 
Published: January 2016

ABSTRACT
The structure, formation, and evolution of the Milky Way bulge is a matter of debate. Important diagnostics for discriminating between models of bulge formation and evolution include α-abundance trends with metallicity, and spatial abundance and metallicity gradients. Due to the severe optical extinction in the inner Bulge region, only a few detailed investigations of this region have been performed. Here we aim at investigating the inner 2 degrees of the Bulge (projected galactocentric distance of approximately 300 pc), rarely investigated before, by observing the [α/Fe] element trends versus metallicity, and by trying to derive the metallicity gradient in the b < 2° region. [α/Fe] and metallicities have been determined by spectral synthesis of 2 μm spectra of 28 M-giants in the Bulge, lying along the southern minor axis at (l, b) = (0, 0), (0, −1°), and (0, −2°). These were observed with the CRIRES spectrometer at the Very Large Telescope, (VLT) at high spectral resolution. Low-resolution K-band spectra, observed with the ISAAC spectrometer at the VLT, are used to determine the effective temperature of the stars. We present the first connection between the Galactic center (GC) and the Bulge using similar stars, high spectral resolution, and analysis techniques. The [α/Fe] trends in all our three fields show a large similarity among each other and with trends further out in the Bulge. All point to a rapid star formation episode in the Bulge. We find that there is a lack of an [α/Fe] gradient in the Bulge all the way into the center, suggesting a homogeneous Bulge when it comes to the enrichment process and star formation history. We find a large range of metallicities from −1.2 < [Fe/H] < +0.3, with a lower dispersion in the GC: −0.2 < [Fe/H] < +0.3. The derived metallicities of the stars in the three fields get, in the mean, progressively higher the closer to the Galactic plane they lie. We could interpret this as a continuation of the metallicity gradient established further out in the Bulge, but due to the low number of stars and possible selection effects, more data of the same sort as presented here is necessary to conclude on the inner metallicity gradient from our data alone. Our results firmly argue for the center being in the context of the Bulge rather than very distinct.
OPTICAL SPECTROSCOPIC OBSERVATIONS OF GAMMA-RAY BLAZAR CANDIDATES. V. TNG, KPNO, AND OAN OBSERVATIONS OF BLAZAR CANDIDATES OF UNCERTAIN TYPE IN THE NORTHERN HEMISPHERE
Authors: Álvarez Crespo N. , Masetti N. , Ricci F. , Landoni M. , Patiño-Álvarez V. , Massaro F. , D’Abrusco R. , Paggi A. , Chavushyan V. , Jiménez-Bailón E. , Torrealba J. , Latronico L. , La Franca F. , Smith Howard A. , Tosti G. 
Published: January 2016

ABSTRACT
The extragalactic γ-ray sky is dominated by emission from blazars, a peculiar class of active galactic nuclei. Many of the γ-ray sources included in the Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidates of uncertain type (BCUs) because there are no optical spectra available in the literature to confirm their nature. In 2013, we started a spectroscopic campaign to look for the optical counterparts of the BCUs and of the unidentified γ-ray sources to confirm their blazar nature. Whenever possible we also determine their redshifts. Here, we present the results of the observations carried out in the northern hemisphere in 2013 and 2014 at the Telescopio Nazionale Galileo, Kitt Peak National Observatory, and Observatorio Astronómico Nacional in San Pedro Mártir. In this paper, we describe the optical spectra of 25 sources. We confirmed that all of the 15 BCUs observed in our campaign and included in our sample are blazars and we estimated the redshifts for three of them. In addition, we present the spectra for three sources classified as BL Lacs in the literature but with no optical spectra available to date. We found that one of them is a quasar (QSO) at a redshift of z = 0.208 and the other two are BL Lacs. Moreover, we also present seven new spectra for known blazars listed in the Roma-BZCAT that have an uncertain redshift or are classified as BL Lac candidates. We found that one of them, 5BZB J0724+2621, is a “changing look” blazar. According to the spectrum available in the literature, it was classified as a BL Lac, but in our observation we clearly detected a broad emission line that led us to classify this source as a QSO at z = 1.17.
UBVRIz LIGHT CURVES OF 51 TYPE II SUPERNOVAE
Authors: Galbany Lluís , Hamuy Mario , Phillips Mark M. , Suntzeff Nicholas B. , Maza José , Jaeger Thomas de , Moraga Tania , González-Gaitán Santiago , Krisciunas Kevin , Morrell Nidia I. , Thomas-Osip Joanna , Krzeminski Wojtek , González Luis , Antezana Roberto , Wishnjewski Marina , McCarthy Patrick , Anderson Joseph P. , Gutiérrez Claudia P. , Stritzinger Maximilian , Folatelli Gastón , Anguita Claudio , Galaz Gaspar , Green Elisabeth M. , Impey Chris , Kim Yong-Cheol , Kirhakos Sofia , Malkan Mathew A. , Mulchaey John S. , Phillips Andrew C. , Pizzella Alessandro , Prosser Charles F. , Schmidt Brian P. , Schommer Robert A. , Sherry William , Strolger Louis-Gregory , Wells Lisa A. , Williger Gerard M. 
Published: January 2016

ABSTRACT
We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986–2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C&T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.
MOLECULAR GAS VELOCITY DISPERSIONS IN THE ANDROMEDA GALAXY
Authors: Caldú-Primo Anahi , Schruba Andreas 
Published: January 2016

ABSTRACT
In order to characterize the distribution of molecular gas in spiral galaxies, we study the line profiles of CO (1 – 0) emission in Andromeda, our nearest massive spiral galaxy. We compare observations performed with the IRAM 30 m single-dish telescope and with the CARMA interferometer at a common resolution of 23 arcsec ≈ 85 pc × 350 pc and 2.5 km s−1. When fitting a single Gaussian component to individual spectra, the line profile of the single dish data is a factor of 1.5 ± 0.4 larger than the interferometric data one. This ratio in line widths is surprisingly similar to the ratios previously observed in two other nearby spirals, NGC 4736 and NGC 5055, but measured at ∼0.5–1 kpc spatial scale. In order to study the origin of the different line widths, we stack the individual spectra in five bins of increasing peak intensity and fit two Gaussian components to the stacked spectra. We find a unique narrow component of FWHM = 7.5 ± 0.4 km s−1 visible in both the single dish and the interferometric data. In addition, a broad component with FWHM = 14.4 ± 1.5 km s−1 is present in the single-dish data, but cannot be identified in the interferometric data. We interpret this additional broad line width component detected by the single dish as a low brightness molecular gas component that is extended on spatial scales >0.5 kpc, and thus filtered out by the interferometer. We search for evidence of line broadening by stellar feedback across a range of star formation rates but find no such evidence on ∼100 pc spatial scale when characterizing the line profile by a single Gaussian component.
THE REFLARES AND OUTBURST EVOLUTION IN THE ACCRETING MILLISECOND PULSAR SAX J1808.4–3658: A DISK TRUNCATED NEAR CO-ROTATION?
Authors: Patruno A. , Maitra D. , Curran P. A. , D’Angelo C. , Fridriksson J. K. , Russell D. M. , Middleton M. , Wijnands R. 
Published: January 2016

ABSTRACT
The accreting millisecond X-ray pulsar SAX J1808.4–3658 shows peculiar low luminosity states known as “reflares” after the end of the main outburst. During this phase the X-ray luminosity of the source varies by up to three orders of magnitude in less than 1–2 days. The lowest X-ray luminosity observed reaches a value of

, only a factor of a few brighter than its typical quiescent level. We investigate the 2008 and 2005 reflaring state of SAX J1808.4–3658 to determine whether there is any evidence for a change in the accretion flow with respect to the main outburst. We perform a multiwavelength photometric and spectral study of the 2005 and 2008 reflares with data collected during an observational campaign covering the near-infrared, optical, ultra-violet and X-ray band. We find that the NIR/optical/UV emission, expected to come from the outer accretion disk, shows variations in luminosity over an order of magnitude. The corresponding X-ray luminosity variations are instead much deeper, spanning about 2–3 orders of magnitude. The X-ray spectral state observed during the reflares does not change substantially with X-ray luminosity, indicating a rather stable configuration of the accretion flow. We investigate the most likely configuration of the innermost regions of the accretion flow and we infer an accretion disk truncated at or near the co-rotation radius. We interpret these findings as due to either a strong outflow (due to a propeller effect) or a trapped disk (with limited/no outflow) in the inner regions of the accretion flow.
THE DEFINITIVE X-RAY LIGHT CURVE OF SWIFT J164449.3+573451
Authors: Mangano V. , Burrows D. N. , Sbarufatti B. , Cannizzo J. K. 
Published: January 2016

ABSTRACT
On 2011 March 28, the Swift Burst Alert Telescope triggered on an object that had no analog in over six years of Swift operations. Follow-up observations by the Swift X-ray Telescope (XRT) found a new, bright X-ray source covering three orders of magnitude in flux over the first few days, that was much more persistent (and variable) than gamma-ray burst afterglows. Ground-based spectroscopy found a redshift of 0.35, implying extremely high luminosity, with integrated isotropic-equivalent energy output in the X-ray band alone exceeding 1053 erg in the first two weeks after discovery. Strong evidence for a collimated outflow or beamed emission was found. The observational properties of this object are unlike anything ever before observed. We interpret these unique properties as the result of emission from a relativistic jet produced in the aftermath of the tidal disruption of a main sequence star by a massive black hole (BH) in the center of the host galaxy. The source decayed slowly as the stellar remnants were accreted onto the BH, before abruptly shutting off. Here we present the definitive XRT team light curve for Swift J164449.3+573451 and discuss its implications. We show that the unabsorbed flux decayed roughly as a

power law up to 2012 August 17. The steep turnoff of an order of magnitude in 24 hr seems to be consistent with the shutdown of the jet as the accretion disk transitioned from a thick disk to a thin disk. Swift continues to monitor this source in case the jet reactivates.
THE LICK-CARNEGIE EXOPLANET SURVEY: HD 32963—A NEW JUPITER ANALOG ORBITING A SUN-LIKE STAR
Authors: Rowan Dominick , Meschiari Stefano , Laughlin Gregory , Vogt Steven S. , Butler R. Paul , Burt Jennifer , Wang Songhu , Holden Brad , Hanson Russell , Arriagada Pamela , Keiser Sandy , Teske Johanna , Diaz Matias 
Published: January 2016

ABSTRACT
We present a set of 109 new, high-precision Keck/HIRES radial velocity (RV) observations for the solar-type star HD 32963. Our data set reveals a candidate planetary signal with a period of 6.49 ± 0.07 years and a corresponding minimum mass of 0.7 ± 0.03 Jupiter masses. Given Jupiter's crucial role in shaping the evolution of the early Solar System, we emphasize the importance of long-term RV surveys. Finally, using our complete set of Keck radial velocities and correcting for the relative detectability of synthetic planetary candidates orbiting each of the 1122 stars in our sample, we estimate the frequency of Jupiter analogs across our survey at approximately 3%.