bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abundances of Disk PNe in M31 and the radial oxygen gradient
Authors: Kwitter Karen B. , Lehman Emma M. M. , Balick Bruce , Henry Richard B. C. 
Published: August 2012

AbstractWe have obtained spectra of 16 PNe in the disk of M31 and determined the abundances of He, N, O, Ne, S and Ar. Here we present the median abundances and compare them with previous M31 PN disk measurements and with PNe in the Milky Way. We also derive the radial oxygen gradient in M31, which is shallower than that in the Milky Way, even accounting for M31's larger disk scale length.
PyNeb: a new software for the analysis of emission lines
Authors: Luridiana Valentina , Morisset Christophe , Shaw Richard A. 
Published: August 2012

AbstractWe describe an ongoing project to migrate the emission-line analysis package nebular from its current environment, IRAF, to a modern programming environment where it can be used from command line, a local GUI, or the web. We are also updating the supporting atomic data where they have been superseded by superior calculations or measurements.
Plasma diagnostics for planetary nebulae and H ii regions using N ii and O ii optical recombination lines
Authors: McNabb Ian A. , Fang Xuan , Liu Xiao–Wei , Storey Peter J. 
Published: August 2012

AbstractWe carry out plasma diagnostic analysis for a number of planetary nebulae (PNe) and H ii regions. We use N ii and O ii optical recombination lines (ORLs) with new effective recombination coefficients calculated under the intermediate coupling scheme, for a range of electron temperatures (Te) and densities (Ne), and fitted against the most reliable measurements. Comparing Te derived from ORLs, collisionally excited lines (CELs), the hydrogen Balmer Jump, and/or He i if available, we find the relation Te (ORLs) < Te (He i) < Te (H i BJ) < Te (CELs), confirming the physical conditions in the bi-abundance model postulated by Liu et al., i.e. the nebula contains another cold, metal-rich and probably H-deficient component.
Planetary nebula spectra in M 60 and M 82
Authors: Méndez Roberto H. , Teodorescu Ana M. , Hattori Takashi , Magrini Laura , Johnson Lent C. 
Published: August 2012

AbstractUsing the Subaru telescope and its FOCAS spectrograph in multi-object mode, we have obtained spectra of a selection of bright PNs in two galaxies: the Virgo giant elliptical M 60 (NGC 4649), and the starburst spiral M 82. We report on individual extinctions, as determined from the Balmer decrement, and also on the intensities of [O III] 4959 and 5007 relative to Hβ.
A consolidated online database of Galactic planetary nebulae
Authors: Miszalski Brent , Acker A. , Ochsenbein F. , Parker Q. A. 
Published: August 2012

AbstractSince the issue of the unifying Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (SECGPN) a large number of new discoveries have been made thanks to improved surveys and discovery techniques. The increasingly heterogeneous published population of Galactic PNe, that we have determined totals <2850 PNe, is becoming more difficult to study on the whole without a centralised repository. We introduce a consolidated and interactive online database with object classifications that reflect the latest multi-wavelength data and the most recent results. The extensible database, hosted by the Centre de Donnees astronomique de Strasbourg (CDS), will contain a wealth of observed data for large, well-defined samples of PNe including coordinates, multi-wavelength images, spectroscopy, line intensities, radial velocities and central star information. It is anticipated that the database will be publicly released early 2012.
Modeling the dust emission from PN IC418
Authors: Morisset Christophe , Szczerba Ryszard , Anibal García-Hernández D. , García-Lario Pedro 
Published: August 2012

AbstractWe construct a detailed model for the IR dust emission from the PN IC 418. We succeed to reproduce the emission from 2 to 200 μm. We can determine the amount of emitting dust as well as its composition, and compare to the depletion of elements determined for the photoionized region.
Distance determination to PNe using the extinction-distance method
Authors: Navarro Silvana G. , Corradi Romano L. M. , Mampaso Antonio 
Published: August 2012

AbstractWe present individual distances to three PNe: NGC 6537, NGC 6781 and NGC 7027, determined by the extinction-distance method. These objects are part of a larger sample (35) of PNe that we observed at ORM. In order to apply this method, and to obtain accurate distances, we determined the spectral type of 40 to 60 stars in the line of sight of each PNe. This implied the necessity of classifying few thousands of stellar spectra with S/N ratio between 10 and 60. To solve such need we developed an ANN system to perform automatic spectral classification which could classify spectra with S/N ratio as low as 20 with an accuracy better than 2 spectral subtypes. In this poster we compare the accuracy of such distances with previous distance determinations using other methods. We conclude that it is possible to use this method to obtain the distance of a large number of PNe with better precision.
The kinematics of evolved planetary nebulae
Authors: Pereyra E. Margarita , Richer Michael G. , López Jose-Alberto 
Published: August 2012

AbstractWe have selected a group of 85 evolved planetary nebulae to study their kinematic characteristic based on spatially resolved, long-slit echelle spectroscopy. The data have been drawn from the San Pedro Mártir Kinematic Catalogue of PNe. The aim is to characterize in detail the global kinematics of PNe at advanced stages of evolution with the largest sample of homogenous data used to date for this purpose. The results reveal groups that share kinematic and photo-ionization characteristics of the nebular shell at the different late stages under study. The expansion velocities are typically larger than seen in earlier evolutionary stages, with the largest velocities occurring in objects with very weak or absent [N II]λλ6548, 6584 emission line. These results shall serve to be compared to predictions of hydrodynamical models.
The kinematical behavior of Galactic PNe with [WC] central star
Authors: Rechy-García Jackeline S. , Peña Miriam , García-Rojas Jorge 
Published: August 2012

AbstractHigh resolution spectroscopic data of a large sample of galactic planetary nebulae with [WC] central stars ([WC]PNe) are analyzed to determine their kinematical behavior. Their heliocentric velocities have been determined with a precision better than a few km/s. Distances obtained from the literature are used to derive the peculiar velocities of the objects. Our preliminary results are: (a) The [WC] PNe are distributed in the galactic disk and they appear more concentrated than the normal PNe. (b) Separating the sample in Peimbert's types, we find that Type I PNe show in general low peculiar velocities (<50 km/s) except for a couple of objects apparently belonging to the galactic bulge. For the other [WC]PNe, most of them belong to the Peimbert's Type II (defined as having Vpec ≤ 60 km/s). However there is an important fraction (28%) showing Vpec larger than 60 km/s therefore they are classified as Peimbert's Type III.
A complete survey of mm line emission from CO and 13CO in water fountain stars
Authors: Rizzo J. Ricardo , Gómez José F. , Miranda Luis F. , Osorio Mayra , Suárez Olga 
Published: August 2012

Abstract“Water fountains” (WF) are post-AGB stars characterized by very fast and often bipolar jets in the water maser line at 22 GHz. We conducted a survey of the CO and 13CO line emission using the IRAM 30m radio telescope of all the sources visible from the observatory. Over a total of 10 WFs observed, we identified CO and 13CO associated to IRAS 18460-0151 and IRAS 18596+0315. As the CO line emission is ubiquitous in the Galactic plane, the confirmed detections have met strict criteria to consider these cases as confirmed detections. The velocity components associated to the WFs are ~ 40 km s−1 wide, centered at the star velocity, present only at the star position, and detected in the four observed transitions, the CO and 13CO J=1→0 and 2→1 lines. A preliminary study, based on line ratios, indicates that this molecular component has a high opacity, and a very low 12C/13C isotopic ratio.
Kinematic age determinations of planetary nebula central stars
Authors: Rodrigues Thaise S. , Maciel Walter J. 
Published: August 2012

AbstractCentral stars of planetary nebulae (CSPN) have a relatively large mass interval, so that it is expected that these stars also have different ages, typically above 1 Gyr. Apart from the properties of the CSPN themselves, the problem of age determination is also important in the context of the chemical evolution of the Galaxy, for instance in the understanding of the time variation of chemical abundance gradients. In this work, we estimated the ages of a sample of CSPN on the basis of some correlations between their kinematic properties and the expected ages. According to these correlations, the observed dispersions in the U, V, W velocities are uniquely defined by the stellar ages. The adopted correlations were derived from the recent Geneva-Copenhagen survey of galactic stars. Preliminary results suggest the most CSPN in the galactic disk have ages under 3 Gyr. These results are also compared with some recent age distributions based on independent correlations involving the nebular chemical abundances.
A Herschel study of Planetary Nebulae
Authors: Van de Steene Griet C. , Exter Katrina M. , van Hoof Peter A. M. , Lim Tanya L. , Barlow Michael J. , Matsuura Mikako , Ueta Toshiya ,   the MESS consortium
Published: August 2012

AbstractWe present Herschel PACS and SPIRE images of the dust shells around the planetary nebulae NGC 650, NGC 6853, and NGC 6720, as well as images showing the dust temperature in their shells. The latter show a rich structure, which indicates that internal extinction in the UV is important despite the highly evolved status of the nebulae.
The Σ – D relation for Galactic planetary nebulae: Application of orthogonal fitting procedure
Authors: Vukotić Branislav , Urošević Dejan 
Published: August 2012

AbstractWe estimate the parameters of the radio surface brightness to diameter (Σ – D) relation for the sample of Galactic planetary nebulae (PNe). The bootstrap re-sampling and orthogonal offsets fitting procedure are applied. The orthogonal fitting procedure provides that the parameter values of D – Σ and Σ – D fits are invariant within the estimated uncertainties. We discuss the probability statistics of the fitted (log Σ = log A - β log D) relation and the resulting fit parameters which is indicative for PN distance determination.
A study of the effect of ionization and illumination on morphologies of planetary nebulae
Authors: Zhang Yong , Kwok Sun , Ko Chung-Ming 
Published: August 2012

AbstractWe carry out a modelling study of the effect of ionization and illumination on the morphologies of planetary nebulae (PNs), aiming to investigate the hypothesis of Kwok (2010) that the bipolar and multipolar lobes of PNs can be produced by leakage of UV photons into those directions. Using photoinization code, we construct a series of nebular models consisting of a dense envelope and cones of low density. The results show that the visible morphologies of PNs may be fundamentally different from their intrinsic structures.
[Fe iii] lines in the planetary nebula NGC 2392
Authors: Zhang Yong , Fang Xuan , Chau Wayne , Hsia Chin-Hao , Liu Xiao-Wei , Kwok Sun 
Published: August 2012

AbstractThe Eskimo Nebula (NGC 2392) is a young double-shell planetary nebula (PN). Its intrinsic structure and the responsible shaping mechanism are still not fully understood. We present new optical spectroscopy of NGC 2392 at two different locations to obtain the spectra of the inner and outer shells. Several [Fe iii] lines are clearly detected. We find that these [Fe iii] lines mostly originate from the inner shell. Therefore, we suggest that NGC 2392 might have an intrinsic structure similar to the Ant Nebula Mz 3, which exhibits a number of [Fe iii] lines from the central dense regions. In this scenario, the inner and outer shells correspond to the central emission core and the outer lobes of Mz 3, respectively.
Expression patterns reveal niche diversification in a marine microbial assemblage
Authors: Gifford Scott M , Sharma Shalabh , Booth Melissa , Moran Mary Ann 
Published: August 2012

Abstract
Resolving the ecological niches of coexisting marine microbial taxa is challenging due to the high species richness of microbial communities and the apparent functional redundancy in bacterial genomes and metagenomes. Here, we generated over 11 million Illumina reads of protein-encoding transcripts collected from well-mixed southeastern US coastal waters to characterize gene expression patterns distinguishing the ecological roles of hundreds of microbial taxa sharing the same environment. The taxa with highest in situ growth rates (based on relative abundance of ribosomal protein transcripts) were typically not the greatest contributors to community transcription, suggesting strong top-down ecological control, and their diverse transcriptomes indicated roles as metabolic generalists. The taxa with low in situ growth rates typically had low diversity transcriptomes dominated by specialized metabolisms. By identifying protein-encoding genes with atypically high expression for their level of conservation, unique functional roles of community members emerged related to substrate use (such as complex carbohydrates, fatty acids, methanesulfonate, taurine, tartrate, ectoine), alternative energy-conservation strategies (proteorhodopsin, AAnP, V-type pyrophosphatases, sulfur oxidation, hydrogen oxidation) and mechanisms for negotiating a heterogeneous environment (flagellar motility, gliding motility, adhesion strategies). On average, the heterotrophic bacterioplankton dedicated 7% of their transcriptomes to obtaining energy by non-heterotrophic means. This deep sequencing of a coastal bacterioplankton transcriptome provides the most highly resolved view of bacterioplankton niche dimensions yet available, uncovering a spectrum of unrecognized ecological strategies.
Source-Finding for the Australian Square Kilometre Array Pathfinder
Authors: Whiting M. , Humphreys B. 
Published: August 2012

AbstractThe Australian Square Kilometre Array Pathfinder (ASKAP) presents a number of challenges in the area of source finding and cataloguing. The data rates and image sizes are very large, and require automated processing in a high-performance computing environment. This requires development of new tools, that are able to operate in such an environment and can reliably handle large datasets. These tools must also be able to accommodate the different types of observations ASKAP will make: continuum imaging, spectral-line imaging, transient imaging. The ASKAP project has developed a source-finder known as selavy, built upon the duchamp source-finder. selavy incorporates a number of new features, which we describe here.Since distributed processing of large images and cubes will be essential, we describe the algorithms used to distribute the data, find an appropriate threshold and search to that threshold and form the final source catalogue. We describe the algorithm used to define a varying threshold that responds to the local, rather than global, noise conditions, and provide examples of its use. And we discuss the approach used to apply two-dimensional fits to detected sources, enabling more accurate parameterisation. These new features are compared for timing performance, where we show that their impact on the pipeline processing will be small, providing room for enhanced algorithms.We also discuss the development process for ASKAP source finding software. By the time of ASKAP operations, the ASKAP science community, through the Survey Science Projects, will have contributed important elements of the source finding pipeline, and the mechanisms in which this will be done are presented.
Diffusive racetrack oxidation in a Ti sputter target by reactive high power impulse magnetron sputtering
Authors: Audronis M , Abrasonis G , Munnik F , Heller R , Chapon P , Bellido-Gonzalez V 
Published: August 2012

Abstract
This paper reports experimental results for near-surface Ti sputter target oxidation in a magnetron racetrack during reactive high power impulse magnetron sputtering (HIPIMS) at various optical plasma monitoring set-points in the transition region between ‘metal’ and ‘poisoned’ target states. Oxygen depth profiles were obtained by nuclear reaction analysis and glow discharge optical emission spectroscopy. Ti target surface oxidation depth as induced by reactive HIPIMS was found to depend on the process set-point as well as discharge conditions. Deepest oxidation was observed when operating close to ‘fully poisoned (FP)’ or in ‘FP’ regime with oxygen profiles extending as deep as ∼0.5 µm (oxygen concentration ⩾5 at%). Oxygen profiles obtained indicate the occurrence of oxygen bulk diffusion. Process induced elevated target surface temperature, magnetic field and plasma assistance are suggested to contribute substantially to these profiles. Based on these findings it is proposed that ion-bombardment-assisted thermal diffusion is a third target poisoning mechanism that can be taking place and is therefore important in reactive HIPIMS in addition to the two currently accepted mechanisms—ion implantation and chemisorption. Under the conditions investigated in this work, diffusive oxidation was most significant when operating in the lower part of the hysteresis loop. Reactive HIPIMS processes that will facilitate significant diffusive sputter target surface oxidation will also be expected to exhibit wider hysteresis and longer target cleaning times after substantial target poisoning.
Nonvolatile bipolar resistive switching in an Ag/TiO2/Nb : SrTiO3/In device
Authors: Zhu Yongdan , Li Meiya , Zhou Hai , Hu Zhongqiang , Liu Xiaolian , Fang Xiaoli , Sebo Bobby , Fang Guojia , Zhao Xingzhong 
Published: August 2012

Abstract
A TiO2 thin film was deposited on a Nb : SrTiO3 substrate by pulsed laser deposition to form an Ag/TiO2/Nb : SrTiO3/In device. The bipolar resistive switching (RS) effect of this device was investigated. The current–voltage characteristics exhibited pronounced and stable bipolar RS features. The device could be switched to a low resistance state (LRS) at forward voltage and returned to a high resistance state (HRS) at reverse voltage, and the RS ratio R
HRS/R
LRS reached up to 2 × 103 at a read voltage of −0.5 V. Moreover, the RS ratio could be adjusted by changing the maximum value of the forward or reverse voltage, which shows promise for multilevel memories. These results are discussed by considering carrier injection-trapped/detrapped process of the heterostructure and show high potential for nonvolatile memory applications.
Synthesis of an embedded metal nanoparticle planar assembly by low-energy ion irradiation of a thin discontinuous metal film sandwiched in silica
Authors: Khan Saif A , Srivastava S K , Avasthi D K 
Published: August 2012

Abstract
Synthesis of a planar assembly of metal nanoparticles embedded in silica by low-energy ion irradiation is presented here. Argon ions of 350 keV were used to irradiate SiO2/Au/SiO2 and SiO2/Ag/SiO2 tri-layered films, with oxide thicknesses of 40 nm and metal layer thickness of 2 nm, to synthesize well isolated nanoparticles without the need of annealing. The nanoparticles have an average diameter of about 6 nm as revealed by transmission electron microscopy. Simulations by three-dimensional kinetic lattice Monte Carlo were performed to understand the ion-induced nanoparticle array formation from the initially percolated as-deposited metal layer embedded in the silica matrix.
Biologistics—Diffusion coefficients for complete proteome of Escherichia coli
Authors: Kalwarczyk Tomasz , Tabaka Marcin , Holyst Robert 
Published: September 2012

Abstract
Motivation: Biologistics provides data for quantitative analysis of transport (diffusion) processes and their spatio-temporal correlations in cells. Mobility of proteins is one of the few parameters necessary to describe reaction rates for gene regulation. Although understanding of diffusion-limited biochemical reactions in vivo requires mobility data for the largest possible number of proteins in their native forms, currently, there is no database that would contain the complete information about the diffusion coefficients (DCs) of proteins in a given cell type.
Results: We demonstrate a method for the determination of in vivo DCs for any molecule—regardless of its molecular weight, size and structure—in any type of cell. We exemplify the method with the database of in vivo DC for all proteins (4302 records) from the proteome of K12 strain of Escherichia coli, together with examples of DC of amino acids, sugars, RNA and DNA. The database follows from the scale-dependent viscosity reference curve (sdVRC). Construction of sdVRC for prokaryotic or eukaryotic cell requires ~20 in vivo measurements using techniques such as fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), nuclear magnetic resonance (NMR) or particle tracking. The shape of the sdVRC would be different for each organism, but the mathematical form of the curve remains the same. The presented method has a high predictive power, as the measurements of DCs of several inert, properly chosen probes in a single cell type allows to determine the DCs of thousands of proteins. Additionally, obtained mobility data allow quantitative study of biochemical interactions in vivo.
Contact: rholyst@ichf.edu.pl
Supplementary information: Supplementary data are available at Bioinformatics Online.