bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology evolution of MOCVD grown GaN epitaxial layers on nanoPSS
Authors: Jiang Xianzhe , Chen Zhizhong , Li Junze , Jiang Shuang , Kang Xiangning , Zhang Guoyi 
Published: February 2014

AbstractNanoscale patterned sapphire substrates (NPSS) were fabricated through nanoimprint lithography (NIL) technology and etching treatment. With optimized growth conditions, high‐quality GaN epilayers were epitaxially grown by commercial metal organic chemical vapor deposition (MOCVD) system. Structural and optical properties were studied. Better imprint stamp as well as faster transition between different growth modes during lateral epitaxial growth were found to be two important factors that improve the crystal quality and reduce the density of the defects. A new kind of irregular circular mesas was observed with random distribution, which may come from accelerated growth by template imperfection. Considering the evolution of pattern size and density, possible origin of such structure has been proposed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pulsed modulation doping of AlxGa1‐xN (x>0.6) AlGaN epilayers for deep UV optoelectronic devices
Authors: Chen Hung‐Chi , Ahmad Iftikhar , Zhang Bin , Coleman Antwon , Sultana Mahbuba , Adivarahan Vinod , Khan Asif 
Published: February 2014

AbstractWe report a new approach of pulsed modulation doping (PMD) to achieve n‐type doping in AlxGa1‐xN (x>0.6) layers. In this approach silane flow is cyclically modulated during n‐AlGaN growth which enable us to grow low dislocation density n‐AlGaN templates for UV (λ ∼ 280 nm) LEDs. We observed that dislocation density for un‐doped AlGaN layers on high quality AlN layers is 3.3×108cm‐2. This dislocation density was increased to 2.3×109 cm–2 for conventionally grown n‐AlGaN layers on AlGaN templates. We were able to reduced dislocation density in n‐AlGaN layers to 3.5×108cm–2 using PMD of n‐AlGaN layers. The dislocation densities in these samples were studies using etch pit density (EPD) and Williamson and Hall studies. A comparative study of LED structures on conventional and PMD doped n‐AlGaN showed improved performance for LED emitting at 280 nm for LED structure on PMD n‐doped AlGaN layers. In this paper the details of our growth procedure, the epi‐structure X‐ray, AFM, and other characterizations will be presented. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A cable neck‐restraint to live‐capture coyotes
Authors: Wegan Michael T. , Etter Dwayne R. , Belant Jerrold L. , Beyer Dean E. , Svoboda Nathan J. , Petroelje Tyler R. 
Published: February 2014

ABSTRACTWe evaluated a cable neck‐restraint for live capture of coyotes (Canis latrans) in Michigan, USA, from 6 January to 22 March 2011. We documented capture efficiency, selectivity, and animal welfare using criteria developed by the Association of Fish and Wildlife Agencies Best Management Practices and the International Organization for Standardization. We constructed cable restraints with an 8.9‐cm‐diameter minimum loop stop and reverse bend washer locks drilled to 4.8 mm, to more readily relax on 2.4‐mm‐diameter steel cable. Cable restraints were set for 938 trap‐nights during January–March 2011. Capture efficiency was 71.4% (n = 20 coyotes) and selectivity 95.0%. We performed necropsies (n = 11) or external examinations (n = 9) to evaluate capture‐related injuries and released coyotes fitted with Global Positioning System collars (n = 5) to estimate home‐range size. Mean individual injury score of necropsied coyotes was 5.0 ± SD 8.9 and mean total injury score was 7.3 ± SD 9.8; we observed no mortality of coyotes due to capture. Home range sizes of 2 coyotes (8.9 km2 and 16.6 km2) were within the 95% confidence interval of mean home‐range size of resident coyotes captured in foothold traps (16.0 km2 ± SD 5.7, n = 11). Our findings indicate this cable restraint configuration exceeds all Best Management Practices criteria and is suitable for the capture of coyotes in both wildlife management and research arenas. © 2014 The Wildlife Society.
Modification of Stearidonic Acid Soybean Oil by Immobilized Rhizomucor miehei Lipase to Incorporate Caprylic Acid
Authors: Ifeduba Ebenezer A. , Akoh Casimir C. 
Published: February 2014

AbstractImmobilized sn‐1,3 specific Rhizomucor miehei lipase (RML) was used to catalyze the incorporation of caprylic acid (C8:0) into high stearidonic acid (SDA, C18:4ω3) soybean oil (SDASO) to form structured lipids (SL). The effects of type of biocatalyst (Celite‐, octyl‐Sepharose‐, and Duolite‐immobilized RML) and reaction temperature (30, 40, 50, and 60 °C) on acidolysis and acyl migration were studied. Celite‐immobilized RML (C‐RML) at 50 °C maximized C8:0 incorporation and minimized acyl migration compared to other treatments. Optimal levels of substrate molar ratio (C8:0 to SDASO), incubation time, and enzyme load for SL synthesis by C‐RML at 50 °C was determined by response surface methodology to be 6:1, 24 h, and 20 % weight of substrates, respectively. This optimum treatment was scaled‐up in hexane or solvent‐free reaction media using SDASO or an SDA‐enriched acylglycerol mixture as substrate. This yielded various SL with C8:0 contents ranging from 17.0 to 32.5 mol% and SDA contents ranging from 20.6 to 42.3 mol%. When digested, these SL may deliver C8:0 for quick energy and SDA for heart health making them potentially valuable for medical and nutraceutical applications.
Is stress perceived differently in relationships with parents and peers? Inter‐ and intra‐regional comparisons on adolescents from 21 nations
Authors: Persike Malte , Seiffge‐Krenke Inge 
Published: February 2014

ABSTRACTThis study investigated how adolescents (mean age of 15 years) from 21 countries perceived parent‐ and peer‐related stress. Across countries, adolescents perceived parent‐related stress at considerably greater levels than peer‐related stress. Adolescents assigned to six geographical regions differed significantly in overall stress levels as well as in the disparity between perceived stress levels in the parent and peer domain. Regional comparisons revealed that adolescents from Southern Europe exhibited the highest levels of parent‐related stress, followed by adolescents from Latin America, the Middle East, and Asia. The stress levels of adolescents from Central European and North American countries were generally quite low. Correspondence analyses revealed distinctive patterns of perceived stress in close relationships, depending on the region. The discussion focuses on different parental styles and cultural values as potential influential factors for differences in stress perception between regions.
COMMUNITY SOCIOECONOMIC CONTEXT AND ITS INFLUENCE ON INTERMEDIARY DETERMINANTS OF CHILD HEALTH: EVIDENCE FROM COLOMBIA
Authors: OSORIO ANA MARÍA , BOLANCÉ CATALINA , MADISE NYOVANI 
Published: February 2014

SummaryIntermediary determinants are the most immediate mechanisms through which socioeconomic position shapes health inequities. This study examines the effect of community socioeconomic context on different indicators representing intermediary determinants of child health. In the context of Colombia, a developing country with a clear economic expansion, but one of the most unequal countries in the world, two categories of intermediary determinants, namely behavioural and psychosocial factors and the health system, are analysed. Using data from the 2010 Colombian Demographic and Health Survey (DHS), the results suggest that whilst the community context can exert a greater influence on factors linked directly to health, in the case of psychosocial factors and parent's behaviours, the family context can be more important. In addition, the results from multilevel analysis indicate that a significant percentage of the variability in the overall index of intermediary determinants of child health is explained by the community context, even after controlling for individual, family and community characteristics. These findings underline the importance of distinguishing between community and family intervention programmes in order to reduce place-based health inequities in Colombia.
When governments support poaching: a review of the illegal trapping of thrushesTurdusspp. in theparanyof Comunidad Valenciana, Spain
Authors: MURGUI ENRIQUE 
Published: February 2014

SummaryTheparanyis a device used in Comunidad Valenciana (Spain) for trapping birds by the use of limed sticks. Between 1988 and 2001 successive Comunidad Valenciana governments authorised the legal trapping of thrushesTurdusspp. in 5,000paranyeach year. Approximately 1.5 million thrushes (mostly Song ThrushTurdus philomelosand RedwingT. iliacus) along with half a million birds of many protected species (including raptors) were trapped annually. Authorisation ceased in 2001 but illegal trapping still occurs, using at least 2,000parany. Comunidad Valenciana governments have explicitly supported bird trapping on both legal and technical grounds claiming that only small numbers of thrushes are caught and that other species are unaffected, thus complying with the EU Birds Directive. Such assertions have never been proven, and regional, national and international courts have declared that theparanycontravenes nature protection laws. Comunidad Valenciana governments have deliberately overlooked such judgements. It is concluded that eradication ofparanythrough law enforcement and educational schemes would be the best option. Nevertheless, according to the EU Birds Directive, controlled bird trapping would be feasible, and the requisites for such a strategy are discussed. The main obstacle to both eradication and strictly controlled use ofparanyis the lack of political will by Comunidad Valenciana governments.
Near-IR Diffuse Interstellar Bands in SDSS-III APOGEE Spectra
Authors: Zasowski G. , Ménard B. 
Published: February 2014

AbstractUsing high resolution H-band spectra from first-year observations of the SDSS-III APOGEE survey, we have searched for the presence of Diffuse Interstellar Bands (DIBs) towards several thousand stars and obtained ~7 000 robust detections spanning a broad range of Galactic environments. This represents the largest homogeneous sample of DIB systems in terms of both size and sky coverage, which can be used for various statistical studies. For example, we find the strength of the most prominent near-IR DIB (at 1.5723 μm) to be strongly correlated with line-of-sight dust extinction, and its apparent velocity appears to trace that of the Galactic CO emission. The ability to work at near-IR wavelengths allows us to probe lines of sight penetrating through the dusty disk of the Galaxy, spanning a range of about 8 magnitudes of extinction. This preliminary investigation illustrates how a large sample of DIBs can serve as a useful tool to probe the structure of the Galaxy and the chemistry of the interstellar medium.
Diffuse Interstellar Bands in M33
Authors: Smith K. T. , Cordiner M. A. , Evans C. J. , Cox N. L. J. , Sarre P. J. 
Published: February 2014

AbstractWe present the first sample of diffuse interstellar bands (DIBs) in the nearby galaxy M33. Studying DIBs in other galaxies allows the behaviour of the carriers to be examined under interstellar conditions which can be quite different from those of the Milky Way, and to determine which DIB properties can be used as reliable probes of extragalactic interstellar media. Multi-object spectroscopy of 43 stars in M33 has been performed using Keck/DEIMOS. The stellar spectral types were determined and combined with literature photometry to determine the M33 reddenings E(B-V)M33. Equivalent widths or upper limits have been measured for the λ5780 DIB towards each star. DIBs were detected towards 20 stars, demonstrating that their carriers are abundant in M33. The relationship with reddening is found to be at the upper end of the range observed in the Milky Way. The line of sight towards one star has an unusually strong ratio of DIB equivalent width to E(B-V)M33, and a total of seven DIBs were detected towards this star.
X-Shooter Survey of Near-Infrared DIBs
Authors: Cox N. L. J. , Cami J. , Kaper L. , Foing B. H. , Ehrenfreund P. , Ochsendorf B. B. , van Hooff S. H. M. , Salama F. 
Published: February 2014

AbstractWe present the first results of an exploratory VLT/X-Shooter survey of near-infrared diffuse interstellar bands (DIBs) in diffuse to translucent interstellar clouds. These observations confirm the presence of recently discoved NIR DIBs and provide more accurate rest wavelengths and line widths. Example spectra are shown for the reddened, AV ~ 10 mag, line-of-sight towards the distant binary system 4U 1907+09.
Automated Extraction of DIBs from Cool Star Spectra
Authors: Chen H.-Ch. , Lallement R. , Puspitarini L. , Bonifacio P. , Babusiaux C. , Hill V. 
Published: February 2014

AbstractWe have developed a method allowing to extract DIBs from cool star spectra, based on combinations of stellar synthetic, telluric transmission (when necessary), and DIB profile models. It is applicable when the star temperature, surface gravity and metallicity have been previously estimated. Such a method aims at extracting extensive data from stellar spectroscopic surveys such as the Gaia-ESO Survey in progress at the VLT. The method has been applied to several strong DIBs detected towards stars from various programs and located at various distances from the solar neighborhood to the Galactic Bulge. Here we illustrate the extraction of the 8620 Å DIB, and compare its strength to the one of the 6284 Å band, both for nearby and bulge stars.
First Results from a Study of DIBs with Thousands of High-Quality Massive-Star Spectra
Authors: Apellániz J. Maíz , Sota A. , Barbá R. H. , Morrell N. I. , Pellerin A. , Alfaro E. J. , Simón-Díaz S. 
Published: February 2014

AbstractWe are using five different surveys to compile the largest sample of diffuse interstellar band (DIB) measurements ever collected. GOSSS is obtaining intermediate-resolution blue-violet spectroscopy of ~2500 OB stars, of which 60% have already been observed and processed. The other four surveys have already collected multi-epoch high-resolution optical spectroscopy of 700 OB stars with different telescopes, including the 9 m Hobby-Eberly Telescope in McDonald Observatory. Some of our stars are highly-extinguished targets for which no good-quality optical spectra have ever been published. For all of the targets in our sample we have obtained accurate spectral types, measured non-DIB ISM lines, and compiled information from the literature to calculate the extinction. Here we present the first results of the project, the properties of twenty DIBs in the 4100-5500 Å range. We clearly detect a couple of previously elusive DIBs at 4170 Å and 4591 Å; the latter could have coronene and ovalene cations as carriers.
Behaviour of the Broadest DIBs as a Function of E(B–V)
Authors: York B. , Sonnentrucker P. , Hobbs L. M. , York D. G. , Friedman S. D. , Dahlstrom J. , Welty D. E. , Snow T. P. , Rachford B. L. 
Published: February 2014

AbstractWe present the first results of a dedicated search for Diffuse Interstellar Bands that have profiles with FWHM > 6 Å. Broad DIBs have been noticed in past surveys using averages of multiple sight lines (e.g. Jenniskens & Désert, 1994), but careful detection, measurement, and cataloguing for individual sight lines has not been done since the pioneering work of Herbig (1995). We have initiated an observing campaign using the Apache Point Observatory in order to obtain low-resolution spectra to search for such broad DIBs and monitor their behaviour from star to star. A first sample of 21 stars with 0.3 < E(B-V) < 3.3 mag, along with 15 matched low-reddening stars, were observed with the APO/DIS B400 (R ~ 450) and R300 (R ~ 1000) gratings to obtain spectra having S/N > 500.
Blue Luminescence and Extended Red Emission: Possible Connections to the Diffuse Interstellar Bands
Authors: Witt A. N. 
Published: February 2014

AbstractBlue luminescence (BL) and extended red emission (ERE) are observed as diffuse, optical-wavelength emissions in interstellar space, resulting from photoluminescence by ultraviolet(UV)-illuminated interstellar grains. Faintness and the challenge of separating the BL and ERE from the frequently much brighter dust-scattered continuum present major observational hurdles, which have permitted only slow progress in testing the numerous models that have been advanced to explain these two phenomena. Both the ERE, peaking near 680 nm (FWHM ~ 60 - 120 nm) and the BL, asymmetrically peaking at ~ 378 nm (FWHM ~ 45 nm), were first discovered in the Red Rectangle nebula. Subsequently, ERE and BL have been observed in other reflection nebulae, and in the case of the ERE, in carbon-rich planetary nebulae, H II regions, high-latitude cirrus clouds, the galactic diffuse ISM, and in external galaxies. BL exhibits a close spatial and intensity correlation with emission in the aromatic emission feature at 3.3 micron, most likely arising from small, neutral polycyclic aromatic hydrocarbon (PAH) molecules. The spectral characteristics of the BL also agree with those of fluorescence by PAH molecules with 13 to 19 carbon atoms. The BL phenomenon is thus most readily understood as the optical fluorescence of small, UV-excited aromatic molecules. The ERE, by contrast, though co-existent with mid-IR PAH emissions, does not correlate with emissions from either neutral or ionized PAHs. Instead, the spatial ERE morphology appears to be strictly governed by the density of far-UV (E ≥ 10.5 eV) photons, which are required for the ERE excitation. The most restrictive observational constraint for the ERE process is its exceptionally high quantum efficiency. If the ERE results from photo-excitation of a nano-particle carrier by photons with E ≥ 10.5 eV in a single-step process, the quantum efficiency exceeds 100%. Such a process, in which one to three low-energy optical photons may be emitted following a single far-UV excitation, is possible in highly isolated small clusters, e.g. small, dehydrogenated carbon clusters with about 20 to 28 carbon atoms. A possible connection between the ERE carriers and the carriers of DIBs may exist in that both are ubiquitous throughout the diffuse interstellar medium and both have an abundance of low-lying electronic levels with E ≤ 2.3 eV above the ground state.
Herschel/HIFI Discoveryof a Far-Infrared DIB Analog
Authors: Müller H. S. P. , Schilke P. , Gerin M. , Lis D. C. , Bergin E. A. , Pearson J. C. , De Luca M. , Black J. H. 
Published: February 2014

AbstractThe Herschel Space Observatory carried out observations at far-infrared wavelengths, which significantly increased our knowledge of the interstellar medium and the star-formation process in the Milky Way and external galaxies, as well as our understanding of astrochemistry.Absorption features, known, e.g., from observations at millimeter wavelengths, are more commonly observed in the far-infrared, in particular toward strong dust continuum sources. The lowest energy transitions are not only observed at LSR-velocities related to the source, but often also at velocities associated with diffuse molecular clouds along the line of sight toward the background source.Unbiased spectral line surveys of the massive and very luminous Galactic Center sources Sagittarius B2(M) and (N) were carried out across the entire frequency range of the high-resolution Heterodyne Instrument for Far-Infrared Astronomy (HIFI). An absorption feature was detected toward both sources at about 617.531 GHz, corresponding to 20.599 cm−1, 485.47 μm, or 2.5539 meV. This feature is unique in its appearance at all velocity components associated with diffuse foreground molecular clouds, together with its conspicuous absence at velocities related to the sources themselves. The carriers of at least a substantial part of the DIBs are thought to reside in the diffuse interstellar medium. Therefore, we consider this absorption feature to be a far-infrared DIB analog.Subsequent dedicated observations confirmed that the line is present only in the foreground clouds on the line of sight toward other massive star-forming regions in the Galactic disk. There is indication that the feature has substructure, possibly of fine or hyperfine nature. Attempts to assign the feature to atomic or molecular species have been unsuccessful so far.
λ4430 Emission by Comet Hyakutake
Authors: A'Hearn M. F. , Wellnitz D. D. , Meier R. 
Published: February 2014

AbstractComets provide a very different but well understood environment in which to search for DIBs. Observations of occultations by cometary comae have not detected DIBs, but none were very near the nucleus, where the column density of dust is highest. We report here unidentified emission bands, centered at λ4430, very near the nucleus of comet Hyakutake. These may be vaporized forms of grain carriers or fragments of large-molecule carriers. At least two different species appear to be present based on two different spatial distributions.
Kinematic Distance of Galactic Radio Objects
Authors: Zhu H. , Tian W. , Su H. , Wu D. 
Published: February 2014

AbstractWe briefly summarize the method of kinematic distances of Galactic radio objects and discuss the ambiguity in this method. Both Hi absorption and Hi self-absorption are effective tools to solve the kinematic distance ambiguity. We build the 21 cm Hi absorption spectrum of the complex G35.6-0.5, and suggest SNR G35.6-0.4, one component of the complex, is located at the near side distance of about 3.6 kpc.
Laboratory Spectroscopy of PAHs
Authors: Pino T. , Féraud G. , Bréchignac Ph. , Bieske E. J. , Schmidt T. W. 
Published: February 2014

AbstractSpectroscopic investigations of PAHs have been conducted for many years, commencing with solid and solution studies and more recently including gas phase characterisation of a broad range of different species. Through the development of new, efficient methods of production and more sensitive spectroscopic techniques, fresh data are becoming available for not only neutral species, but also for radicals, ions and clusters.
Broadband Cavity Enhanced Absorption Spectroscopy: A New Approach to Search for DIB Carriers
Authors: Walsh A. J. , Zhao D. , Ubachs W. , Linnartz H. 
Published: February 2014

AbstractA new and sensitive set-up to swiftly test proposed carriers of the diffuse interstellar bands (DIBs), over a relatively broad spectral range, is described. The instrument utilizes broad-band cavity enhanced absorption spectroscopy (BBCEAS) and incorporates an optomechanical shutter to modulate light from a continuous incoherent light source. A pulsed supersonically expanding planar plasma expansion is used to mimic conditions in translucent interstellar clouds. Measurements of plasma durations as low as 400 μs are possible. The sensitivity is estimated to be better than 10 ppm/pass, measured with an effective exposure time of only ca. 1 s. The performance and potential of the instrument is demonstrated on spectra of C5H, C6H and C9H3 recorded through expanding hydrocarbon plasma.
Carbon Interstellar Chemistry: Theory versus Observations
Authors: Wakelam V. 
Published: February 2014

AbstractTo study the interstellar chemical composition and interpret molecular observations, astrochemists have built chemical models over the years. Those models compute the composition of the gas and the icy mantles of interstellar grains taking in account a large number of processes, such as chemical reactions in the gas-phase, interactions with grain surfaces (sticking and evaporation) and chemical reactions at the surface of the grains. Those models rely on a number of parameters (physical parameters of the medium and intrinsic chemical parameters such as rate coefficients), which are estimated with an associated uncertainty. From a chemical point of view, those uncertainties are mainly due to an incomplete knowledge of the efficiency of the processes in the interstellar conditions. Many studies in the recent and past years have been undertaken to improve this knowledge, either using experimental or theoretical results in physico-chemistry.