bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trigonometric Parallax of the Protoplanetary Nebula OH 231.8+4.2
Authors: Choi Y. K. , Brunthaler A. , Menten K. M. , Reid M. J. 
Published: July 2012

AbstractWe report a trigonometric parallax measurement for the H2O masers around the protoplanetary nebula OH 231.8+4.2 carried out with the Very Long Baseline Array (VLBA). Based on astrometric monitoring for 1 year, we measured a parallax of 0.65 ± 0.01 mas, corresponding to a distance of 1.54 +0.02−0.01 kpc. The spatial distribution of H2O masers is consistent with that found in the previous studies. After removing the average proper motion of 1.4 mas yr−1, corresponding to 10 km s−1, the internal motions of the H2O maser spots indicate a bipolar outflow.
Annual Parallax Measurements of an Infrared Dark Cloud MSXDC G034.43+00.24
Authors: Kurayama Tomoharu 
Published: July 2012

AbstractWe have measured the annual parallax of the H2O maser associated with an infrared dark cloud, MSXDC G034.43+00.24, with VERA. The parallax is 0.643 ± 0.049 mas, corresponding to a distance of 1.56+0.12−0.11 kpc. This value is less than half of the previous kinematic distance of 3.7 kpc. We revised the core-mass estimates of MSXDC G034.43+00.24 from the previous estimations of 1000M⊙ to hundreds of M⊙. The spectral type is still consistent with that of the massive star.
Distance and Maser Outflows of the Galactic Star-forming Region W51 Main/South
Authors: Sato Mayumi , Reid Mark J. , Brunthaler Andreas , Menten Karl M. 
Published: July 2012

AbstractWe report on high-resolution astrometry of 22 GHz H2O maser emission in the Galactic massive star-forming region W51 Main/South using the Very Long Baseline Array. We measured the trigonometric parallax of W51 Main/South to be 0.185 ± 0.010 mas, corresponding to a distance of 5.41+0.31−0.28 kpc. The H2O maser emission in W51 Main/South traces four powerful bipolar outflows within a 0.4 pc size region, three of which are associated with dusty molecular hot cores and/or hyper- or ultra-compact Hii regions. The maser outflows in W51 Main/South have a relatively small range of internal 3D speeds, suggesting that multiple speed maser outflows in other Galactic massive star-forming regions may come from separate young stellar objects closely spaced on the sky.
Trigonometric Parallax of RCW 122
Authors: Wu Y. W. , Xu Y. , Menten K. M. , Zheng X. W. , Reid M. J. 
Published: July 2012

AbstractAs a part of the BeSSeL (Bar and Spiral Structure Legacy) survey, we report a trigonometric parallax for the massive star-forming region G348.70–1.04. Its distance is 3.38−0.27+0.33 kpc, indicating that it is in the Scutum-Centaurus arm. Its proper motion is −0.73 ± 0.04 mas yr−1 toward the east and −2.83 ± 0.50 mas yr−1 toward the north.
New class I methanol masers
Authors: Voronkov M. A. , Caswell J. L. , Ellingsen S. P. , Breen S. L. , Britton T. R. , Green J. A. , Sobolev A. M. , Walsh A. J. 
Published: July 2012

AbstractWe review properties of all known collisionally pumped (class I) methanol maser series based on observations with the Australia Telescope Compact Array (ATCA) and the Mopra radio telescope. Masers at 36, 84, 44 and 95 GHz are most widespread, while 9.9, 25, 23.4 and 104 GHz masers are much rarer, tracing the most energetic shocks. A survey of many southern masers at 36 and 44 GHz suggests that these two transitions are highly complementary. The 23.4 GHz maser is a new type of rare class I methanol maser, detected only in two high-mass star-forming regions, G357.97-0.16 and G343.12-0.06, and showing a behaviour similar to 9.9, 25 and 104 GHz masers. Interferometric positions suggest that shocks responsible for class I masers could arise from a range of phenomena, not merely an outflow scenario. For example, some masers might be caused by interaction of an expanding Hii region with its surrounding molecular cloud. This has implications for evolutionary sequences incorporating class I methanol masers if they appear more than once during the evolution of the star-forming region. We also make predictions for candidate maser transitions in the ALMA frequency range.
OH Masers and Supernova Remnants
Authors: Wardle Mark , McDonnell Korinne 
Published: July 2012

AbstractOH(1720 MHz) masers are created by the interaction of supernova remnants with molecular clouds. These masers are pumped by collisions in warm, shocked molecular gas with OH column densities in the range 1016–1017, cm−2. Excitation calculations suggest that inversion of the 6049 MHz OH line may occur at the higher column densities that have been inferred from main-line absorption studies of supernova remnants with the Green Bank Telescope. OH(6049 MHz) masers have therefore been proposed as a complementary indicator of remnant-cloud interaction.This motivated searches for 6049 MHz maser emission from supernova remnants using the Parkes 63 m and Effelsberg 100 m telescopes, and the Australia Telescope Compact Array. A total of forty-one remnants have been examined by one or more of these surveys, but without success. To check the accuracy of the OH column densities inferred from the single-dish observations we modelled OH absorption at 1667 MHz observed with the Very Large Array towards three supernova remnants, IC 443, W44 and 3C 391. The results are mixed – the OH column is revised upwards in IC443, downwards in 3C391, and is somewhat reduced in W44. We conclude that OH columns exceeding 1017 cm−2 are indeed present in some supernova remnants and so the lack of any detections is not explained by low OH column density. We discuss the possibility that non-local line overlap is responsible for suppressing the inversion of the 6049 MHz line.
Unveiling the kinematics of the disk and the ionized stellar wind of the massive star MWC349A through RRL masers
Authors: Báez-Rubio Alejandro , Martín-Pintado Jesús 
Published: July 2012

AbstractThe kinematics of photoevaporating disks and their associated ionized outflows around massive stars are fundamental to understand how these stars are formed and they evolve in their early phases of their evolution. To date, the important advances have been provided by studying the UC-HII region of MWC349A thanks to their strong maser emission at Hydrogen radio-recombination lines (RRLs). This B[e] star is one of the best prototypes of massive star with an ionized outflow expanding at nearly constant velocity. A 3D radiative transfer model applied to the H30α line has allowed to constrain the disk kinematics, which seems to follow pure Keplerian rotation in its outer parts. The model has also allowed us to constraints the launching radius of the outflow. Our results are supported by the agreement of our model predictions with the observations for other observed RRLs. Recent high-frequency observations of RRL masers with the Herschel Space Telescope (HIFI) show that the kinematics of the disk inner regions is not well understood. Modeling of these lines will constrain the formation of the ionized winds.
Intrinsic Sizes of the W3 (OH) Masers via Short Time Scale Variability
Authors: Laskar Tanmoy , Goss W. M. , Zauderer B. Ashley 
Published: July 2012

AbstractWe present a study of short time-scale variability of OH masers within a contiguous 15-hour Very Long Baseline Array observation of the high-mass star-forming region, W3 (OH). With an angular resolution of ~7 mas and a velocity resolution of 53 m s−1, we isolate emission from masers in the field into individual Gaussian-shaped components, each a few milliarcseconds in size. We compute dynamic spectra for individual maser features with a time resolution of 1 minute by fitting for the flux density of all sources in the field simultaneously in the uv-domain. We isolate intrinsic maser variability from interstellar scintillation and instrumental effects. We find fluctuations in the maser line shape on time scales of 5 to 20 minutes, corresponding to maser column lengths of 0.5 to 2.0 Astronomical Units.
Methanol masers in the Herschel era Putting them in the star formation context
Authors: Pestalozzi Michele 
Published: July 2012

AbstractMethanol masers are known to be among the most reliable tracers of high-mass stars in early stages of evolution. A number of searches across the Galaxy has yielded to date, a complete census of those masers in two thirds of the Milky Way, providing a catalogue of some 800 sources to be studied in depth. In particular, it is important to characterise the physical properties of the objects hosting methanol masers, and this is possible today using data from the Herschel Space Observatory (HSO). The exceptional spatial resolution of HSO and its wavelength coverage are perfectly tuned to put the methanol maser phase into its star formation context. This paper presents results on the characterisation of methanol maser hosts using Herschel data from the Hi-GAL project, an Open Time Key Project to survey the inner Galactic plane at 5 wavelengths between 70 and 500 μm.
Early results from a diagnostic 1.3 cm survey of massive young protostars
Authors: Brogan Crystal L. , Hunter Todd R. , Cyganowski Claudia J. , Indebetouw Remy , Friesen Rachel , Chandler Claire 
Published: July 2012

AbstractWe have used the recently-upgraded Karl G. Jansky Very Large Array (JVLA) to conduct a K-band (~24 GHz) study of 22 massive young stellar objects in 1.3 cm continuum and a comprehensive set of diagnostic lines. This survey is unique in that it samples a wide range of massive star formation signposts simultaneously for the first time. In this proceeding we present preliminary results for the 11 sources in the 2-4 kpc distance bin. We detect compact NH3 cores in all of the fields, with many showing emission up through the (6,6) transition. Maser emission in the 25 GHz CH3OH ladder is present in 7 of 11 sources. We also detect non-thermal emission in the NH3 (3,3) transition in 7 of 11 sources.
Effects of variable magma supply on mid‐ocean ridge eruptions: Constraints from mapped lava flow fields along the Galápagos Spreading Center
Authors: Colman Alice , Sinton John M. , White Scott M. , McClinton J. Timothy , Bowles Julie A. , Rubin Kenneth H. , Behn Mark D. , Cushman Buffy , Eason Deborah E. , Gregg Tracy K. P. , Grönvold Karl , Hidalgo Silvana , Howell Julia , Neill Owen , Russo Chris 
Published: July 2012

Mapping and sampling of 18 eruptive units in two study areas along the Galápagos Spreading Center (GSC) provide insight into how magma supply affects mid‐ocean ridge (MOR) volcanic eruptions. The two study areas have similar spreading rates (53 versus 55 mm/yr), but differ by 30% in the time‐averaged rate of magma supply (0.3 × 106 versus 0.4 × 106 m3/yr/km). Detailed geologic maps of each study area incorporate observations of flow contacts and sediment thickness, in addition to sample petrology, geomagnetic paleointensity, and inferences from high‐resolution bathymetry data. At the lower‐magma‐supply study area, eruptions typically produce irregularly shaped clusters of pillow mounds with total eruptive volumes ranging from 0.09 to 1.3 km3. At the higher‐magma‐supply study area, lava morphologies characteristic of higher effusion rates are more common, eruptions typically occur along elongated fissures, and eruptive volumes are an order of magnitude smaller (0.002–0.13 km3). At this site, glass MgO contents (2.7–8.4 wt. %) and corresponding liquidus temperatures are lower on average, and more variable, than those at the lower‐magma‐supply study area (6.2–9.1 wt. % MgO). The differences in eruptive volume, lava temperature, morphology, and inferred eruption rates observed between the two areas along the GSC are similar to those that have previously been related to variable spreading rates on the global MOR system. Importantly, the documentation of multiple sequences of eruptions at each study area, representing hundreds to thousands of years, provides constraints on the variability in eruptive style at a given magma supply and spreading rate.
Heat flow in the Lesser Antilles island arc and adjacent back arc Grenada basin
Authors: Manga Michael , Hornbach Matthew J. , Le Friant Anne , Ishizuka Osamu , Stroncik Nicole , Adachi Tatsuya , Aljahdali Mohammed , Boudon Georges , Breitkreuz Christoph , Fraass Andrew , Fujinawa Akihiko , Hatfield Robert , Jutzeler Martin , Kataoka Kyoko , Lafuerza Sara , Maeno Fukashi , Martinez‐Colon Michael , McCanta Molly , Morgan Sally , Palmer Martin R. , Saito Takeshi , Slagle Angela , Stinton Adam J. , Subramanyam K. S. V. , Tamura Yoshihiko , Talling Peter J. , Villemant Benoit , Wall‐Palmer Deborah , Wang Fei 
Published: July 2012

Using temperature gradients measured in 10 holes at 6 sites, we generate the first high fidelity heat flow measurements from Integrated Ocean Drilling Program drill holes across the northern and central Lesser Antilles arc and back arc Grenada basin. The implied heat flow, after correcting for bathymetry and sedimentation effects, ranges from about 0.1 W/m2 on the crest of the arc, midway between the volcanic islands of Montserrat and Guadeloupe, to <0.07 W/m2 at distances >15 km from the crest in the back arc direction. Combined with previous measurements, we find that the magnitude and spatial pattern of heat flow are similar to those at continental arcs. The heat flow in the Grenada basin to the west of the active arc is 0.06 W/m2, a factor of 2 lower than that found in the previous and most recent study. There is no thermal evidence for significant shallow fluid advection at any of these sites. Present‐day volcanism is confined to the region with the highest heat flow.
Solar influence on winter severity in central Europe
Authors: Sirocko Frank , Brunck Heiko , Pfahl Stephan 
Published: July 2012

The last two winters in central Europe were unusually cold in comparison to the years before. Meteorological data, mainly from the last 50 years, and modelling studies have suggested that both solar activity and El Niño strength may influence such central European winter coldness. To investigate the mechanisms behind this in a statistically robust way and to test which of the two factors was more important during the last 230 years back into the Little Ice Age, we use historical reports of freezing of the river Rhine. The historical data show that 10 of the 14 freeze years occurred close to sunspot minima and only one during a year of moderate El Niño. This solar influence is underpinned by corresponding atmospheric circulation anomalies in reanalysis data covering the period 1871 to 2008. Accordingly, weak solar activity is empirically related to extremely cold winter conditions in Europe also on such long time scales. This relationship still holds today, however the average winter temperatures have been rising during the last decades.
Maximum wind speeds and US hurricane losses
Authors: Murnane R. J. , Elsner J. B. 
Published: July 2012

There is academic, commercial, and public interest in estimating loss from hurricanes striking land and understanding how loss might change as a result of future variations in climate. Here we show that the relationship between wind speed and loss is exponential and that loss increases with wind speed at a rate of 5% per m s−1. The relationship is derived using quantile regression and a data set comprising wind speeds of hurricanes hitting the United States and normalized economic losses. We suggest that the “centercepts” for the different quantiles account for exposure‐related factors such as population density, precipitation, and surface roughness, and that once these effects are accounted for, the increase in loss with wind speed is consistent across quantiles. An out‐of‐sample test of this relationship correctly predicts economic losses from Hurricane Irene in 2011. The exponential relationship suggests that increased wind speeds will produce significantly higher losses; however, increases in exposed property and population are expected to be a more important factor for near future losses.
On the sunrise oscillation of the F region in the equatorial ionosphere
Authors: Ambili K. M. , St.‐Maurice J.‐P. , Choudhary R. K. 
Published: July 2012

This paper shows that, contrary to previous explanations, the apparent undulating motion of the equatorial F region peak at sunrise is produced by photochemistry rather than dynamics. Our study is based on an investigation of the behavior of the early morning ionosphere observed by a Digital Ionosonde at Trivandrum, India. The phenomenon is rooted in the production of new plasma at the upper F region altitudes soon after sunrise. As the peak photoproduction rate moves down in altitude and increases in magnitude the newly formed plasma follows a similar trend. Once the density becomes large enough to be detected by an ionosonde, a jump is observed in the F region peak altitude. The jump is followed by a quick downward motion of the increasingly strong F peak. Chemistry causes the downward motion of the F peak to end near 250 km. Electrodynamics is not responsible for the sunrise undulation, but plays an indirect role in the detection of the sunrise effect by simultaneously lowering during the night the peak height and decreasing the density. When detectable, the remnant plasma introduces a lower peak height that facilitates the observation of the initial increase in peak height, while the lower background density allows the relatively small initial density increase from photoionization to be observed.
Comparing the cross polar cap potentials measured by SuperDARN and AMIE during saturation intervals
Authors: Gao Ye 
Published: July 2012

Assimilative Mapping of Ionospheric Electrodynamics (AMIE) and Super Dual Auroral Radar Network (SuperDARN) are two commonly used techniques to measure cross polar cap potential (ΦPC). In this study, I compare ΦPC inferred from AMIE with that inferred from SuperDARN during saturation intervals. Measurements from Defense Meteorological Satellite Program (DMSP) and polar cap (PC) index are also used to help estimate true ΦPC. Seven saturation events in 2000 were selected. For each event, I ran the AMIE software driven by magnetometer data only, by magnetometer data and SuperDARN data, and by SuperDARN data only. Then I compared ΦPC obtained from AMIE with that from SuperDARN. I found that: (1) ΦPC inferred from SuperDARN is significantly lower than that inferred from other techniques including AMIE when ΦPC is large (e.g., greater than 150 kV); (2) ΦPC inferred from AMIE with SuperDARN input is much higher than ΦPC inferred from SuperDARN; (3) ΦPC inferred from AMIE with magnetometer input tends to give the same results as that inferred from AMIE with magnetometer and SuperDARN input; (4) ΦPC inferred from AMIE with magnetometer input is, in general, in agreement with ΦPCinferred from AMIE with SuperDARN input. It is suggested that reason for the low values of SuperDARN‐derived ΦPC during saturation intervals is that the SuperDARN algorithm to compute ΦPC from measurements is not applicable to such intervals.
Energy transport by kinetic‐scale electromagnetic waves in fast plasma sheet flows
Authors: Chaston C. C. , Bonnell J. W. , Clausen L. , Angelopoulos V. 
Published: July 2012

We report observations from the THEMIS spacecraft characterizing the nature and importance of low frequency electromagnetic fluctuations on kinetic scales embedded within fast flows in the Earth's plasma sheet. A consideration of wave property variations with frequency and flow speed suggest that for spacecraft frame frequencies satisfying |vf|/ñi ≤ ùsc ≤ 100|vf|/ñi (or 0.2 ≲ fsc ≲ 20 Hz) these fluctuations can generally be described as kinetic Alfvén waves. Here vf is the flow speed, ñi the ion gyroradius, and ùsc and fsc are the angular and cyclical frequencies respectively in the spacecraft frame. The statistics of energy transport via Poynting flux (S) in these fluctuations and ion energy flux (å) in the flow follow log normal distributions with mean values of 〈S〉 = 101.1 ± 0.7 and 〈ε〉 = 102.4 ± 0.4 mW/m2 respectively where the values are ‘mapped’ to a reference magnetic field at 100 km altitude. Here the indices following ‘ ± ’ correspond to one standard deviation. We find that 〈S/ε〉 = 10−1.3 ± 0.7 or that kinetic Alfvén waves on average transport ∼5% of the total energy transport in the flow but note that the values larger than 25% are within one standard deviation of the mean. Our observations show that these waves are continually radiated outward from the flow toward the auroral oval, low latitude boundary layer or lobes and that over several Earth‐radii the integrated energy loss from the flow channel can be comparable to the total energy content of the flow itself. We find that this plasma sheet energy loss process is particularly effective within |XGSE| ≤ 15 RE.
Evaporative losses from a common reed‐dominated peachleaf willow and cottonwood riparian plant community
Authors: Kabenge Isa , Irmak Suat 
Published: July 2012

Our study is one of the first to integrate and apply within‐canopy radiation physics parameters and scaling‐up leaf‐level stomatal resistace (rL) to canopy resistance (rc) approach to quantify hourly transpiration (TRP) rates of individual riparian plant species—common reed (Phragmites australis), peachleaf willow (Salix amygdaloides), and cottonwood (Populus deltoides)— in a mixed riparian plant community in the Platte River Basin in central Nebraska. Two experimental years (2009 and 2010) were contrasted by warmer air temperature and presence of flood water in 2010. The seasonal average rc values for common reed, peachleaf willow, and cottonwood in 2009 were 76, 70, and 107 s m−1, respectively. The corresponding rc values in the flood year (2010) were 70, 66, and 105 s m−1 for the same species, respectively. In 2009, the seasonal total TRP for common reed, peachleaf willow, and cottonwood were 483, 522, and 431 mm, respectively. Corresponding TRP values in 2010 were greater as 550, 655, and 496 mm, respectively. In 2009, TRP accounted for 64% of ETa during June–September, and the proportion varied between 41% and 69% for most of the season. In 2010, TRP accounted for 61% of ETa during June–September, and the proportion varied between 41% and 65% for most of the season. The average surface evaporation rate of the riparian zone was 0.81 mm d−1 in 2009 and 1.70 mm d−1 in 2010. Seasonal evaporation was 160 mm in 2009 and 312 mm in 2010. The study provides a basis for understanding the dynamics of transpiration for riparian vegetation in response to the environmental conditions and provides valuable water use data for more complete water balance analyses by accounting for the water use of riparian vegetation species.
Training Speech Language Pathologists of Adult Clients on the Implementation of AAC Into Everyday Practice
Authors: Crema Christopher , Moran Nicole 
Published: July 2012

Abstract
As speech-language pathologists enter into the workforce, it is clear that many of them are underprepared in the area of Alternative and Augmentative Communication (AAC). Many times, inexperienced clinicians will not be aware of the resources available to them for further clinical training in AAC. Researchers have investigated and documented how these clinicians prefer to learn about new technology as adults. In this article, we will identify and discuss the need for ongoing clinical training for clinicians with limited experience with AAC specific to the adult population, note ways in which inexperienced clinicians can obtain clinical training, and review literature that examines the various ways adult clinicians learn new and technological information most effectively.