Constraining the properties of 1.2-mm dust clumps that contain luminous water masers

We have conducted a sensitive water maser search with the ATCA towards 267 1.2-mm dust clumps presented in the literature. We combine our new observations with previous water maser observations to extend our sample to 294 1.2-mm dust clumps, towards which we detect 165 distinct water maser sites towards 128 1.2-mm dust clumps. Within the fields of our observations, we additionally find four water masers with no apparent associated 1.2-mm dust continuum emission. Our overall detection rate of 44 per cent appears to vary as a function of Galactic longitude. We find that there is an excellent correspondence between the locations of the detected water masers with the peak of the target 1.2-mm dust clump sources. As expected from previous similar studies, the water masers are chiefly detected towards the bigger, brighter and more massive 1.2-mm dust clumps. We find further evidence that the water masers tend to increase in flux density (and therefore luminosity), as well as velocity range, as the sources evolve. We also show that the current sample of water maser sources suffer less from evolutionary biases than previous targeted searches. A higher fraction of dust clump sources in our sample are only associated with water masers (41) than only associated with methanol masers (13). This suggests that water masers can be present at an even earlier evolutionary stage than 6.7-GHz methanol masers. Comparison of the water maser detection rates associated with different combinations of methanol maser and radio continuum, as well as those with neither tracer, shows that the highest detection rate is towards those sources which also exhibit methanol maser emission. We have tested a previously hypothesised model for water maser presence towards 1.2-mm dust clumps. We suggest refinements and future work which will further constrain the nature of the driving sources associated with water masers.Comment: accepted to MNRA

Buffalo Child Care Means Business: Full Study Report

[Excerpt] Buffalo Child Care Means Business presents the economic and business case for making Buffalo\u27s children the focus of economic development. The 2006 survey of 117 businesses located in downtown Buffalo, New York, documents the business sector\u27s present and projected reliance upon high quality child care services as a necessary component to optimum workplace recruitment, productivity and stability. This promising study highlights research specific to the Buffalo region measuring the cost the community bears as a result of low quality child care and early education. It draws upon nationally recognized economic development strategies to offer recommendations for a strategic child care plan integral to the City of Buffalo\u27s overall strategic initiatives to strengthen downtown\u27s attractiveness to successful enterprises. The early development needs of Buffalo\u27s children must be front and center if the potential economic power of broadly successful education is to be realized. With business, government, education and child care leaders at the table, Buffalo\u27s economic renaissance can be built on individual and social foundations that last a lifetime

37 GHz methanol masers : Horsemen of the Apocalypse for the class II methanol maser phase?

We report the results of a search for class II methanol masers at 37.7, 38.3 and 38.5 GHz towards a sample of 70 high-mass star formation regions. We primarily searched towards regions known to show emission either from the 107 GHz class II methanol maser transition, or from the 6.035 GHz excited OH transition. We detected maser emission from 13 sources in the 37.7 GHz transition, eight of these being new detections. We detected maser emission from three sources in the 38 GHz transitions, one of which is a new detection. We find that 37.7 GHz methanol masers are only associated with the most luminous 6.7 and 12.2 GHz methanol maser sources, which in turn are hypothesised to be the oldest class II methanol sources. We suggest that the 37.7 GHz methanol masers are associated with a brief evolutionary phase (of 1000-4000 years) prior to the cessation of class II methanol maser activity in the associated high-mass star formation region.Comment: 14 pages, 4 figures, accepted for publication in Ap

From Forest To Tundra: Historical Biogeography, Floristic Diversity And Nucleotide Variation In Balsam Poplar

Thesis (Ph.D.) University of Alaska Fairbanks, 2010The North America boreal forest extends across more than 10� of latitude from central Labrador to interior Alaska. Periods of major climate fluctuations, including glacial and interglacial cycles, drove major migrations in the Quaternary history of the boreal forest. Beringia, the unglaciated region between the Lena and Mackenzie rivers, is recognized as an important refugium for arctic plants during the last ice age, but its role for boreal trees remains controversial. The paleobotanical record indicates Populus balsamifera (balsam poplar) survived within Beringia during the last glacial. My research employed an interdisciplinary approach, combining techniques in the fields of ecology, evolution and population genetics, to reconstruct the late Quaternary migration history of balsam poplar and to describe and classify balsam poplar plant communities in the Alaskan Arctic. Chapter 1 describes the motivation for the research. Chapter 2 addresses whether a demographically-detectable population of balsam poplar was present within Beringia during the most recent ice age. I found that patterns of variation in chloroplast DNA are most consistent with the presence of a single population of balsam poplar south of the continental ice sheets through the Late Quaternary. Chapter 3 is an analysis of floristic diversity in balsam poplar communities across the Arctic Slope, Interior Alaska and the Yukon Territory and asks whether one balsam poplar-associated plant community spans the arctic and boreal regions, or if these communities differ. I found that arctic communities are dominated by arctic-alpine taxa, whereas boreal communities are dominated by boreal taxa. A strong linkage between climate and the occurrence of balsam poplar also was observed on the Arctic Slope. Chapter 4 is a study of nucleotide diversity in three nuclear loci across the range of balsam poplar. This was the first study to document geographic structure in genetic variation within the species. It also showed that diversity in three North American poplars (P. balsamifera, P. deltoides and P. trichocarpa) was substantially less than that of three Eurasian poplars (P. alba, P. nigra and P. tremula). Chapter 5 summarizes the research and points toward future research directions

The Effect of Moisture on Ply-Bond Strength of Paperboard

This study was carried out to evaluate the effect on the ply-bond strength of the moisture content of the plies of a multi-ply sheet at the time of joining. Two-ply sheets were formed with the plies at various moisture contents at joining. The resulting ply-bonds were evaluated by three methods, viz. Instron peel, Mullen ply-bond, and z-direction tensile. Each method showed the same trend of ply-bond strength dependence on moisture and within the range of experimental error the average values of the three techniques correlated well. This study showed that the moisture content of the plies at joining is extremely critical in the ply-bond strength of paperboard. The practical minimum moisture content at which a ply-bond was possible was 20%. There was a gradual increase of ply-bond strength with increasing moisture content of the plies until a critical moisture range of 85 to 90% was reached. In this narrow range of moisture content the ply-bond strength increased two to fourfold. Once the critical range of moisture content was exceeded, no further increase in ply-bond strength occurred because the failure of the two-ply assembly occurred within one of the plies. This was confirmed by experiments which showed that the single ply (intraply) strength was of the same magnitude as the two-ply bond strength

12.2-GHz methanol maser MMB follow-up catalogue - II. Longitude range 186 to 330 degrees

We present the second portion of a catalogue of 12.2-GHz methanol masers detected towards 6.7-GHz methanol masers observed in the unbiased Methanol Multibeam (MMB) Survey. Using the Parkes radio telescope we have targeted all 207 6.7-GHz methanol masers in the longitude range 186 to 330 degrees for 12.2-GHz counterparts. We report the detection of 83 12.2-GHz methanol masers, and one additional source which we suspect is thermal emission, equating to a detection rate of 40 per cent. Of the 83 maser detections, 39 are reported here for the first time. We discuss source properties, including variability and highlight a number of unusual sources. We present a list of 45 candidates that are likely to harbor methanol masers in the 107.0-GHz transition.Comment: Accepted MNRAS 19 July 201