1,996 research outputs found

    An integrated model of personal sector expenditure and portfolio decisions

    Get PDF
    In this study a quarterly model of UK Personal Sector portfolio and expenditure decisions over the period 1976 to 1967 is constructed and estimated. This model differs from most other empirical studies of Personal Sector portfolio behaviour in that separabililty of preferences is not assumed and so an integrated framework is adopted for estimation which allows for simultaneous interrelationships between the various decisions

    The JCMT dense gas survey of the Perseus Molecular Cloud

    Full text link
    We present the results of a large-scale survey of the very dense gas in the Perseus molecular cloud using HCO+ and HCN (J = 4 - 3) transitions. We have used this emission to trace the structure and kinematics of gas found in pre- and protostellar cores, as well as in outflows. We compare the HCO+/HCN data, highlighting regions where there is a marked discrepancy in the spectra of the two emission lines. We use the HCO+ to identify positively protostellar outflows and their driving sources, and present a statistical analysis of the outflow properties that we derive from this tracer. We find that the relations we calculate between the HCO+ outflow driving force and the Menv and Lbol of the driving source are comparable to those obtained from similar outflow analyses using 12CO, indicating that the two molecules give reliable estimates of outflow properties. We also compare the HCO+ and the HCN in the outflows, and find that the HCN traces only the most energetic outflows, the majority of which are driven by young Class 0 sources. We analyse the abundances of HCN and HCO+ in the particular case of the IRAS 2A outflows, and find that the HCN is much more enhanced than the HCO+ in the outflow lobes. We suggest that this is indicative of shock-enhancement of HCN along the length of the outflow; this process is not so evident for HCO+, which is largely confined to the outflow base.Comment: 25 pages, 14 figures, 9 table

    Araneae of Alberta and Saskatchewan, Canada

    Get PDF

    Two new species of Sabacon harvestmen, with descriptions of the females of Sabacon astoriensis Shear and Sabacon sheari Cokendolpher, from Western North America. (Arachnida, Opiliones, Sabaconidae)

    Get PDF
    Two new species of Sabaconidae (Ischyropsalidoidea) are described: Sabacon # 1 from central Alberta and British Columbia and Sabacon # 2 from Oregon. Descriptions of the females of Sabacon astoriensis Shear 1975, from Oregon, and Sabacon sheari Cokendolpher 1984, from Oregon and Idaho, are also given

    Versatile liquid helium scintillation counter of large volume design

    Get PDF
    Design and performance of large liquid helium scintillation counter for meson experiment

    Prairie spiders of Alberta and Saskatchewan

    Get PDF
    In the prairie ecozone of Alberta and Saskatchewan, 356 species of spiders in 2 I families have been collected. The 10 families with the most species were Linyphiidae (30%), Gnaphosidae (13%), Salticidae (8%), Theridiidae (8%), Lycosidae (8%), Dictynidae (6%), Thomisidae (6%), Araneidae (5%), Philodromidae (5%) and Clubionidae (3%). These 10 families constituted 91% of the spider biodiversity. In the grassland region ofthe prairie ecozone, there were relatively more species of Gnaphosidae, Lycosidae, Theridiidae, Thomisidae, Dictynidae and Philodomidae and fewer Linyphiidae and Clubionidae than for all provincial ecozones combined. The percentages in the parkland region of the prairie ecozone tended to be intermediate

    On the ubiquity of molecular anions in the dense interstellar medium

    Get PDF
    Results are presented from a survey for molecular anions in seven nearby Galactic star-forming cores and molecular clouds. The hydrocarbon anion C6H- is detected in all seven target sources, including four sources where no anions have been previously detected: L1172, L1389, L1495B and TMC-1C. The C6H-/C6H column density ratio is greater than about 1.0% in every source, with a mean value of 3.0% (and standard deviation 0.92%). Combined with previous detections, our results show that anions are ubiquitous in dense clouds wherever C6H is present. The C6H-/C6H ratio is found to show a positive correlation with molecular hydrogen number density, and with the apparent age of the cloud. We also report the first detection of C4H- in TMC-1 (at 4.8-sigma confidence), and derive an anion-to-neutral ratio C4H-/C4H = (1.2 +- 0.4) x 10^-5 (= 0.0012 +- 0.0004%). Such a low value compared with C6H- highlights the need for a revised radiative electron attachment rate for C4H. Chemical model calculations show that the observed C4H- could be produced as a result of reactions of oxygen atoms with C5H- and C6H-

    Molecular line contamination in the SCUBA-2 450 {\mu}m and 850 {\mu}m continuum data

    Get PDF
    Observations of the dust emission using millimetre/submillimetre bolometer arrays can be contaminated by molecular line flux, such as flux from 12CO. As the brightest molecular line in the submillimetre, it is important to quantify the contribution of CO flux to the dust continuum bands. Conversion factors were used to convert molecular line integrated intensities to flux detected by bolometer arrays in mJy per beam. These factors were calculated for 12CO line integrated intensities to the SCUBA-2 850 {\mu}m and 450 {\mu}m bands. The conversion factors were then applied to HARP 12CO 3-2 maps of NGC 1333 in the Perseus complex and NGC 2071 and NGC 2024 in the Orion B molecular cloud complex to quantify the respective 12CO flux contribution to the 850 {\mu}m dust continuum emission. Sources with high molecular line contamination were analysed in further detail for molecular outflows and heating by nearby stars to determine the cause of the 12CO contribution. The majority of sources had a 12CO 3-2 flux contribution under 20 per cent. However, in regions of molecular outflows, the 12CO can dominate the source dust continuum (up to 79 per cent contamination) with 12CO fluxes reaching \sim 68 mJy per beam.Comment: Accepted 2012 April 19 for publication in MNRAS. 21 pages, 13 figures, 3 table

    Molecular Tracers of Embedded Star Formation in Ophiuchus

    Full text link
    In this paper we analyze nine SCUBA cores in Ophiuchus using the second-lowest rotational transitions of four molecular species (12CO, 13CO, C18O, and C17O) to search for clues to the evolutionary state and star-formation activity within each core. Specifically, we look for evidence of outflows, infall, and CO depletion. The line wings in the CO spectra are used to detect outflows, spectral asymmetries in 13CO are used to determine infall characteristics, and a comparison of the dust emission (from SCUBA observations) and gas emission (from C18O) is used to determine the fractional CO freeze-out. Through comparison with Spitzer observations of protostellar sources in Ophiuchus, we discuss the usefulness of CO and its isotopologues as the sole indicators of the evolutionary state of each core. This study is an important pilot project for the JCMT Legacy Survey of the Gould Belt (GBS) and the Galactic Plane (JPS), which intend to complement the SCUBA-2 dust continuum observations with HARP observations of 12CO, 13CO, C18O, and C17O J = 3 - 2 in order to determine whether or not the cold dust clumps detected by SCUBA-2 are protostellar or starless objects. Our classification of the evolutionary state of the cores (based on molecular line maps and SCUBA observations) is in agreement with the Spitzer designation for six or seven of the nine SCUBA cores. However, several important caveats exist in the interpretation of these results, many of which large mapping surveys like the GBS may be able to overcome to provide a clearer picture of activity in crowded fields.Comment: 43 pages including 19 postscript figures. Accepted for publication in the PAS

    Redescription of the spider Robertus arcticus (Chamberlin & Ivie) (Araneae: Theridiidae), with the first description of the female

    Get PDF
    The original description of Robertus arcticus (Chamberlin and Ivie, 1947) (Araneae: Theridiidae) was based on a single male collected in Alaska, United States of America. The female has remained undescribed, although specimens of both sexes have been collected over the intervening decades. The species occurs in boreal Alaska, and records from Cold Lake, Alberta, Canada and James Bay, Ontario, Canada suggest that it is probably widely distributed in the Canadian boreal. Here we redescribe the male and describe the female for the first time. Most specimens examined in our study were collected from the ground of boreal forest peatlands in northeastern Alberta
    corecore