1,542 research outputs found

    Resolving the Submillimeter Background: the 850-micron Galaxy Counts

    Get PDF
    Recent deep blank field submillimeter surveys have revealed a population of luminous high redshift galaxies that emit most of their energy in the submillimeter. The results suggest that much of the star formation at high redshift may be hidden to optical observations. In this paper we present wide-area 850-micron SCUBA data on the Hawaii Survey Fields SSA13, SSA17, and SSA22. Combining these new data with our previous deep field data, we establish the 850-micron galaxy counts from 2 mJy to 10 mJy with a >3-sigma detection limit. The area coverage is 104 square arcmin to 8 mJy and 7.7 square arcmin to 2.3 mJy. The differential 850-micron counts are well described by the function n(S)=N_0/(a+S^3.2), where S is the flux in mJy, N_0=3.0 x 10^4 per square degree per mJy, and a=0.4-1.0 is chosen to match the 850-micron extragalactic background light. Between 20 to 30 per cent of the 850-micron background resides in sources brighter than 2 mJy. Using an empirical fit to our >2 mJy data constrained by the EBL at lower fluxes, we argue that the bulk of the 850-micron extragalactic background light resides in sources with fluxes near 1 mJy. The submillimeter sources are plausible progenitors of the present-day spheroidal population.Comment: 5 pages, accepted by The Astrophysical Journal Letter

    Reproductive wastage among Merino ewe flocks. 2. Non-clover areas

    Get PDF
    This research sought to define the reasons for low fertility among Merino ewes in Western Australia. This first article looks at wastage in Non-Clover area

    Scintillation and charge extraction from the tracks of energetic electrons in superfluid helium-4

    Full text link
    An energetic electron passing through liquid helium causes ionization along its track. The ionized electrons quickly recombine with the resulting positive ions, which leads to the production of prompt scintillation light. By applying appropriate electric fields, some of the ionized electrons can be separated from their parent ions. The fraction of the ionized electrons extracted in a given applied field depends on the separation distance between the electrons and the ions. We report the determination of the mean electron-ion separation distance for charge pairs produced along the tracks of beta particles in superfluid helium at 1.5 K by studying the quenching of the scintillation light under applied electric fields. Knowledge of this mean separation parameter will aid in the design of particle detectors that use superfluid helium as a target material.Comment: 10 pages, 8 figure

    Open Space – a collaborative process for facilitating Tourism IT partnerships

    Get PDF
    The success of IT projects depends on the success of the partnerships on which they are based. However past research by the author has identified a significant rate of failure in these partnerships, predominantly due to an overly technical mindset, leading to the question: “how do we ensure that, as technological solutions are implemented within tourism, due consideration is given to human-centred issues?” The tourism partnership literature is explored for additional insights revealing that issues connected with power, participation and normative positions play a major role. The method, Open Space, is investigated for its ability to engage stakeholders in free and open debate. This paper reports on a one-day Open Space event sponsored by two major intermediaries in the UK travel industry who wanted to consult their business partners. Both the running of the event and its results reveal how Open Space has the potential to address some of the weaknesses associated with tourism partnerships

    Micromegas operation in high pressure xenon: charge and scintillation readout

    Full text link
    The operational characteristics of a Micromegas operating in pure xenon at the pressure range of 1 to 10 bar are investigated. The maximum charge gain achieved in each pressure is approximately constant, around 4x10^2, for xenon pressures up to 5 bar and decreasing slowly above this pressure down to values somewhat above 10^2 at 10 bar. The MM presents the highest gains for xenon pressures above 4 bar, when compared to other micropattern gaseous multipliers. The lowest energy resolution obtained for X-rays of 22.1 keV exhibits a steady increase with pressure, from 12% at 1bar to about 32% at 10 bar. The effective scintillation yield, defined as the number of photons exiting through the MM mesh holes per primary electron produced in the conversion region was calculated. This yield is about 2x10^2 photons per primary electron at 1 bar, increasing to about 6x10^2 at 5 bar and, then, decreasing again to 2x10^2 at 10 bar. The readout of this scintillation by a suitable photosensor will result in higher gains but with increased statistical fluctuations.Comment: 22 pages, 11 figure

    Reviews

    Get PDF
    The following publications have been reviewed by the mentioned authors;Introducing Craft Design and Technology by A. Breckon and D. Prest, reviewed by Richard KimbellThe Design Process by The Design Council, reviewed by R. MillettDesign Project No. 2 Heavy Plant by John Jeffrey and Nigel Billington, reviewed by R. LightfootThe Eighteenth Century Art, Design and Society, 1689-1789 by Bernard Denvir, reviewed by Marjorie A. CruickshankIndustrial Design Requirements of Industry by C. Hayes and K. Dorsey, reviewed by B. SmithModern Design in Plastics by D. P. Greenwood, reviewed by J. EgglestonWoodturning Projects for Dining by J. A. Sainsbury, reviewed by J. EgglestonWood Turning Music Boxes by J. A. Jacobson, reviewed by J. EgglestonYoung Blood: Britain's Art and Design Schools Today and Tomorrow edited by Kate Baynes, reviewed by A. E. LambethA. Century of Art Education 1882-1982 Hornsey College of Art Centenary Book by Clive Ashwin, reviewed by Oberta de Joi

    Spitzer IRAC Observations of Star Formation in N159 in the LMC

    Full text link
    We present observations of the giant HII region complex N159 in the LMC using IRAC on the {\it Spitzer Space Telescope}. One of the two objects previously identified as protostars in N159 has an SED consistent with classification as a Class I young stellar object (YSO) and the other is probably a Class I YSO as well, making these two stars the youngest stars known outside the Milky Way. We identify two other sources that may also be Class I YSOs. One component, N159AN, is completely hidden at optical wavelengths, but is very prominent in the infrared. The integrated luminosity of the entire complex is L 9×106\approx 9\times10^6L_{\odot}, consistent with the observed radio emission assuming a normal Galactic initial mass function (IMF). There is no evidence for a red supergiant population indicative of an older burst of star formation. The N159 complex is 50 pc in diameter, larger in physical size than typical HII regions in the Milky Way with comparable luminosity. We argue that all of the individual components are related in their star formation history. The morphology of the region is consistent with a wind blown bubble $\approx 1-2Myr-old that has initiated star formation now taking place at the rim. Other than its large physical size, star formation in N159 appears to be indistinguishable from star formation in the Milky Way.Comment: 14 figure

    Coupling to optical phonons in the one-dimensional t-J model: Effects on superconducting fluctuations and phase separation

    Full text link
    The one-dimensional (1D) tt-JJ Holstein model is studied by exact diagonalization of finite rings using a variational approximation for the phonon states. Due to renormalization effects induced by the phonons, for intermediate electron-phonon coupling, the phase separation (PS) boundary, and with it the region of dominating superconducting fluctuations is shifted substantially to smaller values of J/tJ/t as compared to the pure tt-JJ model. Superconducting correlations are weakened through charge density wave interactions mediated by the phonons. Possible consequences for the high TcT_c oxides are discussed.Comment: 4 pages, Latex2

    State-of-the-art in product service-systems

    Get PDF
    A Product Service-System (PSS) is an integrated combination of products and services. This western concept embraces a service-led competitive strategy, environmental sustainability, and the basis to differentiate from competitors who simply offer lower priced products. This paper aims to report the state-of-the-art of PSS research by presenting a clinical review of literature currently available on this topic. The literature is classified and the major outcomes of each study are addressed and analysed. On this basis, this paper defines the PSS concept, reports on its origin and features, gives examples of applications along with potential benefits and barriers to adoption, summarises available tools and methodologies, and identifies future research challenges
    corecore