11,740 research outputs found

    Ozonation of cooling tower waters

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    Continuous ozone injection into water circulating between a cooling tower and heat exchanger with heavy scale deposits inhibits formation of further deposits, promotes flaking of existing deposits, inhibits chemical corrosion and controls algae and bacteria

    Photoionization models for extreme Lyα\alpha λ\lambda1216 and HeII λ\lambda1640 ratios in quasar halos, and PopIII vs AGN diagnostics

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    We explore mechanisms to produce extremely high Ly-alpha/HeII flux ratios, or to enhance the observed number of Ly-alpha photons per incident ionizing photon, in extended AGN-photoionized nebulae at high-redshift. Using photoionization models, we explore the impact of ionization parameter, gas metallicity, ionizing spectrum, electron energy distribution, and cloud viewing angle on the relative fluxes of Ly-alpha, HeII and other lines, and on the observed number of Ly-alpha photons per incident ionizing photon. We find that low ionization parameter, a relatively soft or filtered ionizing spectrum, low gas metallicity, kappa-distributed electron energies, or reflection of Ly-alpha photons by HI can all result in significantly enhanced Ly-alpha relative to other lines (>10%), with log Ly-alpha/HeII reaching values up to 4.6. In the cases of low gas metallicity, reflection by HI, or a hard or filtered ionizing spectrum, the observed number of Ly-alpha photons per incident ionizing photon is itself significantly enhanced above the nominal Case B value of 0.66 due to collisional excitation, reaching values up to 5.3 in our 'extreme case' model. At low gas metallicity (e.g. 0.1 x Solar), the production of Ly-alpha is predominantly via collisional excitation rather than recombination. In addition, we find that collisional excitation of Ly-alpha becomes more efficient if the ionizing continuum is pre-filtered through an optically thin screen of gas closer to the AGN. We also show that Ly-alpha / HeII ratios of the z~3.5 quasars studied by Borisova et al. (2016) are consistent with AGN-photoionization of gas with moderate to low metallicity and/or low ionization parameter, without requiring exotic ionization/excitation mechanisms such as strong line-transfer effects. We also present UV-optical diagnostic diagrams to distinguish between photoionization by Pop III stars and AGN photoionization.Comment: Accepted for publication in A&A. 14 pages, 9 figures. Abstract slightly shortened to meet arxiv character limi

    Liquid ethylene-propylene copolymers

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    Oligomers are prepared by heating solid ethylene-propylene rubber in container that retains solid and permits liquid product to flow out as it is formed. Molecular weight and viscosity of liquids can be predetermined by process temperature. Copolymers have low viscosity for given molecular weight

    Modulated voltage metastable ionization detector

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    The output current from a metastable ionization detector (MID) is applied to a modulation voltage circuit. An adjustment is made to balance out the background current, and an output current, above background, is applied to an input of a strip chart recorder. For low level concentrations, i.e., low detected output current, the ionization potential will be at a maximum and the metastable ionization detector will operate at its most sensitive level. When the detected current from the metastable ionization detector increases above a predetermined threshold level, a voltage control circuit is activated which turns on a high voltage transistor which acts to reduce the ionization potential. The ionization potential applied to the metastable ionization detector is then varied so as to maintain the detected signal level constant. The variation in ionization potential is now related to the concentration of the constituent and a representative amplitude is applied to another input of said strip chart recorder

    The interstitial cells of the urodele testis

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    Social pedagogy, music making and adopted children

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    Social pedagogy has become a common feature of CPD training for staff working with looked after children and adopted children. Social workers, foster carers and adoptive parents use the characteristic features of social pedagogical practice to develop meaningful relationships with a young person in care. Creative elements such as music have been noted to be useful activities in which both parties (children and support worker) can share a common interest and partake within a joint activity. This article sets out to examine the way in which a community music project working with adopted children and their adoptive parents uses social pedagogy and the impact that this may have on the participants. A case study strategy is used to examine the Loud and Clear adoption family learning project at Sage Gateshead, through which a multi-methodological approach was used, including interviews and participatory action research to gather participants’ and facilitators’ narratives of the impacts the sessions and approaches were having. Furthermore, participatory observations were also undertaken to see at first hand the social pedagogical approaches that the facilitators were using within sessions. Findings from the study indicated that having the opportunity to participate in a joint musical activity was key to helping children and adoptive parents develop their attachments to one another. Similarly, through facilitators providing opportunities for the group to socialise, adoptive parents were able to develop a support network that they felt would have been lacking within their lives. Both of these findings indicate the impact of adopting the common third approach to music making

    The Pitfalls of Constructing Yield Maps

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