305 research outputs found

    The Effects of Small Molecules on the Thermal Degradations of Some Vinyl Polymers

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    In the introductory chapter, the development of research into thermal degradation is traced from study of homopolymers, through copolymers and binary polymer blends, to the present study of polymer/small molecule blends. Following a chapter describing the experimental techniques employed, Chapter Three consists of results, abstracted into tabular form, of a survey of the effects of various small molecules on the thermal degradation of a range of polymers. On the basis of this survey, three blends were chosen, for reasons given in Chapters Four, Five, and Six, to be studied in detail. Zinc bromide was found to exert a massive effect on the thermal degradation of poly(methyl methacrylate) by combining with pendant ester groups to form a co-ordination complex, which subsequently allows cyclisation reactions at low temperature, with liberation of methyl bromide. A complete reaction mechanism for blend degradation is proposed. The effect of zinc bromide on poly(vinyl acetate) degradation, again thought to proceed through complex formation, is of a catalytic nature, resulting in liberation, of acetic acid at temperatures much lower than those required for release of acetic acid from poly(vinyl acetate) alone. Chapter Six deals with the effect, on poly(methyl methacrylate) degradation, of zinc oxide, a widely used commercial additive. In this case, the effect is less marked, with zinc oxide promoting some decomposition of methyl methacrylate units at high temperature, accompanied by some reduction to zinc in the process. In overall conclusion, it can be seen that, whereas some small molecules do not affect polymer degradation, a large number exert a significant influence. The type of effect depends on particular polymer/additive selection, but on the basis of Chapters Four and Five, one possible generalisation is that the likelihood of low temperature degradation is increased if polymer-additive complex formation is possible

    Investigation of techniques for automatic polyphonic music transcription using wavelets.

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    Thesis (M.Sc) - University of KwaZulu-Natal, Pietermaritzburg, 2009.It has been said (although sadly I have no source) that music is one of the most useful yet useless phenomena known to mankind. Useless in that it has, apparently, no tangible or immediately practical function in our lives, but extremely useful in that it is a truly universal language between human beings, which transcends boundaries and allows us to express ourselves and experience emotions in rather profound ways. For the majority of us, music exists to be listened to, appreciated, admired (sometimes reviled) but generally as some sort of stimulus for our auditory senses. Some of us feel the need to produce music, perhaps simply for our own creative enjoyment, or maybe because we crave the power it lends us to be able to inspire feelings in others. For those of us who love to know “the reason why” or “how things work” and wish to discover the secrets of music, arguably the greatest of all the arts, there can surely be no doubt that a fascinating world of mathematics, harmony and beauty awaits us. Perhaps the reason why music is able to convey such strong emotions in us is because we are (for whatever strange evolutionary reason or purpose) designed to be innately pattern pursuing, sequence searching and harmony hungry creatures. Music, as we shall discover in this research, is chock-a-block full of the most incredible patterns, which are just waiting to be deciphered

    Modelling health behaviour: the contribution of health thinking style

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    PosterClare E. McGuiness, Ian Zajac, Deborah Turnbull, Carlene Wilso

    The experience of being a guide dog puppy raiser volunteer: a longitudinal qualitative collective case study

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    There are no published studies that consider the experiences of guide dog puppy raisers. As these people are volunteers, their continued willingness to participate in the training of dogs for assisting the vision impaired and blind is essential for the viability of guide dog schools around the world. Using a qualitative, longitudinal methodology, data were collected from nine guide dog puppy raisers at four time points: before receiving the puppy, one week, then three months after the puppy arrived, and 13 months after the puppy arrived (at which time all puppies had left the raisers). Participants reported more challenges than benefits in raising the puppies. Volunteering to be a guide dog puppy raiser may not be the pleasant experience that is anticipated when community members first offer their services. Understanding what it is like to be a puppy raiser and working towards ways in which to address problems is essential, given that, without volunteers to train and care for puppies, vision impaired and blind people would not have access to guide dogs.Anna Chur-Hansen, Lucy-Kate Werner, Clare E. McGuiness, and Susan Haze

    Thinking style as a predictor of men's participation in cancer screening

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    Men's participation in cancer screening may be influenced by their thinking style. Men's need for cognition (NFC) and faith in intuition were measured to explore whether they varied by demographic variables or predicted screening behavior. Australian males (n = 585, aged 50-74 years) completed surveys about past screening and were subsequently offered mailed fecal occult blood tests (FOBTs). Demographic predictors included age, socioeconomic status, educational attainment, and language spoken at home. The screening behaviors were self-reported prostate cancer screening (prostate-specific antigen testing and digital rectal examinations [DREs]), and colorectal cancer screening (self-reported FOBT participation and recorded uptake of the FOBT offer). Analysis comprised principal component analysis and structural equation modelling. NFC was positively related to demographic variables education, socioeconomic status, and speaking English at home. Faith in intuition was negatively related to educational attainment. NFC predicted variance in self-reported DRE participation (r = .11, p = .016). No other relationships with thinking style were statistically significant. The relationship of NFC to DRE participation may reflect the way certain attributes of this screening method are processed, or alternatively, it may reflect willingness to report participation. The relationship of thinking style to a range of healthy behaviors should be further explored.Clare E. McGuiness, Deborah Turnbull, Carlene Wilson, Amy Duncan, Ingrid H. Flight, and Ian Zaja

    Synchronous oceanic spreading and continental rifting in West Antarctica

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    Magnetic anomalies associated with new ocean crust formation in the Adare Basin off north-western Ross Sea (43 – 26 Ma) can be traced directly into the Northern Basin that underlies the adjacent morphological continental shelf, implying a continuity in the emplacement of oceanic crust. Steep gravity gradients along the margins of the Northern Basin, particularly in the east, suggest that little extension and thinning of continental crust occurred before it ruptured and the new oceanic crust formed, unlike most other continental rifts and the Victoria Land Basin further south. A pre-existing weak crust and localisation of strain by strike slip faulting are proposed as the factors allowing the rapid rupture of continental crust

    To DRE or not to DRE?

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    PosterMcguiness, C.E.,Turnbull, D., Wilson, C., Duncan, A., Flight, I.H.

    K-shell photoionization of ground-state Li-like carbon ions [C3+^{3+}]: experiment, theory and comparison with time-reversed photorecombination

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    Absolute cross sections for the K-shell photoionization of ground-state Li-like carbon [C3+^{3+}(1s2^22s 2^2S)] ions were measured by employing the ion-photon merged-beams technique at the Advanced Light Source. The energy ranges 299.8--300.15 eV, 303.29--303.58 eV and 335.61--337.57 eV of the [1s(2s2p)3^3P]2^2P, [1s(2s2p)1^1P]2^2P and [(1s2s)3^3S 3p]2^2P resonances, respectively, were investigated using resolving powers of up to 6000. The autoionization linewidth of the [1s(2s2p)1^1P]2^2P resonance was measured to be 27±527 \pm 5 meV and compares favourably with a theoretical result of 26 meV obtained from the intermediate coupling R-Matrix method. The present photoionization cross section results are compared with the outcome from photorecombination measurements by employing the principle of detailed balance.Comment: 3 figures and 2 table