Lexical Effects in Perception of Tamil Geminates

Lexical status effects are a phenomenon in which listeners use their prior lexical knowledge of a language to identify ambiguous speech sounds in a word based on its word or nonword status. This phenomenon has been demonstrated for ambiguous initial English consonants (one example being the Ganong Effect, a phenomenon in which listeners perceive an ambiguous speech sound as a phoneme that would complete a real word rather than a nonsense word) as a supporting factor for top-down lexical processing affecting listeners' subsequent acoustic judgement, but not for ambiguous mid-word consonants in non-English languages. In this experiment, we attempt to look at ambiguous mid-word consonants with Tamil, a South Asian language in order to see if the same top-down lexical effect was applicable outside of English. These Tamil consonants can present as either singletons (single speech sounds) or geminates (doubled speech sounds).We hypothesized that by creating ambiguous stimuli between a geminate word kuppam and a singleton non-word like kubam, participants would be more likely to perceive the ambiguous sound as a phoneme that completes the real word rather than the nonword (in this case, perceiving the ambiguous sound as a /p/ for kuppam instead of kubam). Participants listened to the ambiguous stimuli in two separate sets of continua (kuppam/suppam and nakkam/pakkam) and then indicated which word they heard in a four-alternative forced choice word identification task. Results showed that participants identified the ambiguous sounds as the sound that completed the actual word, but only for one set of continua (kuppam/suppam). These data suggest that there may be strong top-down lexical effects for ambiguous sounds in certain stimuli in Tamil, but not others.No embargoAcademic Major: LinguisticsAcademic Major: Psycholog

Deeply inelastic scattering off nuclei at RHIC

We discuss the physics case for an electron--nucleus collider at RHIC.Comment: 36 pages LaTex, 10 figures, Plenary talk at EPIC meeting, MIT, September 14th-16th, 200

Classical methods in DIS and nuclear scattering at small x

In hadrons and nuclei at very small x, parton distributions saturate at a scale Q_s(x). Since the occupation number is large, and $Q_s(x)>>\Lambda_{QCD}$, classical weak coupling methods may be used to study this novel regime of non-linear classical fields in QCD. In these lectures, we apply these methods to compute structure functions in deeply inelastic scattering (DIS) and the energy density of gluons produced in high energy nuclear collisions.Comment: Latex, 41 pgs. Lectures at the XXXIX Cracow School of Theoretical Physics, Zakopane, Poland, May29th-June8th, 199

Homoacetogenesis as an alternative hydrogen sink in the rumen : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Microbiology and Genetics at Massey University, Palmerston North, New Zealand.

Ruminant livestock contribute significantly to global greenhouse gas emissions. This is due to microorganisms, known as methanogens that generate methane from hydrogen and carbon dioxide during feed fermentation in the rumen. Mitigation strategies are being developed to reduce methane emissions from ruminants. However, inhibiting methane production may cause accumulation of unused hydrogen in the rumen, which may slow down rumen fermentation and affect animal productivity. Homoacetogens, microbes known to reside in the rumen, can use hydrogen and carbon dioxide to form acetate. Homoacetogens could take over the role of ruminal hydrogen disposal following inhibition of methanogens. The aims of this study were to quantify the involvement of alternative hydrogen utilisers, such as homoacetogens, in hydrogen or electron utilisation. Chemical compounds were screened to identify specific inhibitors of methanogens (BES, acetylene), and both methanogens and homoacetogens (chloroform). Homoacetogenesis was measured via incorporation of 13CO2 into 13C-acetate using a short-term in vitro assay. This short-term in vitro assay measured and confirmed the occurrence of homoacetogenesis in sheep rumen fluid, and it accounted for 1.67% of electron utilisation in fresh rumen fluid. Homoacetogenesis increased in the assay when BES was added, suggesting homoacetogens could increase their activity in the absence of methanogens. Homoacetogenesis decreased with the addition of chloroform, which is known to partially inhibit homoacetogens. Methane formation was inhibited by acetylene in an in vitro serial batch fermentation inoculated with sheep rumen fluid. Homoacetogenesis did not increase, but the homoacetogens were able to grow and maintain themselves as the rumen material was repeatedly diluted and supplemented with fresh feed. Their activity accounted for 2.32% of electron utilisation. To study their significance in the rumen, methane formation was inhibited in sheep using acetylene. Homoacetogenesis increased and accounted for 6.53% of electron utilisation. However, propionate appeared to be the major electron sink (58-88%) in the absence of methanogenesis both in vitro and in vivo. In the future, knowledge of these hydrogen-utilising microorganisms could be used to divert hydrogen or electrons into more beneficial end-products, leading to the transition from a normal methane-producing rumen to an equally or even more productive low methane one