3,542 research outputs found

    Perceptual assimilation, discrimination, and acquisition of non-native and second-language vowels assimilated as uncategorised

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    Non-native and second-language (L2) phones are perceived in terms of their similarities and differences to the listener’s native (L1) phonemes. A non-native phone that is reliably identified as similar to a single L1 phoneme is described as being categorised according to PAM/PAM-L2 (Best, 1995; Best & Tyler, 2007), and such categorised assimilations have been the focus of much of the research on non-native and L2 speech perception. It is also possible that non-native/L2 phones are perceived as being speech-like, but are not identified with any one particular L1 phoneme. In such instances, they are said to be assimilated as uncategorised. This thesis presents experiments designed to address how these uncategorised phones are perceived, discriminated, and acquired by adult L2 learners. The findings have theoretical implications for models of cross-language and L2 speech perception, and contribute to our understanding of the perception and acquisition of uncategorised phones. The first question addressed in this thesis was whether there were any systematic differences in the way in which uncategorised non-native phones are assimilated within the L1 phonological system. In the first experiment, native Egyptian Arabic speakers residing in Egypt perceptually assimilated and rated all of the Australian English vowels in relation to their L1 vowels. Results revealed new assimilation types for uncategorised phones. They may be perceived as being moderately similar to just a single L1 phoneme (focalised), to two or more L1 phonemes (clustered), or unlike any of the L1 phonemes (dispersed). This suggests that not all uncategorised phones are perceived in the same way, but rather, they vary in the extent to which they are perceptually identified with L1 phonemes. The second set of experiments addressed the issue of how well pairs of non-native phones might be discriminated when one or both phones are assimilated as uncategorised (i.e., Uncategorised-Uncategorised and Uncategorised-Categorised assimilations, respectively). Native Australian English speakers discriminated Danish monophthongal and diphthongal vowel contrasts varying in assimilation type, including Uncategorised-Uncategorised and Uncategorised-Categorised. Discrimination accuracy was modulated by the presence of perceived phonological overlap in the categorisations to L1 phonemes, with partially overlapping contrasts discriminated less accurately than non-overlapping contrasts. By considering the different uncategorised assimilations and the presence of perceived phonological overlap to L1 categories, it was possible to fine-tune predictions for Uncategorised- Uncategorised and Uncategorised-Categorised assimilations much better than if overlap were not considered. The final aim of this thesis was to examine the acquisition of uncategorised L2 phones in adults. It was predicted that new category formation would be more likely to occur for uncategorised, than for categorised, L2 phones. Egyptian Arabic speakers acquiring Australian English in an immersion setting were recruited for a 1-year longitudinal study. They were assessed on their perceptual assimilation of the English vowels, and also on their discrimination accuracy of English vowels that formed Uncategorised-Uncategorised and Uncategorised-Categorised assimilations, as it is these assimilations that should be easily acquired according to the PAM (Best, 1995) and SLM (Flege, 1995) theoretical models. The learners were not absolute beginners, but they differed on six factors related to L2 experience (i.e., length of residence, age of foreign language acquisition, age of immersion, proportion of L2 use, L2 vocabulary size, and duration of English as a foreign language training). There was no evidence of new category acquisition, perhaps because they had already reached a plateau in L2 learning at the start of the study, or possibly because a longer period of immersion may be needed to determine whether they show improvements over time. However, by considering variability among individual learners, the six factors were shown to predict discrimination accuracy to a certain extent, predominantly for Uncategorised-Uncategorised and Uncategorised-Categorised assimilations. Overall, the experiments reported in this thesis provided a much-needed systematic and thorough investigation into the perceptual assimilation, discrimination, and acquisition of uncategorised non-native/L2 phones. The experiments demonstrated that uncategorised phones vary in their perceptual assimilation to the L1, and that discrimination accuracy is dependent upon the presence of perceived phonological overlap for contrasts involving uncategorised phones. This has important theoretical implications for both cross-language and L2 speech perception models. A number of interesting questions are also raised for L2 phonological category formation, answers to which have the potential to provide a step forward in our understanding of L2 acquisition

    Cold-water coral reef frameworks, megafaunal communities and evidence for coral carbonate mounds on the Hatton Bank, north east Atlantic

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    Offshore banks and seamounts sustain diverse megafaunal communities, including framework reefs formed by cold-water corals. Few studies have quantified environmental effects on the alpha or beta diversity of these communities. We adopted an interdisciplinary approach that used historical geophysical data to identify topographic highs on Hatton Bank, which were surveyed visually. The resulting photographic data were used to examine relationships between megafaunal communities and macrohabitat, the latter defined into six categories (mud, sand, cobbles, coral rubble, coral framework, rock). The survey stations revealed considerable small-scale variability in macrohabitat from exposed Late Palaeocene lava flows to quiescent muddy habitats and coral-built carbonate mounds. The first reported evidence for coral carbonate mound development in UK waters is presented, which was most pronounced near present-day or former sites of topographic change, suggesting that local current acceleration favoured coral framework growth and mound initiation. Alpha diversity varied significantly across macrohabitats, but not between rock and coral rubble, or between smaller grain sized categories of cobbles, sand and mud. Community composition differed between most macrohabitats, and variation in beta diversity across Hatton Bank was largely explained by fine-scale substratum. Certain megafauna were clearly associated with particular macrohabitats, with stylasterid corals notably associated with cobble and rock habitats and coral habitats characterized by a diverse community of suspension-feeders. The visual surveys also produced novel images of deep-water megafauna including a new photographic record of the gorgonian coral Paragorgia arborea, a species not previously reported from Rockall Plateau. Further interdisciplinary studies are needed to interpret beta diversity across these and other environmental gradients on Hatton Bank. It is clear that efforts are also needed to improve our understanding of the genetic connectivity and biogeography of vulnerable deep-water ecosystems and to develop predictive models of their occurrence that can help inform future conservation measures

    Goodness-of-Fit Tests to study the Gaussianity of the MAXIMA data

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    Goodness-of-Fit tests, including Smooth ones, are introduced and applied to detect non-Gaussianity in Cosmic Microwave Background simulations. We study the power of three different tests: the Shapiro-Francia test (1972), the uncategorised smooth test developed by Rayner and Best(1990) and the Neyman's Smooth Goodness-of-fit test for composite hypotheses (Thomas and Pierce 1979). The Smooth Goodness-of-Fit tests are designed to be sensitive to the presence of ``smooth'' deviations from a given distribution. We study the power of these tests based on the discrimination between Gaussian and non-Gaussian simulations. Non-Gaussian cases are simulated using the Edgeworth expansion and assuming pixel-to-pixel independence. Results show these tests behave similarly and are more powerful than tests directly based on cumulants of order 3, 4, 5 and 6. We have applied these tests to the released MAXIMA data. The applied tests are built to be powerful against detecting deviations from univariate Gaussianity. The Cholesky matrix corresponding to signal (based on an assumed cosmological model) plus noise is used to decorrelate the observations previous to the analysis. Results indicate that the MAXIMA data are compatible with Gaussianity.Comment: MNRAS, in pres

    Cognitive factors in perception and imitation of Thai tones by Mandarin versus Vietnamese speakers

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    The thesis investigates how native language phonological and phonetic factors affect non-native lexical tone perception and imitation, and how cognitive factors, such as memory load and stimulus variability (talker and vowel context variability), bias listeners to a phonological versus phonetic mode of perception/imitation. Two perceptual experiments and one imitation experiment were conducted with Thai tones as the stimuli and with Mandarin and Vietnamese listeners, who had no experience with Thai (i.e., naive listeners/imitators). The results of the perceptual experiments (Chapters 5 and 6) showed phonological effects as reflected in assimilation types (Categorised vs. UnCategorised assimilation) and phonetic effects indicated by percent choice and goodness ratings in tone assimilation, largely in line with predictions based on the Perceptual Assimilation Model (PAM: Best, 1995). In addition, phonological assimilation types and phonological overlap of the contrasts affected their discrimination in line with predictions based on PAM. The thesis research has revealed the influence of cognitive factors on native language influences in perception and imitation of non-native lexical tones, which contribute differently to different tasks. The findings carry implications for current non-native speech perception theories. The fact that non-native tone imitation deviations can be traced back to native phonological and phonetic influences on perception supports and provides new insights about perception-production links in processing non-native tones. The findings uphold the extrapolation of PAM and ASP principles to non-native tone perception and imitation, indicating that both native language phonological and phonetic influences and their modulation by cognitive factors hold implications for non-native speech perception/learning theories, as well as for second language instruction

    Home alone: autonomous extension and correction of spatial representations

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    In this paper we present an account of the problems faced by a mobile robot given an incomplete tour of an unknown environment, and introduce a collection of techniques which can generate successful behaviour even in the presence of such problems. Underlying our approach is the principle that an autonomous system must be motivated to act to gather new knowledge, and to validate and correct existing knowledge. This principle is embodied in Dora, a mobile robot which features the aforementioned techniques: shared representations, non-monotonic reasoning, and goal generation and management. To demonstrate how well this collection of techniques work in real-world situations we present a comprehensive analysis of the Dora system’s performance over multiple tours in an indoor environment. In this analysis Dora successfully completed 18 of 21 attempted runs, with all but 3 of these successes requiring one or more of the integrated techniques to recover from problems

    Breath holds in spontaneous speech

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    This article provides a first quantitative overview of the timing and volumerelated properties of breath holds in spontaneous conversations. Firstly, we investigate breath holds based on their position within the coinciding respiratory interval amplitude. Secondly, we investigate breath holds based on their timing within the respiratory intervals and in relation to communicative activity following breath holds. We hypothesise that breath holds occur in different regions of the lung capacity range and at different times during the respiratory phase, depending on the conversational and physiological activity following breath holds. The results suggest there is not only considerable variation in both the time and lung capacity scales, but detectable differences are also present in breath holding characteristics involving laughter and speech preparation, while breath holds coinciding with swallowing are difficult to separate from the rest of the data based on temporal and volume information alone. Kokkuvõte. Kätlin Aare, Marcin Włodarczak ja Mattias Heldner: Hinge kinni hoidmine spontaanses kõnes. Artikkel kirjeldab hinge kinni hoidmist spontaansetes vestlustes ajaliste ja kopsumahuga seotud omaduste kaudu. Hinge kinni hoidmist analüüsitakse esmalt selle põhjal, kus see käimasoleva hingamisfaasi kopsumahu ulatuse suhtes asub. Teine fookus on ajalisel faktoril: kus hoitakse hinge kinni käimasoleva hingamisfaasi alguse ja lõpu ning vestlustes sisalduva kõne vm suhtes. Hüpoteeside kohaselt peaks hinge kinni hoidmine ajalisel ja kopsumahuga seotud skaalal toimuma erinevas kohas sõltuvalt sellest, milline kontekst hinge kinni hoidmist vestluses ümbritseb. Tulemused näitavad, et kuigi hinge kinni hoidmine esineb suure varieeruvusega mõlemal skaalal, sisaldab andmestik mustreid, mis eristavad kõneplaneerimisega seotud hinge kinni hoidmist teistest alternatiividest. Tulemustest selgub ka, et neelatustega seotud hinge kinni hoidmist on keeruline muudest eristada vaid aja ja kopsumahuga seotud informatsiooni abil. Märksõnad: hinge kinni hoidmine, kõnehingamine, spontaanne kõne, vestlused kolme osalejag

    Comorbidity among patients with colon cancer in New Zealand

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    Effects of smoking and alcohol use on oesophageal cancer amongst Black South Africans in Johannesburg from 1999-2009

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    Background: Oesophageal cancer is the fourth most common cancer in black South African males with an age-standardised incidence rate of 7.31 per 100 000 in 2010, and sixth in black South African females, 3.59 per 100 000. The adoption of lifestyle behaviours such as tobacco and alcohol use was on the rise in that decade, amongst black South Africans living in Johannesburg. Aim: The overall aim was to investigate the association of smoking and alcohol use on oesophageal cancer amongst 18 to 74-year-old black South Africans in Johannesburg from 1999 to 2009. Methods: Secondary analysis were done based on a matched case-control study design. We used the conditional univariate and matched multiple logistic regression for statistical analysis as the main analysis. Gender was ascertained as an effect modifier therefore the analysis were done separately for males and females. Sensitivity analysis of the findings were tested using the unconditional univariate and unmatched multiple logistic regression. Results: Heavy smokers had an increased likelihood of oesophageal cancer as shown in the conditional multivariate logistic regression (AOR = 9.0; 95% CI: 5.2 – 15.5) in males and (AOR = 5.2; 95% CI: 1.3 – 20.1) in females. Alcohol consumption was a much stronger risk factor for oesophageal cancer among female heavy drinkers (AOR = 2.1; 95% CI: 1.5 – 2.9) relative to the light drinkers, controlling for other variables. There was a significant interaction of tobacco use and alcohol drinking as they acted synergistically to increase the likelihood of oesophageal cancer among current heavy smokers and heavy drinkers, (AOR = 15.0; 95% 7.2 – 31.3) in males and (AOR = 2.7; 95% 0.6 – 11.2) in females, compared to non-drinkers. iv Conclusion: We established that over the ten-year study period, smoking and alcohol use were both associated with oesophageal cancer independently and as combined exposures. An increase in sin tax on cigarettes and alcohol as well as increased education on the risk factors associated with the development of oesophageal cancer could be used as interventions to decrease the burden of this disease. Keywords: Smoking, Alcohol, Cancer, South AfricaLG201