The clever designs of natural transducers are a great source of inspiration for man-made systems. At small length scales, there are many transducers in nature that we are now beginning to understand and learn from. Here, we present an example of such a transducer that is used by field crickets to produce their characteristic song. This transducer uses two distinct components—a file of discrete teeth and a plectrum that engages intermittently to produce a series of impulses forming the loading, and an approximately triangular membrane, called the harp, that acts as a resonator and vibrates in response to the impulse-train loading. The file-and-plectrum act as a frequency multiplier taking the low wing beat frequency as the input and converting it into an impulse-train of sufficiently high frequency close to the resonant frequency of the harp. The forced vibration response results in beats producing the characteristic sound of the cricket song. Based on various experimental observations reported in the literature, we model the sound production mechanism as consisting of three stages—actuator, frequency multiplier, and amplifier. We then examine how different features of the forewing govern the sound production. With careful experiments on the harp, we estimate the actual modulus of the harp cuticle and also measure the morphological features of the forewings of different field cricket species. Using this data, we construct a finite element model of the harp and carry out modal analysis to determine its natural frequency. We fine tune the model with appropriate elastic boundary conditions to match the natural frequency of the harp of a particular species—Gryllus bimaculatus. We model impulsive loading based on a loading scheme reported in the literature and predict the transient response of the harp. We show that the harp indeed produces beats and its frequency content matches closely that of the recorded song. Subsequently, we use our FEM model to show that the natural design is quite robust to structural perturbations in the file. The characteristic song frequency produced is unaffected by small variations in the spacing of file-teeth and even by larger gaps. We then attempt to predict a scaling law that crickets must use for spectrum allocation. We use our FEM model, with measurements and computations, to arrive at a predictive model that relates call frequencies of field crickets to the harp dimensions. We verify the validity of this model by using the measured dimensions of harps of nine field cricket species. We then use our model to provide possible explanations as to why the song frequency of various field crickets in our study is bounded between 3.1 kHz and 6.8 kHz. We also show that we are faced with similar challenges as crickets when designing miniature MEMS (Micro-Electro-Mechanical Systems) speakers. We present a design of MEMS speakers that is inspired by how the crickets actuate. We have been able to realize our first prototypes using simple fabrication processes. By electrostatically actuating the MEMS devices, we obtain a sound pressure of 70 dB SPL at a distance of 10 cm. We believe that with a few design and fabrication iterations, we will be able to achieve a much higher sound pressure output from the MEMS speakers.

Current ESL instructors and theorists agree that university students of ESL have a need for a large passive vocabulary. This research was undertaken to determine the effectiveness of a semantic field approach to passive vocabulary acquisition in comparison to a traditional approach. A quantitative analysis of the short-term and long-range results of each approach is presented. Future research and teaching implications are discussed. The outcome of the experimentation lends tentative support to a semantic field approach.

D. Litt. et Phil. / Evidence from several sociolinguistic studies suggests that second language speakers' pronunciation of their target language embodies several varieties of the target language pronunciation. These varieties have developed as a result of the particular social contexts of their language learning and language use. An acquaintance with the Tsongas who speak Afrikaans as a second language will confirm this suggestion- yet no in-depth study of any repute has been done among the Tsongas in this area. The only related study in this field was carried out by Nkatini (1978)...

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This dissertation presents a study of African American and Hispanic speakers in East Austin, Texas, an area that has been historically segregated and is now experiencing rapid gentrification. The current literature is lacking research on minority participation in sound change. This dissertation contributes to redressing the deficit in this area by describing data from sociolinguistic interviews with African American and Hispanic speakers; the following questions are considered: How do social variables influence a linguistic system? How do the social pressures of gentrification influence linguistic variables? To what extent do minority speakers participate in sound changes present in the majority group's variety of English? Specifically, it considers GOOSE and GOAT fronting and the relative positions of LOT and THOUGHT. It has previously been suggested that only Anglo speakers participate in changes affecting these vowels. With regard to GOOSE and GOAT, in many varieties of Southern English, the back vowels become fronted in Anglo speech while they remain backed in African American and Hispanic speech (e.g., Thomas, 2001a). However, the findings discussed here show that African American and Hispanic speakers may front these vowels to achieve particular stylistic purposes. With regard to LOT and THOUGHT, these vowel classes have merged, or are undergoing merger, in many regions of the United States (Labov, Ash, & Boberg, 2006). In Texas, Anglo and Hispanic speakers exhibit the LOT~THOUGHT merger while African American speakers reportedly do not and in general resist the merger (Bailey, Wikle, & Sand, 1991; Bernstein, 1993; Labov et al., 2006; Thomas, 2001a). The findings presented here suggest a trend for LOT~THOUGHT moving towards merger among African American speakers in Central Texas. This is unexpected among African American speakers in Texas and in the U.S. at large. The findings presented illustrate the importance of ethnically diverse samples in describing speech. In Texas where there is a large population of Hispanic residents, we cannot claim to have a thorough knowledge of the regional variety of English without investigating minority speakers. The analysis presented here is a step towards describing a more diverse data set of regional American English. / text

published_or_final_version / Linguistics / Master / Master of Arts

This thesis reports a cross-cultural study that investigated the ways Chinese and Swedish college students do gender in their experiences of reading English as a second language. The concept “doing gender in reading” in this study derives from the view of reading as a social practice that leads to gendered identities construction. Previous studies, which mostly found that girls outperformed boys in reading achievement, created a linear relationship between gender and achievement. This study, informed by social theories of literacy (Gee, 2008; Street, 1984; Kress, 2010) and poststructuralist theories of gender (Weedon, 1997; Butler, 1990), explored how socially-constituted gendered ideologies might be instantiated and negotiated in college students’ experiences of reading English as a second language. It gave particular attention to diversity within and between genders and to the dynamics of students’ socio-culturally mediated reading practices. The study was guided by the following sub-questions: (a) What gender-specific ideologies can be identified in Chinese and Swedish college students’ narratives of reading English as a second language? (b) How do Chinese and Swedish college students act in relation to gender-specific ideologies in their everyday English reading practices? The study was conducted with a qualitative approach of narrative inquiry. Focal informants were four Chinese students and four Swedish students enrolled in English teacher education programs in their home countries. Data were collected over a sixmonth period with techniques of student journal writing, interviews, focus groups, and ethnographic observations. Baxter’s (2003) feminist poststructuralist discourse analysis framed and guided data analysis. The study found three recurrent English reading practices across cases that led to gendered identities construction. These were: making investment in English reading; adopting the strategy of reading English alone; and choosing English reading materials in relation to teachers. Overarching ideologies that shaped these practices included perceptions of reading as a more female-appropriate activity, male readers as independent readers who could solve problems on their own, and female readers as emotional readers who are sensitive to their relation with others. Informants’ actions in relation to these gender-specific ideologies fell into two major categories: conformance and resistance. Findings suggested that female informants seemed to be more ready to resist these ideologies whereas males tended to comply. Swedish informants seemed to demonstrate more awareness of and readiness to resist gendered ideologies compared to Chinese informants. The findings from this study imply that gendered ideologies can have both facilitating and debilitating effects on students’ reading experiences. Therefore, language teachers should develop a critical consciousness of gendered ideologies and how they relate to their students in specific contexts. In response to prevailing socioculturally constituted and power-laden ideologies, the study proposes a new perspective from which to interpret gender and reading English as a second language across cultures. Such a contribution adds momentum to the paradigm shift from essentialism to poststructuralism in second language acquisition that purports that gender is more than an identity label. / published_or_final_version / Education / Doctoral / Doctor of Philosophy

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