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1	The perceptibility of duration in the phonetics and phonology of contrastive consonant length Hansen, Benjamin Bozzell 12 July 2012 (has links) This dissertation investigates the hypothesis that the more vowel-like a consonant is, the more difficult it is for listeners to classify it as geminate or singleton. A perceptual account of this observation holds that more vowel-like consonants lack clear markers to signal the beginning and ending of the consonant, so listeners don’t perceive the precise duration and consequently the phonological contrast may be neutralized in some languages. Three experiments were performed to address these questions using data from Persian speakers. In Experiment I, four speakers produced singleton and geminate tokens of the voiced oral consonants [d,z,n,l,j] and the glottals [h] and glottal stop at three speaking rates. It was found that Persian speakers do distinguish geminate durations from singleton durations for all manners even at very fast speaking rates, and vowels preceding geminates are slightly longer than those preceding singletons. Speaking rate had more of an effect on geminates than on singletons for all segments studied: the durations of the geminates decreased more in fast speech than the durations of the singletons did. In Experiment II, listeners heard manipulated continua of consonants ranging from singletons to geminates. Subjects’ identification curves were modeled using the cumulative Gaussian model. The modeled standard deviation was interpreted as the breadth of the perceptual threshold, and a broader threshold understood to indicate a less distinct perceptual boundary between the two categories. Obstruents [d,z] had smaller breadth values than the sonorants [n,l,j], and the glottals had the largest breadth values of all. This indicates that while sonorants were more difficult for listeners to categorize than obstruents, the glottals were the most difficult to categorize of the segments tested. Experiment III tested whether the modification of a specific parameter, the formant transition duration, would affect the perceptibility of the geminate/singleton contrast. A single token containing the glide [j] was manipulated to produce three different continua, each having a distinctly different manipulated transition: short, normal or long. It was found that the longer the transition was, the broader the perceptual threshold, thus making the consonant harder to categorize. / text Geminate Persian Manner Classification Vowellike Rate Perceptual Threshold Glottal Sonorant Formant Transition
2	THE PRODUCTION OF ARABIC GEMINATE STOPS BY ENGLISH LEARNERS OF ARABIC Almutiri, Ahmed Saad 01 May 2015 (has links) This study aims to investigate the developmental ability of beginning and advance L1 English learners of Arabic to pronounce standard Arabic geminate consonants when enrolled in a full time L2 program. The results showed that English learners produced shorter closure duration when pronouncing geminates. In particular, the beginners lengthened singletons more than the advanced learners did, while both groups of learners shortened geminates much more so than native speakers of Arabic. The advanced L1 English learners of Arabic produced longer geminate duration than beginners. The ultimate result was a smaller ratio between singleton and geminate consonants in comparison to native speakers of Arabic. Acquisition Arabic Learners English Closure Duration Consonantal Length Contrasts L1 L2 Ratio Singleton Geminate
3	Condutividade induzida por radiação ionizante no Mylar (PET) e Kapton (polimiidia). / Radiation-induced conductivity in Mylar (PET) and Kapton (polymide) Gregório Filho, Rinaldo 14 August 1986 (has links) Este trabalho apresenta uma extensiva série de resultados experimentais da condutividade induzida por radiação X contínua, durante e após a irradiação, em amostras de PET e Kapton. As medidas foram realizadas variando-se uma série de parâmetros, tais como: o campo elétrico aplicado, a taxa de exposição, a espessura da amostra, o tipo de eletrodo, a energia da radiação e as condições ambientes. Foram feitas ainda medidas da corrente termo-estimulada em amostras irradiadas e não irradiadas, que permitiram verificar a presença de armadilhas nos materiais. Medidas da corrente fotônica com diferentes eletrodos e espessuras das amostras, constataram a influência do eletrodo no valor dessa corrente. Finalmente um modelo teórico foi desenvolvido, baseado na teoria de balanço dos portadores generalizada, com a inclusão do efeito do campo elétrico na taxa de geração de portadores (efeito Onsager). O ajuste teórico-experimental permitiu a determinação numérica dos principais parâmetros de condução, tais como, mobilidade dos portadores, coeficiente de recombinação e densidade de armadilhas, para os dois materiais estudados. / In this work we present extensive results of measurements of the prompt and delayed radiation-induced conductivity of samples of PET and Kapton. Experimental parameters, such as the effective energy of the radiation, the exposure rate, the total dose, the value of the applied electric field, the nature of the electrodes, and the ambienta1 conditions were changed within wide limits. We also report measurement of thermally stimulated currents for non-irradiated and for irradiated samples which allowed us to investigate the trap-structure of the materials. Measurements of photo-Compton currents with different electrode materials and sample thicknesses gave information about the relation between the nature of the electrodes and the amplitudes of the currents. Based on the generalized rate theory of radiation-induced conduction we developed a theoretical model which includes the effect of the applied electric field on the carrier generation yield (geminate recombination, Onsager effect). Comparison of experimental and theoretical curves allowed us to determine the values of the main conduction parameters, such as carrier mobility, recombination coefficient, trap densities, for the materials under investigation. Condutividade induzida por radiação Efeito Onsager Geminate recombination Onsager effect PET PET Poliimida Polymide Radiation-induced conductivity Raios-X Recombinação geminativa
4	Condutividade induzida por radiação ionizante no Mylar (PET) e Kapton (polimiidia). / Radiation-induced conductivity in Mylar (PET) and Kapton (polymide) Rinaldo Gregório Filho 14 August 1986 (has links) Este trabalho apresenta uma extensiva série de resultados experimentais da condutividade induzida por radiação X contínua, durante e após a irradiação, em amostras de PET e Kapton. As medidas foram realizadas variando-se uma série de parâmetros, tais como: o campo elétrico aplicado, a taxa de exposição, a espessura da amostra, o tipo de eletrodo, a energia da radiação e as condições ambientes. Foram feitas ainda medidas da corrente termo-estimulada em amostras irradiadas e não irradiadas, que permitiram verificar a presença de armadilhas nos materiais. Medidas da corrente fotônica com diferentes eletrodos e espessuras das amostras, constataram a influência do eletrodo no valor dessa corrente. Finalmente um modelo teórico foi desenvolvido, baseado na teoria de balanço dos portadores generalizada, com a inclusão do efeito do campo elétrico na taxa de geração de portadores (efeito Onsager). O ajuste teórico-experimental permitiu a determinação numérica dos principais parâmetros de condução, tais como, mobilidade dos portadores, coeficiente de recombinação e densidade de armadilhas, para os dois materiais estudados. / In this work we present extensive results of measurements of the prompt and delayed radiation-induced conductivity of samples of PET and Kapton. Experimental parameters, such as the effective energy of the radiation, the exposure rate, the total dose, the value of the applied electric field, the nature of the electrodes, and the ambienta1 conditions were changed within wide limits. We also report measurement of thermally stimulated currents for non-irradiated and for irradiated samples which allowed us to investigate the trap-structure of the materials. Measurements of photo-Compton currents with different electrode materials and sample thicknesses gave information about the relation between the nature of the electrodes and the amplitudes of the currents. Based on the generalized rate theory of radiation-induced conduction we developed a theoretical model which includes the effect of the applied electric field on the carrier generation yield (geminate recombination, Onsager effect). Comparison of experimental and theoretical curves allowed us to determine the values of the main conduction parameters, such as carrier mobility, recombination coefficient, trap densities, for the materials under investigation. Condutividade induzida por radiação Efeito Onsager PET Poliimida Raios-X Recombinação geminativa Geminate recombination Onsager effect PET Polymide Radiation-induced conductivity
5	Photodissoziation von Polyhalogenmethanen in Fluiden: Kurzzeitdynamik und Mechanismen / Photodissociation of polyhalomethanes in fluids: Ultrafast dynamics and mechanisms Wagener, Philipp 29 April 2008 (has links) No description available. 540 Chemie Mathematics and Computer Science photolytischer Käfigeffekt Polyhalogenmethane Ultrakurzzeitdynamik Photodissoziation Photoisomerisierung Pump Probe Spektroskopie überkritische Fluide Schwingungsenergierelaxation charge-transfer-Komplex lokale Dichtevergrößerung Photoionisation Solvatation freies Elektron Diffusion geminale Rekombination CTTS-Komplex photolytic cage effect polyhalomethanes ultrafast dynamics photodissociation photoisomerization pump probe spectroscopy supercritical fluids vibrational energy transfer charge-transfer complex local density enhancement photoionisation solvationdynamics of free electron diffusion geminate recombination CTTS-complex 35.13 35.16 35.22 SD 000: Physikalische Chemie SBC 000: Chemie bei hohen Drucken SIL 000: Laser-Chemie {Strahlungschemie}

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