The achievement of thermally stable second-order nonlinear optical (NLO) coefficients in polymers is an important but elusive goal in obtaining useful materials for commercial devices. In order to demonstrate the effect of photocrosslinkable groups on enhancement of stability of NLO properties, a series of NLO polymers were investigated, which contain side-chain NLO chromophores with a variable number of crosslinkable methacrylate groups attached to the chromophore opposite the main chain attachment point. Following electric field poling, polymers were crosslinked by irradiating polymer samples containing a photoinitiator. Decay of second-order NLO properties was measured by second harmonic generation (SHG), and stability of SHG coefficients was significantly enhanced after photocrosslinking for polymers containing multiple crosslinkable groups on the chromophore. Addition of reactive diluents further enhanced stability. The enhancement of thermal stability demonstrates the efficacy of photocrosslinking and suggests that the stability improvements may carry over to systems with more efficient chromophores and more stable polymer backbones. The addition of photocrosslinkable materials is also exploited in photoresists to mitigate alignment limitations on flexible substrates during photolithographic patterning by enabling imaging of two device layers in a single lithographic exposure. To facilitate the simultaneous patterning of two device layers, a new photoresist system was developed which is able to store and transfer two images concurrently. The dual-tone photoresist system has the ability to store two independent latent images, distinguished by the incident exposure light wavelength, while remaining compatible with reactive ion etch image transfer processes. A modified chemically amplified photoresist for 193 nm lithography containing an added photobase generator (PBG) leads to a dual-threshold behavior of the dissolution vs. dose contrast curve that enables pitch division of patterned images. To improve these resists, a study of resist components’ effects on line edge roughness and pitch division process windows was performed. The kinetics of two-stage PBGs are compared to single-stage PBGs with a view toward achieving higher acid latent image gradients at the line edge. Application of nuclear magnetic resonance spectroscopy to determine the rate constants for resist components in thin films is demonstrated and discussed as a tool for formulating dual-threshold resists. / text

Revised; Originally Published 2002 / 4 pp. / Pine bark beetles in Arizona are generally of the genus Ips or Dendroctonus. Fading foliage in the tree is often the first sign of a beetle attack. Prevention is best practiced since control is not possible once the beetles have successfully colonized the tree. Colonization is dependent upon trees being in a vulnerable condition caused by stress from various agents and site conditions.

This dissertation presents the results of a study conducted on the speech of male and female students training to become Drill Instructors (hereafter DIs) in the United States Marine Corps. Both high amplitude and low pitch are reported to be important characteristics of the DI Command Voice; these characteristics are also strongly associated with masculinity (Hicks 1997). However, previous research argues that female DIs do not view these qualities as the most important characteristics of the Command Voice. They focus instead on being "direct" (Hicks 1997, Hicks Kennard 1999). The question I address is whether or not the Command Voice taught in DI School is used differently by female and male DI students in authoritative speech.The data were recorded at the DI School in Parris Island, South Carolina. Six subjects participated in the study. The two factors considered were sex and speech style, which included: 1) teachback: high-amplitude recitations of training procedures, 2) locker-box discussion: a speech style used in academic settings, 3) interviews, and 4) a reading sample. Both vowel duration and peak pitch measurements were done in each speech style; measurements on larger thirty-second "chunks" of discourse were taken for mean pitch, standard deviation of pitch, range of pitch, and speaking rate for each speaker in each speech style. There was a significant main effect on vowel duration for all subjects except for one male and a significant main effect on peak pitch for all subjects. For discourse measurements of pitch, there was a significant main effect for mean pitch, standard deviation of pitch, and pitch range.Pair-wise comparisons resulted in significant differences in peak pitch for all subjects in all speech styles. Both females and males exhibited the same pattern for both vowel and discourse pitch measurements, from highest to lowest pitch: teachbacks, lockerbox discussion, reading sample, and interview. However, females' vowels were significantly longer in the most authoritative speech style--precisely where males had their shortest vowel duration. This difference suggests that in authoritative speech, females use vowel duration as part of the "directness" in authority, where males do not.

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The main purpose of the present study was to investigate whether a shift from absolute to relative pitch perception occurs during early childhood. Other factors that can influence the development of absolute pitch, such as cognitive abilities and the child's environment were examined. Young children completed (n=88): (1) a variety of pitch tasks (absolute and relative pitch tests) prior to and after two months of focused instruction on absolute and relative pitch, (2) tests of cognitive abilities, and (3) a questionnaire gathering information about family musical environment. / The results indicate that a shift from absolute to relative perception occurs between the ages of 5 and 7. Children younger than six demonstrated limited ability to perform relational tasks such as ordering bells, identifying transposed intervals, and comparing pitches. However, they memorized target pitches better than the older children, matched target tones on the xylophone and sang newly learned songs in their original key more often than did the older children. Older children benefited to a larger extent from the training on relative pitch. Cognitive and spatial abilities were related to absolute pitch development: children who identified pitches better had a more sequential and a less simultaneous way of processing information. Family musical environment seems to have influenced the development of absolute pitch. Implications for the acquisition of absolute pitch are discussed.

This thesis proposes to improve and enrich the expressiveness of English Text-to-Speech (TTS) synthesis by identifying and generating natural patterns of prosodic prominence. In most state-of-the-art TTS systems the prediction from text of prosodic prominence relations between words in an utterance relies on features that very loosely account for the combined effects of syntax, semantics, word informativeness and salience, on prosodic prominence. To improve prosodic prominence prediction we first follow up the classic approach in which prosodic prominence patterns are flattened into binary sequences of pitch accented and pitch unaccented words. We propose and motivate statistic and syntactic dependency based features that are complementary to the most predictive features proposed in previous works on automatic pitch accent prediction and show their utility on both read and spontaneous speech. Different accentuation patterns can be associated to the same sentence. Such variability rises the question on how evaluating pitch accent predictors when more patterns are allowed. We carry out a study on prosodic symbols variability on a speech corpus where different speakers read the same text and propose an information-theoretic definition of optionality of symbolic prosodic events that leads to a novel evaluation metric in which prosodic variability is incorporated as a factor affecting prediction accuracy. We additionally propose a method to take advantage of the optionality of prosodic events in unit-selection speech synthesis. To better account for the tight links between the prosodic prominence of a word and the discourse/sentence context, part of this thesis goes beyond the accent/no-accent dichotomy and is devoted to a novel task, the automatic detection of contrast, where contrast is meant as a (Information Structure’s) relation that ties two words that explicitly contrast with each other. This task is mainly motivated by the fact that contrastive words tend to be prosodically marked with particularly prominent pitch accents. The identification of contrastive word pairs is achieved by combining lexical information, syntactic information (which mainly aims to identify the syntactic parallelism that often activates contrast) and semantic information (mainly drawn from the Word- Net semantic lexicon), within a Support Vector Machines classifier. Once we have identified patterns of prosodic prominence we propose methods to incorporate such information in TTS synthesis and test its impact on synthetic speech naturalness trough some large scale perceptual experiments. The results of these experiments cast some doubts on the utility of a simple accent/no-accent distinction in Hidden Markov Model based speech synthesis while highlight the importance of contrastive accents.

This thesis compares the speech quality of Code Excited Linear Predictor (CELP, Federal Standard 1016) speech coder with a new wavelet method to compress speech. The performances of both are compared by performing subjective listening tests. The test signals used are clean signals (i.e. with no background noise), speech signals with room noise and speech signals with artificial noise added. Results indicate that for clean signals and signals with predominantly voiced components the CELP standard performs better than the wavelet method but for signals with room noise the wavelet method performs much better than the CELP. For signals with artificial noise added, the results are mixed depending on the level of artificial noise added with CELP performing better for low level noise added signals and the wavelet method performing better for higher noise levels.

The aims of this research project were to identify and classify the binder-filler interfaces formed in carbon electrodes and to determine the effects of the interfacial quality on important electrode properties. The effects of raw materials and some fabrication process variables on interfacial characteristics and quality of laboratory produced test electrodes were also studied, and the development of binder-filler interfaces during the carbonisation process followed. Electrode quality was assessed by measurement of density, electrical resistivity and tensile strength. Pore structural data were also obtained by using a computerised image analysis system allied to an optical microscope. Interface quality data were obtained by examining etched surfaces in a scanning electron microscope and classifying the binder-filler interface observed into one of five categories. The category depending on the extent of contact between the binder and filler. Accordingly, test electrodes were produced from combinations of four filler carbons, comprising three grades of calcined petroleum coke and an electro-calcined anthracite, and four coal-tar binder pitches which varied in the type and quantity of insoluble matter content. Examination of these test electrodes showed that the nature of the filler carbon used had a dominant influence on the quality of the interface formed, as assessed by this technique. A combination of one filler carbon and one binder pitch was used to study the effects of some fabrication process variables. These were pitch content and, mixing time and temperature. Of these process variables, pitch content and mixing temperature were found to have the major effects on the binder-filler interface and electrode quality. Investigation of the development of the binder-filler interfaces during the carbonisation process showed three distinct zones of interface development and transformation. These zones were associated with three temperature dependent mechanisms; thermal stress relaxation between 200-350 degrees C, volatile gas evolution from coal-tar pitch decompositionb etween3 50-600 degrees C and stresses induced by thermal contraction of the binder phase between 600-1000 degrees C.

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