As optical designs become more sophisticated and incorporate aspheric and free form surfaces, the need to specify limits on mid-spatial frequency manufacturing errors becomes more critical, particularly as we better understand the effects of these errors on image quality. While there already exist methods based on Fourier analysis to specify these errors in most commercial interferometry software, the method of calculation and the power spectral density (PSD) results remain obscure to many in the optical design and manufacturing field. We suggest that the structure functions (SF) contains the same information as in the Fourier based PSD but in a way that is much more transparent to analysis, interpretation and application as a specification. The units of measure are more familiar and the concept behind the analysis is simpler to understand. Further, the information contained in the structure function (or PSD) allows a complete specification of an optical surface from the finest measurable detail of roughness to the overall figure. We discuss the origin of the structure function in the field of astronomy to describe the effects of air turbulence on image quality, the simple mathematical definition of the structure function and its easy means of calculation and how its results should be scaled depending on the location of the optical surface in a system from pupil to image plane. Finally, we give an example of how to write a specification of an optical surface using the structure function.

The purpose of this study is to examine the position of twentieth century American poetry at the mid-point of the century to ascertain whether contemporary poetry--poetry written in the fifties and sixties--has been justly relegated to the obscure position which it now occupies.

Doctor of Philosophy / Department of Physics / Kristan L. Corwin / This research has focused on the development, demonstration, and characterization of a new type of laser based on optically-pumped gases contained within hollow optical fibers. These novel lasers are appealing for a variety of applications including frequency metrology in the mid-infrared, free-space communications and imaging, and defense applications. Furthermore, because of the hollow core fibers used, this technology may provide the means to surpass the theoretical limits of output power available from high power solid-core fiber laser systems. Gas-filled hollow-core fiber lasers based on population inversion from acetylene ([superscript]12C[subscript]2H[subscript]2) and hydrogen cyanide (HCN) gas contained within the core of a kagome-structured hollow-core photonic crystal fiber have now been demonstrated. The gases are optically pumped via first order rotational-vibrational overtones near 1.5 μm using 1-ns duration pulses from a home-built optical parametric amplifier. Narrow-band laser emission peaks in the 3-μm region corresponding to the ΔJ = ±1 dipole allowed rotational transitions between the pumped vibrational overtone modes and the fundamental C-H stretching modes have been observed in both molecules. High gain resulting from tight confinement of the pump and laser light together with the active gas permits these lasers to operate in a single pass configuration, without the use of any external resonator structure. Studies of the generated mid-infrared pulse energy, threshold energy, and slope efficiency as functions of the launched pump pulse energy and gas pressure have been performed and show an optimum condition where the maximum laser pulse energy is achieved for a given fiber length. The laser pulse shape and the laser-to-pump pulse delay have been observed to change with varying pump pulse energy and gas pressure, resulting from the necessary population inversion being created in the gases at a specific fiber length dependent on the launched pulse energy. Work is on going to demonstrate the first continuous wave version of the laser which may be used to produce a single coherent output from many mutually incoherent pump sources.

This thesis, which supports an exhibition of visual art, develops from Jean Baudrillard's philosophy of seduction. I have focused on the representation of the bachelor and his pad in American men's magazines from the mid-twentieth century. During this period, magazines such as Playboy, Escapade and Rogue created features on modern living to reassure an independent and affluent man that a dwelling with style and taste would ensure a happy bachelor life and facilitate intimacy. My photographs and collages add complexity to this portrait by framing this unique space as a stage where an unmarried man encircled by his lusty decor acted to entrance a woman.

Thesis advisor: Andy Hargreaves / Interest in educational change has continued to grow over the past three decades (Fullan, 1982; Tyack & Cuban, 1995). One focus has been the challenge of implementing sustainable reforms, particularly in secondary schools, which have traditionally been resistant to change (Goodson, 1983; Hargreaves, 2003; Louis & Miles, 1990; McLaughlin & Talbert, 2001). Another has been the role of teachers in implementing, sustaining and also resisting change (Fullan, 1993; Hargreaves, 1994; Kennedy, 2005; Little, 1996). In spite of challenges--and arguably lack of success--wave after wave of reform has attempted to introduce lasting change in schools (Sarason, 1990). No Child Left Behind (NCLB) (U.S. Department of Education, 2002) represents the latest wave of reform. This wave requires a relentless focus on achievement and improvement. The impact of NCLB is felt at the state level, where high-stakes, standardized tests are given annually as a means to measure progress (U.S. Department of Education, 2002). In Massachusetts, the test is the Massachusetts Comprehensive Assessment System (MCAS). While the effects of mandated change are undoubtedly felt at all levels, it is teachers in mid-career for whom the stakes might be highest. Will reform work successfully stimulate and support them, or will it feel like an additional and unwanted burden on the their already full schedules? My dissertation thus explores the following question: * What are the effects of contemporary high-stakes mandated reform on the change commitments and capacities of middle career teachers? Related to this broad question, I explore the in-school conditions and generational factors that influence these change commitments and capacities. The surprising findings revealed that most teachers, representing both high and low performing schools in urban and suburban districts, felt that the MCAS in particular and the standards movement in general offer a neutral to positive opportunity for teachers to assess their students and to hone their curricular and teaching strategies. This statement holds true for the quantitative data as well; teachers generally appear to feel more control and influence over their work than in the recent past. / Thesis (PhD) — Boston College, 2009. / Submitted to: Boston College. Lynch School of Education. / Discipline: Teacher Education, Special Education, Curriculum and Instruction.

Esta dissertação tem como objeto as vogais médias postônicas não-­finais do Português Brasileiro, especificamente a emergência das formas altas [] e [] e das médias-­baixas [] e [], estas últimas especificamente em dialetos do nordeste. Por meio do arcabouço teórico da Geometria de Traços, buscou-­se analisar os motivadores fonológicos que estão correlacionados à emergência de cada uma das formas das vogais. A principal hipótese que se buscou verificar foi se a emergência das vogais [] e [] na posição postônica não-­final, classificadas na literatura como resultantes de alçamento vocálico, está condicionada a correlatos fonológicos, tendo em vista que até então não se conseguiu encontrar um padrão que pudesse formalizar uma regra. Além disso, buscou-­se investigar se a emergência das formas médias-­baixas [, ] na postônica não-­final poderia ser formalizada por regra. Para tanto, realizou-­se um experimento de leitura de palavras em duas localidades, São Paulo e São Luís. A amostra foi constituída por 40 informantes com idades entre 20 e 30 anos, 20 de cada localidade. Os dados foram transcritos após uma verificação acústica de medição de formantes e posteriormente codificados para que testes estatísticos fossem aplicados. Com base nos resultados obtidos, observou-­se que (i) a emergência das formas altas se correlacionou à presença de uma vogal alta na átona final que compartilhasse o mesmo ponto de articulação que o da postônica não-­final, isto é, coronal para [] e labial para []; e que (ii) a emergência das médias-­baixas se correlacionou à presença da vogal dorsal, ou seja, da vogal baixa na átona final. Para a formalização de ambas as regras, faz-­se necessário assumir a proposta de Wetzels (2011) a respeito da neutralização como um mecanismo de mudança do valor do traço que garante a distinção em outro contexto. Entretanto, para que se pudesse capturar o fato de, para a emergência das vogais altas, além do traço de abertura, haver também correlação com o ponto de articulação da átona final e de que a produção das médias-­baixas é garantida pelo traço [aberto3], ambas as regras devem ser assimilatórias: do nó vocálico para as altas [, ] e do traço [+aberto3] para as médias-­baixas [, ]. / This thesis focuses on non-­final post-­tonic mid-­vowels, specifically, the emergence of the high [, ] and low-­mid vowels [, ], the latter characteristic of northeastern dialects. Based on the theoretical framework of Feature Geometry, it was intended to study the phonological motivators that are correlated with the emergence of each vowel form. The main hypothesis verified was if the emergence of [] and [] in non-­ final post-­tonic context, classified in the literature as a result of vowel rising phenomenon, is subject to phonological correlates, considering that up to this point no known study had found a pattern that could formalize a rule. In addition, it was intended to investigate whether the emergence of the low-­mid forms [, ] in non-­final post-­tonic context could also be formalized by rule. Therefore, a word reading experiment was ran in two cities, São Paulo and São Luis. The sample consisted of 40 informants, who were men and women aged between 20 and 30 years, 20 from each locality. Data were transcribed after an acoustic analysis of formant measurement and subsequently coded for statistical analysis. Based on the results, it was found that (i) the emergence of the high vowels was correlated with the presence of a high word final vowel that also shared the same place of articulation as the one in the non-­final post-­tonic context, i.e., coronal to [] and labial to []; and (ii) the emergence of mid-­low was correlated with the presence of the dorsal vowel, therefore, low vowel in word final position. To formalize both rules, it is necessary to assume Wetzels (2011) proposal that neutralization is a mechanism by which contrastive feature values are replaced by their opposite values. However, in order to capture the fact that, for the emergence of the high vowel, besides the open feature, theres also an association to the place of articulation of the word final vowel and that the production of mid-­low is guaranteed by the feature [open3], both rules should be assimilatory: the vocalic node for the high [, ] and the [+open3] feature to low-­ mid [, ].

In this dissertation, I use seismic imaging and waveform modeling methods to investigate melt migration processes and the structure of the magma plumbing system beneath the East Pacific Rise (EPR) and Endeavour segment of the Juan de Fuca Ridge, respectively. This work begins by studying shallow mantle reflections beneath the EPR. I find the amplitude versus offset and waveform characteristics of the reflections to be consistent with a sub-horizontal dunite channels located up to 20 km off-axis. The depth of the dunite channels correlate with patterns of mantle melt delivery and the predicted base of the thermal lithosphere, suggesting the channels are thermally controlled and may have formed in situ via dissolution by focused flow at the base of the lithosphere. This interpretation is consistent with field observations in ophiolites and numerical modeling of melt-focusing channels. The three-dimensional velocity structure of the Endeavour segment is then investigated to identify how patterns of mantle melt delivery influence the segment-scale distribution of crustal melt and crustal accretion. The results from this study indicate that the mantle magmatic system is skewed relative to the ridge-tracking crustal magmatic system and that this skew exerts primary control on magmatic, tectonic, and hydrothermal activity at the Endeavour segment. In regions where mantle melt delivery is axis-centered, mantle-derived melts are efficiently transported from the mantle to the crust, resulting in frequent crustal melt replenishment, associated seismogenic cracking, and enhanced crustal melt content that drives vigorous hydrothermal activity. Conversely, sites of off-axis melt delivery are characterized by less efficient vertical melt transport, resulting in infrequent crustal melt injection and hence, reduced crustal melt content and hydrothermal activity. Next, I focus on how along-axis variations in magma replenishment modulate crustal permeability and the intensity of hydrothermal circulation. Using full-waveform inversion, I show that sites of localized magma replenishment to the axial magma lens, along with induced seismogenic cracking, coincide with enhanced permeability. I conclude that the frequency of magma injection governs hydrothermal circulation patterns and heat flux at mid-ocean ridges. This dissertation includes previously published and unpublished coauthored material.

Esta dissertação tem como objetivo analisar quais são os contextos que permitem ou bloqueiam o processo de alçamento vocálico das vogais médias pré-tônicas, tal como em caf[] caf[e]teria, mas não *caf[e]zinho. Assumiu-se a análise de Wetzels (1991, 1992, 1995), que propõe que este alçamento neutraliza as vogais médio-baixas através do desligamento do traço [aberto3]. Neste trabalho foram checadas três hipóteses, a saber, se a vogal seguinte a vogal médio-baixa influencia no alçamento da mesma, se o tipo de sílaba resultante da derivação influencia no alçamento ou bloqueio das vogais médias e, por fim, se a morfologia exerce influência neste fenômeno. De acordo com os dados do corpus desta dissertação, dentre as hipóteses perseguidas, a morfologia que demonstrou ter maior influência na escolha do processo de alçamento ou bloqueio das vogais médio-baixas. As outras hipóteses foram parcialmente confirmadas. Na hipótese da influencia da vogal seguinte na neutralização vocálica foi comprovado que este exerce influência, no entanto ela não ocorre pelo processo de harmonia e desarmonia. Já na hipótese da influência da sílaba resultante, apenas o contexto CVCCVC é capaz de bloquear a neutralização vocálica, enquanto os contextos que resultam CV são inertes ao processo. Os dados deste trabalho confirmaram a hipótese de Lee (1995) sobre a propriedade dos sufixos de bloquear o alçamento vocálico, e esta tese inova ao propor um estudo mais profundo dos sufixos aumentativos a fim de inseri-los a estes sufixos. Nesta tese também apresenta-se evidências de que a classificação proposta por Mateus e dAndrade (2000) de sufixos avaliativos e z-avaliativos não se mostrou aplicável aos dados do português brasileiro. / This dissertation aims to analyze the contexts that allow or block the process of vocalic raising of pretonic mid vowels as in caf[] caf[e]teria (coffee coffee bar) but not in *caf[e]zinho (small cup of coffee). It was assumed the approach proposed by Wetzels (1991, 1992, 1995), which argues that this vocalic raising neutralizes the mid/low vowels because of a disconnection of the trace [open3] In this work, three hypotheses are checked: 1) if the vowel that follows a midlow vowel has some influence on the vocalic raising of the second vowel; 2) if the type of syllable that results from the derivation has some influence on the raising or on the blocking of mid vowels; and, finally, if the morphology plays some role on this phenomenon. After analyzing the data and following the three hypotheses, it was noted that the morphology has great influence on the choice between raising and blocking the process of the mid low vowels. The other two hypotheses were partially confirmed. The hypothesis that predicts the influence of the following vowel on vocalic neutralization was proved, however it does not occur because of the process of vocalic harmony and disharmony. The hypothesis regarding the influence of the resultant syllable was partially confirmed too; it was seen that in the context of CVCCVC the vocalic neutralization is blocked, whereas in the contexts with CV as a result this blocking process does not occur. Moreover, the analysis of the data confirmed the hypothesis followed by Lee (1995) on the role played by the suffixes on blocking the vocalic raising. The study conducted for this dissertation innovates for proposing a deeper study about augmentative suffixes and for presenting evidences that the classification proposed by Mateus & dAndrade (2000) does not explain what happens in the morphology of Brazilian Portuguese.

A região cárstica de Lagoa Santa (MG) apresenta uma das evidências de ocupação humana mais antiga das Américas, datada do final do Pleistoceno e início do Holoceno. Um intenso registro arqueológico é observado nos períodos compreendidos entre 10.000 a 8.000 anos AP (antes do presente) e 2.000 a 1.000 anos AP. No período intermediário (Holoceno Médio) observa-se nos sítios arqueológicos uma minimização da representação desses vestígios. Autores denominaram esse período de \"Hiato do Arcaico\" que sugeriria que essas populações teriam emigrado por conta de eventos de seca na região, corroborados por dados provenientes da palinologia. O sítio paleontológico RMT-1, situado na região, pertence à bacia do Ribeirão da Mata e contém sedimentos de natureza aluvial datados entre 5.800-4.500 anos AP. e 2.500-1.500 anos AP. Neles estão contidos restos vegetais (pólen, lenho e folhas fósseis). O presente trabalho teve como objetivo principal identificar taxonomicamente assembléias fósseis de folhas por meio da morfologia com a finalidade de reconhecer com quais características fisionômicas atuais essa assembléia mais se assemelharia. As análises de similaridade confrontadas com 47 listas florísticas do Brasil demonstraram que houve alta correlação com Florestas Estacionais Semideciduais e formações de Cerrado. Não foi possível confirmar nem refutar a hipótese do \"Hiato do Arcaico\" já que não houve a presença de taxa que representariam exclusivamente um clima marcadamente seco, entretanto, sugere-se uma estacionalidade nas formações vegetais mais pronunciada ou uma associação fisionômica diferente das vegetações atuais expressadas por mosaico vegetacional. / The karst region of Lagoa Santa (MG) has one of the most ancient evidences of human occupation in Americas, dated from the end of the Pleistocene and beginning of the Holocene. An intense archaeological register is observed in periods between 10.000 to 8.000 years BP (before present) and 2.000 to 1.000 years BP. In the intermediary period (mid-Holocene) a decrease on the representation of these remains could be observed in the archaeological sites. Authors called this period \"Archaic Gap\" which suggests that these populations have migrated due to drougth events in the region that are corroborated by data from the palinological studies. The paleontological site RMT-1, situated in the same region, belongs to the basin of the Ribeirão da Mata and contains sediments of alluvial nature that are dated from 5.800-4.500 years AP. to 2.500-1.500 years BP. In these sediments plant remains (pollen, wood and fossil leaves) were found. The present study aims to identify fossil assemblages of leaves through the morphology to recognize which present physiognomy is closer to the assemblage. The analyses of similarity faced this assemblage with 47 floristical lists from Brazil, and demonstrated that there was a high correlation with semi-decidous stationary forests and cerrado. It was not possible to confirm neither to refute the hypothesis of the \"Archaic Gap\" since there was no observed taxa that could represent exclusively a markedly dry climate However, a more pronounced seasonality in the plant formations or a physiognomic association different from the present vegetational mosaics are suggested.

De nombreuses applications militaires ou civiles, telles que la spectroscopie dans les bandes de transmission de l’atmosphère (bandes 3-5µm et 8-12µm), nécessitent de disposer de sources émettant dans le moyen infrarouge (IR). Les travaux de cette thèse portent sur la génération de rayonnement dans la bande 3-5µm par amplification paramétrique (mélange à quatre ondes) dans les fibres optiques en verres fluorés et en verres de chalcogénures. La première partie de ce travail a été consacrée à l’étude théorique et à la modélisation des conditions d’accord de phase et du gain paramétrique dans des fibres à saut d’indice monomodes en verres fluorés ZBLAN et verres de chalcogénures As2S3 et As2Se3. La nature des résultats obtenus nous a conduit à étudier théoriquement le potentiel de l’accord de phase multimode dans les fibres en verres de chalcogénures. La deuxième partie de ce travail a porté sur la modélisation de l’amplification paramétrique dans des fibres en verres de chalcogénures microstructurées à géométrie hexagonale. Pour ce faire, un modèle simplifié de la propagation dans les fibres microstructurées hexagonales a été développé : le modèle de l’indice effectif de gaine (EIM). Il a ensuite été comparé à une méthode de résolution aux éléments finis. Grâce à cette comparaison, nous avons pu améliorer la précision du modèle EIM en déterminant la valeur de plusieurs paramètres empiriques. Ce modèle nous a alors permis de prédire l’efficacité du processus d’amplification paramétrique dans les fibres microstructurées. L’ensemble de ces études théoriques a permis d’identifier les fibres les plus adaptées à la conversion de fréquence vers la bande 3-5µm. Enfin, nous avons réalisé un banc de mesure de la dispersion chromatique des fibres, ainsi que le dimensionnement d’un convertisseur de fréquence utilisant les fibres identifiées dans l’étude théorique. / Various civil or military applications, such as spectroscopy in the atmospheric transparency windows (3 – 5 µm and 8 – 12 µm ranges), require the use of mid-infrared emitting laser sources.The work presented in this thesis is about light generation in the 3 – 5 µm range by parametric amplification (four-wave mixing) in fluoride and chalcogenide fibers. The first part of the study is devoted to modelizations of phase-matching condition and parametric gain in monomode step-index ZBLAN fluoride fibers as well as As2S3 and As2Se3 chalcogenide fibers. The results obtained in this modelization led to the theoretical study of multimode phase-matching conditions in chalcogenide fibers.The second part of the study presents the modelization of parametric amplification in hexagonal microstructured chalcogenide fibers. A simplified model, called the effective index method (EIM), has been developed and compared to the finite element method. Thanks to this comparison, the accuracy of the EIM model was improved through the determination of several empirical parameters. Using the improved EIM model, we have been able to predict the parametric amplification efficiency in microstructured fibers. Thus, all those theoretical studies allowed us to identify the most adapted fibers for frequency conversion in the 3 – 5 µm range. Eventually, we realized an experimental bench to measure the chromatic dispersion of optical fibers, and we suggested an experimental architecture using the fibers we had indentified in the theoretical study.