Compositions are vectors of nonnegative numbers that sum to a constant, usually one or 100%. They arise in a wide array of fields: geological sampling, budgets,fat/protein/carbohydrate in foods, percentage of the vote acquired by each political party, and more. The usual candidate distributions for modeling compositions -- the Dirichlet and the logistic normal distribution -- have density zero if any component is zero. While statistical methods have been developed for "rounded" zeros, zeros stemming from values below a detection level, and zeros arising from count data, there remain problems with essential zeros, i.e. cases in continuous compositions where a component is truly absent. We develop a model for compositions with essential zeros based on an approach by Aitchison and Kay (2003). It uses a mixture of additive logistic normal distributions of different dimension, related by common parameters. With the requirement of an additional constraint, we develop a likelihood and methods estimating parameters for location and dispersion. We also develop a permutation test for a two-group comparison, and demonstrate the model and test using data from a diabetes study. These results provide the first use of the additive logistic normal distribution formodeling and testing compositional data in the presence of essential zeros.

Ovarian cancer is the deadliest gynecologic cancer for women. Diagnosis at the local stage leads to 91% 5-year survival rates, but only 15% of cases are detected early. Existing screening methods have proven ineffective in large clinical trials. Screening is complicated by the heterogeneity of the disease with multiple types of ovarian cancer originating both on the ovary and in the fallopian tube. Early stage cancer is too subtle for non-invasive imaging techniques such as ultrasound or magnetic resonance imaging. This study evaluates the feasibility and design of dual modality, multispectral fluorescence imaging (MFI) and optical coherence tomography (OCT) endoscopes for improved ovarian cancer screening. The study is broken up into three sections. In the first study MFI is validated in an ex vivo imaging study of human ovarian and fallopian tube tissue samples. Tissue autofluorescence excited by ultraviolet and blue wavelengths is shown to be a promising discriminator between normal and cancerous tissue. The second study combines OCT and MFI into a sub millimeter diameter endoscope designed to screen for ovarian cancer by screening inside the fallopian tube and at the ovary. The small size is required for screening the full length of the fallopian tube. MFI is implemented as a wide-field navigational imaging technique with high sensitivity complemented by high resolution structural depth imaging of OCT over a limited field of view. The final study presents a novel lens design for a scanning fiber endoscope with forward-viewing navigation and side-viewing OCT. A piezo tube is used to scan an optical fiber providing both the navigation channel’s illumination and OCT imaging. The design spatially separates the forward-viewing illumination from the OCT. As the piezo fiber circularly scans at its maximum deviation the OCT beam focus is rotationally scanned out the side of the endoscope tip by a rotationally symmetric double reflection in the cover plate.

Psykisk ohälsa ökar och enligt socialstyrelsen lider cirka 20 % av arbetsför ålder av psykisk ohälsa. En enkätundersökning genomfördes för att undersöka, hur stor betydelse kön, ålder, coping och känsla av sammanhang har på psykisk ohälsa? Totalt insamlades 108 enkäter var av 101 användes för analys. Data analyserades med hjälp av en hierarkisk multipel regressionsanalys och Pearson korrelationer. 39 % av variationen i psykisk ohälsa förklarades av KASAM, copingstil, ålder och kön. Starkast relaterad till ohälsa i regressionsanalysen var KASAM. Högre KASAM hos en individ innebär bättre psykisk hälsa. Diskussion förs kring bland annat fördelar och nackdelar med valda instrument, sned könsfördelning, samhällsnytta och enkätkonstruktion. Att se vilka faktorer som starkt påverkar psykisk ohälsa är av betydelse för vidare forskning för att sätta fingret på vad som påverkar psykisk ohälsa och till vilken grad.

Coherence describes the validity of the internal rules that drive the behaviors of a virtual environment (VE) in presenting a credible scenario. A VR system with a high level of coherence could lead to strong plausibility illusion, which is a key component of the sense of presence. There are few existing studies centered around coherence, and they tend to put the user in a passive role when experiencing the VE without emphasizing on their active participation in the interaction. This dissertation makes up this gap by connecting the concept of coherence with fundamental 3D user interface design that focuses on the algorithms that map the user's actions to the VE's behaviors. Specifically, we inspect the design of coherent interactions for two complicated tasks, namely travel and object manipulation. For travel, we propose a family of redirected walking techniques called "narrative driven cell-based redirection", which lets the user traverse a VE that's much larger than the physical space without breaking the coherence of the scenario. For object manipulation, we propose the novel concept of physics coherence to capture whether an interface conforms to the rules of physics and design several novel techniques that try to balance between physics coherence and usability. Together, we provide some useful tools for designing coherent interactions and discuss how coherence affects user experience in VR interaction. / Doctor of Philosophy / To create a virtual reality (VR) experience that feels plausible, it’s important to consider the validity of the internal rules that drive the behaviors of the virtual environment (VE), which we call “coherence” of a VR system. We discuss how to support coherence in two types of fundamental VR interaction. The first one is travel, which concerns moving the viewpoint around following the user’s intention. For this task, we propose a family of novel interaction techniques called “narrative driven cell-based redirection”, which lets the user traverse a VE that’s much larger than the physical space without breaking the coherence of the scenario. The second one is object manipulation, which is about controlling a virtual object using hand input. For this task, we propose the novel concept of physics coherence to capture whether the interaction conforms to the rules of physics and design several novel techniques that try to balance between physics coherence and controllability. Together, we provide some useful tools for designing coherent interactions and discuss how coherence affects user experience in VR interaction.

Initiatives in many countries to improve learner performances in mathematics in poor communities have been described as largely unsuccessful mainly due to their cursory treatment of curriculum alignment. Empirical evidence has shown that in high achieving countries the notion of coherence was strongly anchored in cognitively demanding mathematics programs. The view that underpins this study is that a cognitively demanding and coherent mathematics curriculum has potential to level the playing field for the poor and less privileged learners. In South Africa beyond 1994, little has been done to understand the potential of such coherent curriculum in the context of the NCSM. This study examined the levels of cognitive demand and alignment between the written, tested and taught NCSM. The study adopted Critical Theory as its underlying paradigm and used a multiple case study approach. Wilson and Bertenthal’s (2005) dimensions of curriculum coherence provided the theoretical framework while Webb’s (2002) categorical coherence criterion together with Porter’s (2004) Cognitive Demand tools were used to analyse curriculum and assessment documents. Classroom observations of lesson sequences were analysed following Businskas’ (2008) model of forms of mathematical connections since connections of different types form the bases for high cognitive demand (Porter, 2002). The results indicated that higher order cognitive skills and processes are emphasized consistently in the new curriculum documents. However, in the 2008 examination papers the first examinations of the new FET curriculum, lower order cognitive skills and processes appeared to be emphasized, a finding supported by Umalusi (2009) and Edwards (2010). Classroom observations pointed to teachers focusing more on rote learning of both concepts and procedures and less on procedural and conceptual understanding. Given the widespread evidence of the tested curriculum impacting on the taught curriculum, this study suggests that this lack of alignment between the advocated curriculum on one hand, the tested and the taught curricula on the other, needs to be investigated further for it endangers the teaching and learning of higher order cognitive skills and processes in the FET mathematics classrooms for the poor and less privileged. Broader evidence suggests that this would work against efforts towards supporting the upward mobility of poor children in the labour market.

The aim of this research was to longitudinally and quantitatively investigate sense of coherence (SOC) and coping strategies as predictors of compassion satisfaction (CS) and compassion fatigue (CF) as measured by secondary traumatic stress (STS) and burnout (BT) during the first six months of training in a professional psychology training programme. Trainee therapists’, “dramatically shift” their “focus of functioning over time” to adorn the personality and self of the therapist (Rønnestad & Skovholt, 2003, p. 28). This adaptive process may initially unravel over six months as trainees balance client and workload stressors (Hill, Sullivan, Knox & Schlosser, 2007; Tryssenaar & Perkins, 2001). However, research on the developmental processes behind the negative (CF) and positive (CS) avenues of therapeutic stressors is lacking in the trainee therapists’ population, especially quantitatively (Schwing, LaFollette, Steinfeldt & Wong, 2010; Thériault, Gazzola & Richardson, 2009). This research aimed to explore these issues in relation to professional development through SOC and coping as predictors of CS and CF over a six month training period. Variables were investigated quantitatively through the Professional Quality of Life Scale (ProQOL) (Stamm, 2010) the Brief COPE (BCOPE) (Carver, 1997) and the 29-item self-report Orientation to Life Questionnaire (OLQ) (Antonovsky, 1987). As such, the primary focus of this research was on how SOC and coping strategies were utilised by trainee therapists as process variables in predicting the positive (CS) and negative (CF) avenues of therapeutic work over a six month period of psychotherapy training. Findings suggested that, at the beginning of training, sense of coherence was directly associated with the core outcome variables (CS and CF (as measured by STS and BT). When trainee therapists started seeing clients two months later, the effect of SOC was mediated by coping. At the end of training, only coping was directly associated with outcome variables as the effect of SOC on CS and CF disappeared. These implications are further discussed in the research.

Dans les année récentes, les systèmes d'atomes froids ont été reconnus comme des outils prometteurs pour réaliser des simulateurs quantiques, ainsi que pour différentes applications en information quantique. Parmi eux notamment la jonction Josephson bosonique, un système de bosons ultrafroids dilués pouvant occuper deux modes, a été employée pour réaliser un interféromètre atomique, qui a permi d'estimer un déphasage avec une précision dépassant la limite classique. Dans cette thèse, nous étudions d'un point de vue théorique la production, la détection et la décohérence d'états intriqués qui peuvent être utilisés pour l'interférométrie de haute précision dans une jonction Josephson bosonique. Parmi ces états quantiques utiles se trouvent les états comprimés et les superpositions macroscopiques d'états cohérents. Dans la première du manuscrit, nous démontrons que les superpositions macroscopiques d'états cohérents peuvent être créées pendant la dynamique qui suit un arrêt soudain du couplage entre les deux modes de la jonction, puis nous étudions des protocoles de détection expérimentale. Il existe inévitablement dans chaque expérience des sources de bruit, les principaux étant le bruit de phase, induit par des fluctuations des énergies des deux modes, et la perte d'atomes. La présence de bruit induit de la décohérence et dégrade les corrélations quantiques des états manipulés. Dans la deuxième partie du manuscrit nous analysons en détail la façon dont les corrélations quantiques utiles des états comprimés et des superpositions macroscopiques sont dégradées par le bruit de phase. Nous montrons que, pour des intensités de bruit modérées, les superpositions d'états cohérents à plusieurs composantes sont des candidats intéressantes pour l'interférométrie de précision. Enfin, nous étudions l'effet de la perte d'atomes sur la formation des superpositions macroscopiques, en montrant comment la décohérence agit sur la matrice densité du système / In recent years, cold atomic systems have been recognized as very promising tools for quantum simulators and for applications in quantum technology. In particular, a Bose Josephson junction (BJJ) - a system of ultracold dilute bosons which can occupy two modes - has been used to realize an atomic interferometer, allowing to estimate a phase shift with a precision beyond the classical limit. In this thesis we study theoretically the production, detection and decoherence of entangled states which can be used for high-precision interferometry in a Bose Josephson junction. Among such useful quantum states are atomic squeezed states and macroscopic superpositions of coherent states. In the first part of the thesis, after demonstrating that macroscopic superpositions of coherent states can be created during the dynamics following a "quench" of the coupling between the two modes of the junction, we study protocols for their experimental detection. In the experiments there are unavoidable sources of noise, the major sources being phase noise, induced by stochastic fluctuations of the energies of the two modes of the BJJ, and particle losses. The presence of noise induces decoherence and degrades the quantum correlations of these states. In the second part of the thesis we analyze in detail how the useful quantum correlations of squeezed states and macroscopic superpositions are degraded by phase noise. We show that for moderate phase noise intensities multicomponent superpositions of coherent states are interesting candidates for high-precision atom interferometry. Finally, we address the effect of atom losses on the formation of macroscopic superpositions, showing how decoherence affects the system density matrix.

Neste trabalho desenvolvemos um novo método para análise biométrica do olho. Essa análise se compõe de medidas dos parâmetros biomecânicos, ou seja, espessura da córnea, distancia entre a córnea e o cristalino, espessura do cristalino, e distancia entre o cristalino e a retina. Este novo método funciona utilizando o princípio da interferometria com laser de baixa coerência. O conhecimento desses parâmetros e de suma importância para o fornecimento de dados necessários para o implante de lentes intra-oculares, em casos de catarata. Alem disso, eles permitem diagnosticar patologias clinicamente caracterizadas por suas alterações. O instrumento convencionalmente utilizado para essas medidas e o biômetro ultra-sônico. Embora esses biômetros sejam práticos e eficientes, a resolução por análise ultra-sônica esta limitada ao fato do tecido ocular não fornecer ecos satisfatórios em freqüências muito acima de 10 MHz. Uma limitação na resposta de freqüência determina uma subseqüente limitação na precisão de medida, já que esta será tanto maior quanta maior a freqüência. Uma variedade de técnicas diferentes tem sido experimentada nos últimos dez anos visando estabelecer um método mais preciso. Entretanto, várias das alternativas existentes têm sido rejeitadas devido à complexidade operacional e altos custos. A técnica interferométrica, entretanto, reúne alta resolução, simplicidade operacional e baixo custo. Isso pode ser constatado pelos resultados obtidos, os quais revela um enorme potencial aplicativo para futuros trabalhos de pesquisa ou mesmo de diagnose. / In this work we have developed a new method for biometric analysis of the eye. This analysis consists of measurements of biomechanical parameters, like thickness of the cornea, distance between the cornea and the crystalline lens, thickness of the crystalline lens and distance between the crystalline lens and the retina. In this new method we use the interferometric principle with a low coherence laser. The knowledge of these parameters is very important in order to supply the necessary data for the implant of intraocular lenes, in the cases of cataract. Besides of allow the diagnosis of the pathologies, which are characterized by their changes. The instrument used in the measurements is an ultrasonic biometer. However the resolution of this instrument is limited by the ocular tissue, which does not allow satisfactory echos in frequencies above 10 MHz. A variety of the techniques have been used in the last ten years in the order to establish a more accurate method. However most of the existing alternatives have been rejected due to operational complexity and high cost. The interferometric technique unites high resolution, operational simplicity and low cost. This can be concluded by the results obtained in this work, which demonstrate the great potentiality of the method for future in academic research or clinical diagnosis.

Thesis advisor: Vincent Cho / District leaders are attempting to navigate unprecedented federal and state policy pressures to create a coherent plan for improvement with limited guidance from research. Rorrer, Skrla, and Scheurich (2008) identified establishing policy coherence as one of four essential roles in systemic reform performed by district leaders. This qualitative case study explored how leaders in one Massachusetts public school district that had demonstrated signs of improving achievement and equity attempted to establish policy coherence. Drawing primarily upon semi-structured interviews, this study found that district leaders enacted the role to varying degrees in ways that were consistent with Rorrer et al. (2008). In particular, building leaders were much less apt to respond to external policies in a proactive and deliberate manner. Furthermore, district leaders worked to mediate policies in service to local goals and needs in a variety of ways. Recommendations include how district leaders can enact the role in a more proactive and deliberate manner while setting clear goals and developing collaborative partnerships with schools, all which allow them to craft coherence more effectively. / Thesis (EdD) — Boston College, 2016. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Leadership and Higher Education.

Este estudo abordou os aspectos teóricos e experimentais relacionados ao desenvolvimento de um sistema de tomografia por coerência óptica (OCT) no domínio de Fourier sensível à polarização (PS-FD-OCT) e a sua utilização na determinação da Matriz de Mueller (MM-OCT). O estudo iniciou-se com uma revisão bibliográfica que abordou desde os primeiros estudos relacionados à técnica até o estado da arte, bem como o formalismo matemático da interferometria de baixa coerência no domínio espectral e polarização da luz. Realizaram-se estudos baseados em simulação numérica sobre três tipos diferentes de algoritmos, responsáveis pela recuperação do sinal de espalhamento, sendo eles: a Transformada de Fourier Direta; Interpolação e Zero-Filling. Ao fim dessa etapa concluiu-se que o algoritmo Zero-Filling 2N apresentou melhores características quando comparado aos outros algoritmos. Na parte experimental, primeiramente, diferentes arranjos OCT foram montados e medidas realizadas para verificação aspectos relacionados à teoria. Consecutivamente, utilizando uma amostra polimérica, realizaram-se imagens de birrefringência, que permitiram a determinação da birrefringência da amostra quantitativamente. Finalmente, imagens em diferentes estados de polarização foram realizadas, através delas determinou-se as imagens referentes aos elementos das Matrizes de Mueller, que foram analisadas individualmente. / This study approached theoretical and experimental aspects related with the development of a polarization sensitive, Fourier domain, optical coherence tomography system (PS-FD-OCT) and its utilization on the Mueller Matrix determination. This work began with a bibliographic revision, which describes since the early studies to the actual state of the art of the technique. The mathematical formalism of Fourier domain low coherence interferometry and light polarization was performed as well. Studies based on numerical simulations, of three different algorithm types, responsible to recover the scattering profile, were done. The implemented algorithms were: Direct Fourier Transform, Interpolation and Zero-Filling. By the end of the simulation study, was possible to conclude that the algorithm Zero-Filling 2N presented better characteristics when compared with the others. In the experimental part, firstly different OCT setups were assembled and measurements were done in order to verify aspects related with the theory. Then, using a polymeric sample, birefringence images were performed, which allowed determining the sample birefringence quantitatively. Finally, images taken of different polarization states were collected, and through then images related with the Mueller Matrix elements were calculated, which were analyzed individually.