VictorJuiz/thesis huggingface dataset:
Programs that work [electronic resource] : mathematics teacher preparation programs in Japan, the United States, and Finland
Keywords: Education.

This study examines successful and internationally renowned mathematics teacher training programs in Japan, the United States, and Finland. Using interview data from program instructors, prospective mathematics teachers, and program directors, as well as from my own experiences as a teacher and researcher in each of these countries, I examine themes in mathematics teacher education are consistent across these three cultural contexts, namely the relationship between theory and practice, authenticity, and the goals of mathematics teaching. In addition, I examine themes unique to each context, such as juku (Japan), English Language Learners (the United States), and equity versus elitism (Finland). I also look at the themes of relationships and expectations that are reflected in my personal account of learning to teach in Japan, the United States, and Finland. Despite recent emphasis on reform teaching methods, such as those proposed by the National Council of Teachers of Mathematics, and drastic reforms in the last decade through policies such as No Child Left Behind and Race to the Top, the United States continues to fall further behind in international comparisons of mathematics achievement. Believing that problems do exist within the American educational system, educational research leaders have pointed to the continued educational success of nations such as Finland and Japan in order to learn what features of these high-performing systems might be components for success. While there is great value in international comparisons, this viewpoint ignores high-performing programs in the United States and ignores the fact that not all overseas programs are equal. I argue that the exemplary cases are the most valuable, including the case of well-established programs in the United States as well.
Propagation phenomena in reaction-advection-diffusion equations [electronic resource]
Keywords: Mathematics.

Reaction-advection-diffusion (RAD) equations are a class of non-linear parabolic equations which are used to model a diverse range of biological, physical, and chemical phenomena. Originally introduced in the early twentieth century as a model for population dynamics, they have been used in recent years in diverse contexts including climate change, criminal behavior, and combustion. These equations are characterized by the combination of three behaviors: spreading, stirring, and growth/decay. The main focus of mathematical research into RAD equations over the past century has been in characterizing the propagation of solutions. Indeed, these equations are characterized by the invasion of an unstable state by a stable state at a constant rate (for instance, the invasion of empty space by a population until the environmental carrying capacity is reached). In general, this can be characterized by the existence, uniqueness, and stability of traveling wave solutions, or solutions with a fixed profile which move at a constant speed in time. In general, the speed and shape of these traveling waves gives us the speed with which the stable state invades the unstable state. This thesis assumes the following trajectory, investigating two specific RAD equations: the Fisher-KPP equation, used in population dynamics, and a coupled reactive-Boussinesq system, used to model combustion in a fluid. For the former equation, we prove results regarding the precise spreading rate, and for the latter equation, we prove an existence result for a special solution that generalizes the traveling wave. In the first part of this thesis, we prove two results quantifying the precise speed of spreading for solutions to the Cauchy problem of the Fisher-KPP equation. The first of these results, concerning localized initial data, provides intuition for a lower order term obtained non-rigorously in. Specifically, we prove a quantitative convergence-to-equilibrium result in a related model, which has been used as a close approximation of the Fisher-KPP equation. The second of these results, concerning non-localized initial data and building on the work of Hamel and Roques, quantifies the super-linear in time spreading of the population. Here we compute the highest order term in the spreading for a broad class of initial data. In the second part of this thesis, we look at a coupled system that models combustion in a fluid, and we prove a qualitative propagation result. Unlike classical models, this relatively new system accounts for the effect of advection induced by the buoyancy force that results from the evolution of the temperature. Essentially, this means that we take into account the phenomenon that ``hot air rises.'' We exhibit a generalized traveling wave solution of this system, called a pulsating front, in two-dimensional periodic domains. To our knowledge, this is the first result regarding the existence of ``pulsating fronts'' in a coupled system.
Prospects for alternative fuels in heavy-duty diesel engines with sootless emissions [electronic resource]
Keywords: Mechanical Engineering.

The emission of carbonaceous particulate matter (soot) from work-producing devices is a global problem. Direct-injection, compression-ignited (Diesel) engines are a source of soot emissions that are problematic because they are mobile and operate regularly within populated regions. The subsequent effect on air quality is a serious health concern due to their small size and potential penetrability within the human body through the lungs. Furthermore, their contribution to atmospheric aerosols has a significantly negative effect on the environment. The problem with Diesel engine combustion is primarily a function of the fuel properties and subsequent combustion kinetics. The attraction of No.~2 Diesel fuel is that it is easily autoignitable, and for a typical direct-injection, compression-ignited engine this is a desirable quality. By employing a high-temperature combustion strategy, however, a host of alternative fuels become viable. This work addresses the prospects for using non-traditional fuels within a direct-injection, compression-ignited engine. A number of alternative fuels are identified as having potential, namely methanol, ethanol, butanol, dimethyl ether, synthesis gas, and methane (as a surrogate for natural gas). These are attractive because they are either oxygenated (and rely less on ambient gas entrainment) or gaseous (and can turbulently mix with ease). The combustion behavior of each fuel is examined by two means: First, a simple and well-controlled apparatus allows single-jet combustion to be imaged with a high-frame-rate, color digital camera. Second, a computationally efficient, quasi-dimensional jet model is used to explore each fuel with a detailed chemical mechanism, and includes a multi-step soot model. Once each fuel is examined independently, a subset are identified as forming too much soot such that their use within a production engine would emit levels above the EPA regulation standard. Two separate soot reduction methods are then explored within this work: dilution of the fuel with water, and dilution of the ambient gas with exhaust gas species. For each strategy, images are obtained that provide direct evidence of reduced soot formation. The jet model is then examined in detail to gain deeper insight into the potential mechanisms leading to the observed soot reduction.
The public impact of Latin America's approach to open access [electronic resource]
Keywords: Education.

This study explores the extent to which research published in Latin America—where the vast majority of which is made freely available to the public—has an impact and reach beyond the academic community. It addresses the ways in which the study of research impact is moving beyond the counting citations, which has dominated bibliometrics for well over the last 50 years. As more of the world's research is made freely available to the public, there is an increasing probability that the impact and reach of research extends beyond the confines of academia. To establish the current extent of public access, this study explores who the users of Latin American research are, as well as their motivations for accessing the work by using a series of simple pop-up surveys, which were displayed to users of the two largest scholarly journal portals in Latin America. The results, after thousands of responses, indicate that traditional scholarly use makes up only a quarter of the total use in Latin America. The majority of use is from non-scholar communities, namely students (around 50% of the total use) and from individuals interested for professional or personal reasons (collectively around 20% of the total use). By linking the survey responses to the articles being read, it was also possible to identify points of convergence and divergence in student, faculty, and public interest groups. Finally, this study employed methods from a new field of inquiry, altmetrics, in an attempt to capture engagement with research on the social Web. The success of such methods for the Latin American case were limited due to low coverage levels, but the research nevertheless contributes to the understanding of nascent field of altmetrics more broadly. The study concludes with a discussion of the conceptual, political, curricular, and methodological implications of this new approach to scientific communication.
Quantifying paleoclimate dynamics using isotopes in precipitation [electronic resource]
Keywords: Earth System Science.

As anthropogenic emissions of greenhouse gasses continue to alter the Earth's climate, it becomes increasingly vital to understand how the Earth system has responded to high temperatures and pCO2 in the past. The Cenozoic era in particular offers unique insights into climate systems equilibrated with modern to near-future radiative forcing and comparable global geographic boundary conditions. Isotopes in precipitation ([delta] D and [delta] 18O) are one of the more ubiquitous tools used to investigate Cenozoic climate, as they are sensitive to a number of hydro-climatic factors including rainout patterns, terrestrial moisture recycling, evaporative source conditions, and atmospheric mixing by transient eddies. While this sensitivity allows for the potential characterization of large-scale hydrologic dynamics, separating out these disparate effects remains a major challenge for interpreting proxy records. This dissertation aims to address this challenge by using a reactive transport model of isotopes in precipitation to develop a framework for testing hypotheses of past conditions against proxy records. This framework is then applied along with other established methods to investigate a number of Cenozoic climate questions including: (1) migration of the Pacific storm track in response to changes in the structure of tropical Pacific SST's and initiation of Northern Hemisphere glaciation through the Plio-Pleistocene; (2) peak eustatic Pliocene sea level and East Antarctic Ice Sheet stability; and (3) global latent heat transport under Early Eocene hothouse climate conditions.
Quantitative image analysis reveals diet-driven changes in gut microbiota localization [electronic resource]
Keywords: Microbiology and Immunology.

The community of commensal bacteria, viruses and eukaryotic microorganisms within our gastrointestinal tract, the gut microbiota, is a fundamental part of our biology. Foundational work has demonstrated that these organisms are required for proper development of the immune, circulatory and central nervous systems; and changes in the membership of this community are associated with pathologies such as obesity, colorectal cancer, type 2 diabetes and inflammatory bowel diseases. Though much research has focused on community composition assessed by pyrosequencing, emerging evidence suggests that many of these disease states are also associated with changes in bacterial localization within the intestines. However, standardized imaging and quantitation methods have not been established yet in the field. The work in this dissertation develops and validates such methods, and applies them to determine the effects of a low fiber diet on spatial organization of the gut microbiota. Chapter 1 contains a literature review of existing tools to study the microbiota, with a focus on the advantages and limitations of different imaging strategies. Chapter 2 includes the histological, imaging, and computational methods developed to develop a high-resolution imaging and quantification pipeline, using gnotobiotic and humanized mice on a polysaccharide-deficient diet as a test case. Chapter 3 further develops the work from Chapter 2, with a focus on host response to a low fiber diet. Chapter 4 contains perspectives and future directions for the applications of imaging to the gut microbiota field.
A quantitative study of the axonal transport mechanics in neurons [electronic resource]
Keywords: Chemistry.

Neurons are highly polarized cells with their axon often extending over large distances away from the cell bodies (up to 1 meter in axonal length with a cell body less than 50 micrometer in diameter). Given that the majority of neuronal proteins and materials are synthesized in the cell body, such a long axon precludes effective diffusion of soma-produced proteins to their presynaptic destinations at the axonal terminals. As a result, neurons rely extensively on active axonal transport to deliver newly synthesized synaptic proteins, ion channels, lipids, and mitochondria to their axonal destinations via anterograde transport. On the other hand, retrograde axonal transport is responsible for carrying molecules and organelles destined for degradation from the axonal terminals back to the cell body. A highly efficient and tightly regulated machinery is thus required for a robust long-range transport of materials to ensure the neurons' proper growth, maintenance and survival. This thesis is a quantitative study of the underlying mechanism of axonal transport, with a specific focus on the retrograde axonal transport machinery in neurons. In our experimental setup, the axonal transport of cargos can be directly visualized in real-time using a neuronal microfluidic platform and fluorescence microscopy technique. We observe that cargos have high tendency to slow down their transport speed when crossing various obstacles along the axon such as non-moving cargos and stationary mitochondria. Single molecule study of retrograde nerve growth factor transport reveals that mechanical tug-of-war and intracellular motor regulation are complementary features of the near-unidirectional endosome directionality. Specifically, a stochastic mechanical simulation suggests that the endosomes are driven on average by 5-6 active dyneins and 1-2 down-regulated kinesins. This result is further supported by a study of the dynamics of endosomes detaching under load in axons, showcasing the cooperativity of multiple dyneins and the subdued activity of kinesins. Lastly, we present a quantitative characterization of the complex behavior of light-sensitive cryptochrome 2 (CRY2) protein under blue light. The results contribute to the understanding of the light-inducible CRY2 system and can be used as a guide to establish new optogenetic strategies to probe cellular processes in live cells.
Quantum edge transport in topological insulators [electronic resource]
Keywords: Physics.

In the quantum Hall effect, electrons circulate in one direction around the edge of a 2D sample. The robustness of these states is protected by the topology of the band structure and scattering is only possible if thermally-activated 2D conduction provides a path across the bulk. However, the environmental conditions required for the effect (large magnetic fields and, usually, low temperatures) make it unsuitable for most practical applications. This dissertation discusses the implementation of two similar topological transport phenomena, in the absence of magnetic fields, using the class of materials known as topological insulators. First, it reports on investigations into the quantum spin Hall effect, a time-reversal-symmetric state with counterpropagating, spin-polarized edge channels. Mean free paths in this case are limited to only a few micrometers due to a scattering mechanism under investigation. Second, it reports on recent results on the quantum anomalous Hall effect demonstrating part-per-10,000 conductance quantization, arising from nearly perfect transport through one-way edge channels, in magnetically-doped thin films of 3D topological insulators. It shows that dissipation only occurs due to thermally-activated states that can be nearly eliminated via an unexpected magnetocaloric effect.
Quaternion tools for mathematical prediction [electronic resource]
Keywords: Electrical Engineering.

Existing quaternion neural network structures suffer from two key limitations: first, these structures are computationally expensive to train; and second, they do not perform all mathematical operations in the quaternion domain. Existing quaternion neural networks are limited by using a real-valued, nonlinear activation function independently on each quaternion dimension. The original contributions to knowledge in this work address both limitations. The computational limitations are addressed through the introduction of a version of quaternion Backpropagation that requires significantly fewer training cycles for convergence and is further addressed with the introduction of Direct Quaternion Error, an algorithm that performs equivalently to quaternion Backpropagation under certain conditions and requires considerably less computation per training cycle. As for performing mathematical operations in the quaternion domain, a new multi-valued quaternion neuron and neural network structure are proposed, wherein a discrete-valued activation function that operates simultaneously in all four quaternion dimensions is introduced. Since there are no standard datasets for the evaluation of quaternion neural networks, two applications are used to demonstrate the effectiveness of the proposed techniques. The problems of automated prostate cancer Gleason grading and chaotic time series prediction are investigated. Both of these are difficult prediction problems and are appropriate for benchmarking mathematical classification and prediction techniques. The high-speed quaternion neural network training techniques are shown to be effective in the Gleason grading experiments, and the new multi-valued quaternion neural network is shown to outperform both real-valued and other quaternion-valued neural networks in the chaotic time series prediction.
The queer chronotope [electronic resource] : the confessional return in the nineteenth-century fantastic
Keywords: Comparative Literature.

Rousseau claims that in writing The Confessions, he seeks to make himself completely transparent to his reader. And indeed, recourse to the confessional mode in eighteenth-century sentimentality often points to sympathy with another, or the desire for thoroughly open communication. With the turn to the nineteenth century, literary historians argue that psychological realism supplants the affective charge of sympathetic discourse all the while retaining the (now implicit) claim to total transparency. In other words, where the diarist once confessed, now the panoptic gaze of the dispassionate realist narrator unearths. But effusive expressions of love, care, and admiration between men, uneasily coexisting with paranoias born of fretful musings and intractable jealousies, continue to haunt the literature of terror in the nineteenth-century. And those expressions are still inscribed in a confessional mode. Therefore, this dissertation sets out to track the persistence of this discursive mode in the traditions of the fantastic in the British, French, and German novels. This dissertation examines how confession flows into a generic configuration called the queer chronotope, which replaces eighteenth-century sentimentality. But distinct to the male confessional plots of the queer chronotope is the denial of sympathy. The texts in question betray the affective mark of being cut off from the sympathetic other of sentimentality. Unlike their literary fathers, the neurotic heroes of male confessional plots no longer delight in unburdening through narrative. Instead, they find themselves trapped in a morose narrative body. The confessional mode in the queer chronotope, as this dissertation argues, becomes a solipsistic prison in which a weakened narrative ego confesses before an omnipotent super ego, deriving from the fear of losing paternal love. And therefore the male confessional plot rehearses the same frustration of satisfaction of the ego ideal, which means narrativizing hypochondria, melancholy, narcissism, self-loathing, and other male obsessional disorders. As a narrative poetics, confession turns into the repetition of an unpleasure.
Rainbow Junction: South Africa’s Born Free Generation and the Future of Democracy
Keywords:  Program in International Relations
Center on Democracy Development and the Rule of Law
Program on Urban Studies
Stanford University
South Africa
Born Free
Afrobarometer
Mixed Methods
democratic transitions
youth attitudes
ethnography
civic micro-practices
civic engagement
Rainbow Nation
Thesis

Fifty-five percent of South Africa’s population today is under 25 years old, born with no living memory of apartheid. By demography alone, this “born free” generation will play an increasingly central role in the nation’s civic and political life. Therefore I ask: What attitudes, values, and beliefs characterize the born free generation’s views on democracy and civic engagement in South Africa? And what do these imply for the country’s future? Given South Africa’s democratic transition, I initially hypothesized that the born frees would possess distinctive views; like many researchers and authors, I took the very term “born free” to suggest a different set of attitudes about democracy and a certain liberation from the fetters of apartheid. Yet my results indicate that at the national level, South African born frees do not possess uniform views on the psychological, political, and economic aspects of democracy and governance. Although the generation never lived through apartheid, its lived experience is historically freighted and differs tremendously along lines of race and class. My analysis also shows something else: deep, pervasive racial cleavages in the psychological, political, and economic attitudes of the born frees, and in South Africa more generally. In one urban Johannesburg neighborhood, my data indicate that its born frees, overcoming both racial stratification and planned gentrification, do possess distinctive values and beliefs on the hyper-local level: my ethnographic work shows that these young South Africans have developed numerous civic micro-practices that enable and are enabled by interpersonal trust and use difference as a political resource. Hyper-local civic interactions can percolate upward, a process essential to consolidating democracy in the Rainbow Nation.