VictorJuiz/thesis huggingface dataset:
Attitude determination of passively magnetically stabilized nano satellites [electronic resource]
Keywords: Aeronautics and Astronautics.

The work in this thesis enables attitude determination to be performed on passively magnetically stabilized nano satellites using only a measurement of the solar vector. Existing state of the art methods can achieve an accuracy of one degree using a full attitude sensor suite. The methods presented in this thesis achieve an accuracy of five degrees at a reduced mass and power cost, opening up new mission opportunities for nano satellites and providing a backup capability for existing designs. Two approaches to attitude determination are presented. Firstly, a batch algorithm is described that simultaneously estimates both satellite attitude and unknown parameters in the satellite's attitude dynamics model. Secondly, an online attitude determination capability is developed by extending the commonly employed multiplicative extended Kalman filter (MEKF) for situations where no gyros are present. Both approaches were applied to actual flight data from NASA's O/OREOS and the University of Michigan's RAX-1 nano satellites and results verified against independent data.
Automated handling of Drosophila for biological investigation [electronic resource]
Keywords: Electrical Engineering.

The fruit fly, Drosophila melanogaster, is a key model species for biological research. Trained humans can manipulate, inspect and dissect individual flies, but these operations are often rate-limiting bottlenecks for screening and experimentation. Here I present a high-speed, economical robot for handling non-anesthetized adult flies. Using machine vision the robot tracks a fly's thorax and gently grabs it ~400 ms after targeting. The robot can then translate and rotate the picked fly, inspect its phenotype, dissect or release it, and thereby rapidly prepare multiple flies sequentially for a wide range of experimental formats. In one illustration, the robot restrained flies and dissected the cuticle to permit two-photon imaging of neural dynamics. In another, the robot sorted flies by sex. The robot's tireless capacity for accurate, repeatable manipulations will enable experiments and biotechnology applications that would otherwise be totally infeasible, especially those requiring high-throughput capture, testing and assessment of individual fly attributes.
Automatic mesh adaptation using the continuous adjoint approach and the spectral difference method [electronic resource]
Keywords: Aeronautics and Astronautics.

In this thesis, mesh adaptation using continuous adjoint is tested on two-dimensional Euler equations. Both the flow solver and the adjoint solver are implemented with the high order spectral difference (SD) method. Both h and p adaptation are studied. The test cases include a half-cylinder in subsonic flow and a NACA 0012 airfoil in subsonic and transonic flows. It is found that h-refinement is more suitable for flow discontinuities while p-refinement offers a better performance in smooth flows. Both adaptation methods lead to a faster functional convergence than uniformly h or p refined meshes. In addition, the adapted meshes show similar patterns as those arrived at using the discrete adjoint method. Comparisons between different adjoint target output functionals are also made.
Balancing stem cell self-renewal and differentiation in the skin [electronic resource]
Keywords: Developmental Biology.

The skin is a classical example of a tissue maintained by stem cells, but the identity of the stem cells that maintain the different epidermal compartments and the signaling mechanisms that control their activity remain unclear. Using lineage tracing and quantitative clonal analyses, we show that the Wnt-target gene Axin2 marks epidermal stem cells that compete neutrally and require Wnt/[beta]-catenin signaling to proliferate. By RNA in situ hybridization, we show that the Axin2-expressing stem cells produce their own self-renewal signals in the form of Wnt proteins. These cells also express secreted Wnt inhibitors, including Dkks, which accumulate at high levels around more differentiated cells. We propose a new model for skin maintenance, in which epidermal stem cells produce short-range Wnt signals to maintain their own identity and function, while simultaneously secreting longer-range inhibitors that suppress Wnt signaling to promote differentiation of the stem cell progeny.
Bank dominance: Financial sector determinants of sovereign risk premia
Keywords:  Department of Economics
Stanford Department of Economics
Thesis

This paper investigates the persistence, extent and nature of the correlation between banking and sovereign credit risk in the European financial crisis. I use Credit Default Swap (CDS) premia on sovereigns as a measure of sovereign risk while using a specially constructed CDS Banking Risk Index (BRI) to measure the financial sector risk of each country. This paper finds that there is “bank dominance” in the determination of sovereign risk premia in the European financial crisis even when fiscal variables are included in the estimation. The Banking Risk Index is the primary statistically significant determinant of sovereign risk premia in the crisis period. Moreover, this paper finds that the correlation between banking and sovereign risk increases with an increase in the financial sector risk, measured by the BRI—in times of greater financial sector risk, banking and sovereign risk are jointly evaluated in the market, even more so than usual.
Barker’s Hypothesis and the Selection Effect: The Repercussions of Fetal Malnutrition in the Context of the Great Chinese Famine in 1959-1961
Keywords:  Department of Economics
Stanford Department of Economics
China
famine
health
Barker’s hypothesis
gender
Thesis

The causal pathway linking prenatal and early childhood environments with health and economic outcomes in adulthood has been a question that has intrigued doctors, economists, and policymakers alike. In drawing upon the regional and temporal variation in the intensity of the Great Chinese Famine in 1959-1961—the largest famine known to-date, I find that prenatal exposure to the famine results in a negative impact for both men and women. Specifically, women were found to have a higher likelihood to be diagnosed with diabetes, whereas men were found to have a lower likelihood to be presently working. Furthermore, these results are reinforced with additional specifications. These findings demonstrate that the impacts of the famine have considerable ramifications on the health and wellbeing of those affected more than 40 years later, and strengthen support for the importance of programs that reduce nutritional during the period of gestation and early childhood years.
Being present [electronic resource] : expanding consumers' perceptions of time through momentary temporal focus
Keywords: Business.

One of the most striking features of our modern society is the high degree to which time is valued: For many Americans, time has become the most precious consumer commodity and the ultimate scarcity. Indeed, prior research has documented that those who consume, work, and live in our society are feeling increasingly starved for time and that this sense of time famine can take a toll on health and well-being. So, how can we combat this time shortage? Approaching this problem from a psychological perspective, this dissertation illustrates that altering people's perceptions of their temporal resources may be one possible remedy for these feeling of time starvation. Although increasing the objective amount of time that people possess has inherent limitations (there are, after all, only 24 hours in a day), this dissertation provides evidence that this time shortage problem has an important perceptual component and that it is possible to meaningfully expand people's subjective sense of time availability. Across a series of laboratory experiments, this dissertation reveals that one's momentary temporal focus (i.e., the extent to which one is currently focused on the past, the present, and the future) influences perceptions of time: A stronger focus on the present expands people's ensuing perceptions of current time availability, making them feel more time affluent or "rich" in time. Exploring this time expansion effect across diverse dependent variables and various methods of construct activation (including direct cognitive means [e.g., priming tasks and deep thinking exercises], indirect behavioral means [e.g., slow controlled breathing], and indirect emotional means [e.g., the experience of awe]), this work also demonstrates the robustness of the effect, identifies a specific instance when the effect does not occur, reveals the mechanisms underlying the effect, and provides a variety of insights into the psychology of time. Moreover, the results of these experiments also demonstrate that this perceptual expansion of time alters people's decision making, preferences, cognitive abilities, behavioral tendencies, and psychological well-being. Thus, this dissertation underscores that shifting people's perceptions of time availability can have significant downstream consequences for both consumers and managers.
Beyond "limited English proficiency" [electronic resource] : reading, bilingualism, and long-term English learners
Keywords: Education.

This dissertation, a multiple case study of five long-term English learners (LTELs), problematizes the prevalent interpretation that their low standardized reading test scores are evidence of their "limited English proficiency." Rather than relying on this predominant assumption, I spent a year examining five high school LTELs' reading practices in biology and English language arts through ethnographic observations, interviews, think-alouds, and the collection of selected documents. Both my data collection and the subsequent analysis were informed by a conceptualization of reading as a social practice. This perspective recognizes reading, as measured on standardized tests, as a cultural product that reflects particular sociocultural ways of making meaning with texts. The analysis, which relied primarily on iterative coding and analytic memoing, led to a multifaceted representation of the five focal students' reading practices. The findings indicate that the focal students were inexperienced with the kinds of reading tasks that they encountered on standardized assessments of reading. In particular, they were unaccustomed to autonomous and silent reading of disciplinary texts. Moreover, students' beliefs about reading reflected what previous research has described as "more passive" ideas about comprehension. Nevertheless, during think-alouds, students demonstrated the ability to engage in comprehension strategies that are prized by the research literature. In summary, these findings suggest that the interpretive focus on English proficiency obscures the students' English-speaking identities and ignores multiple factors beyond language proficiency that influence the way they construct meaning with texts. Specifically, the results suggest that the five focal students' difficulties with reading are not unique to ELs and highlight the importance of their in-school experiences with reading. The implications of this research are integral to research, policy, and practice that seek to create more appropriate instructional environments for LTELs.
"Big think" or "bottom-up"? [electronic resource] : how private philanthropic foundations seek to influence public education policy
Keywords: Education.

Private philanthropic foundations are perennially controversial actors within public policy contexts, and their influence within U.S. education policy has increased over the last several decades, yet their actions in the public sphere have received limited empirical and theoretical attention. This dissertation presents a cross-case comparative analysis of four influential foundations active in the field of K-12 public education. I determine that these foundations have fundamentally different values regarding their roles as policy actors. These contrasting values represent two distinct modes of engagement, which I describe as economic and political approaches. I also find that four distinct organizational norms influence whether foundations predominantly align with an economic or political approach. These norms include the foundations' loci of control, problem orientation, preferred policy actors, and expectations regarding results. I use these empirical findings to explore key questions regarding the influence of foundations as private actors within public education.
Biological fluorescence imaging on the nanoscale [electronic resource] : STED super-resolution microscopy of cells and tissues
Keywords: Chemistry.

A majority of biological microscopy investigations involve the focusing of visible light with conventional lenses. Fluorescence microscopy is one of the most widely used tools in biology but its resolution has historically suffered from the diffraction limit to about 200 nm laterally and 800 nm axially. In the past decade, this resolution problem has been overcome by the rapidly emerging field of super-resolution microscopy. The first demonstrated super-resolution technique, STimulated Emission Depletion (STED) Microscopy, is the topic of this Dissertation. This Dissertation has two primary areas of focus: the design optimization of a STED microscope, covered in Chapters 2-4, and its application to super-resolution imaging in cells and tissues, covered in Chapters 4-6. Chapter 2 describes the STED apparatus and experimental methods used. This chapter covers the guiding principles behind the design of a STED microscope, which forms a basis for understanding the logic underlying the homebuilt STED microscope which was constructed for this research. This STED microscope has a typical resolution of approximately 60 nm (full-width-at-half-maximum) or 25 nm (sigma) and has the sensitivity to image single fluorophores. In Chapter 3, a framework for evaluating and optimizing STED performance in the presence of several key tradeoffs is presented. Chapter 4 describes both developments in STED Microscopy required to utilize far-red-emitting dyes and the challenges associated with performing super-resolution imaging in intact Drosophila tissue. In Chapter 5, the optimization of labeling density revealed the 9-fold symmetry of a centriole protein structure, an important organelle in cell development. In Chapter 6, Huntingtin protein aggregates are resolved beyond the diffraction limit in a cell model of the neurodegenerative Huntington's disease.
Biophysical analysis of bacterial and viral systems [electronic resource] : a shock tube study of bio-aerosols and a correlated AFM/NanoSIMS investigation of vaccinia virus
Keywords: Mechanical Engineering.

The work presented herein is concerned with the development of biophysical methodology designed to address pertinent questions regarding the behavior and structure of select pathogenic agents. Two distinct studies are documented: a shock tube analysis of endospore-laden bio-aerosols and a correlated AFM/NanoSIMS study of the structure of vaccinia virus. An experimental method was formulated to analyze the biological and morphological response of endospores to gas dynamic shock waves. A novel laser diagnostic system was implemented to provide time resolved data concerning the structural decomposition of endospores in shock-heated flows. In addition, an ex situ methodology combining viability analysis, flow cytometry and scanning electron microscopy was employed to both assess the biological response of the endospore to the shock event, as well as to provide complementary data regarding the structural state of the treated endospore. This methodology was implemented to model the shock wave induced response of a variety of Bacillus endospores. The results are subsequently synthesized into a theoretical framework to be employed in modeling the interaction of endospore-laden bio-aerosols with blast waves. An analytical method combining atomic force microscopy (AFM) and nanometer-scale secondary ion mass spectrometry (NanoSIMS) was developed to examine the spatial localization and depth distribution of specific biological elements in viral systems. This methodology was implemented to analyze the distribution of 13C labeled fatty acids as well as 15N labeled thymidine in individual nanometer sized vaccinia viral particles. Based upon the 13C and 15N signals, three-dimensional depth-resolved data regarding the architecture and localization of the virion lipid membrane and the nucleoprotein complex was generated. In addition, this methodology was employed to provide direct correlation of architectural and chemical data for isolated sub-viral structures. The technique and results presented herein represent a novel tool for the structural and chemical study of both intact viral particles as well as specifically targeted sub-viral elements.
"Blessed is he who says and does" [electronic resource] : gender, law, and Jewish communal identity
Keywords: Religious Studies.

This dissertation explores the ways in which contemporary Jewish law defines women's place in the Jewish community. I carry out a close reading of recent responsa on women and public prayer, women and ritual objects, and women in the rabbinate that utilizes Ronald Dworkin's theory of law as integrity, Catherine Bell's understanding of ritual, and Pierre Bourdieu's conception of the habitus. I identify several main themes in the current halakhic attitude toward women. Women occupy an ambiguous space in this rhetoric: they are Jews, but if Jews are also defined as those obligated in all the commandments, then women are in some important sense outsiders to the 'real' Jewish community. The decisors struggle with this issue, and with the legitimacy of women's requests for greater Jewish participation. Some seek to maintain the status quo in the name of fidelity to tradition, while others ultimately grant women a limited set of new rights as exceptional individuals rather than as a group.
Bonding and structures of light element energy systems under extreme conditions [electronic resource]
Keywords: Geological and Environmental Sciences.

This dissertation focuses on investigating the effect of pressure on the structure and bonding of three types of light-element energy systems using a suite of synchrotron x-ray characterization probes including diffraction, spectroscopic and imaging techniques. Ammonia borane (AB), which contains a remarkably high hydrogen content, shows rich structural and dihydrogen bonding variations upon compression. More strikingly, AB is found to be capable of storing a significant amount of extra hydrogen molecules in addition to the hydrogen chemically stored in itself, which makes this novel AB-H2 compound one of the most hydrogen rich materials currently known. LiMn2O4, a promising cathode material for Li-ion batteries, is found to be extremely sensitive to deviatoric stress which triggers a cubic-to-tetragonal phase transition. Such a transition during the battery working environment is detrimental to both the performance and lifetime. However, the nanostructured material can accommodate more stress and strain compared to its bulk counterpart. Glassy carbon, which has very low density and 100% sp2 bonding at ambient conditions, undergoes a transition to amorphous diamond at high pressure. This new carbon allotrope possesses an amorphous structure with 100% sp3 bonds and exceptional hardness. The property of superhardness, if turns out to be isotropic, can be advantageous relative to crystalline diamond for which the hardness is highly anisotropic. The findings could lead to new classes of ultradense and strong materials that can serve as energy-efficient components such as wear resistant parts for all kinds of transportation.
Bones, bones, bones [electronic resource] : using protein-engineered biomaterials to improve bone regeneration and implant osseointegration
Keywords: Bioengineering.

Our bones are complex and beautiful structures that highlight that Nature is a masterful materials scientist. These composite structures of minerals, proteins, and cells are capable of maintaining a remarkable, ever-changing balance based on an individual's biomechanical needs. Growing, running, jumping, sitting, sleeping -- all of our actions and inactions are chronicled and inform the processes of new bone formation and old bone resorption. The hierarchical microstructure, building from calcium phosphate nanocrystals embedded in collagen fibers, underscores the importance of mineral and organic components that synergistically contribute to the toughness of bone needed daily. Unfortunately, due to trauma or disease, at times our bones fail and are unable to heal themselves. It is for these instances that the field of Regenerative Medicine works to develop therapies built on expertise from materials science, engineering, and medical fields. Using protein engineering and bone biology as the starting foundation, my thesis work has focused on the development of two protein-engineered biomaterials for the improvement of regenerative medicine therapies focused on osseointegration of implants and bone regeneration. Engineered protein biomaterials harness the extensive toolkit provided to us by Nature, which includes the machinery to synthesize protein materials and myriad functional pieces to mix and match in our novel designs. With these tools I've helped develop an engineered elastin-like protein to be a photocrosslinkable, cell-adhesive, thin-film coating to improve the osseointegration of implants used to stabilize fractures. The material demonstrates increased speed and extent of cell attachment to coated surfaces, serving as proof of principle for use of this material in stimulating integration of coated implants through improved implant-cell interactions. Focusing my attention on non-healing skeletal defects, I worked with MITCH, our Mixing-Induced, Two-Component Hydrogel, to develop it for stem cell delivery and bone regeneration applications. MITCH employs molecular recognition of a peptide domain binding pair for gentle, on-demand, 3D cell encapsulation at constant physiological conditions. Further using this binding strategy to emulate the intimate interface between organic and mineral phases in native bone by crosslinking mineral nanoparticles into the hydrogel network via specific molecular interactions, I created a material capable of delivering adipose-derived stem cells and stimulating fast bone regeneration in critical-size calvarial defects. Regenerative medicine brings together the renewing power of stem cells and the rational design of biomimetic niches to help the body heal when it is incapable of doing so without assistance. Taken together, this body of work validates the strategy of designing protein-engineered biomaterials by taking cues from Nature to further the development of regenerative medicine therapies, improving their success and widespread adoption.