VictorJuiz/thesis huggingface dataset:
Type safety in the Linux kernel [electronic resource]

Type casts are ubiquitous in Linux and other systems software. Casts reinterpret a pointer to a heap object of one type as a pointer to another type, and are the main way by which programmers can violate type safety, the notion that objects are used as a consistent type throughout their lifetime. A program which is not type safe can exhibit corruption and crashes. Moreover, the C language provides no guarantees about type safety, so responsibility for ensuring type safety falls entirely to programmers. This thesis describes an approach to proving that type casts preserve type safety, specifically in the Linux kernel. This approach uses automated static analysis to infer the abstractions underlying each type cast: type casts are performed for a reason, often to implement polymorphism or another advanced programming language feature, and by identifying this reason the cast can be proved safe. We prove this safety for 75.2% of downcasts to structure types in Linux, out of a population of 28767. Analyzing type casts in Linux requires deep reasoning about the heap at a scale well beyond the previous state of the art. This thesis describes the analysis techniques we developed for this problem, which are broadly applicable to doing sound and precise analysis of the heap at a large scale.

Advisor: Aiken Alexander primary advisor. Thesis advisor
Engler Dawson R. advisor. Thesis advisor
Lam Monica S. advisor. Thesis advisor
Ultrafast 2D-IR spectroscopy of chemical and conformational dynamics in ionic solutions [electronic resource]

The solute-solvent interactions dictate many physical and chemical properties of ionic solutions, as well as the equilibrium structure of ionic assemblies in solution, ranging from free ions, ion pairs, ion-pair dimers, ion-pair tetramers to nanoparticles and ionic crystals. These interactions include hydrogen bonding, charge-charge, charge-dipole, dipole-dipole interactions, etc. Because of the very fast timescales involved, we need novel time-resolved spectroscopic techniques to investigate the microscopic dynamics in the solution. Ultrafast two-dimensional infrared (2DIR) spectroscopy is a unique tool to study equilibrium chemical dynamics on the picosecond timescale. In this thesis, I present my graduate studies of chemical and conformational dynamic in ionic solutions using 2DIR, focusing on two main systems: aqueous ionic solutions and organic ionic solutions. In aqueous solutions, we have applied polarization-selective 2DIR to investigate the H-bond exchange mechanism in aqueous NaClO4 solution, using hydroxyl stretches of water as vibrational markers. The results show that a water molecule shifts its H-bond partners between water and perchlorate by means of large, prompt angular rotation. Using a jump-exchange kinetic model, we extract an H-bond exchange dynamics of ~6 ps and an average jump angle of 50 degree, in agreement with the jump angle observed in molecular dynamics simulations. We also investigate ligand exchange dynamics between different anions in the first solvation shell of magnesium cation in aqueous solution at an exchange time of 50 ps, with CN stretch of thiocyanate as a marker. In nonaqueous ionic solutions, we study the dynamics of ionic assemblies, including the ion pairing and dimerization processes in different organic solvents. The dimerization of LiNCS ion-pair to form (LiNCS)2 dimer is measured to happen on 20-50 ps, while ion pairing dynamics is as slow as hundreds of picoseconds. The ion pairing study complicates from multiple exchange process involved, such as self-ligand exchange which is also investigated by concentration dependent measurements.

Keywords: Physics
Advisor: Gaffney Kelly primary advisor. Thesis advisor
Bucksbaum Philip H. advisor. Thesis advisor
Fayer Michael D. advisor. Thesis advisor
Ultrafast optical control of semiconductor donor electron spins [electronic resource]

Robust qubits and reliable techniques to control those qubits are essential for quantum computing applications. In this work, I investigate the use of fast optical pulses to prevent decoherence and manipulate semiconductor electron spins in two material systems. I also demonstrate a novel technique for decoherence measurements that may improve imaging capabilities and yield new information of solid-state materials. In the first system investigated, electrons bound to silicon donors in GaAs, I show partial coherent control of the electron spins using an ultrafast (picosecond) pulse. I find it possible to rotate the spins an angle > pi/3 at a fidelity of 0.9 with the limited rotation angle likely due to the presence of unwanted excitations. I use a sequence of these pulses to perform a small-angle, optical, spin-echo experiment and measure a decoherence time of 7 microseconds, presumably caused by magnetic noise from nuclear spin diffusion. This technique is significant because of its improved time resolution, spatial resolution, and power requirements over existing methods. The second material studied, electrons bound to fluorine donors in ZnSe, has the potential to be an excellent qubit. Its larger binding energy, potential for isotopic purification of the host-lattice nuclear spins, and presence of fluorine nuclear spin 1/2 coupled to the electron spin will likely lead to higher fidelity manipulations and longer spin-memory times than seen for electrons bound to Si:GaAs. In this work, I show preliminary optical measurements that identify emission from single donors and verify the presence of a three-level Lambda-system, laying the foundation for fast optical control and decoherence studies. The work in this thesis helps establish the qubit potential of both materials, and the techniques developed to control and measure these spins are applicable to almost any optically active, solid-state, electron-spin system.

Keywords: Applied Physics
Advisor: Yamamoto Yoshihisa primary advisor. Thesis advisor
Harris S. E. (Stephen Ernest)
Mabuchi Hideo advisor. Thesis advisor
Unconventional magnetic order and excitations in the pseudogap phase of mercury barium copper oxide [electronic resource]

A major open issue about the cuprate high-temperature superconductors is the nature of the pseudogap phenomenon. In this Thesis, I report results of neutron scattering studies on the model hole-doped compound HgBa2CuO4+d (Hg1201). I first report polarized neutron diffraction results, which show evidence in Hg1201 for a novel "hidden" magnetic order in the pseudogap phase that preserves the translational invariance of the crystal lattice, and a lack of evidence for any additional order that would break this invariance. The observations are consistent with either unconventional spin order or magnetic order due to orbital charge currents. I then present a systematic study of the high-energy magnetic excitations in Hg1201 using inelastic neutron scattering. The investigation started with measurements of the magnetic "resonance" mode, and then unexpectedly led to the discovery of novel magnetic excitations that have not been previously identified in the cuprates. These excitations seem to be associated with the hidden magnetic order in the pseudogap phase, and they have highly unusual characteristics that go outside of the conventional wisdom for the cuprates. Finally, I present results for Hg1201 from two other experimental techniques: magnetometry for uniform susceptibility and X-ray photoelectron spectroscopy. The main conclusion of this Thesis is that there exist significant magnetic correlations that are fundamentally different from the well-studied antiferromagnetic correlations. The novel magnetism seems to involve hole carriers that reside not only in the copper-oxygen layers, but also in other orbitals that likely involve the apical oxygens.

Keywords: Physics
Advisor: Greven Martin primary advisor. Thesis advisor
Kapitulnik Aharon primary advisor. Thesis advisor
Shen Zhi-Xun advisor. Thesis advisor
Underpinnings of institutions [electronic resource]

This dissertation investigates the role of historical events on institutions. In particular, it provides empirical evidence that the timing of agricultural adoption during the Neolithic Revolution, when humans adopted agriculture for the first time, has a strong inverse relationship with the level of constraints that political executives face in modern periods, such as the extent to which they can raise local tax levels. It also provides evidence that certain cultural traits known to foster economic and institutional development, including the level of participation in local community, beliefs in tolerance, obedience, control in life, trust and parental responsibility, have strong ties back to the Neolithic Revolution. The findings come from analyzing novel vegetation data and carbon dates showing the initial agricultural adoption from various Neolithic archaeological sites, as well as data on the level of executive power and local tax levels in Europe and East Asia. The analysis also uses the World Value Survey in order to compare current cultural differences across geographic regions. The results suggest that the regions adopting agriculture early also developed autocratic, extractive institutions in modern periods, while those adopting agriculture late witnessed democratic, egalitarian institutions. They also show that the respondents in regions which adopted agriculture late are more willing to participate and volunteer in social organizations, take active roles in local communities, and value tolerance, control in life and trust over obedience and parental responsibility. The dissertation interprets the diffusion of Neolithic farmers as one potential explanation for how the Revolution influenced modern institutions. As farmers spread out to new lands during the Neolithic Revolution, they developed strong hunter-gatherer traits, and established institutions as outcomes of past institutions, new environment and smaller population. The institutions in the origin of agriculture therefore differed substantially from the ones in the later settlements. While in the origin, large communities formed centralized political systems with hierarchical orders, later migrants established egalitarian political systems that were more suitable for smaller population and new environment. Once these institutions were established, their differences remained persistent in the long run. The dissertation concludes with a current example of the dynamics between cultural divergence and institutions in China between 1990 and 2000, in which the empirical analysis looks modern ethnic cleavages as manifestations of cultural divergence, and the level of public goods provision as a defining characteristic of institutional performance.

Advisor: Jha Saumitra primary advisor. Thesis advisor
Wacziarg Romain primary advisor. Thesis advisor
Malhotra Neil Ankur advisor. Thesis advisor
Underpinnings of institutions [electronic resource]

This dissertation investigates the role of historical events on institutions. In particular, it provides empirical evidence that the timing of agricultural adoption during the Neolithic Revolution, when humans adopted agriculture for the first time, has a strong inverse relationship with the level of constraints that political executives face in modern periods, such as the extent to which they can raise local tax levels. It also provides evidence that certain cultural traits known to foster economic and institutional development, including the level of participation in local community, beliefs in tolerance, obedience, control in life, trust and parental responsibility, have strong ties back to the Neolithic Revolution. The findings come from analyzing novel vegetation data and carbon dates showing the initial agricultural adoption from various Neolithic archaeological sites, as well as data on the level of executive power and local tax levels in Europe and East Asia. The analysis also uses the World Value Survey in order to compare current cultural differences across geographic regions. The results suggest that the regions adopting agriculture early also developed autocratic, extractive institutions in modern periods, while those adopting agriculture late witnessed democratic, egalitarian institutions. They also show that the respondents in regions which adopted agriculture late are more willing to participate and volunteer in social organizations, take active roles in local communities, and value tolerance, control in life and trust over obedience and parental responsibility. The dissertation interprets the diffusion of Neolithic farmers as one potential explanation for how the Revolution influenced modern institutions. As farmers spread out to new lands during the Neolithic Revolution, they developed strong hunter-gatherer traits, and established institutions as outcomes of past institutions, new environment and smaller population. The institutions in the origin of agriculture therefore differed substantially from the ones in the later settlements. While in the origin, large communities formed centralized political systems with hierarchical orders, later migrants established egalitarian political systems that were more suitable for smaller population and new environment. Once these institutions were established, their differences remained persistent in the long run. The dissertation concludes with a current example of the dynamics between cultural divergence and institutions in China between 1990 and 2000, in which the empirical analysis looks modern ethnic cleavages as manifestations of cultural divergence, and the level of public goods provision as a defining characteristic of institutional performance.

Keywords: Business.
Advisor: Jha Saumitra primary advisor. Thesis advisor
Wacziarg Romain primary advisor. Thesis advisor
Malhotra Neil Ankur advisor. Thesis advisor
Understanding and manipulating ganglioside biosynthesis [electronic resource]

The mammalian cell surface is comprised of a heterogenous mixture of proteins and lipids decorated by carbohydrates. These molecules are known as glycoconjugates. Among the many types of glycolipids imbedded within the plasma membrane is a class of negatively charged species known as gangliosides. Gangliosides, which are characterized by the presence of sialic acid residues, are responsible for regulating the activity of many cell surface proteins and serve as recognition targets for cell-cell communication and pathogen invasion. To investigate the biological roles of gangliosides in mammalian cells, I have employed metabolic oligosaccharide engineering techniques to introduce small structural changes into sialic acid residues. Using these methods, I have successfully demonstrated the biosynthesis of photocrosslinking gangliosides in mammalian cells. These photocrosslinking gangliosides can be used to capture and isolate transient ganglioside-mediated interactions in their native environment. I have also used metabolic engineering techniques to probe the substrate selectivity of ganglioside sialyltransferases in mammalian cells. My results illustrate significant differences in the ability of different cell lines to metabolize sialic acid analogs; these differences may be due species-specific variations in sialyltransferase specificity.

Keywords: Chemistry
Advisor: Du Bois Justin primary advisor. Thesis advisor
Kohler Jennifer
Khosla Chaitan
Unemployment Makes You Sick, But High Unemployment Makes Us Healthy

Previous studies have shown that unemployment leads to poor health, but other studies have also shown that population health improves when the unemployment rate is higher. This paper resolves these seemingly contradictory results by analyzing the effects of both unemployment and the unemployment rate on health using individual-level panel data. I find that unemployment worsens health, controlling for reverse causality by considering individuals who lost their jobs due to firm closure, and that an increase in the unemployment rate improves health, controlling for changes in employment status. Furthermore, the effect of the unemployment rate on health is limited only to individuals who remain employed during business fluctuations. The unemployment literature and the unemployment rate literature are therefore capturing effects on different individuals.

Keywords:  Department of Economics
Stanford Department of Economics
unemployment
health
business cycles
Thesis
Advisor: Bhattacharya Jayanta
Unsupervised feature learning via sparse hierarchical representations [electronic resource]

Machine learning has proved a powerful tool for artificial intelligence and data mining problems. However, its success has usually relied on having a good feature representation of the data, and having a poor representation can severely limit the performance of learning algorithms. These feature representations are often hand-designed, require significant amounts of domain knowledge and human labor, and do not generalize well to new domains. To address these issues, I will present machine learning algorithms that can automatically learn good feature representations from unlabeled data in various domains, such as images, audio, text, and robotic sensors. Specifically, I will first describe how efficient sparse coding algorithms --- which represent each input example using a small number of basis vectors --- can be used to learn good low-level representations from unlabeled data. I also show that this gives feature representations that yield improved performance in many machine learning tasks. In addition, building on the deep learning framework, I will present two new algorithms, sparse deep belief networks and convolutional deep belief networks, for building more complex, hierarchical representations, in which more complex features are automatically learned as a composition of simpler ones. When applied to images, this method automatically learns features that correspond to objects and decompositions of objects into object-parts. These features often lead to performance competitive with or better than highly hand-engineered computer vision algorithms in object recognition and segmentation tasks. Further, the same algorithm can be used to learn feature representations from audio data. In particular, the learned features yield improved performance over state-of-the-art methods in several speech recognition tasks.

Advisor: Ng Andrew Hock-soon
Koller Daphne advisor. Thesis advisor
Shenoy Krishna V. (Krishna Vaughn) advisor. Thesis advisor
Upper bounds and moments of L-functions [electronic resource]

L-functions are some of the most studied objects in number theory. Although many crucial properties of L-functions remain mysterious, central conjectures such as the generalized Riemann hypothesis (GRH). This thesis concerns properties of L-functions. In particular, we focus on studying upper bounds and moments of $L$-functions. Assuming GRH, we give effective explicit upper bounds for L-functions on the critical line and apply these bounds to determine what numbers are represented by a given ternary quadratic form. Moreover the best known version of the Lindelof hypothesis from the Riemann hypothesis (RH) is also derived. Another important way of understanding LH is through moments of L-functions. Information about moments sheds light on the distribution of values of \zeta(1/2 + it). We try to understand the joint distribution of quantities like \zeta(1/2 + it) and \zeta(1/2 + it + i). To study these we consider "shifted moments" of the zeta function and obtain good upper and lower estimates for such moments.

Keywords: Mathematics
Advisor: Soundararajan Kannan
Bump Daniel
Venkatesh Akshay
Upper ocean physical and ecological dynamics in the Ross Sea, Antarctica [electronic resource]

This dissertation examines several aspects of the unique physical-biological system that controls biogeochemical cycling in the Ross Sea, the largest continental shelf sea along the Antarctic margin and the most biologically productive region in the Southern Ocean. The core component of the research involves interpretation of data from two oceanographic cruises to the region, one during Summer of 2005--2006 and another in Spring of 2006--2007. Four key research questions are addressed. (1) What physical mechanisms force spatial and temporal variability in mixing depths? (2) How does the dynamic physical environment characteristic of Antarctic continental shelf seas structure distributions of biomass and chemical tracers of production? (3) What key physical and physiological mechanisms control the 13C/12C ratio of organic and inorganic carbon in waters on the Ross Sea continental shelf? and (4) How do physiological variables interact with environmental variability to control phytoplankton taxonomic zonation? Chapter 1 presents an introduction to ocean carbon biogeochemistry and the oceanography of the Southern Ocean and the Ross Sea. Chapter 2 examines the mechanisms effecting early season stratification in the Ross Sea. Lateral advection in the region of upper ocean fronts is shown to be an important mechanism setting early season stratification. Chapter 3 examines several tracer-based methods for estimating upper ocean net community production in the Ross Sea, with explicit recognition of the complexities associated with control volume assumptions and high rates of temporal change. Chapter 4 considers the environmental controls on the distribution of 13C/12C ratios in the Ross Sea. It is shown quantitatively that the two dominant phytoplankton taxa in the Ross Sea have different intrinsic fractionation factors, likely as a result of differing carbon-acquisition physiologies. Air-sea exchange is shown to occur with very noisy fractionation. Finally, Chapter 5 examines the interaction of algal physiology with environmental variability, addressing the key physiological-environmental controls on the taxonomic distribution of phytoplankton in the Ross Sea. While it is difficult to draw concrete conclusions, the most compelling line of evidence suggests that differing photoprotective capacities is the most important physiological characteristic structuring taxonomic distributions. An appendix presents a design for an infrared absorbance-based instrument for the determination of total dissolved inorganic carbon in seawater.

Keywords: Environmental Earth System Science
Advisor: Dunbar Robert B.
Arrigo Kevin R. advisor. Thesis advisor
Caldeira K. (Ken)
Thomas Leif N. advisor. Thesis advisor
Urteil und kairozentrische Welt [electronic resource]

An inquiry into the structure of human judgment in Modernity since Kant. In drawing on authors such as Fichte and Hölderlin, Nietzsche and Frege, Kafka and Wittgenstein, Heidegger, Schmitt, Davidson, Rorty and Deleuze, the study attempts to recuperate the notion of judgment from its inherited aporia between metaphysical and antimetaphysical models. The aim is to draft a model of judgment for our present that accounts for the whole spectrum of situations in which judgment shows its relevance -- whether we are determining a metaphor in a poem, a course of action, a specific interpretive view on history, or a sentence in court.

Keywords: Comparative Literature
Advisor: Berman Russell A.
Gumbrecht Hans Ulrich primary advisor. Thesis advisor
Bohrer Karl Heinz
Nightingale Andrea Wilson advisor. Thesis advisor