VictorJuiz/thesis huggingface dataset:
Understanding and manipulating ganglioside biosynthesis [electronic resource]
Keywords: Chemistry

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.
Unemployment Makes You Sick, But High Unemployment Makes Us Healthy
Keywords:  Department of Economics
Stanford Department of Economics
unemployment
health
business cycles
Thesis

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.
Upper bounds and moments of L-functions [electronic resource]
Keywords: Mathematics

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.
Upper ocean physical and ecological dynamics in the Ross Sea, Antarctica [electronic resource]
Keywords: Environmental Earth System Science

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.
Urteil und kairozentrische Welt [electronic resource]
Keywords: Comparative Literature

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.
The use of virtual self models to promote self-efficacy and physical activity performance [electronic resource]
Keywords: Communication.

Five pretests and two experiments were conducted in a fully immersive virtual environment to test the utility of virtual representations of the self (VRSs), i.e., photorealistic virtual humans made to resemble the self, in promoting health behaviors. Using social cognitive theory as a framework, these studies manipulated identification with and vicarious reinforcement of virtual selves and virtual others to encourage exercise behavioral modeling and promote self-efficacy. The pretests indicated that virtual selves were more effective than virtual others in promoting behavioral modeling both at the time of the experiment and 24 hours following. The pretests also indicated that vicarious reinforcement of the VRS led to greater behavioral modeling than reinforcement of a virtual other. Study 1 revealed that virtual representations of the self are more effective than similar or dissimilar representations in promoting exercise behaviors; however, self-efficacy did not vary among groups. Study 2 compared virtual environments to the process of mental practice (i.e., visualization or mental imagery) in promoting exercise performance among low and high self-efficacy participants. Participants across conditions demonstrated greater performance over time. Finally, the dissertation considers future directions for research conducted with virtual representations of the self as both avatars and agents in health contexts.
User Privacy and the Evolution of Third-party Tracking Mechanisms on the World Wide Web
Keywords: Computer Science.
Data protection
Internet searching
Personal information management
Thesis

Third-party tracking refers to tracking done by websites that a user never navigates to explicitly. Many Internet users are vaguely aware that their information may be collected online. However, data suggests there is relatively little knowledge about third-party tracking and its associated privacy risks. The FoxTracks software tool attempts to address this lack of knowledge about third-party online tracking for the benefit of interested users with varying levels of technical knowledge. FoxTracks is a Firefox add-on program that browses the web along with the user and collects information about three types of trackers that may be monitoring the user: HTTP cookies, Local Shared Flash Objects, and DOM Storage entries. The interface to FoxTracks displays the user's information as it has been collected by the trackers; the highly personalized view of third-party tracking is uniquely accessible and informative for end-users. Beyond the development of FoxTracks, the analysis presented in this thesis discusses the history, key players, and motivations of third-party tracking, and how each influenced the design choices made in the software. In particular, the motivations of third-party entities, who are frequently online advertisers, are examined in at length. A computer security rubric is then applied to the behavior and tracking methodologies of third parties in order to show their adversarial qualities in matters of user privacy.
Using synthetic small molecules to probe the structure and function of voltage-gated ion channels [electronic resource]
Keywords: Chemistry

Several methods of examining the structure and function of voltage-gated ion channels are described. The first part of this work involves synthetic small molecules based on the structure of (+)-saxitoxin, a marine neurotoxin. (+)-saxitoxin interacts with the pore of the voltage-gated sodium (NaV ) channel to prevent the passage of ions. A scaffold was designed to be modular, synthetically facile, and contain the functionality that had been implicated in the previous literature. Several members of this family of molecules were produced, and they were assayed for occlusion of sodium current (INa). The second part of this work examines the gating kinetics of voltage-gated potassium (KV) channels. 6-bromo-mercaptotryptamine (BrMT) is a marine neurotoxin that has been shown to alter the gating kinetics of KV channels. Specifically, BrMT affects the early, typically independent steps of KV gating by stabilizing the resting state of some number of the subunits. A family of small molecules was designed and synthesized that would examine the functional effects of different parts of the BrMT molecule. BrMT is a dimer containing three key functional groups: a halogenated indole, a pendant ethyl-amine, and a disulfide linker. Variance at all these positions was examined, and each had different effects. Notably, one of the variants, in which the disulfide linker was substituted for an oxy-bismethyl ether linker, affects KV gating in a different way from BrMT. Alternate models of gating in the presence of this novel analog are discussed.
Valuation of fleeting opportunities [electronic resource]
Keywords: Management Science and Engineering

This dissertation is concerned with the study of problems that involve fleeting opportunities. These are situations with limited capacity and a stream of opportunities on which the decision maker must decide whether to capitalize as they occur. One example is the evaluation of business proposals by Venture Capitalists (VC). I have developed a process to help decision makers in such situations set their policies and answer valuation questions. In the VC context, this process helps evaluate the firm itself or the value of a partner in hiring/firing situations. It can also help the organization's decision makers determine the value of information-gathering activities for different deals at different situations. Our solution is based on three steps. In the first, we assess the frame and decision basis. In the second, we build the valuation funnel. In the third, we apply the results of the valuation funnel to decisions regarding the deal flow and specifically to deals as they arrive. We assume that the risk preference of the decision maker follows a linear or an exponential utility function. We formulate the generic problem in the valuation funnel as a dynamic program wherein the decision maker can either accept a given deal directly, reject it directly, or seek further information on its potential and then decide whether to accept it or not. This approach is illustrated in this dissertation through several examples. Our results show well-behaved characteristics of the optimal policy, deal flow value, and the value of information and other alternatives over time and capacity. To enable these results, we developed the power u-function further and defined a u-value multiplier and certain equivalent multipliers. We also studied different approximations for the power u-curve based on few moments of the underlying distribution. The system we created gives a valuation template for the fleeting opportunities problem. This template allows decision makers to address single opportunities as they occur and guides their approach to the deal flow as a whole. We believe this template will help to extend the application of Decision Analysis and spur more research within the fleeting opportunities problem and, more generally, valuation problems. Our process allows us a valuation template for problems fitting the fleeting opportunities description. This, we hope, will extend the use of Decision Analysis into new fields.
The value of vision in radical technological innovation [electronic resource]
Keywords: Mechanical Engineering

Is a technological vision needed to drive radical or disruptive innovations? Few studies have discussed a possible relationship between the formation of a technological vision and the sustained creation of radical innovation. Even fewer have analyzed a relationship systematically, and finding a suitable data set has proven to be a challenge to scholars. Since 1958, the U.S. Defense Advanced Research Projects Agency (DARPA) has sponsored high risk, high reward research and development that bridge the gap between fundamental discoveries and their military uses. The agency's sole charter has been radical innovation, providing 52 years of sustained practice. This study draws on 59 interviews with DARPA personnel and funding recipients, whose time at the agency spans 45 of those years. Historical interviews and agency documents further validated the data set. Using grounded theory methodology, this study identifies the importance of vision in radical technological innovation, synthesizing prior studies from organizational innovation, technology management, visionary leadership, and industrial research and development. Four major findings are discussed, which address the timing and criteria for innovation visions, specific mechanisms for the formation of visions, the role of socialization on envisioning, and the corresponding governance model. These findings, supported by empirical evidence, add to the current understanding of technological visions and radical innovation research.
Visualizing and modeling joint behavior of categorical variables with a large number of levels [electronic resource]
Keywords: Statistics

Large social, internet, or biological networks frequently have a long tailed degree distribution. Often there are two long tail phenomena. For bipartite networks two different entity types may each have a power law degree distribution, and for directed networks both in-degree and out-degree may have power law distributions. We present a graphical display to visualize the affinities. The display also exposes some interpretable anomalies in network data. Our graphic is based on ordering the entities by size. We show in a Zipf--Poisson model that the largest entities accounting for the majority of data are correctly ordered with probability near one. A saturation model produces head to tail affinities similar to those seen in the data, though a bipartite preferential attachment model gives a better fit to the marginal distributions. Sharp bounds are obtained on the behavior of the margins in both of these cases. Extensions of these models are also considered. As our graphical display has a close connection to copulas, we explore the utility of parametric and nonparametric copula models for our data and we present two new ways of generating smooth valid copula-density estimates. We also develop a new class of discrete-choice models in which the choice set grows with time. By exploiting the structure that arises when the covariate vector takes a special form, we are able to fit a rich model via maximum-likelihood to a data set with over fifty million observations. Interesting issues arise when attempting to simulate from the fitted model, which leads to a proposal for how to sample from discrete distributions with a very large number of possible outcomes and with probabilities that evolve over time.
Visualizing individual neurons and their synaptic distributions in the mouse brain [electronic resource]
Keywords: Biology.

The mammalian nervous system consists of billions of neurons arranged into complicated networks (neuronal circuits) that mediate all aspects of brain function and behavior. A fundamental goal of neuroscience is to describe the structure of neural circuits at the level of single cells and to understand how this structure enables information acquisition, processing, storage, and ultimately the control of behavior. Over the past hundred years, the cumulative efforts of many individuals have led to the development of a wide array of neuronal labeling tools. First, in this thesis, with the ultimate goal of further expanding genetically coded labeling tools to visualize the presynaptic distribution in single neurons within the mouse brain in vivo, I developed a new genetic synaptic labeling method and used it to analyze the spatial patterning of synapses in developing and mature cerebellar granule. Second, taking the advantage of the MADM system that allows gene knockout in single cells and simultaneously labeling the cells for morphology characterization, I also utilized MADM to study the function of the Rai1 gene, heterozygosity of which results in Smith-Magenis Syndrome in human.
Wave equations on asymptotically de Sitter spaces [electronic resource]
Keywords: Mathematics

Asymptotically de Sitter spaces are Lorentzian manifolds modeled on the de Sitter space of general relativity. In this dissertation, we construct the forward fundamental solution for the wave and Klein-Gordon equations on asymptotically de Sitter spaces. We adapt classes of conormal and paired Lagrangian distributions to this setting and show that the lift of the kernel of the forward fundamental solution to a blown-up space is a sum of distributions in these classes. We use the structure of the kernel of the fundamental solution to study its mapping properties. We show that Strichartz estimates with loss hold for the positive mass Klein-Gordon equation on asymptotically de Sitter spaces. When the mass parameter is the conformal value, Strichartz estimates hold without loss. As an application of these estimates, we prove a small-data global existence result for a defocusing Klein-Gordon equation.
Weak independent directors, strong controlling shareholders [electronic resource] : do independent directors constrain tunneling in Taiwan?
Keywords: Law.

One of the most important challenges to modern corporate governance is to constrain controlling shareholder from tunneling corporate resources at a cost to non-controlling shareholders. RPTs have been proved by empirical studies as a major channel for tunneling. OECD has also stressed the challenge of abusive RPTs to Asian corporate governance. This dissertation serves an initial attempt to empirically assess the extent to which independent directors in Taiwan constrain tunneling. Taiwan serves as an appropriate jurisdiction for research in that private benefits agency problem is prevalent among Taiwanese public companies and that independent directors were newly introduced to Taiwan's corporate boards, which traditionally follow dual-board system. Nevertheless, the results are daunting. RPTs among Taiwanese public companies are common but rarely monitored by the board. Interview results further confirm this finding. Overall, independent directors' oversight on RPTs or tunneling is generally weak. In addition, most RPTs that are sent for board review are explicitly required by the law to do so. The law plays a decisive role in constraining RPTs. Self-regulation by firms of self-dealing transactions is rare. The value of independent directors in reconciling conflicts of interest matters has not been recognized by Taiwanese public companies. The existence of statutory supervisor, which is the traditional corporate monitors under dual-board system, further weakens the monitoring function of independent directors. Furthermore, there exists tremendous information asymmetry between independent directors and controlling shareholders, in particular, the shareholder managers. The information needed to uncover abusive RPTs is among the hardest to obtain. To overcome information asymmetry, independent directors in Taiwan generally choose to join a board with which they are familiar. The interview results reveal that independent directors generally maintain close social relationships with the controlling shareholders. Thus, there is concern that bias arising from the social ties could hinder the independence of directors. Finally, this Dissertation evaluates the effectiveness of legal transplantation of independent directors from a single board system to a dual board system. Transplantation is a long process where new legal measures grind against pre-existing local conditions. Taiwan is still in a transition period where one-third of listed companies operate under a dual board system with independent directors on the board. Independent directors were put on an advising board for some monitoring tasks while there exists another institution, the statutory supervisor, still in charge of corporate oversight. In addition, without complementary judicial deference to the decisions of independent boards, the value of independent directors to the firm greatly diminished. All these existing local conditions present challenges to the new legal device and hinder the transplantation process.