VictorJuiz/thesis huggingface dataset:
Chronotopes of a Continent: Ben Okri and the Spatial Dynamics of The Famished Road
Keywords:  Department of English
Department of English
African novel
Nigeria
postcolonial literature
chronotope
twentieth century literature
Nigerian history
Negritude
Pan-Africanism
narrative theory
Thesis

This thesis examines the role of Ben Okri's The Famished Road (1991) in the canon of African literature. The unique narrative structure of the novel opens up possibilities of interpretation beyond the potentially limiting scales of analysis often associated with the African novel, including tribe, nation, race, and continent.
Cognitive and neural mechanisms of self-control [electronic resource]
Keywords: Psychology.

Self-control, the ability to regulate impulses, is an important determinant of adaptive behavior and numerous significant life outcomes. This dissertation focuses on a class of decision-making known as intertemporal choices that require exertion of self-control. Intertemporal choices are decisions made between options that are available at different points in time. Delay discounting describes how individuals discount the value of future outcomes as a function of the delay until their receipt. The five experiments presented in this dissertation explore the cognitive and neural mechanisms of intertemporal decision making using a range of variables that predict differences in decision makers' discount rates. These variables include cultural differences (Experiment 1), cognitive framing of choice options (Experiments 2 and 4), and the magnitude of the reward under consideration (Experiment 3). Finally, we use repetitive transcranial magnetic stimulation (rTMS) to disrupt the processes identified in Experiments 2 and 3 to demonstrate their specificity and causality (Experiment 5).
Cohesion and decohesion kinetics of polymer solar cells [electronic resource]
Keywords: Chemistry.

Polymer organic solar cells (OSCs) possess many desirable properties include low temperature solution processibility of photoactive materials and the utilization of flexible substrates for conformal OSC design. However, challenges remain that may inhibit their adoption and implementation. Among these are thermochemical stability, optimized power conversion efficiency, and mechanical reliability. Indeed, for organic solar cells to be used on flexible substrates, mechanical reliability of the individual layers and interfaces is pertinent. In this dissertation, quantitative micromechanical testing techniques were employed to help characterize the mechanical reliability of the layers and interfaces for polymer OSCs. From testing, it was determined that the polymer:fullerene photoactive layer consistently failed cohesively. The cohesive strength of most photoactive layers generally ranged from 0.5 to 2.0 Joules per square meter. However, by using thermal annealing, manipulating the photoactive layer structure, and selecting polymer molecular weight, cohesion values as high as 17 Joules per square meter could be achieved. Indeed, polymer molecular weight affected cohesion the most due to significant plasticity within the photoactive layer. Conversely, improved cohesion did not always result in improved device electronic performance. By optimizing cohesion and efficiency, we are able to come closer to design guidelines for mechanically robust and efficient solar cells. Finally, because OSCs must operate in the environment at temperatures as high as 65 C, we analyzed OSCs under dry, inert environmental conditions and showed how temperature affects the decohesion kinetics within the device. It was demonstrated that the decohesion rate generally accelerated with increasing test temperature. We were able to develop a viscoelastic kinetic model that was able to describe and predict decohesion for these devices. This collective work and modeling will provide greater insight into the practical limitations of OSC design and will aid in future development of OSCs with greater mechanical reliability and in-service lifetimes.
Collective governance in student housing cooperatives
Keywords: cooperatives
co-ops
student housing
collective governance
student groups
Thesis

Student housing cooperatives, or co-ops, are hybrid organizations that combine bureaucratic and communitarian organizational logics. Despite the inherent tension between these dual ways of organizing communal life, student co-ops are remarkably long-lived intentional communities, lasting over decades of constantly shifting membership and leadership. Collective governance, through which student co-ops manage to survive as communitarian projects in bureaucratic organizations, is the central phenomenon of interest in this study. How does the practice of collective governance in student co-ops enable students to negotiate between competing organizational forms and sustain a cooperative way of life? Through participant-observation of sixteen group decision-making meetings in two student co-ops, I depict the practice of collective governance in student co-ops as constituted in two parallel processes: managerial decision-making and collective decision-making. These systems reflect the hybridization of bureaucracy and communitarianism into a dynamic organizational form centered on negotiation and compromise. These findings suggest that while bureaucracy and communitarianism may be incompatible organizational logics, structured efforts toward compromise between them can itself be the basis for robust communal projects.
Combined optical trapping and sm-FRET for nucleic acid folding studies [electronic resource]
Keywords: Physics.

By studying ancient RNA motifs found in all kingdoms of life, we are also looking back in time to a common evolutionary ancestor. Riboswitches and ribozymes are structured RNAs capable of gene regulation and catalysis. Their surprising catalytic/functional diversity and prevalence across species hints at an "RNA World" that predates our current paradigm which depends on DNA for information and protein for catalysis. The TPP riboswitch is an ancient ligand-binding RNA that regulates vitamin B1 (TPP) synthesis in bacteria, archaea, and even higher organisms like plants. Using single molecule optical trapping (OT) and the judicious application of piconewton forces, we have studied the folding pathways of the riboswitch and its response to TPP and other analogues. Ligand binding appears to form in two steps: TPP must first bind weakly before proceeding to a strongly bound state, as measured by the non-equilibrium work required to unfold it. To probe the physical origin of these states, we use a novel dual-beam optical trap combined with simultaneous FRET that can measure two orthogonal signals of the molecule's conformation. We demonstrate the direct observation of both the unfolding of secondary (base-paired) structures (via OT) and long-range tertiary contacts (via FRET) that form during ligand binding. In time, we anticipate this technique will become a sought-after tool that can expose the intricate folding pathways of complex biomolecules.
Commitments not to communicate before and after digital media [electronic resource] : a study of the will and ways to disconnect under changing conditions
Keywords: Communication.

"Information wants to be free, " goes the catchphrase of the information age. Falsely attributing agency to inanimate information by anthropomorphizing it wears away at belief in the role of individual agency in people's own communicative lives. So-called "internet addiction" is one prominent example of this in its displacement of responsibility from the will to the body. Neither engineers nor policymakers nor individuals adrift in the disorienting superabundance of digital communication claim responsibility for it, and few are proposing serious solutions. Communication scholars of various stripes offer theories of why we do and do not choose certain media, do and do not use certain devices, but there has been no systematic treatment of the myriad ways people deliberately structure quiet into their lives. This dissertation is such an analysis. The economic concept of "commitment devices" is applied to communication, generating a new definition of communication avoidance: the willful choice to limit one's own future communication choices. Our present motivations and methods for preempting communication of different kinds are illuminated through three historical chapters devoted to accounts of communication avoidance in the religious, public, and personal spheres. "Information overload" is a new term for an old phenomenon, and although masses of messages are today a quantitatively and qualitatively different problem, examples reaching back thousands of years to the seventh day—that of rest—help to frame contemporary problems within older concerns both technical and normative. A number of taxonomies are developed in order to better understand the diversity of and relationships between different forms of disconnection. In the digital case, this includes an analysis in terms of four different categories of means of disconnection: practices, software, hardware, and location. The book concludes with a discussion of the social and political project of destigmatizing avoidance and envisioning infrastructures that would empower people to better control the silences in their own lives.
Community structure of large networks [electronic resource]
Keywords: Electrical Engineering.

One of the main organizing principles in real-world networks is that of network communities, which are sets of nodes that share common properties, functions, or roles. Communities in networks often overlap as nodes can belong to multiple communities at once. Identifying such overlapping network communities is crucial for an understanding of social, technological, and biological networks. In this thesis, we develop a family of accurate and scalable community detection methods and apply them to large networks. We begin by challenging the conventional view that defines network communities as densely connected clusters of nodes. We show that the conventional view leads to an unrealistic structure of community overlaps. We present a new conceptual model of network communities, which reliably captures the overall structure of a network as well as accurately models community overlaps. Based on our model, we develop accurate algorithms for detecting overlapping communities that scale to networks an order of magnitude larger than what was possible before. Our approach leads to novel insights that unify two fundamental organizing principles of networks: modular communities and the commonly observed core-periphery structure. In particular, our results show that dense network cores stem from the overlaps between many communities. As the final part of the thesis, we present several extensions of our models such that we can detect communities with a bipartite connectivity structure and we combine the node attributes and the network structure for community detection.
Comparative analysis of stomatal development networks in Arabidopsis and Brachypodium [electronic resource]
Keywords: Biology.

Stomata, epidermal valves made up of paired guard cells flanking a central pore, are found in most aerial tissues of plants, where they function to regulate gas exchange. Production of mature stomata involves a series of asymmetric cell divisions (ACDs) and cell fate transitions, and the molecular genetic regulation of this process has been extensively studied in the dicot Arabidopsis thaliana (thale cress). Yet, it remains largely unknown whether the same genetic regulators are used across a range of taxa, and how genes and networks might differ between species to produce (or accommodate) distinct developmental patterns. Indeed, stomatal ontogeny is remarkably diverse among plant species, with particularly intriguing differences between dicots and grasses. Whereas Arabidopsis stomata are sprinkled across the leaf surface seemingly at random, grasses produce stomata oriented along the leaf axis in specific linear cell files. In my thesis work, I have examined the genetic networks controlling stomatal development in grasses, focusing particularly on how these networks resemble or differ from those of Arabidopsis. My studies are conducted using the forage grass Brachypodium distachyon, a recently developed, genetically tractable model species related to wheat and barley. First, I report the basic characterization of Brachypodium stomatal development, as well as the identification of stomatal mutants via a forward genetic screen. Subsequently, I describe mutations in two orthologues of known Arabidopsis stomatal regulators: the bHLH gene BdICE1, which is required for production of mature stomata, and the MAPKKK gene BdYDA1, which enforces correct stomatal patterning. Although both mutants resemble their Arabidopsis counterparts, their phenotypes suggest subtly but intriguingly different roles in Brachypodium. BdICE1, unlike Arabidopsis ICE1, is not functionally redundant with its paralogue BdSCRM2, and the two Brachypodium genes have roles in promoting GMC and guard cell identity, respectively. Further, preliminary data suggest that the ICEs of Brachypodium may differ from those of Arabidopsis in their interactions with SPCH family bHLHs. Similarly, although BdYDA1, like Arabidopsis YDA, enforces stomatal patterning, it also regulates a number of other asymmetrically dividing epidermal cell lineages (e.g., hair and silica cell lineages), suggesting a role as a general regulator of fate asymmetry. Finally, I discuss prospects for using timelapse imaging and computational modeling to gain insight into stomatal lineage polarity, division, and fate specification processes in both dicots and grasses.
The comparative grammaticality of the English comparative [electronic resource]
Keywords: Linguistics.

The goal of this dissertation is to investigate systematic variation in English comparative adjective formation using the insights of lexical prosody and Optimality Theory. I provide a sustained argument in favor of lexically specified, representationally rich prosodic structure. Chapter 1 introduces comparative adjective variation (CAVE) in the context of morphological-periphrastic alternations in language and draws particular attention to comparative grammaticality as a theoretically appropriate solution to the systematic nature of CAVE. Chapter 2 provides an in-depth corpus analysis of spoken and written English from the Corpus of Contemporary American English. Alongside replicating several earlier results, the chapter provides evidence for the variable, systematic nature of suffixation to adjectives of different prosodic and morphological shapes. In Chapter 3, I make two major claims. First, I argue that morphemes can exhibit various degrees of prosodic strength, spelled out as differences in structure, an inherent property of morphemes as they are stored as Roots in an abstract lexicon. Second, I argue that token frequency influences prosodic strength through the direct modulation of prosodic structure; infrequent and phonotactically complex short adjectives are less likely to undergo reduction processes because of their more articulated prosodic structure. In contrast, frequently used adjectives have less articulated prosodic structure, which results in more reduction processes. These two claims set the basis for a representational difference between high- and low-frequency adjectives, which accounts for their divergent susceptibility to phonological reduction and phonetic shortening. Chapter 4 is concerned with spelling out the structure of the grammar of comparative suffixation. It divides the grammar into Stem and Word strata and argues that variable suffixation rates require both stratal and representational (morphological and prosodic) routes of explanation. In sum, variable suffixation results from the representational differences argued for in Chapter 3, as well as the dual-stratum membership of -er at the Stem and Word strata. A variety of adjective types are considered. Chapter 5 addresses comparative grammaticality at the level of syntax and sketches a preliminary analysis of how phrasal prosody may also affect suffixation rates, which has implications for the phonology-syntax interface and the degree to which lexical and syntactic information should be separated in linguistic theory. Chapter 6 concludes the dissertation, comparing present contributions to previous work on CAVE.
Comparing Fiscal Strategies for the U.S. in a New Keynesian Framework
Keywords:  Department of Economics
Stanford Department of Economics
fiscal consolidation
CMS model
stimulus
output growth
structural model
Thesis

In this paper, I use Coenen, McAdam, and Straub’s (2008) (CMS) structural macroeconomic model to compare and contrast three fiscal strategies for the U.S.: (1) short-run stimulus followed by fiscal consolidation, with stimulus financed by future spending reductions, (2) short-run stimulus followed by fiscal consolidation, with stimulus financed by future tax rate increases, and (3) short-run stimulus followed by permanently higher spending in the form of transfers. My analysis follows the framework of analysis done by Cogan et al. (2013) on fiscal consolidation strategies in the same model. I find that the model produces a temporary positive output effect from the short-run stimulus, followed by negative effects on output due to the conclusion and subsequent payment of stimulus. Long-run fiscal consolidation after stimulus is more favorable than permanently higher spending because it decreases the medium- and long-run output cost of stimulus and creates favorable conditions for long-run growth. Stimulus financed by spending reductions is preferable to tax financed stimulus in terms of output growth generated. Lastly, permanently higher spending in terms of transfers is particularly harmful to growth.
Composition and molecular architecture of the sonic hedgehog morphogen [electronic resource]
Keywords: Developmental Biology.

The Hedgehog signaling pathway performs essential and diverse roles in embryonic development and adult tissue homeostasis throughout the animal kingdom. Hedgehog proteins are secreted morphogens that emanate from localized pools of cells, generating a concentration gradient that communicates positional information to the cells within the tissue. A distinctive feature of Hedgehog proteins is covalent modification with a N-terminal palmitate and a C-terminal cholesterol, which strongly tether Hedgehog to cell membranes and modulate its distribution in tissues. Despite this hydrophobic character, Hedgehog proteins mobilize from expressing cells and travel far from their source to act directly upon distant responding cells. Although evidence exists for multiple mechanisms of Hedgehog mobilization, the actual physical form of the Hedgehog morphogen, as it is packaged and deployed in tissues, remains unknown. Studies in zebrafish have revealed a secreted factor, Scube2, that functions non-cell-autonomously to enable Hedgehog signaling. This led to the discovery that the mouse Scube2 protein can drive release of fully-lipidated Sonic Hedgehog from cell membranes in a soluble form that is potent in signaling assays. In this study, we have taken advantage of Scube2 activity to investigate the physical form of the active Shh morphogen. The signaling activity of this Scube2-released ShhNp is associated predominantly with a large, but discrete, protein complex approximately 250-300 kilodaltons in size. Further analysis suggests that this consists largely of a Scube2:Shh complex, although fully-lipidated Shh could also be present in other forms. Exracellular matrix glycans, such as heparan sulfate, contribute to the assembly and release of soluble, high molecular weight form of Shh by Scube2, and a heparin chain of 16 units suffices to potentiate Scube2-mediated release of ShhNp. This defined system has allowed us to produce large quantities of active morphogen for analysis, thus enabling us to begin addressing questions about the composition, stoichiomentry, and molecular architecture of the active morphogen.
Comprehensive modeling of complex silicon microelectromechanical (MEMS) resonators [electronic resource]
Keywords: Mechanical Engineering.

There is intense interest in micro and nanomechanical resonators for a variety of scientific and commercial applications. Microelectromechanical (MEMS) resonators are employed as frequency reference in various applications to generate an oscillatory signal from mechanical resonance. Dissipation of oscillation energy attenuates resonator's output signal. This attenuation is measured by the quality factor of the resonator. Therefore, high quality factor is a key factor for accurate measurement of frequency. Fundamental physical processes related to energy dissipation in MEMS resonators are not fully understood in general. For various resonators, different processes contribute to a different degree to the total energy dissipation. Due to interaction of mechanical vibration and energy dissipating processes, a strong coupling can take place leading to dissipation and a low quality factor. For simple geometries like a thin beam, quality factor can be reasonably predicted when resonating in the fundamental flexure mode but predictions deteriorate drastically as the designs get more complex to fulfill higher frequency and quality factor requirements. Dissipation in these resonators is generally complex and rarely well understood, and can be limited by quantum mechanical mechanisms. This thesis demonstrates exceptional modeling capability for a set of fundamentally different resonators. First, we provide a clear description of the relevant dissipation mechanisms and discuss models for accurate prediction of the quality factor. The essential difference of frequency reference technologies is set by resonator characteristics including frequency, quality factor and temperature sensitivity. We show by comparison to measurements of various devices built in our lab that we are able to predict performance for a wide range of resonators. As this level of agreement between modeling and measurement is generally unprecedented for arbitrarily complex devices, we hope it clarifies the relationship between the dissipation mechanisms and the probability of their appearance in different categories of resonators.
Comprehensive non-invasive prenatal diagnostics for genetic diseases [electronic resource]
Keywords: Bioengineering.

We are entering an era where invasive procedures such as amniocentesis for genetic testing are being replaced with non-invasive, safe, earlier-to-detect, and more cost-effective technologies that take advantage of circulating (cell-free) fetal DNA in maternal blood. Currently, the new non-invasive technologies are clinically indicated mainly for aneuploidies, which is only a fraction of genetic diseases indicated for detection by invasive procedures. This thesis focuses on using digital PCR and high throughput sequencing tools, both of which are exponentially decreasing in cost, to achieve new diagnostic capabilities using cell-free DNA. The first portion of the thesis covers using targeted amplicons to diagnose Mendelian diseases and to obtain the fetal fraction—an important measurement for quality control of many genetic tests. The second portion covers sequencing approaches to detect microdeletions greater than 1 Mbp. This was demonstrated by detecting Digeorge syndrome, a relatively common ~3 Mbp deletion that can result in several life threatening health conditions. The final portion covers the whole genome determination of the fetus using either linked targets for inherited diseases or direct sequencing at high coverage for the exome component. Here, de novo mutations are covered with direct sequencing while many other mutations, such as deletions and trinucleotide repeats, can be covered by linked targets. This new toolbelt of techniques, in combination with comprehensive carrier screening, will help to dramatically widen the impact of non-invasive prenatal diagnostics to nearly all genetic diseases.