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FAS Theses and Dissertations

Mostrando recursos 1 - 20 de 542

  1. Pop-Up Tissue Retraction Mechanism for Endoscopic Surgery

    Becker, Samuel Craig
    Numerous therapeutic transendoscopic procedures exist to treat lesions in the GI tract. However, these procedures are limited both by their difficulty and by the amount of training required to successfully perform them. The surgeon is tasked with simultaneously steering the distal tip of the endoscope, applying and maintaining tension to retract tissue, and manipulating electro-cautery tools with limited dexterity. In this thesis, I propose a device designed to assist with anchoring and tissue retraction during endoscopic surgical procedures. The designed solution decouples the tissue-grasping function from endoscope tip movement, leaving the surgeon free to use the endoscope tip solely for...

  2. Pop-Up Tissue Retraction Mechanism for Endoscopic Surgery

    Becker, Samuel Craig
    Numerous therapeutic transendoscopic procedures exist to treat lesions in the GI tract. However, these procedures are limited both by their difficulty and by the amount of training required to successfully perform them. The surgeon is tasked with simultaneously steering the distal tip of the endoscope, applying and maintaining tension to retract tissue, and manipulating electro-cautery tools with limited dexterity. In this thesis, I propose a device designed to assist with anchoring and tissue retraction during endoscopic surgical procedures. The designed solution decouples the tissue-grasping function from endoscope tip movement, leaving the surgeon free to use the endoscope tip solely for...

  3. An Anatomical and Functional Dissection of the Role Pet1 Raphe Neurons Play in Neonatal Cardiorespiratory Homeostasis

    Dosumu-Johnson, Ryan T.
    Life-sustaining cardiorespiratory homeostasis requires the dynamic response of brainstem neural circuits. Apneas - the cessation of breathing often accompanied by bradycardia - can reflect defects in these circuits, and if frequent or prolonged can be life-threatening. During early postnatal life, mammals exhibit a higher frequency of spontaneous apneas, thus needing to engage this respiratory circuitry frequently, robustly, and reliably. Dysfunction can lead to sudden unexpected death and is hypothesized to be one underlying cause of the Sudden Infant Death Syndrome (SIDS), which is the leading cause of postneonatal infant mortality in the western world. Brainstem abnormalities have been observed in...

  4. The Effect of Intracavity Field Variation on the Emission Properties of Quantum Cascade Lasers

    Mansuripur, Tobias S.
    A common and powerful simplification in laser physics is to ignore the spatial dependence of the intracavity field intensity, and instead replace it with its average value. This approach can elucidate many aspects of laser behavior. In this work, however, we examine several problems, both theoretical and experimental, whose understanding requires that the intracavity intensity variation be properly taken into account. We first address theoretically the question of light reflecting from an amplifying slab, a simple problem to pose but one that reveals counterintuitive solutions of the Fresnel equations. These subtleties provide a deeper understanding of negative refraction in nonmagnetic...

  5. The Poetic Path to Awakening: Reading the Buddhist Literary Text as a Form of Practice in Aśvaghoṣa’s Mahākāvya

    Regan, Julie A.
    This thesis proposes a new approach to reading and understanding a Buddhist literary work as a form of practice relying on aesthetic pleasure to engage readers on a textual path that gradually awakens understanding. Its starting point is the claim of Aśvaghoṣa, the first known author of the genre of classical Sanskrit literature known as mahākāvya, that he has told truth in literary form in order to reach an audience interested only in pleasure and not liberation. My investigation of his second century CE works, Buddhacarita and Saundarananda, through the lens of this statement, together with traditional Indic commentaries on...

  6. Discipline and Publish: Jews, the Logic of the State, and the Beginning of Modern Hebrew and Yiddish Literature in Eastern Europe (1806-1845)

    Dynes, Ofer
    Jews, the Logic of the State, and the Beginning of Modern Hebrew and Yiddish Literature in Eastern Europe (1806-1845) investigates and connects two historical phenomena: The rise of modern Jewish literature in Eastern Europe, and the encounter of Polish Jews with the modern imperial state. I examine the rise of Yiddish and Hebrew literature both within an internal Jewish framework, as well as a response to the transformation of Jewish society in the wake of Poland’s partitions (1773-1795), under imperial rule. This project shows how literature became one of the central venues for negotiating the encounter with the logic and...

  7. Between China and Tibet: A Documentary History of Khotan in the Late Eighth and Early Ninth Century

    Zhang, Zhan
    Since the late 19th century, expeditions in Khotan sponsored by various countries have yielded several collections of Khotanese manuscripts. Among them, the British Collection, the Russian Collection, and the Hedin stand out as they contain most of the secular documents from the Khotan region. In his groundbreaking work in 2006, Yutaka Yoshida regrouped these secular documents into six archives, Archive 0 to Archive 5, according to date and provenance. In my dissertation, I continue Yoshida’s work and focus on Archive 3, a group of texts from the Domoko Oasis, some 120 km east of Khotan, dating from 798-802, the initials...

  8. Towards Perfect Molecular Measurement

    Daugharthy, Evan
    The rapid pace of technological innovation has profoundly transformed life sciences research. Whereas less than 100 years ago researchers were often confined to descriptive and theoretical practices, modern scientists can perceive the inner workings of living systems using advanced measurement technology. This ability to acquire measurements of molecules enables the construction of mechanistic models of biological phenomena. Yet despite the power of existing measurement technologies, many aspects of life remain obscured. The things which we cannot observe or measure inspire continuing technology development efforts, such as the work presented in this dissertation. Here, we present a historical, empirical, and theoretical...

  9. Towards Perfect Molecular Measurement

    Daugharthy, Evan
    The rapid pace of technological innovation has profoundly transformed life sciences research. Whereas less than 100 years ago researchers were often confined to descriptive and theoretical practices, modern scientists can perceive the inner workings of living systems using advanced measurement technology. This ability to acquire measurements of molecules enables the construction of mechanistic models of biological phenomena. Yet despite the power of existing measurement technologies, many aspects of life remain obscured. The things which we cannot observe or measure inspire continuing technology development efforts, such as the work presented in this dissertation. Here, we present a historical, empirical, and theoretical...

  10. The Ways of Zainab: Visitations and Valuations Between Iran and Syria via Turkey

    Yildiz, Emrah
    The Ways of Zainab: Visitations and Valuations between Iran and Syria via Turkey follows the pathways of a ziyarat (visitation) route, also known as Hajj-e Fuqara’ (pilgrimage of the poor) from bus stations in Tabriz, Iran through informal bazaars in Gaziantep, Turkey to shrines in Damascus, Syria. I propose that Sayyida Zainab’s ziyarat can be productively understood as a region- and subject-making route. By accounting for the spatial and historical production of these territories and the subject formations of their inhabitants, this dissertation charts out two broad avenues of inquiry. First, it analyzes how pilgrims, merchants and other border-crossers of...

  11. The Politics of Conscience: Religious Activism and Social Change in Postwar America

    Bohlen, Casey
    This dissertation is a history of the post-World War II United States religious left, from its birth in the early Cold War through its twilight in the mid-1970s. Although the study of religion and politics is flourishing, recent scholarship has overwhelmingly focused on the Christian right and the resurgence of American evangelicalism. Yet Jewish, Catholic, and ecumenical Protestant activists were key players in the mid-century political left, from nuns staging interracial sit-ins in the middle of Chicago’s busiest intersections to rabbis and ministers running the nation’s largest illegal abortion referral network. Focusing on the work of activist clergy and religious...

  12. The Contest for Human Rights: Soviet Soft Power Through Détente, Reform, and Collapse, 1973-1991

    Kerley, Elizabeth Carol
    This dissertation examines Soviet approaches to human rights as a soft power issue across three periods of challenge and innovation: the mobilization of international human rights criticism in the 1970s; the launch by Mikhail Gorbachev of projects to transform the Soviet Union’s domestic life and international standing; and the progressive fragmentation of the USSR along national lines in the period 1988-1991. Through an assessment of late Soviet human rights strategies and their relationship to domestic practice, and drawing on the “spiral model” proposed by Risse, Ropp, and Sikkink (1999), it illustrates the ultimate dependence of human rights norms’ meaning and...

  13. Empirical Essays on Secrecy and Security in the United States

    Gill, Michael Zachary
    This dissertation analyzes longstanding issues in U.S. foreign policy and political economy with novel data and research methods. Chapter 1 asks: to what extent do “surprise” shifts in the international security environment help individual firms in the defense economy? This paper exploits the timing of three major events—the terrorist attacks of 9/11, the announcement of the Iraq troop surge, and the death of Osama Bin Laden—to assess how firms financially respond to shocks in the demand for defense. Utilizing financial market data for a set of “exposed” defense firms, event studies are performed via the estimation of Bayesian structural time...

  14. Survival mechanisms of peripheral sensory axons

    Pease, Sarah Elizabeth
    The ability to receive and process tactile information relies on proper interconnectivity of sensory neuron circuitry. Long peripheral sensory axons are necessary for rapid transmission of sensory information, and are particularly susceptible to degeneration, both during developmental pruning and in response to pathological insults such as injury. While axon degeneration mechanisms have been extensively studied, the opposing mechanisms of axon survival are not well understood. Here we use in vitro and in vivo methods to investigate intrinsic mechanisms governing axonal survival both during development and in response to chemotoxic injury. During development, sensory neurons compete for a limited supply of neurotrophic...

  15. Hope’s Harvest: Wandering and the Poetics of ‘Getting By’ Among the Gandharva of Nepal

    Spray, Stephanie Anne
    Hope’s Harvest: Wandering and the poetics of ‘getting by’ among the Gandharva of Nepal is an ethnography of the occupational caste of musicians in Nepal known as the Gandharva that focuses on their artistry in music and life, in particular those adaptations of their musical tradition in rural and urban contexts that enable them to “get by” in contemporary Nepal. Much of the text focuses on those practices that Gandharva describe under the rubric of “wandering,” such as itinerant music performances and begging, as well as “walking business,” or street peddling in tourist neighborhoods in Nepal; it also attends to...

  16. Subtype-Specific Corticostriatal Projection Neuron Developmental Gene Expression and Corticospinal Expression of the Paroxysmal Nonkinesigenic Dyskinesia Gene

    Xu, Zhaoying
    The mammalian neocortex is responsible for motor control, integration of sensory information, perception, cognitive function, and consciousness. It is complex, yet highly organized, with six layers containing broad classes of excitatory projection neurons (along with interneurons) with diverse subtype and area identities. Corticostriatal projection neurons (CStrPN) are the major cortical efferent neurons connecting the cerebral cortex to the striatum of the basal ganglia, and are critically involved in motor planning, execution, movement control, learning, and cognitive functions. As the predominant type of CStrPN, intratelencephalic CStrPN (CStrPNi) project axons across the hemispheres to innervate contralateral striatum, and degenerate selectively (along with...

  17. The Developmental Origins of Logical Inference: Deduction and Domain-Generality

    Mody, Shilpa
    Is there a fundamental divide between the types of thoughts that human adults can entertain and those available to infants and nonhuman animals? The research in this dissertation explores the developmental origins of abstract, combinatorial, propositional thought. As a case study, we examined infants’ and children’s ability to make a logical inference, the disjunctive syllogism: A or B, not A, therefore B. In Paper 1, we asked when infants begin to recruit negation in reasoning. When shown that a toy was hidden in one of two buckets, and that one of those buckets was empty, 17-month-olds (but not 15-month-olds) used...

  18. A genetic dissection of the interactions between the CbtA toxin of Escherichia coli and the bacterial cytoskeleton

    Heller, Danielle M.
    Prokaryotic chromosomal toxin-antitoxin (TA) systems, consisting of a stable toxin and a labile, cotranscribed antitoxin, have been shown to target a number of essential processes in bacteria. The Escherichia coli genome encodes multiple chromosomal TA systems, including a family of three homologous systems, cbtA/cbeA, ykfI/yafW, and ypjF/yfjZ, that targets the bacterial cytoskeleton. Upon overproduction of the CbtA, YkfI, or YpjF toxins, E. coli cells adopt a lemon-like morphology, reminiscent of that seen upon simultaneous inhibition of cell division and cell elongation pathways. Consistent with this observed morphology, previously published work has shown that the CbtA toxin interacts with both the...

  19. Counsel and Command: An Address-Dependent Account of Authority

    Glaeser, Micha Bernhard
    In this dissertation I develop an account of the concept of authority and the distinction between theoretical and practical authority in terms of their proper forms of interpersonal address. I then exploit the difference in moral status between these forms of address in order to develop an account of the moral significance of the state. In Chapter 1, I discuss Stephen Darwall’s recent critique of Joseph Raz’s “service conception” of authority. I argue that Darwall’s argument suffers from a conflation of two forms of preemption, which I call “encompassing” and “determining” preemption. In Chapter 2, I argue that Darwall’s own,...

  20. Activation of Weak Nucleophiles in Anion-Binding Catalysis

    Park, Yongho
    Anion-binding catalysis has emerged as a powerful principle for the development of highly enantioselective transformations. This strategy relies on the ability of dual hydrogen-bond donors to promote anion abstraction from neutral substrates to generate cationic electrophiles such as iminium ions and oxocarbenium ions. Activation of nucleophiles in anion-binding reactions can further expand the scope of both electrophiles and nucleophiles in this mode of catalysis. The research described in this dissertation explores the use of thiourea catalysts to activate weak nucleophiles in two distinct reactions. In Chapter 1, a diastereoselective glycosylation reaction of glycosyl halides is reported. The transformation is catalyzed by...

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