4 resultados para Hierarchy and topology

em Duke University


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This thesis examines how the depiction of the family during war reinforces or challenges societal values in three nineteenth-century novels. The primary focus lies in three novels by Sir Walter Scott, Leo Tolstoy, and Harriet Beecher Stowe that represent the perspectives of England, Russia, and the United States, respectively, and their evolving nationalism as the roots of the Napoleonic Wars and the American Civil War became visible. By investigating the interaction between economic classes, it can be concluded that the preservation of the family is inherently dependent on social status in some nations, while in others, it is integral to daily life regardless of class. The backdrop of impending war only serves to heighten national differences, overturn the organization of the family hierarchy, and redefine the idea of the modern household.

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Biofouling, the accumulation of biomolecules, cells, organisms and their deposits on submerged and implanted surfaces, is a ubiquitous problem across various human endeavors including maritime operations, medicine, food industries and biotechnology. Since several decades, there have been substantial research efforts towards developing various types of antifouling and fouling release approaches to control bioaccumulation on man-made surfaces. In this work we hypothesized, investigated and developed dynamic change of the surface area and topology of elastomers as a general approach for biofouling management. Further, we combined dynamic surface deformation of elastomers with other existing antifouling and fouling-release approaches to develop multifunctional, pro-active biofouling control strategies.

This research work was focused on developing fundamental, new and environment-friendly approaches for biofouling management with emphasis on marine model systems and applications, but which also provided fundamental insights into the control of infectious biofilms on biomedical devices. We used different methods (mechanical stretching, electrical-actuation and pneumatic-actuation) to generate dynamic deformation of elastomer surfaces. Our initial studies showed that dynamic surface deformation methods are effective in detaching laboratory grown bacterial biofilms and barnacles. Further systematic studies revealed that a threshold critical surface strain is required to debond a biofilm from the surface, and this critical strain is dependent on the biofilm mechanical properties including adhesion energy, thickness and modulus. To test the dynamic surface deformation approach in natural environment, we conducted field studies (at Beaufort, NC) in natural seawater using pneumatic-actuation of silicone elastomer. The field studies also confirmed that a critical substrate strain is needed to detach natural biofilm accumulated in seawater. Additionally, the results from the field studies suggested that substrate modulus also affect the critical strain needed to debond biofilms. To sum up, both the laboratory and the field studies proved that dynamic surface deformation approach can effectively detach various biofilms and barnacles, and therefore offers a non-toxic and environmental friendly approach for biofouling management.

Deformable elastomer systems used in our studies are easy to fabricate and can be used as complementary approach for existing commercial strategies for biofouling control. To this end, we aimed towards developed proactive multifunctional surfaces and proposed two different approaches: (i) modification of elastomers with antifouling polymers to produce multifunctional, and (ii) incorporation of silicone-oil additives into the elastomer to enhance fouling-release performance.

In approach (i), we modified poly(vinylmethylsiloxane) elastomer surfaces with zwitterionic polymers using thiol-ene click chemistry and controlled free radical polymerization. These surfaces exhibited both fouling resistance and triggered fouling-release functionalities. The zwitterionic polymers exhibited fouling resistance over short-term (∼hours) exposure to bacteria and barnacle cyprids. The biofilms that eventually accumulated over prolonged-exposure (∼days) were easily detached by applying mechanical strain to the elastomer substrate. In approach (ii), we incorporated silicone-oil additives in deformable elastomer and studied synergistic effect of silicone-oils and surface strain on barnacle detachment. We hypothesized that incorporation of silicone-oil additive reduces the amount of surface strain needed to detach barnacles. Our experimental results supported the above hypothesis and suggested that surface-action of silicone-oils plays a major role in decreasing the strain needed to detach barnacles. Further, we also examined the effect of change in substrate modulus and showed that stiffer substrates require lower amount of strain to detach barnacles.

In summary, this study shows that (1) dynamic surface deformation can be used as an effective, environmental friendly approach for biofouling control (2) stretchable elastomer surfaces modified with anti-fouling polymers provides a pro-active, dual-mode approach for biofouling control, and (3) incorporation of silicone-oils additives into stretchable elastomers improves the fouling-release performance of dynamic surface deformation technology. Dynamic surface deformation by itself and as a supplementary approach can be utilized biofouling management in biomedical, industrial and marine applications.

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This dissertation attempts to retrieve the integration of prayer and theology in the life of the church. Prayer is a spiritual and bodily theological activity that forms Christian identity and virtuous character. The bodily dimension of Christian prayer plays an essential role in theological understanding and moral formation. However, the embodiment of prayer has been mostly neglected in modern academic theology. This study highlights the significance of the body at prayer in theological studies and spiritual formation.

Chapter 1 presents Karl Barth’s theology of prayer as a model of the integration of prayer, theology, and Christian life (lex orandi, lex credendi, lex agendi). However, Barth’s attempt to overcome the dichotomy between theory and practice in theology did not pay much attention to embodiment of prayer. Through ritual studies and phenomenology (Marcel Mauss, Maurice Merleau-Ponty, and Pierre Bourdieu), chapter 2 shows why the bodily dimension of the practice of prayer should be recovered in theology and ministry; then it explains how Christians in the early and medieval church actually prayed with the body, how their bodily actions were understood in their theological paradigms, and how their actions contributed to the formation of Christian character. Chapter 3 narrows the focus to the formation of the heart in the making of Christian character. The practice of prayer has been emphasized not only as an expression of the inner heart of pray-ers but also as a channel of grace that shapes their affections as enduring dispositions of the heart. Furthermore, historically the bodily practice of prayer gave theological authority to the devout Christians who were marginalized in academic theology or ecclesiastical hierarchy, and Chapter 4 presents the lex orandi of praying women who gained their theological knowledge, wisdom, and authority through their exemplary practices of prayer (Catherine of Siena, Mechthild of Magdeburg, Julian of Norwich, Margery Kempe, and Teresa of Avila). These historical examples reveal how Christian communities appreciated and celebrated the theological voices from the margins, which developed from theological embodiments in prayer.

This dissertation concludes that academic theology needs to heed these diverse theological voices, which are nurtured through everyday practice, as an integral part of theological studies. Therefore, it calls for a new paradigm for understanding the relationship between theory and practice in theological education. The integration between theory and bodily practice is necessary for both academic theology and spiritual formation. A more holistic understanding of Christian practices will not only enhance the training of scholars and clergy but also give the laity their own theological voices that will enrich academic theology.