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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Shape-Shifting Surfaces for Rapid Release and Direct Stamping of Organized Micro-Tissues

Dupont, Samuel James 01 January 2012 (has links)
The primary aim of the research in this study is to develop a robust and simple platform for the in vitro organization of cells on surfaces which facilitate rapid cell release and allows for the direct stamping of highly organized micro-tissues. Current approaches towards this goal have been very successful but are lengthy and subject cells to harsh conditions for extended periods of time raising questions regarding cell health and maintenance of physiological state. To address these concerns a platform was developed to allow for rapid cell release by utilizing a release mechanism different from previous work. Micron-scale structures comprised of the thermally responsive polymer poly(N-isopropylacrylamide) (pNIPAAm) were fabricated into various geometries to serve as a platform for cell culture. Structures were covalently confined to rigid surfaces causing non-uniform distortion of the structure's geometry upon swelling. This resulted in four primary modes of geometric distortion, or swelling-induced instability: differential lateral swelling, localized edge buckling, bulk structural buckling, and surface wrinkling. It was found that slight modifications to a linear elastic model was sufficient to predict these behaviors and provided guidance on design of the cell culture platform. Observations also suggest that a rapidly swelling structure engenders multiple forms of instability which arise as sequential and discrete steps during the swelling process. At each step the length scale of the instability increases in a step-wise fashion until the final equilibrium structure is reached. Culture of NIH 3T3 fibroblasts atop pNIPAAm structures of various geometries resulted in the growth of highly aligned micro-tissue building blocks with three distinct geometries: planar aligned micro-tissue sheets, "ribbon-like" micro-tissues, and "fiber-like" micro-tissues. Release of the micro-tissues was facilitated by the thermally-induced shape-shifting nature of micron-scale pNIPAAm structures. Release occurred rapidly (∼3 min) and required a more mild temperature shift (delta T = 9°C) than other approaches. It was found that the mechanism for cell detachment was mechanical in nature and did not require cellular activity unlike other approaches. Cell detachment was directly correlated to surface strain as a result of thermally-induced shape-shifting and has a level of dependence on cellular contractility. The platform was tested to show its capacity to directly translocate organized micro-tissues to a virgin surface. Cell transfer by direct stamping was achieved with micro-tissues retaining their shape, although stamped micro-tissues lost their organization after several hours of culture. Although the stamping process requires additional optimization, these results provide evidence that this platform has the capacity to culture and directly translocate highly organized micro-tissues. Additionally, this process provides a new, minimally invasive, approach to cell culture such that rapid construction of highly organized multi-layered tissues can be realized.
2

後現代組織對策略之再思考 / Rethinking Strategy in the Postmodern Organization

林俊杰, Lin, Chun-chieh Peter Unknown Date (has links)
摘要 組織乃社會網絡的一員,其必須正視後現代主義者對當今後現代社會的觀察,以及必須面臨的嚴苛挑戰! 本論文旨在探討後現代主義思潮對當代組織的影響與啟示為何?部分當代管理情境(或稱後現代情境), 例如,追求一切可能性、對簡單之渴望、感性的思維、 不確定性、 快速變遷、不連續性、模糊、 無界限、解構、 去中間化、 片斷化、 以族群取代社會階級、 多元化、尊重差異、超現實、以及反宰制性規則等等,對當代組織(或稱後現代組織)現在或未來在策略擬定時的影響與啟示為何? 面對後現代情境及其挑戰 , 後現代組織現在或未來對策略之再思考為何? 後現代組織未來可能適用之新的組織模式為何? 以及後現代組織對策略之再思考的實務作為為何? 本研究主要以文獻探討與次級資料檢索之檔案研究法為主,資料檢索的對象(含個案資料之來源)是以探討較高層次的概念性策略新思維為主。至於屬於研究輔助性質之個案部分,則以屬於營利性質之全球知名多國籍企業、由製造導向轉型為服務導向者、或者可印證本研究所探討之策略新思維者為主。 經由本探索研究後發現,面對後現代主義思維的衝擊,以及後現代管理情境的挑戰,組織應該重新檢視其前提假設、回歸策略本質、勾勒遠大的構想、開創新的價值曲線以避開面對面競爭、重新尋找組織在數位世界的價值定位與經營模式、專注核心、建立社群、培養廣義「顧客」----利害關係人之新的忠誠度、善用所有利害關係人的關係與優勢、 注重組織內外部的整合以及策略要素之間的整合與一致性、擺脫語言牢籠(規則)的束縛而賦予員工彈性、持續尋找任何強調彈性結構、網絡關係、溝通效率、以及民主化機制的組織模式或概念。 最後,對於全球的多國籍企業,本研究建議其必須在全球的產業分工體系之下,勾勒遠大的構想、開創新的價值曲線、發展世界級的核心能力、建立或主導某些內外部社群或電子企業社群、採行time pacing策略以穩健成長、強化跨產業或跨國之組織與策略整合的作為、時時檢視與修改任何宰制性的政策或規則、以及繼續尋找與試行任何可能且可行的組織模式或概念。 / Abstract Organizations that are parts of social network must take into account those issues discovered and criticized by Postmodernist and those severe challenges facing organizations. This dissertation tries to explore those impact and implications aroused by postmodernist for contemporary organizations, those contemporary scenario (postmodern scenario) facing organizations, such as in search of possibilities, in need of simplicity, sensuous thinking, indeterminacy, a rapidly changing environment, discontinuity, ambiguity, boundarylessness, borderless, deconstruction, disintermediation, fragmentation, social class replaced by tribes, diversity, apprizing difference or otherness, hyperreality, and against governing rules, that will affect the strategic planning of organizations at present or in the coming future. In addition, this dissertation also tries to explore that currently or in the coming future how organizations rethink their strategies while facing postmodern scenario and its rigorous challenges, what forms, models or concepts of organization design that organizations can apply, and those managerial practices that organizations have ever executed. The research methodology adopted by this dissertation is primarily literature review and secondary data exploration. The target data including cases are focused on those conceptual strategic thinking. Those cases that are mainly complement to this dissertation are those distinguished multinational corporations (MNC) that have ever been transformed from manufacturing-oriented to service-oriented, or are able to prove partial strategic thinking reviewed in the dissertation. In the face of those thinking impact stirred by postmodernist and challenges resulted from postmodern managerial scenario, this dissertation concludes that organizations should review and rethink their assumption for the world, revisit the essence of strategy, picture and propose the big ideas, create or explore new value curves to avoid cruel face-to-face competition, explore new value positions and business models in the digital world, focus and develop core businesses and competence, build and manage communities, cultivate new types of royalty for those stakeholders partnering with organizations, utilize the relationships with and advantages from stakeholders, emphasize and advocate internal and external organizational integration and consistence and alignment for strategies, free from the cage of language and empower employees, keep exploring those organizational models or concepts that advocate or propose flexibility, networks of people, efficiency of communication, and spirit of democracy. In conclusion, this dissertation suggests that under global industrial value chains, multinational corporations should picture and propose the big ideas, create and explore new value curves, develop best-in-world core competence, form or dominate some internal or external communities or e-business communities, adopt strategy of time pacing for sound and moderate growth, reinforce cross-industry or cross-nation integration for organizations and strategies, keep reviewing and modifying any governing policy or rules, and keep searching and experimenting any latest possible and feasible models or concepts of organization.

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