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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.
41

Synthetic and analytical studies aimed at molecular recognition applications

Kubarych, Colin John 28 October 2010 (has links)
The creation of small molecule libraries for binding into the NS1A protein of influenza A viruses and the development of an indicator displacement assay for the differentiation of fatty acids are reported herein. Using Mitsunobu chemistry, a variety of structures based on hydroquinone, resorcinol and 2,7-dihydroxynaphthalene cores were synthesized. Both polar and non-polar functional groups were added to diversify the cores to help understand which molecule binds best to the protein. Because of poor protein binding, the focus of the project moved to a new lead compound, epigallocatechin-3-gallate (EGCG). EGCG showed promise in computational studies and efforts towards the synthesis of the epigallocatechin core were undertaken. Using a fluorescent indicator displacement assay (IDA), a sensing system for fatty acids was developed. The system consisted of bovine, rabbit, and human serum albumins as host molecules, while the fluorescent indicators were fluorescein, 2-anthracene carboxylic acid, and 1-anilino-8-naphthalene sulfonic acid. Fatty acids were able to be differentiated from one another based on their carbon chain length and the degree of unsaturation. The IDA was then subjected to a complex mixture of fatty acids, in the form of edible oils. The oils (extra virgin olive, hazelnut, peanut, sunflower and canola) with different fatty acid profiles were able to be differentiated from each other using principal component analysis. / text
42

Higher order Godunov IMPES compositional modelling of oil reservoirs

Morton, Alison January 1996 (has links)
No description available.
43

A Hybrid Method for Predicting Lift and Drag of Semi-planing/Semi-displacement Hull Forms

Taravella, Brandon 06 August 2009 (has links)
With the ever present desire for ships and boats to run faster while carrying a greater load, a need exists to reduce the drag while simultaneously increasing hydrodynamic lift. Therefore, a need for semi-planing/semi-displacement hullforms exists for vessels to carry relatively high loads (between 500 and 3000 tons) with a general length Froude number range between 0.4 and 1.0. A hybrid method for calculating the lift and drag of semi-planing/semi-displacement hull forms is developed. This is done by separating the kinematic boundary condition into odd and even parts. The odd and even parts of the kinematic boundary condition are solved independently along with the free-surface boundary condition and superimposed for a complete "hybrid" solution. The superimposed solution components relate to Michell's (1898) "thin ship" integral for odd flow and Maruo's (1967) "flat ship" integral for even flow. A generalized form of Michell's (1898) integral is provided for high speed slender bodies by implementing a more realistic near field condition (Ogilvie, 1975) and a wake trench (Vorus, 2009). A generalized form of Maruo's (1967) integral has also been developed. Comparisons of the generalized methods have been made with available model test and/or analytical data. With this, the concept of the Semihull (Vorus, 2005) is revisited. Some results are given concerning the validity of the Semihull as compared to a traditional displacement ship. Hull form optimization is also explored and the deadrise angle distribution proves to be a major factor in calm water hydrodynamic performance.
44

Narratives of homelessness and displacement : Life testimonies of Cameroonian asylum seekers in Johannesburg

Pineteh, Ernest Angu 22 October 2008 (has links)
This thesis is based on an analysis of the life testimonies about homelessness and displacement told by the Cameroonian refugee community in Johannesburg. It seeks to understand not only the experiences and the conditions of migrancy within a specific group of involuntarily displaced persons in an African city but also how these experiences are constructed and reconstructed ‘in the telling’. The main thrust of the thesis is a discourse analysis of the oral narratives and stories that Cameroonian asylum seekers and refugees living in the city of Johannesburg tell about themselves, their past, present and future, their journey to exile and their aspirations, memories of home and sense of identity as forced migrants in a global era. The data for this study was gleaned from a series of interviews with twenty Cameroonian forced migrants and the interviews are used in this thesis as my primary texts. The analysis focuses primarily on the narrative construction of migrant experiences, exploring how Cameroonian forced migrants use varied narrative strategies and patterns to articulate broader exilic discourses such as the construction of memory, identity and spaces. Therefore, through the testimonies collected and recorded from my informants, I was able to access individual lives as well as the subjective and collective experiences of Cameroonian forced migrants, and explore how they interpret and construct these experiences. Also, the testimonies provided a platform from which to examine how Cameroonian forced migrants narrativise exilic experiences, construct identities, remember the past and represent diasporic spaces. The study has produced a number of significant outcomes. Firstly, the testimonies tend to represent exile as a place that provides solutions for the predicaments of displaced persons. Secondly, the study also reveals that migrant narratives can be multidimensional and multi-functional if individual experiences and element of time are taken into account. This is evident from the multiple, shifting and somewhat contesting narratives produced by different respondents. Thirdly, because of these narrative features, the testimonies are often affected by the logic of ambivalence, emerging from the constant subversion and undermining of the same narratives using different narrative patterns, metaphors, images and symbols. Finally, the multiplicity, subversion and the shifts of the narratives therefore draw our attention to the fact that testimonies from the same refugee community have the potentials of generating different interpretations of shared experiences of displacement.
45

The Far winter

Unknown Date (has links)
This collection of poems engages narratives of geographical and emotional displacement on a journey toward a place from which to begin writing. The inciting narrative is one of travel - Brazil, to England, and to adulthood. A second narrative emerges as a gradual realization that these first displacements will never be truly resolved and that this lack of resolution is the only occasion from which to write. As the collection continues, the speaker of these poems is less and less comfortable with pronouncement and more and more comfortable with action. The act of doing something - moving, driving, walking, escaping, returning, floating down a river of ice - is what creates the silence needed to proceed. Through the body, deafening directives can be temporarily suspended. / by Elizabeth Rodrigues. / Thesis (M.F.A.)--Florida Atlantic University, 2008. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.
46

Surviving Dispossession: Burmese Migrants in Thailand's Border Economic Zones

Saltsman, Adam January 2015 (has links)
Thesis advisor: Stephen Pfohl / This dissertation explores the intersection of gender, violence, and dispossession among Burmese migrants living in precarious circumstances in Thailand, close to the border with Myanmar. In this space, particularly in the town of Mae Sot and surrounding areas, migrants are targets of multiple overlapping technologies of governance, including the Thai state, multinational garment export processing facilities, plantation-style agricultural firms, international humanitarian NGOs, and transnational social and political networks. Through a multi-modal qualitative approach relying on collaborative action research and key informant interviews, I consider how this complex web of discursive and relational power simultaneously renders migrants invisible subjects of global supply chains and yet hyper-visible targets of humanitarian assistance and intervention. Invisible because actors associated with state or market forces performatively enforce upon migrant bodies the violent notion that they are deportable, reiterating the boundaries of sovereignty at each encounter. And visible because as migrants struggle to make ends meet working long hours for illegally low wages, NGOs spotlight their social problems and offer solutions that promote individual biowelfare but not wider transformative change. Despite what appear to be opposing forces, both forms of power contribute to the production of gendered border subjects that are healthy workers; ethical and self-reliant yet docile. Migrants interpret and negotiate these overlapping systems, exerting agency as they rely on their own social and political networks to establish mechanisms of order that are shaped by but not necessarily subordinate to the disciplinary regimes of factories and farms, the juridical frameworks of the state, or the biopolitical gaze of NGOs. This dissertation finds that within these mechanisms, gender becomes a key discursive metaphor both to make sense of the widespread violence of displacement and to maintain collective order. Migrants' own gendered performances of discipline are themselves a product of border precarity and forge pathways of limited agency through which migrants seek to navigate the everyday conditions of that precarity. Throughout, this dissertation reflexively examines its own collaborative action research approach as well as humanitarian intervention on the border to identify ways that both are complicit in gendered border subjectivation. Gender in this analysis manifests itself as a set of discursive resources that NGO staff and migrants make use of as they seek to effect change--albeit in ways that tend to leave unchallenged the larger structural conditions of violence and neoliberal sovereignty that undergird and require the formation of a docile and disposable border population. Thus, in one sense, this dissertation is about how migrants survive in a violent context of dispossession, but it is also just as much about the generative qualities of violent life, the spaces in which agency challenges precarity, and the ways in which performatively reproduced gendered hierarchies are at the center of both precarity and resistance. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Sociology.
47

Annular flattening in mitral valve prolapse / CUHK electronic theses & dissertations collection

January 2015 (has links)
Mitral valve (MV) prolapse (MVP) is the most common cause of surgical mitral regurgitation (MR) in developed countries. The normal mitral annulus is saddle in shape, connecting the left atrium (LA) and left ventricle (LV) into a functional entity, and is susceptible to distortion by LA and LV remodeling. Annular nonplanarity is important for alleviating mechanical stress on mitral leaflets and chordae tendinae. Recently, loss of annular saddle shape has been demonstrated as a novel mechanism in the pathogenesis of degenerative MR. Hitherto, the prevalence and features of annular flattening have not been well assessed in MVP patients, as well as potential factors related to annular flattening. / Current guidelines recommend MV repair as the preferred treatment for clinically significant MR. Annuloplasty are routinely used to restore the annular structure and function. Recent long-term studies showed that anterior leaflet or bileaflet prolpase was associated with suboptimal outcomes. However, the relation between mitral leaflets and annular geometry in MVP is not completely understood. / The application of two-dimensional (2D) echocardiography (ECHO) has been limited since mitral annulus has a nonplanar configuration. Three-dimensional (3D) ECHO was shown to be superior to 2D in defining the anatomy of MVP. In this thesis, MVP was identified as systolic displacement (≥2 mm) of any segment of mitral leaflets into the LA passing the mitral annular plane, as indicated in a long axis view (parasternal or apical three-chamber). Finally, 117 MVP patients consecutively referred to our echo laboratory for transesophageal echocardiography (TEE) were retrospectively studied. Twenty-nine patients referred for TEE for suboptimal transthoracic images, exclusion of endocarditis, or evaluation of cardiac source of embolic event and found to have no underlying structural cardiac disease or arrhythmia were included as the normal reference. Standard 2D transthoracic ECHO and 2D/3D TEE were performed in all the subjects. Custom software was used for quantification of 3D MV morphology and key geometric parameters, including mitral annulus, leaflets and chordae, were automatically measured. / The main findings were as follows: / 1. Annular saddle shape flattening (annular height to commisural width ratio <15%) was a common abnormality in MVP patients. More than 50% MVP patients had annular flattening. / 2. Atrial fibrillation (AF) and mitral annular disjunction (MAD) were found to be independent factors associated with annular flattening. MAD was associated with more severe myxomatous MV changes with excessive traction on papillary muscle. The potential roles of MAD in the development of myxomatous MV disease may be through excessive mobility of the mitral apparatus or disturbing 3D annular configuration with reduced annular height and loss of the saddle shape. / 3. Annular flattening was associated with advanced myxomatous MV changes and a higher prevalence of complex prolapse (anterior leaflet and/or bileaflet prolapse). Complex prolapse was associated with more severe annular flattening and dilation, leaflets elongation, increased billow volume and impaired mitral-aortic coupling. / In summary, this thesis provided new data of the 3D MV geometry in MVP patients with new insights into the mechanisms of disease progression and strategies to improve surgical outcomes. Using new techniques in 3D TEE, the thesis demonstrated that annular flattening is a common abnormality, associated with AF, MAD, and more advanced, complex lesions, with implication in the complexity and timing of MV repair. The results suggested that annuloplasty with saddle-shaped rings may be important to restore the structure and function of MV and to improve the durability of repair, particularly important for complex lesions. These data also implied that maintenance of sinus rhythm may help to prevent annular flattening and progression of MVP-related MR. Finally, MAD may be an echocardiographic marker of annular flattening and may require specific surgical correction. / 在發達國家,需要外科治療二尖瓣反流(MR)最常見的原因是二尖瓣脫垂(MVP)。正常二尖瓣瓣環是一個非平面的馬鞍型結構,連接左心房和左心室使之成為一個功能性整體,其結構和功能易受到心房和心室重構的影響。馬鞍型瓣環有助於降低瓣葉和腱索的機械性壓力。最新研究表明瓣環馬鞍型結構缺失是MVP患者出現退行性MR的發病機制。但沒有研究評估瓣環扁平在MVP患者中的患病率,相關特征性改變及引起瓣環扁平的因素。 / 目前,指南推薦二尖瓣修复術作為伴有嚴重MR的脫垂病人的首選治療方法。二尖瓣修复術中常規使用瓣環成形術有助於恢復瓣環的結構和功能。臨床研究顯示脱垂累及前葉或雙葉的手术预后不理想。目前尚不清楚瓣葉和瓣環幾何結構之間存在的相互關係。 / 由於瓣環的非平面結構,三維超聲評估二尖瓣脫垂的價值優於二維超聲。在本研究中,二尖瓣脫垂被定義為長軸水平(胸骨旁長軸或者心尖三腔切面)二尖瓣瓣葉的任何部分發生收縮期向左房面移位,并超過瓣環水平2毫米以上。最後,我們回顧性地研究了117名被轉診到我們心臟超聲實驗室進行經食道超聲檢查的MVP病人。本研究同時入組了29名无其他潛在結構性心臟病或心律不齊的正常對照。他們由於欠佳的經胸超聲圖質量,或者為了排除心內膜炎,或者為了評價血栓是否來自心臟接受了经食道超聲檢查。所有研究對象均接受了標準的二維經胸超聲及二維/三維經食道超聲檢查。研究採用專業軟件對受試者二尖瓣的三維形態進行定量分析。該軟件可自動測量二尖瓣的重要幾何學參數,包括瓣環,瓣葉和鍵索。 / 研究的主要發現包括: / 1.瓣環扁平(瓣環高度與連合線長度之比不超過15%)是一種常見的解剖學異常,超過50%MVP的患者罹患該種畸形。 / 2. 房顫和二尖瓣瓣環分離是引起瓣環扁平的獨立影響因素。瓣環分離與較嚴重的黏液樣改變以及過多的乳頭肌牽拉相關,其在黏液樣二尖瓣疾病中的作用可能是通過引起二尖瓣裝置的過度移動,或通過降低瓣環的高度導致馬鞍形結構缺失從而破壞二尖瓣裝置正常三維幾何學結構。 / 3. 瓣環扁平與嚴重的黏液樣改變有關,同時合併高比例的複雜脫垂(前葉和/或雙葉脫垂)。複雜脫垂與嚴重瓣環扁平和擴大,瓣葉冗長及隆起容積增加相關,同時破壞了二尖瓣-主動脈瓣耦合。 / 總之,本文對MVP疾病進展的機制提出了新的見解,并為手術治療提供有效的策略。本文採用三維經食道超聲領域中最新的成像和圖像分析技術并發現在MVP患者中瓣環扁平是一種常見解剖學發現,其發病與房顫,瓣環分離及嚴重和複雜病變有明確的相關性。這些發現有助於病變複雜程度分級和確定手術時間。採用馬鞍形瓣環成形術既可以修復二尖瓣的結構和功能又能提高修复的持久性。其重要性在複雜MVP患者中尤為明顯。盡早復律可預防瓣環馬鞍形結構缺失和防止反流的加重。最後瓣環分離可作為检测瓣環扁平的超聲學指標,可能需要特殊的外科矯正。 / Jin, Chunna. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 152-165). / Abstracts also in Chinese. / Title from PDF title page (viewed on 12, September, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.
48

Novel thermostable DNA polymerases for isothermal DNA amplification

Morant, Nick January 2015 (has links)
DNA polymerases play a fundamental role in the transmission and maintenance of genetic information and have become an important in vitro diagnostic and analytical tool. The Loop-mediated isothermal DNA amplification (LAMP) method has major applications for disease and pathogen detection and utilises the unique strand-displacement activity of a small group of thermostable DNA polymerases. The Large (Klenow-like) Fragment of Geobacillus stearothermophilus DNA polymerase I (B.st LF Pol I) currently serves as the enzyme of choice for the majority of these isothermal reactions, with few alternatives commercially available. An increasing need for point-of-care nucleic acid diagnostics is now shifting detection methods away from traditional laboratory based chemistries, such as the polymerase chain reaction (PCR), in favour of faster, and often simpler, isothermal methods. It was recognised that in order to facilitate these rapid isothermal reactions there was a requirement for alternative thermostable, strand-displacing DNA polymerases and this was the basis of this thesis. This thesis reports the successful identification of polymerases from Family A, chosen for their inherent strand-displacement activity, which is essential for the removal of RNA primers of Okazaki fragments during lagging-strand DNA synthesis in vivo. Twelve thermophilic organisms, with growth temperature ranges between 50oC and 80oC, were identified and the genomic DNA extracted. Where DNA sequences were unavailable, a gene-walking technique revealed the polA sequences, enabling the Large Fragment Pol I to be cloned and the recombinant protein over-expressed in Escherichia coli. A three-stage column chromatography purification permitted the characterisation of ten newly identified Pol I enzymes suitable for use in LAMP. Thermodesulfatator indicus (T.in) Pol I proved to be the most interesting enzyme isolated. Demonstrating strong strand-displacement activity and thermostability to 98oC, T.in Pol I is uniquely suitable to a newly termed heat-denaturing LAMP (HD-LAMP) reaction offering many potential advantages over the existing LAMP protocol. The current understanding of strand-displacement activity of Pol I is poorly understood. This thesis recognised the need to identify the exact regions and motifs responsible for this activity of the enzyme, enabling potential enhancements to be made. Enzyme engineering using site-directed mutagenesis and the formation of chimeras confirmed the importance of specific subdomains in strand-separation activity. With this knowledge, a unique Thermus aquaticus (T.aq) Pol I mutant demonstrated sufficient strand-displacement activity to permit its use in LAMP for the first time. The fusion of Cren7, a double-stranded DNA binding protein, to Pol I for use in LAMP is also reported. Although the fusion construct was found to reduce amplification speed, enhancements were observed in the presence of increased salt concentrations and it is suggested here as a means for future enzyme development.
49

Experimental studies on resistance to fluid displacement in single pores

Kwelle, Stephen Okachukwu January 2017 (has links)
Understanding the resistance to displacement of one fluid by another in multiphase transport in a porous medium is very beneficial in hydrocarbon exploration and production as well as geological storage of carbon dioxide. Pore resistance behaviour of a porous medium controls the fluxes of fluids through the caprocks over the geological times and therefore directly determines the volume and localization of the hydrocarbons trapped (best locations for exploration) and also the overpressured formation (zone of drilling hazard). In the design for enhanced oil recovery and geological storage, it sets a limit on both the injection pressure and storage capacity of the reservoir to avoid an upward migration of the injected fluid into the overlaying formations. Many investigations have been carried out on the resistance to porous media flows for decades, yet the understanding of the individual factors affecting it is not complete, because most studies were carried out on core samples, whereas flow resistance depends on the flow details at the pore scale. For example, two core samples may have same porosity but different pore size. This research focused on advancing the understanding of resistance to multiphase displacement in a porous medium, using the pressure profile of interface flow through single pores, to measure the resistance to two-phase flow and then link the impact of pore geometry, surface tension, fluid properties, and wettability, on the pressure profile to the displacement process, in order to fill the noticed gap of knowledge. Experiments conducted in this research using tapered capillaries revealed that the resistance to two-phase flow is significantly higher than the single phase resistance and the pore throat of a porous medium is not just determined by a group of smallest pore sizes as understood using core samples, but by response of critical effective pore diameter to resistance to two-phase interface flow. The initiation of a pore throat is characterised by a drastic increase in the resistant pressure at the effective pore size. The effective pore diameter is generally less than 500 μm and increases with the pore tip diameter and the capillary gradient, interfacial tension, but decreased by surfactants. Viscosity does not have any significant effect on the effective pore diameter. The study also revealed a relationship between pore contact angle and pore throat; pore contact angle is maximum and remains fairly constant at the pore throat. The overall outcome of this research is a significant contribution to the influence of pore geometry on the resistance to porous media flows.
50

Essays on the economics of unemployment and retirement

Ye, Han 05 December 2018 (has links)
This dissertation consists of three chapters that study issues related to unemployment and retirement decisions of workers.The first chapter examines the impact of additional pension benefits on the retirement timing of low-income female workers in Germany. Using administrative pension insurance records from Germany, it studies the impact of a pension subsidy program on retirement decisions of recipients. The kinked schedule of the policy allows me to identify the causal effect using a regression kink design. The estimation suggests that 100 euros in additional monthly pension benefits induce female recipients to claim pensions earlier by about 10 months. A back-of-the-envelope calculation suggests that the ratio of the behavioral cost to the mechanical cost of this subsidy program is 0.3, which is smaller than that of other anti-poverty programs. The second chapter studies the total labor supply effects of Unemployment Insurance (UI) for older workers --- both at the extensive and the intensive margin. It documents sharp bunchings in UI inflows at age discontinuities created by UI eligibility for workers in their 50s. Using a combination of regression discontinuity designs and bunching techniques, we quantify the magnitude of these responses exploiting a variety of thresholds, kinks, and notches induced by the UI and retirement institutions. We estimate the total effect using a dynamic life-cycle structural model. Results suggest that the impact of UI extension on non-employment durations for older workers is almost twice as large as the impact for younger workers. The third chapter examines the impact of receiving written advance notification of layoff on the labor supply of displaced workers by exploring the California Worker Adjustment and Retraining Notification (WARN) Act. The California WARN Act, implemented in 2003, expands the requirements of the federal WARN Act. It provides protection to workers in smaller firms and at smaller layoff events. Using the Displaced Worker Supplement to the Current Population Surveys from 1996 to 2018 and a differences-in-difference method, I find that the displaced workers affected by the mini WARN Acts are 3\% more likely to claim unemployment insurance. Conditional on claiming UI, they are less likely to exhaust UI.

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