187Re-187Os analysis of magnetite and other oxide minerals from various well dated geological settings (kimberlites, lamprophyres, Manicouagan impact melt rock, Great Bear magmatic zone iron ore deposits and Laramie Anorthosite complex) worldwide have been used to investigate the potential for precise geochronology. 187Re-187Os isotopes in groundmass oxide minerals from kimberlites and lamprophyres are not suitable for emplacement geochronology due to low Re contents and large quantities of un-radiogenic Os. TRD and TMA ages can be calculated however, and correlate well with previously published depletion ages and large magmatic events in the overlying crust, indicating the effectiveness of this technique. Geochronology using magnetite from the remaining settings is im-precise due to very low Re and Os contents but the ages produced are in the correct area. Young ages produced from the Laramie anorthosite complex indicate that magnetite may have a low closure temperature to Os diffusion (~200-300C).

Allograft tissue is used to reconstruct cardiac birth defects but induces an immune response resulting in allo-sensitization. Decellularization reduces the immune response, however, acellular vascular tissue is thrombogenic. In-vitro endothelialization may attenuate thrombogenicity. Here we offer our work, which determines a novel method of endothelial cell attachment using Arginine-Glycine-Aspartic Acid (RGD) peptides. We show that an RGD-FITC peptide can be bound to a decellularized ovine cardiac scaffold. RGD modification increases HUVEC cell adhesion to the surface at 3 days of static incubation in-vitro compared to decellularized tissue alone. Repetition using a decellularized human scaffold shows similar results. Cleavage of the potentially immunogenic FITC label retains our RGD peptide. In summary, we determine that decellularized allografts show enhanced HUVEC cell adhesion when modified with an RGD peptide under static conditions. This may increase cell retention in-vivo leading to a decellularized cardiac allograft repopulated with functional autologous cells from the recipient. / Experimental Surgery

Thesis (Ph.D.)--Xianggang Zhong wen da xue, 2000. / Zhi dao jiao shou: Mo Banghao. 880-03 Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1945. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 282-300).

Thesis--Catholic University of America. / Vita. Bibliography: p. 131-134.

Nature and scope of work: This work presents details of the method and results of an investigation of the role and influence of international reservations systems within the UK hotel industry. The research comprised three questionnaire surveys of the use of computer reservations systems and distribution services by UK hotels. These are analysed and to produce an indication of general use of systems and the contribution which these currently make to hotel groups and consortia. The work also included a study of developments in access methods and changes in buyer behaviour as observed by representatives of computer reservation and distribution system, travel agency, hotel representation and intermediary companies. The impact of information technology developments on the travel agency industry, distribution systems operators and intermediaries is considered. The work then indicates the potential implications of these developments for the strategic planning and operational management of hotels in light of prevailing attitudes to technology, preferred sales methods and buyer behaviour. A computer based information and selection facility is developed. This provides a means of identifying the functions required of a distribution system in order to achieve specific business aims. It identifies the channels which meet the requirements while also providing details of the implications associated with use of each. Contribution to knowledge: This research provides the first published account of the current and potential influence of information technology on the way in which the UK hotel sector deals with its market and on the structure of the industry itself. The work results from a comprehensive study of the role of a significant emerging technology within an important sector of the tourism, travel and leisure industry. It is seen as being complete in its own right but also forms a starting point for longitudinal research since no previous work of this nature or scale has been undertaken in the area of interest. The guide developed as part of this work also lends itself to extensive future development as both the technology with which it is concerned and the technology upon which it is based continue to mature. The results of primary research indicate that there is scope for potential change in hotel sector sales and marketing practices as new methods of conducting business are adopted by hospitality industry service providers, agencies and the buying public. The work also suggests that global distribution systems are not the most suitable channel for all hotels but that alternatives must be considered in the context of the particular requirements of each hotel business. The use of formal research methods provides those involved in this sector with an objective assessment of the implications of widespread adoption of computer based reservation and distribution systems for individual businesses and for the industry as a whole. This addresses a requirement which was identified by the author and contributors in the course of the research. The subject area is complicated by the number of available channels through which businesses may distribute and receive information. This complexity is acknowledged throughout the work generates a distribution channel evaluation guide based on the research findings. The purpose of this device is to direct readers through the process of selecting the most appropriate channel to meet their specific business aims. The guide is based on results from the various stages of primary research which indicated the aspects of distribution system use about which hoteliers were unclear and also provided material about possible strategic uses and the operational implications experienced by users. This information was used to develop a staged method of identifying the type of system which would meet specific requirements and to indicate the implications associated with the use of a particular type of distribution system. This decision process is described and is then presented in the form of a hypertext document. The current version provides an elementary guide which can be used to assist qualitative evaluation in a complex subject area and indicates how this technology can be applied in its most basic form. Planned future work aims to develop the scope and function of the static reference document to produce a means of access to product provider information and to create a forum through which users can communicate with each other through e-mail. System suppliers can provide links to their own product information pages which can be accessed by users seeking information and advice. These developments will result in a guide which is interactive and can be kept up to date by system suppliers. This extension of the guide's role should enable it to provide material to be used in the decision support process by users wishing to conduct quantitative evaluation or comparison of distribution systems. This stage of development would require the use of a facility such as the World Wide Web (WWVV) to enable users and suppliers to communicate with each other. The WWW offers ready support for hypertext, the use of which is considered to be important for this application because of its ease of use for inexperienced computer users, the wide availability of the WWW and the suitability of an on-line system as means of publishing material which is subject to continual change. However, it is considered likely that a static version of the guide could be made available for users who do wish to avoid the cost and complication of obtaining access to the WWW. Although the use of hypertext is becoming more common, it is believed that this is the first use of this technology as a means of publishing research in this field.

Age-related macular degeneration (AMD) is the largest cause of blindness for those over 65 in the developed world. There is currently no treatment for the retinal cellular loss associated with the disease. One potential therapy is to implant retinal stem cells into the eye using a biodegradable polymer scaffold. Blends of the biodegradable polymers, poly(L-lactic acid) (PLLA) and poly(D,L-lactic-co-glycolic acid) (PLGA) have been formulated into microspheres. The influence of changing processing parameters on the size and morphology of the microspheres has been studied. A human retinal pigment epithelial (APRE-19) cell line was shown to adhere, survive and proliferate on the surface of the microspheres in vitro. Assays have demonstrated that the nature of the blend influenced cell behaviour. Transplantation of retinal pigment epithelial (RPE) cells on a supportive matrix has also been investigated as a therapy for AMD. In view of AMD related pathology of the native RPE support, Bruch’s membrane (BM), transplanted RPE cells require a scaffold to reside on. Copolymers based on methyl methacrylate (MMA) and poly(ethylene glycol) methacrylate (PEGM) have been synthesised and chemically modified at the PEG terminus. These polymers were subsequently manufactured into a fibrous scaffold using an electrospinning technique and investigated as an artificial BM. RPE cells were shown to attach and proliferate successfully on the surface of the fibrous scaffold in vitro. Cell adhesion was significantly enhanced on scaffolds with the PEG chain terminus modification. Significantly less apoptotic cell death was also observed on these surfaces. The diffusion properties of these artificial membranes have also been investigated. In addition, the novel gelation of the produced copolymers under certain conditions has been studied

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the developed world, but the mechanisms leading to AMD are poorly understood. Circulating retinal autoantibodies and antibody deposits in the retina are associated with AMD but despite this relationship, immune complex (IC)-mediated responses and underlying mechanisms of inflammation in the retina have not been characterised. IgG antibodies can activate immune effector function through formation of IC and their interaction with Fcγ receptors (FcγR) expressed by immune cells. This study aims to test the hypothesis that IC formed in the retina induce an inflammatory response following interaction with activating FcγRs expressed on microglia and/or macrophages, which may contribute to the pathogenesis of AMD. To study the biological effect of IC formation in the retina a model of IC injury was developed and fully characterised. The involvement of mouse FcγRs (mFcγRs) was first studied using Fc gamma chain deficient (γ-/-) mice, lacking cellular expression of activating mFcγRs, and further characterised using FcγRI-/-, FcγRIII-/- and FcγRIV-/- mice. The presence of IC and human FcγR (hFcγR) expression was investigated in human donor eyes from early and wet AMD patients and healthy controls. Finally the effect of inflammatory mediators on human retinal pigmented epithelium (RPE) function was investigated by direct stimulation with cytokines or indirect stimulation using conditioned medium of polarised human macrophages. IC deposition in the mouse retina led to an inflammatory response that depended on the presence of activating mFcγRs, particularly mFcγRI and mFcγRIII, but not on mFcγRIV. Immune complex deposition and increased numbers of immune cells expressing hFcγRIIa and hFcγRIIb were found in the choroid of early AMD donors and microglia in the retina of wet AMD donor eyes. Finally, macrophage activation differentially impacted on RPE cell function, with regards to barrier function and VEGF secretion. The results in this thesis support the hypothesis that immune complex-mediated inflammation could play a role in the pathogenesis of AMD.

The degradation of eyesight is a frightening experience for individuals and unfortunately gradual loss of vision with old age is commonplace. One of the most common forms of eye disease which effects vision is Age-Related Macular Degeneration (AMD). AMD is the leading cause of blindness in the developed world and there is currently no cure for the disease. One treatment option available for the neovascular form of AMD is the injection of Bevacizumab [an anti-vascular endothelial growth factor (VEGF) drug] into the eye on a monthly basis. Investigation into the biodegradable polymers poly(L-lactic acid) (PLLA) and poly(D,L-lactic-co-glycolic acid) (PLGA) as a possible drug delivery system with highly uniform and reproducible microspheres was developed. Under optimised parameters Bevacizumab-encapsulated PLLA:PLGA microspheres were successfully prepared with a steady release of Bevacizumab being obtained. Additionally, fibrous scaffolds of methyl methacrylate (MMA) and poly(ethylene glycol) methacrylate (PEGM) were prepared by an electrospinning process. These MMA:PEGM co-polymers were investigated as a possible Bruchs membrane replacement and as the support for retinal pigment epithelium (RPE) transplantation. The MMA:PEGM co-polymers were functionalised with N-succinimidyl which resulted in the fibres forming a gel in vitro. Gel formation was examined further and successful RPE cell attachment and growth onto these gels was observed. Further work on surface active agents was undertaken to improve the cell adhesion, proliferation and growth of RPE cells onto these methacrylate based frameworks. An arginine-glycine-aspartic acid (RGD) peptidomimetic was prepared and reacted onto the surface of the MMA:PEGM co-polymers, however, the peptidomimetic-attached MMA:PEGM fibres offered little improvement in cell growth in comparison with N-succinimidyl–activated MMA:PEGM co-polymer fibres. Additional attachment of the natural proteins laminin, collagen and fibronectin onto the microspheres was achieved. Attachment of these proteins prolonged the release of the dye from the microspheres and showed no cytotoxic effects when examined in-vitro.

Made available in DSpace on 2014-06-12T23:16:24Z (GMT). No. of bitstreams: 2 arquivo9361_1.pdf: 365923 bytes, checksum: dfc40eb69f2003b5cf836e93b55135a7 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2003 / Este estudo tem como objeto as representações sociais em torno da profissão docente e concomitantemente sobre as representações sociais de gênero, no que se refere à identidade profissional desse grupo social. Dois conceitos nortearam este estudo. O primeiro, é o de Representações Sociais entendido como teorias do senso comum que são engendradas pelos indivíduos na sua interação social, influenciando, desse modo, concepções de mundo e práticas sociais, no nosso caso, práticas profissionais. O segundo é Masculinidade, compreendido como uma construção sócio-cultural e relacional com outras masculinidades e feminilidades sobre o corpo masculino. Sob estes dois marcos teóricos foram analisadas as associações e entrevistas realizadas com 10 professores que atuam no Ensino Fundamental da rede municipal da cidade do Recife. A análise das verbalizações permitiu confirmar a docência elementar como espaço associado às mulheres por lidarem com crianças, por serem mais sensíveis, enfim, por ancorarem a docência ao quadro de conhecimento já instituído sobre o gênero feminino. A docência constitui, assim, um campo profissional estigmatizado aos homens. Isto leva os professores a utilizarem como estratégia de atualização do modelo hegemônico de masculinidade representações sociais que se ancoram na figura paterna: as crianças necessitam de um exemplo de homem , sendo os professores o segundo pai, o tio