No description available.

No description available.

No description available.

From a review of the many and varied attempts to date to design a successful cardiac prosthesis, it was shown that 1) every attempt to design a ventricular actuating mechanism (the crucial element in a cardiac prosthesis) has failed to satisfy one or more of the design requirements and has thus resulted in a maximum survival time for an animal on a cardiac prosthesis of 247 hours and, 2) by combining the operating principles of two previously developed actuating mechanisms (spring-driven and rotating shaft-driven), a successful design could be the possible result. A description of the design and construction of a prototype of such a hybrid configuration was next presented. The mechanism presented in the study was then briefly evaluated with respect to its ability to 1) self-regulate its pump output and, 2) produce a physiological aortic pressure/time waveform. Results of the study demonstrated that the pump was capable of producing a quasi-physiological pressure/time waveform. Self regulatory ability was proven to be ineffective. / Master of Science

As is well known, users can make significant contributions to innovations, including innovating themselves. However, much work on user innovation has focussed on developed countries. The question remains whether and how users innovate in a developing country setting. Bodies of literature that explicitly consider innovations in such settings emphasise the influence of limitations. This thesis therefore investigates how limitations shape the creation and sharing of innovations by users. This issue is analysed for medical technologies, because these can have different user groups, including patients, who have been little focussed on, even in developed countries. In this setting, a focus on innovation as defined relatively inclusively is most suitable, and therefore the term 'changes' is often used rather than 'innovations' to express this inclusiveness. By comparing the changes made to the same kind of technology by different groups of users in different settings with different limitations, the influence of these limitations can be analysed. Therefore, data were collected on changes made by patients as well as orthopaedic technicians to lower limb prostheses in two orthopaedic centres in Malawi. First, observations were conducted of the production process for prostheses, followed by semi-structured interviews with orthopaedic technicians and patients, and with additional experts to understand the broader context. It was found that patients and orthopaedic technicians did make many changes. Three kinds of limitations were identified, that influence these changes by users. Like users in developed countries, patients and orthopaedic technicians make these changes to fulfil their needs because available products and services are not satisfactory. Limitations both restrict what products and services are available to users, and also influence the characteristics of the creation and sharing of changes by users. Many users reported on efforts to share their changes with others despite the limitations, often due to a sense of professional collegiality and solidarity. In summary, limitations help to explain how changes by users occur in developing countries, but also how any accumulation of such changes users make is restricted. Improving this situation could help less developed countries in making better use of any user innovations that do occur, and thus contribute to their development more generally.

No description available.

Thesis (M.Phil.) - University of Queensland, 2004. / Includes bibliographical references.

Thesis (M.S.)--Ohio University, March, 2006. / Title from PDF t.p. Includes bibliographical references (p. 113-116)

Orientadores: Antonio Celso Fonseca de Arruda e Adolfo Alberto Leirner / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-21T17:53:16Z (GMT). No. of bitstreams: 1 Novello_WaldyrParolari_D.pdf: 6415622 bytes, checksum: 6e55b3be14643df35b02ad69af0fd66b (MD5) Previous issue date: 1996 / Resumo: O presente trabalho refere-se ao projeto, construção e avaliação de um dispositivo capaz de oxigenar e remover o dióxido de carbono do sangue durante circulação extracorpórea em operações cardíacas ou em procedimentos de suporte pulmonar. O funcionamento do dispositivo baseia-se na exposição de finas camadas de sangue a uma região com alta concentração de oxigênio. Nele, o sangue que passa por um reservatório cilíndrico, disposto horizontalmente, é exposto ao oxigênio através da rotação de discos imersos no sangue e fixos a um eixo central. A avaliação foi realizada através de testes "in vitro" e "in vivo" onde foram analisados parâmetros como: transferência gasosa, hemólise, gradiente de pressão, redução do número de plaquetas, volume interno e eficiência dos sistemas de controle de gases desenvolvidos. Através do estudo dos parâmetros construtivos e operacionais foi possível obter um dispositivo em condições seguras de utilização com fluxos de sangue de até 1,5 L/min. O oxigenador desenvolvido agrega as principais vantagens dos oxigenadores de bolhas e de membrana, sendo estes os dois tipos de oxigenadores atualmente mais utilizados nos centros cirúrgicos do mundo. Estas vantagens estão relacionadas com a eficiência, recursos operacionais, segurança quanto a vazamentos, custo e lesão aos constituintes sangüíneos / Abstract: This paper presents the design, construction and evaluation of a device capable of oxygenating and removing the carbon dioxide fTom the blood during cardiac surgical procedures requiring cardiopulmonary bypass or in pulmonary support procedures. The device works based on the exposure of thin layers of blood to a higWyoxygen concentrated region. Blood flows through a horizontally set cylindricalreservoir exposed to oxygen by the rotation ofblood immersed discs fixed to a central axis. Evaluation was performed by "in vitro" and "in vivo" tests where gas transfer, hemolysis, pressure drop, platelets number, priming volume and efficiency of developed gas control system were analyzed. The study of the design and operational parameters yielded a device with safe conditions ofuse with blood flows up to 1.5 L/min. The developed device has the main advantages of the two types of blood oxygenators presently used in the world regarding to efficiency, operational resources, leakage safety and trauma to blood elements / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

Thesis (M.S. in Biomedical Engineering)--Vanderbilt University, May 2005. / Title from title screen. Includes bibliographical references.