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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

Metal nanoparticle modified polysulfone membrane for water treatment

Phelane, Lisebo January 2013 (has links)
>Magister Scientiae - MSc / Membrane separation processes have been widely applied in the treatment of wastewater with polysulfone (PSF) polymer membrane being the most frequently used in ultrafiltration of wastewater due to its chemical and structural stability and mechanical robustness. The disadvantage to these membranes is their hydrophobicity which leads to membrane fouling caused by organic pollutants in water. Many studies have been conducted to increase the hydrophilic properties of the polysulfone membrane surface. Most recently metal oxide nanoparticles have been introduced to the polymer matrix in order to reduce membrane fouling and increase its hydrophilicity with measurable success. Natural organic matters are the one of the major fouling agents during ultrafiltration, reverse osmosis and microfiltration. Two organic acids (Tannic Acid and Alginic Acid) were selected to test the fouling behaviour of nanometallic synthesised polysulfone membranes. For this study, polysulfone casting suspension was prepared by dissolving polysulfone beads in N,N-dimethly acetamide. Three metallic nanoparticles of Silver, Cobalt and Nickel were selected to improve the hydrophilicity of the polysulfone membrane. The metal nanoparticles were prepared using the chemical reduction method. Cobalt nanoparticles were synthesized by dissolving the cobalt chloride salt in deionized water and reduced with sodium borohydride at room temperature. The nickel chloride salt was dissolved in ethanol and reduced with sodium borohydride under magnetic stirrer. Silver nanoparticles were prepared by dissolving the silver nitrate in deionised water and heated to boil, the sodium citrate was added to reduced the silver nitrate. These nanoparticles were then integrated into the polysulfone polymer matrix to form the metal nanoparticle polysulfone nanocomposites. This study focused on four prepared polysulfone nanocomposite membrane; 1 unmodified polysulfone (PSF), 2 polysulfone modified with cobalt nanoparticles (PSF/Co), 3 polysulfone modified with nickel nanoparticles (PSF/Ni) and 4 polysulfone modified with silver nanoparticles (PSF/Ag).
2

Succession planning strategies to attract partners at professional services firms

Turton, Roberta 24 September 2013 (has links)
As the struggle to attract, engage and develop talent in knowledge intensive firms increases, this paper sought to uncover succession-planning strategies professional services firms may employ to attract Chartered Accountants to partnership. Designed as an organizational action research study, this investigation elicited the perspectives of Chartered Accountants using a survey and interviews. Chartered Accountants at all stages of their career development at Collins Barrow Calgary LLP were targeted, including newly designated professionals, Managers, Senior Managers and Partners. The study found that although the role of partner is unclear to research participants, autonomy, compensation and an established firm infrastructure are enticing. Study recommendations included the creation of a compelling vision to educate and engage prospective partners, communicating attractants and barriers to advancement to partner and enhancing existing partnership talent development programs. This organizational action research project was designed in full compliance with Royal Roads University's (RRU) (2007) Research Ethics Policy.
3

O processo de cuidar do adolescente : percepção de enfermeiras do PSF

Martins, Aretusa de Oliveira 09 September 2013 (has links)
Submitted by Hiolanda Rêgo (hiolandar@gmail.com) on 2013-09-06T19:24:03Z No. of bitstreams: 1 Dessertação_enf_Aritusa Martins.pdf: 985304 bytes, checksum: 81ca1d4608f497fa1fd88855a86f7a5f (MD5) / Approved for entry into archive by Flávia Ferreira(flaviaccf@yahoo.com.br) on 2013-09-09T13:58:31Z (GMT) No. of bitstreams: 1 Dessertação_enf_Aritusa Martins.pdf: 985304 bytes, checksum: 81ca1d4608f497fa1fd88855a86f7a5f (MD5) / Made available in DSpace on 2013-09-09T13:58:31Z (GMT). No. of bitstreams: 1 Dessertação_enf_Aritusa Martins.pdf: 985304 bytes, checksum: 81ca1d4608f497fa1fd88855a86f7a5f (MD5) / O processo de cuidar do adolescente tem suscitado preocupações dos profissionais das diversas áreas de conhecimento, em especial, da educação e da saúde. Para que entendamos este processo precisamos considerar que a adolescência envolve alterações de natureza biológicas com aceleração do desenvolvimento cognitivo e estruturação da personalidade. No Brasil, existem, aproximadamente, 35 milhões de adolescentes. Este grupo, apesar de ser considerado sadio, está vulnerável a diversos problemas de saúde, entre eles, susceptibilidade às doenças infecciosas, problemas nutricionais, fatores de risco cardiovascular, doenças sexualmente transmissíveis, o uso/abuso de drogas, fragilidade da saúde mental, alterações de crescimento e desenvolvimento, além de outras circunstancias próprias desta fase. Este estudo teve como objetivo apreender e analisar as percepções das enfermeiras, que atuam nas unidades do PSF (Programa de Saúde da Família), das cidades de Itabuna e Ilhéus, sobre o adolescente e o processo de cuidar. É um estudo descritivo de abordagem qualitativa. A coleta de dados foi realizada através de entrevistas semi-estruturadas. Os sujeitos foram oito enfermeiras do município de Itabuna e quatro do município de Ilhéus, no estado da Bahia, que atuam nas unidades do PSF. Foi utilizado como referencial teórico a literatura sobre a temática e as políticas públicas de saúde voltadas para a adolescência, com ênfase no PROSAD e no PSF. Os dados apontaram que as enfermeiras têm percepções variadas acerca do adolescente tais como, um ser em fase de transição/transformação; um ser complicado, agitado, inquieto, inconstante e desinformado; e sem referência no serviço de saúde. Quanto aos sentimentos acerca do cuidar do adolescente, as enfermeiras sentem-se despreparadas, sem capacitação, necessitando de treinamento específico, educação continuada; sentem a necessidade de parcerias com grupos da comunidade; algumas não gostam de trabalhar com adolescentes, acham difícil; outras se sentem, ainda, inseguras, angustiadas e desanimadas. Tais percepções e sentimentos podem estar influenciando na situação em que se encontra a saúde dos adolescentes nas unidades onde atuam as entrevistadas, a qual não é trabalhada, especificamente, e, quando acontece é no contexto da saúde da mulher ou em palestras esporádicas sobre sexualidade. Como fatores que refletem na abordagem ao adolescente e no processo de cuidar deste, identificamos: a necessidade de um espaço físico; a formação acadêmica pouco direcionada para o adolescente; tabus e valores impregnados nas enfermeiras; imposição de conceitos por parte das enfermeiras que não oferecem oportunidade ao adolescente de expressar seus próprios conceitos, de desenvolver um pensamento crítico; e a falta de capacitação específica para atuar no processo de cuidar do adolescente. Esperamos que este estudo possa contribuir com os profissionais, estimulando-os a exercitar um esforço conjunto visando a mudança da situação em que se encontra o processo de cuidar de adolescentes, nas unidades do PSF. / Salvador
4

Restauration d'images 3D de microscopie de fluorescence en présence d'aberrations optiques / Restoration of 3D fluorescence microscopy images under the presence of optical aberrations

Ben Hadj, Saïma 17 April 2013 (has links)
Dans cette thèse, nous nous intéressons à la restauration d'image tridimensionnelle de microscopie de fluorescence. Deux difficultés majeures dans ce système d'imagerie sont traitées. La première est le flou variable en profondeur qui est dû aux aberrations induites par la variation des indices de réfraction dans le système optique et le spécimen imagé. La deuxième est le bruit qui est principalement dû au processus de comptage de photons. L'objectif de cette thèse est de réduire ces distorsions afin de fournir aux biologistes une image de meilleure qualité possible. Dans la première partie de cette thèse, nous étudions les modèles d'approximation du flou variable en profondeur et nous choisissons un modèle adéquat au problème d'inversion. Dans ce modèle, la réponse impulsionnelle (RI) variable en profondeur est approchée par une combinaison convexe d'un ensemble de RIs invariables spatialement. Nous développons pour ce modèle deux méthodes rapides de restauration non-aveugle par minimisation d'un critère régularisé, chacune d'elles est adaptée au type de bruit présent dans les images de microscopie confocale ou à champ large. Dans la deuxième partie, nous abordons le problème de restauration aveugle et proposons deux méthodes dans lesquelles le flou variable en profondeur et l'image sont conjointement estimés. Dans la première méthode, la RI est estimée en chaque voxel du volume considéré afin de laisser une grande liberté sur la forme de la RI, tandis que dans la deuxième méthode, la forme de la RI est contrainte par une fonction gaussienne afin de réduire le nombre de variables inconnues et l'espace des solutions possibles. Dans ces deux méthodes d'estimation aveugle, l'effet des aberrations optiques n'est pas efficacement estimé en raison du manque d'information. Nous améliorons ces méthodes d'estimation en alternant des contraintes dans les domaines fréquentiel et spatial. Des résultats sont montrés en simulation et sur des données réelles. / In this thesis, we focus on the restoration of three-dimensional image of fluorescence microscopy. Two major difficulties in this imaging system are considered. The first one is the depth-variant blur due to aberrations induced by the refractive index variation in the optical system and the imaged specimen. The second difficulty is the noise due to the photon counting process. The goal of this thesis is to reduce these distortions in order to provide biologists with a better image quality. In the first part of this thesis, we study the approximation models of the depth-variant blur and choose an appropriate model for the inversion problem. In that model, the depth-variant point spread function (PSF) is approximated by a convex combination of a set of space-invariant PSFs. We then develop for that model two fast non-blind restoration methods by minimizing a regularized criterion, each of these methods is adapted to the type of noise present in images of confocal or wide field microscopy. In the second part, we address the problem of blind restoration and propose two methods where the depth-variant blur and the image are jointly estimated. In the first method, the PSF is estimated at each voxel in the considered volume in order to allow high degree of freedom on the PSF shape while in the second method, the shape of the PSF is constrained by a Gaussian function in order to reduce the number of unknown variables and the space of possible solutions. In both blind estimation methods, the effect of optical aberrations is not effectively estimated due to the lack of information. We thus improve these estimation methods by alternating some constraints in the frequency and spatial domains. Results on simulated and real data are shown.
5

Desenvolvimento de um algoritmo híbrido de fotometria estelar a partir de imagens do espaço. / Development of a hybrid algorithm for time-resolved stellar photometry from space images.

Kleber Iguchi 26 November 2010 (has links)
CoRoT (Convection, Rotation and planetary Transits) é uma missão espacial liderada pela Agência Espacial Francesa (CNES) em associação com diversos parceiros internacionais, entre eles o Brasil. Seus objetivos principais são o estudo da sismologia estelar e a procura por planetas extra-solares (exoplanetas). Ambos os programas científicos baseiam-se em uma fotometria de altíssima precisão e requerem observações ininterruptas de longa duração, possíveis somente a partir do espaço. Uma revisão da literatura indica a existência de três técnicas principais para a realização de fotometria estelar a partir de imagens capturadas em CCDs: fotometria por máscara (por abertura), por ajuste de limiar (por threshold), e por ajuste da resposta impulsiva do sistema de aquisição de imagens. A fotometria por máscara, ou por abertura, apresenta maior precisão para o registro de estrelas brilhantes, em cenários de maior estabilidade de atitude do satélite (situação de baixo jitter), e é a solução adotada a bordo pelo satélite CoRoT, por ser um algoritmo determinístico. A fotometria por ajuste da resposta impulsiva, também chamada de função de espalhamento do ponto (point-spread function, PSF), por sua vez, por levar em conta a resposta do sistema a uma fonte pontual de luz, permite a restauração da imagem original através de processos de deconvolução; apresenta maior precisão para estrelas fracas, ou em um cenário degradado, com perturbações devidas a radiação externa (stray light), ou em que o jitter de atitude do satélite seja elevado. Tal robustez é uma característica desejada no processo de restauração de imagens. Já a fotometria por threshold é aplicada somente em casos de jitter muito elevado e pobre conhecimento da resposta impulsiva do sistema, de modo que não é utilizada no satélite CoRoT. Este trabalho visa consolidar e potencializar a participação brasileira no projeto CoRoT e contribuir com os esforços associados à redução de dados da missão, através de uma proposta inovadora de fotometria híbrida, que se utilizará dos conhecimentos da PSF modelada do instrumento e da alta relação sinal/ruído alcançada com a fotometria por máscara realizada a bordo, baseada e fundamentada em resultados preliminares que atestam o potencial desta metodologia. Tal algoritmo permite um ganho substancial de precisão fotométrica em relação à técnica de abertura, resultando em uma melhor exploração dos dados disponíveis, dada a sua robustez em caso de degradação dos dados de entrada. / CoRoT (Convection, Rotation and planetary Transits) is a high precision photometry experience dedicated to stellar seismology and the search for extrasolar planets. The mission is led by the French Space Agency (CNES) in association with several French laboratories and international partners in Austria, Belgium, Germany, Spain and Brazil. Both scientific programs require great instrumental stability and long, uninterrupted observation runs, which take place simultaneously on adjacent regions of the sky. An overview of the literature displays three main techniques to perform stellar photometry from space CCD images: aperture photometry, threshold photometry and PSF-fitting photometry. Aperture photometry defines a mask which represents the CCD pixels to be summed up in the computation of the collected photon flux for a given star. This method presents very high precision for isolated, bright stars and for stable satellite attitude (low jitter scenarios). It is the data reduction technique implemented on-board, due both to link capacity constraints (given the large number of targets simultaneously observed by the instrument) and to its deterministic algorithm. Fitting photometry allows restoration of degraded stellar images through deconvolution processes, using the point spread function (PSF) of the optical instrument itself. This technique presents better performance for crowded fields and for faint stars; it also presents robustness in the presence of disturbances such as stray light or high satellite attitude jitter. Finally, threshold photometry takes into account only those pixels whose values are above a given pre-computed level. This method is used only in scenarios with excessive satellite depointing due to attitude jitter, or in cases where the instrumental PSF is poorly known. Therefore, it is not used in the CoRoT mission. This work intends to consolidate and strengthen the Brazilian share in the CoRoT Project, contributing to the efforts associated to the ground-based reduction of scientific data, through an innovative, hybrid photometry technique, which will take advantage of a high-resolution instrumental PSF and of the high signal-to-noise-ratio obtained in the on-board aperture photometry. Studies here described show that this methodology, compared to the Aperture technique, achieves gains in photometric precision and in the operational duty cycle, enabling robust and accurate data exploitation.
6

ATENÇÃO À SAÚDE DO IDOSO NA PRÁTICA DIÁRIA DA EQUIPE DO PROGRAMA DE SAÚDE DA FAMÍLIA. SÃO LUÍS, 2006 / HEALTH CARE OF THE ELDERLY IN DAILY PRACTICE TEAM THE PROGRAM OF FAMILY HEALTH. SÃO LUIS, 2006.

Holanda, Vânia do Perpetuo Socorro Bastos Cantanhêde 17 March 2007 (has links)
Made available in DSpace on 2016-08-19T17:47:13Z (GMT). No. of bitstreams: 1 VANIA DO PERPETUO SOCORRO BASTOS CANTANHEDE HOLANDA.pdf: 5870696 bytes, checksum: f5e2c112a9cbb6726d2fac92561ff934 (MD5) Previous issue date: 2007-03-17 / An interesting phenomenon that is observed nowadays is that the population is getting old. This is showed in many countries, in Europe, North America and a part of Asia, but in those countries, this phenomenon is happening in a slowly way and is followed by an economical growth that helps the development of plans more systematic and efficient. In some countries that are developing, just like Brazil, this phenomenon has been happening in a quickly way, and there is a prospect that in 2025, Brazil is the sixth country in the world related by old population and in instead of those countries mentioned before, without any economical or organizational conditions that support their consequences. So, it's necessary to find a way of strategies to promote to this group age a healthy attention that preserves their functional capacity guarantying to old population independence and autonomy for as much time as possible. On this way, it's really important that everybody participate in a research to find an attention more resolved and efficient, above all the professionals that develop their plans in a basic attention, giving the possibility to take care of the elderly in their real context (familiar, social and political) avoiding to send many people to the other levels of· attention and increasing the chances to provide to elderly people a healthy aging. It argues about the attention to health elderly by the strategy of the health family, related by statement of the people that take care of this service. It is a study with exploration, descriptive and with quantities approach. The target was concluded with many different professionals that are distributed in the 89 teams of health family of São Luís, including a sample calculation that defined like representative sample to doctors, nurses and nurse auxiliaries, 30 people of each professional category - added 10% to any kind of loses. The sample concluded 33 people of each category. In spite of the "ACS" involve more professionals; opt to considerate 33 people of this category to be included on the study. So, the sample of the research made 132 people. It was identified four variables that represented statistics importance, with variations on the many professional categories studied, showed here: Kinds of planned actions, Knowledge of the National politic of heath for elderly, kinds of schedule and discretion of definition to home visit and it was concluded that even if the knowledge of the National politic of health to elderly being a priority in the health ministry schedule, is still observed the distance of its theories and the routine of the professionals of the health family from São Luís, being at least unknown by many of them with predominance in nurses auxiliaries and "ACS". The pathologies degenerative-chronicles, hypertension and diabetes are pointed like the main target of the planned actions and executed by the teams, which with the national politics of health elderly, is insufficient, maybe because the difficulties are related by the lack capacity of health professionals in the health family ion the geriatric area. The factors that interfere in the daily practice of the workers of the Health family team from São Luís, it was observed that the factors that help their work, "the actions and the services" that were developed by the team or even by the "ACS" themselves. But, the only professional category that had a different opinion was the "ACS" that attributed "the receptive of the elderly and their families" like the main facility to the development of their actions with this population. Discussing with the difficulties founded, almost everybody, excepting the doctors, that the lack of materials and equipments are the main difficulty, interfering directly in the actions that are planned and executed by the teams from São Luís. The doctors say that the main problem is related by the actions that are not being executed properly and in a unsatisfactory way. So, It is responsibility of the state and the city of São Luís, develop actions with the health family teams, for example, with enabling, just searching partnership with high school and college institutions to discuss concepts about elderly, aging, national politics of health to elderly and its interface with the principle and concepts of the program of the health family, in a way to notice and teach these professionals to the development of actions not only to elderly that are registered in the program of hypertension or diabetes, but to everyone that needs attention. It is responsibility of the city to offer conditions to the professionals of the health family program could develop their activities without any kind of interruption because of some lack of people working, materials and logistics. It is good to express that the home visit made with plans, in a systematical way and with discretion will be an important tool to identify in loco the necessities and situations that the elderly will be exposed by the program. / O envelhecimento populacional é um fenômeno vivenciado em vários países do mundo, especialmente nos da Europa, América do Norte e parte da Ásia, contudo, nesses países este fenômeno tem ocorrido de forma lenta e coincidindo com crescimento econômico, o que favoreceu o desenvolvimento de ações mais sistemáticas e eficientes. Nos países em desenvolvimento, como o Brasil, este fenômeno tem ocorrido de forma extremamente acelerada, havendo inclusive perspectiva de que este ocupe em 2025 a sexta posição no mundo em relação à população idosa e ao contrário dos primeiros, sem que haja condições econômicas e organizacionais que sustentem suas consequências. Sendo assim, faz-se necessária a formulação de estratégias de modo a proporcionar a este grupo etário uma atenção à saúde que preserve a capacidade funcional, garantindo à população idosa independência e autonomia por maior tempo possível. Neste sentido, é de suma importância à participação conjunta dos diversos atores na busca de uma atenção mais resolutiva e eficiente, sobretudo dos profissionais que desenvolvem suas ações na atenção básica, dado a possibilidade de cuidar do idoso no seu real contexto (familiar, social e político), evitando demandas preveníveis para os outros níveis de atenção e aumentando a chance de proporcionar ao idoso um envelhecimento saudável. Discorre-se sobre a atenção à saúde do idoso desenvolvida pela Estratégia Saúde da Família de São Luís, segundo profissionais que a desenvolvem. Trata-se de um estudo exploratório, analítico-descritivo com abordagem quantitativa. A população-alvo foi constituída pelos profissionais das diferentes categorias que compõe as 89 equipes de Saúde da Família do município de São Luís, sendo procedido um cálculo amostral que definiu como amostra representativa para os médicos, enfermeiros e auxiliares de enfermagem, 30 indivíduos de cada categoria profissional É acrescida de 10% para compensação de possíveis perdas. A amostra totalizou 33 indivíduos de cada categoria. Apesar da categoria de ACS envolver um número maior de profissionais, optou-se por considerar apenas 33 profissionais dessa categoria para compor o estudo. Assim, a amostra da pesquisa totalizou 132 indivíduos. Identificaram-se quatro variáveis que apresentaram significância estatística, tendo variações dentro das diversas categorias profissionais estudadas, sendo as mesmas: tipos de ações planejadas, conhecimento da PNSI, forma de agendamento e critérios de definição de visitas domiciliares e concluiu-se ainda que embora a Política Nacional de Saúde do Idoso faça parte das prioridades constantes na agenda do Ministério da Saúde, ainda observa-se certo distanciamento entre as suas diretrizes e as práticas diárias dos profissionais das Equipes de Saúde da Família de São Luís, sendo inclusive desconhecida por grande parte desses, predominantemente entre os auxiliares e agentes comunitários de saúde. As doenças crônico-degenerativas, hipertensão e diabetes mellitus, têm sido apontadas como principais alvos das ações planejadas e executadas pelas equipes, o que à luz da PNSI, representa uma abordagem limitada, talvez tal dificuldade esteja relacionada à baixa capacitação dos profissionais de saúde do PSF na área gerontogeriátrica. Com relação aos fatores que interferem nas práticas diárias dos trabalhadores do PSF de São Luís, observou-se como fatores que facilitam a atenção "as ações e serviços" já desenvolvidos pelas equipes ou pelos próprios agentes comunitários de saúde. Contudo, a única categoria profissional que teve opinião divergente foi a dos agentes comunitários de saúde que atribuiu "a receptividade dos idosos e/ou familiares" como principal facilidade para o desenvolvimento das suas ações junto a este grupo populacional. Em se tratando das dificuldades enfrentadas, foi consenso da maioria dos profissionais, com exceção dos médicos, que a deficiência no fornecimento de medicamentos, materiais e/ou equipamentos, configura-se com a principal dificuldade, interferindo diretamente nas ações que são planejadas e/ou executadas pelas equipes de São Luís. Segundo os médicos, a principal está relacionada às ações que são desenvolvidas de forma insatisfatória. Cabe, portanto ao Estado e Município de São Luís, desenvolverem ações junto as equipes de Saúde da Família relacionadas à capacitação, buscando inclusive parcerias com Instituições de ensino médio e superior, para discutir conceitos sobre idoso, envelhecimento, Política Nacional de Saúde do Idoso e sua interface com os princípios e diretrizes do PSF de modo a sensibilizar e instrumentalizar esses profissionais para o desenvolvimento de ações não apenas voltadas para os idosos que estejam cadastrados nos grupos de hipertensão e diabetes, mas para todos os outros com suas diferentes necessidades de atenção. Cabe ainda ao município oferecer condições para que os profissionais do PSF possam desenvolver suas atividades. sem que estas frequentemente sofram interrupções por deficiências de recursos humanos, materiais, insumos ou de logística. Vale referir ainda, que a visita domiciliária feita com planejamento, sistematicamente e de forma criteriosa será importante ferramenta para identificação in loco das necessidades e situações de riscos a que a população idosa acompanhada pelo programa possa estar exposta
7

Desenvolvimento de um algoritmo híbrido de fotometria estelar a partir de imagens do espaço. / Development of a hybrid algorithm for time-resolved stellar photometry from space images.

Iguchi, Kleber 26 November 2010 (has links)
CoRoT (Convection, Rotation and planetary Transits) é uma missão espacial liderada pela Agência Espacial Francesa (CNES) em associação com diversos parceiros internacionais, entre eles o Brasil. Seus objetivos principais são o estudo da sismologia estelar e a procura por planetas extra-solares (exoplanetas). Ambos os programas científicos baseiam-se em uma fotometria de altíssima precisão e requerem observações ininterruptas de longa duração, possíveis somente a partir do espaço. Uma revisão da literatura indica a existência de três técnicas principais para a realização de fotometria estelar a partir de imagens capturadas em CCDs: fotometria por máscara (por abertura), por ajuste de limiar (por threshold), e por ajuste da resposta impulsiva do sistema de aquisição de imagens. A fotometria por máscara, ou por abertura, apresenta maior precisão para o registro de estrelas brilhantes, em cenários de maior estabilidade de atitude do satélite (situação de baixo jitter), e é a solução adotada a bordo pelo satélite CoRoT, por ser um algoritmo determinístico. A fotometria por ajuste da resposta impulsiva, também chamada de função de espalhamento do ponto (point-spread function, PSF), por sua vez, por levar em conta a resposta do sistema a uma fonte pontual de luz, permite a restauração da imagem original através de processos de deconvolução; apresenta maior precisão para estrelas fracas, ou em um cenário degradado, com perturbações devidas a radiação externa (stray light), ou em que o jitter de atitude do satélite seja elevado. Tal robustez é uma característica desejada no processo de restauração de imagens. Já a fotometria por threshold é aplicada somente em casos de jitter muito elevado e pobre conhecimento da resposta impulsiva do sistema, de modo que não é utilizada no satélite CoRoT. Este trabalho visa consolidar e potencializar a participação brasileira no projeto CoRoT e contribuir com os esforços associados à redução de dados da missão, através de uma proposta inovadora de fotometria híbrida, que se utilizará dos conhecimentos da PSF modelada do instrumento e da alta relação sinal/ruído alcançada com a fotometria por máscara realizada a bordo, baseada e fundamentada em resultados preliminares que atestam o potencial desta metodologia. Tal algoritmo permite um ganho substancial de precisão fotométrica em relação à técnica de abertura, resultando em uma melhor exploração dos dados disponíveis, dada a sua robustez em caso de degradação dos dados de entrada. / CoRoT (Convection, Rotation and planetary Transits) is a high precision photometry experience dedicated to stellar seismology and the search for extrasolar planets. The mission is led by the French Space Agency (CNES) in association with several French laboratories and international partners in Austria, Belgium, Germany, Spain and Brazil. Both scientific programs require great instrumental stability and long, uninterrupted observation runs, which take place simultaneously on adjacent regions of the sky. An overview of the literature displays three main techniques to perform stellar photometry from space CCD images: aperture photometry, threshold photometry and PSF-fitting photometry. Aperture photometry defines a mask which represents the CCD pixels to be summed up in the computation of the collected photon flux for a given star. This method presents very high precision for isolated, bright stars and for stable satellite attitude (low jitter scenarios). It is the data reduction technique implemented on-board, due both to link capacity constraints (given the large number of targets simultaneously observed by the instrument) and to its deterministic algorithm. Fitting photometry allows restoration of degraded stellar images through deconvolution processes, using the point spread function (PSF) of the optical instrument itself. This technique presents better performance for crowded fields and for faint stars; it also presents robustness in the presence of disturbances such as stray light or high satellite attitude jitter. Finally, threshold photometry takes into account only those pixels whose values are above a given pre-computed level. This method is used only in scenarios with excessive satellite depointing due to attitude jitter, or in cases where the instrumental PSF is poorly known. Therefore, it is not used in the CoRoT mission. This work intends to consolidate and strengthen the Brazilian share in the CoRoT Project, contributing to the efforts associated to the ground-based reduction of scientific data, through an innovative, hybrid photometry technique, which will take advantage of a high-resolution instrumental PSF and of the high signal-to-noise-ratio obtained in the on-board aperture photometry. Studies here described show that this methodology, compared to the Aperture technique, achieves gains in photometric precision and in the operational duty cycle, enabling robust and accurate data exploitation.
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Does Adjunctive Pain Control with Dexmedetomidine Improve Outcomes in Patients with Adolescent Idiopathic Scoliosis?

Spaulding, Kole 19 May 2017 (has links)
A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Adolescent Idiopathic Scoliosis (AIS) is typically treated surgically by Posterior Spinal Fusion (PSF) surgery. Intravenous analgesics and oral opioids are commonly used for pain management. Several adjunct therapies are used in addition to the standard treatments. One of these therapies is the use of dexmedetomidine (dex). Though dex has been found to be an effective sedative for post‐operative patients, there are also several adverse effects that are associated with its use. The purpose of this study was to investigate the effectiveness and overall benefit of using dex for pain control for patients undergoing PSF for AIS. IRB approval was obtained. A group of 43 patients with AIS undergoing PSF and using Dex for adjunctive pain control were matched with 43 patients who did not use Dex. The groups were matched based on gender, age, height, weight, and level of spinal fusion. During the patients’ post‐operative hospital stay, the total opioid use and clinical pain scores were compared between the two groups using t‐tests, with significance set at p<0.05. Total opiate use was 239.6 morphine equivalent doses in the non‐Dex (control) group and 246.2 in the group that received Dex (p=0.72). The average pain score in the control group was 2.3, and the group that received Dex was 2.6 (p =0.43). There were no differences in the complication rate between the two groups, specifically the oversedation rates and pulmonary complications. Lastly, the average length of stay for the control group was 4.8 days compared to the dex group, which was 5.0 days (p=0.35). Although adjunctive pain modalities may be very useful in the treatment of postoperative pain after PSF in patients with AIS, the use of Dex in this cohort did not improve pain scores, lower opioid use, or lower the LOS. Based on these results, we do not recommend the routine use of dexmedetomidine as an adjunctive pain control modality. Adjunctive modalities are important in pain control in patients with AIS undergoing PSF, but the use of dexmedotomidine was not effective in improving pain control.
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Partial Volume Correction in PET/CT

Åkesson, Lars January 2008 (has links)
<p>In this thesis, a two-dimensional pixel-wise deconvolution method for partial volume correction (PVC) for combined Positron Emission Tomography and Computer Tomography (PET/CT) imaging has been developed. The method is based on Van Cittert's deconvolution algorithm and includes a noise reduction method based on adaptive smoothing and median filters. Furthermore, a technique to take into account the position dependent PET point spread function (PSF) and to reduce ringing artifacts is also described. The quantitative and qualitative performance of the proposed PVC algorithm was evaluated using phantom experiments with varying object size, background and noise level. PVC results in an increased activity recovery as well as image contrast enhancement. However, the quantitative performance of the algorithm is impaired by the presence of background activity and image noise. When applying the correction on clinical PET images, the result was an increase in standardized uptake values, up to 98% for small tumors in the lung. These results suggest that the PVC described in this work significantly improves activity recovery without producing excessive amount of ringing artifacts and noise amplification. The main limitations of the algorithm are the restriction to two dimensions and the lack of regularization constraints based on anatomical information from the co-registered CT images.</p>
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Partial Volume Correction in PET/CT

Åkesson, Lars January 2008 (has links)
In this thesis, a two-dimensional pixel-wise deconvolution method for partial volume correction (PVC) for combined Positron Emission Tomography and Computer Tomography (PET/CT) imaging has been developed. The method is based on Van Cittert's deconvolution algorithm and includes a noise reduction method based on adaptive smoothing and median filters. Furthermore, a technique to take into account the position dependent PET point spread function (PSF) and to reduce ringing artifacts is also described. The quantitative and qualitative performance of the proposed PVC algorithm was evaluated using phantom experiments with varying object size, background and noise level. PVC results in an increased activity recovery as well as image contrast enhancement. However, the quantitative performance of the algorithm is impaired by the presence of background activity and image noise. When applying the correction on clinical PET images, the result was an increase in standardized uptake values, up to 98% for small tumors in the lung. These results suggest that the PVC described in this work significantly improves activity recovery without producing excessive amount of ringing artifacts and noise amplification. The main limitations of the algorithm are the restriction to two dimensions and the lack of regularization constraints based on anatomical information from the co-registered CT images.

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