No description available.

Thèse doctorat : Sciences et Techniques du Déchet : Villeurbanne, INSA : 2004. / Titre provenant de l'écran-titre. Bibliogr. p. 213-226.

No description available.

Signaling systems regulate the flow of cellular information by organizing proteins in space and time to coordinate a variety of cellular activities that are critical for the proper development, function, and maintenance of cells. Signaling molecules can exhibit several levels of complexity through the utilization of modular protein interactions, which can generate simple linear behaviors or complex behaviors such as ultrasensitivity. Protein modularity also serves as the basis for the vast protein networks that form the regulatory networks that govern several biological activities. My work focuses on the importance of protein modularity in complex biological systems, in particular the regulatory pathways of spindle positioning. The first part of my work involves the construction of a synthetic regulatory network using modular protein interactions in an effort to understand the complex behavior of the natural spindle orientation regulator Pins. Utilizing well-characterized protein domains and their binding partners, I built an autoinhibited protein switch that can be activated by a small protein domain. We found that the input-output relationship of the synthetic protein switch could be tuned by the simple addition of "decoy" domains, domains that bind and sequester input signal, thereby impeding the onset of the output response to generate an input threshold. By varying the number and affinities of the decoy domains, we found that we could transform a simple linear response into a complex, ultrasensitive one. Thus, modular protein interactions can serve as a source of complex behaviors. The second part of my work focuses on elucidating the molecular mechanisms underlying spindle positioning in the Drosophila neuroblast. I found that Pins orients the mitotic spindle by coordinating two opposite-polarity microtubule motors Dynein and Kinesin-73 through its multiple domains. Kinesin-73 also relies on its modular domain architecture to perform its duties in Pins-mediated spindle positioning, where its N-terminal half functions in coordinating cortical-microtubule capture while its C-terminal half functions as a region necessary for the activation of Dynein. Thus, modular protein design allows for the organization of spindle orientation regulators in space to achieve the complex biological activity that is spindle positioning. This dissertation includes previously published and unpublished coauthored material. / 10000-01-01

No description available.

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1989. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1989. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:24:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-02-25Bitstream added on 2014-06-13T18:20:14Z : No. of bitstreams: 1 oliveira_lca_me_arafo.pdf: 6998958 bytes, checksum: 84e0be5fadd238e2fd976b220d028362 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho é proposto analisar a distribuição de tensões produzidas na dentina radicular do incisivo central superior restaurado com diferentes sistemas de pinos intra-radiculares, através dos Métodos de Fotoelasticidade e Elementos Finitos. Esta análise foi realizada para os seguintes sistemas de pinos intra-radiculares: fibra de carbono, fibra de vidro, zircônio, aço inoxidável, titânio e metálico fundido (Liga de Cu-Al), o dente hígido foi utilizado como controle. Em ambos método foi construído um modelo bidimensional representativo do incisivo central superior e aplicada uma carga de 100 N no terço incisal da região palatina com um inclinação de 45º em relação aoa longo eixo do dente. Os resultados foram expressos em função da Tensão de Von Mises - Se e Sy, e valor da Ordem de Franja, para o Método de Elementos Finitos e Fotoelasticidade, respectivamente. Através da análise dos resultados, concluiu-se que houve diferenças significativas na distribuição de tensão entre os seis sistemas de pinos testados, sendo que, os pinos de zircônio, aço inoxidável, titânio e metálico fundido, promoveram uma alta concentração de tensões na região conduto radicular ao longo da interface pino/dentina. Nos pinos de fibra de vidro e fibra de carbono houve uma distribuição de tensões uniforme ao longo de toda a superfície radicular, não se verificou áreas de concentração de tensões produzidas por estes sistemas de pinos. Os pinos de zircônio, aço inoxidável, titânio e metálico fundido apresentaram propriedades mecânicas diferentes da estrutura dental, promovendo alterações significativas no comportamento mecânico do dente. De acordo com estes resultados, concluímos que os pinos não metálicos atendem de maneira satisfatória os requisitos necessários para proporcionarem um comportamento mais semelhante à estrutura dental, a compatibilidade... . / This work proposes a study about the distribution of mechanical stresses in the radicular dentin of restored with different posts systems, by means of the photoelastic and the finite element techniques. This analysis is conducted for the following posts systems: carbon fiber, fiberglass, zirconium, stainless steel, titanium and cast metal (Cu-Al alloy) and the healthy tooth (control). For this purpose, representative two-dimensional models of the central upper incisor are built for both methods. These models are subject to a 100N load applied at the tip of the crown, at 45º from the axle along the tooth. The results are expressed in terms of the Von Mises and Sy stresses and the fringe order, for the finite element and photoelastic methods, respectively. Through the analysis of these results, it can be concluded that significant stress distribution differences arise between the six different pin systems tested, so that those made of zirconium, stainless steel, titanium and cast metal produced high stress concentration at the post/dentin interface region. In the cases of the carbon fiber and fiberglass pins, on the other hand, the stress distribution along the radicular surface is uniform, lacking stress concentration areas. The zirconium, stainless steel, titanium and cast metal pins present mechanical properties which are different from those of the tooth structure, resulting in significant alterations over the mechanical behavior of the dental structure. The non-metallic pins comply more satisfactorily with the requirements necessary to provide a mechanical behavior more similar to that of the dental structure, the compatibility among the mechanical properties found in these system and the dentin providing a biomimetic behavior, reducing the risk of failure or root fractures.

Resumo: Neste trabalho é proposto analisar a distribuição de tensões produzidas na dentina radicular do incisivo central superior restaurado com diferentes sistemas de pinos intra-radiculares, através dos Métodos de Fotoelasticidade e Elementos Finitos. Esta análise foi realizada para os seguintes sistemas de pinos intra-radiculares: fibra de carbono, fibra de vidro, zircônio, aço inoxidável, titânio e metálico fundido (Liga de Cu-Al), o dente hígido foi utilizado como controle. Em ambos método foi construído um modelo bidimensional representativo do incisivo central superior e aplicada uma carga de 100 N no terço incisal da região palatina com um inclinação de 45º em relação aoa longo eixo do dente. Os resultados foram expressos em função da Tensão de Von Mises - Se e Sy, e valor da Ordem de Franja, para o Método de Elementos Finitos e Fotoelasticidade, respectivamente. Através da análise dos resultados, concluiu-se que houve diferenças significativas na distribuição de tensão entre os seis sistemas de pinos testados, sendo que, os pinos de zircônio, aço inoxidável, titânio e metálico fundido, promoveram uma alta concentração de tensões na região conduto radicular ao longo da interface pino/dentina. Nos pinos de fibra de vidro e fibra de carbono houve uma distribuição de tensões uniforme ao longo de toda a superfície radicular, não se verificou áreas de concentração de tensões produzidas por estes sistemas de pinos. Os pinos de zircônio, aço inoxidável, titânio e metálico fundido apresentaram propriedades mecânicas diferentes da estrutura dental, promovendo alterações significativas no comportamento mecânico do dente. De acordo com estes resultados, concluímos que os pinos não metálicos atendem de maneira satisfatória os requisitos necessários para proporcionarem um comportamento mais semelhante à estrutura dental, a compatibilidade... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: This work proposes a study about the distribution of mechanical stresses in the radicular dentin of restored with different posts systems, by means of the photoelastic and the finite element techniques. This analysis is conducted for the following posts systems: carbon fiber, fiberglass, zirconium, stainless steel, titanium and cast metal (Cu-Al alloy) and the healthy tooth (control). For this purpose, representative two-dimensional models of the central upper incisor are built for both methods. These models are subject to a 100N load applied at the tip of the crown, at 45º from the axle along the tooth. The results are expressed in terms of the Von Mises and Sy stresses and the fringe order, for the finite element and photoelastic methods, respectively. Through the analysis of these results, it can be concluded that significant stress distribution differences arise between the six different pin systems tested, so that those made of zirconium, stainless steel, titanium and cast metal produced high stress concentration at the post/dentin interface region. In the cases of the carbon fiber and fiberglass pins, on the other hand, the stress distribution along the radicular surface is uniform, lacking stress concentration areas. The zirconium, stainless steel, titanium and cast metal pins present mechanical properties which are different from those of the tooth structure, resulting in significant alterations over the mechanical behavior of the dental structure. The non-metallic pins comply more satisfactorily with the requirements necessary to provide a mechanical behavior more similar to that of the dental structure, the compatibility among the mechanical properties found in these system and the dentin providing a biomimetic behavior, reducing the risk of failure or root fractures. / Orientador: Maria Salete Machado Cândido / Coorientador: Sônia Aparecida Goulart Oliveira / Banca: Jesuânia Maria Guardiero Azevedo Pfeifer / Banca: Welingtom Dinelli / Mestre

Research evaluating the surgical repair of femoral neck fractures in dogs is limited. This study evaluated the in vitro mechanical properties of canine femoral neck fractures stabilized with two medium Orthofix® Partially-threaded Kirschner Wires (Orthofix pins), a 2.7 mm cortical bone screw placed in lag fashion with anti-rotational Kirschner wire (K-wire), and three 1.1 mm divergent K-wires. This study compared the mean compressive pressure, compressive force and area of compression created by the insertion the Orthofix pins and a 2.7 mm cortical bone screw placed in lag fashion. Monotonic testing was used to quantify mechanical strength and pressure sensitive film was used to quantify compression. There was no significant difference in the stiffness or load to failure for the three repair methods evaluated. There was no significant difference in the compressive pressure, compressive force or area of compression in osteotomies stabilized with Orthofix pins and 2.7 mm bone screws.