Sprains are the most common injuries to ligamentous tissues. They are classified as first-degree, second-degree, or third-degree sprains depending upon their severity. First-degree sprains are the result of over-stretching of ligaments. Second-degree sprains involve partial tears of the ligaments. In third-degree sprains, the ligaments are completely torn. Although first- and second-degree sprains are not as severe as third-degree sprains, they occur more frequently. The mechanisms leading to sprains are still not well understood. Therefore, histo-mechanical experiments and theoretical studies are needed to advance our current knowledge on the etiology of sprains. In the first part of this study, a structurally-based constitutive equation is proposed to simulate the damage evolution process in ligaments. The ligament is modeled as a bundle of crimped collagen fibers that are assumed to be oriented along one direction, the physiological loading direction. The gradual straightening of collagen fibers determines the nonlinearity in the toe region of the tensile axial stress-strain curve. Straight collagen fibers behave as a linear elastic material. The gradual damage of collagen fibers determines the nonlinearity in the failure region of the tensile axial stress-strain curve. The parameters in the constitutive equation are estimated by curve fitting experimental data on rat medial collateral ligaments (MCLs) published in the biomechanics literature. In the second part of this study, mechanical experiments are performed in order to identify and quantify damage in ligamentous tissues. MCLs, which are harvested from Sprague-Dawley (SD) rats, are subjected to displacement controlled tensile tests. Specifically, the ligaments are stretched to consecutively increasing stretch values until their complete failure occurs. The elongation of the toe region and decrease in tangent modulus of the linear region of the collected stress-strain data are analyzed and two significantly different damage threshold strains are determined. The effect of age and skeletal maturation on the damage evolution process is also investigated by performing mechanical tests on MCLs isolated from two age groups of SD rats. In the third part of this study, scanning electron microscopy (SEM) is used to determine variations in the microstructure of ligaments that are associated with the elongation of the toe region and decrease in tangent modulus of the linear region of the stress-strain curve. MCLs from SD rats are subjected to different threshold strains that produce damage and, subsequently, examined using SEM. By comparing the morphology of collagen fibers and fibrils in undamaged and damaged MCLs, the microscopic variations induced by strain are determined and correlated to the observed macroscopic mechanical damage. / Ph. D.

Yes / While the importance of s-commerce is implicitly recognized, inconsistencies in extant empirical research pose significant challenges. Based on perspectives from trust, social presence, and socio-technical theories, this study develops an integrated model of the factors that influence intention and use behavior, with particular attention to the role of trust in s-commerce. The model is tested using meta-analytic structural equation modeling techniques on 201 observations from 83 s-commerce studies. Implications for research and practice are discussed.

A team at Goddard Space Flight center has developed a coating of aluminum mirrors they term XeLiF. This coating has high ultraviolet reflection and improved environmental stability over similar LiF coatings. For these reasons, it is a potential candidate for the future Habitable Worlds Observatory (HWO) flagship space telescope mission. However, the stability of XeLiF at the planned L2 orbit of HWO has not been investigated. This study highlights the potential damage to XeLiF when irradiated by electrons that will be present at L2. This radiation will begin removing LiF after 6 years of exposure as well as start roughening the surface. An RMS roughness over 40 nm will be reached by 30 years. Protective measures or replacement coatings need to be investigated.

The current generation of structural equation modeling (SEM) is loosely split in two divergent groups - covariance-based and variance-based structural equation modeling. The relative newness of variance-based SEM has limited the development of techniques that extend its applicability to non-metric data. This study focuses upon the extension of general linear model techniques within the variance-based platform of partial least squares structural equation modeling (PLS-SEM). This modeling procedure receives it name through the iterative PLS‑SEM algorithm's estimates of the coefficients for the partial ordinary least squares regression models in both the measurement model and the overall structural model. This research addresses the following research questions: (1) What are the appropriate measures for data segmentation within PLS‑SEM? (2) What are the appropriate steps for the analysis of rank-ordered path coefficients within PLS‑SEM? and (3) What is an appropriate model selection index for PLS‑SEM? The limited type of data to which PLS-SEM is applicable suggests an opportunity to extend the method for use with different data and as a result a broader number of applications. This study develops and tests several methodologies that are prevalent in the general linear model (GLM). The proposed data segmentation approaches posited and tested through post hoc analysis of structural model. Monte Carlo simulation allows demonstrating the improvement of the proposed model fit indices in comparison to the established indices found within the SEM literature. These posited PLS methods, that are logical transfers of GLM methods, are tested using examples. These tests enable demonstrating the methods and recommending reporting requirements.

Esta pesquisa contextualiza a emergência histórica do Boletim Sem Terra, sistematiza o conteúdo e forma da publicação desde a primeira edição ­ em maio de 1981 ­ até a consolidação do Jornal Sem Terra, como instrumento do então recém-fundado Movimento dos Trabalhadores Rurais Sem Terra (MST). O estudo parte de uma discussão conceitual sobre a comunicação de massa e hegemônica, passando pelos referenciais de cidadania, jornalismo alternativo, mídia radical e popular, para situar o objeto no conjunto da comunicação contra- hegemônica. Analisa a questão agrária e a luta pela terra no Brasil, com a apresentação de outras experiências de imprensa de movimentos sociais do campo. A partir de uma perspectiva histórica da ocupação da Encruzilhada Natalino, no Rio Grande do Sul, que originou o Boletim Sem Terra, sistematiza o conteúdo de 43 edições da publicação, divididas em quatro fases, até sua transferência de Porto Alegre para São Paulo, em maio de 1985. Por fim, analisa as práticas e formas de fazer do periódico, sua relação com a Igreja e seu papel na articulação do MST nacionalmente. / This research contextualizes the historical urgency of \"Boletim Sem Terra\" (Landless workers Bulletin). It systematizes the contents and form of the publication, since its first edition, in May 1981, up to its consolidation as \"Jornal Sem Terra\" (Landless workers Newspaper), as a tool of the at the time newly founded Movimento dos Trabalhadores Rurais Sem Terra (MST, Landless Workers\' Movement). The study starts from a conceptual discussion about mass and hegemonic communication, going through citzenship referential, alternative journalism, radical and popular media, to place the subject in the counter-hegemonic communication group. This study analyzes the agrarian issue and the struggle for land in Brazil, introducing others rural social movements media experiences. Taking a historical perspective about the occupation of \"Encruzilhada Natalino\", in the state of Rio Grande do Sul, Brazil - where the bulletin was created -, this research systematizes the contents of 43 editions of the publication, divided in four periods, until it was transfered to São Paulo, in May 1985. Lastly, this study analyzes the periodical\'s uses and ways of being produced, its relationship with the Church and its role in MST\'s national organization and political articulation.

Made available in DSpace on 2015-04-14T13:39:01Z (GMT). No. of bitstreams: 1 454109.pdf: 1412748 bytes, checksum: 299ca1ac4eb3e5f1edc408ae212d88c2 (MD5) Previous issue date: 2014-01-08 / The aim of this paper is to research the position of adjectives in both Mandarin and Brazilian Portuguese, with respect to syntax and semantics. When compared to Mandarin which has a more rigid order, Brazilian Portuguese has the greater flexibility in the word order of the noun phrase, especially, the adjective position. Firstly, the relevant studies concern about adjectives of the two languages are taken up, with the objective of showing what they form a class of words with a peculiar syntactic-semantic behavior. Secondly, this paper also presents the syntactic approaches that explain the flexibility of the position of adjectives in Brazilian Portuguese in an interface with semantics. Meanwhile, proposals are illustrated, in which describe syntactic and semantic properties with regard to the adjective positioning in Mandarin. Lastly, this work discusses the limitations and reflections of the adopted theories. In addition, the analysis of adjectives within a noun phrase of Brazilian Portuguese and Mandarin, leads proposing a syntactic-semantic proximity between the two both languages in some extent / Este trabalho tem como objetivo investigar a posi??o de adjetivos no portugu?s brasileiro e no mandarim com rela??o ? sintaxe e sem?ntica. O portugu?s brasileiro apresenta maior flexibilidade na ordem dos elementos no sintagma nominal, sendo mais livres as posi??es que os adjetivos ocupam, se comparadas ?s do mandarim que apresenta uma ordem mais r?gida. Em primeiro lugar, retomam-se os estudos relevantes sobre adjetivos das duas l?nguas para evidenciar que eles formam uma classe de palavras com o comportamento sint?tico-sem?ntico peculiar. Segundo, buscam-se abordagens sint?ticas que explicam a flexibilidade da posi??o de adjetivos do portugu?s brasileiro em interface com a sem?ntica. Em paralelo, ilustram-se propostas que apresentam propriedades sint?tica e sem?ntica, no que diz respeito ao posicionamento de adjetivos no mandarim. Finalmente, discutem-se as limita??es e reflex?es das teorias adotadas neste trabalho. Al?m disso, ao propor que existe, de certa forma, a proximidade sint?tico-sem?ntica entre o portugu?s brasileiro e mandarim, realiza-se a an?lise de adjetivos dentro de sintagma nominal em ambas as l?nguas

A melhora na eficiência do uso do espectro de radiofrequência é fundamental para permitir um desempenho adequado dos diversos sistemas sem fio cuja complexidade e requerimentos aumentam a cada dia. O panorama atual de atribuição de canais é estático, tolerando assim, que o espectro de radiofrequência seja usado de forma desequilibrada, gerando com isso, problemas de coexistência em algumas faixas e subutilização de recursos em outras. Para contornar esse problema, tem sido proposta a ideia de introduzir algoritmos de cognição nos dispositivos sem fio, a fim de permitir um modelo de alocação dinâmico adicional. Neste, os usuários secundários equipados com rádios cognitivos podem utilizar de forma dinâmica os canais subutilizados de usuários primários. Um usuário primário tem prioridade de uso do canal como consequência da atribuição estática, porém, o uso do canal por um usuário secundário qualquer é oportunista e limitando ao tempo de inatividade do usuário primário em um determinado local. As redes de sensores sem fio trabalham em uma banda concorrida e são sistemas que podem melhorar seu desempenho utilizando um mecanismo de acesso dinâmico aos canais, possibilitando o aproveitamento dos períodos de inatividade de usuários primários ou aumentando sua capacidade de coexistência na banda de operação atual. Segundo a literatura pesquisada são vários os desafios existentes para conseguir um método distribuído de acesso dinâmico aos canais que considere as restrições de trocas de sinalizações, consumo de energia e complexidade dos dispositivos de uma rede de sensores sem fio. Neste contexto, propõe-se uma metodologia de sensoriamento e acesso dinâmico aos canais para uma rede de sensores sem fio considerando a simplicidade dos dispositivos. Como fatores de inovação, optou-se pela definição de uma política de sensoriamento por clusters que permite realizar uma aprendizagem cooperativa por reforço da situação dos canais de operação. Além disso, a definição de um mecanismo de acesso dinâmico aos canais fundamentado no padrão IEEE 802.15.4 permite comunicação e coordenação distribuída de forma assíncrona. O funcionamento da metodologia proposta é avaliado e comparado usando simulações e experimentos mediante um estudo de caso específico. As comparações são realizadas com métodos de seleção de canal: fixa, cega ou baseada em recompensas por acesso. Os resultados mostram a eficiência no acesso dinâmico aos canais com aumentos na taxa de entrega de mensagens e na capacidade de coexistir com as redes primárias. / The efficiency improvement of the use of radiofrequency spectrum is fundamental to allow more complex and more optimal wireless systems. The current channel allocation is static. It tolerates unbalanced use of the radiofrequency spectrum generating coexistence problems in some bands and underutilization of resources in other bands. The introduction of cognitive algorithms into wireless devices has been proposed to overcome that problem, in order to allow an additional dynamic allocation model. In this, the secondary users equipped with cognitive radios will be able to use dynamically the underutilized channels of primary users. A primary user has channel usage priority related to the static allocation, on the other hand, the use of the channel by any secondary user is opportunistic and limited to the inactivity time of the primary user in a specific place. Wireless sensor networks work in a competitive band. These systems can improve their performance using a dynamic access to the channels and consequently to enable the utilization of inactivity periods of primary users or to increase the coexistence capability at their current operation band. According to the researched literature, several challenges exist to find a distributed method for dynamic access to the channels considering the restrictions on control signaling, energy consumption and computational complexity of wireless sensor network devices. In this context, a methodology of sensing and dynamic access to the channels in a wireless sensor network considering the restrictions of the devices is proposed. As innovation, we opted for the definition of a sensing policy by clusters that allows the cooperative reinforcement learning of the situation of channels. In addition, a mechanism for dynamic access to the channels based on the IEEE 802.15.4 standard is defined to allow asynchronous and distributed coordination. The behavior of the proposed methodology is evaluated and compared using simulations and experiments through a specific case study. The comparisons are performed with channel selection methods: fixed, blind and access based. The results show good efficiency in the dynamic allocation of the channels, increasing the message delivery rate and the coexistence capability.

Submitted by Nathalya Silva (nathyjf033@gmail.com) on 2017-06-28T18:50:54Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_QualidadeVideoBaseada.pdf: 5424847 bytes, checksum: d1e53f54bb4188d31d8d98a7322b0d6e (MD5) / Approved for entry into archive by Irvana Coutinho (irvana@ufpa.br) on 2017-08-10T12:24:31Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_QualidadeVideoBaseada.pdf: 5424847 bytes, checksum: d1e53f54bb4188d31d8d98a7322b0d6e (MD5) / Made available in DSpace on 2017-08-10T12:24:31Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_QualidadeVideoBaseada.pdf: 5424847 bytes, checksum: d1e53f54bb4188d31d8d98a7322b0d6e (MD5) Previous issue date: 2017-03-10 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / O fluxo de informação multimídia digital em redes sem fio tem crescido de forma exponencial, devido à popularização dos padrões IEEE 802.11 como tecnologia de acesso, bem como ao aumento de dispositivos (clientes) que operam neste padrão. O streaming de vídeo em altas resoluções também está se tornando comum nessas redes, impulsionando o desenvolvimento de CODECs mais eficientes. Neste contexto, algumas métricas de QoE e QoS devem ser atendidas para entregar um conteúdo com qualidade ao usuário final. Esta dissertação estuda o comportamento do streaming de vídeo em rede sem fio utilizando o padrão IEEE 802.11ac operando na faixa de 5,2 GHz, o CODEC avaliado é o H.264/AVC para as resoluções 720p, 1080p e 2160p. A partir das simulações das perdas de pacotes durante a transmissão de vídeo foi desenvolvido uma estimativa da média da perda de PSNR para cada resolução, encontrando a relação da perda de qualidade de vídeo variando a resolução em função da perda de pacotes. O modelo proposto apresentou bons resultados quando comparado com os dados reais, obtendo RMSE de aproximadamente de 2,32 dB e desvio padrão de 2,2 dB. Esta modelagem pode auxiliar no planejamento da rede de comunicação bem como no aprimoramento de novos codificadores de fonte, resultando em uma melhor qualidade de experiencia. / The flow of digital multimedia information in wireless networks has grown exponentially due to the popularization of the IEEE 802.11 Standards as access technology, as well as the increase of devices (clients) that operate in this standard. High-resolution video streaming is also becoming commonplace in these networks, driving the development of more efficient CODECs. In this context, some QoE and QoS metrics must be met to deliver quality content to the end user. This dissertation studies the behavior of wireless video streaming using the IEEE 802.11ac standard operating in the 5.2 GHz range, the CODEC rated is the H.264 / AVC for the 720p, 1080p and 2160p resolutions. From the packet loss simulations during video transmission an estimate of the average loss of PSNR for each resolution was developed, finding the relation of the loss of video quality varying the resolution in function of the loss of packets. The proposed model presented good results when compared to the real data, obtaining RMSE of 2.32 dB and standard deviation of 2.2 dB. This modeling can aid in communication network planning as well as enhancement of new source encoders, resulting in a better quality of experience.

This work presents a new approach of fabricating arrays of electrodes, separated by sub-micrometer gaps allowing the systematic investigation of electric properties of organic semiconductors. The laterally stacked devices are fabricated by using a trench isolation technique for separating different electrical potentials, as it is known for micromachining technologies like Single Crystal Reactive Ion Etching and Metallization (SCREAM). The essential part of this process is the patterning of sub-micrometer trenches onto the silicon substrate in a single lithographic step. Afterwards, the trenches are refilled by SiO2 to allow the precise tuning of the electrode separation gap. The metal electrodes are formed via magnetron sputtering. This technological approach allows us to fabricate device structures with a transport channel length in the range of 100-250 nm by conventional photolithography. In this experiment, three different metals like Au, Co, and Ni were used as the electrode materials, while copper phthalocyanine, being deposited by thermal evaporation in high vacuum, was employed as the organic semiconductor under evaluation. The final aim has been study of spin transport through the organic channel in varied geometry.

The present paper develops a procedure based on multivariate copulas for simulating multivariate non-normal data that satisfies a pre-specified covariance matrix. The covariance matrix used, can comply with a specific moment structure form (e.g., a factor analysis or a general SEM model). So the method is particularly useful for Monte Carlo evaluation of SEM models in the context of non-normal data. The new procedure for non-normal data simulation is theoretically described and also implemented on the widely used R environment. The quality of the method is assessed by performing Monte Carlo simulations. Within this context a one-sample test on the observed VC-matrix is involved. This test is robust against normality violations. This test is defined through a particular SEM setting. Finally, an example for Monte Carlo evaluation of SEM modeling of non-normal data using this method is presented. (author's abstract) / Series: Research Report Series / Department of Statistics and Mathematics