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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.
81

Genetic Dissection of Hypertension Related Renal Disease Using the Dahl Salt-Sensitive Rat

Garrett, Michael Richard January 2006 (has links)
No description available.
82

Genetic analysis of motor axon pathfinding in Zebrafish

Rodino-Klapac, Louise Rose 24 August 2005 (has links)
No description available.
83

Deformational plagiocephaly:prevalence, quantification and prevention of acquired cranial asymmetry in infants

Aarnivala, H. (Henri) 16 May 2017 (has links)
Abstract The recommendation for infants to sleep supine has decreased the incidence of sudden infant death syndrome by more than a half, but as another consequence, a dramatic rise has been observed in the incidence of acquired cranial asymmetry (deformational plagiocephaly, DP). According to recent data, almost half of otherwise healthy infants are affected by some degree of DP at 7 to 12 weeks of age, and especially in the USA and some Central European countries, major effort is put into treatment of severe DP. However, little is known of the prognosis of DP in the absence of intervention, and although primary preventive strategies are often recommended, a lack of evidence on the effectiveness of such measures persists. Furthermore, although 3D imaging is nowadays frequently used on infants with DP, no data is available on the accuracy of the measurements used to quantify cranial asymmetry. In the present study, the efficacy of a primary preventive program in reducing the incidence of DP was tested in a randomized, controlled trial. The course of DP in the absence of active treatment was studied throughout the first year of life, and factors impacting the prognosis of DP were investigated. The diagnostic accuracy of four 3D stereophotogrammetry-based measurements was also analyzed and compared, with a goal of determining their optimal cut-off values for DP. DP was less prevalent and less severe in the intervention group infants at the end of the RCT (3 months). The point prevalence of DP peaked at 3 months, whereafter spontaneous improvement in DP was seen throughout the follow-up period until 12 months of age. A preferential infant head position at 3 months was the strongest predictor of a subsequently unfavorable course of DP. Cranial asymmetry seen at birth was transient, and none of the older infants with torticollis had presented neck imbalance at birth, but rather appeared to develop the condition postnatally concomitantly with DP. Although all studied asymmetry-related measurements performed well regarding diagnostic accuracy, OCLR produced the most accurate classification of DP. In conclusion, primary preventive guidelines would likely aid in reducing the burden from both DP itself and associated healthcare costs, although substantial spontaneous improvement from DP can usually be expected. The cut-off values defined for the asymmetry-related measurements have clinical implication in both making the diagnosis of DP and determining the target outcomes for treatment. / Tiivistelmä Imeväisten nukuttaminen selällään on vähentänyt kätkytkuolemien määrää alle puoleen aiemmasta, mutta käytäntö on myös huomattavasti lisännyt asentoperäisen, ei-synostoottisen vinokalloisuuden esiintyvyyttä; tuoreen tutkimustiedon mukaan jopa lähes joka toisella imeväisellä on nähtävissä jonkinasteista asentovinokalloisuutta 7–12 viikon iässä. Etenkin USA:ssa ja muutamissa Keski-Euroopan maissa vaikea-asteista asentovinokalloisuutta hoidetaan aktiivisesti kypäräortoosein, mutta samanaikaisesti tietämys tilan luonnollisesta kulusta on vähäistä. Vaikka riskitekijöitä tunnetaan ja ehkäiseviä toimenpiteitä usein suositellaan, ei niiden tehosta ole juuri näyttöä. Nykyään 3D-pintakuvantamista käytetään usein vinokalloisten imeväisten seurannassa, mutta epäsymmetrian mittaamiseen käytettyjen muuttujien osuvuudesta ei ole tietoa. Tämän tutkimuksen tarkoituksena oli selvittää vastasyntyneiden vanhemmille annettavan vauvan käsittelyohjeistuksen vaikutusta asentovinokalloisuuden ilmaantuvuuteen satunnaistetussa, kontrolloidussa asetelmassa. Lisäksi pitkäaikaisseurannassa kartoitettiin asentovinokalloisuuden luonnollista kulkua ja ennusteeseen vaikuttavia tekijöitä suomalaisilla imeväisillä. Tutkimuksessa myös analysoitiin ja vertailtiin 3D-kuvista laskettavien epäsymmetriaa mittaavien muuttujien diagnostista osuvuutta. Käsittelyohjeita saaneiden lapsilla oli 3 kuukauden iässä merkittävästi vähemmän asentovinokalloisuutta ja kalloasymmetria oli lievempää kuin verrokkiryhmässä. Asentovinokalloisuuden esiintyvyys oli korkeimmillaan juuri 3 kuukauden iässä, jonka jälkeen merkittävää spontaania palautumista oli havaittavissa koko 12 kuukauden ikään jatkuneen seurannan ajan. Vastasyntyneillä nähty kalloasymmetria oli puolestaan ohimenevää, eikä myöskään vastasyntyneenä dokumentoitu kaulan liikerajoitus lisännyt myöhemmän vinokalloisuuden riskiä, vaan vinokalloisilla usein tavattava torticollis (kierokaula) näytti kehittyvän ensimmäisten elinviikkojen aikana yhdessä vinokalloisuuden kanssa. 3 kuukauden iässä havaittu imeväisen halu pitää päätään aina samaan suuntaan käännettynä oli yhteydessä kalloasymmetrian huonompaan spontaaniin palautumiseen. Tutkituista epäsymmetriaa mittaavista muuttujista OCLR erotteli vinokalloiset parhaiten. Yhteenvetona voidaan todeta, että ennaltaehkäisevä ohjeistus voisi vähentää vinokalloisuutta ja siitä aiheutuvia hoitokuluja kustannustehokkaasti, mutta vinokalloisuudelta on lupa odottaa myös merkittävää spontaania palautumista. Tutkimuksessa määritellyillä epäsymmetriaa mittaavien muuttujien raja-arvoilla on käyttöä sekä diagnostiikan että hoidon tavoitteiden määrittelemisen saroilla.
84

Human optokinetic nystagmus : a stochastic analysis

Waddington, Jonathan January 2012 (has links)
Optokinetic nystagmus (OKN) is a fundamental gaze-stabilising response in which eye movements attempt to compensate for the retinal slip caused by self-motion. The OKN response consists of a slow following movement made in the direction of stimulus motion interrupted by fast eye movements that are primarily made in the opposite direction. The timing and amplitude of these slow phases and quick phases are notably variable, but this variability is poorly understood. In this study I performed principal component analysis on OKN parameters in order to investigate how the eigenvectors and eigenvalues of the underlying components contribute to the correlation between OKN parameters over time. I found three categories of principal components that could explain the variance within each cycle of OKN, and only parameters from within a single cycle contributed highly to any given component. Differences found in the correlation matrices of OKN parameters appear to reflect changes in the eigenvalues of components, while eigenvectors remain predominantly similar across participants, and trials. I have developed a linear and stochastic model of OKN based on these results and demonstrated that OKN can be described as a 1st order Markov process, with three sources of noise affecting SP velocity, QP triggering, and QP amplitude. I have used this model to make some important predictions about the optokinetic reflex: the transient response of SP velocity, the existence of signal dependent noise in the system, the target position of QPs, and the threshold at which QPs are generated. Finally, I investigate whether the significant variability within OKN may represent adaptive control of explicit and implicit parameters. iii
85

Prevalence asymetrických stranových postižení na pohybovém aparátu v novorozeneckém a kojeneckém věku. / Prevalence of asymmetric lateral disability on musculoskeletal apparatus in the neonatal age and infancy

Hanzlová, Andrea January 2013 (has links)
Title: Prevalence of asymmetric lateral disability on musculoskeletal apparatus in the neonatal age and infancy. Objective: The purpose of this research thesis was to compile issues of possible types of asymmetric musculoskeletal impairment observed in neonates and infants, identify potential causes of these asymmetries and lateral predilection for reported types of asymmetries. The main subject of discussion are just found lateral predilection of asymmetries and relationship of their causes with prenatal, perinatal or postnatal period. Methods: This thesis is structured in the form of literary research and has descriptively- analytical character. Results: On the basis of the analysis of available sources about the asymmetric musculoskeletal impairment in neonates and infants a comprehensive picture of possible types of these impairment, their causes and lateral predilections was made. The vast majority of reported asymmetric impairment seems related to prenatal or perinatal period. Key words: asymmetry in infancy, birth injuries, congenital defects, positional preference
86

Faces of mathematics teachers in policy and practice

Basbozkurt, Hakan 30 September 2009 (has links)
This paper will report on the findings of the research that was conducted in a private school in Johannesburg about mathematics teachers’ identities described in policy and how these are demonstrated in practice. The central questions that guided the study were: ‘How are identities of mathematics teachers described in the new mathematics curriculum policy?’ and ‘How are these identities demonstrated in practice?’ I anticipated comparing teacher’s personal pedagogic and official pedagogic identities in classroom practice for Further Education and Training (FET) band from learners’ perspective since learners are at the center of the Outcome-Based-Education (OBE). This study was informed by theoretical concepts of ‘identity’ from Gee (2001), Boaler and Greeno (2000), and Jansen (2001). Naidoo and Parker’s (2005), Jita and Vandeyar (2006) and Parker (2006) analyzed tension between personal pedagogic and official pedagogic subject identities of South African teachers provided me a contextualized framework for this study. My analysis confirms that although the two teachers’ identities still have tension, reconstruction of the ‘new face’ of the teachers is on progress that has relation with ‘the kind of teacher’ is referred by the NCS.
87

Ligações deslizantes para análise dinâmica não linear geométrica de estruturas e mecanismos tridimensionais pelo método dos elementos finitos posicional / Sliding connections for the geometrical nonlinear dynamical analysis of three-dimensional structures and mechanisms by the positional finite element method

Siqueira, Tiago Morkis 22 February 2019 (has links)
Este estudo trata do desenvolvimento de uma formulação matemática para ligações deslizantes aplicada à análise dinâmica não linear geométrica de estruturas e mecanismos tridimensionais conjuntamente à sua implementação computacional. Esses tipos de ligações possuem diversas aplicações nas indústrias aeroespacial, mecânica e civil sendo de interesse prático na simulação de, por exemplo: antenas de satélite, braços robóticos e guindastes; estruturas civis aporticadas, como estruturas pré-moldadas; e o acoplamento veicular móvel em pontes de geometria qualquer. Para a introdução das ligações deslizantes nos elementos finitos de pórtico plano, pórtico espacial e de casca são empregados os métodos dos multiplicadores de Lagrange, Lagrangeano aumentado e função de penalização como forma de imposição das restrições cinemáticas das juntas. Aspectos como rugosidade e dissipação por atrito na trajetória de deslizamento das ligações são considerados de forma a complementar o modelo numérico. Conexões rotacionais entre os elementos finitos empregados são também consideradas. Adicionalmente, uma formulação para atuadores flexíveis é desenvolvida de forma a introduzir movimentação aos corpos. Para simulação do comportamento dos sólidos emprega-se uma formulação do método dos elementos finitos em uma versão Lagrangeana total baseada em posições. Utiliza-se a relação constitutiva de Saint-Venant-Kirchhoff para caracterização dos materiais. Estuda-se a integração temporal das equações não lineares do movimento com restrições através dos métodos de Newmark e α-generalizado e a solução do sistema não linear é obtida pelo método de Newton-Raphson. Diversos exemplos são apresentados para verificação das formulações propostas. / This study deals with the development of a mathematical formulation for sliding connections applied to the geometrical nonlinear dynamical analysis of three-dimensional structures and mechanisms along with its computational implementation. These kinds of connections have several applications in aerospace, mechanical and civil industries when simulating, e.g.: satellite antennas, robotic arms and cranes; frame like civil structures, such precast structures; and the coupling between moving vehicles and bridges of any geometry. For the introduction of sliding connections in plane frames, spatial frames and shell finite elements the Lagrange multipliers, augmented Lagrangian and penalty function methods are employed as to enforce the joints kinematic constraints. Aspects such as roughness and friction dissipation on the connections sliding path are considered as to complement the numerical model. Rotational connections between the employed finite elements are also considered. In addition, a formulation for flexible actuators is developed to introduce motion to the bodies. In order to simulate the behaviour of solids, a total Lagrangian finite element method formulation based on positions is employed. The Saint-Venant-Kirchhoff constitutive relation is used to characterize the materials. The time integration of the constrained nonlinear equations of motion is studied by the Newmark and generalized-α methods and the solution of the nonlinear system is obtained by the Newton-Raphson method. Several examples are presented to verify the proposed formulations.
88

Análise da influência do campo higrométrico sobre a reação álcali-agregado / Analysis of the higrometric\'s field influence on the alkali-aggregate reaction

Salomão, Rafael Corrêa 10 April 2017 (has links)
A reação álcali-sílica é uma patologia de origem química que ocorre em estruturas de concreto. A partir desta reação há a formação de um gel de álcali-sílica que em contato com a água provoca expansão e deformação da estrutura. Esta patologia traz muitos transtornos e prejuízos, principalmente em obras que estão em contato direto com a água (barragens, pontes, piers, etc) e a possibilidade de prever o comportamento e deformações em uma estrutura desse porte é de grande valia. Neste trabalho é feita a modelagem da percolação d\'água em meio poroso por meio do método dos elementos finitos, sem movimentação de malha e fazendo uso de função Heaviside contínua para a percolação. A modelagem da reação álcali-sílica é feita por meio de um modelo paramétrico, com alteração para contemplar regimes não uniformes de umidade e sua interferência na taxa de expansão. A modelagem do campo mecânico é feita pelo Método dos Elementos Finitos Posicional. / The alkali-silica reaction (ASR) is a pathology that occurs in concrete structures. Such pathology creates an alkali-silica gel that when in contact to water promotes expansion and strain on a affected structure. Most buildings that are susceptible to this fenomena are the ones in contact with water, such as dams, piers and bridges. The possibility to predict the ASR behavior and total strain developed would be helpful. In this work, finite element method with fixed mesh is employed to model seepage in a porous media. Also, it\'s used a Heaviside function for the percolation coefficient. The modeling of the alkali-silica reaction is done by a parametric model, modified to non-uniform humidity conditions and it\'s interference on the expansion rate. The modeling of the mechanical field is done by the Positional Finite Element method.
89

Estudo e desenvolvimento de código computacional para análise de impacto entre estruturas levando em consideração efeitos térmicos / Study and development of computational code to analyze impact in structures considering thermal effects

Carrazedo, Rogério 19 January 2009 (has links)
Ao se estudar problemas de impacto de estruturas deformáveis, a consideração dos efeitos térmicos se faz muito importante, pois além de se observar a transformação de energia mecânica em calor pode-se considerar, ao longo do processo de análise, as mudanças das propriedades mecânicas do material envolvido devido ao aquecimento do meio. Neste sentido, o objetivo principal deste trabalho é o desenvolvimento de uma formulação termodinamicamente consistente e sua implementação computacional, baseada no potencial de energia livre de Helmholtz e na primeira e segunda leis da termodinâmica, para se analisar, via elementos finitos, o impacto entre estruturas com comportamento termo-elástico e termo-plástico. O problema mecânico será tratado com formulação posicional desenvolvida em projetos de pesquisa anteriores e que podem ser classificados como Lagrangeano total com cinemática exata. Para a modelagem do impacto utilizar-se-á a técnica do multiplicador de Lagrange associada à teoria potencial para previsão do impacto, técnica de retorno geometricamente definida e algoritmo de integração temporal de Newmark adequadamente adaptado para problemas gerais de impacto. / It becomes quite important study the thermal effects when considering impact in structures, because besides the mechanical energy changing into heat, one may consider the changes in the material properties due overheating. In this sense, the main goal of this work is develop a thermodynamic formulation and its implementation, based in the Helmholtz free-energy and in the first and second law of thermodynamics, to analyze structures under impact. The mechanical problem will be solved by a positional finite element application developed in past researches and it can be classified as a total Lagrangean with exact kinematics. In order to consider the impact, the Lagrangean multiplier will be associated to the potential theory of impact prevision, technique geometrically defined and an adapted technique based on the time integration of Newmark, modified to impact problems.
90

Astrofotografia como estratégia no ensino da astronomia / Astrophotography as a strategy in the teaching of astronomy

Amaral, Jose Antonio do 15 March 2019 (has links)
Nesta dissertação, a observação do céu noturno utilizando como instrumento câmeras fotográficas comuns, sem qualquer pretensão profissional, adquire uma dimensão importante como instrumento de apoio ao Ensino de Astronomia, permitindo que estudantes de escolas públicas, ou qualquer pessoa interessada em aprender astronomia, tenha fácil acesso, uma vez que instrumentos óticos como telescópios, são acessíveis a bem poucos. Sob este ponto de vista, é vital oferecer aos estudantes da escola básica e a toda e qualquer pessoa interessada em ciências, oportunidade de participarem de atividades didáticas através da fotografia do céu noturno, resgatando assim o hábito latente de olhar para céu, esquecido pelas novas gerações, vítimas da poluição atmosférica e luminosa, fruto de nossa tecnologia mal dimensionada. O objetivo é incentivar o interesse pela astronomia, estabelecendo um contato sistemático deles com o céu noturno, despertando em cada um a questão fundamental: qual posição ocupamos no contexto do Universo. Este trabalho se preocupa principalmente em proporcionar estratégias acessíveis para fotografar o Céu e de como tratar sobre propostas didáticas para a Fotografia do Céu, utilizando equipamentos simples. Nosso objeto de estudo partiu de uma análise dos conteúdos de astronomia presentes na grade de Ensino Médio das escolas administradas pelo Centro Paula Souza, vinculados aos Parâmetros Curriculares Nacionais. Essa avaliação se apoiou em dois pontos de vista. No primeiro a análise se deu a partir dos conteúdos de astronomia presentes nos livros didáticos adotados pelas escolas para o triênio 2018/2019/2020, alinhados com os Parâmetros Curriculares Nacionais e a grade do ensino médio nas escolas técnicas. O segundo ponto de vista se deu através de uma pesquisa on-line com os estudantes dessas escolas, avaliando o percentual desses conteúdos a que eles efetivamente tiveram contato. Para subsidiar a análise desses percentuais, executamos um estudo sobre o conteúdo de Astronomia, na qual foram elencadas cinco questões, ligadas à proposição de temas abordados pelos professores das disciplinas que contém o tema Astronomia História da Astronomia; Sistema Solar; Estações Climáticas; Sistema Terra-Lua-Sol e Constelações do Hemisfério Sul. Os resultados mostram que, apesar da coerência entre os Parâmetros Curriculares Nacionais e a grade do ensino médio analisados, um percentual significativo de estudantes disseram não terem tido contato com um ou mais temas. A pesquisa serviu como norteadora da necessidade de elaboração e da aplicação de um material didático composto por atividades e oficinas que, utilizando a fotografia do céu noturno, a experimentação e construção de materiais didáticos, atuou como catalizador do aprendizado, reforçando esses conteúdos, utilizando as muitas formas de abordar os conceitos contidos no ensino médio, estimulando os estudantes e até mesmo professores a refletir sobre como nos relacionamos e aprendemos sobre o Universo. / In this work, the observation of the Night Sky using common photographic cameras as instrument, without any professional pretension, acquires an important dimension as a support tool for Astronomy Teaching, allowing students from public schools, or anyone interested in learning astronomy, to have easy access, since optical instruments such as telescopes are accessible to very few people. Under this point of view, it is vital to offer to students of elementary school, and to anybody interested in sciences, the opportunity to participate in didactic activities through photographs of the Night Sky, recovering therefore the habit of looking at the sky, forgotten by the new generations, victims of the atmospheric and luminous pollution, fruit of our ill-directed technology. The goal is to rise the interest for astronomy, establishing a systematic contact with the Night Sky, waking up in each one the fundamental question: which position do we occupy in the context of the Universe? This work concerns mainly in providing accessible strategies to photograph the sky and how do we deal on didactic proposals Sky photographs using simple equipment. Our object of study was based on an analysis of the astronomy contents present in the regular high-school curriculum of the schools administered by the Paula Souza Center, linked to the National Curricular Parameters. This assessment was based on two points of view. In the first one the analysis was based on the astronomy contents present in the textbooks adopted by the schools for the triennium 2018/2019/2020, aligned with the National Curricular Parameters and the high school curriculum in the technical schools. The second point of view was through an online survey with the students of these schools, evaluating the percentage of these contents to which they actually had contact. In order to subsidize the analysis of these percentages, we performed a study on the Astronomy contents, in which five issues were listed, related to the proposal of topics addressed by the teachers of the disciplines that contains the theme Astronomy - \"History of Astronomy\"; \"Solar system\"; \"Climatic seasons\"; \"Sun-Earth-Moon System\" and \"Constellations of the Southern Hemisphere\". The results show that, despite the consistency between the National Curriculum Parameters and the high school curriculum analyzed, a significant percentage of students said they did not have contact with one or more subjects. The research served as a guideline for the need to elaborate and apply a didactic material composed of activities and workshops that, using Night Sky photography, experimentation and construction of didactic materials, acted as a catalyst for learning, reinforcing these contents, using many ways to approach the concepts contained in high school, encouraging students and even teachers to reflect on how we relate and learn about the Universe.

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