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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.
191

Estudo comparativo da mensuração de ventrículo esquerdo por meio de ecocardiografia nos modos M e bidimensional, nos cortes transversal e longitudinal em cães adultos normais da raça Pastor Alemão / Comparative study of left ventricular measurement by bidimensional and M mode echocardiography performed in short-axis and long-axis in adult normal German Shepherds

Valéria Marinho Costa de Oliveira 18 December 2009 (has links)
A avaliação do ventrículo esquerdo (VE) é uma das principais contribuições da ecocardiografia no estudo da função cardíaca e inclui a mensuração dos diâmetros da cavidade e espessura das paredes em diástole e sístole. O estudo por meio do modo M tem sido usado como padrão para a realização da mensuração e para o cálculo de índices sistólicos, mas o modo bidimensional também é utilizado para este fim. As medidas podem ser adquiridas a partir de dois planos de imagem: transversal e longitudinal. A definição de intervalos de confiança para valores normais de VE permite a identificação de remodelamento ventricular, concêntrico ou excêntrico, decorrente de doenças cardiovasculares ou sistêmicas. Assim sendo, o objetivo deste estudo foi comparar as medidas ecocardiográficas desta câmara obtidas pelos seguintes métodos: modo M em corte transversal, modo M em corte longitudinal, modo bidimensional em corte transversal e modo bidimensional em corte longitudinal. Adicionalmente, estudou-se o comportamento do efeito do peso e do sexo nos métodos mencionados. Foram selecionados 40 cães adultos da raça Pastor Alemão sem alterações cardiovasculares. A realização do ecocardiograma de cada animal inclui os quatro métodos descritos acima, de acordo com o recomendado pela literatura. Foram pesquisados os efeitos do corte e do método, bem como a influência do peso e do sexo, sobre cada medida estudada, linear ou derivada. O peso apresentou correlação com todas as medidas lineares de VE em pelo menos um dos métodos, mas não com fração de encurtamento (FE) e fração de ejeção (FEj). Utilizando-se a análise univariada, verificou-se que machos apresentaram todas as medidas estudadas significativamente maiores que fêmeas em pelo menos um dos métodos, exceto FE e FEj, cujos valores não foram diferentes entre os sexos. Observou-se efeito isolado do corte apenas sobre diâmetro diastólico final do ventrículo esquerdo (DdFVE), com medidas maiores obtidas no corte transversal, e mudança de comportamento do sexo nos cortes com influência significativa do peso sobre septo interventricular em diástole (SIVd). Houve efeito isolado do modo sobre os índices de função sistólica FE e FEj, com valores maiores fornecidos pelo modo M. O peso teve efeito isolado positivo sobre parede livre de ventrículo esquerdo em diástole (PLVEd), exceto no modo M em corte transversal e (diâmetro sistólico final de ventrículo esquerdo (DsFVE). O sexo, retirada a influência do peso, teve efeito isolado apenas sobre DdFVE, com machos apresentando valores significativamente maiores que fêmeas em ambos os cortes no modo bidimensional. Os resultados Os resultados mostram que há risco de erro de interpretação quando valores normais de referência, gerados a partir de determinado método, são utilizados para a avaliação de um paciente examinado por técnica de mensuração diversa, especialmente quando se obtém resultados nos limites superior ou inferior de normalidade. / Left ventricle (LV) evaluation is one of the most important contributions of echocardiography in the assessment of cardiac function. It includes measurements of internal diameter and wall thickness at end-diastole and end-sistole of this chamber. M Mode echocardiography has been widely used for measuring linear dimensions and quantifying systolic function, but bidimensional mode is also used with the same purpose. The LV measurement can be derived from transverse or longitudinal images of the heart. The establishment of normal confidence intervals of LV dimensions allows identification of concentric or excentric ventricular remodeling process secondary to cardiovascular and systemic diseases. The aim of this study was to compare LV measurements obtained from four methods: M mode in short-axis, M mode in long-axis, bidimensional mode in short-axis and bidimensional mode in long-axis view of the heart. In addition the effect of weight and gender over measures was studied in the methods mentioned above. Forty adult German Shepherds without cardiovascular diseases were selected. The echocardiogram of each animal included the four described methods, according previous referenced recommendations. The effects of axis and mode as well as weight and gender were studied for each linear or derived LV measure. Weight correlated with all linear LV measures at least in one method, but not with ejection fraction (EF) and shortening fraction (SF). All LV measures of males were greater than those of females at least in one method, except for EF and SF, which did not differ between sexes. Isolated effect of the axis was observed only for LV end diastolic diameter (LVEDD), with greater values obtained from short-axis views. The combined effect of axis, gender and weight was identified in interventricular septal end diastolic thickness. There was isolated effect of mode over EF and SF, with greater measures derived from bidimensional mode methods. Weight had isolated significant positive effect over LV enddiastole posterior wall thickness in all methods, except from M mode performed in short axis, and LV end-sistolic diameter. Gender had isolated effect only over LVEDD, males showing greater values than females in bidimensional mode in short and long axis. Professionals should be aware of the possibility of erroneous interpretation when using data obtained by a different method of that used in the patient exam as reference, mainly for the values situated in inferior and superior limits of confidence intervals.
192

Small wind turbine starting behaviour

Worasinchai, Supakit January 2012 (has links)
Small wind turbines that operate in low-wind environments are prone to suffer performance degradation as they often fail to accelerate to a steady, power-producing condition. The behaviour during this process is called “starting behaviour” and it is the subject of this present work. This thesis evaluates potential benefits that can be obtained from the improvement of starting behaviour, investigates, in particular, small wind turbine starting behaviour (both horizontal- and vertical-axis), and presents aerofoil performance characteristics (both steady and unsteady) needed for the analysis. All of the investigations were conducted using a new set of aerodynamic performance data of six aerofoils (NACA0012, SG6043, SD7062, DU06-W-200, S1223, and S1223B). All of the data were obtained at flow conditions that small wind turbine blades have to operate with during the startup - low Reynolds number (from 65000 to 150000), high angle of attack (through 360◦), and high reduced frequency (from 0.05 to 0.20). In order to obtain accurate aerodynamic data at high incidences, a series of CFD simulations were undertaken to illustrate effects of wall proximity and to determine test section sizes that offer minimum proximity effects. A study was carried out on the entire horizontal-axis wind turbine generation system to understand its starting characteristics and to estimate potential benefits of improved starting. Comparisons of three different blade configurations reveal that the use of mixed-aerofoil blades leads to a significant increase in starting capability. The improved starting capability effectively reduces the time that the turbine takes to reach its power-extraction period and, hence, an increase in overall energy yield. The increase can be as high as 40%. Investigations into H-Darriues turbine self-starting capability were made through the analogy between the aerofoil in Darrieus motion and flapping-wing flow mechanisms. The investigations reveal that the unsteadiness associated with the rotor is key to predicting its starting behaviour and the accurate prediction can be made when this transient aerofoil behaviour is correctly modelled. The investigations based upon the analogy also indicate that the unsteadiness can be exploited to promote the turbine ability to self-start. Aerodynamically, this exploitation is related to the rotor geometry itself.
193

Konstrukce paralaktické vidlicové montáže astronomického dalekohledu / Construction of Equatorial Fork Mount

Tůma, Jiří January 2010 (has links)
This master's thesis deals with design of equatorial fork mount for astronomical telescope. The issue of space object watching equipment is deeply analysed. The enclosures of analysis are used in design project. Important aspects are accuracy of motion and high resolution of mount. These parameters are compared with series manufactured equatorial mounts.
194

Řešení technologie při výrobě odlitku v malé strojírenské firmě / Solution technology of production part cast in condition small engineering company

Gulda, Jiří January 2011 (has links)
The dissertation work focuses on the design and optimization of the castings and foundry technology and the production a particular model for the casting. The technology proposal and the pattern set building in 3D using CAD system. The casting simulation in CAE MAGMAsoft® system and evaluation of the proposed casting technology. Production of the pattern using CAD/CAM software and CNC machine tools with a focus on 3-axis and 5-axis machining. The economic benefits for the company.
195

Presentation and evaluation of gated-SPECT myocardial perfusion images : Radial Slices - data reduction without  loss  of  information

Darvish, Darvish, Öçba, F.Nadideh January 2013 (has links)
Single photon emission tomography (SPECT) data from myocardial perfusion imaging (MPI) are normally displayed as a set of three slices orthogonal to the left ventricular (LV) long axis for both ECG-gated (GSPECT) and non-gated SPECT studies. The total number of slices presented for assessment depends on the size of the heart, but is typically in excess of 30.  A requirement for data presentation is that images should be orientated about the LV axis; therefore, a set of radial slice would fulfill this need. Radial slices are parallel to the LV long axis and arranged diametrically. They could provide a suitable alternative to standard orthogonal slices, with the advantage of requiring far fewer slices to adequately represent the data. In this study a semi-automatic method was developed for displaying MPI SPECT data as a set of radial slices orientated about the LV axis, with the aim of reducing the number of slices viewed, without loss of information and independent on the size of the heart. Input volume data consisted of standard short axis slices orientated perpendicular to the LV axis chosen at the time of reconstruction.  The true LV axis was determined by first determining the boundary on a central long axis slice, the axis being in the direction of the y-axis in the matrix. The skeleton of the myocardium were found and the true LV axis determined for that slice. The angle of this axis with respect to the y-axis was calculated. The process was repeated for an orthogonal long axis slice. The input volume was then rotated by the angles calculated. Radial slices generated for presentation were integrated over a sector equivalent to the imaging resolution (1.2 cm); assuming the diameter of the heart is about 8cm then non-gated data could be represented by 20 radial slices integrated over an 18 degree section. Gated information could be represented with four slices spaced at 45 intervals, integrated over a 30 degree sector.
196

Predicting Posttraumatic Stress Disorder Symptoms During Adolescence: A Longitudinal Study of The Role of Hypothalamic-Pituitary-Adrenal (HPA) Axis Dysfunction

Liu, Keke, 1988- 05 1900 (has links)
Posttraumatic stress disorder (PTSD) is a trauma-related disorder that may develop in response to traumatic or stressful events. Dysfunction of the Hypothalamic-Pituitary-Adrenal (HPA) axis has been implicated in the disorder. Studies support such dysfunction as being a consequence of PTSD, rather than a precursor. However, most studies of the HPA are either cross-sectional or have been carried out in adults. The aim of the present study was to identify whether HPA dysregulation interacts with stressful experiences to increase the likelihood of developing PTSD symptoms in a community-recruited sample of healthy adolescent girls. Adolescent girls (N = 550) and one of their parents participated. Adolescents’ clinical symptoms were assessed at baseline and at a nine month follow-up. Saliva samples were collected from all adolescent participants at waking, 30 minutes after waking, and 8 pm on 3 consecutive days. Flattened diurnal slope of cortisol at baseline was associated with increased PTSD symptoms nine months later. Baseline cortisol awakening response (CAR) per se was not prospectively related to developing PTSD symptoms, but its interactions with stressful experience was associated with elevated PTSD symptoms at follow-up. Effects were small and need to be replicated in samples with more severe stressors, as well as more clinical levels of PTSD. Nevertheless, findings suggest that dysregulated basal HPA functioning may be involved in the development of PTSD symptoms.
197

Vliv mikrobiomu na aktivitu HPA osy / Effect of microbiota on the activity of HPA axis

Fajstová, Alena January 2017 (has links)
Recent research shows, that gut microbiome can influence various functions of the organism and is able to communicate with the brain. The data also show that changes in the composition of gut microbiome can influence behavior and stress reactions and vice versa, psychological state of the organism can cause changes in gut microbiome. The aim of this master's thesis was to examine changes of HPA activation and local metabolism of glucocorticoids caused by stress in the presence or absence of gut microbiome. We therefore used germ-free mice and studied the effect of stress in pituitary, adrenal gland, colon and spleen. We found that, stress has different impact on gene expression in adrenal gland, colon and spleen in the presence or absence of gut microbiome. In contrast, there wasn't any significant effect of stress on pituitary in germ free mice and their conventionaly colonized counterparts.
198

Konstrukce naklápěcího otočného stolu / Design of tilting rotary table

Hanzlík, Aleš January 2011 (has links)
The aim of this thesis is the design of the rotary tilting table controlled the fourth and fifth axis for CNC centrum.První part includes the search for pivotally tilting tables. The second part includes the choice of technical paremetrů pivotally tilting table for selected CNC center, design of possible options , selection of appropriate options, design of the selected option.
199

Časo-prostorové utváření molekulárních gradientů v časném embryonálním vývoji Xenopus laevis. / Formation of spatio-temporal molecular gradients in early embryonic development of Xenopus laevis.

Šídová, Monika January 2015 (has links)
Clarifying the underlying spatio-temporal mechanisms that determine body pattern is important for detailed understanding of embryonic development. A crucial question of vertebrate embryogenesis remains: when and how are single blastomeres determined for differentiation that subsequently leads to body axes specification and the formation of different tissues and organs? The answer to this question will be beneficial for primary research as well as in the field of applied medicine. The main aim of the presented thesis was to study spatio-temporal molecular gradients of cell fate determinants during early embryonic development. The African clawed frog Xenopus laevis was used as a model organism because of their large size of oocytes and external embryonic development. Due to late activation of embryonic transcription, a crucial mechanism of early blastomeres determination is dependent on asymmetric localization of maternal factors within oocyte and their uneven distribution into single blastomeres during early cell division. Two main localization patterns were identified along the animal-vegetal axis of the mature Xenopus oocyte using qPCR tomography. The localization gradient with preference in either animal or vegetal hemisphere was found for maternal mRNA as well as miRNAs. Moreover, two vegetal...
200

Topological tools for discrete shape analysis / Utilisation de la topologie pour l'analyse de formes discrètes

Chaussard, John 02 December 2010 (has links)
L'analyse d'images est devenue ces dernières années une discipline de plus en plus riche de l'informatique. La topologie discrète propose un panel d'outils incontournables dans le traitement d'images, notamment grâce à l'outil du squelette, qui permet de simplifier des objets tout en conservant certaines informations intactes. Cette thèse étudie comment certains outils de la topologie discrète, notamment les squelettes, peuvent être utilisés pour le traitement d'images de matériaux.Le squelette d'un objet peut être vu comme une simplification d'un objet, possédant certaines caractéristiques identiques à celles de l'objet original. Il est alors possible d'étudier un squelette et de généraliser certains résultats à l'objet entier. Dans une première partie, nous proposons une nouvelle méthode pour conserver, dans un squelette, certaines caractéristiques géométriques de l'objet original (méthode nécessitant un paramètre de filtrage de la part de l'utilisateur) et obtenir ainsi un squelette possédant la même apparence que l'objet original. La seconde partie propose de ne plus travailler avec des objets constitués de voxels, mais avec des objets constitués de complexes cubiques. Dans ce nouveau cadre, nous proposons de nouveaux algorithmes de squelettisation, dont certains permettent de conserver certaines caractéristiques géométriques de l'objet de départ dans le squelette, de façon automatique (aucun paramètre de filtrage ne doit être donné par l'utilisateur). Nous montrerons ensuite comment un squelette, dans le cadre des complexes cubiques, peut être décomposé en différentes parties. Enfin, nous montrerons nos résultats sur différentes applications, allant de l'étude des matériaux à l'imagerie médicale / These last years, the domain of image analysis has drastically evolved. Digital topology offer a set of tools adapted to image analysis, especially the skeletonization process (also called homotopic thinning) which can simplify input data while keeping specific information untouched. In this thesis, we focus on how digital topology, especially skeletons, can help material image analysis.The goal of a skeletonization process is to remove unnecessary information from an input, and provide a simplified object, called the skeleton, having the same characteristics than the original data. It is then possible to perform some computations on the skeleton and generalise their results to the original data. In the first part of this thesis, we propose some new tools for preserving, during skeletonization, important geometrical features of the original data, and obtain a skeleton with the same visual appearance than the input.In the second part, we present the cubical complex framework, where objects are no more made only of voxels. We propose in this framework new skeletonization algorithms, some of them preserving automatically the visual aspect of the input during the thinning process (no filtering parameter from the user is required). We then show how a skeleton, in the cubical complexes framework, can be decomposed into basic parts, and we show some applications of these algorithms to material image analysis and medical image analysis

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