Els elements transposables (TEs) són seqüències repetitives amb el tret definitori de canviar la seva posició al genoma. Ocupen fraccions importants dels genomes eucariotes, y, tot i que solen considerar-se paràsits genètics, també s'especula amb la possibilitat de que tinguessin alguna funció cel·lular que encara ens és desconeguda. Tot i així, sembla evident que tenen un paper important com facilitadors de l'evolució, ja que generen variabilitat al genoma de l'hoste. El TE Galileo està implicat en la generació de reordenacions cromosòmiques adaptatives naturals a l'espècie Drosophila buzzatii, en la que hauria generat variabilitat amb valor adaptatiu per a l'hoste. A més, tots els elements Galileo trobats en treballs anteriors eren defectius – composats bàsicament d'estructures similars a la dels elements Foldback – i no es van poder establir relacions d'homologia amb ninguna seqüència coneguda. Amb aquest rerefons, en aquesta tesi es va plantejar caracteritzar l'element genètic mòbil Galileo en diferents espècies de Drosophila i analitzar la seva dinàmica evolutiva. D'aquesta forma, en una primera fase es van buscar elements Galileo complets en diferents espècies del gènere Drosophila: D. buzzatii, D. mojavensis, D. virilis, D. willitoni, D. ananassae, D. pseudoobscura i D. persimilis, fent servir tant mètodes bioinformàtics com experimentals (depenent de si el genoma analitzat estava seqüenciat o no). Les còpies trobades presenten llargues Repeticions Invertides Terminals (TIR) de fins a 1,2 Kb, una elevada identitat amb seqüències de Galileo descrites anteriorment i, a més, contenen una zona codificant que ha permès classificar Galileo com a membre de la superfamília de l'element P. Posteriorment, mitjançant anàlisis filogenètiques, hem trobat l'existència de subfamílies de Galileo en tres espècies (D. buzzatii, D. mojavensis, D. virilis) i evidència d'activitat transposicional recent (D. willitoni, D. ananassae, D. pseudoobscura, D. persimilis i D. mojavensis). En una segona fase de la tesi, hem dut a terme experiments amb part de la proteïna que es codifica a Galileo i hem comprovat que interacciona amb les TIR de Galileo, confirmant que aquesta seqüència és la responsable de la reacció de transposició. Finalment, hem analitzat en detall la diversitat de Galileo al genoma de D. mojavensis i hem detectat una diversitat estructural molt important, on l'intercanvi de seqüències entre elements pareix força freqüent per l'evolució dels TEs. / Los elementos transponibles (TEs) son secuencias repetitivas cuya característica definitoria es la capacidad de cambiar de posición en el genoma. Ocupan fracciones muy importantes de los genomas de eucariotas, y aunque se suelen considerar parásitos genéticos, también se especula con la posibilidad de que pudieran tener alguna función celular que aún nos es desconocida. No obstante, parece evidente que tienen un papel importante como facilitadores de la evolución, al generar variabilidad en el genoma del huésped. El TE Galileo está implicado en la generación de reordenaciones cromosómicas adaptativas naturales en la especie Drosophila buzzatii, con lo que habría generado variabilidad adaptativa para el huésped. Además, todos los elementos Galileo encontrados en trabajos anteriores eran defectivos – compuestos básicamente de estructuras similares a las de los elementos Foldback – y no se pudieron establecer relaciones de homología con ninguna secuencia conocida. Con este trasfondo, en esta tesis se planteó caracterizar el elemento genético móvil Galileo en diferentes especies de Drosophila y analizar su dinámica evolutiva. De esta manera, en una primera fase se buscaron elementos Galileo completos en en diferentes especies del género Drosophila: D. buzzatii, D. mojavensis, D. virilis, D. willitoni, D. ananassae, D. pseudoobscura y D. persimilis, utilizando métodos tanto bioinformáticos como experimentales (dependiendo de si el genoma analizado estaba secuenciado o no). Las copias encontradas presentan largas Repeticiones Invertidas Terminals (TIR) de hasta 1,2 Kb, una elevada identidad con secuencias de Galileo descritas con anterioridad y, además, contienen una zona codificante que ha permitido clasificar Galileo como miembro de la superfamilia del elemento P. Posteriormente, mediante análisis filogenéticos, hemos encontrado la existencia de subfamilias de Galileo en tres especies (D. buzzatii, D. mojavensis, D. virilis) y evidencias de actividad transposicional reciente (D. willitoni, D. ananassae, D. pseudoobscura, D. persimilis y D. mojavensis). En una segunda fase de la tesis, hemos llevado a cabo experimentos con parte de la proteína que codifica Galileo y hemos comprobado que interacciona con las TIR de Galileo, confirmando que esta secuencia es la responsable de la reacción de transposición. Finalmente, hemos analizado en detalle la diversidad de Galileo en el genoma de D. mojavensis y hemos detectado una diversidad estructural muy importante, lo que sugiere que el intercambio de secuencias entre elementos podría ser bastante frecuente para la evolución de los TEs. / Transposable elements (TE) are repetitive sequences whose ability to change their location in the genome defines them. They made up a important proportion of the eukaryotic genomes, and although they are often considered as genetic parasites, it has been also argued that they might have some still unknown cellular function. Nevertheless, it is clear that they play a role as drivers of their host evolution, due to the fact that TEs generate genetic variability. The TE Galileo is involved in the generation of adaptive chromosomal rearrangements in natural populations of Drosophila buzzatii, indicating that it would be a driver of adaptation in its host. Moreover, all Galileo elements found in previous works were incomplete – mainly composed by Foldback-like structures – and homology relationships could not be established with any known sequence. With this background, this thesis was proposed to characterise the mobile genetic element Galileo in different Drosophila species and analyse its evolutionary dynamics. Thus, in a first phase we searched for complete copies of Galileo in different species of the Drosophila genus: D. buzzatii, D. mojavensis, D. virilis, D. willitoni, D. ananassae, D. pseudoobscura and D. persimilis, using both bioinformatic and experimental methods (depending on whether the analysed genome was available or not). The copies found present long TIR (up to 1.2 Kb), high sequence identity with previously found Galileo sequences and, moreover, they harbour coding sequences that have allowed the classification of Galileo as a member of the P-element superfamily. Subsequently, by means of phylogenetic analyses, we have found that there are Galileo subfamilies in three different species (D. buzzatii, D. mojavensis, D. virilis) and evidence of recent transpositional activity (in D. willitoni, D. ananassae, D. pseudoobscura, D. persimilis and D. mojavensis). In a second phase of the thesis, we have conducted experiments with part of the Galileo protein and detected specific binding to the Galileo TIR, confirming that this sequence is responsible for the transposition reaction. Finally, we have thoroughly studied the Galileo variability in the D. mojavensis genome and found a striking structural variation, suggesting that the exchange of sequences among different Galileo copies might be quite common and important for TEs evolution.

Hydrocephalus is a clinical conditon where the brain tissue is deformed by the expanding ventricules. In this thesis, the mechanical deformation of a hydrocephalic brain is studied using a biomechanical model, where the material properties of the tissue are described by a viscoelastic model. A set of governing equations is derived when the motion is quasi-static motion and deformation is small. Then, finite element method is used for spatial discretization, and finite difference and trapezoidal rule are used for time-stepping. Moreover, the computational meshes are generated from medical images of patient's brain using level set method and a program called DistMesh. Numerical stability of the time-stepping scheme is also studied. <br /><br /> Several numerical studies are conducted to investigate several aspect of the brain with hydrocephalus. The state of stress of the tissue is found to be compressive everywhere in the brain. The viscoelastic properties of the brain are investigated and found to be dominated by elastic response. Lastly, the displacement made by the ventricular wall as it expands and shrinks is found to be non-uniform.

Cell-cell adhesion is important to understanding the mechanics of cell-cell interactions. A recent study of cell adhesion was conducted by others using an Atomic Force Microscopy to measure forces when two cells are brought together and then pulled apart. When the two cells come in contact, the adhesion molecules of one cell bind to molecules of the other cell throughout the contact region. When the two cells are then pulled apart, some of these bonds break off while others lead to the formation of tethers which also eventually also break. These phenomena create a force-time curve, which is difficult to interpret. In order to model this experiment and understand details of the experiments, a series of modules were added to a 2D finite element model used previously to model cells and their mechanical interactions. These new modules were designed to replicate mechanical processes associated with molecular detachments at the cell-cell interface. The enhanced model includes several new types of elements including an InterfaceTruss, which characterizes individual adhesion bonds between two cells. Parametric studies carried out using the new finite element model showed that cytoplasmic viscosity, actin cortex stiffness, and the lifetime of the molecular attachments at the cell-cell interface all affect one or more portions of the force time curve. The model was able to model virtually all of the significant features of the experimental force-time curve, and when suitable parameter values are chosen, the model closely approximates the observed features of the experimental curves. The new finite element model provides an effective tool for investigating features of the cell-cell interface. It also provides a powerful tool for learning about the mechanical properties of the cells and their bonds and tethers and for the design of new cell adhesion experiments.

Abstract The behavior for MoSi2 based high temperature heating elements for resistive heating has been examined in elevated temperature and low oxygen content environment. MoSi2 spontaneously forms a protective SiO2 scale at high temperature if the amount of oxygen in the ambient atmosphere is sufficient according to the following reaction: 5MoSi2 + 7O2(g)  7SiO2 + Mo5Si3 If the oxygen content at a specific temperature is too low, SiO(g) is more stable than SiO2 and the following reaction will occur instead: 2SiO2  2SiO(g) + O2(g) Then surface will be Si-deplated and finally, the base material will be exposed. Si and Mo will oxidize and degas from the surface as SiO and MoO3 with severe diameter reduction of the heating element as a result. It is therefore of high interest to find the relationship between the maximum element temperature and the oxygen content in the ambient atmosphere to be able to fully exploit the potential of the heating elements and also to aid and help diagnose customer complaints.   After 14 full scale tests in a custom made atmospheric furnace, the following equation could be calculated: p(O2) = 1.748·100.01677·T·log(e)-10 The equation gives the minimum oxygen content at a specified temperature. The equation is based on 100 hours tests at atmospheric pressure, gas flow rate of 4 liter per minute, varying temperature and varying oxygen content. Nitrogen has been used as carrier gas for the oxygen.

In this paper a continuous Galerkin multiscale method (CGMM) and a discontinuous Galerkin multiscale method (DGMM) are proposed, both based on the variational multiscale method for solving partial differential equations numerically. The solution is decoupled into a coarse and a fine scale contribution, where the fine-scale contribution is computed on patches with localized right hand side. Numerical experiments are presented where exponential decay of the error is observed when increasing the size of the patches for both CGMM and DGMM. DGMM gives much better accuracy when the same size of the patches are used.

An autostereoscopic display based on a Holographic Optical Element(HOE) presents new opportunities for faithful 3D displaying but also presents potential new problems, such as: accuracy of 3D objects, interactivity and user perception. In this evaluation, which is the first of its kind for this type of display, I have explored and tested methods and tools for the evaluation of these potential problems. I have found that the visual quality is comparable to more common display types but with a significant visual delay due to the parallel rendering of graphics and the projectors significant input lag. From this I have concluded that the display system is not yet ready for its intended purpose, cranio-maxillofacial surgery planning. We need projectors with less input lag and preferably better optics. The software needs to be optimized for multimonitor rendering as well.

Hydrocephalus is a clinical conditon where the brain tissue is deformed by the expanding ventricules. In this thesis, the mechanical deformation of a hydrocephalic brain is studied using a biomechanical model, where the material properties of the tissue are described by a viscoelastic model. A set of governing equations is derived when the motion is quasi-static motion and deformation is small. Then, finite element method is used for spatial discretization, and finite difference and trapezoidal rule are used for time-stepping. Moreover, the computational meshes are generated from medical images of patient's brain using level set method and a program called DistMesh. Numerical stability of the time-stepping scheme is also studied. <br /><br /> Several numerical studies are conducted to investigate several aspect of the brain with hydrocephalus. The state of stress of the tissue is found to be compressive everywhere in the brain. The viscoelastic properties of the brain are investigated and found to be dominated by elastic response. Lastly, the displacement made by the ventricular wall as it expands and shrinks is found to be non-uniform.

Cell-cell adhesion is important to understanding the mechanics of cell-cell interactions. A recent study of cell adhesion was conducted by others using an Atomic Force Microscopy to measure forces when two cells are brought together and then pulled apart. When the two cells come in contact, the adhesion molecules of one cell bind to molecules of the other cell throughout the contact region. When the two cells are then pulled apart, some of these bonds break off while others lead to the formation of tethers which also eventually also break. These phenomena create a force-time curve, which is difficult to interpret. In order to model this experiment and understand details of the experiments, a series of modules were added to a 2D finite element model used previously to model cells and their mechanical interactions. These new modules were designed to replicate mechanical processes associated with molecular detachments at the cell-cell interface. The enhanced model includes several new types of elements including an InterfaceTruss, which characterizes individual adhesion bonds between two cells. Parametric studies carried out using the new finite element model showed that cytoplasmic viscosity, actin cortex stiffness, and the lifetime of the molecular attachments at the cell-cell interface all affect one or more portions of the force time curve. The model was able to model virtually all of the significant features of the experimental force-time curve, and when suitable parameter values are chosen, the model closely approximates the observed features of the experimental curves. The new finite element model provides an effective tool for investigating features of the cell-cell interface. It also provides a powerful tool for learning about the mechanical properties of the cells and their bonds and tethers and for the design of new cell adhesion experiments.

Ultrasonic is a transport form of sound. There is no mass transportation, only energy transportation occurs in transfer process. Recently, the ultrasonic was widely used in a variety of purposes. For example¡Gsonar, non-destructive testing, washing and emulsification. Due to the effects of mechanical vibration of ultrasonic on the physiological can promote the percutaneous absorption, ultrasonic is widely used in medical cosmetic field. It can get amazing amount of spending and will continue growth every year. The skin is the body's largest organ, which can be divided into epidermis, dermis and hypodermis. There are two main approaches for drugs to be delivered through the skin: directly penetrate the epidermis and penetrate the lipid layer of cell space. The main purpose of this study is to executing numerical simulation through finite element analysis. By constructing the 3D FEM model of the skin, the effects of different level combinations of the three factors, massage time, amplitudes and frequencies of ultrasonic, on the equivalent strain distributions of the epidermis, dermis, hypodermis and muscle layers were studied, while the skin was massaged by using ultrasonic. The simulation results showed that the difference of maximum equivalent strain is nearly one hundred times between different factor¡¦s level combinations. That means the choice of the appropriate factor¡¦s level combination will affect the efficacy of ultrasonic massage seriously. The numerical simulation results also showed that amplitude is the most influential factor on the equivalent strain for every layers of skin except the epidermis.

The purpose of this study is to analyze baseball collision by using finite element method, and investigate batting effect on the sweet spot on the bat and then change the baseball geometry parameter. In addition, the researcher would like to investigate the effect of flight on batted ball by changing swing parameter. LS-DYNA is used to simulate collision on the different position on the bat after using SolidWorks to build modal, then compare the results to locate the exact position of sweet spot on the bat. By building different weight, length and radius of bat barrel, and simulate collision individually, the researcher wishes to investigate the influence of changing bat geometry parameter to batting effect on sweet spot. At last changing the undercut distance and bat swing angle, two of the swing parameter, to simulate collision, and the results of collision are used to get flight trajectory by numerical method, then analyze the influence of changing swing parameter to batted ball range. This study can provide bat geometry characteristic, swing information, and a reference for choosing a baseball bat, even help adjust batting feel for the batter.