Orientador: Ricardo Magnus Osorio Galvão / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-15T03:53:59Z (GMT). No. of bitstreams: 1 Oliveira_GlauciaMariaGleibede_M.pdf: 1785751 bytes, checksum: ff3d389a11542ca8ef20be7b281065f9 (MD5) Previous issue date: 1980 / Resumo: O objetivo deste trabalho é estudar a estabilidade do Modo Kink Interno e do Modo Kink Central em plasmas cilíndricos, MHD ideais, devido a variações de pressão e diferentes perfis de corrente. Utiliza-se a equação de Euler para estabilidade-s derivada por Goedbloed e Sakanaka. A análise do problema é baseada num método de teoria de camada limite, onde efeitos devido à inércia do plasma só são considerados numa pequena camada, no entorno do ponto onde a perturbação é paralela às linhas de campo. Para o Modo Kink Interno é feito também a análise numérica, integrando-se uma equação de valor característico. Calculou-se a razão de crescimento da instabilidade para os dois modos para diferentes perfis de pressão e corrente. Verificou-se que tanto para o Modo Kink Interno quanto para o Modo Kink Central, a razão de crescimento torna-se maior com o aumento nas variações destes perfis. Mas para o Modo Kink Interno obteve-se uma redução de até 50% na razão de crescimento, comparada com os resultados obtidos por Rosenbluth et al. Para o Modo Kink Central constatou-se que a razão de crescimento é proporcional ao b do plasma e às derivadas da pressão e corrente / Abstract: The objective of this work is to study the stability of the Internal Kink and Central Kink modes in ideal MHD cylindrical plasmas due to the pressure variations and the different current profiles. It was used the s - Euler equation derived by Goedbloed and Sakanaka. Its analysis is based on the boundary layer method, where the effects due to the plasma inertia are only considered in a boundary layer in the neighborhood of the surface where the perturbation is parallel to the field lines. For the internal Kink mode a numerical analysis is also done by integrating the Euler equation. It was calculated the growth rate of the two modes for the different pressure and current profiles. It was verified that for both, the Internal Kink and Central Kink modes, the growth rate becomes larger as the derivative of these profiles increases. However, for the Internal Kink mode, one obtains a reduction of up to 50% in the growth rate calculated by Rosenbluth et al. For the Central Kink mode, one notices that the growth rate is proportional to b of the plasma and to the derivatives of the pressure and current / Mestrado / Física / Mestre em Física

Orientador: Ricardo Magnus Osorio Galvão / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-15T07:23:33Z (GMT). No. of bitstreams: 1 Machado_WaltairVieira_M.pdf: 1976150 bytes, checksum: ebd557829c1a6a830acf6c25236b08e7 (MD5) Previous issue date: 1980 / Resumo: Até recentemente, os trabalhos sobre instabilidades resistivas têm sistematicamente considerado um sistema em equilíbrio estático no qual uma pequena perturbação é introduzida. Este modelo não é inteiramente auto-consistente, porque, em virtude da resistividade finita do plasma, o fluido tem uma velocidade de difusão resistiva de equilíbrio dada por VR = r0/tR (ou o que é equivalente, ¶B/¶t ¹ 0 no equilíbrio). O efeito de VR não se processa na escala de tempo tR, como se argumentava, e sim na escala de tempo necessária para o fluido atravessar a camada resistiva, ou seja, d/VR. Em outras palavras, VR pode ser desprezado somente para modos nos quais gd/VR >> 1. A inclusão de VR na análise de modos resistivos tais que g ~ VR/d - tende a estabilizar o modo. A análise do efeito de VR ¹ 0 na estabilidade de modos resistivos, tem sido até o presente somente restrita a modos, para os quais a perturbação está localizada no entorno da camada resistiva. O trabalho desenvolvido nesta tese estende esta análise para outros modos resistivos para os quais o efeito de VR ¹ 0 ainda não havia sido estudado. Em particular, analisaremos o modo Kink Interno Resistivo e o modo de Reconexão. Mostramos com este trabalho, que o Modo Kink Interno não é afetado pelo fluxo de difusão. No entanto o Modo de Reconexão é atenuado pela presença de um fluxo difusivo de velocidade. A razão de crescimento do modo de Reconexão, quando se considera VR ¹ 0 fica reduzida cerca de 35% em relação ao valor encontrado para a análise do modo, usando o modelo de equilíbrio estático / Abstract: Until recently works on resistive instabilities has systematically considered a system in static equilibrium on which a small perturbation is introduced. This model is not completely self-consistent, because, due to the finite plasma resitivity the fluid has an equilibrium resistive diffusion velocity given by VR = r0/tR (in another words ¶B/¶t ¹ 0 in equilibrium). The effect of VR does not occur in the time scale of tR, as usually given, but in the time scale necessary for the fluid to go through the resistive layer, i. e. , d/VR. In another words, VR can be neglected only for modes in which the growth rate g >> VR/d. An inclusion of VR in the analysis of resistive modes, such that g ~ VR/d, tends to stabilize the mode. Up to now, the analysis of the effect of VR ¹ 0 in the stability of resistive modes has been restricted to modes for which the perturbation is localized in the neighborhood of the resistive layer. In this work this analyze, is extended to other resistive modes for which the effect of VR ¹ 0 is not yet been studied. In particular, we will analyze the resistive internal kink mode and the reconnection mode. We show that the internal kink mode is not affected by the diffusion flux. However the reconnection mode is attenuated by the presence of a velocity flux diffusion. When we consider VR ¹ 0, the growth rate of the reconnection mode is reduced by about 35% relative to the static equilibrium case / Mestrado / Física / Mestre em Física

Abstract The carbonic anhydrase (CA) gene family contains eleven active members, the basic physiological functions of which are linked to the interconversion of carbon dioxide and bicarbonate (CO2 + H2O ⇔ H+ + HCO3⇔ H2CO3-). They participate in a variety of physiological processes that involve pH regulation, CO2 and HCO3- transport and water and electrolyte balance, and some new functions have also been suggested recently. A novel tumour-associated antigen, MN, containing a CA-domain and named MN/CA IX, has been found to promote cell proliferation when transfected into NIH3T3 cells and has also been shown to be a potential biomarker for neoplasia in the uterine cervix. The present study examines the expression of MN/CA IX in the normal alimentary tract by immunohistochemistry and compares it with the expression of cytoplasmic CA I, CA II, apical plasma membrane associated CA IV and secretory CA VI. The distribution of mitochondrial CA V is examined by immunohistochemistry and Western blotting. The value of MN/CA IX as a potential biomarker of gastrointestinal tumours is assessed in a series of colorectal and hepatobiliary neoplasms. A positive immunoreaction for MN/CA IX was detected in the basolateral plasma membrane of the gastric, intestinal and biliary epithelium, but was confined to the proliferating cryptal enterocytes in the human gut, suggesting a role in cellular proliferation. In colorectal tumours, MN/CA IX immunoreaction was also located in the proliferative zone, indicating that it could be a useful marker of cellular proliferation. In the case of hepatobiliary tumours a positive signal was mainly associated with tumours of biliary epithelial parentage. These results demonstrate that MN/CA IX has a unique expression pattern in the alimentary tract relative to other CAs. Its localization and enzymatic properties suggest that it may have a dual function in the gastrointestinal epithelium. Through its CA activity it could participate in the regulation of carbon dioxide/bicarbonate homeostasis, while its localization to the basolateral surfaces of proliferating cryptal enterocytes suggests that it may serve as a ligand or receptor for one or more other proteins that regulate intercellular communication and/or cell proliferation. MN/CA IX may also serve as a new biomarker of gastrointestinal tumours.

<p>This thesis demonstrates a measurement of a plasma fluctuation velocity-space cross-correlation matrix using laser induced fluorescence. The plasma fluctuation eigenmode structure on the ion velocity distribution function can be empirically determined through singular value decomposition from this measurement. This decomposition also gives the relative strengths of the modes as a function of frequency. Symmetry properties of the matrix quantify systematic error. The relation between the eigenmodes and plasma kinetic fluctuation modes is explored. A generalized wave admittance is calculated for these eigenmodes. Since the measurement is a localized technique, it may be applied to plasmas in which a single point measurement is possible, multipoint measurements may be difficult, and a velocity sensitive measurement technique is available.

Face au développement actuel des nanotechnologies il apparaît important de pouvoir contrôler la taille des nano-objets mis en oeuvre par les industriels aussi bien pour la qualité des produits manufacturés que pour la sécurité des personnes et la protection de l'environnement. Le travail qui a été accompli au cours de cette thèse concernait la recherche de solutions innovantes pour mesurer la taille de nanoparticules en voie sèche. Pour cela nous nous sommes plus particulièrement concentrés sur la physique des plasmas poudreux. En effet l'utilisation d'un plasma permet de favoriser la désagglomération de l'échantillon de poudre que l'on souhaite caractériser et la présence de poussières dans un plasma modifie sensiblement les caractéristiques électriques de ce dernier. Nous avons montré dans un premier temps qu'il est possible de déterminer la taille moyenne de poussières piégées dans une décharge capacitive RF à basse pression à partir de la mesure de la variation des paramètres électriques de cette dernière quand de la poudre s'y forme ou y est injectée. Nous avons également développé une nouvelle technique de granulométrie par sédimentation à basse pression et assistée par plasma. Cette technique consiste à disperser l'échantillon de poudre en l'injectant dans un plasma puis à en déduire sa taille à partir de la mesure de sa vitesse de sédimentation après l'extinction du plasma. Ainsi, il est possible de déterminer la fonction de distribution en taille de l'échantillon de poudre que l'on analyse. Le système que nous avons conçu a été utilisé avec succès pour contrôler en temps réel une ligne de production de nanopoudres au CEA Saclay. / The recent development of nanotechnology has made nanoparticle sizing more and more important for the quality of manufactured products as well as for human health and environmental protection. The aim of this thesis was to look for innovative solutions to measure the size and the concentration of nanoparticles in dry environnement. To meet this requirement we focused on the physics of dusty plasmas because the desagglomeration of a powder sample is enhanced when it is exposed to a plasma and the dusts modify signifcantly the electrical properties of the plasma where they are trapped. The first result of this work is the determination of the mean size of dusts that are injected or formed in a RF low pressure capacitive discharge from the variations of the electrical parameters of the plasma and of the discharge. A new particle sizing technique has also been developed. It consists of determining the powder size distribution from the measurement of its sedimentation speed following the extinction of the discharge. The system that has been designed was successfully used to monitor in real time a nanopowder production line based at the CEA Saclay.

Les plasmocytes à longue durée de vie responsables de la production d’anticorps sont majoritairement retrouvés dans la moelle osseuse (Manz, et al 1997). D’autres sites de résidence ont été décrits, comme la rate ou les lieux de réactions immunes inflammatoires. Au cours de ce travail, nous nous sommes attachés à décrire les caractéristiques des cellules plasmocytaires responsables de la sécrétion d’anticorps pathogéniques, dans une maladie auto-immune, le purpura thrombopénique immunologique (PTI). Le PTI est une maladie caractérisée par une thrombopénie d’intensité variable associée à la présence d’anticorps anti-plaquettes à l’origine d’une destruction des plaquettes par les macrophages spléniques.Nous avons étudié la rate de ces patients dans différentes conditions pathologiques, splénectomisés en seconde ligne thérapeutique, ou après traitement par un anticorps anti-CD20 déplétant les lymphocytes B. En étudiant les tissus spléniques des patients en échec primaire du traitement par anti-CD20, nous avons mis en évidence une population plasmocytaire résiduelle splénique constituée principalement de plasmocytes, qui en l’absence de lymphocytes B proliférant, préexistaient à la déplétion B. L’analyse du transcriptome de ces plasmocytes, a révélé un profil comparable aux plasmocytes de la moelle osseuse, avec un programme à longue durée de vie. A l’inverse, les plasmocytes des donneurs sains, ainsi que les plasmocytes des patients non traités par les anti-CD20 présentaient un profil intermédiaire entre les plasmocytes à longue durée de vie et les plasmablastes. Une analyse plus fine en cellule unique a confirmée qu’il s’agissait d’une population intermédiaire. Ainsi, la déplétion lymphocytaire B (par l’anticorps anti-CD20) dans le PTI semble favoriser la différenciation en plasmocytes à longue durée de vie dans la rate de ces patients, expliquant ainsi pour certain d’entre eux l’absence de réponse thérapeutique. Nos résultats suggèrent ainsi que les modifications de l’environnement splénique par la déplétion B, pourraient promouvoir la différenciation et l’établissement de plasmocytes « normaux » en plasmocytes à longue durée de vie dans la rate, notamment par le biais de BAFF (B-cell activating factor), ouvrant la perspective à des travaux fondamentaux, et surtout à des applications cliniques qui permettraient en modulant l’environnement splénique lors du traitement anti-CD20 d’empêcher la formation des plasmocytes à longue durée de vie et donc la splénectomie. / Pas de résumé en anglais

No description available.

>Magister Scientiae - MSc / Hydroxyapatite (HA), which is a natural component of bone tissue, is already being marketed as a coating for the metal shafts of hip implants as well as dental screws and other endoprostheses with the expectation of improved bonding to bone through osseointegration. Coatings prepared by the more widely used and commercial method, plasma spraying technique suffer from poor adhesion or delamination from the substrate. The high temperatures also results in a number of unstable decomposition phases compared to the more crystalline phase. The main purpose of the present research was to prepare and characterize HA coatings using low temperature sol-gel method with the specific aims of improving adhesion on both the HA/metal and HA/bone interface which have been reported failure modes of implants. / South Africa

No description available.

Many technological and biomedical applications ranging from water filtration and oil extraction to arteriosclerosis and vein thrombosis rely upon the transport of solids in liquids. Particulate matter suspended in liquid flowing through channels that are often microscopic or millimeters in size which leads to clogging. This dissertation examines the clogging behavior of microscopic channels by microscopic particles suspended in liquid. We physically model clogging in microchannels by flowing microparticles through microfluidic channels. Unlike previous studies, we choose non-uniform microchannels; specifically, we study clogging in microchannels whose width narrows over the length of the channel. Converging channels are inspired by the pore size variations in real porous media like membrane filters and sandstone. Initially we study the clogging behavior of microparticles in arrays of parallel microchannels as we vary the microchannel entrance (mouth) width and microchannel length. We measure the time until each channel clogs and we calculate the number of particles that pass prior to clogging. Contrary to expectation, we show that the number of particles passing through a pore increases exponentially with increasing mouth width but decreases linearly as the channel length increases. Changing the dimensions of the channels changes the particulate suspension’s flow rate which in turn changes the shear stresses that particles experience near the channel wall. When particles experience higher near-wall shear stress, the particles are less likely to adhere to channel walls and engender clogging. We confirm the effect of flow rate on channel clogging by demonstrating that the number of particles needed to clog a tapered channel increases as the pressure applied to the particulate suspension increases. The connection between flow rate and clogging highlights the interplay between hydrodynamic forces and intermolecular forces that govern particle attachment and ultimately clogging. We further explore this relationship by modulating the interaction between the particle and channel wall in a single tapered channel. While observing single channels clogging, we also resolve individual particles gradually building up on channel walls and forming clogs. Interestingly, particles also cluster on upstream channel walls only to later detach and clog at the downstream constriction. At low pressures, the channel clogs when particles accumulate individually near the constriction. At high pressures, the channel clogs when particle clusters detach from channel walls upstream and flow into the constriction. Finally, we compare the clogging behavior of particles with long, electrosteric stabilizing molecules on the surface to the clogging behavior of particles with shorter electrostatic stabilizing molecules on the surface. We also compare the clogging behavior of both particle types in the presence of varying concentrations of a monovalent salt. We show that clogging is mitigated when Debye length is comparable to the length of the stabilizing molecule on the particle’s surface. / Engineering and Applied Sciences - Applied Physics