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Contribuição à análise de estabilidade transitória, em duas escalas de tempo, de sistemas elétricos de potência via métodos diretos; Contribution to two-time scale transient stability assessment of power systems by direct methods

Theodoro, Edson Aparecido Rozas
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/03/2013 PT
Relevância na Pesquisa
36.34%
O presente trabalho tem como objetivo investigar a presença de diferentes escalas de tempo nos modelos matemáticos que descrevem a dinâmica dos sistemas elétricos de potência (SEPs), em particular a existência de duas escalas de tempo distintas: lenta e rápida, e explorá-las no estudo de estabilidade transitória destes sistemas através da utilização de métodos diretos (funções energia). Em particular, o método do Ponto de Equilíbrio Instável de Controle (CUEP) para modelos com duas escalas de tempo será estudado e aplicado na análise de estabilidade transitória de SEPs. As bases teóricas para a análise de estabilidade transitória, de sistemas com duas escalas de tempo, serão apresentadas, assim como funções energia e novos algoritmos numéricos para o cálculo do CUEP nestes sistemas, a fim de evidenciar as melhorias e possíveis limitações deste novo método CUEP em duas escalas de tempo quando comparado ao método CUEP tradicional. Explorando as escalas de tempo lenta e rápida na análise de estabilidade transitória, espera-se que novos algoritmos numéricos mais robustos para o cálculo do CUEP sejam obtidos, assim como a diminuição do conservadorismo dos resultados.; The main objective of this work is to investigate the existence of several time-scales in the mathematical models of electric power systems...

Instabilidade lateral de vigas pré-moldadas em situações transitórias; Lateral stability of precast concrete beams during transient situations

Krahl, Pablo Augusto
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/04/2014 PT
Relevância na Pesquisa
36.34%
O objetivo desta pesquisa é apresentar procedimentos de verificação da estabilidade lateral de vigas de concreto em situações transitórias e com eles realizar análises paramétricas. As fases transitórias estudadas são içamento, transporte e pré-serviço com e sem contraventamento nos apoios. As formulações apresentadas contém cálculo de carga crítica de instabilidade lateral, momento crítico e fator de segurança. São apresentados exemplos numéricos e a partir deles realizadas análises paramétricas com intuito de determinar limites de segurança. Os parâmetros variados foram fck, imperfeições geométricas, vão, largura da mesa comprimida e espessura da alma fazendo uma comparação entre vigas I e retangular. Com os resultados, foram obtidas esbeltezes geométricas limite para fases transitórias, relações entre carga crítica e carga devido ao peso próprio e uma relação entre momento crítico elástico e momento último de flexão para a fase transitória anterior à execução do tabuleiro com contraventamento nos apoios, especificamente. Na comparação entre vigas I e retangular, constatou-se que os dois tipos de seção apresentam limites de segurança distintos. As análises mostraram que os limites de esbeltez geométrica recomendados...

Um método para previsão de sobrecarga transiente em sistemas computacionais por meio de modelos dinâmicos obtidos empiricamente; A method for transient overload prediction in computer systems from empirically obtained dynamical models

Luz, Helder Jefferson Ferreira da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/10/2014 PT
Relevância na Pesquisa
36.29%
Este trabalho apresenta um método empírico para previsão de sobrecargas transientes em sistemas computacionais por meio de modelagem dinâmica. A técnica, baseada em aproximações lineares e invariantes no tempo, tem como objetivo identificar a capacidade de um sistema computacional absorver variações na carga de trabalho. Experimentalmente, a identificação dessa capacidade do sistema pode ser feita por meio de técnicas de avaliação de desempenho, em que a abordagem prevalente é a estimação da capacidade estática em regime estacionário de operação, observando-se o desempenho sob demanda constante. Entretanto, essa avaliação não considera o regime transiente do sistema, i.e durante o período de restabelecimento ao regime estacionário após uma perturbação, e durante o qual, o esforço exigido pode ser bastante diverso, e potencialmente acima daquele apurado sob condições de regime estacionário. A proposta deste trabalho é a formulação de uma metodologia para avaliação de desempenho em regime transiente em sistemas computacionais sob carga de trabalho variável e que forneça informação para o dimensionamento de recursos e políticas de controle de admissão que evitem sobrecargas por efeitos transitórios. A metodologia baseia-se na parametrização de um modelo dinâmico a partir de ensaios experimentais...

Transient-fault robust systems exploiting quasi-delay insensitive asynchronous circuits; Sistemas robustos a falhas transientes explorando circuitos assíncronos quase-insensíveis aos atrasos

Bastos, Rodrigo Possamai
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
ENG
Relevância na Pesquisa
36.39%
Os circuitos integrados recentes baseados em tecnologias nanoeletrônicas estão significativamente mais vulneráveis a falhas transientes. Os erros gerados são assim também mais críticos do que eram antes. Esta tese apresenta uma nova virtude em termos de confiabilidade dos circuitos assíncronos quase-insensíveis aos atrasos (QDI): a sua grande habilidade natural para mitigar falhas transientes de longa duração, que são severas em circuitos síncronos modernos. Uma metodologia para avaliar comparativamente os efeitos de falhas transientes tanto em circuitos síncronos como em circuitos assíncronos QDI é apresentada. Além disso, um método para obter a habilidade de mitigação de falhas transientes dos elementos de memória de circuitos QDI (ou seja, os C-elements) é também proposto. Por fim, técnicas de mitigação são sugeridas para aumentar ainda mais a atenuação de falhas transientes por parte dos Celements e, por consequência, também a robustez dos sistemas assíncronos QDI.; Recent deep-submicron technology-based ICs are significantly more vulnerable to transient faults. The arisen errors are thus also more critical than they have ever been before. This thesis presents a further novel benefit of the Quasi-Delay Insensitive (QDI) asynchronous circuits in terms of reliability: their strong natural ability to mitigate longduration transient faults that are severe in modern synchronous circuits. A methodology to evaluate comparatively the transient-fault effects on synchronous and QDI asynchronous circuits is presented. Furthermore...

Modelagem e caracterização da propagação de pulsos transientes causados por radiação ionizante; Modeling and characterization of the propagation of transient pulses caused by ionizing radiation

Ribeiro, Ivandro da Silva
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.34%
A propagação de eventos transientes na lógica combinacional é estudada através da simulação elétrica do circuito, utilizando-se o simulador Hspice. Uma das fontes de falhas transientes é o pulso transiente causado por partículas ionizantes que atingem o circuito. O estudo é centrado nas propriedades de mascaramento elétrico das portas lógicas. Estuda-se a propagação do pulso transiente através de cada estágio da lógica até que alcance um elemento da memória. A partir do estudo das propriedades de mascaramento elétrico, propõe-se um modelo simples para a degradação e ampliação de um pulso transiente enquanto este é propagado através de uma cadeia de portas lógicas. O modelo considera as propriedades elétricas das portas, utilizando como parâmetro principal da modelagem o tempo de propagação (atraso) da porta lógica. O modelo é computacionalmente eficiente e adequado para implementação em ferramentas de auxilio de projeto automatizadas, como ferramentas de timing analysis. A ferramenta timing analysis poderia então executar um algoritmo para percorrer todos os nós de um circuito, determinando os nós mais sensíveis, ajudando a estimar e reduzir a taxa de falhas transientes do circuito. Visando no futuro...

Detecting transient faults in the configurable reconfigurable core architecture without false error signals

Ferreira, Luigi Vaz
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
ENG
Relevância na Pesquisa
36.37%
Fault tolerance is an important issue to worry about in the computing world. The detection of errors provided by transient faults, among others source of errors, in a determined region of a computer architecture is necessary to increase the reliability of the architecture. Circuit level time-redundancy (NICOLAIDIS, 1999) is a good technique to detect transient errors (those caused by transient faults) with low impact in area in a first moment. This work presents two implementations of the technique and the conditions we must respect in order to maximize the error detection without generating false errors signals. In addition, these implementations are used to construct the component that is part of a flexible error handling module (FEHM) (SCHWEIZER et al., 2012). This module is incorporated in the Configurable Reconfigurable Core (OPPOLD et al., 2007) architecture in order to detect and mask errors caused by permanent and transient faults. As a result, the simulations confirm that the conditions formulated avoids the false errors signals generation. However, the synthesis results shows that the technique can impact, not only in the area, but also in the performance of the circuit. Furthermore, fault injection simulations show that the FEHM has a vulnerability in the presence of transient faults.; Tolerância a falhas é uma questão importante a se preocupar no mundo da computação. A detecção de erros providos de falhas transientes...

Transient non-Darcy forced convective heat transfer from a flat plate embedded in a fluid-saturated porous medium

Nakayama, A.; Ebinuma, C. D.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 249-253
ENG
Relevância na Pesquisa
36.34%
Transient non-Darcy forced convection on a flat plate embedded in a porous medium is investigated using the Forchheimer-extended Darcy law. A sudden uniform pressure gradient is applied along the flat plate, and at the same time, its wall temperature is suddenly raised to a high temperature. Both the momentum and energy equations are solved by retaining the unsteady terms. An exact velocity solution is obtained and substituted into the energy equation, which then is solved by means of a quasi-similarity transformation. The temperature field can be divided into the one-dimensional transient (downstream) region and the quasi-steady-state (upstream) region. Thus the transient local heat transfer coefficient can be described by connecting the quasi-steady-state solution and the one-dimensional transient solution. The non-Darcy porous inertia works to decrease the velocity level and the time required for reaching the steady-state velocity level. The porous-medium inertia delays covering of the plate by the steady-state thermal boundary layer. © 1990.

Transient stability indices from a hybrid approach

Padilha, A.; Denis, E. F.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 474-478
ENG
Relevância na Pesquisa
36.34%
This paper deals with hybrid method for transient stability analysis combining time domain simulation and a direct method. Nowadays, the step-by-step simulation is the best available tool for allowing the uses of detailed models and for providing reliable results. The main limitation of this approach involves the large time of computational simulations and the absence of stability margin. On the other hand, direct methods, that demand less CPU time, did not show ample reliability and applicability yet. The best way seems to be using hybrid solutions, in which a direct method is incorporated in a time domain simulation tool. This work has studied a direct method using the transient potential and kinetic energy of the critical machine only. In this paper the critical machine is identified by a fast and efficient method, and the proposal is new for using to get stability margins from hybrid approaches. Results from systems, like 16-machine, show stability indices to dynamic security assessment. © 2001 IEEE.

Transient transpiration radiometer : development of a heat flux sensor for high aggressivity environments; Radiómetro por transpiração transitória : desenvolvimento de um sensor de fluxo de calor para ambientes de elevada agressividade

Calisto, Hugo Miguel Filipe
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
POR
Relevância na Pesquisa
36.29%
The development of a new instrument for the measurement of convective and radiative is proposed, based on the transient operation of a transpiration radiometer. Current transpiration radiometers rely on steady state temperature measurements in a porous element crossed by a know gas mass flow. As a consequence of the porous sensing element’s intrinsically high thermal inertia, the instrument’s time constant is in the order of several seconds. The proposed instrument preserves established advantages of transpiration radiometers while incorporating additional features that broaden its applicability range. The most important developments are a significant reduction of the instrument’s response time and the possibility of separating and measuring the convective and radiative components of the heat flux. These objectives are achieved through the analysis of the instrument’s transient response, a pulsed gas flow being used to induce the transient behavior.; Propõe-se o desenvolvimento de um novo instrumento para medição de fluxos de calor convectivos e radiativos, baseado na operação de um radiómetro de transpiração em regime transitório. Os radiómetros de transpiração atuais baseiam-se em medições de temperatura em regime estacionário num elemento poroso atravessado por um caudal mássico gasoso conhecido. Como consequência da inércia térmica intrinsecamente elevada do elemento sensível poroso...

Transient forced convection in an isothermal fluid-saturated porous medium layer: effective permeability and boundary layer thickness

Miguel, A. F.; Reis, A
Fonte: Begell House Publicador: Begell House
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.29%
Transient forced convection in an isothermal saturated porous-medium layer is analyzed analytically on the basis of the Forchheimer-Brinkman-extended Darcy equation. An analytical solution describing the transient regime is obtained by considering the ensemble average velocity of the fluid flow as much larger than the fluctuations in the fluid velocity. This solution provides a better knowledge of the features of the flow within the porous layer. Among other results is presented an expression for the effective porous-medium permeability, as a function of the Darcy number, of the Reynolds number, and of a "relaxation time" characteristic of the transient regime. The solution found also indicates that an appropriate periodic forcing of the pressure gradient may increase the effective permeability of the porous layer to fluid flow.

Differential equations important in the M|G|∞ queue system transient behavior and busy period study

Ferreira, Manuel Alberto M.
Fonte: Slovak University of Technology Publicador: Slovak University of Technology
Tipo: Conferência ou Objeto de Conferência
Publicado em //2005 ENG
Relevância na Pesquisa
36.29%
This paper main subject is the M|G|∞ queue system populational process transient probabilities study as time functions. We achieve it completely when the time origin is an unoccupied system instant. But we do not get such a goal when the time origin is a busy period beginning instant. We shall see that, in this last situation, the service time length distribution hazard rate function plays a very important role. And so the results got may be useful in the survival analysis field. As the M|G|∞ queue can be applied in the modelation of many social problems: sickness, unemployment, emigration, ...(see, for instance, Ferreira (1995, 1996, 2003a and 2003b)), in these situations it is very important to study the busy period length distribution of that system. We show, in this work, that the solution of the problem may be in the resolution of a Ricatti equation generalizing the work of Ferreira (1998 and 2003) as a consequence of the transient behaviour study. We put also a special incidence in the study of the mean and the variance of the transient probabilities when the time origin is a busy period beginning instant, as time function. It allows the consideration of very interesting linear differential equations.

Clinical significance of transient left ventricular dilation assessed during myocardial Tc-99m sestamibi scintigraphy

Duarte,Paulo Schiavom; Smanio,Paola Emanuela; Oliveira,Carlos Alberto; Martins,Luiz Roberto; Mastrocolla,Luiz Eduardo; Pereira,Julio César
Fonte: Sociedade Brasileira de Cardiologia - SBC Publicador: Sociedade Brasileira de Cardiologia - SBC
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2003 EN
Relevância na Pesquisa
36.46%
OBJECTIVE: To assess the clinical significance of transient ischemic dilation of the left ventricle during myocardial perfusion scintigraphy with stress/rest sestamibi. METHODS: The study retrospectively analyzed 378 patients who underwent myocardial perfusion scintigraphy with stress/rest sestamibi, 340 of whom had a low probability of having ischemia and 38 had significant transient defects. Transient ischemic dilation was automatically calculated using Autoquant software. Sensitivity, specificity, and the positive and negative predictive values were established for each value of transient ischemic dilation. RESULTS: The values of transient ischemic dilation for the groups of low probability and significant transient defects were, respectively, 1.01 ± 0.13 and 1.18 ± 0.17. The values of transient ischemic dilation for the group with significant transient defects were significantly greater than those obtained for the group with a low probability (P<0.001). The greatest positive predictive values, around 50%, were obtained for the values of transient ischemic dilation above 1.25. CONCLUSION: The results suggest that transient ischemic dilation assessed using the stress/rest sestamibi protocol may be useful to separate patients with extensive myocardial ischemia from those without ischemia.

Transient wave propagation phenomena at visco-elastic half-spaces under distributed surface loadings

Mesquita,E; Antes,H; Thomazo,LH; Adolph,M
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 EN
Relevância na Pesquisa
36.45%
This article analyzes the transient wave propagation phenomena that take place at 2D viscoelastic half-spaces subjected to spatially distributed surface loadings and to distinct temporal excitations. It starts with a fairly detailed review of the existing strategies to describe transient analysis for elastic and viscoelastic continua by means of the Boundary Element Method (BEM). The review explores the possibilities and limitations of the existing transient BEM procedures to describe dynamic analysis of unbounded viscoelastic domains. It proceeds to explain the strategy used by the authors of this article to synthesize numerically fundamental solutions or auxiliary states that allow an accurate analysis of transient wave propagation phenomena at the surface of viscoelastic half-spaces. In particular, segments with spatially constant and linear stress distributions over a halfspace surface are considered. The solution for the superposition of constant and discontinuous adjacent elements as well as linear and continuous stress distributions is addressed. The in uence of the temporal excitation type and duration on the transient response is investigated. The present study is based on the numerical solution of stress boundary value problems of (visco)elastodynamics. In a first stage...

Determination of the rheological properties of thin plate under transient vibration

Skočilas,Jan; Skočilasová,Blanka; Soukup,Josef
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
36.29%
The article deals with systematic analysis of the transient vibration of rectangular viscoelastic orthotropic thin 2D plate. The analysis is focused on specific deformation models of plate and for specific linear models of rheological properties. The viscoelastic isotropic and anisotropic (orthotropic) materials were investigated. The plate is loaded by general transient impulse. The time and coordinate dependencies of the fundamental quantities - displacements, rotations, stress and deformations in arbitrary points of plate under transient vibration, e. g. the analysis of stress and deformation waves in plates were investigated. The selected models are defined by constitutive equations for stress and deformation dependence. The isotropic and orthotropic model is considered. The analysis results depend on quality of the determined mechanical properties of the materials. The standard methods commonly used are time-consuming and not accurate enough. The new methodology of determining the material parameters directly from investigated plate is proposed and proven.

AGROBEST: an efficient Agrobacterium-mediated transient expression method for versatile gene function analyses in Arabidopsis seedlings

Wu, Hung-Yi; Liu, Kun-Hsiang; Wang, Yi-Chieh; Wu, Jing-Fen; Chiu, Wan-Ling; Chen, Chao-Ying; Wu, Shu-Hsing; Sheen, Jen; Lai, Erh-Min
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.43%
Background: Transient gene expression via Agrobacterium-mediated DNA transfer offers a simple and fast method to analyze transgene functions. Although Arabidopsis is the most-studied model plant with powerful genetic and genomic resources, achieving highly efficient and consistent transient expression for gene function analysis in Arabidopsis remains challenging. Results: We developed a highly efficient and robust Agrobacterium-mediated transient expression system, named AGROBEST (Agrobacterium-mediated enhanced seedling transformation), which achieves versatile analysis of diverse gene functions in intact Arabidopsis seedlings. Using β-glucuronidase (GUS) as a reporter for Agrobacterium-mediated transformation assay, we show that the use of a specific disarmed Agrobacterium strain with vir gene pre-induction resulted in homogenous GUS staining in cotyledons of young Arabidopsis seedlings. Optimization with AB salts in plant culture medium buffered with acidic pH 5.5 during Agrobacterium infection greatly enhanced the transient expression levels, which were significantly higher than with two existing methods. Importantly, the optimized method conferred 100% infected seedlings with highly increased transient expression in shoots and also transformation events in roots of ~70% infected seedlings in both the immune receptor mutant efr-1 and wild-type Col-0 seedlings. Finally...

Thermal-hydraulic transient analysis of a packed particle bed reactor fuel element; Title as it appears in the M.I.T. Graduate List, Jun. 4, 1990: Transient thermal-hydraulic analysis of a packed particle bed reactor fuel element

Casey, William Emerson
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Tese de Doutorado Formato: 146 leaves: ill. 28 cm.
EN_US
Relevância na Pesquisa
36.34%
Title as it appears in the M.I.T. Graduate List, Jun. 4, 1990: Transient thermal-hydraulic analysis of a packed particle bed reactor fuel element; A model which describes the thermal-hydraulic behavior of a packed particle bed reactor fuel element is developed and compared to a reference standard. The model represents a step toward a thermal-hydraulic module for a real-time, autonomous reactor powder controller. The general configuration of the fuel element is a bed of small (diameter about 500 microns) fuel particles are packed between concentrically mounted retention cylinders referred to as frits. The momentum integral approach used in the MINET code is applied ot this model to balance the fundamental mass, energy and momentum conservation relationships. The element is divided into only three control volumes: the inlet plenum and cold frit define the first control volume, the fuel particle bed defines a second control volume, and the outlet plenum and hot frit define the third control volume. The solid phase of the particle bed is represented by a single node. This simple model was validated against the reference standard and compared favorably. As a demonstration of the model's flexibility, a number of variations were analyzed. These included variations in fuel element geometry and the initial and final values of inlet temperature...

Is the measurement of inferior thyroid artery blood flow velocity by color-flow Doppler ultrasonography useful for differential diagnosis between gestational transient thyrotoxicosis and Graves' disease? A prospective study

Zuhur,Sayid Shafi; Özel,Alper; Velet,Selvinaz; Buğdacı,Mehmet Sait; Çil,Esra; Altuntas,Yüksel
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
36.37%
OBJECTIVE: To determine the role of peak systolic velocity, end-diastolic velocity and resistance indices of both the right and left inferior thyroid arteries measured by color-flow Doppler ultrasonography for a differential diagnosis between gestational transient thyrotoxicosis and Graves' disease during pregnancy. METHODS: The right and left inferior thyroid artery-peak systolic velocity, end-diastolic velocity and resistance indices of 96 patients with thyrotoxicosis (41 with gestational transient thyrotoxicosis, 31 age-matched pregnant patients with Graves' disease and 24 age- and sex-matched non-pregnant patients with Graves' disease) and 25 ageand sex-matched healthy euthyroid subjects were assessed with color-flow Doppler ultrasonography. RESULTS: The right and left inferior thyroid artery-peak systolic and end-diastolic velocities in patients with gestational transient thyrotoxicosis were found to be significantly lower than those of pregnant patients with Graves' disease and higher than those of healthy euthyroid subjects. However, the right and left inferior thyroid artery peak systolic and end-diastolic velocities in pregnant patients with Graves' disease were significantly lower than those of non-pregnant patients with Graves' disease. The right and left inferior thyroid artery peak systolic and end-diastolic velocities were positively correlated with TSH-receptor antibody levels. We found an overlap between the inferior thyroid artery-blood flow velocities in a considerable number of patients with gestational transient thyrotoxicosis and pregnant patients with Graves' disease. CONCLUSIONS: This study suggests that the measurement of inferior thyroid artery-blood flow velocities with colorflow Doppler ultrasonography does not have sufficient sensitivity and specificity to be recommended as an initial diagnostic test for a differential diagnosis between gestational transient thyrotoxicosis and Graves' disease during pregnancy.

Strategies for improving production levels of HIV-1 VLPs by transient transfection of HEK 293 suspension cultures

Cervera Garcia, Laura
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2015 ENG
Relevância na Pesquisa
36.34%
Les partícules similars a virus (VLP) ofereixen un gran potencial com a candidates per a la nova producció de vacunes. En aquest treball es presenta el desenvolupament i l'optimització d'un protocol de producció de VLP de Gag d'VIH-1 mitjançant l'expressió gènica transitòria en cultius de cèl·lules HEK 293 en suspensió. La transfecció transitòria permet una generació ràpida de proteïnes recombinants en quantitat i qualitat suficient per realitzar assajos preclínics, i és particularment interessant en les fases primerenques del desenvolupament. Aquest treball es divideix en quatre capítols principals. Al primer capítol, el medi comercial lliure de sèrum Freestyle 293 s'optimitza mitjançant l'ús de components d'origen no animal. L'ús de medis químicament definits i sense components derivats d'animals és un requisit bàsic per una vacuna destinada als éssers humans. La densitat cel·lular màxima assolida utilitzant el medi de cultiu optimitzat (suplementat amb 0,9X de mescla de lípids, 19,8 mg/L d'insulina recombinant i 1,6 mg/L de transferrina recombinant) és 5,4×106 cèl·lules/ml en discontinu, gairebé el doble del que s'assoleix utilitzant el medi sense suplementar (2.9×106 cèl·lules / ml). A més a més...

Is the measurement of inferior thyroid artery blood flow velocity by color-flow Doppler ultrasonography useful for differential diagnosis between gestational transient thyrotoxicosis and Graves' disease? A prospective study

Zuhur, Sayid Shafi; Özel, Alper; Velet, Selvinaz; Buğdacı, Mehmet Sait; Çil, Esra; Altuntas, Yüksel
Fonte: Universidade de São Paulo. Faculdade de Medicina Publicador: Universidade de São Paulo. Faculdade de Medicina
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 01/01/2012 ENG
Relevância na Pesquisa
36.37%
OBJECTIVE: To determine the role of peak systolic velocity, end-diastolic velocity and resistance indices of both the right and left inferior thyroid arteries measured by color-flow Doppler ultrasonography for a differential diagnosis between gestational transient thyrotoxicosis and Graves' disease during pregnancy. METHODS: The right and left inferior thyroid artery-peak systolic velocity, end-diastolic velocity and resistance indices of 96 patients with thyrotoxicosis (41 with gestational transient thyrotoxicosis, 31 age-matched pregnant patients with Graves' disease and 24 age- and sex-matched non-pregnant patients with Graves' disease) and 25 ageand sex-matched healthy euthyroid subjects were assessed with color-flow Doppler ultrasonography. RESULTS: The right and left inferior thyroid artery-peak systolic and end-diastolic velocities in patients with gestational transient thyrotoxicosis were found to be significantly lower than those of pregnant patients with Graves' disease and higher than those of healthy euthyroid subjects. However, the right and left inferior thyroid artery peak systolic and end-diastolic velocities in pregnant patients with Graves' disease were significantly lower than those of non-pregnant patients with Graves' disease. The right and left inferior thyroid artery peak systolic and end-diastolic velocities were positively correlated with TSH-receptor antibody levels. We found an overlap between the inferior thyroid artery-blood flow velocities in a considerable number of patients with gestational transient thyrotoxicosis and pregnant patients with Graves' disease. CONCLUSIONS: This study suggests that the measurement of inferior thyroid artery-blood flow velocities with colorflow Doppler ultrasonography does not have sufficient sensitivity and specificity to be recommended as an initial diagnostic test for a differential diagnosis between gestational transient thyrotoxicosis and Graves' disease during pregnancy.

Scanning Ion Deep Level Transient Spectroscopy: I. Theory

Laird, J S; Jagadish, Chennupati; Jamieson, David Norman; Legge, G J F
Fonte: Institute of Physics Publishing Publicador: Institute of Physics Publishing
Tipo: Artigo de Revista Científica
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Theoretical aspects of a new technique for the MeV ion microbeam are described in detail for the first time. The basis of the technique, termed scanning ion deep level transient spectroscopy (SIDLTS), is the imaging of defect distributions within semiconductor devices. The principles of SIDLTS are similar to those behind other deep level transient spectroscopy (DLTS) techniques with the main difference stemming from the injection of carriers into traps using the localized energy-loss of a focused MeV ion beam. Energy-loss of an MeV ion generates an electron-hole pair plasma, providing the equivalent of a DLTS trap filling pulse with a duration which depends on space-charge screening of the applied electric field and ambipolar erosion of the plasma for short ranging ions. Some nanoseconds later, the detrapping current transient is monitored as a charge transient. Scanning the beam in conjunction with transient analysis allows the imaging of defect levels. As with DLTS, the temperature dependence of the transient can be used to extract trap activation levels. In this, the first of a two-part paper, we introduce the various stages of corner capture and derive a simple expression for the observed charge transient. The second paper will illustrate the technique on a MeV ion implanted Au-Si Schottky junction.