No description available.

Quantum dot infrared photodetectors (QDIPs) have emerged as a promising technology in the mid- and far-infrared (3-25 μm) for medical and environmental sensing that have a lot of advantages over current technologies based on Mercury Cadmium Telluride (MCT) and quantum well (QW) infrared photodetectors (QWIPs). In addition to the uniform and stable surface growth of III/V semiconductors suitable for large area focal plane applications and thermal imaging, the three dimension confinement in QDs allow sensitivity to normal incidence, high responsivity, low darkcurrent and high operating temperature. The growth, processing and characterizations of these detectors are costly and take a lot of time. So, developing theoretical models based on the physical operating principals will be so useful in characterizing and optimizing the device performance. Theoretical models based on non-equilibrium Green's functions have been developed to electrically and optically characterize different structures of QDIPs. The advantage of the model over the previous developed classical and semiclassical models is that it fairly describes quantum transport phenomenon playing a significant role in the performance of such nano-devices and considers the microscopic device structure including the shape and size of QDs, heterostructure device structure and doping density. The model calculates the density of states from which all possible energy transitions can be obtained and hence obtains the operating wavelengths for intersubband transitions. The responsivity due to intersubband transitions is calculated and the effect of having different sizes and different height-to-diameter ratio QDs can be obtained for optimization. The dark and photocurrent are calculated from the quantum transport equation provided by the model and their characteristics at different design parameter are studied. All the model results show good agreement with the available experimental results. The detectivity has been calculated from the dark and photocurrent characteristics at different design parameters. The results shows a trade off between the responsivity and detectivity and what determines the best performance is how much the rate of increase of the photocurrent and dark current is affected by changing the design parameters. Theoretical modeling developed in the thesis give good description to the QDIP different characteristics that will help in getting good estimation to their physical performance and hence allow for successful device design with optimized performance and creating new devices, thus saving both time and money. / Thesis / Doctor of Philosophy (PhD)

No description available.

No description available.

No description available.

The research study is a review of research at Virginia Tech on the relationship between school building condition and student and teacher performance and attitudes. There have been several reviews or synthesis studies of the research in the field of school facilities over the last 65 years. One institution, Virginia Tech has produced several research studies in this area of scholarly work over the past two decades. With this large corpus of research directly related to Cash's theoretical model, first used in 1993, it becomes necessary to find out what the research has shown and also to find out what these researchers have advocated for further research. The study extracted 84 findings from the 20 studies reviewed with 67% being statistically significant. Only eight of the 20 relationships in the theoretical model had related findings. Building Condition and Faculty Attitude and Building Condition and Student Achievement had the highest number of related findings. The study states that a better Building Condition has a positive relationship on higher student achievement and attitudes. The synthesis of the findings also drew seven conclusions that should be factored into future research decisions. The study also extracted 74 recommendations for further research. The three relationships that had the greatest number of related recommendations for further research were Building Condition and Student Achievement, Building Condition and Student Attitudes, and Building Condition and Faculty Attitude. The relationships that were either not investigated or were investigated by one or two research studies are the areas that need more research. The theoretical model produced several propositions for further research. The propositions follow the logical progression of the model from the decisions of the school authorities and financial ability of the school system in determining the condition of the school building to the eventual effect the school building conditions have upon student and teacher performance and attitudes. The presented taxonomy of research needs, through the propositions, serves as a guide in determining the needs for filling the gaps in the research related to Building Condition and Student and Teacher Performance and Attitude at Virginia Tech and other institutions. / Ph. D.

No / Inadequate drug delivery to tumours is now recognised as a key factor that limits the efficacy of anticancer drugs. Extravasation and penetration of therapeutic agents through avascular tissue are critically important processes if sufficient drug is to be delivered to be therapeutic. The purpose of this study is to develop an in silico model that will simulate the transport of the clinically used cytotoxic drug doxorubicin across multicell layers (MCLs) in vitro. Three cell lines were employed: DLD1 (human colon carcinoma), MCF7 (human breast carcinoma) and NCI/ADR-Res (doxorubicin resistant and P-glycoprotein [Pgp] overexpressing ovarian cell line). Cells were cultured on transwell culture inserts to various thicknesses and doxorubicin at various concentrations (100 or 50 microM) was added to the top chamber. The concentration of drug appearing in the bottom chamber was determined as a function of time by HPLC-MS/MS. The rate of drug penetration was inversely proportional to the thickness of the MCL. The rate and extent of doxorubicin penetration was no different in the presence of NCI/ADR-Res cells expressing Pgp compared to MCF7 cells. A mathematical model based upon the premise that the transport of doxorubicin across cell membrane bilayers occurs by a passive "flip-flop" mechanism of the drug between two membrane leaflets was constructed. The mathematical model treats the transwell apparatus as a series of compartments and the MCL is treated as a series of cell layers, separated by small intercellular spaces. This model demonstrates good agreement between predicted and actual drug penetration in vitro and may be applied to the prediction of drug transport in vivo, potentially becoming a useful tool in the study of optimal chemotherapy regimes.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: See full text for abstract / AFRIKAANSE OPSOMMING: Sien volteks vir opsomming

Uma das características da Administração Pública atual é a necessidade de uma atuação com mais qualidade e com foco em resultados traços do modelo teórico do gerencialismo. Ainda, segundo os preceitos da governança pública, propõe-se que a atividade da Administração Pública, voltada para a eficiência e para o cumprimento de metas, seja possível através da interação do Estado com outros atores sociais, tais como empresas e organizações da sociedade civil. Nesse contexto, merece destaque o contratualismo com as entidades privadas sem fins lucrativos para que auxiliem o Estado na consecução de seus objetivos, especialmente na realização de serviços públicos. Em um modelo colaborativo, são feitos ajustes entre a Administração Pública e essas entidades para a realização de desígnios comuns a ambos, com um incremento na eficiência e na qualidade da prestação dos serviços públicos. No Brasil, um dos tipos de acordos possíveis para se atingir essa finalidade é o contrato de gestão com as organizações sociais, regulamentado pela Lei federal n. 9.637/98. Neste tipo de ajuste, o grande destaque é a necessidade de mensuração do desempenho atingido e a sua comparação com as metas propostas, para fins de controle e de responsabilização. Contudo, na prática, há uma carência de mecanismos que possibilitem tal finalidade. Para que se torne viável a aferição de resultados neste tipo de ajuste, propõe-se o uso de indicadores de desempenho mais comumente utilizados no âmbito privado. Dentre os modelos possíveis, sugere-se a adaptação do balanced scorecard, a fim de possibilitar o controle pelo cumprimento de metas nos contratos de gestão. Por fim, há uma ilustração prática através da análise do contrato celebrado entre a Secretaria Municipal da Saúde da Prefeitura Municipal de São Paulo e a Associação Paulista para o Desenvolvimento da Medicina (SPDM), com vistas ao desenvolvimento das ações e serviços de saúde no Território Aricanduva-Sapopemba-São Mateus. / One characteristic of the current Public Administration is the need of a higher quality performance focused on results features of the managerialist theoretical model. Furthermore, in accordance with the commandments of public governance, it is proposed that the activities of the Public Administration focused on efficiency and compliancy with goals is possible by means of the interaction between the State and other social actors, such as businesses and civil society organizations. In this context, contractualism involving nonprofitable private entities deserves emphasis so that they help the State reach their goals, especially in the execution of public services. In a collaborative model, agreements are reached between the Public Administration and those entities to reach common goals increasing the efficiency and quality of public services rendering. In Brazil, one of the possible kinds of agreement to reach this goal is the management contract with social organizations regulated by Federal Law n. 9.637/98. In this kind of agreement, the greatest highlight is the need to measure the achieved performance and its comparison with the established goals for controlling and responsibility purposes. However, in practice, there is an absence of mechanisms which make such purposes possible. To enable the measurement of results in this kind of agreement, the use of performance indicators is proposed more commonly used in the private field. Among the possible models, the adaptation of the balanced scorecard is suggested in order to make the control by compliance with goals in the management contract possible. At last, there is a practical illustration based on the analysis of the contract entered into by the Municipal Office of Health of São Paulo (Secretaria Municipal da Saúde da Prefeitura Municipal de São Paulo) and the São Paulo Association for Medicine Development (SPDM Associação Paulista para o Desenvolvimento da Medicina), aiming at the development of health actions and services in the areas of Aricanduva Sapopemba São Mateus.

Um dos principais problemas das lajes-cogumelo refere-se à ruína por puncionamento da ligação laje-pilar. Esta forma de ruína deve ser evitada, proporcionando-se às lajes as melhores condições para o desenvolvimento de mecanismos de escoamento das armaduras e de ruína por flexão, antes da ocorrência da ruína por cisalhamento. A introdução de fibras de aço em elementos de concreto submetidos a solicitações tangenciais proporciona melhoria de desempenho, seja pelo aumento da capacidade resistente, seja pela alteração da forma de ruína. Pretende-se contribuir com o avanço do conhecimento sobre o assunto, explorando aspectos como a análise das similaridades dos efeitos da adição de fibras de aço na resistência e na ductilidade de lajes-cogumelo à punção, com aqueles que se observam no cisalhamento de vigas prismáticas análogas. Abordam-se os casos de ligações laje-pilar interno sem armadura de punção, variando-se a resistência do concreto, a taxa e o tipo de fibra utilizado. A partir dos resultados experimentais, verificou-se que existe uma similaridade de comportamento estrutural entre esses dois elementos e concluiu-se que é possível utilizar ensaios de cisalhamento em vigas prismáticas para se obter indicadores a serem utilizados nos ensaios de punção de lajes. Foi efetuada uma análise da adaptabilidade de modelos teóricos existentes sobre cisalhamento em vigas e punção em lajes, com vistas à consideração do efeito da adição de fibras de aço ao concreto. Com base nesses modelos, foram estabelecidos critérios quantitativos para avaliação da resistência e da ductilidade das ligações laje-pilar. / One of the main problems of flat slabs concerns the punching shear failure of the slab-column connection. This form of failure must be avoided, providing flat slabs with the best conditions for the development of yielding mechanisms of the flexural reinforcement before the occurrence of shear failure. The addition of steel fibers to concrete elements subjected to tangential stress provides performance improvement, by either the resistant capacity increase or the failure mode alteration. It is intended to contribute to the advance of the subject knowledge, by exploring aspects as the analysis of similarities of the steel fiber addition effects on both strength and ductility of flat slabs to punching shear with those observed in the shear of analogous prismatic beams. The cases approached include internal slab-column connections without shear reinforcement, and the variables investigated included concrete strength, fiber volume and type of steel fiber. From the experimental results, it was possible to verify that there exists a similarity of structural behavior between these two elements and the shear tests in prismatic beams can be used to get indicators to be utilized in punching shear tests of flat slabs. An adaptability analysis of the existing theoretical models on shear in beams and punching shear in flat slabs was carried out in order to consider the steel fibers addition effect on the concrete. Based on these models, quantitative criteria for the evaluation of both strength and ductility of the slab-column connections were established.