The thesis deals with design and implementation of controllers for the RMAP protocol, which is used by SpaceWire network endpoints to access memory contents of another endpoint. The theoretical research introduces concepts of the SpaceWire network, then describes the RMAP protocol and the AMBA AHB bus interface in detail. The practical part of this thesis then uses this information to design and implement controllers for the RMAP protocol. It first defines an architecture of these controllers, then describes design of individual blocks based on this architecture. As a next step, the thesis describes methods used to verify designed controllers and to test these controllers in an FPGA chip. Finally, an analysis of maximum frequency and usage of FPGA resources is done based on estimates provided by the synthesis tool.

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Made available in DSpace on 2017-07-10T14:57:32Z (GMT). No. of bitstreams: 1 HELOUISE_ RIGHI.pdf: 781690 bytes, checksum: e73794e76d42164775e107e6f2160613 (MD5) Previous issue date: 2016-03-02 / With the ample craving for teeth whitening, it is fundamental the production of increasingly clearer materials and also a good color stability, before the possible degradation which are exposed. The camphorquinone (CQ) is the photo initiator most widely applied on the dental composite, but it has the yellow coloration and suffers darkening when exposed to ultraviolet light (UV), endangering the maintenance of the esthetics harmony. The goal of this study was to evaluate in vitro the effect of the photo initiator Phenylpropanodione, singly or in association with the CQ, about the color stability of the resinous photoactive cement and its bond adhesive resistence, by microshear. The null hypotheses are: i) the photo initiator PPD does not interfere with the color changing of the resin cement, after the photoaging motivated by prolonged exposure to UV light; and ii) the photo initiator PPD does not interfere with the resistance of the adhesive bond of resin cement to the ceramic. Four resinous cements where used, which one of them was commercial (RelyX Venner, 3M/ESPE) and three experimental, differing each other's photo initiator's concentration. For the color analysis, ceramic discs were cemented above the bovine dentine, simulating the indirect restorations (n=8), being exposed to 120 h of UV, and tested about the color alterations which were measured applying the CIELab scale, by spectrophotometer of reflectance. The obtained datas were verified about the normal distribution, for then being submited to ANOVA and to the complementary test Tukey, all with 5% significance. The results of color analysis do not statistically significant difference to E of 4 cements studied neither to L , a and b . For the Union of Resistance of all cements studied showed statistically significant differences among themselves, with the highest for commercial cement RelyX Venner® (29.07 MPa), followed by cement with CQ (21.74 MPa) , and cement CQ + PPD (19.09 MPa); and the lowest result was obtained with the cement using only the PPD as photoinitiator (13.99 MPa) . Therefore to the parameters studied in this work, the PDD was not advantageous as photoinitiator resin cements, because made low bond strength value ceramics and not demonstrated superiority as for color stability . / Com o amplo anseio pelo branqueamento dental, é fundamental a produção de materiais cada vez mais claros e que também possuam boa estabilidade de cor, ante às possiveis degradações a que ficam expostos. A Canforoquinona (CQ) é o fotoiniciador mais amplamente empregado nos compósitos odontológicos, porém tem coloração amarelada e sofre escurecimento ao ser exposta à luz ultra violeta (UV), comprometendo a manutenção da harmonia estética. O objetivo deste estudo foi avaliar in vitro o efeito do fotoiniciador Phenilpropanodiona (PPD), isoladamente ou em associação com a CQ, sobre a estabilidade de cor de cimentos resinosos fotoativados, e sua resistência de união adesiva à cerâmica, por teste de microcisalhamento. As hipóteses nulas testadas são: i) o fotoiniciador PPD não interfere na alteração de cor de cimentos resinosos, após o foto envelhecimento provocado por exposição prolongada a luz UV; e ii) o fotoiniciador PPD não interfere na resistência da união adesiva de cimentos resinosos à cerâmica. Foram utilizados 4 cimentos resinosos, sendo um comercial (RelyX Venner®) e 3 experimentais, diferindo entre si quanto ao tipo e concentração dos fotoiniciadores. Para a análise de cor, foram cimentados discos cerâmicos sobre dentina bovina, simulando restaurações indiretas (n=8), sendo expostos a 120 h de UV, e testados quanto às alterações de cor, que foram mensuradas empregando a escala CIELab, por meio de espectrofotômetro de reflectância. Os dados obtidos foram verificados quanto a distribuição normal, para então serem submetidos a ANOVA e ao teste complementar Tukey, todos com significância de 5%. Os resultados do teste de cor não apresentam diferença estatisticamente significante para o E dos 4 cimentos estudados, nem tampouco para L, a e b. Para a resistência de união, todos os cimentos estudados apresentaram diferenças estatisticamente significantes entre si, com o maior resultado para o cimento comercial RelyX Venner® (29,07 Mpa), seguido pelo cimento com CQ (21,74 Mpa), e então pelo cimento de CQ+PPD (19,09 Mpa); e o menor resultado foi obtido com o cimento utilizando apenas o PPD como fotoiniciador (13,99 Mpa). Portanto, para os parâmetros estudados neste trabalho, o PDD não se mostrou vantajoso como fotoiniciador de cimentos resinosos, já que apresentou baixo valor de resistência de união à cerâmica e não demonstrou superioridade quanto à estabilidade de cor.

Antibiotic resistance is a growing problem on a global scale. Increasing numbers of bacteria resistant toward one or multiple antibiotics could return us to the high mortality rates for infectious diseases of the pre-antibiotic era. The need for development of new classes of antibiotics is great as is increased understanding of the mechanisms underlying the development of antibiotic resistance. We have investigated the emergence of resistance to peptide deformylase inhibitors, a new class of antibiotics that target bacterial protein synthesis. The fitness of resistant mutants as well as their propensity to acquire secondary compensatory mutations was assessed in order to gain some insight into the potential clinical risk of resistance development. Most of this work was done in the bacterium Salmonella typhimurium, due to the availability of excellent genetic tools to study these phenomena. In addition, we have studied the bacterium Staphylococcus aureus as peptide deformylase inhibitors have been shown to have the greatest effect on Gram-positive organisms. In the course of this work we also examined the mechanistic aspects of translation initiation. Using a cell-free in vitro translation system we studied the effects of various components on translation initiation. These results have been combined with results obtained from resistant and compensated bacterial strains in vivo to gain new insights into the mechanisms of translation initiation.

An experimental and modelling investigation of a tetrafunctional initiator designed for free radical polymerizations is presented. Multifunctional initiators are believed to provide two advantages over traditional monofunctional initiators. With a higher number of functional sites per molecule, they are able to increase polymer production while simultaneously maintaining or increasing polymer molecular weight. Examination of the literature indicates the majority of academic and industrial published studies have investigated difunctional initiators with most focusing on styrene. In this thesis, a tetrafunctional initiator, JWEB50, was systematically investigated for a variety of monomer systems in order to develop a better understanding of the behaviour of multifunctional initiators in free radical polymerizations. <br /><br /> A kinetic study comparing the tetrafunctional initiator to a monofunctional counterpart, TBEC, demonstrated that the impact of a multifunctional initiator is dependent upon monomer type. Regardless of the homo- or copolymer system examined, it was observed that the tetrafunctional initiator could produce higher rates of polymerization due to the greater number of labile groups per initiator molecule. However, the influence of the tetrafunctional initiator on the polymer molecular weight was dictated by the polymerization characteristics of the system in question. In the case of styrene, the tetrafunctional initiator maintained similar molecular weights compared to the monofunctional initiator while for methyl methacrylate (MMA), switching from a mono- to a tetrafunctional initiator actually decreased the polymer molecular weight. Other monomers such as butyl acrylate and vinyl acetate and copolymers of MMA and styrene or alpha-methyl styrene were examined to study the effect of initiator functionality in free radical polymerizations. <br /><br /> Subsequent to the kinetic investigation, polystyrene and poly(methyl methacrylate) samples produced with the tetrafunctional initiator were characterized in detail in order to examine the effects of initiator functionality on polymer properties. Samples generated with the monofunctional initiator were used for comparison purposes. Chromatographic and dilute solution methods were able to detect significant levels of branching in the polystyrene sample produced with JWEB50, while poly(methyl methacrylate) samples showed no evidence of branching. Rheological tests involving a combination of oscillatory and creep shear measurements were completed in order to detect differences between samples. The presence of branching using rheological techniques was clearly observed for both polystyrene and poly(methyl methacrylate) samples produced with the tetrafunctional initiator. <br /><br /> In order to explain the experimental results observed in the kinetic and polymer properties studies, a reaction mechanism for polymerizations initiated with a tetrafunctional initiator was proposed and used in the development of a mathematical model. Reactions involving the fate/efficiency of functional groups are properly accounted for, while in the past this had been ignored by modelling work in the literature. Based on model predictions, di-radical concentrations were estimated to be several orders of magnitude smaller than mono-radical concentrations and their contribution in the reaction mechanism was found to be negligible. Modelling results also demonstrated that the concentration and chain length of various polymer structures (i. e. , linear, star or coupled stars) depend upon monomer type and reaction conditions.

An experimental and modelling investigation of a tetrafunctional initiator designed for free radical polymerizations is presented. Multifunctional initiators are believed to provide two advantages over traditional monofunctional initiators. With a higher number of functional sites per molecule, they are able to increase polymer production while simultaneously maintaining or increasing polymer molecular weight. Examination of the literature indicates the majority of academic and industrial published studies have investigated difunctional initiators with most focusing on styrene. In this thesis, a tetrafunctional initiator, JWEB50, was systematically investigated for a variety of monomer systems in order to develop a better understanding of the behaviour of multifunctional initiators in free radical polymerizations. <br /><br /> A kinetic study comparing the tetrafunctional initiator to a monofunctional counterpart, TBEC, demonstrated that the impact of a multifunctional initiator is dependent upon monomer type. Regardless of the homo- or copolymer system examined, it was observed that the tetrafunctional initiator could produce higher rates of polymerization due to the greater number of labile groups per initiator molecule. However, the influence of the tetrafunctional initiator on the polymer molecular weight was dictated by the polymerization characteristics of the system in question. In the case of styrene, the tetrafunctional initiator maintained similar molecular weights compared to the monofunctional initiator while for methyl methacrylate (MMA), switching from a mono- to a tetrafunctional initiator actually decreased the polymer molecular weight. Other monomers such as butyl acrylate and vinyl acetate and copolymers of MMA and styrene or alpha-methyl styrene were examined to study the effect of initiator functionality in free radical polymerizations. <br /><br /> Subsequent to the kinetic investigation, polystyrene and poly(methyl methacrylate) samples produced with the tetrafunctional initiator were characterized in detail in order to examine the effects of initiator functionality on polymer properties. Samples generated with the monofunctional initiator were used for comparison purposes. Chromatographic and dilute solution methods were able to detect significant levels of branching in the polystyrene sample produced with JWEB50, while poly(methyl methacrylate) samples showed no evidence of branching. Rheological tests involving a combination of oscillatory and creep shear measurements were completed in order to detect differences between samples. The presence of branching using rheological techniques was clearly observed for both polystyrene and poly(methyl methacrylate) samples produced with the tetrafunctional initiator. <br /><br /> In order to explain the experimental results observed in the kinetic and polymer properties studies, a reaction mechanism for polymerizations initiated with a tetrafunctional initiator was proposed and used in the development of a mathematical model. Reactions involving the fate/efficiency of functional groups are properly accounted for, while in the past this had been ignored by modelling work in the literature. Based on model predictions, di-radical concentrations were estimated to be several orders of magnitude smaller than mono-radical concentrations and their contribution in the reaction mechanism was found to be negligible. Modelling results also demonstrated that the concentration and chain length of various polymer structures (i. e. , linear, star or coupled stars) depend upon monomer type and reaction conditions.

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 45-48).

The work discussed in this thesis deals with the significance of initiator tRNA gene copy number in Escherichia coli. A summary of the relevant literature discussing the process of protein synthesis, initiator tRNA selection and gene redundancy is presented in Chapter 1. Chapter 2 describes the ‘Materials and Methods’ used in the experimental work carried out in this thesis. The next three chapters address the significance of initiator tRNA gene copy number in E. coli at three levels; at the level of the molecule (Chapter 3), at the level of the cell (Chapter 4) and at the level of the population (Chapter 5). At the end of the thesis are appended three publications, which include two papers where I have contributed to work not discussed in this thesis and one review article. A brief summary of chapters 3 to 5 is provided below: (i) Chapter 3: Can E. coli remain viable without the 3 G-C base pairs in initiator tRNA? Initiator tRNAs are distinguished from elongator tRNAs by several features key among which are the three consecutive and near universally conserved G-C base pairs found in the anticodon stem of initiator tRNAs. These bases have long been believed to be essential for the functioning of a living cell, both from in vitro and in vivo analysis. In this study, using targeted mutagenesis and an in vivo genetics based approach, we have shown that the 3 G-C base pairs can be dispensed with in E. coli, and the cell can be sustained on unconventional initiator tRNAs lacking the intact 3 G-C base pairs. Our study uncovered the importance of considering the relative amounts of molecules in a living cell, and their role in maintaining the fidelity of protein synthesis. (ii) Chapter 4: Can elongator tRNAs initiate protein synthesis? There are two types of tRNAs; initiator tRNA, of which there is one representative in the cell, and elongator tRNAs of which there are several representatives. In this study, we have uncovered initiation of protein synthesis by elongator tRNAs by depleting the initiator tRNA content in the cell. This raises the possibility that competition between initiator and elongator tRNAs at the P site of the ribosome occurs routinely in the living cell, and provides a basis for initiation at several 'start' sites in the genome that may not be currently annotated as such. We speculate that such a phenomenon could be exploited by the cell to generate phenotypic diversity without compromising genomic integrity. (iii) Chapter 5: How many initiator tRNA genes does E. coli need? E. coli has four genes that encode initiator tRNA, these are the metZWV genes that occur at 63.5 min in the genome, and the metY gene that occurs at 71.5 min in the genome. Earlier studies indicated that the absence of metY had no apparent impact on cell growth. In view of the importance of initiator tRNA gene copy number in maintaining the rate and fidelity of protein synthesis, we examined the fitness of strains carrying different numbers of initiator tRNA genes by competing them against each other in both rich and limited nutrient environments. Our results indicate a link between caloric restriction and protein synthesis mediated by the initiator tRNA gene copy number.

The diploma thesis deals with the influence of technological parameters on the emulsion copolymerization of methyl methacrylate with n butyl acrylate. The theoretical part contains knowledge in the field of influences of proces tempereture, concentration of initiator, concentration of emulsifier, stirring rate and dose rate on emulsion polymerization. In the experimental part was observed effect of the concentration of the ionic emulsifier, nonionic emulsifier, furthemore was observed effect of stirring speed and the concentration of initiator K2S2O8 on conversion of copolymerization. During all copolymerizations, conversions was determinated via solids content evaluation. By dynamic light scattering was determinated and presented polymer particle size of the prepared emulsions. Stability of emuldions was observed via effect of different ionic strenght and yield of freeze thaw cycles coalescence. Based on experimental results were proposed conditions of polyacrylic lattex preparation.

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