Objetivos: Este estudo in vivo avaliou comparativamente diferentes técnicas de clareamento de dentes polpados, quanto ao grau de mudança de cor e estabilidade do tratamento num período de doze meses, sensibilidade dentinária e o condicionamento ácido prévio ao clareamento. Métodos: Quarenta e cinco voluntários foram selecionados, de acordo com os critérios de inclusão e exclusão, e divididos aleatoriamente em 5 grupos (n=15). No clareamento em consultório, apenas na hemi-arcada direita (inferior e superior), o gel clareador foi ativado com uma fonte de luz híbrida enquanto no outro lado o gel não foi ativado, assim um mesmo voluntário participou de dois grupos. Além disso, um primeiro pré-molar superior direito ou esquerdo foi condicionado previamente ao clareamento com ácido fosfórico a 37% durante 15s. G1- Lase Peroxide (DMC Equipamentos), a base de peróxido de hidrogênio (PH) a 35% + duas ativações do gel com luz híbrida (LED e Laser de Diodo) (Whitening Lase II DMC Equipamentos) por três minutos e intervalo de 1min; em três aplicações; G2- Lase Peroxide em três aplicações de 15min e intervalos de 15mim; G3 - Opalescence Xtra Boost (Ultradent), a base de PH a 38% + duas ativações do gel com luz híbrida por três minutos e intervalo de 1min; em três aplicações; G4- Opalescence Xtra Boost em três aplicações de 15min e intervalos de 15mim; G5 - Opalescence PF (Ultradent), a base de peróxido de carbamida (PC) a 15%, 2 horas diárias por 10 dias. A avaliação da cor quantitativamente foi realizada com o espectofotômetro Vita EasyShade (Vita), antes do clareamento e após 24horas, 1 semana, 6 e 12 meses. A diferença de cor (_E) foi mensurada através do programa CIELab. A sensibilidade dentinária foi avaliada por meio do questionário VAS antes, imediatamente após o clareamento, 24 horas e uma semana. Resultados: A análise estatística não revelou nenhuma diferença estatística significante entre os grupos com e sem ativação do gel com luz híbrida. Diferença estatística foi observada entre os resultados após 24h, 1 semana e 1, 6 e 12 meses para todos os grupos experimentais. O clareamento em consultório utilizando o Lase Peroxide mostrou um aumento significante na sensibilidade quando comparado com o clareamento caseiro. O Lase Peroxida utilizado com luz híbrida e condicionamento prévio do esmalte demonstrou aumento significante da alteração de cor. Conclusão: Pode-se concluir que todas as técnicas e agentes clareadores usados são efetivos no clareamento dental. O uso de condicionamento ácido prévio ao clareamento aumenta o grau clareamento dos dentes. / Objectives: This study was evaluated color change and stability and tooth sensitivity in patients submitted to different bleaching techniques. Methods: Forty five patients were selected according to inclusion/exclusion criteria and divided in five groups (n=15). A half-mouth design was conducted to compare two in-office bleaching techniques with the same product and the effect of acid condition before treatment. G1: 35% hydrogen peroxide (HP) (Lase Peroxide, DMC Equipments) + hybrid light (LED + Diode Laser) Whitening Lase II (DMC equipments); G2: 35%HP; G3: 38%HP, X-tra Boost (Ultradent) + hybrid light; G4: 38%HP and G5: 20% Carbamide Peroxide (PC), Opalescence PF (Ultradent). For G1 and G2, PH was applied on the enamel surface for three consecutive times and activated by hybrid light during 6 min; G2 and G4, PH was applied on the enamel surface for three consecutive times during 15min and interval of 15min; G5, 15% PC for 2 hours daily during 10 days at home. The spectrophotometer VITA Easyshade (VITA) was used for color change, before the treatment and 24h, 1 week, 1, 6 and 12 months after. Color differences (_E) were assessed by means of the CIELab Program. VAS questioner was used for sensitivity tooth before the treatment and immediately, 24h and 1 week after. Results: The statistical analysis did not reveal any significant difference between activated or not by hybrid light. Statistical difference was observed between the results after 24h, 1 week and 1, 6 and 12 months, for both experimental groups. In-office bleaching with Lase Peroxide showed significant increase tooth sensitivity compared to home bleaching. Lase Peroxide with hybrid light and acid condition showed a significant increase in color change. Conclusion: It could be concluded that all the techniques and bleaching agents used are effective for dental bleaching. The use of acid condition before bleaching increase color chance.

This thesis argues that the concept of spatial proximity offers a viable and practical option for the development of context-aware systems for highly mobile and dynamic environments. Such systems would overcome the shortcomings experienced by today’s location-based and infrastructure dependent systems whose ability to deliver context-awareness is prescribed by their infrastructure. The proposed architecture will also allow for scalable interaction as against the single level of interaction in existing systems which limits services to a particular sized area. The thesis examines the concept of spatial proximity and demonstrates how this concept can be exploited to take advantage of technological convergence to offer mobility and scalability to systems. It discusses the design of a proximity-based system that can deliver scalable context-aware services in highly mobile and dynamic environments. It explores the practical application of this novel design in a proximity-sensitive messaging application by creating a proof-of-concept prototype. The proof-of-concept prototype is used to evaluate the design as well as to elicit user views and expectations about a proximity-based approach. Together these provide a valuable insight into the applicability of the proximity-based approach for designing context-aware systems. The design and development work discussed in the thesis presents a Proximity-Sensitive System Architecture that can be adapted for a variety of proximity-sensitive services. This is illustrated by means of examples, including a variety of context-aware messaging applications. The thesis also raises issues for information delivery, resource sharing, and human-computer interaction. While the technological solution (proximity-based messaging) offered is only one among several that can be developed using this architecture, it offers the opportunity to stimulate ideas in the relatively new field of proximity and technological convergence research, and contributes to a better understanding of their potential role in offering context-aware services.

Temperature-sensitivity (TS) is often used as a way to attenuate microorganisms to convert them into live vaccines. Studies indicate that live vaccines are often necessary for the complete clearance of certain pathogenic organisms. In this work we explore the use of TS genetic circuits that express lethal genes for their potential utility as a widely applicable approach to TS attenuation. Here, we use restriction endonucleases as the lethal gene products. We tested different combinations of TS repressors and cognate promoters controlling the expression of genes encoding restriction endonucleases inserted at four different non-essential sites in the Escherichia coli chromosome. We found that the presence of the restriction endonuclease genes did not affect the viability of the host strains at the permissive temperature, but that expression of the genes at elevated temperatures killed the strains to varying extents. The location of the genetic circuit cassette in the chromosome was critical, and insertion at the ycgH site led to minimal cell death. Induction of the TS circuit in a growing culture led to a pre-mature leveling off of the optical density, and a shift in the number of cells that could exclude a dye that indicated cell viability. Incubation of cells initially grown at low temperature and then suspended in phosphate buffered saline at high temperature, led to about 100-fold loss of cell viability per day compared to minimal loss of viability for the parental strain. The Dual strain containing two different genetic circuits was found to have reduced escape frequency compared to single circuit strains. However, strains carrying either one or two TS lethal circuits could generate mutants that survived high temperature. These mutants included start codon deletions as well as upstream deletions of the TetRD1 encoding gene as well as complete deletions of the lethal gene circuits. / Graduate

Magister Scientiae - MSc / South Africa

Thorough understanding of interfaces requires an assessment of both the surface and bulk properties through the use of multiple techniques. In this thesis, infrared absorption, Raman scattering and sum frequency generation were used as vibrational probes of different features of interfacial systems including the ability to measure surface and bulk effects. Two-dimension correlation analysis was used to study the relationship between the spectral response of the different techniques. Attenuated total reflection absorption, bulk Raman scattering and sum frequency generation were used to study the adsorption of ethanol--water mixture on fused silica. With the use of two-dimension correlation analysis, interesting results were observed concerning the behavior of the surface in respect to the bulk. Surface concentration of ethanol were concluded to be higher than in the bulk indicative of competitive adsorption. Furthermore, at low concentration ethanol was shown to adsorb to the surface in dimers, to then form a bilayer of strongly oriented ethanol molecules at higher concentration. At highest concentration, this bilayer is disturbed, leaving only one layer at the surface of oriented ethanol molecules. The same spectroscopic techniques were applied to pressure sensitive adhesives of different composition while drying on a sapphire surface. The presence or absence of acrylic acid in the material was shown to alter the reorientation at the surface while drying. In the case where no acrylic acid is present, the orientation of the polymer at the surface was driven by the packing of the molecules at the surface. When acrylic acid was present in the pressure sensitive adhesive, reorientation occurred much faster and was caused by strong hydrogen bonding with the surface of the sapphire. An increase in acrylic acid composition, increased the rate of reorientation. An experimental set up was constructed to specifically study interfaces with a nonuniform distribution within the plane of the surface. This allows for concomitant measurement of polarized total internal reflection Raman scattering and sum frequency generation spectroscopy along with bright field imaging and cross polarized imaging. This set up was used to study the L-histidine crystal in situ adsorbed on fused silica. The polarized experiments along with calculations allowed for a more in-depth analysis of the crystal orientation effect on the birefringence, the Raman and the sum frequency generation. / Graduate

This thesis explores how peace journalism (PJ) translates into practice in the Kenyan media environment. Through the personal accounts of practicing reporters in Kenya, this research reveals the challenges and opportunities Kenyan journalist-participants faced while covering the 2013 presidential election. Through their personal experiences, this research reveals reporters were working in an exceptionally challenging media environment; one significantly shaped by the 2007 election and post-election violence. Participants identified numerous constraints that shaped their reporting practices, including structural constraints within their newsrooms and societal constraints in relation to ethnic identity. This thesis concludes that PJ has yet to offer sufficient concrete or practical solutions addressing these influencing factors, largely because of an overestimation of the agency journalists possess. Therefore, this research validates an existing body of research that suggests there is a need for PJ to consider factors outside of journalists themselves, which may constrain their work. The objective of the research is not to discredit the value of the tools PJ offers, but rather draw attention to the notion that those tools alone are insufficient.

In this thesis, the work focuses on developing distributed optical fiber vibration sensors based on phase-sensitive optical time domain reflectometry (Φ-OTDR). Three works have been accomplished to improve the performances of Φ-OTDR for distributed vibration sensing. Firstly, Φ-OTDR based on a polarization diversity scheme is demonstrated to mitigate the polarization mismatch effect occurring in traditional systems. A theoretical analysis is performed in different polarization cases corresponding to coherent and polarization diversity detection. Φ-OTDR based polarization diversity shows a great potential in the multi-events sensing application. Two vibration events are simultaneously detected and their signal to noise ratios are improved by 10.9 dB and 8.65 dB, respectively, compared to the results obtained by a conventional coherent scheme. Intensity fluctuation in a phase-sensitive optical-time domain reflectometry (Φ-OTDR) system caused by stochastic characteristics of Rayleigh backscattering has limited relative vibration strength measurement, which is proportional to dynamic strain. A trace-to-trace correlation coefficient is thus proposed to quantify the Φ-OTDR system stability and a novel approach of measuring the dynamic strain induced by various driving voltages of lead zicronate titanate (PZT) is demonstrated. Piezoelectric vibration signals are evaluated through analyzing peak values of the fast Fourier transform spectra at fundamental frequency and high-order harmonics based on Bessel functions. Experimental results show high correlation coefficients and good stability of our Φ-OTDR system, as well as the small measurement uncertainty of measured peak values. To reduce the intra-band noise caused by the finite extinction ratio of optical pulses, Φ-OTDR based on high extinction ratio generation is studied. Two methods are developed for achieving high extinction ratio of optical pulse generation. One of the approaches is to synchronize two cascaded electro-optic modulators to achieve high extinction ratio operation. The other one is to use the nonlinear optical fiber loop mirror as an optical switch to suppress the continuous wave portion of optical pulse. The sensing range of 1.8 km and 8.4 km with corresponding spatial resolution of 0.5 m and 2 m have been demonstrated based on cascaded two electro-optic modulators and nonlinear optical fiber loop mirror setup, respectively.

d-Limonene (Lim) was used in various polymer formulations to achieve a more sustainable polymerization. Lim is a renewable and essentially non-toxic compound, derived from citrus fruit peels, that may replace some of the many toxic and fossil-based chemicals used in polymer synthesis. Bulk free-radical polymerizations of n-butyl acrylate (BA) with Lim were performed to investigate Lim co-polymerization kinetics and estimate the monomer reactivity ratios, important parameters in the prediction of copolymer composition. Kinetic modeling of the BA/Lim copolymerization was performed with PREDICI simulation software. The model supports the presence of a significant degradative chain transfer reaction due to Lim. This reaction mechanism is due to the presence of allylic hydrogen in Lim. Nonetheless, relatively high molecular weight polymers were produced. It was concluded that Lim behaves more like a chain transfer agent than a co-monomer. Terpolymerizations of BA, butyl methacrylate (BMA) with Lim were then performed. In order to predict the terpolymer composition, the monomer reactivity ratios for BA/BMA were estimated. By applying the three pairs of co-monomer reactivity ratios to the integrated Mayo-Lewis equation, terpolymer compositions were ably predicted up to high monomer conversion levels. Lim was then used as a chain transfer agent to prepare core-shell latex-based pressure sensitive adhesives (PSA) comprising BA and styrene via seeded semi-batch emulsion polymerization. By varying the concentration of Lim and divinylbenzene crosslinker, the core polymer microstructure was modified to yield different molecular weights and degrees of crosslinking. The core latex was then used as a seed to prepare core-shell latexes. By changing the Lim concentration during the shell-stage polymerization, the molecular weight of shell polymer was also modified. The latexes were characterized for their microstructure and were cast as films for PSA performance evaluation. The PSA performance was shown to be highly related to the polymer microstructure. Tack and peel strength showed a decrease with increasing Lim concentration. Shear strength went through a maximum with a core Lim concentration increase from 0 to 5 phm.

In July 2008, the UK Information Commissioner launched a review of EU Directive 95/46/EC on the basis that: “European data protection law is increasingly seen as out of date, bureaucratic and excessively prescriptive. It is showing its age and is failing to meet new challenges to privacy, such as the transfer of personal details across international borders and the huge growth in personal information online. It is high time the law is reviewed and updated for the modern world.” Legal practitioners such as Bergkamp have expressed a similar sense of dissatisfaction with the current legislative approach: “Data Protection as currently conceived by the EU is a fallacy. It is a shotgun remedy against an incompletely conceptualised problem. It is an emotional, rather than rational reaction to feelings of discomfort with expanding data flows. The EU regime is not supported by any empirical data on privacy risks and demand…A future EU privacy program should focus on actual harms and apply targeted remedies.” Accordingly, this thesis critiques key concepts of existing data protection legislation, namely ‘personal’ and ‘sensitive’ data, in order to explore whether current data protection laws can simply be amended and supplemented to manage privacy in the information society. The findings from empirical research will demonstrate that a more radical change in EU law and policy is required to effectively address privacy in the digital economy. To this end, proposed definitions of data privacy and private data was developed and tested through semi-structured interviews with privacy and data protection experts. The expert responses indicate that Bergkamp et al have indeed identified a potential future direction for privacy and data protection, but that further research is required in order to develop a coherent definition of privacy protection based on managing risks to personal data, and harm from misuse of such information.

High blood pressure or hypertension is a major public health issue that affects more than 50% of adults in the United States. Hypertension is the leading risk factor for multiple cardiovascular events including stroke and myocardial infarction. In general, hypertension is considered a disease of the aged population as 2/3rds of adults over 65 are hypertensive. Critically, a sex dependent component exists as females under age 50 are less likely to develop hypertension than males. Dietary sodium intake significantly influences blood pressure regulation and its importance is underscored by the salt-sensitivity of blood pressure, which is characterized by acute increases in blood pressure in response to dietary salt intake. The salt-sensitivity of blood pressure is prevalent in 25% of normotensive individuals and 50% of hypertensive individuals. Coupled with statistics that show Americans on average consume 2 g of sodium in excess of the recommended daily allowance, the risk for developing salt-sensitive hypertension is drastically higher in salt-sensitive individuals. Moreover with age, there is an increase in the prevalence and severity of salt-sensitivity. Taken together, these findings underscore the need for novel therapeutics to combat hypertension. The pathophysiology of the salt-sensitivity of blood pressure and age dependent hypertension has been attributed in part to excessive sympathetic outflow that can drive increases in sodium reabsorption. Excessive sympathetic outflow via the release of norepinephrine has been linked to increased activity of a key renal sodium transporter, the sodium chloride cotransporter (NCC). This thesis investigates the adrenergic signaling pathway by which excessive sympathetic outflow drives NCC activity and sodium reabsorption as well investigates the mechanisms underlying sex differences in age dependent hypertension. Our findings demonstrate that 1) norepinephrine mediates its influence on NCC activity via an α1-adrenoceptor gated pathway involving WNK/SPAK/OxSR1 kinase signaling, 2) α1-adrenoceptor antagonism can prevent and attenuate the development and maintenance of salt-sensitive hypertension, 3) β-adrencoptor antagonism has no effect on NCC activity, 4) in male rats age dependent salt-sensitivity of blood pressure and hypertension is associated with age dependent- increases in NCC activity and impairments in renal sodium handling, and 5) female rats do not develop age dependent hypertension or salt-sensitivity of blood pressure. Collectively, these results support a sympathetic model of NCC regulation that plays a key role in salt-sensitive hypertension and age dependent hypertension. / 2021-05-26T00:00:00Z