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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
711

Filmes sensíveis a pressão pela técnica de fotoluminescência. / Pressure sensitive films based on photoluminescence technique.

Keth Rousbergue Maciel de Matos 20 May 2011 (has links)
O presente projeto tem como objetivo contribuir para o desenvolvimento de dispositivos para monitoração de pressão dinâmica do ar. Para isso, foram produzidos filmes sensíveis a pressão baseados na detecção de concentração de oxigênio por meio de processos de emissão fotoluminescente das moléculas de Azul de Metileno (MB) e Platina Octaetilporfirina (PtOEP). Nesse sentido, foi estudado o comportamento da emissão fotoluminescente dessas moléculas em interação com o gás de oxigênio. A concentração de oxigênio (do ar) sobre superfície sensível depende da pressão dinâmica de superfície. Desta forma, monitorando a fotoluminescência dos dispositivos submetidos a diferentes concentrações de oxigênio, pode-se determinar uma relação entre a pressão pontual da superfície analisada e a intensidade de emissão fotoluminescente do filme. Os dispositivos de monitoração de pressão dinâmica são constituídos de um filme de estado sólido contendo as moléculas sensíveis. Foram utilizados como substratos hospedeiros para o Azul de Metileno e para a Octaetilporfirina de Platina, os filmes de silício poroso oxidado e Poliestireno, respectivamente. É proposto um arranjo experimental que utiliza um fluorímetro para caracterizar as amostras produzidas e uma câmara de fluxo de gases. Os dispositivos apresentaram elevada sensibilidade e evidenciaram o potencial para desenvolvimento e integração de sensores baseados no silício poroso à microeletrônica. / This project aims to contribute to the development of devices for monitoring dynamic pressure of the air. In this sense, films were produced based on pressure-sensitive detection of oxygen concentration through processes of photoluminescence emission from the molecules of methylene blue (MB) and platinum octaethylporphyrin (PtOEP). Accordingly, it was studied the behavior of the photoluminescence emission of these molecules in interaction with the oxygen gas. The concentration of oxygen (of the air composition) on the sensitive surface depends on the surface dynamic pressure. Thus, monitoring the photoluminescence of the devices under different oxygen concentrations, it can be determined a relationship between the punctual pressure of the tested surface and the photoluminescence emission intensity of the film. The devices for monitoring dynamic pressure are made of a solid state film containing the sensitive molecules. Oxidized porous silicon and polystyrene films were used as hosts for the Methylene Blue and for the Platinum Octaethylporphyrin, respectively. It was proposed an experimental setup that uses a spectrofluorophotometer and a gas flow chamber to characterize the produced samples. The devices showed high sensitivity and potential for development and integration of the sensors based on porous silicon for microelectronics.
712

Moradores em ação: constituição da paisagem no bairro Ribeirão Verde, em Ribeirão Preto - SP / Dwellers in action: building the landscape at the Ribeirão Verde area, in Ribeirão Preto, SP

Laura Barzaghi de Laurentiis 26 April 2010 (has links)
A dissertação versa sobre as tentativas de formação da paisagem em assentamentos habitacionais periféricos em áreas ambientalmente sensíveis, com base nas ações paisagísticas de alguns moradores, os moradores-em-ação. Partindo do entendimento de que as ações normativas e técnicas são necessárias mas não suficientes quando as questões referentes à conservação de recursos naturais e à preservação de áreas protegidas envolvem pessoas, e, consequentemente, as subjetividades, o estudo procurou desvelar o processo de formação de valores em relação à paisagem mediante diferentes formas de apropriação do espaço. O objeto empírico é o bairro Ribeirão Verde, localizado na periferia da cidade de Ribeirão Preto, resultado de um empreendimento da iniciativa privada em parceria com a Cohab-RP, na forma de lotes urbanizados, numa área de fragilidade ambiental, por ser zona de recarga do aquífero Guarani. O objeto mais amplo é constituído pelas questões ambientais e paisagísticas envolvidas em um assentamento habitacional em área periférica e ambientalmente sensível, produzido no processo de urbanização intensa e problemática da cidade de Ribeirão Preto, e sua ocupação por uma população desenraizada que, mediante ações paisagísticas no espaço livre, constrói laços afetivos, um sentido de identidade e a própria paisagem do lugar. Buscou-se verificar as formas de apropriação de um espaço sem histórico para seus moradores, e como se dá, em tais condições, a constituição de uma paisagem. Para tanto, no quadro teórico-conceitual dos estudos de Percepção Ambiental e numa abordagem qualitativa, colheram-se e analisaram-se depoimentos de moradores do bairro. A partir desse material concluiu-se que as ações que propõem a separação entre natureza e cidade não correspondem à realidade da complexa interdependência entre os elementos que compõem o ambiente, encontrando-se alternativas na construção de substratos paisagísticos plásticos, receptivos, que possam acolher a heterogeneidade dos moradores, seus aportes e diferentes usos e apropriações materiais, afetivos, simbólicos. / This dissertation deals with attempts at landscape building in peripherical housing settlements in an environment-sensitive area, through specific actions of a group of dwellersthe dwellers in action. On the assumption that the actual standardizing and technical interferences are necessary but not enough when people are concerned in issues regarding the conservation of natural resources and the preservation of endangered areasmeaning their native subjectivities, the study attempted to unravel the process of value formation regarding the landscape space by means of different ways of space appropriation. The empirical object was the Ribeirão Verde district, in the outskirts of Ribeirão Preto city. This settlement resulted from a private housing enterprise partner with Cohab-RP, to establish urbanized lots on an environment-sensitive area, since it is a reload site for the Guarani spring. In its widest sense, the object is made up of environment and landscape issues concerning an urban settlement on a peripherical and endangered area, resulting from the intensive and problematic urbanizing effort in Ribeirão Preto city, subsequently taken up by a space uprooted population. By means of their landscaping of free land parcels, these people build their attachments, a new sense of identity, and give the place its own profile. An attempt was made to identify how the dwellers tried to appropriate some land space without any prior story for them, and how they build the landscape under such circunstances. The testimonies of the district dwellers were collected and analyzed based on the theoretical body of concepts of Environment Perception, according to a qualitative approach. Based on this material we came to the conclusion that the actions intended to separate nature from city do not correspond to the reality of the complex interdependency among the elements that make up the environment, with its correlate search for alternatives to build plastic and receptive landscape sites able to welcome the material, symbolical, and psychological diversity of the dwellers, their individual contribution, differences in usage, and space appropriation.
713

Detecção de fraudes em cartões: um classificador baseado em regras de associação e regressão logística / Card fraud detection: a classifier based on association rules and logistic regression

Paulo Henrique Maestrello Assad Oliveira 11 December 2015 (has links)
Os cartões, sejam de crédito ou débito, são meios de pagamento altamente utilizados. Esse fato desperta o interesse de fraudadores. O mercado de cartões enxerga as fraudes como custos operacionais, que são repassados para os consumidores e para a sociedade em geral. Ainda, o alto volume de transações e a necessidade de combater as fraudes abrem espaço para a aplicação de técnicas de Aprendizagem de Máquina; entre elas, os classificadores. Um tipo de classificador largamente utilizado nesse domínio é o classificador baseado em regras. Entretanto, um ponto de atenção dessa categoria de classificadores é que, na prática, eles são altamente dependentes dos especialistas no domínio, ou seja, profissionais que detectam os padrões das transações fraudulentas, os transformam em regras e implementam essas regras nos sistemas de classificação. Ao reconhecer esse cenário, o objetivo desse trabalho é propor a uma arquitetura baseada em regras de associação e regressão logística - técnicas estudadas em Aprendizagem de Máquina - para minerar regras nos dados e produzir, como resultado, conjuntos de regras de detecção de transações fraudulentas e disponibilizá-los para os especialistas no domínio. Com isso, esses profissionais terão o auxílio dos computadores para descobrir e gerar as regras que embasam o classificador, diminuindo, então, a chance de haver padrões fraudulentos ainda não reconhecidos e tornando as atividades de gerar e manter as regras mais eficientes. Com a finalidade de testar a proposta, a parte experimental do trabalho contou com cerca de 7,7 milhões de transações reais de cartões fornecidas por uma empresa participante do mercado de cartões. A partir daí, dado que o classificador pode cometer erros (falso-positivo e falso-negativo), a técnica de análise sensível ao custo foi aplicada para que a maior parte desses erros tenha um menor custo. Além disso, após um longo trabalho de análise do banco de dados, 141 características foram combinadas para, com o uso do algoritmo FP-Growth, gerar 38.003 regras que, após um processo de filtragem e seleção, foram agrupadas em cinco conjuntos de regras, sendo que o maior deles tem 1.285 regras. Cada um desses cinco conjuntos foi submetido a uma modelagem de regressão logística para que suas regras fossem validadas e ponderadas por critérios estatísticos. Ao final do processo, as métricas de ajuste estatístico dos modelos revelaram conjuntos bem ajustados e os indicadores de desempenho dos classificadores também indicaram, num geral, poderes de classificação muito bons (AROC entre 0,788 e 0,820). Como conclusão, a aplicação combinada das técnicas estatísticas - análise sensível ao custo, regras de associação e regressão logística - se mostrou conceitual e teoricamente coesa e coerente. Por fim, o experimento e seus resultados demonstraram a viabilidade técnica e prática da proposta. / Credit and debit cards are two methods of payments highly utilized. This awakens the interest of fraudsters. Businesses see fraudulent transactions as operating costs, which are passed on to consumers. Thus, the high number of transactions and the necessity to combat fraud stimulate the use of machine learning algorithms; among them, rule-based classifiers. However, a weakness of these classifiers is that, in practice, they are highly dependent on professionals who detect patterns of fraudulent transactions, transform them into rules and implement these rules in the classifier. Knowing this scenario, the aim of this thesis is to propose an architecture based on association rules and logistic regression - techniques studied in Machine Learning - for mining rules on data and produce rule sets to detect fraudulent transactions and make them available to experts. As a result, these professionals will have the aid of computers to discover the rules that support the classifier, decreasing the chance of having non-discovered fraudulent patterns and increasing the efficiency of generate and maintain these rules. In order to test the proposal, the experimental part of the thesis has used almost 7.7 million transactions provided by a real company. Moreover, after a long process of analysis of the database, 141 characteristics were combined using the algorithm FP-Growth, generating 38,003 rules. After a process of filtering and selection, they were grouped into five sets of rules which the biggest one has 1,285 rules. Each of the five sets was subjected to logistic regression, so their rules have been validated and weighted by statistical criteria. At the end of the process, the goodness of fit tests were satisfied and the performance indicators have shown very good classification powers (AUC between 0.788 and 0.820). In conclusion, the combined application of statistical techniques - cost sensitive learning, association rules and logistic regression - proved being conceptually and theoretically cohesive and coherent. Finally, the experiment and its results have demonstrated the technical and practical feasibilities of the proposal.
714

Développement d’une méthode d’optimisation multiobjectif pour la construction bois : prise en compte du confort des usagers, de l’impact environnemental et de la sécurité de l’ouvrage / Development of a multiobjective optimisation method for timber building : consideration of user comfort, environmental impact and structural safety

Armand Decker, Stéphanie 22 September 2015 (has links)
Les pays industrialisés cherchent aujourd’hui à réduire leur consommation d'énergie et à utiliser des matières premières de substitution, notamment renouvelables dont le bois fait partie. Pour promouvoir son usage, le développement de méthodes favorisant son recours dans les systèmes constructifs pour la construction multiétage est nécessaire.La conception d’un bâtiment est multicritère. Des objectifs contradictoires sont à optimiser simultanément. Des solutions de compromis Pareto-optimaux sont par exemple recherchées entre l’atteinte des meilleures performances d’usage et la limitation de l’impact environnemental du bâtiment. Ces travaux portent ainsi sur le développement d’une méthode d’optimisation multiobjectif de systèmes constructifs bois adaptés au multiétage.Des objectifs de maximisation du confort vibratoire des planchers et de minimisation des besoins de chauffage, d’inconfort thermique, de potentiel de réchauffement climatique et d’énergie grise sont pris en compte. La méthode repose sur un algorithme d’optimisation multiobjectif par essaim particulaire capable de proposer un ensemble de solutions non-dominées constituant le front de Pareto. L’espace des solutions est contraint par des exigences réglementaires nécessaires à la sécurité de l’ouvrage. L’ensemble des fonctions-objectif est modélisé sous forme de fonctions analytiques. Les sorties d’intérêt du modèle de simulation thermique dynamique sont substituées par des métamodèles.La méthode développée est mise en oeuvre sur un cas d’étude. Les résultats obtenus offrent une grande diversité dans un panel de 20 000 solutions optimales. Ces résultats constituent un support de discussion entre les différents acteurs d’un projet de construction. / Industrialised countries are seeking to reduce their energy consumption and to use alternative raw materials, including renewables such as wood. To promote its use, multi-storey timber constructive systems need the development of new design methods.Building required a multicriteria design where conflicting objectives must be optimised simultaneously. Research solutions have to achieve the best Pareto-compromise between use performance and environmental impact of the building. This work aims to develop a multiobjective optimisation method of timber multi-storey building.The objectives of maximising floor vibration comfort and minimising heating needs, thermal discomfort, global warming potential and embodied energy are taken into account. A multi-objective particle swarm optimization algorithm is used to obtain a set of non-dominated solutions which is the Pareto front. The solution space is constrained by regulatory requirements necessary for the safety of the structure. All objective-functions are modelled as analytic functions. Dynamic thermal simulation model outputs are replaced by metamodels.The developed method is implemented on a case study. The results offer a great diversity in a panel of 20 000 optimal solutions. These results provide a basis for discussion between the different actors of a construction project.
715

Development of a transitioning approach to reduce surface water volumes in combined sewer systems

Smith, Kerry W. S. January 2016 (has links)
The overarching goal of this research is to establish a successful forum for a transition from the existing paradigm of managing wastewater infrastructure to a more sustainable paradigm that achieves a more efficient utilisation of wastewater assets. A transitioning approach to support a more efficient utilisation of surface water and wastewater assets and infrastructure is proposed and developed. The determined transitioning approach possesses key stages namely developing the arena, developing the agenda, case study, and monitoring. The case study stage investigates a drainage utility identifying their improvement drivers, the removal of surface water through detailed drainage modelling and the financial examination of the costs incurred under the various scenarios conducted. Understanding the implications of removing/attenuating surface water from the network is improved through obtaining data by detailed drainage modelling. Infoworks software is used to investigate and assess the current and future operational scenarios of a wastewater system operating over one calendar year. Modelling scenarios were conducted removing surface water from selected areas focusing on the volumes requiring pumping and durations of pumping station(s) operation prior to treatment during storm conditions. The financial implication of removing surface water in combined sewer systems is examined in three main components. Firstly the costs of electricity incurred at the single sewage pumping station (SPS) investigated during the various scenarios modelled require to be addressed. Secondly the costs to retrofit sustainable urban drainage system (SUDS) solutions needs to be identified. Thirdly the implications of removing surface water for the drainage utility at the national level and the potential saving for householder’s committing to a surface water disconnection rebate scheme. When addressed at the macro level i.e., with over 2,100 pumping stations, some operating in sequence and contained within one drainage utility annually treating 315,360 megalitres the significance of the same multiple quantifiable and intangible benefits becomes amplified. The research aims, objectives and findings are presented to the identified and convened stakeholders. The transitioning approach developed encourages positive discourse between stakeholders. The level of success of the transitioning approach determined is then tested using a quantitative methodology through the completion of questionnaires. From the questionnaires completed the respondents unanimously agreed that surface water flows should be removed as well as reduced from the combined sewer system. The respondents agreed that the removal of surface water from a typical combined sewer system is justified by applying a transitioning approach focusing on the energy consumption required to pump increased volumes during storm events. This response is significant based upon the economic evidence and is contrary to the respondents previous position that finance was their most influencing factor. When provided with other potentially available benefits the respondents were even more supportive of the justification to remove surface water from the combined sewer system. The combined findings of the work presented in this thesis provide further justification that the transitioning approach applied to the removal of surface water from a typical combined sewer system, as determined in this research has been successful.
716

La première rencontre du corps malade en contexte de soins infirmiers : la relation de soin : une expérience ultime, du sensible au social / The first encounter with a sick body in a nursing care context : the care relationship : the utmost experience ranging from the sensitive to the social dimensions

Lagarde-Piron, Laurence 07 December 2016 (has links)
Notre étude porte sur les soins infirmiers avec une entrée par le corps et les émotions dans le contexte de formation et dans l’espace sensible de l’hôpital. L’étudiant est placé au centre de notre recherche, il vit à travers son corps une expérience sensorielle et relationnelle inédite et singulière dans un cadre social chargé de symboles. Il perçoit le monde des soins à travers ses sens qui l’informent, l’orientent et le déstabilisent. L’inscription de notre recherche en SIC se fait par la problématisation sensible, sensorielle et symbolique ; par la conceptualisation à travers plusieurs disciplines et différentes approches théoriques, l’interactionnisme symbolique et la phénoménologie. L’enquête a permis de recueillir un corpus de données qui, croisées avec nos archives personnelles, ont permis d’explorer l’expérience de l’étudiant dans ses dimensions perceptive et émotionnelle, cognitive et imaginaire, sans la désincarner. Dans une démarche compréhensive, nous cherchons à saisir les processus à l’œuvre dans l’émergence de l’émotion, ses manifestations et sa gestion lorsque l’étudiant se donne pour la première fois en représentation en réalisant ses premiers soins au corps. Les soins d’hygiène se déroulent dans une mise en scène où chacun, soignant et soigné, protège son image et son espace. Ils se prêtent à des mises en scène très variées et des jeux de rôle d’une grande richesse, se révélant sans nul doute comme les plus riches en significations. Ils mobilisent tous les sens et entraînent de nombreuses sensations intimes et secrètes faisant émerger de multiples ressentis qui s'exposent, se partagent et se montrent ou bien s'imposent et indisposent. Ils font résonner l’histoire des soins, les codes et les normes sociales, l’identité du rôle propre de l’infirmière. / Our study focuses on nursing care with a first approach based on human body and emotions through the teaching context in the sensitive hospital environment. The nursing student is a central point of our research as he lives a unique sensitive and interpersonal experience within his own body in a social setting imbued with symbolism. He perceives health care community through his five senses which inform and direct him, but also may destabilize him. We decided to base our study on the information and communication sciences thanks to a sensitive, sensorial and symbolic problematisation and through a multidisciplinary conceptualization based on different theoretical approaches, symbolic interactionism and phenomenology. The survey enabled us to collect a data set which was crossed with the researcher’s personal archives. This has enabled us to explore the student’s experience in its perceptual and emotional as well cognitive and imaginary dimensions, without disembodying it. Within a comprehensive approach, we tried to understand the process involved in the emergence of emotions, its expressions and management when the student performs and handles for the first time body cares. Personal hygiene tasks unfold in a staging where each of the characters, caregiver and care-receiver, protect both his own image and living space. They show various performances and a high degree of role playing which are doubtlessly the most meaningful. Every sense is mustered, drawing numerous intimate and secretive feelings which lead to the emergence of many perceptions. These perceptions are exhibited and shared, or are imposed on and therefore indispose. They are a true part of nurse care History, social codes and standards, and the identity of the nurse’s role.
717

Nanosondes épigénétiques / Epigenetic nanoprobes

Bahhaj, Fatima El 30 October 2014 (has links)
Les cibles épigénétiques telles que les histones désacétylases (HDAC) sont étudiées comme nouveaux traitements anticancéreux, leur fonctionnement anormal étant associée aux processus cancéreux. De nombreux inhibiteurs de ces enzymes sont apparus tel que le SAHA ou le CI-994. Notre laboratoire a développé un nouvel analogue de la trichostatine A appelé NODH. Malgré leur activité anticancéreuse in vitro prometteuse, ces inhibiteurs souffrent de leur manque de solubilité, d'effets toxiques et de leur rapide métabolisation par l'organisme. Afin de pallier ces limitations, ces iHDAC peuvent être conjugués à des vecteurs capables de les transporter dans l'organisme et de les libérer une fois la cible tumorale atteinte. Ce travail de thèse a consisté dans un premier temps à développer des prodrogues acido-sensibles capable de libérer la substance active après endocytose par les cellules. Ces systèmes ont été appliqués aux trois iHDAC SAHA, CI-994 et NODH. Les prodrogues développées ont ensuite été accrochées sur des nanoparticules polymériques connues pour leur biocompatibilité et leur accumulation dans les tumeurs grâce à l'effet EPR. L'activité anticancéreuse de certaines nanoparticules a été validée par des tests in vitro et in vivo. Un deuxième travail a été entrepris concernant la préparation de prodrogues fluorescentes pH labiles capables de libérer la substance active et de moduler la fluorescence par la variation du pH. La dernière partie de ce travail a été consacrée à la mise au point d'une nouvelle méthode de synthèse par voie superacide potentiellement stéréosélective de benzofuranones nécessaires à la préparation d'analogues de NODH. / Epigenetic targets like histone deacetylases (HDAC) are studied as new anticancer treatments, their dysfunctioning being associated to cancer mechanisms. Several epigenetic target inhibitors have been developed like SAHA or CI-994. Our group has developed a new trichostatin A analogue called NODH. Despite their promising in vitro anticancer effect, these inhibitors suffer from lack of solubility, toxic effects and rapid clearance. These constrains make the HDACi good candidates for ligation to vectors able to carry them in the body and to release them when the tumor is reached. The first part of this thesis work has focused on the development of acid sensitive prodrugs able to release an active substance after cellular internalization by endocytosis. These systems were applied to three HDACi SAHA, CI-994 and NODH. These prodrugs were then conjugated to polymeric nanoparticles known for their biocompatibility and their accumulation in tumors exploiting the EPR effect. The anticancer activity of some nanoparticles has been validated by in vitro and in vivo tests. The second part of this work was carried out in order to prepare pH sensitive fluorescent prodrugs able to release the active molecule and to modulate the fluorescent effect by pH changes. The last part of this work was dedicated for the development of a new synthesis in suparacid potentially stereoselective of several benzofuranones required for the preparation of NODH analogs.
718

Analyse par de nouveaux outils de fluorescence du mécanisme de la protéine UHRF1 dans la méthylation de l'ADN / Epigenetic DNA modification monitored by a new fluorescence based tool

Kilin, Vasyl 26 February 2016 (has links)
Les profils de méthylation de l’ADN sont des marques épigénétiques essentielles contrôlant l'expression génétique spécifique des tissus. Ces profils sont fidèlement reproduits par l’enzyme DNMT1 qui est dirigée par la protéine UHRF1 vers les sites CpG hémiméthylés (HM). La spécificité élevée d’UHRF1 vis-à-vis de ces sites CpG HM est liée à la capacité de son domaine SRA de basculer sélectivement les résidus méthylcytosine (mC). Par conséquent, la compréhension de la capacité d’UHRF1 à lire les séquences d'ADN et de basculer leurs résidus mC est une question importante en épigénétique moléculaire. Dans le présent travail, nous avons utilisé des analogues de nucléobases sensibles à l'environnement pour étudier le basculement de base induit par SRA. Nous avons découvert qu’un étiquetage par la 2-thiényl-3-hydroxychromone (3HCnt) à proximité de la cible CpG méthylée, permet le suivi de ce basculement SRA-induit de mC et de sa dynamique. Les spectroscopies de fluorescence à l'état stationnaire et de "stopped flow" ont montré des différences significatives entre les ADNs HM et non méthylé (NM) vis-à-vis de la reconnaissance et la cinétique de liaison du SRA. Effet, nous avons montré que SRA est capable de se lier et de glisser avec une cinétique rapide sur le duplex NM, en accord avec le rôle de lecteur d’UHRF1. Par contre, la cinétique de basculement de mC s’avère beaucoup plus lente, ce qui augmente sensiblement la durée de vie d’UHRF1 lié à un site CpG hémi-méthylé et donc la probabilité de recruter DNMT1 afin de dupliquer fidèlement le profil de méthylation de l’ADN. Nous avons ainsi obtenu pour la première fois un test capable de suivre le basculement de la base induit par UHRF1, ce qui nous a permis de proposer un mécanisme pour le recrutement de DNMT1 par UHRF1 sur les sites HM. / DNA methylation patterns are key epigenetic marks which control tissue specific gene expression. These patterns are faithfully replicated by the DNMT1 enzyme which is directed by the UHRF1 protein to hemi-methylated (HM) CpG sites. The high specificity of UHRF1 to HM CpG sites is related to the ability of its SRA domain to selectively flip methylcytosine (mC) residues. Therefore, the understanding of how UHRF1 reads DNA sequences and flips mC residues is an important question in molecular epigenetics. In the present work, we apply environment-sensitive nucleobase analogues to study the SRA-induced base flipping. We found that only labelling by 2-thienyl-3-hydroxychromone (3HCnt) outside but close to the target methylated CpG allows monitoring the SRA-induced mC-flipping and its dynamics. Fluorescence steady-state spectroscopy and stopped flow measurements showed significant differences in the recognition and binding kinetics of SRA for HM and non-methylated (NM) DNA. Indeed, SRA was found to bind and slide with fast kinetics on NM duplexes, in line with the reader role of UHRF1. In contrast, the kinetics of mC flipping was found to be much slower, substantially increasing the lifetime of UHRF1 bound to a CpG site in HM duplexes and thus, the probability of recruiting DNMT1 in order to faithfully duplicate the DNA methylation profile. Therefore, we proposed for the first time an assay able to sensitively monitor the UHRF1-induced base flipping, which helped us to provide a possible mechanism for the UHRF1 directing function on DNMT1.
719

Simultaneous real-time object recognition and pose estimation for artificial systems operating in dynamic environments

Van Wyk, Frans Pieter January 2013 (has links)
Recent advances in technology have increased awareness of the necessity for automated systems in people’s everyday lives. Artificial systems are more frequently being introduced into environments previously thought to be too perilous for humans to operate in. Some robots can be used to extract potentially hazardous materials from sites inaccessible to humans, while others are being developed to aid humans with laborious tasks. A crucial aspect of all artificial systems is the manner in which they interact with their immediate surroundings. Developing such a deceivingly simply aspect has proven to be significantly challenging, as it not only entails the methods through which the system perceives its environment, but also its ability to perform critical tasks. These undertakings often involve the coordination of numerous subsystems, each performing its own complex duty. To complicate matters further, it is nowadays becoming increasingly important for these artificial systems to be able to perform their tasks in real-time. The task of object recognition is typically described as the process of retrieving the object in a database that is most similar to an unknown, or query, object. Pose estimation, on the other hand, involves estimating the position and orientation of an object in three-dimensional space, as seen from an observer’s viewpoint. These two tasks are regarded as vital to many computer vision techniques and and regularly serve as input to more complex perception algorithms. An approach is presented which regards the object recognition and pose estimation procedures as mutually dependent. The core idea is that dissimilar objects might appear similar when observed from certain viewpoints. A feature-based conceptualisation, which makes use of a database, is implemented and used to perform simultaneous object recognition and pose estimation. The design incorporates data compression techniques, originally suggested by the image-processing community, to facilitate fast processing of large databases. System performance is quantified primarily on object recognition, pose estimation and execution time characteristics. These aspects are investigated under ideal conditions by exploiting three-dimensional models of relevant objects. The performance of the system is also analysed for practical scenarios by acquiring input data from a structured light implementation, which resembles that obtained from many commercial range scanners. Practical experiments indicate that the system was capable of performing simultaneous object recognition and pose estimation in approximately 230 ms once a novel object has been sensed. An average object recognition accuracy of approximately 73% was achieved. The pose estimation results were reasonable but prompted further research. The results are comparable to what has been achieved using other suggested approaches such as Viewpoint Feature Histograms and Spin Images. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / unrestricted
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Progressive landslide analysis : Applications of a Finite Difference Method by Dr. Stig Bernander Case Study of the North Spur at Muskrat Falls, Labrador, Canada

Dury, Robin January 2017 (has links)
An easy-to-use spreadsheet version of a finite difference method for progressive landslide analysis has been developed. The finite difference method was originally developed by Dr. Stig Bernander, earlier adjunct professor at Luleå University of Technology and head of the Design Department of Skanska AB in Gothenburg, Sweden.. The so called Muskrat Falls Project consists in the ongoing construction of a hydroelectric power plant in Churchill River Valley, Labrador, Canada. The site hosting the project includes a land ridge which is supposed to be used as a natural dam and thus be submitted to important water pressures. Yet, previous landslides in the area have shown that a stability analysis is worth to be carried out in order to ensure the safety of the facility. Until now, investigations have only been carried out using the traditional limit equilibrium method and related elastic-plastic theory. For the sake of simplicity, this approach does not take into account deformations outside and inside the sliding body. However, because of the soil features in Churchill River Valley and particularly its ‘deformation softening’ behavior, there is increasing evidence that the conventional analysis is not relevant in this situation. Further, when analyzing the total stability of the ridge, only a horizontal failure surface has been used and not an inclined one, which is very optimistic and rather unrealistic.. In order to provide a more reliable study, a progressive failure analysis has been performed according to the finite difference method of Dr. Stig Bernander. The development of a spreadsheet adapted to this particular problem has allowed getting quickly and easily numerical results for several cases of study and assumptions. For assumed material properties and geometries of failure, the critical load-carrying capacity is below 1000 kN/m whereas a rise of the water level with 21 m will give an increased load of Nq  = 2420 kN/m. This is more than twice of the what the ridge may stand with the assumed properties. The investigation has led to the conclusion that the situation will be risky for many combinations of soil properties if the water level is raised as high as initially planned. The investigation also shows that more material tests are necessary and that stabilization work may be needed to eliminate the risk for a landslide.

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