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Fake news : Kan korrekt information motverka lögner?Eriksson, Joakim, Afanaseva, Anastasiya January 2018 (has links)
Sveriges regering och SÄPO har identifierat fake news som ett hot mot demokratin. I denna studie undersöker vi om fake news påverkar individer, trots att de vid samma tillfälle erhåller korrekt information inom ämnet. Detta gjordes genom en enkätundersökning på studenter vid Uppsala universitet. Vi fann att erhållandet av korrekt information inte är tillräckligt för att motverka effekten av att exponeras för falsk information. De studenter som fick läsa en mening med falsk information var 15 procentenheter mer sannolika att svara att de anser att staten lägger för mycket resurser på invandringen jämfört med kontrollgruppen. Resultatet tyder på att politiker, organisationer och privatpersoner kan dra nytta av att sprida fake news, att de kan göra så anonymt, och att faktagranskning ensamt inte kan stävja problemet med fake news. / The Swedish government and the Swedish Security Service have identified fake news as a threat to democracy. In this study, we investigate if fake news affect individuals, even though they receive correct information regarding the subject simultaneously. This was accomplished through handing out a survey to students at Uppsala University. We found that obtaining correct information is insufficient to counteract the effects of being exposed to fake news. The students who read a sentence with false information were 15 percentage points more likely to answer that they believe that the Swedish government allocates too much resources towards immigration compared to the control group. The result indicate that politicians, organizations and individuals can take advantage of spreading fake news, that they can do so anonymously, and that fact checking alone cannot solve the problem of fake news.
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Proposta e análise de novos sistemas de ancoragem para End Fittings de Risers flexíveisLorio, Diego Andrés January 2016 (has links)
O trabalho apresentado tem como finalidade analisar os sistemas de ancoragem utilizados na fabricação de End Fittings (EF), através de ensaios de dois sistemas de ancoragem alternativos aos utilizados atualmente na indústria. Além disso, é apresentado o desenvolvimento de um modelo de elementos finitos (MEF) que permite a reprodução do comportamento durante o processo de pullout da ancoragem com melhor desempenho. A caracterização dos materiais envolvidos no sistema de ancoragem foi necessária para o desenvolvimento do modelo numérico. Desta forma, o modelo numérico conta com as propriedades elásticas e plásticas dos materiais, fator que influencia o comportamento do sistema assim como os valores de carga necessários para o arrancamento. A comparação das ancoragens propostas foi realizada a partir dos valores de força obtidos por meio de um teste de arrancamento, chamado de pullout. Para isto, arames da armadura de tração de uma linha flowline de 2,5 polegadas foram conformados de acordo à geometria das ancoragens propostas e embebidas em resina epóxi tentando, desta forma, representar de forma simplificada parte do sistema de ancoragem utilizado nos EF. O desempenho das ancoragens foi analisado a partir das curvas de força em função do deslocamento, nas quais se analisou a força máxima de pullout (força máxima de arrancamento), o deslocamento para força máxima de pullout e o valor de rigidez do sistema. Finalmente depois de selecionada a ancoragem com melhor desempenho, os valores experimentais foram comparados com os valores obtidos do modelo numérico, mostrando uma boa aproximação com valores de erro relativo para a força máxima de pullout e rigidez de -1% e 8%, respectivamente. Por fim, propõe-se como trabalho futuro a continuação nos estudos experimentais de pullout com o objetivo de aprofundar o conhecimento sobre os parâmetros que mais influenciam nestes sistemas, através da utilização de novas geometrias e materiais, assim como a normalização do processo de preparação e ensaio das amostras. / The work aims to analyze the anchoring systems used in manufacturing of flexible pipe End Fittings (EF) through the tests of two alternative anchoring systems different of the currently used in the industry. In addition, it is presented the development of a finite element model (MEF) that allows to reproduce the behavior during the pullout process of the anchoring system with the better performance. The characterization of the materials involved in the anchoring system was necessary for the development of the numerical model. In this way, the numerical model include the elastic and plastic properties of materials, factor that influence the behavior of the system as well as the force values needed for the pullout. The comparison of the proposed anchoring systems was performed from the force values obtained through a pullout test. For this, the armor wires of a flowline flexible pipe with a bore of 2.5-inch were conformed according the geometry of the anchoring systems proposed and then were fixed in epoxy resin, trying in this way to represent a simplified form of the anchoring system used in EF. The performance of the anchoring systems was analyzed from the force-displacement curves. The maximum pullout force, the offset for maximum strength of pullout and the stiffness value of the system were used for the analysis. Finally, after selected the anchoring system with better performance, the experimental values were compared with the values obtained from the numerical model. The results showed a good approximation, with a relative error for the maximum pullout force and stiffness of -1% and 8% respectively. As proposal for future works, the author proposes to continue with the experimental studies of pullout in order to enhance the knowledge about the influential parameters in these systems, through the use of new geometries and materials, as well as the standardization of the test samples preparation.
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Azopolímeros e aplicações em efeitos de competição de orientação de cristais líquidos / Azopolymers and Applications of Orientational Effects in Liquid CrystalBruno Silveira de Lima Honda 20 October 2009 (has links)
Neste trabalho foi feito o estudo do efeito de orientação de moléculas de cristal líquido (5CB) em superfícies recobertas com fotopolímeros. Estudamos o processo de alinhamento fotoinduzido às moléculas de cristal líquido, de forma a caracterizar a intensidade de energia de ancoramento em função da energia de luz incidente e da concentração de cromóforos nos fotopolímeros. Foi realizado um estudo do efeito de competição entre duas direções distintas induzidas por fotoalinhamento, através da gravação de microtexturas periódicas. Neste trabalho, foi utilizado um modelo teórico para explicar como se dá a transição orientacional conforme se muda o período da textura periódica gravada. Foi feito também a gravação de grades de relevo nesses materiais, utilizando luz polarizada com alta potência incidente através da técnica de interferência de luz. O objetivo principal deste trabalho seria uma tentativa de se realizar o efeito de competição de alinhamento entre os processos fotoinduzidos: um efeito de fotoalinhamento, levando em conta a orientação das cadeias poliméricas, e outro de relevo, levando em conta a deformação da superfície tratada. Um resultado obtido foi a impossibilidade de se realizar este estudo, pois as intensidades de energia de ancoramento induzidas envolvidas diferem entre si de um fator de duas ordens de grandeza, mostrando que a direção de fotoalinhamento sempre acaba prevalecendo. Para contornar este problema, foi estudada a competição de fotoalinhamento com a técnica de rubbing, tendo em vista que as intensidades de energia de ancoramento estudadas eram compatíveis entre si. / In this work we performed a study of the orientacional effect of the liquid crystals molecules in substrates coated with azopolymers films. We studied the photoalignment induced to liquid crystals molecules to determine the behavior of the magnitude of anchoring energy as a function of incident energy and azodyes concentration in the polymer. Then we performed a competition study of the competition of photoalignment effect by recording a microtexture pattern on the azopolymer surface, with two directions of alignment. In this work, we also introduced a theoretical model to explain the orientacional transitions observed as we changed the period of the patterned microtexture. Another technique utilized was the Surface Relief Grating recording, by using polarized light with enough power and creating an interference pattern in the azopolymer surface, we were able to create a topological structure in the surface. The main objective of this work was supposed to investigate the competition between these two photoinduced effects, when one is caused by a photoalignment of the polymer chains, and the other is due to topological issues. We concluded that it was not possible to have competition between these two effects, mainly because the magnitude of the anchoring energy induced by SRG was found to be a hundred times smaller than the photoinduced one. As an alternative to this approach, we studied, then, the competition between the rubbing process and the photoalignment effect, as the magnitude of these two effects was found to be compatible.
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Avaliação da vida em fadiga de um novo modelo de terminal conector para dutos flexíveisXavier, Flávio Galdino January 2009 (has links)
Este trabalho foca a avaliação da vida em fadiga de um novo modelo de terminal conector para dutos flexíveis (risers) de camadas não aderentes (unbonded). Os ensaios foram feitos levando em consideração apenas a parte estrutural desses dutos, de forma a ensaiar uma nova configuração de ancoragem da armadura de tração encontrada nesse equipamento conhecido como terminal conector (end fitting). É dentro deste componente que os arames da armadura de tração são fixados por resina epóxi em conjunto com uma configuração específica permitindo dessa maneira a sustentação do duto flexível quando fixado a plataformas offshore. Para a escolha do novo modelo de ancoragem aqui proposto, além de se tomar como referência, fez-se também uma analogia aos modelos utilizados nas ancoragens das barras metálicas utilizadas em concreto protendido. Isto foi feito por entender que algumas características mecânicas da resina epóxi aproximam-se das do concreto. Para a definição do novo modelo de ancoragem, uma análise simplificada, utilizando o Método dos Elementos Finitos (MEF), foi feita em dois modelos de ancoragens recomendados na API RP 17B (2002) e utilizado por alguns fabricantes, no intuito de verificar as distribuições das tensões ao longo desses arames dentro do terminal conector quando envolto pela resina epóxi. Esta análise destacou as regiões ao longo dos arames onde havia concentrações das tensões. Utilizando-se dessas informações, foi desenvolvida uma nova configuração para o arame dentro da resina de maneira a minimizar esses concentradores de tensão, permitindo assim que o modelo de ancoragem proposto tenha um melhor desempenho em fadiga. Para tanto, as verificações desses modelos feitas através do MEF e validadas através de ensaios experimentais em escala reduzida, mostraram que o modelo proposto apresentou reduções do KT da ordem de 16,5% e das tensões na resina de 60% quando comparados aos outros dois modelos comerciais. Após essas avaliações protótipos do novo terminal conector foram confeccionados em escala real e montado a dois pedaços de duto flexível de 2,5" de diâmetro, compondo assim dois corpos de prova: o CP1 e o CP2, os quais foram submetidos a ensaios de tração estáticos e carregamentos dinâmicos. Nos ensaios o CP1 foi submetido a uma carga máxima em tração de 844 kN e após esse carregamento, a não evidência de ruptura nos arames da armadura de tração o levou para o ensaio de fadiga com cargas em tração variando entre 130 e 304 kN a uma freqüência de 1Hz para uma vida de 1.000.000 de ciclos de carga. O resultado desse ensaio mostrou a viabilidade do conceito, uma vez que se atingiu a 1.000.000 de ciclos de carga sem a ruptura de qualquer arame dentro do terminal conector, evidenciado através da dissecação. Para finalizar os trabalhos, um segundo corpo de prova (CP2) foi confeccionado, obedecendo as recomendações estipuladas na API RP 17B (2002). Ensaiado com os mesmos parâmetros do CP1, se conseguiu levá-lo a fase de Dano igual a 1. Ao final desse ensaio observaram-se a ruptura de alguns arames na região mediana sobre o duto flexível que unia os dois conectores. Já as dissecações não mostraram evidências de arames rompidos internamente aos conectores. / This work focuses on the evaluation of the fatigue of life in a new model of end fitting for unbounded flexible pipe (risers). The tests had been made taking in consideration only the structural part of these risers, in order to test a new configuration of anchorage of the tensile armor found in equipment known as an end fitting. It is inside of this component that the tensile armor wires are fixed by epoxy resin in the set with specific configuration in this way allowing the sustentation these flexible pipes when the fixed offshore platforms. For the choice of the new model of anchorage considered here, beyond the reference if taking an analogy to the models used in the anchorage dues ones of the metallic bars used in prestressed concrete. This was made by understanding that some mechanical characteristics of the epoxy resin are come close to the concrete. For the definition of the new model of anchorage, the simplified analysis, using the Finite Element Method (FEM), was made in two models of anchorage dues recommended in API RP 17B (2002) and used by some manufacturers, in intention to verify the distributions tensions along the wires within of the end fitting when wrapped for the epoxy resin. This analysis highlighted the wires throughout the regions where it had concentrations of the tensions. Using these information of itself, a new configuration for the wire inside of the way resin was developed to minimize these concentrators of tension as soon as, allowing anchorage of the considered model one has better performance in fatigue. For in such a way, the verifications of these models made through the FEM and validated through experimental tests in reduced scale, had shown that the considered model presented reductions of the KT of the order of 16.5% and stress in the resin of 60% when compared with the others two commercial models. After these evaluations archetypes of connecting the new end fitting had been confectioned in real scale and mounted two pieces of flexible pipe of 2.5" of diameter, thus composing test of two bodies: the CP1 and the CP2, which had been submitted the static tension tests and dynamic loads tests. In the tests the CP1 was submitted to tension in the maximum load of 844 kN and after this shipment, the evidence of rupture in the wires of armor did not take the tension it for the tests of fatigue in traction with loads varying between 130 and 304 kN to the frequency of 1Hz for a life of 1,000,000 cycles of load. The result of this test showed the viability of the concept, that if the team reached the inside of 1,000,000 load cycles without the rupture of any wire of the end fitting, evidenced through the dissection. To finish the works, the body of the test (CP2) it was confectioned, obeying to the recommendations stipulated in API RP 17B (2002). Tested with the same parameters of CP1, were taken to the stage Damage equal to 1. To the end of this test they had observed it rupture of some wires in the region on the medium flexible pipe that joined the two end fittings. Already the dissections had not shown evidence of broken internally wires to the end fittings.
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A heurística da ancoragem e seus efeitos no julgamento: decisões de consumo / The anchoring heuristic and its effects in judgment: consume decisionsMarcos Roberto Luppe 28 August 2006 (has links)
Este trabalho destina-se a realizar um estudo dos efeitos da heurística da ancoragem em estimativas numéricas, e esta fundamentado em pressupostos teóricos apresentados por Amos Tversky e Daniel Kahneman em um estudo seminal de 1974. Sendo assim, este trabalho tem por objetivo examinar quais os efeitos da heurística da ancoragem nas estimativas numéricas sob a perspectiva da avaliação de bens de consumo. Os objetivos específicos foram testar o método proposto por Jacowitz e Kahneman (1995) para a mensuração dos efeitos da ancoragem em estimativas de quantidades incertas e comparar os resultados deste estudo, com os resultados dos trabalhos realizados anteriormente nesta área em outros países. O método utilizado segue as etapas propostas por Jacowitz e Kahneman (1995). Os resultados indicaram que, embora, novos experimentos sejam necessários para um avanço no entendimento de como a ancoragem pode influenciar o processo decisório de consumo, a confirmação da manifestação dos efeitos da ancoragem na estimação de quantidades incertas no experimento 1, e dos preços de diferentes produtos e serviços no experimento 2, numa avaliação do grupo total de participantes da pesquisa, foi a principal contribuição deste trabalho, além de seus resultados corroborarem com os resultados encontrados em estudos similares realizados em outros países, revelando que, no contexto brasileiro, também se observam os efeitos da ancoragem. Além disso, os resultados estendem a pesquisa dos efeitos da ancoragem na estimação do preço de produtos e serviços, e contribui para um melhor entendimento do comportamento do consumidor. Especificamente, o experimento 2 fornece novas percepções relativas aos estudos da ancoragem e indica como um número arbitrário apresentado a um indivíduo pode alterar o seu julgamento, quanto ao preço de um produto ou serviço. Deste modo, esses resultados sugerem que, em vez de dependerem de um enfoque mais passivo na estimação do valor de um produto para os compradores em potencial, e fixarem um preço de acordo com os métodos tradicionais de precificação, os varejistas podem adotar um papel mais ativo na determinação dos preços de determinados produtos, baseados na análise de fatores subjetivos que afetam os julgamentos de preços dos consumidores. / This research paper aims to study the effects of anchoring heuristic in numerical estimates, based on the theoretical presuppositions presented in the seminal work of Amos Tversky and Daniel Kahneman in 1974. The purpose of this work is hence to examine what effects of anchoring heuristic has in numerical estimates for an assessment of consumer goods. The specific objectives were to test the method suggested by Jacowitz and Kahneman (1995) to measure the anchoring effects in estimates of uncertain quantities and compare the results of this study with those of surveys previously conducted in this field in other countries. The method used follows the steps suggested by Jacowitz and Kahneman (1995). The results indicated that, although new experiments are necessary to further understand how the anchoring is likely to influence the consumer decision process, the confirmed appearance of the anchoring effects on the estimate of uncertain quantities in experiment 1, and the prices of different products and services in experiment 2, in an overall group assessment of those who participated in the research, was the main contribution to this work, besides the fact that its results corroborated the results found in similar studies conducted in other countries, thereby revealing that the anchoring effects are also observed in the Brazilian context. Moreover, the results broaden the research on the anchoring effects when estimating product and service prices, and contribute to a better grasp of consumer behaviour. Experiment 2, more specifically, supplies new perceptions as to surveys on anchoring and reveals how an arbitrary number presented to an individual can change their judgement as to the price of a product or service. Hence, the results suggest that instead of having to concentrate more passively on a value estimate of a product for potential buyers and fixing a price according to traditional pricing methods, retailers may adopt a more active role when fixing the price of specific products, based on the analysis of subjective factors that affect the consumers judgement on prices.
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An Escap-ee from French to English who will never return : A semantic and syntactic study of the -ee suffix in English / Suffixet som rymde från franska till engelska : En semantisk och syntaktisk studie av det engelska suffixet -eeWong, Yiu Tong January 2017 (has links)
The aim of this paper is to investigate the semantic and syntactic properties of the -ee suffix in English. The -ee suffix was borrowed from the French ‑é suffix during the late Middle Ages, when French started to exert its linguistic influence on English. Previous research suggests that the -ee suffix in English exhibits the semantic properties of sentience, episodicity and passivity. Syntactically, the function of the -ee suffix in English may suggest ergativity. Furthermore, it has been suggested that contextual anchoring is involved in the use of the -ee suffix. I explored these characteristics of the -ee suffix by testing non‑standardised -ee suffixed nouns with the mentioned semantic and syntactic properties. The process of differentiating non‑standardised from standardised -ee suffixed nouns was done with the help of a well-established dictionary and the Internet. The results showed that sentience and episodicity applied to most -ee suffixed nouns. In addition, passivity was an important feature in the -ee nominalisation of transitive stem verbs. When the meaning of -ee suffixed nouns was complex, contextual anchoring served to facilitate the understanding of the meaning of the noun. Syntactically, the relationship between the ‑ee suffix and ergativity was weak. Thus, it can be concluded that the use of the ‑ee suffix is controlled by several semantic properties simultaneously, whereas the syntactic properties are relatively unimportant. / Den här uppsatsen undersöker -ee-suffixets semantiska och syntaktiska egenskaper i engelska. Suffixet lånades från det franska suffixet -é under senmedeltiden, när det franska språket började påverka engelska. Tidigare forskning hävdar att det engelska -ee-suffixet påvisar semantiska egenskaper såsom animacitet, episodicitet och passivitet. Syntaktiskt sett kan suffixet även tyda på ergativitet. Användning av suffixet är i viss mån förknippad med förankringen i kontexten. Ickestandardiserade -ee -avledda substantiv identifierades och deras semantiska och syntaktiska egenskaper undersöktes. Urvalet av icke-standardiserade och standiserade substantiv utfördes med hjälp av ett väletablerat lexikon och Internet. Resultatet visade att de flesta -ee-avledda substantiven uppvisar episodicitet och majoriteten även animacitet. Passivitet är ett viktigt kännetecken av suffixet när det gäller substantiveringen av transitiva verb. Betydelserna av vissa mer svårtydda eeavledda substantiv förankras ibland i kontexten med exempelvis förekomsten av er-/-or-avledda motsvarigheter. Syntaktiskt sett är ergativitet inte ett tydligt särdrag av -ee-suffixet. Sammanfattningsvis kan det hävdas att -ee-suffixets användning styrs framför allt av samverkan mellan flera olika semantiska aspekter, medan den syntaktiska egenskapen, ergativitet, är relativt oväsentlig.
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Acute and Chronic Effects of Large-Vessel Anchoring on Coral Reef Communities Inside a Designated Commercial AnchorageWaters, Lauren 01 May 2015 (has links)
Coral reefs provide economic and environmental services to millions of people as areas for recreation, sources of food, jobs, and shoreline protection; and are now under threat from multiple stresses (NOAA 2002). Anthropogenic impact from acute physical events such as commercial vessel grounding and anchor drags have been well documented throughout the world and southeast Florida. However little data exist on the chronic effects of large commercial vessels anchoring on reef resources. The Port Miami commercial anchorage was designated circa 1927 and was delineated over approximately 700 acres of reef resources. Anchorage use, benthic resources, and substrate composition were surveyed to understand the impact commercial vessel anchoring activities have had. Survey sites included both random sites within the anchorage to understand the cumulative chronic effect of anchoring activity, as well as targeted surveys at recently anchored sites to understand the immediate impacts of those anchoring events. Survey data were also compared to anchorage use data to understand how vessel traffic patterns influenced impact. Results indicated that there was both significant differences at acute recent impact sites and chronic impact sites. Generally, Outer Reef chronic impact sites had more evidence of chronic impacts both in the benthic community and substrate composition than Inner Reef sites. Significant differences on Outer Reef included an increase in the percent cover of small rubble, a decrease in octocoral percent cover, and a decrease in the density of larger octocoral size classes. Significant differences on Inner Reef included a decrease in the number of scleractinian species present compared to control sites.
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Měření subjektivní duševní pohody učitelů na základní škole s využitím metody ukotvujících vinět / Measuring subjective well-being of teachers at elementary schools with using the anchoring vignette methodVlčková, Petra January 2016 (has links)
The diploma thesis deals with evaluation of subjective well-being of elementary school teachers with use of anchoring vignettes. General goal of the thesis is to research actual subjective well-being of teachers and find out what factors are affecting it. Theoretical part characterizes subjective well-being and its components, its interconnection with life satisfaction, quality of life and happiness. Theoretical part also consists of explanation of the anchoring vignettes method including description of its application in particular researches. Empirical part of the thesis uses an existing survey method called Diener's satisfaction with life scale supplemented by anchoring vignettes. The research refers to high level of subjective well-being among teachers. Some variables (eg. family status, work in city or village) which make differences between levels of satisfaction were found. Application of anchoring vignettes method confirmed results of self-assessing questions in most cases. Keywords: subjective well-being, life satisfaction, quality of life, anchoring vignette, teacher survey
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PKA Signaling in ABCA1 Function: A Role in Modulation of Cholesterol Efflux and Macrophage InflammationMa, Loretta T. K. January 2013 (has links)
Formation of lipid-laden macrophage foam cells and inflammation are the central components in the initiation and progression of atherosclerosis. ABCA1 is well established as an anti-atherogenic factor that facilitates cellular cholesterol and phospholipid efflux, promotes reverse cholesterol transport, and suppresses pro-inflammatory cytokine secretion. Through these functions, ABCA1 is capable of reducing the lipid burden in atherosclerotic plaque. PKA signaling is an integral factor in promoting many anti-atherogenic functions of ABCA1; however, mechanistic aspects of PKA signaling associated with ABCA1 remain poorly defined. Thus, the first part of this study investigates the involvement of spatially regulated PKA signaling in ABCA1 activities through the use of st-Ht31, a PKA de-anchoring peptide. It appears that de-anchoring PKA robustly increases ABCA1-mediated microparticle release, one of the cholesterol efflux pathways of ABCA1, and reverses macrophage foam cell formation. These results highlight the significance of subcellular compartmentalization of PKA signaling in ABCA1 functions and present PKA de-anchoring as a potential therapeutic strategy for atherosclerotic lesion regression. The second part of this study provides evidence that ABCA1 activates PKA and promotes the secretion of anti-inflammatory IL-10, a cytokine crucial for inflammation resolution. Furthermore, we provide evidence that this elevated PKA activity is the underlying mechanism in which macrophage ABCA1 promotes M2-like inflammatory response. Our results also suggest that ABCA1 activates PKA by regulating cholesterol, which poises macrophages towards an anti-inflammatory or M2-activated phenotype. Collectively, we demonstrate that PKA signaling plays a crucial multifactorial role in anti-atherogenic functions of ABCA1.
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Localisation et fonctions de la nucléoline au centrosome / Localisation and functions of nucleolin at the centrosomeGaume, Xavier 28 April 2014 (has links)
La nucléoline est une des protéines les plus abondantes des nucléoles. Ses fonctions ne sont cependant pas restreintes à la biogénèse des ribosomes. En absence de nucléoline, un phénotype d’amplification du nombre de centrosomes en mitose, associé à des fuseaux multipolaires a été récemment rapporté. Notre étude vise à comprendre l’implication de la nucléoline dans l’apparition de ce phénotype et notamment ses conséquences sur l’organisation des microtubules.Par immunofluorescence, nous mettons en évidence que la fraction centrosomale de la nucléoline est spécifiquement associée au centriole mature en interphase, alors qu’en mitose seule une forme phosphorylée y est détectée.En interphase, les cellules déplétées en nucleoline présentent une amplification de leurs centrioles immatures, entourés par un réseau anormal de péricentrine, dénotant une perte de structuration de la matrice péricentriolaire. De plus, une désorientation du réseau microtubulaire causée par une capacité de nucléation ralentie et une perte d’ancrage des microtubules au centrosome mature est observée. Par des expériences de co-immunoprécipitation avec la tubuline γ, un lien avec le complexe d’initiation de la nucléation des microtubules est dévoilé.En conclusion, les résultats de ma thèse révèlent que structurellement la nucléoline est associée au centriole mature des cellules en interphase et que fonctionnellement elle stimule la nucléation des microtubules et participe à leur ancrage au centrosome mature pour orienter le réseau microtubulaire en interphase. La nucléoline pourrait ainsi être un des acteurs de la synchronicité entre centrosomes et nucléoles pour la régulation du cycle cellulaire. / Nucleolin is an abundant non-ribosomal protein of the nucleolus. Nevertheless its functions are not restricted to ribosome biogenesis. Without nucleolin, a phenotype of abnormally high centrosome numbers was recently reported in mitosis, associated with multipolar spindle formation. The purpose of our study is to understand nucleolin’s involvement in the appearance of this phenotype and specifically consequences on microtubule network organisation. By immunofluorescence, visual evidences of a centrosomal fraction of nucleolin are provided, specifically associated with the mature centriole of interphase cells. In mitosis, only a phosphorylated form of nucleolin is detected at the spindle poles.In interphase, nucleolin depleted cells exhibit immature centriole amplification surrounded by an abnormal mesh of pericentrine, showing a loss of pericentriolar matrix structuration. Furthermore, in most nucleolin depleted cells, a complete disorganisation of microtubule network is observed, caused by a slower microtubule nucleation capacity and a loss of microtubule anchoring at the mature centriole. Using co-immunoprecipitation with γ-tubulin, a major centrosomal protein, a link with the microtubule nucleation complex was highlighted.Taken together my thesis results reveal that in interphase cells, nucleolin is structurally associated with the mature centriole, and functionally stimulates microtubule nucleation and participates in their anchoring at the mature centrosome to orient microtubule network. Thus, nucleolin could be a major actor in the synchronicity between centrosome and nucleoli for cell cycle regulation.
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