Orientador: Caio Lucidius Naberezny Azevedo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-24T12:51:18Z (GMT). No. of bitstreams: 1 Ferreira_EduardoVargas_M.pdf: 8131052 bytes, checksum: f344cd1f11e8d818f3aac90f48396cbc (MD5) Previous issue date: 2014 / Resumo: No presente trabalho propõem-se novos modelos da Teoria de Resposta ao Item para respostas politômicas nominais e ordinais (graduais), via dados aumentados, para grupos múltiplos. Para a modelagem das distribuições dos traços latentes de cada grupo, considera-se normais assimétricas centradas. Tal abordagem, além de acomodar a característica de assimetria aos dados, ajuda a garantir a identificabilidade dos modelos estudados, a qual é tratada tanto sob a ótica frequentista quanto bayesiana. Com relação aos métodos de estimação, desenvolveu-se procedimentos bayesianos através de algoritmos de Monte Carlo via cadeias de Markov (MCMC), utilizando o algoritmo de Gibbs (DAGS), com a verossimilhança aumentada (dados aumentados) e Metropolis-Hastings, considerando a verossimilhança original. As implementações computacionais foram escritas em linguagem C++, integradas ao ambiente computacional, gráfico e estatístico R, viabilizando rotinas gratuitas, de código aberto e alta velocidade no processamento, essenciais à difusão de tais metodologias. Para a seleção de modelos, utilizou-se o critério de informação deviance (DIC), os valores esperados do critério de informação de Akaike (EAIC) e o critério de informação bayesiano (EBIC). Em relação à verificação da qualidade do ajuste de modelos, explorou-se a checagem preditiva a posteriori, que fornece meios concretos de se avaliar a qualidade do instrumento de medida (prova, questionário etc), qualidade do ajuste do modelo de um modo global, além de indícios de violações de suposições específicas. Estudos de simulação, considerando diversas situações de interesse prático, indicam que os modelos e métodos de estimação produzem resultados bastante satisfatórios, com superioridade dos modelos assimétricos com relação ao simétrico (o qual assume simetria das distribuições das variáveis latentes). A análise de um conjunto de dados reais, referente à primeira fase do vestibular da UNICAMP de 2013, ilustra o potencial da tríade: modelagem, métodos de estimação e ferramentas de diagnósticos, desenvolvida neste trabalho / Abstract: In this work, we propose new Item Response Theory models for nominal and ordinal (gradual) polytomous responses through augmented data schemes considering multiple groups. For the distribution of the latent traits of each group, we consider a skew-normal distribution under the centered parametrization. This approach will allow for accommodating a possible skewness of the latent trait distribution, but is also helpful to ensure the identifiability of the models, which is studied under frequentist and Bayesian paradigms. Concerning estimation methods, we developed Bayesian methods through Markov chain Monte Carlo (MCMC) algorithms by using the Gibbs algorithm (DAGS), with augmented likelihood (augmented data) and Metropolis-Hastings algorithms, considering the original likelihood. The computational environment was written in the C++ language and integrated with the R program (a statistical computational and graphical environment), allowing for free, open source and high-speed routines which, in turn, are essential to the dissemination of the developed methodologies. In terms of model selection, we considered the deviance information criterion (DIC), the expected Akaike information criterion (EAIC) and expected Bayesian information criterion (EBIC). Regarding model-fit assessment tools, we explore the posterior predictive model- checking which allows for assessing the quality of measurement, instruments (tests, questionnaires, and others), the model fit in a global sense, besides providing directions toward violations of specific assumptions. Simulation studies, considering different situations of practical interest, indicate that the models and estimation methods produced reasonable results, with outperformance of skew models when compared to symmetric ones (which assumes symmetry of the latent trait distribution). Analysis of a data set which corresponds to the first phase of the 2013 written examination of UNICAMP (State University of Campinas), illustrates the potential of the following triad: modelling; estimation methods; and diagnostic tools developed in this work. / Mestrado / Estatistica / Mestre em Estatística

This Thesis in Military Technology deals with experiences drawn from the forced introduction of Weapons Station 01, 2009. The work aims to identify the experiences regarding the forced procurement of military equipment to see how they can develop normal and fast procurement of equipment. The main conclusions of  this work, is to achieve greater capability and increase the military utility, are:   -          Common objectives and priorities of stakeholders -          Response and joint types shall determine requirements for system -          Ensure an integrated project team also at lower levels -          Engage the integrated logistic support early in the materiel process -          Include Armed Forces staff as early as possible in the testing and validation -          Prioritize work to facilitate the rapid development of decision on use (BOA) -          Provide back up for increased redundancy in the mission area

This work presents the result of a research that had as objective to examine how were prescribed the geometric knowledge for the formation of primary teachers in Sergipe in the period from 1890 to 1944. For this, the sources used were official documents like Decrees, Laws, Regulations, Teaching programs and pedagogical journals in order to identify and characterize geometric knowledge in the training of primary teachers. They were consulted as reference: Valente (2005, 2013) regarding the understanding about the production in history of mathematical education; Leme da Silva (2015) on the understanding of geometric knowledge; Chervel (1990) on the constituents and purposes of a discipline, among other authors. Initially, the research used the documentary study, examining sources from the period from 1890 to 1931, with the purpose of understanding and identifying the geometric knowledge in the formation of normalists in the period before the 1930s. made it possible to compare the geometric knowledge that was proposed for the Normal Course and the Primary Course. According to the Teaching Programs, the geometric knowledge in the Primary Course constituted the subject / discipline Drawing (Linear Design), being recommended in some moments by means of the free drawing, the drawing of geometric figures and, in Arithmetica, approaching "surface , perimeter, area evaluation, relation between diameter and circumference "; for the Normal Course, the geometric knowledge had a more specific treatment with a level of deepening, for example, in relation to the treatment of theories like: "theory of perpendiculars"; "Theory of parallels"; "Polygonos theory". With regard to the teaching method proposed, at the time in Sergipe, we can highlight two moments: the first in the period of 1890 - 1930, whose teaching method recommended in the official documents were intuitive; and the period 1930-1940, with indications of the change of method, going to the active method. The latter can be identified in the guidelines proposed to teachers, under two scopes: in the pedagogical magazines located in the collection of the Epifânio Dórea Library (which probably circulated in this State) and in the organization of geometric knowledge, from the Teaching Programs. / Este trabalho apresenta o resultado de uma pesquisa que teve por objetivo examinar como eram prescritos os saberes geométricos para a formação de professores primários em Sergipe no período de 1890 a 1944. Para isso, as fontes utilizadas foram documentos oficiais como Decretos, Leis, Regulamentos, Programas de Ensino e revistas pedagógicas a fim de identificar e caracterizar os saberes geométricos na formação dos professores primários. Foram consultados como referência: Valente (2005, 2013) quanto ao entendimento sobre a produção em história da educação matemática; Leme da Silva (2015) acerca do entendimento de saberes geométricos; Chervel (1990) sobre as constituintes e finalidades de uma disciplina, dentre outros autores. Inicialmente, a pesquisa recorreu ao estudo documental, examinando fontes do período de 1890 a 1931, com o intuito de compreender e identificar quais e como se apresentavam os saberes geométricos na formação de normalistas no período anterior à década 1930. O exame das fontes desse período possibilitou tecer uma comparação entre os saberes geométricos que eram propostos para o Curso Normal e Curso Primário. De acordo com os Programas de Ensino, os saberes geométricos no Curso Primário constituíam a matéria/disciplina Desenho (Desenho Linear), sendo recomendado, em alguns momentos por meio do desenho livre, o traçado de figuras geométricas e, em Arithmetica, abordando “superfície, perímetro, avaliação das áreas, relação entre diâmetro e circunferência”; para o Curso Normal, os saberes geométricos tinham um tratamento mais específico com um nível de aprofundamento, por exemplo, em relação ao tratamento de teorias como: “theoria das perpendiculares”; “teoria das paralelas”; “teoria dos polygonos”. Com relação ao método de ensino proposto, à época em Sergipe, pode-se destacar dois momentos: o primeiro no período de 1890 – 1930, cujo método de ensino recomendado nos documentos oficiais eram o intuitivo; e o período de 1930 – 1940, com indícios da mudança de método, passando ao método ativo. Esse último, pode ser identificado nas orientações propostas aos professores, sob dois âmbitos: nas revistas pedagógicas localizadas no acervo da Biblioteca Epifânio Dórea (as quais, provavelmente circularam neste Estado) e na organização dos saberes geométricos, a partir dos Programas de Ensino. / São Cristóvão, SE

Orientador: Víctor Hugo Lachos Dávila / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-26T19:55:07Z (GMT). No. of bitstreams: 1 Massuia_MoniqueBettio_M.pdf: 2926597 bytes, checksum: 2a1154c0a61b13f369e8390159fc4c3e (MD5) Previous issue date: 2015 / Resumo: Este trabalho tem como objetivo principal apresentar os modelos de regressão lineares com respostas censuradas sob a classe de distribuições de mistura de escala skew-normal (SMSN), visando generalizar o clássico modelo Tobit ao oferecer alternativas mais robustas à distribuição Normal. Um estudo de inferência clássico é desenvolvido para os modelos em questão sob dois casos especiais desta família de distribuições, a Normal e a t de Student, utilizando o algoritmo EM para obter as estimativas de máxima verossimilhança dos parâmetros dos modelos e desenvolvendo métodos de diagnóstico de influência global e local com base na metodologia proposta por Cook (1986) e Poom & Poon (1999). Sob o enfoque Bayesiano, o modelo de regressão para respostas censuradas é estudado sob alguns casos especiais da classe SMSN, como a Normal, a t de Student, a skew-Normal, a skew-t e a skew-Slash. Neste caso, o amostrador de Gibbs é a principal ferramenta utilizada para a inferência sobre os parâmetros do modelo. Apresentamos também alguns estudos de simulação para avaliar a metodologia desenvolvida que, por fim, é aplicada em dois conjuntos de dados reais. Os pacotes SMNCensReg, CensRegMod e BayesCR para o software R dão suporte computacional aos desenvolvimentos deste trabalho / Abstract: This work aims to present the linear regression model with censored response variable under the class of scale mixture of skew-normal distributions (SMSN), generalizing the well known Tobit model as providing a more robust alternative to the normal distribution. A study based on classic inference is developed to investigate these censored models under two special cases of this family of distributions, Normal and t-Student, using the EM algorithm for obtaining maximum likelihood estimates and developing methods of diagnostic based on global and local influence as suggested by Cook (1986) and Poom & Poon (1999). Under a Bayesian approach, the censored regression model was studied under some special cases of SMSN class, such as Normal, t-Student, skew-Normal, skew-t and skew-Slash. In these cases, the Gibbs sampler was the main tool used to make inference about the model parameters. We also present some simulation studies for evaluating the developed methodologies that, finally, are applied on two real data sets. The packages SMNCensReg, CensRegMod and BayesCR implemented for the software R give computational support to this work / Mestrado / Estatistica / Mestra em Estatística

A dissertação apresenta uma pesquisa que se situa no campo da História da Educação Matemática e que tomou por objeto de estudo a formação dos professores primários no Instituto de Educação General Flores da Cunha (IE), em Porto Alegre. Dialogando com autores da Histórica Cultural e da Histórica Oral busca-se compreender os modos de apropriação, aprender para ensinar os saberes matemáticos na instituição nas décadas de 1950 a 1970, período caracterizado pelo Movimento da Matemática Moderna (MMM). Inferiu-se, a partir das evidências verificadas em documentos localizados no acevo do Laboratório de Matemática da instituição e das entrevistas realizadas com as ex-alunas e ex-professoras, que o MMM norteou a formação das normalistas. Tal movimento materializou-se nas ações das professoras e estudantes que aprendiam e ensinavam a Moderna Matemática, nos materiais didáticos estudados e produzidos pelas normalistas no Laboratório de Matemática da instituição, bem como nos discursos das ex-alunas e da imprensa da época. Evidenciou-se que o envolvimento das normalistas com a renovação da Matemática, no interior do IE, partiu, inicialmente, das inquietações e ações da professora Odila Barros Xavier que almejava mudanças no ensino da Matemática desde o final da década de 1940. Na época, a professora já estudava mudanças no currículo da Matemática do Curso Normal, na incansável busca pela renovação na formação das professoras primárias Através da fundação e organização do Laboratório de Matemática, a partir dos anos 1950, a professora Odila amplia os espaços de formação de professores para além das portas do IE e contribui para a divulgação do pensamento modernizador, coordenando grupos de estudos, ministrando cursos sobre fundamentação teórica e metodológica da Matemática Moderna e incentivando práticas em aulas experimentais com materiais manipuláveis. O ápice deste percurso ocorre no final dos anos 1960 e início dos anos 1970 que, por conseguinte, é fundado o Grupo de Estudos sobre o Ensino da Matemática de Porto Alegre (GEEMPA), sob a liderança da professora Esther Grossi. Através do GEEMPA foram oportunizados cursos de formação de professores com a presença de vários estudiosos, entre eles, Zoltan Dienes, um dos principais autores estudados no Instituto de Educação General Flores da Cunha. Ao longo dos anos 1950 e 1970, a instituição tornou-se referência não só na formação inicial das normalistas, mas também na formação continuada dos professores de Matemática no Rio Grande do Sul, com reconhecimento nacional e internacional, no período marcado pelo MMM. / The dissertation presents a research that is located in the field of History of the Mathematics Education and that took as object of study, the formation of primary teachers at the Flores da Cunha (IE) General Education Institute in the city of Porto Alegre. In dialogue with authors from Cultural, Historical and Oral History, we sought to understand the ways of appropriation to learn how to teach the mathematical knowledge in the institution from 1950 to 1970, a period characterized by the Modern Mathematical Movement (MMM). We infer from the evidence verified in documents located in the acquis from the Laboratory of Mathematics from the institution and the interviews with the former students and the former teachers, that the MMM guided the formation of the normalists. This movement materialized in the actions of the teachers and students who learned and taught Modern Mathematics, in the didactic materials studied and produced by the normalists in the Mathematics Laboratory of the institution, as well as in the speeches of the former students and the press of the time. It was evidenced that the involvement of the normalists with the renewal of Mathematics, within IE, started, initially, from the concerns and the actions of the teacher Odila Barros Xavier, who aspired for changes in the teaching of Mathematics since the end of the 1940s At the time, the teacher was already studying changes in the curriculum of Normal Mathematics Course, in the relentless search for renewal in the training of primary teachers. Through the founding and organization of the Mathematics Laboratory, from the 1950s on wards, teacher Odila expanded the spaces for teacher training beyond IE's doors and contributed to the dissemination of modernizing thinking, coordinating study groups, giving courses on fundamentals theoretical and methodological approach of Modern Mathematics and encouraging practices in experimental classes with manipulative materials. The culmination of this course takes place in the late 1960s and early 1970s, which is why the Mathematics Teaching Group of Porto Alegre (GEEMPA) was founded under the leadership of teacher Esther Grossi. Through the GEEMPA, teacher training courses were offered in the presence of several scholars, among them Zoltan Dienes, one of the main authors studied at the Flores da Cunha General Education Institute. Throughout the 1950s and 1970s, the institution became a reference not only in the initial formation of the normalists, but also in the continuing formation of Mathematics teachers in Rio Grande do Sul, with national and international recognition, during the period marked by the MMM.

No description available.

Le vieillissement normal peut être accompagné par un déclin cognitif incluant une diminution du contrôle attentionnel, une fonction exécutive nous permettant de concentrer notre attention tout en inhibant les distractions. De plus, des études antérieures ont démontré que la musique de fond peut améliorer certaines fonctions exécutives, autant chez les jeunes que chez les personnes âgées. Sachant que le vieillissement normal est caractérisé par un déclin du contrôle attentionnel qui n’est pas observé chez leurs cadets, cette étude vise à explorer si l’effet de la musique de fond sur le contrôle attentionnel est le même chez les personnes âgées et les jeunes adultes. Pour ce faire, 19 personnes âgées (62 à 74 ans) ainsi que 21 jeunes adultes (20 à 32 ans) ont effectué la tâche flanker d’Eriksen, qui évalue le contrôle attentionnel, dans trois conditions : en écoutant de la musique de fond stimulante, relaxante et en silence. Comme attendu, les temps de réaction étaient plus lents pour les essais non congruents que pour les essais congruents. Cette différence, appelée l’effet flanker, était significativement plus grande sous la condition de musique relaxante comparativement aux deux autres conditions. De plus, l’effet flanker était le même dans les deux groupes d’âge. Pour conclure, la musique relaxante nuit au contrôle attentionnel des personnes âgées et des jeunes adultes, comparativement à la musique stimulante et au silence. / Normal aging can be accompanied by a cognitive decline including a decrease in attentional control, an executive function allowing us to focus attention while inhibiting distractors. Also, previous studies demonstrated that background music can enhance some executive functions, both in young and older adults. Knowing that normal aging is characterised by a decline in attentional control that is not observed in their younger peers, this study aims to explore if the effect of background music on attentional control is the same in older and young adults. To do so, 19 older adults (62-74) as well as 21 young adults (20-32) performed the Eriksen’s flanker task, evaluating attentional control, under the exposition of three conditions: stimulating and relaxing music and silence. As expected, reaction time (RT) was slower for the incongruent trials and faster for the congruent ones. However, this difference, called the flanker effect, was significantly greater under the relaxing music condition compared to others, due to a combination of much slower RT in incongruent trials and faster RT in congruent ones. The flanker effect was the same in both age groups. In conclusion, relaxing music impairs attentional control of older and young adults compared to stimulating music and silence.

It is a well-known problem that concrete needs to be made more efficient and that it is the large consumption of cement that is the major contributing factor to the nearby need. There is a zero vision of a climate-neutral concrete where all CO2 emissions in the life cycle of the concrete are to be reset by 2050. It is a question of improving, above all, the process of handling CO2 in the production of cement. This study tackles CO2 emissions from the concrete from a holistic perspective, by exploring optimization possibilities when implementing a newly developed concrete in residential buildings, called Ultra High Performance Concrete (UHPC). While it should be a better alternative for the climate, it should also require less material consumption and be more cost-effective in order to create a competitive alternative to the conventional alternative today, called Normal Concrete (NC). UHPC is during a development phase regarding optimization opportunities and it has been proven in several studies to be able to relate better to a sustainable design, based on a total life cycle progression. This applies above all to large and robust bridge structures where large volume differences are available. The idea behind this study is to highlight the question of whether there is an opportunity to get similar results in the construction of less robust components in residential buildings, since the problem with the mix design for UHPC has been the overall high cost in relation to NC. In recent years, this cost has been reduced and now there are opportunities to effectively introduce UHPC into another segment.In this study, columns and beams were dimensioned in a residential NC building and a residential UHPC building with ETABS (CSI 2019). Furthermore, the components of the buildings were compared, based on the aspect of a sustainable design from a total LCA. What was investigated were the differences in total material consumption, CO2 emissions, and costs.The study showed that the UHPC components were better based on all aspects after its total LCA. The total cement consumption was larger, but the building received at the same time an estimated double the lifespan of the NC- building. The total material consumption in the form of total component volumes became smaller, the total annual CO2 emissions became smaller and the total annual costs became smaller as well. / Det är ett välkänt problem att betong behöver klimateffektiviseras och att det är den storacementkonsumtionen som är den stora bidragande faktorn till det närliggande behovet. Detfinns en nollvision om en klimatneutral betong där alla CO2- utsläpp under betongenslivscykel (LCA), ska nollställas fram till år 2050. Det är en fråga om att framför allt förbättraprocessen gällande hantering av CO2 vid produktion av cement. Den här studien angriperCO2- utsläppen från betongen ur ett helhetsperspektiv, genom att undersökaoptimeringsmöjligheter vid implementering av en nyutvecklad betong i bostadshus, kalladUltra High Performance Concrete (UHPC). Samtidigt som den ska vara ett bättre alternativför klimatet, ska den också kräva mindre materialåtgång och vara mer kostnadseffektiv föratt kunna skapa ett konkurrenskraftigt alternativ till det konventionella alternativet idag,kallad Normal Concrete (NC). UHPC är under en optimeringsfas och den har bevisats i flerastudier kunna förhålla sig bättre till en hållbar design, utifrån en total LCA. Det gäller framförallt stora och robusta brokonstruktioner där stora volymskillnader är disponibla. Tankenmed den här studien är att lyfta fram frågan om det finns möjlighet att få liknande resultatvid byggnation av mindre robusta komponenter i bostadshus, i ju med att problemet medmix-designen för UHPC, har varit den generella höga kostnaden i förhållande till NC. Påsenare år har den kostnaden kunnat reduceras och nu finns möjligheterna att effektivtkunna införa UHPC till ytterligare ett segment.I studien jämfördes pelare och balkar i ett UHPC- hus med motsvarande komponenter i ettNC- hus utifrån aspekten en hållbar design, ur en total LCA. Husen dimensionerades i ETABS(CSI 2019) utefter samma förutsättningar med hänsyn till kravet på bärförförmågorna. Detutgjorde skillnader hos volymerna på komponenterna, som således påvisade hurmaterialåtgången förändrades. CO2- utsläppen och kostnaderna påverkades avbetongkompositionerna och skillnaderna hos de materiella egenskaperna av respektivebetongtyp. I slutändan redovisades vilken betongtyp som genererade minsta och störstaårliga CO2- utsläpp och kostnader.Resultatet visade att UHPC- komponenterna minskade den totala betongåtgången underbyggprocessen med 27,1%, samt minskade armeringsåtgången med 12,0%, men attcementåtgången nästan fördubblades och motsvarade en ökning på 99,4%. CO2- utsläppenvart således betydligt större efter byggprocessen, men i förhållande till ett totaltlivcykelförlopp, minskade de totala årliga utsläppen med 18,8%. Det fanns en kritisk punktdär UHPC- komponenterna måste ha en LCA på minst 97,5 år i förhållande till NCkomponenternas LCA på 60 år, för att vara mer lönsamma utifrån totala CO2- utsläpp.Kostnaderna vart också betydligt större för UHPC- komponenterna efter byggprocessen,men efter en total LCA, minskade de totala kostnaderna med 39,0%. Det fanns en kritiskpunkt, där LCA- förloppet måste uppgå till minst 73,2 år i förhållande till NCkomponenternas LCA på 60 år, för att vara mer lönsamma utifrån totala kostnader.Enligt det framtagna resultatet fanns det goda möjligheter för pelare och balkar i UHPChuset att förhålla sig bättre utifrån en hållbar design, än vad motsvarande komponenter förNC- huset gjorde, efter en total LCA. Pelare och balkar i bostadshus kan bli ett nytt segmentatt introducera UHPC till, även om pålitligheten för studien är begränsad av betydelsefullafelkällor och tillgängliga kunskaper inom området för närvarande.

Les plaques amyloïdes, composées d’agrégats de protéines bêta-amyloïde, sont l’un des principaux marqueurs physiopathologiques de la maladie d’Alzheimer et peuvent s’accumuler jusqu’à trois décennies avant les premiers signes cliniques. Il n’est pas encore bien établi dans quelle mesure le vieillissement cognitif normal pourrait dépendre de la présence de cette pathologie cérébrale. Par ailleurs, la réserve cognitive reflète le décalage parfois observé entre le niveau de pathologie et les manifestations cliniques de démence. En plus d’être associée à un risque réduit de développer une maladie neurodégénérative, la réserve cognitive rend compte d’une susceptibilité réduite de présenter un déclin cognitif associé au vieillissement normal. Cependant, la littérature demeure mitigée quant à l’effet protecteur de la réserve cognitive face à une charge amyloïde élevée à un stade où la cognition est cliniquement normale. L’objectif général de cette thèse était donc d’acquérir une meilleure compréhension de la relation entre la charge amyloïde, la cognition et la réserve cognitive au sein du vieillissement normal. Cette question de recherche a été étudiée grâce à la participation d’un groupe de 104 personnes âgées (77 femmes, âge moyen de 73 ans). Suivant une procédure de dépistage permettant de recruter uniquement des aînés sans trouble cognitif, une batterie d’épreuves neuropsychologiques a été administrée à partir de laquelle une mesure de mémoire épisodique a été extraite. Puis, l’imagerie par résonance magnétique et la tomographie par émission de positons ont permis d’établir la charge amyloïde de chaque participant. La première étude avait comme objectif de documenter chez cette population, d’une part, l’impact de la charge amyloïde sur l’efficience de la mémoire épisodique, et d’autre part, l’effet de la scolarité sur cette relation. Les résultats de cette étude ont permis d’appuyer l’idée que la performance en mémoire épisodique est associée à la charge amyloïde, relation qui est modérée par la scolarité. Plus précisément, cette association demeure significative jusqu’à 13.5 années d'études, alors qu’au-delà de ce seuil, la pathologie n’a plus d’impact sur les performances en mémoire. Ce résultat est cohérent avec celui démontrant que les performances en mémoire épisodique des participants ayant un diplôme d’études secondaires et collégiales étaient significativement affectées par les dépôts amyloïdes comparativement au groupe d’universitaires. La deuxième étude visait à évaluer l’effet protecteur d’autres proxys de réserve cognitive reconnus comme pouvant compenser les effets de l’âge et d’une pathologie cérébrale, soit la profession, le vocabulaire et les activités cognitivement stimulantes liées au style de vie. L’effet de différents indexes composites de réserve ont aussi été examinés. Lorsque considérés individuellement, seule la profession modère significativement la relation entre la charge amyloïde et la mémoire épisodique. Enfin, la combinaison de la profession et de la scolarité démontre la plus grande taille d'effet relativement à la modération de l’impact du fardeau amyloïde sur la mémoire épisodique. Cette thèse met en évidence l’impact de la charge amyloïde sur l’efficience de la mémoire épisodique dans le vieillissement normal. Néanmoins, les personnes âgées cognitivement normales ayant une réserve cognitive mieux développée seraient protégées contre l’effet délétère qu’entraîne cette pathologie sur la mémoire épisodique. / Amyloid plaques, aggregates of beta-amyloid proteins, are one of the main pathophysiologic markers of Alzheimer's disease and can accumulate up to three decades before the first clinical signs. It is unclear to what extent normal cognitive aging might depend on the presence of this brain pathology. Furthermore, cognitive reserve reflects the discrepancy that can be observed between the level of pathology and the clinical manifestations of dementia. In addition to being associated with a reduced risk of developing a neurodegenerative disease, cognitive reserve accounts for the reduced susceptibility to cognitive decline associated with aging. However, whether cognitive reserve may help withstand the effect of high amyloid load among cognitively normal older adults is still unclear. The general objective of this thesis was therefore to gain a better understanding of the relationship between amyloid load, cognition and cognitive reserve in normal aging. This research question was investigated through a sample of 104 older adults (77 women, mean age 73 years). Following a screening procedure which allowed to recruit only older adults with clinically normal cognition, a battery of neuropsychological tests was administered from which a measure of episodic memory was extracted. Participants underwent magnetic resonance imaging and positron emission tomography in order to quantify beta-amyloid load in each participant. The first study aimed to better characterize in this population, on the one hand, the impact of amyloid deposition on the efficiency of episodic memory, and on the other hand, the effect of education against this pathology. Performance in episodic memory was significantly associated with amyloid load, and this relationship was moderated by education. More precisely, the association remained significant up to 13.5 years of education, whereas beyond this threshold, amyloid load no longer had an impact on episodic memory performances. This result is consistent with the fact that the episodic memory performance of participants with a high school and college diploma were significantly affected by amyloid deposits compared to participants with a university degree. The second study aimed to investigate the protective effect of cognitive reserve against amyloid burden by means of other well-documented proxies of cognitive reserve that help better cope with age or pathology, such as occupation, vocabulary and cognitively stimulating lifestyle activities. The effect of different composite indexes of cognitive reserve was also examined. Taken individually, only occupation significantly moderated the relationship between amyloid load and episodic memory. In addition, when combined with education, this composite index of cognitive reserve demonstrated the largest effect size relatively to the moderation of the impact of amyloid burden on episodic memory. This thesis highlights the impact of amyloid load on episodic memory efficiency in normal aging. Furthermore, cognitively normal older adults with higher cognitive reserve appear to be protected against the deleterious effect of amyloid load on episodic memory.

About 1.5 years after the first Covid-19 lockdown, it is clear there will not be an "as before” anymore. New standards have been established among project managers in the German news media industry and hybrid and virtual working has become the New Normal. In this study, nine project managers from German news media organisations have shared their experiences on the Covid-19 pandemic. The main takeaway is that pragmatism and agile principles have been beneficial for the project managers in uncertain times. The role of a successful project manager has seen a shift towards being a facilitator who gives structure to the team but enables it to work more efficiently through communication and building strong trust. / Runt 1,5 år efter den första Covid-19-lockdown står det klart att det inte kommer att bli något "som förut" längre. Nya standarder har etablerats bland projektledare i den tyska nyhetsmediebranschen och hybrid och virtuellt arbete har blivit det Nya Normala. I den här studien har nio projektledare från tyska nyhetsmedieorganisationer delat med sig av sina erfarenheter av Covid-19-pandemin. Den viktigaste slutsatsen är att pragmatism och agila principer har varit till nytta för projektledarna i osäkra tider. Rollen som framgångsrik projektledare har förändrats till att bli en facilitator som ger teamet struktur och som gör det möjligt för teamet att arbeta mer effektivt genom kommunikation och att bygga upp ett starkt förtroende.