Cette thèse porte sur les décompositions en ondelettes M-bandes en arbre dual ainsi que sur leur application à l'analyse et la restauration d'images. Ces décompositions permettent d'obtenir une analyse multi-échelles, directionnelle et locale des images. Elles s'inscrivent donc dans la perspective de travaux récents visant à mieux représenter les informations géométriques (textures, contours) et les préserver lors de traitements. Ce travail s'appuie sur les travaux antérieurs de N. Kingsbury et I. Selesnick portant sur la construction de décompositions en ondelettes formant des paires de Hilbert (approchées). Ces auteurs ont établi divers résultats concernant le cas dyadique et l'une de nos contributions a été de montrer qu'il était possible de généraliser leurs conclusions et de montrer de nouveaux résultats dans le cas M-bandes. Les représentations proposées présentent de nombreux avantages notamment en termes d'invariance par translation de l'analyse et de sélectivité directionnelle. Nous avons établi les conditions que doivent satisfaire les bancs de filtres en arbre dual servant à l'analyse et à la synthèse des signaux traités. Nous avons également étudié les pré-traitements qu'il est nécessaire d'appliquer à des données discrètes. Ces décompositions introduisant typiquement une redondance d'un facteur 2 (dans le cas réel, et de 4 dans le cas complexe), elles constituent des trames à partir desquelles on peut calculer une reconstruction optimale. Ces nouvelles transformées ont finalement été généralisées aux cadres biorthogonal et complexe. Notre volonté d'appliquer ces outils d'analyse au débruitage de signaux nous a conduit à l'étude des propriétés statistiques des coefficients issus de la décomposition M-bandes en arbre dual d'un processus aléatoire stationnaire au sens large. Nous avons tout d'abord calculé les statistiques au second ordre de ces coefficients et nous avons étudié le rôle du post-traitement dans le calcul des corrélations. Quelques résultats asymptotiques concernant les corrélations d'un couple de coefficients primal/dual ont également été obtenus. Les inter-corrélations entre les ondelettes primale et duale jouant un rôle clé dans notre étude, nous en avons fourni des expressions exactes pour quelques familles d'ondelettes usuelles. Des simulations numériques nous ont aussi permis de valider nos résultats théoriques ainsi que d'évaluer la zone d'influence de la dépendance statistique induite. Pour démontrer l'efficacité de ces décompositions, nous avons été amenés à nous intéresser à deux types de problèmes : le débruitage et la déconvolution d'images. En ce qui concerne le débruitage, nous avons poursuivi deux buts principaux liés au cheminement de la thèse. Dans un premier temps, nous nous sommes attachés à montrer que la décomposition en arbre dual M-bandes apporte un gain significatif en terme de qualité, à la fois objective et subjective, par rapport à une décomposition en ondelettes classique, voire une décomposition dyadique en arbre dual. Dans un second temps, nous avons considéré le débruitage d'images multi-canaux pour lesquelles nous avons mis en place un estimateur statistique original reposant sur l'emploi du principe de Stein et permettant notamment de prendre en compte des voisinages quelconques (spatial, intercomposantes, inter-échelles, ...). Les problèmes de déconvolution d'images ont été appréhendés dans le cadre de méthodes variationnelles, en mettant en place un algorithme itératif, utilisant des outils récemment développés en analyse convexe. L'approche proposée permet de résoudre des problèmes inverses associés à des modèles probabilistes variés et elle est applicable à l'analyse M-bandes en arbre dual ainsi qu'à tout autre type de représentation à l'aide d'une trame.

The lumen-to-cell transport, cellular accumulation, and toxicity of ionic cadmium (109Cd2+) and cadmium-cysteine conjugate (Cys-S-109Cd-S-Cys) were studied in isolated perfused S2 segments of the proximal tubule of the rabbit kidney. All perfusion solutions were HEPES buffered and contained 3H-L-glucose which functioned as a volume and leak marker along with 250 nM FD & C Green dye as a vital dye. When ionic cadmium, 0.73µM Cd2+, or 0.73µM cadmium-cysteine conjugate (Cys-S-109Cd-S-Cys) containing solution was perfused through the lumen of the tubule there was no visual evidence of toxicity such as blebbing of the luminal membrane, cellular vital dye uptake, and cellular swelling. Ionic Cd2+ transport was temperature dependent (87% reduction at 22°C and 100% at 11°C) and inhibited by FeCl2 (42% reduction at 10µM) and ZnCl2 (48% reduction at 20µM), and high Ca2+ concentrations (27% reduction at 1.95mM and 69% at 2.6mM). The ionic Cd2+ transport was not affected by verapamil and diltiazem. The cadmium conjugate (Cys-S-Cd-S-Cys) transport was also temperature dependent (76% reduction at 22°C and 100% at 11°C) and inhibited by the amino acids L-cystine and L-arginine (55% and 50% respectively), stimulated by L-methionine (56%), but not affected by L-aspartate, L-glutamate and Gly-Sar. 2, 3-Dimercaptopropane-1-Sulfonate (DMPS) co-perfused with Cd2+ decreased absorption of 20µM Cd2+ (39% reduction at 30 µM and 94.6% reduction at 200 µM), while DMPS added to the bathing solution has no effect on the luminal transport of Cd2+. DMPS co-perfused with 20 µM Cys-S-Cd-S-Cys substantially reduced Cd2+ transport (62% reduction at 30 µM). We conclude that cadmium can be transported at the luminal membrane of the S2 segment of the proximal tubule by multiple mechanisms, depending on the form which it is presented to membrane. Ionic cadmium appears to be transported by iron (DCT1), zinc (ZTL1) transporters and some kind of calcium-selective channel while cadmium conjugate of L-cysteine appears to be transported by L-cystine transporters (system b0+). Dipeptide transporter is not involved in the transport of cadmium. DMPS appears to be a chelator for cadmium.

The aim of this thesis was to describe teenage girls’ experiences and perceptions of participation and influence during learning processes. The UN Convention on the Rights of the Child and the view that children are social actors with their own agency were central to the study. The girls, who were 13 years old when the study began, and 16 when it ended, were interviewed once per semester for three years. Classroom observations formed the basis of the interviews, which provided insight into the learning environment and its working methods. These, in turn, were discussed during the interviews. Nine girls were selected through the IEPs that the school had established for them. They attended regular classes for most of the school day, but received at least one session of special education in smaller groups each week. Their special needs were due to reading and writing difficulties. All of them received special support in English, while seven of the girls also received special support in mathematics. The girls described current events in their life, regarding both school and their spare time, as well as their thoughts about the future, and how efforts to accommodate their special educational needs have affected their schooling. In addition to the girls’ narratives, the IEPs and grades provided the school’s narrative about the girls. The theoretical basis of the thesis comprises cultural-historical ideas of teaching and learning, and the importance of relationships to group-based learning. Descriptive qualitative analyses were based on the teenage girls’ narratives and resulted in five themes; a sixth theme discussed the school’s assessment of the girls through the IEPs and their grades from lower secondary school. Feeling included or not in the group was the overarching theme of all the stories, which involved the girls’ perceptions of how they were treated by the people around them. The results indicate that the girls needed to have instructions repeated to them. There was also a need for continuous encouragement and affirmation in order for them to dare to take on assignments. When it came to collaborative learning together with classmates, the girls preferred to hide their perceived weaknesses, which only made them more dependent on the teacher’s aid. In addition, the girls felt that the teachers were unhappy with the way they handled their school work, and felt overlooked rather than “seen”. In both the stories and the IEPs, concentration difficulties were highlighted as a consistent problem. The analyses show that it is not possible to speak of concentration difficulties without further specification. Since the girls also explained that they were able to maintain concentration, it is necessary to identify which conditions allow pupils to maintain their skills, and when these skills are lost. One finding was that experiences of playing sports created unexpected development opportunities for performing under pressure, even in test situations. According to the girls, visual strengths could compensate for difficulties remembering comprehensive information. The teaching provided opportunities to demonstrate an understanding of facts through visual expression, but creative elements were not included in graded assessments. The study shows that the girls’ leisure-time experiences created opportunities for generalisation regarding learning strategies in school situations.

Chez les eucaryotes, l'ARN polymérase (RNAP) III transcrit les ARN de transferts, l'ARN ribosomique 5S, et plusieurs douzaines d'autres ARNs non traduits. Le génome des mammifères contient plusieurs milliers d'éléments répétés, les SINEs. In vitro, leur transcription dépend de la RNAP III. Le taux de transcription de la RNAP III détermine la croissance et la prolifération cellulaires, sa dérégulation a été associée à de nombreux cancers. Afin de caractériser la distribution sur l'ensemble du génome de la RNAP III et de ses facteurs de transcription TFIIIB et TFIIIC, nous avons développé un protocole très spécifique de ChIP-seq en tandem. Nous avons déterminé l'ensemble des gènes liés par la RNAP III dans les cellules souches embryonnaires de souris. Cet ensemble est bien inférieur au nombre de gènes prédits dans le génome. Nous avons également observé la RNAP III et ses facteurs de transcription liés à 30 régions non annotées, seule une d'entre elles est conservée chez l'humain. Un très faible nombre de SINEs sur un demi-million prédits est associé à la RNAP III. Notre étude révèle de nombreux sites liés uniquement par TFIIIC, nommés " extra-TFIIIC loci ", ETC chez la levure. Ces sites sont associés à la protéine CTCF, et à la cohésine. La cohésine occupe les sites liés par CTCF, et contribue à la formation de boucles ADN, associées à la répression ou à l'activation de l'expression des gènes. Ces données suggèrent que TFIIIC peut jouer un rôle dans l'organisation de l'architecture chromosomique chez les souris. Nous avons également démontré que TCEA1, l'isoforme ubiquitaire de TFIIS, le facteur d'élongation de la RNAP II, est associée aux gènes actifs de classe III. Ceci suggére que TFIIS est un facteur de transcription de classe III. Finalement, la distribution de TFIIS aux gènes de classe II indique que le recrutement de TFIIS n'est pas suffisant pour contrôler la transition de la RNAP II pausée en 5' des gènes en élongation.

Cette thèse vise à comprendre comment des organismes variés tels que les plantes clonales, les humains ou les guêpes parasitoïdes résolvent un problème commun : Comment se comporter dans un environnement hétérogène de manière à prélever le maximum de ressource ? Les organismes n'ayant pas la capacité d'identifier les solutions théoriquement optimales, nous avons étudié les heuristiques permettant de se comporter efficacement sans calcul. Les insectes parasitoïdes, modèles de choix de l'écologie comportementale, nous montrent que l'information perçue de l'environnement influence de manière complexe le comportement d'approvisionnement. Malheureusement, le processus décisionnel sous-jacent n'est pas accessible directement par les méthodes d'investigation connues. Nous avons donc exploré les processus cognitifs convergeant avec les modèles décisionnels optimaux en utilisant l'Homme. De fortes similitudes ont été relevées entre les deux modèles biologiques, mettant ainsi en évidence des points de convergence entre les mécanismes proximaux du comportement. L'environnement et l'histoire évolutive des organismes influencent donc la prise de décision en favorisant l'émergence et le maintien d'heuristiques efficaces indépendamment du degré de complexité cognitive. Cette problématique a été étendue aux plantes clonales qui explorent le milieu par le biais de prolongements végétatifs. Nous avons identifié l'information pertinente et la règle décisionnelle optimale pour une plante clonale afin de maximiser l'exploitation d'une ressource (nutriments, eau, lumière). Les plantes clonales semblent se comporter de manière cohérente avec les prédictions du modèle optimal, révélant un processus décisionnel encore insoupçonné chez ces organismes.

People who work in occupations that involve intensive near work are thought to have a higher chance of developing myopia than other people. For example, microscopists in the United Kingdom have a higher prevalence of myopia than that of the general community. The prevalence of myopia in Hong Kong is extremely high (71 %) and Hong Kong Chinese people are particularly susceptible to myopia development and progression due to environmental factors. It is possible that this environmental susceptibility may lead to Hong Kong Chinese microscopists developing even greater levels of myopia. We found that the prevalence of myopia in Hong Kong microscopists (n=47, mean age=31 years) was higher than that of United Kingdom microscopists (87 % c.f. 71 %) and similar aged people within the general Hong Kong population (87 % c.f. 71 %; −4.45 D c.f. -3.00 D). However, while in most microscopists (83 % of 36 microscopists followed for a two-year period) the amount of myopia and vitreous chamber depth increased over a two year monitoring period (−0.11 D, 0.06 mm), the increase was not clinically significant. We hypothesised that the slower myopia progression rate in Hong Kong microscopists may be the result of their older average age (Hong Kong microscopists: 31.7 years c.f. United Kingdom microscopists: 29.7 years). When a person looks into a microscope, excessive accommodation occurs even though the microscope is designed to render the magnified image at optical infinity (zero accommodation and vergence demand). This over accommodation is called instrument myopia. It is possible that this over accommodation is linked to the myopia development and progression that occurs in users of these instruments. We found that instrument myopia remained consistent with different viewing conditions and microscope settings (inexperienced microscopists, n=20, mean age: 24.1 years, mean spherical refractive error: −2.83 D). The magnitude of instrument myopia was not correlated with either the age or refractive error of the microscope user, while it was lower in those users with greater experience (inexperienced microscopists: 1.03 D c.f. experienced microscopists: 0.43 D). As the Hong Kong microscopists (n=10, mean age: 31.2 years, mean spherical refractive error: −3.39 D) who partook in this study were experienced (6.3 years spent working in this field), this may have contributed to the lower myopia progression that was observed. Studies to determine the main contribution to the phenomena of instrument myopia were also conducted. Instrument myopia was not correlated with convergence when looking into microscope (r= −0.224, p=0.342), near phoria (r=0.351, p=0.129), AC/A ratio (r= −0.135, p=0.571), the convergence induced by the excessive accommodative response (r= −0.028, p=0.906), lag of accommodation (r=0.065, p=0.785) and tonic accommodation (r=0.142, p=0.551). We suggest that the main contribution to instrument myopia during microscopy is proximal accommodation due to the awareness of the closeness, caused by the height of the microscope (i.e. the distance between the viewer and the table where the microscope is placed), during microscopy. For example, we found that the magnitude of instrument myopia increased significantly (from 0.64 D to 1.16 D) when the height of the microscope decreased from 50 cm to 35 cm. In conclusion we have added, through direct observation, to the understanding of the characteristics of instrument myopia. Guidelines for new microscopists aimed at minimising the amount of instrument myopia that is experienced have been developed. This information might help to reduce the amount of myopia progression in commencing microscopists.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

Syftet med essän är att undersöka hur populärkulturens närvaro och inflytande i förskolan kan förstås utifrån olika perspektiv. Essän tar avstamp i berättelser om hur barn tar inspiration ur populärkulturella erfarenheter då de agerar, vilket leder till konsekvenser, vilka ibland kan upplevas som problematiska. Den undersöker möjligheter och risker med inkludering av populärkultur i förskolan i förhållande till barns literacyutveckling, identitetskonstruktion och inflytande. Den undersöker även vad som kan tänkas ligga bakom exkludering av populärkultur i förskolan.Skrivande har använts som en metod för att reflektera och få syn på nya perspektiv i relation till teorier och tidigare forskning. Reflektionen resulterade i flera upptäckter. Bland annat att klassrelaterade normer kan styra pedagogers val av kulturella aktiviteter i förskolans praktik. Vidare att risken som populärkulturen kan ge upphov till vad gäller identitetskonstruktion i samband med literacyutveckling kan inverteras till möjligheter genom critical literacy. Därigenom kan barn lära sig att se hur texter positionerar oss i samhället och hur de kan positionera sig annorlunda. Slutligen kan inkludering av populärkultur i förskolans praktik, som en konsekvens av barns inflytande stimulera barns literacyutveckling. Eftersom populärkulturen är en del av barns erfarenheter samt att den fungerar som katalysator för lärprocessen, genom att ge upphov till en känsla av flow. / This essay aims to examine how presence and influence of popular culture in junior kindergarten can be understood in different ways. The essay is rooted in narratives about children getting inspired from popular culture in their acting that leads to consequences, which sometimes can be experienced as problematic. It explores possibilities and risks that come with including popular culture in junior kindergarten, in relation to literacy development, construction of identity and influence of children. It also explores how to understand what maybe lies behind the exclusion of popular culture in junior kindergarten.Writing has been used as a method to reflect and to spot new perspectives in relation to theories and previous research. The result of the reflection was multiple discoveries. For instance, class related norms can dominate teachers choices of cultural activities put into practice in junior kindergarten. Further on the risks of popular culture, regarding construction of identity in connection with literacy development could be transformed in opportunities through critical literacy. Thereby children can learn to see how we´re positioned in society by texts and how they can position themselves differently. Eventually, inclusion of popular culture into the practice of junior kindergarten, as a result of child influence can stimulate literacy development. Because the popular culture is a part of earlier experiences of the child and it works like a catalyst in the process of learning, while it creates the feeling of flow.

The aim of this study was to investigate how four third grade pupils, who are in need of extra support in their development in writing, and their teacher describe the conditions of the teaching organization when writing factual text. The empirical material consisted of transcripts of interviews with teacher and students, supported by field notes of observations and video observations. Constructively oriented interviews were conducted with an interview guide as support. The choice to carry out observations and video observation also gave an opportunity to study the teaching from different perspectives, and contributed to broader empirical material.   The results of the study show that the scaffolding that existed in the organization in various ways created opportunities for the pupils to write factual texts. Different examples of a varied and successful scaffolding in teaching are presented in the results section. The current teacher used several different artefacts in her teaching as well as collaborative activities like dialogues in full class, or between students, to support knowledge, acquisition on the subject, on subject specific concepts and on factual writing. One obstacle that emerged was that a pupil had difficulty writing the factual text despite the support that existed in the organization of the teaching.   The pupils also describe a varied support in teaching. They used different artefacts as support when they learned the facts on the subject and when writing the factual texts. According to the pupils’ statements more obstacles existed. One pupil had difficulties to write despite the support, one pupil felt that writing by hand was an obstacle, one pupil stressed that the weak interest for the subject as well as the “childish” material (the film) reduced the motivation to learn and two pupils also claimed external influences, like a noisy classroom, to be an obstacle to focusing on the writing task. / Syftet med denna studie var att undersöka hur fyra elever som är i behov av extra stöd i sin skrivutveckling och en lärare i årskurs 3 beskriver vilka förutsättningar som finns i undervisningen för att skriva en faktatext. Det empiriska materialet utgjordes av utskrifter från lärar- och elevintervjuer med stöd av fältanteckningar från observation och videoobservation. Konstruktivistiskt orienterade intervjuer utfördes med en intervjuguide som stöd. Valet att även genomföra observation och videoobservation gav en möjlighet att studera undervisningen utifrån olika perspektiv och bidrog till ett bredare empiriskt material.   Resultaten från studien visade att den stöttning som fanns i undervisningens organisation på många olika sätt skapade förutsättningar för eleverna att skriva en faktatext. Olika exempel på en varierad framgångsrik stöttning presenteras i resultatet. Läraren i studien använde flera olika artefakter som stöd i undervisningen och kollaborativa aktiviteter som samtal i helklass och mellan elever för att stötta kunskapsinhämtning om ämnet, ämnesbegrepp och skrivande av en faktatext. Ett hinder som framkom var att en elev hade svårt att skriva faktatexten trots stödet som fanns i undervisningens organisation.   Eleverna beskrev också ett varierat stöd i undervisningen. De använde olika artefakter som stöd när de skulle lära sig fakta om ämnet och när de skulle skriva faktatexten. Utifrån elevernas beskrivningar framkom fler hinder. En elev hade svårt att skriva trots stödet, en elev ansåg att skrivandet för hand hindrade honom, en elev tar upp att intresset för ämnet är lågt och densamme menar att materialet (filmen) är för ”barnsligt” vilka båda är faktorer som påverkar motivationen att lära och två elever lyfter även yttre påverkansfaktorer, som prat i klassrummet som ett hinder för att kunna koncentrera sig på skrivuppgiften.

Este trabalho apresenta uma proposta de sequência didática em problemas de contagem, a partir de situações de jogos. Foi feito um Estudo de Caso numa turma de 8º ano do ensino fundamental do Colégio Militar de Porto Alegre e, ao longo do segundo semestre de 2008, quando da aplicação desses jogos, fizemos observações em relação às estratégias de contagem, às relações sociais, às distintas formas de organizar a resolução dos problemas que surgiam nas atividades e aos esquemas produzidos pelos alunos. Fundamentados na Teoria dos Campos Conceituais (Vergnaud) e na Zona de Desenvolvimento Proximal (Vygotsky), fazemos uma análise de como esses sujeitos se comportaram em diferentes contextos que abordavam o mesmo campo conceitual multiplicativo. Ao término dessa pesquisa, concluímos que o conjunto das diversas situações dos jogos ampliou o leque de representações de contagem e que o ambiente de sala de aula se tornou mais sociável, à medida que os alunos se integravam para um objetivo comum. / This work proposes a teaching sequence in counting problems, from situations of games. Was made a case study in a class of 8th grade of elementary school of the Military School of Porto Alegre and, during the second half of 2008, when following these games, we made observations on the counting strategies, social interaction, different ways of organizing the problems that arose in the activities and the schemes produced by the students. Based on the Theory of Conceptual Fields (Vergnaud) and Zone of Proximal Development (Vygotsky), we made an analysis of how these individuals behave in different contexts that were on the same multiplicative conceptual field. At the end of this research, we conclude that all the different situations of the game expanded the range of representations of counting and that the environment of the classroom has become more sociable, as the students were integrated into a common goal.