El desarrollo xilemático es un aspecto fuertemente regulado por hormonas y otros factores de tipo endógeno. La caracterización el mutante acaulis5 (acl5) en Arabidopsis thaliana, deficiente en la síntesis de termoespermina, permitió asignar a esta poliamina una función como regulador de la maduración del xilema, impidiendo la muerte celular antes de que el proceso de diferenciación haya culminado. Aunque se desconoce el mecanismo molecular concreto, se ha identificado un grupo de factores de transcripción de la familia bHLH (SAC51/AJAX1, AJAX2, AJAX3 y AJAX4) cuya traducción es promovida por la termoespermina y es imprescindible para la correcta maduración del xilema, y que actúan como represores de la actividad de LONESOME HIGHWAY (LHW) con el fin de controlar temporalmente los eventos de diferenciación dirigidos por este factor de transcripción. Aunque se sabe que la degradación de las proteínas DELLAs por parte de las giberelinas (GAs) es necesaria para el aumento de crecimiento secundario que acompaña la transición floral, se desconoce el mecanismo molecular concreto por el que esto sucede. En un rastreo de doble híbrido en levadura para la identificación de factores de transcripción que median la actividad de las proteínas DELLA se identificó AJAX3 como interactor de GAI, por lo que el objetivo de esta tesis ha sido el de comprobar si las giberelinas (GAs) regulan la maduración del xilema, y si lo hacen a través de esta interacción. El análisis genético, fisiológico y molecular ha demostrado que: (1) la deficiencia en GAs provoca un fenotipo en el xilema similar al de la falta de función de ACL5; (2) es posible localizar a las DELLAs en la vasculatura, solapando con la expresión de otros elementos necesarios para la diferencación del xilema, como ACL5 y LHW; y (3) la acumulación de DELLAs específicamente en el dominio de expresión de ACL5 en la vasculatura dificulta la maduración del xilema. Además, AJAX3 inhibió la capacidad de LHW de activar a sus dianas en ensayos de expresión transitoria en Nicotiana benthamiana, y la coexpresión de GAI alivió esta represión. En base a estos resultados, proponemos que las GAs promueven la maduración del xilema al menos a través de la modulación de la actividad de AJAX3 para acomodar el proceso de diferenciación al aumento de crecimiento secundario durante la transición flora / Álvarez Mahecha, JC. (2014). CONTROL DE LA DIFERENCIACIÓN DEL XILEMA POR GIBERELINAS A TRAVÉS DE LA INTERACCIÓN DELLA-AJAX3 [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48454 / TESIS

Patterns in the floristic composition, stand structure, species richness and environmental characteristics of plant communities at a number of spatial scales were examined in Ku-ring-gai Chase National Park, New South Wales. Vegetation patterns in eastern Australia have often been related primarily to a single environmental variable, soil phosphorus concentration. This study examines the 'single nutrient' hypothesis regarding the distribution of plant species. If soil phosphorus concentration is the majot factor affecting the distribution of plant species, then this should be highly correlated with spatial patterns in the floristic composition of plant communities within the study area. Floristic composition was determined as the frequencies of all vascular species occuring within duplicate 500 m2 quadrants from fifty sites within the Park. Environmental data consisted of 21 variables, including soil physical and chemical characteristics, from each quadrant. The patterns in floristic composition and environmental factors are described and the relationships between composition and environment were examined. through indirect and direct gradient analyses. The measured environmental factors showed strong correlations with floristic patterns; however, two scales of species distributions were apparent: between and within soil type. Direct gradient analyses of composition and environmental data showed soil phosphorus concentration was inadequate in explaining the observed patterns in floristic composition of plant communities are a response to complex multivariable environmental gradients. The structural characteristics of vegetation stands were examined through the development of a multivariate approach to the classification of stand structure. This multivariate approach is essentially a modification of an existing scheme utilising foliage projective cover of various recognisable strata within the strands. Multivariate classification and ordinations of plant communities based on structural characteristics showed strong correspondence to that obtained by compositional analyses. The complex multivariable gradient hypothesis is supported from results examining stand structure-environment relationships. The relationship between species richness and richness of three growth-form types (tree, shrubs, and herbs) and environmental variables were examined through generalised linear models. The measured environmental variables showed strong relationships with species richness, consistent with the results found multivariately with floristic composition and stand structure. No single measured environmental variable adequately predicted the observed patterns in species richness, rather species richness showed strong relationships with complex multivariable environmental gradients. This study clearly demonstrates the the 'single-nutrient' or 'phosphorus' hypothesis is inadequate in explaining all the patterns in the various components of vegetation within Ku-ring-gai Chase National Park. The complex multivariable environmental gradient hypothesis suggested by the relationships between floristic composition and environmental variables is supported by the relationships exhibited by two other attributes of vegetation communities: stand structure and species richness. Further studies testing the significance of the complex multivariable environmental gradient hypothesis are required.

Patterns in the floristic composition, stand structure, species richness and environmental characteristics of plant communities at a number of spatial scales were examined in Ku-ring-gai Chase National Park, New South Wales. Vegetation patterns in eastern Australia have often been related primarily to a single environmental variable, soil phosphorus concentration. This study examines the 'single nutrient' hypothesis regarding the distribution of plant species. If soil phosphorus concentration is the majot factor affecting the distribution of plant species, then this should be highly correlated with spatial patterns in the floristic composition of plant communities within the study area. Floristic composition was determined as the frequencies of all vascular species occuring within duplicate 500 m2 quadrants from fifty sites within the Park. Environmental data consisted of 21 variables, including soil physical and chemical characteristics, from each quadrant. The patterns in floristic composition and environmental factors are described and the relationships between composition and environment were examined. through indirect and direct gradient analyses. The measured environmental factors showed strong correlations with floristic patterns; however, two scales of species distributions were apparent: between and within soil type. Direct gradient analyses of composition and environmental data showed soil phosphorus concentration was inadequate in explaining the observed patterns in floristic composition of plant communities are a response to complex multivariable environmental gradients. The structural characteristics of vegetation stands were examined through the development of a multivariate approach to the classification of stand structure. This multivariate approach is essentially a modification of an existing scheme utilising foliage projective cover of various recognisable strata within the strands. Multivariate classification and ordinations of plant communities based on structural characteristics showed strong correspondence to that obtained by compositional analyses. The complex multivariable gradient hypothesis is supported from results examining stand structure-environment relationships. The relationship between species richness and richness of three growth-form types (tree, shrubs, and herbs) and environmental variables were examined through generalised linear models. The measured environmental variables showed strong relationships with species richness, consistent with the results found multivariately with floristic composition and stand structure. No single measured environmental variable adequately predicted the observed patterns in species richness, rather species richness showed strong relationships with complex multivariable environmental gradients. This study clearly demonstrates the the 'single-nutrient' or 'phosphorus' hypothesis is inadequate in explaining all the patterns in the various components of vegetation within Ku-ring-gai Chase National Park. The complex multivariable environmental gradient hypothesis suggested by the relationships between floristic composition and environmental variables is supported by the relationships exhibited by two other attributes of vegetation communities: stand structure and species richness. Further studies testing the significance of the complex multivariable environmental gradient hypothesis are required.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

abstract: The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) General Abilities Index (GAI) and Cognitive Proficiency Index (CPI) have been advanced as possible diagnostic markers of Attention-Deficit Hyperactivity Disorder (ADHD). Diagnostic utility statistics were used to test the ability of GAI-CPI difference scores to identify children with ADHD. Participants included an ADHD sample (n = 78), a referred but non-diagnosed hospital sample (n = 66), and a simulated sample with virtually identical psychometric characteristics as the WISC-IV 2,200 child standardization sample. Receiver Operating Characteristic (ROC) analyses were computed to determine the utility of GAI-CPI difference scores to identify children with ADHD. The GAI-CPI discrepancy method had an AUC of .64, 95% CI [0.58, 0.71] for the ADHD sample compared to the simulated normative sample and an AUC of .46, 95% CI [0.37, 0.56] for the ADHD sample compared to the referred but non-diagnosed hospital sample. These AUC scores indicate that the GAI-CPI discrepancy method has low accuracy. / Dissertation/Thesis / M.A. Educational Psychology 2010

La modélisation des préférences par le biais de formalismes de représentation compacte fait l'objet de travaux soutenus en intelligence artificielle depuis plus d'une quinzaine d'années. Ces formalismes permettent l'expression de modèles suffisamment flexibles et riches pour décrire des comportements de décision complexes. Pour être intéressants en pratique, ces formalismes doivent de plus permettre l'élicitation des préférences de l'utilisateur, et ce en restant à un niveau admissible d'interaction. La configuration de produits combinatoires dans sa version business to customer et la recherche à base de préférences constituent de bons exemples de ce type de problème de décision où les préférences de l'utilisateur ne sont pas connues a priori. Dans un premier temps, nous nous sommes penchés sur l'apprentissage de GAI-décompositions. Nous verrons qu'il est possible d'apprendre une telle représentation en temps polynomial en passant par un système d'inéquations linéaires. Dans un second temps, nous proposerons une version probabiliste des CP-nets permettant la représentation de préférences multi-utilisateurs afin de réduire le temps nécessaire à l'apprentissage des préférences d'un utilisateur. Nous étudierons les différentes requêtes que l'on peut utiliser avec une telle représentation, puis nous nous pencherons sur la complexité de ces requêtes. Enfin, nous verrons comment apprendre ce nouveau formalisme, soit grâce à un apprentissage hors ligne à partir d'un ensemble d'objets optimaux, soit grâce à un apprentissage en ligne à partir d'un ensemble de questions posées à l'utilisateur. / --

Pour maintenir l'architecture du tissue, les cellules épithéliales se divisent de manière planaire, perpendiculaire à leur axe principal de polarité. Du fait que le centrosome retrouve sa localisation apicale à l'interphase l'orientation du fuseau mitotique est réinitialisée à chaque cycle cellulaire. Nous utilisons de l'imagerie live en trois dimensions de centrosome marqués en GFP pour investiguer la dynamique de l'orientation du fuseau mitotique des cellules neuroépithéliales de l'embryon de poulet. Le fuseau mitotique présente des mouvements stéréotypiques pendant la métaphase, avec dans un premier temps une phase active de d'orientation planaire suivie par une phase de maintenance planaire jusqu'à l'anaphase. Nous décrivons la localisation des protéines NuMA et LGN formant un anneau au niveau du cortex latéral cellulaire au moment de l'orientation du fuseau. Enfin, nous montrons que le complexe protéique formé par LGN, NuMA et par la sous unité Gai localisé au cortex est nécessaire pour les mouvements du fuseau et pour réguler la dynamique de l'orientation du fuseau. La localisation restreinte de LGN et NuMA en anneau cortical est instructive pour l'alignement planaire du fuseau mitotique et est également requise pour sa maintenance planaire. / To maintain tissue architecture, epithelial cells divide in a planar fashion, perpendicular to their main polarity axis. As the centrosome resumes an apical localization in interphase, planar spindle orientation is reset at each cell cycle. We used three-dimensional live imaging of GFP-labeled centrosomes to investigate the dynamics of spindle orientation in chick neuroepithelial cells. The mitotic spindle displays stereotypic movements during metaphase, with an active phase of planar orientation and a subsequent phase of planar maintenance before anaphase. We describe the localization of the NuMA and LGN proteins in a belt at the lateral cell cortex during spindle orientation. Finally, we show that the complex formed of LGN, NuMA, and of cortically located Gái subunits is necessary for spindle movements and regulates the dynamics of spindle orientation. The restricted localization of LGN and NuMA in the lateral belt is instructive for the planar alignment of the mitotic spindle, and required for its planar maintenance.

Many researches are focused on the study of depression in older age, their results show a negative impact of depression on the cognition of the elderly. There are not many studies that focus on geriatric anxiety and their results are often contradictory. In the theoretical part, this thesis aims to provide an insight into the anxiety from the philosophical and clinical standpoint, and in particular to describe the specifics of the geriatric anxiety and various areas of human life that may affect it. The practical part presents the results of 279 participants of the NANOK study aged 60-92 years, the analysis focuses on the effects of anxiety symptoms on cognition, taking into account depressive symptoms. Significant differences in healthy elderly persons are found only in the tests of immediate and delayed recall, no significant differences are found in the attention and executive functions tests. Various ways of influencing cognition by anxiety are discussed. In our sample of healthy older people, the rate of anxiety symtoms was not associated with the level of cognitive performance. Keywords: elderly; cognition; depression; anxiety; screening; Geriatric Anxiety Inventory; GAI

L'objectif général de ce mémoire est d'explorer plusieurs conceptions fondamentales de la pensée nietzschéenne à l'aide de l'idée du tragique qui, croyons-nous, pourrait fournir un gain interprétatif susceptible de clarifier et de mesurer la portée de plusieurs d'entre-elles [sic]. L'idée du tragique est définie pour nous par l'idée d'une primauté et d'un caractère absolument indépassable du pluralisme ontologique, qui implique directement que toute forme d'unité doit conserver un statut essentiellement fictif ; avec cette nuance importante que l'unité, en tant que fiction, est aussi arbitraire que nécessaire. C'est pourquoi l'étude des processus qui conduisent la pluralité à se « résoudre » temporairement dans une unité, tout autant que les conditions qui permettent à ceux-ci d'assurer le renouvellement de cette unité, demeure selon nous l'enjeu primordial, voire une des principales clefs de l'interprétation de la philosophie nietzschéenne. Nous proposons donc d'étudier le corps , le gai savoir et le surhomme comme des thèmes correspondant respectivement à une vision tragique de la pensée, de la connaissance et du philosophe.