Background: One expected consequence of population aging in Europe is the shrinkage of the labor force. Most existing labor force projections allow only inferences about the size and age structure of the future labor force. Objective: In comparison to existing labor force projections, which disaggregate only by age and sex, these projections include information about the highest level of educational attainment (tertiary vs. non-tertiary education), so that an additional level of heterogeneity in labor force participation is considered. This heterogeneity enters the projection methodology through population projection data as well as labor force participation data, since both components are decomposed in the three dimensions of age, sex, and education. Based on data from the European Labor Force Survey (EU LFS), three scenarios were designed to project the economically active population for 26 EU countries up to 2053. Results: Adding the educational dimension to labor force projections discloses a significant shift towards tertiary education degrees between 2008 and 2053. This educational upgrading of the European labor force is not driven by developments in a few large countries but can be expected to take place in each of the 26 analyzed countries. Conclusions: A better educated but shrinking labor force is likely to be able to alleviate some of the anticipated economic consequences of population aging. The presented projections of education-specific labor supply can serve as inputs into forecasts of economic growth that include educational differentials in labor productivity. (author's abstract)

Climate change is one of the great challenges facing agriculture in the 21st century. The goal of this study was to produce projections of crop yields for the central United States in the 2030s, 2060s, and 2090s based on the relationship between weather and yield from historical crop yields from 1980 to 2010. These projections were made across 16 states in the US, from Louisiana in the south to Minnesota in the north. They include projections for maize, soybeans, cotton, spring wheat, and winter wheat. Simulated weather variables based on three climate scenarios were used to project future crop yields. In addition, factors of soil characteristics, topography, and fertilizer application were used in the crop production models. Two technology scenarios were used: one simulating a future in which crop technology continues to improve and the other a future in which crop technology remains similar to where it is today. Results showed future crop yields to be responsive to both the different climate scenarios and the different technology scenarios. The effects of a changing climate regime on crop yields varied both geographically throughout the study area and from crop to crop. One broad geographic trend was greater potential for crop yield losses in the south and greater potential for gains in the north. Whether or not new technologies enable crop yields to continue to increase as the climate becomes less favorable is a major factor in agricultural production in the coming century. Results of this study indicate the degree to which society relies on these new technologies will be largely dependent on the degree of the warming that occurs. Continued research into the potential negative impacts of climate change on the current crop system in the United States is needed to mitigate the widespread losses in crop productivity that could result. In addition to study of negative impacts, study should be undertaken with an interest to determine any potential new opportunities for crop development with the onset of higher temperatures as a result of climate change. Studies like this one with a broad geographic range should be complemented by studies of narrower scope that can manipulate climatic variables under controlled conditions. Investment into these types of agricultural studies will give the agricultural sector in the United States greater tools with which they can mitigate the disruptive effects of a changing climate.

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No description available.

La mise en place des projections axonales est une étape clé du développement des circuits de la moelle épinière qui contrôle les fonctions motrices de l’individu. Il s’agit d’un processus complexe impliquant des mécanismes de spécification des neurones moteurs et des signalisations multiples assurant le guidage spécifique de chaque axone jusqu’à sa cible d’innervation. Les Sémaphorines de classe 3 (Sema3) sont des molécules secrétées dans l’environnement qui participent notamment au guidage des axones moteurs de la moelle épinière. De manière surprenante, les motoneurones expriment également eux-mêmes des Sema3. Mon équipe a déjà montré que l’expression intrinsèque de Sema3A par les motoneurones module leur sensibilité au Sema3A de l’environnement. Ce processus s’effectue par une régulation du niveau de son récepteur à la surface du cône de croissance, la structure terminale de l’axone responsable de la perception des signaux de guidage extracellulaires (Moret et al., 2007). Quelle est la portée de ce nouveau mécanisme modulatoire et peut-il être généralisé à d’autres membres de la famille des Sema3 exprimés dans les motoneurones ? Mon travail de thèse a permis de mettre en évidence ce rôle modulatoire d’un autre membre de la famille Sema3 : Sema3C, dons l’expression est restreinte à une sous-population de motoneurones, en plus d’une expression environnementale. Par des expériences de gain et de perte de fonction dans l’embryon de poulet, nous avons montré que l’expression motoneuronale de Sema3C module de manière différentielle ses deux récepteurs du niveau de récepteur entraînent une modulation de réponse à Sema3C mais aussi à Sema3A et Sema3F, qui se fixent respectivement sur Nrp1 et Nrp2. De plus, nous avons étudié la portée de ce mécanisme de modulation dans l’innervation des membres de l’embryon de poulet, ce modèle permettant l’étude des projections motoneuronales dans un environnement riche en Sema3. Ainsi, l’analyse in vivo des embryons de poulet pour lesquels l’expression intrinsèque de Sema3C dans les motoneurones a été manipulée a permis de montrer que la modulation de réponse aux Sema 3 de l’environnement contribue au positionnement stéréotypé des projection motrices dans le membre antérieur. Ce travail permet donc de proposer que l’expression d’un code de Sema 3 par les motoneurones confère aux différentes sous-populations une sensibilité spécifique aux gradients de Sema 3 présents dans l’environnement et assure ainsi une trajectoire stéréotypée des axones moteurs jusque dans leur territoire cible. / During spinal circuit’s development, the implementation of axonal projections is a key step as it ensures the integrity of motor functions. This complex process implicates several mechanisms such as motoneuton specification and various signaling cascades in order to guide specifically each axon toward its innervation target. Class 3 Semaphorins (Sema3s) are chemotactic cues, secreted in the environment, and contributing to the guidance of spinal motor axons. Surprisingly, these Sema3s are also expressed by motoneurons themselves. Previous work in our team showed that intrinsic expression of Sema 3A. This process arises from the regulation of its receptor availability at the growth cone surface, the terminal end of the axon that enables sensing of extracellular signals (Moret et al., 2007). But in what extent can we generalize this mechanism to other members of the Sema3 family, and what impact could it have, in vivo, during development? My PhD work revealed the modulatory role of another Sema3, Sema3C, expressed in a restricted motoneuronal subpopulation as well as in the environment. By again and loss of function experiments in the chick embryo, we showed that motoneuronal expression of Sema3C modulates differentially its two Neuropilin receptor level, Nrp1 and, Nrp2, at the growth cone surface. These variations of receptors’ availability lead to a response modulation to extrinsic Sema3, but also to Sema3A and Sema3F, that bind to Nrp1 and Nrp2, respectively. Moreover, we analyzed the role of such modulation mechanisms during limb innervation in the chick embryo. Indeed, this model enables the study of motor axon growth in a complex Semaphorin environment. In vivo analysis of chick embryos after intrinsic Sema3C manipulations revealed that response modulation to environmental Sema3s takes part in the stereotyped positioning motor axon projections in the forelimb. Hence, this Study suggest a model in which the expression of a Semaphorin code by motoneurons enables specific subpopulations to modulate their sensitivity Sema3 gradients expressed in their environment, thus contributing to the stereotyped trajectories of motor axon projections towards their final target.

Les tourbières sont largement présentes dans les hautes latitudes nord et plus particulièrement dans les régions de pergélisols. Elles contiennent un important stock de carbone et constituent l’une des plus grandes sources naturelles de méthane. Leur représentation dans un modèle de climat estalors primordiale pour améliorer celle du cycle du carbone. De plus, la contribution des émissions de méthane des tourbières reste encore incertaine et de nombreuses incertitudes persistent. Les émissions de méthane des tourbières dépendent fortement du climat et sont influencées principalement par la température et l’humidité du sol. Parallèlement, le réchauffement climatique particulièrement prononcé à ces latitudes conduit au dégel des pergélisols avec une augmentation de la profondeur de la couche active. Ce grand réservoir de carbone peut être partiellement mobilisé et émis sous forme de CO2 ou CH4, en fonction des conditions hydrologiques à la surface.L’objectif de ces travaux de thèse consiste à représenter les tourbières des hautes latitudes dansle modèle de surface ORCHIDEE. Ce développement est effectué dans la version du modèle qui intègreles processus des hautes latitudes tels que le gel des sols. Les tourbières sont représentées parun schéma hydrologique spécifique ce qui améliore les échanges en énergie et en eau. La difficultérepose sur la représentation des processus locaux des tourbières à l’échelle d’un modèle de climatglobal. Certaines propriétés biologiques ont également été prises en compte afin de mieux représenter la végétation de ces milieux. Pour cela, les tourbières sont intégrées comme un nouveau type devégétation et représentées par une fraction de grille, basée sur des observations. Le comportement hydrologique et l’impact de cette intégration sont évalués à échelle des hautes latitudes ainsi qu’à échelle régionale. Ce développement permet d’estimer ensuite l’évolution de l’hydrologie des tourbières suite au réchauffement climatique. Les changements de l’hydrologie des tourbières d’ici la fin du siècle permettent de mieux évaluer les variations futures de leurs émissions de CH4.Ce travail de développement a ensuite été appliqué pour déterminer l’évolution des émissions deméthane. Les tourbières constituent l’une des plus grandes sources naturelles de méthane et contrôlentà plus de 70 % la variabilité interannuelle de la concentration atmosphérique de CH4. Les émissionsde méthane résultent de différents processus physiques et biologiques tels que la méthanogénèse etla méthanotrophie. Pour représenter ces processus, un modèle de densité de flux existant, intégré dans ORCHIDEE, a été adapté pour les tourbières afin d’estimer les émissions de méthane des tourbières des hautes latitudes. L’évolution de ces émissions est étudiée entre le début du 20ème et la fin du 21ème siècles selon différents scénarios climatiques. / Peatlands are widely present in northern latitudes and especiallyin permafrost regions. They contain a high carbon stock and are one ofthe greatest natural sources of methane. Their representation in a climate model is crucial to improve the one of the carbon cycle. Moreover, the contribution of methanepeatland emissions remains uncertain.Methane emissions from peatlands strongly depend on the climate and are influenced primarily by temperature and soil moisture. Meanwhile, climate change is particularlysevere at these latitudes and leads to thawing permafrost with increasing the active layer depth. This large carbon reservoir may be partially mobilized and emitted asCO2 or CH4, depending on hydrological conditions at the surface.The aim of this PhD thesis is to represent northern peatlands in the ORCHIDEE land surface model. This development is carried out in the version of the model that incorporatesprocesses in high latitudes such as the soil freezing. Peatlands are represented by a specific hydrological scheme which improves the exchange of energy and water. The difficulty isbased on the representation of local peatlands processes across a global climate model. Some biological properties were also considered to represent bettervegetation of these environments. To do so, peatlands are integrated as a new type ofvegetation and represented by a fraction of a grid, based on observations. Thehydrological behaviour and the impact of this integration are estimated at the boreal scale as well asregionally. This development then allows estimate changes in the hydrology of peatlands due to global warming. Studying the changes in hydrology of peatlands by the end of th 21st century will improve the prediction of future changes in their CH4 emissions.This development work was then applied to determine the evolution of methane emissions. Peatlands are one of the largest natural sources of methane and control more than 70% interannual variability of atmospheric concentration of CH4. Methane emissions result from various physical and biological processes such as methanogenesis and the methanotrophy. To represent these processes, a flux density model, integratedin ORCHIDEE, was adapted for peatlands to estimate their methane emissions. The evolution of these emissions is studied between the early 20th and late 21st centuries under different climate scenarios.

Cette étude inédite se propose d’aborder un pan méconnu de l’histoire du cinéma dans l’enseignement. Le réseau « Freinet », du nom de son instigateur, Célestin Freinet, a joué, depuis la fin des années 1920, un rôle important dans l’introduction du cinéma à l’école en France. Il réunit, en marge du système traditionnel, des éducateurs militant pour des méthodes nouvelles d’apprentissage ; des « expérimentateurs » qui utilisent dans leur classe des outils originaux tel quele cinéma. Si le réseau « Freinet » existe toujours aujourd’hui, l’étude se borne aux expérimentations fondatrices (1927-1968). Ce flash-back historique vise à découvrir des usages hors du commun et d’une grande modernité. Les pratiques constituent le principal axe d’analyse pour déterminer un particularisme en matière d’emploi du cinéma en classe face aux formes d’utilisation usuelles qui consistent à employer le film comme support de la leçon. L’élève devient « acteur ». Cette acception de l’apprentissage ouvre la voie à de nouvelles formes d’exploitation de la projection. Elle ouvreaussi la voie au cinéma outil d’expression, de création et de développement. / This unprecedented study addresses an unknown fold of Cinema History in education. The network « Freinet », named after its instigator Celestin Freinet, has played, since the end of the 20’s, an important role, by introducing the cinema into school in France. It brings together, outside the traditional system, educators campaining for new learning methods ; « experimenters » who use uncommon tools such as cinema in their class. Nowadays, if the network « Freinet » does still exist, the study is limited to the founders experimentations (1927 – 1968). This historical flashback aims to discover uncommon uses, also demonstrating a great modernity. Practices establish the main lead of the analysis in order to define a particularism in terms of uses of cinema in class, opposite common uses of movies as support of the lesson. The pupil becomes « actor ». This learning acceptance paves the way for new types of projection. It also opens the way for cinema as an expressing, creating and developing tool.

The South Nation watershed is located in Eastern Ontario, Canada and managed under the authority of the South Nation Conservation (SNC). The watershed covers an area of 400,000 hectares with four dominant categories of land-use classes (60% agriculture, 34% forest, 5% mixed urban, and 1% other). Water quality is a great concern for the SNC as many anthropogenic activities generate harmful pollutants (such as heavy metals, nitrogen, phosphorus, and pesticides) that are discharged to the river through surface and groundwater flow. The discharge patterns of these pollutants are mainly driven by land-use distribution within the watershed which has been constantly evolving with urbanization and intensification of agriculture. Major changes in land-uses can potentially offset current SNC efforts to mitigate water pollution. The objective of the current study is to predict land-use series of maps for the South Nation watershed starting from 1991 to 2020. The prediction is carried out using the land-use allocation algorithm of the Dyna-CLUE (Dynamic Conversion of Land-Use and its Effects) model which is implemented for local regions. Dyna-CLUE is a spatially explicit hybrid land-use allocation model that combines estimation and simulation models, and its allocation procedures predict future trends of land-use surface (estimated from historical trends). The binary logistic regression is used to link preferences of land-use classes and potential demographic and geographic driving factors. Expert judgment was used to select a set of spatial driving factors believed to be responsible for changes in land-use distribution in the South Nation watershed. Three different scenarios for future development of the region were considered, with different initial conditions and conversion restrictions. The simulation results were evaluated using visual and statistical validation techniques to assess the performance of the model in generating maps similar to reality. The Dyna-CLUE model was successfully applied to the South Nation watershed. It was observed that the simulated maps generated from the model were in good agreement with the reality maps. This was confirmed through statistical validation via map pair analysis (error matrix) used to assess the overall accuracy of the model predictions. Results showed that the model was sensitive to land-use restrictions. Such type of modeling can be valuable for assessing the land-use changes at the local level, and setting up a decision support system for the South Nation Conservation towards sustainable land-use management in the watershed. Better results are expected to be achieved with more reliable datasets (i.e., accurate classification of land-use types in reality maps). Data availability and quality were the main obstacles that faced this research work. Our work has the merit to be the first application of CLUE model in Eastern Ontario.

This thesis concerns dimensions and projections of sets that could be described as fractals. The background is applied problems regarding analysis of human tissue. One way to characterize such complicated structures is to estimate the dimension. The existence of different types of dimensions makes it important to know about their properties and relations to each other. Furthermore, since medical images often are constructed by x-ray, it is natural to study projections. This thesis consists of an introduction and a summary, followed by three papers. Paper I, Anders Nilsson, Dimensions and Projections: An Overview and Relevant Examples, 2006. Manuscript. Paper II, Anders Nilsson and Peter Wingren, Homogeneity and Non-coincidence of Hausdorff- and Box Dimensions for Subsets of ℝn, 2006. Submitted. Paper III, Anders Nilsson and Fredrik Georgsson, Projective Properties of Fractal Sets, 2006. To be published in Chaos, Solitons and Fractals. The first paper is an overview of dimensions and projections, together with illustrative examples constructed by the author. Some of the most frequently used types of dimensions are defined, i.e. Hausdorff dimension, lower and upper box dimension, and packing dimension. Some of their properties are shown, and how they are related to each other. Furthermore, theoretical results concerning projections are presented, as well as a computer experiment involving projections and estimations of box dimension. The second paper concerns sets for which different types of dimensions give different values. Given three arbitrary and different numbers in (0,n), a compact set in ℝn is constructed with these numbers as its Hausdorff dimension, lower box dimension and upper box dimension. Most important in this construction, is that the resulted set is homogeneous in the sense that these dimension properties also hold for every non-empty and relatively open subset. The third paper is about sets in space and their projections onto planes. Connections between the dimensions of the orthogonal projections and the dimension of the original set are discussed, as well as the connection between orthogonal projection and the type of projection corresponding to realistic x-ray. It is shown that the estimated box dimension of the orthogonal projected set and the realistic projected set can, for all practical purposes, be considered equal.

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