Universiẗat, Diss.--Wuppertal, 2007.

Zugl.: Düsseldorf, Universiẗat, Diss., 1998.

No description available.

Les symbioses mycorhiziennes, entre champignons et racines de plantes, concernent 95 % des espèces végétales. Les arbres sociaux des forêts boréales et tempérées forment avec les champignons un type particulier d’association : la symbiose ectomycorrhizienne. Les ectomycorrhizes jouent un rôle essentiel dans la nutrition hydrominérale des arbres, le cycle des éléments minéraux et la production primaire. Cependant, leur complexité n’a pas permis à ce jour de déchiffrer leurs rôles et leurs fonctions précises. La récente disponibilité du génome du champignon ectomycorhizien Laccaria bicolor et de celui de l'arbre hôte Populus trichocarpa fournit une occasion inégalée d’approfondir nos connaissances du développement et du fonctionnement de cette symbiose. Les objectifs de cette étude ont donc été de participer à la caractérisation et au décryptage du génome de L. bicolor puis à la recherche des gènes impliqués dans la formation des ectomycorhizes chez les deux partenaires. Dans un premier temps et afin d’aider à l’assemblage de la séquence génomique de L. bicolor, nous avons identifié les séquences répétées et construit une carte génétique. Sur les 60 Mb de ce génome, nous avons mis en évidence 8 % de séquences microsatellitaires et 24 % d’éléments transposables. Une carte génétique a été construite à partir de 111 monocaryons issus de L. bicolor S238N. Cette carte comprend 326 marqueurs (8 RAPD, 243 AFLP, 59 SSR et 14 SNP) répartis sur 10 groupes de liaison ancrés à la séquence génomique de L. bicolor. Dans un second temps, nous avons tenté d’identifier les gènes impliqués dans l’établissement des ectomycorhizes chez le peuplier en combinant une approche de détection par QTLs et par puces à ADN. Nous avons ciblé 81 gènes potentiellement impliqués dans l’établissement et/ou le fonctionnement de la symbiose. / The mycorrhizal symbioses between fungi and roots concern 95 % of the plant species. Social trees of boreal and temperate forests form a particular type of root association with fungi: the ectomycorrhizal symbiosis. Ectomycorrhizas play a major role in tree hydromineral nutrition, nutrient cycles and primary production. However, their complexity have so far prevented from deciphering their precise function and role. The recent availability of the genome of the ectomycorrhizal fungus Laccaria bicolor and that of the host-tree Populus trichocarpa provides an unprecedented opportunity to decipher the key components of development and functioning of this symbiosis. The aims of this study were to participate to the characterization and deciphering of the genome of L. bicolor, and to determine the genes involved in the formation of ectomycorrhizas in both partners. Firstly, in order to facilitate the assembly of the genomic sequence of L. bicolor, we have identified the repeated sequences and generated a genetic map. On the 60 Mb of this genome, 8 % are microsatellite sequences and 24 % transposable elements. A genetic map was built from 111 monokaryons issued from L. bicolor S238N. This map includes 326 markers (8 RAPD, 243 AFLP, 59 SSR and 14 SNP) distributed on 10 linkage groups anchored onto the genomic sequence of L. bicolor. Secondly, we have identified the genes involved in the establishment of ectomycorrhizas in poplar by combining QTL detection and DNA microarrays. We targeted 81 genes which can be involved in the establishment and/or the functioning of the symbiosis.

Le résumé en français n'a pas été communiqué par l'auteur. / Markets and their operation is of vital importance for economic efficiency and growth. In this thesis I analyse market strategies underlying the important factors that guarantee the optimality of firms' investments for three different market environments. The first chapter refers on how we can use state-of-art instruments by the transmission network of the electricity market to induce the generators to adopt optimal investment planning. Coordinating the timing and location of new production facilities is one of the challenges of liberalized power sectors. It is complicated by the presence of transmission bottlenecks, oligopolistic competition, and the unknown prospects of low-carbon technologies. We build a model encompassing a late and early investment stage, two technologies, and a single transmission bottleneck and compare dynamic efficiency of several market designs. Allocating network access on a short-term competitive basis distorts investment decisions as firms will pre-empt competitors by investing early. Compensating early investors for future network congestion, as is the case in the E.U., only exacerbates this problem. Dynamic efficiency is restored with long-term transmission rights that can be resold on a secondary market. As early investment lowers the resale value of the transmission rights, firms will invest optimally. We show that dynamic efficiency does not require firms to trade physical rights for accessing the transmission line, but financial rights on receiving the scarcity revenues generated by the transmission line suffice. The second chapter focuses on investments on innovation and the way they are particularly affected for different types of industries by product market competition and the existence of financial constraints. It illustrates that, besides its well-studied impact on the incentives to innovate, product market competition also affects the financial capacity to innovate. As innovation projects are by definition risky and external financing is subject to moral hazard concerns, lenders may be reluctant to finance the projects of firms that are not considered credible borrowers. I develop a step-by-step innovation model and show how product market competition may restrict the ability of firms to be credible borrowers. This effect can become the main driver of R&D activities when firms are financial constrained and market competition fierce. It is the follower firms in sectors with high technology dispersion that are mostly affected. Moreover, for intermediate levels of competition, financial constraints induce firms in industries with low technology dispersion to invest more in R&D and move toward the technological frontier as they reduce the ability of their competitors that left behind to innovate. The last chapter focuses on competition for prominence in the organic results of a search engine which account for more than 80-90% of online traffic. Firms decide about how to allocate their investments between search engine optimization strategy and improvement of their products and services' quality. Using a monopolistic competition model with consumer search we evaluate the impact of the search engine algorithm on firms' optimal allocation of investments, estimating how quality is affected by the presence of search engine optimization techniques. We find that despite the additional investment cost, search engine optimization helps search engines to rank more efficiently firms and consequently it induces firms to invest more in the quality of their products. Consumer surplus also increases as consumers find easier good matches to their queries at minimum search cost. Under particular conditions total welfare also increases.

Zugl.: Kassel, Universiẗat, Diss., 2007.

<p>The purpose of this investigation is to reveal those hidden factors, which influence how leadership is practised, as well as the roles male and female play in their professions. Furthermore this investigation aims to elude the expectations and demands that leaders experience and their origin.</p><p>The investigation is based on six interviews of senior managers, two male and four female. A qualitative approach has been utilized to penetrate the subject and understanding of the identified phenomenon. </p><p>The theories employed to analyse the finding are Lincoln, Gerth & Mills and Merton. To further highlight certain specific results parts of Ahrne, Beck & Beck-Gernsheim theories have also been empoyeed. </p><p>This study has generated a new concept, “Dual Leadership”, with the aim of understanding the more diffuse concept of “Female Leadership”. Via investigating how and if the respondents interact between their rolls, an understanding of the </p><p>Socialisationprocesse significance identified factors that indirectly influence the shaping of leadership.</p><p>The primary conclusion is that via disregarding the epithet female leadership and instead introduces the concept of Dual Leadership, both leaders and organisations despite gender can benefit and generate a richer and more equal society where experiences and knowledge are adopted.</p>

No description available.

The purpose of this investigation is to reveal those hidden factors, which influence how leadership is practised, as well as the roles male and female play in their professions. Furthermore this investigation aims to elude the expectations and demands that leaders experience and their origin. The investigation is based on six interviews of senior managers, two male and four female. A qualitative approach has been utilized to penetrate the subject and understanding of the identified phenomenon. The theories employed to analyse the finding are Lincoln, Gerth & Mills and Merton. To further highlight certain specific results parts of Ahrne, Beck & Beck-Gernsheim theories have also been empoyeed. This study has generated a new concept, “Dual Leadership”, with the aim of understanding the more diffuse concept of “Female Leadership”. Via investigating how and if the respondents interact between their rolls, an understanding of the Socialisationprocesse significance identified factors that indirectly influence the shaping of leadership. The primary conclusion is that via disregarding the epithet female leadership and instead introduces the concept of Dual Leadership, both leaders and organisations despite gender can benefit and generate a richer and more equal society where experiences and knowledge are adopted.

No description available.