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Zusammenfassung gemäß § 11 der Promotionsordnung der Fakultät II (Fassung 01.10.05) und den „Allgemeinen Richtlinien des Senats über die Veröffentlichung von Dissertationen und die Ablieferung von Pflichtexemplaren“ (Senatsbeschluss vom 14.7.1999) zu meiner Dissertation mit dem Titel: „Modeling the New Economic Geography – R&D, Vertical Linkages, Policy Implications“ The present work introduces four theoretical papers, which primarily focus on R&D, interindustrial linkages, and their policy implications. All in all, three issues basically motivated conception and realization: At first, previous NEG models do not incorporate endogenous R&D activities of firms. Existing models include R&D only in a growth context, which increases the formal complexity and departs from the simple core-periphery formulation. Second, vertical linkages are extensively considered in the class of international models. In face of its formal simplicity, the majority of publications refer to the standard model of Krugman and Venables (1995) utilizing intra-industry trade in which the manufacturing sector produces its own intermediates. However, the results are similar to the core-periphery model, but the implications of vertical linkages, especially in terms of specialization, cannot be reproduced. In contrast, the more challenging version of Venables (1996), which considers an inter-industry framework of an explicit upstream and downstream sector, is often cited (143 citations according to IDEAS/RePEc), but only few papers were directly built on it: Puga and Venables (1996), Amiti (2005), Alonso-Villar (2005). The third issue concerns the calibration of real economies. Although, hundreds of numerical simulations have been done in order to display the modeling outcomes, an application to particular industries in terms of their spatial formation and evolution is still a neglected field of research. Against this background, the present work aims to make a contribution to these topics. For a summary, all four papers are briefly to be summarized at this point. The first paper, entitled 'Too Much R&D? – Vertical Differentiation and Monopolistic Competition,' discusses whether product R&D in developed economies tends to be too high compared with the socially desired level. In this context, a model of vertical and horizontal product differentiation within the Dixit-Stiglitz (1977) framework of monopolistic competition is set up where firms compete in horizontal attributes of their products, and also in quality that can be controlled by R&D investments. The paper reveals that in monopolistic-competitive industries, R&D intensity is positively correlated with market concentration. Furthermore, welfare and policy analysis demonstrate an overinvestment in R&D with the result that vertical differentiation is too high and horizontal differentiation is too low. The only effective policy instrument in order to contain welfare losses turns out to be a price control of R&D services. The main contribution of this closed economy model in the course of the present work is a modeling framework, which can easily be adapted to the New Economic Geography. This has been approached in the second paper: ‘R&D and the Agglomeration of Industries' in which the seminal core-periphery model of Krugman (1991) is extended by endogenous research activities. Beyond the common ‘anonymous' consideration of R&D expenditures within fixed costs, this model introduces vertical product differentiation, which requires services provided by an additional R&D sector. In the context of international factor mobility, the destabilizing effects of a mobile scientific workforce are analyzed. In combination with a welfare analysis and a consideration of R&D promoting policy instruments and their spatial implications, this paper also makes a contribution to the brain-drain debate. In contrast to this migration based approach, the third paper 'Agglomeration, Vertical Specialization, and the Strength of Industrial Linkages' focuses on vertical linkages in their capacity as an additional agglomeration force. The paper picks up the seminal model of Venables (1996) and provides a quantifying concept for the sectoral coherence in vertical-linkage models of the New Economic Geography. Based upon an alternative approach to solve the model and to determine critical trade cost values, this paper focuses on the interdependencies between agglomeration, specialization and the strength of vertical linkages. A central concern is the idea of an 'industrial base,' which is attracting linked industries but is persistent to relocation. As a main finding, the intermediate cost share and substitution elasticity basically determine the strength of linkages. Thus, these parameters affect how strong the industrial base responds to changes in trade costs, relative wages and market size. The fourth paper 'The Spatial Dynamics of the European Biotech Industry' presents a simulation study of the R&D intensive biotech industry using the standard Venables model. Thus, it connects all three preceding papers and puts them into the real economic context of the European integration. The paper reviews the potential development of the European biotech industry with respect to its spatial structure. On the first stage, the present industrial situation as object of investigation is described and evaluated with respect to a further model implementation. In this context, the article introduces the findings of an online survey concerning international trade, conducted with German biotech firms in 2006. On the second stage, the results are completed by the outcomes of a numerical simulation within the New Economic Geography (NEG), considering vertical linkages between the biotech and pharmaceutical industries as an agglomerative force. The analysis reveals only a slight relocation tendency to the European periphery, constrained by market size, infrastructure and factor supply. In the final conclusions, central results of all four papers are summarized with respect to economic policy. Against the background of general legitimization and the impact of political intervention, Chapter 6 draws the main conclusions for location and innovation policies. In this regard, the industrial-base concept as well as the mobility of R&D play a central role during this discussion.