Typical bifurcation scenario in a three region identical New Economic Geography model

EU enlargement and the internal geography of countries

Dynamic agglomeration patterns in a two-country new economic geography model with four regions

New Economic Geography models describe a cumulative process of spatial agglomeration: Firms tend to cluster in locations with good access to demand, and similarly, workers are drawn to regions where market potential is high because the price index is lower there. This paper provides an empirical assessment of this forward linkage that relates labour migrations to the geography of production through real wage differentials. In the spirit of Hanson (1998), we use bilateral migration data for five European countries over the 1980s and 1990s to perform quasi-structural estimations of a new economic geography model derived from Krugman (1991). The results show strong evidence in favor of this model. As expected, migrants do follow market potential. Moreover, we provide estimates for all key parameters of the model. These estimates suggest that a sudden emergence of a core-periphery pattern is unlikely within European countries: centripetal forces are too limited in geographical scope, and mobility costs are too high.

Two aspects of New Economic Geography models are often singled out for criticism, especially by geographers: the treatment of geography, typically as a pre-given, fixed and highly idealized abstract geometric space; and the treatment of history, typically as ‘logical’ time (the movement to equilibrium in a model's solution space) rather than real history. In this paper we examine the basis for these criticisms, and explore how far and in what ways NEG models might be made more credible with respect to their representation of geography and history, and particularly whether and to what extent the work of geographers themselves provides some insights in this regard. We argue that the conceptualization of space and time is in fact a challenge for both NEG theorists and economic geographers, and that, notwithstanding their ontological and epistemological differences, both groups would benefit from an interchange of ideas on this front. Réinventer les (nouveaux) modèles de géographie économique: comment prendre la géographie et l'histoire plus au sérieux Rèsumè Deux aspects particuliers des modèles de la nouvelle géographie économique sont souvent l'objet de critiques, notamment de la part des géographes, à savoir: le traitement de la géographie, généralement comme un espace géométrique abstrait prédéterminé, fixe et extrêmement idéalisé, et le traitement de l'histoire, généralement comme un créneau ‘logique’ (un mouvement vers l’équilibre dans un espace à solution du modèle) et non pas comme l'histoire réelle. Dans la présente communication, nous nous penchons sur le fondement de ces critiques, et nous examinons dans quelle mesure les modèles de la NEG pourraient devenir plus plausibles sur le plan de la façon dont ils représentent la géographie et l'histoire, notamment si le travail des géographes apporte de nouveaux éléments sur cette question, et dans quelle mesure. Nous soutenons que la conceptualisation de l'espace et du temps constitue, en fait, un défi tant pour les théoriciens de la NEG que pour les géographes économiques, et qu'au-delà de leurs différences ontologiques et épistémologiques, un échange d'idées sur ce sujet serait bénéfique pour ces deux groupes. Reconsideración de modelos de (Nueva) Geografía Económica: Tomando más en serio la geografía y la historia Extracto A menudo, existen dos aspectos particulares de los modelos de Nueva Geografía Económica que reciben críticas, especialmente por parte de los geógrafos: el tratamiento de la geografía, típicamente como un espacio geométrico abstracto altamente idealizado, fijo y predeterminado; y, el tratamiento de la historia, típicamente como un tiempo ‘lógico’ (el movimiento hacia el equilibrio en el espacio de solución de un modelo), en lugar de como historia real. En este estudio examinamos la base de estas críticas y exploramos hasta qué punto y de qué formas, los modelos NEG podrían hacerse más creíbles con respecto a su representación de la geografía e historia, y particularmente, si, y hasta qué punto el trabajo de los geógrafos mismos proporciona algún tipo de visión interna en esta cuestión. Discutimos que la conceptualización del espacio y el tiempo es, de hecho, un reto para los teóricos NEG y los geógrafos económicos, y que, independientemente de sus diferencias ontológicas y epistemológicas, ambos grupos se beneficiarían de un intercambio de ideas en este campo.

International Integration and Regional Inequalities: How Important is National Infrastructure?

For reasons of analytical tractability, new economic geography (NEG) models treat geography in a very simple way: attention is either confined to a simple 2-region or to an equidistant multi-region world. As a result, the main predictions regarding the impact of e.g. diminishing trade costs are based on these simple models. When doing empirical or policy work these simplifying assumptions become problematic and it may very well be that the conclusions from the simple models do not carry over to the heterogeneous geographical setting faced by the empirical researcher or policy maker. This paper tries to fill this gap by adding more realistic geography structures to the Puga (1999) model that encompasses several benchmark NEG models. By using extensive simulations we show that many, although not all, conclusions from the simple models do carry over to our multi-region setting with more realistic geography structures. Given these results, we then simulate the impact of increased EU integration on the spatial distribution of regional economic activity for a sample of 194NUTSII regions and find that further integration will most likely be accompanied by higher levels of agglomeration.

In early development, morphogen gradients orchestrate the establishment of body axes. Perturbations of such a fundamental process are often damaging to embryonal development, making it difficult to study the role of body patterning factors later during development or even in adult animals. The planarian flatworm Schmidtea mediterranea provides a valuable model for addressing this challenge: Its pluripotent stem cell population does not only allow it to regenerate and reestablish its body axes after injury but is also required for dynamic tissue turnover and body plan maintenance. Therefore, by introducing perturbations of body axis patterning by RNA-interference we can study the remodeling of the body plan and the functions of patterning factors in an adult animal. A specifically interesting body plan determinant is Bone morphogenetic protein (BMP), a member of the TGFβ signaling family, which has been shown to not only pattern the dorso-ventral axis in S. mediterranea, but also influences anterior-posterior and mediolateral patterning. It is expressed on the dorsal side in a mediolateral gradient with the highest expression on the midline and fading intensity towards the body edge. However, how this mediolateral bmp expression gradient is formed is poorly understood. Moreover, the spatial distribution of BMP signaling activity through the planarian body remains unstudied so far. The overall goal of my thesis was to probe the mechanistic basis of BMP gradient formation in S. mediterranea. In the first part, I systematically annotated the TGFβ signaling pathway components including BMP in the S. mediterranea genome and reconstructed their phylogeny in the context of other metazoans. Next, I established a Western blotting assay for the quantification of BMP signaling activity in response to the knockdown of potential BMP signaling factors. Furthermore, I established a whole mount immunostaining assay for the activated BMP signaling transducer phospho-Smad1 to reveal the spatial patterns of BMP signaling activity. With these tools at hand, I was able to quantify BMP signaling activity and visualize its spatial distribution throughout the planarian body. In the last part of the thesis, I utilized these methods to gain understanding of the mechanisms that establish the mediolateral expression profile of bmp in S. mediterranea. I found previously undescribed TGFβ ligands and identified candidates for putative regulators of BMP4 signaling activity in an RNAi screen. Furthermore, I was able to visualize the spatial distribution of BMP signaling activity in S. mediterranea wild type animals and found that BMP signaling is not only active in the sites of dorsal bmp4 expression, but also occurs in other tissues like the gut. Moreover, my findings indicate that BMP signaling is likely involved in gut branching. By assessing the expression pattern of bmp4 and the spatial distribution of BMP signaling activity, I found indications for autoregulation of BMP signaling in S. mediterranea, possibly by a patterning organizer on the midline. Moreover, the metalloproteinase Tolloid is possibly necessary for long range BMP signal distribution from the midline to the body edge and influences muscle development. In summary, my work provides an overview of the TGFβ signaling components of S. mediterranea and their phylogenetic relation to components of other metazoans, new assays to assess BMP signaling activity in S. mediterranea, and insights into the mechanisms of the mediolateral distribution of BMP signaling activity.

Abstract. This work aims to assess the performance of state-of-the-art global climate models in representing the upper-tropospheric Rossby wave pattern in the Northern Hemisphere and over the European–Atlantic sector. A diagnostic based on finite-amplitude local wave activity is used as an objective metric to quantify the amplitude of Rossby waves in terms of Rossby wave activity. This diagnostic framework is applied to a set of coupled historical climate simulations at different horizontal resolutions, performed in the framework of the PRIMAVERA project and compared with observations (ERA5 reanalysis). At first, the spatio-temporal characteristics of Rossby wave activity in the Northern Hemisphere are examined in the multimodel mean of the whole PRIMAVERA set. When examining the spatial distribution of transient wave activity, only a minimal improvement is found in the high-resolution ensemble. On the other hand, when examining the temporal variability of wave activity, a higher resolution is beneficial in all models apart from one. In addition, when examining the Rossby wave activity time series, no evident trends are found in the historical simulations (at both standard and high resolutions) and in the observations. Finally, the spatial distribution of Rossby wave activity is investigated in more detail focusing on the European–Atlantic sector, examining the wave activity pattern associated with weather regimes for each model. Results show a marked inter-model variability in representing the correct spatial distribution of Rossby wave activity associated with each regime pattern, and an increased horizontal resolution improves the models' performance only for some of the models and for some of the regimes. A positive impact of an increased horizontal resolution is found only for the models in which both the atmospheric and oceanic resolution is changed, whereas in the models in which only the atmospheric resolution is increased, a worsening model performance is detected.

Comprehensive zoning is ubiquitous in U.S. cities, yet we know surprisingly little about its longrun impacts. We provide the first attempt to measure the causal effect of land use regulation over the long term, using as our setting Chicago's first (1923) comprehensive zoning ordinance. Our results indicate that zoning has had a broader and more significant impact on the spatial distribution of economic activity than was previously believed. In particular, zoning may be more important than either geography or transportation networks -the workhorses of urban economic geography models -in explaining where commercial and industrial activity are located.

Coping with inefficiencies in a New Economic Geography model: The unintended consequences of policy interventions

The article is dedicated to describing the capabilities of the cooperative game theory for studying spatial distribution of economic activity. The paper discusses the features of cooperative games the spatial connotation of which drives from the fact that they formalize the conflict between the forces aimed at concentration of economic activity, and the forces aimed at its dispersion (hereinafter ‘the fundamental conflict’). The author proposes a classification of spatial cooperative games based on: 1) the method of specifying the set of players, 2) the type of solution to the fundamental conflict. The players in the models under consideration are the elements of the economic space with either a simple or a complex structure. The elements with a simple structure are economic agents with their objective functions deriving from their rational choices. The elements with a complex structure are aggregates, such as regions, economic areas, or countries. If we consider it possible to describe objective functions for such players, we should use the functions incorporating a great range of decisions made by different economic agents. The article pays special attention to justification of the usage of spatial cooperative games to model interactions between the elements of the economic space with a complex structure. In spatial cooperative games, the fundamental conflict is solved either by creating a spatial projection of economic interactions, and picking the player’s locations or by studying the delocalization of economic interactions and evaluating the coalition productivity of players. The author distinguishes four types of spatial cooperative games and for each class gives an example of a specific application of the game model. Within the given classification, the author studies game models of distribution networks, interregional interactions, service facilities location, spatial growth, and production planning for spatially concentrated firms. The conclusion is that even though spatial cooperative games are used for research on various levels of generalization, they are, first of all, useful as a means of researching the phenomena of economic activity delocalization. Thus, as far as the location theory is concerned, the games act rather as a tool that complements the optimization calculations with evaluations of stability of the obtained solutions to coalitional and migration threats. From the standpoint of the concept of interregional interactions it acts as an independent tool significant for assessing system effects and their distribution between different elements of the economic space. Furthermore, the author suggests that the future of cooperative games as a tool for research on spatial distribution of economic activity is associated with the search for statements that connect the results of analysis of economic space elements with a simple and complex structure

We extend an agent-based model of crime-pattern formation initiated in Short et al. by incorporating the effects of law enforcement agents. We investigate the effect that these agents have on the spatial distribution and overall level of criminal activity in a simulated urban setting. Our focus is on a two-dimensional lattice model of residential burglaries, where each site (target) is characterized by a dynamic attractiveness to burglary and where criminal and law enforcement agents are represented by random walkers. The dynamics of the criminal agents and the target-attractiveness field are, with certain modifications, as described in Short et al. Here the dynamics of enforcement agents are affected by the attractiveness field via a biasing of the walk, the detailed rules of which define a deployment strategy. We observe that law enforcement agents, if properly deployed, will in fact reduce the total amount of crime, but their relative effectiveness depends on the number of agents deployed, the deployment strategy used, and spatial distribution of criminal activity. For certain policing strategies, continuum PDE models can be derived from the discrete systems. The continuum models are qualitatively similar to the discrete systems at large system sizes.

International and regional integration are accompanied by the fear that the reduction of trade barriers might change the spatial distribution of economic activity radically. In the past decade, the ‘New Economic Geography’ has developed as a theory explaining some of the forces which might influence the spatial distribution of economic activity. Since trade costs play a crucial role in this new theory, it is natural to expect the New Economic Geography to contribute substiantially to the understanding of how regional integration might change the economic landscape. This paper reviews the New Economic Geography literature. It turns out that the literature’s theoretical predictions are ambiguous and that the empirical evidence on the theory is very scant so far.

Quantity and spatial distribution of earth-air activity in Cave 108 of the Dunhuang Mogao Grottoes

Spatial distribution of ion channel activity in biological membranes: the role of noise