This paper develops a quantitative model of internal city structure that features agglomeration and dispersion forces and an arbitrary number of heterogeneous city blocks. The model remains tractable ...and amenable to empirical analysis because of stochastic shocks to commuting decisions, which yield a gravity equation for commuting flows. To structurally estimate agglomeration and dispersion forces, we use data on thousands of city blocks in Berlin for 1936, 1986, and 2006 and exogenous variation from the city's division and reunification. We estimate substantial and highly localized production and residential externalities. We show that the model with the estimated agglomeration parameters can account both qualitatively and quantitatively for the observed changes in city structure. We show how our quantitative framework can be used to undertake counterfactuals for changes in the organization of economic activity within cities in response, for example, to changes in the transport network.
Abstract Using newly constructed spatially disaggregated data for London from 1801 to 1921, we show that the invention of the steam railway led to the first large-scale separation of workplace and ...residence. We show that a class of quantitative urban models is remarkably successful in explaining this reorganization of economic activity. We structurally estimate one of the models in this class and find substantial agglomeration forces in both production and residence. In counterfactuals, we find that removing the whole railway network reduces the population and the value of land and buildings in London by up to 51.5% and 53.3% respectively, and decreases net commuting into the historical center of London by more than 300,000 workers.
This paper exploits the division of Germany after the Second World War and the reunification of East and West Germany in 1990 as a natural experiment to provide evidence for the importance of market ...access for economic development. In line with a standard new economic geography model, we find that, following division, cities in West Germany close to the East-West German border experienced a substantial decline in population growth relative to other West German cities. We show that the model can account for the quantitative magnitude of our findings and provide additional evidence against alternative possible explanations.
This paper develops a simple model to analyse how a lack of political competition may lead to policies that hinder economic growth. We test the predictions of the model on panel data for the US ...states. In these data, we find robust evidence that lack of political competition in a state is associated with anti-growth policies: higher taxes, lower capital spending, and a reduced likelihood of using rightto- work laws. We also document a strong link between low political competition and low income growth.
Periodic elections are the main instrument through which voters can hold politicians accountable. From this perspective term limits, which restrict voters' ability to reward politicians with ...re-election, appear counterproductive. We show that despite the disciplining effect of elections, term limits can be ex-ante welfare improving from the perspective of voters. By reducing the value of holding office, term limits can induce politicians to implement policies that are closer to their private preferences. Such “truthful” behavior by incumbents in turn results in better screening of incumbents. We characterize under which circumstances two-term or even longer term limits are the optimal institution for voters.
•Voters hold politicians accountable through periodic elections.•We show that term limits can nevertheless be in the interest of voters.•Term limits induce politicians to choose policies closer to their own preferences.•Such “truthful” behavior in turn results in better screening of incumbents.•We characterize when two-term or longer term limits are optimal for voters.
Abstract—A central prediction of a large class of theoretical models is that industry location is not uniquely determined by fundamentals. Despite the theoretical prominence of this idea, there is ...little systematic evidence in support of its empirical relevance. This paper exploits the division of Germany after World War II and the reunification of East and West Germany as an exogenous shock to industry location. Focusing on a particular economic activity, an air hub, we develop a body of evidence that the relocation of Germany's air hub from Berlin to Frankfurt in response to division is a shift between multiple steady states.
This paper evaluates the impact of changes in public employment on private sector activity using the creation of the new West German government in Bonn in the wake of the Second World War as a source ...of exogenous variation. To guide our empirical analysis, we develop a simple economic geography model in which public sector employment affects private sector employment through its impact on wages and house prices and also through potential productivity and amenity spillovers to the private sector. We find that relative to a control group of cities, Bonn experiences a substantial increase in public employment. However, this results in only modest increases in private sector employment with each additional public sector job destroying around 0.2 jobs in industry and creating just over one additional job in other parts of the private sector. We show how our model can explain this finding and provide several pieces of evidence for the mechanisms emphasized by the model.
Helium nanodroplets are considered ideal model systems to explore quantum hydrodynamics in self-contained, isolated superfluids. However, exploring the dynamic properties of individual droplets is ...experimentally challenging. In this work, we used single-shot femtosecond x-ray coherent diffractive imaging to investigate the rotation of single, isolated superfluid helium-4 droplets containing ~10⁸ to 1011 atoms. The formation of quantum vortex lattices inside the droplets is confirmed by observing characteristic Bragg patterns from xenon clusters trapped in the vortex cores. The vortex densities are up to five orders of magnitude larger than those observed in bulk liquid helium. The droplets exhibit large centrifugal deformations but retain axially symmetric shapes at angular velocities well beyond the stability range of viscous classical droplets.
Interferon regulatory factor (IRF) family members impart cell‐type specificity to toll‐like receptor (TLR) signalling, and we recently identified a role for IRF6 in TLR2 signalling in epithelial ...cells. TLR3 has a well‐characterized role in wound healing in the skin, and here, we examined TLR3‐dependent IRF6 functions in human keratinocytes. Primary keratinocytes responded robustly to the TLR3 agonist poly(IC) with upregulation of mRNAs for interferon‐β (IFN‐β), the interleukin‐12 (IL‐12) family member IL‐23p19 and the chemokines IL‐8 and chemokine (C–C motif) ligand 5 (CCL5). Silencing of IRF6 expression enhanced poly(IC)‐inducible IFN‐β mRNA levels and inhibited poly(IC)‐inducible IL‐23p19 mRNA expression in primary keratinocytes. Consistent with these data, co‐transfection of IRF6 increased poly(IC)‐inducible IL‐23p19 promoter activity, but inhibited poly(IC)‐inducible IFN‐β promoter activity in reporter assays. Surprisingly, poly(IC) did not regulate IL‐12p40 expression in keratinocytes, suggesting that TLR3‐inducible IL‐23p19 may have an IL‐23‐independent function in these cells. The only other IL‐12 family member that was strongly poly(IC) inducible was EBI3, which has not been shown to heterodimerize with IL‐23p19. Both co‐immunoprecipitation and proximity ligation assays revealed that IL‐23p19 and EBI3 interact in cells. Co‐expression of IL‐23p19 and EBI3, as compared with IL‐23p19 alone, resulted in increased levels of secreted IL‐23p19, implying a functional role for this heterodimer. In summary, we report that IRF6 regulates a subset of TLR3 responses in human keratinocytes, including the production of a novel IL‐12 family heterodimer (p19/EBI3). We propose that the TLR3‐IRF6‐p19/EBI3 axis may regulate keratinocyte and/or immune cell functions in the context of cell damage and wound healing in the skin.
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