Size of nested cities

Models of cities based on conventional spatial market theory are unable to replicate a realistic size distribution. The stochastic process approach to size distribution, which assumes proportionate growth, does not provide an economic foundation for spatial trades. There is an apparent irreconcilability. We propose that since there is a continuum of equilibria in models of spatial markets with endogenous location, proportionate growth can work as equilibrium selection. We present computations for an urban configuration that has not been presented in the literature before. A small city locates inside a larger city's agricultural supply zone. This generates a larger variation in city size that may include a realistic size distribution.     

船舶结构焊接结晶裂纹的产生与防止

焊接结构中焊接裂纹经常出现,其中结晶裂纹是最容易产生的一种裂纹。本文介绍了焊接结构中结晶裂纹产生的原因,并提出了有效的预防措施。     

范围经济视域下范围产品的技术关联性研究——基于有形产品的视角

企业通过充分利用剩余资源生产加工出来的不同产品之间形成了资源的相关性。企业带来范围经济的一组产品之间必然存在着内在的关联。技术作为一种极其重要的生产要素,它通过产品的技术关联为企业创造范围经济成为范围产品关联的重要表现方式。范围产品之间存在着局部独立关联、局部交叉关联、技术整体关联和技术混合关联四种形式。技术的规模化、员工的专业化、设备的高效化是技术关联创造范围经济的内在机制。企业在实施多元化战略时,要充分考虑自身所处的行业特征及经营阶段,采取合适的技术关联方式,充分创造范围经济。     

How much can we trust China’s investment statistics?

Abstract

Building upon recent research into the underestimation of China’s official final consumption expenditure, this paper investigates the quality of China’s investment data. We strictly follow the official method to estimate the annual gross fixed capital formation (GFCF) expenditure from 2004 to 2012, and the resulting figures are significantly different from the official statistics. This implies that the ‘total investment in fixed assets’ data, which are the primary source for the estimation of GFCF, grossly exaggerate actual investments, and that the official GFCF figures are not, strictly speaking, independently estimated, as they are purported to be. We deduce that the official gross capital formation figure is more or less a residual item obtained by subtracting final consumption and net exports from the official GDP figure that is calculated based on the production-cum-income approach. As a result, the underestimation of China’s consumption expenditure automatically translates into overestimation of investment expenditure. We conclude that China’s official consumption and investment statistics cannot be trusted as the basis for policy discussions and academic research.     

What Drives the Historical Formation and Persistent Development of Territorial States?

The importance of the length of state history for understanding variations in income levels and growth rates across countries has received a lot of attention in the recent literature on long‐run comparative development. The literature, however, is silent about its origins. This paper explores the determinants of statehood by considering the potential roles of an early transition to fully‐fledged agricultural production, the adoption of state‐of‐the‐art military innovations, and the opportunity for economic interaction with the regional economic leader. The results demonstrate that only the association between economic interaction and the rise and development of the state is statistically robust.     

Bond Pricing with a Time‐Varying Price of Risk in an Estimated Medium‐Scale Bayesian DSGE Model

New Keynesian model in which households have Epstein–Zin preferences with time‐varying risk aversion and the central bank has a time‐varying inflation target can match the dynamics of nominal bond prices in the U.S. economy well. The model generates a large steady‐state term spread and its fitting errors for bond yields are comparable to those obtained from a nonstructural three‐factor model, and one‐third smaller than in models with a constant inflation target or risk aversion. Including data on interest rates has large effects on variance decompositions, making investment technology shocks much less important than found in other recent papers.     

Separate when equal? Racial inequality and residential segregation

This paper sets out a new mechanism involving the emergence of middle-class black neighborhoods that can lead segregation in American cities to increase as racial inequality narrows. The formation of such neighborhoods requires a critical mass of highly educated blacks in the population, and leads to an increase in segregation when those communities are attractive for blacks who would otherwise reside in middle-class white neighborhoods. To assess the empirical importance of this “neighborhood formation” mechanism, we propose a two-part research design. First, inequality and segregation should be negatively related in cross section for older blacks if our mechanism operates strongly, as we find using both the 1990 and 2000 Censuses. Second, a negative relationship should also be apparent over time, particularly for older blacks. Here, we show that increased educational attainment of blacks relative to whites in a city between 1990 and 2000 leads to a significant rise in segregation, especially for older blacks, and to a marked increase in the number of middle-class black communities. These findings draw attention to a negative feedback loop between racial inequality and segregation that has implications for the dynamics of both phenomena.     

Localizing Land Governance,Strengthening the State: Decentralization and Land Tenure Security in Uganda

Decentralization of land governance is expected to significantly improve land tenure security of small‐scale farmers in Africa, through ensuring better protection of their assets and reducing land‐related conflicts. This paper, however, cautions not to have too high expectations of transferring responsibilities for land administration and dispute resolution to local government bodies. Field research in Mbarara District in south‐western Uganda brings out how decentralization has limited impacts in terms of localizing land services provision. Nonetheless, local land governance has transformed in important ways, as decentralization adds to institutional multiplicity, and fuels competition among state and non‐state authorities, and about the rules they apply. Rather than strengthening local mechanisms for securing tenure, the reforms introduce new forms of tenure insecurity, fail to transform local conventions of dealing with land disputes and delegitimize local mechanisms for securing tenure. In practice, decentralization has had limited effects in securing tenure for the rural poor, yet reinforces the presence of the state at the local level in diverse ways.     

Migration,Friendship Ties,and Cultural Assimilation

We study immigrant assimilation by analyzing whether friendship with natives is a measure of cultural assimilation, and by investigating the formation of social ties. Using the German Socio‐Economic Panel, we find that immigrants with a German friend are more similar to natives than those without German friends, along several important dimensions, including concerns about the economy, an interest in politics, and a host of policy issues. Turning to friendship acquisition, we find that becoming employed, time spent in the host country, the birth of a child, residential mobility, and additional education acquired in the host country are significant drivers of social network variation.