Migration and Urban Poverty and Inequality in China

Using data from recent surveys of migrants and local residents in 10 cities in 2005, this paper examines how migration influences measurements of urban poverty and inequality in China, and also compares how other indicators of well-being differ for migrants and local residents. Contrary to previous studies that report that the income poverty rate of migrant households is 1.5 times that of local resident households, we find relatively small differences in the poverty rates of migrants and local residents. Although the hourly wages of migrants are much lower than those of local residents, migrant workers work longer hours and have lower dependency ratios and higher labor force participation rates. Including migrants increases somewhat measures of urban income inequality. Significant differences between migrants and local residents are found for non-income welfare indicators such as housing conditions and access to social insurance programs.migration, urban, poverty, inequality, social protection, China

Who makes market

We explore the role of dealers to determine whether they are liquidity-providing market makers or liquidity-taking information traders. Standard models of market making, such as Kyle (1985) and Grossman and Miller (1988), imply a negative contemporaneous correlation between market maker order flow and stock returns. We test this relation with a unique dataset containing trades of all dealers in a well-developed, liquid market. The correlation is strongly positive, implying that dealers take liquidity. We also develop a unique profit decomposition to compare intraweek information and market making profits. Dealers earn significant excess returns, in aggregate driven by information rather than market making. Subgroup analysis reveals that information profits are positive and increasing in stock capitalization, and market making returns are positive and significant for all but the largest stocksDealer, Liquidity Provision

Quantifying Long-Term Scientific Impact

The lack of predictability of citation-based measures frequently used to gauge impact, from impact factors to short-term citations, raises a fundamental question: Is there long-term predictability in citation patterns? Here, we derive a mechanistic model for the citation dynamics of individual papers, allowing us to collapse the citation histories of papers from different journals and disciplines into a single curve, indicating that all papers tend to follow the same universal temporal pattern. The observed patterns not only help us uncover basic mechanisms that govern scientific impact but also offer reliable measures of influence that may have potential policy implications

The great proletarian cultural revolution, disruptions to education, and returns to schooling in urban China

In determining whether a country's higher education system should be expanded, it is important for policymakers first to determine the extent to which high private returns to post-secondary education are an indication of the scarcity of graduates instead of the high unobserved ability of students who choose to attend post-secondary education. To this end, the paper identifies the returns to schooling in urban China using individual-level variation in educational attainment caused by exogenous city-wide disruptions to education during the Cultural Revolution from 1966 to 1976. For city-cohorts who experienced greater disruptions, children's educational attainment became less correlated with that of their fathers and more influenced by whether their fathers held administrative positions. The analysis calculates returns to college education using data from the China Urban Labor Survey conducted in five large cities in 2001. The results are consistent with the selection of high-ability students into higher education. The analysis also demonstrates that these results are unlikely to be driven by sample selection bias associated with migration, or by alternative pathways through which the Cultural Revolution could have affected adult productivity.Education For All,Tertiary Education,Secondary Education,Primary Education,Population Policies

On absolute Galois splitting fields of central simple algebras

A splitting field of a central simple algebra is said to be absolute Galois if it is Galois over some fixed subfield of the centre of the algebra. The paper provides an existence theorem for such fields over global fields with enough roots of unity. As an application, all twisted function fields and all twisted Laurent series rings over symbol algebras (or p-algebras) over global fields are crossed products. A closely related statement holds for division algebras over Henselian valued fields with global residue field. The existence of absolute Galois splitting fields in central simple algebras over global fields is equivalent to a suitable generalization of the weak Grunwald-Wang Theorem, which is proved to hold if enough roots of unity are present. In general, it does not hold and counter examples have been used in noncrossed product constructions. This paper shows in particular that a certain computational difficulty involved in the construction of explicit examples of noncrossed product twisted Laurent series rings can not be avoided by starting the construction with a symbol algebra.Comment: 12 pages (A4); to appear in J. Number Theory (2007

Do Investors Learn About Analyst Accuracy?

We study the impact of analyst forecasts on prices to determine whether investors learn about analyst accuracy. Our test market is the crude oil futures market. Prices rise when analysts forecast a decrease (increase) in crude supplies. In the 15 minutes following supply realizations, prices rise (fall) when forecasts have been too high (low). In both the initial price action relative to forecasts and in the subsequent reaction relative to realized forecast errors, the price response is stronger for more accurate analysts. These price reactions imply that investors learn about analyst accuracy and trade accordingly.Financial Economics, Institutional and Behavioral Economics, Political Economy,

Mechanical Characterization of Fourth Generation Composite Humerus

Mechanical data on upper extremity surrogate bones, supporting use as biomechanical tools, is limited. The objective of this study was to characterize the structural behaviour of the fourth-generation composite humerus under simulated physiologic bending, specifically, stiffness, rigidity, and mid-diaphysial surface strains. Three humeri were tested in four-point bending, in anatomically defined anteroposterior (AP) and mediolateral (ML) planes. Stiffness and rigidity were derived using load–displacement data. Principal strains were determined at the anterior, posterior, medial, and lateral surfaces in the humeral mid-diaphysial transverse plane of one specimen using stacked rosettes. Linear structural behaviour was observed within the test range. Average stiffness and rigidity were greater in the ML (918 ± 18 N/mm; 98.4 ± 1.9 Nm2) than the AP plane (833 ± 16 N/mm; 89.3 ± 1.6 Nm2), with little inter-specimen variability. The ML/AP rigidity ratio was 1.1. Surface principal strains were similar at the anterior (5.41 µε/N) and posterior (5.43 µε/N) gauges for AP bending, and comparatively less for ML bending, i.e. 5.1 and 4.5 µε/N, at the medial and lateral gauges, respectively. This study provides novel strain and stiffness data for the fourth-generation composite humerus and also adds to published construct rigidity data. The presented results support the use of this composite bone as a tool for modelling and experimentation

Ising model simulation in directed lattices and networks

On directed lattices, with half as many neighbours as in the usual undirected lattices, the Ising model does not seem to show a spontaneous magnetisation, at least for lower dimensions. Instead, the decay time for flipping of the magnetisation follows an Arrhenius law on the square and simple cubic lattice. On directed Barabasi-Albert networks with two and seven neighbours selected by each added site, Metropolis and Glauber algorithms give similar results, while for Wolff cluster flipping the magnetisation decays exponentially with time.Comment: Expanded to 8 pages: additional author, additional result