A test of adverse selection in the market for experienced workers

We show that in labor market models with adverse selection, otherwise observationally equivalent workers will experience less wage growth following a period in which they change jobs than following a period in which they do not. We find little or no evidence to support this prediction. In most specifications the coefficient has the opposite sign, sometimes statistically significantly so. When consistent with the prediction, the estimated effects are small and statistically insignificant. We consistently reject large effects in the predicted direction. We argue informally that our results are also problematic for a broader class of models of competitive labor markets.Othe

Rigidity around Poisson Submanifolds

We prove a rigidity theorem in Poisson geometry around compact Poisson submanifolds, using the Nash-Moser fast convergence method. In the case of one-point submanifolds (fixed points), this immediately implies a stronger version of Conn's linearization theorem, also proving that Conn's theorem is, indeed, just a manifestation of a rigidity phenomenon; similarly, in the case of arbitrary symplectic leaves, it gives a stronger version of the local normal form theorem; another interesting case corresponds to spheres inside duals of compact semisimple Lie algebras, our result can be used to fully compute the resulting Poisson moduli space.Comment: 43 pages, v3: published versio

Analytical investigation of the mixing of two parallel streams of dissimilar fluids

Free jet mixing analysis for parallel streams of different fluid

Experimental investigation of the mixing of two parallel streams of dissimilar fluids

Velocity and density profiles in mixing region between adjacent half jets of dissimilar fluid

Bones, Bombs and Break Points: The Geography of Economic Activity

We consider the distribution of economic activity within a country in light of three leading theories - increasing returns, random growth, and locational fundamentals. To do so, we examine the distribution of regional population in Japan from the Stone Age to the modern era. We also consider the Allied bombing of Japanese cities in WWII as a shock to relative city sizes. Our results support a hybrid theory in which locational fundamentals establish the spatial pattern of relative regional densities, but increasing returns may help to determine the degree of spatial differentiation. One implication of these results is that even large temporary shocks to urban areas have no long-run impact on city size.

Market Size, Linkages, and Productivity: A Study Of Japanese Regions

markets, regions, productivity

Do Endowments Predict the Location of Production? Evidence from National and International Data

Examining the relationship between factor endowments and production patterns using international and Japanese regional data, we provide the first empirical confirmation of Ethier's correlation approach to the Rybczynski theorem. Moreover, we find evidence of substantial production indeterminacy. Prediction errors are six to thirty times larger for goods traded relatively freely. A compelling explanation of this phenomenon is the existence of more goods than factors in the presence of trade costs. This result implies that regressions of trade or output on endowments have weak theoretical foundations. Furthermore, since errors are largest in data sets where trade costs are small, we explain why the common methodology of imputing trade barriers from regression residuals often leads to backwards results.

Do Factor Endowments Matter for North-North Trade?

The dominant paradigm of world trade patterns posits two principal features. Trade between North and South arises due to traditional comparative advantage, largely determined by differences in endowment patterns. Trade within the North, much of it intra-industry trade, is based on economies of scale and product differentiation. The paradigm specifically denies an important role for endowment differences in determining North-North trade. This paper provides the first sound empirical examination of this question. We demonstrate that trade in factor services among countries of the North is systematically related to endowment differences and large in economic magnitude. Intra-industry trade, rather than being a puzzle for a factor endowments theory, is instead the conduit for a great deal of this factor service trade.

A Search for Multiple Equilibria in Urban Industrial Structure

Theories featuring multiple equilibria are now widespread across many fields of economics. Yet little empirical work has asked if such multiple equilibria are salient features of real economies. We examine this in the context of the Allied bombing of Japanese cities and industries in WWII. We develop a new empirical test for multiple equilibria and apply it to data for 114 Japanese cities in eight manufacturing industries. The data provide no support for the existence of multiple equilibria. In the aftermath even of immense shocks, a city typically recovers not only its population and its share of aggregate manufacturing, but even the specific industries it had before.

Non-perturbative effective model for the Higgs sector of the Standard Model

A non-perturbative effective model is derived for the Higgs sector of the standard model, described by a simple scalar theory. The renormalized couplings are determined by the derivatives of the Gaussian Effective Potential that are known to be the sum of infinite bubble graphs contributing to the vertex functions. A good agreement has been found with strong coupling lattice simulations when a comparison can be made