Is Stolper–Samuelson dangerous and FPE a failure?

The Heckscher–Ohlin model has spawned the twin theorems of Stolper–Samuelson and factor-price equalization (FPE), both of which concern the effects of international trade on wages and income distribution. A recent literature, critical of both theorems, claims that they no longer serve as a useful guide for understanding the complex web of trade and wages. This literature also claims that the twin theorems are empirically misleading and irrelevant. The present essay argues that the critics have exaggerated the empirical failure of the twin theorems and, more importantly, they have missed the central message of the theorems; especially, that of Stolper–Samuelson on the optimality of free trade.     

The Convergence Hypothesis: History,Theory, and Evidence

The hypothesis that per capita output converges across economies over time represents one of the oldest controversies in economics. This essay surveys the history and development of the hypothesis, focusing particularly on its vast literature since the mid-1980s. A summary of empirical analyses, econometric issues, and various tests of the convergence hypothesis are also presented. Moreover, the essay analyzes the implications of the hypothesis for economic growth, especially as it relates to underdeveloped economies.     

Coordinating electronic commerce activities in MANIFOLD

Modern electronic commerce environments are heavily web-based and involve issues such as distributed execution, multiuser interactive access or interface with and use of middleware platforms. Thus, their components exhibit the properties of communication, cooperation and coordination as in CSCW, groupware or workflow management systems. In this paper we examine the potential of using coordination technology to model electronic commerce activities and we show the benefits of such an approach. Furthermore, we argue that control-oriented, event-driven coordination models (which enjoy some inherent properties such as security) are more suitable for electronic commerce than data-driven ones which are based on accessing an open shared communication medium in almost unrestricted ways. This revised version was published online in August 2006 with corrections to the Cover Date.     

An Estimation of the Impact of Oil Shocks on Crude Oil Exporting Economies and Their Trade Partners

This research evaluates the impact of oil price shocks on oil producing and consuming economies; we used a simultaneous equation framework for different countries with business relations. As expected, we found that oil-producers (here, Iran and Russia) benefit from oil price shocks. However contrary to previous findings, they also benefit from the indirect effect through their trade partners. For oil-consuming economies, the effects are more diverse. In some countries, output falls in response to an oil price shock, while some others seem to be relatively immune. Generally, those countries which trade more with oil producers gain indirect benefits via higher demand from oil-producers. For instance, the Netherlands, Germany, France, Italy, the US, the UK, and China get a negative direct effect and positive indirect effect from oil producing countries. This is exactly the result that we anticipated. India has both negative effects directly and indirectly and seems to suffer more in a positive oil price shock. For Japan, Spain, Switzerland and Turkey the results are reversed. They benefit from an oil shock directly and indirectly.     

Theorems on correspondences and stability of the core

In this note two theorems strengthening Grodal's (1971) Theorem on correspondences are proved. The first drops the convexity assumption. The second strengthens that theorem further for the case when the range is the positive orthant. In this case, the conclusion of Grodal's Theorem - the intersection of the integral with the interior of the range being open- is modified to read as the integral being a relative open subset of the positive orthant. An example is provided to show that, such a strengthening is not valid in general. This allows us to dispense with the requirment of convexity of preferences in Grodal's (1971) theorems on the closedness of the set of Pareto optimal allocations, the core, and the continuity of the core correspondence for pure exchange economies. We apply this result to show that blocking coalitions in a large economy are stable. Received: September 30, 1998; revised version: September 18, 2001 RID="*" ID="*" The author is grateful to an anonymous referee for helpful comments. The usual disclaimer applies.     

Experiments on two-phase flow in hydraulic jump on pebbled rough bed: Part 1–Turbulence properties and particle chord time and length

This study reported and discussed turbulence characteristics, such as turbulence intensity, correlation time scales, and advective length scales. The characteristic air–water time scale, including the particle chord time and length and their probability density functions (PDFs), was investigated. The results demonstrated that turbulence intensity was relatively greater on a rough bed in the roller length, whereas further downstream, the decay rate was higher. In addition, the relationship between turbulence intensity and dimensionless bubble count rate reflected an increase in turbulence intensity associated with the number of entrained particles. Triple decomposition analysis (TDA) was performed to determine the contributions of slow and fast turbulent components. The TDA results indicated that, regardless of bed type and inflow conditions, the sum of the band-pass (T'_u) and high-pass (T″_u) filtered turbulence intensities was equal to the turbulence intensity of the raw signal data (T_u). T″_u highlighted a higher turbulence intensity and larger vorticities on the rough bed for an identical inflow Froude number. Additional TDA results were presented in terms of the interfacial velocity, auto- and cross-correlation time scales, and longitudinal advection length scale, with the effects of low- and high-frequency signal components on each highlighted parameter. The analysis of the air chord time indicated an increase in the proportion of small bubbles moving downstream. The second part of this research focused on the basic properties of particle grouping and clustering.     

Experiments on two-phase flow in hydraulic jump on pebbled rough bed: Part 2–Bubble clustering

A survey on bubble clustering in air–water flow processes may provide significant insights into turbulent two-phase flow. These processes have been studied in plunging jets, dropshafts, and hydraulic jumps on a smooth bed. As a first attempt, this study examined the bubble clustering process in hydraulic jumps on a pebbled rough bed using experimental data for 1.70 < Fr₁ < 2.84 (with Fr₁ denoting the inflow Froude number). The basic properties of particle grouping and clustering, including the number of clusters, the dimensionless number of clusters per second, the percentage of clustered bubbles, and the number of bubbles per cluster, were analyzed based on two criteria. For both criteria, the maximum cluster count rate was greater on the rough bed than on the smooth bed, suggesting greater interactions between turbulence and bubbly flow on the rough bed. The results were consistent with the longitudinal distribution of the interfacial velocity using one of the criteria. In addition, the clustering process was analyzed using a different approach: the interparticle arrival time of bubbles. The comparison showed that the bubbly flow structure had a greater density of bubbles per unit flux on the rough bed than on the smooth bed. Bed roughness was the dominant parameter close to the jump toe. Further downstream, Fr₁ predominated. Thus, the rate of bubble density decreased more rapidly for the hydraulic jump with the lowest Fr₁.