Testing the General Validity of the Heckscher-Ohlin Theorem: The Natural Experiment of Japan

We exploit Japan's 19th century opening up to trade to test a general formulation of the Heckscher-Ohlin theorem. This formulation is based on Ohlin's measure of factor scarcity where autarky factor prices impose a refutable prediction on the economy's factor content of trade. Our test combines factor price data in Japan's autarky period with commodity trade data and a technology matrix in Japan's early free trade period. Our technology matrix is derived from a major Japanese survey of agricultural techniques during the early Meiji period, accounts by European visitors and numerous studies by Japanese and western scholars that draw on village records, business accounts and other historical sources. Evaluating Japan's factor content of trade during 1868-1875 at the corresponding autarky factor prices, we fail to reject the Heckscher-Ohlin prediction in each sample year.

Evolution of virulence in opportunistic pathogens: generalism, plasticity, and control

Standard virulence evolution theory assumes that virulence factors are maintained because they aid parasitic exploitation, increasing growth within and/or transmission between hosts. An increasing number of studies now demonstrate that many opportunistic pathogens (OPs) do not conform to these assumptions, with virulence factors maintained instead because of advantages in non-parasitic contexts. Here we review virulence evolution theory in the context of OPs and highlight the importance of incorporating environments outside a focal virulence site. We illustrate that virulence selection is constrained by correlations between these external and focal settings and pinpoint drivers of key environmental correlations, with a focus on generalist strategies and phenotypic plasticity. We end with a summary of key theoretical and empirical challenges to be met for a fuller understanding of OPs

Testing the general validity of the Heckscher-Ohlin Theorem: the natural experiment of Japan

We exploit Japan's 19th century opening up to trade to test a general formulation of the Heckscher-Ohlin theorem. This formulation is based on Ohlin's measure of factor scarcity where autarky factor prices impose a refutable prediction on the economy's factor content of trade. Our test combines factor price data in Japan's autarky period with commodity trade data and a technology matrix in Japan's early free trade period. Our technology matrix is derived from a major Japanese survey of agricultural techniques during the early Meiji period, accounts by European visitors and numerous studies by Japanese and western scholars that draw on village records, business accounts and other historical sources. Evaluating Japan's factor content of trade during 1868-1875 at the corresponding autarky factor prices, we fail to reject the Heckscher-Ohlin prediction in each sample year.

Testing the General Validity of the Heckscher-Ohlin Theorem: The Natural Experiment of Japan

We exploit Japan’s 19th century move from autarky to free trade to provide the first test of the general validity of the price formulation of the Heckscher-Ohlin theorem. In this formulation a country’s autarky factor price vector imposes a single refutable prediction on the economy’s factor content of trade. Our test combines factor price data from Japan’s late autarky period with Japan’s factor content of trade calculated with the technologies of the country of origin of traded goods. The direct and indirect input requirements are constructed from many historical sources, including a major Japanese survey of agricultural techniques and a rich set of 19th century comparative cost studies. Evaluating Japan’s factor content of trade during 1865-1876 at autarky factor prices, we fail to reject the Heckscher-Ohlin hypothesis in each sample year.testing the price version of Heckscher-Ohlin, the natural experiment of Japan

Rural Land-Use Trends in the Conterminous United States, 1950-2000.

In order to understand the magnitude, direction, and geographic distribution of land-use changes, we evaluated land-use trends in U.S. counties during the latter half of the 20th century. Our paper synthesizes the dominant spatial and temporal trends in population, agriculture, and urbanized land uses, using a variety of data sources and an ecoregion classification as a frame of reference. A combination of increasing attractiveness of nonmetropolitan areas in the period 1970–2000, decreasing household size, and decreasing density of settlement has resulted in important trends in the patterns of developed land. By 2000, the area of low-density, exurban development beyond the urban fringe occupied nearly 15 times the area of higher density urbanized development. Efficiency gains, mechanization, and agglomeration of agricultural concerns has resulted in data that show cropland area to be stable throughout the Corn Belt and parts of the West between 1950 and 2000, but decreasing by about 22% east of the Mississippi River. We use a regional case study of the Mid-Atlantic and Southeastern regions to focus in more detail on the land-cover changes resulting from these dynamics. Dominating were land-cover changes associated with the timber practices in the forested plains ecoregions and urbanization in the piedmont ecoregions. Appalachian ecoregions show the slowest rates of landcover change. The dominant trends of tremendous exurban growth, throughout the United States, and conversion and abandonment of agricultural lands, especially in the eastern United States, have important implications because they affect large areas of the country, the functioning of ecological systems, and the potential for restoratio

Synergy and Group Size in Microbial Cooperation

Microbes produce many molecules that are important for their growth and development, and the consumption of these secretions by nonproducers has recently become an important paradigm in microbial social evolution. Though the production of these public goods molecules has been studied intensely, little is known of how the benefits accrued and costs incurred depend on the quantity of public good molecules produced. We focus here on the relationship between the shape of the benefit curve and cellular density with a model assuming three types of benefit functions: diminishing, accelerating, and sigmoidal (accelerating then diminishing). We classify the latter two as being synergistic and argue that sigmoidal curves are common in microbial systems. Synergistic benefit curves interact with group sizes to give very different expected evolutionary dynamics. In particular, we show that whether or not and to what extent microbes evolve to produce public goods depends strongly on group size. We show that synergy can create an “evolutionary trap” which can stymie the establishment and maintenance of cooperation. By allowing density dependent regulation of production (quorum sensing), we show how this trap may be avoided. We discuss the implications of our results for experimental design