1/z-renormalization of the mean-field behavior of the dipole-coupled singlet-singlet system HoF_3

The two main characteristics of the holmium ions in HoF_3 are that their local electronic properties are dominated by two singlet states lying well below the remaining 4f-levels, and that the classical dipole-coupling is an order of magnitude larger than any other two-ion interactions between the Ho-moments. This combination makes the system particularly suitable for testing refinements of the mean-field theory. There are four Ho-ions per unit cell and the hyperfine coupled electronic and nuclear moments on the Ho-ions order in a ferrimagnetic structure at T_C=0.53 K. The corrections to the mean-field behavior of holmium triflouride, both in the paramagnetic and ferrimagnetic phase, have been calculated to first order in the high-density 1/z-expansion. The effective medium theory, which includes the effects of the single-site fluctuations, leads to a substantially improved description of the magnetic properties of HoF_3, in comparison with that based on the mean-field approximation.Comment: 26pp, plain-TeX, JJ

Survival of the Best Fit: Exposure to Low-Wage Countries and the (Uneven) Growth of U.S. Manufacturing Plants

This paper examines the role of international trade in the reallocation of U.S. manufacturing activity within and across industries from 1977 to 1997. It introduces a new measure of industry exposure to international trade, motivated by the Heckscher-Ohlin model, which focuses on where imports originate rather than their overall level. Results demonstrate that plant survival as well as output and employment growth are negatively associated with the share of industry imports sourced from the world ¿s lowest-wage countries. Within industries, activity is reallocated towards capital- intensive plants. Plants are also more likely to alter their product mix (i.e. switch industries) in response to trade with low-wage countries. Plants altering their product mix switch to industries that are more capital and skill- intensive.Low-Wage Country Import Competition, Heckscher-Ohlin, Manufacturing Plant

Falling Trade Costs, Heterogeneous Firms, and Industry Dynamics

This paper examines the response of industries and firms to changes in trade costs. Several new firm-level models of international trade with heterogeneous firms predict that industry productivity will rise as trade costs fall due to the reallocation of activity across plants within an industry. Using disaggregated U.S. import data, we create a new measure of trade costs over time and industries. As the models predict, productivity growth is faster in industries with falling trade costs. We also find evidence supporting the major hypotheses of the heterogenous-firm models. Plants in industries with falling trade costs are more likely to die or become exporters. Existing exporters increase their shipments abroad. The results do not apply equally across all sectors but are strongest for industries most likely to be producing horizontally-differentiated tradeable goods.

Falling Trade Costs, Heterogeneous Firms and Industry Dynamics

This paper examines the response of industries and firms to changes in trade costs. Several new firm-level models of international trade with heterogeneous firms predict that industry productivity will rise as trade costs fall due to the reallocation of activity across plants within an industry. Using disaggregated U.S. import data, we create a new measure of trade costs over time and industries. As the models predict, productivity growth is faster in industries with falling trade costs. We also find evidence supporting the major hypotheses of the heterogeneous-firm models. Plants in industries with falling trade costs are more likely to die or become exporters. Existing exporters increase their shipments abroad. The results do not apply equally across all sectors but are strongest for industries most likely to be producing horizontally-differentiated tradeable goods.Plant deaths, survival, exit, exports, employment, tariffs, freight costs, transport costs

Importers, Exporters, and Multinationals: A Portrait of Firms in the U.S. that Trade Goods

This paper provides an integrated view of globally engaged US firms by exploring a newly developed dataset that links US international trade transactions to longitudinal data on US enterprises. These data permit examination of a number of new dimensions of firm activity, including how many products firms trade, how many countries firms trade with, the characteristics of those countries, the concentration of trade across firms, whether firms transact at arm’s length or with related parties, and whether firms import as well as export. Firms that trade goods play an important role in the United States, employing more than a third of the US workforce. We find that the most globally engaged US firms, i.e. those that both export to and import from related parties, dominate US trade flows and employment at trading firms. We also find that firms that begin trading between 1993 and 2000 experience especially rapid employment growth and are a major force in overall job creation.exporters, importers, multinationals, related-party trade

Survival of the Best Fit: Competition from Low Wage Countries and the (Uneven) Growth of US Manufacturing Plants

We examine the relationship between import competition from low wage countries and the reallocation of US manufacturing from 1977 to 1997. Both employment and output growth are slower for plants that face higher levels of low wage import competition in their industry. As a result, US manufacturing is reallocated over time towards industries that are more capital and skill intensive. Differential growth is driven by a combination of increased plant failure rates and slower growth of surviving plants. Within industries, low wage import competition has the strongest effects on the least capital and skill intensive plants. Surviving plants that switch industries move into more capital and skill intensive sectors when they face low wage competition.