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This paper presents a simple partial equilibrium framework for considering the economic implications of administered protection in Tanzania, against the background of the country's parallel exchange market and the establishment of the own-funds and open general license (OGL) facilities for authorizing imports. It also presents estimates of the range of possible adjustment in the real exchange rate and trade flows following from a unification of the highly-fragmented import licensing system, coupled with sufficient liberalization of the OGL facility to eliminate own-funded imports and the incentive to export smuggling.

Mitochondria import nearly all of their approximately 1,000–2,000 constituent proteins from the cytosol across their double-membrane envelope 1 – 5 . Genetic and biochemical studies have shown that the conserved protein translocase, termed the TIM23 complex, mediates import of presequence-containing proteins (preproteins) into the mitochondrial matrix and inner membrane. Among about ten different subunits of the TIM23 complex, the essential multipass membrane protein Tim23, together with the evolutionarily related protein Tim17, has long been postulated to form a protein-conducting channel 6 – 11 . However, the mechanism by which these subunits form a translocation path in the membrane and enable the import process remains unclear due to a lack of structural information. Here we determined the cryo-electron microscopy structure of the core TIM23 complex (heterotrimeric Tim17–Tim23–Tim44) from Saccharomyces cerevisiae . Contrary to the prevailing model, Tim23 and Tim17 themselves do not form a water-filled channel, but instead have separate, lipid-exposed concave cavities that face in opposite directions. Our structural and biochemical analyses show that the cavity of Tim17, but not Tim23, forms the protein translocation path, whereas Tim23 probably has a structural role. The results further suggest that, during translocation of substrate polypeptides, the nonessential subunit Mgr2 seals the lateral opening of the Tim17 cavity to facilitate the translocation process. We propose a new model for the TIM23-mediated protein import and sorting mechanism, a central pathway in mitochondrial biogenesis. The cryo-electron microscopy structure of the mitochondrial TIM23 complex from Saccharomyces cerevisiae shows that Tim17 forms a protein translocation path.

We analyze the effect of rising Chinese import competition between 1990 and 2007 on US local labor markets, exploiting cross-market variation in import exposure stemming from initial differences in industry specialization and instrumenting for US imports using changes in Chinese imports by other high-income countries. Rising imports cause higher unemployment, lower labor force participation, and reduced wages in local labor markets that house importcompeting manufacturing industries. In our main specification, import competition explains one-quarter of the contemporaneous aggregate decline in US manufacturing employment. Transfer benefits payments for unemployment, disability, retirement, and healthcare also rise sharply in more trade-exposed labor markets.

New goods play a central role in many trade and growth models. We use detailed trade and firm-level data from India to investigate the relationship between declines in trade costs, imports of intermediate inputs, and domestic firm product scope. We estimate substantial gains from trade through access to new imported inputs. Moreover, we find that lower input tariffs account on average for 31% of the new products introduced by domestic firms. This effect is driven to a large extent by increased firm access to new input varieties that were unavailable prior to the trade liberalization.

Using novel firm-level microdata and leveraging a natural experiment, this paper provides causal evidence for the role of trade and multinational firms in the cross-country transmission of shocks. The scope for trade linkages to generate cross-country spillovers depends on the elasticity of substitution with respect to domestic inputs. Using the 2011 Tōhoku earthquake as an exogenous shock, we structurally estimate production elasticities at the firm level and find greater complementarities in input usage than previously thought. For Japanese affiliates in the United States, output falls roughly one-for-one with declines in imports, consistent with a relationship between imported and domestic inputs that is close to Leontief.

Since the seminal work of Krugman, product variety has played a central role in models of trade and growth. In spite ofthe general use oflove-of-variety models, there has been no systematic study of how the import of new varieties has contributed to national welfare gains in the United States. In this paper we show that the unmeasured growth in product variety from U. S. imports has been an important source of gains from trade over the last three decades (1972–2001). Using extremely disaggregated data, we show that the number of imported product varieties has increased by a factor of three. We also estimate the elasticities of substitution for each available category at the same level of aggregation, and describe their behavior across time and SITC industries. Using these estimates, we develop an exact aggregate price index and find that the upward bias in the conventional import price index over this time period was 28 percent or 1.2 percentage points per year. We estimate the value to U. S. consumers of the expanded import varieties between 1972 and 2001 to be 2.6 percent of GDP.

This paper adopts five dimensions and 15 indexes of green development, people's life, innovation ability, economic vitality and coordinated development to establish an evaluation system of high-quality economic development. It uses principal component analysis to measure the economic high-quality development of 233 prefecture-level cities from 2003 to 2016, and empirically studies the impact of import sophistication on China's high-quality economic development. The results show that the increase in the sophistication of imported technology can significantly promote the high-quality development of the regional economy, and this effect is applicable to both imported intermediate and final products. In regions with higher and lower levels of economic development, eastern areas, and regions with high-quality development above 90% quantiles, the increase in imported technology content can significantly drive the high-quality development of the local economy. However, it has a great negative impact on the areas with a high-quality development index below 10% quantile. The robustness and endogeneity check support the above viewpoint. Further mechanism analysis shows that the final product import competition and intermediate product import spillover play a mediating role in the process of import sophistication affecting the high-quality economic development. The conclusion of this paper has important theoretical value and practical significance for the use of import trade to achieve high-quality economic development.

How big is the elasticity of substitution between goods from different countries—the Armington elasticity? Estimates of the macroelasticity between home and imported goods are often smaller than the microelasticity between foreign sources of imports. Using new, highly disaggregate U.S. production data matched to imports and simulated data from a Melitz-style model with nested CES preferences, we explore estimation techniques for the two elasticities. For between two-thirds and three-quarters of sample goods, there is no significant difference between the macro- and microelasticities, but for the rest, the microelasticity is significantly higher, even at the same level of disaggregation.