Pub Date : 2009-10-14DOI: 10.1111/j.1467-9361.2009.00523.x
E. Funkhouser
I use longitudinal data to examine the relationship between individual and household outcomes prior to emigration and choice of migration destination. In addition, I have separately pooled data on Nicaraguans in the destination countries. These two types of data together provide a rich description of the determinants of choice of destination for Nicaraguan emigrants. For emigration to both the United States and Costa Rica, patterns of emigration are consistent with individual wage gains. The main finding, though, is that emigrants to Costa Rica have characteristics similar to non-emigrants and that emigration to Costa Rica is based relatively more on the current economic condition of the sender household. In contrast, emigration to the United States is based on the accumulated pre-emigration labor market success of emigrants' households in Nicaragua. These findings suggest that household pre-migration factors may be more important than individual factors as determinants of the location decision.
{"title":"The Choice of Migration Destination: A Longitudinal Approach Using Pre-Migration Outcomes","authors":"E. Funkhouser","doi":"10.1111/j.1467-9361.2009.00523.x","DOIUrl":"https://doi.org/10.1111/j.1467-9361.2009.00523.x","url":null,"abstract":"I use longitudinal data to examine the relationship between individual and household outcomes prior to emigration and choice of migration destination. In addition, I have separately pooled data on Nicaraguans in the destination countries. These two types of data together provide a rich description of the determinants of choice of destination for Nicaraguan emigrants. For emigration to both the United States and Costa Rica, patterns of emigration are consistent with individual wage gains. The main finding, though, is that emigrants to Costa Rica have characteristics similar to non-emigrants and that emigration to Costa Rica is based relatively more on the current economic condition of the sender household. In contrast, emigration to the United States is based on the accumulated pre-emigration labor market success of emigrants' households in Nicaragua. These findings suggest that household pre-migration factors may be more important than individual factors as determinants of the location decision.","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91060826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
William Easterly, Ariell Reshef, Julia M. Schwenkenberg
The authors systematically document remarkably high degrees of concentration in manufacturing exports for a sample of 151 countries over a range of 3,000 products. For every country manufacturing exports are dominated by a few"big hits"which account for most of the export value and where the"hit"includes both finding the right product and finding the right market. Higher export volumes are associated with higher degrees of concentration, after controlling for the number of destinations a country penetrates. This further highlights the importance of big hits. The distribution of exports closely follows a power law, especially in the upper tail. These findings do not support a"picking winners"policy for export development; the power law characterization implies that the chance of picking a winner diminishes exponentially with the degree of success. Moreover, given the size of the economy, developing countries are more exposed to demand shocks than rich ones, which further lowers the benefits from trying to pick winners.
{"title":"The Power of Exports","authors":"William Easterly, Ariell Reshef, Julia M. Schwenkenberg","doi":"10.1596/1813-9450-5081","DOIUrl":"https://doi.org/10.1596/1813-9450-5081","url":null,"abstract":"The authors systematically document remarkably high degrees of concentration in manufacturing exports for a sample of 151 countries over a range of 3,000 products. For every country manufacturing exports are dominated by a few\"big hits\"which account for most of the export value and where the\"hit\"includes both finding the right product and finding the right market. Higher export volumes are associated with higher degrees of concentration, after controlling for the number of destinations a country penetrates. This further highlights the importance of big hits. The distribution of exports closely follows a power law, especially in the upper tail. These findings do not support a\"picking winners\"policy for export development; the power law characterization implies that the chance of picking a winner diminishes exponentially with the degree of success. Moreover, given the size of the economy, developing countries are more exposed to demand shocks than rich ones, which further lowers the benefits from trying to pick winners.","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"250 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77911516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A perennial case for industrial policy is based on the protection of young or emerging industries. Despite a natural association with concepts of life cycles, industrial policy has not been analyzed in the context of an industry life-cycle model. In particular, an important life-cycle characteristic, the potential for very large changes in the rate of net entry, is ignored. In this paper, we demonstrate how the impact of industrial policy depends critically on the entry and exit dynamics within an industry. We construct a model of technology adoption in which the number of firms is endogenous, and derive a set of novel predictions about the effects of protection on firm technology decisions. Specifically, we show that permanent protection can induce earlier adoption, but also decreases the probability that a given firm adopts the new technology. Likewise, we demonstrate that reducing the duration of protection results in faster adoption than permanent protection, but also reduces a given firm's probability of adoption. Finally, we show that, for industries characterized by flexibility in firm numbers, protection does not change the rate of technology adoption but does increase the size and probability of a shakeout (large scale net exit).
{"title":"Infant Industry Protection and Industrial Dynamics","authors":"Josh Ederington, Phillip McCalman","doi":"10.2139/ssrn.1503419","DOIUrl":"https://doi.org/10.2139/ssrn.1503419","url":null,"abstract":"A perennial case for industrial policy is based on the protection of young or emerging industries. Despite a natural association with concepts of life cycles, industrial policy has not been analyzed in the context of an industry life-cycle model. In particular, an important life-cycle characteristic, the potential for very large changes in the rate of net entry, is ignored. In this paper, we demonstrate how the impact of industrial policy depends critically on the entry and exit dynamics within an industry. We construct a model of technology adoption in which the number of firms is endogenous, and derive a set of novel predictions about the effects of protection on firm technology decisions. Specifically, we show that permanent protection can induce earlier adoption, but also decreases the probability that a given firm adopts the new technology. Likewise, we demonstrate that reducing the duration of protection results in faster adoption than permanent protection, but also reduces a given firm's probability of adoption. Finally, we show that, for industries characterized by flexibility in firm numbers, protection does not change the rate of technology adoption but does increase the size and probability of a shakeout (large scale net exit).","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78681366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a general equilibrium model of monopolistic competition featuring pro-competitive effects and a competitive limit, and investigate the impact of trade on welfare and efficiency. Contrary to the constant elasticity case, in which all gains from trade are due to product diversity, our model allows for a welfare decomposition between gains from product diversity and gains from pro-competitive effects. We show that the market outcome is not efficient because too many firms operate at an inefficiently small scale by charging too high markups. We further illustrate that trade raises efficiency by narrowing the gap between the equilibrium utility and the optimal utility. As the population gets arbitrarily large in the integrated economy, the equilibrium utility converges to the optimal utility because of the competitive limit. We finally extend the variable elasticity model to a multi-sector setting, and show that intersectoral distortions are eliminated in the limit. The multi-sector model allows us to illustrate some new aspects arising from intersectoral and intrasectoral allocations, namely that trade leads to structural convergence, rather than sectoral specialization, and that trade induces domestic exit in the nontraded sector.
{"title":"Trade, Competition, and Efficiency","authors":"K. Behrens, Yasusada Murata","doi":"10.2139/ssrn.1477016","DOIUrl":"https://doi.org/10.2139/ssrn.1477016","url":null,"abstract":"We present a general equilibrium model of monopolistic competition featuring pro-competitive effects and a competitive limit, and investigate the impact of trade on welfare and efficiency. Contrary to the constant elasticity case, in which all gains from trade are due to product diversity, our model allows for a welfare decomposition between gains from product diversity and gains from pro-competitive effects. We show that the market outcome is not efficient because too many firms operate at an inefficiently small scale by charging too high markups. We further illustrate that trade raises efficiency by narrowing the gap between the equilibrium utility and the optimal utility. As the population gets arbitrarily large in the integrated economy, the equilibrium utility converges to the optimal utility because of the competitive limit. We finally extend the variable elasticity model to a multi-sector setting, and show that intersectoral distortions are eliminated in the limit. The multi-sector model allows us to illustrate some new aspects arising from intersectoral and intrasectoral allocations, namely that trade leads to structural convergence, rather than sectoral specialization, and that trade induces domestic exit in the nontraded sector.","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73156822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
International standards have the potential to both promote and hinder international trade. Yet empirical scholarship on the standards-trade relationship has been held up due to some methodological challenges: measurement problems, varied effects, and endogeneity concerns. We are able to surmount these challenges while considering the impact of one particular standard on the country-pair trade flows between 91 nations over the 1995-2005 period. To deal with these challenges, we measure the degree of standardization via the penetration of ISO 9000 in individual nations, allow ISO diffusion to manifest via multiple (quality-signaling, information/compliance-cost, and common-language) effects, and use instrumental variable and panel data techniques to overcome endogeneity concerns. We find strong evidence in support of ISO 9000 involving a common-language effect that enhances country-pair trade; yet, the evidence is more mixed with regard to the quality-signaling and information/compliance-cost effects. While we find ISO-rich nations (most notably European) to clearly benefit from the worldwide diffusion of standardization, ISO 9000 represents a de facto trade barrier for nations (e.g., the US and Mexico) lagging behind in terms of adoption.
{"title":"ISO 9000: New Form of Protectionism or Common Language in International Trade?","authors":"Joseph A. Clougherty, M. Grajek","doi":"10.2139/ssrn.1476290","DOIUrl":"https://doi.org/10.2139/ssrn.1476290","url":null,"abstract":"International standards have the potential to both promote and hinder international trade. Yet empirical scholarship on the standards-trade relationship has been held up due to some methodological challenges: measurement problems, varied effects, and endogeneity concerns. We are able to surmount these challenges while considering the impact of one particular standard on the country-pair trade flows between 91 nations over the 1995-2005 period. To deal with these challenges, we measure the degree of standardization via the penetration of ISO 9000 in individual nations, allow ISO diffusion to manifest via multiple (quality-signaling, information/compliance-cost, and common-language) effects, and use instrumental variable and panel data techniques to overcome endogeneity concerns. We find strong evidence in support of ISO 9000 involving a common-language effect that enhances country-pair trade; yet, the evidence is more mixed with regard to the quality-signaling and information/compliance-cost effects. While we find ISO-rich nations (most notably European) to clearly benefit from the worldwide diffusion of standardization, ISO 9000 represents a de facto trade barrier for nations (e.g., the US and Mexico) lagging behind in terms of adoption.","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83674626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper focuses on the analysis of the relationship between maritime trade and transport cost in Latin America. The data available are disaggregated (SITC 5 digit level) maritime trade flows on trade routes within Latin America over the period 1999-2004. The contribution to the literature is to disentangle the effects that transport costs have on the extensive margin (number of products imported) and the intensive margin (quantity imported of each product) of international trade in order to test some of the predictions of the trade theories that introduce firm heterogeneity in productivity, as well as fixed costs of exporting. Recent investigations show that spatial frictions (distance) reduce trade mainly by reducing the number of shipments and that most firms ship only to geographically proximate customers, instead of shipping to many destinations in quantities that decrease in distance. Our findings confirm this result for intra-LA trade and show that the opposite pattern is observed for ad-valorem freight rates that reduce aggregate trade values mainly by reducing the quantity imported (intensive margin).
{"title":"Freight Rates and the Margins of Intra-Latin American Maritime Trade","authors":"I. Martínez‐Zarzoso, G. Wilmsmeier","doi":"10.2139/ssrn.1471374","DOIUrl":"https://doi.org/10.2139/ssrn.1471374","url":null,"abstract":"This paper focuses on the analysis of the relationship between maritime trade and transport cost in Latin America. The data available are disaggregated (SITC 5 digit level) maritime trade flows on trade routes within Latin America over the period 1999-2004. The contribution to the literature is to disentangle the effects that transport costs have on the extensive margin (number of products imported) and the intensive margin (quantity imported of each product) of international trade in order to test some of the predictions of the trade theories that introduce firm heterogeneity in productivity, as well as fixed costs of exporting. Recent investigations show that spatial frictions (distance) reduce trade mainly by reducing the number of shipments and that most firms ship only to geographically proximate customers, instead of shipping to many destinations in quantities that decrease in distance. Our findings confirm this result for intra-LA trade and show that the opposite pattern is observed for ad-valorem freight rates that reduce aggregate trade values mainly by reducing the quantity imported (intensive margin).","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84089054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using an N-heterogeneous-country Cournot intra-industry model with three dimensions of heterogeneity considered: i.e., marginal cost of production, market size, and industry concentration, the current paper shows that even under open regionalism regime, in contrast with Yi (1996), global free trade may not be attained via the expansion of customs union. The paper also characterizes the endogenous custom union formation path. When countries are farsightedly rational, customs union can serve as a stepping stone for multilateral liberalization.
{"title":"Asymmetric Country Customs Union Formation","authors":"Xin Zhao, Baomin Dong","doi":"10.2139/ssrn.1467840","DOIUrl":"https://doi.org/10.2139/ssrn.1467840","url":null,"abstract":"Using an N-heterogeneous-country Cournot intra-industry model with three dimensions of heterogeneity considered: i.e., marginal cost of production, market size, and industry concentration, the current paper shows that even under open regionalism regime, in contrast with Yi (1996), global free trade may not be attained via the expansion of customs union. The paper also characterizes the endogenous custom union formation path. When countries are farsightedly rational, customs union can serve as a stepping stone for multilateral liberalization.","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83782122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Edward J. Balistreri, Russell Hillberry, T. Rutherford
Many contemporary theoretic studies of trade over geography reduce to an examination of constant-elasticity reactions to changes in iceberg trade costs. These impacts are readily analyzed in simple constant-returns models based on the Armington (1969) assumption of regionally differentiated goods. Following the line of reasoning suggested by Arkolakis et al. (2008) one can reach the surprising conclusion that industrial organization does not matter. In the present paper, we show that this finding is fragile, and with a minor elaboration of their model, the rich industrial-organization features of the popular Melitz (2003) model do, in fact, generate important differences for trade and welfare.
许多关于地理贸易的当代理论研究都归结为对冰山贸易成本变化的恒弹性反应的考察。这些影响很容易在基于阿明顿(1969)区域差异化商品假设的简单不变回报模型中进行分析。按照Arkolakis et al.(2008)提出的推理思路，我们可以得出令人惊讶的结论:产业组织并不重要。在本文中，我们表明这一发现是脆弱的，并且通过对其模型的少量阐述，流行的Melitz(2003)模型中丰富的产业组织特征实际上确实对贸易和福利产生了重要的差异。
{"title":"Trade and Welfare: Does Industrial Organization Matter","authors":"Edward J. Balistreri, Russell Hillberry, T. Rutherford","doi":"10.2139/ssrn.1479612","DOIUrl":"https://doi.org/10.2139/ssrn.1479612","url":null,"abstract":"Many contemporary theoretic studies of trade over geography reduce to an examination of constant-elasticity reactions to changes in iceberg trade costs. These impacts are readily analyzed in simple constant-returns models based on the Armington (1969) assumption of regionally differentiated goods. Following the line of reasoning suggested by Arkolakis et al. (2008) one can reach the surprising conclusion that industrial organization does not matter. In the present paper, we show that this finding is fragile, and with a minor elaboration of their model, the rich industrial-organization features of the popular Melitz (2003) model do, in fact, generate important differences for trade and welfare.","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80364834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper establishes six stylized facts about firms' export prices using detailed customs data on the universe of Chinese trade flows. First, across firms selling a given product, exporters that charge higher prices earn greater revenues in each destination, have bigger worldwide sales, and enter more markets. Second, firms that export more, that enter more markets and that charge higher export prices import more expensive inputs. Third, across destinations within a firm-product, firms set higher prices in richer, larger, bilaterally more distant and overall less remote countries. Fourth, across destinations within a firm-product, firms earn bigger revenues in markets where they set higher prices. Fifth, across firms within a product, exporters with more destinations offer a wider range of export prices. Finally, firms that export more, that enter more markets and that offer a wider range of export prices pay a wider range of input prices and source inputs from more origin countries. We propose that trade models should incorporate two features to rationalize these patterns in the data: more successful exporters use higher-quality inputs to produce higher-quality goods (stylized facts 1 and 2), and firms vary the quality of their products across destinations by using inputs of different quality levels (stylized facts 3, 4, 5 and 6).
{"title":"Export Prices across Firms and Destinations","authors":"Kalina B. Manova, Zhiwei Zhang","doi":"10.1093/QJE/QJR051","DOIUrl":"https://doi.org/10.1093/QJE/QJR051","url":null,"abstract":"This paper establishes six stylized facts about firms' export prices using detailed customs data on the universe of Chinese trade flows. First, across firms selling a given product, exporters that charge higher prices earn greater revenues in each destination, have bigger worldwide sales, and enter more markets. Second, firms that export more, that enter more markets and that charge higher export prices import more expensive inputs. Third, across destinations within a firm-product, firms set higher prices in richer, larger, bilaterally more distant and overall less remote countries. Fourth, across destinations within a firm-product, firms earn bigger revenues in markets where they set higher prices. Fifth, across firms within a product, exporters with more destinations offer a wider range of export prices. Finally, firms that export more, that enter more markets and that offer a wider range of export prices pay a wider range of input prices and source inputs from more origin countries. We propose that trade models should incorporate two features to rationalize these patterns in the data: more successful exporters use higher-quality inputs to produce higher-quality goods (stylized facts 1 and 2), and firms vary the quality of their products across destinations by using inputs of different quality levels (stylized facts 3, 4, 5 and 6).","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79760203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-09-01DOI: 10.7835/JCC-BERJ-2009-0030
J. Torres-Zorrilla
This article illustrates an application of the input-output model to estimate the multiplier effects of investments and exports of the Peruvian economy. One conclusion is that multipliers of services are greater than multipliers of industries while primary products exhibit intermediate multipliers. Another conclusion is that exports reflect a much higher multiplier effect than do investments. Employment and wage multipliers appear greater for service sectors than for modern exporting sectors, such as mining and metallurgy, and for modern urban sectors, such as electricity, insurance, construction, and beverages.
{"title":"Multipliers of the Peruvian Economy 2002","authors":"J. Torres-Zorrilla","doi":"10.7835/JCC-BERJ-2009-0030","DOIUrl":"https://doi.org/10.7835/JCC-BERJ-2009-0030","url":null,"abstract":"This article illustrates an application of the input-output model to estimate the multiplier effects of investments and exports of the Peruvian economy. One conclusion is that multipliers of services are greater than multipliers of industries while primary products exhibit intermediate multipliers. Another conclusion is that exports reflect a much higher multiplier effect than do investments. Employment and wage multipliers appear greater for service sectors than for modern exporting sectors, such as mining and metallurgy, and for modern urban sectors, such as electricity, insurance, construction, and beverages.","PeriodicalId":14396,"journal":{"name":"International Trade","volume":"352 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2009-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74848374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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