We examine how the age structure of a company's workforce affects company performance. Although, the effect of aging on individual productivity has been analyzed frequently, organizational productivity effects, which are more than the sum of individual productivities, have not. Furthermore, we do not only address the effect of changes in average age but also of changes in age diversity on organizational performance. We make a theoretical contribution by introducing a simple economic model to study the effects of workforce heterogeneity on company performance. The model provides a formal structure, i.e. cost and benefit curves, to analyze how changes in age diversity may affect organizational performance. We then break new ground by combining this economic model with theoretical insights and empirical results on aging and diversity from multiple and very diverse disciplines. As a result we derive empirically testable hypotheses which are tested in the empirical section based on a linked employer employee dataset with more than 18.000 German firms and 2 million employees. We find new and innovative results. Although previous research has often found declining individual productivity effects with increasing age, we find that organizational productivity does not necessarily decline with average workforce age, particularly if changes in age diversity and type of tasks are controlled for. We also find that an increase in age diversity can have substantial positive productivity effects, particularly in innovative and creative companies. Our results are not only discussed in terms of statistical significance, but also with respect to economic importance and the consequences of demographic changes on organizational performance.
{"title":"The Impact of Aging and Age Diversity on Company Performance","authors":"U. Backes-Gellner, S. Veen","doi":"10.2139/ssrn.1346895","DOIUrl":"https://doi.org/10.2139/ssrn.1346895","url":null,"abstract":"We examine how the age structure of a company's workforce affects company performance. Although, the effect of aging on individual productivity has been analyzed frequently, organizational productivity effects, which are more than the sum of individual productivities, have not. Furthermore, we do not only address the effect of changes in average age but also of changes in age diversity on organizational performance. We make a theoretical contribution by introducing a simple economic model to study the effects of workforce heterogeneity on company performance. The model provides a formal structure, i.e. cost and benefit curves, to analyze how changes in age diversity may affect organizational performance. We then break new ground by combining this economic model with theoretical insights and empirical results on aging and diversity from multiple and very diverse disciplines. As a result we derive empirically testable hypotheses which are tested in the empirical section based on a linked employer employee dataset with more than 18.000 German firms and 2 million employees. We find new and innovative results. Although previous research has often found declining individual productivity effects with increasing age, we find that organizational productivity does not necessarily decline with average workforce age, particularly if changes in age diversity and type of tasks are controlled for. We also find that an increase in age diversity can have substantial positive productivity effects, particularly in innovative and creative companies. Our results are not only discussed in terms of statistical significance, but also with respect to economic importance and the consequences of demographic changes on organizational performance.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"163 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127520542","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 : 2009-01-02DOI: 10.1111/j.1468-246X.2008.01323.x
Ingrid Esser, Tommy Ferrarini, Kenneth Nelson, O. Sjöberg
The article outlines a conceptual and theoretical framework for improved comparative analysis of publicly provided social protection in developing countries, drawing on the research tradition of the study of longstanding welfare democracies. An important element of the proposed institutional approach is the establishment of comparable qualitative and quantitative indicators for social protection. The empirical example of child benefits indicates that differences between developed and developing countries should not be exaggerated, and that the prevalence of child benefits in sub-Saharan African and Latin American countries today resembles the inter-war period (1919-1938) situation in developed regions.
{"title":"A Framework for Comparing Social Protection in Developing and Developed Countries: The Example of Child Benefits","authors":"Ingrid Esser, Tommy Ferrarini, Kenneth Nelson, O. Sjöberg","doi":"10.1111/j.1468-246X.2008.01323.x","DOIUrl":"https://doi.org/10.1111/j.1468-246X.2008.01323.x","url":null,"abstract":"The article outlines a conceptual and theoretical framework for improved comparative analysis of publicly provided social protection in developing countries, drawing on the research tradition of the study of longstanding welfare democracies. An important element of the proposed institutional approach is the establishment of comparable qualitative and quantitative indicators for social protection. The empirical example of child benefits indicates that differences between developed and developing countries should not be exaggerated, and that the prevalence of child benefits in sub-Saharan African and Latin American countries today resembles the inter-war period (1919-1938) situation in developed regions.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128214536","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 examines the differentiated outcomes of vocational and general secondary academic education, particularly in terms of employment opportunities, labor market earnings, and access to tertiary education in Indonesia. With data from a panel of two waves of the Indonesia Family Life Survey in 1997 and 2000, the paper tracks a cohort of high school students in 1997 to examine their schooling and employment status in 2000. The findings demonstrate that: (1) attendance at vocational secondary schools results in neither market advantage nor disadvantage in terms of employment opportunities and/or earnings premium; (2) attendance at vocational schools leads to significantly lower academic achievement as measured by national test scores; and (3) There is no stigma attached to attendance at vocational schools that results in a disadvantage in access to tertiary education; rather, it is the lower academic achievement associated with attendance at vocational school that lowers the likelihood of entering college. The empirical approach of this paper addresses two limitations of the existing literature in this area. First, it takes into account the observation censoring issue due to college entry when evaluating labor market outcomes of secondary school graduates. Second, using an instrumental variable approach, the paper also treats endogeneity of household choice of vocational versus academic track of secondary education, teasing out the net effect of secondary school choice on labor market and schooling outcomes.
{"title":"Vocational Schooling, Labor Market Outcomes, and College Entry","authors":"Dandan Chen","doi":"10.1596/1813-9450-4814","DOIUrl":"https://doi.org/10.1596/1813-9450-4814","url":null,"abstract":"This paper examines the differentiated outcomes of vocational and general secondary academic education, particularly in terms of employment opportunities, labor market earnings, and access to tertiary education in Indonesia. With data from a panel of two waves of the Indonesia Family Life Survey in 1997 and 2000, the paper tracks a cohort of high school students in 1997 to examine their schooling and employment status in 2000. The findings demonstrate that: (1) attendance at vocational secondary schools results in neither market advantage nor disadvantage in terms of employment opportunities and/or earnings premium; (2) attendance at vocational schools leads to significantly lower academic achievement as measured by national test scores; and (3) There is no stigma attached to attendance at vocational schools that results in a disadvantage in access to tertiary education; rather, it is the lower academic achievement associated with attendance at vocational school that lowers the likelihood of entering college. The empirical approach of this paper addresses two limitations of the existing literature in this area. First, it takes into account the observation censoring issue due to college entry when evaluating labor market outcomes of secondary school graduates. Second, using an instrumental variable approach, the paper also treats endogeneity of household choice of vocational versus academic track of secondary education, teasing out the net effect of secondary school choice on labor market and schooling outcomes.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122409802","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 recent paper by Brunetti (2006) examines whether the US estate tax forces heirs with insufficient liquid assets to sell inherited businesses in order to pay the estate tax. It concludes that the estate tax has a positive effect on such sales. This note highlights features of the estate tax and succession planning by entrepreneurs that have been overlooked which could explain the observed pattern of business sales. These omissions, along with measurement errors, cast doubt on the reported findings.
{"title":"The Estate Tax and the Demise of the Family Business: A Comment","authors":"David Joulfaian","doi":"10.2139/SSRN.1309856","DOIUrl":"https://doi.org/10.2139/SSRN.1309856","url":null,"abstract":"A recent paper by Brunetti (2006) examines whether the US estate tax forces heirs with insufficient liquid assets to sell inherited businesses in order to pay the estate tax. It concludes that the estate tax has a positive effect on such sales. This note highlights features of the estate tax and succession planning by entrepreneurs that have been overlooked which could explain the observed pattern of business sales. These omissions, along with measurement errors, cast doubt on the reported findings.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"15 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123745916","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 investigates intra-urban population and employment shifts over 1980-2000, using the Cincinnati Metropolitan Area as a case study. Population and employment are disaggregated by ethnicity (White, Black, Others) and industry (eleven sectors) to better capture different location behaviors. Inter-industry relationships are considered when constructing variables. Additional diversity and locational and socio-economic variables are also included into a simultaneous equation model. The results reveal strong interactions between ethnic groups, confirm the existence of agglomeration effects, and suggest that diversity has positive effects on both firms and households in both periods. For firms, better access to their potential customers and employees is more important than better access to the input/output sectors. Further, the results reveal changing dynamics, from 1980-1990 to 1990-2000, for different population and activity groups, and suggest that, overall, firm location behaviors are more stable than household behaviors.
{"title":"Accessibility, Diversity, and the Dynamics of Population and Employment Location","authors":"Sumei Zhang, J. Guldmann","doi":"10.2139/ssrn.1321488","DOIUrl":"https://doi.org/10.2139/ssrn.1321488","url":null,"abstract":"This paper investigates intra-urban population and employment shifts over 1980-2000, using the Cincinnati Metropolitan Area as a case study. Population and employment are disaggregated by ethnicity (White, Black, Others) and industry (eleven sectors) to better capture different location behaviors. Inter-industry relationships are considered when constructing variables. Additional diversity and locational and socio-economic variables are also included into a simultaneous equation model. The results reveal strong interactions between ethnic groups, confirm the existence of agglomeration effects, and suggest that diversity has positive effects on both firms and households in both periods. For firms, better access to their potential customers and employees is more important than better access to the input/output sectors. Further, the results reveal changing dynamics, from 1980-1990 to 1990-2000, for different population and activity groups, and suggest that, overall, firm location behaviors are more stable than household behaviors.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127462245","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}
It has traditionally been believed that collecting survey measures of total spending necessarily involved asking a large number of questions, too many for inclusion of a comprehensive spending measure in a general-purpose survey. In this paper the authors report on a supplemental survey to the Health and Retirement Study that took up this challenge. They discuss issues that arise designing a survey module to collect spending data with strict time constraints, describe how the implementation in the Consumption and Activities Mail Survey (CAMS) played out, and elicit anomalies that more detailed analysis of data quality revealed. They report how they addressed some of these anomalies in subsequent waves of CAMS. Other anomalies required conducting additional randomized experiments to find what explains the observed patterns. The results highlight the tension between asking about spending using a long time frame, which exacerbates recall bias, versus using a short time frame, which risks relying on an unrepresentative snapshot of a household's spending to proxy the total for the last 12 months. An important complicating factor in deciding which goods should be put into which time frames is that there is substantial heterogeneity in the frequency of spending across households even for the same category of spending.
{"title":"Methodological Innovations in Collecting Spending Data: The HRS Consumption and Activities Mail Survey","authors":"M. Hurd, S. Rohwedder","doi":"10.2139/ssrn.1317467","DOIUrl":"https://doi.org/10.2139/ssrn.1317467","url":null,"abstract":"It has traditionally been believed that collecting survey measures of total spending necessarily involved asking a large number of questions, too many for inclusion of a comprehensive spending measure in a general-purpose survey. In this paper the authors report on a supplemental survey to the Health and Retirement Study that took up this challenge. They discuss issues that arise designing a survey module to collect spending data with strict time constraints, describe how the implementation in the Consumption and Activities Mail Survey (CAMS) played out, and elicit anomalies that more detailed analysis of data quality revealed. They report how they addressed some of these anomalies in subsequent waves of CAMS. Other anomalies required conducting additional randomized experiments to find what explains the observed patterns. The results highlight the tension between asking about spending using a long time frame, which exacerbates recall bias, versus using a short time frame, which risks relying on an unrepresentative snapshot of a household's spending to proxy the total for the last 12 months. An important complicating factor in deciding which goods should be put into which time frames is that there is substantial heterogeneity in the frequency of spending across households even for the same category of spending.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114861785","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 study analyses the fiscal sustainability of the Finnish public sector using stochastic projections to describe uncertain future demographic trends and asset yields. While current tax rates are unlikely to yield sufficient tax revenue to finance public expenditure with an ageing population, if developments are as expected, the problem will not be very large. However, there is a small, but not negligible, probability that taxes will need to be raised dramatically, perhaps by over 5 percentage points. Such outcomes, if realised, could destabilise the entire welfare state. The study also analyses three policy options aimed at improving sustainability. Longevity adjustment of pension benefits and introduction of an NDC pension system would reduce the expected problem and narrow the sustainability gap distribution. Under the third option, pension funds would invest more in equities and expect to get higher returns. This policy also limits the sustainability problem, but only under precondition that policymakers in the future can live with substantially larger variation in the value of the funds without adjusting tax rules or benefits.
{"title":"Population Ageing and Fiscal Sustainability in Finland: A Stochastic Analysis","authors":"J. Lassila, T. Valkonen","doi":"10.2139/ssrn.1318176","DOIUrl":"https://doi.org/10.2139/ssrn.1318176","url":null,"abstract":"This study analyses the fiscal sustainability of the Finnish public sector using stochastic projections to describe uncertain future demographic trends and asset yields. While current tax rates are unlikely to yield sufficient tax revenue to finance public expenditure with an ageing population, if developments are as expected, the problem will not be very large. However, there is a small, but not negligible, probability that taxes will need to be raised dramatically, perhaps by over 5 percentage points. Such outcomes, if realised, could destabilise the entire welfare state. The study also analyses three policy options aimed at improving sustainability. Longevity adjustment of pension benefits and introduction of an NDC pension system would reduce the expected problem and narrow the sustainability gap distribution. Under the third option, pension funds would invest more in equities and expect to get higher returns. This policy also limits the sustainability problem, but only under precondition that policymakers in the future can live with substantially larger variation in the value of the funds without adjusting tax rules or benefits.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114366328","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}
In this paper we examine the empirical relationship between immigration and crime across Italian provinces during the period 1990-2003. Drawing on police data, we first document that the size of the immigrant population is positively correlated with the incidence of property crimes and with the overall crime rate. We then use instrumental variables based on migration towards other European countries to identify the causal impact of exogenous changes in the immigrant population of Italy. According to these estimates, immigration increases only the incidence of robberies and has no effect on all other types of crime. Since robberies represent a very small fraction of all criminal offences, the effect on the overall crime rate is not significantly different from zero.
{"title":"Immigration and Crime: An Empirical Analysis","authors":"Milo Bianchi, P. Buonanno, P. Pinotti","doi":"10.2139/ssrn.1356568","DOIUrl":"https://doi.org/10.2139/ssrn.1356568","url":null,"abstract":"In this paper we examine the empirical relationship between immigration and crime across Italian provinces during the period 1990-2003. Drawing on police data, we first document that the size of the immigrant population is positively correlated with the incidence of property crimes and with the overall crime rate. We then use instrumental variables based on migration towards other European countries to identify the causal impact of exogenous changes in the immigrant population of Italy. According to these estimates, immigration increases only the incidence of robberies and has no effect on all other types of crime. Since robberies represent a very small fraction of all criminal offences, the effect on the overall crime rate is not significantly different from zero.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130439871","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}
Brazil's inequalities in welfare and poverty across and within regions can be accounted for by differences in household attributes and returns to those attributes. This paper uses Oaxaca-Blinder decompositions at the mean as well as at different quantiles of welfare distributions on regionally representative household survey data (2002-03 Household Budget Survey). The analysis finds that household attributes account for most of the welfare differences between urban and rural areas within regions. However, comparing the lagging Northeast region with the leading Southeast region, differences in returns to attributes account for a large part of the welfare disparities, in particular in metropolitan areas, supporting the presence of agglomeration effects in booming areas.
{"title":"Sources of Welfare Disparities Across and Within Regions of Brazil: Evidence from the 2002-03 Household Budget Survey","authors":"E. Skoufias, R. Katayama","doi":"10.1596/1813-9450-4803","DOIUrl":"https://doi.org/10.1596/1813-9450-4803","url":null,"abstract":"Brazil's inequalities in welfare and poverty across and within regions can be accounted for by differences in household attributes and returns to those attributes. This paper uses Oaxaca-Blinder decompositions at the mean as well as at different quantiles of welfare distributions on regionally representative household survey data (2002-03 Household Budget Survey). The analysis finds that household attributes account for most of the welfare differences between urban and rural areas within regions. However, comparing the lagging Northeast region with the leading Southeast region, differences in returns to attributes account for a large part of the welfare disparities, in particular in metropolitan areas, supporting the presence of agglomeration effects in booming areas.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127692260","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 : 2008-12-01DOI: 10.1111/j.1467-9442.2008.00562.x
Tuomas Pekkarinen
This paper studies the relationship between the timing of tracking of pupils into vocational and academic secondary education and gender differences in educational attainment and income. We argue that in a system that streams students into vocational and academic tracks relatively late (age 15-16), girls are more likely to choose the academic track than boys because of gender differences in the timing of puberty. We exploit the Finnish comprehensive school reform of the 1970's to analyze this hypothesis. This reform postponed the tracking of students from the age of 10-11 to 15-16 and was adopted gradually by municipalities so that we can observe members of the same cohorts in both systems. We find that the postponement of the tracking age increased gender differences in the probability of choosing the academic secondary education and in the probability of continuing into academic tertiary education. The reform had particularily negative effects on boys from non-academic family backgrounds. Finally, the reform decreased the gender wage gap in adult income by four percentage points.
{"title":"Gender Differences in Educational Attainment: Evidence on the Role of Tracking from a Finnish Quasi-Experiment","authors":"Tuomas Pekkarinen","doi":"10.1111/j.1467-9442.2008.00562.x","DOIUrl":"https://doi.org/10.1111/j.1467-9442.2008.00562.x","url":null,"abstract":"This paper studies the relationship between the timing of tracking of pupils into vocational and academic secondary education and gender differences in educational attainment and income. We argue that in a system that streams students into vocational and academic tracks relatively late (age 15-16), girls are more likely to choose the academic track than boys because of gender differences in the timing of puberty. We exploit the Finnish comprehensive school reform of the 1970's to analyze this hypothesis. This reform postponed the tracking of students from the age of 10-11 to 15-16 and was adopted gradually by municipalities so that we can observe members of the same cohorts in both systems. We find that the postponement of the tracking age increased gender differences in the probability of choosing the academic secondary education and in the probability of continuing into academic tertiary education. The reform had particularily negative effects on boys from non-academic family backgrounds. Finally, the reform decreased the gender wage gap in adult income by four percentage points.","PeriodicalId":106212,"journal":{"name":"Labor: Demographics & Economics of the Family","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134118491","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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