Benoît Mercereau, João Paulo C. C. Sertã, Constance Gavini
Sustainable index funds are becoming mainstream. A natural question is how well these funds promote sustainability. They can do so in two ways: by influencing firms’ cost of capital; and by voting and engaging management. Both work empirically. Moreover, promoting ESG creates financial value for shareholders. How well sustainable index funds use these two promotion levers varies a lot, though. For example, 37% of sustainable index funds have a lower ESG score than their non-ESG benchmark. Only 16% perform more than a simple negative screening and go beyond specific themes while improving ESG scores by at least 5% and avoiding derivatives. The number and sophistication of sustainable index funds should continue to grow. Frameworks for analyzing them are therefore timely. TOPICS: ESG investing, mutual funds/passive investing/indexing, performance measurement
{"title":"Promoting Sustainability Using Passive Funds","authors":"Benoît Mercereau, João Paulo C. C. Sertã, Constance Gavini","doi":"10.3905/jii.2019.1.071","DOIUrl":"https://doi.org/10.3905/jii.2019.1.071","url":null,"abstract":"Sustainable index funds are becoming mainstream. A natural question is how well these funds promote sustainability. They can do so in two ways: by influencing firms’ cost of capital; and by voting and engaging management. Both work empirically. Moreover, promoting ESG creates financial value for shareholders. How well sustainable index funds use these two promotion levers varies a lot, though. For example, 37% of sustainable index funds have a lower ESG score than their non-ESG benchmark. Only 16% perform more than a simple negative screening and go beyond specific themes while improving ESG scores by at least 5% and avoiding derivatives. The number and sophistication of sustainable index funds should continue to grow. Frameworks for analyzing them are therefore timely. TOPICS: ESG investing, mutual funds/passive investing/indexing, performance measurement","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47168682","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 : 2019-05-31DOI: 10.3905/jii.2019.10.1.007
Joanne M. Hill
The success of exchange-traded funds (ETFs) has been disruptive to the asset management business, driven by lower fees and the strong relative performance of index-based investment approaches along with their greater transparency and ease of access. ETFs are unique among investment products, utilized for both short-term and long-term strategies and available at the same cost to all categories of investors. ETF growth has raised several issues for asset managers and financial markets that call for new approaches. These include the rise of systematic, active strategies, the significance of index providers in education and marketing, and the challenges facing asset manager distribution. TOPICS: Exchange-traded funds and applications, passive strategies, mutual fund performance
{"title":"COMMENTARY: Active Indexing with ETFs: Disruption and Implications","authors":"Joanne M. Hill","doi":"10.3905/jii.2019.10.1.007","DOIUrl":"https://doi.org/10.3905/jii.2019.10.1.007","url":null,"abstract":"The success of exchange-traded funds (ETFs) has been disruptive to the asset management business, driven by lower fees and the strong relative performance of index-based investment approaches along with their greater transparency and ease of access. ETFs are unique among investment products, utilized for both short-term and long-term strategies and available at the same cost to all categories of investors. ETF growth has raised several issues for asset managers and financial markets that call for new approaches. These include the rise of systematic, active strategies, the significance of index providers in education and marketing, and the challenges facing asset manager distribution. TOPICS: Exchange-traded funds and applications, passive strategies, mutual fund performance","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3905/jii.2019.10.1.007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49116808","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 question that comes up in the construction of factor portfolios is whether country and sector biases (in the form of active weights) should be neutralized. In this article, we review the assumptions that drive this decision, highlighting that both the portfolio construction framework and the desired portfolio criteria are critical to answering this question. We focus on two empirical examples—a rules-based approach to constructing the portfolio that is reflective of many current indexes in the marketplace and an optimization-based approach that is becoming an increasingly popular path. We corroborate past findings that indicated the answer depends on the portfolio construction framework. Moreover, it depends on the factor in question as well as the criteria—for example, returns, risk, information ratio, and turnover. If the returns and the information ratio are the focus, empirical evidence suggests some form of neutralization across both types of portfolio construction, particularly for value and size. When minimizing risk, maximizing the exposure per unit of tracking error and minimizing the turnover are the primary objectives, so the argument for neutralization is less clear. TOPICS: Portfolio construction, analysis of individual factors/risk premia
{"title":"Country and Sector Bets: Should They Be Neutralized in Global Factor Portfolios?","authors":"J. Bender, Rehan Mohamed, Xiaole Sun","doi":"10.3905/jii.2019.1.069","DOIUrl":"https://doi.org/10.3905/jii.2019.1.069","url":null,"abstract":"A perennial question that comes up in the construction of factor portfolios is whether country and sector biases (in the form of active weights) should be neutralized. In this article, we review the assumptions that drive this decision, highlighting that both the portfolio construction framework and the desired portfolio criteria are critical to answering this question. We focus on two empirical examples—a rules-based approach to constructing the portfolio that is reflective of many current indexes in the marketplace and an optimization-based approach that is becoming an increasingly popular path. We corroborate past findings that indicated the answer depends on the portfolio construction framework. Moreover, it depends on the factor in question as well as the criteria—for example, returns, risk, information ratio, and turnover. If the returns and the information ratio are the focus, empirical evidence suggests some form of neutralization across both types of portfolio construction, particularly for value and size. When minimizing risk, maximizing the exposure per unit of tracking error and minimizing the turnover are the primary objectives, so the argument for neutralization is less clear. TOPICS: Portfolio construction, analysis of individual factors/risk premia","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3905/jii.2019.1.069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41735390","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 : 2019-05-31DOI: 10.3905/jii.2019.10.1.051
Fatollah Salimian, Robert C. Winder, Herman Manakyan, Kashi Khazeh
Investors in exchange-traded products (ETPs) face a number of influencing elements that potentially erode their investments. These factors may include taxes, trading fees, administrative expenses, and rebalancing costs. At the same time, leveraged exchange-traded product (LETP) investors are further burdened with yet another mathematical phenomenon known as beta slippage, which erodes their return on investment. In this article, the authors demonstrate the influence of beta slippage on LETP return on investment. They use the daily S&P 500 Total Return Index (SPXT-TRA) for the period from January 1, 1988 through December 31, 2017, and observe the impact of beta slippage on the rate of return on investment, using ETPs with various leverage ratios. The authors also use the daily mean and standard deviation of SPXT-TRA returns for the same period to simulate daily returns for 300 annual periods to observe the same impact on LETPs. Both the historical returns and the simulated returns demonstrate that beta slippage has a tendency to decay the return on investment compared to the underlying index returns. However, this effect is influenced by the magnitude and variability of returns. The authors find that in time periods with the highest returns, beta slippage impacts investors favorably and amplifies the return on investment. TOPICS: Exchange-traded funds and applications, performance measurement, statistical methods
{"title":"Divergent Influence of Beta Slippage on Leveraged ETPs: A Simulation Approach","authors":"Fatollah Salimian, Robert C. Winder, Herman Manakyan, Kashi Khazeh","doi":"10.3905/jii.2019.10.1.051","DOIUrl":"https://doi.org/10.3905/jii.2019.10.1.051","url":null,"abstract":"Investors in exchange-traded products (ETPs) face a number of influencing elements that potentially erode their investments. These factors may include taxes, trading fees, administrative expenses, and rebalancing costs. At the same time, leveraged exchange-traded product (LETP) investors are further burdened with yet another mathematical phenomenon known as beta slippage, which erodes their return on investment. In this article, the authors demonstrate the influence of beta slippage on LETP return on investment. They use the daily S&P 500 Total Return Index (SPXT-TRA) for the period from January 1, 1988 through December 31, 2017, and observe the impact of beta slippage on the rate of return on investment, using ETPs with various leverage ratios. The authors also use the daily mean and standard deviation of SPXT-TRA returns for the same period to simulate daily returns for 300 annual periods to observe the same impact on LETPs. Both the historical returns and the simulated returns demonstrate that beta slippage has a tendency to decay the return on investment compared to the underlying index returns. However, this effect is influenced by the magnitude and variability of returns. The authors find that in time periods with the highest returns, beta slippage impacts investors favorably and amplifies the return on investment. TOPICS: Exchange-traded funds and applications, performance measurement, statistical methods","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3905/jii.2019.10.1.051","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42960715","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 article uses portfolio optimization techniques to determine optimal country allocation in an emerging market (EM) portfolio and compares the resulting performance to the performance of the MSCI Emerging Markets Index (MSCI EM Index) to test how large the spread is between the two returns. In addition, the article analyzes optimal allocation of the EM portfolio alongside a developed markets index when using the MSCI EM Index as a proxy as well as a mean-variance EM index as a proxy for EM exposure. The results indicate that popular EM index fund performance and exchange-traded fund (ETF) performance do not align with theory from 1993 to 2017, with a spread in Sharpe ratios from 0.37 to 0.10 between the mean-variance optimized EM performance and the MSCI EM Index. In addition, the optimal weightings are very different, 50 percent when using the mean variance relative to 0 percent. The article concludes that an equal-weighted EM portfolio may be the best choice for an investor, with a maximum allocation of 30 percent to EMs based on an equal-weighted EM portfolio. TOPICS: Emerging markets, exchange-traded funds and applications, performance measurement, portfolio construction
{"title":"Emerging Market Funds: They May Not Enhance Asset Allocation","authors":"Todd J. Feldman","doi":"10.3905/jii.2019.1.068","DOIUrl":"https://doi.org/10.3905/jii.2019.1.068","url":null,"abstract":"This article uses portfolio optimization techniques to determine optimal country allocation in an emerging market (EM) portfolio and compares the resulting performance to the performance of the MSCI Emerging Markets Index (MSCI EM Index) to test how large the spread is between the two returns. In addition, the article analyzes optimal allocation of the EM portfolio alongside a developed markets index when using the MSCI EM Index as a proxy as well as a mean-variance EM index as a proxy for EM exposure. The results indicate that popular EM index fund performance and exchange-traded fund (ETF) performance do not align with theory from 1993 to 2017, with a spread in Sharpe ratios from 0.37 to 0.10 between the mean-variance optimized EM performance and the MSCI EM Index. In addition, the optimal weightings are very different, 50 percent when using the mean variance relative to 0 percent. The article concludes that an equal-weighted EM portfolio may be the best choice for an investor, with a maximum allocation of 30 percent to EMs based on an equal-weighted EM portfolio. TOPICS: Emerging markets, exchange-traded funds and applications, performance measurement, portfolio construction","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3905/jii.2019.1.068","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46838199","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 : 2019-05-31DOI: 10.3905/jii.2019.10.1.075
Javier Rodríguez
In this study, the author examines and compares the US market risk exposure and true diversification benefits of emerging markets closed-end funds and exchange-traded funds. The author uses a two-factor econometric model and orthogonal returns to isolate both, US direct market risk and true diversification. Results show that exchange-traded funds that invest in emerging markets are a better vehicle for US-based investors to gain international diversification. In comparison to closed-end funds, exchange-traded funds provide truer international diversification and have less exposure to US market risk. TOPICS: Mutual fund performance, exchange-traded funds and applications
{"title":"Return Orthogonality and True Diversification Benefits of BRIC Securities","authors":"Javier Rodríguez","doi":"10.3905/jii.2019.10.1.075","DOIUrl":"https://doi.org/10.3905/jii.2019.10.1.075","url":null,"abstract":"In this study, the author examines and compares the US market risk exposure and true diversification benefits of emerging markets closed-end funds and exchange-traded funds. The author uses a two-factor econometric model and orthogonal returns to isolate both, US direct market risk and true diversification. Results show that exchange-traded funds that invest in emerging markets are a better vehicle for US-based investors to gain international diversification. In comparison to closed-end funds, exchange-traded funds provide truer international diversification and have less exposure to US market risk. TOPICS: Mutual fund performance, exchange-traded funds and applications","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3905/jii.2019.10.1.075","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46350453","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 : 2019-05-31DOI: 10.3905/jii.2019.10.1.001
Brian R. Bruce
{"title":"Editor’s Letter","authors":"Brian R. Bruce","doi":"10.3905/jii.2019.10.1.001","DOIUrl":"https://doi.org/10.3905/jii.2019.10.1.001","url":null,"abstract":"","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44564941","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}
Corey Hoffstein, Daniel “Justin” Sibears, Nathan D. Faber
Prior research demonstrates that performance can be highly sensitive to index construction choices related to rebalance dates. The authors define the measure of rebalance timing luck as the standard deviation in returns between identically managed investment portfolios that are rebalanced on different dates (sub-indexes). Using a simple fixed-mix strategy, the authors identify that rebalance timing luck can have significant implications for realized results. Statistical tests imply that the ex ante expected returns for the sub-indexes are identical and that realized performance differences are not expected to mean-revert over time. The authors demonstrate that investors can minimize the impact of rebalance timing luck through equal-weight exposure to the sub-indexes. The authors propose an ex ante model to estimate the magnitude of rebalance timing luck and to confirm that the process of equal weighting across N sub-indexes reduces rebalance timing luck by 1/N. TOPICS: Mutual funds/passive investing/indexing, portfolio construction, performance measurement, statistical methods
{"title":"Rebalance Timing Luck: The Difference between Hired and Fired","authors":"Corey Hoffstein, Daniel “Justin” Sibears, Nathan D. Faber","doi":"10.3905/jii.2019.1.070","DOIUrl":"https://doi.org/10.3905/jii.2019.1.070","url":null,"abstract":"Prior research demonstrates that performance can be highly sensitive to index construction choices related to rebalance dates. The authors define the measure of rebalance timing luck as the standard deviation in returns between identically managed investment portfolios that are rebalanced on different dates (sub-indexes). Using a simple fixed-mix strategy, the authors identify that rebalance timing luck can have significant implications for realized results. Statistical tests imply that the ex ante expected returns for the sub-indexes are identical and that realized performance differences are not expected to mean-revert over time. The authors demonstrate that investors can minimize the impact of rebalance timing luck through equal-weight exposure to the sub-indexes. The authors propose an ex ante model to estimate the magnitude of rebalance timing luck and to confirm that the process of equal weighting across N sub-indexes reduces rebalance timing luck by 1/N. TOPICS: Mutual funds/passive investing/indexing, portfolio construction, performance measurement, statistical methods","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3905/jii.2019.1.070","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42619522","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}
The article analyzes factor exposures of European equity exchange-traded funds (ETFs) according to 10-year regressions and a holdings-based analysis. While smart beta ETFs target certain factors explicitly, they and conventional market-capitalization-weighted ETFs (conventional ETFs) both can carry implicit exposures, too. The analysis shows that especially various sector ETFs carry strong regression-based factor exposures, which are only partially mirrored from a holdings-based view. Collectively, the conventional and smart beta ETFs show various significant factor loadings, which are mostly backed by the holdings-based analysis. Translating the flows in smart beta ETFs into a form of factor timing of market participants, the asset-weighted smart beta aggregate outperformed the market on an absolute and risk-adjusted basis. TOPICS: Analysis of individual factors/risk premia, exchange-traded funds and applications, developed markets, performance measurement
{"title":"European ETF Factor Exposures: Evidence from a Regression- and Holdings-Based Analysis","authors":"Philipp A. Dirkx","doi":"10.3905/jii.2019.1.067","DOIUrl":"https://doi.org/10.3905/jii.2019.1.067","url":null,"abstract":"The article analyzes factor exposures of European equity exchange-traded funds (ETFs) according to 10-year regressions and a holdings-based analysis. While smart beta ETFs target certain factors explicitly, they and conventional market-capitalization-weighted ETFs (conventional ETFs) both can carry implicit exposures, too. The analysis shows that especially various sector ETFs carry strong regression-based factor exposures, which are only partially mirrored from a holdings-based view. Collectively, the conventional and smart beta ETFs show various significant factor loadings, which are mostly backed by the holdings-based analysis. Translating the flows in smart beta ETFs into a form of factor timing of market participants, the asset-weighted smart beta aggregate outperformed the market on an absolute and risk-adjusted basis. TOPICS: Analysis of individual factors/risk premia, exchange-traded funds and applications, developed markets, performance measurement","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3905/jii.2019.1.067","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47540326","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 : 2019-03-31DOI: 10.3905/jii.2019.9.4.046
G. Giese, Linda-Eling Lee, D. Melas, Z. Nagy, Laura Nishikawa
There has been a wide range of research in academia and the asset management industry about the financial benefits of ESG investing. However, the question of how to achieve consistency when integrating ESG has not obtained the same level of attention. As a result, ESG integration currently is often applied inconsistently and incompletely across asset owners’ portfolios. The authors of this article focus on how asset owners can implement ESG integration through index-based allocations to portfolios that seek to replicate ESG indexes. Index-based approaches offer consistency, transparency, and replicability and are generally cost-effective. Over a seven-year study period, global and regional versions of the MSCI ESG Leaders Indexes (as proxies for regional allocations) resulted in significant variations in their respective ESG profiles and performance, but in all instances, there was a clear reduction in all key risk measures.
{"title":"Performance and Risk Analysis of Index-Based ESG Portfolios","authors":"G. Giese, Linda-Eling Lee, D. Melas, Z. Nagy, Laura Nishikawa","doi":"10.3905/jii.2019.9.4.046","DOIUrl":"https://doi.org/10.3905/jii.2019.9.4.046","url":null,"abstract":"There has been a wide range of research in academia and the asset management industry about the financial benefits of ESG investing. However, the question of how to achieve consistency when integrating ESG has not obtained the same level of attention. As a result, ESG integration currently is often applied inconsistently and incompletely across asset owners’ portfolios. The authors of this article focus on how asset owners can implement ESG integration through index-based allocations to portfolios that seek to replicate ESG indexes. Index-based approaches offer consistency, transparency, and replicability and are generally cost-effective. Over a seven-year study period, global and regional versions of the MSCI ESG Leaders Indexes (as proxies for regional allocations) resulted in significant variations in their respective ESG profiles and performance, but in all instances, there was a clear reduction in all key risk measures.","PeriodicalId":36431,"journal":{"name":"Journal of Index Investing","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3905/jii.2019.9.4.046","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45033285","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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