Maximilian A. Müller, Edward J. Riedl, T. Sellhorn
This paper examines pricing differences across recognized and disclosed fair values. We build on prior literature by examining two theoretical causes of such differences: lower reliability of the disclosed information, and/or investors’ higher related information processing costs. We examine European real estate firms reporting under International Financial Reporting Standards (IFRS), which require that fair values for investment properties, our sample firms’ key operating asset, either be recognized on the balance sheet or disclosed in the footnotes. Consistent with prior research, we predict and find a lower association between equity prices and disclosed relative to recognized investment property fair values, reflecting a discount assigned to disclosed fair values. We then predict and find that this discount is mitigated by lower information processing costs (proxied via high analyst following), and some support that it is also mitigated by higher reliability (proxied via use of external appraisals). These latter results are documented using subsample analyses to test one attribute (either information processing costs or reliability) while holding the other constant. Overall, these findings are consistent with fair value reliability and information processing costs providing complementary explanations for observed pricing discounts assessed on disclosed accounting amounts.
{"title":"Recognition versus Disclosure of Fair Values","authors":"Maximilian A. Müller, Edward J. Riedl, T. Sellhorn","doi":"10.2139/ssrn.2362362","DOIUrl":"https://doi.org/10.2139/ssrn.2362362","url":null,"abstract":"This paper examines pricing differences across recognized and disclosed fair values. We build on prior literature by examining two theoretical causes of such differences: lower reliability of the disclosed information, and/or investors’ higher related information processing costs. We examine European real estate firms reporting under International Financial Reporting Standards (IFRS), which require that fair values for investment properties, our sample firms’ key operating asset, either be recognized on the balance sheet or disclosed in the footnotes. Consistent with prior research, we predict and find a lower association between equity prices and disclosed relative to recognized investment property fair values, reflecting a discount assigned to disclosed fair values. We then predict and find that this discount is mitigated by lower information processing costs (proxied via high analyst following), and some support that it is also mitigated by higher reliability (proxied via use of external appraisals). These latter results are documented using subsample analyses to test one attribute (either information processing costs or reliability) while holding the other constant. Overall, these findings are consistent with fair value reliability and information processing costs providing complementary explanations for observed pricing discounts assessed on disclosed accounting amounts.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121826640","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 investigates how alliance portfolio composition affects young firms’ outcomes. Drawing on signaling theory, we propose how alliance portfolio composition — number, functional domains (R&D, manufacturing, and marketing), and single-purpose or multi-purpose nature of alliances within the portfolio — may affect a firm’s likelihood of achieving a liquidity event (IPO or acquisition). We study 8,600 U.S.-based, VC-backed firms during the period of 1990 to 2002 from 10 industry sectors. We find that alliance portfolios (to a certain extent) increase a firm’s liquidity event likelihood. Further, firms with heterogeneous alliance portfolios, including portfolios emitting greater efficiency signals versus endorsement signals, are more likely to experience an IPO versus acquisition. Our findings lend support to the value of multi-function alliances within portfolios.
{"title":"Unpacking Functional Alliance Portfolios: How Signals of Venture Viability Affect New-Venture Outcomes","authors":"Manuela N. Hoehn-Weiss, S. Karim","doi":"10.2139/ssrn.2008234","DOIUrl":"https://doi.org/10.2139/ssrn.2008234","url":null,"abstract":"This article investigates how alliance portfolio composition affects young firms’ outcomes. Drawing on signaling theory, we propose how alliance portfolio composition — number, functional domains (R&D, manufacturing, and marketing), and single-purpose or multi-purpose nature of alliances within the portfolio — may affect a firm’s likelihood of achieving a liquidity event (IPO or acquisition). We study 8,600 U.S.-based, VC-backed firms during the period of 1990 to 2002 from 10 industry sectors. We find that alliance portfolios (to a certain extent) increase a firm’s liquidity event likelihood. Further, firms with heterogeneous alliance portfolios, including portfolios emitting greater efficiency signals versus endorsement signals, are more likely to experience an IPO versus acquisition. Our findings lend support to the value of multi-function alliances within portfolios.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129381368","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 provides an encyclopedic survey of the platform strategy literature and is organized around launch strategies, governance, and competition. A platform strategy is the mobilization of a networked business platform to expand into and operate in a given market. A business platform, in turn, is a nexus of rules and infrastructure that facilitate interactions among network users. A platform may also be viewed as a published standard, together with a governance model, that facilitates third party participation. Platforms provide building blocks that serve as the foundation for complementary products and services. They also match buyers with suppliers, who transact directly with each other using system resources and are generally subject to network effects. Examples include operating systems, game consoles, payment systems, ride sharing platforms, smart grids, healthcare networks, and social networks.
{"title":"Platform Strategy","authors":"Geoffrey G. Parker, Marshall W. Van Alstyne","doi":"10.2139/ssrn.2439323","DOIUrl":"https://doi.org/10.2139/ssrn.2439323","url":null,"abstract":"This article provides an encyclopedic survey of the platform strategy literature and is organized around launch strategies, governance, and competition. A platform strategy is the mobilization of a networked business platform to expand into and operate in a given market. A business platform, in turn, is a nexus of rules and infrastructure that facilitate interactions among network users. A platform may also be viewed as a published standard, together with a governance model, that facilitates third party participation. Platforms provide building blocks that serve as the foundation for complementary products and services. They also match buyers with suppliers, who transact directly with each other using system resources and are generally subject to network effects. Examples include operating systems, game consoles, payment systems, ride sharing platforms, smart grids, healthcare networks, and social networks.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124086489","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}
Seasonal demand for products is common at many companies including Kraft Foods, Case New Holland, and Elmer’s Products. Planning inventory and production in the face of seasonal demand can be challenging. Many companies experience a severe drop in inventory and service as they transition from a high season to a low season. Kraft has termed this phenomenon the 'landslide effect.' In this paper, we present real examples of the landslide effect and describe its causes by comparing common industry practice to the correct inventory mathematics for non stationary demand. We investigate the magnitude and drivers of the landslide effect through both an analytical model and a case study. We find that the effect increases with seasonality, lead time, and demand uncertainty and can lower service by an average of ten points at a representative company. Companies can avoid the landslide effect by using demand forecasts over the preceding lead time to calculate safety stock targets.
{"title":"Misalignment in the Timing of Seasonal Demand and Supply: The Landslide Effect","authors":"John J. Neale, S. Willems, James C. Beyl","doi":"10.2139/ssrn.2029509","DOIUrl":"https://doi.org/10.2139/ssrn.2029509","url":null,"abstract":"Seasonal demand for products is common at many companies including Kraft Foods, Case New Holland, and Elmer’s Products. Planning inventory and production in the face of seasonal demand can be challenging. Many companies experience a severe drop in inventory and service as they transition from a high season to a low season. Kraft has termed this phenomenon the 'landslide effect.' In this paper, we present real examples of the landslide effect and describe its causes by comparing common industry practice to the correct inventory mathematics for non stationary demand. We investigate the magnitude and drivers of the landslide effect through both an analytical model and a case study. We find that the effect increases with seasonality, lead time, and demand uncertainty and can lower service by an average of ten points at a representative company. Companies can avoid the landslide effect by using demand forecasts over the preceding lead time to calculate safety stock targets.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"05 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129868611","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 capital market is a market for securities (debt or equity), where business enterprises and governments can raise long-term funds. It is defined as a market in which money is provided for periods longer than a year. The capital market includes the stock market (equity securities) and the bond market (debt). Capital markets may be classified as primary markets and secondary markets. In primary markets, new stock or bond issues are sold to investors via a mechanism known as underwriting. In the secondary markets, existing securities are sold and bought among investors or traders, usually on a securities exchange, over-the-counter, or elsewhere. Capital Markets of today are driven by many factors like the economic growth, interest rates, forex, foreign investments and many more, but one of the most important factor that would drive tomorrow’s Capital Market is the environment. Capital markets that include companies attuned to environmental issues in future would create permanent and powerful incentives for them to improve their environmental performance, while also ensuring better returns for investors. In future: •Capital Market would ensure that the financial implications of environmental opportunities and risk are properly understood by financial institutions, investors and issuers and are appropriately reflected in the world’s capital markets, •The capital markets will play a transforming role in addressing climate change, enabling the transition from a fossil-fuel based economy to a post-carbon economy, •For investors, it would represent a unique opportunity to participate in a fundamental market transformation of today to tomorrow.
{"title":"Capital Markets for Tomorrow","authors":"N. S. Patil","doi":"10.2139/SSRN.1532707","DOIUrl":"https://doi.org/10.2139/SSRN.1532707","url":null,"abstract":"A capital market is a market for securities (debt or equity), where business enterprises and governments can raise long-term funds. It is defined as a market in which money is provided for periods longer than a year. The capital market includes the stock market (equity securities) and the bond market (debt). Capital markets may be classified as primary markets and secondary markets. In primary markets, new stock or bond issues are sold to investors via a mechanism known as underwriting. In the secondary markets, existing securities are sold and bought among investors or traders, usually on a securities exchange, over-the-counter, or elsewhere. Capital Markets of today are driven by many factors like the economic growth, interest rates, forex, foreign investments and many more, but one of the most important factor that would drive tomorrow’s Capital Market is the environment. Capital markets that include companies attuned to environmental issues in future would create permanent and powerful incentives for them to improve their environmental performance, while also ensuring better returns for investors. In future: •Capital Market would ensure that the financial implications of environmental opportunities and risk are properly understood by financial institutions, investors and issuers and are appropriately reflected in the world’s capital markets, •The capital markets will play a transforming role in addressing climate change, enabling the transition from a fossil-fuel based economy to a post-carbon economy, •For investors, it would represent a unique opportunity to participate in a fundamental market transformation of today to tomorrow.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"181 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124546717","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}
How much should a family save for retirement and for the kids’ college education? How much insurance should they buy? How should they allocate their portfolio across different assets? What should a company choose as the default asset allocation for a mandatory retirement saving plan? We believe that the life-cycle model developed by economists over the last fifty years provides guidance for making such decisions. The theory teaches us to view financial assets as vehicles for transferring resources across different times and outcomes over the life cycle, and that perspective allows households and planners to think about their decisions in a logical and rigorous way. This paper lays out and illustrates the basic analytical framework from the theory in nonmathematical terms, with the aim of providing guidance to financial service providers, consumers, and policymakers.
{"title":"The Theory of Life-Cycle Saving and Investing","authors":"Z. Bodie, Jonathan Treussard, P. Willen","doi":"10.2139/ssrn.1002388","DOIUrl":"https://doi.org/10.2139/ssrn.1002388","url":null,"abstract":"How much should a family save for retirement and for the kids’ college education? How much insurance should they buy? How should they allocate their portfolio across different assets? What should a company choose as the default asset allocation for a mandatory retirement saving plan? We believe that the life-cycle model developed by economists over the last fifty years provides guidance for making such decisions. The theory teaches us to view financial assets as vehicles for transferring resources across different times and outcomes over the life cycle, and that perspective allows households and planners to think about their decisions in a logical and rigorous way. This paper lays out and illustrates the basic analytical framework from the theory in nonmathematical terms, with the aim of providing guidance to financial service providers, consumers, and policymakers.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124536510","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}
Despite the availability of source code, deploying open source software (OSS) in an enterprise environment requires expertise. Recent surveys and case studies show that the skills of IT staff in an organization are one of the key factors in OSS adoption decisions. Another important factor organizations consider when choosing a platform is network effects. This paper studies how users' skills and network effects may influence the market where proprietary software (PS) competes with OSS. In the model, users make adoption decisions considering their own skills and the network effects of the software, and the vendor of PS prices its product strategically. It is found that in presence of network effects, PS dominates the market when OSS does not provider higher benefits to users. This implies that OSS as a low-cost substitute to PS cannot survive in a market exhibiting network effects. To gain market share, OSS has to outperform PS by a large margin, which can be achieved if significant portion of users are highly skilled and thus can customize the OSS to better satisfy their needs.
{"title":"Impact of User Skills and Network Effects on the Competition between Open Source and Proprietary Software","authors":"Lihui Lin","doi":"10.2139/ssrn.945431","DOIUrl":"https://doi.org/10.2139/ssrn.945431","url":null,"abstract":"Despite the availability of source code, deploying open source software (OSS) in an enterprise environment requires expertise. Recent surveys and case studies show that the skills of IT staff in an organization are one of the key factors in OSS adoption decisions. Another important factor organizations consider when choosing a platform is network effects. This paper studies how users' skills and network effects may influence the market where proprietary software (PS) competes with OSS. In the model, users make adoption decisions considering their own skills and the network effects of the software, and the vendor of PS prices its product strategically. It is found that in presence of network effects, PS dominates the market when OSS does not provider higher benefits to users. This implies that OSS as a low-cost substitute to PS cannot survive in a market exhibiting network effects. To gain market share, OSS has to outperform PS by a large margin, which can be achieved if significant portion of users are highly skilled and thus can customize the OSS to better satisfy their needs.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"148 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116339953","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 high cost of international economic and financial crises highlights the need for a comprehensive framework to assess the robustness of national economic and financial systems. This paper proposes a new comprehensive approach to measure, analyze, and manage macroeconomic risk based on the theory and practice of modern contingent claims analysis (CCA). We illustrate how to use the CCA approach to model and measure sectoral and national risk exposures, and analyze policies to offset their potentially harmful effects. This new framework provides economic balance sheets for inter-linked sectors and a risk accounting framework for an economy. CCA provides a natural framework for analysis of mismatches between an entity's assets and liabilities, such as currency and maturity mismatches on balance sheets. Policies or actions that reduce these mismatches will help reduce risk and vulnerability. It also provides a new framework for sovereign capital structure analysis. It is useful for assessing vulnerability, policy analysis, risk management, investment analysis, and design of risk control strategies. Both public and private sector participants can benefit from pursuing ways to facilitate more efficient macro risk accounting, improve price and volatility discovery, and expand international risk intermediation activities.
{"title":"A New Framework for Analyzing and Managing Macrofinancial Risks of an Economy","authors":"Z. Bodie, D. Gray, R. C. Merton","doi":"10.2139/ssrn.936661","DOIUrl":"https://doi.org/10.2139/ssrn.936661","url":null,"abstract":"The high cost of international economic and financial crises highlights the need for a comprehensive framework to assess the robustness of national economic and financial systems. This paper proposes a new comprehensive approach to measure, analyze, and manage macroeconomic risk based on the theory and practice of modern contingent claims analysis (CCA). We illustrate how to use the CCA approach to model and measure sectoral and national risk exposures, and analyze policies to offset their potentially harmful effects. This new framework provides economic balance sheets for inter-linked sectors and a risk accounting framework for an economy. CCA provides a natural framework for analysis of mismatches between an entity's assets and liabilities, such as currency and maturity mismatches on balance sheets. Policies or actions that reduce these mismatches will help reduce risk and vulnerability. It also provides a new framework for sovereign capital structure analysis. It is useful for assessing vulnerability, policy analysis, risk management, investment analysis, and design of risk control strategies. Both public and private sector participants can benefit from pursuing ways to facilitate more efficient macro risk accounting, improve price and volatility discovery, and expand international risk intermediation activities.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131403272","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}
I develop a simple model that examines the relations between the extent of competitive interaction among firms in output markets, their capital structures, and the aggressiveness of their operating strategies. A firm's optimal leverage is related to the degree to which its operating strategy affects its rivals' value functions and resulting optimal output market choices. This relation is positive, regardless of whether the competition in output markets is in strategic substitutes or in strategic complements. I test the model's prediction using two proxies for the extent of competitive interaction among firms. The empirical evidence provides support for the model.
{"title":"Capital Structure and Interaction Among Firms in Output Markets - Theory and Evidence","authors":"Evgeny Lyandres","doi":"10.2139/ssrn.400620","DOIUrl":"https://doi.org/10.2139/ssrn.400620","url":null,"abstract":"I develop a simple model that examines the relations between the extent of competitive interaction among firms in output markets, their capital structures, and the aggressiveness of their operating strategies. A firm's optimal leverage is related to the degree to which its operating strategy affects its rivals' value functions and resulting optimal output market choices. This relation is positive, regardless of whether the competition in output markets is in strategic substitutes or in strategic complements. I test the model's prediction using two proxies for the extent of competitive interaction among firms. The empirical evidence provides support for the model.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"5 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120807500","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}
Marcia Millon Cornett, A. Marcus, A. Saunders, H. Tehranian
This paper examines the relationship between institutional investor involvement in and the operating performance of large firms. We confirm a significant relationship between a firm’s operating cash flow returns and both the percent of institutional stock ownership and the number of institutional stockholders. However, the positive relationship between the number of institution al investors holding stock and operating cash flow returns is found only for pressure-insensitive institutional investors (those with no business relationship with the firm). The number of pressure-sensitive institutional investors (those with an existing or potential business relationship with the firm) has no impact on performance. These results suggest that institutional investors that need to protect actual or promote potential business relationships with firms in which they invest are compromised as monitors of the firm, and lend credence to calls for greater independence of board members from firms.
{"title":"The Impact of Institutional Ownership on Corporate Operating Performance","authors":"Marcia Millon Cornett, A. Marcus, A. Saunders, H. Tehranian","doi":"10.2139/ssrn.468800","DOIUrl":"https://doi.org/10.2139/ssrn.468800","url":null,"abstract":"This paper examines the relationship between institutional investor involvement in and the operating performance of large firms. We confirm a significant relationship between a firm’s operating cash flow returns and both the percent of institutional stock ownership and the number of institutional stockholders. However, the positive relationship between the number of institution al investors holding stock and operating cash flow returns is found only for pressure-insensitive institutional investors (those with no business relationship with the firm). The number of pressure-sensitive institutional investors (those with an existing or potential business relationship with the firm) has no impact on performance. These results suggest that institutional investors that need to protect actual or promote potential business relationships with firms in which they invest are compromised as monitors of the firm, and lend credence to calls for greater independence of board members from firms.","PeriodicalId":180189,"journal":{"name":"Boston University Questrom School of Business Research Paper Series","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126962840","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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