Prior research generally finds that the financial media levels the playing field among investors by reducing information acquisition costs for unsophisticated investors. In the setting of information transfers, I demonstrate that when media coverage is likely to reduce the industry information acquisition costs for both sophisticated and unsophisticated investors, their information gap may be widened. Specifically, I find that same-day Wall Street Journal (WSJ) coverage of a focal firm’s earnings announcement (EA) exacerbates information asymmetry of its industry peers around the focal firm’s EA day. However, when the WSJ article is published one day after the EA, there is no change in peer information asymmetry on both the EA day and the day after. Additional analysis shows that the effects of same-day WSJ coverage on peer information asymmetry are stronger when it is more likely to reduce peer investors’ industry information acquisition costs and when inferring the implications of the focal firm EA for the peer entails higher information integration costs. These findings suggest that media coverage may increase information asymmetry among investors despite its importance in information dissemination.
{"title":"Is Media Really the Great Information Equalizer? The Effects of WSJ Coverage of Firm Earnings Announcements on Peer Information Asymmetry in Information Transfers","authors":"Jing Xia","doi":"10.2139/ssrn.3837808","DOIUrl":"https://doi.org/10.2139/ssrn.3837808","url":null,"abstract":"Prior research generally finds that the financial media levels the playing field among investors by reducing information acquisition costs for unsophisticated investors. In the setting of information transfers, I demonstrate that when media coverage is likely to reduce the industry information acquisition costs for both sophisticated and unsophisticated investors, their information gap may be widened. Specifically, I find that same-day Wall Street Journal (WSJ) coverage of a focal firm’s earnings announcement (EA) exacerbates information asymmetry of its industry peers around the focal firm’s EA day. However, when the WSJ article is published one day after the EA, there is no change in peer information asymmetry on both the EA day and the day after. Additional analysis shows that the effects of same-day WSJ coverage on peer information asymmetry are stronger when it is more likely to reduce peer investors’ industry information acquisition costs and when inferring the implications of the focal firm EA for the peer entails higher information integration costs. These findings suggest that media coverage may increase information asymmetry among investors despite its importance in information dissemination.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123476083","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}
Zhang and Zhou (2016) use the concept of Bayesian persuasion due to Kamenica and Gentzkow (2011) to analyze information disclosure in a contest with one-sided asymmetric information. They show that an effort-maximizing designer can manipulate information disclosure to increase expected efforts in the contest, but base their analysis upon active participation in the contest by all types of the informed player. We extend their analysis to equilibria in which some informed types exert no effort in the contest, showing how this changes the type of information disclosure that arises.
Zhang and Zhou(2016)利用Kamenica and Gentzkow(2011)的贝叶斯说服概念分析了信息片面不对称竞争中的信息披露。他们表明，努力最大化的设计师可以操纵信息披露来增加比赛中的预期努力，但他们的分析是基于所有类型的知情玩家对比赛的积极参与。我们将他们的分析扩展到均衡，在这种均衡中，一些知情人士在竞争中不付出任何努力，显示这是如何改变出现的信息披露类型的。
{"title":"Partial Information Disclosure in a Contest","authors":"Derek J. Clark, Tapas Kundu","doi":"10.2139/ssrn.3808118","DOIUrl":"https://doi.org/10.2139/ssrn.3808118","url":null,"abstract":"Zhang and Zhou (2016) use the concept of Bayesian persuasion due to Kamenica and Gentzkow (2011) to analyze information disclosure in a contest with one-sided asymmetric information. They show that an effort-maximizing designer can manipulate information disclosure to increase expected efforts in the contest, but base their analysis upon active participation in the contest by all types of the informed player. We extend their analysis to equilibria in which some informed types exert no effort in the contest, showing how this changes the type of information disclosure that arises.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121233083","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}
Most of the literature on organizational design and incentives assumes public contracting. Yet most real world compensation contracts are private information, observed only by their direct signatories. This matters when agents work together to produce a joint output, because they care about each others' incentives. In this case, the principal can gain from designating one agent "team leader," with authority to decide, and hence observe, all the bonuses. Such "outsourcing" of contracting is never optimal with fully public contracts. With private contracts, by contrast, it raises effort by reassuring agents that the incentives provided are sufficiently strong; but it distorts effort allocation, as the team leader takes too much of the compensation budget. Even when observability is held constant, pay delegation can raise output by skewing bonuses towards more productive agents.
{"title":"Private Compensation and Organizational Design","authors":"A. Buffa, Qing Liu, L. White","doi":"10.2139/ssrn.3410479","DOIUrl":"https://doi.org/10.2139/ssrn.3410479","url":null,"abstract":"Most of the literature on organizational design and incentives assumes public contracting. Yet most real world compensation contracts are private information, observed only by their direct signatories. This matters when agents work together to produce a joint output, because they care about each others' incentives. In this case, the principal can gain from designating one agent \"team leader,\" with authority to decide, and hence observe, all the bonuses. Such \"outsourcing\" of contracting is never optimal with fully public contracts. With private contracts, by contrast, it raises effort by reassuring agents that the incentives provided are sufficiently strong; but it distorts effort allocation, as the team leader takes too much of the compensation budget. Even when observability is held constant, pay delegation can raise output by skewing bonuses towards more productive agents.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"139 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114232418","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 propose a tractable framework to introduce externalities in a screening model. Agents differ in both payoff-type and influence (how strongly their actions affect others). Applications range from pricing network goods to regulating industries that create externalities. Inefficiencies arise only if the payoff-type is unobservable. When both dimensions are unobserved, the optimal allocation satisfies lexicographic monotonicity: increasing along the payoff-type to satisfy incentive compatibility, but tilted towards influential agents to produce the externality. In particular, the allocation depends on a private characteristic that is payoff-irrelevant for the agent. We characterize the solution through a two-step ironing procedure that addresses the nonmonotonicity in virtual values arising from the countervailing impact of payoff-types and influence. If observable, influence is used as a signal of the payoff-type. We provide sufficient conditions for rents from influence to emerge even in a setting featuring atomistic agents.
{"title":"Screening while Controlling an Externality","authors":"Franz Ostrizek, Elia Sartori","doi":"10.2139/ssrn.3823180","DOIUrl":"https://doi.org/10.2139/ssrn.3823180","url":null,"abstract":"We propose a tractable framework to introduce externalities in a screening model. Agents differ in both payoff-type and influence (how strongly their actions affect others). Applications range from pricing network goods to regulating industries that create externalities. Inefficiencies arise only if the payoff-type is unobservable. When both dimensions are unobserved, the optimal allocation satisfies lexicographic monotonicity: increasing along the payoff-type to satisfy incentive compatibility, but tilted towards influential agents to produce the externality. In particular, the allocation depends on a private characteristic that is payoff-irrelevant for the agent. We characterize the solution through a two-step ironing procedure that addresses the nonmonotonicity in virtual values arising from the countervailing impact of payoff-types and influence. If observable, influence is used as a signal of the payoff-type. We provide sufficient conditions for rents from influence to emerge even in a setting featuring atomistic agents.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121515617","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}
Legal scholars have long recognized the clan or close-knit community as alternative institutions for supporting trade when contract law and trusted courts are unavailable. But recent research finds that heterogeneous business networks engage in high-stakes transactions that are not fully susceptible to formal, judicially backed contracting. These networks lack features seen as undergirding clan- or community-supported trade. They lack preexisting noncommercial social ties that allow reliable and trusted information to spread at low cost, make exiting the network difficult, and enable coordinated sanctioning of cheaters. Consequently, some leading scholars doubt that these networks are doing the work of sustaining cooperation. Can business networks sustain cooperation? If so, how? This Article offers an answer by presenting and theorizing an original case study into a long-term, sophisticated, high-stakes trade network that relied on neither the court nor the clan. When the gains from trade are sufficiently large, parties can build mechanisms to produce and disseminate reliable information needed to support trade by starting with transactions that align incentives and commit to high transparency about behavior. Parties can then strengthen their commitments by investing in the bilateral relationship and by building a network in which each party is connected to multiple other parties, which facilitates the dissemination of information about behavior in trading relationships. The targeted cultivation of strong personal ties together with the construction of a trading network allow for bonding of higher-risk transactions and a greater variety of transactional terms than can be supported by incentive alignment alone. The reinsurance trade suggests that cultivated, freestanding business networks can support extralegal private ordering under a larger set of circumstances than legal scholars currently appreciate.
{"title":"Contracts Without Courts or Clans: How Business Networks Govern Exchange","authors":"Sadie Blanchard","doi":"10.2139/SSRN.3780925","DOIUrl":"https://doi.org/10.2139/SSRN.3780925","url":null,"abstract":"Legal scholars have long recognized the clan or close-knit community as alternative institutions for supporting trade when contract law and trusted courts are unavailable. But recent research finds that heterogeneous business networks engage in high-stakes transactions that are not fully susceptible to formal, judicially backed contracting. These networks lack features seen as undergirding clan- or community-supported trade. They lack preexisting noncommercial social ties that allow reliable and trusted information to spread at low cost, make exiting the network difficult, and enable coordinated sanctioning of cheaters. Consequently, some leading scholars doubt that these networks are doing the work of sustaining cooperation. Can business networks sustain cooperation? If so, how? This Article offers an answer by presenting and theorizing an original case study into a long-term, sophisticated, high-stakes trade network that relied on neither the court nor the clan. When the gains from trade are sufficiently large, parties can build mechanisms to produce and disseminate reliable information needed to support trade by starting with transactions that align incentives and commit to high transparency about behavior. Parties can then strengthen their commitments by investing in the bilateral relationship and by building a network in which each party is connected to multiple other parties, which facilitates the dissemination of information about behavior in trading relationships. The targeted cultivation of strong personal ties together with the construction of a trading network allow for bonding of higher-risk transactions and a greater variety of transactional terms than can be supported by incentive alignment alone. The reinsurance trade suggests that cultivated, freestanding business networks can support extralegal private ordering under a larger set of circumstances than legal scholars currently appreciate.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128587523","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}
As firms evolve, the tasks required to generate firm value change, as does the ability of earnings to reflect changes in that value. To the extent earnings differentially captures managers’ effort toward desire tasks, contracting theory suggests its role in incentive pay should also change. However, anecdotal evidence suggests boards often fail to alter the weights on earnings in response to changes in the firm over time, relying instead on the status quo. In this study, we use a large longitudinal sample research design to investigate whether and how boards alter the weight on earnings in bonus contracts as its contracting usefulness changes over time. Our results suggest that although some contract evolution occurs, it often lacks timeliness. We find that boards often rely on contracting decisions made in prior periods, suggesting evidence of the status quo bias. Consistent with the status quo bias affecting board decisions, we document that process accountability mitigates a lack of concurrent contract evolution with shifts in firm evolution. Finally, we show that firms trade off earnings for other more idiosyncratic performance measures, suggesting alternate measures incrementally inform manager effort in early and late stages of firm development.
{"title":"The Weight on Earnings in Incentive Contracting: Dynamic Response or Status Quo?","authors":"Katharine D. Drake, Melissa A. Martin","doi":"10.2139/ssrn.3796180","DOIUrl":"https://doi.org/10.2139/ssrn.3796180","url":null,"abstract":"As firms evolve, the tasks required to generate firm value change, as does the ability of earnings to reflect changes in that value. To the extent earnings differentially captures managers’ effort toward desire tasks, contracting theory suggests its role in incentive pay should also change. However, anecdotal evidence suggests boards often fail to alter the weights on earnings in response to changes in the firm over time, relying instead on the status quo. In this study, we use a large longitudinal sample research design to investigate whether and how boards alter the weight on earnings in bonus contracts as its contracting usefulness changes over time. Our results suggest that although some contract evolution occurs, it often lacks timeliness. We find that boards often rely on contracting decisions made in prior periods, suggesting evidence of the status quo bias. Consistent with the status quo bias affecting board decisions, we document that process accountability mitigates a lack of concurrent contract evolution with shifts in firm evolution. Finally, we show that firms trade off earnings for other more idiosyncratic performance measures, suggesting alternate measures incrementally inform manager effort in early and late stages of firm development.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"252 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123591196","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 study bankruptcy rules in a setting where individuals have state contingent claims. A rule must distribute shares before uncertainty resolves. Within a wide class of parametric rules, we first characterize rules of ex-ante form in terms of the way that the rule processes inherent uncertainty in the individual claims. The key property is: No Penalty for Risk. It says that the rule does not penalize an individual in a situation that differs from another only in terms of the this individual's claim in that the former situation has a risky version of the riskless claim in the latter situation. With regard to the ex-post characterization, our key property is: Indifference to Independent Combinations. It says that if an individual is risk neutral with expected utility preferences then any rule that makes her indifferent between any bankruptcy problem and a corresponding independent combination of gamble between a degenerate gamble and a zero game (any bankruptcy game with zero endowment) forces the rule to be in the ex-post form. Finally, a partial comparative static result is provided which formalizes the claim that individuals generally and ex-ante rules more appealing when the level of the resource is suffciently low.
{"title":"Parametric Rules for State Contingent Claims","authors":"S. Chatterjee, Sinan Ertemel, Rajnish Kumar","doi":"10.2139/ssrn.3777083","DOIUrl":"https://doi.org/10.2139/ssrn.3777083","url":null,"abstract":"We study bankruptcy rules in a setting where individuals have state contingent claims. A rule must distribute shares before uncertainty resolves. Within a wide class of parametric rules, we first characterize rules of ex-ante form in terms of the way that the rule processes inherent uncertainty in the individual claims. The key property is: No Penalty for Risk. It says that the rule does not penalize an individual in a situation that differs from another only in terms of the this individual's claim in that the former situation has a risky version of the riskless claim in the latter situation. With regard to the ex-post characterization, our key property is: Indifference to Independent Combinations. It says that if an individual is risk neutral with expected utility preferences then any rule that makes her indifferent between any bankruptcy problem and a corresponding independent combination of gamble between a degenerate gamble and a zero game (any bankruptcy game with zero endowment) forces the rule to be in the ex-post form. Finally, a partial comparative static result is provided which formalizes the claim that individuals generally and ex-ante rules more appealing when the level of the resource is suffciently low.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"210 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132561027","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}
Non-deal roadshows (NDRs) are private meetings between management and institutional investors, typically organized by sell-side analysts. We find that around NDRs, local institutional investors trade heavily and profitably, while retail trading is significantly less informed. Analysts who sponsor NDRs issue significantly more optimistic recommendations and target prices, coupled with more “beatable” earnings forecasts, consistent with analysts issuing strategically biased forecasts in order to win NDR business. Our results suggest that NDRs result in a substantial information advantage for institutional investors and create significant conflicts of interests for the analysts that organize them.
{"title":"Non-Deal Roadshows, Informed Trading, and Analyst Conflicts of Interest","authors":"D. Bradley, Russell Jame, Jared Williams","doi":"10.2139/ssrn.3302687","DOIUrl":"https://doi.org/10.2139/ssrn.3302687","url":null,"abstract":"Non-deal roadshows (NDRs) are private meetings between management and institutional investors, typically organized by sell-side analysts. We find that around NDRs, local institutional investors trade heavily and profitably, while retail trading is significantly less informed. Analysts who sponsor NDRs issue significantly more optimistic recommendations and target prices, coupled with more “beatable” earnings forecasts, consistent with analysts issuing strategically biased forecasts in order to win NDR business. Our results suggest that NDRs result in a substantial information advantage for institutional investors and create significant conflicts of interests for the analysts that organize them.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122605229","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 careerist expert advises a sequence of principals on their actions to match a hidden, randomly evolving state. The expert privately knows her competence. The principals learn about the state and the expert’s competence from past advice and past action outcomes, both publicly observable. I find that the equilibrium can feature a “crisis of expertise,” in which principals dismiss a competent expert’s correct advice, and rely only on public information. Notably, the crisis happens precisely when the quality of public information is low, and thus when expert knowledge is much needed. I discuss policy implications for alleviating the crisis.
{"title":"The Crisis of Expertise","authors":"Allen I. K. Vong","doi":"10.2139/ssrn.3768185","DOIUrl":"https://doi.org/10.2139/ssrn.3768185","url":null,"abstract":"A careerist expert advises a sequence of principals on their actions to match a hidden, randomly evolving state. The expert privately knows her competence. The principals learn about the state and the expert’s competence from past advice and past action outcomes, both publicly observable. I find that the equilibrium can feature a “crisis of expertise,” in which principals dismiss a competent expert’s correct advice, and rely only on public information. Notably, the crisis happens precisely when the quality of public information is low, and thus when expert knowledge is much needed. I discuss policy implications for alleviating the crisis.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133768452","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}
Upskilling is an investment in human capital that allows a worker to successfully undertake a new task or new project within his/her existing job. It involves costly e⁄ort on behalf of the employee to acquire new skills and new knowledge. In this context, one essential question for managers is whether to invest in workersupskilling or let them pay for the investment in human capital and compensate them accordingly. Using traditional contract theory analysis, we show that the latter choice is not cost-neutral since the most exible workers benet of an informational rent. A prot comparison shows that it might be in the interest of a company to invest in worker upskilling, rather than to rely on worker self-training.
{"title":"Who Should Pay the Bill for Employee Upskilling?","authors":"R. Vranceanu, A. Sutan","doi":"10.2139/ssrn.3719009","DOIUrl":"https://doi.org/10.2139/ssrn.3719009","url":null,"abstract":"Upskilling is an investment in human capital that allows a worker to successfully undertake a new task or new project within his/her existing job. It involves costly e⁄ort on behalf of the employee to acquire new skills and new knowledge. In this context, one essential question for managers is whether to invest in workersupskilling or let them pay for the investment in human capital and compensate them accordingly. Using traditional contract theory analysis, we show that the latter choice is not cost-neutral since the most exible workers benet of an informational rent. A prot comparison shows that it might be in the interest of a company to invest in worker upskilling, rather than to rely on worker self-training.","PeriodicalId":119201,"journal":{"name":"Microeconomics: Asymmetric & Private Information eJournal","volume":"333 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125790151","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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