Pub Date : 2009-03-01DOI: 10.4018/978-1-60566-256-5.CH002
L. Coutinho, Jaime Simão Sichman, O. Boissier
In this chapter, we discuss the concepts of agent organization, organizational model, and review some existing organizational models. Before the review, we discuss how to classify the diverse aspects of agent organizations currently captured by organizational models. These aspects are named "modelling dimensions". We show that there are at least four basic dimensions: the structural dimension mainly composed of roles and groups, the interactive dimension characterized by dialogical interaction structures, the functional dimension formed by goal/task decomposition, and the normative dimension in which we find the concepts of norms, rights, rules, and so forth. Apart from the basic dimensions, we also identify four other complementary dimensions: environment, evaluation, evolution, and ontology. These are related to the aspects of situatedeness, measurement, adaptation, and domain specific semantics of agent organizations. Finally, we compare the organizational models reviewed and describe how the idea of modelling dimension can help in finding correspondences between organizational models.
{"title":"Modelling Dimensions for Agent Organizations","authors":"L. Coutinho, Jaime Simão Sichman, O. Boissier","doi":"10.4018/978-1-60566-256-5.CH002","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH002","url":null,"abstract":"In this chapter, we discuss the concepts of agent organization, organizational model, and review some existing organizational models. Before the review, we discuss how to classify the diverse aspects of agent organizations currently captured by organizational models. These aspects are named \"modelling dimensions\". We show that there are at least four basic dimensions: the structural dimension mainly composed of roles and groups, the interactive dimension characterized by dialogical interaction structures, the functional dimension formed by goal/task decomposition, and the normative dimension in which we find the concepts of norms, rights, rules, and so forth. Apart from the basic dimensions, we also identify four other complementary dimensions: environment, evaluation, evolution, and ontology. These are related to the aspects of situatedeness, measurement, adaptation, and domain specific semantics of agent organizations. Finally, we compare the organizational models reviewed and describe how the idea of modelling dimension can help in finding correspondences between organizational models.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128273946","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH014
Nicoletta Fornara, M. Colombetti
The specification of open interaction systems is widely recognized to be a crucial issue, which involves the problem of finding a standard way of specifying: a communication language for the interacting agents, the entities that constitute the context of the interaction, and rules that regulate interactions. An approach to solve these problems consists in modelling open interaction systems as a set of artificial institutions. In this chapter we address this issue by formally defining, in the Event Calculus, a repertoire of abstract concepts (like commitment, institutional power, role, and norm) that can be used to specify every artificial institution. We then show how, starting from the formal definition of these concepts and of application-dependent concepts, it is possible to obtain a formal specification of a system. By using a suitable tool, it is then possible to simulate and monitor the system’s evolution through automatic deduction.
{"title":"Specifying Artificial Institutions in the Event Calculus","authors":"Nicoletta Fornara, M. Colombetti","doi":"10.4018/978-1-60566-256-5.CH014","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH014","url":null,"abstract":"The specification of open interaction systems is widely recognized to be a crucial issue, which involves the problem of finding a standard way of specifying: a communication language for the interacting agents, the entities that constitute the context of the interaction, and rules that regulate interactions. An approach to solve these problems consists in modelling open interaction systems as a set of artificial institutions. In this chapter we address this issue by formally defining, in the Event Calculus, a repertoire of abstract concepts (like commitment, institutional power, role, and norm) that can be used to specify every artificial institution. We then show how, starting from the formal definition of these concepts and of application-dependent concepts, it is possible to obtain a formal specification of a system. By using a suitable tool, it is then possible to simulate and monitor the system’s evolution through automatic deduction.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124268939","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH020
Marco Lamieri, D. Mangalagiu
AbstRAct In this chapter we present a model of organization aimed to understand the effect of formal and informal structures on the organization's performance. The model considers the interplay between the formal hierarchical structure and the social network connecting informally the agents emerging while the organization performs a task-set. The social network creation and evolution is endogenous, as it doesn't include any function supposed to optimize performance. After a review of the literature, we propose a definition of performance based on the efficiency in allocating the task of a simulated organization that can be considered as a network-based problem-solving system. We analyze how the emergence of a stable process in decomposing tasks under different market conditions can alleviate the rigidity and the inefficiencies of a hierarchical structure and we compare the performance of different hierarchical structures under variable environment conditions.
{"title":"Interactions Between Formal and Informal Organizational Networks","authors":"Marco Lamieri, D. Mangalagiu","doi":"10.4018/978-1-60566-256-5.CH020","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH020","url":null,"abstract":"AbstRAct In this chapter we present a model of organization aimed to understand the effect of formal and informal structures on the organization's performance. The model considers the interplay between the formal hierarchical structure and the social network connecting informally the agents emerging while the organization performs a task-set. The social network creation and evolution is endogenous, as it doesn't include any function supposed to optimize performance. After a review of the literature, we propose a definition of performance based on the efficiency in allocating the task of a simulated organization that can be considered as a network-based problem-solving system. We analyze how the emergence of a stable process in decomposing tasks under different market conditions can alleviate the rigidity and the inefficiencies of a hierarchical structure and we compare the performance of different hierarchical structures under variable environment conditions.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128331760","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH001
V. Dignum
AbstRAct Agent Organization can be understood from two perspectives: organization as a process and organization as an entity. That is, organization is considered both as the process of organizing a set of individuals, or as an entity in itself, with its own requirements and objectives. In fact, agent organizations demand the integration of both perspectives and rely for a great extent on the notion of openness and heterogeneity of MAS. Practical applications of agents to organizational modeling are being widely developed, however , formal theories are needed to describe interaction and organizational structure. Furthermore, it is necessary to get a closer look at the applicability of insights and theories from organization sciences to the development of agent organizations. In this chapter, current approaches to agent organizations are discussed. Agent Organizations bring concepts and solutions from sociology and organizational theory into agent research, integrating organizational and individual perspectives, and aim at the dynamic adaptation of models to organizational and environmental changes, both of which are impacted by the notion of openness and heterogeneity. The chapter also presents a promising application of agent organizations to the area of human-agent teams.
{"title":"The Role of Organization in Agent Systems","authors":"V. Dignum","doi":"10.4018/978-1-60566-256-5.CH001","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH001","url":null,"abstract":"AbstRAct Agent Organization can be understood from two perspectives: organization as a process and organization as an entity. That is, organization is considered both as the process of organizing a set of individuals, or as an entity in itself, with its own requirements and objectives. In fact, agent organizations demand the integration of both perspectives and rely for a great extent on the notion of openness and heterogeneity of MAS. Practical applications of agents to organizational modeling are being widely developed, however , formal theories are needed to describe interaction and organizational structure. Furthermore, it is necessary to get a closer look at the applicability of insights and theories from organization sciences to the development of agent organizations. In this chapter, current approaches to agent organizations are discussed. Agent Organizations bring concepts and solutions from sociology and organizational theory into agent research, integrating organizational and individual perspectives, and aim at the dynamic adaptation of models to organizational and environmental changes, both of which are impacted by the notion of openness and heterogeneity. The chapter also presents a promising application of agent organizations to the area of human-agent teams.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133159872","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH008
Davide Grossi, F. Dignum
In this chapter we investigate how organizations can be represented as graphs endowed with formal semantics. We distinguish different dimensions of organizations. Each of these dimensions leads to a different structure in the organizational graph. By giving the graphs a formal semantics in Description Logic we show that it is possible to formalize the effect of the organization on the activities of the agents playing the roles of the organization. Such perspective, which combines quantitative (graph-theory) and qualitative (logic) methods is shown to provide a formal ground for the study and analysis of properties of organizations which are commonly addressed only informally.
{"title":"Structural Aspects of Organizations","authors":"Davide Grossi, F. Dignum","doi":"10.4018/978-1-60566-256-5.CH008","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH008","url":null,"abstract":"In this chapter we investigate how organizations can be represented as graphs endowed with formal semantics. We distinguish different dimensions of organizations. Each of these dimensions leads to a different structure in the organizational graph. By giving the graphs a formal semantics in Description Logic we show that it is possible to formalize the effect of the organization on the activities of the agents playing the roles of the organization. Such perspective, which combines quantitative (graph-theory) and qualitative (logic) methods is shown to provide a formal ground for the study and analysis of properties of organizations which are commonly addressed only informally.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115930522","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH019
A. Artikis, Dimosthenis Kaponis, J. Pitt
We have been developing a framework for executable specification of norm-governed multi-agent systems. In this framework, specification is a design-time activity; moreover, there is no support for runtime modification of the specification. Due to environmental, social, or other conditions, however, it is often desirable, or even necessary, to alter the system specification during the system execution. In this chapter we extend our framework by allowing for ‘dynamic specifications’, that is, specifications that may be modified at run-time by the members of a system. The framework extension is motivated by Brewka’s ‘dynamic argument systems’ — argument systems in which the rules of order may become the topic of the debate. We illustrate our framework for dynamic specifications by presenting: (i) a dynamic specification of an argumentation protocol, and (ii) an execution of this protocol in which the participating agents modify the protocol specification.
{"title":"Dynamic Specifications for Norm-Governed Systems","authors":"A. Artikis, Dimosthenis Kaponis, J. Pitt","doi":"10.4018/978-1-60566-256-5.CH019","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH019","url":null,"abstract":"We have been developing a framework for executable specification of norm-governed multi-agent systems. In this framework, specification is a design-time activity; moreover, there is no support for runtime modification of the specification. Due to environmental, social, or other conditions, however, it is often desirable, or even necessary, to alter the system specification during the system execution. In this chapter we extend our framework by allowing for ‘dynamic specifications’, that is, specifications that may be modified at run-time by the members of a system. The framework extension is motivated by Brewka’s ‘dynamic argument systems’ — argument systems in which the rules of order may become the topic of the debate. We illustrate our framework for dynamic specifications by presenting: (i) a dynamic specification of an argumentation protocol, and (ii) an execution of this protocol in which the participating agents modify the protocol specification.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121844440","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH005
C. Cheong, M. Winikoff
Although intelligent agents individually exhibit a number of characteristics, including social ability, flexibility, and robustness, which make them suitable to operate in complex, dynamic, and error-prone environments, these characteristics are not exhibited in multi-agent interactions. For instance, agent interactions are often not flexible or robust. This is due to the traditional message-centric design processes, notations, and methodologies currently used. To address this issue, we have developed Hermes, a goaloriented design methodology for agent interactions which is aimed at being pragmatic for practicing software engineers. Hermes focuses on interaction goals, i.e., goals of the interaction which the agents are attempting to achieve, and results in interactions that are more flexible and robust than messagecentric approaches. In this chapter, we present the design and implementation aspects of Hermes. This includes an explanation of the Hermes design processes, notations, and design artifacts, along with a detailed description of the implementation process which provides a mapping of design artifacts to goal-plan agent platforms, such as Jadex.
{"title":"Hermes: Designing Flexible and Robust Agent Interactions","authors":"C. Cheong, M. Winikoff","doi":"10.4018/978-1-60566-256-5.CH005","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH005","url":null,"abstract":"Although intelligent agents individually exhibit a number of characteristics, including social ability, flexibility, and robustness, which make them suitable to operate in complex, dynamic, and error-prone environments, these characteristics are not exhibited in multi-agent interactions. For instance, agent interactions are often not flexible or robust. This is due to the traditional message-centric design processes, notations, and methodologies currently used. To address this issue, we have developed Hermes, a goaloriented design methodology for agent interactions which is aimed at being pragmatic for practicing software engineers. Hermes focuses on interaction goals, i.e., goals of the interaction which the agents are attempting to achieve, and results in interactions that are more flexible and robust than messagecentric approaches. In this chapter, we present the design and implementation aspects of Hermes. This includes an explanation of the Hermes design processes, notations, and design artifacts, along with a detailed description of the implementation process which provides a mapping of design artifacts to goal-plan agent platforms, such as Jadex.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126197722","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH012
G. Sukthankar, K. Sycara, J. Giampapa, Chris Burnett
AbstrAct This chapter discusses the problem of agent aiding of ad-hoc, decentralized human teams so as to improve team performance on time-stressed group tasks. To see how human teams rise to the challenge, we analyze the communication patterns of teams performing a collaborative search task that recreates some of the cognitive difficulties faced by teams during search and rescue operations. Our experiments show that the communication patterns of successful decentralized ad-hoc teams performing a version of the task that requires tight coordination differ both from the teams that are less successful at task completion and from teams performing a loosely coupled version of the same task. We conclude by discussing: (1) what lessons can be derived, from observing humans, to facilitate the development of agents to support ad-hoc, decentralized teams, and (2) where can intelligent agents be inserted into human teams to improve the humans' performance.
{"title":"Communications for Agent-Based Human Team Support","authors":"G. Sukthankar, K. Sycara, J. Giampapa, Chris Burnett","doi":"10.4018/978-1-60566-256-5.CH012","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH012","url":null,"abstract":"AbstrAct This chapter discusses the problem of agent aiding of ad-hoc, decentralized human teams so as to improve team performance on time-stressed group tasks. To see how human teams rise to the challenge, we analyze the communication patterns of teams performing a collaborative search task that recreates some of the cognitive difficulties faced by teams during search and rescue operations. Our experiments show that the communication patterns of successful decentralized ad-hoc teams performing a version of the task that requires tight coordination differ both from the teams that are less successful at task completion and from teams performing a loosely coupled version of the same task. We conclude by discussing: (1) what lessons can be derived, from observing humans, to facilitate the development of agents to support ad-hoc, decentralized teams, and (2) where can intelligent agents be inserted into human teams to improve the humans' performance.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131113361","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH015
F. Viganò, M. Colombetti
Institutions have been proposed to explicitly represent norms in open multi-agent systems, where agents may not follow them and which therefore require mechanisms to detect violations. In doing so, they increase the efficiency of electronic transactions carried out by agents, but raise the problem of ensuring that such institutions are not characterized by contradictory norms, and provide agents with all the needed powers to fulfill their objectives. In this chapter we present a framework to verify organizations regulated by institutions, which is characterized by a precise formalization of institutional concepts, a language to describe institutions, and a tool to model check them. Finally, to evaluate and exemplify our approach, we model and verify the Chaired Meeting Institution, showing that the verification of institutional rules constitutes a necessary step to define sound institutions.
{"title":"Verifying Organizations Regulated by Institutions","authors":"F. Viganò, M. Colombetti","doi":"10.4018/978-1-60566-256-5.CH015","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH015","url":null,"abstract":"Institutions have been proposed to explicitly represent norms in open multi-agent systems, where agents may not follow them and which therefore require mechanisms to detect violations. In doing so, they increase the efficiency of electronic transactions carried out by agents, but raise the problem of ensuring that such institutions are not characterized by contradictory norms, and provide agents with all the needed powers to fulfill their objectives. In this chapter we present a framework to verify organizations regulated by institutions, which is characterized by a precise formalization of institutional concepts, a language to describe institutions, and a tool to model check them. Finally, to evaluate and exemplify our approach, we model and verify the Chaired Meeting Institution, showing that the verification of institutional rules constitutes a necessary step to define sound institutions.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131593121","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 : 1900-01-01DOI: 10.4018/978-1-60566-256-5.CH023
Olivier Bonnet-Torrés, C. Tessier
This chapter focuses on a Petri Net-based model for team organization and monitoring. The applications considered are missions performed by several robots that cooperate in different ways according to the goals to be achieved. Formal operations on the Petri Net representing the mission plan allow the dynamic hierarchy of subteams to be revealed and the agents’ individual plans – including the relevant cooperation context – to be calculated. The model also allows several failure propagation ways within the team to be highlighted and local plan repair to be considered. Moreover Petri Nets allow direct implementation, and monitoring and control of the plan at each level of the organization: team, subteams, and individual robots.
{"title":"A Formal Petri Net Based Model for Team Monitoring","authors":"Olivier Bonnet-Torrés, C. Tessier","doi":"10.4018/978-1-60566-256-5.CH023","DOIUrl":"https://doi.org/10.4018/978-1-60566-256-5.CH023","url":null,"abstract":"This chapter focuses on a Petri Net-based model for team organization and monitoring. The applications considered are missions performed by several robots that cooperate in different ways according to the goals to be achieved. Formal operations on the Petri Net representing the mission plan allow the dynamic hierarchy of subteams to be revealed and the agents’ individual plans – including the relevant cooperation context – to be calculated. The model also allows several failure propagation ways within the team to be highlighted and local plan repair to be considered. Moreover Petri Nets allow direct implementation, and monitoring and control of the plan at each level of the organization: team, subteams, and individual robots.","PeriodicalId":344795,"journal":{"name":"Handbook of Research on Multi-Agent Systems","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123845912","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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