Abstract:While online discussion platforms have been widely used and received a lot of attention in the infor_x005fmation systems communities，its information organization structure is still in the original form．Research that explains what kind of information organization structure is more suitable for online discussion is rare and confused if any．Thus a theory for optimal information organization in online group discussion is highly desirable．In this study，we follow the perspective of task-technology fitness，describe the fitness between tasks and information organization structures from the three perspectives of communication，process structuring，and information processing，and predict group performances based on task-technology fit condition．We also designed an experiment to validate if a match between task and information organization structure will lead to increased performance．The results indicate that for idea generation tasks，using a groupware with linear structures will lead to higher group performances compared to tree structures．On the other hand，for judgment tasks，using a groupware with tree structures will lead to higher group performances compared to linear structures． The proposed theory and method is extendable，which means we can evaluate the fitness between new task types and unseen technology，and predict the group performances．

Abstract:Considering that there are undesired outputs in many production processes and the fact that the data for the efficiency evaluation contain random errors，a random DEA model was built for the above two prob_x005flems．The model defined the priority of the decision-making units through introducing the concept of risk and depicted the weak disposability of the undesired outputs by applying the " correlation" concept from statistics．This paper combined the randomness and the weak disposability in the framework of optimization theory to build the evaluation model that could investigate both．The empirical analysis investigated the similarities and differences of the model’s evaluation results under different levels of random errors and under the consideration of weak disposability or not．The results showed that the model can solve the problem of undesirable outputs and random errors in the data．In conclusion，the model，with broad applicability，is superior to the existing models．

Abstract:Based on the study of Karp’s ski rental model for the classical online leasing problem，this paper considers the multiple online leasing model for continuous relaxation problem with market interest rate．Firstly， we investigate the optimal offline strategy and show the relationship between the optimal offline cost and market interest rate．Then，based on the online characteristics that offline adversary might stop using assets at anytime so that online players may encounter a high-risk situation like no longer using assets shortly after purchasing，we propose a balancing risk strategy and obtain its optimal competitive ratio by using online algorithm and com_x005fpetitive analysis．Meanwhile，we prove that the competitive ratio of the balancing risk strategy is the optimal ratio for this problem．At last，the monotonicity of relevant variables in the optimal competitive ratio is discussed，and the result shows that the competitive performance of online strategy improves significantly with the factor of market interest rate and multi-unit asset，thereby enhancing the online rental decision-making efficiency．

Abstract:Classic financial theories are far from the explaining lots of anomalies in real markets．Nevertheless the Econophysics，which is based on nonlinear dynamics，complex system and statistical physics and aims at explaining and modeling these anomalies，has been an important area in financial studies．Firstly，this paper briefly introduces the classic financial theory．Secondly，several anomalies which are accepted generally but can not be explained by classic financial theory are summarized and then the reason of the rising of Econophys_x005fics is proposed．We comment on several key aspects such as the definition，researching content and new evolution of econophysics．Finally，the relationship between the classic financial theory and econophysics is discussed．

Abstract:Improvement in external governance environment can constrain the earnings management，and out of personal gains，the ultimate controller can play a different role towards earnings management． From the ex_x005fternal governance environment perspective，applying dynamic panel data consisting 836 companies listed on Shanghai and Shenzhen Exchanges in the period 2004-2011，we test the impact of external institutional environment on earnings management using system GMM method，and examine the role of listed companys’ultimate controllers．The results show: External institutional environment is negatively correlated with earnings management．External institutional environment affects earnings management differently depending on the characteristics and administrative ranks of the ultimate controllers．Specifically，external institutional environment plays a more significant role in constraining earnings management in state-controlled listed companies compared with non-state-controlled ones．Furthermore，external governance environment seems to be more effective in restraining earnings management in listed companies under central government’s control compared with the ones under the control of regional governments．To conclude，the results illustrate the crucial role that the ultimate controller plays in regulating external governance and earnings management．This study enriches the researches of earnings management，thus contributes to the understanding of the institutional root-cause of the differences in earnings management behaviors among Chinese listed companies．

Abstract:This paper studies how the controlling shareholders’financial constraints influence their tunneling behavior and related economic consequences from the perspective of controlling shareholders’stock pledge and freezing．We have documented strong evidence suggesting that: When the controlling shareholders are facing serious financial constraints ( when the equity is pledged or frozen) ，they tend to tunnel more money from lis_x005fted companies，which has negative effects on both the accounting performances and market values of listed companies．At the same time，although the tunneling behavior of large shareholders under financial constraints is greatly mitigated by the external supervision and internal balance power，the above results are still statistically significant even when external supervision and internal balance power are stronger．The above results show that，using stock pledge as a proxy for financial constraint and tunneling incentive of controlling shareholders is more powerful to explain the behavior of controlling shareholders．This study provides not only an analytical perspective and empirical variables to the existing controlling shareholders and corporate governance literature，but also important references for the regulators to monitor the behavior of controlling shareholders and for outside investors to make investment decisions．

Abstract:Considering that most of the actual location practice is in a Euclidean plane，this paper studied the constraint mathematical model of online median location problem on the Euclidean plane under the general metric model．By analyzing the structural properties of this problem，this paper designed a polynomial-time competitive algorithm with proven good constant competitive ratio．