Impacts of distorted fishery statistical data on assessments of three surplus production models

We evaluated the effect of various error sources in fishery harvest/effort data on the maximum sustainable yield （MSY） and corresponding fishing effort （EMsv） using Monte Carlo simulation analyses. A high coefficient of variation （CV） of the catch and effort values biased the estimates of MSY and EMsv. Thus, the state of the fisheries resource and its exploitation was overestimated. We compared the effect using three surplus production models, Hilborn-Waters （H-W）, Schnute, and Prager models. The estimates generated using the H-W model were significantly affected by the CV. The Schnute model was least affected by errors in the underlying data. The CVof the catch data had a greater impact on the assessment than the CV of the fishing effort. Similarly, the changes in CV had a greater impact on the estimated maximum sustainable yield （MSY） than on the corresponding estimate of fishing effort （EMsY）. We discuss the likely effect of these biases on management efforts and provide suggestions for the improvement of fishery evaluations.

Deciding whether manufacturing firms share product links on owned social media considering fan effects

An optimization model is proposed to examine the choice of sharing or not sharing the product link for manufacturing firms with owned social media by considering the role of fan effects.The equilibrium marketing effort level and firm profit in both cases are compared.The results show that the firm chooses to share(not share)the product link when the social platform commission rate is low(high).Moreover,the likelihood of sharing the product link increases as the fan effect weakens and the perceived conversion cost strengthens.Interestingly,the marketing effort level increases with the product price,but firm profit does not always follow.Additionally,as the fan effect and fan count grow,so does the firm s profit.Furthermore,when the firm shares the product link,the level of marketing effort and firm profit decrease with the commission rate.Conversely,when the firm does not share the product link,those aforementioned factors increase as the perceived conversion cost declines.These results thus suggest that firms should enhance the influence of owned social media to attract more high-quality fans,and social platforms should optimize the product link functionality.

Enhancing customers prevention efforts:An incentive feedback mechanism design

To improve the inefficient prevention caused by customers unwillingness to adopt prevention strategies in health management,an incentive feedback mechanism that is based on game theory and contract design theory is introduced.The conditions for making customers and health maintenance organizations(HMOs)willing to participate in the proposed mechanism are given.A dual nonlinear programming model is used to identify the optimal prevention effort of customers and the pricing strategy of HMOs.Results show that to generate increased benefits,HMOs need to consider cost sharing when customers are not familiar with the proposed health services.When health services are gradually accepted,the cost sharing factor can be gradually reduced.Simulation shows that under random circumstances in which the market reaches a certain size,the proposed method exhibits a positive network externality.Motivated by network externality,HMOs only need to make their customers understand that the larger the number of participants,the greater the utility of each person.Such customers may then spontaneously invite others to purchase insurance.

相期吾少年 匡时宜努力——谈“努力”的训练

“大能力”培养的第三条是:努力。我们对努力的表述是“愿意认真工作”。一、“努力”是一种积极的意志品质“努力”也好,“愿意认真工作”也好,说到底,是一种积极的、有益的意志品质。

Why China’s Tax Revenue Is Likely to Maintain Its Rapid Growth: An Explanation within the Framework of Tax Capacity and Tax Effort

An analysis of the dynamics of the rapid growth of tax revenue in China within the framework of tax capacity and tax effort reveals three major drivers following the tax sharing reform. First, the nature of the decentralization contract under the tax sharing system provides strong incentives for taxation. Second, the system of indirect taxes boosts taxpayers’ taxable capacity. And third, China is enjoying the intensively present tax growth dividend. In the future, the first factor will diminish; the second factor will partially cease functioning; and the third factor will remain constant. Over the long term, the tax growth dividend will be long lasting and tax revenue will keep growing at a high speed.

Dynamic analysis of Bernoulli-Euler piezoelectric nanobeam with electrostatic force

The effect of electrostatic force on the dynamic response of a Bernoulli-Euler piezoelectric nanobeam is analyzed in this paper.The governing equations with the electrostatic stress are derived based on a variational principle.Static bending problem of simply supported and cantilever beam is considered.The influence of the electrostatic force on the first four natural frequencies is discussed.It is shown that when the beam thickness is small,the effect of the electrostatic force is significant.When the beam thickness is large,the electrostatic force is insignificant and can be neglected.The results also indicate that one can adjust the natural frequency of a nanobeam by applying appropriate voltage.

Promising Future,yet More Efforts Needed

The Research Collaboration Group on multi-scale methodology and complex systems was financed by the Chinese Academy of Sciences in recognition of the challenge of multi-scale spatio-temporal structure in the 21^st-century chemical engineering science with the hope of possible breakthrough and new opportunities through better understanding and correlation of phenomena occurring at different scales.