Near-optimal control policy for loss networks

In this paper, the phenomenon of the optimal management of requests of service in general networks is formulated as a control problem for a finite number of multiserver loss queues with Markovian routing. This type of problem may arise in a wide range of fields, e.g., manufacturing industries, storage facilities, computer networks, and communication systems. Using inductive approach of dynamic programming, the optimal admission control can be induced to be the functions of the number of requested service in progress. However, for large-scale network, the computational burden to find optimal control policy may be infeasible due to its involvement of the states for all stations in the networks. Hence, the idea of bottleneck modeling is borrowed to compute the near-optimal admission control policy. We reduced the scale of loss network and decreased the difference between the original and reduced models by making compensation for system parameters. A novel method is proposed in this paper to compute the compensation. Numerical results show that the near-optimal control policy demonstrates close performance to the optimal policy.     

Developments in East Asian Welfare Studies

This essay in introduction is to the field of study, rather than to the present, itself distinguished, collection of papers. As such, it opens with a series of ‘flashbacks’: to the ways in which social policy, and the study of social policy, developed out of the interaction between Western welfare states (in this case Britain) and Asia Pacific. The main body of the article then charts the increasing presence of East Asian modes of welfare within comparative social policy, before going on to distinguish between the different types of approach to East Asian welfare study which have so far been adopted. Two sets of three‐part criteria have been adopted for the purposes of classification: focusing first on the dimensions (single case studies of specific countries; East Asia as a region; East Asia in comparison with other parts of the world) and second on the level of issues (matters of policy; of welfare system; of welfare regime) characteristic of each study in question. The article concludes with a restatement of its purpose: not to question the adequacy of hitherto Western (notably, Esping‐Andersen) approaches to the study of welfare regimes, but to demonstrate the need for a substantive extension to their scope.     

Dimensions of subjective well-being and effects of physical activity in Chinese older adults

Subjective well-being (SWB) and its relationship with physical activity have not been systematically investigated in older Chinese people. This study explored these issues using qualitative interviews with a purposive sample of 23 community-dwelling Chinese older adults (age 55-78 y, 12 women); 16 were physically active and 7 physically inactive. Using cross-case analyses, 7 dimensions of SWB emerged: physical, psychological, developmental, material, spiritual, sociopolitical, and social. Although elements of SWB may be shared across cultures, specific distinctions were identified. Active respondents reported the unique contributions of physical activity to the physical, psychological, developmental, and social elements of SWB. The findings suggest that physical activity could enhance the quality of life in Chinese older adults.     

The health effects of caregiving by grandparents in Taiwan: an instrumental variable estimation

Previous research on the health effects of caring for grandchildren has had variable findings, including both positive and negative effects on the health of grandparents. The estimated effects of caregiving may be affected by selection, with the health of grandparent affecting the likelihood of undertaking caregiving. The health effects of caregiving also likely differ according to the cultural motivations for caregiving by grandparents. This paper assesses whether selection into caring for grandchildren affects the estimated effects of caregiving on the health of Taiwanese grandparents. We used four waves (1993?C2003) of the Survey of Health and Living Status of the Elderly in Taiwan to estimate the effect of grandparent caregiving on self-rated health, mobility, and depression. To control for unobserved selection into caregiving, we employed time-varying instrumental variables (the number of grandchildren and marital status of adult children) in addition to person fixed effects. After adjusting for baseline differences, caregivers had better self-rated health, fewer mobility limitations, and fewer depressive symptoms compared to the non-caregivers, which suggest evidence of health improvement for grandparents. Instrumental variable analysis showed that caring for grandchildren was endogenously determined with grandparents?? mobility limitations, and grandparent caregivers benefited from a significant reduction in the number of mobility limitations. Our finding suggests that caring for grandchildren can be beneficial for the health of Taiwanese grandparents and supports our hypothesis that a culturally expected role of caregiving results in role enhancement.     

Related party transactions and audit fees: the role of the internal audit function

Related party transactions (RPTs) are viewed as genuine transactions that rationally fulfil other economic demands of a company. However, RPTs can also be used to transfer wealth from minority shareholders to controlling shareholders. The existence of such transactions may deteriorate financial reporting quality, increase audit risk, and as a result increase audit fees. This study examines the relationship between RPTs and audit fees in Malaysia, where ownership is often concentrated within a controlling family and corporate governance mechanisms are poor. It also investigates the moderating effect of the internal audit function (IAF) on this relationship. We find that external auditors base their fees on the types of RPTs undertaken. Specifically, our results show that audit fees are higher for firms that undertake RPTs involving the sale and purchase of assets, goods, and services. We also document that external auditors rely on the IAF, and thus their fees are lower for firms that undertake RPTs and that have made a large investment in an IAF. Our study is the first to provide evidence that RPTs in Malaysian firms may be abused as a channel to facilitate tunnelling and that the IAF plays a vital role in controlling such transactions.     

A niche analysis of three interpersonal media: examining the competition among Facebook,Line, and e-mail

Dimmick’s niche theory was applied to examine the gratifications obtained from the use of Facebook, Line, and e-mail to understand the competitive relationships among them in Taiwan. Two methods were adopted, the first of which was to conduct 20 intensive interviews. The second method was a telephone survey that consisted of 1,042 valid calls. The results of the data analysis showed that among the three media, Line had the widest niche breadth and the highest scores for competitive superiority, and it competed strongly with Facebook. However, the overall findings actually indicate that the strengths of Facebook and Line were more complementary than competitive. Therefore, based on these results, it is predicted that Facebook and Line are able to coexist. Furthermore, based on the results, it is predicted that Line is unable to replace e-mail in safe and formal communication because it is effective in task coordination whereas the strength of e-mail is in documentation. The results also showed that Facebook and Line had wide niche breadths, indicating that they are “generalists” in terms of communication. In contrast, e-mail had a narrow niche breadth, indicating that it is a “specialist” focusing on safe and formal communication. The results also showed that the competitive superiority scores of a medium were a powerful predictor of the use history of that medium only when individuals perceived that two media were similar.     

Optimal experimental plan for multi-level stress testing with Weibull regression under progressive Type-II extremal censoring

In the design of constant-stress life-testing experiments, the optimal allocation in a multi-level stress test with Type-I or Type-II censoring based on the Weibull regression model has been studied in the literature. Conventional Type-I and Type-II censoring schemes restrict our ability to observe extreme failures in the experiment and these extreme failures are important in the estimation of upper quantiles and understanding of the tail behaviors of the lifetime distribution. For this reason, we propose the use of progressive extremal censoring at each stress level, whereas the conventional Type-II censoring is a special case. The proposed experimental scheme allows some extreme failures to be observed. The maximum likelihood estimators of the model parameters, the Fisher information, and asymptotic variance–covariance matrices of the maximum likelihood estimates are derived. We consider the optimal experimental planning problem by looking at four different optimality criteria. To avoid the computational burden in searching for the optimal allocation, a simple search procedure is suggested. Optimal allocation of units for two- and four-stress-level situations is determined numerically. The asymptotic Fisher information matrix and the asymptotic optimal allocation problem are also studied and the results are compared with optimal allocations with specified sample sizes. Finally, conclusions and some practical recommendations are provided.     

Roles of Vegetable Surface Properties and Sanitizer Type on Annual Disease Burden of Rotavirus Illness by Consumption of Rotavirus-Contaminated Fresh Vegetables: A Quantitative Microbial Risk Assessment

Enteric viruses are often detected in water used for crop irrigation. One concern is foodborne viral disease via the consumption of fresh produce irrigated with virus-contaminated water. Although the food industry routinely uses chemical sanitizers to disinfect post-harvest fresh produce, it remains unknown how sanitizer and fresh produce properties affect the risk of viral illness through fresh produce consumption. A quantitative microbial risk assessment model was conducted to estimate (i) the health risks associated with consumption of rotavirus (RV)-contaminated fresh produce with different surface properties (endive and kale) and (ii) how risks changed when using peracetic acid (PAA) or a surfactant-based sanitizer. The modeling results showed that the annual disease burden depended on the combination of sanitizer and vegetable type when vegetables were irrigated with RV-contaminated water. Global sensitivity analyses revealed that the most influential factors in the disease burden were RV concentration in irrigation water and postharvest disinfection efficacy. A postharvest disinfection efficacy of higher than 99% (2-log₁₀) was needed to decrease the disease burden below the World Health Organization (WHO) threshold, even in scenarios with low RV concentrations in irrigation water (i.e., river water). All scenarios tested here with at least 99.9% (3-log₁₀) disinfection efficacy had a disease burden lower than the WHO threshold, except for the endive treated with PAA. The disinfection efficacy for the endive treated with PAA was only about 80%, leading to a disease burden 100 times higher than the WHO threshold. These findings should be considered and incorporated into future models for estimating foodborne viral illness risks.