Two-stage proportionate flexible flow shop to minimize the makespan

We consider a two-stage flexible flow shop problem with a single machine at one stage and m identical machines at the other stage, where the processing times of each job at both stages are identical. The objective is to minimize the makespan. We describe some optimality conditions and show that the problem is NP-hard when m is fixed. Finally, we present an approximation algorithm that has a worst-case performance ratio of $\frac{5}{4}$ for m=2 and $\frac{\sqrt{1+m^{2}}+1+m}{2m}$ for m≥3.     

An extension of Stein-Lovász theorem and some of its applications

The Stein-Lovász theorem provides an algorithmic way to deal with the existence of certain good coverings, and thus offers bounds related to some combinatorial structures. An extension of the classical Stein-Lovász theorem for multiple coverings is given, followed by some applications for finding upper bounds of the sizes of (d,s out of r;z]-disjunct matrices and (k,m,c,n;z)-selectors, respectively. This gives a unified treatment for some previously known results relating to various models of group testing.     

Bursts and heavy tails of execution time in business processes

This paper investigates the phenomena and effects of heavy tails of execution time in business processes. We approached the heavy tails as a particular variation of business process execution, and analysed them from empirical data of its execution time. The features and possible causes of the heavy tails were investigated. A workflow simulation was conducted to simulate the heavy tails, in order to evaluate quantitatively their effects to business process performance. The simulation outcomes demonstrate that (1) even a heavy-tailed activity in a business process can cause large variation of end-to-end execution times of the process and (2) there are significant prediction gaps resulted by different assumptions of execution times between an exponential distribution and a heavy-tailed distribution.     

Socioeconomic Risk for Adolescent Cognitive Control and Emerging Risk‐Taking Behaviors

This study examined whether cognitive control mediated the association between socioeconomic status (SES; composite of income‐to‐needs ratio and parent education) and changes in risk‐taking behaviors. The sample included 167 dyads of adolescents (53% male; M_age = 14.07 years at Time 1) and their parents, assessed annually across 4 years. Parents reported socioeconomic variables at Time 1. Adolescents reported risk‐taking behaviors at Times 1 and 4, and completed a functional magnetic resonance imaging cognitive control task at Times 2 and 3. Lower SES was associated with lower behavioral (but not neural) cognitive control, which was associated with increases in risk‐taking behaviors. The findings suggest that elevated socioeconomic risk may compromise cognitive control which can cascade into maladaptive behaviors in adolescence.     

Where You Lead,I Will Follow: Exploring Sibling Similarity in Brain and Behavior During Risky Decision Making

This exploratory study examined whether social learning increases similarity in adolescent siblings’ behavior and neural patterns during risky decision making. Participants included 86 adolescents (43 sibling dyads; younger siblings: M_age = 12.2 years; 22 females; older siblings: M_age = 14.6 years; 20 females) who completed questionnaires, and a decision‐making task during an fMRI scan. Younger siblings became more similar to their older siblings’ risky decision making after observing their older sibling take risks). Younger siblings who reported greater modeling of their older sibling, and less differentiation from them, showed increased neural similarity to their older siblings in the ventromedial prefrontal cortex, and the right anterior insula and ventral striatum, respectively. These findings highlight siblings as salient social agents in how adolescents process risky decision making.     

健康舒适视角下城市地下空间规划设计思路初探

随着城市人口的增长,地面空间不足的问题日益突出,而地下空间开发可有效解决该问题.长期以来,我国地下空间规划设计大多从集约利用空间、节约资源能源、保护生态环境等角度出发,对地下空间使用者的健康舒适这一视角关注较少.在解析健康、舒适与地下空间概念的基础上,基于环境心理学中的Vischer舒适理论,构建地下空间健康舒适构成要素的关系框架,并在总结国内外相关研究和地下空间主要特征的基础上,从通风系统、视觉舒适、安全感、声舒适四个方面提出了健康舒适视角下地下空间规划设计思路,从健康与舒适的视角丰富了国内城市地下空间规划设计的相关理论.     

临床医学留学生心胸外科学教学实践探讨

医学留学生教育在我国高等教育中越来越受到重视,本科室自2006年以来承担苏州大学医学部留学生心胸外科见习、实习的教学工作,近十年来本科室对医学留学生心胸外科学教学过程中教学方法、教学手段、教学内容进行了一些有益的探索,对这些探索进行总结,为医学留学生教学提供参考。     

Bayesian inference of multiple structural change models with asymmetric GARCH errors

Structural change in any time series is practically unavoidable, and thus correctly detecting breakpoints plays a pivotal role in statistical modelling. This research considers segmented autoregressive models with exogenous variables and asymmetric GARCH errors, GJR-GARCH and exponential-GARCH specifications, which utilize the leverage phenomenon to demonstrate asymmetry in response to positive and negative shocks. The proposed models incorporate skew Student-t distribution and prove the advantages of the fat-tailed skew Student-t distribution versus other distributions when structural changes appear in financial time series. We employ Bayesian Markov Chain Monte Carlo methods in order to make inferences about the locations of structural change points and model parameters and utilize deviance information criterion to determine the optimal number of breakpoints via a sequential approach. Our models can accurately detect the number and locations of structural change points in simulation studies. For real data analysis, we examine the impacts of daily gold returns and VIX on S&P 500 returns during 2007–2019. The proposed methods are able to integrate structural changes through the model parameters and to capture the variability of a financial market more efficiently.

     

How controversial businesses communicate CSR on Facebook: Insights from the Canadian cannabis industry

This study advances our current understanding of corporate social responsibility (CSR) communication in a controversial industry by analyzing CSR-related Facebook posts from seven Canadian public cannabis companies. Our findings indicated that these companies’ CSR communication on Facebook was mostly instrumentalist, lacked transparency, and used effective multimedia characteristics. In addition, associations between communication strategies and public engagement on social media (e.g., # of likes, comments, and shares) revealed both opportunities and ethical concerns regarding CSR communication in controversial businesses.