SOME COMMENTS ON “A SYSTEMS PERSPECTIVE ON MATERIALS REQUIREMENTS PLANNING”*

We believe there are some serious deficiencies in the Morecroft article on MRP problems which appeared in a recent issue of this journal. The article, at the most, shows that MRP, inappropriately imposed on an existing production system, can result in undesirable system performance. This does not represent a new or startling conclusion. Four problem areas in the article are discussed, and suggested alternative approaches are offered.     

if条件句与充分条件性——if构块式理据的研究

多种不同的语义关系都可以进入if条件句,Sweetser提出三域进行分析;这一分析细致深入,但略嫌共性概括不足.充分条件性是if构块式大家族的背后同一理据的假设;据此,if条件句大家族分为两大构块式群,下分四小类.这个大家族是一个典型范畴,第一小类典型条件句作为充分条件假言判断的语言表达形式是最典型的成员,以下各小类向着边缘成员演变,构成了一个连续统.对if条件句的理解,要通过常规推理,将从句一主句的关系补足为充分条件同其结果的关系.if条件句的多种意义最后都可回归到充分条件性,这就是各类if条件句最后都可归入if构块式大家族的同一理据.这一研究再一次表明了含意本体论的常规关系和常规推理理论在研究构块式的理据方面可能起的作用.     

THE HARMS SHOE COMPANY: DEVELOPMENT OF A COMPUTER MODEL FOR THE CLASSROOM

This paper describes a case that examines five key topics in production and operations management [1]—forecasting, inventory control, transportation planning, aggregate planning, and the disaggregation of the aggregate plan—in an integrated, realistic manner for upper-level undergraduate business majors [3]. The case structure stresses the linkage of these interrelated subjects and supplements the regular classroom presentations dealing with them. The case relies on computer calculations at each stage to provide the information input for calculations at the next stage. It is a static model with a twelve-month planning horizon. Students complete several exercises and assume several roles as the case unfolds. They act on their own in filling some roles and as members of teams in performing others. They do not compete with each other, as the purpose of the case is to help them develop an appreciation of the factors that persons performing the role must consider.     

论运动和营养

不良的饮食习惯和缺乏活动的现代化生活方式 ,引起了各种疾病和特殊病的发生。诸如 ,肥胖症、慢性腰部劳损、高血压、腹部肌肉衰弱和容易罹患的心血管疾病。本文概要地论述关于人体健康的两个方面———运动和营养。     

Neighborhood change within the Canadian ethnic mosaic, 1986–1991

This paper examines the neighborhoodpatterns in three major Canadian metropolitan areasbetween 1986 and 1991. Data are obtained from 1986 and1991 profile census files and two Special Tabulationsof 1986 and 1991 Canadian census. The data indicatethat the first pathway of neighborhood change is thediversification that takes place among charter-onlyneighborhoods with the introduction of a sizableEuropean presence, followed by Asians and then blacks. The second pathway featuring racial uniformityprimarily takes place in multi-ethnic neighborhoodscontaining one or more visible minority groups. Multivariate analysis suggests that the increase inracial and ethnic diversity in neighborhoods isrelated to the efforts of visible minorities,especially Asians, seeking out neighborhoods withEuropeans.     

氧化石墨的合成及其结构研究

在Hummer法的基础上合成了氧化石墨、对氧化石墨的组成、分子结构及其还原性进行了测试与分析,结果表明,氧化石墨结构中含有大量的极性基因,这些基因的存在赋予了氧化石墨在极性溶剂中有良好的溶剂化能力。     

What are you thinking? Acculturation as an activating event for negative evaluative beliefs among Latinos/as

Negative evaluative beliefs and other cognitive structures have been tied to psychological distress across various populations but have not been sufficiently incorporated into acculturation models. The current study examines the relationships between acculturation and various activating events and mediating sources of support related to negative evaluative beliefs among people of Mexican descent (N = 319). Overall, model variables explained 26% of the variance in negative evaluative beliefs. Acculturation, marital commitment, and social capital associated with friends were negatively related to negative evaluative beliefs. Conversely, single relationship status, marital reward value, psychosocial stressors, and bridging social capital were positively related, and likely serve as activating events for negative evaluative beliefs. Identifying mechanisms related to psychological distress as well as supportive structures may help in constructing interventions that will address the specific needs of different groups. Future research should continue to explore appraisal and associated beliefs in acculturation models to understand why acculturative experiences may become stressful.     

Impact of mindful self-care and perceived stress on the health related quality of life among young-adult students in West Virginia

ABSTRACT

There are substantial gaps in research on Health Related Quality of Life (HRQoL) in students aged 18 and above in West Virginia. The purpose of this study is to explore the associations between mindful self-care, perceived stress, and the HRQoL in this population. We conducted a cross-sectional study between March and April 2017. We included participants who were students, aged 18 years and above, living in West Virginia and were able to answer online questions in English. Data was obtained from an online survey using a structured questionnaire, including the SF12v2®, mindful self-care scale- SHORT, and Perceived Stress Scale (PSS)-10. We applied linear regressions to determine the predictors of HRQoL (physical health and mental health) using SF12v2®. 194 participants met the inclusion criteria of the study. Mindful self-care was negatively associated with perceived stress. Better mindful self-care mediated the relationship between perceived stress and psychological well-being, controlling for gender, age, race, marital status, education level, annual household income, and chronic disease status. Perceived stress and mindful self-care were not related to the physical well-being. Better mindful self-care may safeguard against perceived stress among students aged 18 years and above. Our findings in this study recommend more mindfulness-based interventions targeted to this subpopulation to improve psychological well-being.