煤粉炉烟气中汞浓度测试和分布

参照美国标准实验方法(ASTM)中关于汞的OHM等速取样和化学分析法,结合汞的SCEM在线测量技术,利用一多功能流动实验室,对一满负荷运行的100 MW煤粉锅炉尾部烟气系统进行了单质汞、氧化态汞和颗粒态汞的现场测试和分析.得到了空气预热器、静电除尘器前后烟气中气态、固态和烟气中总汞的浓度及其分布.结果表明烟气中气态总汞的浓度随温度的降低发生着氧化态汞向颗粒汞的转化.在ESP之后的清洁烟气中,OHM和SCEM方法的测试结果吻合较好;在含颗粒浓度较高的烟气中,2种方法存在较大的偏差,原因在于OHM取样过滤器中形成一定厚度的飞灰.该飞灰颗粒对烟气中气态汞有吸附作用并形成颗粒汞.     

Does Mathematics Remediation Work?: A Comparative Analysis of Academic Attainment among Community College Students

Postsecondary remediation is a controversial topic. On one hand, it fills an important and sizeable niche in higher education. On the other hand, critics argue that it wastes tax dollars, diminishes academic standards, and demoralizes faculty. Yet, despite the ongoing debate, few comprehensive, large-scale, multi-institutional evaluations of remedial programs have been published in recent memory. The study presented here constitutes a step forward in rectifying this deficit in the literature, with particular attention to testing the efficacy of remedial math programs. In this study, I use hierarchical multinomial logistic regression to analyze data that address a population of 85,894 freshmen, enrolled in 107 community colleges, for the purpose of comparing the long-term academic outcomes of students who remediate successfully (achieve college-level math skill) with those of students who achieve college-level math skill without remedial assistance. I find that these two groups of students experience comparable outcomes, which indicates that remedial math programs are highly effective at resolving skill deficiencies.

Recognising the needs of gender-variant children and their parents

Gender variance confronts widely held assumptions that children born as males will act like ‘boys’ and children born as females will act like ‘girls’. This imposed binary has the effect of perpetuating negativity towards people who express themselves with gendered variations in attire, behaviour or preferences. Despite the existence of gender-variant individuals in every culture and throughout time, many people are unaware that diversity in gender expression and sexual formation is a naturally occurring phenomenon. This qualitative study aimed to establish the needs of gender-variant children and their parents in order to inform education programmes, policies and clinical approaches to gender variance. Three Internet surveys were conducted to explore the experiences of parents raising gender-variant children, the childhood experiences of transgender adults and the views of professionals who work with the transgender community. The needs of gender-variant children emerged in terms of the need for information, peer contact, personal gender expression, safety, and to be heard and accepted by their parents. The most common needs for parents were for information (stories from other parents, research and guidelines; peer support) and educational resources for schools, professionals and local communities. The paper provides comparisons between the three participant groups and recommendations for future research.     

Real or fake? Resources for teaching college students how to identify fake news

Abstract

Fake news has captured the world’s attention. Educational survey research has highlighted the difficulties students and adults have in determining how to identify valid sources. Psychology can help us to understand why it is difficult to distinguish fact from fiction. The authors describe how to identify fake news from digital sources and ways faculty and librarians can teach information literacy skills using the Association of College and Research Libraries (ACRL) Framework, websites, LibGuides, worksheets, and other resources shared in the extensive appendix.     

Acute effects of walking on inflammatory and cardiovascular risk in sedentary post-menopausal women

Abstract

Biochemical markers of inflammation are emerging as new predictors of risk of cardiovascular disease (CVD) and may alter acutely with exercise. Few studies have been conducted on the effects of walking on these markers or whether different walking intensities elicit varied effects. As there is growing interest in modifiable lifestyle factors such as walking to reduce CVD risk, these inflammatory responses warrant investigation. The aim of this study was to compare the effects of walking at 50% versus 70% of predicted maximal heart rate on C-reactive protein (CRP), plasma fibrinogen, and trigylcerides in sedentary post-menopausal women. Twelve post-menopausal women (mean age 58 years, s ± 6; stature 1.62 m, s ± 0.06; body mass 66.8 kg, s ± 6.2) completed two 30-min treadmill walks in a randomized cross-over design. Fasted blood samples were taken (for the determination of plasma fibrinogen, CRP, and lipids) before, immediately after, and 1 and 24 h after exercise. Triglyceride concentrations decreased from pre-exercise to 24 h post exercise at both walking intensities (time×group interaction, P < 0.05). No significant effects were observed for plasma fibrinogen, CRP, total cholesterol, low-density or high-density lipoprotein cholesterol (time x group interaction, P > 0.05). The results of this study suggest that fasting plasma triglycerides are decreased on the morning after 30 min of brisk walking at either 50% or 70% of maximal heart rate (moderate and vigorous intensity).     

Student Flow Between Community Colleges: Investigating Lateral Transfer

The traditional unidirectional (“linear”) postsecondary path from high school to a community college to a 4-year institution into the workforce represents accurately a decreasing proportion of the pathways actually taken by students through higher education. Instead, students increasingly exhibit patterns of enrollment that take them through multiple postsecondary institutions, both within levels of the higher education system (e.g., multiple community colleges, multiple 4-year institutions) and across levels (e.g., movement back and forth between community colleges and 4-year institutions). These “swirling” patterns of enrollment are widely recognized by scholars of higher education, but they remain poorly understood. In this study, I employ data that address 89,057 first-time students in the California community college system to answer a number of key questions concerning lateral transfer between community colleges, which, according to prior research, constitutes one sizeable component of student “swirl”. Building on the very limited work on this topic, I examine whether the reported high prevalence of lateral transfer holds true under a more stringent operational framework than that employed in prior work. I explore whether lateral transfer is primarily an artifact of students enrolling simultaneously in multiple community colleges, sometimes called “double-dipping”. I investigate the timing of lateral transfer from several different perspectives to determine how lateral transfer fits in students’ progress and development. Finally, I probe the relationship between students’ level of academic investment in their current community college and the risk of lateral transfer.     

Electronic Versus Print Textbooks: The Influence of Textbook Format on University Students’ Self-Regulated Learning Strategies,Motivation, and Text Anxiety

Because a majority of university students do not regularly read course textbooks, a study was conducted to determine if portable electronic textbooks (e-textbooks) would increase university student motivation to read by enhancing cognitive learning strategies and self-regulation of learning. The participants included 538 university students who self-chose to use either a print or e-textbook throughout the semester. The dependent variables self-efficacy, intrinsic value, cognitive strategies, self-regulation, and text anxiety were measured in each of two groups of participants using the Technology Confidences and Attitudes scale and the Motivated Strategies for Learning Questionnaire (MSLQ). The results of a multivariate analysis of variance (MANOVA) analysis indicated that there was a significant difference in the students’ MSLQ scores based on their choice of textbook format. These results imply that students who use e-textbooks are more likely to use cognitive and self-regulation strategies than students who use traditional print textbooks in their courses.     

The fourth R: Reasoning

This study examined the self‐concept of a small group of academically gifted adolescents in New Zealand, with the aim of exploring gender differences. Using the Tennessee Self‐Concept Scale: 2, a sample of 40 male and female 15–18 year old students participated. Results indicated gender differences: males scored higher than females on most dimensions with the exception of Self‐Criticism, Moral Self‐Concept, and Inconsistent Responding. Additionally, the mean score was higher for males than females. Results indicate gender differences do occur in some New Zealand gifted adolescents and warrant the need for further research in this area.