A Study of University Students’ Understanding of Simple Electric Circuits Part 2: Batteries,Ohm's Law,Power Dissipated,Resistors in Parallel

RIASSUNTO

In this paper the results of a systematic investigation into university students’ misunderstandings of d.c. simple circuit operations are reported. These results provide evidence of various misconceptions present before and after the teaching at university level of the topics on d.c. circuits: a battery as a source of constant current; the wrong interpretation of the junctional relation expressed by Ohm's law; power dissipated; resistors in parallel. In conclusion, a brief comment is made on the need to make university teachers aware of these results and on the many difficulties encountered in such an attempt.

RIASSUNTO In questo lavoro sono riportati i risultati di una indagine sistematica su comuni forme di ragionamento (errate) che studenti universitari manifestano sul fitn-zionamento di semplici circuiti elettrici. I concetti su cui é stata focalizzata I'attenzione e che sono presenti non solo prima ma anche dopo I'insegnamento a livello universitario sono: la batteria come sorgente di corrente costante, I'errata interpretazione delle relazioni funzionali relative alla legge di Ohm e alia potenza dissipata in un circuito, il collegamento di resistenze in parallelo. Segue, infine, un breve commento sulla necessityá di rendere consapevoli i docenti universitari di tali risultati e delle difficolta incontrate in tale tentativo.     

思想政治教育的耗散结构分析

论文分析了耗散结构理论与思想政治教育之间的一致性,在此基础上,把耗散结构理论的基本原理具体运用于思想政治教育中,提出了运用耗散结构理论进行思想政治教育工作的设想和建议。     

无水乙醇夹带剂超临界CO2萃取荔枝核

以无水乙醇为夹带剂,采用超临界CO2萃取荔枝核,并用气相色谱．质谱联用仪（GC—MS）对荔枝核萃取物的挥发性成分进行了分析．结果表明,以无水乙醇为夹带剂超临界CO2萃取荔枝核的萃取率为5．47％,GC—MS鉴定出32种化合物,主要为甾醇类、萜类、不饱和脂肪酸、棕榈酸、脂肪酸酯、芳香醇,相对质量分数分别为38．8％,26.4％,8．60％,7．54％,8．44％,6．11％．和无夹带剂相比,夹带剂无水乙醇可以提高荔枝核的超临界萃取率．     

脱口秀

小牛多少带有点爆冷嫌疑的夺冠,令现场的情绪瞬间爆棚,马克·库班成了首先的采访对象,接下来,无论是更衣室外的通道,还是新闻发布会的现场,无论是胜利者还是失意人,都得到了宣泄情绪的机会。请相信我,这也许是NBA总决赛历史中最沉重的一次赛后发布会,相比较媒体送给胜利者的歌颂和恭维,失利一方得到的却是一轮又一轮的重磅炸弹,炸得他们体无完肤、无地自容。     

THE SELECTION OF VARIABLES IN MULTIPLE REGRESSION ANALYSIS

4 different procedures are commonly employed with sample data to reduce a set of predictor variables. In the present study these procedures were repeatedly applied to computer-simulated samples to provide comparative data pertaining to two questions: (a) Which procedure can be expected to produce an equation that yields the most accurate predictions for the population? (b) Which procedure is most likely to identify the optimal set of independent variables? The samples were drawn from 12, mathematically defined, multivariate normal populations. Each population consisted of 1 criterion and 10 predictor variables. Five or fewer independent variables constituted the optimal set in each case. With respect to both questions small differences among the procedures were observed. However, the forward selection and stepwise procedures consistently produced more favorable results than the 2 backward elimination procedures. The question of the number of sampling units to use is discussed.     

Modeling,Praise, and Criticism in Teaching Empathic Responding

This study employs a factorial design to investigate the efficacy of all possible combinations of modeling, praise, and criticism as a means of teaching empathic responding to counselor trainees. Measures of empathy were taken on 64 female introductory psychology students at the beginning of an experimental session and following each of two training segments. Results indicate a significant effect for modeling and stage of training. There was a significant interaction between modeling and stage of training such that subjects in the modeling conditions were rated higher in empathy than those in the no-modeling condition at the mid- and postmeasure but not at the premeasure. Results are in agreement with one previously published study but are inconsistent with two others. Discussion focuses on the critical elements of effective feedback techniques.     

史诗《格萨尔》的文化启蒙与教育功能

《格萨尔》作为藏族传统教育的一种重要形式,不仅发挥着传承藏族文化的重要作用,而且也将对藏族现代教育产生深刻影响。文章旨在强调新时期应充分发挥其实际存在的文化启蒙功能和教育作用,批判地吸收《格萨尔》中的积极成份,用以推动藏族社会物质文明和精神文明建设。