旧成都的街头饮食业

同其他艺术一样,烹调也有“阳春白雪”与“下里巴人”之分。风靡海外、引得外国饕餮们交口称赞的川菜就多属于前一类。有这些正宗川味陈于席,自然于口腹、于气氛皆一大乐事。然而,“阳春白雪”不免“曲高和寡”。细究之,此类肴馔多出于声名遐迩如“姑姑筵”、“荣乐园”等名门的嫡传高手,其选材、配料、制作均十分考究。故就是现在国内,除了节庆盛典,也不是一般人能够经常享用的;在新中国成立前,“磨骨头养肠子”的人就更不敢问津了。     

Support for self-regulation in learning complex topics from multimedia explanations: do learners need extensive or minimal support?

Acquiring complex conceptual knowledge requires learners to self-regulate their learning by planning, monitoring, and adjusting the process but they find it difficult to do so. In one experiment, we examined whether learners need broad systems of support for self-regulation or whether they are also able to learn with more economical support configurations. Eighty-six undergraduate students with little prior domain knowledge learned plate tectonics from a multimedia presentation involving animation with concurrent narration and support in one of four forms: minimal support, two variants of intermediate support, or extensive support. After the presentation, participants solved retention and transfer tests. The results revealed that participants receiving the broadest system of support outperformed those in the other conditions, which did not differ from one another. This means that it is so difficult for learners to self-regulate learning that they need considerable support if they are to learn complex conceptual knowledge.     

广州市海珠区疑似麻疹血清抗体检测结果分析

目的:根据广州市海珠区2007-2011年麻疹血清抗体检测结果,分析麻疹发病的性别、年龄与季节分布。方法:采用酶联免疫吸附试验(ELISA)检测麻疹IgM抗体,整理总结历年检测结果。结果:2007-2011年共收集到疑似病例血清409例,IgM抗体阳性病例153例,阳性率37.41%。春季阳性率高(40.53%),IgM抗体阳性年龄为3个月-40岁,8个月龄组阳性率最高(56.86%)。结论:麻疹IgM抗体的检测是快速确诊病例主要方法之一,冬春季仍是麻疹发病的高峰时段,1岁以下儿童是高发人群。     

Correlation between variables subject to an order restriction,with application to scientometric indices

Variables subject to an order restriction, for instance Y ≤ X, have a bivariate distribution over a non-rectangular joint domain that entails a non-null and potentially large structural relation even if the variables show no association (in the sense that particular ranges of values of X do not co-occur with particular ranges of values of Y). Order restrictions affect a number of scientometric indices (including the h index and its variants) that are routinely subjected to correlational analyses to assess whether they provide redundant information, but these correlations are contaminated by the structural relation. This paper proposes an alternative definition of association between variables subject to an order restriction that eliminates their structural relation and reverts to the conventional definition when applied to variables that are not subject to order restrictions. This alternative definition is illustrated in a number of theoretical cases and it is also applied to empirical data involving scientometric indices subject to an order restriction. A test statistic is also derived which allows testing for the significance of an association between variables subject to an order restriction.     

Problem posing based on investigation activities by university students

This paper reports a classroom-based study involving investigation activities in a university numerical analysis course. The study aims to analyse students' mathematical processes and to understand how these activities provide opportunities for problem posing. The investigations were intended to stimulate students in asking questions, to trigger their thinking processes, to promote their ability to investigate and to support them in learning numerical analysis' concepts and procedures. The results show that the investigations provided opportunities for students to experience mathematical processes, including posing questions, formulating and testing conjectures and, to some extent, proving results. They also provide some understanding about the role of problem posing in these processes. Posing questions occurred mainly in an implicit way, in the interpretation of tasks and in identifying regularities, analysing graphs and testing cases. The conjectures were often based on pattern identification or data manipulation, and the students tended to accept them without testing or proving. The students also proposed alternative formulations for the initial questions and posed new problems from their explorations and attempts to refine previous conjectures.     

How Persuasive Are Health Advertisements in First-Person Shooter Games? Exploring Knowledge-Activation and Thought-Disruption Mechanisms

This study examined whether persuasive health messages embedded in shooter games have broad or targeted effects on players’ willingness to engage in risk behaviors (N = 145). Participants presented with in-game health messages discouraging alcohol-impaired driving of motor vehicles showed reduced willingness to drink alcohol and to operate both motor and nonmotor vehicles, compared to those in a no-message gaming control condition. There were no spillover effects on willingness to smoke cigarettes or marijuana, thus implying targeted persuasive effects. In addition, players experiencing high instead of low cognitive load showed decreased postexperiment willingness to drink and operate nonmotor vehicles, thus suggesting that playing a game under high cognitive load can influence players’ attitudes. The findings replicate previous research and further expand on knowledge-activation and thought-disruption mechanisms underlying the persuasiveness of health messages.