The optimum clustering framework: implementing the cluster hypothesis

Document clustering offers the potential of supporting users in interactive retrieval, especially when users have problems in specifying their information need precisely. In this paper, we present a theoretic foundation for optimum document clustering. Key idea is to base cluster analysis and evalutation on a set of queries, by defining documents as being similar if they are relevant to the same queries. Three components are essential within our optimum clustering framework, OCF: (1) a set of queries, (2) a probabilistic retrieval method, and (3) a document similarity metric. After introducing an appropriate validity measure, we define optimum clustering with respect to the estimates of the relevance probability for the query-document pairs under consideration. Moreover, we show that well-known clustering methods are implicitly based on the three components, but that they use heuristic design decisions for some of them. We argue that with our framework more targeted research for developing better document clustering methods becomes possible. Experimental results demonstrate the potential of our considerations.     

Cross-cultural Study of Understanding of Scale and Measurement: Does the everyday use of US customary units disadvantage US students?

Quantitative and qualitative studies of various aspects of the perception of biotechnology were conducted among 469 Slovenian high school students of average age 17 years. Our research aimed to explore relationships among students' pre-knowledge of molecular and human genetics, and their attitudes to four specific biotechnological applications. These applications—Bt corn, genetically modified (GM) salmon, somatic and germ line gene therapy (GT)—were investigated from the viewpoints of usefulness, moral acceptance and risk perception. In addition, patterns and quality of moral reasoning related to the biotechnological applications from the aspect of moral acceptability were examined. Clear gender differences were found regarding the relationship between our students' pre-knowledge of genetics and their attitudes to biotechnological applications. While females with a better genetics background expressed a higher risk perception in the case of GM salmon, their similarly well-educated male colleagues emphasized the risk associated with the use of germ line GT. With all four biotechnological applications, patterns of both rationalistic—deontological and teleological—and intuitive moral reasoning were identified. Students with poorer genetics pre-knowledge applied an intuitive pattern of moral reasoning more frequently than their peers with better pre-knowledge. A pattern of emotive reasoning was detected only in the case of GM salmon. A relatively low quality of students' moral reasoning, as demonstrated by their brief and small number of supporting justifications (explanations), show that there is a strong need for practising skills of argumentation about socio-scientific issues in Slovenian high schools on a much larger scale. The implications for future research and classroom applications are discussed.     

Influence of Three Different Methods of Teaching Physics on the Gain in Students' Development of Reasoning

The Lawson Classroom Test of Scientific Reasoning (LCTSR) was used to gauge the relative effectiveness of three different methods of pedagogy, Reading, Presenting, and Questioning (RPQ), Experimenting and Discussion (ED), and Traditional Methods (TM), on increasing students' level of scientific thinking. The data of a one-semester-long senior high-school project indicate that, for the LCTSR: (a) the RPQ group (n?=?91) achieved effect-sizes d?=?0.30 and (b) the ED group (n = 85) attained effect-sizes d?=?0.64. These methods have shown that the Piagetian and Vygotskian visions on learning and teaching can go hand in hand and as such achieve respectable results. To do so, it is important to challenge the students and thus encourage the shift towards higher levels of reasoning. This aim is facilitated through class management which recognizes the importance of collaborative learning. Carrying out Vygotsky's original intention to use teaching to promote cognitive development as well as subject concepts, this research has shown that it is better to have students experience cognitive conflict from directly observed experiments than by reflecting on reported experience from popularization papers or writings found on the internet.     

Modelling activities integrating construction and simulation supported explanatory and evaluative reasoning

ABSTRACT

Model-based instruction offers numerous benefits to students, including increased content knowledge and critical thinking. This study explored the differences in the knowledge outcomes and reasoning processes employed by undergraduate students in an introductory biology lab as they constructed, revised, and simulated a computational model of a prokaryotic gene regulatory system. We analysed post-lesson conceptual models (n?=?335) and audio-recorded small group discussions (n?=?10) of students that either constructed and revised a computational model and then investigated a pre-constructed computational model or only investigated a pre-constructed computational model to determine the impact of constructing and revising a computational model. No significant differences were found between the mental models of students who constructed and revised a computational model and those who only simulated a pre-constructed computational model. However, this study demonstrated that constructing and revising a model before simulating it offered additional benefits to students by fostering deeper cognitive reasoning processes. Constructing and revising a model elicited more explanatory and evaluative reasoning and prompted students to discuss the underlying mechanisms of the biological system.     

The Influence of 16‐year‐old Students’ Gender,Mental Abilities,and Motivation on their Reading and Drawing Submicrorepresentations Achievements

Submicrorepresentations (SMRs) are a powerful tool for identifying misconceptions of chemical concepts and for generating proper mental models of chemical phenomena in students’ long‐term memory during chemical education. The main purpose of the study was to determine which independent variables (gender, formal reasoning abilities, visualization abilities, and intrinsic motivation for learning chemistry) have the maximum influence on students’ reading and drawing SMRs. A total of 386 secondary school students (aged 16.3 years) participated in the study. The instruments used in the study were: test of Chemical Knowledge, Test of Logical Thinking, two tests of visualization abilities Patterns and Rotations, and questionnaire on Intrinsic Motivation for Learning Science. The results show moderate, but statistically significant correlations between students’ intrinsic motivation, formal reasoning abilities and chemical knowledge at submicroscopic level based on reading and drawing SMRs. Visualization abilities are not statistically significantly correlated with students’ success on items that comprise reading or drawing SMRs. It can be also concluded that there is a statistically significant difference between male and female students in solving problems that include reading or drawing SMRs. Based on these statistical results and content analysis of the sample problems, several educational strategies can be implemented for students to develop adequate mental models of chemical concepts on all three levels of representations.     

The overall knowledge of genetics in Serbian speech and language pathologists

ABSTRACT

An increase in the number of children with speech–language pathology also having a genetic disorder imposes the need for speech and language pathologists (SLPs) to have sufficient knowledge about genetic basis of speech–language disorders. Research aim was to estimate in Serbian SLPs different aspects of theoretical and practical knowledge about intercorrelation of genetics and speech and language pathology and to compare obtained results with the results of SLPs in the United States. The questionnaire from Tramontana’s study was used in our study. Comparison of the results that obtained in our study with those in Tramontana’s study has shown that our study respondents have higher General Knowledge Index (78.6%: 66.2%), higher mean confidence summary score (22.2: 16.7) and higher mean score of ‘overall’ attitudes about genetics and its relation with communication disorders (20.8: 13.6). Differences which emerge from educational programmes, educational levels and practical experience in the observed groups are indicated as possible causes of differences in the obtained results. On the basis of the obtained results, it may be concluded that it is necessary to elevate SLPs’ level of general knowledge about genetics and to acquire their knowledge through clinical practice.     

A comparative study of variations in arithmetic fluency between Norwegian and Finnish third graders

ABSTRACT

The study aimed to investigate variations in addition and subtraction fluency by observing grade three students in Norway (n = 253, M_age = 8.38 y.) and Finland (n = 209, M_age = 9.35 y.) while controlling for their age and non-verbal reasoning. Gender differences were also examined. The focus of the study was on the performance of the low-achieving (LA) students in comparison to the typically achieving (TA) group, not neglecting differences in how early educational support was organised across the two countries. Two-minute speed tests in both addition and subtraction within the 1–20 number range were used to assess fluency. The Finnish students outperformed students in the Norwegian sample both in addition and subtraction fluency. There were more Norwegian students in the LA group (i.e. performance at or below the 25th percentile) in both addition (37.9% vs. 20.1%) and subtraction (39.1% vs. 15.8%). In comparison to the TA students, the LA students made more errors and skipped over more arithmetic tasks in an attempt to solve them. Observed differences are discussed in relation to both country characteristics concerning early mathematics education and early educational support.     

Numerical investigation of the power generation of a ducted composite material marine current turbine

In the hostile and highly corrosive marine environment,advanced composite materials can be used in marine current turbines due to their high strength-to-weight ratios and excellent resistance to corrosion.A composite material marine current turbine(CMMCT),which has significant advantages over traditional designs,has been developed and investigated numerically.A substantial improvement in turbine performance is achieved by placement of a duct to concentrate the energy.Computational fluid dynamics(CFD) results show that the extracted power of a ducted CMMCT can be three to four times the power extracted by a bare turbine of the same turbine area.The results provide an insight into the hydrodynamic design and operation of a CMMCT used to shorten the design period and improve technical performance.     

The identification of teasing among students as an indispensable step towards reducing verbal aggression in schools

Surveys have confirmed the ubiquity of aggression in schools, and verbal aggression is not an exception. The identification of teasing as a frequent form of verbal aggression is an indispensable step towards diminishing it. The purpose of this study was to investigate teasing among primary school students in Slovenia. The research showed that teasing is common in schools: the most usual forms of teasing refer to the students’ appearance, and the victims mostly report negative feelings after being teased. Most teasing was done to reciprocate, and the most frequent response to teasing was a verbal comeback. The research revealed some differences in teasing between students by sex and age and offers some useful implications for practice.     

财政，政策与工业动力——电影产业中合拍现象的涌现

本文对电影产业中日渐增多的跨国合作拍摄现象进行了探讨。我们认为，金融创新与制度创新造就了电影工业中的产业组织，合拍的出现则是它的延展。本文将电影金融作为风险分配机制的中心，依次讨论了合拍过程中政策支持、税收竞争增强、筹资与资金大量涌入等变化，是如何逐渐地提升电影产业发展的驱动力。