The effectiveness of Web search engines for retrieving relevant ecommerce links

Ecommerce is developing into a fast-growing channel for new business, so a strong presence in this domain could prove essential to the success of numerous commercial organizations. However, there is little research examining ecommerce at the individual customer level, particularly on the success of everyday ecommerce searches. This is critical for the continued success of online commerce. The purpose of this research is to evaluate the effectiveness of search engines in the retrieval of relevant ecommerce links. The study examines the effectiveness of five different types of search engines in response to ecommerce queries by comparing the engines’ quality of ecommerce links using topical relevancy ratings. This research employs 100 ecommerce queries, five major search engines, and more than 3540 Web links. The findings indicate that links retrieved using an ecommerce search engine are significantly better than those obtained from most other engines types but do not significantly differ from links obtained from a Web directory service. We discuss the implications for Web system design and ecommerce marketing campaigns.     

随机扩增多态性DNA技术研究发现二氧化钛纳米颗粒对西葫芦具有基因毒性

研究目的：二氧化钛（TiO2）纳米颗粒已经广泛应用于化妆品、防晒霜、涂料和牙膏等。这些纳米颗粒性质非常稳定,能在废水和生物固体中转移和分散。现有研究表明,TiO2纳米颗粒对动物正常生理活动具有毒性等负面作用。但是,它们对植物是否具有毒性特别是是否会产生植物基因毒性至今尚不清楚。因此,本文使用随机扩增多态性DNA技术研究TiO2纳米颗粒是否对西葫芦具有基因毒性,为TiO2纳米颗粒排放进入环境后的潜在植物毒性风险评价提供依据。 创新要点：首次发现了TiO2纳米颗粒对西葫芦具有基因毒性。 重要结论：采用随机扩增多态性DNA技术,发现TiO2纳米颗粒污染处理的西葫芦样品与未处理样品的基因组DNA图谱相比,不仅在谱带强度有明显差异,而且存在谱带消失和新谱带产生现象,表明TiO2纳米颗粒对西葫芦具有基因毒性。     

Discrete-time modeling and control of a boost converter by means of a variational integrator and sliding modes

This work deals with the discrete-time modeling of a boost DC-to-DC power converter by means of a discrete Lagrangian formulation based on the midpoint rule integration method. Then in the basis of this model, a discrete-time sliding mode regulator is designed in order to force the boost circuit to track a DC-biased sinusoidal signal. Simulations and experimental tests are carried on where the great performance of the proposed methodology is verified.     

Perceptions of Video Scenarios to Learn Human Pathophysiology Among Undergraduate Science Students

Pathophysiology describes and explains the physiological dysfunctions that occur in human diseases. Pathophysiology is content heavy, often leading to medical/biomedical science students adopting a surface approach to learning. To encourage more engagement, we developed clinical simulation practical classes using manikin patients. Students considered these were more effective than paper-based case studies. However, they found the first encounter with the manikins daunting. In addition, they did not have a strong sense of responsibility towards the outcome of their treatment choices largely because they recognized this as a simulated experience. Video is a powerful teaching tool to demonstrate situations that are difficult to explain in words, to see theory applied to practice or create enthusiasm and confidence in the viewer regarding the use of new practices. In this study, we evaluated the effectiveness of exposure to a video scenario, in which a high-fidelity manikin was used as the ‘patient’, before the students’ own interactions with the manikin in later classes. Survey results suggested that the students felt more engaged with the case study. They felt the video helped them appreciate aspects of clinical communication and prepare for their time in the simulation laboratory interacting with the manikin. They saw the video as a useful addition to the written case study notes. Their criticisms were mainly around the production quality. This study supports the use of video scenarios as a valuable adjunct to the teaching of pathophysiology to medical/biomedical science students when using either paper- or simulation-based case studies.

     

Analysis of the cognitive unity or rupture between conjecture and proof when learning to prove on a grade 10 trigonometry course

We present results from a classroom-based intervention designed to help a class of grade 10 students (14–15 years old) learn proof while studying trigonometry in a dynamic geometry software environment. We analysed some students’ solutions to conjecture-and-proof problems that let them gain experience in stating conjectures and developing proofs. Grounded on a conception of proof that includes both empirical and deductive mathematical argumentations, we show the trajectories of some students progressing from developing basic empirical proofs towards developing deductive proofs and understanding the role of conjectures and proofs in mathematics. Our analysis of students’ solutions is based on networking Boero et al.’s construct of cognitive unity of theorems, Pedemonte’s structural and referential analysis of conjectures and proofs, and Balacheff and Margolinas’ cK¢ model, while using Toulmin schemes to represent students’ productions. This combination has allowed us to identify several emerging types of cognitive unity/rupture, corresponding to different ways of solving conjecture-and-proof problems. We also show that some types of cognitive unity/rupture seem to induce students to produce deductive proofs, whereas other types seem to induce them to produce empirical proofs.     

Investigating the impact of flexible furniture in the elementary classroom

Learning Environments Research - Educators are beginning to consider the physical learning environment as an additional resource in meeting learning outcomes in modern classrooms. In order to...     

To Freire or not to Freire: Educational freedom and the populist right-wing ‘Escola sem Partido’ movement in Brazil

This article addresses key topics of academic freedom and critical pedagogy during a time of right-wing populist politics. The rise of the far-right politician Jair Bolsonaro to Brazil’s presidency in 2019 was accompanied by a vow to eradicate any vestige of the ideas of Brazilian educator Paulo Freire from the country’s schools. Bolsonaro’s campaign was supported by ultra-conservative groups that have as their core mission a traditional Christian and anti-Communist educational agenda. At the forefront of these groups is the influential and conspicuous ‘Escola sem Partido’ (ESP) movement that has forcefully campaigned against Freire’s critical pedagogy across the country and promoted physical and online abuse of teachers since 2014. This article asks how Freire’s philosophies can be an ally in the struggle for democratic education in the current political climate in Brazil. It employs a method of dialogical narrative to bring Freire’s theories and critical methodology to life and test their potency against the ESP educational philosophies. It initially employs Freire’s core ideas to examine the ESP policies and parliamentary bills. In the second part, it analyses documents and online content produced by civil society resistance to ESP pressures. The findings show the vitality of Freire’s pedagogical philosophy to empower oppressed communities in their demands for quality education. The narrative concludes by demonstrating the vital role of the critical consciousness process and of Freire’s pedagogy of freedom to support ongoing struggles by teachers and communities to block ESP attempts to abolish critical thinking in Brazilian public education.     

A Systematic Approach to Designing,Implementing, and Evaluating Learner-Generated Digital Media (LGDM) Assignments and Its Effect on Self-regulation in Tertiary Science Education

Research in Science Education - This study explored the self-regulation strategies and learning experiences of undergraduate science students completing Learner-Generated Digital Media (LGDM)...     

Difficulties in semantically congruent translation of verbally and symbolically represented algebraic statements

Educational Studies in Mathematics - This paper describes the difficulties faced by a group of middle school students (13- to 15-year-olds) attempting to translate algebraic statements written in...     

Detection of Invalid Test Scores: The Usefulness of Simple Nonparametric Statistics

In recent guidelines for fair educational testing it is advised to check the validity of individual test scores through the use of person‐fit statistics. For practitioners it is unclear on the basis of the existing literature which statistic to use. An overview of relatively simple existing nonparametric approaches to identify atypical response patterns is provided. A simulation study was conducted to compare the different approaches and on the basis of the literature review and the simulation study guidelines for the use of person‐fit approaches are given.