Monthly Archives: January 2017

Comparing student performance

Elementary school students scored marginally higher on the computer-based exam that allowed them to go back to previous answers than on the paper-based exam, while there was no significant difference for middle school students on those two types of tests.

In contrast, high school students showed no difference in their performance on the three types of tests. Likewise, previous research has found that the option to skip, review, and change previous responses also had no effect on the test results of college students.

For the study, tests were given to students in grades 4-12 that assessed their understanding of energy through three testing systems. Instructors elected to administer either the paper-and-pencil test (PPT) or one of two computer-based tests (CBT) based on the availability of computers in their classrooms.

One CBT (using TAO, an open source online testing system) allowed students to skip items and freely move through the test, while the other CBT (using the AAAS assessment website) did not allow students to return to previous test items. In addition, on the TAO test, answers were selected by directly clicking on the text corresponding to an answer. On the AAAS exam, answers were chosen more indirectly, by clicking on a letter (A, B, C, or D) at the bottom of the screen corresponding with an answer.

Gender was found to have little influence on a student’s performance on PPT or CBT; however, students whose primary language was not English had lower performances on both CBTs compared to the PPT. The cause for the difference depending on primary language was unclear, but could have been linguistic challenges that the online environment presented or limits on opportunities to use computers in non-English-speaking environments.

Overall, the study results, along with previous research, indicate that being able to skip, review, and change previous responses could be beneficial for younger children in elementary and middle school but have no influence on older students in high school and college.

Furthermore, results indicated that marking an answer in a different location on a multiple-choice test could be challenging for younger students, students with poor organizational skills, students who have difficulties with concentration, or students who are physically impaired. In addition, having to match an answer to a corresponding letter at the bottom of the screen likely adds an additional level of complexity and cognitive processing.

The researchers note that additional study of CBT answer-choice selection and test navigation features and how they influence elementary and middle school students’ test performance is warranted.

The study was supported by a grant from the Institute of Education Sciences.

Electronic healthcare systems

Information security and protection of privacy are some of the most important factors in the development of high-quality tools in the healthcare sector. If no attention is paid to these aspects, there is substantial risk that individuals may come to harm in healthcare situations. Leonardo Iwaya, PhD student in computer science at Karlstad University, explores ways of securing information and protecting privacy when using mobile applications in healthcare (mHealth).

“Mobile apps are for example used in developing countries to increase the coverage and the access to public healthcare,” says Leonardo Iwaya. “But many projects fail because issues related to data security and privacy cannot be successfully integrated in the systems.”

For instance, in Brazil, mHealth tools have been used by community health workers to improve patients’ treatment in poor and rural areas, strengthening the link between the society and the public health system. These patients often have limited possibilities to visit healthcare clinics and the project instead involved healthcare workers visiting patients at home. Smartphones are, for example, used to streamline the handling of journals. Information gathered during a visit is also used to analyse the impact of the conditions in the specific areas on people’s health, so that more prevention work can be done.

“My part in the project has been to look at how systems are designed and data is processed with respect to data protection and privacy,” says Leonardo Iwaya. “These issues have to be considered from the start if you want to develop digital healthcare systems in which information is properly secured and privacy is protected.”

Spans drop when online ads pop up

Rejer and Jankowski’s direct, objective and real-time approach extends current research about the effect of intrusive marketing on internet users. So far, most studies on this topic have been subjective in nature, and have typically analysed only the impact of online advertisements on brand awareness and memory. Other researchers have investigated web users’ visual attention, recorded their behaviour, or relied heavily on subjective information provided in questionnaires.

In Rejer and Jankowski’s experiment five Polish men and one woman, between 20 and 25 years years of age, were instructed to read ten short pages of text on a computer screen, after which they had to answer questions about the content. During the reading process, their attention was distracted when online advertisements randomly appeared on screen. The brain activity of each participant was measured using an electroencephalogram (EEG). The researchers did not only take note of each participant’s brain signal patterns, but also analysed how consistent these were across the different trials, and how they correlated with those of others.

Two main effects were observed for most subjects. First, the presence of online advertisements influenced participants’ concentration. This was deduced from the significant drop in beta activity that was observed in the frontal/prefrontal cortical areas. According to the researchers, this could indicate that the presentation of the advertisement induced a drop in concentration levels.

Secondly, the appearance of the advertisement induced changes in the frontal/prefrontal asymmetry index. However, the direction of this change differed among subjects, in that for some it dipped, and for others it increased.

The researchers believe that the participants’ response to the advertisement might be influenced by their so-called motivation predisposition. “If the subject is more ‘approach’ oriented, the changes in the asymmetry index might reflect growing activity in the left brain hemisphere. If, on the other hand, the subject is more ‘withdraw’ oriented, these changes might reflect the growing activity in the right hemisphere,” explains Rejer, who also notes that this is only a hypothesis that should be tested in future work on the intrusive nature of different forms of online advertisements.

A new route to molecular wires

As conventional silicon-integrated circuits reach their lower size limit, new concepts are required such as molecular electronics — the use of electronic components comprised of molecular building blocks. Shuo-Wang Yang at A*STAR Institute of High Performance Computing together with his colleagues and collaborators, are using computer modeling to design electric wires made of polymer chains.

“It has been a long-standing goal to make conductive molecular wires on traditional semiconductor or insulator substrates to satisfy the ongoing demand miniaturization in electronic devices,” explains Yang.

Progress has been delayed in identifying molecules that both conduct electricity and bind to substrates. “Structures with functional groups that facilitate strong surface adsorption typically exhibit poor electrical conductivity, because charge carriers tend to localize at these groups,” he adds.

Yang’s team applied density functional theory to a two-step approach for synthesizing linear polymer chains on a silicon surface. “This theory is the best simulation method for uncovering the mechanism behind chemical reactions at atomic and electronic levels. It can be used to predict the reaction pathways to guide researchers,” says Yang.

The first step is the self-assembled growth of single monomers on to the silicon surface. Yang’s team studied several potential monomers including, most recently, a thiophene substituted alkene and a symmetrical benzene ring with three alkynes attached. The second step is the polymerization of the tethered monomers by adding a radical to the system.

According to the calculations, these tethered polymers are semiconductors in their natural state. “We introduced some holes, such as atomic defects, to the wires to shift the Fermi levels and make them conductive,” Yang explains.

The team then studied the electron band structures of each component before and after tethering and polymerization; finding little charge transfer between the molecular wires and the silicon surfaces. “The surface-grafted polymers and underlying substrates seem independent of each other, which is an ideal model of a conductive molecular wire on a traditional semiconductor substrate,” says Yang.

“Our finding provides a theoretical guide to fabricating ideal molecular wires on traditional semiconducting surfaces,” he adds. The team is plans to extend their work to study 2D analogs of these 1D polymer chains that could work as a metallic layer in molecular electronic devices.

The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing and Institute of Materials Research and Engineering.