Developmental changes in the relationship between magnitude acuities and mathematical achievement in elementary school children

The present study examined the developmental change in number and length acuities and their respective relationship with achievement in various domains of mathematics in second vs. fourth graders. Length acuity was measured with a comparison task, in which participants were asked to choose the longer between a pair of lines. Number acuity was measured with a comparison task, in which the participants were asked to choose the more numerous between a pair of dot arrays. Within each grade, length acuity was more precise compared to number acuity. Number acuity was higher in fourth compared to second grade, but length acuity did not differ between grades manifesting a ceiling effect. In second grade, only length acuity was correlated with overall math achievement, especially Geometry and Arithmetic. In fourth grade, only number acuity was correlated with overall mathematical achievement, especially Number Concept and Applied Problems. Taken together, the present study demonstrates that the relationship between magnitude acuities and math achievement dynamically change over the course of elementary school years and that the strength of this relationship may depend on the type of magnitude and the domain of mathematics.     

English-medium teaching in Korean higher education: policy debates and reality

This study critically examined the effectiveness of English medium instruction (EMI) policy within the context of Korean higher education, putting a special focus on its implementation strategy. The data for this study were mainly drawn from student opinion surveys and focus group interviews conducted by the CTL (Center for Teaching and Learning) at KU. The research teams also carried out supplementary interviews with both professors and students. The results indicate that, although the EMI policy seems to have produced, in general, positive outcomes (i.e., with the overall satisfaction level with EMI or its overall effectiveness in improving students’ English proficiency), the compulsory enforcement of EMI without regard to students’/instructors’ language proficiency, the lack of a much-needed support system and appropriate instructors to conduct EMI classes, and the unilateral implementation of EMI across academic disciplines have brought about a number of side effects. Based on these findings, the study recommends for future EMI policy implementation (1) a more flexible approach, considering students’ language proficiency and career plans and the characteristics of various academic disciplines and (2) more thorough preparation to implement the EMI policy (i.e., examination of the human and financial resources available for the institution concerned).     

A typology of undergraduate students' conceptions of size and scale: Identifying and characterizing conceptual variation

The importance of “size and scale” in nanoscience and engineering has been recognized by both scientists and science educators. A solid understanding of this concept is key to the learning of nanoscience. Students, however, have been reported to have considerable difficulty grasping this concept; yet little is known regarding their state of understanding. To address this knowledge gap, we conducted a series of studies that were aimed at exploring the different ways students conceive of “size and scale” in the context of undergraduate nanoscience and engineering courses. Informed by Variation Theory of Learning (Marton and Booth, 1997), we identified four major categories (with two sub‐categories within each) of student conception—fragmented, linear, proportional, and logarithmic. These conception categories, together with the aspects of variation that characterize and distinguish them, are summarized in a typology. In addition to serving as a diagnostic tool to describe students' understanding, this typology can also be used to guide the development of instructional interventions that facilitate students to move toward a more sophisticated understanding of “size and scale.” © 2011 Wiley Periodicals, Inc., Inc. J Res Sci Teach 48: 512–533, 2011     

Returning to school for higher returns

On the basis of those respondents in the National Longitudinal Survey of Youth (NLSY) who change jobs with an intervening period of education reinvestment, the conventional assumption of linearity of log wages in years of schooling is strongly rejected: a typical reinvestment for the 1980 through 1993 period is associated with a rise of about 3.5 percentage points in the estimated return to an additional year of schooling. The estimated marginal rate of return generally rises in the former education level, and reaches the maximum at 15 years of the former level (therefore 16 years of education after reinvestment), where an additional year of investment is associated with a rise in real hourly rate of pay by approximately 20%. Evidence also shows that, while the level of individuals’ risk tolerance affects significantly the probability of returning to school, correcting for sample selectivity makes little difference in the results. Findings in the current paper survive a variety of robustness tests. The current cohort-based evidence is more helpful than existing evidence from cross-sectional data to individuals making schooling decisions.     

Click-based evidence for decaying weight distributions in search effectiveness metrics

Search effectiveness metrics are used to evaluate the quality of the answer lists returned by search services, usually based on a set of relevance judgments. One plausible way of calculating an effectiveness score for a system run is to compute the inner-product of the run’s relevance vector and a “utility” vector, where the ith element in the utility vector represents the relative benefit obtained by the user of the system if they encounter a relevant document at depth i in the ranking. This paper uses such a framework to examine the user behavior patterns—and hence utility weightings—that can be inferred from a web query log. We describe a process for extrapolating user observations from query log clickthroughs, and employ this user model to measure the quality of effectiveness weighting distributions. Our results show that for measures with static distributions (that is, utility weighting schemes for which the weight vector is independent of the relevance vector), the geometric weighting model employed in the rank-biased precision effectiveness metric offers the closest fit to the user observation model. In addition, using past TREC data as to indicate likelihood of relevance, we also show that the distributions employed in the BPref and MRR metrics are the best fit out of the measures for which static distributions do not exist.     

Noninvasive geotechnical site investigation for stability of Cheomseongdae

Architectural heritages are exposed to natural and man-made disasters so that the need for research to prevent disasters has arisen. Cheomseongdae, known as the oldest astronomical observatory in East Asia, displays separation between the members and is tilted to the north-northeast. To diagnose the present conditions and to resolve problems, site investigations are performed. Boring is conducted in the surrounding ground of Cheomseongdae, and noninvasive investigations such as seismic tests and electrical resistivity surveys are conducted as well. The present study proposes a geotechnical engineering approach focused on noninvasive site surveys, and through this, relates current tilted condition of structure and provides information on the stability of Cheomseongdae.     

Reductive surface synthesis of gold nanoparticles on silicate glass and their biochemical sensor applications

Gold nanoparticles (Au NPs) were directly synthesized on the surface of polyvinylsilazane (PVSZ, -[(vinyl)SiH-NH₂]-) without use of extra reductive additives. The reductive Si-H functional groups on the surface of cured PVSZ acted as surface bound reducing agents to form gold metal when contacted with an aqueous Au precursor (HAuCl₄) solution, leading to formation of Au NPs adhered to silicate glass surface. The Au NPs-silicate platforms were preliminarily tested to detect Rhodamine B (1 μM) by surface enhanced Raman scattering. Furthermore, gold microelectrode obtained by post-chemical plating was used as an integrated amperometric detection element in the polydimethylsilane-glass hybrid microfluidic chip.