National Institute of Education
National Institute of Education, Singapore: NIE Digital RepositoryNot a member yet
19917 research outputs found
Sort by
A study on T-equivalent graphs
No full textIn his article [J. Comb. Theory Ser. B 16 (1974), 168–174], Tutte called two graphs T-equivalent (i.e., codichromatic) if they have the same Tutte polynomial and showed that graphs G and G' are T-equivalent if G' is obtained from G by flipping a rotor (i.e., replacing it by its mirror) of order at most 5, where a rotor of order k in G is an induced subgraph R having an automorphism ψ with a vertex orbit {ψ (u) : i ≥ 0} of size k such that every vertex of R is only adjacent to vertices in R unless it is in this vertex orbit. In this article, we show the above result due to Tutte can be extended to a rotor R of order if the subgraph of G induced by all those edges of G which are not in R satisfies certain conditions. Also, we provide a new method for generating infinitely many non-isomorphic T-equivalent pairs of graphs.Accepted versionRP 2/22 DF
Extensions of Moon’s and Bagga and Beineke’s theorems on dicycle and score (outdegree) structures of tournaments
No full textThe dicycle and score (outdegree) structures of tournaments and multipartite tournaments have been studied extensively over past decades. Some classical results include Landau’s [13], Moon’s [15] and Bagga and Beineke’s [2] theorems. In this paper, we extend these results to orientations of a large family of graphs known as the extensions of graphs, which are a natural generalisation of complete multipartite graphs.Accepted versio
Rising heavy precipitation amid decreasing typhoon contribution in Southeast Asia
No full textThe open access publication is available at https://doi.org/10.1088/1748-9326/ae2e1aUnderstanding long-term precipitation changes in Southeast Asia (SEA) is important because the region is highly vulnerable to precipitation-related disasters. This study examines typhoon and non-typhoon heavy precipitation over SEA during 1960–2024 using a typhoon track dataset and three high-resolution precipitation products. Results show a significant decrease in typhoon-precipitation contribution to total precipitation across the entire SEA, both in its continental and maritime regions, especially during the boreal summer half-year. This trend persists under heavy precipitation conditions (95th and 99th percentiles). In contrast, based on tracking results, non-typhoon heavy precipitation shows increases in precipitation area but decreases in lifespan intensity, yielding more total precipitation per event. Our findings indicate a shifting hazard regime: a decrease in typhoon-related rainfall is being offset by a spatial expansion of non-typhoon heavy precipitation, introducing a new regional risk. The findings provide critical insights into the change of regional precipitation patterns and have implications for disaster management and adaptation in SEA
Shifting rules across generations: Variable subject expression in the Canberra Vietnamese heritage language
No full textThe open access publication is available at https://doi.org/10.1017/s0954394525100641This paper examines subject expression in heritage Vietnamese, focusing on its variation in a diasporic, cross-generational context, using corpus data from 45 speakers in Canberra, Australia. While subject expression has been widely studied in other languages, little is known about its use in languages like Vietnamese, which has an “open-class” pronominal system. Results show that although the rates of unexpressed subjects remain stable, the linguistic conditions underlying this variable have undergone change: first-generation speakers are least likely to drop second-person subjects, while second-generation speakers are least likely to drop first-person subjects. Both patterns contradict expectations given the pragmatic constraints of pro-drop in Vietnamese. We further interpret this as potentially a form of community bricolage to re-establish a more equal cross-generational relationship in a diaspora setting. Ultimately, we present a case of pragmatic change driving grammatical choices, thereby also highlighting that contrary to the traditional description, Vietnamese subject expression is perhaps not so “radical” after all
Monitoring suspended sediment longitudinal fluctuations along the Pearl River
No full textClimate change and intensified anthropogenic activities have profoundly altered sediment dynamics in large river systems, particularly across major Asian basins. Traditional hydrological station data, constrained by sparse spatial coverage, are insufficient to capture the continuous longitudinal variability of suspended sediment. To address this limitation, this study integrated satellite remote sensing with advanced model development to quantify suspended sediment concentration (SSC) dynamics across the Pearl River Basin (PRB). A high-accuracy SSC retrieval model was developed by fusing Sentinel-2 imagery with in-situ observations and optimized using a Bayesian calibration algorithm. The results reveal that: (1) Despite still high SSC in the upper PRB (median: 105 mg/L), cascade reservoirs cascade reservoirs substantially intercept suspended sediment, markedly reducing concentrations in midstream reaches; (2) Midstream reaches exhibit lower SSC levels (median: 15 mg/L), while downstream segments show a resurgence (65 mg/L) likely driven by local erosion and tributary inputs; (3) Dam operations have enhanced seasonal SSC disparities reservoir inflow and outflow, with higher retention during the monsoon season and lower during the dry season. These findings demonstrate that traditional hydrological observations fail to represent the pronounced longitudinal SSC variations induced by reservoir cascades, thereby overlooking critical processes shaping sediment transport from the headwaters to the estuary. The spatially continuous SSC maps derived in this study underscore the dual role of reservoirs as both sediment sinks and agents of downstream geomorphic adjustment and deltaic sediment redistribution. These findings offer a scientific basis for improving sediment monitoring and management in the PRB and other similar large river basins facing comparable hydroclimatic and anthropogenic pressures
Overview of normal-reference tests for high-dimensional means with implementation in the R package ‘HDNRA’
No full textThe challenge of testing for equal mean vectors in high-dimensional data poses significant difficulties in statistical inference. Much of the existing literature introduces methods that often rely on stringent regularity conditions for the underlying covariance matrices, enabling asymptotic normality of test statistics. However, this can lead to complications in controlling test size. To address these issues, a new set of tests has emerged, leveraging the normal-reference approach to improve reliability. The latest normal-reference methods for testing equality of mean vectors in high-dimensional samples, potentially with differing covariance structures, are reviewed. The theoretical underpinnings of these tests are revisited, providing a new unified justification for the validity of centralized
-norm-based normal-reference tests (NRTs) by deriving the convergence rate of the distance between the null distribution of the test statistic and its corresponding normal-reference distribution. To facilitate practical application, an R package, HDNRA, is introduced, implementing these NRTs and extending beyond the two-sample problem to accommodate general linear hypothesis testing (GLHT). The package, designed with user-friendliness in mind, achieves efficient computation through a core implemented in C++ using Rcpp, OpenMP, and RcppArmadillo. Examples with real datasets are included, showcasing the application of various tests and providing insights into their practical utility.Accepted versionRI 4/22 ZT
Exploring the role of peer review in computational thinking development among pre-service teachers
No full textThe open access publication is available at https://doi.org/10.58459/rptel.2026.21031Computational thinking can be interpreted as a cognitive process that provides a new paradigm for higher-order thinking about successfully solving problems posed in a technology-mediated teaching and learning context. Peer review has been employed as an effective learning strategy to enhance cognitive practices such as critical thinking, reflection practices and collaborative experiences. A qualitative case study was conducted to explore the role of peer review as a learning strategy of computational thinking among pre-service teachers. The peer comments were coded by adopting a coding scheme of comments, and the interview transcripts were analysed to investigate the significance of the peer-review process and student perceptions of what is most beneficial. Each student was required to design a lesson by integrating the computational thinking facets into their lesson plan. Upon submitting the lesson plan, they were engaged in a blind review process. Individual student reviews the lesson designed by their peers and provides their comments. By adapting a peer-review cognitive process model, this article provides evidence that the peer-review process played a critical role in facilitating pre-service teachers’ computational thinking, particularly problem-solving competencies. The findings indicate that peer review strategy can facilitate computational thinking by enhancing pre-service teachers’ higher-order thinking through constructing and providing critical feedback to their peers. The students perceived the peer-review process was beneficial in improving their computational thinking-integrated lesson design. However, it was suggested that the students be informed about the purposes and learning benefits of the peer-review process to improve their learning experience
Using nonlinear dynamic analysis to differentiate fall status in older women
No full textBackgroundFalls are a significant health concern among older adults. Nonlinear dynamic (NLD) analysis of gait offers insight into fall risk by capturing variability and complexity, but variation in methodological approaches has limited translation. This study aimed to identify NLD measures and data sources that best differentiate fallers from non-fallers.MethodsThirty-four healthy older women (mean age 69.3 ± 5.7 years; 17 fallers, 17 non-fallers) walked on a treadmill at preferred and at ±20 %. Kinematic data were collected using motion capture and a lower-back inertial measurement unit (IMU). Gait complexity and stability were quantified using Multiscale Entropy and Lyapunov Exponents (LyE). Principal component analysis, logistic regression, multivariate tests, ROC curves, and linear discriminant analysis (LDA) identified discriminative features.ResultsFallers reported at least one fall in the past year, walked more slowly, and had a greater chronic disease burden. Short-term LyE (SLyE) from trunk acceleration in the anterior–posterior (AP) direction and sagittal-plane ankle angles best discriminated fall status. ROC analyses showed ankle SLyE provided the highest accuracy (AUC up to 0.88), and AP trunk SLyE had moderate accuracy (AUC up to 0.77). The LDA model achieved 85 % cross-validated accuracy with 82 % sensitivity and 88 % specificity.ConclusionsThe short-term Lyapunov exponent from ankle angle sagittal-plane motion and trunk AP acceleration provide robust markers of fall history in older women. Comparable performance of IMU and motion capture supports IMU-based NLD metrics for scalable fall risk screening
The structures of STEM education: A Macro, meso and micro analysis of learning outcomes
No full textSTEM education is shaped by interconnected macro, meso, and micro structures that impact curriculum design, teaching practices, and learning outcomes. This book explores three distinctive STEM programmes, offering practical insights for educators, researchers, and policymakers to design, plan, and implement effective STEM opportunities that drive meaningful, transformative education.
The first programme, Code to Sew, showcases a university-industry-school partnership that bridges the private-public spaces to foster innovative learning. The second programme, EPIC-STEM, takes an ecosystemic approach to building students’ STEM capital through the affordance of multiple epistemic infrastructures—hackathons, consultative STEM inquiry, symposia, internships, and learning journeys—providing a scalable model across local school clusters. The third programme transcends national boundaries, enhancing teachers’ capacities for STEM curriculum development with cognisance and sensitivities to the partnering country’s digital transformation, education reforms, and local needs.
This book is an essential resource for readers from academic or scholarly policy-making backgrounds aiming to gain deeper insights into the interconnected Structures of STEM education and how they shape meaningful, transferable learning experiences for both educators and learners