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9. Developing very short computerised early vocabulary assessments in a multilingual setting

Author

Chai, Jun Ho

Subjects
BF Psychology
Abstract

The MacArthur-Bates Communicative Development Inventories (CDIs) are one of the most widely adapted sets of parent-report instruments for assessing young children's early vocabulary acquisition (Fenson et al., 2007; Frank, Braginsky, Marchman, & Yurovsky, 2021). The MacArthur-Bates Communicative Development Inventories (CDIs) are valid and reliable not only with children who are developing typically (Fenson et al., 2007, 1993; Pan, Rowe, Spier, & Tamis-Lemonda, 2004; Rescorla, Ratner, Jusczyk, & Jusczyk, 2005; Law & Roy, 2008), but also with children developing atypically (Galeote, Checa, Sánchez- Palacios, Sebastián, & Soto, 2016; Luyster, Lopez, & Lord, 2007; Mayne, Yoshinaga-Itano, Sedey, & Carey, 1998; Mayne, Yoshinaga-Itano, & Sedey, 1999; D. Thal, DesJardin, & Eisenberg, 2007). The CDIs provide extensive insights into children's vocabulary sizes, yet they rely on parents' knowledge of their children. Furthermore, the completion of each CDI is time-consuming as the parent has to assess their child's word knowledge item-by-item, often amounting to 600 words or more. Although previous efforts were made to develop 100-item short-form versions, it is time-consuming to develop short-forms for each language, and their administrations remain a considerable time investment for parents when completing such forms. The process of completing CDIs is made even more laborious, when having to fill out CDIs for several languages, for children exposed to more than one language, such as most children from Malaysia, a linguistically diverse country, where bi- and multilingually-exposed children constitute a significant proportion of the population. Hence, the objective of the current project is two-fold: 1) to collect the first Malaysian early vocabulary data using an adaptation of the CDI forms and provide insights into Malaysian children's early language development; and 2) to develop CDI-based novel vocabulary assessment tools, with the aim of improving the administration of CDIs and examining the viability of a CDI-based toddler-directed word comprehension assessment tool using tablets to supplement the parental reports. The first part of the thesis adopted the MacArthur-Bates Communicative Developmental Inventories - Malaysian version (MCDI-M), a trilingual form developed by Low (2009) to examine the early vocabulary trajectories of young Malaysian children, along with a quantification of environmental effects on the language development of these children, and examining the composition of early vocabularies, i.e., the acquisition of nouns and verbs. The second part of the thesis introduced two novel early vocabulary assessment tools. First, a language-general, Bayesian-inspired item response theory-based framework was developed - based on prior work by Mayor and Mani (2018) and Makransky, Dale, Havmose, and Bleses (2016) (MM-IRT) in order to reduce the number of items needed to assess children's language. This framework was evaluated using data sampled from the Wordbank database in English, Danish, Mandarin and Italian. The framework was then applied to two sets of MCDI-M dataset to evaluate the possibility of using this set of innovations in the context of multilingual children in Malaysia. Second, a toddler-based version of CDIs, using tablets, was evaluated with the aim of directly assessing each child's language skills, and was evaluated empirically. In sum, the first part of this thesis found the use of MCDI-M as an effective early vocabulary assessment tool for Malaysian children, whereas the second part of this thesis paved the way towards the application of rapid yet robust language assessments powered by MM-IRT, to be used in clinical settings, and demonstrated the viability and convergence of using tablets for direct-measure of language skills.

Published
2022

19. Forward Invariance of Sets for Hybrid Dynamical Systems (Part II)

Author

Chai, Jun and Sanfelice, Ricardo

Subjects
Mathematics - Dynamical Systems
Abstract

This article presents tools for the design of control laws inducing robust controlled forward invariance of a set for hybrid dynamical systems modeled as hybrid inclusions. A set has the robust controlled forward invariance property via a control law if every solution to the closed-loop system that starts from the set stays within the set for all future time, regardless of the value of the disturbances. Building on the first part of this article, which focuses on analysis (Chai and Sanfelice, 2019), in this article, sufficient conditions for generic sets to enjoy such a property are proposed. To construct invariance inducing state-feedback laws, the notion of robust control Lyapunov function for forward invariance is defined. The proposed synthesis results rely on set-valued maps that include all admissible control inputs that keep closed-loop solutions within the set of interest. Results guaranteeing the existence of such state-feedback laws are also presented. Moreover, conditions for the design of continuous state-feedback laws with minimum point-wise norm are provided. Major results are illustrated throughout this article in a constrained bouncing ball system and a robotic manipulator application., Comment: 56 pages, 8 figures, Part I is published in arXiv:1808.05129 The article has been accepted by the IEEE Transaction on automatic control journal for publication

Published
2020

25. Detailed polarization measurements of the prompt emission of five Gamma-Ray Bursts

Author

Zhang, Shuang-Nan, Kole, Merlin, Bao, Tian-Wei, Batsch, Tadeusz, Bernasconi, Tancredi, Cadoux, Franck, Chai, Jun-Ying, Dai, Zi-Gao, Dong, Yong-Wei, Gauvin, Neal, Hajdas, Wojtek, Lan, Mi-Xiang, Li, Han-Cheng, Li, Lu, Li, Zheng-Heng, Liu, Jiang-Tao, Liu, Xin, Marcinkowski, Radoslaw, Orsi, Silvio, Produit, Nicolas, Pohl, Martin, Rybka, Dominik, Shi, Hao-Li, Song, Li-Ming, Sun, Jian-Chao, Szabelski, Jacek, Tymieniecka, Teresa, Wang, Rui-Jie, Wang, Yuan-Hao, Wen, Xing, Wu, Bo-Bing, Wu, Xin, Wu, Xue-Feng, Xiao, Hua-Lin, Xiong, Shao-Lin, Zhang, Lai-Yu, Zhang, Li, Zhang, Xiao-Feng, Zhang, Yong-Jie, and Zwolinska, Anna

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Gamma-ray bursts are the strongest explosions in the Universe since the Big Bang, believed to be produced either in forming black holes at the end of massive star evolution or merging of compact objects. Spectral and timing properties of gamma-ray bursts suggest that the observed bright gamma-rays are produced in the most relativistic jets in the Universe; however, the physical properties, especially the structure and magnetic topologies in the jets are still not well known, despite several decades of studies. It is widely believed that precise measurements of the polarization properties of gamma-ray bursts should provide crucial information on the highly relativistic jets. As a result there have been many reports of gamma-ray burst polarization measurements with diverse results, see, however many such measurements suffered from substantial uncertainties, mostly systematic. After the first successful measurements by the GAP and COSI instruments, here we report a statistically meaningful sample of precise polarization measurements, obtained with the dedicated gamma-ray burst polarimeter, POLAR onboard China's Tiangong-2 spacelab. Our results suggest that the gamma-ray emission is at most polarized at a level lower than some popular models have predicted; although our results also show intrapulse evolution of the polarization angle. This indicates that the low polarization degrees could be due to an evolving polarization angle during a gamma-ray burst., Comment: 34 pages, 15 figures (16 pages and 3 figures without supplementary information). Accepted for publication in Nature Astronomy, http://dx.doi.org/10.1038/s41550-018-0664-0

Published
2019
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30. Forward Invariance of Sets for Hybrid Dynamical Systems (Part I)

Author

Chai, Jun and Sanfelice, Ricardo G.

Subjects
Mathematics - Dynamical Systems
Abstract

In this paper, tools to study forward invariance properties with robustness to dis- turbances, referred to as robust forward invariance, are proposed for hybrid dynamical systems modeled as hybrid inclusions. Hybrid inclusions are given in terms of dif- ferential and difference inclusions with state and disturbance constraints, for whose definition only four objects are required. The proposed robust forward invariance notions allow for the diverse type of solutions to such systems (with and without dis- turbances), including solutions that have persistent flows and jumps, that are Zeno, and that stop to exist after finite amount of (hybrid) time. Sufficient conditions for sets to enjoy such properties are presented. These conditions are given in terms of the objects defining the hybrid inclusions and the set to be rendered robust forward invariant. In addition, as special cases, these conditions are exploited to state results on nominal forward invariance for hybrid systems without disturbances. Furthermore, results that provide conditions to render the sublevel sets of Lyapunov-like functions forward invariant are established. Analysis of a controlled inverter system is presented as an application of our results. Academic examples are given throughout the paper to illustrate the main ideas., Comment: 39 pages, 7 figures, accepted to TAC

Published
2018

31. Structure Stability and Electronic Property for Alkaline-Earth Metals Induced Si(111)-3x2 Surfaces

Author

Chai, Jun-Shuai, Li, Zhen-Zhen, Xu, Lifang, and Wang, Jian-Tao

Subjects
Condensed Matter - Materials Science
Abstract

Structural stability and electronic properties of alkaline-earth metals (Ca, Sr, Ba) induced Si(111)-3x2 surfaces have been comprehensively studied by means of ab initio calculations. Adsorption energy and charge density difference calculations show the high structural stability due to the strong chemical bonding. Analysis of electronic band structures and band-decomposed charge density distributions indicates that the third valence band is deriving from top Si and metal atoms, while the top most two valence bands are deriving from the bulk silicon. These results suggest a larger surface band gap of 1.65-1.68 eV, which is good consistent with the recent experimental finding for Sr/Si(111)-3x2 surface. These results reveal a natural explanation for the relevant experimental observation and stimulate further experimental and theoretical exploration on the surface science., Comment: 7 pages , 4 figures

Published
2018
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34. Forward Invariance of Sets for Hybrid Dynamical Systems (Part I)

Author

Chai, Jun and Sanfelice, Ricardo G

Subjects
Control Engineering, Mechatronics and Robotics, Engineering, Control theory, inverters, lyapunov methods, nonlinear control systems, nonlinear dynamic systems, robustness, math.DS, Applied Mathematics, Electrical and Electronic Engineering, Mechanical Engineering, Industrial Engineering & Automation, Control engineering, mechatronics and robotics
Abstract

In this paper, tools to study forward invariance properties with robustness to disturbances, referred to as robust forward invariance, are proposed for hybrid dynamical systems modeled as hybrid inclusions. Hybrid inclusions are given in terms of differential and difference inclusions with state and disturbance constraints, for whose definition only four objects are required. The proposed robust forward invariance notions allow for the diverse type of solutions to such systems (with and without disturbances), including solutions that have persistent flows and jumps, that are Zeno, and that stop to exist after finite amount of (hybrid) time. Sufficient conditions for sets to enjoy such properties are presented. These conditions are given in terms of the objects defining the hybrid inclusions and the set to be rendered robust forward invariant. In addition, as special cases, these conditions are exploited to state results on nominal forward invariance for hybrid systems without disturbances. Furthermore, results that provide conditions to render the sublevel sets of Lyapunov-like functions forward invariant are established. Analysis of a controlled inverter system is presented as an application of our results. Academic examples are given throughout this paper to illustrate the main ideas.

Published
2019

35. A Bayesian-Inspired Item Response Theory-Based Framework to Produce Very Short Versions of MacArthur-Bates Communicative Development Inventories

Author

Chai, Jun Ho, Lo, Chang Huan, and Mayor, Julien

Abstract

Purpose: This study introduces a framework to produce very short versions of the MacArthur-Bates Communicative Development Inventories (CDIs) by combining the Bayesian-inspired approach introduced by Mayor and Mani (2019) with an item response theory-based computerized adaptive testing that adapts to the ability of each child, in line with Makransky et al. (2016). Method: We evaluated the performance of our approach--dynamically selecting maximally informative words from the CDI and combining parental response with prior vocabulary data--by conducting real-data simulations using four CDI versions having varying sample sizes on Wordbank--the online repository of digitalized CDIs: American English (a very large data set), Danish (a large data set), Beijing Mandarin (a medium-sized data set), and Italian (a small data set). Results: Real-data simulations revealed that correlations exceeding 0.95 with full CDI administrations were reached with as few as 15 test items, with high levels of reliability, even when languages (e.g., Italian) possessed few digitalized administrations on Wordbank. Conclusions: The current approach establishes a generic framework that produces very short (less than 20 items) adaptive early vocabulary assessments--hence considerably reducing their administration time. This approach appears to be robust even when CDIs have smaller samples in online repositories, for example, with around 50 samples per month-age.

Published
2020
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38. Analysis and Design of Event-Triggered Control Algorithms Using Hybrid Systems Tools

Author

Chai, Jun, Casau, Pedro, and Sanfelice, Ricardo G

Subjects
Applied Mathematics, Mathematical Sciences, Control Engineering, Mechatronics and Robotics, Engineering
Abstract

This paper proposes a general framework for analyzing continuous-Time systems controlled by event-Triggered algorithms. Closed-loop systems resulting from using both static and dynamic output (or state) feedback laws that are implemented via asynchronous event-Triggered techniques are modeled as hybrid systems given in terms of hybrid inclusions and studied using recently developed tools for robust stability. Properties of the proposed models, including stability of compact sets, robustness, and Zeno behavior of solutions are addressed. The framework and results are illustrated in several event-Triggered strategies available in the literature.

Published
2017

46. On Robust Forward Invariance of Sets for Hybrid Dynamical Systems

Author

Chai, Jun and Sanfelice, Ricardo G

Subjects
Applied Mathematics, Engineering, Control Engineering, Mechatronics and Robotics, Mathematical Sciences
Abstract

Forward invariance with robustness to disturbances for hybrid dynamical systems modeled by hybrid inclusions with state-dependent conditions enabling flows and jumps is studied. In particular, we study forward invariance notions that apply to systems with hybrid inputs and disturbances with nonlinear dynamics, for which not every solution is unique or may exist for arbitrary long hybrid time. Given state-feedback laws, notions of robust forward invariance of sets for closed-loop system are introduced. Sufficient conditions in terms of the objects defining the system are presented. One result using Lyapunov-based conditions removes the usual Lipschitz constraint on continuous dynamics. A bouncing ball example is given to illustrate major results.

Published
2017

47. Is the relative distribution of verbs and nouns modulated by socio-culturalinfluences? Evidence from bilingual infants and toddlers in Malaysia.

Author

Chai, Jun Ho, Low, Hui Min, Wong, Tze Peng, and Mayor, Julien

Abstract

Early vocabularies in most languages tend to contain more nouns than verbs. Yet, the strength of this noun bias hasbeen observed to vary across languages and cultures. Two main hypotheses have aimed at explaining such variations; eitherthat the relative importance of nouns vs. verbs is language- specific, or that socio-cultural influences shape early vocabularystructures. The present study compares the relative distribution of verbs and nouns, in English, between two groups of bilingualinfants and toddlers; Malay-English and Mandarin- English. We found that early English lexicons of Mandarin- Englishbilinguals contained more verbs than in the English lexicon of Malay-English bilinguals, in both comprehension and production.We discuss the potential role of socio-cultural influences on the vocabulary structure in young users of a language.

Published
2017

49. Effect of Cangrelor on Infarct Size in ST-Segment–Elevation Myocardial Infarction Treated by Primary Percutaneous Coronary Intervention: A Randomized Controlled Trial (The PITRI Trial)

Author

Bulluck, Heerajnarain, Chong, Jun Hua, Bryant, Jennifer, Annathurai, Annitha, Chai, Ping, Chan, Mervyn, Chawla, Ashish, Chin, Chee Yang, Chung, Yiu-Cho, Gao, Fei, Ho, Hee Hwa, Ho, Andrew Fu Wah, Hoe, John, Imran, Syed Saqib, Lee, Chi-Hang, Lim, Benji, Lim, Soo Teik, Lim, Swee Han, Liew, Boon Wah, Zhan Yun, Patrick Lim, Ong, Marcus Eng Hock, Paradies, Valeria, Pung, Xuan Ming, Tay, Julian Cheong Kiat, Teo, Lynette, Ting, Boon Ping, Wong, Aaron, Wong, Evelyn, Watson, Timothy, Chan, Mark Y., Keong, Yeo Khung, Tan, Jack W.C., Hausenloy, Derek J., Tan, Jack W.C., Hausenloy, Derek J., Chi, Chee-Tang, Tay, Julian, Xuan Ming, Pung, Anbalakan, Kamalesh, Yann San, Keh, Chew, Kenneth, Chan, Michelle, Rilong, Hong, Swee Leng, Kui, Soo Teik, Lim, Lee, Audry, Maverick Rubillar, Felix, Cai, James, Yap, Jonathan, Ning Yan, Wong, Kay Woon, Ho, Fang Yi, Lim, Xia Yen, Shen, Xucong, Ruan, Khung Keong, Yeo, Hua Chong, Jun, Bryant, Jennifer, Chua, Terrance, Yang Chin, Chee, Paradies, Valeria, Wong, Aaron, Bahru, Leong, Teo, Tina, Ru San, Tan, Hak Chiaw, Tang, Chin, Calvin, Ang, Florence, Kyaw, Min-Tun, Priyalatha, S., Chua, Jia-Mei, Yip, Deborah, Lee, Rosalind, Oh, Katherina, Pei Yi, Ho, Wanshan, Leow, Atiqa Binte Rahmat, Syamimi, Yar Chze, Gan, Hausenloy, Derek J., Gao, Fei, Yan Tan, Shi, Chan, Mervyn, Fatimah, Lateef, Ho, Andrew, Choon Peng Jeffrey, Wee, Han Lim, Swee, Ong Eng Hock, Marcus, Wong, Evelyn, Tan Boon Kiat, Kenneth, Venkataraman, Anantharaman, Chan, Mark Y., Lee, Chi-Hang, Ping, Chai, Fatt Hoe Adrian, Low, Koo Hui, Chan, Poay Huan, Loh, Yi-Ting Laureen, Wang, Zhengfeng Jason, Chen, Dalakoti, Mayank, Ng, Perryn, Ching Hui, Sia, Chook, Shaun, Yip, Alfred, Zhe Yan, Ng, Hartanto Djohan, Andie, Houdmont, Marie, Chew, Nicholas, Jiamin, Siew, Ng, Faclin, Teo, Lynette, Ching Ong, Ching, Song, Junda, Kuang Low, Choong, Shalini, Nair, Francis Prabath, Joseph, Ho, Hee-Hwa, Mahadi, Tasha, Watson, Timothy, Ong, Paul, Xin Ni, Koo, Chai Jun Hui, Tony, Yue Ting, Ho, Zhi Lin Deanna, Khoo, Lee Jin Hyun, Deborah, Ki Fung Cliff, Li, Low Jun Bang, Randal, Joo Hor, Tan, Ke Xuan Jessica, Ng, Jia Min, Chua, Wei Sheng Jonathan, Ong, Xuyan, Teoh, Shu Qi Benita, Chiang, Sim Wen Jun, Eran, An Shing, Ang, Jia-ling Stephanie, Quek, Rui Yi, Pang, Ahmad Hatib Muhammad Alimi, Bin, Jin Hyun, Lee, Shiane, Lim, Chong Keat, Tan, Shonda, Ng, Hoe, John, Tan, Jack, Chee Yang, Chin, Jian Ming, Fam, Raudha, Siti, Annathurai, Annitha, Ping Ting, Boon, Chawla, Ashish, Saqib Imran, Syed, Lim Zhan Yun, Patrick, Tan, Alvin, Lim, Benji, Wah Liew, Boon, and Thon Hon, Yong

Published
2024
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