Permanent URI for this collection
Browse
50 results
Search results
Publication Tunable double-Weyl Fermion semimetal state in the SrSi2 materials class(Nature Publishing Group, 2018) Singh B.; Chang G.; Chang T.-R.; Huang S.-M.; Su C.; Lin M.-C.; Lin H.; Bansil A.; CENTRE FOR ADVANCED 2D MATERIALS; CHEMISTRYWe discuss first-principles topological electronic structure of noncentrosymmetric SrSi2 materials class based on the hybrid exchange-correlation functional. Topological phase diagram of SrSi2 is mapped out as a function of the lattice constant with focus on the semimetal order. A tunable double-Weyl Fermion state in Sr1-x Ca x Si2 and Sr1-x Ba x Si2 alloys is identified. Ca doping in SrSi2 is shown to yield a double-Weyl semimetal with a large Fermi arc length, while Ba doping leads to a transition from the topological semimetal to a gapped insulator state. Our study indicates that SrSi2 materials family could provide an interesting platform for accessing the unique topological properties of Weyl semimetals. © 2018 The Author(s).Publication Eating behaviors moderate the associations between risk factors in the first 1000 days and adiposity outcomes at 6 years of age(Oxford University Press, 2020-05-01) Fogel A.; McCrickerd K.; Aris I.M.; Goh A.T.; Chong Y.-S.; Tan K.H.; Yap F.; Shek L.P.; Meaney M.J.; Broekman B.F.P.; Godfrey K.M.; Chong M.F.F.; Cai S.; Pang W.W.; Yuan W.L.; Lee Y.S.; Forde C.G.; PHYSIOLOGY; SAW SWEE HOCK SCHOOL OF PUBLIC HEALTH; DUKE-NUS MEDICAL SCHOOL; PAEDIATRICS; OBSTETRICS & GYNAECOLOGYBackground: Several risk factors in the first 1000 d are linked with increased obesity risk in later childhood. The role of potentially modifiable eating behaviors in this association is unclear. Objectives: This study examined whether the association between cumulated risk factors in the first 1000 d and adiposity at 6 y is moderated by eating behaviors. Methods: Participants were 302 children from the GUSTO (Growing Up in Singapore Towards healthy Outcomes) cohort. Risk factors included maternal prepregnancy and paternal overweight, excessive gestational weight gain, raised fasting plasma glucose during pregnancy, short breastfeeding duration, and early introduction of solid foods. Composite risk scores reflecting the prevalence and the importance of the risk factors present were computed. Adiposity outcomes were child BMI and sum of skinfolds (SSF), and candidate eating behavior moderators were portion size, eating rate, and energy intake during lunch and in an eating in the absence of hunger task. Results: Higher composite risk score predicted higher BMI z scores (B = 0.08; 95% CI: 0.04, 0.13) and larger SSF (0.70 mm; 0.23, 1.18 mm), and was associated with larger self-served food portions (5.03 kcal; 0.47, 9.60 kcal), faster eating rates (0.40 g/min; 0.21, 0.59 g/min), and larger lunch intakes (7.05 kcal; 3.37, 10.74 kcal). Importantly, the association between composite risk score and adiposity was moderated by eating behaviors. The composite risk score was unrelated to SSF in children who selected smaller food portions, ate slower, and consumed less energy, but was positively associated with SSF among children who selected larger food portions, ate faster, and consumed more energy (eating behavior × risk score interactions: P < 0.05). Conclusions: The association between risk factors in the first 1000 d and adiposity at 6 y varies by eating behaviors, highlighting modifiable behavioral targets for interventions. This trial was registered at clinicaltrials.gov as NCT01174875. Copyright © The Author(s) 2020.Publication A review on swarm intelligence and evolutionary algorithms for solving flexible job shop scheduling problems(IEEE, 2019-06-19) Gao Kaizhou; CAO ZHIGUANG; Zhang Le; Chen Zhenghua; Han Yuyan; Pan Quanke; INDUSTRIAL SYSTEMS ENGINEERING AND MANAGEMENTFlexible job shop scheduling problems (FJSP) have received much attention from academia and industry for many years. Due to their exponential complexity, swarm intelligence (SI) and evolutionary algorithms (EA) are developed, employed and improved for solving them. More than 60% of the publications are related to SI and EA. This paper intents to give a comprehensive literature review of SI and EA for solving FJSP. First, the mathematical model of FJSP is presented and the constraints in applications are summarized. Then, the encoding and decoding strategies for connecting the problem and algorithms are reviewed. The strategies for initializing algorithms? population and local search operators for improving convergence performance are summarized. Next, one classical hybrid genetic algorithm (GA) and one newest imperialist competitive algorithm (ICA) with variables neighborhood search (VNS) for solving FJSP are presented. Finally, we summarize, discuss and analyze the status of SI and EA for solving FJSP and give insight into future research directions.Publication Maternal Dietary Patterns and Gestational Diabetes Mellitus in a Multi-Ethnic Asian Cohort: The GUSTO Study(MDPI, 2016-09-20) de Seymour J.; Chia A.; Colega M.; Jones B.; McKenzie E.; Shirong C.; K. Godfrey; Kwek K.; Saw S. M.; Conlon C.; Chong Y. S.; Baker P.; Chong M. F.; DUKE-NUS GRADUATE MEDICAL SCHOOL S'PORE; SAW SWEE HOCK SCHOOL OF PUBLIC HEALTH; PAEDIATRICS; OBSTETRICS & GYNAECOLOGYGestational Diabetes Mellitus (GDM) is associated with an increased risk of perinatal morbidity and long term health issues for both the mother and offspring. Previous research has demonstrated associations between maternal diet and GDM development, but evidence in Asian populations is limited. The objective of our study was to examine the cross-sectional relationship between maternal dietary patterns during pregnancy and the risk of GDM in a multi-ethnic Asian cohort. Maternal diet was ascertained using 24-h dietary recalls from participants in the Growing up in Singapore towards healthy outcomes (GUSTO) study—a prospective mother-offspring cohort, and GDM was diagnosed according to 1999 World Health Organisation guidelines. Dietary patterns were identified using factor analysis, and multivariate regression analyses performed to assess the association with GDM. Of 909 participants, 17.6% were diagnosed with GDM. Three dietary patterns were identified: a vegetable-fruit-rice-based-diet, a seafood-noodle-based-diet and a pasta-cheese-processed-meat-diet. After adjusting for confounding variables, the seafood-noodle-based-diet was associated with a lower likelihood of GDM (Odds Ratio (95% Confidence Interval)) = 0.74 (0.59, 0.93). The dietary pattern found to be associated with GDM in our study was substantially different to those reported previously in Western populations. © 2016 by the authors; licensee MDPI, Basel, Switzerland.Publication Regulating Monopolistic ISPs Without Neutrality(IEEE, 2019-05-13) TANG JING; Ma Tianbai; DEPARTMENT OF COMPUTER SCIENCE; INDUSTRIAL SYSTEMS ENGINEERING AND MANAGEMENTNet neutrality has recently been heavily debated as a potential regulation of the Internet. This debate is centered around the argument whether the Internet Service Providers (ISPs) should be allowed to provide differentiated services over the Internet. Advocates of net neutrality have expressed concerns about the ISPs’ pricing power, which might be used to discriminate Content Providers (CPs), and consequently destroy innovations at the edge of the Internet and hurt users’ utilities. However, without service differentiation, ISPs do not have incentives to expand infrastructure capacities and provide quality of services, which will eventually impair the development of the future Internet. Although market competition among the ISPs would alleviate the problem and reduce the need for net neutrality regulations, the problem is more severe in monopolistic markets, e.g., rural access markets where natural monopolies exist due to high deployment costs and appropriate regulations are most in need. We study the service differentiation offered by a monopolistic ISP and find that the ISP’s profit-optimal strategy makes a free ordinary service damaged good, which hurts the welfare of CPs and their users. Instead of imposing net neutrality regulations, we propose a more flexible and lenient policy framework that generalizes net neutrality regulations. We believe that by allowing ISPs to differentiate services under a well-designed policy constraint, the utility of the entire Internet ecosystem could be greatly improved.Publication Associations of physical activity and sedentary behavior during pregnancy with gestational diabetes mellitus among Asian women in Singapore(BioMed Central Ltd., 2017-10-18) Padmapriya N.; Bernard J.Y.; Liang S.; Loy S.L.; Cai S.; Zhe I.S.; Kwek K.; Godfrey K.M.; Gluckman P.D.; Saw S.M.; Chong Y.-S.; Chan J.K.Y.; MUELLER-RIEMENSCHNEIDER FALK; Sheppard A.; Chinnadurai A.; Neo Goh A.E.; Rifkin-Graboi A.; Qiu A.; Biswas A.; Lee B.W.; Broekman B.F.P.; Quah B.L.; Shuter B.; Chng C.K.; Ngo C.; Bong C.L.; Henry C.J.; Ing Chee C.Y.; Daniel Goh Y.T.; Fok D.; Yap F.; Heong Yeo G.S.; Chen H.; van Bever H.P.S.; Magiati I.; Yun Wong I.B.; Lau I.Y.-M.; Kapur J.; Richmond J.L.; Holbrook J.D.; Gooley J.J.; Tan K.H.; Niduvaje K.; Singh L.; Su L.L.; Daniel L.M.; Shek L.P.-C.; Fortier M.V.; Hanson M.; MARY CHONG FOONG FONG; Rauff M.; Chua M.C.; Meaney M.; Tint M.T.; Karnani N.; Lek N.; Teoh O.H.; Wong P.C.; Agarwal P.; van Dam R.M.; Rebello S.A.; Chong S.C.; Soh S.-E.; Lim S.B.; Hsu C.-Y.S.; Rajadurai V.S.; Stunkel W.; Han W.M.; Pang W.W.; CHEUNG YIN BUN; Chan Y.H.; Lee Y.S.; DEAN'S OFFICE (MEDICINE); BIOMEDICAL ENGINEERING; SAW SWEE HOCK SCHOOL OF PUBLIC HEALTH; DUKE-NUS MEDICAL SCHOOL; OBSTETRICS & GYNAECOLOGYBackground: Few studies have investigated physical activity (PA) and sedentary behavior (SB) in relation to fasting (FG) and 2-h postprandial plasma glucose (2hPG) levels and gestational diabetes mellitus (GDM); we investigated these associations among Asian pregnant women. Methods: As part of the Growing Up in Singapore Towards healthy Outcomes cohort study, PA and SB (sitting and television times) were assessed by interviewer-administered questionnaire. During 75 g oral glucose tolerance tests at 26-28 weeks' gestation we measured FG, 2hPG levels and GDM (FG ≥ 7.0 mmol/L and/or 2hPG ≥ 7.8 mmol/L). Associations were analysed by multiple linear and logistic regression. Results: Among the 1083 women studied, 18.6% had GDM. SB was not associated with FG, 2hPG and GDM. Higher categories of PA were associated with lower 2hPG and a lower likelihood of GDM (p-trend < 0.05), but not with FG levels. Compared to insufficiently active women, highly active women had lower 2hPG levels [β (95% CI): -0.32 (-0.59, -0.05), p = 0.020) and were less likely to have GDM [OR: 0.56 (0.32-0.98), p = 0.040]. Stratified analysis revealed no associations among under/normal-weight women, but significant associations among overweight/obese women; in those with BMI ≥23 kg/m2, sufficiently active and highly active women were less likely to have GDM [OR: 0.52, (0.29-0.93), p = 0.028, and OR: 0.34, (0.15-0.77), p = 0.010, respectively]. Conclusion: Higher PA was associated with lower 2hPG levels and a lower prevalence of GDM, particularly in overweight/obese women. Further studies are warranted to confirm these findings, and to examine the effectiveness of PA promotion strategies for the prevention of gestational hyperglycemia. © 2017 The Author(s).Publication Physical Activity and Sedentary Behavior Patterns Before and During Pregnancy in a Multi-ethnic Sample of Asian Women in Singapore.(Springer Verlag, 2015-07-04) Padmapriya, Natarajan; Shen, Liang; Soh, Shu E; Shen, Zhe; Kwek, Kenneth; Godfrey, Keith M.; Gluckman, Peter D.; Chong, Yap Seng; Saw, Seang Mei; Müller-Riemenschneider, Falk; SAW SWEE HOCK SCHOOL OF PUBLIC HEALTH; PAEDIATRICS; OBSTETRICS & GYNAECOLOGYObjectives: To describe physical activity (PA) and sedentary behavior (SB) patterns before and during pregnancy among Chinese, Malay and Indian women. In addition, to investigate determinants of change in PA and SB during pregnancy. Methods: The Growing Up in Singapore Towards healthy Outcomes cohort recruited first trimester pregnant women. PA and SB (sitting time and television time) before and during pregnancy were assessed as a part of an interview questionnaire at weeks 26–28 gestational clinic visit. Total energy expenditure (TEE) on PA and time in SB were calculated. Determinants of change in PA and SB were investigated using multiple logistic regression analysis. Results: PA and SB questions were answered by 94 % (n = 1171) of total recruited subjects. A significant reduction in TEE was observed from before to during pregnancy [median 1746.0–1039.5 metabolic equivalent task (MET) min/week, p < 0.001]. The proportion of women insufficiently active (<600 MET-min/week) increased from 19.0 to 34.1 % (p < 0.001). Similarly, sitting time (median 56.0–63.0 h/week, p < 0.001) and television time (mean 16.1–16.7 h/week, p = 0.01) increased. Women with higher household income, lower level of perceived health, nausea/vomiting during pregnancy and higher level of pre-pregnancy PA were more likely to reduce PA. Women with children were less likely to reduce PA. Women reporting nausea/vomiting and lower level of pre-pregnancy sitting time were more likely to increase sitting time. Conclusions for Practice: Participants substantially reduced PA and increased SB by 26–28 weeks of pregnancy. Further research is needed to better understand determinants of change in PA and SB and develop effective health promotion strategies. © 2015, Springer Science+Business Media New York.Publication Bevacizumab Promotes T-Cell-Mediated Collagen Deposition in the Mouse Model of Conjunctival Scarring(2018) Seet L.-F.; Toh L.Z.; Chu S.; Finger S.N.; Ginhoux F.; Hong W.; Wong T.T.; PHYSIOLOGY; MICROBIOLOGY AND IMMUNOLOGY; DUKE-NUS MEDICAL SCHOOL; BIOCHEMISTRYPurpose: We determine the effects of bevacizumab on collagen production in a mouse model of conjunctival scarring.Methods: Experimental surgery was performed as described for the mouse model of conjunctival scarring, and bevacizumab was introduced by conjunctival injection. The capacity of bevacizumab to recognize conjunctival VEGF-A was determined by ELISA. Col1a1 was measured by real-time PCR and immunoblotting. T cells and collagen were visualized by immunofluorescence and picrosirius red staining of bleb cryosections. Conjunctival CD4+ or CD8a+ T cells were counted by flow cytometry. Mouse splenic T cells were cultured with bevacizumab/IgG and their numbers, cell cycle, and collagen production were measured using a cell counter, flow cytometry, and sircol soluble collagen assay, respectively. Reconstitution experiments in severe combined immunodeficiency (SCID) mice were performed by injection of freshly isolated T cells on day 2 postoperatively.Results: Bevacizumab recognized approximately 20% of endogenous murine VEGF-A. Injection of bevacizumab raised Col1a1 expression in the blebs at mRNA and protein levels. Bevacizumab did not induce collagen in conjunctival fibroblasts, but increased CD4+ and CD8a+ cell numbers as well as collagen production by these cells. Collagen appeared to accumulate in the vicinity of T cells in the bevacizumab-treated blebs. While SCID blebs did not show elevated collagen levels, reconstitution with CD4+ or CD8a+ cells resulted in increased Col1a1 expression at mRNA and protein levels.Conclusions: Bevacizumab increased collagen production in the mouse model of conjunctival scarring. This collagen induction was mediated by T cells that were also stimulated by bevacizumab to increase in numbers.Publication Color-stable highly luminescent sky-blue perovskite light-emitting diodes(Nature Publishing Group, 2018) Xing J.; Zhao Y.; Askerka M.; Quan L.N.; Gong X.; Zhao W.; Zhao J.; Tan H.; Long G.; Gao L.; Yang Z.; Voznyy O.; Tang J.; Lu Z.-H.; Xiong Q.; Sargent E.H.; PHYSICS; CHEMISTRYPerovskite light-emitting diodes (PeLEDs) have shown excellent performance in the green and near-infrared spectral regions, with high color purity, efficiency, and brightness. In order to shift the emission wavelength to the blue, compositional engineering (anion mixing) and quantum-confinement engineering (reduced-dimensionality) have been employed. Unfortunately, LED emission profiles shift with increasing driving voltages due to either phase separation or the coexistence of multiple crystal domains. Here we report color-stable sky-blue PeLEDs achieved by enhancing the phase monodispersity of quasi-2D perovskite thin films. We selected cation combinations that modulate the crystallization and layer thickness distribution of the domains. The perovskite films show a record photoluminescence quantum yield of 88% at 477 nm. The corresponding PeLEDs exhibit stable sky-blue emission under high operation voltages. A maximum luminance of 2480 cd m?2 at 490 nm is achieved, fully one order of magnitude higher than the previous record for quasi-2D blue PeLEDs. © 2018, The Author(s).Publication Predominantly night-time feeding and maternal glycaemic levels during pregnancy(Cambridge University Press, 2016-01-25) Loy, See Ling; Cheng, Tuck Seng; Colega, Marjorelee T.; Cheung, Yin Bun; Godfrey, Keith M.; Gluckman, Peter D.; Kwek, Kenneth; Saw, Seang-Mei; Chong, Yap-Seng; Nataraja, Padmapriya; Müller-Riemenschneider, Falk; Lek, Ngee; Yap, Fabian Kok Peng; Chong, Mary Foong Fong; Chan, Jerry Kok Yen; DUKE-NUS GRADUATE MEDICAL SCHOOL S'PORE; SAW SWEE HOCK SCHOOL OF PUBLIC HEALTH; PAEDIATRICS; OBSTETRICS & GYNAECOLOGY