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Publication MICRORNA-128 REGULATES THE PROLIFERATION AND NEUROGENESIS OF NEURAL PRECURSORS BY TARGETING PERICENTRIOLAR MATERIAL 1 (PCM1) IN THE DEVELOPING NEOCORTEX(2016-07-27) PAUL JONG KIM; DEAN'S OFFICE (DUKE-NUS MEDICAL SCHOOL)Formation of the neocortex during brain development requires coordinated transition of cell division from one that favors progenitor proliferation to that of neuronal differentiation undertaken by neural stem cells (NSCs). Disruption to this process may underlie structural changes in the brain associated with neuropsychiatric disorders including autism spectrum disorders (ASDs). Evidence that suggests microRNA (miR)-128, shown to be dysregulated in ASDs, to be a key regulator of NSC division is presented in this thesis. Manipulation of miR-128 in embryonic NSCs is carried out both in vitro and in vivo, in which upregulation increases neurogenesis and inhibits progenitor proliferation while downregulation has the opposite effect. Furthermore, pericentriolar material 1 (PCM1) is identified as the downstream molecular target of miR-128 that mediates the regulatory effect of the microRNA. Overexpression of miR-128 suppresses PCM1 at both mRNA and protein levels, and direct knockdown of PCM1 produces a phenocopy of miR-128 overexpression in NSCs. Finally, concomitant induction of PCM1 and miR-128 overexpression in NSCs rescued the phenotype associated with miR-128 overexpression, both in vitro and in vivo. Taken together, these results demonstrate a novel mechanism by which miR-128 regulates the proliferation and differentiation of NSCs in the developing neocortex.Publication Robust Optimization With Applications In Healthcare Operations Management(2014-08-22) ZHANG MEILIN; DECISION SCIENCES; SIM SOON SUAN, MELVYNThe combination of an increasingly complex world, the vast proliferation of data, and the pressing need to stay one step ahead of competition has sharpened focus on using analytics and optimization for decision making. There is also a need to computationally exploit the wealth of data available in optimization problems by providing a exible framework for modeling uncertainty that incorporates distributional information, while preserving the computational tractability for practical implementation. As motivated by the importance of such a decision making process, I investigate this procedure under robust optimization and extend the ndings into real applications in health care operations management.Publication GENETIC CONNECTIVITY OF FOUR MANGROVE SPECIES FROM THE MALAY PENINSULA(2013-08-12) WEE KIM SHAN; BIOLOGICAL SCIENCES; WEBB, EDWARD LAYMANAs habitat fragmentation and degradation continues to threaten the integrity of genetic connectivity in mangroves, gene flow among populations becomes increasingly important for the maintenance of sufficient genetic diversity and evolutionary potential. In this thesis, I determined the effects of reproductive traits, physical barriers and ocean currents on gene flow in mangroves, by examining the genetic connectivity of four major mangrove species from the Malay Peninsula. My data revealed that the relative genetic connectivity across species reflects their relative propagule dispersal potential, indicating that dispersal traits have a significant influence over gene flow. Comparative analysis across species demonstrated that the peninsula was a differential barrier to gene flow, and that ocean currents are important in defining genetic connectivity. Understanding gene flow in mangroves and the intrinsic and extrinsic factors behind it is crucial in assessing the genetic susceptibility of mangroves towards and the potential of recovery from habitat disturbances.Publication SURVEYS ON THE USAGE OF COMPLEMENTARY AND ALTERNATIVE MEDICINE, HERBAL PRODUCTS IN THE MARKET AND THE EFFECTS OF GINSENOSIDE RG1 ON MEDIAL PREFRONTAL CORTEX(2014-08-15) MEHDY GHAEMINIA; PHARMACOLOGY; TAN CHAY HOON; KOH HWEE LINGUsage of CAM has prominent impact on users? health. Here, this fact was studied by getting the information from community and expanding the research to the laboratory. Analyzing the CAM usage among older adults revealed its prevalence as 54% (the commonest type was herbal medicine). Composite CAM and qigong usages showed protection against cognitive decline. By a telephone-based interview, we found three Panax species among the top six herbs used by older adults. Surveying the labels of products containing the words ?Panax? or ?ginseng?, we found Panax ginseng is the commonest ingredient of such products. Finally, the neuroinhibitory effects of a high abundant chemical component of Panax species, Rg1, on medial prefrontal cortex (mPFC) were observed using electrphysiological and histochemical methods. This first report of modulation of mPFC by Rg1 and first report of its possible neuroinhibitory effects may help to explain its anxiolytic and memory enhancing properties.Publication INFLUENCER-GENERATED ORGANIC CONTENT AND FIRM STRATEGIES(2023-06-27) GAO SHIWEN; MARKETING; Wei Shi LimConsumers are now increasingly relying on social media to discover new products and acquire information about product fit. Influencer-generated organic product reviews, as an independent source of product information, play an increasingly important role in consumers’ purchase decisions. We develop a game-theoretic model to examine whether and how an influencer’s organic product review affects a firm’s advertising and pricing strategies, profit, and consumer surplus. We find that in the presence of consumer search, the influencer’s organic content interacts with the firm’s strategies, suggesting new ways for a firm to manage the influencer’s seemingly independent content. Our results also show that the two types of information (influencer’s organic review and firm-created ad) can be complements or substitutes when the firm targets experts only and the cost of review production is low. Our findings complement the existing research on influencers and offer managerial implications for marketers and policymakers.Publication DEVELOPMENT AND CHARACTERIZATION OF DNA APTAMERS THAT TARGET GLUTEN PEPTIDES RESPONSIBLE FOR CELIAC DISEASE DEVELOPMENT(2013-08-22) ROOPSHA BRAHMA; BIOLOGICAL SCIENCES; KIM CHU-YOUNGCELIAC DISEASE IS TRIGGERED BY EXPOSURE TO WHEAT GLUTEN AND SIMILAR PROTEINS FOUND IN BARLEY AND RYE. WE SELECTED TWO SETS OF SINGLE STRAND DNA APTAMERS THAT TARGET THE IMMUNODOMINANT 33-MER GLUTEN EPITOPE AND INVESTIGATED THEIR ABILITY TO PREVENT GLUTEN-INDUCED AUTOIMMUNITY. THE FIRST SET OF APTAMERS, WHICH BIND TO THE NATIVE 33-MER GLUTEN PEPTIDE (LQLQPFPQPQLPYPQPQPLYPQPQLPYPQPQPF), INHIBITS TISSUE TRANSGLUTAMINASE-MEDIATED DEAMIDATION WHICH IS A NECESSARY STEP IN CELIAC DISEASE DEVELOPMENT. THE SECOND SET OF APTAMERS, WHICH BIND TO THE DEAMIDATED 33-MER GLUTEN PEPTIDE (LQLQPFPQPELPYPQPEPLYPQPELPYPQPQPF), HINDERS EPITOPE LOADING ONTO HLA-DQ2. THESE APTAMERS MAY SERVE AS A PREVENTIVE THERAPEUTIC FOR CELIAC DISEASE.Publication COMBUSTION AND EMISSIONS FORMATION IN DIESEL ENGINE FUELED BY POLYOXYMETHYLENE DIMETHYL ETHER AND ITS BLENDS(2021-05-07) LIN QINJIE; MECHANICAL ENGINEERING; Yang WenmingThe use of alternative oxygenated fuels is imperative for reducing harmful emissions, especially soot particles. Amongst the various oxygenates, polyoxymethylene dimethyl ether, or PODEn, has the highest potential largely due to its high oxygen content and cetane number. A highly compact and reliable PODE3 mechanism consisting of 61 species and 190 reactions has been developed based on decoupling methodology. The major reaction pathway of the PODE3 sub-mechanism, consists of only 11 species and 17 reactions. Another PODE3 mechanism consisting of 120 species and 560 reactions has also been developed for soot prediction. Furthermore, an engine experiment has been conducted using realistic PODE3/diesel blends to ascertain the characteristics of PODE3 combustion in a practical setting. It has been found that PODE3 addition generally leads to decrements in soot and the usage of PODE3 has minimal impact on fuel economy due to the high density of PODE3.Publication STUDY OF NOVEL LOW DIMENSIONAL MATERIALS SYNTHESIZED THROUGH CHEMICAL VAPOR DEPOSITION(2021-01-26) YAN JIAXIN; MATERIALS SCIENCE AND ENGINEERING; Chua Hock Chuan, DanielNovel low dimensional materials have been studied, including synthesis study and application study. Chemical Vapor Deposition, a versatile methodology, has been employed as the main synthesis methodology. Specifically, three groups of materials are the subjects of this comprehensive study. They are: the group of MoS2/MoO2 nanoflowers and nanoflakes, the group of WOx nanowires/nanoneedles, and the group of CuS nanoflakes. MoS2 and MoO2 were tested for their catalytic ability for hydrogen evolution reaction. It was found that MoO2 samples displayed the overall strongest catalytic ability, followed by a hybrid structure and then by MoS2. For WOx nanostructures, they were tested for their heat reflecting property and field emission property. It was found that samples deposited with W17O47 nanoneedles can function as good thermal shielding material due their ability to absorb and reflect NIR wavelength while permitting passage of the visible spectrum. Additionally, due to the metallic nature of W17O47, they can also function as viable field emitters. Lastly, CuS nanoflakes were tested for their ability as dye degradation catalysts. The results reveal that the nanoflakes can effectively decompose methylene blue dye under UV light illumination, resulting in around 55% reduction in characteristic absorption after 2 hours.Publication Three Essays on Macroeconomic Dynamics(2012-08-23) WAN JING; ECONOMICS; ZHANG JIEThe first chapter explores whether inflation taxation, a substitute for income taxation given fixed government spending, can mitigate business fluctuations, promote growth and enhance welfare by extending the Matsuyama model with endogenous growth through endogenous cycles to incorporate money in the utility function. Numerically, optimal money growth enhances welfare based on calibration. The second chapter determines the social optimal path in the innovation-cycle model of Matsuyama (1999, 2001) and explore whether inflation and taxation can be used to obtain the social optimum under a cash-in-advance constraint. The socially optimal path allows innovation to occur at a lower level of the capital-variety ratio than the equilibrium path. The third chapter extends one of the main findings in Bossmann et al. (2007). Bequest motives per se reduce wealth inequality. We show that the result holds for a stronger criterion of inequality comparison between distributions. Our Lorenz dominance result implies their result.Publication Thermosyphon flow for cooling of compact devices(2011-07-04) FILIAN ARBIYANI; MECHANICAL ENGINEERING; YAP, CHRISTOPHER ROBERT; NG KIM CHOONThe challenge of power dissipation in compact devices requires advanced cooling systems. In the present study, three novel cooling systems with essential attributes of compactness, low-cost, high cooling capacity, and orientation-free design are developed. A two-phase thermosyphon water-cooled condenser system was built and used in an experiment and numerical investigation of the effect of heat load on chip temperature. The effect of heat load on temperature difference between chip and inlet cooling water, and the heat load vs heat dissipation were also studied. A new designed of a helical-grooved heat pipe was then fabricated for an experimental study in obtaining the operating temperature as well as temperature distribution along the heat pipe axis for varying conditions, and the thermal resistance and overall heat transfer coefficient over a range of temperatures. Finally, a new design of a sintered heat pipe was fabricated for experiments to obtain a comparison with previous studies of a helical-grooved heat pipe.